JPH07142334A - Aligner - Google Patents

Abstract

PURPOSE:To switch an exposure using a pupil surface filter and that without using it without attaching and detaching the pupil surface filter by providing a means for changing the polarization state of illumination light for applying light to a pattern on a first object surface. CONSTITUTION:In a lighting system 100, a flux of light from a light source 11 is focused on a reticle 1 where light is applied by a capacitor lens 12. A polarization direction selection element 13 is laid out between the capacitor lens 12 and the reticle 1. A polarization plate and 1/2-wavelength plate are available as the polarization direction selection element 13. Also, the polarization direction selection element 13 can be constituted so that the angle of a polarization axis or that of an optical axis can be adjusted within a surface crossing a light axis by an adjustment mechanism or a plurality of polarization direction selection elements can be selectively switched.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exposure apparatus, and more particularly to an exposure apparatus used for manufacturing semiconductor devices such as IC and LSI, imaging devices such as CCD, display devices such as liquid crystal panels, and devices such as magnetic heads.

[0002]

2. Description of the Related Art As semiconductor devices such as ICs and LSIs are highly integrated, the acceleration is further increasing, and along with this, the progress of fine workability technology for semiconductor wafers is remarkable. The projection exposure technique, which is the center of this fine processing technique, is currently being improved in resolution so as to form an image having a size of 0.5 μm or less.

There is a method of shortening the wavelength of the exposure light in order to improve the resolution, but if the wavelength is shortened, the type of glass material that can be used for the projection lens is limited, and it becomes difficult to correct chromatic aberration.

As a projection optical system in which the load related to the correction of chromatic aberration is reduced, an image is formed mainly by the power of a concave mirror, and a beam splitter is used in the projection optical system to further enlarge the exposure area. There is an exposure apparatus that uses a catadioptric optical system composed of a beam splitter and a lens group.

[0005]

The exposure apparatus using this catadioptric optical system has a wide exposure area and high resolution,
It cannot be said that the depth of focus is deep enough.

In recent years, the margin of the depth of focus has become smaller as the line width becomes finer, and various techniques for increasing the depth of focus have been studied, and a predetermined complex amplitude transmission to the pupil plane of the projection optical system has been studied. There is a technique of increasing the depth of focus by arranging an optical filter having a rate distribution.

The image forming technique using the pupil plane filter has a great effect on a specific pattern, but is not always effective on other patterns, and adverse effects may occur on the contrary. .

Therefore, in an actual apparatus, a mechanism for attaching and detaching the pupil plane filter is required so that the image forming method can be changed. However, since the projection optical system is manufactured with extremely high accuracy and the assembly accuracy is also required to be very high, it is difficult to attach / detach the pupil filter and always incorporate it with high accuracy.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide an improved exposure apparatus which solves the above problems.

A first form of an exposure apparatus of the present invention is an exposure apparatus having a projection optical system for projecting a pattern on a first object plane onto a second object plane, wherein the projection optical system is the first
A polarization beam splitter that splits a light beam from the object plane into reflected light and transmitted light; first and second mirrors that respectively reflect the transmitted light and the reflected light split by the polarized beam splitter; and the polarization beam splitter. A first quarter wave plate disposed between the first and second mirrors, and an optical filter disposed near at least one of the first and second mirrors. , A means for changing the polarization state of the illumination light for illuminating the pattern on the first object plane.

The second form of the exposure apparatus of the present invention is the first form.
In an exposure apparatus having a projection optical system for projecting a pattern on an object plane onto a second object plane, the projection optical system may include a first optical system.
A first lens group having a positive refractive power that receives a light beam from the object surface, a polarization beam splitter that separates the light beam from the first lens group into a reflected light and a transmitted light, and a polarization beam splitter that separates the light beam First and second concave mirrors for reflecting and condensing transmitted light and reflected light, respectively, and first and second quadrants arranged between the polarization beam splitter and the first and second concave mirrors. Of the first wavelength plate and the second quarter-wave plate having a positive refracting power for condensing the light beam that has passed through the first and second quarter-wave plates and passed through the polarization beam splitter onto the second object plane. An optical filter having a complex amplitude transmittance distribution is disposed near at least one of the first and second concave mirrors.
It is characterized in that means for changing the polarization state of the illumination light for illuminating the pattern on the object plane is provided.

The means for changing the polarization state of the illumination light selects, as the illumination light, either S-polarized light or P-polarized light reflected or transmitted by the polarization beam splitter.

In the exposure apparatus of the present invention, the exposure using the pupil plane filter of the projection optical system and the exposure not using it can be easily used separately.

If the exposure apparatus of the present invention is used, IC and LS
It is possible to accurately manufacture semiconductor devices such as I, imaging devices such as CCDs, display devices such as liquid crystal panels, and devices such as magnetic heads.

[0015]

1 and 2 are schematic block diagrams showing an embodiment of the present invention, which is a semiconductor device such as an IC or LSI, or a CCD.
2 shows a scanning projection exposure apparatus for accurately manufacturing an image pickup device such as a display device, a display device such as a liquid crystal panel, and a device such as a magnetic head.

In FIGS. 1 and 2, reference numeral 1 is a reticle on which a circuit pattern of a semiconductor element transferred onto a wafer is drawn, and 100 is an illumination system for illuminating the reticle 1. In the illumination system 100, the light flux from the light source 11 is condensed by the condenser lens 12 on the reticle 1 which is the surface to be illuminated. A polarization direction selection element 13 is arranged between the condenser lens 12 and the reticle 1. As the polarization direction selection element 13, there is a polarizing plate or a half-wave plate.
In addition, the polarization direction selection element 13 can be configured to adjust the polarization axis or the angle of the optical axis in a plane orthogonal to the optical axis by an adjustment mechanism (not shown), or a plurality of polarization direction selection elements can be selectively replaced. Configure as follows.

By using this polarization direction selection element 13 (with an adjusting mechanism), the polarization directions of the reticle 1 are changed depending on whether or not the pupil plane filter 10 is used for imaging the device pattern of the reticle 1. It can be illuminated by one of two different polarized illumination lights.

First, the case where a reduced image of the device pattern of the reticle 1 is formed on the wafer surface 9 without using the pupil plane filter 10 in FIG. 1 will be described. The polarization direction selection element 13 of the illumination system 100 is adjusted to illuminate the reticle 1 with P-polarized light having a polarization plane in the plane of the drawing. The P-polarized light beam from the reticle 1 has a lens 2 having a positive refractive power.
Is incident on the polarization beam splitter 3, and is P-polarized. Therefore, it passes through the polarization separation surface 3a of the polarization beam splitter 3 and is transmitted to the quarter-wave plate 4a. Incident.

The P-polarized light transmitted through the polarization beam splitter 3 is converted into circularly polarized light by the quarter-wave plate 4a, reflected and condensed by the concave mirror 5a, transmitted again through the quarter-wave plate 4a, and then circularly reflected. The polarized light is converted into S-polarized light. This light flux enters the polarization beam splitter 3, is reflected downward by the polarization splitting surface 3a thereof, and is incident on the quarter-wave plate 6 which is the polarization varying means. This light beam is converted from S-polarized light into circularly polarized light again by the quarter-wave plate 6 and is condensed on the wafer surface 9 by the positive lens 7 to form a reduced image of the device pattern of the reticle 1 on the wafer surface 9.

Next, a case where a projected image of the device pattern of the reticle 1 is formed using the pupil filter 10 will be described with reference to FIG. By adjusting the polarization direction selection element 13 in the illumination system 100, the reticle 1 can be moved in the direction S perpendicular to the paper surface.
Illuminate with a polarized light beam. The S-polarized light beam from the reticle 1 enters the positive lens 2, is converted into a substantially parallel light beam by the positive lens 2, and enters the polarization beam splitter 3. Since this light flux is S-polarized light, it is reflected upward by the polarization splitting surface 3a of the polarization beam splitter 3 and
It is converted into circularly polarized light by the half-wave plate 4b and transmitted through the pupil plane filter 10. The pupil plane filter 10 has a predetermined complex amplitude transmittance distribution, and the light transmitted through the pupil plane filter 10 has a phase and an amplitude at each position of its wavefront according to the complex amplitude transmittance distribution of the pupil surface filter 10. After being modulated, it is reflected and condensed by the concave mirror 5b, is incident on the pupil surface filter 10 again, and the phase and amplitude are modulated by the pupil surface filter 10. Since the pupil plane filter 10 of the present invention passes a light ray twice, it is designed and manufactured so that it becomes 1/2 of a desired phase amplitude modulation for one transmission. The light flux that has passed through the pupil filter 10 passes through the quarter-wave plate 4b and is converted from circularly polarized light to P-polarized light. Since this light beam enters the polarization beam splitter 3 and is P-polarized light,
The light is transmitted through the polarization splitting surface 3a, converted from P-polarized light into circularly polarized light by the quarter-wave plate 6, and condensed on the wafer surface 9 by the positive lens 7 to perform pupil surface filtering of the device pattern of the reticle 1. A reduced image is formed on the wafer surface 9.

In the apparatus of this embodiment, the illumination system 1 is thus
Only by adjusting the polarization direction selection element 13 in 00 to select the polarization state of the illumination light that illuminates the reticle 1, the same effect as switching the pupil plane filter with the same projection optical system can be obtained.

The quarter-wave plate 6 shown in FIG.
Has the function of changing the polarization direction of light incident on. This is because in the case of imaging a fine pattern, there is a difference in image performance depending on the extending direction of the fine pattern and the polarization direction of light, and therefore it is desirable to convert linearly polarized light into an arbitrary polarization state. In the case of this embodiment, in order to eliminate the difference in image performance due to the direction difference between the vertical pattern and the horizontal pattern, a quarter wave plate is used to convert linearly polarized light into circularly polarized light.
Of course, in addition to the quarter-wave plate, a half-wave plate may be sufficient.

Although the lens 2 shown in this embodiment is a collimator lens, the lens 2 may be a non-collimator lens.

In the projection optical system shown in this embodiment, the lens group is not arranged between the polarization beam splitter and the concave mirror, but it is also possible to arrange the lens group between them.

This embodiment can be used in an exposure apparatus for performing step & repeat exposure.

In this embodiment, the exposure using the pupil plane filter and the exposure not using the pupil surface filter were easily switched.
Two pupil plane filters with different complex amplitude transmittance distributions
It is also possible to provide each concave mirror and switch the exposure using each pupil plane filter.

Next, an embodiment of a method of manufacturing a semiconductor device using the exposure apparatus shown in FIGS. FIG. 3 shows a semiconductor device (semiconductor chip such as IC or LSI, liquid crystal panel or C
The manufacturing flow of CD) is shown. In step 1 (circuit design), the circuit of the semiconductor device is designed. In step 2 (mask manufacturing), a mask (reticle 304) on which the designed circuit pattern is formed is manufactured. On the other hand, in step 3 (wafer manufacturing), a wafer (wafer 306) is manufactured using a material such as silicon. Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) called a post-process, a chip the steps 4 thus wafers created, an assembly step (dicing, Bonde _b ring), a packaging process (chip encapsulation) Including steps. In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. Through these steps, the semiconductor device is completed and shipped (step 7).

FIG. 4 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer (wafer 306) is oxidized. Step 12 (CV
In D), an insulating film is formed on the surface of the wafer. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 15 (resist processing)
Then, a resist (photosensitive material) is applied to the wafer. In step 16 (exposure), the projection exposure apparatus exposes the wafer with an image of the circuit pattern of the mask (reticle 304). In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist are scraped off. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, a circuit pattern is formed on the wafer.

The use of the manufacturing method of this embodiment makes it possible to manufacture highly integrated semiconductor devices.

[0030]

As described above, according to the present invention, it is possible to easily switch between the exposure using the pupil plane filter and the exposure not using the pupil plane filter without performing the complicated work of attaching and detaching the pupil plane filter. Also, switching can be easily performed when different pupil plane filters are used.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention and an explanatory diagram showing normal image formation.

FIG. 2 is a schematic configuration diagram of the same device as FIG. 1 showing an embodiment of the present invention, and is an explanatory diagram showing an image formed by performing pupil plane filtering.

FIG. 3 is a flowchart showing manufacturing steps of a semiconductor device.

FIG. 4 is a flow chart diagram illustrating details of a wafer process during the process of FIG.

[Explanation of symbols]

 1 Reticle 2 Positive lens group 3 Polarizing beam splitter 3a Polarization separating surface 4a, 4b Quarter wave plate 5a, 5b Concave mirror 6 Quarter wave plate 7 Positive lens group 9 Wafer 10 Pupil filter 11 Light source 12 Condenser lens 13 Polarization Direction Selection Element 100 Illumination Optical System

[Procedure amendment]

[Submission date] July 21, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03F 7/20 521 9122-2H

Claims (3)

[Claims] 1. An exposure apparatus having a projection optical system for projecting a pattern on a first object plane onto a second object plane, wherein the projection optical system reflects the light flux from the first object plane as reflected light and transmitted light. Between the polarization beam splitter and the first and second mirrors, and the first and second mirrors that respectively reflect the transmitted light and the reflected light split by the polarization beam splitter. Illuminating a pattern on the first object plane, including first and second quarter-wave plates arranged and an optical filter arranged near at least one of the first and second mirrors. And a means for changing the polarization state of the illumination light to be exposed. 2. An exposure apparatus having a projection optical system for projecting a pattern on a first object plane onto a second object plane, wherein the projection optical system has a positive refractive power for receiving a light beam from the first object plane. A first lens group, a polarization beam splitter that separates the light flux from the first lens group into reflected light and transmitted light, and the transmitted light and reflected light separated by the polarized beam splitter are reflected and condensed respectively. First and second concave mirrors, first and second quarter-wave plates arranged between the polarizing beam splitter and the first and second concave mirrors, and the first and second concave mirrors. A second lens group having a positive refracting power for condensing on the second object plane the light flux that has passed through the two quarter-wave plate and passed through the polarization beam splitter; A complex near at least one of the second concave mirrors A projection exposure apparatus, wherein an optical filter having an amplitude transmittance distribution is arranged, and means for changing a polarization state of illumination light for illuminating the pattern on the first object plane is provided. 3. The polarization beam splitter and the second beam splitter
The exposure apparatus according to claim 2, further comprising polarization changing means between the object plane.