WO2023197237A1 - Lapping table, lapping head, lapping apparatus and lapping method - Google Patents

Abstract

A lapping table (100), comprising a rigid body (110), and the rigid body being used for carrying a wafer (20) and provided with a cavity. The lapping table further comprises a plurality of first through holes (V1) passing through the upper surface of the rigid body from the cavity and a second through hole (V2)passing through the bottom of the rigid body from the cavity. A pressure reduction device (120) is arranged at the bottom of the rigid body, and may depressurize the cavity in the rigid body by means of the second through hole. A lapping head (10), comprising the lapping table and a rotating part (200). An lapping apparatus, comprising the lapping head and a rotating disk (30). Also provided is a lapping method using the lapping apparatus for lapping. During lapping, the pressure reduction device can be controlled to depressurize the cavity in the rigid body, so that the pressure intensity in the cavity is far smaller than that of the outside, and the wafer can be firmly adsorbed on the rigid body by means of the first through holes in the upper surface of the rigid body. The arrangement of a positioning ring used for preventing the wafer from sliding out in a traditional lapping process can be omitted, and the influence on the edge flatness of the wafer caused by the positioning ring during the lapping process can be avoided.

Description

Grinding table, grinding head, grinding equipment and grinding method Technical field

The present application relates to the field of semiconductor manufacturing technology, and in particular to a grinding table, a grinding head, a grinding equipment and a grinding method.

Background technique

Chemical Mechanical Planarization (CMP) technology is a commonly used planarization technology in semiconductor manufacturing. The chemical grinding equipment used in the CMP process is shown in Figure 1, including a grinding head 01, a rotating disk 02, a polishing pad 03 provided on the rotating disk 02, and a grinding fluid nozzle (not shown in the figure). During the chemical mechanical polishing process, the grinding head 01 adsorbs the back side of the wafer 04, and the grinding head 01 exerts corresponding pressure on the back side of the wafer 04, pressing the front side of the wafer 04 down on the grinding pad 03, and the grinding fluid nozzle sprays The polishing liquid is placed between the front side of the wafer 04 and the polishing pad 03, and the front side of the wafer 04 is planarized by the friction force generated by the difference in linear speed between the front side of the wafer 04 and the polishing pad 03.

During the CMP process, the main function of the grinding head 01 is to provide pressure on the back side of the wafer 04. The traditional grinding head 01 is shown in Figure 2 and mainly consists of a body 010 and a positioning ring 011. The body 010 is the main source of pressure for the backside of the wafer, and will directly contact the backside of the wafer 04. The body 010 is composed of multiple annular air bag areas 001. When the air bag areas 001 are ventilated, the air bag areas 001 will inflate to provide pressure on the back side of the wafer 04. The function of the positioning ring 011 is to prevent the wafer 04 from slipping out during the polishing process. Therefore, during the grinding process, the positioning ring 011 needs to exert greater pressure to reduce the gap between the positioning ring 011 and the polishing pad 03 to prevent the wafer 04 from slipping out. Slide out. However, the greater pressure exerted by the positioning ring 011 will form grooves on the polishing pad 03 , thereby affecting the flatness of the edge of the wafer 04 .

Contents of the invention

This application provides a grinding table, grinding head, grinding equipment and grinding method that can avoid the impact on the flatness of the wafer edge during grinding.

In the first aspect, the grinding table provided by the embodiments of the present application may include a rigid body. The rigid body is used to carry the wafer. During grinding, the wafer can be placed on the rigid body. The side of the wafer that needs to be grinded (for example, the wafer The front side) faces away from the rigid body, so that the front side of the wafer is in contact with the polishing pad. By providing upward pressure on the bottom of the rigid body, upward pressure is provided on the wafer. By controlling the rotation speed of the rigid body and the polishing pad, the wafer is Relative motion occurs between the front surface and the polishing pad to generate friction, thereby flattening the front surface of the wafer.

In this application, there is a cavity inside the rigid body, and the grinding table further includes a plurality of first via holes penetrating from the cavity to the upper surface of the rigid body and second via holes penetrating from the cavity to the bottom of the rigid body. , a pressure reducing device is also provided at the bottom of the rigid body, and the pressure reducing device can depressurize the cavity in the rigid body through the second through hole. During grinding, the pressure reducing device can be controlled to depressurize the cavity in the rigid body so that the pressure inside the cavity is much smaller than the external pressure, so that the wafer can be firmly secured through the first via hole on the upper surface of the rigid body. It is adsorbed on the rigid body, which not only eliminates the installation of bit rings used to prevent the wafer from slipping out in the traditional grinding process, but also avoids the impact of the bit rings on the flatness of the wafer edge during the grinding process. In addition, in this application, the wafer is adsorbed on the rigid body during the grinding process, and there is basically no relative movement between the wafer and the rigid body. Therefore, the wear of the wafer on the rigid body can be reduced, thereby reducing the manufacturing cost of semiconductor devices. cost.

In specific implementation, the decompression device decompresses the cavity so that the pressure inside the cavity is smaller than the external pressure. When the pressure inside the cavity is small to a certain extent, it can pass through the first pass on the upper surface of the rigid body. The holes firmly adsorb the wafer to the rigid body.

For example, the pressure reducing device can reduce pressure by evacuating the cavity, and the pressure (or vacuum degree) of the cavity can be controlled by the pressure reducing device according to actual usage conditions, which is not limited here.

In this application, the rigid body can be formed of rigid material to ensure that the rigid body will not deform when the cavity in the rigid body is decompressed.

For example, in one embodiment, the rigid body can be formed of graphene, ceramics or organic materials, which can prevent the grinding table from causing damage to the wafer. Alternatively, in another embodiment, the upper surface of the rigid body can also be coated with graphene, ceramics or organic materials to avoid damage to the wafer caused by the grinding table.

For example, in the grinding table, the rigid body may include a central rigid cavity portion located in the central area and a plurality of annular rigid cavity portions arranged sequentially and outwardly surrounding the central rigid cavity portion, so that the pressure reducing device can be used to Different rigid cavity parts perform different degrees of pressure reduction. For example, for a wafer with a curved edge, the pressure of different rigid cavity parts can be controlled before grinding to change the deformation of the wafer itself before grinding, so that the wafer can fit horizontally on the grinding table. This makes the polished wafer surface smoother.

It should be noted that the "central area" mentioned in this application refers to the central area in the plane, so the annular rigid cavity portion is only provided around the central rigid cavity portion on the side surfaces of the central rigid cavity portion.

In this application, the rigid cavity portion may be composed of an upper surface, a lower surface, and a cavity wall, wherein the central rigid cavity portion may include an upper surface, a lower surface, and an outer cavity wall connecting the upper surface boundary and the lower surface boundary, so that in The area enclosed by the upper surface, lower surface and outer cavity wall forms a cavity. The annular rigid cavity portion may include an annular upper surface, an annular lower surface, an outer cavity wall connecting the outer boundary of the upper surface and the outer boundary of the lower surface, and an inner cavity wall connecting the inner boundary of the upper surface and the inner boundary of the lower surface, so that on the upper surface The area enclosed by the surface, the lower surface, the outer cavity wall and the inner cavity wall forms an annular cavity.

Adaptably, when the rigid body includes a central rigid cavity portion and a plurality of annular rigid cavity portions, the central rigid cavity portion and the plurality of annular rigid cavity portions may be formed of graphene, ceramic or organic materials, or, may The upper surfaces of the central rigid cavity portion and the plurality of annular rigid cavity portions are coated with graphene, ceramics or organic materials.

It should be noted that the rigid cavity part mentioned in this application may be a central rigid cavity part or any annular rigid cavity part.

In this application, the upper surface of the central rigid cavity portion can be a regular figure, such as an equilateral polygon, a circle, etc., and the shape of the boundary of the upper surface of each annular rigid cavity portion is consistent with the upper surface of the central rigid cavity portion. The shapes are the same, for example, the upper surface of the central rigid cavity portion is circular, and the boundaries of the upper surfaces of each annular rigid cavity portion are also circular.

For example, in this application, the upper surface of the central rigid cavity part is circular, and the upper surface of each annular rigid cavity part is annular, thereby ensuring that when the grinding table rotates, the central rigid cavity part The center of is the center of the circle, and the pressure is the same at positions at the same distance from the center of the circle.

For example, in this application, the central rigid cavity part and the plurality of annular rigid cavity parts can be an integral structure, so that a central rigid cavity can be formed as long as a plurality of annular cavity walls are provided between the upper surface and the lower surface. The body portion and multiple annular rigid cavity portions, that is, adjacent rigid cavity portions, can share a cavity wall, thereby reducing the manufacturing difficulty of the grinding table.

Optionally, in this application, the grinding table can also be provided with a pressure supply device at the bottom of the rigid body. During grinding, the pressure supply device can provide upward or downward pressure to the rigid body. Compared with traditional grinding heads that require inflating to provide pressure on the wafer, the pressure supply device can provide more precise pressure control on the rigid body.

It should be noted that this application does not limit the specific implementation of the pressure supply device. It may be any structure capable of providing upward or downward pressure to the rigid body. For example, the pressure supply device may include at least one hydraulic telescopic cylinder and a hydraulic telescopic cylinder connected to the pressure supply device. At least one hydraulic telescopic cylinder has a one-to-one corresponding telescopic rod, wherein the telescopic rod connects the hydraulic telescopic cylinder and the rigid body; the hydraulic telescopic cylinder provides upward or downward pressure to the rigid body through the telescopic telescopic rod.

In order to improve the flatness of grinding, for example, the plurality of annular rigid cavity parts are nested outward from the central rigid cavity part in sequence, that is, the first annular rigid cavity part is sleeved outside the central rigid cavity part, and the first annular rigid cavity part is sleeved outside the central rigid cavity part. The two annular rigid cavity parts are placed outside the first annular rigid cavity part, and the Nth annular rigid cavity part is placed outside the N-1th annular rigid cavity part, so that the central rigid cavity part and Any one of the plurality of annular rigid cavity portions can move in the axial direction of the central rigid cavity portion relative to the remaining rigid cavity portions. In this way, the pressure exerted on the bottom of each rigid cavity can be independently controlled during grinding, thereby improving the flatness of grinding. Moreover, compared with the problem of grinding rate at the junction caused by deformation of the traditional polishing head in different air bag areas, in this application, there is no deformation at the junction of each rigid cavity part, and the pressure acting on the wafer increases in each rigid cavity. The cavity parts and junctions are evenly distributed, thus providing better flatness.

Of course, during specific implementation, among the central rigid cavity portion and the multiple annular rigid cavity portions, one or multiple adjacent rigid cavity portions can also be used as a group, and the central rigid cavity portion and multiple annular rigid cavity portions can be Each annular rigid cavity part is divided into multiple groups, and the groups are nested. The groups can move relative to each other along the axial direction of the central rigid cavity part. Among the multiple rigid cavity parts in the group, There cannot be relative movement between them, and there is no limit here.

Optionally, when a plurality of annular rigid cavity portions are sequentially nested outward from the central rigid cavity portion, the grinding table may also include a first pressure supply device and a plurality of annular rigid cavity portions corresponding to the plurality of annular rigid cavity portions. The second pressure supply device; the plurality of second pressure supply devices and the plurality of annular rigid cavity parts have a one-to-one correspondence relationship, that is, each second pressure supply device corresponds to an annular rigid cavity part, and each annular rigid cavity part Part also corresponds to only one second pressure supply device. The first pressure supply device is located at the bottom of the central rigid cavity and is used to provide upward or downward pressure to the central rigid cavity; each of the plurality of second pressure supply devices is located at a corresponding annular The bottom of the rigid cavity portion is used to provide upward or downward pressure to the corresponding annular rigid cavity portion. Compared with the traditional polishing head that needs to provide pressure to the wafer by inflating, the first pressure supply device and the second pressure supply device can provide more precise pressure control for the corresponding rigid cavity portion.

It should be noted that this application does not limit the implementation of the first pressure supply device and the second pressure supply device, and they may be any structure capable of providing upward or downward pressure.

For example, the first pressure supply device may include a hydraulic telescopic cylinder and a telescopic rod connecting the hydraulic telescopic cylinder and the central rigid cavity portion; the hydraulic telescopic cylinder provides upward or downward pressure to the central rigid cavity portion through the telescopic telescopic rod.

Of course, during specific implementation, the first pressure supply device may also include a plurality of hydraulic telescopic cylinders and telescopic rods corresponding to the plurality of hydraulic telescopic cylinders, which is not limited here.

Exemplarily, the second pressure supply device may include at least two hydraulic telescopic cylinders and telescopic rods corresponding to each hydraulic telescopic cylinder; the hydraulic telescopic cylinders are connected to the corresponding annular rigid cavity portion through the corresponding telescopic rods, and the hydraulic telescopic cylinders pass through The corresponding telescopic rod provides upward or downward pressure to the corresponding annular rigid cavity portion.

For example, in order to ensure that the annular rigid cavity portion is evenly stressed, the at least two hydraulic telescopic cylinders in the second pressure supply device can be evenly distributed.

Optionally, in this application, in order to reduce costs, the second pressure supply device may include two hydraulic telescopic cylinders and two telescopic rods.

In this application, the greater the number of annular rigid cavity portions in the rigid body, the finer the pressure control at different locations during the grinding process. Optionally, the rigid body may include at least 4 annular rigid cavity parts, such as 4, 5, 6, etc. This application does not limit the number of annular rigid cavity parts, and can be determined based on actual conditions such as grinding effect and cost.

In specific implementation, the first via hole can be provided on the upper surface of the central rigid cavity portion, or the first via hole can be provided on the upper surface of at least one rigid cavity portion among the plurality of annular rigid cavity portions. Of course, The first via hole may also be provided on the upper surface of the central rigid cavity part and at least one rigid cavity part, which is not limited here. The second via hole is provided at the bottom of the rigid cavity portion with the first via hole. That is, as long as the upper surface of the rigid cavity portion has the first via hole, the bottom of the rigid cavity portion will be provided with the second via hole. hole, so that the second via hole is used to depressurize the rigid cavity part, and the first via hole is used to absorb the wafer.

Optionally, in this application, in order to increase the adsorption between the rigid cavity part and the wafer, a plurality of first via holes may be provided on the upper surface of the rigid cavity part.

Exemplarily, in this application, a plurality of first via holes are provided on the upper surface of each of the central rigid cavity portion and the plurality of annular rigid cavity portions, and the central rigid cavity portion and the plurality of annular rigid cavity portions are provided with a plurality of first via holes. A second via hole is provided at the bottom of each of the annular rigid cavity portions, so that each rigid cavity portion can absorb the wafer.

In this application, the plurality of first via holes provided in the same rigid cavity part are evenly distributed, which can ensure that the adsorption force of the same rigid cavity part to the wafer is evenly distributed.

For example, in this application, the plurality of first via holes in each of the central rigid cavity portion and the plurality of annular rigid cavity portions are evenly distributed.

This application also does not limit the number and shape of the air holes in the same rigid cavity part, and the design can be based on the actual product. Optionally, in this application, in order to improve the adsorption capacity, at least 4 first via holes can be provided in the same rigid cavity part.

For example, in this application, each of the central rigid cavity portion and the plurality of annular rigid cavity portions is provided with at least 4 first via holes.

It should be noted that in this application, the number of first via holes in different rigid cavity parts may be the same or different. For example, the closer to the edge of the rigid cavity part, the greater the number of first via holes.

In this application, the shapes of the plurality of first via holes in the same rigid cavity part may be the same or different, and are not limited here. Optionally, multiple first via holes located in the same rigid cavity portion have the same shape, thereby ensuring the consistency of each first via hole in the multiple first via holes.

In this application, the shapes of the first via holes located in different rigid cavity parts may be the same or different, and are not limited here. Optionally, in this application, the shapes of the first via holes located in different rigid cavity parts are the same.

In specific implementation, the traditional grinding head has poor edge control effect on the wafer, and is prone to the problem of more edges being ground. Based on this, the grinding table of the present application also includes an annular rigid groove arranged around the rigid body. In this way, when the wafer is placed on the grinding table, the edge of the wafer can be located on the annular rigid groove, that is, the bottom of the edge of the wafer is suspended, thereby reducing the degree of grinding of the edge of the wafer during grinding.

Optionally, in this application, the bottom of the annular rigid groove is also provided with a third through hole, and the decompression device is also used to decompress the annular rigid groove through the third through hole. In this way, the annular rigid groove can be decompressed by the decompression device, so that the edge of the wafer can be deformed downward, thereby increasing the distance from the edge of the wafer to the polishing pad during grinding, thereby further reducing the impact on the wafer. The degree of edge grinding can even avoid grinding the wafer edge.

This application does not limit the diameter width of the central rigid cavity portion, the ring width of the annular rigid cavity portion, and the width of the annular rigid groove, and can be designed according to specific actual products.

In addition, it should be noted that this application does not limit the implementation of the pressure reducing device, as long as it can make the pressure in the cavity much smaller than the external pressure, for example, it can be a vacuum device.

Exemplarily, the pressure reducing device may include a first vacuum valve, the first vacuum valve is disposed at the bottom of the rigid cavity portion with the second through hole, and the first vacuum valve is in communication with the second through hole.

Further, in this application, a third via hole is provided at the bottom of the annular rigid groove, and the pressure reducing device further includes a second vacuum valve located at the bottom of the annular rigid groove and connected to the third via hole.

In a second aspect, the present application also provides a grinding head. The grinding head may include a rotating part and a grinding table fixed on the rotating part as provided in any one of the embodiments of the first aspect. The rotating part is configured as The grinding table is carried and rotated with the rotating part.

In a possible embodiment, the rotating part may include a carrying part and a rotating motor. Among them, the bearing part is used to carry and install the grinding table; the rotating motor is located on the side of the bearing part and is used to drive the bearing part to rotate, and the grinding head installed on the bearing part can rotate with the bearing part.

This application does not limit the specific implementation of the bearing part, and it can be any structure that can implement the solution of this application.

The technical effects that can be achieved in the second aspect can be referred to the description of the technical effects that can be achieved by any possible design in the first aspect, and will not be repeated here.

In a third aspect, the application also provides a grinding head. The grinding equipment includes a rotating disk and a grinding head as provided in any embodiment of the first aspect. The rotating disk is configured to be located above the grinding head during grinding. , the wafer is sandwiched between the grinding head and the rotating disk, and the side of the rotating disk facing the grinding head is attached with a polishing pad. The rotating polishing head and the rotating polishing pad cause relative movement between the front side of the wafer and the polishing pad to generate friction, thereby flattening the front side of the wafer. The other essential components of the grinding equipment are all understood by those of ordinary skill in the art, and will not be described in detail here, nor should they be used to limit the present application. The implementation of the grinding equipment can refer to the above embodiments, and repeated details will not be described again.

The technical effects that can be achieved in the third aspect can be referred to the description of the technical effects that can be achieved by any possible design in the first aspect, and will not be repeated here.

In a fourth aspect, the present application also provides a grinding method using any of the above-mentioned grinding equipment. During grinding, after placing the wafer on the grinding table of the grinding head, the pressure reducing device controls the impact of the rigid body on the grinding table. The cavity is depressurized to adsorb the wafer to the grinding table, and then the rotating disk is controlled to be positioned on the wafer so that the polishing pad on the rotating disk is in contact with the wafer. Finally, the grinding table and the rotating disk are controlled to rotate to polish the wafer. The circle is flattened. In this application, the grinding table firmly adsorbs the wafer to the grinding table during grinding, which not only eliminates the need for the bit ring used to prevent the wafer from slipping out in the traditional grinding process, but also avoids the bit ring belt during the grinding process. The impact on wafer edge flatness. Moreover, during the grinding process, the wafer is adsorbed on the grinding table, and there is basically no relative movement between the wafer and the grinding table. Therefore, the wear of the wafer on the grinding table can be reduced, thereby reducing the manufacturing cost of semiconductor devices.

Optionally, when the grinding table includes a central rigid cavity part and a plurality of annular rigid cavity parts, controlling the decompression device to decompress the cavity of the rigid body includes: controlling the decompression device to decompress the cavity according to the edge curvature of the wafer. The central rigid cavity portion and the plurality of annular rigid cavity portions are depressurized to control the pressure of each of the central rigid cavity portion and the plurality of annular rigid cavity portions. Therefore, before grinding, the pressure of different rigid cavity parts can be controlled to change the deformation of the wafer itself before grinding, so that the wafer can be horizontally attached to the grinding table, thereby making the surface of the polished wafer smoother. .

When the edge of the wafer is bent upward, the pressure of the rigid cavity tends to decrease with the distance of the rigid cavity from the axis of the central rigid cavity. For example, the farther an annular rigid cavity part is from the axis of the central rigid cavity part, the smaller the pressure of the annular rigid cavity part. This application includes but is not limited to the pressure of several adjacent rigid cavity parts being the same. , as long as the overall trend is ensured that the pressure of the annular rigid cavity near the edge is less than the pressure of the annular rigid cavity near the center, the specific design needs to be based on the degree and range of the wafer bending.

When the edge of the wafer is bent downward, the pressure of the annular rigid cavity portion tends to increase with the distance of the annular rigid cavity portion from the central rigid cavity portion. For example, the farther the annular rigid cavity part is from the central rigid cavity part, the greater the pressure of the annular rigid cavity part, but the pressure of several adjacent rigid cavity parts including but not limited to this application is the same. As long as the overall trend is ensured that the pressure of the annular rigid cavity near the edge is greater than the pressure of the annular rigid cavity near the center, the specific design needs to be based on the degree and range of the wafer bending.

In specific implementation, the traditional grinding head has poor control effect on the edge of the wafer, and is prone to the problem of more edges being ground. Therefore, in this application, when the grinding table also includes an annular rigid groove arranged around the rigid body When controlling the grinding table and the rotating disk to rotate, the decompression device can also be controlled to decompress the annular rigid groove. In this way, the annular rigid groove can be decompressed by the decompression device, which can deform the wafer edge downward, thereby increasing the distance between the wafer edge and the polishing pad during polishing, thereby reducing the impact on the wafer. The degree of edge grinding can even avoid grinding the wafer edge.

Optionally, when the grinding table includes a pressure supply device located at the bottom of the rigid body, when controlling the grinding table and the rotating disk to rotate, the pressure supply device can also be controlled to provide upward pressure to the rigid body. Compared with traditional grinding heads that require inflating to provide pressure on the wafer, the pressure supply device can provide more precise pressure control on the rigid body.

For example, when the grinding table includes a first pressure supply device and a plurality of second pressure supply devices, when controlling the grinding table and the rotating disk to rotate, the first pressure supply device and the plurality of second pressure supply devices can be controlled respectively. Provide upward pressure to the corresponding rigid cavity portion. In this way, the pressure exerted on the bottom of each rigid cavity can be independently controlled during grinding, thereby improving the flatness of grinding. Moreover, compared with the problem of grinding rate at the junction caused by deformation of the traditional polishing head in different air bag areas, in this application, there is no deformation at the junction of each rigid cavity part, and the pressure acting on the wafer increases in each rigid cavity. The cavity parts and junctions are evenly distributed, thus providing better flatness.

Optionally, in this application, after the wafer is planarized, the decompression device can also be controlled to stop decompressing the plurality of annular rigid cavity parts; the first pressure supply device can be controlled to depressurize the central rigid cavity part. Provide upward pressure to move the central rigid cavity portion upward relative to the plurality of annular rigid cavity portions; and control the decompression device to stop decompressing the central annular rigid cavity portion.

Description of the drawings

Figure 1 is a schematic structural diagram of the chemical grinding equipment used in the CMP process;

Figure 2 is a schematic structural diagram of a traditional grinding head;

Figure 3 is a schematic structural diagram of a grinding table provided by an embodiment of the present application;

Figure 4 is a structural schematic diagram of the rigid body of the grinding table provided by the embodiment of the present application;

Figure 5 is a schematic diagram of the grinding table adsorbing the wafer provided by the embodiment of the present application;

Figure 6 is another schematic diagram of the grinding table adsorbing the wafer provided by the embodiment of the present application;

Figure 7 is a schematic structural diagram of the central rigid cavity provided by the embodiment of the present application;

Figure 8 is a schematic structural diagram of an annular rigid cavity provided by an embodiment of the present application;

Figure 9 is a schematic structural diagram of another grinding table provided by an embodiment of the present application;

Figure 10 is a schematic structural diagram of the rigid body of the grinding table provided by the embodiment of the present application;

Figure 11 is a schematic structural diagram of another grinding table provided by an embodiment of the present application;

Figure 12 is a schematic structural diagram of another grinding table provided by an embodiment of the present application;

Figure 13 is a schematic top view of the structure of the grinding table provided by the embodiment of the present application;

Figure 14 is a schematic structural diagram of a grinding head provided by an embodiment of the present application;

Figure 15 is a schematic structural diagram of another grinding head provided by an embodiment of the present application;

Figure 16 is a schematic structural diagram of a grinding equipment provided by an embodiment of the present application;

Figure 17 is a schematic flow chart of a grinding method provided by an embodiment of the present application;

Figure 18 is a working schematic diagram of the grinding equipment provided by the embodiment of the present application;

Figure 19 is another working schematic diagram of the grinding equipment provided by the embodiment of the present application.

Explanation of reference symbols:

10-grinding head; 20-wafer; 30-rotating disk; 31-polishing pad; 100-grinding table; 110-rigid body; 120-pressure reducing device; 130-pressure supply device; 131-first pressure supply device; 132-second pressure supply device; 140-annular rigid groove; V1-first via hole; V2-second via hole; 1100-central rigid cavity part; 110n-annular rigid cavity part; 121-first vacuum Valve; 122-second vacuum valve; 110a-the upper surface of the rigid cavity part; 110b-the lower surface of the rigid cavity part; 110c-the outer cavity wall of the rigid cavity part; 110d-the inner cavity wall of the rigid cavity part ; 1311-The hydraulic telescopic cylinder of the first pressure supply device; 1312-The telescopic rod of the first pressure supply device; 1321-The hydraulic telescopic cylinder of the second pressure supply device; 1322-The telescopic rod of the second pressure supply device; 200-Rotation part; 210-carrying part; 220-rotating motor.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be described in further detail below in conjunction with the accompanying drawings.

The terminology used in the following examples is for the purpose of describing specific embodiments only and is not intended to limit the application. As used in the specification and claims of this application, the singular expressions "a," "an," "the above," "the" and "the" are intended to also include, for example, "one or more ” form of expression unless the context clearly indicates otherwise.

In the description of this application, it should be noted that the terms "middle", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present application and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation or a specific orientation. construction and operation, and therefore should not be construed as limitations on this application. The words expressing position and direction described in this application are all explained by taking the accompanying drawings as examples, but they can be changed as needed, and all changes are included in the protection scope of this application. The drawings in this application are only used to illustrate relative positional relationships and do not represent true proportions. In addition, the terms "first" and "second" are used for descriptive purposes only and are not to be understood as indicating or implying relative importance.

In the description of this application, it should be noted that, unless otherwise clearly stated and limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be It is directly connected, or it can be indirectly connected through an intermediary, or it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood on a case-by-case basis.

In order to facilitate understanding of the grinding head provided in the embodiment of the present application, its application scenario is first described. The technical solution of this application can be applied to CMP equipment. The CMP equipment includes a grinding head and a grinding pad. When grinding, the wafer can be sandwiched between the grinding head and the grinding pad, and the grinding head exerts corresponding pressure on the back of the wafer. The front side of the wafer is pressed against the polishing pad, and the front side of the wafer is flattened by the friction force generated by the difference in linear speed between the front side of the wafer and the polishing pad. The present application will be described in further detail below with reference to the accompanying drawings.

Referring to Figure 3, Figure 3 is a schematic structural diagram of a grinding table provided by an embodiment of the present application. The grinding table 100 includes a rigid body 110. The rigid body 110 is used to carry the wafer 20. During grinding, the wafer 20 can be placed on the rigid body 110. The side of the wafer 20 that needs to be grinded (for example, the front side of the wafer 20) Facing away from the rigid body 110 , so that the front side of the wafer 20 is in contact with the polishing pad 31 , upward pressure can be provided on the bottom of the rigid body 110 to provide upward pressure on the wafer. By controlling the relationship between the rigid body 110 and the polishing pad 31 The rotation speed causes relative movement between the front surface of the wafer 20 and the polishing pad 31 to generate friction, thereby flattening the front surface of the wafer 20 .

Continuing to refer to FIG. 3 , there is a cavity inside the rigid body 110 . The grinding table 100 also includes a plurality of first vias V1 penetrating from the cavity to the upper surface of the rigid body 110 and a plurality of first vias V1 penetrating from the cavity to the rigid body 110 . The second via hole V2 at the bottom is provided with a pressure reducing device 120 at the bottom of the rigid body 110. The pressure reducing device 120 can decompress the cavity in the rigid body 110 through the second via hole V2. During grinding, the pressure reducing device 120 can be controlled to depressurize the cavity in the rigid body 110 so that the pressure inside the cavity is much smaller than the external pressure, so that the first through hole V1 on the upper surface of the rigid body 110 can be passed. Firmly adsorbing the wafer 20 to the rigid body 110 not only eliminates the need for a bit ring to prevent the wafer from slipping out in the traditional grinding process, but also avoids the flattening of the wafer edge caused by the bit ring during the grinding process. degree of influence.

In addition, in the traditional grinding process, friction will occur between the body of the grinding head and the wafer during the grinding process, resulting in wear of the grinding head. However, in this application, the wafer is adsorbed on the rigid body during the grinding process. There is basically no relative movement between the wafer and the rigid body, so the wear of the wafer on the rigid body can be reduced, thereby reducing the manufacturing cost of semiconductor devices.

In specific implementation, the decompression device decompresses the cavity so that the pressure inside the cavity is smaller than the external pressure. When the pressure inside the cavity is small to a certain extent, it can pass through the first pass on the upper surface of the rigid body. The holes firmly adsorb the wafer to the rigid body.

For example, the pressure reducing device can reduce pressure by evacuating the cavity, and the pressure (or vacuum degree) of the cavity can be controlled by the pressure reducing device according to actual usage conditions, which is not limited here.

In this application, the rigid body can be formed of rigid material to ensure that the rigid body will not deform when the cavity in the rigid body is decompressed.

For example, in one embodiment, the rigid body can be formed of graphene, ceramics or organic materials, which can prevent the grinding table from causing damage to the wafer. Alternatively, in another embodiment, the upper surface of the rigid body can also be coated with graphene, ceramics or organic materials to avoid damage to the wafer caused by the grinding table.

Referring to Figure 4, Figure 4 is a schematic structural diagram of another rigid body in a grinding table provided by an embodiment of the present application. In the grinding table 100, the rigid body 110 may include a central rigid cavity portion 1100 located in the central area and a plurality of annular rigid cavity portions 1101˜110N arranged sequentially and outwardly along the central rigid cavity portion 1100 (Fig. 4 Taking N equal to 4 as an example for illustration), different rigid cavity parts can be decompressed to different degrees through the decompression device 120 (not shown in FIG. 4 ). For example, for a wafer with a curved edge, the pressure of different rigid cavity parts can be controlled before grinding to change the deformation of the wafer itself before grinding, so that the wafer can fit horizontally on the grinding table. This makes the polished wafer surface smoother.

It should be noted that the “central area” mentioned in this application refers to the central area in the plane, so the annular rigid cavity portion 110n (n is any number from 1 to N) is only in the central rigid cavity portion 1100 Sides (eg, annular sides in Figure 4) are provided around the central rigid cavity 1100.

For example, as shown in FIG. 5 , when the edge of the wafer 20 is bent upward, the pressure of the annular rigid cavity portion 110 n tends to decrease with the distance of the annular rigid cavity portion 110 n from the central rigid cavity portion 1100 . For example, the farther away the annular rigid cavity part 110n is from the central rigid cavity part 1100, the smaller the pressure of the annular rigid cavity part 110n. However, this application includes but is not limited to the pressure of several adjacent rigid cavity parts. Similarly, it is sufficient to ensure that the overall trend is that the pressure of the annular rigid cavity portion 110n near the edge is smaller than the pressure of the annular rigid cavity portion 110n near the center. The specific design needs to be based on the degree and range of bending of the wafer 20. Among them, the more arrows corresponding to the rigid cavity part in Figure 5, the smaller the pressure.

For example, as shown in FIG. 6 , when the edge of the wafer 20 is bent downward, the pressure of the annular rigid cavity portion 110n tends to increase with the distance of the annular rigid cavity portion 110n from the central rigid cavity portion 1100 . For example, the farther away the annular rigid cavity part 110n is from the central rigid cavity part 1100, the greater the pressure of the annular rigid cavity part 110n. However, this application includes but is not limited to the pressure of several adjacent rigid cavity parts. Similarly, as long as the overall trend is ensured that the pressure of the annular rigid cavity portion 110n near the edge is greater than the pressure of the annular rigid cavity portion 110n near the center, the specific design needs to be based on the degree and range of the wafer bending. Among them, the more arrows corresponding to the rigid cavity part in Figure 6, the smaller the pressure.

In this application, the rigid cavity portion may be composed of an upper surface, a lower surface and a cavity wall, wherein the central rigid cavity portion 1100 may include an upper surface 110a, a lower surface 110b and a boundary connecting the upper surface 110a and The outer cavity wall 110c is bounded by the lower surface 110b, thereby forming a cavity in the area surrounded by the upper surface 110a, the lower surface 110b and the outer cavity wall 110c. The annular rigid cavity portion 1100n may include an annular upper surface 110a, an annular lower surface 110b, an outer cavity wall 110c connecting the outer boundary of the upper surface 110a and the lower surface 110b, and an inner boundary connecting the upper surface 110a as shown in FIG. 8 and the inner cavity wall 110d on the inner boundary of the lower surface 110b, thereby forming an annular cavity in the area surrounded by the upper surface 110a, the lower surface 110b, the outer cavity wall 110c and the inner cavity wall 110d.

Adaptably, when the rigid body 110 includes a central rigid cavity portion 1100 and a plurality of annular rigid cavity portions 110n, the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n can be made of graphene, ceramic or organic materials. Alternatively, graphene, ceramic or organic materials may be coated on the upper surfaces of the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n.

It should be noted that the rigid cavity part mentioned in this application may be the central rigid cavity part 1100 or any annular rigid cavity part 110n.

In this application, the upper surface of the central rigid cavity portion 1100 can be a regular figure, such as an equilateral polygon, a circle as shown in FIG. 7, etc., and the shape of the boundary of the upper surface of each annular rigid cavity portion 110n is the same as the center. The upper surfaces of the rigid cavity portions 1100 have the same shape. For example, the upper surface of the central rigid cavity portion 1100 is circular as shown in FIG. 7 , and the boundaries of the upper surfaces of each annular rigid cavity portion 110n are also circular.

For example, in this application, as shown in Figure 4, the upper surface of the central rigid cavity portion 1100 is circular, and the upper surface of each annular rigid cavity portion 110n is annular, thereby ensuring that the grinding table 100 can be When rotating, with the center of the central rigid cavity portion 1100 as the center of the circle, the pressure received at the same distance from the center of the circle is uniform.

For example, in this application, the central rigid cavity part and the plurality of annular rigid cavity parts can be an integral structure, so that a central rigid cavity can be formed as long as a plurality of annular cavity walls are provided between the upper surface and the lower surface. The body portion and multiple annular rigid cavity portions, that is, adjacent rigid cavity portions, can share a cavity wall, thereby reducing the manufacturing difficulty of the grinding table.

Optionally, in this application, as shown in Figure 9, the grinding table 100 can also be provided with a pressure supply device 130 at the bottom of the rigid body 110. During grinding, the pressure supply device 130 can provide upward or downward pressure to the rigid body 110. pressure. Compared with the traditional polishing head that needs to provide pressure to the wafer by inflating, the pressure supply device 130 can provide more precise pressure control for the rigid body 110 .

It should be noted that this application does not limit the specific implementation of the pressure supply device 130. It may be any structure capable of providing upward or downward pressure to the rigid body 110. For example, the pressure supply device 130 may include at least one hydraulic telescopic cylinder. And a telescopic rod corresponding to the at least one hydraulic telescopic cylinder, wherein the telescopic rod connects the hydraulic telescopic cylinder and the rigid body; the hydraulic telescopic cylinder provides upward or downward pressure to the rigid body through the telescopic telescopic rod.

In order to improve the flatness of grinding, for example, as shown in FIG. 10 , the plurality of annular rigid cavity portions 1101 to 110N are sequentially nested outward from the central rigid cavity portion 1100 , that is, the first annular rigid cavity portion 1101 is placed outside the central rigid cavity part 1100, the second annular rigid cavity part 1102 is placed outside the first annular rigid cavity part 1101,... the Nth annular rigid cavity part 110N is placed outside the N-1 In addition to an annular rigid cavity portion 110N-1, in this way, any one of the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n can move along the direction of the central rigid cavity portion 1100 relative to the remaining rigid cavity portions. Move in axial direction Z. In this way, the pressure exerted on the bottom of each rigid cavity can be independently controlled during grinding, thereby improving the flatness of grinding. Moreover, compared with the problem of grinding rate at the junction caused by deformation of the traditional polishing head in different air bag areas, in this application, there is no deformation at the junction of each rigid cavity part, and the pressure acting on the wafer increases in each rigid cavity. The cavity parts and junctions are evenly distributed, thus providing better flatness.

Of course, during specific implementation, among the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n, one or multiple adjacent rigid cavity portions can also be used as a group, and the central rigid cavity portion can be 1100 and a plurality of annular rigid cavity portions 110n are divided into multiple groups, and the groups are nested. The groups can move relative to each other along the axial direction Z of the central rigid cavity portion 1100. The plurality of rigid cavity parts cannot move relative to each other, which is not limited here.

Optionally, when a plurality of annular rigid cavity portions 1101 to 110N are sequentially nested outward from the central rigid cavity portion 1100, as shown in Figure 11, the grinding table 100 may also include a first pressure supply device 131 and A plurality of second pressure supply devices 132 corresponding to the plurality of annular rigid cavity portions 110n; the plurality of second pressure supply devices 132 and the plurality of annular rigid cavity portions 110n have a one-to-one correspondence, that is, each second pressure The supply device 132 corresponds to one annular rigid cavity portion 110n, and each annular rigid cavity portion 110n also corresponds to only one second pressure supply device 132. The first pressure supply device 131 is located at the bottom of the central rigid cavity portion 1100 and is used to provide upward or downward pressure to the central rigid cavity portion 1100; each second pressure supply device 132 of the plurality of second pressure supply devices 132 They are respectively located at the bottom of the corresponding annular rigid cavity portion 110n and are used to provide upward or downward pressure to the corresponding annular rigid cavity portion 110n. Compared with the traditional polishing head that needs to provide pressure to the wafer by inflating, the first pressure supply device 131 and the second pressure supply device 132 can provide more precise pressure control for the corresponding rigid cavity portion.

It should be noted that this application does not limit the implementation of the first pressure supply device 131 and the second pressure supply device 132, and they may be any structure capable of providing upward or downward pressure.

For example, as shown in Figure 11, the first pressure supply device 131 may include a hydraulic telescopic cylinder 1311 and a telescopic rod 1312 connecting the hydraulic telescopic cylinder 1311 and the central rigid cavity portion 1100; the hydraulic telescopic cylinder 1311 is connected to the telescopic cylinder 1311 through the telescopic rod 1312 The central rigid cavity portion 1100 provides upward or downward pressure. Of course, during specific implementation, the first pressure supply device 131 may also include a plurality of hydraulic telescopic cylinders 1311 and telescopic rods 1312 corresponding to the plurality of hydraulic telescopic cylinders 1311, which is not limited here.

For example, as shown in Figure 11, the second pressure supply device 132 may include at least two hydraulic telescopic cylinders 1321 and telescopic rods 1322 corresponding to each hydraulic telescopic cylinder 1321; the hydraulic telescopic cylinder 1321 is connected to the corresponding telescopic cylinder through the corresponding telescopic rod 1322. The annular rigid cavity portion 110n is connected, and the hydraulic telescopic cylinder 1321 provides upward or downward pressure to the corresponding annular rigid cavity portion 110n by telescopically contracting the corresponding telescopic rod 1322.

For example, in order to ensure that the annular rigid cavity portion 110n is evenly stressed, the at least two hydraulic telescopic cylinders 1321 in the second pressure supply device 132 are evenly distributed.

Optionally, in this application, in order to reduce costs, the second pressure supply device 132 may include two hydraulic telescopic cylinders 1321 and two telescopic rods 1322.

In this application, the greater the number of annular rigid cavity portions 110n in the rigid body 110, the finer the pressure control at different positions during the grinding process. Optionally, the rigid body 110 may include at least 4 annular rigid cavity parts 110n, for example, 4 annular rigid cavity parts 110n, 5 annular rigid cavity parts 110n, 6 annular rigid cavity parts 110n, etc. .

This application does not limit the number of annular rigid cavity portions 110n, and can be determined based on actual conditions such as grinding effect and cost.

In specific implementation, the first via hole V1 may be provided on the upper surface of the central rigid cavity part 1100 , or the first via hole may be provided on the upper surface of at least one of the plurality of annular rigid cavity parts 110 n V1, of course, the first via hole V1 can also be provided on the upper surface of the central rigid cavity portion 1100 and at least one rigid cavity portion, which is not limited here. The second via hole V1 is provided at the bottom of the rigid cavity portion with the first via hole V1, that is, as long as the upper surface of the rigid cavity portion has the first via hole V1, the bottom of the rigid cavity portion will be provided with The second via hole V2 is used to depressurize the rigid cavity part through the second via hole V2, and the first via hole V1 is used to absorb the wafer.

Optionally, in this application, in order to increase the adsorption between the rigid cavity part and the wafer, a plurality of first via holes may be provided on the upper surface of the rigid cavity part.

Illustratively, in this application, as shown in FIG. 4 , the upper surface of each of the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n is provided with a plurality of first via holes V1 , and a second via hole V2 is provided at the bottom of each of the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n, so that each rigid cavity portion can absorb the wafer.

In this application, the plurality of first vias V1 provided in the same rigid cavity part are evenly distributed, which can ensure that the adsorption force of the same rigid cavity part to the wafer is evenly distributed.

For example, in this application, the plurality of first via holes V1 in each of the central rigid cavity portion 1100 and the plurality of annular rigid cavity portions 110n are evenly distributed.

This application also does not limit the number and shape of the air holes V in the same rigid cavity part, and the design can be based on the actual product.

Optionally, in this application, in order to improve the adsorption capacity, at least 4 first via holes V1 can be provided in the same rigid cavity part.

For example, in this application, each of the central rigid cavity portion and the plurality of annular rigid cavity portions is provided with at least 4 first via holes.

It should be noted that in this application, the number of first via holes in different rigid cavity parts may be the same or different. For example, the closer to the edge of the rigid cavity part, the greater the number of first via holes.

In this application, the shapes of the plurality of first via holes in the same rigid cavity part may be the same or different, and are not limited here. Optionally, multiple first via holes located in the same rigid cavity portion have the same shape, thereby ensuring the consistency of each first via hole in the multiple first via holes.

In this application, the shapes of the first via holes located in different rigid cavity parts may be the same or different, and are not limited here. Optionally, in this application, the shapes of the first via holes located in different rigid cavity parts are the same.

During specific implementation, the traditional grinding head has poor edge control effect on the wafer, and is prone to the problem of more edges being ground. Based on this, as shown in Figures 12 and 13, the grinding table of the present application also includes a surrounding rigid The body 110 is provided with an annular rigid groove 140 . In this way, when the wafer 20 is placed on the grinding table 100, the edge of the wafer 20 can be located on the annular rigid groove 140, that is, the bottom of the edge of the wafer 20 is suspended, thereby reducing the impact on the wafer 20 during grinding. The degree of grinding of the edges.

Optionally, in this application, a third via hole is also provided at the bottom of the annular rigid groove, and the decompression device 120 is also used to decompress the annular rigid groove 140 through the third via hole, for example, Tank 140 is evacuated. In this way, the annular rigid groove 140 can be decompressed by the decompression device 120, so that the edge of the wafer 20 can be deformed downward, and the distance between the edge of the wafer 20 and the polishing pad can be increased during polishing, thereby further reducing the distance between the edge of the wafer 20 and the polishing pad. The degree of grinding of the edge of the wafer 20 can even avoid grinding the edge of the wafer 20 .

This application does not limit the diameter width of the central rigid cavity portion 1100, the annular width of the annular rigid cavity portion 110n, and the width of the annular rigid groove 140, and can be designed according to specific actual products.

In addition, it should be noted that this application does not limit the implementation of the pressure reducing device, as long as it can make the pressure in the cavity much smaller than the external pressure, for example, it can be a vacuum device.

For example, as shown in FIG. 11 , the pressure reducing device 120 may include a first vacuum valve 121 disposed at the bottom of a rigid cavity portion having a second through hole (not shown in the figure), and The first vacuum valve 121 is connected to the second via hole.

Further, in this application, a third via hole is provided at the bottom of the annular rigid groove, as shown in FIG. 12 . The pressure reducing device 120 also includes a third via hole located at the bottom of the annular rigid groove 140 and connected to the third via hole (in the figure). (not shown) communicates with the second vacuum valve 122 .

Referring to Figures 14 and 15, Figure 14 is a schematic structural diagram of a grinding head provided by an embodiment of the present application, and Figure 15 is a schematic structural diagram of another grinding head provided by an embodiment of the present application. The grinding head 10 may include a rotating part 200 and a grinding table 100 fixed on the rotating part 200 . The rotating part 200 is configured to carry the grinding table 100 and rotate the grinding table 100 with the rotating part 200 .

It should be noted that the grinding table in the grinding head in this application can be the structure provided in any of the above embodiments of this application. The main difference between Figure 14 and Figure 15 is that the grinding table of the grinding head shown in Figure 14 does not include an annular rigid groove, while the grinding head shown in Figure 15 is provided with an annular rigid groove in the grinding table. The specific implementation of other components of the grinding table in the grinding head, such as the rigid body, pressure reducing device, pressure control device, first pressure control device, second pressure control device, etc., may be at least partially the same or may be different.

In a possible embodiment, as shown in FIGS. 14 and 15 , the rotating part 200 may include a bearing part 210 and a rotating motor 220 . The bearing part 210 is used to carry and install the grinding table 100; the rotation motor 220 is located below the bearing part 210 and is used to drive the bearing part 220 to rotate, and the grinding head 100 installed on the bearing part 210 can rotate with the bearing part 220.

This application does not limit the specific implementation of the carrying part 210, and it may be any structure that can implement the solution of this application.

Referring to Figure 16, Figure 16 is a schematic structural diagram of a grinding equipment provided by an embodiment of the present application. As shown in Figure 16, the grinding equipment includes a rotating disk 30 and any one of the grinding heads 10 provided in the above embodiments. The rotating disk 30 is configured to be located above the grinding head 10 during grinding, and the wafer 20 is clamped by the grinding head 10. Between the rotating disc 30 and the rotating disc 30, a polishing pad 31 is attached to the side of the rotating disc 30 facing the polishing head 10. The rotating polishing head 10 and the rotating polishing pad 31 cause relative movement between the front surface of the wafer 20 and the polishing pad 31 to generate friction, thereby planarizing the front surface of the wafer 20 . The other essential components of the grinding equipment are all understood by those of ordinary skill in the art, and will not be described in detail here, nor should they be used to limit the present application. The implementation of the grinding equipment can refer to the above embodiments, and repeated details will not be described again.

Correspondingly, this application also provides a grinding method using the above-mentioned grinding equipment for grinding. As shown in Figure 17, the grinding method may include the following steps:

Step S101: Place the wafer on the grinding table of the grinding head.

In specific implementation, when the grinding table includes a first pressure supply device and a plurality of second pressure supply devices, the grinding head also has the function of receiving the wafer. When the robot arm brings the wafer to the top of the grinding head, the grinding head The rigid cavity portion with the first via hole on the upper surface moves upward to receive the wafer, and then the robot arm moves away, and the rigid cavity portion drives the wafer to fall onto the grinding head. Among them, the upwardly moving rigid cavity portion can be any rigid cavity portion with a first through hole on the upper surface among the central rigid cavity portion and the plurality of annular rigid cavity portions. The details can be determined according to the actual use conditions and will not be discussed here. limited. In practical applications, for example, to prevent the robot arm from touching the upward-moving rigid cavity, a rigid cavity near the center is generally selected, such as a central rigid cavity, which is not limited here.

Therefore, optionally, before placing the wafer on the grinding table of the grinding head in step S101, as shown in FIG. 18, the first pressure supply device 131 is controlled to provide upward pressure to the central rigid cavity portion 1100 to make the central rigid cavity The cavity part 1100 moves upward relative to the plurality of annular rigid cavity parts 110n; then the wafer 20 is placed on the central rigid cavity part 1100, and the decompression device (not shown in the figure) is controlled to align with the central rigid cavity part 1100 The pressure is reduced so that the wafer 20 is adsorbed on the central rigid cavity part 1100; then the first pressure supply device 131 is controlled to provide downward pressure to the central rigid cavity part 1100, so that the central rigid cavity part 1100 moves to the upper surface and The upper surfaces of the plurality of annular rigid cavity portions 110n are located on the same plane.

Step S102: Control the decompression device to depressurize the cavity of the rigid body so that the pressure inside the cavity is much smaller than the external pressure.

Optionally, when the grinding table includes a central rigid cavity part and a plurality of annular rigid cavity parts, controlling the decompression device to decompress the cavity of the rigid body includes: controlling the decompression device to decompress the cavity according to the edge curvature of the wafer. The central rigid cavity portion and the plurality of annular rigid cavity portions are depressurized to control the pressure of each of the central rigid cavity portion and the plurality of annular rigid cavity portions. Therefore, before grinding, the pressure of different rigid cavity parts can be controlled to change the deformation of the wafer itself before grinding, so that the wafer can be horizontally attached to the grinding table, thereby making the surface of the polished wafer smoother. .

As shown in FIG. 5 , when the edge of the wafer 20 is bent upward, the pressure of the rigid cavity portion tends to decrease with the distance of the rigid cavity portion from the axis of the central rigid cavity portion 1100 . For example, the farther the annular rigid cavity portion 110n is from the axis of the central rigid cavity portion 1100, the smaller the pressure of the annular rigid cavity portion 110n. However, this application includes but is not limited to several adjacent rigid cavity portions. The pressure is the same, as long as the overall trend is ensured that the pressure of the annular rigid cavity portion 110n near the edge is less than the pressure of the annular rigid cavity portion 110n near the center, the specific design needs to be based on the degree and range of bending of the wafer 20 .

As shown in FIG. 6 , when the edge of the wafer 20 is bent downward, the pressure of the annular rigid cavity portion 110 n increases with the distance of the annular rigid cavity portion 110 n from the central rigid cavity portion 1100 . For example, the farther away the annular rigid cavity part 110n is from the central rigid cavity part 1100, the greater the pressure of the annular rigid cavity part 110n. However, this application includes but is not limited to the pressure of several adjacent rigid cavity parts. Similarly, as long as the overall trend is ensured that the pressure of the annular rigid cavity portion 110n near the edge is greater than the pressure of the annular rigid cavity portion 110n near the center, the specific design needs to be based on the degree and range of the wafer bending.

Step S103: Control the rotating disk to be positioned on the wafer so that the polishing pad on the rotating disk is in contact with the wafer.

Step S104: Control the grinding table and the rotating disk to rotate to planarize the wafer.

As shown in FIG. 19 , during the grinding process, the grinding table 100 and the rotating disc 30 rotate. In order to increase the relative motion and thereby increase the friction force, the rotating disc 30 also swings back and forth while rotating.

Optionally, when the grinding table includes a pressure supply device located at the bottom of the rigid body, the pressure supply device can also be controlled to provide upward pressure to the rigid body. Compared with traditional grinding heads that require inflating to provide pressure on the wafer, the pressure supply device can provide more precise pressure control on the rigid body.

For example, when the grinding table includes a first pressure supply device and a plurality of second pressure supply devices, the first pressure supply device and the plurality of second pressure supply devices are respectively controlled to provide upward pressure to the corresponding rigid cavity portion. In this way, the pressure exerted on the bottom of each rigid cavity can be independently controlled during grinding, thereby improving the flatness of grinding. Moreover, compared with the problem of grinding rate at the junction caused by deformation of the traditional polishing head in different air bag areas, in this application, there is no deformation at the junction of each rigid cavity part, and the pressure acting on the wafer increases in each rigid cavity. The cavity parts and junctions are evenly distributed, thus providing better flatness.

In specific implementation, the traditional grinding head has poor control effect on the edge of the wafer, and is prone to the problem of more edges being ground. Therefore, optionally, in this application, when the grinding table also includes a When the annular rigid groove is provided with a third via hole at the bottom, the decompression device can also be controlled to decompress the annular rigid groove. In this way, the annular rigid groove can be decompressed by the decompression device, which can deform the wafer edge downward, thereby increasing the distance between the wafer edge and the polishing pad during polishing, thereby reducing the impact on the wafer. The degree of edge grinding can even avoid grinding the wafer edge.

Optionally, in this application, after the wafer is planarized, the decompression device can also be controlled to stop decompressing the plurality of annular rigid cavity parts; the first pressure supply device can be controlled to depressurize the central rigid cavity part. Provide upward pressure to move the central rigid cavity portion upward relative to the plurality of annular rigid cavity portions; control the decompression device to stop decompressing the central annular rigid cavity portion to facilitate removal of the wafer.

According to the technical solution of this application, the grinding table can firmly adsorb the wafer to the grinding table during grinding, which not only eliminates the need for the bit ring used to prevent the wafer from slipping out in the traditional grinding process, but also avoids the need for The impact of bit rings on wafer edge flatness. Moreover, during the grinding process, the wafer is adsorbed on the grinding table, and there is basically no relative movement between the wafer and the grinding table. Therefore, the wear of the wafer on the grinding table can be reduced, thereby reducing the manufacturing cost of semiconductor devices.

In addition, when the grinding table includes a central rigid cavity part and multiple annular rigid cavity parts, for wafers with curved edges, the pressure of different rigid cavity parts can be controlled before grinding to change the wafer itself before grinding. The resulting deformation allows the wafer to fit horizontally on the grinding table, making the polished wafer surface smoother.

Furthermore, this application can independently control the pressure applied to the bottom of each rigid cavity during grinding. Compared with the problem of grinding rate at the junction of different air bag areas due to deformation of the traditional grinding head, in this application There is no deformation at the junction of each rigid cavity part, and the pressure acting on the wafer is evenly distributed in each rigid cavity part and the junction, so it can bring better flatness. Moreover, compared with the traditional polishing head that needs to provide pressure to the wafer by inflating, the pressure supply device can provide more precise pressure control.

When the grinding table of the present application also includes an annular rigid groove, when the wafer is placed on the grinding table, the edge of the wafer can be located on the annular rigid groove, thereby reducing the impact on the edge of the wafer during grinding. Degree of grinding. When the annular rigid groove is decompressed, the edge of the wafer can also be deformed downward, thereby increasing the distance between the edge of the wafer and the polishing pad, thereby further reducing the degree of polishing of the edge of the wafer, and even Grinding of wafer edges can be avoided.

If necessary, the grinding head applied by our bank can be designed according to the production needs, including the number of rigid cavities in the grinding table, the number of pores in the rigid cavity, the shape of the pores, and the arrangement of the pores. Compared with traditional grinding heads, they are more flexible and versatile. For example, to adjust the number of pressure zones, traditional grinding heads require corresponding modifications to the air path of the entire machine. In this application, only the rigid cavity and pressure need to be changed. control device without the need to make major modifications to the entire machine.

Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the protection scope of the present application. In this way, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies, the present application is also intended to include these modifications and variations.

Claims (24)

A grinding table, which is characterized in that it includes: A rigid body for carrying the wafer, and the rigid body has a cavity; A plurality of first via holes penetrating from the cavity to the upper surface of the rigid body; a second via hole penetrating from the cavity to the bottom of the rigid body; A decompression device located at the bottom of the rigid body, the decompression device is used to depressurize the cavity through the second through hole. The grinding table of claim 1, wherein the rigid body has: a central rigid cavity portion located in the central region; A plurality of annular rigid cavity portions arranged sequentially outward along the central rigid cavity portion; The plurality of first via holes and the second via hole are located in at least one rigid cavity portion of the central rigid cavity portion and the plurality of annular rigid cavity portions. The grinding table according to claim 2, wherein the central rigid cavity portion and the plurality of annular rigid cavity portions are an integral structure. The grinding table according to claim 2, wherein the plurality of annular rigid cavity portions are sequentially nested outward from the central rigid cavity portion. The grinding table according to any one of claims 1 to 3, characterized in that the grinding table further includes a pressure supply device located at the bottom of the rigid body, and the pressure supply device is used to provide upward pressure to the rigid body. or downward pressure. The grinding table according to claim 4, wherein the grinding table further includes a first pressure supply device and a plurality of second pressure supply devices corresponding to the plurality of annular rigid cavity portions; The first pressure supply device is located at the bottom of the central rigid cavity portion and is used to provide upward or downward pressure to the central rigid cavity portion; The plurality of second pressure supply devices have a one-to-one correspondence with the plurality of annular rigid cavity portions, and each second pressure supply device in the plurality of second pressure supply devices is located at the corresponding said The bottom of the annular rigid cavity portion is used to provide upward or downward pressure to the corresponding annular rigid cavity portion. The grinding table according to claim 6, wherein the first pressure supply device includes a hydraulic telescopic cylinder and a telescopic rod connecting the hydraulic telescopic cylinder and the central rigid cavity portion; The hydraulic telescopic cylinder provides upward or downward pressure to the central rigid cavity portion by telescopically contracting the telescopic rod. The grinding table according to claim 6, wherein the second pressure supply device includes at least two hydraulic telescopic cylinders and a telescopic rod corresponding to each of the at least two hydraulic telescopic cylinders; The hydraulic telescopic cylinder is connected to the corresponding annular rigid cavity part through the corresponding telescopic rod, and the hydraulic telescopic cylinder provides upward or downward pressure to the corresponding annular rigid cavity part by telescopically contracting the corresponding telescopic rod. downward pressure. The grinding table according to claim 8, wherein the at least two hydraulic telescopic cylinders in the second pressure supply device are evenly distributed. The grinding table according to any one of claims 2-4 and 6-9, wherein the pressure reducing device includes a pressure reducing device located at the bottom of the rigid cavity portion with the second through hole and connected with the second via hole. The second via hole is connected to the first vacuum valve. The grinding table according to any one of claims 1 to 10, wherein the grinding table further includes an annular rigid groove arranged around the rigid body. The grinding table according to claim 11, characterized in that a third via hole is provided at the bottom of the annular rigid groove, and the pressure reducing device is further used to adjust the annular rigid groove through the third via hole. Grooves for pressure relief. The grinding table of claim 12, wherein the pressure reducing device further includes a second vacuum valve located at the bottom of the annular rigid groove and connected to the third via hole. The grinding table according to any one of claims 1 to 13, wherein the pressure reducing device is used to reduce pressure by evacuating the cavity. A grinding head, characterized in that it includes a rotating part and a grinding table according to any one of claims 1 to 14 fixed on the rotating part, the rotating part is configured to carry the grinding table and make the grinding table The grinding table rotates with the rotating part. The grinding head according to claim 15, wherein the rotating part includes a bearing part and a rotating motor; The carrying part is used to carry and install the grinding table; The rotation motor is located below the bearing part and used to drive the bearing part to rotate. A grinding equipment, characterized in that it includes a rotating disc and a grinding head according to claim 15 or 16, the rotating disc is configured to be located above the grinding head during grinding, and the rotating disc faces the grinding head. There is a grinding pad attached to one side of the grinding head. A grinding method using the grinding equipment of claim 17, wherein the grinding method includes: Place the wafer on the grinding table of the grinding head; Control the pressure reducing device to depressurize the cavity of the rigid body; Control the rotating disk to be positioned on the wafer so that the polishing pad on the rotating disk is in contact with the wafer; The grinding table and the rotating disk are controlled to rotate to planarize the wafer. The grinding method according to claim 18, characterized in that when the grinding table includes the central rigid cavity part and the plurality of annular rigid cavity parts, the control of the pressure reducing device to the Depressurization of rigid body cavities includes: The decompression device is controlled to decompress the central rigid cavity portion and the plurality of annular rigid cavity portions according to the edge curvature of the wafer to control the central rigid cavity portion and the multiple annular rigid cavity portions. The pressure of each of the rigid cavity parts in an annular rigid cavity part; where: When the edge of the wafer is bent upward, the pressure of the rigid cavity portion shows a decreasing trend with the distance of the rigid cavity portion from the axis of the central rigid cavity portion; When the edge of the wafer is bent downward, the pressure of the rigid cavity portion tends to increase with the distance of the rigid cavity portion from the axis of the central rigid cavity portion. The grinding method according to claim 18 or 19, wherein the grinding table further includes an annular rigid groove provided around the rigid body, and a third pass is provided at the bottom of the annular rigid groove. hole, when controlling the grinding table and the rotating disk to rotate, it also includes: The decompression device is controlled to decompress the annular rigid groove. The grinding method according to any one of claims 18 to 20, wherein when the grinding table includes the pressure supply device located at the bottom of the rigid body, when the grinding table is controlled and the pressure supply device is located at the bottom of the rigid body, When the carousel rotates, it also includes: The pressure supply device is controlled to provide upward pressure to the rigid body. The grinding method according to any one of claims 18 to 20, characterized in that when the grinding table includes the first pressure supply device and the plurality of second pressure supply devices, when the control of the When the grinding table and the rotating disc rotate, they also include: The first pressure supply device and the plurality of second pressure supply devices are respectively controlled to provide upward pressure to the corresponding rigid cavity portion. The grinding method according to claim 22, characterized in that, before placing the wafer on the grinding table of the grinding head, it further includes: Controlling the first pressure supply device to provide upward pressure to the central rigid cavity portion so that the central rigid cavity portion moves upward relative to the plurality of annular rigid cavity portions; Place the wafer on the central rigid cavity part, and control the decompression device to depressurize the central rigid cavity part so that the wafer is adsorbed on the central rigid cavity part ; The first pressure supply device is controlled to provide downward pressure to the central rigid cavity portion, so that the central rigid cavity portion moves to a position where the upper surface is on the same plane as the upper surfaces of the plurality of annular rigid cavity portions. The grinding method according to claim 23, characterized in that, after planarizing the wafer, it further includes: Control the decompression device to stop decompressing the plurality of annular rigid cavity parts; Controlling the first pressure supply device to provide upward pressure to the central rigid cavity portion so that the central rigid cavity portion moves upward relative to the plurality of annular rigid cavity portions; The decompression device is controlled to stop decompressing the central annular rigid cavity portion.

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