Wafer temporary bonding and de-bonding method, wafer thinning method and temporary bonding carrier plate

Abstract

The invention discloses a wafer temporary bonding and de-bonding method, which comprises the following steps of: providing a light-transmitting temporary support plate when a wafer is temporarily bonded; generating a first release layer on the temporary support plate, wherein the first release layer is of a heat release debonding or photolysis bonding structure; a second release layer is generated on the first release layer, the second release layer is of a solvent dissolution type de-bonding structure, and a heat-resistant shading material is arranged in the second release layer to prevent light from penetrating; temporarily bonding a wafer on the second release layer; when the wafer is de-bonded, laser or ultraviolet light passes through the temporary carrier plate to act on the first release layer, so that the first release layer is heated under the action of the laser or the ultraviolet light to lose viscosity to realize de-bonding or is subjected to photolysis under the action of the laser or the ultraviolet light; the second release layer on the wafer is removed using a solvent. The invention also provides a wafer thinning method and a temporary bonding carrier. The wafer surface is easy to clean while the wafer surface is prevented from being affected by the laser heat effect.

Description

Technical Field

[0001] The present invention relates to semiconductor manufacturing, and particularly to temporary bonding and debonding of wafers. Background Art

[0002] In recent years, with the rapid development of 5G, artificial intelligence, Internet of Things, autonomous driving, and big data, electronic devices are developing towards the direction of multi-function, high bandwidth, and low power consumption. In order to achieve high performance of electronic devices, semiconductor companies have taken the lead in developing 2.5D and 3D advanced packaging technologies (such as interposer, through-silicon via, multi-layer stacking, package-on-package) for mass production, and temporary bonding is one of the most critical processes among them. Initially, engineers developed temporary bonding and debonding processes by referring to the MEMS permanent bonding process, aiming to fix and protect ultra-thin wafers or reduce warping caused by EMC. The temporary bonding and debonding process TBDB (Temporary Bonding&De-bonding) mainly has four categories: thermal slip method, wet chemical immersion method, mechanical peeling method, and photolytic debonding method. This article mainly analyzes the popular photolytic debonding method for 2.5D 300mm wafers and proposes a novel optimization scheme based on mass-produced materials on the market.

[0003] In 2.5D applications, the main purpose of the TBDB (Temporary Bonding&De-Bonding) process developed by most OSAT (Outsourced Semiconductor Assembly and Test) is to fix and protect ultra-thin wafers, and the TBDB process for protecting wafers generally has the following problems: 1. Complicated process: In the debonding process of the vast majority of 300mm 2.5D processes of OSAT, plasma is required to remove the residual release layer, and the entire debonding will be divided into 2 to 3 steps, including debonding, plasma cleaning, and solvent cleaning; 2. Yield loss: Due to the chemical resistance of the bonding layer (including the release layer and the bonding adhesive), especially the release layer, and the difficulty of solvent cleaning after debonding cannot be achieved at the same time, the yield loss comes from the residual glue of the bonding layer on the wafer during debonding; 3. Cost increase: In order to isolate the influence of laser, the traditional method uses a PVD (Physical Vapor Deposition) metal layer as an isolation layer, thus increasing the PVD process and subsequent cleaning costs; 4. Reliability impact: Due to the certain light transmittance of the traditional release layer to laser, the laser penetrates the release layer and the bonding adhesive, which will generate a thermal effect on the wafer, thus bringing a negative impact on reliability.

[0004] Therefore, there is an urgent need for a wafer temporary bonding, debonding, and thinning method and device that can solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide a wafer temporary bonding, debonding, and thinning method and a temporary bonding carrier, which can avoid the negative impact of laser thermal effects on the reliability of the wafer surface and facilitate the cleaning of the wafer surface during the temporary bonding and debonding processes.

[0006] To achieve the above object, the present invention provides a wafer temporary bonding and debonding method, including: when temporarily bonding a wafer, providing a light-transmissive temporary carrier; generating a first release layer on the temporary carrier, the first release layer being a thermal release debonding or photo-debonding structure; generating a second release layer on the first release layer, the second release layer being a solvent dissolution debonding structure, and a heat-resistant light-shielding material being provided in the second release layer to block light from passing through; temporarily bonding the wafer on the second release layer; when debonding the wafer, using laser or ultraviolet light to pass through the temporary carrier and act on the first release layer, so that the first release layer loses its adhesiveness due to heating under the action of laser or ultraviolet light to achieve debonding or undergoes photo-debonding under the action of laser or ultraviolet light; and using a solvent to remove the second release layer on the wafer.

[0007] Preferably, the heat tolerance of the first release layer is greater than or equal to 200 degrees Celsius. This solution enables the first release layer to have sufficient heat resistance, so that after temporary bonding, when processing the wafer, the first release layer has high corrosion resistance and heat resistance.

[0008] Preferably, the light transmittance of the first release layer to 355 nm laser is 0.6% ± 0.05%, and the light transmittance to 532 nm laser is 20% ± 1%.

[0009] Preferably, the light transmittance of the second release layer to 355 nm, 532 nm, or 1064 nm laser is less than 1%.

[0010] Preferably, the heat-resistant light-shielding material of the second release layer is a combination of one or more of carbon black and amorphous silicon. This solution enables the second release layer to have high light-shielding efficiency, low cost, and good heat resistance.

[0011] Preferably, the first release layer includes a thermosetting resin and a heat-generating agent that generates heat under the action of laser or ultraviolet light. The laser or ultraviolet light passes through the temporary carrier and acts on the first release layer, causing the first release layer to carbonize due to heating under the action of laser or ultraviolet light to achieve debonding. This solution enables the first release layer to have good heat resistance and can also be carbonized under the action of laser or ultraviolet light, facilitating the dissociation and removal of the first release layer.

[0012] Specifically, the thickness of the first release layer is less than or equal to 0.25 um. The laser passes through the temporary carrier and irradiates the first release layer multiple times at intervals of half the spot distance, causing the first release layer to heat up and be completely carbonized into powder under the irradiation of the laser or ultraviolet light, and then it is cleaned thoroughly with liquid. This solution uses excessive laser irradiation to completely carbonize the first release layer, which is convenient for thorough cleaning and prevents residues on the wafer after debonding. The liquid can be pure water, or other cleaning liquids, or even the solvent of the second release layer.

[0013] More specifically, the thickness of the first release layer is less than or equal to 0.25 um, and a laser with a wavelength of 355 nm or 532 nm and a power adjusted to 1.5 to 2 times the reference power is used to irradiate at intervals of half the spot distance multiple times, so that the first release layer is carbonized into powder. While preventing the wafer from overheating, complete powderization of the first release layer is achieved, eliminating the need for plasma cleaning.

[0014] Specifically, the main materials of the first release layer are phenolic resin and a thermal acid generator, which have a low cost and can be completely carbonized into powder. Of course, the phenolic resin can be replaced by other thermosetting resins, and the thermal acid generator can also be replaced by other materials that can generate rapid heat under laser or ultraviolet light.

[0015] Specifically, the second release layer includes a combination of one or more of styrene, polymers of acrylic acid, and ethylene glycol monobutyl ether, as well as a heat-resistant light-shielding material. Styrene, polymers of acrylic acid, and ethylene glycol monobutyl ether are used as adhesives. The use of adhesives is not limited to the above materials, and the specific selection of adhesives can be made by those skilled in the art according to actual needs to select materials that can be used as temporary bonding adhesives and are easily soluble in chemical solvents.

[0016] Preferably, a wafer is temporarily bonded to the second release layer through a solvent-dissolvable debonding adhesive layer; after removing the second release layer on the wafer with a solvent, the temporary bonding adhesive layer is also cleaned with a solvent, or while removing the second release layer on the wafer with a solvent, the temporary bonding adhesive layer is also cleaned with a solvent. This solution allows the second release layer to be selected from materials with sufficient viscosity or non-viscous materials, and the second release layer can be made very thin, and then a temporary bonding adhesive is used as the binder for temporary bonding. The optional materials are wider, for example, materials with better corrosion and heat resistance can be selected as the temporary bonding adhesive. The selection of temporary bonding adhesives in the semiconductor field is well-known to those skilled in the art and will not be listed one by one here.

[0017] Preferably, when the second release layer is formed, the edge of the second release layer is also trimmed; the specific process of temporarily bonding the wafer to the temporary bonding adhesive layer dissolved by a solvent on the second release layer includes: forming a temporary bonding adhesive layer on the second release layer, and fully wrapping the second release layer between the temporary bonding adhesive layer and the first release layer; temporarily bonding the wafer to the temporary bonding adhesive layer. This solution prevents the second release layer from being corroded during wafer processing.

[0018] Preferably, the specific process of forming the temporary bonding adhesive layer includes: coating a temporary bonding adhesive on the bonding surface of the second release layer on the temporary carrier plate, then trimming the edge of the coating, and then baking to form the temporary bonding adhesive layer, reducing the degree of erosion of the temporary bonding adhesive layer during wafer processing.

[0019] Preferably, the chemical solvent types of the second release layer and the temporary bonding adhesive layer are different; after removing the second release layer on the wafer with a first solvent, a second solvent is also used to remove the temporary bonding adhesive layer on the wafer. This solution can not only increase the corrosion resistance after the wafer is temporarily bonded to the temporary carrier plate, but also make the second release layer and the temporary bonding adhesive layer cleaner.

[0020] Preferably, the thickness of the second release layer is 2um, and the thickness of the temporary bonding adhesive layer is 20um - 150um. In this solution, the thickness of the second release layer is very thin, and it is easy to clean even if there is a light-shielding material that is not easily dissolved. The presence of the temporary bonding adhesive layer makes the temporary bonding of the wafer more stable, and a bonding adhesive that is easily chemically cleaned can be used as the temporary bonding adhesive layer, which can be made relatively thick.

[0021] Preferably, when the first release layer is formed, baking is also performed to fully cure the first release layer.

[0022] The present invention also provides a wafer thinning method, including: temporarily bonding the first temporary carrier plate to the first bonding surface of the wafer away from the substrate using the above-mentioned wafer temporary bonding and debonding method; grinding and thinning the substrate on the second bonding surface of the wafer; temporarily bonding the second temporary carrier plate to the thinned second bonding surface of the wafer using the above-mentioned wafer temporary bonding and debonding method; and debonding the first temporary carrier plate from the first bonding surface of the wafer using the above-mentioned wafer temporary bonding and debonding method.

[0023] The present invention also provides a wafer temporary bonding carrier plate, including: a temporary carrier plate; a first release layer formed on the temporary carrier plate, the first release layer being a thermal release debonding or photolytic debonding structure; a second release layer formed on the first release layer, the second release layer being a solvent dissolution debonding structure, and a heat-resistant light-shielding material is provided in the second release layer to block light from passing through.

[0024] Preferably, the temporary bonding carrier for the wafer further includes: a temporary bonding adhesive layer formed on the second release layer, and the temporary bonding adhesive layer is a solvent-dissolved debonding structure. This solution enables the second release layer to be made of a material with sufficient viscosity or a non-viscous material, and enables the second release layer to be set very thin, and then uses a temporary bonding adhesive as the binder for temporary bonding. The selectable materials are wider. For example, a material with better corrosion and heat resistance can be selected as the material for the temporary bonding adhesive layer. The selection of temporary bonding adhesives in the semiconductor field is well-known to those skilled in the art and will not be listed one by one here.

[0025] Specifically, the second release layer completely wraps between the temporary bonding adhesive layer and the first release layer. This solution enables the second release layer not to be eroded by chemical agents during wafer processing.

[0026] Specifically, the wafer is temporarily bonded to the temporary carrier through the temporary bonding adhesive layer that is debonded by solvent dissolution on the second release layer, and the chemical solvent types of the second release layer and the temporary bonding adhesive layer are different. This solution can not only increase the corrosion resistance after the wafer is temporarily bonded to the temporary carrier, but also enable the second release layer and the temporary bonding adhesive layer to be cleaned more thoroughly. Of course, the binders selected in the second release layer and the temporary bonding adhesive layer can be the same, so that the solvent types of the second release layer and the temporary bonding adhesive layer are the same. At this time, when debonding, the second release layer and the temporary bonding adhesive layer can be dissolved separately in different containers or dissolved in the same container.

[0027] More preferably, the thickness of the second release layer is 2um, and the thickness of the temporary bonding adhesive layer is 20um - 150um. In this solution, the thickness of the second release layer is very thin, and even if there is a light-shielding material that is not easily dissolved, it is easy to clean. The existence of the temporary bonding adhesive layer makes the temporary bonding of the wafer more stable, and an easily chemically cleanable bonding adhesive can be used as the material for the temporary bonding adhesive layer, which can be made relatively thick. The second release layer for light shielding is relatively thin, which not only has a low cost, but also does not affect the stability of temporary bonding due to excessive light-shielding materials, and uses the temporary bonding adhesive layer to play the role of temporary pasting.

[0028] Preferably, the heat tolerance of the first release layer is greater than or equal to 200 degrees Celsius. This solution enables the first release layer to have sufficient heat resistance, so that during wafer processing after temporary bonding, the first release layer has high corrosion resistance and heat resistance.

[0029] Preferably, the light transmittance of the first release layer to 355nm laser is 0.6% ± 0.05%, and the light transmittance to 532nm laser is 20% ± 1%.

[0030] Preferably, the light transmittance of the second release layer to 355nm, 532nm or 1064nm laser is less than 1%.

[0031] Preferably, the heat-resistant light-shielding material of the second release layer is a combination of one or more of carbon black and amorphous silicon. This solution enables the second release layer to have high light-shielding efficiency, low cost, and good heat resistance.

[0032] Preferably, the main material of the first release layer is a thermosetting resin and a heat generator that generates heat under the action of laser or ultraviolet light, so that the first release layer can be carbonized by heating under the action of laser or ultraviolet light to release the bonding. This solution enables the first release layer to have good heat resistance while also being carbonized under the action of laser or ultraviolet light, facilitating the dissociation and removal of the first release layer.

[0033] Specifically, the main material of the first release layer is phenolic resin and a heat acid generator, which has low cost and can be completely carbonized into powder. Of course, phenolic resin can be replaced by other thermosetting resins, and the heat acid generator can also be replaced by other materials that can generate rapid heat under laser or ultraviolet light.

[0034] Preferably, the second release layer includes a combination of one or more of styrene, a polymer of acrylic acid, and ethylene glycol monobutyl ether, as well as a heat-resistant light-shielding material, and is extremely easy to clean. Styrene, a polymer of acrylic acid, and ethylene glycol monobutyl ether are used as adhesives. The use of adhesives is not limited to the above materials, and the selection of this specific adhesive can be made by those skilled in the art according to actual needs to select materials that can be used as temporary bonding adhesives and are soluble in chemical solvents.

[0035] Compared with the prior art, the present invention uses the first release layer and the second release layer with different debonding methods as the medium during temporary bonding. The first release layer has a structure that can be photo-debonded, and the second release layer has a light-shielding and protective structure. During photo-debonding, the second release layer can effectively protect the wafer, prevent high-transmittance light from damaging the wafer surface, and avoid the negative impact of laser thermal effects on the reliability of the wafer surface. The second release layer can be debonded by being dissolved in a solvent, enabling the second release layer to be debonded by chemical solvent cleaning to complete the temporary bonding debonding, which is easy to clean. Description of the Drawings

[0036] Figure 1 is a flowchart of the temporary bonding method in Embodiment 1 of the present invention.

[0037] Figure 2 is a partial flowchart of the wafer thinning method in Embodiment 1 of the present invention.

[0038] Figure 3 is a flowchart of the temporary debonding method in the wafer thinning method in Embodiment 1 of the present invention.

[0039] Figure 4 is a structural diagram of the temporary bonding carrier in Embodiment 1 of the present invention.

[0040] Figure 5 It is a flowchart of the temporary bonding method in Embodiment 2 of the present invention.

[0041] Figure 6 It is a partial flowchart of the wafer thinning method in Embodiment 2 of the present invention.

[0042] Figure 7 It is a flowchart of the temporary debonding method in the wafer thinning method in Embodiment 2 of the present invention.

[0043] Figure 8 It is a structural diagram of the temporary bonding carrier in Embodiment 2 of the present invention. Detailed implementation manners

[0044] To describe in detail the technical content, structural features, achieved objectives and effects of the present invention, the following is described in detail in conjunction with the implementation manners and with reference to the drawings.

[0045] Embodiment 1: Refer to Figure 2 and Figure 3 , the present invention discloses a wafer thinning method, which includes steps S100 to S400.

[0046] In S100, the wafer 200 is temporarily bonded to the first temporary bonding carrier 100a by using a temporary bonding method, so that the first temporary bonding carrier 100a is temporarily bonded to the first bonding surface of the wafer 200 away from the substrate.

[0047] In S200, the substrate on the second bonding surface of the wafer 200 is ground and thinned to obtain a thinned wafer 200a.

[0048] Of course, after the substrate is ground and thinned, other backside processes of the silicon wafer such as copper exposed TSV Reveal, Polyimide and C4 Bump processes can also be included to fabricate the exposed wafer 200 into a chip. Specifically, the backside processes of the silicon wafer include but are not limited to one or more processes in the process flows such as Si grinding (grinding wheel grinding and thinning), CMP (chemical mechanical polishing), Silicon recess etch (silicon etching), CVD (chemical vapor deposition), Cu protrusion (copper exposure), Photo patterning (lithography patterning), plating (electroplating), Strip (photoresist stripping), Wet Etch (wet etching), Reflow (reflow soldering), etc. In this embodiment, the wafer is thinned to 30 - 100um and the C4 bump process is completed.

[0049] S300 uses a temporary bonding method to temporarily bond the thinned second bonding surface of the thinned wafer 200a to the second temporary bonding carrier 100a.

[0050] S400 uses a temporary debonding method to debond and separate the first bonding surface of the thinned wafer 200a and the first temporary bonding carrier 100a.

[0051] Reference Figure 1 , the temporary bonding method includes steps S11 to S15.

[0052] S11, provide a light-transmitting temporary carrier 10. Among them, the temporary carrier 10 can be a glass carrier or other light-transmitting and high-temperature-resistant carriers.

[0053] S12, generate a first release layer 11 on the temporary carrier 10, and the first release layer 11 is a thermal release debonding or photolytic debonding structure.

[0054] The thermal tolerance of the first release layer 11 is greater than or equal to 200 degrees Celsius, the light transmittance of the first release layer 11 to 355nm laser is 0.6% ± 0.05%, and the light transmittance to 532nm laser is 20% ± 1%; the light transmittance of the second release layer 12 to 355nm, 532nm or 1064nm laser is less than 1%.

[0055]

[0056] Table 1 The above Table 1 is the anti-chemical property test results of the first release layer 11 in different environments. It can be seen from it that the first release layer 11 is a release layer with high anti-chemical and heat resistance and will not be corroded and peeled off in most environments.

[0057] Generating the first release layer 11 on the temporary carrier 10 specifically includes: coating the material of the first release layer on the bonding surface of the temporary carrier 10 and baking it to generate the first release layer 11. The coating is carried out by spin coating or spraying, and the thickness of the first release layer 1 after baking is 0.25um (the recommended value of TOK is 0.33um), the light transmittance to 355nm laser is 0.6%, and the light transmittance to 532nm laser is 20%. During baking, a one-hour atmospheric baking at 320°C once is carried out to achieve complete curing to generate the first release layer 11.

[0058] The first release layer 11 includes a thermosetting resin and a heat generator that generates heat under the action of laser or ultraviolet light. Specifically, the main materials of the first release layer 11 are phenolic resin and a heat acid generator, which have low cost and can be completely carbonized into powder. Of course, the phenolic resin can be replaced by other thermosetting resins, and the heat acid generator can also be replaced by other materials that can generate rapid heat under laser or ultraviolet light. In one embodiment, the first release layer 11 is composed of phenolic resin and a heat acid generator.

[0059] S13, a second release layer 12 is formed on the first release layer 11. The second release layer 12 is a solvent-dissolved debonding structure, and a heat-resistant light-shielding material is provided in the second release layer 12 to block light from passing through.

[0060] Forming the second release layer 12 on the first release layer 11 specifically includes: coating the material of the second release layer on the surface of the first release layer 11 formed on the temporary carrier 10, and baking to form the second release layer 12.

[0061] The second release layer 12 includes a combination of one or more of styrene, a polymer of acrylic acid, ethylene glycol monobutyl ether, and a heat-resistant light-shielding material. The second release layer 12 is dissolved in ammonia water or PGMEA. Styrene, a polymer of acrylic acid, and ethylene glycol monobutyl ether are used as adhesives. The use of adhesives is not limited to the above materials, and the selection of specific adhesives can be made by those skilled in the art according to actual needs to select materials that can be used as temporary bonding adhesives and are dissolved in chemical solvents.

[0062] Among them, the heat-resistant light-shielding material of the second release layer 12 is a combination of one or more of carbon black, amorphous silicon, etc. The heat-resistant light-shielding material can be a light-absorbing material, a light-reflecting material, or a combination of a light-absorbing material and a light-reflecting material.

[0063] Among them, the second release layer 12 is a solvent-dissolved release layer, which can be quickly dissolved in ammonia water or PGMEA. The coating is carried out by spin coating or spraying; the baking is carried out by soft baking at 200°C for ten minutes once. The thickness of the second release layer 12 after baking is 2um. The second release layer 12 can absorb more than 99% of the laser light with wavelengths of 355nm, 532nm, or 1064nm on the market, and the light transmittance is far less than 1%.

[0064] In this embodiment, the thickness of the second release layer 12 is 2um. In the second release layer 12, the weight ratio of the heat-resistant light-shielding material is between 2% and 10%. When the heat-resistant light-shielding material is composed of carbon black and amorphous silicon, the weight ratio of carbon black is between 1% and 5%, and the weight ratio of amorphous silicon is between 1% and 5%.

[0065] Preferably, during the material coating process of the second release layer 12, edge trimming is also required. In this embodiment, a spin coater and developer are specifically used to clean the material of the second release layer within 0 - 3 mm from the edge of the wafer, so as to reduce the corrosion degree during the subsequent wafer thinning process.

[0066] S14, a temporary bonding adhesive layer 13 is formed on the second release layer 12.

[0067] Specifically, a temporary bonding adhesive is coated on the bonding surface of the temporary bonding carrier 100 where the second release layer 12 is located, and then baked to form the temporary bonding adhesive layer 13.

[0068] Among them, the temporary bonding adhesive is a high chemical - and heat - resistant glue that can be dissolved in a specific solvent. The coating is carried out by spin coating or spraying. The baking conditions are step - temperature baking. For example, baking is performed at 90 °C, 160 °C, and 220 °C respectively for a total of 4 minutes. The thickness of the temporary bonding adhesive layer 13 after baking is 20 um - 150 um. Of course, the specific thickness of the temporary bonding adhesive layer 13 can be set according to actual needs. For example, it can be set according to the determined u - bump height, and is not limited to the above values.

[0069]

[0070] Table 2 The above Table 2 shows the chemical resistance test results of the second release layer 12 and the temporary bonding adhesive layer 13 under different environments.

[0071] Preferably, forming the temporary bonding adhesive layer 13 specifically includes: coating a temporary bonding adhesive on the bonding surface of the temporary carrier 10 where the second release layer 12 is located, then performing edge trimming on the coated edge, and then baking to form the temporary bonding adhesive layer 13, so as to reduce the degree of erosion of the temporary bonding adhesive layer 13 during the processing of the wafer 200.

[0072] Preferably, since the second release layer 12 in this embodiment is made very thin, in order to prevent the second release layer from being corroded, during the formation of the second release layer 12, edge trimming is performed on the coated edge of the second release layer 12, so that there is a gap between the edge of the second release layer 12 and the edge of the first release layer 11, and the edge of the second release layer 12 is shorter than the edge of the first release layer 11. Then, when forming the temporary bonding adhesive layer 13, the temporary bonding adhesive layer 13 is wrapped around the top and the periphery of the second release layer 12, so that the second release layer 12 is completely wrapped between the temporary bonding adhesive layer 13 and the first release layer 11.

[0073] Preferably, the chemical solvent types of the second release layer 12 and the temporary bonding adhesive layer 13 are different; after removing the second release layer 12 on the wafer 200 using a first solvent (ammonia water or PGMEA - propylene glycol methyl ether acetate), a second solvent is also used to remove the temporary bonding adhesive layer 13 on the wafer 200. The second solvent is a specific solvent. After using the first solvent to clean the heat - resistant light - shielding material that is not soluble in the second release layer 12, the specific second solvent is used to clean the temporary bonding adhesive layer 13, with good cleaning effect, no residue, no contamination of the wafer by the heat - resistant light - shielding material, and the second solvent can be reused.

[0074] In this way, the temporary bonding carrier 100a in the first embodiment is generated.

[0075] S15, temporarily bond the wafer 200 to the temporary bonding adhesive layer 13.

[0076] In this embodiment, the wafer 200 is temporarily bonded by the temporary bonding adhesive layer 13 that is de - bonded by solvent dissolution on the second release layer 12.

[0077] Preferably, the temporary bonding is carried out in a sealed vacuum environment. Before temporary bonding, the wafer 200 and the temporary carrier 10 are heated to a preset temperature, then a preset pressure is applied for a first preset time, and then baking is carried out at a second preset temperature for a second preset duration to release stress.

[0078] Specifically, the temporary bonding process between the wafer 200 and the temporary bonding adhesive layer 13 is completed in a sealed cavity with a vacuum degree of 0.01 mPa. The wafer 200 and the temporary carrier 10 need to be heated to 215°C, and a pressure of 4000 kgf is applied on one side of the wafer 200 or the temporary carrier 10. The bonding time is 2.5 minutes. After bonding, baking at 220°C for about 5 minutes is required to release stress.

[0079] Reference Figure 3 , the temporary de - bonding method includes: S21, use a laser or ultraviolet light to pass through the temporary carrier 10 and act on the first release layer 11, so that the first release layer 11 loses its viscosity due to heating under the action of the laser or ultraviolet light to achieve de - bonding or undergoes photolysis under the action of the laser.

[0080] Among them, the laser or ultraviolet light is irradiated from the side of the temporary carrier 10 away from the wafer 200. The first release layer on the temporary carrier 10 loses its viscosity due to chemical decomposition under the irradiation of the laser and ultraviolet light, thereby dissociating the thinned wafer 200a from the temporary carrier 10.

[0081] Among them, the first release layer 11 includes a thermosetting resin and a heat generating agent that generates heat under the action of laser or ultraviolet light. The laser or ultraviolet light passes through the temporary carrier 10 and acts on the first release layer 11, causing the first release layer 11 to heat and carbonize under the action of the laser or ultraviolet light to release the bonding. This solution enables the first release layer 11 to have good heat resistance while also being able to carbonize under the action of laser or ultraviolet light, facilitating the dissociation and removal of the first release layer 11.

[0082] Preferably, in this embodiment, the thickness of the first release layer 11 is less than or equal to 0.25 μm. The laser passes through the temporary carrier 10 and irradiates the first release layer 11 multiple times at intervals of half a spot distance difference, causing the first release layer 11 to heat and completely carbonize into powder under the irradiation of the laser or ultraviolet light, and then cleaning it with liquid. This liquid can be pure water or other liquids. This solution enables the first release layer 11 to be directly and completely cleaned with pure water, eliminating the need for plasma slag removal process and plasma cleaning. Of course, the first release layer 11 can also not be cleaned separately, but directly cleaned together with the powder residue left after the dissociation of the first release layer 11 by the cleaning solvent of the second release layer 12 when cleaning the second release layer 12. Among them, the arranged laser array irradiates the first release layer 11 for a preset duration at one time, and then after a period of time, the laser array is moved by a distance of half a spot and irradiates the first release layer 11 for the preset duration again, and this interval irradiation is carried out more than 2 times to complete the powdering of the first release layer 11. The number of times of laser irradiation on the first release layer 11 is determined according to actual needs and is not limited to 2 times. Among them, the number of irradiation times is preferably 2 - 4 times. The more the number of irradiation times, the shorter the duration of each irradiation.

[0083] In this preferred embodiment, the first release layer 11 is completely carbonized, which can effectively prevent the first release layer from remaining on the wafer surface with a certain probability during the subsequent cleaning of the second release layer 12 and the temporary bonding adhesive layer 13 below due to the high chemical resistance of the first release layer 11 after the release of the bonding.

[0084] In this preferred embodiment, the first release layer 11 needs to be completely carbonized by excessive laser. The excessive laser can be absorbed by the second release layer 12 and will not burn through the wafer 200. Therefore, there will be a small amount of carbonization of the second release layer 12, but due to the low chemical resistance of the second release layer 12, it can be cleaned with pure water, other cleaning liquids, or even the solvent of the second release layer 12.

[0085] More specifically, the thickness of the first release layer 11 is less than or equal to 0.25 um, and it is irradiated multiple times at intervals of half a spot distance difference using a laser with a wavelength of 355 nm or 532 nm and a power adjusted to 1.5 to 2 times the reference power, so that the first release layer 11 is carbonized into powder. While preventing the wafer 200 from overheating, complete powderization of the first release layer 11 is achieved. Of course, the specific selection of the laser is not limited to this, as long as it can ensure complete carbonization of the first release layer 11. The specific thickness of the first release layer 11 can also be selected according to actual needs and is not limited to the above specific values.

[0086] S22, use a first solvent to remove the second release layer 12 on the wafer 200.

[0087] Specifically, use a first solvent to wash away the second release layer 12 on the wafer 200.

[0088] S23, use a second solvent to remove the temporary release adhesive layer 13 on the wafer 200.

[0089] Of course, the above method for temporary bonding and debonding of the wafer 200 is not limited to wafer thinning and can also be used in processes such as temporary transfer and packaging of the wafer 200.

[0090] Reference Figure 4 , the temporary bonding carrier 100 generated during the temporary bonding process of the above wafer 200 includes a temporary carrier plate 10, a first release layer 11 formed on the temporary carrier plate 10, a second release layer 12 formed on the first release layer 11, and a temporary bonding adhesive layer 13 formed on the second release layer 12. The first release layer 11 is a thermal release or photo release debonding structure; the second release layer 12 is a solvent dissolution debonding structure, and a heat-resistant light-blocking material is provided in the second release layer 12 to block light from passing through. The temporary bonding adhesive layer 13 is a solvent dissolution debonding structure.

[0091] The specific structural parameters of the first release layer 11, the second release layer 12, and the temporary bonding adhesive layer 13 are as described above and will not be repeated here.

[0092] Example 2: Reference Figure 6 And Figure 7 , the present invention discloses a wafer thinning method, including steps S100 to S400.

[0093] S100, use a temporary bonding method to temporarily bond the wafer 200 to the first temporary bonding carrier 100, so that the first temporary bonding carrier 100 is temporarily bonded to the first bonding surface of the wafer 200 away from the substrate.

[0094] S200 grinds and thins the substrate on the second bonding surface of the wafer 200 to obtain a thinned wafer 200a.

[0095] Of course, after the substrate is ground and thinned, it may also include backside processes of the silicon wafer such as copper TSV Reveal, Polyimide, and C4 Bump processes, etc., to fabricate the exposed wafer 200 into a chip. The specific backside processes of the silicon wafer can be the same as those in Embodiment 1 and will not be repeated here.

[0096] S300 uses a temporary bonding method to temporarily bond the thinned second bonding surface of the thinned wafer 200a to the second temporary bonding carrier 100.

[0097] S400 uses a temporary debonding method to debond and separate the first bonding surface of the thinned wafer 200a and the first temporary bonding carrier 100.

[0098] Reference Figure 5 , the temporary bonding method includes: S11, providing a light-transmissive temporary carrier 10. Among them, the temporary carrier 10 can be a glass carrier or other light-transmissive and high-temperature-resistant carriers.

[0099] S12, generating a first release layer 11 on the temporary carrier 10, and the first release layer 11 is a thermal release debonding or photo-debonding structure.

[0100] The thermal tolerance of the first release layer 11 is greater than or equal to 200 degrees Celsius. The light transmittance of the first release layer 11 to 355 nm laser is 0.6% ± 0.05%, and the light transmittance to 532 nm laser is 20% ± 1%.

[0101]

[0102] Table 1 The above table shows the chemical resistance of the first release layer 11 under different test environments. It can be seen that the first release layer 11 is a release layer with high chemical and heat resistance and will not be corroded and peeled off in most environments.

[0103] Generating the first release layer 11 on the temporary carrier 10 specifically includes: coating the material of the first release layer on the bonding surface of the temporary carrier 10 and baking it to generate the first release layer 11. The coating is carried out by spin coating or spraying. The thickness of the first release layer 1 after baking is 0.25 um (the recommended value of TOK is 0.33 um), the light transmittance to 355 nm laser is 0.6%, and the light transmittance to 532 nm laser is 20%. During baking, a one-hour atmospheric baking at 320 °C is used once to achieve complete curing to generate the first release layer 11.

[0104] The first release layer 11 includes a thermosetting resin and a heat generator that generates heat under the action of laser or ultraviolet light. Specifically, the main materials of the first release layer 11 are phenolic resin and a thermal acid generator, which have low cost and can be completely carbonized into powder. Of course, the phenolic aldehyde resin can be replaced by other thermosetting resins, and the thermal acid generator can also be replaced by other materials that can generate rapid heat under laser or ultraviolet light. In one embodiment, the first release layer 11 is composed of phenolic resin and a thermal acid generator.

[0105] S13a, a second release layer 12a is formed on the first release layer 11. The second release layer 12a is a solvent-dissolved debonding structure, and a heat-resistant light-shielding material is provided in the second release layer 12a to block light from passing through.

[0106] In this way, the temporary bonding carrier 100 in the first embodiment is generated.

[0107] Forming the second release layer 12a on the first release layer 11 specifically includes: coating the material of the second release layer on the surface of the first release layer 11 formed on the temporary carrier 10, and baking to form the second release layer 12a.

[0108] Among them, the second release layer 12a is a solvent-dissolved release layer, which can be quickly dissolved in ammonia water or PGMEA. The coating is carried out by spin coating or spraying; the baking is carried out by one or multiple bakings, such as multiple temperature-gradual soft baking. The second release layer 12a can achieve an absorption of more than 99% for lasers of 355 nm, 532 nm or 1064 nm on the market, and the light transmittance is far less than 1%.

[0109] The second release layer 12a includes a combination of one or more of styrene, polymers of acrylic acid, ethylene glycol monobutyl ether, and a heat-resistant light-shielding material. Above, the second release layer 12a is dissolved in ammonia water or PGMEA. Styrene, polymers of acrylic acid, and ethylene glycol monobutyl ether are used as adhesives. The use of adhesives is not limited to the above materials, and the selection of specific adhesives can be made by those skilled in the art according to actual needs to select materials that can be used as temporary bonding adhesives and dissolved in chemical solvents.

[0110] Among them, the heat-resistant light-shielding material of the second release layer 12a is a combination of one or more of carbon black, amorphous silicon, etc. The heat-resistant light-shielding material can be a light-absorbing material, a light-reflecting material, or a combination of a light-absorbing material and a light-reflecting material.

[0111] In this embodiment, the thickness of the second release layer 12a after baking is 40 - 65 um. In this embodiment, the temporary bonding adhesive layer 13 is omitted, and the function of the temporary bonding adhesive layer 13 is replaced by using a thicker and sufficiently viscous second release layer 12a, so that the second release layer 12a is made thicker and the light-shielding effect is better.

[0112] Preferably, during the material coating process of the second release layer 12a, edge trimming treatment is also required. In this embodiment, a spin coater and developer are specifically used to clean the material of the second release layer within 0-3 mm from the wafer edge, so as to reduce the corrosion degree during the subsequent wafer thinning process.

[0113] S14a, temporarily bond the wafer 200 on the second release layer 12a.

[0114] The wafer 200 is temporarily bonded on the second release layer 12a through a temporary bonding adhesive layer 13 that is de-bonded by solvent dissolution.

[0115] The temporary bonding method in step S14a is the same as step S15 in Embodiment 1 and will not be repeated here.

[0116] Above, the temporary bonding between the temporary bonding carrier 100 and the wafer 200 is completed.

[0117] Reference Figure 7 , the temporary de-bonding method includes: S21, use a laser or ultraviolet light to pass through the temporary carrier 10 and act on the first release layer 11, so that the first release layer 11 loses its adhesiveness due to heating under the action of the laser or ultraviolet light to achieve de-bonding or undergoes photolysis under the action of the laser or ultraviolet light.

[0118] Wherein, the first release layer 11 includes a thermosetting resin and a heat generating agent that generates heat under the action of a laser or ultraviolet light. The laser or ultraviolet light passes through the temporary carrier 10 and acts on the first release layer 11, causing the first release layer 11 to be carbonized by heating under the action of the laser or ultraviolet light to achieve de-bonding. This solution enables the first release layer 11 to have good heat resistance while also being carbonized under the action of a laser or ultraviolet light, facilitating the dissociation and removal of the first release layer 11.

[0119] Preferably, in this embodiment, the thickness of the first release layer 11 is less than or equal to 0.25 um. The laser passes through the temporary carrier 10 and irradiates the first release layer 11 multiple times at intervals of half a spot distance, causing the first release layer 11 to heat up and be completely carbonized into powder under the irradiation of the laser or ultraviolet light, and then cleaning it completely with liquid. This liquid can be pure water or other liquids. This solution enables the first release layer 11 to be completely cleaned directly with pure water, eliminating the need for a plasma slag removal process or plasma cleaning. Of course, the first release layer 11 can also not be cleaned separately, but directly when cleaning the second release layer 12a, the powder residue left after the dissociation of the first release layer 11 is cleaned together with the cleaning solvent of the second release layer 12a. Among them, the arranged laser array irradiates the first release layer 11 for a preset duration once, and then after a period of time, the laser array is moved by a distance of half a spot and irradiates the first release layer 11 for the preset duration again, and this interval irradiation is carried out more than 2 times to complete the powdering of the first release layer 11. The number of irradiation times is preferably 2 - 4 times. The more the number of irradiation times, the shorter the duration of each irradiation.

[0120] In this preferred embodiment, the first release layer 11 is completely carbonized, which can effectively prevent the first release layer from remaining on the wafer surface with a certain probability during the subsequent cleaning of the second release layer 12 and the temporary bonding adhesive layer 13 below it due to the high chemical resistance of the first release layer 11 after debonding.

[0121] In this preferred embodiment, the first release layer 11 needs to be completely carbonized by excessive laser. The excessive laser can be absorbed by the second release layer 12 and will not burn through the wafer 200. Therefore, a small amount of carbonization will occur in the second release layer 12, but due to the low chemical resistance of the second release layer 12, it can be cleaned with pure water, other cleaning liquids, or even the solvent of the second release layer 12.

[0122] More specifically, the thickness of the first release layer 11 is less than or equal to 0.25 um, and a laser with a wavelength of 355 nm or 532 nm and a power adjusted to 1.5 - 2 times the reference power irradiates at intervals of half a spot distance multiple times to carbonize the first release layer 11 into powder. While preventing the wafer 200 from overheating, complete powdering of the first release layer 11 is achieved. Of course, the specific selection of the laser is not limited to this, as long as it can ensure complete carbonization of the first release layer 11. The specific thickness of the first release layer 11 can also be selected according to actual needs and is not limited to the above specific values.

[0123] S22a, removing the second release layer 12a on the wafer 200 using a solvent.

[0124] Specifically, the second release layer 12a on the wafer 200 is cleaned using a solvent of ammonia water or PGMEA.

[0125] Of course, the above method for temporary bonding and debonding of the wafer 200 is not limited to wafer thinning, and can also be used for processes such as temporary transfer and packaging of the wafer 200.

[0126] Reference Figure 8 , the temporary bonding carrier 100 generated during the temporary bonding process of the wafer 200 as described above includes a temporary carrier plate 10, a first release layer 11 formed on the temporary carrier plate 10, and a second release layer 12a formed on the first release layer 11. The first release layer 11 is a thermal release debonding or photo-debonding structure; the second release layer 12a is a solvent dissolution debonding structure, and a heat-resistant light-shielding material is provided in the second release layer 12a to block the laser from passing through.

[0127] The specific structural parameters of the first release layer 11 and the second release layer 12a are as described above and will not be repeated here.

[0128] The above-disclosed are only the preferred embodiments of the present invention. Of course, the scope of rights of the present invention cannot be limited thereby. Therefore, equivalent changes made according to the scope of the patent application of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for temporary bonding and debonding of wafers, characterized in that: Comprising: When temporarily bonding wafers, providing a light-transmissive temporary carrier; Generating a first release layer on the temporary carrier, the first release layer being a thermal release debonding or photo-debonding structure; Generating a second release layer on the first release layer, the second release layer being a solvent-dissolving debonding structure, and a heat-resistant light-blocking material being provided in the second release layer to block light from passing through; Temporarily bonding the wafer on the second release layer; When debonding the wafer, using a laser or ultraviolet light to pass through the temporary carrier and act on the first release layer, so that the first release layer loses its adhesiveness due to heating under the action of the laser or ultraviolet light to achieve debonding or undergoes photo-debonding under the action of the laser or ultraviolet light; Using a solvent to remove the second release layer on the wafer.

2. The temporary bonding and debonding method of a wafer according to claim 1, wherein: The thermal tolerance of the first release layer is greater than or equal to 200 °C, the thickness of the first release layer is less than or equal to 0.25 μm, the light transmittance of the first release layer to 355 nm laser is 0.6% ± 0.05%, and the light transmittance to 532 nm laser is 20% ± 1%; the light transmittance of the second release layer to 355 nm, 532 nm or 1064 nm laser is less than 1%.

3. The temporary bonding and debonding method of a wafer according to claim 1, characterized in that: The heat-resistant light-blocking material of the second release layer is a combination of one or more of carbon black and amorphous silicon.

4. The temporary bonding and debonding method of a wafer according to claim 1, characterized in that: The first release layer includes a thermosetting resin and a heat-generating agent that generates heat under the action of a laser or ultraviolet light. The laser passes through the temporary carrier and acts on the first release layer, causing the first release layer to heat and carbonize under the action of the laser or ultraviolet light to achieve debonding.

5. The temporary bonding and debonding method of a wafer according to claim 4, wherein: The thickness of the first release layer is less than or equal to 0.25 μm. The laser passes through the temporary carrier and irradiates the first release layer multiple times at intervals of half a spot distance difference, causing the first release layer to heat and completely carbonize into powder under the irradiation of the laser or ultraviolet light, and then cleaning it with liquid.

6. The temporary bonding and debonding method of a wafer according to claim 5, characterized in that: Using a laser with a wavelength of 355 nm or 532 nm and a power adjusted to 1.5 to 2 times the reference power to irradiate multiple times at intervals of half a spot distance difference, so that the first release layer carbonizes into powder.

7. The temporary bonding and debonding method of a wafer according to claim 4, wherein: The main material of the first release layer is phenolic resin and a heat-acid generating agent.

8. The temporary bonding and debonding method of the wafer according to claim 1, characterized in that: The second release layer includes a combination of one or more of styrene, a polymer of acrylic acid, and ethylene glycol monobutyl ether, and a heat-resistant light-blocking material.

9. The temporary bonding and debonding method of a wafer according to claim 1, characterized in that: The wafer is temporarily bonded on the second release layer through a temporary bonding adhesive layer that undergoes solvent-dissolving debonding; after using a solvent to remove the second release layer on the wafer, the temporary bonding adhesive layer is also cleaned with a solvent, or the temporary bonding adhesive layer is cleaned with a solvent while using a solvent to remove the second release layer on the wafer.

10. The method for temporarily bonding and debonding wafers according to claim 9, wherein: When generating the second release layer, edge trimming is also performed on the edge of the second release layer; The specific process of temporarily bonding the wafer on the second release layer through a temporary bonding adhesive layer that undergoes solvent-dissolving debonding includes: Generating a temporary bonding adhesive layer on the second release layer, and completely wrapping the second release layer between the temporary bonding adhesive layer and the first release layer; Temporarily bonding the wafer to the temporary bonding adhesive layer.

11. The temporary bonding and debonding method of a wafer according to claim 10, wherein: Generating a temporary bonding adhesive layer specifically includes: coating a temporary bonding adhesive on the bonding surface of the second release layer on the temporary carrier, then performing edge trimming on the coated edge, and then baking to generate a temporary bonding adhesive layer.

12. The temporary bonding and debonding method of a wafer according to claim 9, characterized in that: The chemical solvent types of the second release layer and the temporary bonding adhesive layer are different; after removing the second release layer on the wafer using a first solvent, a second solvent is also used to remove the temporary bonding adhesive layer on the wafer.

13. The temporary bonding and debonding method of a wafer as claimed in claim 9, wherein: The thickness of the second release layer is 2 um, and the thickness of the temporary bonding adhesive layer is 20 um to 150 um.

14. A wafer thinning method, characterized in that: Includes: Temporarily bonding a first temporary carrier to the first bonding surface of the wafer away from the substrate using the wafer temporary bonding and debonding method according to any one of claims 1 - 13; Grinding and thinning the substrate on the second bonding surface of the wafer; Temporarily bonding a second temporary carrier to the thinned second bonding surface of the wafer using the wafer temporary bonding and debonding method according to any one of claims 1 - 13; Debonding the first temporary carrier from the first bonding surface of the wafer using the wafer temporary bonding and debonding method according to any one of claims 1 - 13.

15. A temporary bonding carrier for a wafer, characterized in that: Includes: A temporary carrier; A first release layer formed on the temporary carrier, and the first release layer is a thermal release debonding or photo - release debonding structure; A second release layer formed on the first release layer, the second release layer is a solvent - dissolved debonding structure, and a heat - resistant light - shielding material is provided in the second release layer to block light from passing through.

16. The temporary bonding carrier for a wafer according to claim 15, wherein: Further includes: A temporary bonding adhesive layer formed on the second release layer, and the temporary bonding adhesive layer is a solvent - dissolved debonding structure.

17. The temporary bonding carrier for a wafer according to claim 16, characterized in that: The second release layer completely wraps between the temporary bonding adhesive layer and the first release layer.

18. The temporary bonding carrier for a wafer according to claim 16, wherein: The chemical solvent types of the second release layer and the temporary bonding adhesive layer are different.

19. The temporary bonding carrier for a wafer according to claim 16, wherein: The thickness of the second release layer is 2 um, and the thickness of the temporary bonding adhesive layer is 20 um to 150 um.

20. The temporary bonding carrier for a wafer according to claim 15, wherein: The thermal tolerance of the first release layer is greater than or equal to 200 degrees Celsius, the thickness of the first release layer is less than or equal to 0.25 um, the light transmittance of the first release layer to 355 nm laser is 0.6% ± 0.05%, and the light transmittance to 532 nm laser is 20% ± 1%; the light transmittance of the second release layer to 355 nm, 532 nm or 1064 nm laser is less than 1%.

21. The temporary bonding carrier for a wafer according to claim 15, wherein: The heat - resistant light - shielding material of the second release layer is a combination of one or more of carbon black and amorphous silicon.

22. The temporary wafer bonding carrier according to claim 15, wherein: The main material of the first release layer is a thermosetting resin and a heat - generating agent that generates heat under the action of laser or ultraviolet light, so that the first release layer can be heated and carbonized under the action of laser or ultraviolet light to debond.

23. The temporary bonding carrier for wafers according to claim 22, wherein: The main material of the first release layer is phenolic resin and a heat - generating acid agent.

24. The temporary bonding carrier for wafers according to claim 15, characterized in that: The second release layer includes a combination of one or more of styrene, a polymer of acrylic acid, and ethylene glycol monobutyl ether, and a heat - resistant light - shielding material.

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