A processing aid device and method for thinning a wafer

Abstract

The application belongs to the technical field of semiconductor processing, and particularly discloses a processing auxiliary device for wafer thinning, which comprises a base body and at least one limiting sheet, the limiting sheet is connected with the end of the base body, an installation hole is formed in the limiting sheet, the installation hole is used for installing and placing a wafer, the wafer is detachably connected with one end of the base body, and the height difference between the limiting sheet and the end of the base body is less than the height difference between the wafer to be processed and the end of the base body. The application can guarantee the wafer thinning quality and reduce the wafer fragment or bending phenomenon.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor processing, in particular to a wafer thinning processing method. BACKGROUND

[0002] With the rapid progress of semiconductor technology, wafer thinning process has become increasingly important in the manufacturing of modern electronic devices. Wafer thinning not only can reduce the weight of the product, reduce the cost of materials, but also can improve the performance and integration of the device. Therefore, optimizing the wafer thinning process has become an urgent demand of the current semiconductor industry.

[0003] Currently, wafer thinning techniques mainly include mechanical grinding, chemical mechanical polishing (CMP), laser thinning and other methods. These traditional processes face a series of challenges in the implementation process. For example, in the mechanical grinding process, the surface of the wafer is easy to be scratched and worn, especially in the area where the back of the wafer contacts the substrate, if not cleaned thoroughly, it will cause the influence of contaminants such as colloidal particles on the wafer. Such contamination not only leads to defects in subsequent processing, but also may adversely affect the yield.

[0004] In addition, in the process of traditional bonding materials, the clamping method of sheet-shaped parts is mainly through paraffin or vacuum adsorption, but it has certain limitations. The paraffin bonding method needs to be heated and cooled, which affects the stress on the workpiece surface, and it is difficult to ensure the uniformity of paraffin coating, which cannot guarantee the parallelism of the final machining surface, thereby increasing the risk of product loss.

[0005] Currently, in the process of wafer thinning, a star wheel is usually used to fix the wafer, and the wafer is rotated by a gear to achieve polishing and grinding. However, the existing method is fixed at a polishing height, which cannot adapt to the processing needs of wafers of different thicknesses, limiting the processing flexibility. Moreover, the fixing effect of this method on the wafer is poor, which leads to the risk of breaking during wafer thinning.

[0006] In addition, when processing wafers of different specifications, the adjustment and switching process of the production line is complicated and time-consuming, which reduces the overall efficiency and flexibility of production. At the same time, the traditional cleaning equipment has poor effect in removing small contaminants, which may cause the accumulation of residues on the wafer surface, thereby affecting the subsequent processing steps.

[0007] The polishing pressure is one of the important factors affecting the material removal rate, so whether the wafer can withstand greater polishing pressure during wafer thinning is a decisive factor for wafer fragmentation or deformation. Therefore, the upper limit of the polishing pressure of the wafer can improve the efficiency of wafer thinning. However, as the polishing pressure rises, the risk of wafer fragmentation or deformation increases, which in turn leads to a decrease in yield.

[0008] Current wafer thinning processes still face many challenges, including pollution control, bonding process, processing efficiency, processing flexibility, upper limit of pressure, low yield of ultra-thin wafer, and the like. Therefore, it is urgent to seek new solutions to improve the efficiency, quality and economy of wafer thinning processing. SUMMARY

[0009] The present application provides a wafer thinning processing method, aiming to ensure the quality of wafer thinning while reducing the phenomenon of wafer fragmentation or bending.

[0010] The present application is implemented by the following technical scheme: a wafer thinning processing auxiliary device, comprising a base body and at least one limiting sheet, the limiting sheet is connected with the end of the base body, the limiting sheet is provided with a mounting hole for mounting and placing a wafer, the wafer is detachably connected with one end of the base body, and the height difference between the limiting sheet and the end of the base body is less than the height difference between the wafer to be processed and the end of the base body.

[0011] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0012] In the present application, the base body and the limiting sheet are used to limit and fix the wafer. Since the wafer is placed in the mounting hole of the limiting sheet, and the back surface of the wafer is detachably connected with one end of the base body, the wafer can be effectively clamped.

[0013] In the thinning processing of ultra-thin wafers, the wafer is particularly prone to fragmentation during processing because the processed wafer is ultra-thin. In the prior art, the auxiliary tool used for processing the wafer is not suitable for clamping and fixing the ultra-thin wafer. When processing ultra-thin workpieces, the wafer cannot withstand greater polishing pressure, resulting in breakage, which seriously affects the quality and processing efficiency of the wafer.

[0014] In the present application, the base body plays a role of adding thickness and provides rigid support to the wafer. When the wafer is thinned, the added base body effectively improves the ability of the wafer to withstand greater polishing pressure, ensures the quality of wafer thinning, reduces the phenomenon of wafer fragmentation or bending, and achieves higher polishing efficiency during processing. The wafer thinning processing auxiliary device of the present application is very suitable for processing ultra-thin wafers. The processing auxiliary device of the present application can not be limited by the thickness of the wafer workpiece, and thinner workpieces can be processed by using existing processing technology.

[0015] In addition, the limiting piece can position the wafer after the wafer is thinned, and the thickness of the wafer can be controlled, so that the accuracy of the wafer thinning thickness is improved, and the wafer can be prevented from sliding on the base to affect the processing accuracy of the wafer, and the stability of the wafer during the thinning process is ensured.

[0016] Further, the limiting piece is provided with two, and the two limiting pieces are connected to the top end and the bottom end of the base respectively.

[0017] Beneficial effects: In the scheme, the two limiting pieces are located at the top end and the bottom end of the base, which can simultaneously thin two wafers, thereby improving the processing efficiency, and the two limiting pieces can be changed in thickness to meet the requirements of processing two wafers to obtain wafers with different thicknesses, thereby improving the work efficiency.

[0018] Further, the base is a transparent plate carrier or a glass carrier that can transmit ultraviolet light, and the wafer and the base are connected and fixed by UV light-induced peelable glue.

[0019] Beneficial effects: In the scheme, the wafer and the base are connected by UV light-induced peelable glue, and the base can transmit ultraviolet light, so that after the wafer thinning process is completed, the UV light-induced peelable glue is irradiated by the ultraviolet light irradiation device to soften and realize the peeling of the wafer workpiece.

[0020] Further, the base is quartz glass.

[0021] Beneficial effects: Quartz glass has high temperature resistance, good thermal stability, excellent optical performance, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection, so the ultraviolet light can be irradiated through the base to soften the UV light-induced peelable glue and realize the peeling of the wafer.

[0022] Further, a plurality of airflow injection holes are formed on the limiting piece along the circumferential direction, and the two ends of the plurality of airflow injection holes respectively penetrate the outer side and the inner side of the limiting piece.

[0023] Beneficial effects: The airflow injection holes in the scheme can be connected to external high-pressure injection equipment through pipelines, the high-pressure injection equipment provides high-pressure gas, and the high-pressure gas is injected into the inner side of the mounting hole of the limiting piece through the plurality of airflow injection holes, and the surface of the base connected with the wafer in the later stage is cleaned, so that when the wafer is placed in the mounting hole and fixed with the surface of the base, the pollution and scratches on the back of the wafer can be prevented.

[0024] Further, the plurality of airflow injection holes are horizontally arranged or obliquely arranged.

[0025] Beneficial effects: two setting modes of air flow injection holes are provided in the scheme, the horizontal setting mode of air flow injection holes is more convenient for processing and manufacturing, and the inclined setting mode of air flow injection holes has better cleaning effect on the surface of the base.

[0026] Further, the end of the base is stepped, so that the end of the base has a boss, and the limiting piece is sleeved on the boss.

[0027] Beneficial effects: the boss is arranged on the end of the base in the scheme, so that the limiting piece is sleeved on the boss, the limiting piece with different thickness can be directly replaced according to the required wafer thickness, different thickness limiting pieces can be replaced to adapt to the processing of wafers with different thickness, and the same thinning thickness can be realized for wafers with different thickness, so as to meet the diversified production demand and have strong processing flexibility.

[0028] Further, the end of the base is stepped, so that the end of the base has a boss, and the limiting piece is sleeved on the boss.

[0029] Further, the wafer and the mounting hole of the limiting piece have a gap.

[0030] Beneficial effects: in this way, the wafer has a certain space for giving way during processing, so that the wafer can be effectively prevented from being broken during processing.

[0031] A processing method for thinning wafers, using the above-mentioned processing auxiliary device for thinning wafers, comprising the following steps:

[0032] a) installing limiting pieces on the top end and the bottom end of the base respectively, arranging a plurality of uniformly distributed air flow injection holes on the limiting pieces, and cleaning the connection between the upper surface and the lower surface of the base and the back surface of the wafer;

[0033] b) coating UV light-induced peelable glue on the connection between the upper surface and the lower surface of the base and the back surface of the wafer;

[0034] c) placing two wafers for processing in the mounting holes of the two limiting pieces respectively, and bonding and fixing the wafers to the base through the UV light-induced peelable glue coated on the surface of the base;

[0035] d) fixing the base on a grinding and polishing device, and simultaneously grinding or polishing the back surfaces of the two wafers to thin the wafers;

[0036] e) using a ultraviolet light irradiation device to irradiate the surface of the base which can transmit ultraviolet light, so that the UV light-induced peelable glue loses adhesion, and the wafers are peeled off;

[0037] f) annealing the wafers.

[0038] e) cleaning the wafer by an ultrasonic cleaning device to obtain a thinned wafer.

[0039] Beneficial effects: the scheme utilizes the grinding and polishing device to process the wafer workpiece, the method cleans the surface of the substrate through the airflow injection hole arranged on the limiting sheet, prevents the pollution and scratch of the back surface of the wafer, the wafer workpiece is fixed on the substrate through the UV light-induced peelable adhesive, and after the wafer workpiece is ground or polished, the UV light-induced peelable adhesive is irradiated through the ultraviolet irradiation device to soften the UV light-induced peelable adhesive, so that the wafer workpiece is peeled off.

[0040] The method utilizes the limiting sheet on the substrate to limit the thin sheet workpiece from sliding along the substrate plane during processing, the substrate material adopts a transparent plate carrier or a glass carrier with high surface flatness and ultraviolet light transmittance, and plays a rigid role in supporting the wafer. The method improves the ability of the workpiece (wafer) to withstand greater grinding and polishing pressure by the way of stacking the thickness of the substrate. The substrate and the limiting sheet in the method can adopt a structure with high overall flatness, and the wafer is easy to load and unload, which is suitable for processing of ultra-thin wafers.

[0041] Further, the temperature set during the grinding or polishing process of the wafer in step d is 34-36 DEG C.

[0042] Beneficial effects: the temperature set during the grinding or polishing process should avoid high temperature, and the temperature in the scheme is appropriate to avoid deformation of the wafer material caused by high temperature.

[0043] Compared with the prior art, the present application has the following advantages:

[0044] 1. Airflow injection cleaning on the limiting sheet: airflow injection holes are arranged on the limiting sheet, and the substrate surface is cleaned by airflow impact to prevent pollution and scratches on the back surface of the wafer.

[0045] 2. Limiting sheet fixing wafer: adjustable height limiting sheet is used to fix the wafer to be thinned to ensure the stability of the wafer during the thinning process and meet the thinning requirements of wafers of different thicknesses.

[0046] 3. UV light-induced peelable adhesive curing: UV light-induced peelable adhesive is used to fix the wafer to further enhance the stability of the wafer.

[0047] 4. Double wafer grinding / polishing thinning: two wafers are simultaneously subjected to back surface grinding / polishing thinning to improve overall work efficiency.

[0048] 5. Use of ultraviolet irradiation device: UV light-induced peelable adhesive is cured by the ultraviolet irradiation device arranged in the substrate, so that the wafer is peeled off.

[0049] 5. Laser annealing process: The advantages of laser annealing include the ability to precisely control the heating area and temperature, thereby achieving local or global annealing of the wafer without damaging the overall structure and performance of the wafer. Laser annealing can reduce thermal stress, improve annealing efficiency, and maintain the flatness and electrical performance of the wafer.

[0050] 6. Ultrasonic cleaning: The thinned wafer is thoroughly cleaned by the ultrasonic cleaning equipment to ensure that there is no residual material on the wafer surface, resulting in a high-quality thinned wafer. BRIEF DESCRIPTION OF DRAWINGS

[0051] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0052] Figure 1 is a schematic diagram of the separation of the wafer and the base in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0053] Figure 2 is a schematic diagram of the structure after the wafer and the base are connected in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0054] Figure 3 is a perspective view of the limiting sheet in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0055] Figure 4 is a perspective view of the wafer and the limiting sheet in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0056] Figure 5 is a top view of the wafer and the limiting sheet in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0057] Figure 6 is a schematic diagram of the structure of the airflow injection holes inclined on the limiting sheet in an embodiment of the processing auxiliary device for thinning a wafer of the application;

[0058] Figure 7 is a front view of the base in embodiment 3 of the processing auxiliary device for thinning a wafer of the application.

[0059] Markings in the drawings and corresponding names of parts:

[0060] Wafer 1, limiting sheet 2, mounting hole 201, base 3, boss 301, UV light-induced peelable adhesive 4, airflow injection hole 5, ultraviolet light irradiation device 6. DETAILED DESCRIPTION

[0061] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0062] Example 1

[0063] like Figures 1-2 As shown, this embodiment 1 provides a wafer thinning auxiliary device, including a substrate 3 and at least one limiting piece 2, the limiting piece 2 being connected to the end of the substrate 3. Figure 3 As shown, the limiting piece 2 has a mounting hole 201, which is located in the center of the limiting piece 2. In this embodiment, the limiting piece 2 is generally circular, and the top and bottom ends of the limiting piece 2 are both flat.

[0064] like Figure 4 As shown, mounting hole 201 is used to mount and place wafer 1, combined with Figure 5 As shown, in this embodiment, there is a gap between the wafer 1 and the mounting hole 201 of the limiting piece 2, thereby reserving a certain buffer space for the wafer 1. This can protect the wafer 1 during the processing of the wafer 1 and reduce damage to the wafer 1.

[0065] The height difference between the limiting plate 2 and the end of the substrate 3 is less than the height difference between the wafer 1 to be processed and the end of the substrate 3. This allows a portion of the wafer 1 to be processed to be exposed after being placed behind the limiting plate 2, which is used to control the thickness of the wafer 1 during grinding. By replacing the limiting plate 2 with different thicknesses, wafers 1 with different thickness requirements can be thinned.

[0066] In this embodiment, there are two limiting pieces 2. The two limiting pieces 2 are respectively connected to the top and bottom of the substrate 3. The limiting pieces 2 and the substrate 3 can be fixed by adhesive or screws. The limiting pieces 2 can be removed from the substrate 3 and replaced with limiting pieces 2 of different thicknesses according to the different thicknesses of the wafer 1 to be processed, thereby meeting the requirements of processing wafers 1 of different thicknesses.

[0067] In this embodiment, the two limiting pieces 2 are provided to facilitate the mounting of the wafers 1 to be processed at the top and bottom of the substrate 3, respectively, thereby allowing the two wafers 1 to be thinned simultaneously, which effectively improves work efficiency.

[0068] Combination Figure 2As shown, the wafer 1 is detachably connected to one end of the base 3. In this embodiment, the base 3 is a transparent plate carrier or a glass carrier with a flat surface and capable of transmitting ultraviolet light. The wafer 1 and the base 3 are connected and fixed by the UV light-induced peelable adhesive 4. Since the wafer 1 is fixed on the surface of the base 3, the wafer 1 may be deformed to a certain extent when the wafer 1 bears pressure. Therefore, the UV adhesive needs to be evenly and non-contaminatingly applied, so that the wafer 1 has a high flatness after processing. The UV light-induced peelable adhesive 4 has high adhesion before UV curing and high tackiness reduction after UV irradiation, which can meet the requirements of wafer 1 thinning. In this embodiment, the thickness of the UV light-induced peelable adhesive 4 is 50-55 um.

[0069] In this embodiment, since the thickness of the UV light-induced peelable adhesive 4 and the thickness to be thinned need to be reserved, the thickness of the limiting sheet 2 is preferably 80%-94% of the thickness of the wafer 1 to be processed. In this way, the wafer 1 can be better fixed to ensure that it does not slide along the base 3, and the wafer 1 can be thinned to the required thinning thickness.

[0070] Further, in this embodiment, the base 3 is quartz glass. Quartz glass has high temperature resistance, good thermal stability, excellent optical performance, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability, and environmental friendliness. Therefore, the ultraviolet light can be transmitted through the base 3 to soften the UV light-induced peelable adhesive 4 and then realize the peeling of the wafer 1. Quartz glass has high temperature resistance, good thermal stability, excellent optical performance, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability, and environmental friendliness. Therefore, the ultraviolet light can be transmitted through the base 3 to soften the UV light-induced peelable adhesive 4 and then realize the peeling of the wafer 1.

[0071] The UV light-induced peelable adhesive 4 in this embodiment has the properties of ultraviolet light-curable pressure-sensitive adhesive. Pressure-sensitive adhesive refers to an adhesive that is sensitive to pressure and can be firmly adhered to the surface of the adherend with very weak pressure. Ultraviolet light-curable pressure-sensitive adhesive has fast curing rate, energy saving, cost saving, simple curing equipment, and small occupied area.

[0072] In addition to the advantages of ultraviolet light-curable pressure-sensitive adhesive, the UV light-induced peelable adhesive 4 can realize complete peeling in a short time and change from "sticky" to "not sticky". The wafer 1 is fixed by the UV light-induced peelable adhesive 4, and the wafer 1 can be easily peeled off by ultraviolet light. After ultraviolet irradiation, the number of C=C double bonds is greatly reduced, and the photosensitive resin itself is crosslinked. The large volume shrinkage caused by crosslinking will cause wrinkles between the adhesive and the adherend, and the more serious shrinkage will produce micropores. The wrinkles and micropores produced will damage the interface, resulting in a decrease in the bonding area, which is the fundamental reason for the loss of adhesion of the adhesive.

[0073] The constituting material of the substrate 3 in the embodiment is quartz glass, which has high temperature resistance, good thermal stability, excellent optical performance, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection, so that the UV light can be irradiated through the substrate 3 to soften the UV light-induced peelable adhesive 4 and then realize the peeling of the wafer 1.

[0074] In the embodiment, the UV light-induced peelable adhesive 4 can be irradiated to the substrate 3 with the UV light irradiation device 6, and the wafer 1 can be efficiently and losslessly peeled off by the substrate 3, so as to prevent the wafer 1 from being broken or fragmented during the wafer peeling process.

[0075] In the embodiment, the limiting sheet 2 with different thicknesses can be replaced according to actual needs, so that not only the two wafers 1 can be simultaneously back-grinded or polished to obtain the thinned wafers 1, but also the same thinning thickness required for simultaneously thinning the wafers 1 with different thicknesses can be met, which greatly improves the processing efficiency.

[0076] The substrate 3 is adopted in the present application, which realizes the stacked thickness mode and can improve the ability of the workpiece to withstand greater grinding and polishing pressure, thereby obtaining higher grinding and polishing efficiency. Since the substrate 3 adopts quartz glass material, it has many excellent properties and can be a good carrier for the wafer 1. The device is not limited by the thickness of the workpiece, and existing processing technology can be used to process thinner workpieces. The thickness of the wafer 1 to be processed in the embodiment is less than 1 mm, and the processing auxiliary device for thinning wafers of the present application is suitable for processing ultra-thin wafers 1 with a thickness of less than 1 mm.

[0077] The specific implementation process is as follows:

[0078] In the embodiment, after the UV light-induced peelable adhesive 4 is coated on the positions where the top end and the bottom end of the substrate 3 are connected with the wafer 1, the wafer 1 is placed in the mounting hole 201 of the limiting sheet 2, and the back surface of the wafer 1 to be processed is connected and fixed to the surface of the substrate 3 through the UV light-induced peelable adhesive 4, and there is a gap between the wafer 1 and the limiting sheet 2.

[0079] The left end and the right end of the substrate 3 are installed on the grinding and polishing equipment, and the polishing head on the grinding and polishing equipment grinds or polishes the wafers 1 on the top end and the bottom end of the substrate 3 to realize the thinning processing of the wafers 1.

[0080] Compared with existing technologies, this embodiment can adapt to the processing of wafers 1 of different thicknesses by replacing the limiting plates 2 of different thicknesses, meeting diverse production needs and providing high processing flexibility. The combination of UV photo-exfoliating adhesive 4 and ultraviolet light irradiation device 6 ensures that the peeling process is simple and controllable, reducing damage to wafer 1. In addition, UV photo-exfoliating adhesive 4 has high bonding strength, enhancing the stability of wafer 1. Moreover, its debonding operation is simple, and the adhesive is more environmentally friendly. The back-side grinding / polishing of dual wafers 1 greatly improves production efficiency. The setting of substrate 3 provides a way to stack thickness, thereby increasing the upper limit of pressure and achieving higher processing efficiency. Furthermore, the high flatness of substrate 3 makes it suitable for processing ultra-thin wafers 1.

[0081] Example 2

[0082] The difference between this embodiment and Embodiment 1 is that: [The following is a combination of the two embodiments] Figure 3 and Figure 4 As shown, multiple airflow injection holes 5 are evenly distributed along the circumference of the limiting plate 2, with both ends of the multiple airflow injection holes 5 penetrating through the outer and inner sides of the limiting plate 2, respectively. The diameter of the airflow injection holes 5 is 0.1mm to 0.2mm.

[0083] Combination Figure 2 and Figure 6 As shown, multiple air jet holes 5 are set horizontally or at an angle. The air jet holes 5 are connected to a high-pressure jetting device through pipes. In this way, before installing the wafer 1, gas can be sprayed into the mounting hole 201 through the air jet holes 5, and the position where the substrate 3 and the wafer 1 are connected can be cleaned to prevent contamination and scratches when the wafer 1 is installed on the substrate 3 later.

[0084] Example 3

[0085] The difference between this embodiment and Embodiment 1 is that: Figure 7 As shown, the end of the base 3 is stepped, giving it a boss 301, and the limiting piece 2 is fitted onto the boss 301. In this embodiment, both the top and bottom ends of the base 3 have cylindrical bosses 301, and the two limiting pieces 2 are respectively fitted onto the two bosses 301. The two bosses 301 can provide a more stable limiting effect on the limiting pieces 2, preventing them from shaking or moving.

[0086] In this embodiment, the boss 301 has the function of positioning the mounting position of the limiting piece 2, thereby ensuring the thinning processing accuracy of the wafer 1.

[0087] Example 4

[0088] The difference between this embodiment and the above embodiments is that this embodiment provides a wafer thinning processing method, using a wafer thinning processing auxiliary device from the above embodiments, including the following steps:

[0089] a) Install the limiting sheet 2 at the top and bottom ends of the substrate 3, and set a plurality of airflow injection holes on the limiting sheet 2, and clean the connection between the upper and lower surfaces of the substrate 3 and the back surface of the wafer 1;

[0090] b) Apply UV light-induced peelable glue 4 at the connection between the upper and lower surfaces of the substrate 3 and the back surface of the wafer 1, or apply UV light-induced peelable glue 4 on the back surface of the wafer 1;

[0091] c) Place the two wafers 1 to be processed in the mounting holes 201 of the two limiting sheets 2, and fix them to the substrate 3 through the applied UV light-induced peelable glue 4;

[0092] d) Fix the two ends of the substrate 3 on a grinding and polishing device, and simultaneously grind or polish the two wafers 1 to thin the wafers 1; the temperature set during the grinding or polishing process should avoid high temperature, and in this embodiment, the temperature set during the grinding or polishing process of the wafers 1 is 34-36°C;

[0093] e) Use the ultraviolet light irradiation device 6 to irradiate the surface of the substrate 3 that can transmit ultraviolet light, so that the UV light-induced peelable glue 4 loses adhesion, thereby peeling off the wafers 1;

[0094] f) Perform annealing treatment on the wafers 1, and in this embodiment, laser annealing technology is used to perform annealing treatment on the wafers 1 to reduce thermal damage to the wafers 1; in this embodiment, the laser annealing technology can use other types of annealing processes, such as electron beam annealing or plasma annealing;

[0095] e) Clean the thinned wafers 1 through an ultrasonic cleaning device.

[0096] In this embodiment, the laser annealing technology provides a more precise heat treatment process for the thinned wafers 1, avoiding thermal damage; through the airflow injection holes 5 and the ultrasonic cleaning device, efficient pollution prevention and control during the processing process is achieved, improving the quality of the wafers 1.

[0097] The wafers 1 to be processed can be various semiconductor materials such as sapphire, and in this embodiment, two 6-inch sapphire wafers 1 are selected as the objects to be thinned, and the initial thicknesses of the sapphire wafers 1 are 925um and 950um respectively, and the target thicknesses after thinning are 900um and 925um. Quartz glass is used as the substrate 3, and a plurality of airflow injection holes 5 with a diameter of 0.2mm are set on the limiting sheet 2.

[0098] First, the surface of the substrate 3 is cleaned by the air flow impact of the high-pressure gas in the air flow injection hole 5 to prevent the residue of the colloid and particles. Then, the wafer 1 is placed in the mounting hole 201 of the limiting sheet 2, and the height of the upper and lower limiting sheets 2 is adjusted to 850 um and 875 um respectively according to the thickness of the wafer 1.

[0099] Subsequently, the UV light peelable adhesive 4 is uniformly applied to the side of the sapphire wafer 1 in contact with the substrate 3, and the thickness of the UV adhesive layer is 50 um. The two wafers 1 are simultaneously thinned by chemical mechanical polishing, and the thickness is reduced to 900 um and 925 um respectively.

[0100] After the thinning is completed, the ultraviolet light irradiation device 6 is started, the 180° peeling strength before ultraviolet light curing can reach 25N / mm~35N / mm, and the 180° peeling strength after ultraviolet light irradiation is 0.1N / mm~0.2N / 25mm. The wafer 1 is peeled off.

[0101] Then, the wafer 1 is subjected to laser annealing treatment. Finally, the wafer 1 is cleaned by the ultrasonic cleaning device, and two pieces of thinned sapphire wafers 1 with no particle pollution on the surface and uniform thickness are obtained, and the roughness and TTV meet the industrial requirements.

[0102] In the method, when the 6-inch sapphire wafer 1 is processed, the applied pressure reaches 250kg~300kg, and no fragments are generated. Different thickness limiting sheets 2 can be used to simultaneously thin the sapphire wafers 1 with different thicknesses by the same thinning thickness, so that the processing efficiency is improved. The 180° peeling strength of the workpiece after ultraviolet light irradiation is less than 1N / mm, the residual glue amount is low, and the sapphire wafer 1 back grinding / polishing processing can be met. In the process of chemical mechanical polishing, due to the influence of the superimposed thickness, the wafer 1 can withstand greater pressure, the stress distribution is more uniform, the material removal is more uniform, the polishing quality is higher, and the efficiency of the thinned wafer 1 is greatly improved.

[0103] Example 5

[0104] The difference between this embodiment and example 4 is that in this embodiment, two pieces of 6-inch sapphire wafers 1 are selected for ultra-thin processing, the initial thickness is 375 um, and the target thinned thickness is 350 um.

[0105] Quartz glass is used as the substrate 3, and a plurality of air flow injection holes 5 with a diameter of 0.1mm are arranged on the limiting sheet 2 to clean the surface of the substrate 3 and prevent the residue of the colloid and particles. In order to improve the stability of the wafer 1 and obtain the ultra-thin sapphire wafer 1 with the required thickness, the height of the upper and lower limiting sheets 2 is adjusted to 300 um.

[0106] Then the UV light peelable glue 4 is evenly applied to the side of the sapphire wafer 1 in contact with the substrate 3, and the thickness of the UV glue layer is 50um. After thinning, the ultraviolet light irradiation device 6 is started, the 180° peeling strength before photocuring is 25N / mm~35N / mm, the 180° peeling strength after ultraviolet light irradiation is 0.1N / mm~0.2N / mm, and the wafer 1 is peeled off. Then the wafer 1 is subjected to laser annealing treatment. Finally, the wafer 1 is cleaned by the ultrasonic cleaning device, and a 6-inch ultra-thin sapphire wafer 1 with a thickness of 350um, uniform and high yield is obtained, and the roughness and TTV meet the industrial requirements.

[0107] The method of the present application can process 6-inch ultra-thin sapphire wafers 1 with a pressure of 250kg~300kg, and no fragments are generated. By replacing the limiting sheet 2 with different thicknesses, the same thinning thickness can be applied to sapphire wafers 1 with different thicknesses, effectively improving the processing efficiency. The 180° peeling strength of the UV light peelable glue 4 of the workpiece after ultraviolet light irradiation is less than 1N / mm, the residual glue amount is low, the pollution to the sapphire wafer 1 is reduced, and the sapphire wafer 1 is prevented from breaking or fragmenting in the subsequent cleaning process. During the chemical mechanical polishing process, the wafer 1 can withstand greater pressure due to the superimposed thickness, the polishing quality is very high, and the thinning efficiency of the wafer 1 is greatly improved. The method of the present application is suitable for processing thin parts with a thickness of less than 1mm, and the upper limit of the grinding / polishing pressure can be increased by at least 35% compared with conventional methods.

[0108] It should be noted that the above description of the disclosed embodiments enables one of ordinary skill in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the scope of the present application. Therefore, the present application is not limited to the embodiments shown herein, but is intended to conform to the broadest scope consistent with the principles and novel features disclosed herein.

[0109] In the description of the present application, it should be noted that the terms "first", "second", "third" and the like are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0110] In the description of the present application, the terms "up", "down", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate the orientation or positional relationship shown in the drawings, and are only used to illustrate the relative positional relationship between the components or components, and do not particularly limit the specific mounting orientation of the components or components.

[0111] In the description of the present document, some terms can be used to represent the positional or positional relationship in addition to the meaning of the terms. For example, the term "upper" can also be used to represent a certain dependent relationship or connection relationship in some cases. For those skilled in the art, the specific meaning of these terms in the present application can be understood according to the specific circumstances.

[0112] In the description of the present document, the terms "mounting", "setting", "provided with", "connected", "connected" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally configured; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or internal communication between two devices, elements or components. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0113] The structure, proportion, size, etc. drawn in the drawings attached in the present application are only used to cooperate with the content disclosed in the present technical disclosure, so that those skilled in the art can understand and read, and do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that can be achieved by the present application, should still fall within the scope of the technical content disclosed by the present application.

[0114] The terms used in the present document are those general terms currently widely used in the art in consideration of the functions of the present disclosure, but these terms can vary according to the intention of those skilled in the art, precedents, or new technology in the art. In addition, specific terms can be selected by the applicant, and in this case, the detailed meaning thereof will be described in the detailed description of the present disclosure. Therefore, the terms used in the document should not be understood as mere names, but based on the meaning of the terms and the overall description of the present disclosure.

[0115] Flowcharts or words are used in the present document to illustrate the operation steps performed according to the embodiments of the present application. It should be understood that the operation steps in the embodiments of the present application are not necessarily executed in the order recorded. On the contrary, various steps can be processed in reverse order or simultaneously as needed. At the same time, other operations can be added to these processes, or one or more steps of operation can be removed from these processes.

[0116] The above is only the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A processing aid device for thinning a wafer, characterized by, The device comprises a base and at least one limiting sheet, the limiting sheet is connected with the end of the base, the limiting sheet is provided with a mounting hole for mounting a wafer, the wafer is detachably connected with one end of the base, the height difference between the limiting sheet and the end of the base is less than the height difference between the wafer to be processed and the end of the base; the limiting sheet is provided with two, and the two limiting sheets are respectively connected with the top end and the bottom end of the base; the base is a transparent plate carrier or a glass carrier which can transmit ultraviolet light, the wafer and the base are connected and fixed by UV light-induced peelable adhesive; the base is quartz glass; the limiting sheet is provided with a plurality of airflow injection holes along the circumferential direction, and the two ends of the airflow injection holes are respectively penetrated to the outside and the inside of the limiting sheet, and the airflow injection holes are horizontally arranged or obliquely arranged.

2. The processing aid for thinning a wafer according to claim 1, wherein The end of the base is stepped, so that the end of the base has a boss, and the limiting sheet is sleeved on the boss.

3. The processing aid for thinning a wafer according to claim 1, wherein The wafer and the mounting hole of the limiting sheet have a gap.

4. A method of processing a thinned wafer, the method comprising: The device for processing and thinning wafers according to any one of claims 1-3 comprises the following steps: a) mounting the limiting sheet on the top end and the bottom end of the base, respectively, and arranging a plurality of uniformly distributed airflow injection holes on the limiting sheet, and cleaning the connection between the upper surface and the lower surface of the base and the back surface of the wafer; b) coating UV light-induced peelable adhesive on the connection between the upper surface and the lower surface of the base and the back surface of the wafer, or coating UV light-induced peelable adhesive on the back surface of the wafer; c) placing two wafers to be processed in the mounting holes of the two limiting sheets, respectively, and bonding and fixing the wafers to the base through the coated UV light-induced peelable adhesive; d) fixing the base on a grinding and polishing equipment, and simultaneously grinding or polishing the back surfaces of the two wafers to thin the wafers; e) using an ultraviolet light irradiation device to irradiate the surface of the base which can transmit ultraviolet light, so that the UV light-induced peelable adhesive loses adhesion, thereby peeling off the wafers; f) annealing the wafers; e) cleaning the wafers by an ultrasonic cleaning equipment to obtain the thinned wafers.

5. The method of claim 4, wherein the thickness of the wafer is reduced by about 10 to 50 percent. The temperature during the grinding or polishing process of the wafers in step d is 34-36°C.

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