Temporary bonding glue, preparation method thereof and wafer processing technology

Abstract

The invention discloses a temporary bonding adhesive, a preparation method thereof and a wafer processing technology, and belongs to the field of semiconductor packaging. The temporary bonding glue comprises 10 to 30 parts by weight of an ethylene-propylene-non-conjugated diene terpolymer, 1 to 10 parts by weight of a plasticizer and 70 to 90 parts by weight of a solvent. A corresponding non-conjugated diene monomer in the ethylene-propylene-non-conjugated diene terpolymer is prepared from at least one of 1, 4-butadiene, ethylidene norbornene, dicyclopentadiene, methyl cyclopentadiene, isoprene, 1, 4-hexadiene and 3-ethyl-1, 4-hexadiene, and a corresponding non-conjugated diene monomer in the ethylene-propylene-non-conjugated diene terpolymer is prepared from at least one of 1, 4-butadiene, ethylidene norbornene, dicyclopentadiene, methyl cyclopentadiene, isoprene, 1, 4-hexadiene and 3-ethyl-1, 4-hexadiene. The temporary bonding adhesive can be simultaneously applied to thermal slippage de-bonding and mechanical release de-bonding, realizes a two-in-one function of thermal debonding and mechanical debonding, and is excellent in coating uniformity, so that the film thickness of the temporary bonding adhesive is controllable.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor packaging, and particularly to a temporary bonding adhesive, a preparation method thereof, and a wafer processing technology. Background Art

[0002] Temporary bonding adhesives are usually used in temporary bonding / debonding technologies. For example, a temporary bonding adhesive is used to bond a wafer to be processed to a carrier wafer. Under the support of the carrier wafer, the wafer to be processed is processed to form a functional wafer, thereby ensuring that the wafer to be processed will not warp, bend, or even break.

[0003] After the processing of the wafer to be processed is completed, it is necessary to separate the corresponding functional wafer from the carrier wafer. The separation methods include thermal slip debonding and mechanical release debonding.

[0004] However, based on currently known temporary bonding adhesives, it is difficult for them to be simultaneously applied to thermal slip debonding and mechanical release debonding, and there is still room for improvement in terms of coating uniformity and film thickness control. Summary of the Invention

[0005] In view of this, the present invention provides a temporary bonding adhesive, a preparation method thereof, and a wafer processing technology, which can solve the technical problems existing in the related art.

[0006] Specifically, the technical solutions include the following:

[0007] On the one hand, a temporary bonding adhesive is provided. The temporary bonding adhesive includes: 10 parts by weight - 30 parts by weight of ethylene-propylene-non-conjugated diene terpolymer, 1 part by weight - 10 parts by weight of a plasticizer, and 70 parts by weight - 90 parts by weight of a solvent;

[0008] The non-conjugated diene monomer in the ethylene-propylene-non-conjugated diene terpolymer includes at least one of 1,4-butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4-hexadiene, and 3-ethyl-1,4-hexadiene.

[0009] In some possible implementation manners, the ethylene-propylene-non-conjugated diene terpolymer includes: an ethylene-propylene alternating copolymer chain segment, and the mass percentage of the ethylene monomer corresponding to the ethylene-propylene alternating copolymer chain segment is 40% - 80%, and the mass percentage of the propylene monomer corresponding thereto is 20% - 60%.

[0010] In some possible implementation manners, the ethylene-propylene-non-conjugated diene terpolymer further includes: a non-conjugated diene monomer chain segment, and the mass ratio of the ethylene-propylene alternating copolymer chain segment to the non-conjugated diene monomer chain segment is 2:1 - 5:1.

[0011] In some possible implementation manners, the weight-average molecular weight of the ethylene-propylene alternating copolymer segment is 2.0×10 5 -8.0×10 5 .

[0012] In some possible implementation manners, the weight-average molecular weight of the ethylene-propylene-non-conjugated diene terpolymer is 4.0×10 5 -9.0×10 5 , and the Mooney viscosity ML 1+4 / 125 °C of the ethylene-propylene-non-conjugated diene terpolymer is 50-100.

[0013] In some possible implementation manners, the plasticizer is selected from at least one of white oil, aromatic oil, dioctyl phthalate, dioctyl adipate, n-octyl sebacate, coumarone resin, and petroleum resin.

[0014] In some possible implementation manners, the solvent is selected from at least one of n-dodecene, isododecane, cyclohexanone, n-tetradecane, dimethylformamide, cyclohexane, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether, xylene, and propylene glycol methyl ether acetate.

[0015] On the other hand, a preparation method of a temporary bonding adhesive is provided, and the temporary bonding adhesive is as described in any one of the above;

[0016] The preparation method includes: mixing the plasticizer and the solvent evenly to obtain a mixed solution;

[0017] Under stirring conditions, adding an ethylene-propylene-non-conjugated diene terpolymer to the mixed solution and stirring until a clear and transparent liquid is formed to prepare the temporary bonding adhesive.

[0018] On yet another hand, a wafer processing process is provided, and the wafer processing process includes: based on the temporary bonding adhesive described in any one of the above, temporarily bonding a wafer to a carrier;

[0019] Processing the wafer to obtain a functional wafer;

[0020] Performing a debonding process on the functional wafer and the carrier to separate and obtain the functional wafer.

[0021] In some possible implementation manners, the debonding process is thermal slip debonding or mechanical release debonding.

[0022] The technical solutions provided by the embodiments of the present invention have at least the following beneficial effects:

[0023] The temporary bonding adhesive provided by the embodiments of the present invention uses 10 parts by weight - 30 parts by weight of ethylene - propylene - non - conjugated diene terpolymer as the main body of the bonding adhesive. The corresponding non - conjugated diene monomers include at least one of 1,4 - butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4 - hexadiene, and 3 - ethyl - 1,4 - hexadiene. This type of ethylene - propylene - non - conjugated diene terpolymer can withstand temperatures up to 300 °C, has excellent heat resistance, and can tolerate most organic solvents, acids, and bases, showing excellent chemical solvent tolerance. In addition, this type of ethylene - propylene - non - conjugated diene terpolymer also has excellent aging resistance, elasticity, and adhesiveness. The above properties enable the temporary bonding adhesive based on ethylene - propylene - non - conjugated diene terpolymer to have excellent high - temperature softening properties and room - temperature mechanical properties, allowing the temporary bonding adhesive to be applied to both thermal slip debonding and mechanical release debonding, realizing the dual functions of thermal debonding and mechanical debonding. On this basis, by using 1 part by weight - 10 parts by weight of plasticizer and 70 parts by weight - 90 parts by weight of solvent to act synergistically with the ethylene - propylene - non - conjugated diene terpolymer, the fluidity of the temporary bonding adhesive can be improved. This not only facilitates the application of the temporary bonding adhesive in thermal debonding and mechanical debonding, but also helps to improve its coating uniformity, making the film thickness more controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0025] Figure 1 It is a graph showing the change of the weight percentage of the temporary bonding adhesive provided in Example 1 with temperature;

[0026] Figure 2 It is a graph showing the change of the weight percentage of the temporary bonding adhesive provided in Example 2 with time under the condition of 260 °C. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the protection scope of the present invention.

[0028] With the rapid development of fields such as television, tablet computers, smartphones, and automotive electronics, the demand for semiconductor chips is also increasing continuously. Semiconductor devices are required to be faster and smaller accordingly. Therefore, the demand for wafer thinning is growing. Currently, the initial thickness of silicon wafers is usually several hundred micrometers. The purpose of thinning is to remove most of the bulk silicon on the back. Thinning the bulk silicon does not affect the electrical properties of the wafer, but it will significantly reduce the mechanical stability of the wafer. When the silicon wafer is thinned to less than 150 μm, residual stress will be generated during the process, and the mechanical strength will also decrease. Coupled with the influence of its own mass, the wafer exhibits significant flexibility and brittleness, and it is very easy to warp, bend, or even break.

[0029] In view of the above situation, a temporary bonding adhesive is usually used in the temporary bonding / delamination technology. The wafer to be processed is bonded to the carrier wafer by using the temporary bonding adhesive. Under the support of the carrier wafer, the wafer to be processed is processed to form a functional wafer, so as to ensure that the wafer to be processed will not warp, bend, or even break.

[0030] After the processing of the wafer to be processed is completed, it is necessary to separate the corresponding functional wafer from the carrier wafer. The separation methods include thermal slip delamination and mechanical release delamination.

[0031] Thermal slip delamination refers to a delamination process based on the characteristics of thermoplastic adhesives softening when heated and hardening when cooled. At a lower temperature, the viscosity and hardness of the thermoplastic adhesive are high. When the thermoplastic adhesive is heated above the delamination temperature, its viscosity and hardness are greatly reduced. At this time, the functional wafer can be separated from the temporary carrier (such as the above-mentioned carrier wafer) by slipping. However, thermal slip delamination has the following disadvantages: The delamination temperature is the highest temperature that the thermoplastic adhesive can withstand, which severely limits the thermal budget and results in the inability to implement many high-temperature wafer backside processes.

[0032] Mechanical release delamination refers to applying a tensile force perpendicular to the surface direction to the temporary bonding structure, so that the temporary carrier is peeled off from the surface of the functional wafer. However, mechanical delamination has the following disadvantages: It requires a special chuck system, making its operation complex. In addition, although a tensile force is applied to the temporary carrier during the delamination process, mechanical stress may still damage the circuit on the surface of the functional wafer.

[0033] Currently known temporary bonding adhesives, for example, the WaferBond and ZoneBond series products of Brewer Sciences, the LTHC series products of 3M, the HD-3000 series products of DuPont, the T-MAT series products of Thin Materials, the WL series products of DowCorning, the ZeroNewton series products of Tokyo Ohka Kogyo Co., Ltd. (TOK), the Cyclotene series products of Dow Chemical, etc., have different performances, and usually have one or more of the following problems: for example, they cannot maintain stability in high-temperature environments, thus having limited applications in thermal slip debonding; they cannot withstand certain chemical solvents, resulting in bonding failure; they cannot provide sufficient mechanical support, and the wafers are damaged during the peeling process, thus having limited applications in mechanical release debonding; it is difficult to achieve a uniform film thickness during the coating process, affecting the precision and quality of wafer processing.

[0034] It can be seen that based on currently known temporary bonding adhesives, it is very difficult to apply them to both thermal slip debonding and mechanical release debonding at the same time, and there is still room for improvement in terms of coating uniformity and film thickness control.

[0035] In view of the technical problems existing in the related art, an embodiment of the present invention provides a temporary bonding adhesive, which includes: 10 parts by weight - 30 parts by weight of ethylene-propylene-non-conjugated diene terpolymer, 1 part by weight - 10 parts by weight of plasticizer, and 70 parts by weight - 90 parts by weight of solvent. The non-conjugated diene monomer corresponding to the ethylene-propylene-non-conjugated diene terpolymer includes at least one of 1,4-butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4-hexadiene, 3-ethyl-1,4-hexadiene.

[0036] The temporary bonding adhesive provided by the embodiments of the present invention uses 10 to 30 parts by weight of ethylene-propylene-non-conjugated diene terpolymer as the main body of the bonding adhesive. The corresponding non-conjugated diene monomers include at least one of 1,4-butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4-hexadiene, and 3-ethyl-1,4-hexadiene. This type of ethylene-propylene-non-conjugated diene terpolymer can withstand temperatures up to 300°C, has excellent heat resistance, and can withstand most organic solvents, acids, and bases, with excellent chemical solvent tolerance. In addition, this type of ethylene-propylene-non-conjugated diene terpolymer also has excellent anti-aging properties, elasticity, and adhesiveness. The above properties enable the temporary bonding adhesive based on ethylene-propylene-non-conjugated diene terpolymer to have excellent high-temperature softening performance and room-temperature mechanical performance, enabling the temporary bonding adhesive to be applied to both thermal slip debonding and mechanical release debonding, achieving the dual functions of thermal debonding and mechanical debonding. On this basis, by using 1 to 10 parts by weight of a plasticizer and 70 to 90 parts by weight of a solvent to act synergistically with the ethylene-propylene-non-conjugated diene terpolymer, this can improve the fluidity of the temporary bonding adhesive, which is not only beneficial to the application of the temporary bonding adhesive in thermal debonding and mechanical debonding, but also beneficial to improving its coating uniformity, making the film thickness more controllable.

[0037] In the embodiments of the present invention, the ethylene-propylene-non-conjugated diene terpolymer is copolymerized from ethylene, propylene, and non-conjugated diene as monomers. Among them, the non-conjugated diene monomers involved include at least one of 1,4-butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4-hexadiene, and 3-ethyl-1,4-hexadiene. In some examples, dicyclopentadiene can be used as the non-conjugated diene monomer, which is more beneficial to the anti-aging, corrosion resistance, heat resistance, elasticity, and adhesiveness of the ethylene-propylene-non-conjugated diene terpolymer, making the high-temperature softening performance and room-temperature mechanical performance of the temporary bonding adhesive more excellent, thereby obtaining a more effective dual function of thermal debonding and mechanical debonding.

[0038] The ethylene-propylene-non-conjugated diene terpolymer includes ethylene-propylene alternating copolymer segments and non-conjugated diene monomer segments. Among them, the mass percentage of ethylene monomers corresponding to the ethylene-propylene alternating copolymer segments is 40% - 80%, further can be 50% - 70%, and the mass percentage of propylene monomers corresponding thereto is 20% - 60%, further can be 30% - 50%.

[0039] Regarding the content of ethylene monomer in the ethylene-propylene alternating copolymer segment, it has been found that when the mass percentage of ethylene is 50%-62%, due to the relatively long ethylene chain region or the relatively frequent occurrence of the ethylene chain region, it results in an amorphous structure. This causes the ethylene-propylene-non-conjugated diene terpolymer not to exhibit the crystallinity of ethylene above the glass transition temperature. Therefore, it has relatively low hardness and strength and is relatively soft. From the perspectives of thermal slip debonding and mechanical peeling debonding, this type of ethylene-propylene-non-conjugated diene terpolymer exhibits relatively low shear strength and tensile strength and is prone to slip or peeling phenomena. However, due to the existence of the amorphous structure, this type of ethylene-propylene-non-conjugated diene terpolymer may have the following defects: such as non-smooth surface or irregular shape, etc.

[0040] When the mass percentage of ethylene is 63%-67%, the ethylene-propylene-non-conjugated diene terpolymer has relatively low crystallinity at room temperature. However, it may exhibit a small amount of crystallinity at 40°C - 60°C. In this way, this type of ethylene-propylene-non-conjugated diene terpolymer may exhibit medium shear strength and tensile strength in terms of thermal slip debonding and mechanical peeling debonding. And due to the existence of a small amount of crystallinity, this type of ethylene-propylene-non-conjugated diene terpolymer has a certain rigidity and may exhibit higher crystallinity at higher temperatures, thereby improving the strength and stability of debonding.

[0041] When the mass percentage of ethylene is 68%-80%, the ethylene-propylene-non-conjugated diene terpolymer has relatively high raw rubber strength, vulcanized rubber tensile strength and toughness at room temperature. From the perspectives of thermal slip debonding and mechanical peeling debonding, the ethylene-propylene-non-conjugated diene terpolymer may exhibit relatively high shear strength and tensile strength, which may, to a certain extent, be disadvantageous to the implementation of thermal slip debonding and mechanical peeling debonding.

[0042] It can be seen that the embodiments of the present invention expect the mass percentage of the ethylene monomer corresponding to the ethylene-propylene alternating copolymer segment to be 40%-80%, preferably 50%-70%. This can not only ensure that the ethylene-propylene-non-conjugated diene terpolymer has suitable hardness and strength for the temporary bonding adhesive to avoid cracking or deformation, but also ensure that the ethylene-propylene-non-conjugated diene terpolymer forms a suitable crystal structure, thereby promoting its structural stability and excellent adhesion.

[0043] In the embodiments of the present invention, the mass ratio of the ethylene-propylene alternating copolymer segment to the non-conjugated diene monomer segment is 2:1 - 5:1, and further can be 2:1 - 4:1, which includes but is not limited to 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1, 4.1:1, 4.2:1, 4.3:1, 4.4:1, 4.5:1, 4.6:1, 4.7:1, 4.8:1, 4.9:1, 5:1, etc.

[0044] When the mass ratio of the ethylene-propylene alternating copolymer segment to the non-conjugated diene monomer segment is within the above range, it has excellent flexibility and elasticity, and ensures its tolerance in chemical solvents. In addition, it also exhibits good solubility, which brings convenience to its construction application and significantly improves the simplicity and efficiency of operation.

[0045] In the embodiments of the present invention, the weight-average molecular weight of the ethylene-propylene alternating copolymer segment is 2.0×10 5 - 8.0×10 5 , and further can be 4.0×10 5 - 6.0×10 5 . When the weight-average molecular weight of the ethylene-propylene alternating copolymer segment is within the above range, it has advantages such as good thermal stability and anti-aging ability.

[0046] For any of the ethylene-propylene-non-conjugated diene terpolymers involved above, in the embodiments of the present invention, the weight-average molecular weight of the ethylene-propylene-non-conjugated diene terpolymer is 4.0×10 5 - 9.0×10 5 , and further can be 5.0×10 5 - 8.0×10 5 . The Mooney viscosity ML 1+4 / 125 °C of the ethylene-propylene-non-conjugated diene terpolymer is 50 - 100 MU.

[0047] When the weight-average molecular weight of the ethylene-propylene-non-conjugated diene terpolymer is within the above range, it has the advantages of high mechanical strength and strong toughness, making it suitable for heat-resistant application scenarios with higher requirements, facilitating the molding and processing of the bonding adhesive, and improving production efficiency. At the same time, it also exhibits good chemical medium resistance. Moreover, when the Mooney viscosity of the ethylene-propylene-non-conjugated diene terpolymer is within the above range, it has good fluidity, adhesion performance, and anti-aging performance.

[0048] For any of the above-mentioned temporary bonding adhesives, the weight parts of the ethylene-propylene-non-conjugated diene terpolymer contained therein are 10 to 30 weight parts, and further can be 15 to 20 weight parts, which include but are not limited to: 10 weight parts, 11 weight parts, 12 weight parts, 13 weight parts, 14 weight parts, 15 weight parts, 16 weight parts, 17 weight parts, 18 weight parts, 19 weight parts, 20 weight parts, 21 weight parts, 22 weight parts, 23 weight parts, 24 weight parts, 25 weight parts, 26 weight parts, 27 weight parts, 28 weight parts, 29 weight parts, 30 weight parts, etc.

[0049] In some examples, the plasticizer involved in the embodiments of the present invention is selected from at least one of white oil, aromatic oil, dioctyl phthalate, dioctyl adipate, n-octyl sebacate, coumarone resin, and petroleum resin.

[0050] The embodiments of the present invention have at least the following advantages by using the above types of plasticizers: reducing the viscosity of the temporary bonding adhesive, reducing the brittle temperature of the temporary bonding adhesive, improving the fluidity of the temporary bonding adhesive, and making the temporary bonding adhesive soft, etc.

[0051] Among them, the weight parts of the plasticizer are 1 to 10 weight parts, and further can be 2 to 5 weight parts, which include but are not limited to: 1 weight part, 2 weight parts, 3 weight parts, 4 weight parts, 5 weight parts, 6 weight parts, 7 weight parts, 8 weight parts, 9 weight parts, 10 weight parts, etc.

[0052] When the content of the plasticizer is within the above range, the above-mentioned advantages can be achieved. Moreover, when the dosage of the plasticizer increases, the viscosity of the temporary bonding adhesive will be correspondingly reduced, and the fluidity will be better.

[0053] In some examples, the plasticizer can be a mixture of n-octyl sebacate and dioctyl phthalate, and the mass ratio of n-octyl sebacate to dioctyl phthalate can be 1:1 to 5:1, and further can be 3:1 to 4:1, so as to achieve better effects.

[0054] The choice of solvent in the embodiments of the present invention not only determines the solubility of the resin and the plasticizer, but also directly affects the spin coating process of the bonding adhesive and the final technical effect. Especially in the formulation of solid resin, if no solvent is added, even if there is a plasticizer, it is impossible to form a suitable spin-coatable glue state. This will result in the inability to perform spin coating on the surface of the silicon wafer, and thus the technical effect cannot be effectively evaluated.

[0055] Considering the following various factors, including but not limited to: compatibility, solubility, volatility, toxicity, cost, etc. Based on the types of ethylene-propylene-non-conjugated diene terpolymer and plasticizer used in the embodiments of the present invention, some suitable solvents are selected from at least one of dodecene, isododecane, cyclohexanone, n-tetradecane, dimethylformamide, cyclohexane, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether, xylene, and propylene glycol methyl ether acetate.

[0056] In some examples, the solvent can be a mixture of dodecene and isododecane, and the mass ratio of dodecene to isododecane is 1:1 - 5:1, and further can be 3:1 - 4:1.

[0057] In the temporary bonding adhesive provided by the embodiments of the present invention, the weight portion of the solvent is 70 parts by weight - 90 parts by weight, and further can be 70 parts by weight - 80 parts by weight.

[0058] In some examples, the viscosity of the temporary bonding adhesive provided by the embodiments of the present invention can be 7000 cP - 10000 cP, and further can be 8000 cP - 9500 cP. This not only facilitates the application of the temporary bonding adhesive in terms of thermal debonding and mechanical debonding, but also helps to improve its coating uniformity, making the film thickness more controllable.

[0059] The temporary bonding adhesive provided by the embodiments of the present invention can be used in wafer processing. When applied, it can be prepared by the following method: mixing the plasticizer and the solvent evenly to obtain a mixed solution. For example, adding the solvent and the plasticizer into a stirring kettle and stirring and mixing evenly to obtain a mixed solution. Heating the mixed solution to 40°C - 50°C (such as 40°C - 45°C), and then, under stirring conditions, adding the ethylene-propylene-non-conjugated diene terpolymer into the mixed solution and stirring until a clear and transparent liquid is formed, thereby preparing the temporary bonding adhesive.

[0060] Exemplarily, for the mixing scheme of the plasticizer and the solvent, the stirring conditions can be stirring at a stirring speed of 80 r / min - 100 r / min for 1 min - 10 min.

[0061] Exemplarily, for the mixing scheme of the ethylene-propylene-non-conjugated diene terpolymer and the mixed solution, the stirring conditions can be stirring at a stirring speed of 200 r / min - 300 r / min for 90 min - 180 min.

[0062] For the above-mentioned stirring operation, by adopting high-speed stirring and shearing, the surface energy is increased, thereby forming microcolloidal particles in the mixed system and realizing the uniform dispersion of each component therein.

[0063] After the temporary bonding adhesive is prepared, it can be stored by the following method:

[0064] (1) Storage conditions: The container should be stored sealed and in an environment with low temperature, dryness, and good ventilation. When the temporary bonding adhesive is not in use, keep the container closed and upright. Keep away from fire, light, and heat sources. Mixing storage with strong acids, strong alkalis, and strong oxidants is prohibited. The above storage conditions can ensure the stability and service life of the temporary bonding adhesive, which is conducive to reducing costs during its long-term storage and use.

[0065] (2) Storage time: Since the date of preparation of the temporary bonding adhesive, the preferred expiration date is one natural year.

[0066] The temporary bonding adhesive provided by the embodiments of the present invention has at least the following advantages compared with the prior art:

[0067] (1) The temporary bonding adhesive provided by the embodiments of the present invention has the functions of bonding, thermal debonding, and mechanical debonding at the same time. Among them, its two-in-one debonding function design enables it to adapt to different debonding requirements during the wafer processing, without the need to frequently replace different types of bonding adhesives, which is conducive to improving production efficiency and process flexibility, and provides more convenience and selectivity for wafer processing.

[0068] (2) The temporary bonding adhesive provided by the embodiments of the present invention uses a specific type of ethylene-propylene-non-conjugated diene terpolymer as the main resin. This type of ethylene-propylene-non-conjugated diene terpolymer has excellent heat resistance and chemical resistance, can remain stable at a high temperature of up to 300 °C, and can also withstand most organic solvents, strong acids, and strong alkalis. This high-temperature stability and chemical solvent tolerance enable the temporary bonding adhesive to perform well in the high-temperature wafer backside process, solve the problem of limited thermal slip debonding temperature in the prior art, and at the same time reduce the solvent consumption and environmental pollution in chemical release debonding.

[0069] (3) For the preparation of the temporary bonding adhesive provided by the embodiments of the present invention, its preparation method is simple and easy to implement. Through high-speed stirring and shearing technology, microcolloidal particles can be formed, enabling the colloid to be evenly dispersed, thereby optimizing the TTV (Total Thickness Variation) of the bonding adhesive layer, and it is easy to achieve a uniform film thickness during the coating process, which is conducive to improving the accuracy and quality of wafer processing.

[0070] On the other hand, the embodiments of the present invention also provide the application of any of the above-mentioned temporary bonding adhesives in wafer processing.

[0071] The temporary bonding adhesive provided by the embodiments of the present invention can be used for the temporary bonding of wafers and carriers during the wafer processing, and can be debonded based on thermal slip debonding or mechanical release debonding, and obtain excellent debonding effects.

[0072] Because the improved temporary bonding adhesive provided by the embodiments of the present invention has strong temperature resistance, when thermal slip debonding is used, the debonding temperature can be designed to be higher, which facilitates the smooth implementation of many high-temperature wafer backside processes. When mechanical release debonding is used, the temporary bonding adhesive's superior mechanical strength can prevent mechanical stress from damaging the circuits on the wafer surface.

[0073] The following is an illustrative description of some applications of temporary bonding adhesives in wafer processing.

[0074] Regarding the solution of applying temporary bonding adhesive to the wafer surface, the implementation scheme may be as follows:

[0075] (1) Place the wafer in the spin coater, turn on the vacuum system, fix the wafer with a vacuum chuck, and set the spin coating speed to 1500 r / min-2500 r / min, and further to 2000 r / min-2500 r / min.

[0076] (2) Take a certain amount, for example, 2.5ml-5ml of temporary bonding glue, and evenly drip it to the center of the wafer. Spin coat for 20s-40s, or even 20-30s. The coating amount of temporary bonding glue on the wafer surface can be 2g-5g / 70cm 2 -100cm 2 , in order to obtain the appropriate thickness of the glue layer.

[0077] (3) Close the vacuum chuck, remove the wafer coated with the temporary bonding glue, place it in an oven for baking, and then take it out. For example, the oven temperature is 80°C-150°C, and can be further 150°C. The baking time can be 40s-90s, and can further be 50s-60s.

[0078] (4) The side of the wafer coated with the temporary bonding adhesive is attached to a carrier, for example, the carrier can be a wafer stage or a carrier wafer, and then heated at a set temperature and pressurized at a set pressure to achieve bonding. For example, it can be heated at a temperature of 150°C-200°C and pressurized at a pressure of 0.8kg-1.5kg for 3min-10min, further can be 5min-8min, and finally cooled to room temperature to complete the temporary bonding of the wafer.

[0079] On the other hand, an embodiment of the present invention also provides a wafer processing process, which includes: temporarily bonding the wafer to the carrier based on any one of the temporary bonding adhesives mentioned above; processing the wafer to obtain a functional wafer; and debonding the functional wafer and the carrier to separate the functional wafer.

[0080] Exemplarily, the debonding process is thermal slip debonding or mechanical release debonding. Due to the improved temporary bonding adhesive provided in the embodiments of the present invention, thermal slip debonding or mechanical release debonding respectively avoids their current existing drawbacks.

[0081] The exemplary embodiments of the present invention will be described in more detail below. Although the exemplary embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. For those without specific technical or condition indications in the examples, the techniques or conditions described in the literature in the art or according to the product specifications are followed. For reagents or instruments without indication of the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0082] Examples 1 - 20

[0083] Examples 1 - 20 respectively provide a temporary bonding adhesive, and the formulations of the respective temporary bonding adhesives can be seen in Table 1 below.

[0084] Table 1

[0085]

[0086]

[0087]

[0088] The preparation methods of the temporary bonding adhesives provided by Examples 1 - 20 are as follows:

[0089] Step 1: Add a solvent and a plasticizer to a stirring kettle, stir and mix evenly to obtain a mixed solution. Among them, the stirring condition is stirring at 100 r / min for 8 min.

[0090] Step 2: Heat the mixed solution obtained in Step 1 to 45 °C, and add an ethylene - propylene - non - conjugated diene terpolymer under continuous stirring conditions, and stir until a clear and transparent liquid is formed to prepare the temporary bonding adhesive. Among them, the stirring condition is stirring at 250 r / min for 8 min.

[0091] Comparative Examples 1 - 3

[0092] Comparative Examples 1 - 3 respectively provide temporary bonding adhesives, and the formulations of the respective temporary bonding adhesives can be seen in Table 2 below.

[0093] Table 2

[0094]

[0095] Test Example 1

[0096] The relevant properties of the temporary bonding adhesives provided by Examples 1 - 20 and Comparative Examples 1 - 3 were tested using Test Example 1. The test items and results can be seen in Table 3.

[0097] Table 3

[0098]

[0099]

[0100] Among them, the test methods and evaluation criteria for each test item involved in Table 3 can be seen as follows:

[0101] (1) The uniformity and TTV were both tested using a micrometer. The test methods and evaluation criteria are as follows:

[0102] 1.1. Prepare a high-precision micrometer test instrument, ensure that the instrument has been calibrated and meets the test requirements. Prepare the sample to be tested (a wafer coated with a bonding adhesive layer, and the adhesive layer on it has been baked), ensure that its surface is flat and has no obvious defects or damages.

[0103] 1.2. Firmly clamp the sample to be tested on the test bench to ensure that it will not move or shake during the test, so as to ensure the accuracy of the test results.

[0104] 1.3. Set the test parameters according to the requirements and actual situation of the sample to be tested, ensure that the setting of the test parameters meets the test requirements and can meet the accurate evaluation of the uniformity and TTV.

[0105] 1.4. Start the micrometer test instrument and start testing the surface of the sample to be tested. The micrometer test instrument will collect and display the height change data of the sample surface in real time, and analyze the uniformity and TTV of the sample surface through these data.

[0106] 1.5. Evaluation criteria: If the uniformity < 3%, it is qualified; if the TTV < 3μm, it is qualified.

[0107] (2) The high-temperature stability was tested using thermogravimetric analysis. The test method is as follows:

[0108] 2.1. Prepare the sample to be tested (a wafer coated with a bonding adhesive layer, and the adhesive layer on it has been baked), ensure that its solvent is volatilized as much as possible, test the weight loss of the sample at a fixed heating rate, determine the weight loss of the test sample at different temperatures, and confirm the temperature when the sample mass loss is 5%.

[0109] 2.2. Prepare the same samples to be tested and ensure that their solvents are volatilized as much as possible. Measure the time elapsed when the weight of the sample loses 5% at a fixed temperature as the test time. It can be considered that the sample is stable during this period of time tested at this temperature.

[0110] (3) The test method for thermal slip debonding (abbreviated as thermal debonding) is as follows:

[0111] 3.1. Place the wafer and the carrier wafer bonded with the temporary bonding adhesive in the thermal debonding equipment and heat it to the melting temperature of the temporary bonding adhesive.

[0112] 3.2. Control the viscosity of the temporary bonding adhesive by adjusting the temperature so that it can achieve slip debonding while keeping the wafer stable.

[0113] 3.3. While heating, achieve slip debonding by horizontally sliding the carrier wafer, or in some cases, complete slip debonding through a pushing and pulling action in the vertical direction.

[0114] (4) The test method for mechanical peeling debonding (abbreviated as mechanical debonding) is as follows:

[0115] 4.1. Use a mechanical peeling tool, such as a thin sheet inserter, and insert it between the carrier wafer and the device wafer.

[0116] 4.2. Peel the carrier wafer by an upward pulling force and a rotational shearing force to separate the wafer from the carrier wafer. This process requires precise control to avoid damaging the wafer.

[0117] Combined with the data in Table 3, it can be seen that compared with the comparative example, the temporary bonding adhesive provided by the embodiment of the present invention is excellent in terms of uniformity, TTV after spin coating, TTV after bonding, high-temperature stability, and thermal and mechanical debonding.

[0118] Test Example 2

[0119] The film thickness data corresponding to the temporary bonding adhesive provided in Example 1 at different rotation speeds were tested using Test Example 2. The test results are shown in Table 4.

[0120] Table 4

[0121] Rotational speed rpm 1000 1500 2000 2500 3000 Maximum film thickness μm 41.185 27.403 20.362 16.635 13.823 Minimum film thickness μm 40.702 26.895 20.021 16.352 13.664 Average film thickness μm 40.835 27.245 20.142 16.542 13.798 TTV 0.483 0.508 0.341 0.283 0.159 UNIF% 2.82 2.64 2.51 1.43 0.59

[0122] Among them, UNIF is the uniformity, and UNIF = TTV / (2 × average film thickness).

[0123] As can be seen from Table 4, the bonding adhesive provided in Example 1 has a stable film thickness at different rotation speeds, which is convenient for construction.

[0124] The weight percentage change of the temporary bonding adhesive provided in Example 1 with temperature was tested using Test Example 2 (with a temperature change rate of 20 °C / min). The test results are shown in Figure 1 . It can be seen from Figure 1 that when the weight loss of the temporary bonding adhesive reaches 5%, the corresponding temperature is 262 °C. Therefore, when performing thermogravimetric analysis (TGA) on this temporary bonding adhesive, the temperature for isothermal TGA can be set at 260 °C.

[0125] The weight percentage change of the temporary bonding adhesive provided in Example 2 with time was tested under the condition of a constant temperature of 260 °C using Test Example 2. The test results are shown in Figure 2 . It can be seen from Figure 2 that the temporary bonding adhesive provided in Example 2 is stable under isothermal baking at a high temperature of 260 °C. After a time greater than 30 min, its weight loss reaches 5%.

[0126] In the embodiments of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. The term "plurality" means two or more, unless otherwise clearly defined.

[0127] The above description is only for the convenience of those skilled in the art to understand the technical solution of the present invention and is not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A temporary bonding adhesive, characterized in that, The temporary bonding adhesive comprises: 10 parts by weight - 30 parts by weight of ethylene-propylene-non-conjugated diene terpolymer, 1 part by weight - 10 parts by weight of plasticizer, and 70 parts by weight - 90 parts by weight of solvent; The non-conjugated diene monomer in the ethylene-propylene-non-conjugated diene terpolymer includes at least one of 1,4-butadiene, ethylidene norbornene, dicyclopentadiene, methylcyclopentadiene, isoprene, 1,4-hexadiene, 3-ethyl-1,4-hexadiene.

2. The temporary bonding adhesive according to claim 1, wherein The ethylene-propylene-non-conjugated diene terpolymer comprises: an ethylene-propylene alternating copolymer segment, wherein the mass percentage of the ethylene monomer corresponding to the ethylene-propylene alternating copolymer segment is 40% - 80%, and the mass percentage of the propylene monomer corresponding thereto is 20% - 60%.

3. The temporary bonding adhesive according to claim 2, wherein, The ethylene-propylene-non-conjugated diene terpolymer further comprises: a non-conjugated diene monomer segment, and the mass ratio of the ethylene-propylene alternating copolymer segment to the non-conjugated diene monomer segment is 2:1 - 5:

1.

4. The temporary bonding adhesive according to claim 2, characterized in that The weight-average molecular weight of the ethylene-propylene alternating copolymer segment is 2.0×10 5 -8.0×10 5 .

5. The temporary bonding adhesive according to any one of claims 1-4, characterized in that, The weight-average molecular weight of the ethylene-propylene-non-conjugated diene terpolymer is 4.0×10 5 -9.0×10 5 , and the Mooney viscosity ML 1+4 / 125 °C of the ethylene-propylene-non-conjugated diene terpolymer is 50-100.

6. The temporary bonding adhesive according to claim 1, characterized in that, The plasticizer is selected from at least one of white oil, aromatic oil, dioctyl phthalate, dioctyl adipate, n-octyl sebacate, coumarone resin, petroleum resin.

7. The temporary bonding adhesive according to claim 1, wherein The solvent is selected from at least one of dodecene, isododecane, cyclohexanone, n-tetradecane, dimethylformamide, cyclohexane, ethyl 3-ethoxypropionate, ethylene glycol monobutyl ether, xylene, propylene glycol methyl ether acetate.

8. A preparation method of a temporary bonding adhesive, characterized in that, The temporary bonding adhesive is as described in any one of claims 1 - 7; The preparation method comprises: uniformly mixing the plasticizer and the solvent to obtain a mixed solution; Under stirring conditions, adding the ethylene-propylene-non-conjugated diene terpolymer to the mixed solution and stirring until a clear and transparent liquid is formed to prepare the temporary bonding adhesive.

9. A wafer processing method, characterized in that, The wafer processing process comprises: based on the temporary bonding adhesive described in any one of claims 1 - 7, temporarily bonding the wafer to the carrier; Processing the wafer to obtain a functional wafer; Performing a debonding process on the functional wafer and the carrier to separate and obtain the functional wafer.

10. The wafer processing method according to claim 9, characterized in that, The debonding process is thermal slip debonding or mechanical release debonding.

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