JP3004303B2 - Exposure method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure method and an exposure apparatus, and more particularly, to an exposure method and an exposure method capable of accurately detecting an alignment mark formed on a substrate to be processed. Regarding the device.

[Prior Art] A projection exposure apparatus that exposes an original pattern onto a wafer includes:
In order to improve the resolving power of exposure, a single-wavelength light and a single-wavelength light dedicated projection lens therefor are used.

Therefore, even when detecting the alignment mark, it is illuminated with single-wavelength light and detected.

Further, since the reduction projection lens dedicated to a single wavelength used in this projection exposure apparatus is precisely manufactured, it is difficult to correct chromatic aberration.

With reference to FIG. 8, the state of illumination and detection of an alignment mark using single-wavelength light in the prior art will be described.

As shown in FIG. 8A, a single-wavelength illumination light 102 is irradiated from above the reticle 1, and the alignment mark 25 on the wafer 5 is illuminated through the reduction projection lens 4. The reflected light from here is reflected by the half mirror 106 and detected by the detector 107.

FIG. 8B is an enlarged view of the image detected by the detector 107, and the alignment mark 25 is visible in the window 108 on the mask.

The alignment mark 25 and the mark drawn on the reticle 1 are matched to match the mask pattern with the wafer pattern.

On the other hand, usually, a resist 109 is provided on the alignment mark because it is necessary for pattern formation.

Therefore, the sectional view near the alignment mark is shown in FIG.
As shown in the drawing, the mark part 110 and the resist part 111 can be considered separately.

Therefore, in this case, the single-wavelength light illuminated from above the reticle 1 causes interference in the resist portion, but if the resist thickness is uniform, the intensity of the interference light is constant.

However, in reality, the resist has unevenness due to the unevenness of the alignment mark and the unevenness of the resist thickness. For this reason, the intensity of the interference light is not constant, and there has been a problem that the detection accuracy of the alignment mark is reduced.

In order to solve this problem, in the technique described in Japanese Patent Application Laid-Open No. 60-80223, a bright line (particularly high-brightness light) contained in a mercury lamp, for example, an h-line (wavelength of 405 nm) is used as illumination light. ), G-line (436 nm wavelength), e-line (546 nm wavelength)
m) and d-line (wavelength 577 nm), light of two or more wavelengths is selected, illuminated, and the intensity signal of the detected light is combined to reduce the influence of the resist unevenness.

As an example, FIG. 10 shows a detection signal in the case of illuminating with the e-line and the d-line, and a signal obtained by combining the detection signals.

In the figure, the target low-intensity portions with respect to the center line in the diagram showing the synthesized signal indicate both end portions 112 of the alignment mark 25. The reason why the intensity is low is that when light enters from above, the light is scattered at the end portion and the amount of light returning to the top decreases.

That is, by combining the two signals, both end portions 112 of the alignment mark 25 are detected symmetrically, and it is understood that the influence of the unevenness of the resist is reduced.

Next, illuminate by changing the apparent wavelength,
A method of synthesizing the detection signals is described in Japanese Patent Application Laid-Open No. Sho 60-36312.

In this technique, as shown in FIG. 11, a laser 113 having high linearity is used as illumination light, and a reflecting mirror 1 in the middle of the optical path is used.
This is a technique of swinging the illumination light around the alignment mark 25 by swinging the 14. That is, as shown in FIG. 12, the fact that the optical path length changes in the resist 109 is used.

As a result, the influence of the unevenness of the resist is reduced, and the alignment mark can be detected accurately.

Further, the technique described in Japanese Patent Application Laid-Open No. 01-86518 discloses that, as illumination light, four laser beams having wavelengths different from each other by 27 nm are used, so that interference in the resist can be reduced. Is detected. In particular, lasers with wavelengths of 458, 488, 515, and 543 nm are recommended.

[Problems to be Solved by the Invention] Among the above prior arts, the one having the highest alignment mark detection accuracy is a so-called four-wavelength laser illumination method described in JP-A-01-86518, or JP
This is considered to be a so-called laser swing illumination method described in Japanese Patent Application Laid-Open No. 60-136312.

However, in the four-wavelength laser illumination method, since four types of laser oscillators are required, there is a problem that the projection exposure apparatus becomes expensive.

In addition, the laser swing illumination method has a problem that since there is a movable portion for swinging the laser, the optical axis is likely to change, and the accuracy of detecting the alignment mark is reduced.

A first object of the present invention is to provide an exposure method capable of detecting an alignment mark with high accuracy.

A second object of the present invention is to provide a small, inexpensive, and
An object of the present invention is to provide an exposure apparatus that can accurately detect an alignment mark.

[Means for Solving the Problems] To achieve the first object, according to a first aspect of the present invention, there is provided an exposure apparatus for exposing an original pattern onto a substrate to be processed, comprising: Are respectively separated into S-polarized light and P-polarized light, and the separated S-polarized light and the P-polarized light are irradiated onto the alignment mark formed on the substrate to be processed at different angles from each other, Detecting the diffracted light diffracted by the alignment mark by irradiation at a position optically conjugate with the substrate to be processed, corresponding to the irradiated light of the plurality of wavelengths, and detecting the detected light of the plurality of wavelengths; The relative position between the original pattern and the substrate to be processed is adjusted based on the position of the alignment mark obtained based on the position of the alignment mark obtained based on the diffracted light corresponding to the original image pattern. Relative position Exposing the substrate to be processed, the position of which is adjusted, to provide an exposure method.

In order to achieve the second object, a second aspect of the present invention is provided.
According to the aspect of the present invention, there is provided an exposure apparatus for exposing an original image pattern on a substrate to be processed, and illuminating means for illuminating a plurality of lights having different wavelengths on an alignment mark formed in advance on the substrate to be processed. A detection unit that is disposed at a position optically conjugate with the substrate to be processed and detects the diffracted light irradiated by the irradiation unit and diffracted by the alignment mark in correspondence with the plurality of illuminated lights; Position detecting means for detecting the position of the alignment mark based on diffracted light corresponding to the light of the plurality of wavelengths detected by the detecting means, wherein the irradiating means comprises a plurality of lights having different wavelengths. Respectively, and irradiates the substrate to be processed with the S-polarized light and the P-polarized light separated by the polarized light separating unit at different angles from each other. An exposure apparatus is provided.

[Operation] In the exposure apparatus configured as described above, the irradiating unit irradiates a plurality of lights having different wavelengths onto an alignment mark formed in advance on the substrate to be processed. For example, two or more lights having different wavelengths are separated into identifiable first light and second light for each light of each wavelength, and are irradiated on the alignment mark. The irradiated light is diffracted at the alignment mark. The detecting means detects the diffracted light diffracted by the alignment mark in correspondence with the plurality of irradiated lights. Thereafter, the position detecting means detects the position of the alignment mark based on the diffracted light corresponding to the light of the plurality of wavelengths detected by the detecting means.

As described above, by detecting a plurality of diffracted lights, the influence of interference is reduced, and the position of the alignment mark can be accurately detected.

If two laser beams having different wavelengths are used as the illumination light, four identifiable lights can be obtained with the two laser beams. As in the case of using light, the position of the alignment mark can be accurately detected.

Further, unlike the laser swing illumination method, there is no movable part for swinging the laser, so that the accuracy of the alignment mark detection does not decrease.

Furthermore, compared to the case where light of two wavelengths is simply incident vertically, the fluctuation of the detection accuracy due to the unevenness of the resist and the interference due to the unevenness of the resist caused by the pattern step is significantly reduced. Therefore, the asymmetry of the detected waveform due to the unevenness of the resist application and the unevenness of the pattern of the alignment mark is significantly reduced, the accuracy of the alignment mark detection is remarkably improved, and the desired pattern can be obtained.

In addition, in a pattern detection system in which it is difficult to configure a detection system using continuous spectral components or light having a large number of spectra, the influence of the transparent coating of the test object covering the pattern, and the pattern steps Therefore, it is effective in accurately detecting the position of the pattern and the two-dimensional (planar) shape.

Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIGS. 13 and 14.

FIG. 1A is an exploded view of an alignment mark detection device used in the exposure apparatus according to the present embodiment, and FIG. 1B is an enlarged view of a case where the alignment mark on the wafer is irradiated with laser light. FIG. 2 is an explanatory diagram for explaining an optical path in this embodiment, FIG. 3 is an explanatory diagram showing a detected image, FIGS. 4 and 5 are explanatory diagrams showing the principle of the present embodiment, 6th, 7th
FIGS. 13 and 14 are explanatory diagrams showing the effects of the embodiment, and FIGS. 13 and 14 are tables obtained by substituting numerical values into the analytical expressions of the first embodiment.

As shown in FIG. 1, the configuration of this embodiment is roughly divided into
A laser emitting device 200 that emits a laser for irradiating the alignment mark, and a positioning optical device 201 that forms an image of the diffracted light from the alignment mark and outputs a positioning detection signal.
, A reticle 1, a reduction projection lens 4, and a wafer 5.

The configuration of each device will be described according to the direction in which the laser beam travels.

 First, the configuration of the laser emitting device 200 will be described.

The laser emitting apparatus 200 includes a laser light source 11 for emitting a laser beam of wavelength lambda _1, and a laser light source 12 for emitting a laser beam having a wavelength lambda _2, the optical path in front of the laser light source 11, the two A dichroic mirror 13 for aligning two laser lights emitted from the laser light sources 11 and 12 on one optical path is arranged. On the optical path in front of the laser light source 12, a laser beam having a wavelength lambda _2, to place the reflecting mirror 39 for causing incident on the dichroic mirror 13.

A quarter-wave plate 14 is arranged in front of the dichroic mirror 13, and a birefringent prism 15 is arranged in front of the quarter-wave plate 14. In front of the birefringent prism 15, a lens 16 for refracting an S-polarized laser beam, which is one of the laser beams polarized by the birefringent plasma 15, by a small angle θ and traveling straight away from the optical axis, is provided. Behind it is a reflector for guiding the laser light to the alignment optics behind it
Place 19

Next, the configuration of the positioning optical device 201 will be described in the same manner as described above, according to the traveling direction of the laser beam.

A half prism 20 for refracting the laser light from the laser emitting device 200 is arranged in front of the reflecting mirror 19. A lens 21 is disposed in front of the half prism 20. Further, in front of the lens 21, a reflecting mirror 22 for causing the laser light to enter the reduction projection lens 4 is arranged.

Next, since the laser beam incident on the alignment mark on the wafer 5 is diffracted at the alignment mark on the wafer 5, the configuration of the alignment optical device 201 will be described according to the traveling direction of the diffracted light. .

In front of the half prism 20, to arrange the dichroic mirror 30 for reflecting a laser beam having a wavelength lambda _2. The Above the dichroic mirror 30, a reflecting mirror 41 is disposed in its forward, placing the photoelectric device 33 for detecting the by the laser beam wavelength lambda _2, a real image 31 of the alignment mark.

In front of the dichroic mirror 30, disposing the photoelectric element 32 to detect the by the laser beam wavelength lambda _2, a real image 29 of the alignment mark.

Further, a signal adder 34 for adding the electric signals from the two photoelectric elements 32 and 33 to obtain one detection signal 35 is provided.

Note that the three elements of the half prism 20, the lens 21, and the reflecting mirror 22 are the laser emitting device 200 and the positioning optical device 201.
And are common elements.

On the lower surface of the reticle 1, a circuit pattern is drawn in a portion surrounded by a broken line 2, and reticle position detecting devices 7a and 7b are provided above the reticle alignment marks 3a and 3b, respectively. .

Below the reticle 1, a reduction projection lens 4 for reducing the reticle pattern and forming an image on the wafer 5 is arranged.

Further, below the reduction projection lens 4, a wafer 5 placed on a stage (not shown) is arranged.

Next, the operation of this embodiment will be briefly described with reference to FIG.

First, the position of the wafer 5 is detected by detecting a wafer alignment mark, which will be described later. Next, the reticle 1 is slightly moved, and the reticle position is controlled by the reticle alignment marks 3a and 3b drawn on the reticle 1 and the reticle position detection systems 7a and 7b, and the reticle 1 is moved to a target position. Fit together. As a result, the pattern drawn on the reticle 1 overlaps the wafer 5 with the desired positional accuracy. Next, an exposure illumination system (not shown) above the reticle 1 irradiates the reticle 1 with exposure illumination light. As a result, the circuit pattern drawn on the lower surface of the reticle 1 is
The image is reduced by the reduction projection lens 4 and printed on the chip 6 on the wafer 5, and the overlap exposure is completed.

Next, the operation of the wafer alignment mark detecting device according to the present embodiment will be described with reference to FIG.

From the light sources 11 and 12, the wavelengths λ ₁ and λ
₂ laser light is emitted, and both are dichroic mirrors
By 13 it is combined on one optical path. Since the laser light is linearly polarized light, it becomes circularly polarized light via the quarter-wave plate 14 and reaches the birefringent prism 15.

Therefore, the laser beams having the wavelengths λ ₁ and λ ₂ pass through the birefringent prism 15 so that
The light is branched into a P-polarized laser 17 and an S-polarized laser 18.

Thereafter, the P-polarized laser 17 goes straight on the optical axis,
The polarized laser beam 18 is refracted by a small angle θ by passing through the lens 16, and goes straight away from the optical axis.

Then, by focusing on the P-polarized laser 17 with a wavelength lambda _1, further
Continue explanation.

The P-polarized laser 17 is reflected by a reflecting mirror 19, passes through a half prism 20 (a semi-transparent prism is referred to as a half prism), a lens 21, and a reflecting mirror 22, and becomes a light ray 23.
Reach

On the other hand, the S-polarized laser 18 does not pass on the optical axis, but follows almost the same path as described above to become a light ray 24 and reaches the reduction lens 4.

The rays 23 and 24 illuminate the alignment marks 25 on the wafer, as shown in FIG.

The alignment mark is formed in a concave or convex pattern of 2 to 3 μm square, and when irradiated with laser light, diffracted light such as 26 and 27 indicated by broken lines in FIG. This diffracted light passes through the reduction lens 4 and the reflecting mirror 22 in the direction opposite to the outward path, and forms an image once as an image 28. This image 28 is further enlarged by the lens 21 and the half prism 20, the reflecting mirror 41
After that, the real image 29 is obtained.

That is, the position of the alignment mark 25 and the position of the real image 29 are in a conjugate relationship, and the real image 29 illuminated by the light rays 23 and 24 forms an image at the same position.

However, since the reduction lens 4 present chromatic aberration, the laser light of the wavelength lambda ₁ and lambda _2, a position for imaging are different.

Therefore, a dichroic mirror 30 is provided in the middle, and the light of wavelength λ ₂ is reflected to form an image as a real image 31.

Then, the two real images 29 and 31 are separate photoelectric elements 3
After detection by 2 and 33, conversion into an electric signal, and addition by a signal adder 34, one detection signal 35 from which the influence of interference in the resist has been removed can be obtained.

The detection signal 35 is compared with a signal of a reference mark (not shown) of the stage stored in advance, and the position of the alignment mark 25 on the wafer is matched with the position of the reference mark on the stage. The wafer alignment ends.

Next, the optical path of the laser beam having the wavelength lambda ₁ or lambda ₂ with reference to FIG. 2, will be described.

FIG. 2A shows an optical path of the P-polarized laser light 17, and FIG. 2B shows an optical path of the S-polarized laser light 18.

As shown in FIG. 2A, the parallel laser light incident on the quarter-wave plate 14 is split into a P-polarized laser light 17 and an S-polarized laser light 18 by passing through a birefringent prism 15. You.

The P-polarized laser light 17 travels straight, passes through the lens 16 and the lens 21, and is condensed on the entrance pupil 40 of the reduction lens 4.

 Thereafter, the wafer 5 is irradiated at an incident angle of zero degree.

On the other hand, the S-polarized laser 18 passes through the lens 16, refracts by a small angle θ, travels, further refracts by the lens 21, passes through the position of the image 28, condenses on the entrance pupil 41, It becomes light and irradiates the wafer 5 obliquely at a predetermined incident angle.

The alignment mark 25 and the position of the image 28 have a conjugate relationship, and the laser beam passes through the position of the image 28, so that the alignment mark 25 on the wafer 5 can be illuminated.

In this case, two laser lights that illuminate the wafer 5 are:
Since one laser beam is branched, in general,
Interference occurs on the wafer 5 and intense illumination unevenness occurs.

In order to avoid this development, the present embodiment utilizes the property of the birefringent prism 15 to split circularly polarized light into S-polarized light and P-polarized light.

That is, in FIG. 2A, the P-polarized laser is irradiated on the wafer 5, and in FIG. 2B, the S-polarized laser is irradiated on the wafer 5. The reason for this is that the P-polarized laser and the S-polarized laser have different vibration planes and do not interfere with each other even if they are illuminated simultaneously.

Therefore, one laser beam can be branched and used as apparently two laser beams.

Next, the principle of the alignment mark detection method of this embodiment and the theoretical background will be described with reference to FIG.

According to the description of JP-A-01-86518, the illumination light is
It has been shown that it is desirable to illuminate each other with four different laser beams of about 27 nm wavelength.

According to this prior art, as incident light in FIG. 1 (B), wavelengths λ ₁ , λ ₁ ′, λ ₂ ,
What is necessary is to combine and detect the diffracted lights of each wavelength using the laser of λ ₂ ′, but the apparatus becomes expensive because four laser light sources are required.

Therefore, a laser having a wavelength of λ ₁ , λ ₂ is used as the vertical incident light 23 for the alignment mark, the diffracted light 26 is detected, and the inclined incident light 24 has a wavelength of λ ₁ , λ ₂ . Using a laser, the diffracted light 27 is detected.

Due to the inclined incident light 24, apparently λ ₁ ′, λ
₂ ′ wavelength light is irradiated as vertically incident light 23 and diffracted light
The same effect as that obtained by detecting 26 can be obtained.

The above is the principle of the alignment mark detection method of the present embodiment.

The above principle will be described focusing on the influence of the step of the alignment mark and the resist thickness.

First, the above-described principle will be described focusing on the influence of a pattern step.

FIG. 4 shows a cross section of a resist 25 applied on the alignment mark 25 of FIG. 1 (A).

The light ray 53 is diffracted on the upper surface of the alignment mark, and the light ray 54 is diffracted on the lower surface of the alignment mark. The phase difference [delta] ₁ of both beams is expressed by the following equation.

However, Here, h is the step of the pattern, p is the pitch of the pattern, n ₂
Is the refractive index of the resist.

When θ = 0, assuming that the phase difference at the time of illumination at wavelengths λ ₁ and λ ₁ ′ is δ ₁₀ and δ ₁₀ ′, the following equation is obtained.

However, On the other hand, the wavelength λ ₁ , the incident angle θ ₂₁ , and the phase difference when illuminated are δ
_{If it is 11} , it becomes the following formula.

However, Where δ ₁₁ = δ ₁₀ ′ Using the equations (5) to (8), θ ₁₁ , θ ₂₁ , θ ₂₁ ′, and θ ₁₁ ′ when illuminated at the wavelength λ ₁ can be obtained.

That is, at the incident angle of θ ₁₁ from above the resist, the wavelength λ
Irradiating the light of ₁ and detecting the diffracted light at the diffraction angle θ ₁₁ ′,
It can be seen that the same effect as when the light of wavelength λ ₁ ′ is irradiated vertically and the diffracted light at that time is detected is obtained.

Similarly, it is possible to determine the values when illuminated with wavelength lambda _2.

λ ₁ = 0.488 μm, λ ₂ = 0.543 μm, p = 5 μm, n ₁
FIG. 13 shows the result obtained by calculating the above values from the above equation when = 1 and n ₂ = 1.64.

Note that an Ar laser is used as a laser having a wavelength of 0.448 μm, and a He—Ne laser is used as a laser having a wavelength of 0.543 μm.

As shown in FIG. 13, the laser beams of the _two wavelengths λ ₁ and λ ₂ are vertically and tilted by 27.51 degrees to irradiate the alignment mark, and the diffracted lights 26 and 27 shown in FIG. , It can be seen that the same effect as when illuminated with four laser beams having wavelengths of 0.488, 0.515, 0.543, and 0.570 μm can be obtained.

Next, the effect of the resist thickness will be described with reference to FIG.

FIG. 5 shows a state in which a resist 52 is applied on the alignment mark 25.

When the ray 55 enters at an angle θ ₁ , it reaches point A, producing a diffracted light 56. On the other hand, the zero-order diffracted light (specular reflection light) at point A
Illuminates C from A through B, producing diffracted light 57, so that rays 56 and 57 interfere.

Both the phase difference epsilon ₁ is expressed by the following equation.

However, Here, d is the resist thickness, and n ₂ is the refractive index of the resist.

In the case of θ ₁ = 0, assuming that the phase differences when illuminated at wavelengths λ ₁ and λ ₁ ′ are ε ₁₀ and ε ₁₀ ′, these are expressed by the following equations.

On the other hand, the wavelength lambda _1, the phase difference when illuminated with an incident angle theta _21, when the epsilon ₁₁ by the following equation.

However, Here, if ε ₁₀ = ε ₁₀ ′, Using equations (13) to (16), θ when illuminated at wavelength λ _1
11 , θ ₂₁ , θ ₂₁ ′, and θ ₁₁ ′ can be obtained.

Similarly, it is possible to determine the values when illuminated with wavelength lambda _2.

λ ₁ = 0.488 μm, λ ₂ = 0.543 μm, p = 5 μm, n ₁
FIG. 14 shows the results obtained from the above equation when the above values were set to = 1 and n ₂ = 1.64.

As shown in FIG. 14, the laser having the above wavelength is irradiated vertically and inclined by 24.81 degrees to the registration mark with resist, and the diffracted lights 26 and 27 shown in FIG. It can be seen that the same effect as when illuminated with laser beams of 0.515, 0.543 and 0.570 μm can be obtained.

Summarizing the above, it can be understood that four laser light sources need not be used if laser beams having wavelengths of 0.488 μm and 0.543 μm are vertically and inclined by about 26 ° to irradiate the alignment mark.

The laser having a wavelength of 0.488 μm can be easily obtained by an Ar laser, and the laser having a wavelength of 0.543 μm can be easily obtained by a He—Ne laser.

Next, FIG. 3 shows a display state of a detection signal when an alignment mark is detected using the detection device of this embodiment.

FIG. 3A shows the detection signal 35 in FIG.
FIG. 1 (B) is a display on the monitor 50.
Alignment mark 25 at appears as bright signal 51.

FIG. 3B shows a signal of a scanning line. The horizontal axis represents the x coordinate, and the vertical axis represents the voltage V. Seeking the center of this signal, the position x ₀ of the alignment mark on the wafer.

The position x ₀ of the alignment mark of the wafer, as compared to the position of the reference mark of the stage that is previously stored (not shown), by matching the positions of the two marks, the wafer alignment ends I do.

Next, referring to FIG. 6, a pattern step h of an alignment mark on the wear when the laser light is irradiated,
5 shows a relationship with the interference intensity of the diffracted lights 53 and 54 shown in FIG.

FIG. 6 (A) shows the wavelength 0.488 in FIG. 1 (B).
A case is shown in which a laser beam of μm is incident as incident light 23 and only the diffracted light 26 is detected.

The horizontal axis 60 is the value of the pattern step of the alignment mark on the wafer, and the vertical axis 61 is the diffraction light detection value.

As shown in the figure, the detected value 61 of the diffracted light is greatly affected by the value 60 of the pattern step, and fluctuates between 0.0 and 1.0. Since the diffraction light detection value 61 of 0.0 means that the pattern diffraction light signal becomes 0, it becomes impossible to detect the alignment mark on the wafer.

On the other hand, FIG. 6 (B) shows a case where a two-wavelength laser is irradiated and two diffracted lights 26 and 27 are detected.

It can be seen from the figure that, according to the present embodiment, even if the pattern step changes, the fluctuation of the diffracted light detection value 61 is small, and the alignment mark on the wafer can be detected.

The above is a case where the pattern step h is changed.
The same applies to the case where the resist thickness d is changed.

FIG. 7 shows a diffraction light detection signal when a pattern having uneven resist coating is detected.

The horizontal axis corresponds to the direction of the arrow x shown in FIG.
The vertical axis is the detected signal voltage.

FIGS. 7A and 7B show detection signals of two diffracted lights when illuminated with a laser beam having a wavelength of 0.488 μm,
(C) and (D) show detection signals of two diffracted lights when illuminated with a laser beam having a wavelength of 0.543 μm, and (E) shows an average value of (A) to (D). .

From these figures, it can be seen that each detection signal is asymmetric, but the averaged one is symmetric,
It can be seen that the effect of this embodiment is exhibited.

In the above embodiment, the birefringent prism 15 is used as a means for tilting the irradiation light in FIG. 1A, but a galvanic mirror may be provided instead of the birefringent prism.

In this case, first, the alignment mark is illuminated and detected by a light beam traveling on the optical axis, and the detected image is recorded in the memory. Next, tilt the Galva mirror, and from diagonally,
The image is detected by irradiating a laser beam, detecting the diffracted light, recording the detected image in a memory, and superimposing the image on the image previously recorded in the memory.

Further, an AO diverter, an EO diverter, or a thin film device may be used as a means for tilting the irradiation light.

In the above description, the method of detecting the diffracted light from the alignment mark has been described.However, a birefringent prism is used as a means for inclining the irradiation light, and the regular reflection light from the alignment mark is detected, and the alignment mark is detected. An image may be obtained, and the position of the alignment mark may be obtained.

In the above, one detection mark detection optical system has been described. However, in actual use, an optical system for detecting another registration mark 36 (see FIG. 1) arranged in a direction perpendicular to this position. A system is required. This can be realized by simply providing the optical system described so far in a right angle direction.

Next, as a second embodiment, FIG. 16 shows a positioning device and a projection exposure device using the positioning mark detection device according to the first embodiment.

In the figure, an exposure axis 72 is provided below a light source 73 for exposure illumination.
The reticle 1 on which the original image pattern is drawn and the reduction lens 4 are arranged, and below the reduction projection lens 4, an XY stage on which a rotary stage 70 is mounted is arranged. The wafer 5 is placed on the rotating stage 70.

Further, for detecting the alignment mark, the laser emitting device and the alignment optical device are arranged in the same configuration as in the first embodiment.

 The operation of the present embodiment will be described below.

The predetermined position of the reticle 1 is adjusted to the exposure shaft 72 by the reticle position detection systems 7a and 7b. Next, rotate stage 70 and XY
The reference mark on the stage 71 is aligned with a predetermined position, and this position is stored in the alignment correction device. Then, Example 1
The alignment mark on the wafer 5 is detected by the method described in (1), and this detection signal is sent to the alignment correction device. This detection signal is stored in advance in the rotary stage 70 and the XY stage.
The two stages are finely moved by a driving device (not shown) so as to match the detection signal of the position of the reference mark 71 with the reference signal.

Then, the circuit pattern drawn on the reticle 1 is reduced by the reduction projection lens 4 by being illuminated with exposure illumination light, and is printed on a predetermined position of a chip on the wafer 5.

As a result, a detection deviation of about 0.1 to 0.3 μm may occur in the conventional method, but by using the apparatus according to the present embodiment, the detection deviation is suppressed to about 0.03 μm.

Next, as a third embodiment, a semiconductor manufacturing plant using the second embodiment is shown in FIG.

As shown in the figure, in the semiconductor manufacturing plant of the present embodiment, all the steps are started with circuit design and completed with sealing work.

The feature of this embodiment is that the resist applied on the wafer is
In the device that exposes the pattern drawn on the reticle,
As the other device, a conventionally used device is used.

In general, a semiconductor is manufactured by repeating the above-described exposure process many times.In this case, in this embodiment, a reduced image of a pattern of an enlarged size drawn on a reticle is projected and imaged on a wafer, Expose.

In this reduced projection exposure step, the alignment mark detection position described in the first embodiment is used.

By using the alignment mark detection device,
Unlike the conventional case, four laser light sources are not required, and only two laser light sources are required. The structure is simplified, and the size of the semiconductor manufacturing plant can be reduced.

[Effects of the Invention] According to the exposure method of the present invention, an alignment mark can be detected with high accuracy. Further, according to the exposure apparatus of the present invention, if one illumination light is incident, it is separated as two identifiable illumination lights, so that the number of light sources is half the number of light sources of the conventional alignment mark detection device. The structure can be simplified, miniaturization and cost reduction can be achieved.

[Brief description of the drawings]

FIG. 1 is an enlarged perspective view of a main part showing a first embodiment of the present invention, FIG. 2 is an explanatory diagram for explaining an optical path in the first embodiment, and FIG. 3 shows a detected image. Illustration, 4th,
FIG. 5 is an explanatory view showing the principle of the first embodiment, FIGS. 6 and 7 are explanatory views showing the effect of the first embodiment, FIGS. 8 to 12 are views for explaining the prior art, and FIGS. FIG. 15 is a table showing the results obtained by substituting numerical values into the analytical expressions of the first embodiment, FIG. 15 is a process diagram showing the third embodiment, and FIG. 16 is a perspective view showing the second embodiment. 1 reticle, 2 area showing circuit pattern, 3a, 3
b ... reticle alignment mark, 4 ... reduction projection lens, 5 ... wafer, 12,12 ... laser light source, 13,30 ... dichroic mirror, 14 ... quarter wave plate, 15 ... multiple Refractive prism, 17: P-polarized laser light, 18: S-polarized laser light, 20: Half prism, 23: Normally incident light, 24
…… inclined incident light, 25 …… Wafer alignment mark, 26,27,53,54,56,57 …… Diffraction light, 29,31 …… Real image, 3
2,33 ... photoelectric element, 50 ... TV monitor, 60 ... pattern step of alignment mark on wafer, 61 ... detected value of diffracted light, 200 ... laser emission device, 201 ... optical device for positioning, 102: Single-wavelength illumination light, 106: Half mirror, 109
... resist, 110 ... mark part, 111 ... resist part

Claims (4)

(57) [Claims] 1. An exposure apparatus for exposing an original pattern onto a substrate to be processed, comprising: an irradiating means for irradiating a plurality of lights having different wavelengths onto an alignment mark previously formed on the substrate to be processed; A detecting unit that is disposed at a position optically conjugate with the substrate to be processed, and detects diffracted light irradiated by the irradiation unit and diffracted by the alignment mark in correspondence with the light of the plurality of irradiated wavelengths; Position detecting means for detecting the position of the alignment mark based on diffracted light corresponding to the light of the plurality of wavelengths detected by the detecting means, wherein the irradiating means emits the plurality of lights having different wavelengths. Each having a polarization separation part for separating into S polarization and P polarization, and irradiating the substrate to be processed with the S polarization and the P polarization separated by the polarization separation part at mutually different angles. Exposure apparatus according to symptoms. 2. An alignment mark formed in advance on the substrate to be processed is a pattern having a periodicity in at least one direction, and the detecting means is provided in a direction having a periodicity of the alignment mark. The exposure apparatus according to claim 1, wherein the exposure apparatus is arranged in a direction perpendicular to the direction. 3. An exposure method for exposing an original pattern onto a substrate to be processed, comprising: separating a plurality of lights having different wavelengths into S-polarized light and P-polarized light, respectively; At different angles from each other on the alignment mark formed on the substrate to be processed, and the diffracted light diffracted by the alignment mark by the irradiation corresponds to the light of the plurality of irradiated wavelengths. The position of the alignment mark is determined based on the detected diffracted light corresponding to the plurality of wavelengths of light at the position optically conjugate with the substrate to be processed. Adjusting the relative position of the original image pattern and the substrate to be processed based on the original pattern, and exposing the original image pattern on the substrate to be processed whose relative position is adjusted. 4. An alignment mark formed in advance on the substrate to be processed is a pattern having periodicity in at least one direction, and diffracts the diffracted light in a direction having periodicity of the alignment mark. The exposure method according to claim 3, wherein the detection is performed from a right angle direction.