JPH02848B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray exposure apparatus, more specifically, a container capable of being filled with an oxygen-free gas is connected to an X-ray exposure sample chamber, and the sample is exposed to the atmosphere after exposure. The present invention relates to an X-ray exposure apparatus equipped with a mechanism for introducing the gas into the container without exposing it to oxygen and storing it in an oxygen-free gas for a predetermined period of time.

In recent miniaturization of semiconductor devices, when processing a wafer, a negative X-ray resist is applied on the wafer to form a resist layer, and X-rays are irradiated through a patterned mask.
After such exposure, development is performed, and subsequent etching treatments and the like are performed.

The above-mentioned X-ray exposure is not performed by irradiating the entire surface of the wafer, but by a step-and-repeat method. This is to achieve accurate alignment by taking into account the warpage of the wafer, and also by taking into account geometric positional deviations specific to X-ray exposure.

In the step-and-repeat method described above, when we look at resist A, which was exposed first, and resist B, which was exposed last, there is a difference in the elapsed time between them, and this difference is It was found that two issues emerged.

The residual film rate remaining after a negative X-ray resist is exposed and developed has an important meaning as the line width after development will differ even if exposed with an X-ray absorber pattern of the same line width. It has been found that when a wafer coated with resist is exposed and left in a vacuum or nitrogen gas for a certain period of time, the residual film rate of the resist changes due to so-called post-polymerization. The results are shown in FIG. 1, in which the horizontal axis shows the time for leaving in vacuum or nitrogen (N ₂ ) gas after exposure, that is, the post-processing time, and the vertical axis shows the residual film rate. When the last resist B is exposed,
Resist A, which was first exposed, is at position A on the curve because a certain amount of time has passed, but when the wafer is left in the above atmosphere for one hour, B and A are at B' and A', respectively. The remaining film rate is shown. but,
Exposure to a gas containing O ₂ , such as the atmosphere, stopped postpolymerization at that point. However, storing the sample in vacuum for an additional hour after X-ray exposure requires a complicated device, which increases product cost.

The purpose of the present invention is to remove negative X on a wafer.
When exposing a radiation resist (hereinafter a wafer with such an X-ray resist layer is referred to as a sample) to X-rays using the step-and-repeat method,
The objective is to obtain a uniform residual film rate over the entire surface of the sample, and for this purpose, a container that can be filled with oxygen-free gas is connected to the X-ray exposure chamber, and the sample is exposed to the atmosphere after the X-ray exposure. The present invention provides an apparatus for moving the gas into a container and storing it in the gas for a predetermined period of time. Embodiments of the apparatus of the present invention will be described below with reference to the accompanying drawings.

The illustrated apparatus includes an X-ray generating chamber 1, an X-ray generating source 2 is arranged above the center of the chamber 1, and the X-rays reach a Be window 3 in the illustrated direction and enter the exposure chamber from there.
A stage 6 is arranged in the center of the exposure chamber, and a sample 5 is placed on it. The sample 5 is irradiated with X-rays through a mask 4 in a step-and-repeat manner. The X-ray generation chamber 1 is kept in a vacuum, but the exposure chamber is filled with a vacuum or a gas such as N ₂ that does not contain O ₂ .

Pattern dimensions of samples exposed using the step-and-repeat method (correlation with residual film rate)
As described above, is different between the first exposed resist A and the last exposed resist B.
In order to minimize this difference to a negligible extent and obtain a uniform residual film rate over the entire surface of the sample, sample 5 was transferred to a post-processing chamber connected to the exposure chamber and curing (post-processing) was performed. It is done. A stage 6' may be provided in the post-processing chamber and only the sample 5 may be transferred thereon, or the stage 6 on which the sample 5 is placed may be moved. N ₂ gas is supplied to the post-processing chamber through the gas supply port 7 and is discharged from the gas discharge port 8 . In the post-treatment, it is sufficient to leave the sample for a predetermined period of time, for example, one hour, in a state where it is not exposed to the gas containing O ₂ , so there is no need to pressurize the N ₂ gas. As a result of this 1-hour post-processing, the residual film ratios of the first and last exposed negative X-ray resists A and B move from positions B and A to positions B' and A' in Figure 1. However, the difference has become negligible. In addition, when the exposure time is long, A is sufficient to reduce the difference in the residual film rate of resists exposed using a method that causes a difference in the elapsed time after exposure to a negligible level.
Since the difference between the state and the B state is large, it is necessary to carry out a long post-polymerization treatment in order to reduce the difference. Further, when the exposure time is short, the difference between the A state and the B state is small, so that the difference becomes less of a problem if the polymerization treatment is performed after a short time.

As shown in the figure, the sample 5 is moved from the exposure chamber through the sample entrance/exit chamber to the post-processing chamber.
The →→ method may be used, or the →→ method may be used, in which the sample is placed into the exposure chamber from the sample entrance/exit chamber, exposed to X-rays, and then directly moved to the post-processing chamber after exposure. The key is to avoid exposing the sample to the atmosphere after exposure.

As explained above, using the apparatus of the present invention,
By post-processing the sample after the radiation exposure, a uniform residual film ratio of the X-ray resist can be obtained over the entire surface of the wafer, which means that the reliability of the semiconductor device is improved. Since it is sufficient to supply N ₂ gas to the post-processing chamber, the cost is reduced compared to using conventional complicated vacuum equipment, which leads to lower product costs. In addition, in the above example,
Although we have explained an example using _N2 gas, the gas may be a single gas or a mixture of gases that do not contain oxygen, such as argon (Ar), helium (He),
Freon (CF ₄ ), hydrogen (H ₂ ), neon (Ne), etc. can also be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the relationship between the elapsed time and the residual film rate when a negative photoresist is left in vacuum or _N2 gas, and FIG. 2 is a cross-sectional view of an embodiment of the present invention. It is. ...Exposure chamber, ...Sample entrance/exit room, ...Post-processing room, 5...Sample, 6, 6'...Stage, 7...
...Gas supply port, 8...Gas discharge port.

Claims (1)

[Claims] 1. After irradiating a negative X-ray sensitive resist deposited on the wafer surface with X-rays using a step-and-repeat method, the X-ray resist is post-polymerized to form an X-ray pattern on the entire surface of the wafer. An X-ray exposure apparatus for obtaining a uniform residual film rate of a ray resist, the apparatus comprising an X-ray exposure chamber, a wafer entrance/exit chamber connected to the exposure chamber, and a wafer entrance/exit chamber connected to or An X-ray exposure apparatus comprising a post-processing chamber connected to an exposure chamber and supplied with oxygen-free gas. 2. The X-ray exposure apparatus according to claim 1, wherein the post-processing chamber is directly connected to an X-ray exposure chamber. 3. A step of exposing a negative type X-ray resist formed on the wafer surface to X-rays in an X-ray exposure chamber, and connecting the wafer from the X-ray exposure chamber to the X-ray exposure chamber after the X-ray exposure. and transferring the wafer to a post-processing chamber capable of maintaining an oxygen-free atmosphere in the post-processing chamber, in which the first exposed resist of the negative-type X-ray resist and the last exposed resist of the negative-type X-ray resist are removed. and a step of holding the resist for a sufficient time so that the difference in the residual film rate of the resist exposed to the resist is negligibly small.
Line exposure method. 4 Claim 3, characterized in that the oxygen-free atmosphere is a gas atmosphere of nitrogen, argon, helium, freon, neon, or hydrogen.
X-ray exposure method described in section.