JPS59195646A - Method and device for washing mask for semiconductor element manufacture - Google Patents

Abstract

PURPOSE:To securely remove dust, etc. attaching to both sides of a mask by releasing it from an electrostatic attraction state due to mechanical peeling with a rotary brush and an electrolytic soln. CONSTITUTION:A mask 14 is passed through a gap between shower pipes 21, 21' and further, through a gap between rotary brushes 22, 22' made of nylon to wet both sides of the mask 14 with pure water or aq. <=1% ammonia in a washing vessel 20 and to scrub them. An electrolytic soln. flows out from shower pipes 31, 31' in a washing vessel 30, and the mask 13 is passed between these pipes 31, 31' to remove static electricity accumulated during the brush washing and the use of the mask 13. In a washing vessel 40, the mask 12 to be washed is passed through shower pipes 41, 41' and immersed in an isopropanol vessel 42, and again passed through the pipes 41, 41' for spraying isopropanol to substitute an org. liquid for an aq. soln. The mask 11 to be washed fed to a washing vessel 50 is brought into contact with freon 51 vapor, cleaned with the vapor, and rapidly dried while passing near a cooler 53.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for cleaning a lightless mask used for manufacturing semiconductor devices such as ICs, LSIs, and VLSIs.

``In the semiconductor device manufacturing process, the process that has the greatest control over economic efficiency is the optical exposure process. Conventionally, defects in optical masks and foreign matter adhesion from the semiconductor substrate to the mask during the optical exposure process have occurred. It is being considered.

In particular, the change in exposure technology from a contact non-light system to a projection exposure system or a reduction projection line light system has significantly reduced manufacturing costs since there is no transfer of foreign matter from the semiconductor substrate to the mask.

However, since the light exposure method irradiates the mask with deep ultraviolet or ultraviolet rays, it is difficult to accumulate electrostatic charge on the conductive layer or semiconductor layer of the required pattern for light shielding, which is formed on one main surface of the transparent substrate of the mask. However, airborne dust particles are attracted to the surface of the mask before and after use. In conventional mask cleaning machines, this absorbed dust is cleaned on one or both sides (front and back) using neutral detergent, pure water, jet scrub, etc.
With the conventional device, it was also impossible to guarantee that no dust would come out below 59[S] of the transferred pattern chip. Furthermore,
For reduction projection exposure equipment, there is a demand for a reticle/mask cleaning machine that has defects of 3μ or more * @ 0'' and does not generate stains or dirt when the cleaning liquid dries. Moreover, a mask cleaning technique with good workability was unknown.

SUMMARY OF THE INVENTION An object of the present invention is to provide a mask cleaning method and equipment that is highly workable and that reliably removes dust and the like adsorbed on the front and back surfaces of a mask.

Another object of the present invention is to provide a reticle/mask cleaning method and apparatus which can completely remove deposits of 3 μm or more from a reticle mask used in a reduction projection exposure apparatus.

According to the present invention, a method and apparatus for cleaning an optical exposure mask for manufacturing semiconductor devices, which has a conductive or semiconductive light-shielding pattern of a desired shape on one main surface of a transparent substrate made of glass or quartz, are realized. . That is, in the first step of the light exposure mask of the present invention, the front and back surfaces of the substrate are coated with water, a weakly acidic aqueous solution containing carbonic acid, phosphoric acid, hydrochloric acid, etc., a weakly alkaline aqueous solution such as a dilute solution of ammonia, or alcohol. get wet with liquids such as Next, in the second step, the mask is passed between a pair of rotating books, and a rotating plaque removes any adsorbed matter, deposits, or dirt from the front and back surfaces of the mask.

Mechanically remove stains, etc. In the third step, a shower-like electrolytic solution is sprayed on the front and back surfaces of the mask to wash it away, and in the fourth step, the front and back surfaces of the mask wet with this electrolyte are treated with an alcohol-based solution to remove the aqueous liquid remaining on the mask from the previous step. Wash with organic liquid. Finally, in the fifth step, the material is passed through a mask in 7 Leon type or alcohol type vapor, and then placed in a barrel in a dry atmosphere to complete the cleaning process.

The mask cleaning method of this invention uses a rotating brush to mechanically remove deposits, adsorbed materials, sticky materials, etc. from the front and back surfaces of the mask, and then uses an electrolytic solution to release foreign materials on the mask surface from the state of electrostatic adsorption. It can be washed away. Further, when an alkaline solution such as ammonia, caustic soda, or caustic potash is used as the electrolytic solution, fingerprints, oily dirt, etc. adhering to the mask to be cleaned can be removed. Furthermore, since the aqueous solution remaining when cleaning the mask is replaced with alcohol and steam cleaning with organic gas is followed by drying, the drying speed is fast and there is no flea residue that can be seen when water bath liquid is naturally dried. When using a hydrophilic electrolyte such as ammonia water, phosphoric acid, or caustic potassium as the electrolyte, the cleaning effect on the surface of the mask to be cleaned is improved.
) is remarkable.

Next, embodiments of the present invention will be described with reference to the drawings.

The figure is a model diagram of a mask cleaning apparatus that implements an embodiment of the present invention. In this embodiment, a semiconductor device manufacturing mask 11, 12, 13° 14f which coats a chromium light-shielding pattern of a desired shape on one surface of a transparent quartz substrate: four cleaning tanks 20, 30° 40 which are cleaned in the order of steps .50. Each cleaning tank can simultaneously clean the front and back surfaces of the mask to be cleaned, and therefore the mask is held at its end with a suitable jig and is moved up and down within each cleaning tank.

In the first cleaning tank 20, in order to wet the front and back surfaces of the mask 14 to be cleaned with pure water or 1% or less ammonia water, the mask passes through a gap between a pair of opposing shower pipes 21 and 21'. The mask that has passed through this also passes through a gap between a pair of rotating nylon brushes 22 and 22', and its front and back surfaces are scrubbed. The rotational direction of this rotating brush is the direction in which it sweeps from the top to the bottom of the mask surface, as shown in the figure. In addition, the one-rotation brush rotates from the center toward the mask surface with pipes 21 and 2.
Liquid similar to 1' may be ejected. In this manner, this cleaning tank processes the first step of wetting the front and back surfaces of the mask, and the second step of mechanically sweeping out the front and back surfaces of the mask with a rotary book.

Next, the mask to be cleaned is subjected to shower cleaning with electrolyte in the second cleaning tank 30. In this cleaning tank 30, unlike the previous process, the electrolyte is always connected to the pair of shower pipes 31 and 31'.
During this period, the electrolytic solution flows through the mask 13, thereby causing the electrolytic solution to flow on the front and back surfaces of the mask. This tank 30
In the third step, the static electricity accumulated during the previous step of plaque cleaning and mask use is removed, and the dust on the front and back surfaces of the mask is released from the static electricity and removed using a flowing electrolyte.

As the electrolytic solution here, ammonia water, dilute hydrochloric acid, or carbonated water having a concentration of about 0.1% to about 2% is usable. On the other hand, the shower pipe 21.2 of the first cleaning tank 20 in the previous process
When using an electrolyte with a higher cleaning effect instead of pure water as the effluent from 1', use a hydrophilic electrolyte of 5 or less, such as ammonia, caustic soda, phosphoric acid, or sodium phosphate, and use a one-turn brush 22, 22'. It is preferable to enhance the scrub cleaning effect. Further, the electrolyte in the shower pipe 31, 31' of the second cleaning tank 30 may be switched to pure water at the end of cleaning, if necessary, to rinse and wash away the electrolyte on the front and back surfaces of the mask. The concentrations of the electrolytes mentioned above are given in weight percent.

In the third cleaning tank 40, the mask 12 to be cleaned passes between a pair of shower pipes 41 and 41' and is immersed in an isopropyl alcohol tank 42 in order to replace the aqueous solution used in the previous process with an organic liquid. The isopropyl alcohol from the shower pipes 41 and 41' is ejected again and sent to the fourth cleaning tank 50.

As the alcohol here, other alcoholic chemicals such as methanol and ethanol can be used. The alcohol tank 42 is
Alcohol is supplied from the shower pipes 41, 41', overflows from the four walls and flows out to the outside.

The mask 11 to be cleaned sent to the fourth cleaning tank undergoes steam cleaning by heating 7 Leon 51 to 50 to 60°C by the heater 52 and coming into contact with the Freon vapor obtained on the liquid surface. . Furthermore, when the mask is taken out upwardly through the vicinity of the cooler 53 provided at the top of the kernel tank 50, it is rapidly dried. The cooler 53 has a temperature of 10 to 28°C in a gold Ja”z pipe.
By allowing water to flow through the tank, Freon vapor generated at the bottom of the tank is prevented from flowing out of the tank, reducing Freon consumption and rapidly drying the mask. This process of steam cleaning with organic chemical gas and then drying can also be done with isopropyl alcohol, and the same effect can be obtained by changing the temperature settings of the heater and cooler.

Mask cleaning apparatus 100 of FIG. 1 for carrying out the embodiments described above.
There are four cleaning tanks 20 and 3 that sequentially process masks to be cleaned.
0,40.50, and has a mechanism for sending masks to these cleaning tanks as well as a mechanism for raising and lowering masks in 6 tanks. Furthermore, the six tanks are externally shielded from the outside air, and clean air that has passed through a dust removal filter 61 and an ionized ion shower 62 is introduced therein to maintain cleanliness inside the device and prevent the generation of static electricity.

According to the embodiments described above, deposits and dirt on the surface of the mask to be cleaned are substantially completely cleaned from both the front and back surfaces by scrubbing, electrolyte cleaning, organic gas cleaning, and rapid drying. Furthermore, compared to conventionally known cleaning processes, the processing time is short, the workability is excellent, and the cleaning process is thorough and rational. Therefore, the cleaning method of this embodiment is dust-free and pollution-free cleaning i! This method is particularly advantageous for cleaning reticle masks.

[Brief explanation of drawings]

The figure is a longitudinal sectional view of a mask cleaning device for explaining one embodiment of the present invention. ioo...Cleaning device, 11, 12, 13.14
...Mask, 20...First cleaning tank,
30...Second cleaning tank, 40...Third cleaning tank, 50...Fourth cleaning tank, 21.21
' , 31.31' , 41, 41'... Shower pipe, 22.22'... Plaque.

Claims (2)

[Claims] (1) A method for cleaning a mask for semiconductor device manufacturing having a light-shielding pattern of a desired shape on one main surface of a transparent substrate, which includes a first step of wetting the front and back surfaces of the mask with a liquid, and a pair of rotations of the mask. A second step of passing the electrolyte through the middle of the brush, a third step of flowing the electrolytic solution to the front and back surfaces of the mask, and a fourth step of flowing the organic liquid to the front and back surfaces of the mask. A method for cleaning a mask for semiconductor device manufacturing, comprising the steps of: and a fifth step of bringing the front and back surfaces of the mask into contact with organic gas vapor and then drying them. (2) A means for holding at least a portion of the periphery of a mask for manufacturing semiconductor devices, which has a light-shielding pattern of a desired shape on one main surface of a transparent substrate, and a machine that then wets the surface of the mask with a liquid and brushes it. a means for spraying an electrolytic solution on the front and back surfaces of the mask, a means for spraying an organic chemical on the front and back surfaces of the mask, and a means for steam cleaning and drying the mask with an organic gas. Cleaning equipment for masks used in element manufacturing.