JP3019264B2 - Pattern transfer method and apparatus using X-ray mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a proximity transfer method for performing pattern transfer in a state where an X-ray mask and a substrate are close to each other.
Prevents pressure fluctuations in the gap between the line mask and the substrate,
A device for transferring an X-ray mask pattern onto a substrate with the X-ray mask and the substrate approaching each other with a small gap between them, with the aim of making the approach and separation operations between the mask and the substrate quick. When the X-ray mask and the substrate are approached, the gas in the gap between the mask and the substrate is forcibly exhausted by the exhaust means to reduce the pressure, and when the X-ray mask and the substrate are separated, the gap between the mask and the substrate is removed. Then, gas is forcibly supplied by a pressurizing means to pressurize the gas.

[Industrial applications]

For mass production of ultra-super LSIs that require fine processing of 0.3 μm or less, SR (Sy
nchrotron Radiation) —X-ray exposure is an indispensable technology. The main method of this exposure is a so-called step-and-repeat method in which semiconductor circuit patterns formed on an X-ray mask are sequentially transferred onto a wafer. But X
For line exposure, a 1: 1 proximity exposure (proximity exposure) method must be adopted. Therefore, when transferring a pattern, the distance between the mask and wafer must be extremely close, and when moving to the next pattern transfer area, the mask In order to avoid contact of the wafer, the wafer is moved with a space between the mask and the wafer, and adjusted to the original minute gap after the movement is completed.

The present invention relates to a proximity transfer method and apparatus for performing pattern transfer in a state where the X-ray mask and the substrate are brought close to each other.

[Conventional technology]

FIG. 6 is a sectional view showing a conventional X-ray exposure method. 1
Is an X-ray mask, which is an extremely thin Si having a thickness of about 2 μm.
A pattern 2 such as Ta is formed on the C mask membrane. This SiC mask membrane is transparent to X-rays, and Ta is opaque to X-rays. Reference numeral 3 denotes a mask support ring made of silicon, ceramic, or the like, and the outer periphery of the X-ray mask 1 is adhered and fixed. Then, the mask support ring 3 is fixed to the mask holder 4 of the mask stage.

While the X-ray mask 1 and the substrate 5 are brought close to each other to about 10 to 20 μm, SR-X-rays are irradiated, and the pattern of the X-ray mask 1 is transferred to the resist 6 of the substrate 5 and exposed.

After the exposure, the substrate 5 is moved to the next exposure position.
Moves to position the unexposed position in front of the X-ray mask 1 and perform proximity exposure. By repeating such an operation several tens of times, the entire surface of the substrate 5 is exposed.

Since a reduction optical system cannot be formed in X-ray exposure, a proximity exposure method has to be adopted in this way. Further, in order to transfer an ultrafine pattern of 0.3 μm or less, it is necessary to bring the X-ray mask 1 and the substrate 5 closer together in order to suppress resolution degradation due to diffraction.

By the way, if the X-ray mask 1 and the substrate 5 are relatively moved while keeping the minute gap of about 10 to 20 μm as in the exposure, the X-ray mask 1 may be damaged or broken by contacting the substrate 5. In particular, there is a concern in the case of a substrate whose surface is uneven by selective etching.

Therefore, when the exposure position is moved, the distance between the X-ray mask 1 and the substrate 5 is increased to about 30 to 50 μm, and after moving in a state where there is no danger of contact, the two are brought closer again.
Exposure is performed by adjusting the gap to about 20 μm.

[Problems to be solved by the invention]

By the way, while the gap G between the X-ray mask 1 and the substrate 5 is so small, the size of the X-ray mask 1 is several tens of mm on one side, and the gap D is very large compared to the mask area. Small. Therefore, as shown in FIG. 7 (a), when the X-ray mask 1
It takes time for the gas in the gap G to be pushed out of the gap. When the X-ray mask 1 is moved closer to increase the working efficiency, the X-ray mask 1 is extremely thin, about 2 μm, so that the X-ray mask 1 swells due to the differential pressure as shown in FIG.
It may be damaged.

When the exposure is completed and the X-ray mask 1 is separated from the substrate 5, the space between the X-ray mask 1 and the substrate 5 expands and gas enters from the outside.
It takes time for gas to enter from the outside between the substrate and the substrate 5. Therefore, when the X-ray mask 1 is quickly released, the gap G becomes negative pressure as shown in FIG. 2B, so that the X-ray mask 1 is hard to separate from the substrate 5 and the X-ray mask 1 is in a retracted state.

Therefore, in order to prevent deformation of the X-ray mask, the speed at which the X-ray mask 1 and the substrate 5 are moved closer to and away from each other must be reduced, and as a result, there arises a problem that work efficiency is reduced.

The technical problem of the present invention is to focus on such a problem,
An object of the present invention is to prevent fluctuations in air pressure in a gap between an X-ray mask and a substrate when the X-ray mask and the substrate approach or separate from each other, so that the approach and separation operations between the mask and the substrate can be performed quickly. .

[Means for solving the problem]

(1) FIG. 1 is a side view for explaining the basic principle of a pattern transfer method using an X-ray mask according to the present invention. 1 is X
Line masks 5 and 5 are substrates on which pattern transfer is performed.
When pattern transfer using the X-ray mask 1 is performed, the X-ray mask 1 and the substrate 5 are brought close to each other so as to have a minute gap that can prevent resolution degradation due to diffraction. Release.

In the present invention, the X-ray mask 1 and the time of approaching the substrate 5, the gas gap G between the X-ray mask 1 and the substrate 5 as shown in (a), the exhaust means, as indicated by arrow A _1, the gap The air is evacuated to the outside of G and the pressure is reduced.

Further, (b) when separating the X-ray mask 1 and the substrate 5 as, as an arrow A _2, the gap between the X-ray mask 1 and the substrate 5 G
(2) As shown in FIG. 2, the X-ray mask 1 and the substrate 5 are brought close to each other, and X is This is an apparatus for transferring the pattern of the line mask G to the substrate 5. In this apparatus, when the X-ray mask 1 and the substrate 5 are brought close to each other, the gas in the gap G between the mask and the substrate is forcibly exhausted by the exhaust means to reduce the pressure, and when the X-ray mask 1 and the substrate 5 are separated from each other. A gas supply / exhaust port 6 for forcibly supplying gas to the gap G between the mask and the substrate by a pressurizing means to pressurize the gas is provided in the X-ray mask 1.
The outer side is provided toward the substrate 5.

Further, outside the supply / exhaust port 6, there is provided a resistance generating section 7 for generating a gas flow resistance, and the distance d between the resistance generating section 7 and the substrate 5 is equal to the distance between the X-ray mask 1 and the substrate 5. D is formed such that d ≦ D.

[Action]

(1) As shown in (a), when the X-ray mask 1 and the substrate 5 are brought close to each other, the gap G between them is forcibly evacuated and reduced in pressure, so that the pressure in the gap G is prevented from increasing. it can. Therefore, even if the X-ray mask 1 and the substrate 5 are quickly brought close to each other, the X-ray mask 1 does not expand as shown in FIG. 7A.

Further, when the X-ray mask 1 and the substrate 5 are separated from each other as shown in (b), gas is forcibly supplied from the outside to the gap G between the two and pressurized, so that the pressure drop in the gap G is suppressed. You.
Therefore, even if the X-ray mask 1 and the substrate 5 are quickly separated from each other, the X-ray mask 1 does not retract as shown in FIG. 7B.

As described above, even if the X-ray mask 1 and the substrate 5 are moved closer to or away from each other at a high speed, the deformation of the X-ray mask 1 can be prevented, so that work efficiency is improved, and X-ray exposure is performed in a step-and-repeat method. It is effective in the case.

(2) In the apparatus shown in FIG. 2, when the X-ray mask 1 and the substrate 5 are brought close to each other, the space between the mask and the substrate is supplied from the supply / exhaust port 6 outside the X-ray mask 1 as shown by the solid arrow. Since the gas at the interval G is forcibly exhausted by the exhaust means to reduce the pressure, the X-ray mask 1 can be quickly approached without deformation as in the case of FIG. When the X-ray mask 1 and the substrate 5 are separated from each other, a gas is forcibly supplied from the air supply / exhaust port 6 to the gap G between the mask and the substrate by the pressurizing means, as indicated by a broken arrow. Since the pressure is applied, the gap G does not become a negative pressure and the X-ray mask 1 is not deformed and can be quickly separated.

In this apparatus, the resistance generating portion 7 is provided outside by the air supply / exhaust port 6, and the distance d from the substrate 5 is d ≦ D. Is suppressed, and the gas in the gap G is efficiently and quickly exhausted. Also, when supplying air as indicated by the dashed arrow,
It is possible to suppress the gas ejected from the air supply / exhaust port 6 from flowing out of the resistance generating section 7 to be wasted, and to pressurize the gap G efficiently and quickly. Therefore, according to this device,
The step and repeat operation can be further speeded up.

Note that the longer the width L of the resistance generator 7 is, the more the effect of increasing the resistance is improved.

〔Example〕

Next, how the pattern transfer method and apparatus using an X-ray mask according to the present invention are actually embodied will be described with reference to examples. FIG. 3 is a time chart showing an embodiment of the method of the present invention, which will be described with reference to FIG. (A) shows whether the X-ray mask and the substrate are separated or approached,
(B) shows the exhaust timing, and (c) shows the air supply timing.

Now, when the X-ray mask 1 and the substrate 5 at time t ₂ is assumed to approach, to start the discharging operation of the gap G at the time of the short time before t _1, is accessible from a gap G begins to be reduced pressure, and also was evacuated for a while from the close operation is completed, and ends the exhaust operation at the time of t _3. Then, was exposed to X-ray mask 1, when separating the X-ray mask 1 from the substrate 5, assuming that the X-ray mask 1 and the substrate 5 at the time of t ₅ is disengaged, shortly before separating operation It began air supply operation from the time of t ₄ to the gap G, since the gap G begins pressurized, moved away. Even after the separation operation ends, supply air for a while,
to terminate the air supply operation at the time of t _6.

By repeating such an operation, X-ray exposure by the step-and-repeat method is performed.

FIG. 4 shows an embodiment of a pattern transfer apparatus using an X-ray mask. The mask holder 4 to which the X-ray mask 1 is mounted via the mask support ring 3 is mounted on a mask stage. On the other hand, the substrate 5 is mounted on a wafer stage 8. The relative position and operation of the mask stage and the wafer stage 8 are controlled by the control device 9.

10 is a pressurized tank, 11 is a decompression tank, and the pressure is precisely controlled. Then, they are connected to a supply / discharge pipe 16 via solenoid valves 12, 13 and flow control devices 14, 15, respectively. The supply / discharge pipe 16 is connected via a supply / exhaust hole 17 of the mask holder 4,
It is connected to the supply / exhaust port 6. The opening and closing of the solenoid valves 12 and 13 is also performed by the control device 9.

Next, the operation will be described with reference to the time chart of FIG. Normally, both the solenoid valves 12 and 13 are closed. Assuming that the X-ray mask 1 and the substrate 5 are close to each other, rough alignment is performed at a position close to about 100 μm, and then to 30 to 50 μm. After approaching, coarse positioning is performed. Then, at time t ₁ in FIG. 3, the control device 9 opens the solenoid valve 13 for exhaust, and the pressure reducing tank 11 starts exhausting the gap G from the supply / exhaust port 6. The X-ray mask 1 and the substrate 5 starts close at time t _2, at the time of t ₃ after approaching completion, the exhaust solenoid valve 13 is closed by a signal from the controller 9. Thus, 10 ~
The final positioning is performed in a state of approaching 20 μm.

Exposed in this state is performed, then the control signal from the control device, the air supply electromagnetic valve 12 is opened at time t _4, the pressure tank 10, the air supply is carried out into the gap G from the supply and exhaust port 6 And pressurized. At the time of t ₅ during pressurization, start to move apart the X-ray mask 1 and the substrate 5, at the time of t ₆ after leaving about 30 to 50 [mu] m, by the controller 9, the air supply electromagnetic valve 12 is closed, The movement to the next exposure position is performed.

When performing X-ray exposure in air, the air supply / exhaust port 6
The gas supplied from the air may be air, but He is supplied when exposure is performed in He or the like where energy of X-rays is small. That is, the atmosphere gas in the exposure unit is supplied.

FIG. 5 is a view showing an embodiment of the air supply / exhaust port, in which (a) is a sectional view and (b) is a front view. As shown in (b), the air supply / exhaust port 6 is formed in a ring shape so as to surround the X-ray mask 1, and can supply / exhaust air from the outer periphery of the X-ray mask 1. Further, as shown in (a), the air supply / exhaust port 6 is connected to the X-ray mask 1.
It is formed obliquely toward the gap G between the substrate and the substrate 5, and pressurization and decompression in the area of the gap G are effectively performed.
One or more air supply / exhaust holes 17 are formed in the ceiling of the annular air supply / exhaust port 6, and the more the air supply / exhaust hole 17 is provided, the more quickly the air supply / exhaust can be performed.

〔The invention's effect〕

As described above, according to the present invention, the X-ray mask 1 and the substrate 5
When the gas approaches and separates, by supplying and exhausting gas to and from the gap G between them, even when the approaching / separating operation is performed at high speed,
Since the deformation of the X-ray mask 1 can be prevented by suppressing the pressure fluctuation in the gap G, the transfer operation such as X-ray exposure can be efficiently performed at high speed.

Further, as described in claim 2, the resistance generating portion 7 is provided outside the air supply / exhaust port 6 to suppress the flow of gas between the air supply / exhaust port 6 and the outside, thereby supplying / exhausting the gap G. Can be performed efficiently, and the operation of approaching / separating the X-ray mask 1 and the substrate 5 can be further speeded up.

[Brief description of the drawings]

FIG. 1 is a side view for explaining the basic principle of a pattern transfer method using an X-ray mask according to the present invention, FIG. 2 is a cross-sectional view showing a pattern transfer apparatus using an X-ray mask according to the present invention, and FIG. 4 is a diagram showing an embodiment of a pattern transfer apparatus using an X-ray mask, FIG. 5 is a cross-sectional view and a front view showing an embodiment of a supply / exhaust port, and FIG. FIG. 7 is a sectional view showing an X-ray exposure method and apparatus, and FIG. 7 is a sectional view showing a deformed state of an X-ray mask in a conventional X-ray exposure method. In the figure, 1 is an X-ray mask, 2 is a mask pattern, 3
Is a mask support ring, 4 is a mask holder, 5 is a substrate,
G is a gap, 6 is a supply / exhaust port, 7 is a resistance generator, 9 is a control device, 10 is a pressurized tank, 11 is a decompression tank, 12, 13 are solenoid valves, 14, 15 are flow rate control devices, and 16 is a supply An exhaust pipe 17 indicates a supply / exhaust hole.

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027

Claims (2)

(57) [Claims] An X-ray mask (1) is brought close to a substrate (5) with a small gap (G) therebetween.
When the X-ray mask (1) and the substrate (5) are brought close to each other, the gas in the gap (G) between the mask and the substrate is forcibly exhausted by the exhaust means. When the X-ray mask (1) is separated from the substrate (5), a gas is forcibly supplied to the gap (G) between the mask and the substrate by a pressurizing means to pressurize the substrate. A pattern transfer method using an X-ray mask. 2. An X-ray mask (1) with an X-ray mask (1) and a substrate (5) approaching each other and leaving a small gap (G).
Is a device for transferring the pattern of (1) onto the substrate (5). When the X-ray mask (1) and the substrate (5) are brought close to each other, the gas in the gap (G) between the mask and the substrate is forcibly forced out by the exhaust means. When the X-ray mask (1) and the substrate (5) are separated from each other by evacuation and decompression, a gas is forcibly supplied to the gap (G) between the mask and the substrate by a pressurizing means to pressurize the gas. An exhaust port (6) is provided toward the substrate (5) outside the X-ray mask (1), and a resistance generating section (7) outside the supply / exhaust port (6) for generating a gas flow resistance. The distance d between the resistance generating section (7) and the substrate (5) is set to be equal to the distance between the X-ray mask (1) and the substrate (5).
A pattern transfer apparatus using an X-ray mask, wherein d is equal to or smaller than D.