JPS61208051A - Reduced projecting and exposing device - Google Patents

Abstract

PURPOSE:To improve the acceptance ratio of a semiconductor element on a wafer and the work efficiency by detecting automatically dust on a wafer holding stand for holding the wafer and removing it automatically. CONSTITUTION:A laser beam 2 coming out of a laser beam irradiating device 1 scans the dust 3 on the wafer holding stand 5, which adsorbs the wafer coated with a photoresist, and detects the dust 3 with the aid of a change in the incident light quantity on a light receiving sensor 4 following the scan. The scanning of the laser beam is stopped, simultaneously with the detection of the dust 3 and an ionized gas flow 9 is supplied from an ionized gas flow nozzle 7 to the dust, thereby releasing the electromagnetic attachment of the dust 3. Afterward, a sufficiently accelerated gas blow 10 is ejected to the dust 3 by a gas blow nozzle 8, and the dust 3 is carried in discharging port 11. Thus the acceptance ratio of the semiconductor element and the work efficiency can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reduction projection exposure apparatus, and more particularly to a method for detecting dust on a wafer holder thereof and a method for removing the same.

[Conventional technology]

Conventionally, automatic detection and removal of blood dust on a wafer holder in a reduction projection exposure apparatus has not been performed. Dust control is primarily based on the presence or absence of defects appearing in the photoresist pattern on the wafer formed after exposure.

[Problem that the invention seeks to solve]

A reduction projection exposure system performs exposure processing to transfer the pattern on the reticle onto the photoresist coated on the wafer, but at this time, the transferred image of the reticle pattern must be focused extremely accurately on the photoresist. As a matter of fact, the tolerance of the focus is within several μm. Now,
The wafer coated with photoresist must be adsorbed by a vacuum or other means to the holder that is used to adsorb and feed it, and it must be completely flat. However, if there is dust on the holder, the shape of the dust is reflected on the photoresist surface on Ueno 1-. The surface of the photoresist on the surface of the dust has a correspondingly raised black ink, and if it exceeds the focus tolerance, there is a high possibility that the transferred image in that area will be defective.

However, conventionally, dust on the wafer holding table has been managed only by checking the presence or absence of defects in the photoresist pattern on the wafer, which is formed after the exposure process.・-The quality of the non-defective semiconductor devices was reduced. In addition, work efficiency has been reduced due to re-exposure processes such as peeling and coating of the photoresist on the wafer.

Means for Solving Problem C] The reduction projection exposure apparatus of the present invention automatically detects dust on a holding table that attracts a wafer coated with photoresist by, for example, scanning with a laser beam, It has an automatic dust mechanism that uses an ionized gas flow to neutralize the dust to alleviate strong adsorption, and further removes the dust using a high-pressure gas jet.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIGS. 1(a) and 1(b) are detailed explanatory views of the present invention, FIG. 1(a) is a side view of an automatic dust detection and automatic removal mechanism, and FIG. 1(b) is a perspective view.

This reduction projection exposure system automatically detects dust.

Automatic removal occurs in the following order: First, XY stage 6
The wafer holding table 5 installed above is moved into the dust automatic detection and automatic removal mechanism section according to some instructions.

There, the wafer holding table 5 installed on the XY stage 6 is moved parallel to the straight line connecting the laser beam irradiator 1 and the light receiver 4, and the laser beam 2 is scanned in a direction perpendicular to the moving direction. The entire surface of the wafer is scanned by the light receiving sensor 4 which detects the reflected beam from the wafer holding table surface, and when the reflection point of the laser beam 2 on the wafer holding table overlaps with the dust 3, the light receiving sensor 4 Automatically removes dust3 due to changes in the amount of light incident on the
Detect. At the same time as this dust 3 is detected, the movement of the wafer holding table 5 is stopped, and an ionized gas flow 9 is supplied to the dust from the ionized gas flow nozzle 7 to alleviate the electrostatic adhesion of the dust 3. . At the same time, it is provided facing the ionized gas flow nozzle 7 and the gas jet nozzle 8,
The exhaust port 11 that can take in the gas flow is also opened. After the electrostatic adhesion of the dust 3 is sufficiently relaxed, a sufficiently accelerated gas jet 10 is injected onto the dust by the gas jet nozzle, and the dust 3 is guided into the exhaust boat 11. After a certain period of time, the gas jet 10 is stopped, and after a further certain period of time, the ionized gas flow 9 and the exhaust port 11 are also released, and at the same time, the wafer holding table 5 resumes its movement after being slightly reversed, and the dust is removed automatically. Detection is also restarted.

In this process, the dust adhering to the wafer holder is removed, and thereby any defects caused by the dust on the reduced projection transfer image of the reticle pattern formed on the wafer holder can be removed.

〔Effect of the invention〕

As explained above, the present invention automatically detects the presence or absence of dust on the holder immediately before exposing a wafer coated with photoresist, and automatically removes the dust.
By keeping the photoresist surface flat during exposure processing and making it possible to expose a reduced projection image with a uniform focus, it is possible to improve the yield rate of semiconductor devices and improve work efficiency.

[Brief explanation of the drawing]

Figure 1(a) is a side view of the automatic dust detection and automatic removal mechanism.
(b) shows a perspective view. In addition, in the figure, 1... Laser beam irradiator, 2...
...Laser beam, 3...Dust, 4.
..... Light receiving sensor, 5 ..... Wafer holding table, 6 ..... XY stage, 7 ..... Ionized gas flow nozzle, 8 - ..... Gas jet Nozzle, 9.
. . . ionized gas flow, 10 . . . gas jet, 11 . . . exhaust port.

Claims (2)

[Claims] (1) The wafer is held in a reduction projection exposure apparatus in which a wafer coated with photoresist is attracted to a wafer holding table, a pattern on a reticle is projected in a reduced size, and the reduced pattern is formed by direct exposure. A reduction projection exposure system that uses a laser beam to automatically detect dust on a wafer holding table. (2) The reduction projection exposure apparatus according to claim (1), further comprising means for automatically removing the dust.