JPS6057623A - Non-contact sealing device - Google Patents

Abstract

PURPOSE:To increase the degree of adhesion between a wafer and a mask by forming a gas blow-off hole to a section opposite to a mask holder for a wafer chuck and forming a gas current between the opposite section. CONSTITUTION:A mask 3 is positioned, and fixed to a backup plate 2 by vacuum suction by vacuum holes 7. Nitrogen gas N2'' is forwarded from ring-shaped forwarding holes 14a, 14b formed around a wafer chuck 5, and a gas curtain is formed between the chuck 5 and the mask 3. In the gas N2'', a gas forwarded toward the central section of the chuck 5 is discharged by the vacuum suction of a back pressure forming groove 15, and a gas forwarded toward the outside is discharged as a total discharge gas TN2. Consequently, the intrusion of the outside air can be prevented effectively. The mask 3 is not bent on exposure work even when push-up pressure by a piston 6 is high because there is the plate 2. Accordingly, since the degree of adhesion between a wafer and the mask is increased, resolution is improved, and accuray on an alignment is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a non-contact seal that is effective when applied to mask aligners for photographic processing, particularly mask aligners for improving the density Ii and alignment accuracy between a wafer as a processing object and a mask. It's about resourcefulness.

2. Description of the Related Art Mask aligners (mask alignment devices) used in the manufacture of semiconductor devices have problems with resolution and alignment accuracy because they handle minute patterns. The quality of this resolution is related to the degree of adhesion between the wafer and the mask, and the alignment accuracy is greatly affected by pitch deviation.

By the way, conventionally known glazed mask aligners include those using a push-up contact method and those using a vacuum contact method, each having a 2λ circularity A. Each of these has −
Cho Ilgi remains in office. The above two types of close contact methods will be sequentially explained below with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing the structure of a mask aligner using the push-up contact method. In the figure, 1 is a mask holder that holds a mask 3 at its periphery, and 2 is a mask holder 1.
A bank-up plate 1 made of glass with 1 degree reinforcement for holding the mask is installed so as to be in contact with the inner edge of the mask and the back side of the mask, and 5 is a wafer 4 coated with photoresist.
A wafer chuck for facing the mask 3,
6 is a piston that pushes up the wafer chuck. In addition,
3 is a pin for positioning the mask. This device Fft
is used as follows.

Mask 3 consists of mask holder 1 and banokanop plate 2.
It is fixed to the backup plate 2 by vacuum (■a.) suction through the suction hole 7 provided over the area. Ueno 4 is the nitrogen gas N delivered from Ueno chuck 5.
, ′ are pressed against the mask surface. Immediately before the start of exposure work, the delivery hole 8 provided at the peripheral edge of the Ueno chuck 5 is opened.
Chin gas N2 is sent out from the tank, and a gas curtain is formed around Ueno. After that, light is applied from the back of the backup plate 2 to perform a light drop operation. At this time, the photoresist film on the wafer undergoes a crosslinking reaction due to the ultraviolet light irradiation 1, and this reaction causes the nitrogen gas N2''
' is generated from the photoresist film. Generated chlorine gas N2
The mask, Ueno, and the total emission of Chin gas TN,
It will be mixed in and pushed out.

By the way, the generated nitrogen gas N2 has to pass through the narrow gap between the mask and the Ueno chuck, where the Chin gas N2 for Ueno and adhesion and the Chin gas N2' for the gas curtain are present. Therefore, the tiny amount and pressure of the generated nitrogen gas N2 cannot easily escape to the outside, and remains trapped between the wafer and the mask. As a result, the gap between the wafer and the mask becomes loose, making it impossible to maintain a close contact with the mask, resulting in a disadvantage that the resolution deteriorates.

FIG. 2 is a longitudinal sectional view showing the structure of a mask aligner using a vacuum contact method. In the same figure, ℃ 1 is a mask holder, and a mask 3 is placed on the inner periphery F and the upper part, and a vacuum (■ao 1) suction hole 0 for fixing this mask and a gas curtain holder. It has a delivery hole J1 for delivering the tin gas N2. 5 is a wafer chuck that holds the wafer 4 and makes it face the mask. The diameter of this wafer chuck 5 is made smaller than the diameter of the wafer 4. The wafer 4 and the wafer chuck 5 are sealed by a piston 6 and a seal ring provided around the periphery of the piston. This sealed room R is brought into a negative pressure state by drawing a vacuum (V, o2) with a vacuum suction Jl 12 provided in the mask holder 2.

In the above apparatus, the sealing chamber R becomes a nitrogen gas atmosphere due to the gas curtain of nitrogen gas N2 sent out from the delivery hole 11, and becomes a negative pressure state by evacuation at the suction hole 12, so that the wafer and the mask is atmospheric pressure F1
The relative pressure between the pressure F2 and the push-up pressure F2 of the piston is sufficient to ensure close contact. In addition, since the sealing chamber R is under negative pressure and the diameter of the chuck is smaller than the diameter of the wafer, the nitrogen gas N generated from the photoresist film during exposure is absorbed by the adsorption nitrogen gas N2' and the gas curtain N2. ' is easily discharged without being hindered by Therefore, it is assumed that the initial state of close contact between the wafer and the mask is maintained even during exposure.

However, in the vacuum contact method described above, the horizontal state of the mask is maintained by the balance between the atmospheric pressure F and the piston pressure F2.
While the atmospheric pressure F1 is an equally divided load, the piston pressure is a concentrated load, and the normal piston pressure F2 is larger than the atmospheric pressure 11, causing the mask to bend into a convex shape. At this time, the Ueno film is also pend at the same time, and the pitch dimension with the pattern printed in the previous photoresist process is out of order, resulting in a pitch misalignment. This results in a disadvantage that alignment accuracy deteriorates.

One object of the present invention is to maintain the interior in a reduced pressure state while
An object of the present invention is to provide a sealing method that can realize an aligner etc. that allows alignment.

In order to achieve the above object, an embodiment of the present invention includes a mask holder that holds a mask in the same layer, a bank amplifier plate that is in contact with the inner edge of the mask holder, and a bank amplifier plate that is in contact with the back surface of the mask. It has a wafer chuck that presses the wafer from the back side so as to be in contact with the mask surface, and has a ring-shaped groove on the outer periphery of the surface facing the wafer, and holds the groove part in a negative pressure state. It is characterized by this.

The present invention will be specifically explained below using Examples.

FIG. 3 is a longitudinal sectional view showing an example of the structure of a mask aligner to which the present invention is applied. In this figure, the same parts as those shown in FIGS. 1 and 2 are designated by the same reference numerals.

This mask aligner has a suction hole 7 which is located in a mask holder and a backup plate 2 provided in contact with the mask holder. This hole 7 is used for drawing a vacuum (VaC+) for fixing the mask 3 to the backup plate 2. Furthermore, mask positioning pins 13.13 are provided at the bottom of the mask holder 1, and one of the pins 13 is in contact with the mask via a mask fixing spring 19.

The wafer chuck 5 is injected with nitrogen gas N2 from inside the surface facing the wafer to bring it into close contact with the wafer mask.
' is fed out, and a ring-shaped groove 15°15 is provided on the outside of the surface facing the wafer, and a gas curtain is provided on the outer periphery of the wafer chuck. Two ring-shaped delivery holes 14a and 14b are provided for delivering the nitrogen gas N2'. and,
The ring-shaped groove 15.degree. 15 is designed to be evacuated (3C2).

Due to this evacuation, the groove 15 portion is in a negative pressure state.

The above device is used as follows.

The mask 3 is first positioned by the positioning pins 13 and springs 19, and then fixed to the bank up plays 1 and 2 by applying a vacuum (◯ao1) with the suction plate 7. The wafer 4 is pressed against a mask with nitrogen gas N2'. At this time, since the groove 15 for forming negative pressure is provided so that the effective diameter of the wafer chuck 5 is the same as the wafer diameter, the pressure distribution in the wafer part is highest at the center, so the entire surface of the wafer is are evenly pressed against the mask. Therefore, the degree of adhesion between the wafer and the mask increases. It should be noted that since the nitrogen gas N2 for pressing the wafer is sucked from the wafer 4 into the negative pressure forming hole 15 in the outside air, the pressure in the sea 15 does not increase.

Chin gas N2 for the gas curtain is supplied through two ring-shaped delivery holes I-14a installed on the lining of the Ueno chuck.
, ], 4b to form a gas curtain between the wafer chuck and the mask. This Chin gas N2
' is a sea urchin...The one facing the center of the chuck is the back pressure forming groove 1
5's vacuum 'aC2) is exhausted by suction, and what goes outward is released as total exhaust gas TN2. Like this N2
By forming the delivery hole with a multi-ring 4()G structure, entry of oxygen from the outside air can be more effectively prevented.

Next, during exposure, nitrogen gas N2''' is removed from the photoresist film.
However, this generated gas N2 is completely discharged because the pressure in the ring-shaped groove 15 is wider and lower than that of the gas N2. Therefore, the groove 15 is evacuated (3o2) using the nitrogen gas N2'.

It is necessary to have a capacity that can exhaust a part of N2' and N-2tit gases.

The presence of the backup plate 2 prevents the mask from bending during the exposure operation even if the push-up pressure by the piston 6 is high. Therefore, 1. Pitch misalignment between the mask and the cloth should be avoided. It's ugly.

According to the apparatus as described above, the degree of adhesion between the wafer and the mask at the start of the work and during the exposure work is increased, so the resolution is improved, and since no pitch deviation occurs, the alignment accuracy is improved.

Therefore, the mask aligner has the advantages of both the push-up contact method and the vacuum contact method described above.

The present invention is not limited to the above embodiments, and various modifications can be made. For example, nitrogen gas N2 for gas curtains
' is not sent from the sea urchin chunk 5 as in the above embodiment, but as shown in the partial sectional view shown in FIG.
It is also possible to provide a dedicated ring 16 and send the signal 5 from there. That is, this dedicated ring 16 is connected to the suction hole 17.
The inner diameter of the ring is slightly larger than the outer diameter of the wafer chuck 5, and the gap between the two is filled with nitrogen gas N2 through the delivery hole 118. is sent out to form a gas curtain. If this is done, the advantages of making the Ueno-Chidock 5 smaller and having a simpler structure will also be compromised.

The present invention can be widely used as a non-contact seal.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional views showing a conventional mask aligner structure, FIG. 3 is a vertical cross-sectional view showing an example of a mask aligner to which the present invention is applied, and FIG. 4 is a partial cross-sectional view showing the other side of the present invention. It is a diagram. 1...Mask boulder 1,...Bassokuanov plate, 3...Mask, 4...Wafer, 5 River wafer chuck, 6...Piston, 7...Suction hole, J3...Positioning bin , 14 a , ], 4 b... Ring-shaped gas delivery hole, 15... Ring-shaped groove, 19... Fixing spring. Procedural amendment (method) Indication of case Patent Application No. 5562 of 1982 19JIf with amendee 1 ge 1 Patent applicant V-HJi '510141 ceremony meeting 1l-1 <t:
12 (However, the fourth figure is corrected.)

Claims (1)

[Claims] 1. A space in which a plate-shaped object to be processed is to be processed is formed by the first and second members having closely opposing parts, and the space is formed through the opposing parts. A gas blowing hole is formed in a portion communicating with the outside and corresponding to the opposing portion of the second member, and by forming a gas flow in the gap between the opposing portions, the space can be accessed from the outside. Non-contact sealing device designed to shut off.