A device and method for thinning silicon wafer

Abstract

The present application proposes a thinning device and method for silicon wafers. The thinning device for silicon wafers includes a grinding tooth loading frame, which is in the shape of a long rod and is used to rotate around a rotation axis that vertically passes through the center of the silicon wafer; grinding teeth are arranged on the lower wall surface of the grinding tooth loading frame, wherein the grinding tooth loading frame is constructed to move away from or close to the rotation axis along the diameter direction of the silicon wafer to adjust the position. After the thinning device for silicon wafers is set in place, it only rotates around the fixed rotation axis until it reaches the grinding depth. The operation process is simple, convenient and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor wafer manufacturing, and in particular relates to a device and method for thinning a silicon wafer. Background Art

[0002] As wafer ultra-thinning becomes more and more prominent in the contemporary semiconductor manufacturing process, Taiko grinding (the reason why it is named Taiko grinding is that the wafer thinned by this process looks like a Japanese Taiko drum, and the Romanization of Taiko drum is TAIKO, so this process is called TAIKO grinding) wafer process is being used more and more.

[0003] During the manufacturing process of Taiko wafers, Taiko grinding is first performed to thin the silicon wafer to about 50 microns, for example, within the area within 0.5 to 10 mm of the edge, leaving only the area with a diameter of about 0.5 to 10 mm at the edge of the silicon wafer to maintain the initial thickness. The Taiko ring (i.e., the annular area with an initial thickness of 0.5 to 10 mm) provides sufficient mechanical strength support for the entire silicon wafer.

[0004] After the drum grinding is completed, the wafer is turned over to continue other chip processes. When all processes are completed, the drum ring is removed at the end (i.e. the step of ring grinding).

[0005] In the prior art, grinding wheels are often used to grind the drums and drum rings. The area that the grinding wheel can cover is smaller than the thinning area, so the grinding wheel moves within the thinning area according to the trajectory set by the program. In order to achieve uniform thinning, the entire process requires the laser interferometer to measure the thinning depth online, and through computer calculation, the running trajectory of the grinding wheel is adjusted in real time. The whole process is a cycle of thinning → online measurement → real-time feedback → calculation → adjustment of the thinning route.

[0006] In order to simplify the above operation process, the present invention relates to a thinning device and method for silicon wafers. Summary of the invention

[0007] Aiming at some or all of the above technical problems existing in the prior art, a device and method for thinning silicon wafers are provided. After the thinning device for silicon wafers is set in place, it only rotates around a fixed rotation axis until the grinding depth is reached, and the operation process is simple, convenient and easy to implement.

[0008] According to one aspect of the present invention, the proposed technical solution is:

[0009] A thinning device for silicon wafer, comprising:

[0010] A molar loading frame, which is in the shape of a long rod and is used to rotate around a rotation axis that passes vertically through the center of the silicon wafer.

[0011] The molars are arranged on the lower wall surface of the molar loading frame,

[0012] The molar loading frame is configured to move away from or closer to the rotating axis along the diameter direction of the silicon wafer to adjust the position.

[0013] In one embodiment, the number of the molar loading racks is at least three and they are evenly distributed in an array in the circumferential direction.

[0014] In one embodiment, the inner end of each molar loading frame is slidably connected to the circumferentially adjacent previous molar loading frame, and the inner end sections of all the molar loading frames are connected to form an N-sided polygon, where N is equal to the number of the molar loading frames.

[0015] In one embodiment, a first slideway extending along the axial direction of each molar loading frame is provided on the side wall thereof, and the inner end of the next molar loading frame adjacent in the circumferential direction is inserted into the first slideway to form a sliding connection.

[0016] In one embodiment, a locking assembly for limiting the position of the inner end of each molar loading frame is provided between the inner end of each molar loading frame and a matching molar loading frame.

[0017] In one embodiment, the locking assembly comprises:

[0018] A second slideway is provided on the upper wall surface of the molar loading frame, wherein the second slideway is connected to the first slideway,

[0019] A locking bolt, wherein the bolt end of the locking bolt passes through the second slideway and is threadedly engaged with the inner end of the molar loading frame inserted into the first slideway.

[0020] In one embodiment, according to requirements, the molars are arranged at the inner end section of the molar loading frame for grinding Taiko drums, or the molars are arranged at the outer end section of the molar loading frame for grinding Taiko drum rings.

[0021] In one embodiment, a plurality of molars located in the same axial direction on the molar loading frame are grouped together, the molars in one group are distributed axially at intervals, and the molars in different groups are distributed in a staggered manner.

[0022] In one embodiment, the molars are made of silicon carbide material.

[0023] According to another aspect of the present invention, the proposed technical solution is:

[0024] A method for thinning a silicon wafer using the above-mentioned thinning device for a silicon wafer comprises:

[0025] Step 1: adjusting the position of the molar loading frame so that the molar on the molar loading frame matches the diameter of the drum or the diameter of the drum ring.

[0026] Step 2: actuating the molar loading frame to rotate around the rotation axis to grind the corresponding Taiko drum or Taiko drum ring.

[0027] Compared with the prior art, the advantages of the present invention are: the grinding tooth loading frame is in the shape of a long rod. During the grinding process, the grinding tooth loading frame only needs to rotate around the center of the silicon wafer. During the rotation process, the grinding tooth can just cover the drum or drum ring that needs to be ground, and rotate and grind to a preset position, without the need for the grinding wheel to repeatedly adjust the position of the rotating axis to cover all surfaces that need to be ground as in grinding with a grinding wheel. Therefore, the thinning device of the present application makes the grinding operation simpler. In addition, since the grinding tooth loading frame can be adjusted along the diameter of the silicon wafer, the grinding range of the grinding tooth can be adaptively adjusted, thereby improving the applicability of the thinning device and the scope of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, in which:

[0029] Figure 1 A schematic diagram of a thinning device for silicon wafers according to a first embodiment of the present invention performing Taiko grinding is schematically shown;

[0030] Figure 2 A schematic diagram showing a first embodiment of the present invention in which a thinning device for silicon wafers performs Taiko ring grinding is shown;

[0031] Figure 3 A grinding loading frame suitable for Taiko grinding of a thinning device for silicon wafers according to an embodiment of the present invention is schematically shown;

[0032] Figure 4 A schematic diagram of a grinding loading frame for Taiko ring grinding of a silicon wafer thinning device according to another embodiment of the present invention is shown;

[0033] Figure 5 The schematic diagram shows the connection relationship between the C section of one grinding tooth loading frame and the inner end of another grinding tooth loading frame of the thinning device for silicon wafer according to one embodiment of the present invention;

[0034] Figure 6 Schematically showing a schematic diagram of the position adjustment of the grinding loading frame of the silicon wafer thinning device according to the first embodiment of the present invention;

[0035] Figure 7 A schematic diagram showing the position adjustment of the grinding loading frame of the silicon wafer thinning device according to the second embodiment of the present invention is shown;

[0036] Figure 8 Schematically showing a schematic diagram of the position adjustment of the grinding loading frame of the silicon wafer thinning device according to the third embodiment of the present invention;

[0037] Fig. 9 The schematic diagram shows a silicon wafer that has been thinned by Taiko grinding and has a Taiko ring on the edge.

[0038] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale. DETAILED DESCRIPTION

[0039] In order to make the technical solutions and advantages of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0040] The present application provides a thinning device for silicon wafers. Figures 1 to 8 As shown, the thinning device for silicon wafer includes a grinding tooth loading frame 1 and a grinding tooth 2. Among them, the grinding tooth loading frame 1 is in the shape of a long rod. During the grinding operation, the grinding tooth loading frame 1 is configured to rotate around a rotation axis 3. The rotation axis 3 vertically passes through the center of the silicon wafer 20. The grinding tooth 2 is arranged on the lower wall surface of the grinding tooth loading frame 1, and is used to move under the drive of the grinding tooth loading frame 1, and then grind the part that needs to be ground on the silicon wafer. Therefore, in the present application, the grinding tooth loading frame 1 rotates around a fixed rotation axis 3, and is used for circumferential motion grinding of silicon wafers. The grinding tooth loading frame 1 of this arrangement can cover the area that needs to be ground in all directions during the circumferential motion process, thereby improving the grinding efficiency. At the same time, the rotation axis 3 of the grinding tooth loading frame 1 of this arrangement does not need to be changed. During the grinding process, the grinding uniformity of each part in the axial direction of the grinding tooth loading frame 1 is strong, which helps to ensure the grinding quality. It can be understood that the length dimension of the grinding tooth loading frame 1 in the axial direction itself should be greater than the radius of the silicon wafer, so as to meet the size requirements to be ground.

[0041] According to the present application, the molar loading frame 1 is configured to move away from or closer to the rotating shaft 3 along the diameter direction of the silicon wafer 20 to adjust the position. Figure 6-8 An embodiment of the position adjustment of the molar loading frame 1 is provided. During the position adjustment process of the molar loading frame 1, the grinding coverage diameter thereof changes accordingly, thereby making the thinning device suitable for grinding different drum diameters or drum ring diameters. Figure 6As shown, when the molar loading frame 1 represented by the solid line expands to the dotted line position, the diameter that can be ground by the molar loading frame 1 becomes relatively smaller. Therefore, during the position change of the molar loading frame 1, drums with different diameters can be ground to meet the different needs of users.

[0042] There are at least three molar loading racks 1, which are evenly distributed in an array in the circumferential direction. On the one hand, this arrangement can improve the grinding efficiency. On the other hand, the above arrangement can improve the difference in the arrangement of the molars 2 of the molar loading racks 1, thereby improving the uniformity of the grinding surface everywhere.

[0043] In one embodiment, the inner end of each molar loading frame 1 is slidably connected to the circumferentially adjacent previous molar loading frame 1. The inner end sections of all molar loading frames 1 form an N-gon, where N is equal to the number of molar loading frames 1. Preferably, the inner ends of the molar loading frames 1 form a regular N-gon. Figures 6 to 8 Embodiments are given in which the thinning device has three, four, and five molar loading frames 1. Of course, the present application does not limit the number of specific molar loading frames 1 in the thinning device, that is, the number of molar loading frames 1 can be more or less according to actual needs. The inner end sections of different molar loading frames 1 are connected together, which can help ensure that all molar loading frames 1 are as a whole, ensure the uniformity of the feed amount of each molar loading frame 1, complete the grinding operation of the preset grinding amount, and thus ensure the grinding quality.

[0044] Specifically, Figures 3 to 5 As shown, a first slideway 4 extending along its own axial direction is provided on the side wall of a molar loading frame 1. And the inner end of the next molar loading frame 1 adjacent in the circumferential direction is inserted into the first slideway 4 to form a sliding connection. The inner end of a molar loading frame 1 slides relative to the first slideway 4, so that the molar loading frame 1 moves away from or close to the rotating shaft 3, thereby adjusting the grinding radius of the thinning device. Figure 1 As shown, the molar loading frame 1 includes four sections A, B, C and D in the axial direction from the outer end to the inner end, and the first slideway 4 is arranged on the side wall of the C section. Figures 6 to 8 As shown, when the inner ends of all the grinding teeth loading racks 1 slide relative to the matching first slideway 4, the diameter of the circumscribed circle of the N-gon can be changed. At the same time, the diameter of the circle where the outer ends of all the grinding teeth loading racks 1 are located also changes, so that the grinding size of the silicon wafer suitable for the thinning device is also adjusted accordingly.

[0045] When the inner end of one molar loading frame 1 slides relative to the matching first slideway 4, due to the linkage effect, the other molar loading frames 1 are simultaneously expanded or retracted. Then, the circular area covered by the molar 2 when rotating increases or decreases, so the diameter of the ground drum increases or decreases. Therefore, the thinning device can be widely used for different diameters of drums and drum rings that need to be ground, increasing the scope of use.

[0046] A locking assembly is provided between the inner end of each molar loading frame 1 and a matching molar loading frame 1 to limit the position of the inner end of the molar loading frame 1. Specifically, Figure 5 As shown, the locking assembly includes a second slide 5 and a locking bolt 6. The second slide 5 is arranged on the upper wall surface of each molar loading frame 1. At the same time, the second slide 5 is connected to the first slide 4. For example, the molar loading frame 1 itself can be a tubular body, and the second slide 5 and the first slide 4 are connecting holes opened on the molar loading frame 1. After the bolt end of the locking bolt 6 passes through the second slide 5, it is threadedly matched with the inner end of the molar loading frame 1 inserted into the first slide 4. When the inner end of the molar loading frame 1 slides into place in the first slide 4, the inner end of the molar loading frame 1 can be locked and limited to the C section of the molar loading frame 1 matched therewith by screwing the locking bolt 6. It can be understood that when it is necessary to adjust the grinding radius of the thinning device, it is necessary to first reversely screw the locking bolt 6 to unlock the inner end of the molar loading frame 1.

[0047] According to actual needs, the molar 2 is arranged at different positions of the molar loading frame 1. For example, when the thinning device needs to grind the drum 21, the molar 2 is arranged at the inner end section of the molar loading frame 1 for grinding the drum 21. Figure 3 As shown, the molars 2 are provided on the B, C and D sections of the molar loading frame 1 for adaptively matching the size of the drum 21. At this time, the molars 2 are not provided on the A section of the molar loading frame 1. When the thinning device is used to perform thinning and grinding of the drum 21, the specific position of each molar loading frame 1 is adjusted according to the diameter of the drum to be ground, so that the B, C and D sections match the diameter of the drum to be ground. In other words, the molar 2 located at the outermost end of the B section is opposite to the diameter edge position of the drum 21. During the rotation of the molar loading frame 1 around the rotating axis 3, the A section overlaps the drum ring 22, while the molars 2 on the B, C and D sections penetrate into the drum to grind the silicon wafer, and finally a drum with a size that meets the requirements is formed, as shown in FIG. Fig. 9 shown.

[0048] In addition, when the thinning device needs to grind the drum ring, the grinding teeth 2 are arranged at the outer end section of the grinding teeth loading frame 1 for grinding the drum. Figure 4As shown, there are no molars 2 in the B, C and D sections of the molar loading frame 1, while the A section of the molar loading frame 1 is provided with molars 2. When the thinning device is used to thin and grind the drum ring, the A section overlaps the drum ring 22, and the molars 2 grind the drum ring 22 until a preset depth. It can be understood that the axial dimension of the A section can be relatively large to improve applicability. For example, the axial dimension of the A section is 15 mm, which can grind a drum ring 22 with a radial width of 0.5 mm, and can also be suitable for a drum ring 22 with a radial width of 10 mm. During grinding, in order to avoid affecting the Taiko drum when grinding the Taiko drum ring 22, the innermost molar 2 of section A is used as a position reference for the innermost end of the Taiko drum ring 22, and the outer end of section A extends toward the outer end of the Taiko drum ring 22, so that the molar 2 of section A overlaps the Taiko drum ring 22, and the molar 2 just completely covers the width of the Taiko drum ring 22 that needs to be ground, or is larger than the width of the Taiko drum ring 22 and extends out of the outermost end of the Taiko drum ring 22.

[0049] It can be understood that the molars 2 of the thinning device can be detachably arranged at the corresponding position of the corresponding molar loading frame 1. Of course, in order to simplify the structure, two sets of thinning devices can be provided, and the molars 2 are arranged at different positions for distributed grinding of the drum and the drum ring.

[0050] In one embodiment, Figure 3 and 4 As shown, multiple molars 2 in the same axial direction on the molar loading frame 1 are grouped. The molars 2 in one group are distributed in an axially spaced manner on the molar loading frame 1 itself. The molars 2 in different groups are distributed in a staggered manner to ensure that each area to be ground on the silicon wafer can be ground and thinned. According to actual needs, one or more groups of molars 2 can be set on a molar loading frame 1. Preferably, the molars 2 are made of silicon carbide material.

[0051] The present application also relates to a method for thinning using the thinning device.

[0052] First, the Taiko thinning and grinding operation is performed. According to the diameter of the Taiko that needs to be ground, the position of the molar loading frame 1 can be adjusted. Specifically, the locking bolt 6 is in an unlocked state. At this time, the inner end of the molar loading frame 1 can slide in the first slide 4, thereby adjusting the area covered by the molar 2. After the circular diameter covered by the molar 2 is consistent with the Taiko grinding diameter. Adjust the locking bolt 6 to define the relative position of each molar loading frame 1. Afterwards, the molar loading frame 1 can be driven to rotate around the rotating axis 3, and the molar 2 is driven to rotate to grind the surface of the silicon wafer. After thinning to the expected depth, the Taiko thinning process ends. In this operation, there is no need to adjust the position of the rotating axis 3 of the friction reduction device, and it is only necessary to match the grinding depth fed to the molar loading frame 1 with the depth of Taiko grinding.

[0053] Then, other steps of chip processing can be performed on the front side of the silicon wafer 20. After these steps are completed, the drum ring 22 is thinned. At this time, the thinning device can be selected to be suitable for the drum ring 22, specifically, only the thinning device with the molar 2 in the D section. The position of the molar loading frame 1 is adjusted so that the molar 2 can just cover the drum ring, and the position of each molar loading frame 1 is locked. The molar loading frame 1 is driven to select, and then the drum ring is ground until it is ground to the preset position.

[0054] It can be understood that the thinning device of the present application can be used in both grinding the drum and grinding the drum ring, or the thinning device of the present application can be used only in the grinding drum operation or only in the grinding drum ring operation.

[0055] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and / or modifications that fall within the scope of the present invention, and changes and / or modifications made according to the embodiments of the present invention should be included within the scope of protection of the present invention.

Claims

1. A thinning device for silicon wafers, characterized in that: include: A molar loading frame, which is in the shape of a long rod and is used to rotate around a rotation axis that passes vertically through the center of the silicon wafer. The molars are arranged on the lower wall surface of the molar loading frame, The molar loading frame is configured to adjust the position by moving away from or close to the rotating axis along the diameter direction of the silicon wafer. There are at least three molar loading frames, which are evenly distributed in an array in the circumferential direction. The inner end of each molar loading frame is slidably connected to the upper molar loading frame adjacent to the upper molar loading frame in the circumferential direction. The inner end sections of all the molar loading frames are connected to form an N-gon, where N is equal to the number of the molar loading frames. A first slideway extending along its own axial direction is provided on the side wall of each molar loading frame, and the inner end head of the next molar loading frame adjacent to the upper molar loading frame in the circumferential direction is inserted into the first slideway to form a sliding connection. A locking assembly for limiting the position of the inner end head of each molar loading frame is provided between the inner end head of each molar loading frame and a matching molar loading frame.

2. The device for thinning a silicon wafer according to claim 1, characterized in that: The locking assembly comprises: A second slideway is provided on the upper wall surface of the molar loading frame, wherein the second slideway is connected to the first slideway, A locking bolt, wherein the bolt end of the locking bolt passes through the second slideway and is threadedly engaged with the inner end of the molar loading frame inserted into the first slideway.

3. The device for thinning a silicon wafer according to claim 1 or 2, characterized in that: According to the requirements, the molars are arranged at the inner end section of the molar loading frame for grinding the drum, or the molars are arranged at the outer end section of the molar loading frame for grinding the drum ring.

4. The device for thinning a silicon wafer according to claim 3, characterized in that: The multiple molars on the molar loading frame in the same axial direction form a group, the molars in one group are distributed axially at intervals, and the molars in different groups are distributed in a staggered manner.

5. The device for thinning a silicon wafer according to claim 1 or 2, characterized in that: The molars are made of silicon carbide material.

6. A method for thinning a silicon wafer using the thinning device for silicon wafer according to any one of claims 1 to 5, characterized in that: include: Step 1: adjusting the position of the molar loading frame so that the molar on the molar loading frame matches the diameter of the drum or the diameter of the drum ring. Step 2: actuating the molar loading frame to rotate around the rotation axis to grind the corresponding Taiko drum or Taiko drum ring.

Images