CMP PAD AND CMP EQUIPMENT

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Chinese patent application No. 202410979567.1, filed on Jul. 19, 2024, the disclosure of which is incorporated herein by reference in its entirety.

TECHNICAL FILED

The application relates to semiconductor integrated circuit manufacturing equipment, in particular to a chemical mechanical polishing (CMP) pad. The application also relates to CMP equipment.

BACKGROUND

The continuous shrinking of advanced process nodes in semiconductor manufacturing has resulted in an increasingly narrow process window. The introduction and exploration of “advanced weapons” for process window expansion play an important pole in the improvement of device performance. A full vision next generation (FVXE) assembly achieves the effect of in-situ adjustment of the profile of a wafer by optically monitoring the wafer profile in real time while using a multi-pressure controller (MPC), and can be called a real time process controller (RTPC) of a non-metallic layer. The FVXE assembly needs to be paired with a triple-window (3 window) pad to ensure, by means of a triple window, that an optical path passes through a platen corresponding to the pad and is incident on the wafer to achieve the purpose of real-time improvement of uniformity (NU).

However, during a test, it is found that a polishing rate of the wafer has a “jump” within +/−30 mm, and this “jump” is difficult to improve through pressure adjustment because it only accounts for a part of a pressure adjustment zone that one polishing head can adjust.

BRIEF SUMMARY

According to some embodiments in this application, a CMP pad provided by the application comprises:

• • a first surface and a second surface opposite to each other, the first surface being a polishing surface and being circular; and
  • a plurality of monitor windows, each of the monitor windows penetrating through the first surface and the second surface, each of the monitor windows being uniformly distributed on a first circle, a first annular region centered on the first circle being a monitor window influence zone, the monitor windows causing an increase in a brush rate of a slurry in the monitor window influence zone.

The first surface is provided thereon with a groove pattern structure which is used to adjust a brush rate of a slurry on the first surface and causes a decrease in the brush rate of the slurry in the monitor window influence zone to compensate for the influence of the monitor windows on the increase in the brush rate of the slurry in the monitor window influence zone.

In some cases, the groove pattern structure comprises a plurality of concentric circular grooves.

In a radius direction along the first surface, the circular grooves are isolation structures which are not connected to each other, and the isolation structures serve as structures that cause a decrease in the brush rate of the slurry in the monitor window influence zone.

In some cases, the width of the monitor window influence zone is less than the diameter of a central pressure adjustment zone of a polishing head.

In some cases, the width of the monitor window influence zone is less than or equal to 60 mm.

In some cases, the monitor windows are connected to a light emitting apparatus and a spectrograph of an FVXE assembly through optical fibers.

In some cases, the number of the monitor windows is 3.

In some cases, the first circle is located in one of the circular grooves.

In some cases, a polishing object of the pad is a non-metallic layer, and the FVXE assembly is used to monitor the profile of the non-metallic layer in real time.

According to some embodiments in this application, a CMP equipment provided by the application comprises: a pad. The pad comprises:

• • a first surface and a second surface opposite to each other, the first surface being a polishing surface and being circular; and
  • a plurality of monitor windows, each of the monitor windows penetrating through the first surface and the second surface, each of the monitor windows being uniformly distributed on a first circle, a first annular region centered on the first circle being a monitor window influence zone, the monitor windows causing an increase in a brush rate of a slurry in the monitor window influence zone.

The first surface is provided thereon with a groove pattern structure which is used to adjust a brush rate of a slurry on the first surface and causes a decrease in the brush rate of the slurry in the monitor window influence zone to compensate for the influence of the monitor windows on the increase in the brush rate of the slurry in the monitor window influence zone.

The second surface of the pad is arranged on a polishing table.

A polishing head is disposed above the first surface of the pad, which is used to fix a polished member and press a polished surface of the polished member against the first surface.

In some cases, the groove pattern structure comprises a plurality of concentric circular grooves.

In a radius direction along the first surface, the circular grooves are isolation structures which are not connected to each other, and the isolation structures serve as structures that cause a decrease in the brush rate of the slurry in the monitor window influence zone.

In some cases, the polishing head is divided into a plurality of pressure adjustment zones, and the pressure of each of the pressure adjustment zones is adjusted by a multi-pressure controller.

The width of the monitor window influence zone is less than the diameter of a central pressure adjustment zone of the polishing head.

In some cases, the width of the monitor window influence zone is less than or equal to 60 mm.

In some cases, the CMP equipment further comprises an FVXE assembly, and the monitor windows are connected to a light emitting apparatus and a spectrograph of the FVXE assembly through optical fibers.

In some cases, the number of the monitor windows is 3.

In some cases, the first circle is located in one of the circular grooves.

In some cases, a polishing object of the pad is a non-metallic layer formed on the polished member, and the FVXE assembly is used to monitor the profile of the non-metallic layer in real time.

The CMP pad of the application is provided thereon with monitor windows, and the monitor windows will cause the roughness of regions of the monitor windows to change and thus be different from the roughness of regions which are not affected by the monitor windows, thereby affecting the uniformity of the polishing rate. To this end, the application also makes particular settings for the groove pattern structure on the first surface of the pad, and in particular sets the groove pattern structure according to the requirements for the adjustment of the brush rate of the slurry on the first surface, which can cause a decrease in the brush rate of the slurry in the monitor window influence zone to compensate for the influence of the monitor windows on the increase in the brush rate of the slurry in the monitor window influence zone. In this way, the polishing rate of the monitor window influence zone can be well controlled to prevent the polishing rate of the monitor window influence zone from jumping. Finally, polishing uniformity can be improved, and both wafer to wafer (WTW) uniformity and with in wafer (WIW) uniformity can be improved.

In the application, after monitor windows are provided on the pad, the connection to the FVXE assembly can be realized through optical fibers, and the FVXE assembly can optically monitor the profile of the polishing object in real time and realize real-time adjustment of a polishing process, for example, using a multi-pressure controller at the same time to realize real-time adjustment of the profile of the polishing object, thereby improving the uniformity of the profile of the polishing object.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The application will be further described in detail below in conjunction with the accompanying drawings and the detailed description of the application:

FIG. 1 is a schematic view of the structure of existing CMP equipment;

FIG. 2 is a top view of the existing CMP equipment shown in FIG. 1;

FIG. 3 is a schematic view of the structure of a polishing surface of a pad of the existing CMP equipment;

FIG. 4 is a schematic view of a polishing rate jump distribution region within a wafer when polishing is performed by using the pad of the existing CMP equipment shown in FIG. 3;

FIG. 5A is a schematic view of the structure of a polishing surface of a CMP pad of an embodiment of the application;

FIG. 5B is a schematic view of the cross-section structure of the CMP pad of an embodiment of the application along a dotted line AA in FIG. 5A;

FIG. 6 is a schematic view of the structure of CMP equipment of an embodiment of the application;

FIG. 7 is a top view of the CMP equipment of an embodiment of the application shown in FIG. 6; and

FIG. 8 is a schematic view of a monitor window influence zone in the wafer when polishing is performed by using the pad of the existing CMP equipment shown in FIG. 6.

DETAILED DESCRIPTION OF THE APPLICATION

An existing CMP pad is obtained through a detailed analysis on the basis of the technical problem of the existing CMP pad. Before introducing the existing CMP pad in detail, the following description is first given for the existing CMP pad.

FIG. 1 is a schematic view of the structure of existing CMP equipment. FIG. 2 is a top view of the existing CMP equipment shown in FIG. 1. The existing CMP equipment comprises: a pad 201.

As shown in FIG. 3, the pad 201 comprises:

• • a first surface and a second surface opposite to each other, wherein the first surface is a polishing surface and is circular, and a surface shown in FIG. 3 is the first surface; and
  • a plurality of monitor windows 202, wherein each of the monitor windows 202 penetrates through the first surface and the second surface, and each of the monitor windows 202 is uniformly distributed on a first circle 203. In the triple-window pad, the number of the monitor windows 202 is 3.

The second surface of the pad 201 is arranged on a polishing table 102.

A polishing head 108 is disposed above the first surface of the pad 201, which is used to fix a polished member 101 and press a polished surface of the polished member 101 against the first surface. The polished member 101 is usually a wafer.

The monitor windows 202 are connected to a light emitting apparatus 106 and a spectrograph 105 of an FVXE assembly 104 through optical fibers 107.

A polishing object of the pad 201 is a non-metallic layer, i.e., a non-metallic layer located on the polished member 101. The FVXE assembly 104 is used to monitor the profile of the non-metallic layer in real time.

As shown in FIG. 1, the bottom of the polishing table 102 is connected to a rotating shaft 103. During a polishing process, the rotating shaft 103 drives the entire polishing table 102 to rotate, and the rotation is indicated by a rotating arrow line in FIG. 1. In FIG. 1, the FVXE assembly 104 is disposed in a space at the bottom of the polishing table 102. A power supply or signal line of the FVXE assembly 104 is led outward along the rotating shaft 103.

A plurality of circular grooves 204 and a plurality of longitudinal grooves 205 are provided on the first surface. The longitudinal grooves 205 are used to connect the circular grooves 204 along a radius direction. During the polishing process, a slurry (not shown) moves along the first surface of the pad 201 under the action of a centrifugal force generated by the rotation of the polishing table 102 and forms a uniformly distributed structure, and the longitudinal grooves 205 increase the flow of the slurry between the circular grooves 204 along the radius direction.

During a test, it is found that a polishing rate of a wafer has a “jump” within +/−30 mm, and this “jump” is difficult to improve through pressure adjustment because it only accounts for a part of a pressure adjustment zone that one polishing head can adjust. FIG. 4 is a schematic view of a polishing rate jump distribution region within the wafer when polishing is performed by using the pad of the existing CMP equipment shown in FIG. 3. A polishing rate of a region indicated by a dotted circle 101b will jump, that is, the polishing rate of the region indicated by the dotted circle 101b will be higher than a polishing rate outside the region indicated by the dotted circle 101b.

In the prior art, the polishing head 108 is usually divided into a plurality of pressure adjustment zones, and the pressure of each pressure adjustment zone is independently adjusted by a multi-pressure controller, thereby adjusting a polishing rate of each pressure adjustment zone. However, a dotted circle 101a in FIG. 4 shows that the range of a region corresponding to a central pressure adjustment zone of the polishing head 108 is greater than the range of the region indicated by the dotted circle 101b, so that the polishing rate of the region indicated by the dotted circle 101b is improved through pressure adjustment, because adjusting the pressure of the central pressure adjustment zone alone will also affect a polishing rate of an annular region between the dotted circles 101a and 101b, finally resulting in the uniformity of the polishing rate still not meeting the requirements. In FIG. 4, the range of a region indicated by the dotted circle 101a is a circular region with a radius of r1, and the range of the region indicated by the dotted circle 101b is a circular region with a radius of r2. It can be seen that r1 is larger than r2. In the prior art, r1 is usually 40 mm, and r2 is 30 mm.

FIG. 5A is a schematic view of the structure of a polishing surface of a CMP pad 301 of an embodiment of the application. FIG. 5B is a schematic view of the cross-section structure of the CMP pad 301 of an embodiment of the application along a dotted line AA in FIG. 5A. The CMP pad 301 of an embodiment of the application comprises:

• • a first surface and a second surface opposite to each other, wherein the first surface is a polishing surface and is circular, a surface shown in FIG. 5A is the first surface, corresponding to a front surface in FIG. 5B, and the second surface corresponds to a back surface in FIG. 5B; and
  • a plurality of monitor windows 302, wherein each of the monitor windows 302 penetrates through the first surface and the second surface, each of the monitor windows 302 is uniformly distributed on a first circle 304, a first annular region centered on the first circle 304 is a monitor window influence zone, and the monitor windows 302 cause an increase in a brush rate of a slurry in the monitor window influence zone.

In an embodiment of the application, the first circle 304 is shown with reference to a dotted circle in FIG. 7. The circular grooves 303 are omitted in FIG. 7.

In some embodiments, the number of the monitor windows is 3.

Also referring to FIG. 7, a polished member 401 is usually a wafer. The monitor windows 302 need to monitor the thickness of the polished member 401 during the polishing process. Therefore, the polished member 401 needs to be placed on the first circle 304. When the pad 301 rotates, an annular region centered on the first circle 304 will polish the polished member 401, and the polished member 401 will also rotate with a polishing head 408. After being mapped onto the polished member 401, the monitor window influence zone corresponds to a region indicated by a dotted circle 401b with a radius of r102 in FIG. 8.

The first surface is provided thereon with a groove pattern structure. The groove pattern structure is used to adjust a brush rate of a slurry on the first surface, and causes a decrease in the brush rate of the slurry in the monitor window influence zone to compensate for the influence of the monitor windows 302 on the increase in the brush rate of the slurry in the monitor window influence zone.

In an embodiment of the application, as shown in FIG. 5A, the groove pattern structure comprises a plurality of concentric circular grooves 303. In a radius direction along the first surface, the circular grooves 303 are isolation structures which are not connected to each other. The isolation structures serve as structures that cause a decrease in the brush rate of the slurry in the monitor window influence zone.

In an embodiment of the application, the first circle 304 is located in one of the circular grooves 303.

The cross-section structures of the circular grooves 303 and the monitor windows 302 are shown with reference to FIG. 5B. It can be seen that near the monitor windows 302, the roughness of the first surface is different from that of other regions, so there will be an increased influence on the brush rate of the slurry, which will have an increased influence on a polishing rate of a region near the monitor windows 302, i.e., the monitor window influence zone.

Moreover, in an embodiment of the application, the circular grooves 303 are not connected to each other, so the slurry will not flow between the circular grooves 303 of different radii through the longitudinal grooves. Therefore, a brush rate of a slurry in each region will decrease, and the brush rate of the slurry in the monitor window influence zone will also decrease, so as to compensate for the influence on the increase in the brush rate of the slurry brought about by the monitor windows 302 themselves.

In an embodiment of the application, the width of the monitor window influence zone is less than the diameter of a central pressure adjustment zone of the polishing head 408. The structure of the polishing head 408 is shown with reference also to FIG. 6. The polishing head 408 is usually divided into a plurality of pressure adjustment zones, and the pressure of each pressure adjustment zone is adjusted independently by a multi-pressure controller so as to adjust a polishing rate of each pressure adjustment zone. As shown in FIG. 8, a dotted circle 401a shows that the central pressure adjustment zone of the polishing head 408 acts on a region on the polished member 401, and the two are in one-to-one correspondence. It can be seen that a region indicated by the dotted circle 401a is not equal to the region indicated by the dotted circle 401b, and the region indicated by the dotted circle 401a is larger than the region indicated by the dotted circle 401b. In this way, if only a polishing rate of the region indicated by the dotted circle 401b produces a jump, then the pressure of the central pressure adjustment zone cannot be adjusted to decrease the polishing rate of the region indicated by the dotted circle 401b, because adjusting the pressure of the central pressure adjustment zone alone will also affect a polishing rate of an annular region between the dotted circles 401a and 401b, finally resulting in the uniformity of the polishing rate still not meeting the requirements.

In some embodiments, the width of the monitor window influence zone is less than or equal to 60 mm, corresponding to r102 of 30 mm in FIG. 8. The radius of the central pressure adjustment zone of the polishing head 408, i.e., r101, is 40 mm.

In an embodiment of the application, also referring to FIG. 6, the monitor windows 302 are connected to a light emitting apparatus 406 and a spectrograph 405 of an FVXE assembly 404 through optical fibers 407.

A polishing object of the pad 301 is a non-metallic layer. The FVXE assembly 404 is used to monitor the profile of the non-metallic layer in real time.

The CMP pad 301 of an embodiment of the application is provided thereon with monitor windows 302, and the monitor windows 302 will cause the roughness of regions of the monitor windows 302 to change and thus be different from the roughness of regions which are not affected by the monitor windows 302, thereby affecting the uniformity of the polishing rate. To this end, the application also makes particular settings for the groove pattern structure on the first surface of the pad 301, and in particular sets the groove pattern structure according to the requirements for the adjustment of the brush rate of the slurry on the first surface, which can cause a decrease in the brush rate of the slurry in the monitor window influence zone 401b to compensate for the influence of the monitor windows 302 on the increase in the brush rate of the slurry in the monitor window influence zone 401b. In this way, the polishing rate of the monitor window influence zone 401b can be well controlled to prevent the polishing rate of the monitor window influence zone 401b from jumping. Finally, polishing uniformity can be improved, and both wafer to wafer (WTW) uniformity and with in wafer (WIW) uniformity can be improved.

In an embodiment of the application, after the monitor windows 302 are provided on the pad 301, the connection to the FVXE assembly 404 can be realized through optical fibers 407, and the FVXE assembly 404 can optically monitor the profile of the polishing object in real time and realize real-time adjustment of the polishing process, for example, using a multi-pressure controller at the same time to realize real-time adjustment of the profile of the polishing object, thereby improving the uniformity of the profile of the polishing object.

FIG. 6 is a schematic view of the structure of CMP equipment of an embodiment of the application. FIG. 7 is a top view of the CMP equipment of an embodiment of the application shown in FIG. 6. The CMP equipment of an embodiment of the application comprises: a pad 301.

As shown in FIG. 5A, the pad 301 comprises:

• • a first surface and a second surface opposite to each other, wherein the first surface is a polishing surface and is circular, a surface shown in FIG. 5A is the first surface, corresponding to a front surface in FIG. 5B, and the second surface corresponds to a back surface in FIG. 5B; and
  • a plurality of monitor windows 302, wherein each of the monitor windows 302 penetrates through the first surface and the second surface, each of the monitor windows 302 is uniformly distributed on a first circle 304, a first annular region centered on the first circle 304 is a monitor window influence zone, and the monitor windows 302 cause an increase in a brush rate of a slurry in the monitor window influence zone.

In an embodiment of the application, the first circle 304 is shown with reference to a dotted circle in FIG. 7. The circular grooves 303 are omitted in FIG. 7.

In some embodiments, the number of the monitor windows is 3.

Also referring to FIG. 7, the polished member 401 is usually a wafer. The monitor windows 302 need to monitor the thickness of the polished member 401 during the polishing process. Therefore, the polished member 401 needs to be placed on the first circle 304. When the pad 301 rotates, an annular region centered on the first circle 304 will polish the polished member 401, and the polished member 401 will also rotate with the polishing head 408. After being mapped onto the polished member 401, the monitor window influence zone corresponds to the region indicated by the dotted circle 401b with a radius of r102 in FIG. 8.

The first surface is provided thereon with a groove pattern structure. The groove pattern structure is used to adjust a brush rate of a slurry on the first surface, and causes a decrease in the brush rate of the slurry in the monitor window influence zone to compensate for the influence of the monitor windows 302 on the increase in the brush rate of the slurry in the monitor window influence zone.

The second surface of the pad 301 is arranged on a polishing table 402.

A polishing head 408 is disposed above the first surface of the pad 301, which is used to fix the polished member 401 and press a polished surface of the polished member 401 against the first surface.

In an embodiment of the application, as shown in FIG. 5A, the groove pattern structure comprises a plurality of concentric circular grooves 303. In a radius direction along the first surface, the circular grooves 303 are isolation structures which are not connected to each other. The isolation structures serve as structures that cause a decrease in the brush rate of the slurry in the monitor window influence zone.

In an embodiment of the application, the first circle 304 is located in one of the circular grooves 303.

The cross-section structures of the circular grooves 303 and the monitor windows 302 are shown with reference to FIG. 5B. It can be seen that near the monitor windows 302, the roughness of the first surface is different from that of other regions, so there will be an increased influence on the brush rate of the slurry, which will have an increased influence on a polishing rate of a region near the monitor windows 302, i.e., the monitor window influence zone.

Moreover, in an embodiment of the application, the circular grooves 303 are not connected to each other, so the slurry will not flow between the circular grooves 303 of different radii through the longitudinal grooves. Therefore, a brush rate of a slurry in each region will decrease, and the brush rate of the slurry in the monitor window influence zone will also decrease, so as to compensate for the influence on the increase in the brush rate of the slurry brought about by the monitor windows 302 themselves.

In an embodiment of the application, the width of the monitor window influence zone is less than the diameter of a central pressure adjustment zone of the polishing head 408. The structure of the polishing head 408 is shown with reference also to FIG. 6. The polishing head 408 is usually divided into a plurality of pressure adjustment zones, and the pressure of each pressure adjustment zone is adjusted independently by a multi-pressure controller so as to adjust a polishing rate of each pressure adjustment zone. As shown in FIG. 8, the dotted circle 401a shows that the central pressure adjustment zone of the polishing head 408 acts on a region on the polished member 401, and the two are in one-to-one correspondence. It can be seen that the region indicated by the dotted circle 401a is not equal to the region indicated by the dotted circle 401b, and the region indicated by the dotted circle 401a is larger than the region indicated by the dotted circle 401b. In this way, if only a polishing rate of the region indicated by the dotted circle 401b produces a jump, then the pressure of the central pressure adjustment zone cannot be adjusted to decrease the polishing rate of the region indicated by the dotted circle 401b, because adjusting the pressure of the central pressure adjustment zone alone will also affect a polishing rate of an annular region between the dotted circles 401a and 401b, finally resulting in the uniformity of the polishing rate still not meeting the requirements.

In some embodiments, the width of the monitor window influence zone is less than or equal to 60 mm, corresponding to r102 of 30 mm in FIG. 8. The radius of the central pressure adjustment zone of the polishing head 408, i.e., r101, is 40 mm.

In an embodiment of the application, also referring to FIG. 6, the monitor windows 302 are connected to the light emitting apparatus 406 and the spectrograph 405 of the FVXE assembly 404 through optical fibers 407.

A polishing object of the pad 301 is a non-metallic layer. The FVXE assembly 404 is used to monitor the profile of the non-metallic layer in real time.

As shown in FIG. 6, the bottom of the polishing table 402 is connected to a rotating shaft 403. During the polishing process, the rotating shaft 403 drives the entire polishing table 402 to rotate, and the rotation is indicated by a rotating arrow line in FIG. 6. In FIG. 6, the FVXE assembly 404 is disposed in a space at the bottom of the polishing table 402. A power supply or signal line of the FVXE assembly 404 is led outward along the rotating shaft 403.

In the prior art, the roughness of the 3 window pad at a three-hole position is different from that at other positions, resulting in a fast brush rate of a slurry at this position, and this position corresponds exactly to +/−30 mm from the wafer center, resulting to a jump in a polishing rate at the wafer center. In an embodiment of the application, the longitudinal grooves are removed from Pad, i.e., the pad, to reduce the brush rate of the slurry at 3 window, thereby decreasing the polishing rate at the wafer center.

In an embodiment of the application, after the removal of the longitudinal grooves, the wafer is flattened from a raised shape within 30 mm. Nu %, namely, the uniformity, is reduced from 6.87% to 2.67%, which can solve the problem of the profile of the water center. After the introduction of an FVXE function, wafer to wafer (WTW), with in wafer (WIW), and marathon data show that Nu % has increased by over 60% compared to an open loop. The open loop indicates that FVXE is not used for real-time feedback control of polishing.

In the prior art, in addition to increasing the flow of the slurry to the pad center, the longitudinal grooves can also remove substances such as particles or byproducts on the pad and the wafer, thus playing a role of defect improvement. Experiments show that through process recipe adjustment, such as adjustment of parameters such as pad condition, pad clean/wafer rinse, brush, etc., after the longitudinal grooves are removed in an embodiment of the application, it is possible to achieve a defect level comparable to a baseline of the prior art.

The application is described in detail above with reference to the specific embodiments, but these embodiments are not intended to limit the application. Without departing from the principle of the application, many transformations and improvements may be made by those skilled in the art, which should also be considered to be within the scope of protection of the application.