Processing auxiliary device and method for thinning wafer

Abstract

The invention belongs to the technical field of semiconductor processing, and particularly discloses a processing auxiliary device for thinning a wafer, which comprises a base body and at least one limiting piece, the limiting piece is connected with the end part of the base body, the limiting piece is provided with a mounting hole, the mounting hole is used for mounting and placing the wafer, and the limiting piece is arranged on the base body. The wafer is detachably connected with one end of the base body, and the height difference between the limiting piece and the end portion of the base body is smaller than the height difference between the wafer to be machined and the end portion of the base body. According to the invention, the wafer breaking or bending phenomenon can be reduced while the wafer thinning quality is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor processing, and in particular to a method for processing a thinned wafer. Background Art

[0002] With the rapid advancement of semiconductor technology, wafer thinning processes have become increasingly important in the manufacture of modern electronic devices. Wafer thinning can not only reduce product weight and material costs, but also improve device performance and integration. Therefore, optimizing wafer thinning processes has become an urgent need in the current semiconductor industry.

[0003] At present, wafer thinning technologies mainly include mechanical grinding, chemical mechanical polishing (CMP), laser thinning and other methods. These traditional processes face a series of challenges in implementation. For example, during mechanical grinding, the surface of the wafer is susceptible to scratches and wear, especially in the area where the back of the wafer contacts the substrate. If it is not cleaned thoroughly, it will cause contaminants such as colloids and particles to affect the wafer. This contamination will not only cause defects in subsequent processing, but may also have an adverse effect on the yield rate.

[0004] In addition, in the process of traditional bonding materials, the clamping method of thin-film parts is mainly through paraffin or vacuum adsorption, but it has certain limitations. The paraffin bonding method requires heating and cooling operations, which affects the surface stress of the workpiece, and it is difficult to ensure the uniformity of the paraffin coating. The parallelism of the final processed surface cannot be guaranteed, which increases the risk of product loss.

[0005] At present, in the process of wafer thinning, a planetary wheel is usually used to fix the wafer, and the wafer is driven to rotate by gears to achieve polishing and grinding. However, the existing method mostly fixes the polishing height, which cannot adapt to the processing requirements of wafers of different thicknesses, limiting the processing flexibility. In addition, this method has a poor effect on fixing the wafer, resulting in the risk of wafer breakage during the thinning process.

[0006] In addition, when processing wafers of different specifications, the adjustment and switching of the production line is cumbersome and time-consuming, which reduces the overall efficiency and flexibility of production. At the same time, traditional cleaning equipment is not effective in removing tiny contaminants, which may cause the accumulation of residues on the surface of the wafer, thus affecting subsequent processing steps.

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

[0008] The current wafer thinning process still faces many challenges, including contamination control, bonding process, processing efficiency, processing flexibility, pressure limit, low yield of ultra-thin wafers, etc. Therefore, it is urgent to find new solutions to improve the efficiency, quality and economy of wafer thinning. Summary of the invention

[0009] The invention provides a method for processing a thinned wafer, aiming at ensuring the wafer thinning quality while reducing the phenomenon of wafer fragmentation or bending.

[0010] The present invention is achieved through the following technical scheme: a processing auxiliary device for thinning a wafer, comprising a base and at least one limit plate, the limit plate is connected to the end of the base, a mounting hole is opened on the limit plate, the mounting hole is used to install and place the wafer, the wafer is detachably connected to one end of the base, and the height difference between the limit plate and the end of the base is smaller than the height difference between the wafer to be processed and the end of the base.

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

[0012] In this solution, the wafer is limited and fixed by using a base and a limiting plate. Since the wafer is placed in the mounting hole of the limiting plate and the back of the wafer is detachably connected to one end of the base, the wafer can be effectively clamped.

[0013] In the thinning process of ultra-thin wafers, since the processed wafers are extremely thin, the wafers are particularly prone to breakage during the processing. The auxiliary tools used in the processing of wafers in the prior art are not suitable for clamping and fixing ultra-thin wafers. When processing ultra-thin workpieces, the wafers cannot withstand greater grinding pressure and cause breakage, which seriously affects the quality and processing efficiency of the wafers.

[0014] In this solution, the setting of the substrate plays the role of stacking thickness and plays a role of supporting the rigidity of the wafer. In this way, when the wafer is thinned, the stacking of the substrate effectively improves the ability of the wafer to withstand greater polishing pressure, while ensuring the quality of wafer thinning, reducing the phenomenon of wafer fragmentation or bending, and achieving higher polishing efficiency during the processing. A processing auxiliary device for thinning wafers in this solution is very suitable for processing ultra-thin wafers. The processing auxiliary device of this solution is not limited by the thickness of the wafer workpiece, and thinner workpieces can be processed by using existing processing technology.

[0015] In addition, the setting of the limit plate in the present scheme can play a role in positioning the thinning thickness of the wafer, and can control the processing thickness requirements of the wafer, thereby improving the accuracy of the wafer thinning thickness. The limit plate can prevent the wafer from sliding on the substrate during the wafer processing and affecting the wafer processing accuracy, thereby ensuring the stability of the wafer during the thinning process.

[0016] Furthermore, two limiting plates are provided, and the two limiting plates are respectively connected to the top end and the bottom end of the base.

[0017] Beneficial effects: In this solution, the two limit plates are respectively located at the top and bottom of the base. This setting can thin the two wafers at the same time, thereby improving the processing efficiency. The setting of the two limit plates can change the thickness of the two limit plates to meet the needs of simultaneously processing two wafers and obtain wafers of different thicknesses, thereby improving work efficiency.

[0018] Furthermore, the substrate is a transparent plate carrier or a glass carrier that can transmit ultraviolet light, and the wafer and the substrate are connected and fixed by UV light-induced strippable adhesive.

[0019] Beneficial effect: In this solution, the wafer and the substrate are connected by UV photo-strippable adhesive, and the substrate can transmit ultraviolet light. Therefore, after the wafer thinning process is completed, the UV photo-strippable adhesive is irradiated by an ultraviolet light device to soften it and then the wafer workpiece can be peeled off.

[0020] Furthermore, the substrate is quartz glass.

[0021] Beneficial effects: Quartz glass has high temperature resistance, good thermal stability, excellent optical properties, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection, so ultraviolet light can be irradiated through the substrate to soften the UV photo-strippable adhesive and then realize the stripping of the wafer.

[0022] Furthermore, a plurality of airflow injection holes are provided on the limiting plate along its circumference, and two ends of the plurality of airflow injection holes respectively penetrate the outer side and the inner side of the limiting plate.

[0023] Beneficial effect: The air flow injection holes in this solution can be connected to an external high-pressure injection device through a pipeline. The high-pressure injection device provides high-pressure gas and sprays it to the inner side of the mounting hole of the limit plate through multiple air flow injection holes to clean the surface of the substrate that will be connected to the wafer later. In this way, when the wafer is placed in the mounting hole and fixed to the substrate surface, contamination and scratches on the back of the wafer can be prevented.

[0024] Furthermore, the plurality of airflow injection holes are all arranged horizontally or inclined.

[0025] Beneficial effect: This solution provides two ways of setting the airflow injection holes. The way of setting the airflow injection holes horizontally is more convenient for processing and manufacturing, while the way of setting the airflow injection holes obliquely has a better cleaning effect on the surface of the substrate.

[0026] Furthermore, the end of the base is in a step shape, so that the end of the base has a boss, and the limiting piece is sleeved on the boss.

[0027] Beneficial effect: In this solution, a boss is arranged on the end of the base, so that it is convenient to put the limit plate on the boss, and to directly replace the limit plates with different thicknesses according to the thickness of the wafer that needs to be thinned. By replacing the limit plates with different thicknesses, it can adapt to the processing of wafers with different thicknesses and meet the requirement of achieving the same thinning thickness for wafers with different thicknesses at the same time, thereby meeting diversified production needs and having strong processing flexibility.

[0028] Moreover, the setting of the boss can limit the limiting plate. After the limiting plate is mounted on the boss, there will be no shaking. When the wafer is thinned, the stability of the wafer can be ensured, thereby improving the accuracy of wafer processing.

[0029] Furthermore, there is a gap between the wafer and the mounting hole of the limiting plate.

[0030] Beneficial effect: Such an arrangement can provide a certain buffer space for the wafer during the processing, which can effectively prevent the wafer from being broken during the processing.

[0031] A method for processing a thinned wafer, using the above-mentioned processing auxiliary device for thinning a wafer, comprises the following steps:

[0032] a) Installing limiting plates at the top and bottom of the substrate respectively, and setting a plurality of evenly distributed air flow injection holes on the limiting plates to clean the connection between the upper and lower surfaces of the substrate and the back of the wafer;

[0033] b) applying UV photo-strippable adhesive on the upper and lower surfaces of the substrate at the junction with the back of the wafer;

[0034] c) placing the two processed wafers in the mounting holes of the two limiting plates respectively, and bonding and fixing them to the substrate via UV photo-strippable adhesive coated on the surface of the substrate;

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

[0036] e) using an ultraviolet irradiation device to irradiate the surface of the substrate that is transparent to ultraviolet light, so that the UV light-induced strippable adhesive loses its stickiness, thereby stripping the wafer;

[0037] f) performing annealing treatment on the wafer;

[0038] e) Cleaning the wafer by ultrasonic cleaning equipment to obtain a thinned wafer.

[0039] Beneficial effects: This scheme utilizes a grinding and polishing device to process a wafer workpiece. This method cleans the surface of the substrate through the airflow injection holes arranged on the limiting plate to prevent contamination and scratches on the back of the wafer. This method fixes the wafer workpiece on the substrate through UV photo-strippable adhesive, and after the wafer workpiece is ground or polished, the UV photo-strippable adhesive is irradiated by an ultraviolet light device to soften it and thereby realize the stripping of the wafer workpiece.

[0040] This method uses a limit plate on the substrate to limit the thin workpiece from sliding along the substrate plane during processing; the substrate material uses a transparent plate carrier or glass carrier with a very high surface flatness and can transmit ultraviolet light, which plays a rigid supporting role for the wafer. This method uses the substrate to achieve superimposed thickness to enhance the ability of the workpiece (wafer) to withstand greater polishing pressure; in this method, both the substrate and the limit plate can adopt a structure with a high overall flatness, and the wafer is easy to load and unload, which is suitable for the processing of ultra-thin wafers.

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

[0042] Beneficial effect: The temperature set during the grinding or polishing process should avoid high temperature. The temperature in this solution is appropriate to avoid deformation of the wafer material caused by high temperature.

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

[0044] 1. Air jet cleaning on the limiting plate: Air jet holes are set on the limiting plate to clean the substrate surface by air impact to prevent contamination and scratches on the back of the wafer.

[0045] 2. Use limit plates to fix the wafer: Use limit plates with adjustable height to fix the wafer to be thinned, ensure the stability of the wafer during the thinning process, and meet the thinning requirements of wafers of different thicknesses.

[0046] 3. UV photo-strippable adhesive curing: UV photo-strippable 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 back-grinded / polished thinning to improve overall work efficiency.

[0048] 5. Use of ultraviolet irradiation device: The ultraviolet irradiation device arranged in the substrate is used to dissolve the UV photo-strippable adhesive, thereby realizing the stripping of the wafer.

[0049] 5. Laser annealing: 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 properties of the wafer.

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

[0051] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0052] Figure 1 This is an exploded schematic diagram of a wafer and a substrate in an embodiment of a wafer thinning processing auxiliary device of the present invention;

[0053] Figure 2 It is a schematic structural diagram of a wafer and a substrate connected in an embodiment of a wafer thinning processing auxiliary device of the present invention;

[0054] Figure 3 A three-dimensional diagram of a limiting piece in an embodiment of a wafer thinning processing auxiliary device of the present invention;

[0055] Figure 4 A three-dimensional diagram of a wafer and a limiting piece in an embodiment of a wafer thinning processing auxiliary device of the present invention;

[0056] Figure 5 A top view of a wafer and a limiting piece in an embodiment of a wafer thinning processing auxiliary device of the present invention;

[0057] Figure 6 It is a schematic structural diagram of an embodiment of a wafer thinning processing auxiliary device of the present invention in which the air flow injection holes on the limiting plate are arranged obliquely;

[0058] Figure 7 This is a front view of the base in Example 3 of a processing auxiliary device for thinning a wafer according to the present invention.

[0059] Marks and corresponding parts names in the attached drawings:

[0060] Wafer 1, limiting piece 2, mounting hole 201, substrate 3, boss 301, UV photo-strippable adhesive 4, air flow injection hole 5, ultraviolet irradiation device 6. DETAILED DESCRIPTION

[0061] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0062] Example 1

[0063] like Figure 1-Figure 2 As shown, this embodiment 1 provides a wafer thinning processing auxiliary device, including a base 3 and at least one stopper 2, and the stopper 2 is connected to the end of the base 3. Figure 3 As shown, a mounting hole 201 is provided on the limiting piece 2, and the mounting hole 201 is located at the center of the limiting piece 2. In this embodiment, the limiting piece 2 is in a circular ring shape as a whole, and the top and bottom ends of the limiting piece 2 are both flat.

[0064] like Figure 4 As shown, the mounting hole 201 is used to mount the 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 plate 2, thereby reserving a certain buffer space for the wafer 1, so that the wafer 1 can be protected during the processing of the wafer 1 and the damage to the wafer 1 can be reduced.

[0065] The height difference between the limiting plate 2 and the end of the base 3 is smaller than the height difference between the wafer 1 to be processed and the end of the base 3, so that a portion of the wafer 1 to be processed can be exposed after being placed on the limiting plate 2, which is used to control the thickness of the wafer 1 after grinding and thinning. In this way, by replacing the limiting plates 2 with different thicknesses, the wafer 1 with different thinning requirements can be thinned.

[0066] In this embodiment, two limit plates 2 are provided, and the two limit plates 2 are respectively connected to the top and bottom ends of the base 3. The limit plates 2 and the base 3 can be fixed by adhesive or screws. The limit plates 2 can be removed from the base 3 and replaced with limit plates 2 of different thicknesses according to the different thicknesses of the wafer 1 to be thinned to, thereby meeting the requirements of processing wafers 1 of different thicknesses.

[0067] The provision of two limiting plates 2 in this embodiment facilitates the installation of the wafers 1 to be processed at the top and bottom of the base 3, respectively, so that two wafers 1 can be thinned at the same time, effectively improving the work efficiency.

[0068] Combination Figure 2As shown, the wafer 1 is detachably connected to one end of the substrate 3. The substrate 3 in this embodiment is a transparent plate carrier or glass carrier with a flat surface and transparent to ultraviolet light. The wafer 1 and the substrate 3 are connected and fixed by a UV photo-strippable adhesive 4. Since the wafer 1 is fixed on the surface of the substrate 3, when the wafer 1 is under pressure, the wafer 1 may be deformed to a certain extent. Therefore, the application of the UV glue needs to be uniform and pollution-free, so that the wafer 1 has a higher flatness after processing. The UV photo-strippable adhesive 4 has high adhesion before UV light curing and high viscosity reduction after UV irradiation, which can meet the requirements of thinning the wafer 1. In this embodiment, the coating thickness of the UV photo-strippable adhesive 4 is 50um to 55um.

[0069] In this embodiment, since a reserve is made for the thickness of the UV photo-strippable adhesive 4 and the thickness that needs to be thinned, the thickness of the limiting plate 2 is preferably 80%-94% of the thickness of the wafer 1 to be processed. This can better fix the wafer 1 to ensure that it does not slide along the substrate 3, and can thin the wafer 1 to the required thinning thickness.

[0070] Furthermore, in the present embodiment, the substrate 3 is quartz glass, which has high temperature resistance, good thermal stability, excellent optical properties, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection, so ultraviolet light can be irradiated through the substrate 3 to soften the UV photo-strippable adhesive 4 and thus realize the stripping of the wafer 1. Quartz glass has high temperature resistance, good thermal stability, excellent optical properties, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection, so ultraviolet light can be irradiated through the substrate 3 to soften the UV photo-strippable adhesive 4 and thus realize the stripping of the wafer 1.

[0071] The UV photo-peelable adhesive 4 in this embodiment has the properties of UV-curable pressure-sensitive adhesive when used. Pressure-sensitive adhesive refers to a colloid that is sensitive to pressure and can be firmly adhered to the surface of the adherend with very weak pressure. UV-curable pressure-sensitive adhesive has a fast curing rate, saves energy, saves costs, has simple curing equipment, and occupies a small area.

[0072] In addition to the advantages of UV-curing pressure-sensitive adhesives, UV photo-peelable adhesive 4 can also be completely peeled off in a short time, and the transition from "sticky" to "non-sticky" occurs. The present invention uses UV photo-peelable adhesive 4 to fix wafer 1, and wafer 1 can be easily peeled off by ultraviolet light. After ultraviolet light irradiation, the C=C double bonds are greatly reduced, and the photosensitive resin itself is cross-linked. The large volume shrinkage caused by cross-linking will cause wrinkles on the interface between the adhesive and the adhered object, and micropores will appear in places where the shrinkage is more serious. The wrinkles and micropores generated damage the interface, resulting in a reduction in the bonding area, which is the fundamental reason for the loss of colloid adhesion.

[0073] The constituent material of the substrate 3 in this embodiment is quartz glass, which has high temperature resistance, good thermal stability, excellent optical properties, excellent chemical stability, electrical insulation, high mechanical strength, biocompatibility, processability and environmental protection. Therefore, ultraviolet light can be irradiated through the substrate 3 to soften the UV photo-strippable adhesive 4 and thus realize the stripping of the wafer 1.

[0074] In this embodiment, the UV photo-strippable adhesive 4 can cooperate with the ultraviolet irradiation device 6 to irradiate the substrate 3, and transmit the ultraviolet light through the substrate 3 to achieve efficient and non-destructive stripping of the wafer 1, thereby preventing the wafer 1 from being broken or fragmented during the unloading process.

[0075] In this embodiment, the limiting plates 2 of different thicknesses can be replaced according to actual needs, which not only meets the requirement of simultaneously performing back grinding or polishing thinning on two wafers 1 to obtain thinned wafers 1, but also meets the requirement of simultaneously thinning wafers 1 of different thicknesses to the same thinning thickness, thereby greatly improving the processing efficiency.

[0076] The present invention adopts a substrate 3, which realizes a stacking thickness method and can improve the ability of the workpiece to withstand greater polishing pressure, thereby obtaining a higher polishing efficiency. Since the substrate 3 is made of 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 can use existing processing technology to process thinner workpieces. The thickness of the wafer 1 to be processed in this embodiment is less than 1 mm, and the processing auxiliary device for thinning the wafer using the present invention is suitable for processing ultra-thin wafer 1 workpieces with a thickness of less than 1 mm.

[0077] The specific implementation process is as follows:

[0078] In this embodiment, after coating UV photo-strippable adhesive 4 on the top and bottom ends of the substrate 3 where they are connected to the wafer 1, the wafer 1 is placed in the mounting hole 201 of the limiting plate 2 and the back side of the wafer 1 to be processed is connected and fixed to the surface of the substrate 3 by the UV photo-strippable adhesive 4, with a gap between the wafer 1 and the limiting plate 2.

[0079] The left and right ends of the substrate 3 are mounted on a grinding and polishing device. The polishing head on the grinding and polishing device grinds or polishes the wafer 1 on the top and bottom ends of the substrate 3 to achieve thinning processing on the wafer 1 .

[0080] Compared with the prior art, the present embodiment can adapt to the processing of wafers 1 of different thicknesses by replacing the limit plates 2 of different thicknesses, meet the diversified production needs, and have strong processing flexibility; the UV photo-strippable adhesive 4 is combined with the ultraviolet irradiation device 6 to ensure that the stripping process is simple and controllable, reduce damage to the wafer 1, and the UV photo-strippable adhesive 4 has high bonding strength, enhances the stability of the wafer 1, and its debonding operation is simple, and the colloid is more environmentally friendly; the back grinding / polishing thinning of the double wafer 1 greatly improves the production efficiency; the setting of the substrate 3 provides a method of stacking thickness, thereby increasing the upper limit of pressure and having higher processing efficiency, and the substrate 3 has a high flatness, which is suitable for the processing of ultra-thin wafers 1.

[0081] Example 2

[0082] The difference between this embodiment and embodiment 1 is that: Figure 3 and Figure 4 As shown, a plurality of airflow injection holes 5 are evenly formed on the limiting plate 2 along its circumference, and both ends of the plurality of airflow injection holes 5 respectively penetrate the outer side and the inner side of the limiting plate 2. The diameter of the airflow injection holes 5 is 0.1 mm to 0.2 mm.

[0083] Combination Figure 2 and Figure 6 As shown, the multiple air flow injection holes 5 are arranged horizontally or inclined, and the air flow injection holes 5 are connected to the high-pressure injection equipment through a pipeline. In this way, before installing the wafer 1, gas can be sprayed to the inside of the installation hole 201 through the air flow injection holes 5, and the connection position between the substrate 3 and the wafer 1 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, so that the end of the base 3 has a boss 301, and the limiting piece 2 is sleeved on the boss 301. In this embodiment, the top and bottom ends of the base 3 both have cylindrical bosses 301, and the two limiting pieces 2 are respectively sleeved on the two bosses 301. The two bosses 301 can play a more stable limiting role for the limiting piece 2, and can prevent the limiting piece 2 from shaking and moving.

[0086] The boss 301 in this embodiment has a positioning function for the installation 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 embodiment is that: this embodiment provides a method for processing a thinned wafer, using a processing auxiliary device for thinning a wafer in the above embodiment, including the following steps:

[0089] a) Installing a limit plate 2 at the top and bottom of the substrate 3 respectively, and providing a plurality of evenly distributed airflow injection holes on the limit plate 2 to clean the connection between the upper and lower surfaces of the substrate 3 and the back of the wafer 1;

[0090] b) coating a UV photo-strippable adhesive 4 on the connection between the upper surface and the lower surface of the substrate 3 and the back surface of the wafer 1 or coating a UV photo-strippable adhesive 4 on the back surface of the wafer 1;

[0091] c) placing two processed wafers 1 in the mounting holes 201 of the two limiting plates 2 respectively, and bonding and fixing them to the substrate 3 by applying UV photo-strippable adhesive 4;

[0092] d) fixing both ends of the substrate 3 on a grinding and polishing device, and simultaneously grinding or polishing the back sides of the two wafers 1 to thin the wafers 1; the temperature set during the grinding or polishing process should avoid high temperature. In this embodiment, the temperature set during the grinding or polishing process of the wafer 1 is 34° C.-36° C.;

[0093] e) using an ultraviolet irradiation device 6 to irradiate the surface of the substrate 3 which is transparent to ultraviolet light, so that the UV light-induced strippable adhesive 4 loses its stickiness, thereby stripping the wafer 1;

[0094] f) performing annealing on the wafer 1. In this embodiment, laser annealing technology is used to anneal the wafer 1 to reduce thermal damage to the wafer 1. The laser annealing technology in this embodiment may adopt other types of annealing processes, such as electron beam annealing or plasma annealing;

[0095] e) Cleaning the wafer 1 by ultrasonic cleaning equipment to obtain a thinned wafer 1.

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

[0097] The wafer 1 to be processed can be a variety of semiconductor materials such as sapphire. In this embodiment, two 6-inch sapphire wafers 1 are selected as the objects to be thinned. The initial thickness of the sapphire wafers 1 is 925um and 950um, respectively, and the target thickness after thinning is 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 limit plate 2.

[0098] First, the high-pressure gas in the airflow injection hole 5 generates airflow impact to clean the surface of the substrate 3 to prevent the residue of colloids and particles. Next, the wafer 1 is placed in the mounting hole 201 of the limit plate 2, and the heights of the upper and lower limit plates 2 are adjusted to 850um and 875um respectively according to the thickness of the wafer 1.

[0099] Subsequently, UV photo-strippable adhesive 4 is evenly applied to the contacting side of sapphire wafer 1 and substrate 3, and the thickness of UV adhesive coating is 50 um. Chemical mechanical polishing is performed on the two wafers 1 at the same time, and the thicknesses are thinned to 900 um and 925 um respectively.

[0100] After the thinning is completed, the ultraviolet irradiation device 6 is started, and 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, and the wafer 1 is peeled.

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

[0102] When processing a 6-inch sapphire wafer 1, the method of the present invention applies a pressure of 250kg to 300kg without causing fragmentation. And by replacing the limit pieces 2 of different thicknesses, sapphire wafers 1 of different thicknesses can be thinned to the same thickness at the same time, thereby improving processing efficiency. After being irradiated with ultraviolet light, the 180° peeling strength of the workpiece is less than 1N / mm, and the amount of residual glue is low, which can meet the requirements of back grinding / polishing of the sapphire wafer 1. During the chemical mechanical polishing of the workpiece, 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 thinning the wafer 1 is greatly improved.

[0103] Example 5

[0104] The difference between this embodiment and embodiment 4 is that in this embodiment, two 6-inch sapphire wafers 1 are selected for ultra-thin processing, with an initial thickness of 375um and a target thickness after thinning of 350um.

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

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

[0107] When processing a 6-inch ultra-thin sapphire wafer 1, the method of the present invention applies a pressure of 250kg to 300kg, and no fragments occur. And by replacing the stopper pieces 2 of different thicknesses, the sapphire wafers 1 of different thicknesses can be thinned to the same thickness at the same time, which effectively improves the processing efficiency. The 180° peeling strength of the UV photo-strippable adhesive 4 of the workpiece after ultraviolet light irradiation is less than 1N / mm, and the residual adhesive amount is low, which reduces the contamination of the sapphire wafer 1 and avoids the sapphire wafer 1 from breaking or fragmenting in the subsequent cleaning procedure. During the chemical mechanical polishing of the workpiece, due to the influence of the superimposed thickness, the wafer 1 can withstand greater pressure, the polishing quality is very high, and the efficiency of thinning the wafer 1 is greatly improved. The method of the present invention is suitable for processing thin-sheet 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 professionals and technicians in the field to implement or use the present application. Various modifications to these embodiments will be apparent to professionals and technicians in the field, 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 will not be limited to the embodiments shown herein, but should conform to the widest scope consistent with the principles and novel features disclosed herein.

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

[0110] In the description of this document, terms such as "up", "down", "left", "right", "front", "back", "top", "bottom", "inside", "outside", "middle", "vertical", "horizontal", "lateral", and "longitudinal" indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only used to illustrate the relative positional relationships between the various components or components, and do not particularly limit the specific installation orientations of the various components or components.

[0111] In the description of this document, some terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to the specific circumstances.

[0112] In the description of this document, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0113] The structures, proportions, sizes, etc. drawn in the drawings in this application are only used to match the contents disclosed in this technical briefing book for technical personnel in this field to understand and read, and are not used to limit the restrictive conditions for the implementation of this application. Therefore, they have no substantive technical significance. Any structural modification, change in proportional relationship or adjustment of size should still fall within the scope of the technical content disclosed in this application without affecting the effects and purposes that can be achieved by this application.

[0114] The terms used in this document are those common terms currently widely used in the art in consideration of the functions of the present disclosure, but these terms may vary according to the intention of a person of ordinary skill in the art, precedents, or new technologies in the art. In addition, specific terms may be selected by the applicant, and in this case, their detailed meanings will be described in the detailed description of the present disclosure. Therefore, the terms used in the document should not be understood as simple names, but rather as an overall description based on the meaning of the terms and the present disclosure.

[0115] Flowcharts or text are used in this document to illustrate the operating steps performed according to the embodiments of the present application. It should be understood that the operating steps in the embodiments of the present application are not necessarily accurately performed in the order of recording. On the contrary, various steps can be processed in reverse order or simultaneously as needed. At the same time, other operations can also be added to these processes, or a certain step or several steps can be removed from these processes.

[0116] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, 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 auxiliary device for thinning a wafer, characterized in that: It includes a base and at least one limiting plate, wherein the limiting plate is connected to the end of the base, a mounting hole is provided on the limiting plate, and the mounting hole is used to install and place a wafer. The wafer is detachably connected to one end of the base, and a height difference between the limiting plate and the end of the base is smaller than a height difference between the wafer to be processed and the end of the base.

2. The wafer thinning processing auxiliary device according to claim 1, characterized in that: There are two limit plates, which are respectively connected to the top and bottom ends of the base.

3. The processing auxiliary device for thinning a wafer according to claim 1, characterized in that: The substrate is a transparent plate carrier or a glass carrier that can transmit ultraviolet light, and the wafer and the substrate are connected and fixed by UV light-induced strippable adhesive.

4. The wafer thinning processing auxiliary device according to claim 3, characterized in that: The substrate is made of quartz glass.

5. A wafer thinning processing auxiliary device according to any one of claims 1 to 4, characterized in that: The limiting plate is provided with a plurality of airflow injection holes along its circumference, and two ends of the plurality of airflow injection holes respectively penetrate the outer side and the inner side of the limiting plate.

6. The wafer thinning processing auxiliary device according to claim 5, characterized in that: The plurality of airflow injection holes are all arranged horizontally or inclined.

7. A wafer thinning processing auxiliary device according to any one of claims 1 to 4, characterized in that: The end of the base is in a step shape, so that the end of the base has a boss, and the limiting piece is sleeved on the boss.

8. The wafer thinning processing auxiliary device according to claim 1, characterized in that: There is a gap between the wafer and the mounting hole of the limiting plate.

9. A method for processing a thinned wafer, characterized in that: The process of using a wafer thinning auxiliary device according to any one of claims 1 to 8 comprises the following steps: a) Installing limiting plates at the top and bottom of the substrate respectively, and setting a plurality of evenly distributed air flow injection holes on the limiting plates to clean the connection between the upper and lower surfaces of the substrate and the back of the wafer; b) coating a UV photo-strippable adhesive on the connection between the upper surface and the lower surface of the substrate and the back side of the wafer or coating a UV photo-strippable adhesive on the back side of the wafer; c) placing the two processed wafers in the mounting holes of the two limiting plates respectively, and bonding and fixing them to the substrate by applying UV photo-strippable adhesive; d) fixing the substrate on a grinding and polishing device, and simultaneously back-grinding or polishing the two wafers to thin the wafers; e) using an ultraviolet irradiation device to irradiate the surface of the substrate that is transparent to ultraviolet light, so that the UV light-induced strippable adhesive loses its stickiness, thereby stripping the wafer; f) performing annealing treatment on the wafer; e) Cleaning the wafer by ultrasonic cleaning equipment to obtain a thinned wafer.

10. The method for processing a thinned wafer according to claim 9, characterized in that: The temperature set during the grinding or polishing of the wafer in step d is 34° C.-36° C.

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