Information
-
Patent Grant
-
6530649
-
Patent Number
6,530,649
-
Date Filed
Thursday, August 16, 200122 years ago
-
Date Issued
Tuesday, March 11, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
-
CPC
-
US Classifications
Field of Search
US
- 347 63
- 347 50
- 347 56
- 347 13
- 347 66
- 347 42
- 239 548
- 361 761
-
International Classifications
-
Abstract
A carrier includes a substrate formed to accept microelectronic chips at various pockets in the substrate. The microelectronic chips are hermetically sealed within the substrate by a deposition process using localized energy supplied at gaps between the chips and the pockets. During the heating process, seal material is deposited in the gaps to form the hermetic seals.
Description
TECHNICAL FIELD
The technical field is microelectronic devices and methods for producing microelectronic devices. More specifically, the technical field is hermetic seals for microelectronic devices.
BACKGROUND
Inkjet printers are used to produce text and images on a variety of media such as paper, transparencies and labels. A typical inkjet printer uses a carriage that holds one or more ink cartridges. The ink that is to be printed on the media is forced through small holes in thermal inkjet (TIJ) chips to produce the desired text or image. Thermal inkjet chips are small crystal structures that are placed in a larger substrate to provide the desired array of inkjet printing nozzles. The chips include an interconnect to route signals from a front side of the substrate to a backside of the substrate.
The ink used in many inkjet printers is corrosive, and the interconnect and the materials used to form the substrate may be subject to failure due to the corrosive effect of the ink. Adhesives may be used to fill the peripheral gaps between the TIJ chips and the substrate, and may prevent the flow of ink between the TIJ chips and the substrate. Adhesives may also provide some protection for other components in an inkjet printer. Adhesives, however, have several disadvantages. One disadvantage is that conventional adhesives may corrode when exposed to ink. Conventional adhesives also fail to provide a hermetic seal, and may allow ink to pass into and through the peripheral gaps.
A need therefore exists for a corrosion resistant hermetic seal between a chip and a substrate.
SUMMARY
According to a first aspect, a carrier includes chips hermetically sealed within pockets in a substrate. A chip is hermetically sealed to the substrate by depositing seal material in a peripheral gap between the chip and the substrate. The seal is deposited between the chip and the substrate using localized energy supplied at the peripheral gap. The chips may be, for example, thermal inkjet (TIJ) chips.
According to the first aspect, the deposited seal may be generally resistant to inks used in inkjet printers, and to other corrosive substances. The deposited seal is more stable than adhesive seals. In addition, the hermetic seal prevents corrosive ink from affecting delicate wiring or other fixtures on the chips and on the substrate.
Also according to the first aspect, the use of localized energy reduces the chance that carrier components will be damaged by the deposition process. For example, if the localized energy is localized heating at the peripheral gap, the heating can be maintained in a controlled area. Therefore, wiring, fixtures, or other components on the carrier are not unnecessarily exposed to the heat energy used in the deposition process.
Other aspects and advantages will become apparent from the following detailed description, taken in conjunction with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
The detailed description will refer to the following drawings, in which like numerals refer to like elements, and in which:
FIG. 1
is a perspective view of a carrier comprising a substrate and chips;
FIG. 2
is a cross-sectional side view of the carrier of
FIG. 1
;
FIG. 3A
is a cross-sectional side view of a pocket of the substrate illustrated in
FIG. 1
;
FIG. 3B
is a plan view of a top side of the substrate illustrated in
FIG. 3A
;
FIG. 4A
is a cross-sectional side view of a chip; and
FIG. 4B
is a plan view of a top side of the chip illustrated in FIG.
4
A.
DETAILED DESCRIPTION
A seal deposited between a chip and a substrate provides a hermetic seal between the chip and the substrate. The hermetic seal may be used in a variety of applications, and provides significant advantages. One such application is in a carrier for an inkjet printer. In the inkjet printer embodiment, hermetic seals are formed between thermal inkjet (TIJ) chips and a substrate.
FIG. 1
is a perspective view of a carrier
10
suitable for use in an inkjet printer. The carrier
10
includes a substrate
20
having a bottom or mounting side
22
, a top side
24
, and chips
40
. The chips
40
may be, for example, TIJ chips.
The bottom side
22
of the substrate
20
receives ink from the inkjet printer, and the top side
24
faces the media (e.g., paper) on which desired text or images are to be printed. A plurality of pockets
30
are cut into the substrate
20
, each pocket being designed to accommodate a chip
40
. Each of the pockets
30
may include an aperture
33
that provides a passage from the bottom side
22
to the top side
24
. Each of the pockets
30
may include first side profiles
32
formed in the pocket
30
. The chips
40
may include side profiles
46
that are complimentary to the side profiles
32
.
Each chip
40
also includes holes
49
through which ink drops are ejected through a top surface
44
, leads
52
to effectuate ink transfer, and a base surface
42
(illustrated in
FIG. 4B
) in contact with an ink supply (not shown). In
FIG. 1
, the chips
40
and the pockets
30
are shown with two conductive leads (two each of
52
and
50
, respectively). However, any number of wiring leads may be patterned on the chips
40
and on the substrate
20
at the pockets
30
. The leads
50
and
52
are electrically connected when the chips
40
are inserted in the substrate
20
. The leads
50
,
52
may be electrically connected by press fitting, or by applying solder
61
(see FIG.
2
). The leads
50
,
52
are used to route signals from one side of the substrate
20
to the other.
Seals
60
seal the peripheral gaps between the mounted chips
40
and the substrate
20
, and retain the chips
40
in the pockets
30
. The seals
60
may advantageously be made by a deposition process performed using localized energy. The deposition process creates hermetic seals
60
between the chips
40
and the substrate
20
. A seal
60
is discussed in detail below with reference to FIG.
2
.
FIG. 2
is a side cross-sectional view of a portion of the carrier
10
showing a seal
60
in a peripheral gap between a chip
40
and the substrate
20
. In
FIG. 2
, the seal
60
is illustrated as sealing the peripheral gap near the top side surface
24
and the bottom side surface
22
. Alternatively, the seal
60
can fill the entire peripheral gap between the chip
40
and the substrate
20
. The seal
60
forms a hermetic seal between the top side surface
24
and the bottom side surface
22
.
In the embodiment illustrated in
FIG. 2
, a heating device
70
is formed on the substrate
20
and a heating device
72
is formed on the chip
40
. The heating devices
70
,
72
may be, for example, small conductive elements known as “microheaters.” During a deposition process, current is passed through the heating devices
70
,
72
in order to heat the chip
40
and the substrate
20
at the peripheral gap. The heating devices
70
,
72
provide localized heat energy, which causes deposition gases to break down and to deposit seal material in the peripheral gap.
The seal
60
prevents ink from leaking through the peripheral gaps between the chips
40
and the substrate
20
. This feature is desirable because inks used in inkjet printers may be corrosive, and may damage the conductive leads
50
,
52
and other fixtures on the substrate
20
and on the chips
40
. If the chip
40
is an inkjet printhead (i.e., a TIJ chip), then sealing the peripheral gaps also prevents the chips
40
from being pushed out of the pockets
30
by ink (not shown) supplied to the chip
40
.
The seals
60
can be formed of corrosion resistant materials. For example, the seals
60
can be polysilicon deposited during an SiH
4
chemical vapor deposition (CVD) process. Other suitable deposition gases are discussed in detail below. The seals
60
can also be formed from deposited metals. Examples of suitable metals include aluminum, titanium, copper, platinum, tungsten, and other metals. The seals
60
may be formed in situ in the peripheral gap by local heating generated by the heating devices
70
,
72
. The use of local heating is desirable because portions of the carrier
10
may be sensitive to high temperatures. Local heating reduces the chance that components of the carrier
10
will be damaged during the deposition process. In other embodiments, localized energy for deposition may be provided using lasers.
FIGS. 3A and 3B
illustrate a possible arrangement for heating devices on the substrate
20
.
FIG. 3A
is a cross-sectional side view of a pocket
30
of the substrate
20
, and
FIG. 3B
is a plan view of the top side
24
of the substrate
20
surrounding the pocket
30
. The substrate
20
includes resistive heating devices
70
,
74
disposed on surfaces of the substrate
20
. A first heating device is
70
is patterned on the top side of the substrate
20
, and a second heating device
74
is patterned on a side profile
32
. The heating devices
70
,
74
include leads that connect to external power supplies (not shown). The heating devices
70
,
74
can be arranged in any configuration on the substrate
20
, and the configuration may vary according to the desired shape for the seal
60
.
The heating devices
70
,
74
can be formed by, for example, a patterning process. The heating devices
70
,
74
and the leads
50
can be formed using the same mask.
FIGS. 4A and 4B
illustrate a possible arrangement for heating devices on the chip
40
.
FIG. 4A
is a cross-sectional side view of a chip
40
, and
FIG. 4B
is a plan view of a base
42
of the chip
40
. The chip
40
includes a resistive heating device
72
formed on the base
42
of the chip
40
. The heating device
72
includes a lead that connects to an external power supply (not shown). The heating device
72
can be arranged in any configuration on the chip
40
, and the configuration may vary according to the desired shape for the seal
60
. The heating device
72
can be formed by, for example, a patterning process. The heating device
72
and the leads
52
can be formed using the same mask.
The number and arrangement of heating devices illustrated in
FIGS. 3A
,
3
B,
4
A, and
4
B is exemplary, and any configuration of heating devices can be utilized to obtain local heating at the peripheral gap between the chip
40
and the substrate
20
. For example, a single heating device disposed in the peripheral gap, on either the substrate
20
or the chip
40
, may be sufficient to form a seal
60
during a deposition process. Alternatively, a greater number of heating devices can be formed on the substrate
20
or the chip
40
to obtain a desired seal
60
configuration. In one embodiment, heating devices disposed within the peripheral gap can be activated early in the deposition process to fill a center portion of the peripheral gap with seal material. Subsequently, heating devices at the periphery of the peripheral gap can be activated to complete the seal
60
.
The heating devices illustrated in
FIGS. 3A
,
3
B,
4
A and
4
B can be, for example, microheaters. Microheaters may have a thickness on the order of, for example, 10 μm in the vicinity of the peripheral gap. The size of the leads to the microheaters increases away from the peripheral gap, to prevent heating outside of the region surrounding the peripheral gap.
The fabrication of the carrier
10
will now be discussed with reference to FIG.
2
. The following discussion describes the mounting of a single chip
40
within the substrate
20
. The carrier
10
can, however, include any number of chips
40
mounted in the substrate
20
.
The chip
40
is first inserted into a pocket
30
so that the conductors
50
on the substrate
20
contact the conductors
52
on the chip
40
. The conductors
50
,
52
are preferably coated with an insulative material, such as, for example, a dielectric, with a small amount of the insulative material removed where the conductors contact one another. After the chip
40
is inserted in the pocket
30
, the solder
61
is applied to electrically connect the conductors
50
,
52
. As an alternative to solder, the substrate
20
and the chip
40
can be held together under pressure during the fabrication process, with the conductors
50
,
52
correspondingly maintaining conductive contact while the seal
60
is formed.
Next, the carrier
10
is exposed to a deposition gas. The heating devices
70
,
72
are supplied with current during exposure to the deposition gas. The temperature of the heating devices
70
,
72
can be varied according to the desired shape of the seal
60
, the deposition gas used to form the seal
60
, and the number and arrangement of heating devices formed on the substrate
20
and/or the chip
40
.
The deposition gas can be silicon-containing gases such as, for example, SiH
4
, SiH
2
Cl
2
, and other gases. If SiH
4
is used, deposition can be achieved at a temperature of approximately 500 degrees C. The SiH
4
breaks down at this temperature and deposits a polysilicon seal
60
in the peripheral gap. Other deposition gases, such as, for example SiH
4
, may also be used to form a silicon-containing seal
60
. The seal
60
may be deposited using, for example, chemical vapor deposition (CVD), photon assisted CVD, laser assisted CVD and other deposition processes.
The seal
60
may also be formed of a metal, such as, for example, aluminum, titanium, copper, platinum, tungsten, and other metals. Deposition gases and temperatures recognized in the art can be used to deposit seals containing the above metals. The seal
60
may be deposited using, for example, metal organic chemical vapor deposition (MOCVD), and other deposition processes.
During deposition, the heating devices
70
,
72
are maintained at the desired temperature while the seal
60
is deposited in the peripheral gap.
As an alternative to heating devices, one or more lasers may be aimed at the peripheral gap to provide local heating at the peripheral gap during the deposition process. This is known as “laser-assisted CVD.” The lasers can include, for example, an array of lasers capable of heating the peripheral gap to the desired deposition temperature. As another alternative, lasers could be used to break down the deposition gas during deposition, a process known as “photon-assisted CVD.” Laser-assisted CVD and photon-assisted CVD can also be used together, and in combination with heating devices. Either laser-assisted CVD or photon-assisted CVD can be used alone to provide localized energy for deposition, in which case heating devices would be unnecessary.
The seal
60
formed during the deposition process is hermetic, and prevents ink from leaking through the peripheral gap between the TIJ chip
40
and the substrate
20
. The seal
60
may also be formed from materials that are generally resistant to ink, and to other corrosive materials. The use of a localized energy source reduces the chance that components of the carrier
10
will be damaged during deposition.
In
FIG. 1
, a plurality of pockets
30
for mounting the chips
40
are illustrated. However, the carrier
10
can include a single pocket
30
for mounting one TIJ chip
40
. Alternatively, and as shown, the self-aligned carrier
10
can include a plurality of pockets
30
in which a plurality of chips
40
may be mounted.
While the above embodiments are discussed with reference to a carrier
10
suitable for use in an inkjet printer, the seal
60
may be advantageously employed in any seal process. For example, the seal
60
may be used in any application where a chip is bonded to a substrate. Further, the carrier
10
an be an assembly or subassembly for use in an electronic device.
While the carrier
10
is described with reference to exemplary embodiments, many modifications will be readily apparent to those skilled in the art, and the present disclosure is intended to cover variations thereof.
Claims
- 1. A carrier for an electronic device, comprising:a substrate having at least one pocket formed in the substrate; at least one electronic chip, wherein the electronic chip is inserted into the pocket; and at least one seal, wherein the seal is disposed in at least one peripheral gap between the electronic chip and the substrate, and wherein the seal comprises: seal material deposited in the peripheral gap by one or more localized heating devices providing energy at the peripheral gap.
- 2. The carrier of claim 1, wherein the seal is deposited in the peripheral gap by local heating within the peripheral gap.
- 3. The carrier of claim 1, wherein the seal is deposited in the peripheral gap by local heating at a periphery of the peripheral gap.
- 4. The carrier of claim 1, wherein the seal is deposited in the peripheral gap by photon-assisted deposition at the peripheral gap.
- 5. The carrier of claim 1, wherein the seal comprises metal.
- 6. The carrier of claim 1, wherein the seal comprises silicon.
- 7. The carrier of claim 1, wherein the seal is deposited by a chemical vapor deposition process.
- 8. The carrier of claim 1, wherein the one or more heating devices are disposed on at least one of the electronic chip or the substrate, wherein heat emitted from the one or more heating devices is the energy, and wherein the heat is capable of raising a temperature of the peripheral gap to a deposition temperature of the seal.
- 9. The carrier of claim 8, wherein the heating device includes a conductive line connectable to a power source.
- 10. The carrier of claim 1, wherein the substrate comprises:first wiring patterned on the substrate at the pocket, wherein the chip comprises patterned second wiring electrically coupled to the first wiring.
- 11. The carrier of claim 1, wherein the chip is a thermal inkjet chip.
- 12. A method mounting a chip in a substrate, comprising:providing a substrate having at least one pocket; providing at least one electronic chip, wherein the electronic chip is shaped to be received by the substrate; inserting the electronic chip in the pocket; and providing one or more localized heating devices providing energy at at least one peripheral gap between the substrate and the electronic chip inserted in the pocket; and depositing seal material in the peripheral gap.
- 13. The method of claim 12, wherein the step of providing localized energy at a peripheral gap comprises:passing a current through at least one heating device disposed on at least one of the substrate and the electronic chip.
- 14. The method of claim 13, wherein the step of providing a substrate comprises:providing a substrate comprising the heating device.
- 15. The method of claim 13, wherein the step of providing an electronic chip comprises:providing a chip comprising the heating device.
- 16. The method of claim 12, wherein the step of providing one or more localized heating devices providing energy at a peripheral gap comprises:heating the peripheral gap with at least one laser.
- 17. The method of claim 12, wherein the step of providing one or more localized heating devices providing energy at a peripheral gap comprises:providing photonic energy to deposition gases at the peripheral gap.
- 18. A carrier for an electronic device, comprising:a substrate having at least one pocket formed in the substrate; at least one electronic chip, wherein the electronic chip is inserted in the pocket; at least one seal means for sealing at least one peripheral gap between the electronic chip and the substrate; and heating means for raising a temperature of the peripheral gap to a deposition temperature of the seal means.
- 19. The carrier of claim 18, wherein the seal means is deposited by a chemical vapor deposition process.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
5992769 |
Wise et al. |
Nov 1999 |
A |
6366468 |
Pan |
Apr 2002 |
B1 |
6402301 |
Powers et al. |
Jun 2002 |
B1 |