KR20010080964A - Method for storing carrier for polishing wafer - Google Patents

Abstract

A carrier 3 storage method is provided for polishing a silicon wafer capable of storing the carrier 3 in a manner that reduces scratches on the silicon wafer. This method involves storing the carrier 3 completely immersed in the liquid for use in polishing the silicon wafer. At least the majority of the liquid is deionized water.

Description

Storage method of carrier for wafer polishing {METHOD FOR STORING CARRIER FOR POLISHING WAFER}

Background of the Invention

The present invention relates to a carrier storage method used to polish a silicon wafer. In some polishing processes, both sides of the wafer are polished simultaneously.

Recently, a process of polishing silicon wafers, in particular, a process of simultaneously polishing both sides of a wafer has attracted attention. However, there is a serious problem that scratches occur on the silicon wafer during the polishing process.

The main cause of scratch formation is due to the carrier and the pin sleeve for driving the carrier. Such a carrier and a pin device are disclosed in Japanese Patent Laid-Open No. 8-096166. These members have been improved to reduce the rate at which scratches occur.

However, as these improvements are made, the conditions for acceptable scratches are also more regulated, allowing only smaller and smaller ones. Thus, more improvements are required, requiring tighter control over the carrier.

The carriers so far have been carriers 3 on a plurality of carrier setters 2 arranged on rollers 4 in the carrier reservoir 1, for example as shown in FIG. 3. ) Was stored horizontally.

It has been found that scratches continue to occur at unacceptable levels because of such dry storage. Moreover, the number of scratches on the silicon wafer increases with the number of times the carrier is used in the polishing process. It is believed that scratches are caused by contaminants such as residual abrasive slurry on the carrier that accompanies the polished silicon wafer when the carrier is replaced with the stored one. In addition, contaminants may be accompanied as a result of using a completely new carrier.

In view of the above-mentioned problems, the present invention particularly provides a method of storing a wafer polishing carrier in which a carrier is stored in a manner that reduces scratches on a silicon wafer generated during a polishing process of a silicon wafer, on which both sides of the silicon wafer are polished simultaneously. The purpose.

Summary of the invention

The present invention provides a method of polishing a silicon wafer that generates fewer scratches on the wafer; Providing a method of using a wafer carrier that can be utilized by current polishing apparatus without significant changes; Provide an economical way to use; Provided is a method that can be used in a wafer polishing process for simultaneously polishing both sides of a wafer.

The present invention provides a method of storing a carrier used to polish a silicon wafer. The method includes a method of completely immersing and storing a carrier in a liquid containing deionized water prior to use with the wafer in a wafer polishing step.

Other objects and features will be in part apparent and in part described below.

Brief description of the drawings

1 is a schematic illustration showing an embodiment of a carrier storage method according to the present invention.

2 is a schematic explanatory diagram showing still another embodiment of the carrier storage method according to the present invention.

3 is a schematic explanatory diagram showing an embodiment of a conventional carrier storage method.

4 is a graph showing the relationship between the number of times of polishing and the occurrence rate of scratches.

Corresponding reference characters indicate corresponding parts throughout the various views of the drawings.

Detailed description of the preferred embodiments

The present invention provides a method of storing a carrier for use during a polishing step of a silicon wafer during a polishing process. It is desirable that both sides of the wafer be polished simultaneously. The method includes completely immersing the carrier in a stock solution, such as deionized water or liquid mixtures containing deionized water, prior to use in the polishing step.

While storing the carriers, the stock solution is preferably maintained at a temperature of about 20 to 80 ℃. It is also desirable that the stock solution be filter-circulated washed while the carrier is stored, but the stock solution may be filtered not only during carrier storage but also at other times or at other times than during carrier storage.

According to the invention, a method is provided for storing a carrier for simultaneously polishing both sides of a silicon wafer, wherein the carrier is completely immersed and stored in a stock solution comprising a liquid mixture and one or more liquids containing dissolved solids. This is further provided. The main component of the stock solution is deionized water.

In order to obtain liquid mixtures it is preferred that the following components are added to the deionized water in the amounts indicated for the deionized water weight:

Surfactant (0.1-5% by weight);

Aqueous ammonia and hydrogen peroxide; And

Surfactant (0.1-5 wt% + aqueous ammonia and hydrogen peroxide)

The surfactant may be a soluble solid.

In the present invention, the pH of the stock solution is preferably about 7-12. In addition, the stock solution is preferably filter-circulated washed.

In the method of the present invention, the brush for cleaning the carrier and the abrasive polishing pad is stored with the carrier and the brush completely immersed in the stock solution.

As described above, in the method of storing the carrier of the present invention, the carrier is stored in a completely immersed state in the stock solution. Thus, the carrier can be separated from the contaminants so that the carrier can be stored and taken out clean. In addition, the contaminants of the carrier can be easily cleaned because the contaminants are not dried on the carrier and the carrier is not easily attached to the carrier even if it is initially contaminated. Thus, the number of scratches decreases as the contaminants that can cause scratches during the polishing process are reduced.

The method of the present invention can be applied not only to the aforementioned polishing carrier but also to a brush used to clean the abrasive polishing pad.

The deionized water used in the present invention is preferably super deionized water purified by use of an ion exchanger of an electrical recovery type in which an ion exchange resin and an ion exchange membrane are mixed, or purified by a reverse osmosis device.

The liquid mixture of the present invention is preferably prepared by adding the surfactant in an amount of about 0.1 to 5% by weight of deionized water (water present) in the final mixture.

This can have the effect of washing the stock with contaminants (especially particles) that are attached to the carrier and subsequently removed by filtering. In general, the volume ratio of ammonia water to hydrogen peroxide water to deionized water is adjusted in the range of about 1: 1: 10 to 1: 1: 200.

Surfactants that can be used in the present invention are selected from cationic surfactants, anionic surfactants, nonionic surfactants and amphoteric surfactants. Nonionic surfactants and amphoteric surfactants are preferred to remove contaminants.

Next, the carrier storage method of the present invention will be described in detail.

1 is a schematic explanatory diagram showing an embodiment of a carrier storage method of the present invention.

As shown in FIG. 1, the container 13 for storing the carrier is preferably first filled with a filter-washed stock solution.

A portion of the deionized water or liquid mixture (reserved liquid) described above is introduced into the filter 10 from the water intake port 11 disposed at the bottom of the vessel 13 by the use of a circulation pump 9, and the filter 10 The filter is cleaned by s), and is continuously provided to the container 13 through a water supply port 12 disposed on top of the container 13.

As the filter 10, it is preferable to use the filter which filters about 0.05-1.0 micrometer.

As described above, deionized water or liquid mixtures with sufficient contaminant particles are continuously circulated in the container so that substantially no particles are attached to the carrier even when the particles enter the container while the carrier is in or out of the container. The carrier should be placed in the container before drying after use to aid in the removal of particles from the carrier. Since the particles are not dry, they are hardly attached to the carrier, and even if the particles are attached to the carrier, the carrier can be easily cleaned before using or reusing the carrier.

For example, it is preferable to use the arm 5 shown in FIG. 1 to take the carrier out of the container for storing the carrier or to put the carrier into the container.

The arm 5 comprises a plurality of grooves 6 for holding the carrier, a stopper 7 for holding the arm 5 when the arm 5 is positioned to eject or insert the carrier and an arm 5. (Or the support part 8) is provided with the support part 8 which can support the arm 5 in the predetermined position of the container 13 so that it may move up and down.

The carrier 3 may be introduced into a container for immersing and storing the carrier in the stock solution. For example, the carrier 3 may be suspended by a storage shelf 14 in the form of a rack. The shelf is held in the container 13 by wires 16 connected to wintch means 18, which are operable to move the shelf up and down at a predetermined position in the container 13 as shown in FIG. 2. Hanging.

The wire 16 is preferably made of a material having low dusting properties. For example, nylon and the like can be suitably used as such a material.

With respect to the container 13 storing the carrier, the opening of the container 13 is preferably closed during carrier storage to prevent particles in the atmosphere from entering the container 13. In addition, the container 13 is preferably arranged in a clean air environment, such as in a clean room.

Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to these examples.

The incidence of scratches per silicon wafer (count / sl) was determined by visually observing silicon wafers in the dark using collimate light with a luminous intensity of 10 ⁵ lux and observing scratches as scratches by contaminants. It was obtained by discrimination.

By using the vessel 13 shown in FIG. Saved.

Thereafter, several polishing processes (a general method) were simultaneously performed on both sides of the silicon wafer using the aforementioned carrier.

The correlation between the number of polishing processes on the wafer and the rate of occurrence of scratches is shown in FIG. 4.

By using the vessel 13 shown in FIG. 1, the mixed liquid filtered by the filter 10 (1.0 μm filtration filter) is circulated while being completely immersed in a liquid mixture having a temperature of about 40 ° C. and a pH of about 10. The carrier 3 was stored.

The liquid mixture was prepared by adding L-64 (manufactured by BASF) 0.5 wt%, 30% ammonia water 0.5 wt%, 30% hydrogen peroxide solution (relative to the total weight of deionized water in the final mixture) as deactivator Was prepared.

Thereafter, several polishing processes (a general method) were simultaneously performed on both sides of the silicon wafer using the aforementioned carrier.

The correlation between the number of polishing processes on the wafer and the rate of occurrence of scratches is shown in FIG. 4.

The carrier 3 was stored in a dry state using the reservoir 1 for storing the carrier shown in FIG. 3.

Several polishing processes were performed simultaneously on both sides of the silicon wafer using the carrier.

The correlation between the number of polishing processes on the wafer and the rate of occurrence of scratches is shown in FIG. 4.

As shown in FIG. 4, the incidence of scratches on the silicon wafer was reduced in Examples 1 and 2 as compared to the comparative example.

In addition, in Example 2, the rate of occurrence of scratches on the silicon wafer was maximally reduced by adding the surfactant, ammonia water and hydrogen peroxide water to the deionized water as compared to using only deionized water.

As is clear from the above description, according to the present invention, the carrier can be stored in a clean state and can reduce the occurrence of scratches on the silicon wafer while simultaneously polishing both sides of the silicon wafer.

In describing the components of the present invention or preferred embodiment (s), the articles a, an, the, said are meant that one or more components are present. The words “configured”, “comprising” and “comprising” are included and mean that there may be additional components in addition to the described components.

As various changes are possible in the above structure without departing from the scope of the present invention, all contents contained in the above description and shown in the accompanying drawings shall be interpreted as an example and should not be interpreted in a limited sense.

Claims (13)

As a method of storing a carrier used for polishing a silicon wafer, And the carrier is completely immersed and stored in a liquid containing deionized water before being used with the wafer in the wafer polishing step. The method of claim 1, The temperature of the liquid is about 20 ℃ to about 80 ℃ the storage method of a carrier. The method of claim 2, And the liquid is filter-circulated rinsed. The method of claim 3, wherein And the liquid is substantially deionized water. The method of claim 4, wherein A carrier storage method, characterized in that both sides of the wafer are polished at the same time. The method of claim 1, And said liquid is a mixture comprising mostly deionized water. The method of claim 6, Wherein said mixture comprises from about 0.1 to 5% by weight of surfactant in said deionized water in said mixture. The method of claim 6, And said mixture comprises ammonia water and hydrogen peroxide water. The method of claim 6, Wherein said mixture comprises from about 0.1 to 5% by weight of ammonia water, hydrogen peroxide water and surfactant in said deionized water. The method of claim 8, Wherein the pH of the mixture is about 7-12. The method of claim 9, Wherein the pH of the mixture is about 7-12. The method of claim 6, The temperature of the mixture is about 20 ℃ to about 80 ℃ the storage method of a carrier. The method of claim 12, And the mixture is filter-circulated rinsed.