JPS59188123A - X-ray exposure device - Google Patents

Abstract

PURPOSE:To enable to improve a throughput of an X-ray exposure device by filling a space between an X-ray mask and an exposure wafer by gas controlled in composition ingredients of specific pressure, thereby enabling to apply a high sensitivity X-ray negative resist. CONSTITUTION:A shutter 10 is provided at the position substantially near an X-ray mask 5. An exposure chamber 11 which partly uses a vacuum sealing structure is evacuated in vacuum by 12 in a suitable vacuum evacuation system. After it is evacuated in vacuum of 10<-1>-10<-2>Torr, gas 14 controlled in composition ingredients is introduced from a gas inlet 13. Finally, the pressure in the chamber is set to become slightly larger than the atmospheric pressure. Suitably gas is always introduced into the chamber so as to correspond to the leakage of the chamber. A wafer automatic feeding mechanism 15 can supply the wafer 6 at the prescribed time interval to the wafer stage 8 in the chamber 11, and the exposed waffer is received from the wafer stage, and removed out of the chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray exposure apparatus, and particularly to an X-ray exposure apparatus used in X-ray lithography that can copy fine patterns of 1 μm or less.

It was announced in Electronics Letters, Vol. 8, No. 4, pp. 102-104 (1972) that it is possible to copy high-resolution patterns using X-ray phosphorography using soft X-rays. Since then, research on xWs phosphorography has been vigorously pursued.

A conventional X-ray exposure apparatus used for X-ray lithography is shown in FIG. There is a metal target 2 in a tube section 1 that is evacuated to a high vacuum of about 10-' Torr, and soft X-rays 3 generated from the target by electron beam irradiation are taken out of the tube through an X-ray extraction tube 4. Ru. The X-ray mask 5 and the resist-coated wafer 6 existing in the air atmosphere,
It is irradiated with the soft X-rays 3. The X-ray mask 5 is set on a mask fixing device 7, and the wafer 6 is set on a wafer stage 8.

However, such a device has one problem in its configuration. That is, the X-ray mask and wafer are set in the atmosphere. Although this atmospheric exposure method has features such as relatively easy equipment configuration and excellent operability, it actually involves an important time difference in X-ray exposure. . The biggest challenge in X&l Ginko is improving throughput. High-sensitivity X-ray resists play an extremely important role in improving this throughput. The requirements for Xi resist are approximately 10
Extremely high sensitivity of mJ/crd or less is required.

Koma, including the recent trends, it seems that the realization of this request will not be easily achieved. The highest sensitivity currently available for negative resists is PGMA (Tokyo Ohka), 5IuL-
Approximately 30 +nJ / (
M (for positive resists, FBM-F" PM (Daikin Industries) etc. is about 50 mJ/c++!.While meeting the above requirements for high sensitivity, high resolution in the submicron range and appropriate dry etching resistance. This is not an easy task to achieve as it also requires the following.

Incidentally, it is a well-known fact among those involved in resist development that negative resists generally have higher sensitivity than positive resists. Therefore, it is natural to think that the development of high-sensitivity X-ray resists will mainly be done with negative resists. Anticipating this, the present inventor has also consistently studied the evaluation of negative resists in X-ray exposure. However, negative resists have one major problem. That is, negative resists are easily affected by the exposure atmosphere. In particular, the fact that oxygen during atmospheric exposure reduces the crosslinking reaction of negative resists is
This is a generally well-known fact. The inventor also
This point has been confirmed using methods such as
The crosslinking reaction of POMA, ie, the sensitivity, is significantly reduced.

In the prior art shown in FIG. 1, the atmospheric exposure method is an essential part of the apparatus configuration, and it is impossible to solve the above-mentioned problems.

SUMMARY OF THE INVENTION An object of the present invention is to provide an X-ray exposure apparatus having a novel structure that eliminates such conventional problems, allows application of a high-sensitivity X-ray negative resist, and is expected to improve throughput.

The gist of the present invention is that the space between the X-ray mask and the exposure tube is filled with a gas whose composition is controlled and whose pressure is 2 atmospheres or less.

The present invention will be described below with reference to drawings showing embodiments. FIG. 2 is a schematic sectional view of an embodiment of the present invention, showing a configuration diagram of an X-ray exposure apparatus. As in FIG. 1, the soft X-rays 3 emitted from the X-ray extraction window 4 of the tube section 1 are irradiated onto the X-ray mask 5 through the atmosphere 9. The new configuration will be explained below. A shutter lO is provided at a position 7 approaching the X-ray mask 5. The exposure chamber 11 in which the shutter is part of a vacuum-sealed structure is evacuated 12 using a suitable evacuation system. 10-'~1O-2To
After evacuation of rr is performed, a gas 14 whose composition is controlled is introduced from the gas introduction port 13. Finally, the pressure inside the exposure chamber is set to be slightly higher than atmospheric pressure. Appropriate gas is always introduced into the chamber to account for leaks in the exposure chamber.
- The automatic feed mechanism 15 (only a part is shown) is connected to the exposure chamber 1
The ueno layer 6 can be supplied to the ueno stage 8 in the exposure chamber at predetermined time intervals, and the exposed ueno layer can be removed from the ueno stage and taken out of the exposure chamber.

When feeding the sea urchin/.-6 into the exposure chamber 11 and when taking out the sea urchin/. The sea urchin enters the exposure chamber and moves to the delivery position 15'. The wafer stage 8 also moves to the urchin transfer position 8' to transfer the wafer. At this time, part or all of the wafer state 8 may be moved out of the exposure chamber 11 to transfer the wafer 6. Since the pressure inside the exposure chamber is more positive than that of the atmosphere, air does not get mixed into the chamber. The shutter 10 has the role of protecting the X-ray mask 5 by withstanding the atmospheric pressure during evacuation, but once the inside of the exposure chamber is sufficiently filled with an appropriate gas 14 and the pressure becomes slightly positive than 1 atmosphere, The shutter 10 is not in an open state,
A line mask 5 is incorporated to become part of the closed structure of the exposure chamber. This shutter must be open at least during exposure. After opening the shutter, the mask and wafer are brought close to each other by several tens of micrometers to eliminate light. The withstand pressure of the X-ray mask itself is usually 0.1 to 0.2 atmospheres, and in this case, the above-mentioned shutter is absolutely necessary. In addition, the institution to which the present inventor belongs has confirmed that a Si thin film with a thickness of 3 to 4 μm has a withstand pressure of approximately 1 atm, and if a new X-ray mask substrate material is developed, the withstand pressure will be 1 to 2 atm. There is a possibility of obtaining. However, the aforementioned shutter is necessary to protect the X-ray mask during long-term use.

Furthermore, when using a negative resist whose sensitivity is severely degraded when exposed to air, it is recommended to use a gas inert to the resist, such as He (helium) or N2 (nitrogen), as the gas introduced into the exposure chamber. good. The inventor has confirmed that when these gases are used, there is no decrease in the sensitivity of the negative resist.

As described above, by adopting the new structure, an exposure atmosphere with appropriate gas components can be obtained without permanent exposure in the atmosphere, and the above-mentioned problems can be solved. Furthermore, the continuous wafer transport mechanism into the exposure chamber allows automatic continuous exposure, thereby achieving the objectives of the present invention.

FIG. 3 is a schematic sectional view of another embodiment of the present invention, showing a configuration diagram of an X-ray exposure apparatus. It is the same as in FIG. 2 up to the point that an automatic opening/closing shutter 10 is provided. In this configuration, a vacuum sealed space 19 is formed by the shutter 10, the shutter holding mechanism 17, the wafer stage 8, and the sealing mechanism 18 whose dimensions can be easily changed. After a part of the wafer stage is evacuated by a vacuum pump 12, an appropriate gas 14 is introduced from a gas inlet 13 in a part of the shutter holding mechanism, and the inside of the vacuum sealed space is maintained at a positive pressure slightly higher than 1 atmosphere. , the shutter 10 is in the open state,
The X-ray mask 5 becomes part of the structure forming the exposure space. The wafer up/down mechanism 20 is used to transfer the wafer 6 to and from the automatic wafer transport mechanism 15, and to fully align the distance between the X-ray mask 5 and the wafer and to set a predetermined distance during exposure. Ueno-6 is Ueno-6
- From the location of the automatic switch 16 provided in a part of the wafer stage 8 by the automatic feed Hoa 15, the exposure space 19
The sea urchins are sent to the delivery position 15'.

At this time, the wafer up/down mechanism 20 is
It is descending at the delivery position 2 o't, and the delivery of sea urchins, etc. is carried out. When the wafer transfer is completed, the automatic wafer feeding mechanism 15 retreats outside the exposure space, the automatic switch 16 closes and the exposure space is sealed, and the distance between the X fat mask 5 and the wafer -6 is set to a constant distance of N1. , then alignment and exposure are performed.

The wafer 6 is taken out after flashing by the reverse procedure to the above. This configuration also achieves the object of the present invention.

Regarding the gas introduced into the exposure space, it is important that the oxygen content is controlled to 1 g or less. If more oxygen is contained, exposure sensitivity will decrease.

The material is not limited to the aforementioned He and N2, but may also be Ar (argon). Depending on the type of resist used, an inert gas containing a small amount of 02 may be used to improve the shape of the resist pattern. Thus, various combinations are included within the scope of the present invention.

Furthermore, although a shutter is used in the above two embodiments,
A shack is not necessary unless long-term protection of a line mask is required. In this case, the X-ray mask itself is already part of the structure that seals the exposure chamber. However, in this case, since the pressure of dew is added, the pressure resistance of the mask itself must be at least the industrial pressure.

In addition, in the two examples described in MiJ, an example was shown in which an appropriate gas was replaced after evacuation, but it is also possible to replace the appropriate gas with an appropriate gas for the required time without evacuation to achieve the objective. It is also within the scope of the present invention to obtain an exposure atmosphere that provides a suitable exposure atmosphere. That is, the exposure chamber does not necessarily have to have a sealed structure. In this case, pressure control of the exposure space is required. Alternatively, exposure may be performed in a vacuum. However, even in this case, the oxygen content must be below a certain value as described above.

As described above, according to the present invention, it is possible to easily obtain a gas whose composition is controlled in the exposure atmosphere between the X-ray mask and the exposed wafer, which ultimately leads to an improvement in the throughput of exposed wafers. A practical X&IN optical device can be achieved.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of a conventional X-ray fogging apparatus, and FIGS. 2 and 3 are schematic cross-sectional views of an X-ray exposure apparatus showing an embodiment of the present invention. ■...Tube section, 2...Metal target, 3...
・Soft X-ray 4...X-ray extraction window, 5...X-ray mask, 6
．． 6'...Sea urchin...-17...Mask fixing mechanism, 8
... Wafer stage (exposure position), 8'... Wafer stage (wafer - delivery 1- position f), 9... Atmosphere, 10... Shutter, 11... Exposure chamber, 1
2... Vacuum exhaust, 13... Gas inlet, 14...
Gas, 15...Wafer automatic feeding mechanism (retreat position),
15'...Wafer automatic feed mechanism (urchin...-delivery position), 16...Automatic opener, 17...Shutter holding mechanism, 18...Seal mechanism, 19...Exposure space,
20... Wafer up and down mechanism (exposure position), 20'...
・Wafer up and down mechanism (wafer delivery position), 21...
- Arrow indicating movement of the wafer stage, 22...Arrow indicating movement of the wafer automatic feeding mechanism, 23...Arrow indicating movement of the wafer up/down mechanism. 11: Person J

Claims (4)

[Claims] (1) An X-ray device comprising at least a tube section including an X-ray source, an In the radiation exposure apparatus, the space between the wafer placed on the wafer stage and the X-ray mask is under pressure 2.
An X-ray exposure apparatus characterized in that it is filled with a gas whose pressure is below atmospheric pressure and whose oxygen content is 1φ or less. (2) The X-ray exposure apparatus according to claim 1, wherein the exposure chamber has a sealed structure capable of being evacuated, and a vacuum exhaust device for evacuating the exposure chamber is provided. (3) The X-ray exposure apparatus according to claim 1 or 2, wherein the opening of the exposure chamber is provided with a shutter that opens at least during exposure. (4) A mechanism for placing a wafer on a wafer stage after a predetermined time and removing the wafer from the wafer stage after exposure is provided. The X-ray exposure apparatus described above.