High-uniformity low-damage chip deep thinning method based on single-point diamond cutting

Abstract

The invention discloses a high-uniformity low-damage chip deep thinning method based on single-point diamond cutting. Comprising the following steps: step S100, carrying out fine polishing treatment on the back surface of a chip, and thinning the chip to a middle thickness; and the middle thickness is 80 to 120 [mu] m. And S200, carrying out ultra-precision fly cutting on the back surface of the chip processed in the step S100 by using a single-point diamond cutter, and cutting the back surface of the chip to a target thickness. The invention provides a composite thinning process combining fine polishing pretreatment and single-point diamond cutting, and aims to realize ultrahigh thickness uniformity and extremely low surface damage of a chip, so that the quantum efficiency of the chip is remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of semiconductor ultra-precision machining technology, and in particular to a high-uniformity, low-damage chip deep thinning method based on single-point diamond cutting. Background Technology

[0002] The structure of an infrared detector is simply divided into three layers: a substrate layer (cadmium zinc telluride), an absorption layer (mercury cadmium telluride), and a readout circuit. The absorption layer (mercury cadmium telluride) is the most critical, but infrared light must first pass through the substrate. If the substrate absorbs most of the infrared light, the signal reaching the absorption layer will be weakened, thus affecting the detector's response. In order to obtain high-performance infrared focal plane array devices, it is necessary to thin the detector chip by removing the substrate or completely removing the substrate.

[0003] In existing technologies, mechanical grinding, chemical mechanical polishing, or chemical polishing are commonly used to thin chips. However, these thinning methods all have certain drawbacks:

[0004] Mechanical polishing: Mechanical polishing is generally used as a pre-processing step for fine polishing. It requires rapid material removal, and the material removal rate is related to the abrasive grain size. Typically, the processed surface has a large damage layer thickness, and is prone to introducing cracks and stress. These damages can become non-radiative recombination centers, severely reducing the quantum efficiency of the chip.

[0005] Chemical mechanical polishing (CMP): While it can achieve good surface quality, it is influenced by many factors, such as the polishing pad material, type of polishing slurry, slurry ratio, and the addition of surfactants and dispersants. Furthermore, the actual polishing effect varies significantly between slurries from different manufacturers, making the slurry ratio and selection particularly important during processing. A balance between chemical and mechanical actions is required during polishing; when chemical action is dominant, orange peel effect is easily produced, while when mechanical action is dominant, scratches appear, making practical operation difficult. In addition, the thickness uniformity of back thinning processes using CMP on existing production lines is concentrated between 5-8 μm, and in some cases even exceeds 10 μm, which is significantly different from the target requirements.

[0006] Chemical polishing (CP): The entire polishing process involves almost no mechanical action, mainly chemical corrosion. The most significant problem in this process is edge collapse, which easily results in a surface that is thick in the middle and thin at the edges, making it difficult to guarantee thickness uniformity. Summary of the Invention

[0007] To address the shortcomings of existing thinning technologies, this invention proposes a composite thinning process that combines fine polishing pretreatment with single-point diamond cutting. This process aims to achieve ultra-high thickness uniformity (submicron level) and extremely low surface damage in chips, thereby significantly improving the quantum efficiency of the chips.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for high-uniformity, low-damage chip thinning based on single-point diamond cutting, characterized by comprising the following steps:

[0010] Step S100: Perform fine polishing on the back of the chip to thin the chip to an intermediate thickness; the intermediate thickness is 80 to 120 μm.

[0011] Step S200: Use a single-point diamond tool to perform ultra-precision flying cut on the back side of the chip processed in step S100, cutting it to the target thickness.

[0012] Furthermore, during the ultra-precision flying cut operation in step S200, the chip is positioned using a tooling fixture;

[0013] The tooling fixture includes a base plate, a chip support for supporting the chip, and a stop assembly for limiting chip displacement; the chip support is fixed to the upper end of the base plate; the stop assembly is disposed on the outer ring of the chip support;

[0014] The chip support has a groove at its upper end; the groove has a mesh-like groove structure and is connected to the vacuum suction cup.

[0015] During the ultra-precision flying cut operation, the chip is placed on the upper part of the chip support, blocking the upper port of the groove; a vacuum is drawn by a vacuum chuck to create a negative pressure under the chip, and the chip is then vacuum-adsorbed and fixed to the upper part of the chip support.

[0016] Furthermore, the chip support includes a number of spaced square blocks and annular protrusions; all square blocks are located in the inner circle of the annular protrusions; the grooves are the spacing grooves between adjacent square blocks and between the square blocks and the annular protrusions, presenting an overall grid-like groove structure.

[0017] The bottom of the groove is provided with several through-hole ventilation holes; the vacuum suction cup is assembled at the lower end of the tooling fixture, and the groove is connected to the airflow interface of the vacuum suction cup through the ventilation holes.

[0018] Furthermore, the stop assembly includes a plurality of stops spaced apart along the outer ring of the chip support; the lower end of the stop is fixedly or detachably connected to the upper end of the base plate; the height of the stop is higher than the height of the chip support, but lower than the total height of the chip after clamping.

[0019] Furthermore, the outer ring of the chip support is provided with a step block between two adjacent blocks. The upper surface of the step block is a step surface, and the height of the step surface is lower than the height of the chip support.

[0020] Furthermore, a bottom groove is provided at the bottom of the base plate; the bottom groove connects the vacuum suction cup and the vent hole.

[0021] Furthermore, in step S200:

[0022] First, a single-point diamond tool is used to rough cut the back of the chip. During the rough cutting operation, the process parameters of single-point diamond cutting are: spindle speed: 1300-1500 rpm, table feed rate: 15-18 mm / min, feed rate: 5-10 μm.

[0023] Then, a single-point diamond tool is used to perform a fine cutting operation on the back of the chip after the rough cutting operation. During the fine cutting operation, the process parameters of single-point diamond cutting are: spindle speed: 1300-1500rpm, table feed speed: 7-10mm / min, feed rate: 1-3μm.

[0024] Furthermore, after completing step S200, the thickness uniformity of the chip cut to the target thickness is less than 2μm.

[0025] Furthermore, after completing step S200, the surface roughness Ra value of the chip cut to the target thickness is less than 10 nm.

[0026] Furthermore, in step S100, the back of the chip is finely polished using a chemical mechanical polishing method; step S200 is performed in a constant temperature, clean, and shock-resistant environment.

[0027] Compared with existing technologies, the invention provides a high-uniformity, low-damage chip thinning method based on single-point diamond cutting, which has the following advantages:

[0028] 1. Ultra-high thickness uniformity: Due to the extremely high precision of the single-point diamond cutting process, the rotational accuracy of the spindle and the straightness of the guide rail can be perfectly replicated. Therefore, this invention can control the thickness uniformity of the chip to within 2μm, or even reach 0.5μm or higher. This is far superior to traditional mechanical polishing techniques.

[0029] 2. Low surface damage: Pre-polishing removes deep damage and stress from rough machining. In ultra-precision cutting, single-point diamond cutting is performed with extremely small depths of cut and feed rates, operating within the "brittle" or even "plastic" domain. Material is removed through microscopic plastic flow, significantly suppressing crack initiation and propagation. The resulting surface roughness Ra value can reach below 10 nm.

[0030] 3. Significantly Improved Device Performance: Due to minimal surface damage, surface states and non-radiative recombination centers are reduced; due to high thickness uniformity, the optical path difference generated when infrared light passes through materials of different thicknesses is small, which significantly improves the uniformity of quantum efficiency for infrared focal plane detectors. Experimental data show that the quantum efficiency of the chip thinned using the method of this invention is about 30% higher than that of chips manufactured by traditional processes.

[0031] 4. Synergistic Effect of Process Combination: This invention creatively combines "high-efficiency polishing for removal" with "high-precision, low-damage single-point diamond cutting technology." Polishing provides a qualified "blank" for ultra-precision cutting, avoiding chip cracking and tool damage caused by directly cutting thick chips, and shortening processing time; while single-point diamond cutting achieves the ultimate precision that polishing cannot reach. The two complement each other, ensuring efficiency while achieving processing quality that cannot be achieved by a single process.

[0032] 5. In this invention, in step S200, a tooling fixture is used to position the chip; a vacuum chuck is used to adsorb and fix the chip, so that it is fixed to the upper end of the chip support in the tooling fixture after being adsorbed during the thinning operation. With the assistance of the stop block on the outer ring of the chip support, under the above-mentioned limiting and fixing method, the position of the chip will be accurately and stably limited within the preset position, which can achieve better cutting effect. Compared with the traditional wax bonding and fixing method, the heating, melting and cooling of wax during the wax bonding process already causes a large thickness deviation in thickness uniformity; secondly, the wax bonding process tests the operator's skill level, and different operators can have very different operations for the same process; finally, the combination of vacuum adsorption and stop block makes it less likely for the chip to shift or tilt during the thinning operation, which is more conducive to achieving uniform chip cutting and reducing the thickness difference of the chip after the thinning operation.

[0033] 6. In this invention, there are several spaced-apart blocks, the lower end of which is fixedly connected to the upper end of the base plate by screws; the height of the blocks is lower than the total height of the chip after it is clamped.

[0034] Multiple stops are used to constrain the chip's position, ensuring that the chip does not shift during processing. Simultaneously, the stops also buffer some of the cutting force. The stable chip position during operation facilitates more uniform thickness during cutting, reducing thickness variations after machining. Attached Figure Description

[0035] Figure 1 This is a flowchart of the high-uniformity, low-damage chip deep thinning method based on single-point diamond cutting in the invention.

[0036] Figure 2 This is a simplified diagram of the infrared detection chip in this invention.

[0037] Figure 3 This is a schematic diagram of the positional distribution structure between the vacuum chuck, tooling fixture, and chip in step S200 of the present invention.

[0038] Figure 4 This is a schematic diagram of the connection structure between the spindle disk and the single-point diamond tool in the ultra-precision single-point diamond milling machining center of the present invention.

[0039] Figure 5 This is a three-dimensional view of a tooling fixture in this invention.

[0040] Figure 6 This is a top view of a tooling fixture in this invention.

[0041] Figure 7 It is a sectional view along the AA direction.

[0042] Figure 8 It is a sectional view along the BB direction.

[0043] Figure 9 This is a schematic diagram of the bottom structure of a tooling fixture in this invention.

[0044] Figure 10 This is a schematic diagram of the structure of the stop block in this invention.

[0045] Figure 11 This is a schematic diagram of the tooling fixture after the chip is assembled in this invention (the position of the three stops is shown in the figure).

[0046] Figure 12 This is a comparison diagram of the thickness uniformity before and after cutting using the single-point diamond cutting process in this invention.

[0047] Figure 13 This is a schematic diagram showing the percentage of thickness uniformity distribution using the single-point diamond cutting process in this invention.

[0048] In the picture:

[0049] 1-Spindle disk, 2-Single-point diamond tool, 3-Vacuum chuck, 4-Tooling fixture, 5-Chip;

[0050] 40-Base plate, 41-Stop block, 42-First step block, 43-Second step block, 44-Third step block, 45-Annular protrusion, 46-Chip pad block, 47-Bottom groove, 48-Ventilation hole, 49-Groove;

[0051] 51-Substrate layer, 52-Absorbing layer, 53-Readout circuit;

[0052] 61 - Stop block mounting area; 62 - Screw mounting hole;

[0053] 70-chip. Detailed Implementation

[0054] The technical solutions of the embodiments of the invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Based on the embodiments of the invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the invention.

[0055] The invention provides a method for high-uniformity, low-damage chip thinning based on single-point diamond cutting, the flowchart of which is shown below. Figure 1 As shown.

[0056] Specifically, this embodiment provides an infrared detector chip epitaxially grown on a cadmium zinc telluride substrate, with an initial thickness of approximately 350 μm.

[0057] The high-uniformity, low-damage chip thinning method based on single-point diamond cutting described in this invention is used to thin an infrared detector chip with an initial thickness of approximately 350 μm. The specific steps include:

[0058] Step S100: Perform fine polishing on the back side of the chip (i.e., the substrate layer of the chip) to thin the chip to an intermediate thickness.

[0059] Specifically, in step S100, the chip is first adhered to a glass substrate of suitable size using wax. Then, a chemical mechanical polishing machine is used with polishing slurry to thin the chip from 350 μm to an intermediate thickness of 100 μm under appropriate pressure and polishing disc speed. Measurements show that the thickness uniformity at this stage is ±5 μm. Preferably, the chip can also be thinned to an intermediate thickness of 80 to 120 μm as needed.

[0060] The purpose of step S100 is to remove most of the material and obtain a relatively flat surface without macroscopic damage, in preparation for subsequent ultra-precision flying cut processing.

[0061] Step S200: Using an ultra-precision single-point diamond milling machining center and a single-point diamond tool (a synthetic single-crystal diamond tool can be selected), perform ultra-precision flying cut on the back side of the chip processed in step S100 to cut it to the target thickness.

[0062] Specifically, during the ultra-precision flying cut operation in step S200, a tooling fixture is used to position the chip; a vacuum chuck is used to adsorb and fix the chip, so that it is fixed to the upper end of the chip support after being adsorbed during the thinning operation. With the assistance of the stop blocks on the outer ring of the chip support, the chip's position will be accurately and stably limited within the preset position under the above-mentioned limiting and fixing method, which can achieve better cutting results.

[0063] Preferably, the ultra-precision flying-cut thinning operation in step S200 can be performed in several steps, as follows:

[0064] First, a single-point diamond tool is used to rough cut the back of the chip. During the rough cutting operation, the process parameters of single-point diamond cutting are: spindle speed: 1300-1500 rpm, table feed rate: 15-18 mm / min, feed rate: 5-10 μm.

[0065] Then, a single-point diamond tool is used to perform a fine cutting operation on the back of the chip after the rough cutting operation. During the fine cutting operation, the process parameters of single-point diamond cutting are: spindle speed: 1300-1500rpm, table feed speed: 7-10mm / min, feed rate: 1-3μm.

[0066] This embodiment utilizes a vertical single-point diamond milling machining center for ultra-precision flying cut operations, equipped with a vacuum system connected to a vacuum chuck 3. Both the spindle (z-axis) and x-axis employ air bearing technology, achieving a minimum depth of cut of 0.2 μm. Cutting is achieved by controlling the spindle speed, table feed rate, table feed amount, and depth of cut. The cutting process is described below. Figure 4 The chip undergoes final back thinning by precisely controlling the cutting depth, feed rate, and spindle speed. This step needs to be performed in a temperature-controlled, clean, and vibration-resistant environment to minimize the effects of thermal deformation, contamination, and vibration.

[0067] After the roughing and fine cutting operations in step S200, the chip is finally thinned from 100μm to the final target thickness, which is related to the wavelength of the epitaxial film.

[0068] We inspected the chip after completing step S200: Using a z-axis microscope thickness gauge, we measured the thickness uniformity at eight points on the chip, with the thickness tests conducted at the four corners and perimeters, 1 mm from the edge. The maximum thickness deviation was less than 2 μm, and the minimum deviation was 0.5 μm. Using a white light interferometer, the surface roughness Ra value was measured to be 6 nm. Quantum efficiency: The measured quantum efficiency of the chip was 80%, a 30% improvement compared to a chip with the same thickness achieved through conventional thinning (quantum efficiency of 50%).

[0069] Specifically, such as Figure 13 The image shows a comparison of the thickness uniformity of a chip before and after single-point diamond cutting (i.e., a comparison of the thickness uniformity of a chip after fine polishing and thinning to the intermediate thickness and the thickness uniformity of a chip after single-point diamond cutting to the target thickness). Figure 13 This image shows the thickness uniformity of a chip cut to the target thickness using a single-point diamond tool. Although the target thickness requirement is ±2μm, from... Figure 12 It can be seen that this process can control the chip thickness uniformity within ±1μm. Among the 84 batches of delivered chips, the proportion with uniformity performance of ±1μm was 82%, which shows that the process has practical significance.

[0070] For chips that have passed the inspection, further cleaning and etching operations can be performed; specifically, after cutting, the chips are cleaned with dewaxing solution and then micro-etched. The purpose of micro-etching is to remove cutting marks.

[0071] Single Point Diamond Turning (SPDT) is a machining technology that uses natural single-point diamond tools to cut workpieces on ultra-high precision machine tools. Currently, by precisely controlling the machine tool and machining environment, SPDT technology can directly produce products that meet optical quality requirements, achieving nanoscale surface roughness. It exhibits excellent performance in machining materials such as infrared crystals, non-ferrous metals, and some laser crystals.

[0072] This embodiment creatively combines "high-efficiency polishing for removal" with "high-precision, low-damage single-point diamond cutting technology." Polishing provides a qualified "blank" for ultra-precision cutting, avoiding chip cracking and tool damage caused by directly cutting thick chips, and shortening processing time; while single-point diamond cutting achieves the ultimate precision that polishing cannot reach. The two complement each other, ensuring efficiency while achieving processing quality that cannot be achieved by a single process.

[0073] In this embodiment, in step S200, a tooling fixture is used to clamp the chip; a vacuum chuck 3 is used to adsorb and fix the chip 5, so that it is fixed in the chip clamping area after being adsorbed during the thinning operation. With the assistance of the stop block 41, under the above-mentioned limiting and fixing method, the position of the chip will be accurately and stably limited to the clamping area specified on the upper end of the chip support, which can achieve better cutting effect. Compared with the traditional wax bonding and fixing method, the heating, melting and cooling of wax during the wax bonding process has already caused a large thickness deviation in thickness uniformity; secondly, the wax bonding process tests the operator's skill level, and different operators can have very different operations for the same process; finally, the combination of vacuum adsorption and stop block makes it less likely for the chip to shift or tilt during the thinning operation, which is more conducive to achieving uniform chip cutting and reducing the thickness difference of the chip after the thinning operation.

[0074] like Figures 5 to 8 The diagram shown is a structural schematic of a tooling fixture in the invention (excluding the stop block assembly). Figure 9 This is a schematic diagram of the bottom structure of the tooling fixture; Figure 10 This is a schematic diagram of the block's structure; Figure 11 This is a perspective view of the tooling fixture in this invention (including three stops).

[0075] The tooling fixture 4 includes a base plate 40, a chip support for supporting the chip, and a stop assembly for limiting chip displacement; the chip support is fixed to the upper end of the base plate 40; the stop assembly is disposed on the outer ring of the chip support and is used to limit the horizontal displacement of the chip at the upper end of the chip support during the cutting operation.

[0076] In this embodiment, the stop assembly includes three stops 41 spaced apart along the outer ring of the chip support. The lower end of the stop 41 is fixedly or detachably connected to the upper end of the base plate. The height of the stop 41 is higher than the height of the chip support but lower than the total height of the chip after clamping.

[0077] like Figures 5-8 As shown, in this embodiment, two of the three stops 41 are symmetrically distributed around the outer ring of the chip support, while the remaining stop is located between the two symmetrically distributed stops. These three points restrict the chip's displacement during the cutting operation, thereby improving the final cutting effect.

[0078] like Figures 5 to 8 As shown, the chip support has a mesh groove 49 on its upper end, which is connected to the vacuum chuck 3, and the upper port of the groove 49 leads to the upper end face of the chip support. During the ultra-precision flying cut operation, the chip is located on the upper end of the chip support, blocking the upper port of the groove 49. The vacuum chuck 3 draws a vacuum to create a negative pressure under the chip, which is then vacuum-adsorbed and fixed to the upper end of the chip support.

[0079] In this embodiment, the groove 49 presents a grid-like groove structure, and its inner cavity is a continuous groove space. Specifically, as shown... Figures 5 to 8 As shown, in this embodiment, the chip support includes several spaced square blocks 46 and annular protrusions 45; all square blocks 46 are arranged in an array, and all the arrayed square blocks 46 are located in the inner circle of the annular protrusions 45; the grooves 49 are the spacing slots between adjacent square blocks 46 and between square blocks 46 and annular protrusions 45, forming a grid-like groove structure. The upper end face of the square blocks 46 and the upper end face of the annular protrusions 45 are at the same height. When the chip is placed on the upper end of the chip support, it will completely cover the upper port of the groove 49. Thus, after the vacuum chuck 3 draws a vacuum, a negative pressure will be formed in the groove 49 below the chip, thereby causing the chip to be adsorbed on the upper end of the chip support and located between the three stops 41 (specifically, during the cutting operation, the chip is placed in the chip clamping area; after the chip is placed in the chip clamping area, it is located between the three stops 41 on the upper end of the chip support, such as...). Figure 11 (As shown).

[0080] In this embodiment, the trenches 49 are distributed in a grid pattern, and the crisscross structure of the grid trenches forms an interconnected channel network. Through the uniform flow guidance and negative pressure dispersion effect of the grid trenches, the adsorption force is applied evenly to the chip, which is conducive to the uniform and stable adsorption of the chip in the chip clamping area.

[0081] Specifically, such as Figure 6 As shown, the bottom of the groove 49 is provided with 6 vent holes 48; each vent hole 48 is arranged through the tooling thickness direction and the two ends of the vent hole are connected; the vacuum suction cup 3 is assembled at the lower end of the tooling fixture 4, and the groove 49 is connected to the airflow interface of the vacuum suction cup 3 through the 6 vent holes 48.

[0082] The lower end of the stop block 41 is fixedly or detachably connected to the upper end of the base plate 40; the height of the stop block 41 is higher than the height of the chip support, but lower than the total height after the chip is clamped (i.e., when the chip is placed on the upper end of the chip support, the height of the stop block 41 is lower than the height of the upper surface of the chip); at the same time, on the outer ring of the chip support, between two adjacent stop blocks 41, the upper end of the base plate 40 is also fixedly provided with three step blocks (specifically, the first step block 42, the second step block 43, and the third step block 44), the upper surface of the step block is a step surface, and the height of the step surface is lower than the height of the chip support (specifically, such as...). Figure 5 As shown, the step surfaces of the three step blocks are at the same height, and all are lower than the upper surface of the annular protrusion 45.

[0083] like Figures 7-8 As shown, in this embodiment, the chip support, base plate 40, and three stepped blocks are an integral, non-separable component. Figure 5 and Figure 6 As shown, in this integrated component, three stepped blocks are set on the outer ring of the annular protrusion 45, which are rigid support transition structures between the annular protrusion 45 and the base plate 40. This not only realizes the spatial connection between the side end of the annular protrusion 45 and the upper end of the base plate 40, but also ensures the stability of load transfer and structural connection between the two through its own rigid structural characteristics.

[0084] The space between two adjacent step blocks is a stop block mounting area 61, and the stop blocks are installed within this stop block mounting area 61; the upper end of the base plate 40 is provided with screw mounting holes 62, which are located within the stop block mounting area 61; Figure 10 As shown, the L-shaped stop 41 is provided with a mounting through hole. During installation, the screw passes through the mounting through hole from top to bottom and is threaded into the screw mounting hole 62, thereby fixing the stop 41 to the base plate 40.

[0085] This fixture is a dedicated positioning fixture for chip back-end thinning processes. It is primarily used for precise chip positioning. After positioning, a negative pressure is applied beneath the chip to create an adsorption and clamping effect, ensuring the chip remains in a fixed position and its surface is parallel to the single-point diamond tool during processing. The fixture is made of brass, offering advantages such as wear resistance, rust prevention, and resistance to scratching precision workpieces. The overall design is modular, consisting mainly of a main base and several stops. The main body is the core load-bearing structure and positioning reference of the entire fixture, and is a three-tiered base, such as... Figure 5 As shown, its structure, from top to bottom and from inside to outside, can be divided into the following key parts: Chip support area: This area directly supports the chip, ensuring that after the chip is placed, its upper surface is at a precise and known height position, thereby ensuring that subsequent cutting can be performed with the correct machining amount to achieve the precise back thinning target. Three stepped blocks are set around the outer ring of the chip support. The bottom plate is located at the lowest point of the overall structure of the main base. The stop block is fixed to the side of the stepped block with screws, thereby realizing the installation of the stop block. In the tooling fixture structure of this embodiment, the chip support, stepped blocks, and stop blocks have different heights, and the positions of the chip support, stepped blocks, and stop blocks can be quickly determined by the height difference.

[0086] Vacuum Adsorption Fixing: Ventilation holes with a diameter of 1mm are designed in the grooves between the square blocks to connect to an external vacuum system. After the chip is placed in the chip clamping area, the vacuum is activated, and the negative pressure through these small holes evenly and stably adsorbs the chip into the chip clamping area. This is a non-contact, stress-free clamping method that effectively avoids deformation or damage caused by mechanical clamping. Stops: Stops are provided on the outer ring of the chip support. Although vacuum adsorption ensures chip adhesion, slight displacement may still occur during processing. Adding stops solves this problem. Furthermore, since the spindle rotates counterclockwise, the stops also help to disperse cutting forces. The stops contact the chip edge from the side, eliminating these residual degrees of freedom and completely locking the chip in the preset position. The height of the stops is less than the total height of the chip after clamping, specifically 0.1mm lower. During processing, the stable chip position facilitates more uniform thickness through cutting operations, reducing the thickness difference of the chip after cutting.

[0087] In addition, in this embodiment, a bottom groove 47 is provided at the bottom of the base plate 40, and the bottom groove 47 communicates with the lower opening of the vent hole 48, such as... Figure 9 As shown, the bottom groove 47 connects the vacuum suction cup and the vent 48, forming a large-diameter vent, which is beneficial for achieving rapid response and stable maintenance of vacuum adsorption. The groove provides a small "gas storage" space (albeit under negative pressure), which helps to quickly establish and release the vacuum, improving loading and unloading efficiency. When there are slight fluctuations in the vacuum system, this cavity plays a certain buffering role, maintaining the instantaneous stability of the adsorption force.

Claims

1. A high-uniformity, low-damage chip thinning method based on single-point diamond cutting, characterized in that, Includes the following steps: Step S100: Perform fine polishing on the back of the chip to thin the chip to an intermediate thickness; the intermediate thickness is 80 to 120 μm. Step S200: Use a single-point diamond tool to perform ultra-precision flying cut on the back side of the chip processed in step S100, cutting it to the target thickness.

2. The high-uniformity, low-damage chip thinning method based on single-point diamond cutting according to claim 1, characterized in that: During the ultra-precision flying cut operation in step S200, the chip is positioned by the tooling fixture (4); The tooling fixture (4) includes a base plate (40), a chip support for supporting the chip, and a stop assembly for limiting chip displacement; the chip support is fixed to the upper end of the base plate (40); the stop assembly is disposed on the outer ring of the chip support; The chip support is provided with a groove (49) at the upper end; the groove (49) presents a mesh-like groove structure and is connected to the vacuum suction cup (3); During the ultra-precision flying cut operation, the chip is placed on the upper end of the chip support, blocking the upper port of the groove (49); a vacuum is drawn by the vacuum chuck (3) to create a negative pressure under the chip, and the chip is then vacuum-adsorbed and fixed to the upper end of the chip support.

3. The method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to claim 2, characterized in that: The chip support includes several spaced square blocks (46) and annular protrusions (45); all square blocks (46) are located in the inner circle of the annular protrusions (45); the grooves (49) are the spaced grooves between adjacent square blocks (46) and between square blocks (46) and annular protrusions (45), presenting an overall grid-like groove structure. The bottom of the groove (49) is provided with several through-holes (48); the vacuum suction cup (3) is assembled at the lower end of the tooling fixture (4), and the groove (49) is connected to the airflow interface of the vacuum suction cup (3) through the vents (48).

4. The method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to claim 3, characterized in that: The stop assembly includes several stops (41) spaced apart along the outer ring of the chip support; the lower end of the stop (41) is fixedly or detachably connected to the upper end of the base plate; the height of the stop (41) is higher than the height of the chip support and lower than the total height of the chip after clamping.

5. The method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to claim 4, characterized in that: A step block is also provided between two adjacent blocks (41) on the outer ring of the chip support. The upper surface of the step block is a step surface, and the height of the step surface is lower than the height of the chip support.

6. A method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to any one of claims 2-5, characterized in that: A bottom groove (47) is provided at the bottom of the base plate (40); the bottom groove (47) connects the vacuum suction cup and the vent hole (48).

7. A high-uniformity, low-damage chip thinning method based on single-point diamond cutting according to any one of claims 1-5, characterized in that, In step S200: First, a single-point diamond tool is used to perform a rough cut on the back of the chip. During the rough cut, the process parameters for single-point diamond cutting are: spindle speed: 1300-1500 rpm, table feed rate: 15-18 mm / min, and feed rate: 5-10 μm. Then, a single-point diamond tool is used to perform a fine cutting operation on the back of the chip after the rough cutting operation. During the fine cutting operation, the process parameters of single-point diamond cutting are: spindle speed: 1300-1500rpm, table feed speed: 7-10mm / min, feed rate: 1-3μm.

8. A method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to any one of claims 1-5, characterized in that: After completing step S200, the thickness uniformity of the chip cut to the target thickness is less than 2μm.

9. A method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to any one of claims 1-5, characterized in that: After completing step S200, the surface roughness Ra value of the chip cut to the target thickness is less than 10 nm.

10. A method for high-uniformity, low-damage chip thinning based on single-point diamond cutting according to any one of claims 1-5, characterized in that: In step S100, the back of the chip is finely polished using chemical mechanical polishing; step S200 is performed in a constant temperature, clean, and shock-resistant environment.

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