JP2000021748A - Method of exposure and exposure equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To expose plural patterns to a substrate to be exposed to produce a superposed pattern on a same shot by dividing a luminous flux emitted from an exposure light source into plural ones and making each divided luminous flux illuminate a mutually different area of an exposure field by adjusting desired illuminating conditions for each. SOLUTION: A linearly polarized beam emitted from a laser beam source 1 is converted into a circular polarized beam by a λ/2 plate, and is launched to a polarizing beam splitter 3. The polarizing beam splitter 3 reflects s- polarized beam and passes p-polarized beam, dividing the beam that has passed the λ/2 plate into two luminous fluxes. The p-polarized beam passing through the polarizing beam splitter 3 is reflected by a mirror 4, is reflected by a mirror 7 and by one of the reflecting planes of a roof prism 9 after the illuminating conditions are controlled by an illumination system 5, and illuminates area A on a reticle 11. On the other hand, the s-polarized beam is reflected by a mirror 8 and by the other reflecting plane of the roof prism 9 after the illuminating conditions are controlled by an illumination system 6, and illuminates area B on the reticle 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an exposure method and an exposure apparatus, and more particularly to an exposure method and an exposure apparatus for exposing a fine circuit pattern onto a substrate to be exposed. Such an exposure method and an exposure apparatus are used, for example, in the manufacture of various devices such as semiconductor chips such as ICs and LSIs, display elements such as liquid crystal panels, detection elements such as magnetic heads, and imaging elements such as CCDs.

[0002]

2. Description of the Related Art At present, the mainstream of a projection exposure apparatus used for manufacturing devices such as ICs, LSIs and liquid crystal panels by using a photolithography technique uses an excimer laser as a light source. However, in a projection exposure apparatus using this excimer laser as a light source, a line width of 0.1
It is difficult to form a fine pattern of 5 μm or less.

In order to increase the resolution, it is theoretically necessary to increase the NA (numerical aperture) of the projection optical system or to reduce the wavelength of the exposure light. It is not easy to reduce the wavelength of the exposure light. That is, the depth of focus of the projection optical system is inversely proportional to the square of NA and proportional to the wavelength λ.
Is increased, the depth of focus becomes smaller, focusing becomes difficult, and productivity decreases. Also, the transmittance of most glass materials is extremely low in the far ultraviolet region, for example, λ = 248
Even fused silica used in nm (KrF excimer laser) drops to almost zero below λ = 193 nm. At present, a glass material that can be used practically in a region of an exposure wavelength λ = 150 nm or less corresponding to a fine pattern having a line width of 0.15 μm or less by ordinary exposure has not been realized.

Therefore, by performing double exposure of two-beam interference exposure and normal exposure on the substrate to be exposed, and by giving a multi-level exposure amount distribution to the substrate to be exposed at that time, higher resolution is achieved. Is disclosed in Japanese Patent Application No. 9-304232, "Exposure method and exposure apparatus".
(Hereinafter referred to as the prior application). According to this method, a pattern having a minimum line width of 0.10 μm can be formed by using a projection exposure apparatus in which the exposure wavelength λ is 248 nm (KrF excimer laser) and the image side NA of the projection optical system is 0.6. .

[0005]

By the way, in the embodiment of the prior application, the two-beam interference exposure is performed by so-called coherent illumination using a phase shift mask (or reticle) having a line width of 0.1 μmL & S (line and space). afterwards,
Normal exposure (for example, exposure by partial coherent illumination) is performed using a mask (or reticle) on which an actual element pattern having a minimum line width of 0.1 μm is formed. As described above, the double exposure method requires two exposure steps under different exposure conditions for each shot in order to form one pattern. For this reason, there is a problem that the throughput becomes slow.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the throughput of a multiple exposure method in which a plurality of types of patterns are overprinted on the same shot on a substrate to be exposed to form one type of pattern.

[0007]

In order to achieve the above object, the present invention divides a light beam emitted from one exposure light source into a plurality of light beams and sets each of the divided light beams to desired illumination conditions. Thus, different areas within one exposure field are illuminated.

[0008]

In order to improve the throughput of a multiple exposure system in which a plurality of types of patterns are overprinted on the same shot on a substrate to be exposed to form one type of pattern, the present inventors use these types of patterns. By forming the mask on one mask (or reticle), the replacement time of the mask (or reticle) was shortened. FIG. 2 shows a pattern (hereinafter, referred to as an F pattern) A such as the phase shift mask and a pattern (hereinafter, referred to as an R pattern) B such as an actual element pattern in one exposure field of one reticle. The state of the formation is shown. The illumination conditions such as σ and the exposure amount are different between the F pattern and the R pattern.

As described above, when there are regions with different illumination conditions in one reticle, in a conventional exposure apparatus having only one illumination system, the illumination region is limited by a masking blade for each region where the illumination condition of the reticle is the same. Then, two exposures of the F pattern and the R pattern are performed on one chip. Therefore, when the reticle of FIG. 2 is used, as shown in FIG.
The exposure had to be performed multiple times, and the throughput was reduced.

In the present invention, the case where the reticle shown in FIG. 2 is used will be described. As shown in FIG. 1, a light beam emitted from one exposure light source is divided into two and inserted into respective optical paths. After controlling the illumination conditions such as σ and the exposure amount by the illumination system, the pattern A and the pattern B are simultaneously illuminated with different light beams and exposed. Thus, one exposure field can be simultaneously exposed under two illumination conditions by one exposure. Therefore, if the substrate to be exposed is exposed by the step-and-repeat or step-and-scan method while moving stepwise by, for example, シ ョ ッ ト shots, it is possible to perform 露 光 exposure in one exposure operation per の area of the exposure field. Assuming that a shot corresponds to one chip, all the chips except the end chip can be double-exposed with the pattern A and the pattern B.

As a result, the number of times of the exposure operation is reduced to about 1/2 of that in FIG. 3, and the throughput is improved about twice.
This effect of improving the throughput is even more remarkable in triple or multiple exposure.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a preferred embodiment of the present invention, the exposure light source is a laser light source, and when illuminating two areas on the original under two illumination conditions, the light emitted from the laser light source is λ / After passing through the two plates, the light is split into two by a polarizing beam splitter, and the λ / 2 plate is rotated to control the split ratio of the two light beams. This makes it possible to arbitrarily set the exposure amounts of the two regions without loss of light amount.

[0013] Further, a configuration is adopted in which the split light beam is reflected by a roof prism to two regions in one exposure field, and the roof prism is made movable, so that the area ratio of the two regions is made variable. Can be.
When there is a relatively narrow pattern width portion requiring double exposure and a relatively wide pattern width portion sufficient in the conventional exposure method in one chip, the area of the F pattern is reduced to reduce the area of the R pattern. By increasing the area, the shot area can be increased, which is useful for improving the throughput. An exposure apparatus according to a preferred embodiment of the present invention is a scanning projection exposure apparatus that exposes a pattern image of an original onto a substrate to be exposed by scanning the original and the substrate to be exposed synchronously and relatively with a projection optical system. A plurality of pattern areas are arranged in the scanning direction on an original, have a plurality of apparatus offsets corresponding to respective areas in one job, and various apparatuses are arranged at boundaries of the pattern areas during scanning exposure. The offset is switched. For example, since the exposure of the phase shift mask (F pattern) is performed using light passing through the periphery of the projection lens, the focus and tilt are deviated from the exposure of the R pattern due to the influence of aberration. Also, the relative displacement between the F pattern and the R pattern on the reticle is measured in advance at the time of alignment of the reticle or wafer by providing alignment marks for the F pattern and the R pattern, and is switched at the boundary during scanning exposure. .

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of an exposure apparatus according to one embodiment of the present invention. In the figure, 1 is a laser light source such as a KrF excimer laser, 2 is a λ / 2 plate, 3 is a polarization beam splitter,
4, 7, 8 are mirrors, 5, 6 are illumination systems, 9 is a roof prism, 11 is a reticle, 12 is a projection lens, and 15 is a wafer.

The linearly polarized light emitted from the laser light source 1 is
The light is converted into circular or elliptically polarized light by the λ / 2 plate 2 and enters the polarization beam splitter 3. The polarization beam splitter 3 reflects the s-polarized light and passes the p-polarized light, and
The light that has passed through the two plates 2 is split into two light beams. The p-polarized light that has passed through the polarization beam splitter 3 is reflected by a mirror 4, and after its illumination conditions (such as σ and exposure amount) are controlled by an illumination system 5, is reflected by a mirror 7 and one reflection surface 9 a of a roof prism 9. To illuminate the area A on the reticle 11. On the other hand, the s-polarized light reflected by the polarization beam splitter 3 is incident on the illumination system 6, and the illumination condition (σ
And the exposure amount are controlled, the light is reflected by the mirror 8 and the other reflection surface 9b of the roof prism 9 to illuminate the area B on the reticle 11. Thereby, the reticle 11
The pattern images of the upper regions A and B are simultaneously projected onto the wafer 15 by the projection lens 12 and exposed. By providing two illumination systems for one light source 1 and simultaneously exposing two areas on one reticle under different illumination conditions, the number of exposures per wafer is shown in FIGS. The conventional example can be reduced to about 1/2, and the throughput can be improved about twice.

The illumination condition is such that a pattern formed in each region on the reticle 11 is a phase shift pattern (F pattern).
And the actual element pattern (R pattern), for example, F
The illumination condition of the pattern is σ = 0.3-0.2, the illumination condition of the R pattern is σ = 0.6-0.8, and the exposure amount is 2-3 times that of the F pattern. In the present embodiment, the λ / 2 plate 2 is rotated according to such a light amount ratio, and the ratio of the p-polarized light to the s-polarized light of the light beam incident on the polarizing beam splitter 3, that is, the light beam splitting by the polarizing beam splitter 3 Control the ratio. As described above, by using the λ / 2 plate 2, two types of exposure amounts can be arbitrarily set without loss of light amount.

This embodiment can be applied to both a step-and-repeat type exposure apparatus (stepper) and a step-and-scan type exposure apparatus (scanning projection exposure apparatus). When applied to a scan type exposure apparatus, various apparatus offsets such as focus, tilt, and alignment can be instantaneously switched at a boundary between two areas of the same reticle during scanning, and two jobs are included in one job. To have two device offsets.

[0018]

Next, an embodiment of a device production method using the above-described projection exposure apparatus or method will be described. FIG. 4 shows a micro device (a semiconductor chip such as an IC or an LSI, a liquid crystal panel, a CCD, a thin film magnetic head,
2 shows a flow of manufacturing a micromachine or the like. Step 1
In (Circuit Design), a device pattern is designed. Step 2 is a process for making a mask on the basis of the designed pattern. Step 3 (wafer manufacturing)
Then, a wafer is manufactured using a material such as silicon or glass. Step 4 (wafer process) is called a pre-process,
An actual circuit is formed on the wafer by lithography using the prepared mask and wafer. The next step 5 (assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). including. In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 5 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed on the wafer by exposure using the above-described exposure apparatus or method. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer.

By using the production method of this embodiment, it is possible to produce a highly integrated device, which was conventionally difficult to produce, at low cost.

[0021]

As described above, according to the present invention, a plurality of regions are provided in one exposure field so that appropriate illumination conditions can be set for each region, so that a plurality of types of patterns are simultaneously exposed. Therefore, it is possible to improve the throughput of the multiple exposure in which the patterns formed in the plurality of regions are overprinted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a double exposure apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a reticle used in the apparatus of FIG.

FIG. 3 is an explanatory diagram in the case of performing exposure with a conventional exposure apparatus using the reticle of FIG. 2;

FIG. 4 is a diagram showing a flow of manufacturing a micro device.

FIG. 5 is a diagram showing a detailed flow of a wafer process in FIG. 4;

[Explanation of symbols]

1: laser light source, 2: λ / 2 plate, 3: polarizing beam splitter, 4, 7, 8: mirror, 5, 6: illumination system, 9: roof prism, 11: reticle, 12: projection lens, 15:
Wafer.

Claims (12)

[Claims] 1. A light beam emitted from one exposure light source is divided into a plurality of light beams, and the divided light beams are set to desired illumination conditions to illuminate different regions in one exposure field. Exposure method. 2. The exposure method according to claim 1, wherein an original plate on which different types of patterns are formed corresponding to different regions in the one exposure field is used. 3. When the exposure light source is a laser light source and the two regions on the original are illuminated under two illumination conditions, the light emitted from the laser light source passes through a λ / 2 plate, and then a polarization beam splitter. 3. The exposure method according to claim 1, further comprising: dividing the light beam into two by rotating the λ / 2 plate, and controlling a division ratio of the two light beams. 4. The apparatus according to claim 1, wherein the light beam split into two is reflected by a roof prism to two areas in the one exposure field, and the roof prism is made movable to change the area ratio of the two areas. Item 4. The exposure method according to Item 3. 5. A scanning projection exposure method for exposing images of said plurality of patterns on said substrate to be exposed by scanning said master and said substrate to be exposed synchronously relative to a projection optical system. The plurality of areas are arranged in the scanning direction on the original, have a plurality of apparatus offsets corresponding to each area in one job, and switch various apparatus offsets at the boundaries of the areas during scanning exposure. Claim 1 to claim
4. The exposure method according to any one of 4. 6. A means for dividing a light beam emitted from one exposure light source into a plurality of light beams, a desired exposure condition is set for each of the divided light beams, and different regions in one exposure field are set by each light beam. An exposure apparatus comprising: an illumination system for illuminating. 7. The exposure apparatus according to claim 6, wherein originals on which different types of patterns are formed corresponding to different regions in the one exposure field are used. 8. The exposure light source is a laser light source, a polarization beam splitter for dividing the laser light source into two, and a λ disposed between the laser light source and the polarization beam splitter.
/ 2 plate, and means for controlling the light amount ratio of the two light beams split by the polarizing beam splitter by rotating the λ / 2 plate, wherein different types of two regions in the one exposure field are provided. 8. The exposure apparatus according to claim 6, wherein said pattern can be exposed simultaneously. 9. A roof prism for reflecting the split light beam to two regions in the one exposure field, and means for changing the area ratio of the two regions by moving the roof prism. 9. The exposure method according to claim 8, wherein: 10. A scanning projection exposure apparatus for exposing the plurality of pattern images on the substrate to be exposed by scanning the original and the substrate to be exposed synchronously and relatively to a projection optical system. The plurality of areas are arranged in the scanning direction on the original, have a plurality of apparatus offsets corresponding to each area in one job, and switch various apparatus offsets at the boundaries of the areas during scanning exposure. Claim 6
An exposure apparatus according to any one of claims 1 to 9. 11. A device manufacturing method, comprising manufacturing a device using the exposure method according to claim 1 or the exposure apparatus according to claim 6. 12. A device manufactured by the device manufacturing method according to claim 11.