CN114864421A - Bonding process of deep Pad wafer and application thereof - Google Patents
Bonding process of deep Pad wafer and application thereof Download PDFInfo
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- CN114864421A CN114864421A CN202210488378.5A CN202210488378A CN114864421A CN 114864421 A CN114864421 A CN 114864421A CN 202210488378 A CN202210488378 A CN 202210488378A CN 114864421 A CN114864421 A CN 114864421A
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- 238000000034 method Methods 0.000 title claims abstract description 97
- 239000003292 glue Substances 0.000 claims abstract description 80
- 239000000758 substrate Substances 0.000 claims abstract description 63
- 239000011521 glass Substances 0.000 claims abstract description 48
- 238000010438 heat treatment Methods 0.000 claims description 56
- 238000005086 pumping Methods 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 8
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 4
- 229910052751 metal Inorganic materials 0.000 claims description 4
- 239000002184 metal Substances 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- 239000000463 material Substances 0.000 claims description 3
- 229910052710 silicon Inorganic materials 0.000 claims description 3
- 239000010703 silicon Substances 0.000 claims description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 2
- 239000000956 alloy Substances 0.000 claims description 2
- 229910052782 aluminium Inorganic materials 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 2
- 239000000919 ceramic Substances 0.000 claims description 2
- 229910052802 copper Inorganic materials 0.000 claims description 2
- 239000010949 copper Substances 0.000 claims description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 239000010931 gold Substances 0.000 claims description 2
- 239000007769 metal material Substances 0.000 claims description 2
- 229910052759 nickel Inorganic materials 0.000 claims description 2
- 238000002203 pretreatment Methods 0.000 claims description 2
- 239000004593 Epoxy Substances 0.000 claims 1
- 235000012431 wafers Nutrition 0.000 abstract description 104
- 238000007711 solidification Methods 0.000 abstract 1
- 230000008023 solidification Effects 0.000 abstract 1
- 239000003822 epoxy resin Substances 0.000 description 21
- 229920000647 polyepoxide Polymers 0.000 description 21
- 229940095676 wafer product Drugs 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 8
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- 238000004026 adhesive bonding Methods 0.000 description 6
- 230000001070 adhesive effect Effects 0.000 description 6
- 238000005516 engineering process Methods 0.000 description 5
- 230000010354 integration Effects 0.000 description 3
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- 230000002159 abnormal effect Effects 0.000 description 1
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- 238000007792 addition Methods 0.000 description 1
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- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000004100 electronic packaging Methods 0.000 description 1
- 229920006335 epoxy glue Polymers 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/60—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/56—Encapsulations, e.g. encapsulation layers, coatings
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/50—Assembly of semiconductor devices using processes or apparatus not provided for in a single one of the subgroups H01L21/06 - H01L21/326, e.g. sealing of a cap to a base of a container
- H01L21/60—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation
- H01L2021/60007—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation involving a soldering or an alloying process
- H01L2021/60015—Attaching or detaching leads or other conductive members, to be used for carrying current to or from the device in operation involving a soldering or an alloying process using plate connectors, e.g. layer, film
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- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Adhesives Or Adhesive Processes (AREA)
Abstract
The invention provides a bonding process of a deep Pad wafer and application thereof, wherein the bonding process comprises the steps of firstly contacting a glass substrate with bonding glue with the wafer, then carrying out pretreatment, and finally filling the bonding glue on the glass substrate into a Pad pit of the wafer and curing under the condition of temperature rise to complete bonding of the deep Pad wafer; the pretreatment comprises the steps of vacuumizing twice and breaking vacuum once, and air remained in the Pad pits is effectively removed before solidification, so that the problems of holes and residual glue of the solidified wafers are fundamentally avoided, the reject ratio of deep Pad bonded wafer products is reduced, the stability of the bonding process is improved, and a new process method is provided for bonding the deep Pad wafers.
Description
Technical Field
The invention belongs to the technical field of semiconductor processes, and particularly relates to a bonding process of a deep Pad wafer and application thereof.
Background
The miniaturization and multifunctional integration of integrated circuit processes and electronic components has driven the development of micro-electromechanical systems technology. The three-dimensional integration technology based on the through silicon via can greatly reduce the size of a chip and improve the interconnection density and the electrical performance by manufacturing vertical three-dimensional integration, and particularly has wide application prospects in the field of network big data and memory manufacturing, MEMS systems and the like. The permanent wafer bonding is a key technology for realizing three-dimensional stacking and interconnection in three-dimensional electronic packaging, the permanent bonding process reduces the occupied area and greatly improves the product performance, and the wafer-level glue bonding belongs to one type of wafer bonding with an intermediate layer, and the quality of bonding directly determines whether the subsequent process has the phenomena of corrosion and over-corrosion.
However, at present, the bonding process between the wafer-level packaging glass and the CIS wafer still has difficulties and challenges, and the wafer-level CIS glue bonding process is facing the challenges brought by the CIS front-end manufacturing process, in the CIS wafer, the logic chip circuit storage circuits are prepared beside and below the photosensitive area and are led out to the metal Pad beside the photosensitive area through the metal interconnection lines, and the Pad depths manufactured by different front-end processes are different.
The existing wafer level adhesive bonding technical scheme is mainly based on the traditional technology that a product is preheated, then vacuumized, heated and pressurized, then kept at a constant temperature and pressure, and finally cooled and depressurized. CN106298452A discloses a wafer bonding method based on array type point pressing, which includes: based on the traditional wafer bonding method, point pressure equipment is adopted, and the mode of bonding all points of a plane simultaneously in the traditional wafer bonding method is changed into the mode of bonding all points of the plane asynchronously and synchronously. The point pressure bonding method stated in the invention comprises the following steps: preparing a wafer to be bonded by using a hot-pressing bonding mode, selecting the size of a single bonding point of a point pressing device, dividing an area to be bonded into array points with equal size according to the size of the single bonding, and bonding at a certain temperature and under a certain pressure by using the point pressing device in the actual bonding process according to the array points. The point-pressure bonding equipment used by the invention has low manufacturing cost and simple operation, and in addition, the point-pressure bonding method has the characteristics of selectivity of a bonding area and the like, and can meet the requirements in certain specific application fields. Although the one-step temperature-raising direct bonding method adopted in the technology rarely causes the phenomena of cavities, bubbles and the like in the permanent bonding adhesive of the middle layer for the product with the wafer Pad depth of less than 1 micron, when the wafer Pad depth is more than 1 micron, the bubbles in the deep Pad cavity are difficult to control, and the bonding adhesive is difficult to be fully filled into the Pad pits within the limited bonding time before the bonding adhesive is cured, so that the quality of the bonded product is abnormal, and the appearance abnormality such as bubbles, residues or seepage exists, and the yield of the product is seriously influenced.
Therefore, it is an urgent technical problem to be solved in the art to develop a bonding process suitable for deep Pad wafers.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a bonding process of a deep Pad wafer and application thereof, wherein the bonding process effectively removes air in a Pad pit through two times of vacuum pumping and one time of vacuum breaking, fundamentally avoids the problems that cured bonding glue is easy to generate holes and residual glue, has high stability, and provides a new process method for glue bonding of the deep Pad wafer.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a bonding process for a deep Pad wafer, the bonding process comprising: contacting a glass substrate with bonding glue with a wafer, carrying out pretreatment, and filling the bonding glue on the glass substrate into a Pad pit of the wafer and curing under the condition of temperature rise to complete bonding of the deep Pad wafer;
the pretreatment method comprises the following steps: and sequentially carrying out primary vacuum pumping, vacuum breaking and secondary vacuum pumping on the system to finish the pretreatment.
In the bonding process provided by the invention, a glass substrate with a bonding paste is firstly contacted with a wafer (for example, the glass substrate with the bonding paste is contacted in a bonding cavity of a bonding machine, and then the system is subsequently vacuumized, which means the bonding cavity), and exemplarily, a structural schematic diagram of the glass substrate with the bonding paste before pretreatment in the bonding process provided by the invention is shown in fig. 1, wherein 1 represents the glass substrate, 2 represents a dam paste, the dam paste 2 is generally a photoresist, 3 represents the bonding paste, 4 represents the wafer substrate, 5 represents a Pad layer, 6 represents a photosensitive area, and 7 represents a Pad pit. The pretreatment is carried out after the contact, the pretreatment is mainly carried out to remove air in the Pad pit of the wafer, the subsequent bonding glue is prevented from being filled into the Pad pit and bubbles are generated in the curing process, for a deep Pad wafer, the effect of completely removing the bubbles cannot be achieved through single vacuumizing, therefore, two times of vacuumizing and one time of vacuum breaking are required, the system (bonding cavity) is in a certain vacuum state through the first vacuumizing, the Pad pit of the wafer is also in the vacuum state, the change of the vacuum degree is slow due to the fact that the Pad pit is sealed, the bubbles in the pit are discharged, the bonding cavity is rapidly restored to the atmospheric pressure through the vacuum breaking, the Pad pit of the wafer is still in the vacuum state, the wafer glue can reach the Pad pit under the action of pressure by utilizing pressure difference, the volume of the Pad pit is further reduced, and the gas in the Pad pit can be further extruded, finally, the second vacuumizing is performed, so that the extruded bubbles are further pumped away, and the generation of Pad bubbles in the subsequent bonding process is finally and fundamentally reduced or even avoided, so that the reject ratio of the glue bonding wafer product is reduced; after the pretreatment is finished, the direct holding system is subjected to further heating under a vacuum condition, so that the bonding glue on the glass substrate is further filled into the Pad pits of the wafer and cured to complete the bonding of the deep Pad wafer, and exemplarily, the structural schematic diagram of the contact between the glass substrate with the bonding glue and the wafer after the bonding process is completed is shown in fig. 2, wherein 1 represents the glass substrate, 2 represents the dam glue, the dam glue 2 generally adopts photoresist, 3 represents the bonding glue, 4 represents the wafer substrate, 5 represents the Pad layer, and 6 represents the photosensitive area, and as can be seen from fig. 2, the bonding glue 3 has been completely filled into the Pad pits of the wafer substrate 2.
It should be noted that, the "bonding process for deep Pad wafer" in the present invention refers to a wafer with Pad pits with a depth > l μm.
Preferably, the bonding glue comprises a two-component epoxy glue.
Preferably, the wafer comprises a wafer substrate and a Pad layer deposited in the wafer substrate pits.
Preferably, the wafer substrate comprises a silicon substrate, a ceramic substrate, a glass substrate or an integrated circuit chip substrate.
Preferably, the material of the Pad layer includes a metal material or an alloy material.
Preferably, the metal comprises any one of gold, copper, aluminum or nickel.
Preferably, the vacuum degree of the system after the first vacuum pumping is 1 to 200Pa, such as 20Pa, 40Pa, 60Pa, 80Pa, 100Pa, 120Pa, 140Pa, 160Pa or 180 Pa.
Preferably, the vacuum degree of the system after the second vacuum pumping is 0.01 to 1Pa, such as 0.05Pa, 0.1Pa, 0.2Pa, 0.3Pa, 0.4Pa, 0.5Pa, 0.6Pa, 0.7Pa, 0.8Pa or 0.9Pa, and the like.
Preferably, the pretreatment is carried out under heated conditions.
Preferably, the heating temperature is 30 to 35 ℃, for example, 30.5 ℃, 31 ℃, 31.5 ℃, 32 ℃, 32.5 ℃, 33 ℃, 33.5 ℃, 34 ℃ or 34.5 ℃.
As a preferable technical scheme of the invention, the pretreatment is carried out at the temperature of 30-35 ℃ to facilitate further extrusion of bubbles in the Pad pits, and the bonding adhesive can keep low viscosity to counteract the occurrence of adhesive residue caused by pressure difference after vacuum breaking.
Preferably, the temperature raising method is a staged temperature raising method.
Preferably, the step-wise temperature increasing method specifically includes: heating the system to 60-70 deg.C (such as 61 deg.C, 62 deg.C, 63 deg.C, 64 deg.C, 65 deg.C, 66 deg.C, 67 deg.C, 68 deg.C or 69 deg.C) for the first time, keeping the temperature for 1-3 min (such as 1.2min, 1.4min, 1.6min, 1.8min, 2min, 2.2min, 2.4min, 2.6min or 2.8 min), heating the system to not less than 90 deg.C (such as 91 deg.C, 92 deg.C, 93 deg.C, 94 deg.C, 95 deg.C, 96 deg.C, 97 deg.C, 98 deg.C or 99 deg.C) for the second time, keeping the temperature for not less than 15min (such as 16min, 17min, 18min, 19min, 20min, 21min, 22min, 23min, 24min or 25 min), and finishing the step-shaped heating.
As a preferred technical scheme of the invention, the bonding glue is filled into the Pad pits and is cured under the conditions of stepwise temperature rise and vacuum, and bonding is carried out under the condition of keeping vacuum, so that bubbles at the positions of the pits where the Pad is positioned in the wafer can be promoted to be discharged, and other additional chemical reactions can be prevented from being generated in the glue bonding process. Meanwhile, bonding is completed in a step-type heating mode, the system reaches 60-70 ℃ due to the first heating, the mobility and the activity of bonding glue are the best, the bonding machine can fill the bonding glue into the Pad pit, the time of the system at 60-70 ℃ is controlled to be 1-3 min, the problem that the flow speed of the bonding glue at the temperature is too high and then the bonding glue flows into a photosensitive area on a wafer to affect chip imaging can be avoided, and meanwhile, the bonding glue can be guaranteed to be completely filled into the Pad pit, and a cavity cannot be generated; and then, the temperature is raised to be higher than 90 ℃ for the second time, so that the bonding glue flowing into the Pad pit completely loses fluidity to achieve primary curing, and the time of keeping at 90 ℃ is kept for more than 15min to ensure that the curing is finished.
Preferably, the temperature rise rate of the first temperature rise is 10-20 ℃/min, such as 11 ℃/min, 12 ℃/min, 13 ℃/min, 14 ℃/min, 15 ℃/min, 16 ℃/min, 17 ℃/min, 18 ℃/min or 19 ℃/min, and the like.
As a preferred technical scheme of the invention, the temperature rise rate of the first temperature rise is 10-20 ℃/min, so that the bonding glue can be ensured to smoothly flow into the Pad pit, and the condition that the bonding glue on the whole cofferdam flows into the photosensitive area to cause pollution due to overhigh flow rate of the bonding glue is avoided.
Preferably, the temperature rise rate of the second temperature rise is 30-40 ℃/min, such as 31 ℃/min, 32 ℃/min, 33 ℃/min, 34 ℃/min, 35 ℃/min, 36 ℃/min, 37 ℃/min, 38 ℃/min or 39 ℃/min.
As a preferred technical solution, the bonding process includes: the method comprises the following steps of (1) carrying out pretreatment after contacting a glass substrate with bonding glue with a wafer, wherein the pretreatment comprises the following steps: carrying out first vacuum pumping on the system until the vacuum degree is 1-200 Pa, breaking the vacuum to enable the system to recover the atmospheric pressure, and carrying out second vacuum pumping until the vacuum degree is 0.01-1 Pa to finish the pretreatment; and then filling bonding glue on the glass substrate into Pad pits in the wafer and curing under the conditions of stepwise temperature rise and vacuum degree of 0.01-1 Pa, wherein the stepwise temperature rise method comprises the following steps: and heating the system to 60-70 ℃ for the first time, preserving heat for 1-3 min, heating the system to not less than 90 ℃ for the second time, preserving heat for not less than 15min, completing the step-type heating, and completing the bonding of the deep Pad wafer.
In a second aspect, the present invention provides a use of the deep Pad wafer bonding process of the first aspect in chip manufacturing.
Compared with the prior art, the invention has the following beneficial effects:
(1) the bonding process of the deep Pad wafer provided by the invention comprises the steps of firstly contacting a glass substrate with bonding glue with the wafer, then carrying out pretreatment, and finally filling the bonding glue on the glass substrate into a Pad pit of the wafer and curing under the condition of temperature rise to complete bonding of the deep Pad wafer; the pretreatment comprises the steps of vacuumizing twice and breaking vacuum once, so that the problems of holes and residual glue in the solidified wafer are fundamentally solved, the bonding process is high in stability and simple and convenient to operate, and the requirement of large-scale mass production can be met.
(2) As the preferred technical scheme of the invention, the bonding process adopts a staged heating mode and a pretreatment step, so that the traditional one-step heating bonding process is changed, the problems of glue overflow, glue residue, bubbles (holes) and the like which are easy to occur in the bonding process are solved, the glue overflow rate of the obtained bonded wafer product is as low as 0-2%, the glue residue rate is as low as 0-2%, and the bubble rate is as low as 1-4%, the yield of the product is effectively improved, and a new thought is provided for the bonding process of a deep Pad wafer (Pad depth is more than 1 mu m).
Drawings
FIG. 1 is a schematic view of a structure in which a glass substrate with bonding paste before pretreatment is in contact with a wafer in a bonding process according to the present invention;
FIG. 2 is a schematic structural view of a glass substrate with bonding paste contacting a wafer after the bonding process provided by the present invention is completed;
the manufacturing method comprises the following steps of 1-a glass substrate, 2-cofferdam glue, 3-bonding glue, 4-a wafer substrate, 5-Pad layers, 6-photosensitive areas and 7-Pad pits.
Detailed Description
The technical solution of the present invention is further explained by the following embodiments. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
Unless otherwise specified, in the detailed description, the specification and parameters of the devices such as the glass substrate and the wafer are the same.
Example 1
A bonding process of a deep Pad wafer specifically comprises the following steps:
(1) contacting a glass substrate with epoxy resin bonding glue and a wafer in a bonding cavity of a bonding machine, wherein the glass substrate with the epoxy resin bonding glue is positioned below the bonding cavity and directly contacted with a lower disc of the bonding machine, and then preprocessing is carried out in the bonding cavity, and the specific preprocessing operation comprises the following steps: setting the lower disc temperature to be 33 ℃, carrying out first vacuum pumping on the bonding cavity until the vacuum degree is 100Pa, breaking the vacuum to restore the standard atmospheric pressure of the bonding cavity, and carrying out second vacuum pumping on the bonding cavity until the vacuum degree is 0.5Pa to finish the pretreatment;
(2) keeping the vacuum degree at 0.5Pa, and filling (pushing the lower disc to the upper disc) the epoxy resin glue on the glass substrate into the Pad pit in the wafer and curing under the condition of the step-shaped temperature rise, wherein the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 65 ℃ for the first time according to the heating rate of 15 ℃/min, preserving the heat for 2min, heating the system to 90 ℃ for the second time according to the heating rate of 35 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Example 2
A bonding process of a deep Pad wafer specifically comprises the following steps:
(1) the glass substrate with the epoxy resin bonding glue is in contact with the wafer in a bonding cavity of a bonding machine, the glass substrate with the epoxy resin bonding glue is located below and directly in contact with a lower disc of the bonding machine, the wafer is clamped on a clamp of an upper disc, and then pretreatment is carried out, wherein the pretreatment specifically comprises the following steps: setting the lower disc temperature to be 30 ℃, carrying out first vacuum pumping on the bonding cavity until the vacuum degree is 200Pa, breaking the vacuum to restore the standard atmospheric pressure of the bonding cavity, and carrying out second vacuum pumping on the bonding cavity until the vacuum degree is 1Pa to finish the pretreatment;
(2) keeping the vacuum degree at 1Pa, and filling (pushing the lower disc to the upper disc) the epoxy resin glue on the glass substrate into a Pad pit in the wafer and curing under the condition of stepwise temperature rise, wherein the stepwise temperature rise method comprises the following steps: and (3) heating the system to 60 ℃ for the first time according to the heating rate of 10 ℃/min, preserving the heat for 3min, heating the system to 90 ℃ for the second time according to the heating rate of 30 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Example 3
A bonding process of a deep Pad wafer specifically comprises the following steps:
(1) the glass substrate with the epoxy resin bonding glue is in contact with the wafer in a bonding cavity of a bonding machine, the glass substrate with the epoxy resin bonding glue is located below and directly in contact with a lower disc of the bonding machine, the wafer is clamped on a clamp of an upper disc, and then pretreatment is carried out, wherein the pretreatment specifically comprises the following steps: setting the lower disc temperature to be 35 ℃, carrying out first vacuum pumping on the bonding cavity until the vacuum degree is 1Pa, breaking the vacuum to enable the bonding cavity to recover the standard atmospheric pressure, carrying out second vacuum pumping on the bonding cavity until the vacuum degree is 0.01Pa, and finishing the pretreatment;
(2) keeping the vacuum degree at 0.01Pa, and filling (pushing the lower disc to the upper disc) the epoxy resin glue on the glass substrate into the Pad pit in the wafer and curing under the condition of the step-shaped temperature rise, wherein the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 70 ℃ for the first time according to the heating rate of 20 ℃/min, preserving the heat for 1min, heating the system to 90 ℃ for the second time according to the heating rate of 40 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Example 4
A bonding process of a deep Pad wafer is different from that of the embodiment 1 only in that the temperature of a lower disc is set to be normal temperature during the pretreatment of the step (1), and other conditions and steps are the same as those of the embodiment 1.
Example 5
A bonding process of a deep Pad wafer is the same as that in the embodiment 1 in the step (1), and the difference is only that a step heating method is adopted to replace a staged heating method in the step (2), wherein the step heating method specifically comprises the following steps: and directly heating the system to 90 ℃ according to the heating rate of 35 ℃/min, and preserving the temperature for 15min to finish the bonding of the deep Pad wafer.
Example 6
A bonding process of a deep Pad wafer is disclosed, wherein the step (1) is the same as the embodiment 1, and the step (2) specifically comprises the following steps: keeping the vacuum degree to be 0.5Pa, and enabling the epoxy resin glue on the glass substrate to be filled into a Pad pit in a wafer and cured under the condition of step-shaped temperature rise, wherein the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 65 ℃ for the first time according to the heating rate of 35 ℃/min, preserving the heat for 2min, heating the system to 90 ℃ for the second time according to the heating rate of 35 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Example 7
A bonding process of a deep Pad wafer is disclosed, wherein the step (1) is the same as the step 1, the difference is only that the step (2) is subjected to stepwise temperature rise under the standard atmospheric pressure, the vacuum degree is not kept to be 0.5Pa, and other conditions and steps are the same as the step 1.
Comparative example 1
A bonding process of a deep Pad wafer specifically comprises the following steps: contacting a glass substrate with epoxy resin bonding glue with a wafer in a bonding cavity of a bonding machine, wherein the glass substrate with the epoxy resin bonding glue is positioned below and directly contacted with a lower disc of the bonding machine, the temperature of the lower disc is set to 55 ℃ for machine type preheating, then vacuumizing is carried out to enable the vacuum degree to be 0.5Pa, and the epoxy resin glue on the glass substrate is filled into a Pad pit in the wafer and cured under the condition of step-shaped temperature rise, and the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 65 ℃ for the first time according to the heating rate of 15 ℃/min, preserving the heat for 2min, heating the system to 90 ℃ for the second time according to the heating rate of 35 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Comparative example 2
A bonding process of a deep Pad wafer specifically comprises the following steps:
(1) contacting a glass substrate with epoxy resin bonding glue with a wafer in a bonding cavity of a bonding machine, wherein the glass substrate with the epoxy resin bonding glue is positioned at the lower side and directly contacted with a lower disc of the bonding machine, then setting the temperature of the lower disc to be 33 ℃, and vacuumizing the bonding cavity until the vacuum degree is 0.5 Pa;
(2) keeping the vacuum degree to be 0.5Pa, and filling the epoxy resin glue on the glass substrate into Pad pits in the wafer and curing under the condition of step-shaped temperature rise, wherein the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 65 ℃ for the first time according to the heating rate of 15 ℃/min, preserving the heat for 2min, heating the system to 90 ℃ for the second time according to the heating rate of 35 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Comparative example 3
A bonding process of a deep Pad wafer specifically comprises the following steps:
(1) contacting a glass substrate with epoxy resin bonding glue with a wafer in a bonding cavity of a bonding machine, wherein the glass substrate with the epoxy resin bonding glue is positioned at the lower side and directly contacted with a lower disc of the bonding machine, then setting the temperature of the lower disc to be 33 ℃, and vacuumizing the bonding cavity until the vacuum degree is 100 Pa;
(2) keeping the vacuum degree at 100Pa, and filling the epoxy resin glue on the glass substrate into Pad pits in the wafer and curing under the condition of step-shaped temperature rise, wherein the step-shaped temperature rise method comprises the following steps: and (3) heating the system to 65 ℃ for the first time according to the heating rate of 15 ℃/min, preserving the heat for 2min, heating the system to 90 ℃ for the second time according to the heating rate of 35 ℃/min, preserving the heat for 15min, and finishing the bonding of the deep Pad wafer.
Comparative example 4
A deep Pad wafer bonding process, comprising: and (3) contacting the glass substrate with the epoxy resin bonding glue with the wafer in a bonding cavity of a bonding machine, wherein the glass substrate with the epoxy resin bonding glue is positioned at the lower side and directly contacted with a lower disc of the bonding machine, then vacuumizing is carried out to enable the vacuum degree to be 0.5Pa, the system is heated to 90 ℃ for the second time according to the heating rate of 35 ℃/min, and the temperature is kept for 15min to complete the bonding of the deep Pad wafer.
And (3) performance testing:
(1) glue overflow, glue residue and air bubble conditions: detecting the notch of the wafer towards the 6 o' clock direction, selecting 9 regions, selecting 16 chips in each region, and observing the chips with glue overflow, glue residue and bubbles by adopting a polarized low power microscope (0.75X) and calculating the occupancy ratio of the chips.
The bonded wafer products prepared by the bonding processes provided in examples 1 to 7 and comparative examples 1 to 4 were tested according to the above test method, and the test results are shown in table 1:
TABLE 1
As can be seen from the data in table 1:
the bonded product obtained by the bonding process provided by the invention has less glue overflow, glue residue and air bubbles, and the yield of the product is effectively improved, specifically, the bonded wafer product prepared by the bonding process provided by the embodiments 1 to 7 has the glue overflow rate of 0 to 8%, the glue residue rate of 0 to 10% and the air bubble rate of 1 to 50%.
Comparing example 1 with comparative example 1, it can be seen that the glue overflow rate and the glue residue rate of the bonded wafer product obtained without the pretreatment step are both increased, and the bubble rate is greatly increased.
Comparing example 1 with comparative examples 2 to 3, it can be seen that the bubble rate of the bonded wafer product obtained by only performing one-time vacuum pumping is also greatly increased.
Comparing example 1 with comparative example 4, it can be seen that the bonded wafer product obtained by the conventional bonding process has a high residual adhesive rate and a bubble rate as high as 100%, indicating that the product yield is very low.
Further comparison of example 1 with example 4 shows that the absence of heat treatment during the pretreatment results in a slight increase in the bubble rate of the resulting product.
Further comparison of examples 1 and 5 shows that bonding with one step temperature increase after pretreatment results in slight increases in the yield of flash, residual and blister of the resulting wafer product.
Further comparing example 1 with example 6, it can be seen that bonding at a high temperature rise rate for the first time of the stepwise temperature rise results in an increase in the glue overflow rate and the glue residue rate of the obtained wafer product.
Finally, comparing example 1 with example 7, it can be seen that the absence of vacuum during the step-wise temperature increase increases the glue overflow rate, the glue residue rate, and the bubble rate of the finally bonded wafer product, and particularly affects the bubble rate.
In conclusion, the bonding process provided by the invention effectively eliminates the problems of holes and residual glue existing in the cured wafer, and the bonding process is further limited to adopt the step of stepwise heating to match with pretreatment, so that the glue overflow rate, the residual glue rate and the bubble rate of the obtained bonded wafer product are respectively as low as 0-2%, 0-2% and 1-4%.
The applicant states that the present invention is illustrated by the above embodiments of a deep Pad wafer bonding process and its application, but the present invention is not limited to the above process steps, i.e. it does not mean that the present invention must rely on the above process steps to be implemented. It will be apparent to those skilled in the art that any modification of the present invention, equivalent substitutions of selected materials and additions of auxiliary components, selection of specific modes and the like, which are within the scope and disclosure of the present invention, are contemplated by the present invention.
Claims (10)
1. A bonding process for a deep Pad wafer, the bonding process comprising: contacting a glass substrate with bonding glue with a wafer, carrying out pretreatment, and filling the bonding glue on the glass substrate into a Pad pit of the wafer and curing under the condition of temperature rise to complete bonding of the deep Pad wafer;
the pretreatment method comprises the following steps: and sequentially carrying out primary vacuum pumping, vacuum breaking and secondary vacuum pumping on the system to finish the pretreatment.
2. The bonding process of claim 1, wherein the bonding paste comprises a two-part epoxy paste.
3. The bonding process of claim 1 or 2, wherein the wafer comprises a wafer substrate and a Pad layer deposited in a pocket of the wafer substrate.
4. The bonding process of claim 3, wherein the wafer substrate comprises a silicon substrate, a ceramic substrate, a glass substrate, or an integrated circuit chip substrate.
5. The bonding process according to claim 3 or 4, wherein the material of the Pad layer comprises a metallic material or an alloy material;
preferably, the metal comprises any one of gold, copper, aluminum or nickel.
6. The bonding process according to any one of claims 1 to 5, wherein the degree of vacuum of the system after the first evacuation is 1 to 200 Pa;
preferably, the vacuum degree of the system after the second vacuumizing is 0.01-1 Pa;
preferably, the pretreatment is carried out under heated conditions;
preferably, the heating temperature is 30-35 ℃.
7. The bonding process according to any one of claims 1 to 6, wherein the temperature is raised in a stepwise manner;
preferably, the step-wise temperature increasing method specifically includes: and (3) heating the system to 60-70 ℃ for the first time, preserving the heat for 1-3 min, heating the system to not less than 90 ℃ for the second time, preserving the heat for not less than 15min, and completing the step-type heating.
8. The bonding process according to claim 7, wherein the first temperature rise rate is 10-20 ℃/min;
preferably, the temperature rise rate of the second temperature rise is 30-40 ℃/min.
9. The bonding process according to any one of claims 1 to 8, wherein the bonding process comprises: the method comprises the following steps of (1) pre-treating a glass substrate with bonding glue after the glass substrate is contacted with a wafer, wherein the pre-treating method comprises the following steps: performing first vacuum pumping on the system until the vacuum degree is 1-200 Pa, breaking the vacuum to restore the atmospheric pressure of the system, and performing second vacuum pumping on the system until the vacuum degree is 0.01-1 Pa to finish the pretreatment; and then keeping the vacuum degree of the system at 0.01-1 Pa, and filling the bonding glue on the glass substrate into a Pad pit in the wafer and curing the bonding glue under the condition of step-type temperature rise, wherein the step-type temperature rise method specifically comprises the following steps of: and (3) heating the system to 60-70 ℃ for the first time according to the heating rate of 10-20 ℃/min, preserving heat for 1-3 min, heating the system to not less than 90 ℃ for the second time according to the heating rate of 30-40 ℃/min, preserving heat for not less than 15min, and completing bonding of the deep Pad wafer.
10. Use of a deep Pad wafer bonding process according to any of claims 1 to 9 in chip manufacturing.
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