JPH0888209A - Adhesive tape and method for removing foreign matter adhering to semiconductor wafer - Google Patents

Abstract

PURPOSE: To prevent the dropping of the elimination factor of foreign matters from semiconductor wafers and the electrostatic destruction of the wafers due to static electricity at the time of using a dry cleaning method using an adhesive tape. CONSTITUTION: An adhesive tape 1 for removing foreign matters is composed of a substrate film 11 and adhesive layer 12 and is subjected to an antistatic finish. Foreign matters adhering to the front and/or rear surface of a semiconductor wafer are removed by removing the tape 1 from the front and/or rear surface of the wafer after sticking the tape 1 to the front and/or rear surface of the wafer so that the foreign matters can be streak to the adhesive layer 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape for removing foreign matter adhering to a semiconductor wafer and a method for removing it, which is applied to a cleaning step in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art As the density of LSIs increases, the degree of integration increases, and the diversification of circuits progresses, foreign substances (particles) such as dust and metal impurities existing on semiconductor wafers increase the yield of products and increase the reliability of products. Has come to have a great influence on. For example, a foreign substance existing on the surface of a semiconductor wafer (circuit pattern forming surface) causes a disconnection or a short circuit of a circuit when the circuit is formed. In addition, foreign matter existing on the back surface of the semiconductor wafer (the surface opposite to the circuit pattern surface) may cause the focus to be deviated during the exposure process at the time of circuit formation. -It causes

Therefore, in the LSI manufacturing process, efforts are being made to improve the level of cleanliness in the manufacturing process and the level of wafer cleaning technology, and various cleaning technologies have been proposed and implemented. Especially, the washing process is about 3
It accounts for 0%, which is the key to improving yield and reliability. However, with the recent increase in the density and integration of LSIs, the problems of the conventional wafer cleaning method have become apparent.

The wafer cleaning method includes wet cleaning (using ultrapure water, chemical solution, etc.) and dry cleaning (UV ozone, O 2).
₍₂ plasma etc.), and in general, wet cleaning is frequently applied because of its good balance of versatility and economy. The problem of wet cleaning is that foreign matter removed from the wafer by cleaning is reattached to the wafer, and in particular foreign matter attached to the back surface of the wafer becomes a significant source of contamination. Also,
Since wet cleaning requires a drying process, the problem of wafer contamination during the drying process also exists.

As a cleaning method for compensating the disadvantages of wet cleaning, dry cleaning methods (UV ozone, O ₂ plasma, etc.) are being advanced, and advantages such as reduction of redeposition of foreign matters and omission of a drying step are utilized. However, it has been found that dry cleaning does not show a sufficient ability to remove foreign substances and is not suitable for removing a large amount of contaminants.

As another attempt, JP-A-48-35771
JP-A-53-92665, JP-A 1-1
Japanese Patent No. 35574 discloses a method of using an adhesive tape to adsorb foreign matter adhering to the surface of a semiconductor wafer onto the adhesive layer surface of the tape to remove it. Since this method can be said to be a kind of dry cleaning, it is possible to avoid the problem of reattachment of foreign matter in wet cleaning and the problem of contamination in the drying process, and it is also applicable to other dry cleaning such as UV ozone and O ₂ plasma. In comparison, it is expected that the ability to remove foreign matter will be further enhanced.

[0007]

However, in the method proposed above, static electricity is generated during the peeling operation after sticking the adhesive tape on the semiconductor wafer, and this static electricity removes foreign matter composed of suspended particles. Since redeposition occurs on the surface of the semiconductor wafer, there is a problem in that the removal rate of foreign matter is reduced accordingly. In addition, there is a risk of electrostatic breakdown of the semiconductor wafer due to the generation of static electricity.
e Coupled Device) is a general MOS
-Since the electrostatic withstand voltage is lower than that of LSI, measures against static electricity in the manufacturing process are indispensable.

In view of the above circumstances, the present invention uses a specific adhesive tape in a dry cleaning system using an adhesive tape, which is more useful than the wet cleaning system, to generate static electricity. The purpose is to prevent the reduction of the foreign matter removal rate due to the above, and to prevent electrostatic breakdown of the semiconductor wafer.

[0009]

Means for Solving the Problems The inventors of the present invention have made extensive studies on the above-mentioned object, and as a result, by using an adhesive tape which has been subjected to an antistatic treatment, the adhesive tape is attached to a semiconductor wafer. It was found that the generation of static electricity during the peeling operation after the attachment is prevented, and the reduction of the foreign matter removal rate and the electrostatic breakdown of the semiconductor wafer due to the reattachment of the foreign matter due to the static electricity can be successfully prevented, and the present invention is completed. It arrived.

That is, according to the present invention, firstly, as the above-mentioned specific adhesive tape, an adhesive tape composed of a support film and an adhesive layer is subjected to an antistatic treatment to remove foreign matter attached to a semiconductor wafer. It provides a removable adhesive tape.

Secondly, after attaching the above-mentioned adhesive tape to the front surface and / or the back surface of the semiconductor wafer,
Disclosed is a method for removing foreign matter attached to a semiconductor wafer, characterized in that the foreign matter attached to the front surface and / or the back surface of the semiconductor wafer is adsorbed to the pressure-sensitive adhesive layer surface and removed from the semiconductor wafer by a peeling operation. .

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an example of a foreign matter removing adhesive tape of the present invention. 1 is adhesive tape,
It is composed of a support film 11 and an adhesive layer 12.

The support film 11 is made of plastic such as polyester, polycarbonate, polyvinyl chloride, ethylene-vinyl acetate copolymer, ethylene-ethyl acrylate copolymer, polyethylene, polypropylene, ethylene-propylene copolymer. Usually consists of 10 to 10
The film has a thickness of 1,000 μm.

The pressure-sensitive adhesive layer 12 is the support film 11 described above.
A variety of pressure-sensitive adhesives such as acrylic resin, silicone resin, fluorine resin, rubber, etc., which have adhesive strength under normal conditions, are applied on the top and crosslinked by heating, etc. It is formed by sticking the pressure-sensitive adhesive layer formed by the same method as above on the support film 11. The thickness may be appropriately determined, but is usually 5 to 100 μm. The adhesive strength is JIS as a peelable adhesive strength.
180 degree peeling adhesion to silicon wafer measured according to Z-0237 (at room temperature, peeling speed 300
mm / min) is usually 50 to 500 g / 20 mm wide.

In the present invention, such an adhesive tape 1 is subjected to an antistatic treatment. For antistatic treatment,
An antistatic agent is coated on the support film 11, a conductive substance is vapor-deposited on the support film 11, an antistatic agent is kneaded into the material of the support film 11, and the material of the support film 11 is made conductive. There is a method such as adding an antistatic agent to the pressure-sensitive adhesive layer 12. Antistatic agents and conductive materials used in these methods include surfactant-based materials, conductive organic material-based materials (carbon black, organic semiconductors, etc.), metal-based materials, and metal oxide-based materials.

In the present invention, the adhesive tape having the above-mentioned structure is used to remove foreign matters adhering to the semiconductor wafer.
In this method, first, an adhesive tape is attached to the entire front surface and / or the back surface of the semiconductor wafer so that the surface of the adhesive layer is sufficiently adapted to the foreign matter on the wafer. This may be done by pressing the adhesive tape on the wafer with a hand roller and then leaving it for a few minutes.

When the adhesive tape is peeled off from the end portion of the adhesive tape and the peeling operation is performed after the attachment, the foreign matters adhering to the semiconductor wafer are adsorbed on the adhesive layer surface and removed from the wafer. At that time, static electricity is not generated as in the prior art, and there is little risk of redeposition of suspended particles or electrostatic breakdown of the semiconductor wafer due to static electricity.

With this method, a high removal rate of foreign matter on a semiconductor wafer (usually 75% of foreign matter having a size of 0.2 μm or more)
Cleaning and removal with a higher removal rate (above) reduces the occurrence of circuit disconnection, shots, and exposure defects during circuit formation, and because there is no fear of electrostatic damage, the yield and reliability of semiconductor devices are improved. Greatly improved. Further, from the standpoint of global environment conservation, by replacing the conventional wet cleaning and dry cleaning methods that consume large amounts of pure water, chemicals, air, electric power, etc. with the method of the present invention, It can also contribute significantly to conservation.

[0019]

EFFECTS OF THE INVENTION According to the adhesive tape for removing foreign matter and the method of removing the same according to the present invention, there is no problem of static electricity generation due to the adhesive tape, and the foreign matter adhering to the semiconductor wafer can be removed at a high removal rate. Since it can prevent electrostatic breakdown of semiconductor wafers,
It can greatly contribute to the improvement of the yield and reliability of semiconductor devices. Further, compared to other conventional cleaning methods, a contribution effect in terms of global environment conservation can be obtained.

[0020]

EXAMPLES Next, examples of the present invention will be described to more specifically describe.

Example 1 A nonionic surfactant-based antistatic agent was applied to one surface of a polyester support film having a thickness of 50 μm, and an antistatic treatment was applied thereto. The solution was applied and heat-crosslinked at 120 ° C. for 3 minutes to prepare a pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a thickness of 20 μm. The adhesive strength of this adhesive tape to a silicon wafer (mirror surface) is measured according to JIS Z-0237. 18
0 degree peeling adhesive strength (at room temperature, peeling speed 300 mm / min)
The width was 155 g / 20 mm. Further, the surface resistivity (ASTM D-257 of the antistatic treated surface of this adhesive tape
) Was 5.9 × 10 ⁹ Ω / □.

Next, a 5 inch silicon wafer (a mirror wafer without a circuit pattern) having no foreign matter having a size of 0.2 μm or more is passed through a predetermined process (ion implantation process process) to remove the foreign matter. Laser surface inspection device [LS-500 manufactured by Hitachi Electronics Engineering Co., Ltd.]
0; a device capable of counting the number of foreign matters only on the mirror surface of a silicon wafer],
The number of foreign matters having a size of 2 μm or more was counted. In addition,
In order to count the foreign matters adhering to the front and back of the wafer, the same inspection was performed for two cases in which the mirror surfaces were reversed.

On the mirror surface of the silicon wafer thus attached with the foreign matter, the adhesive tape produced by the above-mentioned method is
Stick it with a hand roller, leave it for 3 minutes,
The adhesive tape was peeled off and washed. After this cleaning, the number of foreign matters having a size of 0.2 μm or more attached to the mirror surface was counted again using the laser surface inspection device. The foreign matter removal rate was calculated from the number of foreign matter after cleaning by this sticking and peeling operation and the number of foreign matter before cleaning. The series of work was performed in a class 10 clean room (temperature 23 ° C., humidity 60%). The results are shown in Table 1 below.
(Wafer surface) and Table 2 (Wafer back surface).

Example 2 As an antistatic treatment, a pressure-sensitive adhesive tape was prepared in the same manner as in Example 1 except that aluminum as a conductive material was vapor-deposited to a thickness of 1,000 Å on one surface of a polyester support film. It was made. The adhesive strength of this tape was the same as in Example 1, but the surface resistivity (ASTM
(According to D-257) was 1 × 10 ² Ω / □.
Using this tape, the foreign matter removal rate was measured in the same manner as in Example 1. The results were as shown in Tables 1 and 2 below.

Comparative Example 1 An adhesive tape was prepared in the same manner as in Example 1 except that one surface of the polyester support film was not subjected to any antistatic treatment.
I made a cup. The adhesive strength of this tape was the same as in Example 1, but the surface resistivity (AST
(According to MD-257) was 2.8 × 10 ¹⁵ Ω / □. Using this tape, the foreign matter removal rate was measured in the same manner as in Example 1. The results were as shown in Tables 1 and 2 below.

[0026]

[Table 1]

[0027]

[Table 2]

As is clear from the results of Tables 1 and 2, the adhesive tapes of Examples 1 and 2 of the present invention are less likely to cause redeposition of suspended particles due to generation of static electricity. It is clear that the foreign matter attached to the front surface and the back surface of the silicon wafer can be removed at a higher removal rate than the adhesive tape of Comparative Example 1.

Incidentally, the above-mentioned Examples 1 and 2 and Comparative Example 1
The cleaning method shown in 1 is applied to a predetermined semiconductor wafer manufacturing process, and the yields of semiconductor devices finally obtained are tabulated. As a result, the methods of Example 1 and Example 2 are different from those of Comparative Example 1. By comparison, it was found that the yield increased by about 4%. Further, as a result of examining the electrostatic breakdown occurrence rate of the semiconductor device, it was 0% by the method of Example 1 and Example 2, but was 3% by the method of Comparative Example 1.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of an adhesive tape for removing foreign matter of the present invention.

[Explanation of symbols]

 1 Adhesive tape 11 Support film 12 Adhesive layer

Claims (2)

[Claims] 1. An adhesive tape for removing foreign matters attached to a semiconductor wafer, which is obtained by subjecting an adhesive tape comprising a support film and an adhesive layer to an antistatic treatment. 2. The adhesive tape according to claim 1 is attached to the front surface and / or the back surface of a semiconductor wafer, and then a peeling operation is performed to adhere foreign substances attached to the front surface and / or the back surface of the semiconductor wafer. A method for removing foreign matter adhering to a semiconductor wafer, which comprises adsorbing the agent layer surface to remove it from the semiconductor wafer.