JPH0774082A - Aligner and manufacture of semiconductor chip using the same - Google Patents

Abstract

PURPOSE:To detect the positional information of a mark image with high accuracy by imaging the alignment mark on a wafer face on the image formation face of a CCD camera, using a detection light different in wavelength from an exposure light. CONSTITUTION:A detection light, which has come out of the light source 14 consisting of the halogen lamp issuing a beam 9 (nonexposure beam) different in wavelength from exposure light, is applied to the alignment mark 4 on a wafer 3, passing through a lens 15, a beam splitter 16, a mirror M1, and an objective 12 in order. And, the information on the observed image of the alignment mark 4 on the wafer 3 is imaged on a CCD camera 13, passing through the objective 12, a mirror M1, a beam splitter 16, a beam splitter 20, a mirror M2, and a erector lens 21 in order. Hereby, it becomes possible to detect the positional information of the mark image with high accuracy in case of detecting the mark.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and a semiconductor chip manufacturing method using the same, and more particularly to a projection lens system for forming a fine electronic circuit pattern such as IC or LSI formed on a reticle (mask) surface. An exposure apparatus having a function of projecting light onto a wafer surface by (projection optical system) and observing the state of an alignment mark on the wafer surface with a CCD camera with light having a wavelength different from that for the exposure, and the same. The present invention relates to a method of manufacturing a semiconductor chip.

[0002]

2. Description of the Related Art In a minute projection type exposure apparatus for semiconductor manufacturing, a circuit pattern of a reticle as a first object is projected onto a wafer as a second object by a projection lens system and exposed. The alignment mark (AA mark) on the wafer is detected by observing the wafer surface using an observation device (detection means), and based on the detection result, the reticle and the wafer are aligned, that is, so-called alignment is performed. .

The alignment accuracy at this time largely depends on the optical performance of the observation apparatus. Therefore, the performance of the observation device is an important factor in the exposure device.

Conventionally, an alignment mark (AA mark) formed on a wafer surface in an exposure apparatus is observed by an observation microscope system, and the position of the alignment mark is detected using an image signal projected on the image pickup means surface of a CCD camera. However, it is often practiced to obtain wafer position information.

Particularly in recent years, non-exposure light having a relatively wide wavelength range has been used as observation illumination light mainly for the following two reasons.

The first reason is that when observing an alignment mark formed on a wafer surface, a photosensitive material (resist) for transferring an electronic circuit pattern is often applied on the wafer surface. Since the resist usually absorbs a lot at the exposure wavelength, it becomes difficult to detect the alignment mark on the wafer through the resist film at the exposure wavelength. However, there is a problem in that the detection of the alignment mark becomes unstable due to exposure to light, or it becomes impossible to detect it. Therefore, a detection method using non-exposure light is desired.

The second reason is that, when light having a relatively wide wavelength range, such as a halogen lamp, is used as the illumination light for observing the non-exposure light, a monochromatic light source such as a He--Ne laser is used on the wafer. It is possible to reduce interference fringes due to film thickness unevenness of the resist film and various functional films used in the semiconductor process, which tend to occur when the AA mark is observed, and it is possible to perform better alignment.

For these reasons, the alignment mark observing microscope system is designed to be able to detect the alignment mark favorably by the non-exposure light and the illumination light for observation having a relatively wide wavelength width.

[0009]

In the recent exposure apparatus for semiconductor manufacturing, alignment marks on the wafer surface are CC-aligned.
There is a method of detecting the position of a wafer by forming it on the surface of an image pickup means of a D camera and obtaining position information of the AA mark obtained by the image pickup means.

However, when the position of the alignment mark is detected using the detection signal from the CCD camera as described above, a measurement error (hereinafter
It is called "measurement linearity error". ) May occur and the alignment accuracy may be degraded.

FIG. 2 is an explanatory diagram showing the occurrence of measurement linearity error. The same figure shows the relationship between the position of the stage when the alignment mark formed on the wafer surface is moved by the stage and the measurement value obtained by detecting the position of the alignment mark using the detection signal photoelectrically converted by the CCD camera. ing. In this way, there is an error in the sinusoidal curve having a cycle corresponding to the pixels of the CCD camera.

Although the maximum value of the measurement error varies depending on the image quality of the alignment mark image projected by the observation microscope system, it may reach the amount equivalent to 1/2 of the pixels of the CCD camera, which deteriorates the measurement accuracy. In some cases, it was a major cause.

According to the present invention, the detection light (alignment light) having a wavelength different from that of the exposure light is used to form an alignment mark (hereinafter, simply referred to as "mark") on the wafer surface on the image pickup surface of the CCD camera. An object of the present invention is to provide an exposure apparatus having an improved mark detection function, which can detect the position information of the mark image with high accuracy when detecting the mark, and a semiconductor chip manufacturing method using the same. .

[0014]

The present invention solves the problem that a measurement error occurs due to the influence of pixels of an image pickup means of a CCD camera (hereinafter, also simply referred to as "CCD camera"), and alignment accuracy is deteriorated. In addition, when an image projected by an observation microscope system for observing the alignment mark on the wafer is picked up by a CCD camera and photoelectrically converted, and the position of the alignment mark is detected using this detection signal, one pixel of the CCD camera is used. The position of the alignment mark is determined based on a plurality of position information detected at a plurality of different positions within a corresponding range.

For example, the position of the alignment mark is determined based on two pieces of position information detected at positions different from each other by an amount corresponding to approximately ½ of the pixels of the CCD camera, whereby the measurement error due to the influence of the pixels of the CCD camera. The effect of is reduced and the alignment accuracy is improved.

Next, the exposure apparatus of the present invention and the method of manufacturing a semiconductor chip using the same will be specifically described.

First, the exposure apparatus of the present invention comprises: (1-1) a projection lens system for projecting a pattern of a first object onto a second object with exposure light, and a second detection light system with detection light having a wavelength different from that of the exposure light. Illuminate the object and CC the mark on the second object
An image is formed on the image pickup means surface of the D camera, the position information of the mark is detected at a plurality of different positions within a range corresponding to one pixel of the image pickup means, and the position information of the mark is detected based on the detection result of the position information of the mark. It is characterized by having a detecting means for performing relative alignment between the first object and the second object.

(1-2) A projection lens system for projecting the pattern of the first object onto the second object with the exposure light, and the second object with the detection light having a wavelength different from that of the exposure light to illuminate the second object. An image of the mark on the object is formed on the surface of the image pickup means of the CCD camera, the position information of the mark is detected at different positions corresponding to approximately 1/2 of the pixels of the image pickup means, and the detection result of the position information of the mark is detected. It is characterized by having a detection means for performing relative alignment between the first object and the second object based on the above.

(1-3) A projection lens system for projecting the pattern of the first object onto the second object with the exposure light, and the second object with the detection light having a wavelength different from that of the exposure light to illuminate the second object. When an image of the mark on the object is formed on the surface of the image pickup means of the CCD camera,
The movable optical member provided in the optical path is slightly displaced to form an image at a plurality of positions on the surface of the image pickup means, and the first object is detected based on the detection result of the position information of the mark at the plurality of positions. It is characterized by having a detection means for performing relative position alignment with the second object.

In particular, it is characterized in that the optical member is composed of a plane parallel plate which can be tilted with respect to the optical axis, and the optical member is composed of a wedge member which is rotatable with respect to the optical axis. .

(1-4) A projection lens system for projecting the pattern of the first object onto the second object with the exposure light, and the second object with the detection light having a wavelength different from that of the exposure light to illuminate the second object. When an image of the mark on the object is formed on the surface of the image pickup means of the CCD camera,
The surface of the image pickup means is slightly displaced in a plane orthogonal to the optical axis to form images at a plurality of positions on the surface of the image pickup means, and based on the detection result of the position information of the mark at the plurality of positions, It is characterized by having a detecting means for performing relative alignment between the first object and the second object.

In particular, the plurality of positions on the surface of the image pickup means are two different positions, which are approximately half the amount of pixels of the image pickup means.

The semiconductor chip manufacturing method of the present invention includes: (2-1) Detecting the alignment mark on the wafer by the detecting means using the detection light that does not expose the wafer, and obtaining the mark based on the detection. The wafer is aligned according to the position information of the mark image, and the image of the circuit pattern is projected onto the wafer through the projection lens system by illuminating the circuit pattern of the mask with the exposure light that exposes the wafer. When manufacturing a semiconductor chip by transferring by transfer, the detection means forms an image of the mark on the wafer surface on the imaging means surface of the CCD camera, and at a plurality of different positions within a range corresponding to one pixel of the imaging means. It is characterized in that the position information of the mark is detected, and the relative position of the mask and the wafer is adjusted based on the detection result of the position information of the mark.

(2-2) The detection mark which does not expose the wafer to light is used to detect the alignment mark on the wafer by the detection means, and the alignment of the wafer is performed based on the position information of the mark image obtained based on the detection. When a semiconductor chip is manufactured by projecting and transferring an image of the circuit pattern onto the wafer through a projection lens system by illuminating the circuit pattern of the mask with exposure light that exposes the wafer, the detection means Forms an image of the mark on the wafer surface on the surface of the image pickup means of the CCD camera, detects the position information of the mark at different positions corresponding to approximately 1/2 of the pixels of the image pickup means, and detects the position information of the mark. The relative position of the mask and the wafer is adjusted based on the detection result of 1.

(2-3) The detection mark which does not expose the wafer to light is used to detect the alignment mark on the wafer by the detection means, and the alignment of the wafer is performed based on the position information of the mark image obtained based on the detection. When a semiconductor chip is manufactured by projecting and transferring an image of the circuit pattern onto the wafer through a projection lens system by illuminating the circuit pattern of the mask with exposure light that exposes the wafer, the detection means Makes a minute displacement of a movable optical member provided with the mark on the wafer in the optical path to form an image at a plurality of positions on the image pickup means surface of the CCD camera, and displays the position information of the mark at the plurality of positions. It is characterized in that the relative alignment between the mask and the wafer is performed based on the detection result.

In particular, the plurality of positions on the surface of the image pickup means are different positions which are approximately ½ of the pixels of the image pickup means.

(2-4) The detection mark which does not expose the wafer to light is used to detect the alignment mark on the wafer by the detection means, and the alignment of the wafer is performed based on the position information of the mark image obtained based on the detection. When a semiconductor chip is manufactured by projecting and transferring an image of the circuit pattern onto the wafer through a projection lens system by illuminating the circuit pattern of the mask with exposure light that exposes the wafer, the detection means Forms a mark on the wafer surface at a plurality of positions on the surface of the image pickup means that is displaceable in a plane orthogonal to the optical axis, and determines the relative position between the mask and the wafer based on the detection result of the position information of the mark. The feature is that they are aligned.

[0028]

FIG. 1 is a schematic view of a main part of an optical system of Example 1 when the present invention is applied to an exposure apparatus for manufacturing a semiconductor device.

In the figure, numeral 8 is a reticle (also called a mask) as a first object, which is placed on the reticle stage 10. A wafer 3 is a second object, and an alignment mark (also referred to as an AA mark or a mark) 4 is provided on the surface of the wafer. A projection optical system 5 is composed of a projection lens system and projects a circuit pattern or the like on the reticle (mask) 8 surface onto the wafer 3 surface. The projection lens system 5 is a telecentric system on both the reticle 8 side and the wafer 3 side.

An illumination system 9 illuminates the reticle 8 with exposure light. Reference numeral 2 denotes a θ, Z stage on which the wafer 3 is placed, and θ rotation and focus adjustment of the wafer 3, that is, Z
We are adjusting the direction. The θ, Z stage 2 is mounted on the XY stage 1 for performing the step operation with high accuracy. An optical square (bar mirror) 6 that serves as a reference for measuring the stage position is placed on the XY stage 1.
The optical square 6 is monitored by a laser interferometer 7.

In the present embodiment, the alignment between the reticle 8 and the wafer 3 is performed indirectly by aligning the respective reference marks 17, which will be described later, whose positional relationship is determined in advance. Alternatively, the resist image pattern or the like is actually aligned and exposed, the error (offset) is measured, and offset processing is performed in consideration of the value thereafter.

Next, each element of the detecting means 101 for detecting the position of the mark 4 on the surface of the wafer 3 will be described.

An observation microscope 11 observes the AA mark 4 on the surface of the wafer 3 with non-exposure light. In this embodiment, an off-axis method is used in which alignment is performed without the projection lens 5.

Reference numeral 14 denotes a light source for detecting the AA mark 4, which is composed of a halogen lamp that emits a light beam (non-exposure light) having a wavelength different from the wavelength of the exposure light. 15 is a lens,
The light flux (detection light) from the light source 14 is condensed and made incident on the beam splitter 16 for illumination. Reference numeral 12 is an objective lens.

The detection light from the lens 15 reflected by the beam splitter 16 is reflected by the mirror M ₁ and guided through the objective lens 12 to the AA mark 4 on the surface of the wafer 3 for illumination.

Reference numeral 19 is a light source for illuminating the reference mark 17
It consists of ED etc. Reference numeral 18 is a lens. Light source 19
The light flux from is condensed by the lens 18, guided to the reference mark 17, and illuminated. Reference numeral 20 denotes a beam splitter for the reference mark, which reflects the light beam from the reference mark 17 and makes it enter the erector lens 21 via the mirror M ₂ . The erector lens 21 forms an image of the reference mark 17 and the AA mark 4 on the surface of the wafer 3 on the image pickup surface of the CCD camera 13 (hereinafter also referred to as "CCD camera"). The detecting means 101 in this embodiment has each of the above elements.

In this embodiment, the non-exposure light (detection light) emitted from the light source 14 passes through the lens 15, the beam splitter 16, the mirror M ₁ and the objective lens 12 in this order, and then the wafer 3
Illuminate the upper AA mark 4. The observation image information of the AA mark 4 on the wafer 3 includes the objective lens 12, the mirror M ₁ , and the
The CCD camera 1 through the beam splitter 16, the beam splitter 20, the mirror M ₂ , and the erector lens 21.
Image on 3.

At this time, in this embodiment, the pixels of the image pickup means of the CCD camera 13 (hereinafter referred to as "the pixels of the CCD camera").
Say. The position information based on the detection signal from the CCD camera 13 is detected at two positions corresponding to ½ of the stage). Then, by determining the position of the alignment mark 4 based on the detected position information of the two marks, the measurement error due to the influence of the pixels of the CCD camera 13 is reduced.

2 and 3 show the CCD camera 13 at this time.
It is explanatory drawing which shows that the measurement error by the influence of the pixel of can be reduced.

FIG. 2 shows how a measurement linearity error is generated due to the influence of the pixels of the CCD camera 13.
In FIG. 2, the horizontal axis represents the measured value of the stage position and the vertical axis represents the measurement linearity error.

When the stage movement amount corresponding to ½ of the pixels of the CCD camera is ΔS, the stage position is S ₀
ΔC ₁ , the measurement linearity error at the position
When the measurement linearity error when the stage position is S ₀ + ΔS is ΔC ₂ , the measured values at different positions corresponding to 1/2 of the pixels of the CCD camera have different signs and the same absolute value. I understand.

Meanwhile, in response to the position S _0, S ₀ + ΔS stage, when the measurement value based on the detection signal of the CCD camera including the measurement linearity errors and _{C 1, C 2, C 1} = S 0 + ΔC 1 C ₂ = S ₀ + ΔS + ΔC ₂

When the stage position is S ₀ , the CCD
When the positional information C ₀ based on the detection signal of the camera is obtained by the following formula C ₀ = (C ₁ + C ₂ ) / 2−ΔS using C ₁ and C ₂ , the measurement linearity error can be canceled.

FIG. 3 shows the CCD camera 1 when the stage is moved by an amount corresponding to 1/2 of the pixels of the CCD camera.
3 shows a state in which the projected image of the AA mark 4 projected on 3 is moved by 1/2 of the pixel of the CCD camera 13.

On the other hand, the reference mark 17 is obtained by illuminating the light emitted from the light source 19 including the LED for illuminating the reference mark with the lens 18
The light is condensed and illuminated by the laser beam and is focused on the CCD camera 13 via the beam splitter 20 and the mirror M ₂ and the erector lens 21.

The position of the observed image of the AA mark 4 on the wafer 3 formed on the CCD camera 13 on the CCD camera 13 is measured by a signal processing device (not shown), and the CCD camera 13 is also measured by the signal processing device. Accurate position information of the XY stage 1 is obtained by comparing the position of the projected image of the reference mark 17 which is imaged on the upper side and is always fixed, and thereby highly accurate alignment is performed.

FIG. 4 is a schematic view of the essential parts of an optical system of Example 2 when the present invention is applied to an exposure apparatus for manufacturing semiconductor elements. 4, the same members as those shown in FIG. 1 are designated by the same reference numerals.

The present embodiment is different from the embodiment 1 of FIG. 1 in that the AA mark 4 on the wafer 3 is observed using the light passing through the projection lens 5, that is, the alignment is performed by the TTL method. Is different, and other configurations are almost the same.

In this embodiment, the non-exposure light emitted from the halogen lamp 14a is the lens 15, the beam splitter 16, the objective lens 12, the mirror M ₁ and the projection lens system 5 in this order.
After that, the AA mark 4 on the wafer 3 is illuminated.

Observation image information of the AA mark 4 on the wafer 3 is imaged on the CCD camera 13 through the projection lens 5, the mirror M ₁ , the objective lens 12, the beam splitter 16, the beam splitter 20, and the erector lens 21 in order.

On the other hand, the reference mark 17 is illuminated by condensing the light emitted from the LED light source 19 for illuminating the reference mark by the lens 18, and forms an image on the CCD camera 13 via the beam splitter 20 and the objective erector lens 21. .

The position of the observation image of the AA mark 4 on the wafer 3 formed on the CCD camera 13 on the CCD camera 13 is measured by a signal processing device (not shown), and the CCD camera 13 is also measured by the signal processing device. Accurate position information of the stage is obtained by comparing the position of the projected image of the reference mark 17 which is imaged on the upper side and is always fixed, and thereby highly accurate alignment is performed.

In the first and second embodiments, in order to apply the alignment simultaneously in the XY2 directions, the stage may be driven in the 45 ° direction with respect to the XY directions.

FIG. 5 is a schematic view of the essential parts of an optical system of Example 3 when the present invention is applied to an exposure apparatus for manufacturing semiconductor elements.

In the figure, numeral 8 denotes a reticle as a first object, which is placed on the reticle stage 10. 3 is the second
It is a wafer as an object, and alignment marks (AA marks) 4 are provided on the surface thereof. Reference numeral 5 denotes a projection optical system including a projection lens system and a reticle (mask).
The circuit patterns on the 8th surface are projected on the 3rd surface of the wafer. The projection lens system 5 is a telecentric system on both the reticle 8 side and the wafer 3 side.

An illumination system 9 illuminates the reticle 8 with exposure light. Reference numeral 2 denotes a θ, Z stage on which the wafer 3 is placed, and θ rotation and focus adjustment of the wafer 3, that is, Z
We are adjusting the direction. The θ, Z stage 2 is mounted on the XY stage 1 for performing the step operation with high accuracy. An optical square (bar mirror) 6 that serves as a reference for measuring the stage position is placed on the XY stage 1.
The optical square 6 is monitored by a laser interferometer 7.

The alignment between the reticle 8 and the wafer 3 in this embodiment is performed indirectly by aligning each with a reference mark 17, which will be described later, whose positional relationship is determined. Alternatively, the resist image pattern or the like is actually aligned and exposed, the error (offset) is measured, and offset processing is performed in consideration of the value thereafter.

Next, each element of the detecting means 101 for detecting the position of the mark 4 on the surface of the wafer 3 will be described.

An observation microscope 11 observes the AA mark 4 on the surface of the wafer 3 with non-exposure light. In this embodiment, an off-axis method is used in which alignment is performed without the projection lens 5.

Reference numeral 14 denotes a light source for detecting the AA mark 4, which is composed of a halogen lamp which emits a light flux (non-exposure light) having a wavelength different from the wavelength of the exposure light. 15 is a lens,
The light flux (detection light) from the light source 14 is condensed and made incident on the beam splitter 16 for illumination. Reference numeral 12 is an objective lens.

The detection light from the lens 15 reflected by the beam splitter 16 is reflected by the mirror M ₁ and guided through the objective lens 12 to the AA mark 4 on the surface of the wafer 3 for illumination.

Reference numeral 19 is a light source for illuminating the reference mark 17
It consists of ED etc. Reference numeral 18 is a lens. Light source 19
The light flux from is condensed by the lens 18, guided to the reference mark 17, and illuminated. Reference numeral 20 denotes a beam splitter for the reference mark, which reflects the light beam from the reference mark 17 and makes it enter the erector lens 21 via the mirror M ₂ .

Reference numeral 22a is a plane-parallel plate, and has AA mark 4
The image forming position on the image pickup means surface of the CCD camera 13 is slightly changed. Reference numeral 22b is a piezoelectric element, which changes the inclination of the plane-parallel plate 22a.

The erector lens 21 uses the reference mark 17 and the AA mark 4 on the surface of the wafer 3 for the CCD camera 13 respectively.
An image is formed on the image pickup surface (hereinafter, also referred to as "CCD camera"). The detecting means 101 in this embodiment has each of the above elements.

In this embodiment, the non-exposure light (detection light) emitted from the light source 14 passes through the lens 15, the beam splitter 16, the mirror M ₁ and the objective lens 12 in this order, and then the wafer 3
Illuminate the upper AA mark 4. The observation image information of the AA mark 4 on the wafer 3 includes the objective lens 12, the mirror M ₁ , and the
An image is formed on the CCD camera 13 through the beam splitter 16, the beam splitter 20, the mirror M ₂ , the erector lens 21, and the plane-parallel plate 22a.

In this embodiment, the plane parallel plate 22a for minutely changing the image forming position of the AA mark 4 and the piezoelectric element 22 for changing the inclination of the plane parallel plate 22a are used.
The position of the alignment mark 4 is determined based on two pieces of position information detected at positions that are different by ½ of the pixels of the CCD camera 13 by driving b. The measurement error due to the influence of is reduced.

Next, referring to FIGS. 2 and 6, the CCD at this time
It will be described that the measurement error due to the influence of the pixels of the camera 13 can be reduced.

FIG. 2 shows how a measurement linearity error occurs due to the influence of the pixels of the CCD camera. Figure 2
In the figure, the horizontal axis represents the measured value of the stage position, and the vertical axis represents the measurement linearity error.

When the stage movement amount corresponding to 1/2 of the pixels of the CCD camera is ΔS, the stage position is S ₀
ΔC ₁ , the measurement linearity error at the position
Assuming that the measurement linearity error when the stage position is S ₀ + ΔS is ΔC ₂ , the measurement linearity errors ΔC ₁ and ΔC ₂ at different positions corresponding to 1/2 of the pixels of the CCD camera have different signs and are absolute. You can see that the values are the same.

[0070] On the other hand, corresponds to the position S _0, S ₀ + ΔS stage, when the measurement value based on the detection signal of the CCD camera including the measurement linearity errors and _{C 1, C 2, C 1} = S 0 + ΔC 1 C ₂ = S ₀ + ΔS + ΔC ₂

The position of the stage is set to one of the pixels of the CCD camera.
/ 2 and the projected image of the AA mark formed on the CCD camera is
Since displacing by an amount equivalent to 2 is equivalent, when the position of the stage is S ₀ , the positional information C ₀ based on the detection signal of the CCD camera is used as C ₁ and C ₂ to obtain the following formula C ₀ = The measurement linearity error can be canceled by obtaining (C ₁ + C ₂ ) / 2−ΔS.

FIG. 6 shows the CCD camera 1 when the piezoelectric element 22b is driven to change the inclination of the plane-parallel plate 22a.
3 shows a state in which the image forming position of the AA mark 4 on 3 is changed.

On the other hand, the reference mark 17 is obtained by illuminating the light emitted from the light source 19 including the LED for illuminating the reference mark with the lens 18
The light is condensed and illuminated by a beam splitter 20, a mirror M _2, and an erector lens 21 and a plane-parallel plate 22.
An image is formed on the CCD camera 13 via a.

The position of the observed image of the AA mark 4 on the wafer 3 formed on the CCD camera 13 on the CCD camera 13 is measured by a signal processing device (not shown), and the CCD camera 13 is also measured by the signal processing device. Accurate position information of the XY stage 1 is obtained by comparing the position of the projected image of the reference mark 17 which is imaged on the upper side and is always fixed, and thereby highly accurate alignment is performed.

FIG. 7 and FIG. 8 are schematic views of the essential parts of a part of the fourth and fifth embodiments of the present invention.

Compared with the first embodiment shown in FIG. 1, the fourth embodiment shown in FIG. 7 is different from the first embodiment shown in FIG. 1 in that the plane parallel plate 22a is replaced by a wedge plate 22c, and the piezoelectric element 22b for changing the inclination of the plane parallel plate 22a is replaced by the wedge plate 22c. The motor 22d for rotating around the optical axis is used. Then, by rotating the motor 22d, C
It is the same as the first embodiment except that the image forming position of the AA mark 4 on the CD camera 13 is changed.

In FIG. 7, by rotating the motor 22d,
It shows a state in which the image forming position of the AA mark 4 on the CCD camera 13 is changed when the wedge plate 22c is rotated about the optical axis.

In the fifth embodiment of FIG. 8, the piezoelectric element 22e is attached to the holder of the CCD camera 13 and the CCD camera 13 itself is parallel to the image plane of the AA mark 4, as compared with the first embodiment of FIG. In other words, this is different from the first embodiment in that the image forming position of the AA mark 4 on the CCD camera 13 is relatively changed by displacing it in a plane orthogonal to the optical axis. Is the same. FIG. 8 shows the piezoelectric element 2.
It shows a state in which the position of the CCD camera 13 is displaced by driving 2e.

In the third to fifth embodiments, the operation of the driving member for changing the image forming position of the AA mark may be continuous vibration or rotation. At this time, it is preferable that the amount of change in the position of the alignment mark that is continuously changed is a continuous change corresponding to approximately one pixel of the CCD camera.

This is because the position information is integrated (stored in the CCD element) irrespective of the phase of the linearity error and the measurement error is reduced, as indicated by the diagonal lines in FIG.

The operation of each of the driving members in the third to fifth embodiments is to be a continuous operation. In the third embodiment, the plane-parallel plate 22a is vibrated by continuously driving the piezoelectric element 22b. 4, the wedge plate 22c is connected to the motor 22.
d may be rotated continuously, and in the fifth embodiment, the piezoelectric element 22e may be continuously driven to vibrate the CCD camera 13 itself.

FIG. 10 is a schematic view of the essential parts of an optical system of Example 6 when the present invention is applied to an exposure apparatus for manufacturing semiconductor elements. 10, the same members as those shown in FIG. 5 are designated by the same reference numerals.

The present embodiment is different from the third embodiment in FIG. 5 in that the AA mark 4 on the wafer 3 is observed by using the light passing through the projection lens 5, that is, the alignment is performed by the TTL method. Is different, and other configurations are almost the same.

In this embodiment, the non-exposure light emitted from the halogen lamp 14 illuminates the AA mark 4 on the wafer 3 through the lens 15, the beam splitter 16, the objective lens 12, the mirror M ₁ and the projection lens system 5 in this order.

The observation image information of the AA mark 4 on the wafer 3 is passed through the projection lens 5, the mirror M ₁ , the objective lens 12, the beam splitter 16, the beam splitter 20, the erector lens 21 and the plane parallel plate 22a in this order on the CCD camera 13. Image on.

On the other hand, the reference mark 17 is illuminated by condensing the light emitted from the LED light source 19 for illuminating the reference mark by the lens 18, passing through the beam splitter 20, the objective erector lens 21 and the plane parallel plate 22a, and the CCD camera 13. Image on top.

The position of the observed image of the AA mark 4 on the wafer 3 formed on the CCD camera 13 on the CCD camera 13 is measured by a signal processing device (not shown), and the CCD camera 13 is also measured by the signal processing device. Accurate position information of the stage is obtained by comparing the position of the projected image of the reference mark 17 which is imaged on the upper side and is always fixed, and thereby highly accurate alignment is performed.

Further, in order to apply simultaneously in the XY2 directions, in the case of a plane parallel plate, 45 ° with respect to the XY directions.
If the wedge plate is rotated, the operation in the XY directions appears every 90 °, so that it can be applied as it is. When the CCD camera itself is displaced, it can be driven in the 45 ° direction with respect to the XY direction. It can be easily realized.

[0089]

According to the present invention, by setting each element as described above, the detection mark (alignment light) having a wavelength different from that of the exposure light is used to align the alignment mark on the wafer surface on the imaging surface of the CCD camera. And an exposure apparatus having an improved mark detection function capable of detecting the position information of the mark image with high accuracy when the mark is formed, and a method of manufacturing a semiconductor chip using the same. can do.

Particularly, according to the present invention, the image projected by the observation microscope system for observing the alignment mark on the wafer is picked up by the CCD camera, photoelectrically converted, and the position of the alignment mark is detected by using this detection signal. In the alignment method, the position of the alignment mark is determined on the basis of a plurality of position information detected at a plurality of different positions within a range corresponding to one pixel of the CCD camera. By determining the position of the alignment mark based on two pieces of position information detected at positions different from each other by approximately ½ of the pixels of, the influence of the measurement error due to the influence of the pixels of the CCD camera is reduced, and the alignment is performed. The feature is that the accuracy is improved.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of measurement linearity error according to the present invention.

FIG. 3 is an explanatory view of a part of FIG.

FIG. 4 is a schematic view of the essential portions of Embodiment 2 of the present invention.

FIG. 5 is a schematic view of the essential portions of Embodiment 3 of the present invention.

FIG. 6 is an explanatory view of a part of FIG.

FIG. 7 is a schematic view of a main part of a part of a fourth embodiment of the present invention.

FIG. 8 is a schematic view of a main part of a part of a fifth embodiment of the present invention.

FIG. 9 is an explanatory diagram of measurement linearity error according to the present invention.

FIG. 10 is a schematic view of the essential portions of Embodiment 6 of the present invention.

[Explanation of symbols]

1 XY stage 2 θ stage 3 wafer 4 alignment mark (AA mark) on the wafer 5 projection lens 6 bar mirror 7 laser interferometer 8 for measuring the position of the XY stage 8 reticle 9 exposure illumination system 10 reticle stage 11 observation microscope 12 Objective lens 13 CCD camera 14 Halogen lamp light source for illumination 15 Lighting lens 16 Beam splitter for illumination 17 Reference mark 18 Lens for reference mark illumination 19 LED light source for reference mark illumination 20 Beam splitter for reference mark 21 Elector lens 22a Parallel plane plates 22b and 22e Piezoelectric element 22c Wedge plate 22d Motor

Claims (12)

[Claims] 1. A projection lens system for projecting a pattern of a first object onto a second object with exposure light, and a second object illuminated with detection light having a wavelength different from that of the exposure light, An image of the mark is formed on the surface of the image pickup means of the CCD camera, position information of the mark is detected at a plurality of different positions within a range corresponding to one pixel of the image pickup means, and based on the detection result of the position information of the mark. And an detecting device for performing relative alignment between the first object and the second object. 2. A projection lens system for projecting a pattern of a first object onto a second object with exposure light, and a second object illuminated with detection light having a wavelength different from that of the exposure light. An image of the mark is formed on the surface of the image pickup means of the CCD camera, position information of the mark is detected at different positions corresponding to approximately 1/2 of the pixels of the image pickup means, and based on the detection result of the position information of the mark. An exposure apparatus comprising: a detection unit that performs relative alignment between the first object and the second object. 3. A detection means detects a position alignment mark on the wafer using detection light that does not expose the wafer, and the position of the wafer is aligned based on the position information of the mark image obtained based on the detection. When a semiconductor chip is manufactured by projecting and transferring an image of the circuit pattern onto the wafer through a projection lens system by illuminating the circuit pattern of the mask with exposure light that exposes the wafer, the detecting means is the wafer. The mark on the surface is imaged on the surface of the image pickup means of the CCD camera, the position information of the mark is detected at a plurality of different positions within a range corresponding to one pixel of the image pickup means, and the position information of the mark is detected. A method of manufacturing a semiconductor chip, characterized in that the mask and the wafer are aligned relative to each other based on the result. 4. A detecting mark is used to detect an alignment mark on the wafer using detection light that does not expose the wafer, and the wafer is aligned based on the position information of the mark image obtained based on the detection. When a semiconductor chip is manufactured by projecting and transferring an image of the circuit pattern onto the wafer through a projection lens system by illuminating the circuit pattern of the mask with exposure light that exposes the wafer, the detecting means is the wafer. The mark on the surface is imaged on the surface of the image pickup means of the CCD camera, the position information of the mark is detected at different positions corresponding to about 1/2 of the pixels of the image pickup means, and the detection result of the position information of the mark is detected. A method of manufacturing a semiconductor chip, wherein the relative alignment between the mask and the wafer is performed based on the above. 5. A projection lens system for projecting a pattern of a first object onto a second object with exposure light, and a second object illuminated with detection light having a wavelength different from that of the exposure light. When the mark is imaged on the image pickup means surface of the CCD camera, a movable optical member provided in the optical path is finely displaced to form an image at a plurality of positions on the image pickup means surface, and at the plurality of positions. An exposure apparatus comprising: a detection unit that performs relative alignment between the first object and the second object based on a detection result of mark position information. 6. The exposure apparatus according to claim 5, wherein the optical member is composed of a plane parallel plate that is tiltable with respect to the optical axis. 7. The exposure apparatus according to claim 5, wherein the optical member is composed of a wedge member rotatable about an optical axis. 8. A projection lens system for projecting a pattern of a first object onto a second object with exposure light, and a detection light having a wavelength different from that of the exposure light to illuminate the second object, When an image of the mark is formed on the surface of the image pickup means of the CCD camera, the surface of the image pickup means is slightly displaced in a plane orthogonal to the optical axis to form an image at a plurality of positions on the surface of the image pickup means. An exposure apparatus comprising: a detection unit that performs relative alignment between the first object and the second object based on a detection result of position information of the mark at the position. 9. The exposure apparatus according to claim 8, wherein the plurality of positions on the surface of the image pickup unit are two different positions, which are approximately ½ of the pixels of the image pickup unit. 10. A detection means detects the alignment mark on the wafer by using detection light that does not expose the wafer,
The position of the wafer is aligned based on the position information of the mark image obtained based on the detection, and the circuit pattern of the mask is illuminated with the exposure light that exposes the wafer to form an image of the circuit pattern through the projection lens system. When a semiconductor chip is manufactured by projecting and transferring it onto a wafer, the detecting means slightly displaces a movable optical member provided with a mark on the wafer in the optical path, and a plurality of detecting means on the surface of the image pickup means of the CCD camera. A method of manufacturing a semiconductor chip, comprising forming an image at a position, and performing relative alignment between the mask and the wafer based on a detection result of position information of the mark at the plurality of positions. 11. The method of manufacturing a semiconductor chip according to claim 10, wherein the plurality of positions on the surface of the image pickup means are different positions by an amount corresponding to approximately ½ of pixels of the image pickup means. 12. A detection means detects the alignment mark on the wafer using detection light that does not expose the wafer,
The position of the wafer is aligned based on the position information of the mark image obtained based on the detection, and the circuit pattern of the mask is illuminated with the exposure light that exposes the wafer to form an image of the circuit pattern through the projection lens system. When a semiconductor chip is manufactured by projecting and transferring it on a wafer, the detection means forms marks on the wafer surface at a plurality of positions on the image pickup means surface that are displaceable in a plane orthogonal to the optical axis, A method of manufacturing a semiconductor chip, characterized in that the mask and the wafer are relatively aligned based on the detection result of the mark position information.