JPH0695366A - Method for washing phase shift mask - Google Patents

Abstract

PURPOSE:To decrease the damages to be given on the surface of wiring patterns and to effectively remove foreign matter by passing the phase shift mask under water flow having ultrasonic vibrations in horizontal, perpendicular or other positions. CONSTITUTION:The water flow 1 having the ultrasonic vibrations is formed by using, for example, 'High Megasonic US Shower (R)' produced by Kaijo Co., and applying 95kHz ultrasonic vibrations to the water. The phase shift mask 2 arranged parallel on a transporting machine 3 is passed through this water flow. The water molecules having the ultrasonic vibrations vibrate the foreign matter intruding into the recessed parts of the mask. The foreign matter is thereby separated and removed from the mask together with the washing water flow. The resticking of the foreign matter once removed from the substrate is prevented by the water flow and the sticking of the foreign matter is decreased as compared with the conventional methods. As a result, the foreign matter on the surface is effectively removed without giving serious damages on the wiring patterns of the phase shift mask 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to cleaning of a phase shift mask utilizing the phase difference of illumination used for manufacturing semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, formation of a fine pattern in a solid-state element such as VLSI has been mainly performed by a microexposure projection method. The above method uses a projection optical system to reduce and image the light transmitted through a photomask on which a magnified wiring pattern is drawn on a resist-coated substrate.
The wiring pattern is transferred.

However, in recent years, as the density of patterns has increased, the intervals between the patterns have become smaller, and the wavelengths of the light source have come closer to each other, which lowers the resolution and contrast of the projected image. Phase shift masks have been proposed, as shown in.

Conventionally, various cleaning methods have been used for removing foreign matters. A scrubbing method for rubbing foreign matters by applying a rotating brush to the substrate surface, a high pressure for ejecting high-pressure water toward the substrate surface. There is a law. However, Figure 2,
As can be seen in comparison with FIG. 3, the phase shift mask
Since the shifter material for introducing the phase difference is formed on the photomask, the step difference of the pattern is large as compared with the normal photomask, and it is difficult to remove the foreign matter entering the recess. For example, the film thickness of a normal mask is about 1000 Å, whereas the film thickness of a phase shift mask is about 5000 Å, and the depth of the concave portion of the pattern becomes deep. Further, since the wiring pattern of the phase shift mask is finer than that of a normal photo mask, when a strong force of scrubbing or high pressure is applied during cleaning, the wiring pattern may be chipped or dropped. It was the cause of the new defect.

Further, conventionally, as an ultrasonic cleaning method, an ultrasonic wave generator is installed under a dip tank, bubbles are generated in the tank by using a frequency of about 100 kHz, and the force when the bubbles burst is used. There is a method of removing foreign matter, but the bubbles were large in the pattern gap, and the effect was extremely weak against foreign matter in the recesses.

[0006]

SUMMARY OF THE INVENTION The present invention provides a method for cleaning a phase shift mask which eliminates the above defects, reduces damage to the wiring pattern surface, and effectively removes foreign matters. Is.

[0007]

According to the present invention, in a step of cleaning a phase shift mask, the phase shift mask is passed at a horizontal or vertical position under a water flow having ultrasonic vibrations. Is the cleaning method.

[Action]

According to the present invention, in the step of cleaning the phase shift mask, the water molecules having ultrasonic vibration are removed from the foreign matter entering the mask concave portion by allowing the cleaning water having ultrasonic vibration falling from above to pass under the water flow. By applying vibration, foreign matter can be separated and removed from the mask along with the cleaning water flow, and no strong force is applied as compared with the conventional cleaning method, so there is no damage such as chipping or dropping of the wiring pattern.

[0009]

EXAMPLES Examples will be described below with reference to the drawings. FIG. 1 is a side view for explaining an embodiment of the cleaning method of the present invention. Create a belt-like water stream from above,
A high-megasonic US shower manufactured by Kaijo Co., Ltd. was used to apply ultrasonic vibration of 950 kHz to create a water stream 1 having ultrasonic vibration. The phase shift mask 2 having a recess width of 0.1 μm and a depth of 7,000 Å horizontally arranged on the carrier 3 under this water flow has a carrier speed of 0.5 cm / sec and a water amount of 10 to 15 l / mi.
Passed at n. The foreign matter once removed from the substrate did not reattach due to running water, and the foreign matter adhesion was reduced compared to the conventional method, and there was no pattern damage.

[0010]

According to the present invention, it is possible to effectively remove foreign matter on the surface without causing a large damage to the wiring pattern of the phase shift mask.

[Brief description of drawings]

FIG. 1 is a side view illustrating an embodiment of a cleaning method of the present invention.

FIG. 2 is a conceptual sectional view of an example of a phase shift mask.

FIG. 3 is a conceptual sectional view of a conventional photomask.

[Explanation of symbols]

 1 Water Flow with Ultrasonic Vibration 2 Phase Shift Mask 3 Carrier 4 Light-Shielding Layer (Chromium) 5 Shifter Material 6 Stopper Layer 7 Glass Substrate 8 Foreign Material

Claims (1)

[Claims] 1. A method of cleaning a phase shift mask, which comprises passing the phase shift mask under a stream of water having ultrasonic vibrations.