CN115401587B - Polishing head and semiconductor wafer flattening equipment - Google Patents

Polishing head and semiconductor wafer flattening equipment Download PDF

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Publication number
CN115401587B
CN115401587B CN202211190659.9A CN202211190659A CN115401587B CN 115401587 B CN115401587 B CN 115401587B CN 202211190659 A CN202211190659 A CN 202211190659A CN 115401587 B CN115401587 B CN 115401587B
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China
Prior art keywords
wafer
pressurizing
retaining ring
gear
ring
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CN202211190659.9A
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Chinese (zh)
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CN115401587A (en
Inventor
杨兆明
王东洁
曾文昌
中原司
张峰
江涛
康斌斌
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Zhejiang Xinhui Equipment Technology Co ltd
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Zhejiang Xinhui Equipment Technology Co ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B29/00—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents
    • B24B29/02—Machines or devices for polishing surfaces on work by means of tools made of soft or flexible material with or without the application of solid or liquid polishing agents designed for particular workpieces
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/04—Headstocks; Working-spindles; Features relating thereto
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B41/00—Component parts such as frames, beds, carriages, headstocks
    • B24B41/06—Work supports, e.g. adjustable steadies
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B47/00—Drives or gearings; Equipment therefor
    • B24B47/22—Equipment for exact control of the position of the grinding tool or work at the start of the grinding operation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention discloses a polishing head and semiconductor wafer flattening equipment, which are applied to the technical field of semiconductor processing, wherein the lower surface of a driving disc is divided into a wafer pressurizing area positioned in a central area and an outer ring pressurizing area; the wafer pressurizing area is provided with a first pressurizing device, the outer ring pressurizing area is provided with a second pressurizing device, and the first pressurizing device and the second pressurizing device are mutually independent; the second pressurizing device is connected with a retaining ring, and the deformation of the polishing pad is controlled to control the edge removal amount of the wafer to be polished while the wafer is kept from flying by controlling the pressure applied to the retaining ring. By arranging the first pressurizing device and the second pressurizing device which are mutually independent, the first pressurizing device is independently controlled to apply pressure to the wafer fixing device, and the second pressurizing device is independently controlled to apply pressure to the retaining ring, the wafer can be independently applied with controllable pressure through the wafer fixing device according to the required removal amount, and therefore the control of the wafer edge removal amount is achieved.

Description

Polishing head and semiconductor wafer flattening equipment
Technical Field
The present invention relates to the field of semiconductor processing technology, and in particular, to a polishing head and a semiconductor wafer planarization apparatus.
Background
The chemical mechanical polishing device is mainly used for carrying out global planarization treatment on the microcosmic rough surface of the wafer after the film deposition process so as to carry out the subsequent semiconductor process. Among them, the polishing head plays a very critical role. For wafers, the edge removal control capability directly affects the wafer edge quality; the uniformity of the wafer while pressing directly affects the flatness of the wafer. It is an urgent problem to those skilled in the art how to provide a polishing head that can individually control the amount of wafer edge removal during the polishing process.
Disclosure of Invention
The invention aims to provide a polishing head capable of controlling the edge removal amount of a wafer; another object of the present invention is to provide a semiconductor wafer planarization apparatus that can control the edge removal amount of a wafer.
In order to solve the technical problems, the invention provides a polishing head, which comprises a driving disc, a retaining ring and a wafer fixing device;
the lower surface of the driving disc is divided into a wafer pressurizing area positioned in a central area and an outer ring pressurizing area surrounding the wafer pressurizing area; the wafer pressurizing area is provided with a first pressurizing device, the outer ring pressurizing area is provided with a second pressurizing device, and the first pressurizing device and the second pressurizing device are mutually independent;
the second pressurizing device is connected with a retaining ring, and controls the deformation of the polishing pad by controlling the pressure applied to the retaining ring while keeping the wafer to be polished from flying during processing, so as to control the edge removal amount of the wafer to be polished; the first pressurizing device is connected with the wafer fixing device.
Optionally, the first pressurizing device includes a first flexible film located in the wafer pressurizing area, and a wafer pressurizing channel for delivering air to the first flexible film; the second pressurizing device comprises a second flexible film positioned in the outer ring pressurizing area and an outer ring pressurizing channel for conveying air to the second flexible film.
Optionally, the device further comprises a torque transmission device, wherein the torque transmission device comprises a driving external gear fixedly connected with the driving disk and a driving internal gear meshed with the driving external gear; a retaining ring external gear which is positioned below the driving internal gear, fixedly connected with the driving internal gear and meshed with the retaining ring internal gear; the retaining ring inner gear is fixedly connected with the wafer fixing device, and the retaining ring outer gear is fixedly connected with the retaining ring.
Optionally, the upper surface of drive internal gear is provided with and extends to the upper limit bulge of drive external gear top, upper limit bulge with be provided with the slip stroke clearance between the drive external gear.
Optionally, the wafer fixing device is provided with a lower limit protrusion extending to the lower part of the outer ring gear, and a sliding travel gap is arranged between the lower limit protrusion and the outer ring gear.
Optionally, the lower surface of the second pressurizing device is fixedly connected with a pressurized ring, the lower surface of the pressurized ring is fixedly connected with the outer ring gear, the lower surface of the outer ring gear is fixedly connected with a retaining ring fixing ring, and the lower surface of the retaining ring fixing ring is fixedly connected with the retaining ring.
Optionally, a back film is disposed on the lower surface of the wafer fixing device, and the wafer fixing device is further disposed to convey air between the back film and the wafer to be polished, and an air layer is formed between the back film and the wafer to compensate for thickness variation of the back film.
Optionally, the back pressure channel includes a plurality of output ports, and the output ports are uniformly distributed in the area where the back film is located.
Optionally, the back pressure channel is further used for vacuumizing and adsorbing the wafer to be polished.
The invention also provides semiconductor wafer planarization equipment, which comprises the polishing head.
The invention provides a polishing head, which comprises a driving disc, a retaining ring and a wafer fixing device; the lower surface of the driving disc is divided into a wafer pressurizing area positioned in a central area and an outer ring pressurizing area surrounding the wafer pressurizing area; the wafer pressurizing area is provided with a first pressurizing device, the outer ring pressurizing area is provided with a second pressurizing device, and the first pressurizing device and the second pressurizing device are mutually independent; the second pressurizing device is connected with a retaining ring, and the edge removing amount of the wafer to be polished is controlled by controlling the pressure applied to the retaining ring; the first pressurizing device is connected with a wafer fixing device.
By arranging the first pressurizing device and the second pressurizing device which are mutually independent, the first pressurizing device is independently controlled to apply pressure to the wafer fixing device, the second pressurizing device is independently controlled to apply pressure to the retaining ring, controllable pressure can be independently applied to the wafer through the wafer fixing device according to the required edge removal amount, and controllable pressure is independently applied to the polishing pad through the retaining ring, so that the control of the wafer edge removal amount is realized.
The invention also provides a semiconductor wafer flattening device which has the same beneficial effects and is not described in detail herein.
Drawings
For a clearer description of embodiments of the invention or of the prior art, the drawings that are used in the description of the embodiments or of the prior art will be briefly described, it being apparent that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from them without inventive effort for a person skilled in the art.
FIG. 1 is a schematic view of a polishing head according to an embodiment of the present invention;
FIG. 2 is a schematic view of a polishing head according to an embodiment of the present invention;
FIG. 3 is a schematic view of a polishing head of the prior art;
fig. 4 is a schematic structural diagram of another polishing head according to an embodiment of the present invention.
In the figure: 1. drive disk, 2 drive flange, 3 retaining ring, 4 first pressurization device, 5 second pressurization device, 6 wafer pressurization channel, 7 outer ring pressurization channel, 8 drive external gear, 9 drive internal gear, 10 retaining ring internal gear, 11 retaining ring external gear, 12 upper limit boss, 13 lower limit boss, 14 sliding travel gap, 15 compression ring, 16 retaining ring fixing ring, 17 compression disk, 18 pressurization disk, 19 backing film, 20 wafer to be polished, 21 back pressure channel, 22 outer shield, 23 inner shield, 24 air layer.
Detailed Description
The core of the present invention is to provide a polishing head. In the prior art, the edge removal amount of the wafer is generally difficult to control, and the emphasis in the prior art is on how to make the wafer uniformly stressed, and pressure is generally integrally applied. However, the polishing head not only applies pressure to the wafer, but also applies pressure to the polishing pad around the wafer during polishing. The integral pressure application can cause difficulty in adjusting the edge removal amount of the wafer, and cannot be adjusted according to different task requirements.
The polishing head comprises a driving disc, a retaining ring and a wafer fixing device; the lower surface of the driving disc is divided into a wafer pressurizing area positioned in a central area and an outer ring pressurizing area surrounding the wafer pressurizing area; the wafer pressurizing area is provided with a first pressurizing device, the outer ring pressurizing area is provided with a second pressurizing device, and the first pressurizing device and the second pressurizing device are mutually independent; the second pressurizing device is connected with a retaining ring, and the edge removing amount of the wafer to be polished is controlled by controlling the pressure applied to the retaining ring; the first pressurizing device is connected with a wafer fixing device.
By arranging the first pressurizing device and the second pressurizing device which are mutually independent, the first pressurizing device is independently controlled to apply pressure to the wafer fixing device, the second pressurizing device is independently controlled to apply pressure to the retaining ring, controllable pressure can be independently applied to the wafer through the wafer fixing device according to the required edge removal amount, and controllable pressure is independently applied to the polishing pad through the retaining ring, so that the control of the wafer edge removal amount is realized.
In order to better understand the aspects of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and detailed description. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a polishing head according to an embodiment of the invention.
Referring to fig. 1, in an embodiment of the present invention, a polishing head includes a drive disk 1, a retaining ring 3, and a wafer holding device; the lower surface of the driving disc 1 is divided into a wafer pressurizing area in a central area and an outer ring pressurizing area surrounding the wafer pressurizing area; the wafer pressurizing area is provided with a first pressurizing device 4, the outer ring pressurizing area is provided with a second pressurizing device 5, and the first pressurizing device 4 and the second pressurizing device 5 are mutually independent; the second pressurizing device 5 is connected with the retaining ring 3, and controls the deformation of the polishing pad by controlling the pressure applied to the retaining ring 3 while keeping the wafer to be polished from flying during processing, so as to control the edge removal amount of the wafer to be polished 20; the first pressurizing device 4 is connected with a wafer fixing device.
The above-mentioned driving disk 1 is a disk-shaped structure for imparting rotation to the wafer 20 to be polished and providing a driving force, and the rest of the polishing head in the embodiment of the present invention is generally disposed on the lower surface side of the driving disk 1, and the upper surface of the driving disk 1 is generally provided with a driving flange 2. The lower surface of the driving disk 1 is divided into a wafer pressing area in a central area and an outer ring pressing area surrounding the wafer pressing area, wherein the outer ring pressing area is generally annular, and the wafer pressing area is positioned at the inner side of the outer ring pressing area. The wafer pressing area corresponds to the wafer 20 to be polished, and the outer ring pressing area corresponds to the retainer ring 3.
The wafer pressurizing area is provided with a first pressurizing device 4, the outer ring pressurizing area is provided with a second pressurizing device 5, wherein the first pressurizing device 4 and the second pressurizing device 5 are required to be separated from each other and are independently controlled, namely, the first pressurizing device 4 and the second pressurizing device 5 are mutually independent. The first pressurizing device 4 is configured to provide a downward pressure, and the first pressurizing device 4 is connected to a wafer fixing device, through which the wafer 20 to be polished is fixed during use, and the corresponding first pressurizing device 4 can apply the downward pressure to the wafer 20 to be polished.
The second pressurizing means 5 described above may also be used to provide a downward pressure, which second pressurizing means 5 is fixedly connected to the retaining ring 3. The retainer ring 3 presses the polishing pad at the edge of the wafer 20 to be polished during use, so that the second pressing means 5 can apply downward pressure to the polishing pad at the edge of the wafer 20 to be polished. The retaining ring 3 is used for retaining the wafer to be polished without flying, and different deformation amounts of the polishing pad can be generated by applying different pressures to the polishing pad through the retaining ring 3, and different deformation amounts can cause different edge removal amounts of the wafer to be polished. I.e., by controlling the pressure applied to the retainer ring 3, the deformation of the polishing pad can be controlled to control the edge removal amount of the wafer 20 to be polished. Thus, by controlling the pressure applied to the polishing pad by the retainer ring 3 by the second pressurizing means 5, the amount of deformation generated by the polishing pad can be controlled, thereby achieving control of the amount of edge removal of the wafer 20 to be polished. The amount of edge removal of the wafer 20 to be polished is thus controlled by controlling the pressure applied to the retainer ring 3 in the embodiment of the present invention.
In the embodiment of the present invention, the first pressurizing device 4 includes a first flexible film located in the wafer pressurizing area, and a wafer pressurizing channel 6 for delivering air to the first flexible film; the second pressurizing means 5 comprises a second flexible membrane located in the outer ring pressurizing zone and an outer ring pressurizing channel 7 for delivering air to the second flexible membrane.
In embodiments of the present invention, the flexible membrane may be inflated, in particular by delivering compressed air, i.e. air pressure, to the flexible membrane, thereby generating a downward force. Specifically, the first pressurizing device 4 located in the wafer pressurizing area is a first flexible film, and the second pressurizing device 5 located in the outer ring pressurizing area is a second flexible film. Whereas the wafer pressure channels 6 extend generally from the drive flange 2 through the interior of the drive plate 1 to the first flexible membrane, the corresponding outer ring pressure channels 7 extend generally from the drive flange 2 through the interior of the drive plate 1 to the second flexible membrane. Of course, the wafer pressing passage 6 and the outer ring pressing passage 7 may be provided in other manners, and are not particularly limited herein. Because the driving disc 1 is divided into the wafer pressurizing area and the outer ring pressurizing area, and the wafer pressurizing channel 6 and the outer ring pressurizing channel 7 are arranged in the driving disc 1, the driving disc 1 can be of a split structure or an integrated structure, the integrated structure can enable the driving disc 1 to have higher structural strength, and the split structure can facilitate maintenance of the driving disc 1. The structure of the drive disk 1 is not particularly limited herein, as the case may be.
According to the polishing head provided by the embodiment of the invention, the first pressurizing device 4 and the second pressurizing device 5 which are mutually independent are arranged, the first pressurizing device 4 is independently controlled to apply pressure to the wafer fixing device, the second pressurizing device 5 is independently controlled to apply pressure to the retaining ring 3, the wafer can be independently applied with controllable pressure through the wafer fixing device according to the required edge removal amount, and the retaining ring 3 is independently applied with controllable pressure to the polishing pad, so that the edge removal amount of the wafer can be controlled.
The specific structure of a polishing head according to the present invention will be described in detail in the following embodiments of the invention.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a polishing head according to an embodiment of the invention.
The embodiment of the present invention is different from the embodiment of the present invention described above, and the structure of the polishing head is further limited on the basis of the embodiment of the present invention described above. The rest of the content is described in detail in the above embodiment of the present invention, and will not be described in detail herein.
Referring to fig. 2, in the embodiment of the present invention, the polishing head further includes a torque transmission device including a driving external gear 8 fixedly connected to the driving disk 1, and a driving internal gear 9 intermeshed with the driving external gear 8; a retaining ring external gear 11 positioned below the driving internal gear 9, fixedly connected to the driving internal gear 9, and meshed with the retaining ring external gear 10; the retaining ring outer gear 11 is fixedly connected with the retaining ring 3, and the retaining ring inner gear 10 is fixedly connected with the wafer fixing device. The fixed connection is typically a fastening connection.
The torque transmission device is used for transmitting torque to the retaining ring 3 and the wafer fixing device so as to drive the wafer 20 to be polished to rotate. Specifically, the side having the driving disk 1 may be formed to extend downward to form an annular end portion fixedly connected to the external driving gear 8, and the external driving gear 8 may be fixedly connected to the annular end portion. The driving internal gear 9 described above meshes with the driving external gear 8, so that torque can be transmitted to the driving internal gear 9. The retaining ring gear 10 is usually located below the driving internal gear 9, and the retaining ring gear 10 is fixedly connected with the lower surface of the driving internal gear 9, so that nine torque can be transmitted to the retaining ring gear 10; while the retaining ring gear 10 is fixedly coupled to the wafer holder to transmit torque to the wafer holder. The above-described retainer ring gear 10 is also meshed with the retainer ring external gear 11 while the retainer ring external gear 11 is fixedly coupled with the retainer ring 3, thereby transmitting torque to the retainer ring 3. Normally, the retainer ring external gear 11 would be located below the drive external gear 8. In the exemplary embodiment of the invention, the torque has the same transmission path before it is transmitted to the retaining ring gear 10, i.e. the drive flange 2, the drive disk 1, the drive external gear 8, the drive internal gear 9 and the retaining ring gear 10; the torque is then split into two paths, one path being the retaining ring gear 10-the wafer to be polished 20-the wafer fixing device; the other path is a retaining ring inner gear 10, a retaining ring outer gear 11 and a retaining ring 3.
Specifically, in the embodiment of the present invention, the upper surface of the driving internal gear 9 is provided with the upper limit projection 12 extending above the driving external gear 8, and a sliding stroke gap 14 is provided between the upper limit projection 12 and the driving external gear 8. The upper limit protrusion 12 may have a ring shape, thereby forming the structure of the upper limit flange. The upper limit projection 12 extends above the external drive gear 8, so that the internal drive gear 9 can be hung on the inner side of the external drive gear 8 to mesh with the external drive gear 8.
The sliding travel gap 14 formed between the upper limit protrusion 12 and the driving external gear 8 is specifically used for realizing floating self-adaptation when the wafer fixing device applies pressure to the wafer and presses the polishing pad. When polishing the wafer 20 to be polished, the wafer is pressed against the surface of the polishing pad, which is specifically disposed on the surface of the polishing platen. When the polishing head presses the wafer 20 to be polished against the polishing disk, the wafer holding device can float up and down in the sliding travel gap 14, so that the perpendicularity error between the polishing head and the polishing disk can be eliminated by the sliding travel gap 14.
Accordingly, in the embodiment of the present invention, the wafer fixing device is provided with the lower limit protrusion 13 extending to the lower side of the holding ring external gear 11, and the sliding stroke gap 14 is provided between the lower limit protrusion 13 and the holding ring external gear 11. The lower limit protrusion 13 may also have a ring shape, and the lower limit protrusion 13 may extend below the outer ring gear 11.
Similar to the above-described sliding stroke gap 14 formed between the upper limit projection 12 and the driving external gear 8, the sliding stroke gap 14 formed between the lower limit projection 13 and the retainer ring external gear 11 is also used to achieve floating up and down between the wafer pressing region corresponding part and the outer ring pressing region corresponding part, so that the perpendicularity error between the polishing head and the polishing disk can be eliminated by the above-described sliding stroke gap 14. Wherein the first pressurizing means 4, the wafer fixing means, the driving inner gear 9 and the retaining ring inner gear 10 are usually members corresponding to the wafer pressurizing area, and the remaining members including the second pressurizing means 5 including the subsequent pressurizing ring 15, the driving outer gear 8, the retaining ring outer gear 11, the retaining ring fixing ring 16 and the retaining ring 3 are members corresponding to the outer ring pressurizing area.
In the embodiment of the invention, the lower surface of the second pressurizing device 5 is fixedly connected with a pressurized ring 15, the lower surface of the pressurized ring 15 is fixedly connected with a retaining ring external gear 11, the lower surface of the retaining ring external gear 11 is fixedly connected with a retaining ring fixing ring 16, and the lower surface of the retaining ring fixing ring 16 is fixedly connected with a retaining ring 3. The path along which the second pressurizing means 5 applies pressure to the retainer ring 3 is therefore: the second pressurizing device 5, the pressure receiving ring 15, the retaining ring external gear 11, the retaining ring fixing ring 16 and the retaining ring 3.
In the embodiment of the invention, the wafer fixing device comprises a pressure receiving disc 17, a pressure disc 18 and a back film 19, wherein the lower surface of the first pressure device 4 is fixedly connected with the pressure disc 17, the lower surface of the pressure disc 17 is fixedly connected with the pressure disc 18, and the lower surface of the pressure disc 18 is fixedly connected with the back film 19. The wafer 20 to be polished is adsorbed on the surface of the back film 19 during polishing. Typically, the outside of the drive disk 1 may be provided with a downwardly extending outer shroud 22, while the retaining ring 16 may be provided with an upwardly extending inner shroud 23, typically the inner shroud 23 will be located inside the outer shroud 22.
According to the polishing head provided by the embodiment of the invention, the formed sliding travel gap 14 can eliminate the perpendicularity error between the polishing head and the polishing disk.
The specific structure of a polishing head according to the present invention will be described in detail in the following embodiments of the invention.
Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of a polishing head in the prior art; fig. 4 is a schematic structural diagram of another polishing head according to an embodiment of the present invention.
The embodiment of the present invention is different from the embodiment of the present invention described above, and the structure of the polishing head is further limited on the basis of the embodiment of the present invention described above. The rest of the content is described in detail in the above embodiment of the present invention, and will not be described in detail herein.
Referring to fig. 3 and 4, in the embodiment of the present invention, the lower surface of the wafer fixing device is provided with a back film 19, and the wafer fixing device is further provided with a mechanism for delivering air between the back film 19 and a wafer 20 to be polished, and an air layer 24 is formed between the wafer and the back film to compensate for the thickness variation of the back film.
The air layer 24 is typically transported through the back pressure channel 21. The back pressure channel 21 typically extends from inside the drive flange 2, through the wafer holder, to the backing film 19. Since the back film 19 may have uneven thickness, uneven thickness of the back film 19 may cause uneven stress when the wafer 20 to be polished is pressurized during polishing. The outlet of the back pressure channel 21 extends at least to the back film 19, so that compressed air, i.e. air pressure, can be delivered to the back film 19 and the wafer 20 to be polished for a while, and an air layer 24 is formed between the back film 19 and the wafer 20 to be polished, and the air layer 24 can compensate for a gap formed between the back film 19 and the wafer 20 to be polished due to uneven thickness of the back film 19, so that the wafer 20 to be polished can be uniformly pressurized when the wafer 20 to be polished is pressurized.
In general, the back pressure channel 21 has a plurality of output ports, and the output ports are uniformly distributed in the area where the back film 19 is located, so that the air layer 24 can be uniformly formed. Unlike the wafer pressurization passage 6 and the outer ring pressurization passage 7 described above, the back pressure passage 21 can pump out air to form a vacuum environment for adsorption, and can pump liquid including pure water for cleaning and cooling, in addition to air. Specifically, the back pressure channel 21 is also used to vacuum the wafer 20 to be polished. That is, in the embodiment of the present invention, when the polishing head needs to adsorb the wafer 20 to be polished, vacuum adsorption may be performed by pumping vacuum between the wafer 20 to be polished and the back film 19 through the back pressure channel 21, so as to fix the wafer 20 to be polished while moving the wafer 20 to be polished. Accordingly, the above-described air pressure transmitted through the back pressure passage 21 can also be used for breaking the vacuum. The pure water supplied through the back pressure passage 21 pushes away the wafer 20 to be polished adsorbed on the back film 19 after breaking the vacuum, and simultaneously cleans the pressurizing plate 18 and the through holes of the back film 19.
The working time sequence of the polishing head provided by the embodiment of the invention is as follows: the polishing head moves to a loading position, the polishing head descends, and the back pressure channel 21 is opened in vacuum in a pipeline to absorb the wafer 20 to be polished; after the wafer is adsorbed on the polishing head, the polishing head rises and moves to a processing position and then descends, and based on the sliding travel gap 14, the wafer is self-adaptively floated through the driving external gear 8, the driving internal gear 9, the retaining ring external gear 10 and the retaining ring external gear 11 and is attached to a polishing pad on a polishing disk; then closing vacuum in the back pressure channel 21 and simultaneously opening air pressure to break vacuum, then starting to rotate the wafer 20 to be polished, pressurizing the wafer 20 to be polished through the first pressurizing device 4 while rotating, simultaneously pressurizing the retaining ring 3 through the second pressurizing device 5, and simultaneously opening the air pressure in the back pressure channel 21 to polish the wafer 20 to be polished until polishing is finished; after polishing, stopping rotating, closing the wafer pressurization at the same time, pressurizing the outer ring, closing the air pressure in the back pressure channel 21, and vacuum-opening the adsorption wafer at the same time; and the rear polishing head is lifted to move to an unloading position, the polishing head is lowered, pure water is started while the vacuum in the back pressure channel 21 is closed, the vacuum is closed after the wafer is pushed away for unloading, and the pure water in the pipeline is blown off by starting the air pressure, so that the whole polishing process of the wafer 20 to be polished is completed once.
According to the polishing head provided by the embodiment of the invention, the air layer 24 can be formed through the back pressure channel 21, the problem of uneven stress caused by uneven thickness of the back film 19 is solved, the thickness change of the back film 19 is solved, and meanwhile, the wafer 20 to be polished can be conveniently transported through vacuum adsorption.
The polishing head in the embodiments of the present invention has several important features:
the first and wafer pressing is performed by the first pressing device 4 using a pressing plate made of SUS (stainless steel) or Ceramics.
Second, a back film 19 (commercially available nonwoven fabric) is interposed between the pressing plate 18 and the wafer 20 to be polished, and serves to prevent the pressing plate from damaging the silicon wafer. Then, holes having a diameter of 1mm or less are uniformly drilled in the back film 19, and air or vacuum is discharged from the holes to assist in holding and releasing the wafer 20 to be polished during handling.
Third, by blowing out a small amount of air from the holes provided in the back film 19, the thickness change of the back material can be eliminated, and the silicon wafer can be homogenized when pressurized, thereby improving the processing accuracy.
Fourthly, in order to prevent flying sheets during processing of the polished wafer 20, a retaining ring 3 is arranged on the outer ring in a pressurizing manner; further, the deformation amount of the polishing pad can be controlled by pressing alone, and therefore, the edge of the wafer can be prevented from being single-sided (face collapse).
Fifthly, torque is transmitted by utilizing the gear, the gear can slide up and down when being meshed, the self-adaption type polishing device has self-adaption property, and the influence of perpendicularity errors between the shaft and the polishing disc on machining precision can be placed.
The invention also provides a semiconductor wafer flattening device which comprises the polishing head provided by any one of the embodiment of the invention. The remaining structure of the semiconductor wafer planarization apparatus may refer to the prior art, and will not be described herein.
Since the polishing head provided in the above embodiment of the invention is provided with the first pressurizing device 4 and the second pressurizing device 5 which are independent of each other, the first pressurizing device 4 is independently controlled to apply pressure to the wafer fixing device, and the second pressurizing device 5 is independently controlled to apply pressure to the retaining ring 3, so that the wafer can be independently applied with controllable pressure through the wafer fixing device according to the required edge removal amount, and the retaining ring 3 is independently applied with controllable pressure to the polishing pad, thereby realizing the control of the wafer edge removal amount. Therefore, the semiconductor wafer planarization equipment provided by the embodiment of the invention can also realize the control of the wafer edge removal amount.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.
The polishing head and the semiconductor wafer planarization apparatus provided by the present invention are described in detail above. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims (6)

1. A polishing head comprising a drive plate, a retaining ring and a wafer holder;
the lower surface of the driving disc is divided into a wafer pressurizing area positioned in a central area and an outer ring pressurizing area surrounding the wafer pressurizing area; the wafer pressurizing area is provided with a first pressurizing device, the outer ring pressurizing area is provided with a second pressurizing device, and the first pressurizing device and the second pressurizing device are mutually independent;
the second pressurizing device is connected with a retaining ring, and controls the deformation of the polishing pad by controlling the pressure applied to the retaining ring while keeping the wafer to be polished from flying during processing, so as to control the edge removal amount of the wafer to be polished; the first pressurizing device is connected with the wafer fixing device;
the torque transmission device comprises a driving external gear fixedly connected with the driving disk and a driving internal gear meshed with the driving external gear; a retaining ring external gear which is positioned below the driving internal gear, fixedly connected with the driving internal gear and meshed with the retaining ring internal gear; the retaining ring outer gear is fixedly connected with the retaining ring;
an upper limit protrusion extending to the upper part of the external driving gear is arranged on the upper surface of the internal driving gear, and a sliding stroke gap is arranged between the upper limit protrusion and the external driving gear;
the wafer fixing device is provided with a lower limit protrusion extending to the lower part of the retaining ring external gear, and a sliding travel gap is arranged between the lower limit protrusion and the retaining ring external gear;
the lower surface of the second pressurizing device is fixedly connected with a pressurized ring, the lower surface of the pressurized ring is fixedly connected with the outer retaining ring gear, the lower surface of the outer retaining ring gear is fixedly connected with a retaining ring fixing ring, and the lower surface of the retaining ring fixing ring is fixedly connected with the retaining ring.
2. A polishing head according to claim 1, wherein the first pressurizing means includes a first flexible membrane located in the wafer pressurizing area, and a wafer pressurizing channel for delivering air to the first flexible membrane; the second pressurizing device comprises a second flexible film positioned in the outer ring pressurizing area and an outer ring pressurizing channel for conveying air to the second flexible film.
3. A polishing head according to claim 1, wherein the lower surface of the wafer holding device is provided with a back film, and a back pressure passage extends from the inside of the driving flange, through the wafer holding device, to the back film, and supplies compressed air between the back film and the wafer to be polished, and an air layer is formed between the back film and the wafer to compensate for a thickness variation of the back film.
4. A polishing head according to claim 3, wherein the back pressure channel comprises a plurality of output ports, the output ports being evenly distributed over the area of the back film.
5. A polishing head according to claim 3, wherein the back pressure passage is further for vacuum sucking the wafer to be polished.
6. A semiconductor wafer planarization apparatus, characterized by comprising the polishing head according to any one of claims 1 to 5.
CN202211190659.9A 2022-09-28 2022-09-28 Polishing head and semiconductor wafer flattening equipment Active CN115401587B (en)

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JP3428566B2 (en) * 1995-02-28 2003-07-22 三菱マテリアル株式会社 Wafer polishing method
TW431942B (en) * 1997-04-04 2001-05-01 Tokyo Seimitsu Co Ltd Polishing device
US6231428B1 (en) * 1999-03-03 2001-05-15 Mitsubishi Materials Corporation Chemical mechanical polishing head assembly having floating wafer carrier and retaining ring
JP2000326218A (en) * 1999-05-14 2000-11-28 Mitsubishi Materials Corp Polishing machine and manufacture for wafer
BE1016792A5 (en) * 2005-10-04 2007-06-05 Hansen Transmissions Int METHOD FOR MANUFACTURING A COUPLING
JP6447472B2 (en) * 2015-11-26 2019-01-09 株式会社Sumco Wafer polishing method
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