U.S. patent application number 09/952140 was filed with the patent office on 2003-03-20 for methods of making microelectronic assemblies using bonding stage and bonding stage therefor.
Invention is credited to Behlen, Jim, Damberg, Philip, Kunz, Rene.
Application Number | 20030054627 09/952140 |
Document ID | / |
Family ID | 25492625 |
Filed Date | 2003-03-20 |
United States Patent
Application |
20030054627 |
Kind Code |
A1 |
Behlen, Jim ; et
al. |
March 20, 2003 |
METHODS OF MAKING MICROELECTRONIC ASSEMBLIES USING BONDING STAGE
AND BONDING STAGE THEREFOR
Abstract
A method of making a microelectronic assembly comprises
connecting a lead to a contact on a microelectronic element and to
a stage. The microelectronic element is juxtaposed with a
microelectronic component and the lead is disconnected from the
stage. The lead is bonded to a terminal pad on the microelectronic
component. A stage for making a microelectronic assembly has a
conduit for introducing a bonding tool toward a lead bonded to the
stage and extending across the conduit while the microelectronic
element is juxtaposed with the microelectronic component.
Inventors: |
Behlen, Jim; (Sunnyvale,
CA) ; Damberg, Philip; (Cupertino, CA) ; Kunz,
Rene; (Mountain View, CA) |
Correspondence
Address: |
LERNER, DAVID, LITTENBERG,
KRUMHOLZ & MENTLIK
600 SOUTH AVENUE WEST
WESTFIELD
NJ
07090
US
|
Family ID: |
25492625 |
Appl. No.: |
09/952140 |
Filed: |
September 14, 2001 |
Current U.S.
Class: |
438/617 ;
257/E21.518; 257/E23.069 |
Current CPC
Class: |
H01L 2924/01082
20130101; H01L 23/3114 20130101; H01L 2224/48624 20130101; H01L
2224/48647 20130101; H01L 2224/85203 20130101; H01L 2924/00013
20130101; H01L 2224/48465 20130101; H01L 2224/85181 20130101; H01L
2224/48091 20130101; H01L 2224/32014 20130101; H01L 2224/85207
20130101; H01L 2924/00014 20130101; H01L 2224/05624 20130101; H01L
2224/48744 20130101; H01L 2224/48747 20130101; H01L 2224/73265
20130101; H01L 2924/01013 20130101; H01L 2924/12042 20130101; H01L
2224/8114 20130101; H01L 2224/1134 20130101; H01L 2224/48724
20130101; H01L 2224/48744 20130101; H01L 2924/01079 20130101; H01L
2224/48227 20130101; H01L 24/85 20130101; H01L 2221/68359 20130101;
H01L 2224/48624 20130101; H01L 2224/48647 20130101; H01L 2924/00014
20130101; H01L 2224/48091 20130101; H01L 2224/85001 20130101; H01L
2924/14 20130101; H01L 2224/45124 20130101; H01L 2924/12042
20130101; H01L 2224/05644 20130101; H01L 2224/48644 20130101; H01L
2224/85181 20130101; H01L 23/49816 20130101; H01L 2224/45144
20130101; H01L 2224/85205 20130101; H01L 2224/85205 20130101; H01L
2924/01006 20130101; H01L 2924/15311 20130101; H01L 2924/00013
20130101; H01L 2224/48747 20130101; H01L 2924/01033 20130101; H01L
2224/05647 20130101; H01L 2224/45124 20130101; H01L 2224/48465
20130101; H01L 2224/48465 20130101; H01L 2224/48644 20130101; H01L
21/6835 20130101; H01L 24/48 20130101; H01L 2224/48091 20130101;
H01L 2224/0401 20130101; H01L 2224/45144 20130101; H01L 2224/85207
20130101; H01L 2924/01029 20130101; H01L 2924/00014 20130101; H01L
2224/78 20130101; H01L 2924/00014 20130101; H01L 2924/00 20130101;
H01L 2224/48465 20130101; H01L 2924/00 20130101; H01L 2924/00
20130101; H01L 2924/00 20130101; H01L 2924/00 20130101; H01L
2924/00 20130101; H01L 2924/00 20130101; H01L 2924/00014 20130101;
H01L 2924/00 20130101; H01L 2924/00 20130101; H01L 2924/00014
20130101; H01L 2224/48091 20130101; H01L 2924/00 20130101; H01L
2224/48227 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2224/85203 20130101; H01L 24/45 20130101; H01L 2224/48724
20130101; H01L 2924/01005 20130101; H01L 2924/014 20130101; H01L
2224/13099 20130101 |
Class at
Publication: |
438/617 |
International
Class: |
H01L 029/06 |
Claims
1. A method of making a microelectronic assembly, comprising: a)
connecting a first end of a lead to a contact on a microelectronic
element; b) connecting a second end of said lead to a stage
disposed adjacent to said microelectronic element; c) juxtaposing
said microelectronic element with a microelectronic component
having terminal pads exposed at a first side of said
microelectronic component; d) disconnecting said lead from said
stage, either before or after said juxtaposing; and e) bonding said
lead to one of said terminal pads.
2. The method of claim 1, wherein said lead comprises a wire having
a first end and a second end, said wire being formed by wire
bonding said first end to said contact, extending said wire past a
peripheral edge of said microelectronic element and bonding said
second end of said wire to said stage.
3. The method of claim 1, further comprising assembling said
microelectronic element with said microelectronic component.
4. The method of claim 3, further comprising assembling at least
one pad element with said microelectronic element and said
microelectronic component so that said at least one pad element is
disposed between said microelectronic element and said
microelectronic component.
5. The method of claim 4, wherein said at least one pad element
comprises a compliant pad element.
6. The method of claim 1, wherein said microelectronic element
comprises at least one semiconductor chip.
7. The method of claim 1, further comprising making said
microelectronic component by forming said terminal pads on a first
side of a dielectric layer, forming conductive traces on said first
side, and forming connection terminals on a second side of said
dielectric layer so that said terminal pads are electrically
connected to said connection terminals by said conductive
traces.
8. The method of claim 7, further comprising applying solder at
said second side of said dielectric layer to form said connection
terminals.
9. The method of claim 1, wherein said lead is disconnected from
said stage by severing a portion of said lead connected to said
contact from another portion of said lead connected to said
stage.
10. The method of claim 1, wherein said lead is releasably
connected to said stage and is disconnected from said stage by
removing said microelectronic element from said stage.
11. The method of claim 10, wherein said lead is connected to an
upper surface of said stage and said upper surface comprises a
non-stick surface.
12. The method of claim 1, wherein said bonding of said lead to
said terminal pad includes displacing said lead in a direction
toward said terminal pad utilizing a bonding tool.
13. The method of claim 1, wherein said stage has a first surface
and includes a conduit being open on said first surface.
14. The method of claim 13, wherein said second end of said lead is
bonded to said first surface so that said lead extends over said
conduit.
15. The method of claim 14, wherein said lead is disconnected by
inserting a cutting tool into said conduit and severing a portion
of said lead connected to said contact from another portion of said
lead connected to said stage.
16. The method of claim 14, wherein said lead is bonded to said
terminal pad by inserting a bonding tool into said conduit,
displacing said lead in a direction toward said terminal pad and
bonding said lead to said terminal pad.
17. The method of claim 1, wherein said microelectronic element is
mounted to said stage and said microelectronic element is
juxtaposed with said microelectronic component by moving said stage
to said microelectronic component.
18. The method of claim 1, wherein: a) said microelectronic element
has a first surface and a second surface facing oppositely from
said first surface and said contacts are exposed at said first
surface; b) said microelectronic element is juxtaposed with said
microelectronic component so that said first surface faces said
first side of said microelectronic component.
19. The method of claim 1, wherein: a) said microelectronic element
has a first surface and a second surface facing oppositely from
said first surface and said contacts are exposed at said first
surface; b) said microelectronic element is juxtaposed with said
microelectronic component so that said second surface faces said
first side of said microelectronic component.
20. A method of forming a microelectronic assembly, comprising: a)
connecting a first end of a wire to a contact on a microelectronic
element having peripheral edges; b) extending said wire beyond said
peripheral edges of said microelectronic element; c) connecting a
second end of said wire to a stage disposed adjacent to said
microelectronic element; d) assembling said microelectronic element
with a microelectronic component having a first side and a second
side, said first side having terminal pads exposed at said first
side and said second side having connection terminals exposed at
said second side, each said connection terminal being electrically
connected to one of said terminal pads; e) disconnecting said wire
from said stage, either before or after said assembling; and f)
bonding said wire to one of said terminal pads.
21. The method of claim 20, further comprising assembling at least
one pad element with said microelectronic element and said
microelectronic component so that said at least one pad element is
disposed between said microelectronic element and said
microelectronic component.
22. The method of claim 21, wherein said at least one pad element
comprises a compliant pad element.
23. The method of claim 20, wherein said microelectronic element
comprises at least one semiconductor chip.
24. The method of claim 20, wherein said wire is disconnected from
said stage by severing a portion of said wire connected to said
contact from another portion of said wire connected to said
stage.
25. The method of claim 20, wherein said stage has a first surface
and includes a conduit being open on said first surface and said
second end of said wire is bonded to said first surface so that
said wire extends over said conduit.
26. The method of claim 25, wherein said wire is bonded to said
terminal pad by inserting a bonding tool into said conduit,
displacing said wire in a direction toward said terminal pad and
bonding said wire to said terminal pad.
27. The method of claim 20, wherein said microelectronic element is
mounted to said stage and said microelectronic element is
juxtaposed with said microelectronic component by moving said stage
to said microelectronic component.
28. A stage for making a microelectronic assembly, comprising: a) a
base arranged to hold a microelectronic element during positioning
of the microelectronic element with respect to a microelectronic
component; b) walls extending upwardly from the base and
terminating in an upper surface, said walls having a conduit
defined therein so as to be open at said upper surface; and c) a
bonding tool arranged to be introduced toward a lead extending
across said conduit at said upper surface and to apply energy in
bonding the lead to a terminal pad on a microelectronic
component.
29. The stage of claim 28, wherein said base defines vacuum holes
for holding the microelectronic element.
30. The stage of claim 28, further comprising a cutting tool for
separating a lead bonded to said upper surface from said stage.
31. The stage of claim 30, wherein said cutting tool is arranged to
be introduced toward the lead through said conduit.
32. The stage of claim 28, further comprising a clamp for holding
the microelectronic element.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to methods of making
microelectronic assemblies such as semiconductor chip packages.
BACKGROUND OF THE INVENTION
[0002] Modern electronic devices utilize semiconductor chips,
commonly referred to as "integrated circuits" which incorporate
numerous electronic elements. These chips are mounted on substrates
that physically support the chips and electrically interconnect
each chip with other elements of a circuit. The substrate may be a
part of a chip package including a single chip and equipped with
terminals for interconnecting the chip with external circuit
elements. The interconnection between the chip and its supporting
substrate is commonly referred to as a "first level"
interconnection. The interconnection between the substrate and the
larger elements of the circuit is commonly referred to as a "second
level" interconnection.
[0003] In a wire bonding process, the substrate has a top surface
with a plurality of electrically conductive contact pads disposed
on the top surface near the periphery of the substrate. The chip is
secured to the top surface of the substrate so that the contact
pads on the substrate lie outwardly of the chip. The chip is
mounted with the back surface of the chip confronting the top
surface of the substrate and with the front surface of the chip
facing upwardly, away from the substrate, so that electrical
contacts on the front surface are exposed. Fine wires are connected
between the contacts on the front face of the chip and the contact
pads on the top surface of the substrate.
[0004] Semiconductor chip assemblies may also utilize a component
having bond windows for making electrical connections between
terminals on the component and contacts on a semiconductor chip.
Such a component is disclosed in certain embodiments of WO
94/03036, the disclosure of which is hereby incorporated by
reference herein. The component comprises a layer having a gap and
leads extending across the gap so that the leads are supported at
both ends. The component is disposed on top of a semiconductor chip
so that the leads generally extend over the contacts of the chip. A
bonding tool is utilized to bond each lead to a contact on the
chip, by advancing the tool toward a lead and forcing the lead
toward the contact on the chip. The lead may include a frangible
section that breaks when the lead is forced toward the contact.
Heat and/or ultrasonic vibration is applied to the lead by the tool
so as to bond the lead to the contact. Prior to bonding to a
semiconductor chip, the leads are secured to the component and
somewhat protected during handling of the component and arranging
of the component with the semiconductor chip. However, a bonding
window is required to provide access to the contacts.
[0005] Despite the foregoing improvements, further advancement in
making microelectronic assemblies is desirable.
SUMMARY OF THE INVENTION
[0006] The present invention addresses these needs.
[0007] In one aspect of the present invention, a method of making a
microelectronic assembly comprises connecting a first end of a lead
to a contact on a microelectronic element. A second end of the lead
is connected to a stage disposed adjacent to the microelectronic
element. The microelectronic element is juxtaposed with a
microelectronic component having terminal pads exposed at a first
side of the microelectronic component. The lead is disconnected
from the stage, either before or after juxtaposing the
microelectronic element with the microelectronic component. The
lead is bonded to one of the terminal pads on the microelectronic
component.
[0008] Methods in accordance with embodiments of the invention
interconnect a microelectronic element with a microelectronic
component without the use of a bond window for accessing the leads.
In addition, the leads may remain bonded to the stage during some
or all of the handling of the microelectronic element and are thus
supported during handling, making damage to the leads less likely.
Components having bond windows must have bond windows aligned with
the contacts on the microelectronic element to be assembled with
the component. In a method in accordance with embodiments of the
invention, microelectronic elements of different sizes and having
contacts in different locations may be accommodated.
[0009] In preferred embodiments, the lead comprises a wire formed
by wire bonding a first end of the wire to the contact on the
microelectronic element, extending the wire past a peripheral edge
of the microelectronic element, and bonding a second end of the
wire to the stage. The microelectronic element is preferably
mounted to the stage and juxtaposed with the microelectronic
component by moving the stage to the microelectronic component. The
microelectronic element preferably has a first surface and a second
surface facing oppositely from the first surface and the contacts
are exposed at the first surface. The microelectronic element is
preferably juxtaposed with the microelectronic component so that
the first surface faces the first side of the microelectronic
component, so that the contacts on the microelectronic element face
the terminals on the microelectronic component.
[0010] In embodiments having the wires bonded to the stage while
the microelectronic element is juxtaposed with the microelectronic
component, the wires are supported during handling and arranging
the microelectronic element with the microelectronic component.
When the microelectronic element is juxtaposed with the component
so that the contacts on the microelectronic element face the
component, the wires may be shorter than in other embodiments and
performance of the completed assembly is enhanced.
[0011] In other embodiments, the microelectronic element is
juxtaposed with the microelectronic component so that the second
surface of the microelectronic element faces the first side of the
microelectronic component. In this embodiment, the contacts on the
microelectronic component face away from the component.
[0012] The microelectronic element is preferably assembled with the
microelectronic component. At least one pad element is preferably
assembled with the microelectronic element and the microelectronic
component so that the at least one pad element is disposed between
the microelectronic element and the microelectronic component. The
at least one pad element may comprise a compliant pad element.
[0013] The microelectronic element may comprise at least one
semiconductor chip, a temporary support layer, a sacrificial layer,
a connection component, a printed circuit board, a wafer or tape of
semiconductor chips, or a substrate. The microelectronic component
may comprise a semiconductor chip, a printed circuit board,
temporary support layer, a sacrificial layer, a connection
component, a substrate, or a wafer or tape of semiconductor chips,
and may incorporate a variety of conductive features on surfaces
thereof or incorporated within the component.
[0014] Methods in accordance with embodiments of the present
invention may comprise making the microelectronic component by
forming the terminal pads on a first side of a dielectric layer,
forming conductive traces on the first side, and forming connection
terminals on a second side of the dielectric layer so that the
terminal pads are electrically connected to the connection
terminals by the conductive traces. Solder may be applied at the
second side of the dielectric layer to form the connection
terminals.
[0015] The lead is preferably disconnected from the stage by
severing a portion of the lead connected to the contact from
another portion of the lead connected to the stage. The bonding of
the lead to the terminal pad may include displacing the lead in a
direction toward the terminal pad utilizing a bond tool.
[0016] The lead, in other preferred embodiments, is releasably
connected to the stage and disconnected from the stage by removing
the microelectronic element from the stage. For example, the lead
may be connected to an upper surface of the stage and the upper
surface may comprises a non-stick surface.
[0017] In certain preferred embodiments, the stage has a first
surface and includes a conduit being open on the first surface. The
second end of the lead is bonded to the first surface so that the
lead extends over the conduit. The lead may be disconnected by
inserting a cutting tool into the conduit and severing a portion of
the lead connected to the contact from another portion of the lead
connected to the stage. The lead is preferably bonded to the
terminal pad by inserting a bonding tool into the conduit,
displacing the lead in a direction toward the terminal pad and
bonding the lead to the terminal pad.
[0018] In another aspect of the present invention, a method of
making a microelectronic assembly comprises connecting a first end
of a wire to a contact on a microelectronic element having
peripheral edges. The wire is extended beyond the peripheral edges
of the microelectronic element. A second end of the wire is bonded
to a stage disposed adjacent to the microelectronic element. The
microelectronic element is assembled with a microelectronic
component having a first side and a second side. The
microelectronic component has terminal pads exposed at the first
side and connection terminals exposed at the second side. Each
connection terminal is electrically connected to one of the
terminal pads. The wire is disconnected from the stage, either
before or after the assembling. The wire is bonded to one of the
terminal pads.
[0019] At least one pad element is preferably assembled with the
microelectronic element and the microelectronic component so that
the at least one pad element is disposed between the
microelectronic element and the microelectronic component. The at
least one pad element preferably comprises a compliant pad
element.
[0020] The microelectronic element may comprise at least one
semiconductor chip.
[0021] The wire is preferably disconnected from the stage by
severing a portion of the wire connected to the contact from
another portion of the wire connected to the stage.
[0022] In certain preferred embodiments, the stage has a first
surface and includes a conduit open on the first surface. The
second end of the wire is bonded to the first surface so that the
wire extends over the conduit. The wire is bonded to the terminal
pad by inserting a bonding tool into the conduit, displacing the
wire in a direction toward the terminal pad and bonding the wire to
the terminal pad.
[0023] Preferably, the microelectronic element is mounted to the
stage and the microelectronic element is juxtaposed with the
microelectronic component by moving the stage to the
microelectronic component.
[0024] In a further aspect of the present invention, a stage for
making a microelectronic assembly comprises a base arranged to hold
a microelectronic element during positioning of the microelectronic
element with respect to a microelectronic component. The stage has
walls extending upwardly from the base and terminating in an upper
surface. The walls define a conduit that is open at the upper
surface. A bonding tool is arranged to be introduced toward a lead
extending across the conduit at the upper surface and to apply
energy in bonding the lead to a pad on a microelectronic
component.
[0025] The base of the stage may define vacuum holes for holding
the microelectronic element. In another alternative, the stage has
a clamp for holding the microelectronic element.
[0026] The stage may include a cutting tool for separating from the
stage a lead bonded to the upper surface. The cutting tool is
preferably arranged to be introduced toward the lead through the
conduit.
BRIEF DESCRIPTION OF THE DRAWINGS
[0027] These and other features, aspects and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings
where:
[0028] FIG. 1 is a schematic, cross-sectional view of a
microelectronic element disposed in a stage in a method in
accordance with an embodiment of the invention;
[0029] FIG. 2 is the cross-sectional view of FIG. 1, at a later
stage in the method;
[0030] FIG. 3 is the cross-sectional view of FIG. 2, at a later
stage in the method;
[0031] FIG. 4 is the cross-sectional view of FIG. 3, at a later
stage in the method;
[0032] FIG. 5 is a schematic, cross-sectional view of a
microelectronic component in a method in accordance with the
embodiment of FIGS. 1-4;
[0033] FIG. 6 is a schematic, top right perspective view of the
microelectronic component of FIG. 5;
[0034] FIG. 7 is the cross-sectional view of FIG. 5, at a later
stage in the method;
[0035] FIG. 8 is a schematic, cross-sectional view of a
microelectronic component and microelectronic element in a method
in accordance with the embodiment of FIGS. 1-7;
[0036] FIG. 9 is the cross-sectional view of FIG. 8, at a later
stage in the method;
[0037] FIG. 10 is the cross-sectional view of FIG. 9, at a later
stage in the method;
[0038] FIG. 11 is a schematic, cross-sectional view of a
microelectronic element disposed in a stage in a method in
accordance with another embodiment of the invention;
[0039] FIG. 12 is the cross-sectional view of FIG. 11, at a later
stage in the method;
[0040] FIG. 13 is a schematic, cross-sectional view of a
microelectronic element and microelectronic component in the method
of FIGS. 11-12;
[0041] FIG. 14 is the cross-sectional view of FIG. 13, at a later
stage in the method;
[0042] FIG. 15 is the cross-sectional view of a FIG. 14, at a later
stage in the method;
[0043] FIG. 16 is the cross-sectional view of a FIG. 15, at a later
stage in the method;
[0044] FIG. 17 is a schematic, cross-sectional view of a
microelectronic element and microelectronic component in a method
in accordance with a further embodiment of the invention;
[0045] FIG. 18 is the cross-sectional view of FIG. 17, at a later
stage in the method;
[0046] FIG. 19 is a schematic, cross-sectional view of a
microelectronic element disposed in a stage in a method in
accordance with a further embodiment of the invention;
[0047] FIG. 20 is the cross-sectional view of FIG. 19, at a later
stage in the method; and
[0048] FIG. 21 is the cross-sectional view of FIG. 20, at a later
stage in the method.
DETAILED DESCRIPTION
[0049] A method in accordance with an embodiment of the invention
is shown in FIGS. 1-10. A microelectronic element, which may
comprise a semiconductor chip 10, is supported on a stage 12 having
one or more walls 14 surrounding the chip 10 and a base 16 for
supporting the chip 10. The walls 14 extend upwardly from the base
16 and terminate in an upper surface 15 disposed adjacent the chip
10. In preferred embodiments, the walls 14 have a height
approximately equal to the height of the chip 10 so that leads to
be connected to the chip are no longer than necessary. The chip 10
has a first surface 18 and a second surface 20 facing oppositely
from the first surface 18. The chip 10 has four peripheral edges
extending between the first surface 18 and second surface 20. As
FIG. 1 is a cross-sectional view, only the first peripheral edge 22
and the second peripheral edge 24 are shown. Contacts 25 are
exposed at the first surface 18, which faces upwardly away from the
base 16 of the stage 12. The chip 10 shown in FIG. 1 has contacts
arranged in two rows alongside the first peripheral edge 22 and
second peripheral edge 24. However, microelectronic elements having
contacts arranged in any number of patterns may be used in
embodiments in accordance with the invention. The second surface 20
of the chip 10 rests upon the base 16. The contacts 25 may comprise
contacts of copper, gold, aluminum, or alloys of these metals.
[0050] As shown in FIG. 2, leads 26 are connected to the contacts
25, preferably using wire bonding techniques. Such techniques are
well known in the art of making semiconductor chip assemblies. A
wire bonding tool is utilized to hold a first end 31 of a wire 28
against the contact 25 and bonding energy is applied to bond the
wire 28 to the contact 25. The bonding energy may comprise either
thermocompression, ultrasonic, or thermosonic energy. The wire
bonding tool has a wire feed hole through which the wire is
dispensed. After bonding the wire 28 to the contact 25, the wire
bonding tool is withdrawn and moved towards the upper surface 15.
As the tool is moved, the wire 28 is dispensed from the feed hole.
The wire bonding tool is then used to bond the wire 28 to the upper
surface 15 of the walls 14 of the stage 12, by holding the wire
against the upper surface and applying bonding energy. The
remaining wire in the wire bonding tool is separated from the wire
28 extending between the contact 25 and the upper surface 15 of the
stage 12 by breaking or flaming off the wire so that a second end
32 of the wire 28 remains bonded to the stage. This cycle may be
reversed so that the wire is first bonded to the stage 12 and then
bonded to the contact 25 on the chip 10. Before bonding to the
contact 25, the wire bonding tool may be used to form a ball 29 of
wire material which is bonded to the contact 25. The wire may
comprise any material suitable for making an electrically
conductive connection. For example, the wire material may comprise
gold, gold alloys, or aluminum alloys. The wire 28 is preferably
flexible.
[0051] As shown in FIGS. 3 and 4, a cutting tool 30 is utilized to
separate the wire 28 from the stage 12 by severing the wire 28. The
cutting tool may comprise: a series of cutting tools, each tool
cutting an individual wire 28; a pair of cutting tools, each tool
cutting the wires 28 connected to contacts 25 adjacent one
peripheral edge of the chip 10; or a single tool. The cutting tool
may comprise a blade or a scissor-like pair of blades. After the
wire 28 is cut, the wire remains connected to a contact 25 at the
first end 31 and has a free, unconnected end.
[0052] A microelectronic component, such as a connection component
used to make semiconductor chip packages, is formed. An example of
a microelectronic component that may be used in embodiments of the
invention is shown in FIG. 5. The component 35 shown in FIG. 5 may
be formed by providing a dielectric layer 36 having a first side 38
and a second side 40 facing oppositely from the first side. The
dielectric layer may comprise a layer of polyimide and is
preferably a flexible layer. The dielectric layer 36 has a central
region 42 and a peripheral region 43 surrounding the central region
42 and extending to edges of the dielectric layer 36. Terminal pads
44 are formed on the dielectric layer 36 so that the terminal pads
44 are exposed at the first side 38 in the peripheral region 43 of
the dielectric layer. Conductive traces 46 are formed so that they
are connected to the terminal pads 44 and extend on the first side
38 of the dielectric layer to vias 48. (FIG. 6). Any of the methods
for forming such conductive features that are well known in the
microelectronic and/or semiconductor fields may be used. For
example, the terminal pads 44 and traces 46 may be formed by
photolithographic techniques. In other embodiments, the traces 46
are incorporated within the dielectric layer 36 or extend on the
second side 40. Other conductive features, such as power planes or
ground planes may be incorporated within dielectric layer 36 and
dielectric layer 36 may comprise a plurality of layers.
[0053] Vias 48 are formed so that they extend from the first side
38 to the second side 40 of the dielectric layer and are lined
and/or filled with an electrically conductive material so as to
form an electrical connection between the traces 46 on the first
side 38 and connection terminals 50 exposed at the second side 40.
The vias essentially comprise holes through the dielectric layer 36
and may be made by cutting the dielectric layer with a laser, or by
any of the methods known in the microelectronic and/or
semiconductor fields. The vias 48 are bounded by walls of the
dielectric layer formed in cutting the dielectric layer 36. The
vias 48 are lined with an electrically conductive material by
seeding the walls of the dielectric layer 36 in the vias 48 with an
electrically conductive material, as is well known. Preferably,
electrically conductive annular pads surrounding the vias are
formed at the second side 40 of the dielectric layer 36. The
annular pads may also be formed utilizing photolithographic
techniques. The terminal pads 44, traces 46 and conductive material
for the vias 48 may comprise any conductive material suitable for
electronic components. These conductive features may comprise
copper, gold, alloys of these metals, or conductive polymers.
[0054] The connection terminals 50 may include solder disposed in
the vias 48 or otherwise applied at the second side 40 of the
dielectric layer 36. Solder balls may be applied to the vias 48, at
the annular pads, and reflowed so that the solder flows into the
vias 48 and forms a bulging, dome-shaped terminal 50 exposed at the
second side 40 of the dielectric layer 36. Other methods of forming
such terminals are known. For example, a solder paste may be
applied at the second side 40. The connection terminals 50 and vias
48 are formed so that the terminal pads 44, exposed at the first
side 38, are connected to the connection terminals 50, exposed at
the second side 40, through the traces 46.
[0055] The connection terminals 50 are used in forming connections
between the chip 10 and other microelectronic elements, such as a
printed circuit board or substrate.
[0056] The chip and component shown in the figures may include many
more contacts, terminal pads, connection terminals and traces than
are shown, as the Figures are schematic views and show only a few
such features, for ease of illustration.
[0057] A pad element 52 is attached to the microelectronic
component 35, as shown in FIG. 7. The pad element 52 preferably
comprises a pad of compliant material, such as that disclosed in
certain embodiments of U.S. Pat. No. 5,679,977, the disclosure of
which is hereby incorporated by reference herein. The pad element
may be formed in place on the component 35, or on the chip 10, or
otherwise disposed therebetween. The pad element may be formed by
screen printing a curable liquid elastomer gel onto a surface of
the component 35 or chip 10 and then curing the elastomer to form a
compliant layer. The pad element may also comprise a preformed
element that is adhered to the component 35 or the chip 10.
[0058] In other preferred embodiments, a plurality of pad elements
are disposed on or otherwise interposed between the microelectronic
component and the microelectronic element. Such pad elements may be
as disclosed in certain embodiments of U.S. Pat. No. 5,659,952, the
disclosure of which is hereby incorporated by reference herein.
[0059] The component 35, pad element 52 and chip 10 are juxtaposed
with one another and assembled together. The chip 10 is juxtaposed
with the pad element 52 and component 35 utilizing a pick and place
machine, or other robotic equipment for handling microelectronic
parts. The pick and place machine engages the chip 10 using a clamp
54, which may use either a mechanical clamping force or vacuum to
hold the chip 10 in place during handling. The pick and place
machine moves the clamp 54 so as to orient the chip 10 to the
position shown in FIG. 8, relative to the component 35. The chip 10
is placed upon, and preferably adhered to, a face of the pad
element 52 while the component 35 is supported on a surface or
platen. Preferably, such surface or platen for supporting the
component 35 has a groove for accommodating the connection
terminals 50 while supporting the component 35 by the dielectric
layer 36. The pick and place machine may be used to apply pressure
necessary for curing or activating any adhesive that may be used to
adhere the chip 10 to the pad element 52. The chip 10 is placed on
the pad element 52 So that the wires 28 are positioned above the
terminal pads 44. Preferably, the terminal pads 44 are relatively
large in comparison to the wires 28 so that minor errors in placing
the chip 10 with respect to the component 35 do not affect the
ability to bond the wires 28 to the terminal pads 44. Automatic
pattern recognition or robotic vision equipment known in
microelectronic manufacturing and other fields is preferably used
to position the chip 10 on the component 35 So that the wires 28
are aligned with the terminal pads 44.
[0060] Preferably, the pick and place machine is arranged to handle
a plurality of chips and assemble a plurality of chips with a
plurality of components or a substrate incorporating a plurality of
individual component regions. The individual component regions may
later be separated in singulation of individual chip packages. In
singulation, the component regions are essentially severed from one
another.
[0061] The wires 28 are bonded to the terminal pads 44, as shown in
FIGS. 9 and 10. A bonding tool 55 is utilized to displace the wires
28 toward a terminal pad 44, engage the wires 28 with the terminal
pads 44, and apply energy to bond the wires 28 to the terminal pads
44. The bonding tool 55 is preferably arranged to apply heat and/or
ultrasonic vibration to bond the wires 28 to the terminal pads 44.
Preferably, the bonding tool 55 comprises a bonding tool similar to
that disclosed in certain embodiments of WO 94/03036, the
disclosure of which is hereby incorporated by reference herein. The
bonding tool 55 engages each wire 28 and bonds the wire 28 to the
terminal pad 44, one at a time. The tool 55 advances to the next
wire 28 and can bond all the wires 28 on a series of chips 10
quickly enough for a commercial operation on large numbers of
chips. In other embodiments, gang bonding may be used, in which a
series of wires 28 are bonded to terminal pads 44 at the same
time.
[0062] The bonding tool 55 preferably has features that engage the
wires 28 and encourage correct positioning of the wires with
respect to the terminal pads 44. For example, the bonding tool may
have grooves for engaging and adjusting the position of the wires
28. Automatic pattern recognition and positioning equipment known
in the microelectronic manufacturing and other fields may be used
in operating the bonding tool 55 so as to engage the wires 28 and
bond them to the terminal pads 44.
[0063] Preferably, the assembly is encapsulated to protect the
wires and the connections between the contacts, wires, and terminal
pads. The assembly may be encapsulated by engaging the assembly
between two platens or placing the assembly in a fixture and
introducing a flowable, curable dielectric material so that the
material invades the spaces around the wires 28 and between the
chip 10 and component 35. Preferably, the encapsulant material is
curable to a compliant material so that compliant or flexible
materials used, such as flexible leads, remain flexible.
[0064] Preferably, the assembly is formed so that the connection
terminals move relative to the contacts on the chip, as disclosed
in certain embodiments of U.S. Pat. No. 5,679,977, the disclosure
of which is hereby incorporated by reference herein. The dielectric
layer of the microelectronic component and the pad element may
comprise flexible or compliant materials. In bonding the wires to
the terminal pads of the microelectronic component, a support
structure, such as those disclosed in certain embodiments of U.S.
Pat. No. 5,777,379, the disclosure of which is hereby incorporated
by reference herein, may be used to support the dielectric
layer.
[0065] Another embodiment of the invention is shown in FIGS. 11-16.
Many of the steps and elements in this embodiment may be as
discussed above in connection with FIGS. 1-10 and elements shown in
FIGS. 11-16 have reference numerals corresponding to similar
elements of FIGS. 1-10. The microelectronic element, which may
comprise a semiconductor chip 110, is placed in a stage 112. The
stage 112 comprises a fixture having walls 114 that extend upwardly
from a base 116. The walls 114 have an upper surface 115 that is
disposed adjacent the first surface 118 of the chip. Contacts 125
of the chip 110 are exposed at the first surface 118.
[0066] The stage 112 has conduits 119 that are open at the upper
surface 115 of the walls 114. The stage has a clamp for engaging
and holding the chip 110 during handling. Alternatively or
additionally, the base 116 may incorporate a plurality of vacuum
holes or vacuum heads for holding the chip 110.
[0067] As shown in FIG. 12, leads 126 are attached to the contacts
125 and the upper surface 115 of the stage 112 so that the leads
126 extend over the conduits 119 in the stage 112. The leads 126
preferably comprise wire bonding wires 128.
[0068] The stage 112 is utilized to juxtapose the chip 110 with
respect to a microelectronic component 135, as shown in FIG. 13.
The stage 112 is attached to robotic handling equipment for moving
and positioning the stage 112 so that the chip is aligned with the
component 135 and the wires 128 are aligned with the terminal pads
144 on the component 135.
[0069] Preferably, a pad element 152 is interposed between the chip
110 and component 135. In interposing the pad element 152, the pad
element may be formed on, or applied to, the chip 110 or component
135. The chip 110, component 135 and pad element 152 are then
assembled together so that the wires 128 are aligned with the
terminal pads 144 of the component 135, as shown in FIG. 14.
[0070] The conduits 119 are then used in bonding the wires 128 to
the terminal pads 144 on the component 135. A bonding tool 155 is
introduced through the conduits 119 in the stage 112 and advanced
toward the wires 128 at upper surface 115. The bonding tool 155
displaces a portion of each wire 128 toward a terminal pad 144 and
bonds the wire 128 to the terminal pad 144 utilizing bonding
energy, such as heat and/or ultrasonic vibration. (FIG. 15). One
continuous conduit running adjacent the wires 128 may be utilized
as an alternative to the pair of conduits 119 shown in FIGS. 1-16.
Such conduits enable the stage 112 to be utilized for handling the
chip 110 during the various steps in the method of making a
microelectronic assembly. The conduits permit access to the wires
128 while the stage 112 holds the chip 110 in place.
[0071] Preferably, the wires 128 are severed from the upper surface
115 of the stage 112 after the chip 110 and component 135 are
assembled so that the likelihood that the wires 128 become damaged
in handling the chip 110 is reduced. As shown in FIG. 16, the wires
128 are separated from the upper surface 115 of the stage 112 by
cutting the wires 128 with a cutting tool 130. In cutting the wires
128, the portion of the wires 128 that extends to the contacts is
severed from the portion of the wires 128 that extends to the stage
112.
[0072] FIG. 16 shows the cutting tool 130 being introduced through
the conduits 119 so that the cutting tool can gain access to the
wires 118 while the stage 112 holds the chip 110. The cutting tool
may comprise a blade or a pair of scissor-like blades.
Alternatively, the wires may be severed from the upper surface 115
of the stage 112 by flaming off the portion of the wire 128
extending to the surface 115 from the portion of the wire 128
extending to the contact 125.
[0073] In a further embodiment of the invention, the
microelectronic element or chip 210 is assembled with the
microelectronic component 235 so that the second surface 220 faces
the component 235. As shown in FIG. 17, the second surface 220 of
the chip 210 is attached to the pad element 252 so that the
contacts 225 face away from the component 235. The wires 228 are
bonded to the terminal pads 244 using a bonding tool 255, as shown
in FIGS. 17 and 18. It may be necessary to make the wires 228
longer than in the embodiments discussed above, so that the wires
228 extend downwardly alongside the peripheral edges 222 and 224 of
the chip 210, to the terminal pads 244.
[0074] In a further embodiment of the invention, the leads are not
disconnected from the stage by severing one portion of the lead
from another portion of the lead. As shown in FIG. 19, a
microelectronic element 310 is mounted in a stage 312 and leads
326, which may comprise wires 328 formed by wire bonding, are
connected to contacts 325 of the microelectronic element 310 at a
first end 331 of the wires 328 and connected to the stage 312 at a
second end 332 of the wires 328. Preferably, the second end 332 of
the wires 328 are connected to an upper surface 315 of the stage
312. It is also preferred that the second end 332 is releasably
connected to the upper surface 315. For example, upper surface 315
may comprise a non-stick surface 317 so that the second end 332 of
the wires is releasable from the upper surface 317. As shown in
FIG. 21, the microelectronic element 310 is removed from the stage
312 utilizing a pick and place machine, or other robotic equipment
for handling microelectronic parts. As the microelectronic element
310 is removed from the stage 312, the wires 328 become detached
from the upper surface 315. The microelectronic element is 310 then
juxtaposed with a component, as discussed above.
[0075] These and other variations and combinations of the features
discussed above can be utilized without departing from the
invention. For example, the wires may be crimped by a tool and then
severed during bonding to the terminal pads on the microelectronic
component. In addition, connection components other than the
components discussed above may be used to form a microelectronic
assembly in accordance with embodiments of the invention. Further,
the leads may comprise leads other than the bonding wires discussed
above. Thus, the foregoing description of the preferred embodiments
should be taken by way of illustration rather than by way of
limitation of the invention as defined by the claims.
* * * * *