JPH06104167A - Manufacture of aligner and semiconductor device - Google Patents

Abstract

PURPOSE:To effectively clean a wafer rear in a photolithography process, to reduce resolution defective of a transcription pattern and to improve yield of a product by providing a removal mechanism consisting of a cleaning part and a drying part which remove a foreign matter attaching to the wafer rear before the wafer is mounted on an exposure position between a wafer supply part and a wafer mount part. CONSTITUTION:A wafer 21 is set in a cleaning cup 28 and attracted by vacuum. Thereafter, cleaning liquid 30 such as pure water and alcohol is guided from a cleaning liquid tank 31 to a rotary disc 32 built in the cleaning cup 28, and is sprayed to a rear of the wafer 21 from a plurality of nozzles 33. Since the rotary disc 32 is rotated by a motor 34 synchronizing with the above, an entire of a rear of the wafer 21 is cleaned and a deposited foreign matter is removed. After cleaning is completed, dry air consisting of inert gas such as nitrogen is sprayed and an entire of a rear of the wafer 21 is dried. Then, the wafer 21 is carried and mounted on a wafer chuck, positioned by an XY stage and exposed by illumination optical system and projecting optical system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device manufacturing technique which is effective for use in a manufacturing process in which flatness of an object to be processed such as a wafer is required. The present invention relates to a technique effective when applied to the technique of exposing the photosensitive material.

[0002]

2. Description of the Related Art One of the important techniques for manufacturing a semiconductor device is a photolithography technique for transferring an element pattern or wiring pattern of an integrated circuit onto a semiconductor wafer.

In this photolithography technique, a semiconductor wafer is coated with a photosensitive material (hereinafter referred to as a photoresist), and light is passed through a reticle or a photomask on which a predetermined light-shielding pattern is formed to apply the photosensitive material. It is a technique for transferring a pattern by projecting it onto a formed semiconductor wafer. A projection exposure apparatus is one of the apparatuses used in this technique.

FIG. 3 is a schematic explanatory view of a conventional projection exposure apparatus. As shown in the figure, the light 3 emitted from the light source 2 of the projection exposure apparatus 1 reaches the light shielding pattern 5 formed on the surface of the reticle 4 after passing through the reflection plate and the lens. The light that has passed through the light shielding pattern 5, that is, the projected image 3a
Then, the surface of the resist-coated wafer 7 set at the exposure position is irradiated with the light and the resist is exposed.

Reference numeral 41 is a wafer supply carrier, 42 is a wafer storage carrier, and 43 is a pre-alignment station.

A technique relating to such a projection exposure technique is described in, for example, Japanese Patent Application Laid-Open No. 51-111076.

[0007]

In recent years, semiconductor integrated circuits have become more and more miniaturized, and the design rule has reached the submicron range. Along with this, the transfer pattern by the projection exposure apparatus is also miniaturized, and the photolithography technique is required to have considerable precision, and the exposure environment is also required to be considerably clean.

In such a situation, even the finest foreign matter causes defects. For example, when exposure is performed with foreign matter attached to the wafer surface, the problem that the resist in the portion where the foreign matter is attached is not exposed is a problem that has existed before and after every miniaturization. Even when foreign matter adheres, when exposing the wafer,
In recent years, it has become clear that pattern transfer is greatly affected.

As shown in FIG. 4, when a foreign material A is caught between a mounting member on which the wafer 7 is mounted, for example, the wafer chuck 8 and the wafer 7, the foreign material A causes the wafer 7 to move. It will be distorted. As a result, the flat portion and the foreign matter A
The area between the reduction lens 6 and the wafer 7
Since the distance to the surface is different, a portion exceeding the depth of focus D determined by the projection lens 6 is generated, and the pattern of the projected image exposed at that portion causes poor resolution. Since the depth of focus for guaranteed resolution is decreasing with the progress of miniaturization, the possibility of defective resolution due to the above phenomenon is increasing. In view of the above, the problem of effective cleaning of the back surface of the wafer in the photolithography process has been found by the present inventors.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a semiconductor device manufacturing technique capable of reducing resolution defects and improving yield by solving the above problems.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0012]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows. That is, the exposure for transferring the light-shielding pattern formed on the desired mask to the photosensitive agent applied to the surface of the exposed object is performed after removing the foreign matter adhering to the back surface of the exposed object.

[0013]

According to the above-mentioned means, the foreign matter adhering to the back surface of the object to be exposed can be removed before being placed at the exposure position, so that the influence of the foreign matter on the object to be exposed can be eliminated. It is possible to prevent defective exposure and defective development of the photosensitive material.

[0014]

1 is a schematic explanatory view of a projection exposure apparatus according to an embodiment of the present invention. The projection exposure apparatus 10 will be described below with reference to the drawings. The projection exposure apparatus 10 is roughly divided into an illumination optical system 11, a projection optical system 12, and a transport system 13. Light 15 generated from the light source 14 of the illumination optical system 11 is applied to a mask (reticle) 19 having a light-shielding pattern 18 formed on the surface of a transparent quartz glass plate via a concave mirror 16, a reflecting mirror 17 and the like. Shading pattern 18
Image, that is, the projected image is the reduction lens 2 of the projection optical system 12.
The image is reduced at 0, and is projected onto the wafer 21 to which the photosensitive agent that is the exposed object is applied.

By the way, the wafer 21 is transferred to the transfer system 13.
A large number of wafers are accommodated in a wafer supply side carrier 22 which is a wafer supply section of the wafer supply unit. Dry.

FIG. 2 is a detailed explanatory view of the cleaning / drying mechanism 24. The wafer 21 is first set in a cleaning cup 28 having an inner diameter smaller than the diameter of the wafer, and is sucked and fixed by a vacuum suction hole 29 on the outer peripheral portion of the cleaning cup 28. Then, a cleaning liquid 30 such as pure water or alcohol
Is guided from a cleaning liquid tank 31 containing the cleaning liquid 30 to a rotary disc 32 built in the cleaning cup 28, and a plurality of nozzles 33 arranged on the rotary disc 32 are attached to the back surface of the wafer 21. It is jetted toward. In synchronization with this, the motor 34 rotates the rotating disk 32 to clean the entire back surface of the wafer 21. By this cleaning, foreign matter attached to the back surface of the wafer 21 can be removed. After the cleaning is completed, the valve 35 is switched from the cleaning tank 31 side to the dry air supply unit 36, and dry air composed of an inert gas such as nitrogen is supplied from the dry air supply unit 36 to the cleaning cup 28 to the plurality of nozzles 33 like the cleaning liquid 30.
Is ejected toward the back surface of the wafer 21, and the rotating disk 32 is rotated by the motor 34 in synchronism with this so that the entire back surface of the wafer 21 can be dried.
After drying, it is sent to the pre-alignment station 24 for coarse positioning.

As described above, the wafer 21 which has been cleaned and dried is transferred and placed on the wafer chuck 27 at the exposure position of the projection optical system 12 by using a transfer means (not shown), and the wafer chuck 24. The fixing means, such as a vacuum suction means, is used for close contact.

After that, the wafer 21 positioned by the XY stage 26 is exposed by the illumination optical system 11 and the projection optical system 12, and the pattern is transferred. Then, the wafer 21 is transferred to the wafer storage side carrier 37 which is a wafer storage section. Will be stored.

According to this embodiment, the following operational effects are exhibited. That is, (1) foreign matter on the back surface of the wafer can be removed in the exposure apparatus immediately before the exposure, so that it is possible to reduce the resolution defect of the transfer pattern due to the foreign matter that has adhered to the back surface of the wafer before the exposure such as the transfer system. it can.

(2) Since the foreign matter on the back surface of the wafer is removed and then the wafer is placed and fixed on the wafer chuck, the foreign matter can be prevented from adhering to the wafer chuck.

(3) Since the defective resolution of the transfer pattern due to the foreign matter on the back surface of the wafer can be reduced, the wafer reproduction rate due to the defective resolution of the transfer pattern can be reduced.

(4) Since defective resolution of the transfer pattern due to foreign matter on the back surface of the wafer can be reduced, the product yield is improved.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, in the embodiment, the pre-alignment station and the cleaning / drying mechanism are provided independently of each other, but if the pre-alignment station is provided with the cleaning / drying mechanism and integrated, the efficiency of the apparatus space can be improved. . Similarly, the wafer chuck may be provided with a cleaning / drying mechanism. In addition, in the embodiment, the foreign matter removal on the back surface of the wafer
Although the cleaning / drying mechanism is used, a method of cleaning by directly contacting the back surface of the wafer with a cloth or a brush, a method of ultrasonically cleaning the back surface of the wafer, or a liquid such as pure water or alcohol is not used, Even if a method of blowing off a foreign substance with high-pressure air is used, the same effect can be obtained.

Further, in the present embodiment, the case where it is applied to the projection exposure technique has been described, but it is needless to say that it can be applied to various exposure apparatuses such as the projection exposure technique, the electron beam direct writing technique and the X-ray exposure technique. is there.

In the present embodiment, the wafer is described as the exposed object, but any material can be applied as long as the plate-like object is coated with a photosensitive agent and exposed.

[0026]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, the finer the pattern on the front surface of the wafer and the narrower the range of depth of focus, the higher the flatness of the wafer is required. come.

Therefore, by removing the foreign matter on the back surface of the wafer to be exposed before exposure, and by making the movement distance of the wafer to the exposure position extremely short,
The risk of exposure with foreign matter on the back surface of the wafer adhered can be minimized, so that defective resolution of the transfer pattern can be eliminated, so product yield can be improved, cost can be reduced, and defective rate can be reduced. It is a thing.

[0029]

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an exposure apparatus that is an embodiment of the present invention.

FIG. 2 is a schematic explanatory view of a back surface cleaning mechanism portion of FIG.

FIG. 3 is an overall configuration diagram of a conventional exposure apparatus.

FIG. 4 is an explanatory diagram of resolution failure due to foreign matter on the back surface of the wafer.

[Explanation of symbols]

1 ... Projection exposure device, 2 ... Light source, 3 ... Light, 3a ...
Projected image, 4 ... reticle, 5 ... Shading pattern, 6 ...
Reduction lens, 7 ... Wafer, 8 ... Wafer chuck, 9
..XY stage, 10..Projection exposure apparatus, 11..Illumination optical system, 12..Projection optical system, 13..Transport system, 14
..Light source, 15 ... Light, 16..Concave mirror, 17..Reflector, 18..Shading pattern, 19..Reticle, 20 ..
・ Reducing lens, 21 ・ ・ Wafer, 22 ・ ・ Wafer supply side carrier, 23 ・ ・ Transfer belt, 24 ・ ・ Pre-alignment station, 25 ・ ・ Cleaning / drying mechanism, 26 ・ ・
XY stage, 27 ... Wafer chuck, 28 ... Cleaning cup, 29 ... Vacuum suction hole, 30 ... Cleaning liquid, 31 ...
・ Cleaning liquid tank, 32 ・ ・ Rotating disk, 33 ・ ・ Nozzle,
34 .. Motor, 35 .. Valve, 36 .. Dry air supply unit, 37 .. Wafer storage side carrier.

Claims (3)

[Claims] 1. An exposure apparatus having a wafer placing section between a wafer supply section and a wafer accommodating section, for transferring a desired light-shielding pattern image formed on a mask onto the surface of the object to be exposed coated with a photosensitizer. An exposure apparatus characterized in that a mechanism for removing foreign matter adhering to the back surface of a wafer is provided between the wafer supply section and the wafer mounting section in the previous period. 2. The exposure apparatus according to claim 1, wherein the removing mechanism includes a cleaning unit and a drying unit. 3. A method of manufacturing a semiconductor device, which comprises an exposure step of transferring a desired light-shielding pattern image formed on a mask onto a photosensitive agent applied on the surface of a wafer, the method being carried out after being carried out from a wafer supply section. A step of mounting the wafer on a mounting member having a flat surface after removing foreign matter adhering to the back surface of the wafer immediately before exposure, and a step of exposing the wafer mounted on the mounting member to an exposure device. A method of manufacturing a semiconductor device, comprising: