Wafer edge trimming device

Abstract

The application provides a wafer trimming device, belonging to the technical field of semiconductors, comprising a working chamber, at least two rotating tables, at least two trimming cutters and a driving shaft. The rotating tables are located in the working chamber and are respectively used for carrying a wafer. The trimming cutters are located outside one rotating table and are used for trimming the corresponding wafer. The driving shaft is connected with all the trimming cutters to drive the trimming cutters to move synchronously along a first direction and make all the trimming cutters synchronously approach or move away from the corresponding wafer along the first direction. The first direction is parallel to the surface of the rotating table. The wafer trimming device can trim at least two wafers simultaneously, and all the trimming cutters can synchronously approach or move away from the corresponding wafer, so that the trimming widths of the two wafers are ensured to be the same, and the problem that etchant flows into the bonding surface through the step between the edges of the two wafers during the subsequent back thinning process, thereby causing the metal contact pad to be damaged and cracks to occur on the bonding surface, is avoided.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and more specifically to a wafer trimming device. Background Technology

[0002] Backside thinning is a crucial process in backside illuminated (BSI) technology. In BSI, backside thinning is performed after bonding the pixel wafer and logic wafer. Specifically, it involves using a wet etching process to etch the back side of the pixel wafer's substrate, thereby thinning the substrate to the required thickness. However, because the film layer at the wafer edges is prone to bevel peeling, bubbles can form at the wafer edges. Figure 1 The dashed circle indicates blistering at the wafer edge. During wet etching, the etchant flows into the bonding surface through the blistering location, laterally etching the metal contact pads on the bonding surface. This damages the metal contact pads, affecting device performance. Defects such as cracks are also prone to occur on the bonding surface, affecting the bonding effect.

[0003] To address this issue, before bonding the pixel wafer and logic wafer, a wafer trimming device is typically used to trim the edges of both wafers. This involves using a trimming tool to cut away a portion of the edges of the pixel and logic wafers at a specific depth and width before bonding them. However, current wafer trimming devices can only trim one wafer at a time, meaning the pixel and logic wafers are trimmed separately. The trimming widths of the pixel and logic wafers are difficult to guarantee are identical (the difference can even reach 100μm). This results in a step at the edge after bonding, allowing etchant to flow into the bonding surface through this step, damaging the metal contacts and causing cracks in the bonding surface. Utility Model Content

[0004] In view of this, the present application aims to provide a wafer trimming device to solve the problem that existing wafer trimming devices cannot guarantee that the trimming width of the pixel wafer edge is the same as that of the logic wafer.

[0005] This application provides a wafer trimming apparatus, comprising: Working chamber; At least two rotary stages are located within the working chamber, each used to hold a wafer; At least two trimming tools, each located outside one of the rotating stages, are used to trim the corresponding wafer; and, A drive shaft is connected to all the trimming tools to drive all the trimming tools to move synchronously along a first direction, and to make all the trimming tools move synchronously closer to or further away from the corresponding wafer along the first direction, which is parallel to the surface of the rotary table.

[0006] In some embodiments, the drive shaft is also used to drive all the trimming tools to move synchronously along a second direction, and to make all the trimming tools move synchronously closer to or further away from the corresponding wafer along the second direction, the second direction being perpendicular to the surface of the rotary table.

[0007] In some embodiments, each of the trimming tools is connected to the drive shaft via a connecting rod extending along the first direction and the connecting rod extending along a second direction perpendicular to the surface of the rotary table.

[0008] In some embodiments, the length of the connecting rod along the second direction is different.

[0009] In some embodiments, at least one of the connecting rods may extend or retract along the second direction.

[0010] In some embodiments, it also includes: At least two distance measuring units, each located on a corresponding rotary table or a corresponding trimming tool, are used to measure the distance between the trimming tool and the edge of the corresponding wafer in a first direction.

[0011] In some embodiments, it also includes: At least two width measurement units, each located outside the corresponding rotary table, are used to measure the trimming width of the corresponding wafer in real time.

[0012] In some embodiments, the wafer on the rotary table is a pixel wafer or a logic wafer.

[0013] In some embodiments, the trimming width of the pixel wafer is the same as the trimming width of the logic wafer; and / or, the trimming depth of the pixel wafer is the same as or different from the trimming depth of the logic wafer.

[0014] In some embodiments, the trimming width of both the pixel wafer and the logic wafer is 500μm to 2000μm; and / or, the trimming depth of both the pixel wafer and the logic wafer is 50μm to 300μm.

[0015] This application provides a wafer trimming apparatus, including a working chamber, at least two rotary stages, at least two trimming cutters, and a drive shaft. The rotary stages are located within the working chamber and each carries a wafer. The trimming cutters are located outside one of the rotary stages and are used to trim the corresponding wafer. The drive shaft connects all the trimming cutters to drive them to move synchronously along a first direction, causing them to move synchronously closer to or further away from the corresponding wafer along the first direction, which is parallel to the surface of the rotary stage. An unexpected benefit of this application is that the wafer trimming apparatus can trim all wafers simultaneously, and since all the trimming cutters are driven by the same drive shaft, and all the cutters can move synchronously closer to or further away from the corresponding wafer, it ensures that at least two wafers have the same trimming width. This avoids the problem of etchant flowing into the bonding surface through the steps at the edges of the two wafers during the back-side thinning process after bonding, which could damage the metal contact pads and cause cracks in the bonding surface. This improves bonding quality and device performance. Attached Figure Description

[0016] Figure 1 A schematic diagram of bubbling at the edge of a wafer.

[0017] Figure 2 This is a schematic diagram of the structure of a wafer trimming device provided in an embodiment of this application.

[0018] Figure 3 A flowchart illustrating the operation of a wafer trimming apparatus provided in an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of the structure of a pixel wafer provided in an embodiment of this application.

[0020] Figure 5 This is a schematic diagram of the structure of a trimmed pixel wafer provided in one embodiment of this application.

[0021] Figure 6 This is a schematic diagram of the structure of a logic wafer provided in an embodiment of this application.

[0022] Figure 7 This is a schematic diagram of the structure of a trimmed logic wafer provided in one embodiment of this application.

[0023] Figure 8 This is a schematic diagram of the bonding of a trimmed pixel wafer and a trimmed logic wafer according to an embodiment of this application.

[0024] The attached figures are labeled as follows: 10-First workpiece stage; 11-Second workpiece stage; 20-First rotary stage; 21-Second rotary stage; 30-First trimming tool; 31-Second trimming tool; 40-Drive shaft; 50-Drive assembly; 60-First connecting rod; 61-Second connecting rod; 70-First distance measurement unit; 71-Second distance measurement unit; 80-First width measurement unit; 81-Second width measurement unit; x-First direction; y-Second direction; 100-First substrate; 101-First epitaxial layer; 200-First dielectric layer; 300-First hybrid bonding layer; 301-First metal contact pad; w1-Trimming width of pixel wafer; h1-Trimming depth of pixel wafer; 110-Second substrate; 111-Second epitaxial layer; 210-Second dielectric layer; 310-Second hybrid bonding layer; 311-Second metal contact pad; w2-Trimming width of logic wafer; h2-Trimming depth of logic wafer. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] Figure 2 This is a schematic diagram of the structure of a wafer trimming apparatus provided in one embodiment of this application. Figure 2 As shown, the wafer trimming apparatus includes a working chamber, at least two rotary stages, at least two trimming blades, and a drive shaft 40. Each rotary stage is located within the working chamber and supports one wafer. Each trimming blade is located outside one rotary stage and is used to trim the corresponding wafer. The drive shaft 40 connects all trimming blades, driving them to move synchronously along a first direction x, and causing them to move synchronously closer to or further away from the corresponding wafer along the first direction x, which is parallel to the surface of the rotary stage. An unexpected benefit of this application is that the wafer trimming apparatus can trim all wafers simultaneously, and since the trimming blades are driven by the same drive shaft 40, all trimming blades can synchronously approach or move away from the corresponding wafer, ensuring that the trimming width of the wafers is the same. This avoids the problem of etchant flowing into the bonding surface through the steps at the edges of the two wafers during the subsequent back-side thinning process after bonding, which could damage the metal contact pads and cause cracks in the bonding surface, thus improving bonding quality and device performance.

[0027] Next, for ease of description, we will take the wafer trimming device, which includes two rotating stages and two trimming cutters, as an example. The two rotating stages will be referred to as the first rotating stage 20 and the second rotating stage 21, and the two trimming cutters will be referred to as the first trimming cutter 30 and the second trimming cutter 31. The two wafers will be the pixel wafer and the logic wafer, respectively.

[0028] Please continue reading. Figure 2 A first rotary stage 20 and a second rotary stage 21 are respectively disposed on a first workpiece stage 10 and a second workpiece stage 11 within the working chamber. The first workpiece stage 10 can drive the first rotary stage 20 to move horizontally, and the second workpiece stage 11 can drive the second rotary stage 21 to move horizontally. One of the first rotary stage 20 and the second rotary stage 21 is used to carry the pixel wafer and drive the pixel wafer to rotate, while the other is used to carry the logic wafer and drive the logic wafer to rotate. The first rotary stage 20 and the second rotary stage 21 may have multiple vacuum adsorption holes, through which the pixel wafer or the logic wafer is adsorbed and fixed. The following explanation will use the example of the first rotary stage 20 and the second rotary stage 21 carrying a pixel wafer and a logic wafer, respectively.

[0029] In some embodiments, the first rotary stage 20 and the second rotary stage 21 are not limited to carrying pixel wafers and logic wafers, but can also be used to carry other two types of wafers, which will not be described in detail here.

[0030] Furthermore, the first trimming tool 30 is located outside the first rotary stage 20 and is used to trim the pixel wafer on the first rotary stage 20; the second trimming tool 31 is located outside the second rotary stage 21 and is used to trim the logic wafer on the second rotary stage 21. The first trimming tool 30 and the second trimming tool 31 can be a grinding wheel, with the rotation axis of the grinding wheel perpendicular to the wafer surface. During the trimming process, the first trimming cutter 30 gradually moves along the first direction x until it comes into contact with the edge of the pixel wafer, and continues to move along the first direction x to trim the pixel wafer; at the same time, the second trimming cutter 31 gradually moves along the first direction x until it comes into contact with the edge of the logic wafer, and continues to move along the first direction x to trim the logic wafer; during trimming, both the first trimming cutter 30 and the second trimming cutter 31 rotate around their rotation axis, the first rotary table 20 drives the pixel wafer to rotate, and the second rotary table 21 drives the logic wafer to rotate. Through the squeezing and friction between the first trimming cutter 30 and the pixel wafer and between the second trimming cutter 31 and the logic wafer, the trimming of the pixel wafer and the logic wafer is achieved.

[0031] Please continue reading. Figure 2Each trimming tool is connected to the drive shaft 40 via a connecting rod. Specifically, the first trimming tool 30 and the second trimming tool 31 are both connected to the drive shaft 40 via a connecting rod. More specifically, the first trimming tool 30 is connected to the drive shaft 40 via a first connecting rod 60, and the second trimming tool 31 is connected to the drive shaft 40 via a second connecting rod 61. The drive shaft 40 is located above the first rotary table 20 and the second rotary table 21, and extends along a first direction x. The first connecting rod 60 and the second connecting rod 61 extend approximately along a second direction y, which is perpendicular to the surface of the rotary table (i.e., the second direction y is perpendicular to the first direction x). In this way, the drive shaft 40 can drive the first trimming tool 30 and the second trimming tool 31 to move synchronously via the first connecting rod 60 and the second connecting rod 61. For example, the drive shaft 40 can drive the first trimming tool 30 and the second trimming tool 31 to move synchronously along the first direction x, so that the first trimming tool 30 and the second trimming tool 31 move synchronously closer to or further away from the corresponding wafers along the first direction x (when the first trimming tool 30 moves closer to the pixel wafer in the first direction x, the second trimming tool 31 also moves synchronously closer to the logic wafer in the first direction x; when the first trimming tool 30 moves away from the pixel wafer in the first direction x, the second trimming tool 31 also moves synchronously away from the logic wafer in the first direction x). Therefore, By associating the initial relative positions of the first trimming tool 30 and the first rotary table 20 in the first direction x with the initial relative positions of the second trimming tool 31 and the second rotary table 21 in the first direction x, it can be ensured that when the drive shaft 40 drives the first trimming tool 30 and the second trimming tool 31 to move synchronously along the first direction x, the relative distance between the first trimming tool 30 and the pixel wafer in the first direction x and the relative distance between the second trimming tool 31 and the logic wafer in the first direction x remain consistent. This ensures that after the first trimming tool 30 trims the pixel wafer and after the second trimming tool 31 trims the logic wafer, the trimming width of the pixel wafer and the logic wafer is the same.

[0032] In some embodiments, the drive shaft 40 can drive the first trimming tool 30 and the second trimming tool 31 to move synchronously along the second direction y, so that the first trimming tool 30 and the second trimming tool 31 move synchronously closer to or further away from the corresponding wafers along the second direction y (when the first trimming tool 30 moves closer to the pixel wafer in the second direction y, the second trimming tool 31 also moves synchronously closer to the logic wafer in the second direction y; when the first trimming tool 30 moves away from the pixel wafer in the second direction y, the second trimming tool 31 also moves synchronously away from the logic wafer in the second direction y). Therefore, as long as the first trimming tool 30 and the first rotary table 20 move synchronously along the second direction y... The initial relative position of the first trimming tool 30 and the second trimming tool 31 are associated with the initial relative position of the second rotary table 21 in the second direction y. This ensures that when the drive shaft 40 drives the first trimming tool 30 and the second trimming tool 31 to move synchronously in the second direction y, the relative distance between the first trimming tool 30 and the pixel wafer in the second direction y and the relative distance between the second trimming tool 31 and the logic wafer in the second direction y can be kept consistent. This ensures that after the first trimming tool 30 trims the pixel wafer and the second trimming tool 31 trims the logic wafer, the trimming depth of the pixel wafer and the logic wafer can be the same.

[0033] Of course, in some embodiments, the trimming depth of the pixel wafer and the logic wafer may be different, which does not affect the implementation of this application.

[0034] Furthermore, the drive shaft 40 can be connected to a drive assembly 50, which can specifically control the movement of the first trimming tool 30 and the second trimming tool 31. The drive assembly 50 can be a combination of structures such as a drive motor and a guide rail, which can control the drive shaft 40 to move along the first direction x and the second direction y. Since the drive assembly 50 is not the focus of this application, it will not be described in detail here.

[0035] In some embodiments, the lengths of the two connecting rods along the second direction y can be the same or different; that is, the length of the first connecting rod 60 along the second direction y and the length of the second connecting rod 61 along the second direction y can be the same or different. In this way, the trimming depths of the pixel wafer and the logic wafer can be the same or different. For example, if the trimming depth of the pixel wafer needs to be greater than that of the logic wafer by a predetermined value, the length of the first connecting rod 60 along the second direction y can be set to be greater than the length of the second connecting rod 61 along the second direction y by a predetermined value, which will not be elaborated further here.

[0036] In some embodiments, at least one connecting rod is telescopic along a second direction y, that is, the first connecting rod 60 and / or the second connecting rod 61 is telescopic along the second direction y, so that the length of the first connecting rod 60 and / or the second connecting rod 61 along the second direction y can be changed. This allows for adaptive adjustment of the trimming depth of the pixel wafer and the logic wafer, making the wafer trimming device more adaptable. The telescopic method of the first connecting rod 60 and / or the second connecting rod 61 along the second direction y can be manual or electric, depending on the specific structure of the first connecting rod 60 and / or the second connecting rod 61.

[0037] Please continue reading. Figure 1 The wafer trimming apparatus may further include at least two distance measurement units, each located on a corresponding rotary table or a corresponding trimming cutter, for measuring the distance between the trimming cutter and the edge of the corresponding wafer. In some embodiments, the wafer trimming apparatus includes two distance measurement units, namely a first distance measurement unit 70 and a second distance measurement unit 71. The first distance measurement unit 70 may be located on a first rotary table 20 or on a first trimming cutter 30, for measuring the distance between the first trimming cutter 30 and the pixel wafer. The second distance measurement unit 71 may be located on a second rotary table 21 or on a second trimming cutter 31, for measuring the distance between the second trimming cutter 31 and the logic wafer. By comparing the measurement results of the first distance measurement unit 70 and the second distance measurement unit 71, it can be determined whether the distance between the first trimming cutter 30 and the pixel wafer and the distance between the second trimming cutter 31 and the logic wafer are equal.

[0038] In some embodiments, the first distance measuring unit 70 and the second distance measuring unit 71 may be optical sensors such as laser rangefinders.

[0039] Furthermore, the wafer trimming apparatus may also include at least two width measurement units, each located outside a corresponding rotary stage, for real-time measurement of the trimming width of the corresponding wafer. In some embodiments, the wafer trimming apparatus includes two width measurement units, namely a first width measurement unit 80 and a second width measurement unit 81. The first width measurement unit 80 is located outside the first rotary stage 20 and is used to measure the trimming width of the pixel wafer in real-time. The second width measurement unit 81 is located outside the second rotary stage 21 and is used to measure the trimming width of the logic wafer in real-time. By comparing the measurement results of the first width measurement unit 80 and the second width measurement unit 81, it can be determined whether the trimming width of the pixel wafer and the trimming width of the logic wafer are the same.

[0040] In some embodiments, the first width measuring unit 80 and the second width measuring unit 81 may also be optical sensors such as laser rangefinders. The positions of the first width measuring unit 80 and the second width measuring unit 81 in the second direction y need to be aligned with the trimming positions of the pixel wafer and the logic wafer, respectively. Then, by measuring the distance between itself and the current edges of the pixel wafer and the logic wafer in real time, the trimming width of the pixel wafer and the logic wafer can be obtained.

[0041] Figure 3 This is a flowchart illustrating the operation of a wafer trimming apparatus provided in one embodiment of this application. Figure 3 As shown, the wafer trimming device operates as follows: The pixel wafer and the logic wafer are transferred to the working chamber. The pixel wafer is fixed on the first rotary stage 20, and the logic wafer is fixed on the second rotary stage 21. The first trimming tool 30 and the second trimming tool 31 are reset so that both the first trimming tool 30 and the second trimming tool 31 are in their initial positions. The first workpiece stage 10 and the second workpiece stage 11 are reset so that both the first rotary stage 20 and the second rotary stage 21 are in their initial positions. Thus, the relative distance between the first trimming tool 30 and the pixel wafer in the first direction x is the same as the relative distance between the second trimming tool 31 and the logic wafer in the first direction x.

[0042] Subsequently, the first distance measurement unit 70 begins to measure the distance between the first trimming cutter 30 and the edge of the pixel wafer in the first direction x, and the second distance measurement unit 71 begins to measure the distance between the second trimming cutter 31 and the logic wafer in the first direction x. The first distance measurement unit 70 and the second distance measurement unit 71 send the detection results to the control system of the wafer trimming device.

[0043] The control system can compare the detection results of the first distance measuring unit 70 and the second distance measuring unit 71, and determine whether the detection results of the first distance measuring unit 70 and the second distance measuring unit 71 are the same (specifically, by determining whether the difference between the detection results of the first distance measuring unit 70 and the second distance measuring unit 71 meets the requirements). If not, the first workpiece stage 10 and the second workpiece stage 11 can be used to fine-tune the positions of the first rotary stage 20 and the second rotary stage 21 until the detection results of the first distance measuring unit 70 and the second distance measuring unit 71 are the same.

[0044] Next, the control system controls the first rotary table 20 and the second rotary table 21 to start rotating, and controls the drive assembly 50 to operate. The drive shaft 40 drives the first trimming cutter 30 and the second trimming cutter 31 to move synchronously, and simultaneously controls the first trimming cutter 30 and the second trimming cutter 31 to start rotating, simultaneously trimming the pixel wafer and the logic wafer. During the trimming process, the drive assembly 50 needs to control the first trimming cutter 30 and the second trimming cutter 31 to move along the first direction x via the drive shaft 40 until the trimming width of the pixel wafer and the logic wafer meets the requirements.

[0045] After trimming begins, the first width measurement unit 80 measures the trimming width of the pixel wafer in real time, and the second width measurement unit 81 measures the trimming width of the logic wafer in real time. The first width measurement unit 80 and the second width measurement unit 81 send the detection results to the control system in real time. The control system can compare the detection results of the first width measurement unit 80 and the second width measurement unit 81, and determine whether the detection results of the first width measurement unit 80 and the second width measurement unit 81 are the same (specifically, by determining whether the difference between the detection results of the first width measurement unit 80 and the second width measurement unit 81 meets the requirements). If not, the positions of the first rotating stage 20 and the second rotating stage 21 can be finely adjusted through the first workpiece stage 10 and the second workpiece stage 11 until the detection results of the first width measurement unit 80 and the second width measurement unit 81 are the same.

[0046] Once the trimming width of the pixel wafer and logic wafer reaches the required value, the trimming is completed, and the trimmed pixel wafer and logic wafer are transferred out of the working chamber.

[0047] Figure 4 This is a schematic diagram of the structure of a pixel wafer provided in one embodiment of this application. Figure 4 As shown, the pixel wafer includes a first substrate 100, a first epitaxial layer 101, a first dielectric layer 200, and a first hybrid bonding layer 300, which are stacked sequentially from bottom to top. Various device structures, such as doped regions and gate structures, can be formed in and / or on the first epitaxial layer 101; a metal interconnect structure can be formed in the first dielectric layer 200, which electrically connects the device structures in and / or on the first epitaxial layer 101; a first metal contact pad 301 is formed in the first hybrid bonding layer 300, which is electrically connected to the metal interconnect structure in the first dielectric layer 200.

[0048] Figure 5 This is a schematic diagram of the structure of a trimmed pixel wafer provided in one embodiment of this application. Figure 5As shown, after the pixel wafer is trimmed, a portion of the edge of the pixel wafer is removed. The width of the removed portion of the pixel wafer edge is the trimming width w1, which can be 500μm to 2000μm. The depth of the removed portion of the pixel wafer edge is the trimming depth h1, which can be 50μm to 300μm.

[0049] It should be noted that the edge of the pixel wafer is not completely removed; that is, the trimming depth h1 of the pixel wafer is actually less than the thickness of the pixel wafer. Preferably, after trimming, the edge of the pixel wafer can expose the internal region of the first substrate 100. In other words, when trimming the pixel wafer, a portion of the thickness of the first hybrid bonding layer 300, the first dielectric layer 200, and the first substrate 100 at the edge of the pixel wafer can be removed.

[0050] Figure 6 This is a schematic diagram of the structure of a logic wafer provided in one embodiment of this application. Figure 6 As shown, the logic wafer includes a second substrate 110, a second epitaxial layer 111, a second dielectric layer 210, and a second hybrid bonding layer 310, which are stacked sequentially from bottom to top. Various device structures, such as doped regions and gate structures, can be formed within and / or on the second epitaxial layer 111. Metal interconnect structures can be formed within the second dielectric layer 210, electrically connecting the device structures within and / or on the second epitaxial layer 111. A second metal contact pad 311 is formed within the second hybrid bonding layer 310, electrically connecting the metal interconnect structure within the second dielectric layer 210.

[0051] Figure 7 This is a schematic diagram of the structure of a trimmed logic wafer provided in one embodiment of this application. Figure 7 As shown, after the logic wafer is trimmed, a portion of the edge of the logic wafer is removed. The width of the removed portion of the logic wafer edge is the trimming width w2, which can be 500μm to 2000μm. The depth of the removed portion of the logic wafer edge is the trimming depth h2, which can be 50μm to 300μm.

[0052] It should be noted that the edge of the logic wafer is not completely removed; that is, the trimming depth h2 of the logic wafer is actually less than the thickness of the logic wafer. Preferably, after trimming, the edge of the logic wafer can expose the internal region of the second substrate 110. In other words, when trimming the logic wafer, a portion of the thickness of the second hybrid bonding layer 310, the second dielectric layer 210, and the second substrate 110 at the edge of the logic wafer can be removed.

[0053] It should be noted that this application can ensure that the trimming width w1 of the pixel wafer and the trimming width w2 of the logic wafer are the same, but the trimming depth h1 of the pixel wafer and the trimming depth h2 of the logic wafer can be the same or different.

[0054] Figure 8 This is a schematic diagram illustrating the bonding of a trimmed pixel wafer and a trimmed logic wafer according to an embodiment of this application. Figure 8 As shown, the first hybrid bonding layer 300 of the pixel wafer and the second hybrid bonding layer 310 of the logic wafer are bonded together, and the corresponding first metal contact pad 301 and second metal contact pad 311 are also bonded together. Under low-temperature annealing, the edge-trimmed pixel wafer and the edge-trimmed logic wafer can be bonded together by utilizing the bonding force between the dielectrics. It can be understood that since both the pixel wafer and the logic wafer are trimmed before bonding, the edge areas prone to bubbling on the pixel wafer and logic wafer can be removed, avoiding the adverse effects of edge bubbling on bonding and improving the bonding effect between the pixel wafer and the logic wafer. Simultaneously, from... Figure 8 As can be seen, since the trimming width w1 of the pixel wafer is the same as the trimming width w2 of the logic wafer, the edges of the pixel wafer and the logic wafer can be aligned, and there are no steps at the edge of the bonding surface. When performing the back-side thinning process on the pixel wafer, the etchant will not flow into the bonding surface through the steps at the edge of the bonding surface, thus preventing damage to the first metal contact pad 301 and the second metal contact pad 311 and cracks in the bonding surface, thereby improving the bonding quality and device performance.

[0055] It should be noted that when bonding pixel wafers and logic wafers, the pixel wafers and logic wafers that are being trimmed simultaneously are bonded together, thereby ensuring that there are no steps at the edges of the pixel wafers and logic wafers after bonding.

[0056] Table 1 shows a comparison of the degree of lateral wear on the first metal contact pad 301 and the second metal contact pad 311 when trimming the pixel wafer separately using existing wafer trimming equipment (separate trimming) and when simultaneously trimming the pixel wafer and logic wafer using the wafer trimming equipment of this application. As can be seen from Table 1, when trimming the pixel wafer separately using existing wafer trimming equipment, after bonding the pixel wafer and logic wafer and performing a back-side thinning process on the pixel wafer, the lateral wear on the first metal contact pad 301 and the second metal contact pad 311 is quite severe. However, when simultaneously trimming the pixel wafer and logic wafer using the wafer trimming equipment of this application, after bonding the pixel wafer and logic wafer and performing a back-side thinning process on the pixel wafer, the lateral wear on the first metal contact pad 301 and the second metal contact pad 311 is much less severe. Therefore, this application can significantly improve the damage caused to the first metal contact pad 301 and the second metal contact pad 311 by the etchant in the back-side thinning process.

[0057] Table 1: Comparison of damage to metal contact pads caused by individual trimming and simultaneous trimming. Table 2 shows a comparison of the degree of crack formation on the bonding surface when trimming the pixel wafer separately using existing wafer trimming equipment (separate trimming) and when simultaneously trimming the pixel wafer and logic wafer using the wafer trimming equipment of this application. As can be seen from Table 1, when trimming the pixel wafer separately using existing wafer trimming equipment, after bonding the pixel wafer and logic wafer and performing a back-side thinning process on the pixel wafer, multiple wide cracks appear on the bonding surface, indicating a severe cracking problem. However, when simultaneously trimming the pixel wafer and logic wafer using the wafer trimming equipment of this application, no cracks appear on the bonding surface. Therefore, this application can significantly improve the problem of crack formation on the bonding surface after the back-side thinning process.

[0058] Table 2: Comparison of the degree of crack formation on the bonding surface between individual trimming and simultaneous trimming. In summary, this embodiment provides a wafer trimming apparatus, including a working chamber, at least two rotary stages, at least two trimming cutters, and a drive shaft 40. The rotary stages are located within the working chamber and each carries a wafer. Each trimming cutter is located outside a rotary stage and is used to trim the corresponding wafer. The drive shaft 40 connects all trimming cutters to drive them to move synchronously along a first direction x, and to move them synchronously closer to or further away from the corresponding wafer along the first direction x, which is parallel to the surface of the rotary stage. An unexpected effect of this application is that the wafer trimming apparatus can trim at least two wafers simultaneously, and all trimming cutters are driven by the same drive shaft 40. All trimming cutters can synchronously approach or move away from the corresponding wafer, thereby ensuring that the trimming width of at least two wafers is the same. This avoids the problem of etchant flowing into the bonding surface through the steps at the edges of the two wafers during the subsequent back-side thinning process after wafer bonding, which could damage the metal contact pads and cause cracks in the bonding surface. This improves bonding quality and device performance.

[0059] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0060] It should also be noted that although preferred embodiments have been disclosed above, these embodiments are not intended to limit this application. Any person skilled in the art can make many possible variations and modifications to the technical solutions of this application, or modify them into equivalent embodiments, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solutions of this application, shall still fall within the scope of protection of the technical solutions of this application.

[0061] It should also be understood that, unless otherwise specified or indicated, the terms “first,” “second,” “third,” etc., in the specification are used only to distinguish the various components, elements, and steps in the specification, and not to indicate the logical or sequential relationships between the various components, elements, and steps.

[0062] Furthermore, it should be recognized that the terminology described herein is used only to describe particular embodiments and is not intended to limit the scope of this application. It must be noted that the singular forms “a” and “an” used herein and in the appended claims include plural bases unless the context clearly indicates otherwise. For example, a reference to “a step” or “an apparatus” means a reference to one or more steps or apparatuses, and may include secondary steps and secondary apparatuses. All conjunctions used should be understood in the broadest sense. Also, the word “or” should be understood to have the definition of logical “or” rather than logical “exclusive OR”, unless the context clearly indicates otherwise. Furthermore, implementations of the methods and / or devices in the embodiments of this application may include performing selected tasks manually, automatically, or in combination.

Claims

1. A wafer trimming device, characterized in that, include: Working chamber; At least two rotary stages are located within the working chamber, each used to hold a wafer; At least two trimming tools, each of which is located outside one of the rotating stages, are used to trim the corresponding wafer; as well as, A drive shaft is connected to all the trimming tools to drive all the trimming tools to move synchronously along a first direction, and to make all the trimming tools move synchronously closer to or further away from the corresponding wafer along the first direction, which is parallel to the surface of the rotary table.

2. The wafer trimming apparatus according to claim 1, characterized in that, The drive shaft is also used to drive all the trimming tools to move synchronously along the second direction, and to make all the trimming tools move synchronously closer to or further away from the corresponding wafer along the second direction, which is perpendicular to the surface of the rotary table.

3. The wafer trimming apparatus according to claim 1, characterized in that, Each of the trimming tools is connected to the drive shaft via a connecting rod extending along a first direction and the connecting rod extending along a second direction perpendicular to the surface of the rotary table.

4. The wafer trimming apparatus according to claim 3, characterized in that, The length of the connecting rod varies along the second direction.

5. The wafer trimming apparatus according to claim 3, characterized in that, At least one of the connecting rods is telescopic in the second direction.

6. The wafer trimming apparatus according to claim 1, characterized in that, Also includes: At least two distance measuring units, each located on a corresponding rotary table or a corresponding trimming tool, are used to measure the distance between the trimming tool and the edge of the corresponding wafer in a first direction.

7. The wafer trimming apparatus according to claim 1, characterized in that, Also includes: At least two width measurement units, each located outside the corresponding rotary table, are used to measure the trimming width of the corresponding wafer in real time.

8. The wafer trimming apparatus according to any one of claims 1 to 7, characterized in that, The wafers on the rotating stage are pixel wafers or logic wafers.

9. The wafer trimming apparatus according to claim 8, characterized in that, The trimming width of the pixel wafer is the same as the trimming width of the logic wafer; and / or, the trimming depth of the pixel wafer is the same as or different from the trimming depth of the logic wafer.

10. The wafer trimming apparatus according to claim 8, characterized in that, The trimming width of both the pixel wafer and the logic wafer is 500μm to 2000μm; and / or, the trimming depth of both the pixel wafer and the logic wafer is 50μm to 300μm.

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