U.S. patent application number 16/671391 was filed with the patent office on 2021-03-04 for electronic device including a protection circuit.
This patent application is currently assigned to Semiconductor Components Industries, LLC. The applicant listed for this patent is Semiconductor Components Industries, LLC. Invention is credited to Herbert De Vleeschouwer, Frederick Johan G. Declercq, Pierre Gassot, Woochul Jeon, Jaume Roig-Guitart, Piet Vanmeerbeek, Aarnout Wieers.
Application Number | 20210066285 16/671391 |
Document ID | / |
Family ID | 74680116 |
Filed Date | 2021-03-04 |
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United States Patent
Application |
20210066285 |
Kind Code |
A1 |
Roig-Guitart; Jaume ; et
al. |
March 4, 2021 |
Electronic Device Including a Protection Circuit
Abstract
An electronic device can include a source terminal, a gate
terminal, and a protection circuit. The protection circuit can
include a gate section including a first electrode and a second
electrode, wherein the first electrode of the gate section is
coupled to the gate terminal; and a source section including a
first electrode and a second electrode, wherein the first electrode
of the source section is coupled to the source terminal. The
protection switch can include a control electrode, a first
current-carrying electrode coupled to the gate terminal, and a
second current-carrying electrode coupled to the source terminal.
The second electrode of the gate section, the second electrode of
the source section, and the control electrode of the protection
switch can be coupled to one another. In an embodiment, the
electronic device can further include an electronic component that
is protected by the protection circuit.
Inventors: |
Roig-Guitart; Jaume;
(Oudenaarde, BE) ; De Vleeschouwer; Herbert;
(Zulte, BE) ; Gassot; Pierre; (Brussels, BE)
; Vanmeerbeek; Piet; (Sleidinge, BE) ; Declercq;
Frederick Johan G.; (Harelbeke, BE) ; Wieers;
Aarnout; (Vilvoorde, BE) ; Jeon; Woochul;
(Phoenix, AZ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Semiconductor Components Industries, LLC |
Phoenix |
AZ |
US |
|
|
Assignee: |
Semiconductor Components
Industries, LLC
Phoenix
AZ
|
Family ID: |
74680116 |
Appl. No.: |
16/671391 |
Filed: |
November 1, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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62895833 |
Sep 4, 2019 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 29/7787 20130101;
H01L 27/0288 20130101; H01L 29/404 20130101; H01L 29/41758
20130101; H01L 29/2003 20130101; H01L 27/0255 20130101; H01L
29/7786 20130101; H01L 27/0266 20130101; H01L 29/861 20130101 |
International
Class: |
H01L 27/02 20060101
H01L027/02; H01L 29/778 20060101 H01L029/778 |
Claims
1. An electronic device comprising: a source terminal; a gate
terminal; and a protection circuit comprising: a gate section
including a first electrode and a second electrode, wherein the
first electrode of the gate section is coupled to the gate
terminal; a source section including a first electrode and a second
electrode, wherein the first electrode of the source section is
coupled to the source terminal; and a protection switch including a
control electrode, a first current-carrying electrode coupled to
the gate terminal, and a second current-carrying electrode coupled
to the source terminal, wherein the second electrode of the gate
section, the second electrode of the source section, and the
control electrode of the protection switch are coupled to one
another.
2. The electronic device of claim 1, wherein: the gate section
includes a first diode having a cathode that is the second
electrode of the gate section, and the source section includes a
second diode having a cathode that is the second electrode of the
source section.
3. The electronic device of claim 2, wherein the cathode of the
first diode, the cathode of the second diode, and the control
electrode of the protection circuit are electrically connected at a
node.
4. The electronic device of claim 2, wherein: (1) the first diode
comprises a first gated diode including a drain electrode, a gate
electrode, and a source electrode, wherein the drain electrode of
the first gated diode and the gate electrode of the first gated
diode are coupled to each other, and the source electrode of the
first gated diode is coupled to the control electrode of the
protection switch, (2) the second diode comprises a second gated
diode including a drain electrode, a gate electrode, and a source
electrode, wherein the drain electrode of the second gated diode is
coupled to the control electrode of the protection switch, and the
gate electrode of the second gated diode and the source electrode
of the second gated diode are coupled to each other, or both (1)
and (2).
5. The electronic device of claim 4, wherein the protection switch
has protection switch active area width in a range of 10 mm to 20
mm, and: (1) the first gated diode has a first active area width
that is in a range from 0.1 mm to 1.0 mm, (2) the second gated
diode has a second active area width that is in a range from 0.1 mm
to 1.0 mm, or both (1) and (2).
6. The electronic device of claim 1, wherein: (1) the gate section
comprises: a first transistor including a drain electrode, a gate
electrode, and a source electrode; and a first diode including a
cathode and an anode, wherein: the drain electrode of the first
transistor, the anode of the first diode, and the gate terminal are
coupled to one another, the gate electrode of the first transistor
is coupled to the cathode of the first diode, and the drain
electrode of the first transistor is coupled to the control
electrode of the protection switch, (2) the source section
comprises: a second transistor including a drain electrode, a gate
electrode, and a source electrode; and a second diode including a
cathode and an anode, wherein: the drain electrode of the second
transistor is coupled to the control electrode of the protection
switch, the gate electrode of the second transistor is coupled to
the cathode of the second diode, and the source electrode of the
second transistor, the anode of the second diode, and the source
terminal are coupled to one another, or both (1) and (2).
7. The electronic device of claim 6, wherein the protection circuit
further comprises: (1) a first resistor having a first terminal
coupled to the gate electrode of the first transistor, and a second
terminal coupled to the control electrode of the protection switch;
(2) a second resistor having a first terminal coupled to the gate
electrode of the second component, and a second terminal coupled to
the control electrode of the protection switch; or both (1) and
(2).
8. The electronic device of claim 6, wherein the protection circuit
further comprises: (1) a third gated diode including a drain
electrode, a gate electrode, and a source electrode, wherein the
drain electrode of the third gated diode, the gate electrode of the
third gated diode, and the control electrode of the protection
switch are coupled to one another, and the source electrode of the
third gated diode is coupled to the source terminal, (2) a fourth
gated diode including a drain electrode, a gate electrode, and a
source electrode, wherein the drain electrode of the second gated
diode is coupled to the gate terminal, and the gate electrode of
the second gated diode, the source electrode of the second gated
diode, and the control electrode of the protection switch are
coupled to one another, or both (1) and (2).
9. The electronic device of claim 1, wherein the protection circuit
further comprises: (1) a first transistor including a drain
electrode, a gate electrode, and a source electrode, wherein: the
drain electrode of the first transistor, the gate electrode of the
first transistor, and the control electrode of the protection
switch are electrically connected at a first node, and the source
electrode of the first transistor and the source terminal are
electrically connected at a second node; (2) a second transistor
including a drain electrode, a gate electrode, and a source
electrode, wherein: the drain electrode of the second transistor
and the gate terminal are electrically connected at a third node;
and the gate electrode of the second transistor, the source
electrode of the second transistor, and the control electrode of
the protection switch are electrically connected at a fourth node,
or both (1) and (2).
10. The electronic device of claim 1, wherein the gate section and
the source section have a same number or different numbers of
electronic components.
11. The electronic device of claim 1, further comprising: a drain
terminal; and a power switch including a drain electrode coupled to
the drain terminal, a gate electro coupled to the gate terminal,
and a source electrode coupled to the source terminal.
12. The electronic device of claim 11, wherein the power switch has
a V.sub.TH, and the protection circuit is configured such that the
protection switch turns on when V.sub.GS is greater than
V.sub.TH.
13. The electronic device of claim 12, wherein the power switch has
a V.sub.GSMax, and the protection circuit is configured such that
the protection switch turns on before V.sub.GS reaches
V.sub.GSMax.
14. The electronic device of claim 12, wherein the power switch has
a V.sub.GSMin, and the protection switch turn on before V.sub.GS
reaches V.sub.GSMin.
15. The electronic device of claim 11, wherein the power switch
occupies at least 75% of an active area of the electronic device,
and the protection circuit occupies at most 25% of the active area
of the electronic device.
16. The electronic device of claim 11, wherein the power switch,
the protection switch, a first transistor structure within the gate
section, and a second transistor structure within the source
section has threshold voltages of the transistor structures are
within 20% of one another.
17. The electronic device of claim 11, wherein the power switch and
all transistor structures within the protection circuit are high
electron mobility transistors.
18. The electronic device of claim 11, wherein the power switch and
all transistor structures within the protection circuit are
enhancement-mode transistors.
19. The electronic device of claim 11, wherein from a top view,
wherein: the electronic device has a first peripheral side, a
second peripheral side, a third peripheral side, and a fourth
peripheral side, wherein the first peripheral side is opposite the
second peripheral side, the third peripheral side is opposite the
fourth peripheral sides, and the first and second peripheral sides
are perpendicular to the third and fourth peripheral sides, the
drain terminal is closer to the first peripheral side than the
second peripheral side, the source terminal is closer to the second
peripheral side than the first peripheral side, the power switch is
between the source terminal and the drain terminal and is closer to
the third peripheral side than to the fourth peripheral side, and
the protection circuit is between a gate runner and the first
peripheral side and is closer to the fourth peripheral side than to
the third peripheral side.
20. The electronic device of claim 19, wherein from the top view,
the drain terminal is disposed between the protection circuit and
the first peripheral terminal.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.
119(e) to U.S. Patent Application No. 62/895,833 entitled
"Electronic Device Including a Protection Circuit," by Roig-Guitart
et al., filed Sep. 4, 2019, which is assigned to the current
assignee hereof and incorporated herein by reference in its
entirety.
FIELD OF THE DISCLOSURE
[0002] The present disclosure relates to electronic devices, and
more particularly to, electronic devices that include protection
circuits.
RELATED ART
[0003] When transistors are turned on and off, transistors can
experience transient conditions that are not present when the
transistors are on or off for an extended period (at steady state).
Silicon-based transistors can withstand some transient conditions
due to the presence of diodes in the form of pn junctions within
the active region. Such pn junctions can occur at a drain-body
interface, a source-body interface, and the like. Unlike
silicon-based transistors, high electron mobility transistors do
not have pn junctions within the active region. Accordingly, a
transient, over-voltage or under-voltage condition for high
electron mobility transistors may need to use a protection circuit
to address such condition. Such a protection circuit may only allow
current flow in one direction through the protection circuit or
have relatively high current (i.e., significantly higher than
leakage current of a diode or a transistor) when the protection
circuit is in the on-state. Further improvements to address
transient, over-voltage, or over-current conditions are
desired.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] Embodiments are illustrated by way of example and are not
limited in the accompanying figures.
[0005] FIG. 1 includes a depiction of a schematic diagram of a
circuit in accordance with an embodiment.
[0006] FIG. 2 includes a depiction of a schematic diagram of a
circuit in accordance with a particular embodiment of FIG. 1.
[0007] FIG. 3 includes a depiction of a schematic diagram of a
circuit and cross-sectional views of portions of an electronic
device in accordance with a particular embodiment of FIG. 1.
[0008] FIG. 4 includes a depiction of a schematic diagram of a
circuit and cross-sectional views of portions of an electronic
device in accordance with another particular embodiment of FIG.
1.
[0009] FIG. 5 includes a depiction of a schematic diagram of a
circuit and cross-sectional views of portions of an electronic
device in accordance with another particular embodiment of FIG.
1.
[0010] FIG. 6 includes a depiction of a schematic diagram of a
protection circuit in accordance with an embodiment.
[0011] FIG. 7 includes a depiction of a schematic diagram of a
protection circuit in accordance with another embodiment.
[0012] FIG. 8 includes a plot of drain current for a protection
switch as a function of a voltage difference between gate and
source terminals of an electronic device.
[0013] FIG. 9 includes an illustration of a top view of a layout
for an electronic device that includes a power switch and a
protection circuit in accordance with an embodiment.
[0014] FIG. 10 includes an illustration of a top view of a layout
for an electronic device that includes a power switch and a
protection circuit in accordance with another embodiment.
[0015] FIG. 11 includes an illustration of a top view of a layout
for an electronic device that includes a power switch and a
protection circuit in accordance with a further embodiment.
[0016] FIG. 12 includes an illustration of a top view of a layout
for a protection circuit after forming conductive members for drain
and source electrodes in accordance with an embodiment.
[0017] FIG. 13 includes an illustration of a top view of the layout
for the protection circuit in FIG. 12 after forming conductive
members for gate electrodes and local interconnects.
[0018] FIG. 14 includes an illustration of a top view of a layout
for a protection circuit in FIG. 13 after forming a gate
interconnect and a source terminal.
[0019] FIG. 15 includes an illustration of a top view of a layout
for a protection circuit in accordance with another embodiment.
[0020] FIG. 16 includes an illustration of a top view of a layout
for a protection circuit in accordance with still another
embodiment.
[0021] FIG. 17 includes an illustration of a top view of a layout
for a protection circuit in accordance with yet another
embodiment.
[0022] FIG. 18 includes an illustration of a top view of a layout
for a protection circuit in accordance with a further
embodiment.
[0023] Skilled artisans appreciate that elements in the figures are
illustrated for simplicity and clarity and have not necessarily
been drawn to scale. For example, the dimensions of some of the
elements in the figures may be exaggerated relative to other
elements to help to improve understanding of embodiments of the
invention.
DETAILED DESCRIPTION
[0024] The following description in combination with the figures is
provided to assist in understanding the teachings disclosed herein.
The following discussion will focus on specific implementations and
embodiments of the teachings. This focus is provided to assist in
describing the teachings and should not be interpreted as a
limitation on the scope or applicability of the teachings. However,
other embodiments can be used based on the teachings as disclosed
in this application.
[0025] The term "coupling" and its variants are intended to mean
the transfer of electrical energy from one electronic component to
another. The term "electrically connected" and its variants refer
to a specific type of coupling where there is no intervening
circuit or electronic component. For example, two electronic
components are electrically connected to each other when there is
no circuit or a further electronic component along a current path
between the two components. Thus, with respect to an electrical
connection, electrodes or terminals of the two components are
electrically connected at a node and are at substantially the same
voltage.
[0026] The term "high voltage," with reference to a layer, a
structure, or a device, means that such layer, structure, or device
can withstand at least 50 V difference across such layer,
structure, or device (e.g., between a source electrode and a drain
electrode of a transistor when in an off-state) without exhibiting
dielectric breakdown, avalanche breakdown, or the like.
[0027] In a top view of an electronic device, a length of the gate
electrode within the active region is in a direction parallel to
current flow when in the on-state, and a width of the gate
electrode within the active region is perpendicular to the length
of the gate electrode. If a transistor structure includes more than
one gate electrode, the effective gate width is the sum of the
widths of each gate electrode for the transistor. For a transistor
structure with one gate electrode, the width of the gate electrode
is the same as the effective gate width. Any portion of the gate
electrode that extends outside the active region is not used in
calculating the width.
[0028] The terms "normal operation" and "normal operating state"
refer to conditions under which an electronic component or device
is designed to operate. The conditions may be obtained from a data
sheet or other information regarding voltages, currents,
capacitances, resistances, or other electrical parameters. Thus,
normal operation does not include operating an electrical component
or device well beyond its design limits.
[0029] The term "steady state" is intended to mean a state in which
parameters do not change or may change insignificantly over a
relatively time period, such as a second or longer. The term
"transient state" is intended to mean a state in which one or more
parameters significantly change over a relatively short time
period, such as less than second, and can be less than 0.1 s. For
example, an electrostatic discharge event or immediately after
turning a transistor or other switch on or off may render one or
more devices to go from steady state to a transient state.
[0030] The term "V.sub.GS" refers to the voltage between a gate
terminal and a source terminal of a circuit, where the gate and
source terminals provide electrical connections from outside the
circuit.
[0031] Group numbers correspond to columns within the Periodic
Table of Elements based on the IUPAC Periodic Table of Elements,
version dated Nov. 28, 2016.
[0032] For clarity of the drawings, certain regions of device
structures, such as doped regions or dielectric regions, may be
illustrated as having generally straight-line edges and precise
angular corners. However, those skilled in the art understand that,
due to the diffusion and activation of dopants or formation of
layers, the edges of such regions generally may not be straight
lines and that the corners may not be precise angles.
[0033] The terms "on," "overlying," and "over" may be used to
indicate that two or more elements are in direct physical contact
with each other. Unlike "on", "overlying" and "over" may also mean
that two or more elements are not in direct contact with each
other. For example, "over" may mean that one element is above
another element, but the elements do not contact each other and may
have another element or elements in between the two elements.
[0034] The terms "comprises," "comprising," "includes,"
"including," "has," "having" or any other variation thereof, are
intended to cover a non-exclusive inclusion. For example, a method,
article, or apparatus that comprises a list of features is not
necessarily limited only to those features but may include other
features not explicitly listed or inherent to such method, article,
or apparatus. Further, unless explicitly stated to the contrary,
"or" refers to an inclusive-or and not to an exclusive-or. For
example, a condition A or B is satisfied by any one of the
following: A is true (or present) and B is false (or not present),
A is false (or not present) and B is true (or present), and both A
and B are true (or present).
[0035] Also, the use of "a" or "an" is employed to describe
elements and components described herein. This is done merely for
convenience and to give a general sense of the scope of the
invention. This description should be read to include one, at least
one, or the singular as also including the plural, or vice versa,
unless it is clear that it is meant otherwise. For example, when a
single item is described herein, more than one item may be used in
place of a single item. Similarly, where more than one item is
described herein, a single item may be substituted for that more
than one item.
[0036] The use of the word "about," "approximately," or
"substantially" is intended to mean that a value of a parameter is
close to a stated value or position. However, minor differences may
prevent the values or positions from being exactly as stated. Thus,
differences of up to ten percent (10%) (and up to twenty percent
(20%) for semiconductor doping concentrations) for the value are
reasonable differences from the ideal goal of exactly as
described.
[0037] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this invention belongs. The
materials, methods, and examples are illustrative only and not
intended to be limiting. To the extent not described herein, many
details regarding specific materials and processing acts are
conventional and may be found in textbooks and other sources within
the semiconductor and electronic arts.
[0038] An electronic device can include a protection circuit that
includes a protection switch and one or more electronic components
that are coupled to a control electrode of the power switch. The
protection circuit can be used in conjunction with another
component, such as a power switch, within the electronic circuit.
When the protection switch is on, substantially all of the current
flowing through the protection circuit flows through the protection
switch. Thus, the other electronic component(s) within the
protection circuit can be significantly smaller than the protection
switch.
[0039] The protection circuit can be designed to allow
bidirectional current flow, so that the protection circuit can turn
on with a positive or negative voltage outside the normal operating
range for an electronic device. Thus, during normal operation of
the electronic device, no significant current flows through the
protection circuit. The protection circuit can help to dissipate
charge from an electrostatic event or other similar condition that
may cause the voltage difference between terminals of an electronic
device to become too high or too low. The protection circuit can be
tailored to allow particular voltages to turn on the protection
circuit before the voltage difference between the terminals reaches
a point where the voltage difference would cause damage to a
component to be protected by the protection circuit, such as a
power switch, within the electronic device.
[0040] In an embodiment, the protection circuit does not require a
resistor electrically connected to the control electrode of the
protection switch and one of the terminals for the protection
circuit. However, one or more resistors may be used internally
within the protection circuit. Many different layouts may be used,
and thus, a designer may use a particular layout that meets the
needs to desires for a particular application. The protection
circuit is well suited to protect a high electron mobility
transistor (HEMT) or another transistor that is not a Si-based
transistor. In an embodiment, the protection circuit can be
implemented without adding any processing steps.
[0041] In an aspect, an electronic device can include a source
terminal, a gate terminal, and a protection circuit. The protection
circuit can include a gate section including a first electrode and
a second electrode, wherein the first electrode of the gate section
is coupled to the gate terminal; a source section including a first
electrode and a second electrode, wherein the first electrode of
the source section is coupled to the source terminal; and a
protection switch including a control electrode, a first
current-carrying electrode coupled to the gate terminal, and a
second current-carrying electrode coupled to the source terminal.
The second electrode of the gate section, the second electrode of
the source section, and the control electrode of the protection
switch can be coupled to one another.
[0042] FIG. 1 includes a depiction of a circuit diagram for an
electronic device 100 that includes a power switch 122 and a
protection circuit 140. A current-carrying electrode of the power
switch 122 is coupled to a drain terminal 102, a control terminal
of the power switch 122 is coupled to a gate terminal 104, and
another current-carrying electrode of the power switch 122 is
coupled to a source terminal 106. In the embodiment as illustrated,
the power switch 122 is a transistor, where the drain electrode of
the transistor is coupled to the drain terminal 102, the gate
electrode of the transistor is coupled to the gate terminal 104,
and the source electrode of the transistor is coupled to the source
terminal 106. During normal operation, the power switch 122 can be
turned on by applying a sufficient V.sub.GS for the circuit 100
higher than the threshold voltage (V.sub.TH) of the power switch
122, and current flows from the drain terminal 102 to the source
terminal 106 through the power switch 122. No significant current
flows through the protection circuit 140 during normal operation of
the electronic device 100, regardless whether the power switch 122
is in the on-state or off-state.
[0043] In a particular embodiment, the power switch 122 does not
have any doped regions, and hence, electrostatic discharge
structures or components that can be used with Si-based devices,
may not be available with the electronic device 100. In a
particular embodiment, the power switch 122 is a HEMT.
[0044] The protection circuit 140 helps to reduce the likelihood
that the power switch 122 will become damaged when V.sub.GS becomes
too high or too low. The power switch 122 may have a maximum
recommended V.sub.GS, V.sub.GSMax, and a minimum recommended
V.sub.GS, V.sub.GSMin, that the power switch 122 can withstand
before the power switch 122 is damaged. Thus, V.sub.GS should not
be higher than V.sub.GSMax and should not be lower than
V.sub.GSMin. The absolute values for V.sub.GSMax and V.sub.GSMin
may be the same or different. For example, in an embodiment,
V.sub.GSMax may be 7.5 V, and V.sub.GSMin may be -7.5 V, and in
another embodiment, V.sub.GSMax may be 7.5 V, and V.sub.GSMin may
be -10.0 V. Therefore, the protection circuit 140 can be designed
to turn on and flow current between the gate and source terminals
104 and 106 when V.sub.GS is significantly greater than V.sub.TH of
the power switch 122 and before V.sub.GS reaches V.sub.GSMax or
V.sub.GSMin of the power switch 122.
[0045] In the embodiment as illustrated in FIG. 1, the protection
circuit 140 includes a protection switch 142, a gate section 144,
and a source section 146. When V.sub.GS is sufficiently higher than
V.sub.TH of the power switch 122 (referred to herein as a
forward-bias condition), the gate section 144 can provide a voltage
sufficient to turn on the protection switch 142 before V.sub.GS
reaches V.sub.GSMax. The source section 146 can be designed to
prevent significant current flow through the gate section 144 to a
source node 206. When V.sub.GS is sufficiently less than 0 V
(referred to herein as a reverse-bias condition), the source
section 146 can provide a voltage sufficient to turn on the
protection switch 142 before V.sub.GS reaches V.sub.GSMin. The gate
section 144 can be designed to prevent significant current flow
through the source section 146 to a gate node 204.
[0046] In an embodiment, the protection switch 142 can be a
transistor with a pair of current-carrying electrodes and the
control electrode. A current-carrying electrode of the transistor
142 closer to the gate node 204 can be a drain electrode during the
forward-bias condition and a source electrode during a reverse-bias
condition. Thus, such current-carrying electrode will be referred
to as a D/S electrode. Another current-carrying electrode of the
transistor 142 closer to the source node 206 can be a source
electrode during the forward-bias condition and a drain electrode
during a reverse-bias condition. Thus, such current-carrying
electrode will also be referred to as a S/D electrode. As
illustrated in embodiment of FIG. 1, the D/S electrode of the
protection switch 142 is coupled to the gate terminal 104, the S/D
electrode of the protection switch 142 is coupled to the source
terminal 106.
[0047] One or more components are within each of the gate section
144 and the source section 146. The number of components within the
gate section 144 and the source section 146 can be the same or
different. The gate section 144 has an electrode coupled to the
gate terminal 104 and another electrode coupled to the control
electrode of the protection switch 142. The source section 146 has
an electrode coupled to the control electrode of the protection
switch 142 and another electrode coupled to the source terminal
106. In a particular embodiment, the gate terminal 104, the D/S
electrode of the protection switch 142, and one of the electrodes
of the gate section 144 are electrically connected to one another
at the gate node 204; the other electrode of the gate section 144,
the control electrode of the protection switch 142, and one of the
electrodes of source section 146 are electrically connected to one
another at a node 222; and the other electrode of the source
section 146, the S/D electrode of the protection switch 142, and
the source terminal 106 are electrically connected to one another
at the source node 206.
[0048] FIG. 2 includes an embodiment of the protection circuit 140
in which the gate section 144 includes a set of diodes and the
source section 146 includes another set of diodes. The gate section
144 can have the same number or a different number of diodes as
compared to the source section 146. In another embodiment, each of
the gate section 144 and the source section 146 can have less than
three diodes. In the embodiment as illustrated in FIG. 2, the gate
section 144 can include diode 242, 244, and 24x. The source section
146 can include diode 262, 264, and 26y.
[0049] Referring to gate section 144, an anode of the diode 242 is
coupled to the gate node 204 and the D/S electrode of the
protection switch 142, a cathode of the diode 242 is coupled to an
anode of the diode 244, a cathode of the diode 244 is coupled to an
anode of the diode 24x, and a cathode of the diode 24x is coupled
to the node 222. Referring to source section 146, a cathode of the
diode 26y is coupled to the node 222, an anode of the diode 26y is
coupled to a cathode of the diode 264, an anode of the diode 264 is
coupled to a cathode of the diode 262, and an anode of the diode
262 is coupled to the source node 206. During forward biasing of
the protection circuit 140, the diodes within the gate section 144
can provide a voltage that turns on the protection switch 142, and
the diodes within the source section 146 do not allow a significant
current to flow through the source section 146. During reverse
biasing of the protection circuit 140, the diodes within the source
section 146 can provide a voltage that turns on the protection
switch 142, and the diodes within the gate section 144 do not allow
a significant current to flow through the gate section 144. Thus,
excess charge can be dissipated through the protection switch 142.
The protection circuit 140 is designed so that current does not
flow through both the gate section 144 and the source section 146
at the same time.
[0050] FIG. 3 includes a circuit diagram for a particular
embodiment of the protection circuit 140 and cross-sectional views
of exemplary, non-limiting electronic components within the
electronic device. The cross-sectional views illustrate how
physical structures can be used to achieve the electronic device
100. The cross-sectional view near the right-hand side of FIG. 3
illustrates an exemplary power switch 122 that can be used with the
protection circuit 140.
[0051] In this embodiment, gated diodes in FIG. 3 are used for the
diodes as illustrated in FIG. 2. For the gate section 144, each of
gated diodes 342, 344, and 346 has its drain and gate electrodes
electrically connected to each other. For the source section 146,
each of gated diodes 362, 364, and 366 has its source and gate
electrodes electrically connected to each other. Referring to the
gate section 144, the drain and gate electrodes of the gated diode
342 and the D/S electrode of the protection switch 142 are coupled
to each other, the source electrode of the gated diode 342 is
coupled to the drain and gate electrodes of the gated diode 344,
the source electrode of the gated diode 344 is coupled to the drain
and gate electrodes of the gated diode 346, and the source
electrode of the gated diode 346 is coupled to the node 222.
Referring to the source section 146, the drain electrode of the
gated diode 366 is coupled to the node 222, the gate and source
electrodes of the gated diode 366 are coupled to the drain
electrode of the gated diode 364, the gate and source electrodes of
the gated diode 364 are coupled to the drain electrode of the gated
diode 362, and the gate and source electrodes of the gated diode
362 are coupled to the S/D electrode of the protection switch
142.
[0052] In a particular embodiment, the couplings can be in the form
of electrical connections. For example, the drain and gate
electrodes of the gated diode 342, the D/S electrode of the
protection switch 142, and the gate terminal 104 can be
electrically connected to one another at the gate node 204; the
source electrode of the gated diode 346, the drain electrode of the
gated diode 366, and the control electrode of the protection switch
142 can be electrically connected to one another at the node 222;
and the gate and source electrode of the gated diode 362, the S/D
electrode of the protection switch 142, and the source terminal 106
can be electrically connected to one another at the source node
206.
[0053] In the embodiment as illustrated in FIG. 3, all of the
transistor structures can be HEMTs. The power switch 122 and the
protection switch 142 are configured to act as transistors, and the
other transistor structures are configured to act as diodes, and
specifically, are the gated diodes 342, 344, 346, 362, 364, and
366. The power switch 122 can occupy at least 75% or at least 80%
of the active area of the electronic device. The protection circuit
140 can occupy at most 25% or at most 20% of the active area of the
electronic device. In an embodiment, the power switch 122 may
occupy at most 90% of the active area of the electronic device, and
the protection circuit 140 may occupy at least 10% of the active
area of the electronic device. The areal coverage described in this
paragraph is intended to be illustrative, and therefore, the
percentages for the active areas may be less than or greater that
those described.
[0054] The different sizes of transistor structures are drawn in
FIGS. 3 to 5 to illustrate the relative size of the transistor
structures. Skilled artisans will appreciate that the thicknesses
of the substrate and its overlying layers are the same for the
transistor structures in FIGS. 3 to 5. Thus, after reading this
specification, skilled artisans will appreciate that the different
sizes reflect different areas (as seen from a top view) of the
transistor structures. The power switch 122 is substantially larger
than the transistor structures within the protection circuit 140.
In an embodiment, the effective gate width for the protection
switch 142 can be in a range of 10% to 20% of the effective gate
width of the power switch 122. In another embodiment, the effective
gate width of the transistor structure for each of the gated diodes
342, 344, 346, 362, 364, and 366 is in a range from 0.1% of 1.0% of
the effective gate width of the power switch 122. In a further
embodiment, the effective gate width of transistor structures
within the protection circuit 140 may be outside the ranges given.
Actual values for the effective gate widths can depend on how much
current is to flow through the power switch 122 and the protection
switch 142.
[0055] The layers used in forming the transistors structures
illustrated in FIG. 3 can be the same or nearly the same. While the
description below is for HEMT structures, the concepts herein can
be applied to other transistor structures that do not have diodes
formed between a channel region and either or both of doped source
and doped drain regions, such as with Si-based transistor
technology. Below are some layers and materials that can be used
for the transistor structures.
[0056] The transistor structures as illustrated in FIG. 3 can
include a substrate 410, a nucleation layer 420, a buffer layer
422, a channel layer 424, and a barrier layer 426. The substrate
410 can include silicon, sapphire (monocrystalline
Al.sub.2O.sub.3), silicon carbide (SiC), aluminum nitride (AlN),
gallium oxide (Ga.sub.2O.sub.3), spinel (MgAl.sub.2O.sub.4),
another suitable substantially monocrystalline material, or the
like. In an embodiment, the substrate 410 can be a monocrystalline
Si wafer or a monocrystalline III-V wafer. The particular material
and crystal orientation along the primary surface can be selected
depending upon the composition of the overlying layers. In an
embodiment, the substrate 410 for all of the transistor structures
illustrated in FIG. 3 is electrically connected to the source
terminal 106.
[0057] Each of the nucleation layer 420, the buffer layer 422, the
channel layer 424, and the barrier layer 426 can include a III-N
material, and in a particular embodiment, include
Al.sub.xGa.sub.(1-x)N, where 0.ltoreq.x.ltoreq.1. In an embodiment,
the nucleation layer 420 can help with the transition from the
crystal matrix in the substrate 410 to the crystal matrix of
overlying layers. In a particular embodiment, the nucleation layer
420 includes AlN. The composition of the buffer layer 422 may
depend on the composition of the channel layer 424. The composition
of the buffer layer 422 can be changed as a function of thickness,
such that the buffer layer 422 has a relatively greater aluminum
content closer to the substrate 410 and relatively greater gallium
content closer to the channel layer 424. In a particular
embodiment, the cation (metal atoms) content in the buffer layer
422 near the substrate 410 can be 10 atomic % to 100 atomic % Al
with the remainder Ga, and the cation content in the buffer layer
422 near the channel layer 424 can be 0 atomic % to 50 atomic % Al
with the remainder Ga. The buffer layer 422 can have a thickness in
a range of approximately 1 micron to 5 microns.
[0058] The channel layer 424 can include Al.sub.yGa.sub.(1-y)N,
where 0.ltoreq.y.ltoreq.0.1 and have a thickness in a range of
approximately 20 nm to 4000 nm. The channel and barrier layers 424
and 426 can form a heterojunction in which a two-dimensional
electron gas (2DEG) can be formed. In an embodiment, the barrier
layer 426 includes a III-V material. In a particular embodiment,
the barrier layer 426 can include Al.sub.zGa.sub.(1-z)N, wherein
0.02.ltoreq.z.ltoreq.0.5, and in a further embodiment
0.11.ltoreq.z.ltoreq.0.3. The barrier layer 426 can have a higher
Al content as compared to the channel layer 424. The barrier layer
426 can have a thickness in a range of approximately 2 nm to 40 nm.
In another embodiment, the barrier layer 426 can have a thickness
of at least 6 nm to ensure better that the barrier layer 426 is
continuous over the channel layer 424. In another embodiment, the
barrier layer 426 may have a thickness of at most 25 nm to keep
on-state resistance relatively low.
[0059] Each of the channel layer 424 and the barrier layer 426 may
be undoped or unintentionally doped. Unintentional doping may occur
due to reactions involving the precursors during formation of the
layers 424 and 426. In an embodiment, acceptors can include carbon
from a source gas (e.g., Ga(CH.sub.3).sub.3) when metalorganic
chemical vapor deposition (MOCVD) is used to form the channel and
barrier layers 424 and 426. Thus, some carbon can become
incorporated as the layers 424 and 426 are grown, and such carbon
can result in unintentional doping. The carbon content may be
controlled by controlling the deposition conditions, such as the
deposition temperature and flow rates. In an embodiment, each of
the channel and barrier layers 424 and 426 has a carrier impurity
concentration that is greater than 0 and less than
1.times.10.sup.14 atoms/cm.sup.3 or less than 1.times.10.sup.15
atoms/cm.sup.3 and in another embodiment, at most 1.times.10.sup.16
atoms/cm.sup.3. In a further embodiment, the carrier impurity
concentration with unintentional doping is in a range from
1.times.10.sup.13 atoms/cm.sup.3 to 1.times.10.sup.16
atoms/cm.sup.3.
[0060] The layers overlying the substrate 410 can be formed using
an epitaxial growth technique, and thus the channel layer 424 and
barrier layer 426, and at least a portion of the buffer layer 422
can be monocrystalline. In a particular embodiment, the layers
overlying the substrate 410 can be formed using metalorganic
chemical vapor deposition. In another embodiment, different
composition for the nucleation layer 420 may be used, e.g.,
InAlGaN, InP, or the like.
[0061] In a particular embodiment, the power switch 122, the
protection switch 142, and the transistor structures of the gated
diodes 342, 344, 346, 362, 364, and 366 can be enhancement-mode
transistors. The gate structures can include gate electrodes that
include a p-type semiconductor material and can have the same
semiconductor material as the channel layer 424. For example, the
gate electrodes and channel layer 424 can include GaN, although the
gate electrodes will have a higher dopant concentration as compared
to the channel layer 424. In another embodiment, the gate
structures can include a gate dielectric layer and gate electrodes
that include a metal or a metal alloy. Each of the gate dielectric
layer and the gate electrodes can include one or more films. The
metal or metal alloy gate electrodes are described in more detail
with respect to the drain and source electrodes.
[0062] One or more interconnect levels can be formed, where each
interconnect level includes a patterned interlevel dielectric (ILD)
layer and a patterned conductive layer. As illustrated in FIG. 3,
the power switch 122 may have five interconnect levels, and the
transistor structures within the protection circuit 140 may have
three interconnect levels. The power switch 122 has more
interconnect levels to allow field plates to be formed that control
electrical fields during normal operation of the power switch 122.
The power switch 122 can be a power transistor and, in an
embodiment, have a voltage rating in a range from 50 V to 650 V. In
another embodiment, the voltage rating may be higher or lower than
values previously described. The voltages to which the transistor
structures in the protection circuit 140 may be exposed are smaller
because the protection circuit 140 is coupled to the gate and
source terminals 104 and 106 and is not electrically connected to
the drain terminal 102. Thus, the transistor structures in the
protection circuit 140 do not need field plates to be as complex as
field plates for the power switch 122.
[0063] Each ILD layer can be formed over the barrier layer 426 and
include a single film or a plurality of films. The single film or
each of the films can include an oxide, a nitride, or an
oxynitride. Each ILD layer can have a thickness in a range from 20
nm to 500 nm. Each conductive layer is formed over its
corresponding ILD layer. The conductive layer can include a single
film or a plurality of films. In an embodiment, the conductive
layer can include an adhesion film and a barrier film. Such films
may include Ta, TaSi, Ti, TiW, TiSi, TiN, or the like. The
conductive layer can further include a conductive bulk film. The
bulk film can include Al, Cu, or another material that is more
conductive than other films within the conductive layer. In an
embodiment, the bulk film can include at least 90 wt. % Al or Cu.
The bulk film can have a thickness that is at least as thick as the
other films within the conductive layer. In an embodiment, the bulk
film has a thickness in a range from 20 nm to 900 nm and, in a more
particular embodiment, in a range from 50 nm to 500 nm. More or
fewer films can be used in each ILD layer or each conductive
layer.
[0064] In the embodiment as illustrated in FIG. 3, the power switch
122 includes a drain structure 1222, a gate structure 1224, and a
source structure 1226. The protection switch 142 includes a D/S
structure 1422, a gate structure 1424, and a S/D structure 1426.
Each of the transistor structures for the gated diodes 342, 344,
346, 362, 364, and 366 includes a source structure, a gate
structure, and a drain structure. Each of the drain, gate, source,
D/S, and S/D structures includes one or more of the patterned
conductive layers, and within each structure (e.g., a drain
structure, a source structure, etc.), the portion of the patterned
conductive layer closest to the channel layer 424 is the electrode
(e.g., a drain electrode, a source electrode, etc.) for its
corresponding structure. All of the drain, gate, source, D/S, and
S/D structures include field plates, although field plates may not
be used within the protection circuit 140 in an alternative
embodiment. In the figures, the insulating layer 460 is the
composite of the patterned ILD layers.
[0065] FIG. 4 includes cross-sectional views of portions of the
workpiece in accordance with an alternative embodiment. Two
additional transistors are added to the protection circuit 140.
Although the protection circuit 140 has more components, the
overall size of the protection circuit may be smaller because the
gated diodes can be smaller. The gate section of the protection
circuit 140 includes a transistor 552 and gated diodes 542, 544,
and 546, and the source section of the portion circuit 140 includes
a transistor 572 and gated diodes 562, 564, and 566.
[0066] The transistor 552 includes a drain electrode coupled to the
gate terminal 104, and a source electrode coupled to the control
electrode of the protection switch 142. The transistor 572 includes
a drain electrode coupled to the control electrode of the
protection switch 142, and a source electrode coupled to the source
terminal 106. In an embodiment, the control electrode of the
protection switch 142, the source electrode of the transistor 552,
and the drain electrode of the transistor 572 are electrically
connected to one another at a node 522.
[0067] The gated diodes 542, 544, and 546 have all of the couplings
and electrical connections as previously described with respect to
the gated diodes 342, 344, and 346, except that the source
electrode of the gated diode 546 is coupled to the gate electrode
of the transistor 552. The gated diodes 562, 564, and 566 have all
of the couplings and electrical connections as previously described
with respect to the gated diodes 362, 364, and 366, except that the
drain electrode of the gated diode 566 is coupled to the gate
electrode of the transistor 572.
[0068] FIG. 5 includes another embodiment that is similar to the
embodiment as illustrated and described with respect to FIG. 4. In
FIG. 5, resistors 642 and 662 are coupled between their
corresponding set of gated diodes and a node 622. The resistors 642
and 662 help to make stable the circuit protection operation in
stationary state by providing an additional current path for
leakage or off-state current. The resistors 642 and 644 may have a
value in the high kiloohms to several hundreds of megaohms. In an
embodiment, a terminal of the resistor 642 is coupled to the source
electrode of the gated diode 546 and the gate electrode of the
transistor 552, and the other terminal of resistor 642 is coupled
to the control electrode of the protection switch 142. A terminal
of the resistor 662 is coupled to the drain electrode of the gated
diode 566 and the gate electrode of the transistor 572, and the
other terminal of resistor 662 is coupled to the control electrode
of the protection switch 142. In a particular embodiment, one of
the terminals of the resistor 642, one of the terminals of the
resistor 662, the source electrode of the transistor 562, the drain
electrode of the transistor 572, and the control electrode of the
protection switch 142 are electrically connected to one another at
a node 622.
[0069] In the embodiments as illustrated in FIGS. 2 to 5, when the
protection circuit 140 is at steady state, and the gate-to-source
current is relatively high (>0.01 mA/mm), the V.sub.TH for the
protection circuit 140 in the forward-bias direction will be the
sum of the V.sub.THs of each of the protection switch 142 and all
of the transistor structures between the gate node and the control
electrode of the protection switch 142. Referring to FIGS. 2 and 3,
the V.sub.TH for the protection circuit 140 in the forward-bias
direction will be the sum of the V.sub.THs of the gated diodes 342,
344, 346 and the protection switch 142. The V.sub.TH for the
protection circuit 140 in the reverse-bias direction will be the
negative sum of the V.sub.THs of each of the protection switch 142
and all of the transistor structures between the source node and
the control electrode of the protection switch 142. Referring to
FIGS. 2 and 3, the V.sub.TH for the protection circuit 140 in the
reverse-bias direction will be the negative sum of the V.sub.THs of
the gated diodes 362, 364, 366 and the protection switch 142. When
the protection circuit 140 is at steady state, and the
gate-to-source current is relatively low (<0.01 mA/mm), the
voltage at node 222 is close to zero and the protection circuit is
not activated. When the protection circuit 140 is in a transient
state, the voltage in node 222 is mainly governed by the capacitive
divider between gate section 144 and source section 146. When the
voltage at the node 222 is at least V.sub.TH for the protection
switch 142, the protection circuit 140 turns on.
[0070] In an embodiment, the power switch 122 and each of the
transistor structures within the protection circuit 140 can be
designed to have substantially the same V.sub.TH. Thus, the
protection circuit 140 may have a V.sub.TH that is substantially an
integer multiple of the V.sub.TH. For example, the power switch 122
may have a V.sub.TH of approximately 1.5 V. Each of the gated
diodes 342, 344, 346, 362, 364, 366 and the protection switch 142
may have V.sub.THs of approximately 1.5 V. With such a design,
V.sub.TH of the protection circuit 140 can have a V.sub.TH of
approximately 6.0 V in the forward-bias direction and a V.sub.TH of
approximately -6.0 V in the reverse-bias direction. In another
embodiment, any one or more of the transistor structures within the
protection circuit 140 can have a V.sub.TH that is significantly
different from the V.sub.TH of the power switch 122 or another
transistor structure within the protection circuit 140.
[0071] FIG. 6 includes a protection circuit 740 that is similar to
the protection circuit 140 in FIG. 3. The embodiment illustrated in
FIG. 6 includes gated diodes 742 and 762 in the protection circuit
740. The gated diodes 742 and d762 can enable circuit protection in
a steady state for HEMTs with relatively low gate current source.
These gated diodes allow a current path that is less resistive than
current path through gate-to-source in the protection switch 142.
This should allow building a voltage greater than 0 V at the node
222. In FIG. 6, a forward-bias current path (illustrated with
arrows 752) includes the gated diodes 342, 344, 346, and 742, and a
reverse-bias current path (illustrated with arrows 772) includes
the gated diodes 362, 364, 366, and 762. The gated diodes 742 and
762 can help to form voltage dividers for the forward-bias and
reverse-bias current paths. Each of the gated diodes 742 and 762
may have a V.sub.TH that can be the same, lower, or higher than the
V.sub.TH of the protection switch 142. The gated diodes 342, 344,
346, and 742 lie along a forward-bias current path, and the gated
diodes 362, 364, 366, and 762 lie along a reverse-bias current
path. When forward biased, the voltage at the node 722 will be:
V.sub.722=V.sub.GS.times.(R.sub.DG742/(RDG.sub.342+R.sub.DG344+R.sub.DG3-
46+R.sub.DG742)), where:
[0072] V.sub.722 is the voltage at the node 722, and
[0073] R.sub.DGxxx is the resistance through the gated diode xxx
when gated diode xxx is in its on-state.
[0074] When reversed biased, the voltage at the node 722 will
be:
V.sub.722=V.sub.GS.times.(R.sub.DG762/(RDG.sub.362+R.sub.DG364+R.sub.DG3-
66+R.sub.DG762)).
[0075] The gated diode 742 includes a drain electrode and a gate
electrode coupled to the electrode of the protection switch 142,
and a source electrode coupled to the source terminal 106. The
gated diode 762 includes a drain electrode coupled to the gate
terminal 104, and a gate electrode and a source electrode coupled
to the control electrode of the protection switch 142. In a
particular embodiment, the gate electrode and source electrode of
the gated diode 762, the source electrode of the gated diode 346,
the drain electrode and the gate electrode of the gated diode 742,
the drain electrode of the gated diode 366, and the control
electrode of the protection switch 142 are electrically connected
to one another at the node 722. FIG. 6 also includes a gate node
704 and a source node 706 that serve the same purposes of the gate
node 204 and source node 206 (in FIG. 3), respectively.
[0076] FIG. 7 includes a protection circuit 840 that is similar to
the protection circuit 140 in FIG. 4 and further includes gated
diodes 842 and 862 that are similar to gated diodes 742 and 762,
respectively in FIG. 6. The gated diode 842 includes a drain
electrode and a gate electrode coupled to the control electrode of
the protection switch 142, and a source electrode coupled to the
source terminal 106. The gated diode 862 includes a drain electrode
coupled to the gate terminal 104, and gate and source electrodes
coupled to the control electrode of the protection switch 142. In a
particular embodiment, the source electrode of the transistor 552,
the drain electrode and gate electrode of the gated diode 842, the
gate electrode and the source electrode of the gated diode 862, the
drain electrode of the transistor 572, and the control electrode of
the protection switch 142 are electrically connected to one another
at a node 822. FIG. 7 also includes a gate node 804 and a source
node 806 that serve the same purposes of the gate node 204 and
source node 206 (in FIG. 3), respectively.
[0077] The previously described circuits can be used to allow the
protection circuit 140 to turn on when V.sub.GS significantly
deviates from V.sub.GS during normal operation of the electronic
device. Such a situation may occur during an electrostatic
discharge event or other similar over-voltage or under-voltage
event. For example, the electronic device may have V.sub.GS of 0 V
when the power switch 122 is in an off-state and 5V when the power
switch 122 is in an on-state. When turning on and off the power
switch 122, V.sub.GS may be in a range from -2 V to 5.5 V in the
normal operating state, due to voltage overshoot. Thus, the
protection circuit 140 may be designed so that the protection
switch 142 does not turn on when V.sub.GS is in a range from -2 V
to 5.5 V. In a particular embodiment, the protection circuit 140
can turn on when the V.sub.GS is significantly higher than 5.5 V
and when V.sub.GS is significantly lower than -2 V.
[0078] FIG. 8 includes a plot of drain current (I.sub.DS) of the
protection switch 142 as a function of the V.sub.GS in accordance
with an embodiment. The axes of I.sub.DS and V.sub.GS intersect at
0 A and 0 V. When Vgs is at and close to 0 V, there is no
significant current flow through the protection switch 142. When
V.sub.GS becomes sufficiently high, such as approximately 6 V to
approximately 8 V, the protection switch 142 turns on and current
flows from the gate terminal 104, through the protection switch
142, and to the source terminal 106. Unlike many conventional
circuits, the protection circuit 140 allows current to flow in the
reverse direction, too. When V.sub.GS becomes sufficiently low,
such as approximately -6 V to approximately -8 V, the protection
switch 142 turns on and current flows from the source terminal 106,
through the protection switch 142, and to the gate terminal 104.
Thus, the protection circuit 140 allows for bidirectional current
flow and may not turn on during normal operation of the electronic
device.
[0079] The embodiment corresponding to FIG. 8 illustrates the
protection circuit 140 having a symmetric operation, that is, the
|V.sub.TH| for the forward-bias condition is substantially the same
as |V.sub.TH| for the reverse-bias condition. In another
embodiment, the |V.sub.TH| for forward biasing and |V.sub.TH| for
reverse biasing may be significantly different. For example, the
power switch 122 may be able to withstand a V.sub.GS as high as +8
V or as low as -12 V before a significant risk of damage to the
power switch 122 may occur. The protection circuit 140 may be
designed so that the protection switch 142 turns on in the
forward-bias direction when V.sub.GS is 6 V or higher and turn on
in the reverse-bias direction when V.sub.GS is -9 V or lower.
[0080] Many different layouts can be used with the circuits as
previously described. Some exemplary, non-limiting embodiments are
provided to demonstrate that a particular physical design may be
selected based on the needs or desire for a particular application.
The designs are described with respect to the electronic device in
FIG. 3. After reading this specification in its entirety, skilled
artisans will be able to adjust the designs for electronic
embodiments illustrated and described with respect to the other
protection circuits described in FIGS. 4 to 7.
[0081] FIG. 9 includes a top view of the electronic device to
provide a better understanding of the locations and sizes of the
power switch 122 and the protection circuit 140. The electronic
device has a peripheral side 982 near the top of FIG. 9, a
peripheral side 984 opposite and substantially parallel to the
peripheral side 982, a peripheral side 986 near the left-hand side
of FIG. 9, and a peripheral side 988 opposite and substantially
parallel to the peripheral side 986. The sides 982 and 984 are
substantially perpendicular to the sides 986 and 988. The
peripheral side 986 is closer to the power switch 122 than to the
protection circuit 140, and the peripheral side 988 is closer to
the protection circuit 140 than to the power switch 122. The active
region of the power switch 122 is between the drain and source
terminals 102 and 106. The active regions of the transistor
structures within the protection circuit 140 are between the drain
terminal 102 and a gate runner 944.
[0082] The power switch 122 includes drain electrodes 922
electrically connected to the drain terminal 102, gate electrodes
924 electrically connected to the gate terminals 104 via the gate
runner 944, and source electrodes 926 electrically connected to the
source terminal 106. Referring to FIGS. 3 and 9, a portion of the
source terminal 106 extends over the protection circuit 140 and
makes electrical connections to S/D electrodes of the protection
switch 142 and the source electrode of the gated diode 362. A gate
interconnect 946 extends over the protection circuit 140 and makes
electrical connections to D/S electrodes of the protection switch
142, the drain electrode of the gated diode 342, and the gate
runner 944. Details regarding particular layouts of the protection
circuit 140 and the electrical connections are provided later in
this specification.
[0083] FIG. 10 includes a layout of an alternative embodiment. In
the embodiment as illustrated in FIG. 10, the gate terminal 104 is
pulled away from the peripheral side 988, and the protection
circuit 140 is extended toward the peripheral side 982. The layout
may allow the protection switch 142 to dissipate charge faster than
the embodiment illustrated in FIG. 9. Thus, the layout in FIG. 10
may allow more current to flow through the power switch 122. FIG.
11 is similar to FIG. 10; however, the left-hand side gate terminal
104 (in FIG. 10) is removed. The right-hand side gate terminal 104
is retained.
[0084] FIGS. 12 to 14 include top views of the protection circuit
140 in accordance with an embodiment. FIGS. 12 to 14 are described
with respect to the components are illustrated and described with
respect to FIG. 3. FIG. 12 includes an illustration after
conductive members are formed that correspond to drain and source
electrodes for the transistor structures. In particular, conductive
members 1222 are D/S electrodes for the protection switch 142, and
conductive members 1226 are S/D electrodes for the protection
switch 142.
[0085] Referring to FIGS. 3 and 12, conductive members 1242, 1244,
1246, and 1248 are associated with the gate section of the
protection circuit 140. In particular, the conductive member 1242
is the drain electrode for the gated diode 342, the conductive
member 1244 is the source electrode of the gated diode 342 and the
drain of the gated diode 344, the conductive member 1246 is the
source electrode of the gated diode 344 and the drain of the gated
diode 346, and the conductive member 1248 is the source electrode
of the gated diode 346.
[0086] Referring to FIGS. 3 and 12, conductive members 1262, 1264,
1266, and 1268 are associated with the source section of the
protection circuit 140. In particular, the conductive member 1262
is the source electrode for the gated diode 362, the conductive
member 1264 is the drain electrode of the gated diode 362 and the
source of the gated diode 364, the conductive member 1266 is the
drain electrode of the gated diode 364 and the source of the gated
diode 366, and the conductive member 1268 is the drain electrode of
the gated diode 366.
[0087] FIG. 13 includes an illustration after conductive members
are formed that correspond to gate electrodes for the transistor
structures and interconnects to other parts of the protection
circuit 140. In particular, conductive member 1324 includes gate
electrode portions between the conductive members 1222 and 1226,
where gate electrode portions are gate electrodes for the
protection switch 142. Another portion of the conductive member
1324 is a local interconnect that connects the gate electrode
portions to one another and to the conductive members 1248 and 1268
that are the source of the gated diode 346 and the drain of the
gated diode 366, respectively.
[0088] Referring to FIGS. 3 and 13, conductive members 1342, 1344,
and 1346 are associated with the gate section of the protection
circuit 140. In particular, the conductive member 1342 is the gate
electrode for the gated diode 342 and contacts the conductive
member 1242, the conductive member 1344 is the gate electrode for
the gated diode 344 and contacts the conductive member 1244, and
the conductive member 1346 is the gate electrode for the gated
diode 346 and contacts the conductive member 1246.
[0089] Referring to FIGS. 3 and 13, conductive members 1362, 1364,
and 1366 are associated with the source section of the protection
circuit 140. In particular, the conductive member 1362 is the gate
electrode for the gated diode 362 and contacts the conductive
member 1262, the conductive member 1364 is the gate electrode for
the gated diode 364 and contacts the conductive member 1264, and
the conductive member 1366 is the gate electrode for the gated
diode 366 and contacts the conductive member 1266.
[0090] FIG. 14 includes an illustration after an ILD layer has been
formed and patterned to define contact openings and subsequently
forming the source terminal 106 and the gate interconnect 946.
Contacts between the source terminal 106 and some of its underlying
conductive members and between the gate interconnect 946 and some
of its underlying conductive members are illustrated with dots. In
the embodiment as illustrated, the gate interconnect 946 contacts
the conductive members 1222 (D/S electrodes of the protection
switch 142) and the conductive member 1242 (the drain electrode of
the gated diode 342). The source terminal 106 contacts the
conductive members 1226 (S/D electrodes of the protection switch
142) and the conductive member 1262 (the source electrode of the
gated diode 362).
[0091] On a relative basis (as compared to alternative layouts
addressed below), the layout in FIG. 14 is the simplest to
implement. In the layout as illustrated in FIG. 14, portions of the
conductive members are the drain electrodes, D/S electrodes, source
electrodes, S/D electrode, and gate electrodes within the
protection circuit 140 that are substantially parallel to the
drain, gate, and source electrodes 922, 924, and 926 for the power
switch 122. In FIGS. 14 to 18, contacts between the between the
source terminal 106 and of some its underlying components and
between the gate interconnect 946 and some of its underlying
comp
[0092] FIGS. 15 to 18 illustrate alternative embodiments of the
layout of the protection circuit 140. Each are more complicated on
a relative basis as compared to FIG. 14; however, each may provide
a difference in performance as compared to the layout illustrated
in FIG. 14. FIG. 15 has the same conductive members as described
with respect to FIGS. 12 and 13. The source terminal 106 and the
gate interconnect 946 have different shapes that may allow for
lower resistance in a current path through the protection circuit
140.
[0093] FIGS. 16 to 18 include alternative embodiments in which the
layout is changed. The electrical characteristics in HEMTs
sometimes exhibit dependence with layout orientation. Hence,
layouts in FIGS. 16, 17 and 18 allow different layout orientations
in the protection circuit devices and protected device. This could
allow adjustments to different V.sub.TH values in order to obtain a
higher optimization for the protection circuit.
[0094] FIG. 16 includes a layout where portions of the conductive
members are the drain electrodes, D/S electrodes, source
electrodes, S/D electrode, and gate electrodes within the
protection circuit 140 that are substantially perpendicular to the
drain, gate, and source electrodes 922, 924, and 926 (FIGS. 9 to
11) for the power switch 122. Such a layout can simplify the shape
of the gate interconnect 946. FIG. 17 includes a layout where the
conductive members are the D/S electrodes, S/D electrode, and gate
electrodes within the protection switch 142 that are substantially
perpendicular to the conductive members for the drain, gate, and
source electrodes of the gated diodes within the protection
circuit. FIG. 18 combines advantages seen in the previously
described layouts and includes a more complicated layout for the
gated diodes within the protection circuit 140. As compared to FIG.
17, the layout in FIG. 18 can allow more active area for the
protection switch 142 and less active area for the gated diodes.
The current flowing through the protection circuit 140 can be
larger for the layout of FIG. 18 as compared to FIG. 17.
[0095] After reading this application in its entirety, skilled
artisans will appreciate that many other layouts of the electronic
device are possible. The layouts can be tailored to meet the needs
or desires for a particular application. Accordingly, the layouts
as illustrated and described are to be considered exemplary.
[0096] A protection circuit can include a protection switch and
other electronic components that are coupled to a control electrode
of the protection switch. When the protection switch is on,
substantially all of the current flowing through the protection
circuit flows through the protection switch. Thus, the other
electronic components can be significantly smaller than the
protection switch.
[0097] The protection circuit can be designed to allow
bidirectional current flow, so that the protection circuit can turn
on with a positive or negative voltage outside the normal operating
range for an electronic device. The protection circuit can help
with dissipating charge from an electrostatic event or other
over-voltage or under-voltage event that may cause the voltage
difference between terminals of an electronic device to become too
high or too low. In an embodiment, the protection circuit does not
require a resistor electrically connected to the control electrode
of the protection switch and one of the terminals for the
protection circuit. In particular embodiment, the protection
circuits as described herein may be used; however, a diode or a
transistor can be used between such an internal resistor and either
of the gate terminal 104 or the source terminal 106. The protection
circuit can be tailored to allow particular voltages to turn on the
protection circuit. Many different layouts may be used, and thus, a
designer may determine a particular layout that meets the needs to
desires for a particular application.
[0098] The protection circuit is well suited to protect a HEMT or
another transistor that is not a Si-based transistor. The
protection circuit can be implemented for a wide range of power
ratings (drain terminal-to-source terminal voltage) for electronic
devices, for example, from 50 V to 650 V or higher. In an
embodiment, the protection circuit can be implemented without
adding any processing steps.
[0099] Many different aspects and embodiments are possible. Some of
those aspects and embodiments are described below. After reading
this specification, skilled artisans will appreciate that those
aspects and embodiments are only illustrative and do not limit the
scope of the present invention. Embodiments may be in accordance
with any one or more of the embodiments as listed below.
[0100] Embodiment 1. An electronic device can include a source
terminal, a gate terminal, and a protection circuit. The protection
circuit can include a gate section including a first electrode and
a second electrode, wherein the first electrode of the gate section
is coupled to the gate terminal; a source section including a first
electrode and a second electrode, wherein the first electrode of
the source section is coupled to the source terminal; and a
protection switch including a control electrode, a first
current-carrying electrode coupled to the gate terminal, and a
second current-carrying electrode coupled to the source terminal.
The second electrode of the gate section, the second electrode of
the source section, and the control electrode of the protection
switch can be coupled to one another.
[0101] Embodiment 2. The electronic device of Embodiment 1, wherein
the gate section includes a first diode having a cathode that is
the second electrode of the gate section, and the source section
includes a second diode having a cathode that is the second
electrode of the source section.
[0102] Embodiment 3. The electronic device of Embodiment 2, wherein
the cathode of the first diode, the cathode of the second diode,
and the control electrode of the protection circuit are
electrically connected at a node.
[0103] Embodiment 4. The electronic device of Embodiment 2,
wherein: [0104] (1) the first diode includes a first gated diode
including a drain electrode, a gate electrode, and a source
electrode, wherein the drain electrode of the first gated diode and
the gate electrode of the first gated diode are coupled to each
other, and the source electrode of the first gated diode is coupled
to the control electrode of the protection switch, [0105] (2) the
second diode includes a second gated diode including a drain
electrode, a gate electrode, and a source electrode, wherein the
drain electrode of the second gated diode is coupled to the control
electrode of the protection switch, and the gate electrode of the
second gated diode and the source electrode of the second gated
diode are coupled to each other, or [0106] both (1) and (2).
[0107] Embodiment 5. The electronic device of Embodiment 4, wherein
the protection switch has protection switch active area width in a
range of 10 mm to 20 mm, and: [0108] (1) the first gated diode has
a first active area width that is in a range from 0.1 mm to 1.0 mm,
[0109] (2) the second gated diode has a second active area width
that is in a range from 0.1 mm to 1.0 mm, or [0110] both (1) and
(2).
[0111] Embodiment 6. The electronic device of Embodiment 1,
wherein: [0112] (1) the gate section includes a first transistor
including a drain electrode, a gate electrode, and a source
electrode; and a first diode including a cathode and an anode,
wherein the drain electrode of the first transistor, the anode of
the first diode, and the gate terminal are coupled to one another,
the gate electrode of the first transistor is coupled to the
cathode of the first diode, and the drain electrode of the first
transistor is coupled to the control electrode of the protection
switch, [0113] (2) the source section includes a second transistor
including a drain electrode, a gate electrode, and a source
electrode; and a second diode including a cathode and an anode,
wherein the drain electrode of the second transistor is coupled to
the control electrode of the protection switch, the gate electrode
of the second transistor is coupled to the cathode of the second
diode, and the source electrode of the second transistor, the anode
of the second diode, and the source terminal are coupled to one
another, or [0114] both (1) and (2).
[0115] Embodiment 7. The electronic device of Embodiment 6, wherein
the protection circuit further includes: [0116] (1) a first
resistor having a first terminal coupled to the gate electrode of
the first transistor, and a second terminal coupled to the control
electrode of the protection switch; [0117] (2) a second resistor
having a first terminal coupled to the gate electrode of the second
component, and a second terminal coupled to the control electrode
of the protection switch; or [0118] both (1) and (2).
[0119] 8. The electronic device of Embodiment 6, wherein the
protection circuit further comprises: [0120] (1) a third gated
diode including a drain electrode, a gate electrode, and a source
electrode, wherein the drain electrode of the third gated diode,
the gate electrode of the third gated diode, and the control
electrode of the protection switch are coupled to one another, and
the source electrode of the third gated diode is coupled to the
source terminal, [0121] (2) a fourth gated diode including a drain
electrode, a gate electrode, and a source electrode, wherein the
drain electrode of the second gated diode is coupled to the gate
terminal, and the gate electrode of the second gated diode, the
source electrode of the second gated diode, and the control
electrode of the protection switch are coupled to one another, or
[0122] both (1) and (2).
[0123] Embodiment 9. The electronic device of Embodiment 1, wherein
the protection circuit further includes: [0124] (1) a first
transistor including a drain electrode, a gate electrode, and a
source electrode, wherein the drain electrode of the first
transistor, the gate electrode of the first transistor, and the
control electrode of the protection switch are electrically
connected at a first node, and the source electrode of the first
transistor and the source terminal are electrically connected at a
second node; [0125] (2) a second transistor including a drain
electrode, a gate electrode, and a source electrode, wherein the
drain electrode of the second transistor and the gate terminal are
electrically connected at a third node; and the gate electrode of
the second transistor, the source electrode of the second
transistor, and the control electrode of the protection switch are
electrically connected at a fourth node, or [0126] both (1) and
(2).
[0127] Embodiment 10. The electronic device of Embodiment 1,
wherein the gate section and the source section have a same number
of electronic components.
[0128] Embodiment 11. The electronic device of Embodiment 1,
wherein the gate section and the source section have different
numbers of electronic components.
[0129] Embodiment 12. The electronic device of Embodiment 1 further
includes a drain terminal; and a power switch including a drain
electrode coupled to the drain terminal, a gate electro coupled to
the gate terminal, and a source electrode coupled to the source
terminal.
[0130] Embodiment 13. The electronic device of Embodiment 12,
wherein the power switch has a V.sub.TH, and the protection circuit
is configured such that the protection switch turns on when
V.sub.GS is greater than V.sub.TH.
[0131] Embodiment 14. The electronic device of Embodiment 13,
wherein the power switch has a V.sub.GSMax, and the protection
circuit is configured such that the protection switch turns on
before V.sub.GS reaches V.sub.GSMax.
[0132] Embodiment 15. The electronic device of Embodiment 13,
wherein the power switch has a V.sub.GSMin, and the protection
switch turn on before V.sub.GS reaches V.sub.GSMin.
[0133] Embodiment 16. The electronic device of Embodiment 12,
wherein the power switch occupies at least 75% of an active area of
the electronic device, and the protection circuit occupies at most
25% of the active area of the electronic device.
[0134] Embodiment 17. The electronic device of Embodiment 12,
wherein the power switch, the protection switch, a first transistor
structure within the gate section, and a second transistor
structure within the source section has threshold voltages of the
transistor structures are within 20% of one another.
[0135] Embodiment 18. The electronic device of Embodiment 12,
wherein the power switch and all transistor structures within the
protection circuit are high electron mobility transistors.
[0136] Embodiment 19. The electronic device of Embodiment 12,
wherein the power switch and all transistor structures within the
protection circuit are enhancement-mode transistors.
[0137] Embodiment 20. The electronic device of Embodiment 12,
wherein from a top view, wherein: [0138] the electronic device has
a first peripheral side, a second peripheral side, a third
peripheral side, and a fourth peripheral side, wherein the first
peripheral side is opposite the second peripheral side, the third
peripheral side is opposite the fourth peripheral sides, and the
first and second peripheral sides are perpendicular to the third
and fourth peripheral sides, [0139] the drain terminal is closer to
the first peripheral side than the second peripheral side, [0140]
the source terminal is closer to the second peripheral side than
the first peripheral side, [0141] the power switch is between the
source terminal and the drain terminal and is closer to the third
peripheral side than to the fourth peripheral side, and [0142] the
protection circuit is between a gate runner and the first
peripheral side and is closer to the fourth peripheral side than to
the third peripheral side.
[0143] Embodiment 21. The electronic device of Embodiment 20,
wherein from the top view, the drain terminal is disposed between
the protection circuit and the first peripheral terminal.
[0144] Note that not all of the activities described above in the
general description or the examples are required, that a portion of
a specific activity may not be required, and that one or more
further activities may be performed in addition to those described.
Still further, the order in which activities are listed is not
necessarily the order in which they are performed.
[0145] Benefits, other advantages, and solutions to problems have
been described above with regard to specific embodiments. However,
the benefits, advantages, solutions to problems, and any feature(s)
that may cause any benefit, advantage, or solution to occur or
become more pronounced are not to be construed as a critical,
required, or essential feature of any or all the claims.
[0146] The specification and illustrations of the embodiments
described herein are intended to provide a general understanding of
the structure of the various embodiments. The specification and
illustrations are not intended to serve as an exhaustive and
comprehensive description of all of the elements and features of
apparatus and systems that use the structures or methods described
herein. Separate embodiments may also be provided in combination in
a single embodiment, and conversely, various features that are, for
brevity, described in the context of a single embodiment, may also
be provided separately or in any subcombination. Further, reference
to values stated in ranges includes each and every value within
that range. Many other embodiments may be apparent to skilled
artisans only after reading this specification. Other embodiments
may be used and derived from the disclosure, such that a structural
substitution, logical substitution, or another change may be made
without departing from the scope of the disclosure. Accordingly,
the disclosure is to be regarded as illustrative rather than
restrictive.
* * * * *