JP2000233354A - Wafer notch polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device suppressing the occurrence of linear scratch effectively in polishing of a notch formed in a peripheral edge of the outer periphery of a semiconductor wafer such as a silicon wafer. SOLUTION: In a device which is provided with a means 3 fixing a semiconductor wafer 1 such as a silicon wafer and a discoidal polisher 5 orthogonally crossing the semiconductor wafer fixed by the fixing means and polishing- machines a notch part while rotating and supplying component slurry for polishing by bringing the discoidal polisher into contact with the notch provided in the outer periphery of the wafer, either or both of a brushlike dresser 6 and a discoidal polisher purifying means consisting of a high pressure water injection device are attached to an outer periphery of the discoidal polisher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for polishing a notch formed on an outer peripheral portion of a semiconductor wafer or the like, and more particularly, to cleaning a disk-shaped polisher for polishing a notch. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer notch polishing apparatus provided with an apparatus.

[0002]

2. Description of the Related Art Heretofore, in the manufacturing process of a plate-like material, such as a silicon wafer, which is a raw material of an integrated circuit using a semiconductor such as an IC, an LSI, a VLSI, etc., which is required to have extremely high flatness and parallelism, a precision is required. Planar processing to obtain accurate dimensional accuracy and shape accuracy is performed by a lapping or polishing machine using a rotatable surface plate or a rotatable surface plate with a polishing pad attached to the surface. Is necessarily formed with an orientation flat or a notch to indicate the crystal direction. In particular, in recent years, a notch portion with a small loss of the wafer surface area is often formed in order to increase the product yield and the yield.

The notch is a small cut-out portion formed at the edge of the outermost peripheral edge of the wafer, and there are two types, a U-shaped shape and a V-shaped shape. In the processing of silicon wafers and the like, along with the processing of the surface portion, the peripheral edge portion also has an obtuse angle, or has an arc-shaped profile, for the purpose of preventing chipping and preventing entrainment of dust and the like. And mirror-finished. In particular, due to the trend toward miniaturization and high integration of ICs, LSIs, VLSIs, and the like, and the expansion of epitaxial technology, not only the improvement of the finished surface accuracy of the silicon wafer itself, but also the peripheral edge portion, which is the outermost peripheral portion of the silicon wafer, and the There is also a remarkable demand for improved finishing accuracy for continuous notches.

A wafer sliced from a single crystal ingot of silicon or another compound semiconductor is processed into a mirror-finished wafer having at least one surface mirror-finished through lapping, etching, and polishing steps, followed by device processing. Then, a fine electric circuit is written on the mirror surface. Until a complicated and dense electric circuit is written and divided into semiconductor element chips, the wafer is processed while maintaining the initial disk shape, and cleaning, drying, and transporting between each processing step A series of operations such as enter. In the meantime, if the outermost peripheral surface of the wafer, that is, the surface of the edge of the peripheral portion is steep and unprocessed and is in a rough state, it comes into contact with equipment and other objects during each process, causing micro-destruction (chipping). Fine particles are generated, and contaminant particles are entangled in the rough surface shape, and in the subsequent process, they dissipate and reverse-contaminate the precision-processed surface, resulting in reduced product yield and quality. It often has a significant effect. In order to prevent this, it is a common practice to chamfer the edge portion at an early stage of wafer processing and further mirror-finish the edge portion. This quality requirement is the same for the notch portion, and it is necessary to mirror-finish this portion at the same level as the edge portion.

As a polishing apparatus for the edge portion, for example, Japanese Patent Laid-Open Publication No.
No. 171656, a method of pressing and rotating a wafer edge portion while supplying a polishing composition liquid onto a rotating drum to which a polishing pad is attached, and performing processing by notching, Can be performed, for example, by using an apparatus as disclosed in JP-A-8-168947. That is, the above-described notch portion polishing device is incorporated in an edge polishing device, stops the rotation of the wafer during processing, presses the rotating disk-shaped polisher to that portion, and performs polishing while supplying an abrasive. It is characterized by performing.

[0006] The disc-shaped polisher used herein is, for example, a synthetic fiber or a natural fiber as a raw material, which is made into a felt-like non-woven fabric, or a cloth-like laminate thereof, or a resin-treated product thereof. A soft molded product of a synthetic resin or a composite product thereof is used.
According to such a polishing method, the notch portion is polished to a mirror surface, but linear scratches may frequently occur along the processing direction. The frequency of occurrence of the above-mentioned linear scratches may be more than 50% in a remarkable case,
Contaminant particles are entangled in the scratched part, and the contaminants are dissipated in a subsequent step, and reversely contaminate the mirror-finished surface, which greatly affects the yield and quality of the product.
In order to prevent such undesired phenomena beforehand, it is necessary to process the notch portion to the same level as that for processing the edge portion, and it is necessary to avoid the occurrence of abnormal scratches.

The present inventors have conducted intensive analysis on the causes of linear flaws that frequently occur in polishing of the notch portion, and have found that the causes are as follows. That is, when the disk-shaped polisher used when a linear scratch was generated at the notch portion was observed finely with a microscope, fine foreign matter was attached to the tissue, and this was the main factor that caused a linear scratch during polishing. It has become. This fine foreign matter is fine silicon crushed pieces, which are generated from the notch portion and adhered to the polisher structure when polishing the notch portion, and further generated by diamond grinding when forming the notch portion. It was found that the crack residue was attached to the polisher tissue. As described above, since the disc-shaped polisher is a laminate of a nonwoven fabric or a cloth, the structure is a complicated structure in which fine fibers are entangled, and the crushed pieces of attached silicon can be easily separated. Instead, it causes linear scratches as described above.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present inventors have conducted intensive research and have developed a polishing apparatus according to the present invention. An object of the present invention is to provide a polishing apparatus for a wafer notch portion which does not cause abnormal linear scratches.

[0009]

An object of the present invention is to provide a semiconductor wafer fixing means, and a disk polisher orthogonal to the semiconductor wafer fixed by the fixing means. In a device for polishing a notch portion while supplying a polishing composition slurry while rotating while contacting a notch portion provided on a peripheral portion, the polishing device includes a brush-like dresser and a high-pressure water injection device. And / or both of them are attached to the outer periphery of the disk-shaped polisher.

In the present apparatus, the disk-shaped polisher purifying means is means for removing particles and contaminants adhering to the surface of the polisher by using an external force to return to a clean state. A brush-like dresser is provided so as to contact an outer peripheral portion of the disc-like polisher,
The high-pressure water jetting device has its tip nozzle installed at a position different from the position of the polishing composition slurry supply nozzle, and can jet high-pressure water to the tip of the rotating disk-shaped polisher. It is preferable that drainage on the polishing slurry side and drainage on the high-pressure water side be separate systems. Further, the injection of the high-pressure water may be performed at the same time as the polishing processing, or may be performed separately, and is not particularly limited.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The essential point of the present invention is to effectively remove fine silicon crushed pieces, which are the main cause of the linear scratches generated at the above-mentioned wafer notch, and to obtain a high-precision mirror-finished surface. Is to get That is, the brush-like dresser is constantly or optionally pressed against the tip of the rotating disk-shaped polisher, whereby foreign matter such as crushed pieces attached to the tip of the polisher can be effectively removed by the abrasion force. . In addition, by selectively injecting high-pressure water to the tip of the disc-shaped polisher, foreign matter adhering to the surface, slurry solidified at the tip of the polisher or foreign matter trapped in the polisher tissue can be forcibly removed. Can be. 2 above
Although the two means can exert their effects sufficiently even if they are installed independently, the effect can be further improved by installing both of them.

A specific embodiment of the apparatus for polishing a wafer notch according to the present invention will be described with reference to the drawings, but the present invention is not particularly limited thereby. FIG. 1 is a longitudinal sectional view showing a disk-shaped polisher and a silicon wafer of the present apparatus, and FIG. 2 is a transverse sectional view thereof. FIG. 3 is a sectional view taken along the line AA ′ of FIG. In this embodiment, the silicon wafer 1 is fixed by fixing means comprising a vacuum chuck 3, and a notch portion 2 formed at the outermost peripheral edge thereof has a disk-shaped polisher 5 held by holding plates 4, 4 '. The tip of is contacted. A brush-shaped dresser 6 is disposed at a lower end of the disk-shaped polisher 5, and a high-pressure water injection nozzle 7 is provided at a position apart from a polishing composition slurry supply nozzle 8. The silicon wafer 1 can swing up and down in conjunction with the fixing means. Polishing devices other than silicon wafers are housed in a storage case 9 for preventing scattering.

The outer peripheral edge portion of the disk-shaped polisher 5 is formed into a shape that fits into the shape of the notch portion 2 formed on the outermost peripheral edge portion of the silicon wafer 1, for example, a U-shaped or V-shaped shape. While supplying the polishing composition slurry, the disc-shaped polisher 5
The wafer notch is polished by rotating at a high speed of about 0 to 2000 RPM. The brush-like dresser 6 disposed at the lower end of the disk-like polisher 5 is designed to always or when necessary contact the rotating disk-like polisher. And the like can be effectively removed. In the drawings, the brush-shaped dresser 6 is a fixed type brush formed into a U-shape or a V-shape, but may be a wheel-shaped brush which is rotated by forcible driving, for example.

The high-pressure water is locally injected through the high-pressure water injection nozzle 7 to the outer peripheral edge of the disk-shaped polisher 5. Due to the extremely high external force of the high-pressure water, foreign matters such as fine silicon fragments adhered firmly to the complex structure of the disk-shaped polisher 5 are forcibly removed and washed away. The cleaning with high-pressure water may be performed simultaneously with the progress of the polishing process, or may be performed in a short time after the completion of the polishing process. The latter is better for minimizing the amount of water used and the load on the wastewater treatment facility, but the former is better for the more complete effect. The pressure of the high-pressure water is preferably higher when considering only the washing effect, but the preferable pressure in consideration of operability and economy is approximately 10 kgf.
/ M ² .

[0015] The slurry of the workpiece for polishing used in the polishing process is usually collected and reused.
The same applies to the present invention, however, when coalesced with the wastewater on the high-pressure water side, the concentration is extremely reduced, and its recovery and reuse becomes extremely difficult. Therefore, in the present invention, in order to separate the two drainage systems, the weir 1
It is preferable to provide a separate system 1 and direct the wastewater on the high-pressure water side to the wastewater treatment equipment as it is, and recover and recycle the polishing slurry for reuse.

The disc-shaped polisher used in the present invention is prepared by using fibers as a raw material as described above and tailoring them into a felt-like non-woven fabric, or by laminating them into a fabric and laminating them. Although it is a soft molded product of a synthetic resin or a composite product thereof, the mechanical strength of the resin itself is not so strong, so that it is gripped by the gripping plates 4 and 4 '. It is preferable to use a material that is excellent in chemical stability and chemically stable, for example, a plate made of PEAK material or Teflon-coated stainless steel.

According to the apparatus for polishing a wafer notch portion according to the present invention, the surface roughness of the notch portion having a Ra of 0.1 to 0.3 μm is 0.002 to 0.003 μm.
The mRa was improved to about mRa, and the occurrence of linear flaws, which were frequently seen in the past with a frequency of 50% or more, could be reduced to 1% or less.

[0018]

According to the apparatus for polishing a wafer notch portion according to the present invention, the surface roughness of the notch portion can be improved as well as the conventional method, and a good mirror surface can be obtained. Almost no linear scratches were found. Therefore, reverse contamination in the polishing process of a semiconductor wafer such as a silicon wafer due to the influence of linear scratches can be prevented, which is sufficient for the trend of miniaturization and high integration of ICs, LSIs or VLSIs expected in the future and expansion of epitaxial technology. Can be handled.

[Brief description of the drawings]

FIG. 1 is a longitudinal section of a main part of an apparatus according to the present invention.

FIG. 2 is a cross-sectional view of a main part of the device according to the present invention.

FIG. 3 is a sectional view taken along line A-A 'of FIG.

[Explanation of symbols]

1: Silicon wafer 2: Wafer notch 3: Vacuum chuck 4, 4 ': Grip plate 5: Disc-shaped polisher 6: Brush-shaped dresser 7: High-pressure water injection nozzle 8: Polishing composition slurry supply nozzle 9: Storage case 10 ： Drainage receiving tank 11 ： Weir

Claims (4)

[Claims] 1. A semiconductor device comprising: means for fixing a semiconductor wafer; and a disk-shaped polisher orthogonal to the semiconductor wafer fixed by the fixing means, wherein the disk-shaped polisher is attached to a notch provided on an outer peripheral portion of the wafer. In a device for polishing the notch portion while supplying the polishing composition slurry while rotating while contacting, one or both of a brush-shaped dresser and a disk-shaped polisher purifying means including a high-pressure water injection device are provided. Is mounted on an outer peripheral portion of the disk-shaped polisher. 2. The apparatus according to claim 1, wherein a brush-like dresser is provided so as to contact an outer peripheral portion of said disk-like polisher. 3. The polishing apparatus for a wafer notch according to claim 1, wherein the nozzle of the high-pressure water jetting device is installed at a position different from the position of the supply nozzle of the polishing composition slurry, and is rotated. A high-pressure water jet can be sprayed onto the tip of the disc-shaped polisher. 4. The apparatus according to claim 3, wherein the drainage on the polishing slurry side and the drainage on the high-pressure water side are separate systems.