U.S. patent application number 11/282830 was filed with the patent office on 2006-05-18 for self-cooled vertical electronic component.
This patent application is currently assigned to STMicroelectronics S.A.. Invention is credited to Jean-Luc Morand.
Application Number | 20060101829 11/282830 |
Document ID | / |
Family ID | 34952384 |
Filed Date | 2006-05-18 |
United States Patent
Application |
20060101829 |
Kind Code |
A1 |
Morand; Jean-Luc |
May 18, 2006 |
Self-cooled vertical electronic component
Abstract
A self-cooled electronic component comprising a vertical
monolithic circuit, in which the vertical monolithic circuit is
electrically connected in series with a Peltier cooler so that the
D.C. current flowing through the circuit supplies the cooler and in
which the circuit and the cooler are placed against each other so
that the cold surface of the cooler is in thermal contact with the
circuit.
Inventors: |
Morand; Jean-Luc; (Tours,
FR) |
Correspondence
Address: |
STMicroelectronics Inc.;c/o WOLF, GREENFIELD & SACKS, PC
Federal Reserve Plaza
600 Atlantic Avenue
BOSTON
MA
02210-2206
US
|
Assignee: |
STMicroelectronics S.A.
Montrouge
FR
|
Family ID: |
34952384 |
Appl. No.: |
11/282830 |
Filed: |
November 18, 2005 |
Current U.S.
Class: |
62/3.2 ;
257/E23.082; 62/259.2 |
Current CPC
Class: |
H01L 2924/00 20130101;
H01L 2924/0002 20130101; H01L 35/32 20130101; H01L 23/38 20130101;
H01L 2924/0002 20130101 |
Class at
Publication: |
062/003.2 ;
062/259.2 |
International
Class: |
F25B 21/02 20060101
F25B021/02; F25D 23/12 20060101 F25D023/12 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 18, 2004 |
FR |
04/52671 |
Claims
1. A self-cooled electronic component comprising a vertical
monolithic circuit electrically connected in series with a Peltier
cooler so that a D.C. current flowing through the circuit supplies
the cooler and wherein the circuit and the cooler are placed
against each other so that the cold surface of the cooler is in
thermal contact with the circuit, wherein the cooler comprises an
odd number of concentric regions of a thermoelectric semiconductor
material, of alternate conductivity types, laterally isolated, and
electrically connected in series, a surface of a central region
corresponding to a first terminal, and an opposite surface of an
external region corresponding to a second terminal.
2. The self-cooled electronic component of claim 1, wherein the
cooler comprises three concentric regions: a central region of a
first conductivity type; a ring-shaped region of a second
conductivity type extending around the central region and
electrically and thermally laterally isolated from the central
region; and a peripheral region of the first conductivity type
extending around the ring-shaped region and electrically and
thermally laterally isolated from the ring-shaped region; the
central, ring-shaped, and peripheral regions being of same depth;
the central and ring-shaped regions being thermally and
electrically interconnected by a central metal plate on a first hot
or cold surface of the cooler; and the ring-shaped and peripheral
regions being thermally and electrically interconnected by a
ring-shaped metal plate on a second cold or hot surface of the
cooler.
3. The self-cooled electronic component of claim 2, wherein the
central region is integral with a first current input/output
metallization; and wherein the peripheral region is integral with a
second current input/output metallization, the first and second
current input/output metallizations being formed on opposite
surfaces of the cooler and being thermally and electrically
isolated from the neighboring metal plate of interconnection of the
central region to the ring-shaped region or of the ring-shaped
region to the peripheral region.
4. The self-cooled electronic component of claim 3, wherein the
surface areas of the central, ring-shaped, and peripheral regions
are equal.
5. The self-cooled electronic component of claim 3, wherein the
current coming from the circuit enters the cooler through the first
metallization and comes out through the second metallization, the
first conductivity type being type P and the second conductivity
type being type N.
6. The self-cooled electronic component of claim 3, wherein a
full-plate metallization extends over the entire surface of the
system comprising the metal plate of interconnection of the central
region to the ring-shaped region, and is electrically isolated form
said metal interconnection plate.
7. A Peltier cooler adapted to the cooling of a circuit, comprising
an odd number of concentric regions of alternate conductive types
of a thermoelectric semiconductor material, these regions being
laterally isolated and electrically connected in series, a surface
of the central region corresponding to a first terminal, and an
opposite surface of the external region corresponding to a second
terminal.
8. The Peltier cooler of claim 7, comprising: a central region of a
first conductivity type adapted to being placed against at least a
portion of a main surface of the one-way component; a ring-shaped
region of a second conductivity type extending around the central
region and being laterally electrically and thermally isolated from
the central region; and a peripheral region of the first
conductivity type extending around the ring-shaped region and being
electrically and thermally laterally isolated from the ring-shaped
region; the central, ring-shaped, and peripheral regions being of
same depth; the central and ring-shaped regions being thermally and
electrically interconnected by a central metal plate on a first hot
or cold surface of the cooler; and the ring-shaped and peripheral
regions being thermally and electrically interconnected by a
ring-shaped metal plate on a second cold or hot surface of the
cooler.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to the cooling of electronic
components. More specifically, the present invention relates to the
cooling of a vertical monolithic circuit capable of conducting a
one-way current entering or coming out through its rear
surface.
[0003] 2. Discussion of the Related Art
[0004] In monolithic electronic components or circuits, it is
necessary to carry off the heat generated during operation. In
particular, for semiconductor components with a junction, it is
necessary to avoid changes in the temperature of the active
junctions to guarantee stable operation characteristics.
[0005] FIG. 1 is a simplified cross-section view of a vertical
electronic component 1 made in monolithic form in a semiconductor
substrate, or vertical monolithic circuit. Component 1 comprises a
metallization 5 on a rear surface. A current flows through the
component from one or several metallizations (not shown) formed on
the front surface towards rear surface metallization 5. To cool
down the component, metallization 5 is thermally connected to an
element for carrying off the heat or heat sink 7. Metallization 5
is generally electrically isolated from heat sink 7 by a thermally
conductive element, generally a ceramic plate, a resin layer, or an
isolating film 9.
[0006] The carrying off of the heat of heat sink 7 is performed by
natural heat convection or by an airflow generated by a ventilator
(not shown).
[0007] To improve the heat carrying-off, a heat pipe area of small
dimensions, formed of an area comprising cavities in which a
cooling fluid can flow, is sometimes formed in component 1.
[0008] In spite of this, for high-voltage one-way components such
as diodes, transistors, or thyristors intended to operate at high
powers on the order of several tens of watts or more, malfunctions
can be observed. Such malfunctions are imputed to a drift in the
characteristics (switching thresholds) as a result of a repeated
heating of a component junction or area.
[0009] Further, Peltier coolers, which enable cooling heat sources,
are known. Such coolers are, for example, formed of elementary
cells comprising thermoelectric elements of two opposite
conductivity types N and P.
[0010] FIG. 2 is a partial simplified cross-section view of the
structure of a Peltier effect cell 10 on which is arranged a load
to be cooled down.
[0011] Cell 10 comprises a first N-type doped thermoelectric
element 11 and a second P-type doped thermoelectric element 12.
First and second thermoelectric elements 11 and 12 are, for
example, made of bismuth telluride (Bi.sub.2Te.sub.3). Element 11
is selenium-doped (type N) while element 12 is doped with antimony
(type P). Elements 11 and 12 are electrically connected in series
and thermally connected in parallel. For this purpose, elements 11
and 12 are laterally isolated, electrically and thermally. Their
front surfaces are connected to a same conductive wafer 14. The
rear surface of element 11 is integral with a metal plate 17 and
the rear surface of element 12 is integral with a metal plate 18.
Plate 17 is connected to a current input terminal A. Wafer 18 is
connected to a current output terminal B. At its front surface, a
thermally conductive and electrically isolating plate 20 forms a
tray on which a load to be cooled down can be laid. At its rear
surface, a thermally conductive and electrically isolating plate 22
thermally connects metallizations 17 and 18 to a heat sink 23.
[0012] In operation, a voltage such that cell 10 conducts a current
entering through terminal A and coming out through terminal B, that
is, running from N-type element 11 to P-type element 12, is applied
between terminals A and B of cell 10. The current flow direction is
indicated by arrows in FIG. 2. Then, plate 14 becomes a cold source
at a temperature on the order of -10.degree. C. for a current on
the order of one ampere, while heat sink 23 becomes a hot source at
a temperature from 30 to 50.degree. C.
[0013] Peltier coolers seem extremely attractive and exhibit at
first sight many advantages with respect to conventional heat
dissipation systems but have not found many practical applications
except, possibly, to cool down devices under confined or dangerous
atmosphere. One of their disadvantages is that they require an
autonomous current source capable of providing a high current.
SUMMARY OF THE INVENTION
[0014] The present invention aims at using such coolers in a manner
adapted to the cooling of a vertical monolithic circuit.
[0015] The present invention also aims at providing a system
capable of self-adapting to the thermal power to be dissipated.
[0016] Generally, the present invention provides placing against a
vertical monolithic circuit a Peltier cooler so that the cold
surface of the cooler is in thermal contact with the circuit and
that the D.C. current flowing through the circuit also forms the
current generating the Peltier effect. The assembly thus formed is
a self-cooled electronic component.
[0017] According to an embodiment of the present invention, the
cooler comprises an odd number of concentric regions of a
thermoelectric semiconductor material, of alternate conductivity
types, laterally isolated, and electrically connected in series, a
surface of the central region corresponding to a first terminal,
and an opposite surface of the external region corresponding to a
second terminal.
[0018] According to an embodiment of the present invention, the
cooler comprises three concentric regions: a central region of a
first conductivity type; a ring-shaped region of a second
conductivity type extending around the central region and being
laterally electrically and thermally isolated from the central
region; and a peripheral region of the first conductivity type
extending around the ring-shaped region and being electrically and
thermally laterally isolated from the ring-shaped region; the
central, ring-shaped, and peripheral regions being of the same
depth; the central and ring-shaped regions being thermally and
electrically interconnected by a central metal plate on a first hot
or cold surface of the cooler; and the ring-shaped and peripheral
regions being thermally and electrically interconnected by a
ring-shaped metal plate on a second cold or hot surface of the
cooler.
[0019] According to an embodiment of the present invention, the
central region is integral with a first current input/output
metallization; and the peripheral region is integral with a second
current input/output metallization, the first and second current
input/output metallizations being formed on opposite surfaces of
the cooler and being thermally and electrically isolated from the
neighboring metal plate of interconnection of the central region to
the ring-shaped region or of the ring-shaped region to the
peripheral region.
[0020] According to an embodiment of the present invention, the
surface areas of the central, ring-shaped, and peripheral regions
are equal.
[0021] According to an embodiment of the present invention, the
current coming from the circuit enters the cooler through the first
metallization and comes out through the second metallization, the
first conductivity type being type P and the second conductivity
type being type N.
[0022] According to an embodiment of the present invention, a
full-plate metallization extends over the entire surface of the
system comprising the metal plate of interconnection of the central
region to the ring-shaped region, and is electrically isolated form
said interconnection metal plate.
[0023] The foregoing and other objects, features, and advantages of
the present invention will be discussed in detail in the following
non-limiting description of specific embodiments in connection with
the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 illustrates, in a partial simplified cross-section
view, a vertical monolithic component associated with a heat
carry-off heat sink;
[0025] FIG. 2 illustrates, in a partial simplified cross-section
view, a conventional Peltier cooler;
[0026] FIG. 3 illustrates, in partial simplified cross-section
view, a system for cooling a vertical monolithic circuit according
to an embodiment of the present invention;
[0027] FIG. 4 is a partial simplified top view of an internal
portion of the structure of FIG. 3 observed in plane A-A; and
[0028] FIG. 5 is a simplified view of a self-cooled electronic
component according to the present invention.
DETAILED DESCRIPTION
[0029] For clarity, the same elements have been designated with the
same reference numerals in the different drawings and, further, as
usual in the representation of integrated circuits, the various
drawings are not drawn to scale.
[0030] FIG. 3 is a partial simplified cross-section view of a
cooling system according to an embodiment of the present
invention.
[0031] The rear surface of a monolithic, vertical, one-way
electronic component 30 comprises a current output metallization
31.
[0032] Metallization 31 rests on a planar surface having a central
conductive portion 40 in electric and thermal contact with a region
51 of a cell of a Peltier cooler 50. According to an aspect of the
present invention, central portion 40 is a metal plate.
[0033] As also illustrated by the top view of FIG. 4, seen in plane
A-A of FIG. 3, the Peltier cooler comprises a central P-type region
51, a ring-shaped N-type region 52 extending around central region
51, and a peripheral P-type region 54 extending around ring-shaped
region 52. Central region 51, ring-shaped region 52, and peripheral
region 54 are semiconductor regions of a thermoelectric
semiconductor substrate. The upper and lower surfaces of central
region 51, ring-shaped region 52, and peripheral region 54 are
coplanar. Central region 51 is laterally thermally and electrically
isolated from ring-shaped region 52 by an isolation wall 56.
Ring-shaped region 52 is laterally thermally and electrically
isolated from peripheral region 54 by an isolation wall 57.
[0034] Central region 51, ring-shaped region 52, and peripheral
region 54 are electrically connected in series and thermally
connected in parallel two-by-two, as described hereafter in
relation with FIG. 3.
[0035] Central region 51 is electrically and thermally connected to
ring-shaped region 52 by a conductive plate 42. Plate 42 is
opposite to plate 40 of connection to metallization 31 of component
30, for example, at the rear surface.
[0036] At the front surface, a ring-shaped plate 44 electrically
and thermally connects ring-shaped region 52 and peripheral region
54. Ring-shaped plate 44 extends around central plate 40 and is
electrically and thermally isolated therefrom by isolation wall 56.
Ring-shaped plate 44 is electrically isolated but thermally coupled
to metallization 31 of component 30 by an isolation element 60, for
example, made of ceramics. The upper surface of isolating element
60 is coplanar with the upper surface of central plate 40.
[0037] At the rear surface, peripheral region 54 is connected via
an electrically and thermally conductive ring-shaped plate 46 to a
rear surface metallization 48 of the cooling system. Plate 46
extends around plate 42. Isolation wall 57 laterally isolates plate
42 from ring-shaped plate 46 thermally and electrically. An element
62 electrically isolates plate 42 from metallization 48. Element
62, however, enables a thermal conduction between rear central
portion 42 and metallization 48. The dimensions of plates 42 and 46
and of element 62 are selected so that the front surface of
metallization 48 in contact with plate 46 and element 62 is planar.
The rear surface of metallization 48 may be connected to a heat
sink.
[0038] According to an embodiment of the present invention, rear
metallization 31 of component 30, front metal plate 40, rear plate
42, front ring-shaped plate 44, and rear ring-shaped 46 are made of
copper or of a copper-based alloy.
[0039] According to an embodiment of the present invention, the
individual surfaces of each of central region 51, ring-shaped
region 52, and peripheral region 54 of the Peltier cooler are
substantially equal. The values of these individual surfaces as
well as the thickness of the above-mentioned regions will be
selected, as will appear from what follows, according to the D.C.
current that flows through component 30.
[0040] According to an embodiment to the present invention, thermal
and electric isolation walls 56 and 57 are thick isolators, for
example, on the order of a few tens of .mu.m. Thermally conductive
electric isolators 60, 62, and 64 are thin isolators, for example,
on the order of a few hundreds of .mu.m.
[0041] According to an embodiment of the present invention, central
region 51, ring-shaped region 52, and peripheral region 54 are
formed in a bismuth telluride substrate, ring-shaped region 52
being a region doped with selenium and central region 52 and
peripheral region 54 being doped with antimony.
[0042] When vertical monolithic circuit 30 operates, a current
comes out of its rear surface metallization 31. The current
penetrates into the Peltier effect cell through central P-type
region 51 from front central plate 40 to rear plate 42. It then
passes from rear plate 42 into ring-shaped region 52 towards front
ring-shaped plate 44. Finally, the current flows through peripheral
region 54 and comes out through rear ring-shaped plate 46 and
metallization 48. Under such conditions, the front surface of the
system, that is, plates 40 and 44, becomes a cold source. This cold
source cools down rear metallization 31 of component 30, and thus
the junction or area thereof under heating.
[0043] The operating temperature of vertical monolithic circuit 30
is then advantageously lowered and stabilized. This enables
improving the circuit operation and increasing its lifetime.
[0044] An advantage of the present invention is that the cooling
system according to the present invention does not use a separate
power supply.
[0045] According to an embodiment of the present invention, in the
case of average powers to be dissipated, that is, when the current
is on the order of from a few amperes to a few tens of amperes, the
different thicknesses of the elements forming the cooler are low
and said cooler may advantageously be formed directly on the rear
surface of the vertical monolithic one-way component with which it
is associated.
[0046] According to an embodiment of the present invention, the
cooler is formed separately from the vertical monolithic one-way
component with which it is associated, after which they are joined
by an appropriate technique, for example, by gluing or
soldering.
[0047] Of course, the present invention is likely to have various
alterations, improvements, and modifications which will readily
occur to those skilled in the art. In particular, it will be within
the abilities of those skilled in the art to make any material and
thickness modification necessary in a given technological process.
Thus, it will be within the abilities of those skilled in the art
to adapt the isolating materials to the desired electric or
electric and thermal isolation function.
[0048] Similarly, it will be within the abilities of those skilled
in the art to adapt the used conductive materials to the used
technological process. In particular, those skilled in the art will
adapt the conductive material forming the different metallizations
31 and 48 and conductive plates 40, 42, 44, and 46 to the thermal
and electric conduction constraints of the component.
[0049] It will also be within the abilities of those skilled in the
art to adapt the dimensions, especially the surface area, and the
doping levels of central region 51, ring-shaped region 52, and
peripheral region 54, in particular according to the current
constraints. It should be noted that the thickness of the
thermoelectric substrate in which are formed central region 51,
ring-shaped region 52, and peripheral region 54, depends on the
desired temperature decrease. In the considered example of a
bismuth telluride substrate, a thickness on the order of from 5 to
20 micrometers would be enough. Substrates of such a thickness may
be directly deposited on the rear surface of a vertical monolithic
one-way component, for example, by a pulsed laser deposition. It
should further be understood by those skilled in the art that
bismuth telluride has been described as a thermoelectric
semiconductor element as a non-limiting example only.
[0050] It should also be noted that the cooler according to the
present invention could be turned over, its lower surface in the
drawings being in electric contact by its periphery with the rear
surface metallization of the vertical electronic circuit and the
central portion of its upper surface in the drawings forming the
second terminal of the self-cooled component. Further, although it
is currently preferred to use a cooler with three concentric
regions of alternate conductivity types of a thermoelectric
semiconductor material, other numbers of regions and other
arrangements may be selected by those skilled in the art to adapt
to specific practical conditions.
[0051] Further, only those elements necessary to the understanding
of the present invention have been described. In particular, it
will be within the abilities of those skilled in the art to
complete the structure of FIGS. 3 and 4 with any necessary element
such as, for example, an airflow forced by a ventilation
system.
[0052] Thus, the present invention, as illustrated in FIG. 5,
provides the forming of a self-cooled electronic component 70,
formed of a vertical monolithic circuit 30 and of a Peltier cooler
50 conducting a same current I, capable of being connected by
conductors 71 and 72 to a circuit 74.
[0053] The one-way electronic component may be a one-way component
by nature, for example, a diode or a thyristor. This may also be a
bi-directional conduction element inserted in a circuit such that
it can only conduct a current of a determined direction, for
example, a resistor or another passive component connected to a
circuit comprising a series diode. A possible connection between
circuit 74 and a control terminal of component 30 has also been
shown in FIG. 5 by a dotted line 75. The present invention may also
apply to the field of integrated circuits, for example, by
providing for the rear surface to be metallized and to correspond
to a terminal of the integrated circuit intended to be connected to
an external supply or supply reference terminal. A current
substantially corresponding to the total current consumed by the
integrated circuit when it is operating then enters or comes out
through this rear surface metallization. Thus, in the following
claims, term "vertical monolithic circuit" should be interpreted as
covering any type of discrete or integrated component, active or
passive, in which a current is extracted or introduced through the
rear surface.
[0054] Such alterations, modifications, and improvements are
intended to be part of this disclosure, and are intended to be
within the spirit and the scope of the present invention.
Accordingly, the foregoing description is by way of example only
and is not intended to be limiting. The present invention is
limited only as defined in the following claims and the equivalents
thereto.
* * * * *