CN119260585A

CN119260585A - Wax polishing process and polishing device for silicon wafer

Info

Publication number: CN119260585A
Application number: CN202411219911.3A
Authority: CN
Inventors: 陈跃骅; 方萌; 周贤明; 赵纪平; 戴文仙; 刘小祥; 汪新平; 廖建军
Original assignee: Zhejiang Xunsheng Electronic Co ltd
Current assignee: Zhejiang Xunsheng Electronic Co ltd
Priority date: 2023-10-24
Filing date: 2024-09-02
Publication date: 2025-01-07

Abstract

The present invention relates to the field of silicon wafer processing technology, specifically a silicon wafer wax polishing process and polishing device, comprising the following steps: S1, placing a polishing sheet on a wax polishing disc for wax patching, rotating the silicon wafer continuously for 1-60s, and coating the liquid wax on the back surface of the silicon wafer under the action of centrifugal force; S2, using a physical and chemical dual combination cleaning method for cleaning, first cleaning the polishing disc by a brush and a wax removal detergent, and then putting it into a cleaning machine with an ultrasonic device for secondary cleaning, and recycling it after cleaning. In the silicon wafer wax polishing process and polishing device, by seeking the best rotation speed and continuous rotation time, a more uniform wax film thickness distribution is obtained, and after chemical mechanical polishing, the local flatness of the silicon polishing sheet is better and the yield rate is higher. The polishing disc dewaxing cleaning method is improved, and it can be used to better clean the polishing disc in the wax polishing process.

Description

Silicon wafer waxing polishing process and polishing device

Technical Field

The invention relates to the technical field of silicon wafer processing, in particular to a silicon wafer waxed polishing process and a polishing device.

Background

Currently, the single-sided Chemical Mechanical Polishing (CMP) method of the mainstream silicon substrate material in the world adopts a wax patch mode. The liquid wax is uniformly smeared on the back surface of a silicon wafer, then stuck on a very flat clamp and put on a single-sided polishing machine for polishing. The uniformity of the thickness of the wax film between the wafer and the jig determines the magnitude of the local flatness (SBIR, SFQR) of the silicon substrate material after polishing. As global integrated circuit products have higher performance, the physical line width within the global integrated circuit products has been smaller, and the semiconductor integrated circuit industry has also increased the requirements for the local flatness of polished sheets of silicon substrate materials.

The surface polishing of the silicon wafer can be divided into two processing modes of waxless patch single-sided polishing (commonly used for silicon wafers with the diameter of less than 125 mm) and waxless patch single-sided polishing (commonly used for silicon wafers with the diameter of 150 mm-200 mm) according to different patch modes. However, for polishing silicon wafers with relatively small thickness, the polishing pad is polished by adopting wax adhesion due to the problems of glass fiber reinforced plastic strength, hole depth errors and the like. Although extremely high geometric parameters can be obtained by wax-sticking polishing, the polishing sheet with high surface granularity requirement, especially the polishing sheet with surface granularity of <0.3 mu m, is processed, and the de-waxing and cleaning after polishing become the key of the technology.

In the prior art, after polishing a silicon wafer, because the polishing disk needs to be used for a long time, after the polishing disk is used, a lot of polishing wax remains in the polishing disk, the polishing disk in the wax polishing process cannot be cleaned well by adding a cleaning agent for manual cleaning, the thorough cleaning of the polishing disk cannot be ensured, in the long-term processing, the problem that residual wax is accumulated in the polishing disk and is easy to block and stain is caused, in addition, after the silicon wafer is processed, organic matters can cover part of the surface of the silicon wafer, so that an oxide film and stains related to the oxide film are difficult to remove, then the oxide film is dissolved, epitaxial defects are introduced because the oxide layer is a stain trap, and finally particles, metals and the like are removed, and meanwhile, the surface of the silicon wafer is passivated.

Disclosure of Invention

The invention aims to provide a silicon wafer waxed polishing process and a polishing device, which are used for solving the problems that a lot of polishing wax remains in a polishing disk in the background technology, manual cleaning is generally carried out by adding a cleaning agent, the polishing disk in the waxed polishing process cannot be well cleaned in the mode, thorough cleaning of the polishing disk cannot be ensured, residual wax is accumulated in the polishing disk in long-term processing, residual wax is easy to block and pollute, and in addition, after the silicon wafer is processed, organic matters cover part of the surface of the silicon wafer, so that an oxide film and related pollution are difficult to remove.

In order to achieve the above purpose, the invention provides a silicon wafer waxed polishing process, which comprises the following steps:

S1, placing a polishing sheet on a polishing disc with wax for carrying out wax pasting, continuously rotating a silicon wafer for 1-60S, and coating liquid wax on the back surface of the silicon wafer under the action of centrifugal force, wherein no matter a wax film is uneven due to too low rotating speed or the surface of a silicon wafer part is uncovered due to too high rotating speed, micron-sized undulating morphology is formed on the polished surface of the silicon wafer after the polishing with wax, thereby forming obstruction for device manufacturing in the subsequent process and reducing the yield of a device factory;

s2, cleaning by adopting a physical and chemical dual-combination cleaning mode, firstly cleaning the polishing disk under the combined action of a brush and a paraffin removal cleaning agent, and then putting the polishing disk into a cleaning machine with an ultrasonic device for secondary cleaning, and recycling the polishing disk after cleaning;

S3, connecting a reducer pipe with a very short length on the chip mounting seat, and then connecting the residual wax recovery bottle on the reducer pipe, so that the discharged residual wax directly enters the residual wax recovery bottle for storage in a very short time;

and S4, cleaning the surface of the polished silicon wafer by adopting an RCA cleaning and megasonic cleaning technology.

In the step S2, the residual wax is recovered by the wax remover recovery tank, so that the wax remover can be reused, and the cost is reduced.

As a preferable scheme of the invention, in the step S2, the wax removing cleaning agent is sprayed through the wax removing agent adding pipe, and the brush divides the residual wax marks into countless tiny strip-shaped waxes when the surface of the polishing disk is scratched, so that the contact area between the residual wax and the chemical cleaning agent is increased, the chemical reaction between the wax removing cleaning agent and the residual wax is more thorough, and the countless tiny strip-shaped waxes are more easily shaken off by ultrasonic waves in a later cleaning machine.

As a preferred embodiment of the present invention, the RCA cleaning is a typical, as yet most commonly used wet chemical cleaning process that relies on solvents, acids, surfactants and water to thoroughly clean the wafer surface by spraying, cleaning, oxidizing, etching and dissolving contaminants, organics and metal ions on the wafer surface, in Ultra Pure Water (UPW) after each use of the chemicals.

As a preferable scheme of the invention, the megasonic cleaning technology adopts a piezoelectric effect to remove submicron particles and pollutants from a substrate in combination with a cleaning solution, and the working principle is that a piezoelectric ceramic crystal is excited by high-frequency (700-1000 kHz) alternating current to generate vibration, the vibration generates sound waves, the sound waves propagate through the cleaning solution to form controllable cavitation, the cavitation is caused by pressure change when the sound waves pass through the liquid, and the pollutant particles on the surface of a wafer are removed when the sound waves cross through the surface of an object.

The invention also provides a silicon wafer waxing and polishing device which is used for a silicon wafer waxing and polishing process and comprises a wafer loading seat, wherein a polishing disk is arranged at the top of the wafer loading seat, a polishing wafer is arranged in the polishing disk, a turntable is arranged at the upper part of the polishing wafer, a silicon wafer is arranged at the bottom of the turntable, and the turntable is driven by a motor to rotate so as to drive the silicon wafer to polish the surface of the polishing wafer.

As a preferable scheme of the invention, the upper part of the polishing disk is provided with a polishing agent adding pipe, the end head of the polishing agent adding pipe is provided with a spray head, the outside of the polishing agent adding pipe is connected to a polishing agent storage tank, and the polishing agent adding pipe is of a snake neck pipe structure.

As the preferable scheme of the invention, the cleaning device further comprises a cleaning tank, wherein the cleaning tank is provided with a cleaning disc at the upper part, a hairbrush is arranged at the bottom of the cleaning disc, the cleaning disc is supported by a bracket, a motor is arranged in the middle of the top of the cleaning disc, the motor drives the cleaning disc to rotate, and a screw rod assembly is vertically arranged on the bracket and drives the cleaning disc to lift.

As a preferable scheme of the invention, a dewaxing agent adding pipe is arranged at one side of the upper part of the cleaning tank, a spray head is arranged at the upper end of the dewaxing agent adding pipe, a dewaxing agent storage tank is connected at the lower end of the dewaxing agent adding pipe, and the dewaxing agent adding pipe is of a snake neck pipe structure.

As a preferable scheme of the invention, a residual wax recovery bottle is arranged in the chip mounting seat, the top of the residual wax recovery bottle is connected with a reducer pipe, and the top end of the reducer pipe is connected with a polishing disk.

Compared with the prior art, the invention has the beneficial effects that:

1. in the silicon wafer waxed polishing process and the polishing device, the optimal rotating speed and the continuous rotating time are sought to obtain more uniform wax film thickness distribution, and the silicon polishing wafer is better in local flatness and higher in yield after chemical mechanical polishing.

2. In the silicon wafer waxed polishing process and the polishing device, the polishing disk waxing and cleaning method is improved, and the polishing disk waxing and cleaning device can be used for better cleaning the polishing disk in the waxed polishing process.

3. In the silicon wafer waxed polishing process and the polishing device, the common problems of wax drainage and easy blockage and contamination of residual wax are solved through the recovery of the residual wax.

4. In the silicon wafer waxed polishing process and the polishing device, the RCA cleaning and megasonic cleaning technology is adopted to clean the surface of the polished silicon wafer, so that the cleaning of the silicon wafer is ensured.

Drawings

FIG. 1 is a schematic view of a portion of the structure of the present invention;

FIG. 2 is a second schematic diagram of a portion of the structure of the present invention;

fig. 3 is a schematic view of the internal structure of the tablet holder according to the present invention.

The meaning of each reference sign in the figure is:

1. A mounting seat; 11, reducing pipes, 12, residual wax recovery bottles, 2, polishing discs, 3, polishing sheets, 4, turntables, 5, silicon wafers, 6, polishing agent adding pipes, 7, cleaning tanks, 8, cleaning discs, 81, brushes, 9, a bracket, 10, a wax removing agent adding pipe and 11, a wax removing agent storage tank.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. 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.

Example 1

The invention provides a silicon wafer waxed polishing process and a polishing device, as shown in figures 1-3, comprising the following steps:

S2, cleaning by adopting a physical and chemical dual-combination cleaning mode, firstly cleaning the polishing disc through the combined action of a brush and a paraffin removal cleaning agent, then putting the polishing disc into a cleaning machine with an ultrasonic device for secondary cleaning, recycling after cleaning, and cleaning residual paraffin on the surface of the polishing disc placed in the cleaning machine through ultrasonic vibration by the ultrasonic device, so that the polishing disc is fully cleaned by adopting the physical and chemical dual-combination cleaning;

In the embodiment, in step S2, the residual wax is recovered by the wax remover recovery tank, so that the wax remover can be reused, and the cost is reduced.

Specifically, in step S2, the wax removing cleaning agent is sprayed through the wax removing agent adding pipe, and the brush divides the residual wax marks into countless tiny strip-shaped waxes when the surface of the polishing disk is scratched, so that the contact area between the residual wax and the chemical cleaning agent is increased, the chemical reaction between the wax removing cleaning agent and the residual wax is more thorough, and the countless tiny strip-shaped waxes are more easily shaken off by ultrasonic waves in the subsequent cleaning machine.

Further, RCA cleaning is a typical, as yet most commonly used wet chemical cleaning process that relies on solvents, acids, surfactants and water to thoroughly clean the wafer surface contaminants, organics and metal ion contamination by spraying, cleaning, oxidizing, etching and dissolving the wafer surface contaminants, in Ultra Pure Water (UPW) after each use of the chemicals.

Furthermore, the megasonic cleaning technology adopts the piezoelectric effect in combination with the cleaning liquid to remove submicron particles and pollutants from the substrate, and the working principle is that the piezoelectric ceramic crystal is excited by high-frequency (700-1000 kHz) alternating current to generate vibration, the vibration generates sound waves, the sound waves are transmitted through the cleaning liquid to form controllable cavitation phenomena, the cavitation phenomena are caused by pressure changes when the sound waves pass through the liquid, and the pollutant particles on the surface of the wafer are removed when the sound waves cross through the surface of the object.

Example 2

The invention also provides a silicon wafer waxing polishing device which is used for a silicon wafer waxing polishing process and comprises a wafer mounting seat 1, wherein a polishing disc 2 is arranged at the top of the wafer mounting seat 1, a polishing sheet 3 is arranged in the polishing disc 2, a rotary disc 4 is arranged at the upper part of the polishing sheet 3, a silicon wafer 5 is arranged at the bottom of the rotary disc, and the rotary disc 4 is driven by a motor to rotate so as to drive the silicon wafer 5 to polish the surface of the polishing sheet 3.

Further, the upper portion of polishing dish 2 installs polishing agent and adds pipe 6, and the shower nozzle is installed to the end of polishing agent adding pipe 6, and polishing agent adding pipe 6's external connection is to the polishing agent holding vessel, and polishing agent adding pipe 6 is the snake neck pipe structure, carries out the interpolation of polishing agent to polishing dish 2 inside through polishing agent adding pipe 6, improves the polishing effect.

Further, still include washing tank 7, the upper portion of washing tank 7 is provided with cleaning disc 8, brush 81 is installed to cleaning disc 8's bottom, cleaning disc 8 is supported through support 9, install the motor in the middle of cleaning disc 8's the top, the motor drives cleaning disc 8 and rotates, vertical install the lead screw subassembly on the support 9, the lead screw subassembly drives cleaning disc 8 and goes up and down, through putting into cleaning disc 8 with polishing dish 2 after using, the control lead screw subassembly drives cleaning disc 8 and descends again, then drive cleaning disc 8 through the motor and rotate, and then drive brush 81 and rotate, carry out cleaning work to cleaning disc 8's inside.

Further, a dewaxing agent adding pipe 10 is installed at one side of the upper part of the cleaning tank 7, a spray head is installed at the upper end of the dewaxing agent adding pipe 10, a dewaxing agent storage tank 11 is connected at the lower end of the dewaxing agent adding pipe 10, the dewaxing agent adding pipe 10 is of a snake neck pipe structure, and a dewaxing agent is added into the cleaning tray 8 through the dewaxing agent adding pipe 10.

Further, the inside of dress piece seat 1 is provided with surplus wax recovery bottle 12, and surplus wax recovery bottle 12's top is connected with reducing pipe 11, and reducing pipe 11's top is connected with polishing dish 2 for surplus wax's quick recovery.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the above-described embodiments, and that the above-described embodiments and descriptions are only preferred embodiments of the present invention, and are not intended to limit the invention, and that various changes and modifications may be made therein without departing from the spirit and scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims

1. The silicon wafer waxing and polishing process is characterized by comprising the following steps of:

S1, placing a polishing sheet on a polishing disc with wax for carrying out wax pasting, continuously rotating a silicon wafer for 1-60S, and coating liquid wax on the back surface of the silicon wafer under the action of centrifugal force;

s3, connecting a reducer pipe with a short length on the chip mounting seat, and then connecting the residual wax recovery bottle on the reducer pipe, so that the discharged residual wax directly enters the residual wax recovery bottle for storage in a short time;

2. The process for polishing a silicon wafer with wax according to claim 1, wherein in step S2, the residual wax is recovered by a dewaxing agent recovery tank.

3. The process for polishing a silicon wafer with wax according to claim 1, wherein in step S2, the wax removing cleaning agent is sprayed through the wax removing agent adding pipe, and the brush divides the residual wax marks into countless fine bar-shaped waxes when the surface of the polishing disk is scratched.

4. The wafer waxed polishing process of claim 1, wherein the RCA cleaning relies on solvents, acids, surfactants and water to remove contaminants, organics and metal ions from the wafer surface by spraying, cleaning, oxidizing, etching and dissolving the contaminants without damaging the wafer surface characteristics.

5. The waxy polishing process for silicon wafer according to claim 1, wherein said megasonic cleaning technique uses piezoelectric effect in combination with cleaning liquid to remove sub-fine particles and contaminants from the substrate.

6. A silicon wafer waxing polishing device is used for the silicon wafer waxing polishing process according to any one of claims 1-5 and is characterized by comprising a wafer loading seat (1), wherein a polishing disc (2) is arranged at the top of the wafer loading seat (1), a polishing sheet (3) is arranged in the polishing disc (2), a rotary disc (4) is arranged on the upper part of the polishing sheet (3), a silicon wafer (5) is arranged at the bottom of the rotary disc, and the rotary disc (4) is driven by a motor to rotate so as to drive the silicon wafer (5) to carry out polishing operation on the surface of the polishing sheet.

7. The silicon wafer waxed polishing device according to claim 6, wherein a polishing agent adding pipe (6) is arranged at the upper part of the polishing disk (2), a nozzle is arranged at the end head of the polishing agent adding pipe (6), the outside of the polishing agent adding pipe (6) is connected to a polishing agent storage tank, and the polishing agent adding pipe (6) is of a snake neck pipe structure.

8. The silicon wafer waxing and polishing device according to claim 6, further comprising a cleaning tank (7), wherein a cleaning disc (8) is arranged on the upper portion of the cleaning tank (7), a hairbrush (81) is arranged at the bottom of the cleaning disc (8), the cleaning disc (8) is supported by a support (9), a motor is arranged in the middle of the top of the cleaning disc (8), the motor drives the cleaning disc (8) to rotate, a screw rod assembly is vertically arranged on the support (9), and the screw rod assembly drives the cleaning disc (8) to lift.

9. The silicon wafer waxing and polishing device according to claim 8, wherein a de-waxing agent adding pipe (10) is arranged on one side of the upper part of the cleaning tank (7), a spray head is arranged at the upper end of the de-waxing agent adding pipe (10), a de-waxing agent storage tank (11) is connected at the lower end of the de-waxing agent adding pipe (10), and the de-waxing agent adding pipe (10) is of a snake neck pipe structure.

10. The silicon wafer waxing polishing device according to claim 6, wherein a residual wax recovery bottle (12) is arranged in the wafer loading seat (1), the top of the residual wax recovery bottle (12) is connected with a reducer pipe (11), and the top end of the reducer pipe (11) is connected with the polishing disk (2).