JPH1022209A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To optimize the resolution or focus depth at the exposure and the coarse-dense dependency of a pattern by providing an illumination system filter to control optionally the intensity distribution of transmissive light by controlling transmissivity. SOLUTION: Respective shutter cells of an illumination system filter in which a large number of micro-shutters are arranged are controlled electrically and a desired opening pattern shape is formed through on-off control, thereby controlling the intensity distribution of a transmissive light optionally. Namely, a liquid crystal board 10 in which a large number of micro unit liquid crystal cells are arranged is held by a filter frame, and a frame 9 is incorporated with a circuit for controlling respective liquid crystal cells of the board 10, and further an electric signal is sent to a control circuit in the frame 9 through a software, so that the orientation of a liquid crystal cell at the optional position in the board 10 is controlled. Thus, the parts to be transmitted by a light and to block it are formed and an optional opening shape is obtained, thereby exposing a pattern by an illumination system having various illuminance distributions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exposure apparatus suitable for use in an exposure step for forming a fine pattern.

[0002]

2. Description of the Related Art For example, in a lithography process which is one of the manufacturing processes of a semiconductor device, reduced exposure projection is performed. As shown in the configuration diagram of the exposure apparatus in this reduced exposure projection, light having an arbitrary intensity distribution transmitted through a mask M patterned with Cr (chrome) is used as shown in FIG.
Irradiation is performed on a semiconductor wafer W on which a semiconductor device is formed.

That is, in an exposure apparatus (so-called reduced exposure projection apparatus) 38 shown in FIG.
Light I generated by a light source comprising a lamp 36 and an elliptical mirror 37 is reflected by a mirror 32, passes through a shutter 35, is made uniform by a flyer lens 34, has an opening, and adjusts the light intensity distribution. The exposure intensity distribution is set by the revolver R, and the exposure range is set by the reticle blind 33. Further, the light I is reflected by the mirror 31 and made uniform by the condenser lens D, and then passes through a mask (reticle) M on which a predetermined pattern is formed by Cr. That is, in the mask M, light is shielded in a portion having Cr and light is transmitted in a portion having no Cr,
Light I is patterned. The light I transmitted through the mask M is
After being reduced to a predetermined size by the reduction projection lens L and irradiated onto the semiconductor wafer W coated with a resist (photosensitive agent), the resist is exposed.

At this time, the intensity distribution of the illuminance is determined by the shape of the opening of the revolver R in FIG. The revolver R is formed by forming openings having different shapes around a rotation axis in a circular metal plate. Then, for example, by rotating the revolver R to change the shape of the opening of the revolver R, the intensity distribution of the illumination can be changed.

[0005] Normally, a revolver R having several patterns of the shape of the opening is used to rotate and select arbitrarily. This can save the trouble of replacing the filter as compared with a case where a filter having a different opening shape is replaced.

FIG. 9 shows an example of a revolver R used in the exposure apparatus 38 shown in FIG. The revolver R has shape four openings R _A, R _B, R _C, comprising a R _D. Opening R
_A is an aperture for normal exposure in which the intensity distribution is a uniform normal distribution. Opening R _B is, at the opening of the case (annular illumination) for a ring-shaped intensity distribution, the center of the metal plate is supported hanging by a thin wire or the like. The opening R _C is an opening for shading light in a cross shape, whereby a light intensity distribution having four peaks can be formed. The aperture _RD is an aperture for narrowing the intensity distribution to the center.

[0007] Then, when used in normal exposure, the alignment is performed such that the center of the circular opening _RA coincides with the optical axis of the light I. On the other hand, when it is desired to use other modified illumination, as shown in FIG.
Rotate around ₁ and use the aperture to be used in alignment with the optical axis of light I.

As described above, the shape of the opening of the revolver R is selected according to the purpose, and the selection greatly affects the resolution, the depth of focus, and the pattern density dependency.

[0009]

However, such a conventional method of selecting the intensity distribution of the illuminance depends only on the type of the shape of the opening of the revolver R designed in advance, and the intensity distribution of the illuminance is Cannot be changed freely.

[0010] As shown in FIGS. 9 and 10, a revolver R having several types of opening shape patterns in advance.
Is difficult to estimate the required pattern and prepare it in advance, and when fine fine adjustment is required, it may not be possible to respond immediately.

In order to solve the above-mentioned problem, in the present invention, the exposure is performed by optimizing the resolution, the depth of focus, and the coarse / dense dependency of the pattern by freely changing the intensity distribution of the illumination system. It is an object of the present invention to provide an exposure apparatus capable of performing the above-described operations.

[0012]

SUMMARY OF THE INVENTION The present invention is an exposure apparatus having an illumination system filter capable of arbitrarily controlling the intensity distribution of transmitted light by controlling the transmittance.

According to the configuration of the present invention described above, by providing the illumination system filter capable of arbitrarily controlling the intensity distribution of the transmitted light by controlling the transmittance, the intensity distribution of the transmitted light can be arbitrarily formed. And can be applied to exposure of any pattern.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The exposure apparatus of the present invention has an illumination system filter capable of arbitrarily controlling the intensity distribution of transmitted light by controlling the transmittance.

Further, the present invention provides the above-described exposure apparatus, wherein the illumination system filter is made of a liquid crystal.

An embodiment of the exposure apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration diagram of an embodiment of the exposure apparatus of the present invention. This example is a case where the present invention is applied to reduction exposure projection onto a semiconductor wafer in a semiconductor manufacturing process.
The exposure device 8 includes a light source unit including a mercury lamp (UV lamp) 6 and an elliptical mirror 7, two mirrors 1 and 2 for changing an optical path, a shutter 5, a flyer lens 4,
An illumination system filter F according to the present invention, a reticle blind 3, a condenser lens D for equalizing light, a mask M having a predetermined exposure pattern, and a reduction projection lens L for reducing light to a predetermined size. Having. W indicates a semiconductor wafer to be exposed whose surface is coated with a resist (photosensitive agent).

In the exposure device 8, the light emitted from the mercury lamp 6 of the light source unit is changed in optical path by the mirror 2, passes through the shutter 5, is made uniform by the flyer lens 4, and is made uniform by the illumination system filter F. The intensity distribution of light is adjusted in. The light I whose light intensity distribution is adjusted passes through the reticle blind 3, passes through the condenser lens D and a mask (reticle) M on which a predetermined exposure pattern is formed by, for example, Cr by the optical path changed by the mirror 1, and is further reduced. The semiconductor wafer W is reduced to a predetermined size by the projection lens L and irradiated onto the semiconductor wafer W to expose the resist applied to the semiconductor wafer W.

The illumination system filter F is composed of a large number of micro shutters arranged in principle. Each shutter cell is turned on / off by electrical control to form a desired aperture pattern shape, and to transmit transmitted light. In this embodiment, the illumination system filter F is formed of a liquid crystal plate in which a number of fine liquid crystal cells are arranged.

That is, the illumination system filter F according to this embodiment
As shown in FIG. 2, a liquid crystal plate 10 in which a number of fine unit liquid crystal cells (hereinafter, referred to as liquid crystal cells) are arranged is supported by a filter frame 9.

Although not shown, a circuit for controlling each liquid crystal cell of the liquid crystal plate 10 is incorporated in the filter frame 9 so that the liquid crystal plate 10 can be controlled by software. An electric signal is sent to the control circuit in the filter frame 9 by software to change the orientation of the liquid crystal cell at an arbitrary position in the liquid crystal panel 10, thereby forming the opening 11 and the light shielding portion 12, for example, as shown in FIG. An opening shape can be freely formed inside the filter F, such as a narrow distribution as shown or a distribution with a shape as shown in FIG.

At this time, the electric signal sent to the control circuit has a signal indicating the position (address) of the liquid crystal cell and the state of alignment. Each liquid crystal cell is arranged at an arbitrary address in the filter F, and shows two types of alignment states, that is, a state where the optical path is opened and a state where the optical path is closed.

The operation of the liquid crystal plate 10 is shown in FIGS. FIG. 5 is a diagram illustrating a case where the orientation of the liquid crystal in each liquid crystal cell of the liquid crystal plate 10 is a state where the optical path is opened. Liquid crystal cell 1
The liquid crystal 14 in the liquid crystal layer 15 of each of the 0 liquid crystal cells is oriented parallel to the transmitted light, and the incident light 13 passes through as it is to become the transmitted light 16. Thereby, normal exposure can be performed.

When the optical path is closed by applying an electric signal to the liquid crystal cells corresponding to the three liquid crystals on the right in FIG. 5, the three liquid crystals on the right are aligned as shown in FIG. Close the light path. At this time, since the liquid crystal cells corresponding to the three liquid crystals on the right do not transmit light, the incident light 13 is transmitted light 17 that has passed through the liquid crystal cells corresponding to the two liquid crystals on the left.
Becomes

As described above, by controlling the orientation of the liquid crystal cell at each address, a portion through which light is transmitted and a portion through which light is blocked can be formed, and an arbitrary opening shape can be obtained.

In the above-described example, the liquid crystal cell is aligned in two states, that is, the state in which the optical path is opened and the state in which the optical path is closed. However, it is also possible to form a state in which the optical path is half-opened. . An example is shown below.

Similarly to the above-described example, by applying an electric signal from the state where the optical path is opened as shown in FIG. 5, the liquid crystal cell is brought into a half-open state where the optical path is slightly closed as shown in FIG. To At this time, the intensity of the incident light 13 becomes the transmitted light 18 in which the intensity is weakened, and a halftone light intensity distribution can be obtained.

Further, it is also possible to connect the control circuit of the liquid crystal plate 10 to a computer or the like to program-control the orientation of the liquid crystal cell at each position.

In each of the above examples, the light is shielded by using a filter incorporating a large number of liquid crystal cells. However, the present invention is similarly applicable to a case where light is shielded by forming a light shielding portion having another configuration. Can be applied.
For example, the light intensity distribution can be freely set by forming a blind light-shielding portion having a variable opening area and controlling the area and shape of the opening.

The exposure apparatus of the present invention can be used to form a fine pattern of a semiconductor device, a pattern of a TFT liquid crystal, a pattern of each part of a thin-film magnetic head, a pit pattern of an optical recording medium, and a circuit board. It can be applied to other pattern formation such as the above pattern.

The exposure apparatus of the present invention is not limited to the above-described example, and may take various other configurations without departing from the gist of the present invention.

[0031]

According to the exposure apparatus of the present invention described above,
Exposure can be performed with an illumination system having various illuminance distributions.

By constituting the illumination system filter with liquid crystal, it is possible to turn on / off each fine liquid crystal cell by electrical control and to form an aperture pattern of an arbitrary shape that can transmit light.

Therefore, according to the present invention, resolution, depth of focus,
It is possible to easily select an illumination system in which the dependency of the pattern on the density is optimized.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an exposure apparatus of the present invention.

FIG. 2 is a configuration diagram of an illumination system filter of the exposure apparatus of FIG.

FIG. 3 is a state diagram in one state of the illumination system filter of FIG. 2;

FIG. 4 is a state diagram in another state of the illumination system filter of FIG. 2;

FIG. 5 is a state diagram in which the state of alignment of the liquid crystal is a state in which an optical path is opened.

FIG. 6 is a state diagram in which an alignment state of a part of the liquid crystal is a state where an optical path is opened.

FIG. 7 is a state diagram when a halftone state is enabled.

FIG. 8 is a schematic configuration diagram of a conventional exposure apparatus.

FIG. 9 is a configuration example of a conventional revolver.

FIG. 10 is a diagram showing a use state of the revolver of FIG. 9;

[Explanation of symbols]

1, 2 mirror, 3 reticle blind, 4 fly-a-lens, 5 shutter, 6 mercury lamp (UV lamp), 7 elliptical mirror, 8 exposure device, 9 filter frame, 10 liquid crystal plate, 11 opening, 12 light shielding, 1
3 incident light, 14 liquid crystal, 15 liquid crystal layer, 16, 17, 1
8 transmitted light, 31, 32 mirror, 33 reticle blind, 34 flyer lens, 35 shutter, 36
Mercury lamp (UV lamp), 37 Elliptical mirror, 38 Exposure device, F illumination system filter, D condenser lens, M
Mask, L reduction projection lens, W semiconductor wafer, R
Revolver, I ray

Claims (2)

[Claims] 1. An exposure apparatus comprising an illumination system filter capable of arbitrarily controlling the intensity distribution of transmitted light by controlling transmittance. 2. The exposure apparatus according to claim 1, wherein the illumination system filter is formed of a liquid crystal.