JPH046831A - How to lift and dry the base - Google Patents

Abstract

PURPOSE:To adjust the surface tension of mixed water, to pull up and dry a substrate so as to match its surface state and to enhance a drying quality by a method wherein a surface-active agent is mixed with pure water. CONSTITUTION:At a drying system which uses pure water, a substrate is pulled up from the pure water at a very slow speed, waterdrops which have adhered to the substrate are removed as much as possible by utilizing the surface tension of the pure water, and residual moisture is dried completely by the heat capacity of the substrate or by an auxiliary means such as a hot air, a heater or the like. At the drying system, a surface-active agent is mixed with the pure water. For example, a silicon wafer whose prescribed processing operation and cleaning operation have been finished is immersed for one minute in a mixed liquid of a water-soluble nonionic surface-active agent of polyoxyethylene alkylphenol ether with deionized ultrapure water whose number of particles of 0.2mum or higher in the liquid is one piece or lower per cc; it is pulled up at a uniform speed of 3mm/sec. When the surface shape of the substrate is complicated or the surface of the substrate is strongly hydrophobic, the surface tension of the mixed water is lowered furthermore.

Description

Detailed Description of the Invention [Industrial Application Fields] The present invention relates to a pulling drying method used in the drying process after cleaning of semiconductor silicon substrates, photomasks, liquid crystal panel glass substrates, optical lenses, printed circuit boards, etc. Regarding.

[Conventional technology] Conventionally, by pulling a substrate out of pure water at a very low speed, the surface tension of the pure water is used to remove as much water droplets as possible from the substrate, and the remaining moisture is used to increase the heat capacity of the substrate or hot air,
Drying methods using auxiliary means such as heaters have been proposed and implemented.

(JP-A-56-1614s1), (JP-A-6022S1)
3o), (JP-A-6L-270399), (JP-A-65
-677ss) [Problems to be Solved by the Invention] However, in the above-mentioned conventional technology, since pure water with a high surface tension is used for pulling and drying, pure water is difficult to wrap around a substrate with a complex surface shape ( In addition, there is a problem in that it is difficult to remove water droplets that have entered minute portions on the substrate and water droplets that have adhered to jig contact areas.

Furthermore, when a substrate having a hydrophobic surface is pulled out of pure water and dried, water droplets tend to remain on the substrate (stains and smudges remain), which deteriorates the drying quality.

The present invention solves these problems by mixing a high-purity surfactant into pure water, adjusting the surface tension of the mixed water, and pulling and drying according to the surface condition of each substrate. The purpose is to improve drying quality.

[Means for Solving the Problems] The method of pulling and drying a substrate of the present invention uses the surface tension of pure water to remove water droplets adhering to the substrate as much as possible by pulling the substrate out of pure water at a very low speed. The method is characterized in that a surfactant is mixed in pure water in a pure water drying method in which the remaining moisture is completely dried using the heat capacity of the substrate or auxiliary means such as hot air or a heater.

The surfactant may be nonionic, cationic, anionic, or amphoteric as long as it is compatible with the pure water used in combination. It is also possible to mix and use them as long as no precipitation, precipitation, dispersion, etc. occur.

A surfactant mixing ratio of 3% by weight is sufficient, and higher concentrations may cause stains and stains caused by the surfactant.
Unevenness will occur.

[Effect: When a water-soluble surfactant is mixed into pure water, the surface tension is reduced. If the surface shape of the substrate is complex (substrate with many minute irregularities on the surface) or the substrate surface is highly hydrophobic, by lowering the surface tension, the mixed water will be able to go around to the fine details and the mixed water can be removed. Become.

Since the surfactant has the ability to take in dirt and separate it, the cleanliness is improved and the occurrence of stains is eliminated [Examples] The present invention will be explained in detail below based on Examples.

(Example 1) P-type B-doped (specific resistance 1.6-1.8 MΩcrn),
A silicon wafer with a diameter of 5 inches (1, 0, 0 side),
Colloidal silica (100-200X, S
It was mechanochemically borated with a solution of i0.50% by weight, pH 11) and polished by about 20 μm from one side. The machining surface pressure during this machining is 1001/-Borisher rotation speed is 40
The silicon wafer immediately after processing, which was at rpm, was cleaned in the next step.

(1) Immersion in pure water 1 minute at room temperature (2) Immersion in H2BO3:HtOt (volume ratio 4:1)
1 minute 80℃ (6) Pure water immersion 1 minute room temperature (4) NH40H:H,O,:H,O (volume ratio 1:1
:5) Immersion 5 minutes 70℃ (5) Pure water immersion 1 minute Room temperature (6) ay:n, o (volume ratio 1:10) Immersion 1 minute Room temperature (7) Pure water immersion 5 minutes Room temperature This silicon wafer , a water-soluble nonionic surfactant, polyoxyethylene alkylphenol ether, p
oE(2o) nonylphenol ether and 02 in the liquid
It was immersed for 1 minute in a mixture of deionized ultrapure water (weight ratio 1:1000) in which the number of particles larger than μm was 1 or less per Icc, and then pulled up at a uniform speed of 5 mn and 7 seconds. No water droplets were found attached to the obtained silicon wafer. Moreover, no appearance defects such as stains or unevenness were observed.

(Example 2) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer is treated with a water-soluble anionic surfactant,
Polyoxyethylene alkyl ether phosphate ester (
Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Pricesurf A215
0), and the number of particles larger than 02 μm in the liquid is 1 per 1 cc.
A mixture of deionized ultrapure water (weight ratio 1:100)
The sample was immersed in the water for 1 minute and then pulled out at a constant speed of 5w for 7 seconds.

No water droplets were found attached to the obtained silicon wafer.

Moreover, no appearance defects such as stains or unevenness were observed.

(Example 5) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer was coated with a water-soluble cationic surfactant polyoxyalkylene alicyclic amine (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.,
A mixture of product name Lamiblue) C-2) and deionized ultrapure water in which the number of particles of 02 μm or more in the liquid is 1 or less per 1 cc.
(weight ratio 1:5.QO) for 1 minute, 5 w 7
It was pulled up at a constant speed of seconds. No water droplets were found attached to the obtained silicon wafer. Moreover, no appearance defects such as stains or unevenness were observed.

(Example 4) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer was coated with a water-soluble amphoteric surfactant, amidobetaine type (manufactured by NOF Corporation, product name: Niasan 7/
> EDIF-R) and 00.2 pm in liquid
Immerse for 1 minute in a mixture of deionized ultrapure water (weight ratio, 1zooo) in which the number of particles is 1 or less per CC,
It was pulled up at a constant speed of fi/second. No water droplets were found attached to the obtained silicon wafer. Moreover, no appearance defects such as stains or unevenness were observed.

(Comparative Example 1) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer was mixed with a mixture of the same surfactant and deionized ultrapure water as in Example 1 (however, the weight ratio was X:1O).
The sample was immersed in water for 1 minute, and then pulled out at a constant speed of 5 minutes per second. Although no water droplets were attached to the obtained silicon wafer, appearance defects such as stains and unevenness were observed.

(Comparative Example 2) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer was washed with a mixture of the same surfactant and deionized ultrapure water as in Example 2 (however, the weight ratio was 7:100).
) for 1 minute, and then pulled out at a constant speed of 5 cm/sec. Although there were no water droplets attached to the obtained silicon wafer, appearance defects such as stains and unevenness were observed.

(Comparative Example 3) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

This silicon wafer is
Immerse for 1 minute in deionized ultrapure water with no more than 1 piece per C,
I pulled it up at a constant speed of 3wx+7 seconds.

Water droplets remained on the obtained silicon wafer.

(Comparative Example 4°) A silicon wafer similar to that in Example 1 was processed and cleaned in the same process.

The number of particles of 0.2 μm or more is 1
It was immersed in deionized ultrapure water for 1 minute or less at 0°C and pulled out at a constant speed of 5 ml/sec.

Water droplets remained on the obtained 7 recon quefer.

By lifting the sample from a mixed solution of deionized ultrapure water and an appropriate amount of water-soluble surfactant in this manner, water droplets were easily removed and there were no appearance defects such as stains or unevenness.

[Effects of the Invention] As is clear from the above, the pulling drying method of the present invention from a solution containing a water-soluble surfactant in pure water can easily remove water droplets and further improve cleanliness. High drying speed is possible.

that's all Applicant: Seiko Epson Corporation

Claims (1)

[Claims] By pulling the substrate out of pure water at very low speed,
In the pure water drying method, water droplets adhering to the substrate are removed as much as possible using the surface tension of pure water, and the remaining moisture is completely dried using the heat capacity of the substrate or auxiliary means such as hot air or a heater. A method for pulling and drying a substrate, characterized in that a surfactant is mixed therein.