JPH04372111A - Projection aligner - Google Patents

Abstract

PURPOSE:To prevent an exposure plane from coming wide out of a focal plane in the case of projection exposure of mask patterns onto a substrate having stepped surfaces with a plurality of levels. CONSTITUTION:A transmit/shield mask 2 is mounted at a position optically conjugated with a mask pattern 4. The transmit/shield mask 2 has a light transmitting area in the area corresponding to a projection on the substrate 6 and a light shielding area in the area corresponding to a recess on the substrate. A mask pattern 4 is irradiated with light from a light source 11 via the transmit/shield mask. A pattern of the mask pattern 4 is transferred only to a projection on the substrate 6. Next, the transmit/shield mask 2 is exchanged, and a pattern of the mask pattern 4 is transferred only to a recess on the substrate 6. Therefore, setting a focus optimally at every time of transfer allows no exposure planes to come wide out of a focal plane.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus for transferring a mask pattern onto a substrate having a step surface having a plurality of heights.

0002

[Background Art] In recent years, projection exposure equipment has become higher in NA and wavelength has become shorter, and the height difference in substrates has become higher due to the higher integration of semiconductor devices, so there is no margin for depth of focus when exposing a resist on a substrate. Ta. A technique for increasing the depth of focus margin is disclosed in, for example, Japanese Patent Laid-Open No. 63-42122. In this technique, a resist pattern is formed by aligning an imaging point with multiple points in a resist coated on a substrate and exposing the resist multiple times.

0003

[Problems to be Solved by the Invention] Conventional exposure methods focus on one point in the resist and expose once, or as shown in Japanese Patent Laid-Open No. 63-42122, multiple exposures in the resist are performed. There is a method of aligning the imaging point with a dot and exposing the light multiple times, but both methods transfer the entire mask pattern onto the substrate at once, so when transferring the mask pattern onto a substrate with steps, the focal plane must be There was a problem in that there was an exposed surface that deviated significantly from the exposure surface.

[0004] This invention was made to solve the above-mentioned problems, and when a mask pattern is transferred onto a substrate having a step surface with a plurality of heights, the exposed surface may deviate greatly from the focal plane. The purpose is to obtain a projection exposure apparatus free of

[0005]

[Means for Solving the Problems] A projection exposure apparatus according to the present invention is a projection exposure apparatus that transfers a mask pattern onto a substrate having a step surface having a plurality of heights. A light-transmitting mask having a light-transmitting part and a light-blocking part and installed at a position optically conjugate to the mask pattern is provided, and the mask pattern is applied to the substrate multiple times while the light-transmitting mask is replaced. The feature is that the image is transcribed separately.

[0006]

[Operation] This invention includes a light-transmitting mask and a light-shielding mask that have a light-transmitting part and a light-blocking part depending on the height of the step surface and are installed at a position optically conjugate with respect to the mask pattern. Since the mask pattern is transferred onto the substrate in multiple steps while exchanging the mask pattern, the focus can be adjusted according to the height of each step surface.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the structure of a projection exposure apparatus according to the present invention. In the figure, 1 is a light source, 2 is a light transmitting mask, 3 and 5 are projection lenses, 4 is a mask pattern, and 6 is a substrate. Transmissive light mask 2 has mask pattern 4
It is placed at a position optically conjugate to. Board 6
is also placed at a position optically conjugate with respect to the mask pattern 4.

FIG. 2 is a plan view of the light transmitting mask 2, FIG. 3 is a plan view of the mask pattern 4, and FIG. 4 is a plan view of the substrate 6. The light transmitting mask 2 is placed at a position optically conjugate to the mask pattern 4. The substrate 6 is also placed at a position optically conjugate to the mask pattern 4. Figure 5
4 is a sectional view taken along line LL in FIG. 4. FIG. In FIG. 5, A is a convex portion and B is a concave portion. In FIG. 2, A1 is a light transmitting portion provided corresponding to the convex portion A on the substrate 6, and B1 is a light shielding portion provided corresponding to the concave portion B on the substrate 6. In FIG. 3, A2 is an area where light from the light source 1 is irradiated through the light-transmitting part A1 of the light-transmitting mask 2, and B2 is an area where the light from the light source is blocked by the light-blocking part B1 of the light-transmitting mask 2. . Note that the convex portion A and region A2, the transparent portion A1 and region A2, the recessed portion B and region B2, and the light shielding portion B1 and region B2 are each optically conjugate and have a one-to-one correspondence.

[0009] When the mask pattern 4 is transferred onto the substrate 6 using the projection exposure apparatus having such a configuration, only the pattern in the area A2 on the mask pattern 4 will be transferred onto the substrate 6. In other words, the pattern is transferred only onto the convex portions A on the substrate 6. Therefore, there is no need to take into consideration the recesses B, which would be largely out of focus when the mask pattern 4 is transferred all over the substrate 6 at once. In addition, when transferring the pattern to the convex portion A shown above, the convex portion A is focused at the optimum location.

Next, a light transmitting mask in which the light transmitting part A1 and the light shielding part B1 of the light transmitting mask 2 are reversed, that is, a light transmitting mask in which the light transmitting part A1 is the light shielding part and the light shielding part B1 is the light transmitting part. The mask pattern 4 is transferred onto the substrate 6 using a . At this time, the pattern transferred onto the substrate 6 is only the pattern in area B2 of the mask pattern 4. In other words, the pattern is transferred only onto the recesses B on the substrate 6. Therefore, there is no need to consider the convex portion A, which would be largely out of focus when the mask pattern 4 is transferred all over the substrate 6 at once. Note that when transferring the pattern to the recess B shown above, the optimum focus is set on the recess B.

In the above embodiment, two light-transmitting and shielding masks were used in which the light-transmitting and light-blocking portions of the light-transmitting and shielding mask 2 were formed to correspond to the heights of the convex portion A and the concave portion B, respectively. If a stepped surface with a height of 3 or more is formed, use three or more light-transmitting masks 2 with light-transmitting parts and light-blocking parts formed according to the height of each, and replace the light-transmitting masks. The exposure may be carried out three or more times.

0012

Effects of the Invention As described above, according to the present invention, the light-transmitting and light-shielding parts are provided in a position that is optically conjugate with respect to the mask pattern, and have a light-transmitting part and a light-shielding part corresponding to the height of the stepped surface. A mask is provided, and the mask pattern is transferred onto the substrate in multiple steps while replacing the light-transmitting mask.
The focus can be adjusted according to the height of each stepped surface. As a result, there is an effect that the exposure plane does not deviate significantly from the focal plane.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing the configuration of a projection exposure apparatus according to the present invention.

FIG. 2 is a plan view of a light-transmitting mask.

FIG. 3 is a plan view of a mask pattern.

FIG. 4 is a plan view of the substrate.

FIG. 5 is a cross-sectional view of the substrate.

[Explanation of symbols]

2 Transparent light mask 4 Mask pattern 6 Board

Claims (1)

[Claims] 1. A projection exposure apparatus for transferring a mask pattern onto a substrate having a step surface having a plurality of heights, the projection exposure apparatus having a light-transmitting portion and a light-blocking portion corresponding to the heights of the step surface, the mask pattern being The present invention is characterized by comprising a light-transmitting mask placed at a position optically conjugate to the light-transmitting mask, and transferring the mask pattern onto the substrate in multiple steps while exchanging the light-transmitting mask. Projection exposure equipment.