JPH07333165A - Foreign material inspection device and manufacture of semiconductor device using the inspection device - Google Patents

Abstract

PURPOSE:To highly accurately detect foreign material information regarding inspection surface by providing a detection means, a processing circuit, a judgement circuit and a displacement amount detection means. CONSTITUTION:A scanning spot 20 travels in a vertical direction across the illustration on the rotation of a scanning mirror 13, thereby optically scanning inspection surface 21. Furthermore, a scanning stage system 22 causes the surface 21 to move along a vertical direction (arrow direction) relative to the optical scanning direction of the spot 20, thereby optically scanning the whole of the surface 21 in a two-dimensional way. A displacement sensor 111 as a displacement amount detection means detects the displacement of the reticule (inspection surface) 21 from the prescribed position in a Z-axis (vertical) direction. Also, a judgement circuits 112 adjusts the slice level value (reference signal) of scattering intensity regarding the size of a foreign material on the surface 21, on the basis of a signal from the sensor 111. A processing circuit 100 detects foreign material information regarding the existence or non-existence of a foreign material on the surface of the reticule 21 and the size thereof, using a reference signal from the circuit 112 and a signal from a beat signal processing system 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foreign substance inspection apparatus and a semiconductor device manufacturing method using the same, and more particularly, to a reticle, a photomask, or other original plate on which a circuit pattern used in the semiconductor device manufacturing apparatus is formed. Or / and when foreign matter such as impermeable dust adheres to the inspection surface such as the surface of the pellicle protective film when the pellicle protective film is attached to the original plate, check the presence or absence of the foreign matter and its size. It is suitable for accurate detection.

[0002]

2. Description of the Related Art Generally, in an IC manufacturing process, an exposure circuit pattern formed on an original plate such as a reticle or a photomask is transferred onto a resist-coated wafer surface by a semiconductor printing apparatus (stepper or mask aligner). Is being manufactured.

At this time, if a foreign matter such as a pattern defect or dust is present on the surface of the original plate, the foreign matter is also transferred at the same time when the circuit pattern is transferred, which causes a reduction in the yield of IC manufacturing.

In particular, when a reticle is used and a circuit pattern is repeatedly printed on the wafer surface by the step-and-repeat method, if one harmful foreign substance is present on the reticle surface, the foreign substance is printed on the entire surface of the wafer. This causes the yield of the IC process to be greatly reduced.

Therefore, it is indispensable to detect the presence of foreign matter on the substrate in the IC manufacturing process, and various inspection methods have been conventionally proposed.

Generally, a method is widely used which utilizes the property that foreign matter isotropically scatters light.

FIG. 15 is a block diagram of a main part of a conventional foreign substance inspection apparatus for inspecting the presence or absence of a foreign substance by detecting scattered light from the foreign substance.

In the figure, the laser beam from the laser light source 151 is made into an optimum laser beam for foreign matter inspection by the polarizer 152, the filter 153, the collimator system 154, etc., and is passed through a mirror 155 to a scanning mirror 157 such as a polygon. It is guided to the scanning optical system including the fθ lens 158. The scanning laser beam from the fθ lens 158 is focused as a scanning spot 159 on the surface of the surface 160 to be inspected such as a reticle on which a circuit pattern is formed. Scanning spot 159 by scanning stage system 166
The surface to be inspected 160 is relatively moved in the direction orthogonal to the scanning direction, and the entire surface of the surface to be inspected 160 is scanned for inspection.

The lens system 161 and the aperture 1 are arranged rearward or laterally with respect to the incident direction of the laser beam.
63, and a detection system constituted by the photoelectric detector 164 is arranged. With respect to the arrangement direction of this detection system, the scattered light generated from the circuit pattern or the like when the laser beam is incident on the surface 160 to be inspected has a specific diffraction direction. There is.

In the apparatus having such a structure, when there is no foreign matter in the scanning spot 159, the photoelectric detector 1
The scattered light is not detected at 64, but if a foreign substance is present, the scattered light is isotropically generated from the minute foreign substance, so that the photoelectric detector 164 detects the scattered light. The presence or absence of foreign matter is inspected by processing this detection signal in the signal processing system 165.

[0011]

When the scanning stage 166 is driven to scan the entire inspection surface 160 in the conventional foreign substance inspection apparatus, the scanning stage 166 is driven in the Z direction (vertical direction) due to a drive error. It may fluctuate. When the position of the inspection surface 160 fluctuates in the vertical direction, the intensity of scattered light obtained by the photoelectric detector 164 changes.

Generally, in the case of detecting foreign matter information such as presence / absence of foreign matter and its size by using a slice level with respect to a signal obtained by the detecting means, when the signal obtained by the detecting means changes, the foreign matter information is detected. The detection accuracy will decrease.

According to the present invention, there is a drive error of the scanning stage, and even if the scanning stage fluctuates slightly in the vertical direction, it is possible to detect the foreign substance information on the inspection surface provided on the scanning stage with high accuracy. It is an object of the present invention to provide a foreign matter inspection apparatus which can easily obtain a semiconductor device having a resolution and a method for manufacturing a semiconductor device using the foreign matter inspection apparatus.

[0014]

A foreign matter inspection apparatus according to the present invention comprises: (1-1) scanning a surface to be inspected with a light beam from a light source using a scanning system, and detecting scattered light from the surface to be inspected. When the information is received by the means and the processing circuit uses the signal from the detection means to detect the foreign substance information on the inspection surface using the reference signal from the determination circuit, the determination circuit determines the vertical position of the inspection surface. It is characterized in that the reference signal is adjusted based on a signal from a displacement amount detecting means for detecting a variation.

(1-2) The first of the wavelength λ1 in the first polarization state
The light flux and the first light flux are scanned on at least the first light flux of the second light flux of the wavelength λ2 in the second polarization state in which the polarization state and the wavelength are different from each other on the inspection surface through the scanning system. Of the light fluxes having the second polarization state scattered by the light fluxes having changed polarization states and the heterodyne interference light of the second light fluxes are detected by the detection means, and the processing circuit uses the signal from the detection means. When detecting the foreign substance information on the inspection surface by using the reference signal from the determination circuit, the determination circuit detects the reference signal based on the signal from the displacement amount detecting means for detecting the vertical position variation of the inspection surface. It is characterized by adjusting.

The method of manufacturing a semiconductor device according to the present invention comprises (1-3) bringing the original plate into the foreign matter inspection device from the storage device,
The foreign matter inspection apparatus inspects foreign matter information such as presence or absence of foreign matter and size on the inspection surface of the original plate, and the foreign matter inspection apparatus determines that there is no foreign matter on the inspection surface or the foreign matter size is less than a predetermined size. When the judgment is made, the original plate is set at the exposure position of the exposure device, and when it is judged that there is a foreign matter of a predetermined size, it is cleaned by the cleaning device and then again inspected by the foreign matter inspection device, and the foreign matter of the predetermined size is detected. When it is determined that the original has disappeared, the original plate is set at the exposure position of the exposure apparatus, the pattern on the original plate is exposed and transferred onto the wafer, and the exposed and transferred original plate is manufactured into a semiconductor device through a developing process. At this time, the foreign matter inspection device scans an inspection surface with a light beam from a light source using a scanning system, receives scattered light from the inspection surface by a detection means, and processes it using a signal from the detection means. The circuit can detect the foreign substance information on the inspection surface. It is detected using a reference signal from a circuit, and the determination circuit adjusts the reference signal based on a signal from a displacement amount detecting means for detecting a vertical position variation of the inspection surface. It has a feature.

(1-4) The original plate is carried into the foreign substance inspection device from the storage device, and the foreign substance inspection device inspects foreign substance information such as the presence or absence of foreign substances on the inspection surface of the original plate and the size thereof. When it is determined that there is no foreign matter on the inspection surface or the size of the foreign matter is less than a predetermined value, the original plate is set at the exposure position of the exposure apparatus, and when it is determined that the foreign matter of a predetermined size exists, the cleaning is performed. After cleaning with the apparatus, the foreign matter inspection apparatus again inspects, and when it is determined that there is no foreign matter of a predetermined size, the original plate is set at the exposure position of the exposure apparatus, and the pattern on the original plate is exposed on the wafer. When a semiconductor device is manufactured by transferring the exposed and transferred original plate through a developing process, the foreign matter inspection apparatus determines that the first light flux having the wavelength λ1 in the first polarization state and the first light flux have polarization states and wavelengths. Second that is both different
At least the first of the second light fluxes of wavelength λ2 in the polarization state
The light beam is scanned on the inspection surface through a scanning system, and among the light beams whose polarization state has been changed due to scattering on the inspection surface, a light beam in the second polarization state and heterodyne interference light between the second light beam are generated. The detection circuit detects the foreign matter information on the inspection surface by using the signal from the detection circuit and the processing circuit using the reference signal from the determination circuit, and the determination circuit is perpendicular to the inspection surface. It is characterized in that the reference signal is adjusted on the basis of a signal from a displacement amount detecting means for detecting a positional change in a direction.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of a main part of a surface condition inspection apparatus of the present invention, and FIG. 2 is an enlarged explanatory view of a part of FIG.

In FIG. 1, reference numeral 1 is a laser light source. The laser beam generated from the laser light source 1 is made into a laser beam having an appropriate intensity composed of a linearly polarized component by the polarizing plate 2 and the filter system 3, and collimated by the collimator optical system 4. The laser beam from the collimator optical system 4 is P-polarized by the polarization beam splitter 5.
And the S-polarized laser beam S are separated into two. Of these, the P-polarized laser beam P is reflected by the mirror 6,
The acousto-optic element 9 driven by the driver 8 modulates at the shift frequency ω. The S-polarized laser beam S is modulated by the acousto-optic device 11 driven by the driver 10 at the shift frequency (ω + Δω) and reflected by the mirror 7. The two linearly polarized laser beams P and S that have been frequency-modulated are the polarization beam splitter 1
The two laser beams 12a are combined into two laser beams 12a having two linearly polarized lights that are orthogonal to each other and are different from each other by a shift frequency Δω.

The configuration for obtaining the laser beam 12a in the present embodiment is not limited to the above-described configuration, and only one acousto-optic element is used to modulate only one of the two laser beams at the shift frequency Δω. A configuration is also possible. Further, it may be obtained by using a Zeeman laser light source or by modulating the injection current of the semiconductor laser light source.

The laser beam 12a from the polarization beam splitter 12 is a scanning mirror (polygon mirror) 1
The light is guided to the polarization beam splitter 15 via an optical scanning system (scanning system) having the lens 3 and the fθ lens system 14. Then, the polarization beam splitter 15 separates the P-polarized laser beam 15a (shift frequency ω) and the S-polarized laser beam 15b (shift frequency ω + Δω).

The P-polarized laser beam 15a separated by the polarization beam splitter 15 is set by the filter system 16 so as to have the optimum intensity for foreign matter inspection, and is reflected by the mirror 18, and then is incident on the inspection surface 21 at the incident angle θ. Spot 20
Has converged as. The inspection surface 21 is made of, for example, a reticle or a mask, and a circuit pattern is formed on the surface.

On the other hand, the S-polarized laser beam 15b separated by the polarization beam splitter 15 is set by a filter system 17 so as to have an optimum intensity for foreign matter inspection, and the mirror 1
After being reflected by 9, the light is converged as a spot 20 on the inspection surface 21 at the incident angle φ.

In this embodiment, the two laser beams 15a and 15b are made to converge on the same spot 20 at different incident angles. The intensity ratio of the laser beam 15a and the laser beam 15b is, for example, about 1: 100. The size of the spot 20 is about 10 μm. Here, from the polarization beam splitter 15 to the spot 20
The optical path lengths up to are configured such that the P-polarized laser beam 15a and the S-polarized laser beam 15b have substantially the same length, so that even when the coherent lengths of the laser beams are not so long, they interfere with each other. ing.

A P-polarized laser beam 15a having an incident angle θ
In the 0th-order diffracted light direction (emission angle θ) by
Are arranged. The laser beam 15
With respect to the incident angle φ of b, the amount of scattered light (for example, diffracted scattered light due to the circuit pattern in the case of a reticle) generated from other than the foreign matter or defect to be detected on the inspection surface 21 reaches the photoelectric detector 29 as small as possible. The angle is selected.

The scanning spot 20 moves in the direction perpendicular to the paper surface of FIG. 1 as the scanning mirror 13 rotates,
As a result, the inspection surface 21 is optically scanned. Further, the scanning stage system 22 relatively moves the inspection surface 21 in the direction perpendicular to the optical scanning direction of the spot 20 (the direction of the arrow in the drawing). As a result, the entire inspection surface 21 is two-dimensionally optically scanned.

Reference numeral 111 denotes a displacement sensor as displacement amount detecting means, which detects the amount of displacement of the reticle (inspection surface) 21 from a predetermined position in the Z direction (vertical direction). Reference numeral 112 denotes a determination circuit, which adjusts a slice level value (reference signal) of scattered light intensity relating to the size of the foreign matter on the inspection surface 21 based on a signal from the displacement amount detection means 111. 100
Is a processing circuit, which detects the presence / absence of a foreign substance on the surface of the reticle 21 and the foreign substance information regarding the size thereof using the reference signal from the determination circuit 112 and the signal from the beat signal processing system 30.

In this embodiment, of the light emitted from the scanning spot 20 toward the photoelectric detector 29, the (A1) 0-order diffracted light 23 (P-polarized) of the P-polarized laser beam 15a (P-polarized), (A
2) Backscattered light 24 (P-polarized light + S-polarized light) depolarized by foreign matters or defects of the S-polarized laser beam 15b,
(A3) Three types of light, that is, backscattered light 25 (S-polarized light) due to the circuit pattern formed on the inspection surface 21 of the S-polarized laser beam 15b are targeted. The reason why depolarization occurs due to a foreign substance or a defect is that the surface of the defect portion is generally rough, so that the polarization component is disturbed when diffusely reflected and scattered to generate a polarization component different from the incident polarization plane. On the other hand, depolarization of light scattered by an object having a relatively uniform surface such as a circuit pattern is small.

The P-polarized 0-th order diffracted light 23 (shift frequency ω) generated in the direction of the photoelectric detector 29 and the P-polarized light component of the backscattered light 24 (shift frequency ω + Δω) due to a foreign matter or a defect are optical heterodyne interference due to coincidence of polarization planes. Cause
This interference light is photoelectrically converted to obtain a beat signal. That is, in the optical heterodyne method, the 0th-order diffracted light 23 is the reference light, and since it is P-polarized light, it interferes with this and becomes a beat signal that is scattered light having a P-polarized component due to depolarization in the backscattered light. Only 24. This means that only scattered light due to foreign matter or defects is detected as a beat signal, and even if scattered light from the circuit pattern exists, it does not become a beat signal, or even if it does, it is extremely weak. . As a result, in this embodiment, it is possible to inspect foreign matters and defects with a very high sensitivity and a high S / N ratio.

The scattered light taken in by the lens system 26 removes unnecessary components such as S-polarized light by a polarization filter 27 having a characteristic of passing only P-polarized light components, and reduces beat signal noise such as polarization leakage. .

After that, the light passes through the slit-shaped aperture 28 and is guided to the photoelectric detector 29. Photoelectric detector 2
The detection signal obtained in 9 is processed by the beat signal processing system 30. Then, the determination circuit 112 and the processing circuit 100 detect foreign matter information such as the presence or absence of a foreign matter or a defect based on the beat signal state at that time. The lens system 2
6, the polarization filter 27, the aperture 28, etc. each constitute one element of the detecting means 1001.

In this embodiment, the P-polarized 0th-order diffracted light 23 is used as a reference light, and this and the P-polarized light generated by depolarization of the S-polarized laser beam 15b are subjected to optical heterodyne interference to obtain a beat signal. But P polarization and S
The same detection can be performed even if the polarization relationship is completely exchanged. As an example of a configuration that achieves this,
The polarization beam splitter 15 may be changed in characteristics so that the laser beam 15a is S-polarized and the laser beam 15b is P-polarized, and the polarization filter 27 may have a characteristic of transmitting only the S-polarized component.

Next, a method of generating scattered light and detecting a beat signal in this embodiment will be described. FIG. 2 is an explanatory diagram of scattered light when a foreign substance and a circuit pattern exist near the position of the scanning spot 20 on the inspection surface 21.
In the figure, 201 is 0.3 μm attached to the inspection surface 21.
Approximately a foreign material, 202 is a circuit pattern, and 203 is a beat signal detection system including a polarization filter and the like.

As explained in FIG. 1 above, the shift frequency ω
P-polarized laser beam 15a modulated by and the S-polarized laser beam 15 modulated by the shift frequency (ω + Δω)
b is incident on the same spot position at incident angles θ and φ. The beat signal detection system 203 is arranged in the direction in which the 0th-order diffracted light of the inspection surface 21 of the laser beam 15a is generated. With respect to the S-polarized laser beam 15b, the beat signal detection system 203 is arranged in the direction in which backscattering is detected.

At this time, the 0th-order diffracted light 23 is incident regardless of the presence or absence of foreign matter because the size of the foreign matter to be inspected is about 0.3 μm and the spot diameter for scanning is sufficiently large at about 10 μm. The light reaches the beat signal detection system 203 while the polarization state of the light is substantially maintained. This can be explained from the fact that in the light diffraction phenomenon, the higher order diffracted light depends on the higher frequency component (spatial frequency) of the reflecting surface, and the 0th order diffracted light depends on the lower frequency component of the reflecting surface. That is, the 0th-order diffracted light is not significantly affected by the fine structure in the spot.

Now, assuming that the electric fields of the P-polarized laser beam 15a and the S-polarized laser beam 15b incident on the inspection surface 21 are E ₁ and E ₂ , respectively, it can be expressed as follows.

E ₁ = Ep · exp {j (ωt + θ ₁ )} (1) E ₂ = Es · exp [j {(ωt + Δω) t + θ ₂ )} (2) At this time, the above spot 0th-order diffracted light 23 from 20,
When the backscattered light 24 due to a foreign matter and the backscattered light 25 due to a circuit pattern are F ₁ , R ₁ and R ₂ , respectively, they are as follows.

F ₁ = αEp · exp {j (ωt + θ ′ ₁ )} (3) where α: 0th-order optical diffraction index R ₁ = ΔE ₁ s · exp [j {(ω + Δω) t + θ ′ ₂ }] + ΔE ₁ p · exp [j {(ω + Δω) t + θ ′ ₂ }] ... (4) R ₂ = ΔE ₂ s · exp [j {ω + Δω) t + θ ′ ₃ }] (5) At this time, the beat Regarding the intensity I of the combined beat signal detected by the signal detection system 203, only those having the same polarization plane cause interference, and the S-polarized component is removed by the polarization filter included in the beat detection system 203. Considering this, it can be expressed as follows.

I = | F ₁ + R ₁ + R ₂ | ² = (αEp) ² + ΔE ₁ p ² +2 αEp ΔE ₁ p · cos (Δωt + θ ′ ₂ −θ ′ ₁ ) (6) Given by equation (4) The amplitude ΔE ₁ p of the P-polarized light component generated by depolarization due to a foreign substance is very small, but Ep is much larger than ΔE ₁ p according to the third term of the equation (6). Therefore, the beat signal detection system 203 The output voltage of the beat signal detected in step 1 has better sensitivity than the direct detection of the backscattered light 24 due to foreign matter.

In this embodiment, the DC component and the AC component (frequency Δω) of the beat signal obtained by the equation (6) are selectively extracted by an appropriate method to remove noise such as stray light and further improve the S / N ratio is improved.

The beat signal detected here will be described. FIG. 3 is an explanatory diagram showing an example of the waveform of the detected beat signal. In the figure, 301 is an axis representing time t, 3
02 is an axis representing the intensity I of the detected signal, 306 is the detected beat signal, 303 is the DC component of the beat signal 306, 304 is the AC component of the beat signal 306, and 305 is the time width (the time width at which the beat signal is detected ( Δt).

As described above, the beat signal is not detected if there is no foreign matter or defect in the scanning spot, but if there is a foreign matter or defect, the frequency Δω as shown by the waveform 306 is obtained. Beat signal occurs during the time width Δt. Time width Δt (305) in which the beat signal 306 occurs
Is determined by the size of the scanning spot 20 and the speed at which the spot 20 scans the inspection surface as shown in FIG. That is, in FIG. 4, after the edge of the spot 20 moving at the scanning speed v (402) contacts the foreign matter 201, the spot 20
The time until reaching the position of a is the time width Δt (305) at which the beat signal in FIG. 3 is detected.

A specific configuration example of the beat signal processing system 30 for signal processing the detected beat signal will be described with reference to FIG. In the figure, reference numeral 801 denotes a photoelectric detector 29.
A preamplifier that amplifies the beat signal detected by
802 is the DC component 808 and AC of the amplified beat signal.
The signal processing system for individually detecting the component 807, the reference numeral 803, the 0th-order diffracted light monitor system for monitoring the intensity change of the 0th-order diffracted light 23 by detecting the DC component 808, and the reference numeral 809, which is obtained as a result of the monitoring. A correction signal for correcting the intensity fluctuation of the 0th-order diffracted light 23, 804 is a frequency filter for extracting a signal of frequency Δω from the detected AC components and correcting with a correction signal 809, and 805 is an output of the frequency filter. A counter 806 that determines whether or not a foreign matter or defect is compared with a threshold value and counts, and 806 is the number of foreign matter or defects and the inspection surface 2
It is a computer for storing and displaying the positions of foreign matters and defects on 1.

AC component 807 and DC component 808 of the beat signal detected by the photoelectric detector 29 from the above equation (6).
Are respectively expressed as follows.

(AC component) = 2αEpΔE ₁ p · cos (Δωt + θ ′ ₂ −θ ′ ₁ ) (7) (DC component) = (αEp) ² + ΔE ₁ p ² ≈ (αEp) ²・ ・ ・ (( 8) According to equation (7), the amplitude of the AC component of the beat signal is proportional to the intensity of the 0th-order diffracted light and the backscattered light from the foreign matter or defect.

When the inspection surface 21 is scanned by the spot 20, there is a possibility that the intensity of the 0th-order diffracted light may change due to the influence of the circuit pattern or the like. This change can be obtained by detecting the DC component from the equation (8). ing. Therefore, in order to perform measurement with a high S / N ratio without being affected by this, the DC component of the beat signal represented by the equation (8) is monitored by the 0th-order diffracted light monitor 803 and corrected. The intensity change of the 0th-order diffracted light 23 is corrected by the correction signal 809, for example, by changing the amplification factor of the signal after frequency filtering by the correction signal. As a result, the frequency filter 8
The intensity of the output pulse from 04 is proportional only to the intensity of scattered light from a foreign substance. Then, the counter 805 sets a threshold value for the noise level to determine whether the output pulse is due to a foreign substance or a defect to be detected, or whether the output pulse is due to a circuit pattern or the like. The result is fetched into the computer 806, and processing such as data storage and display is performed.

In FIG. 1, a scanning spot 20 has a spot formed by a laser beam 15a for generating so-called reference light and a spot formed by a laser beam 5b for generating scattered light from dust / foreign matter. The intensity of the interference signal, which is a foreign matter detection signal obtained when the degree of overlap changes in accordance with the movement of the system 22 and the scanning of the laser beam (which is generated in this case by the rotation of the polygon mirror 13) (directly AC in FIG. 3). (Reflected in the component 304) may fluctuate.

Next, the state at this time will be described with reference to FIG. FIG. 6 shows the position of the reflected light (scattered light) from the reticle 101, which is the surface to be inspected, that is, the reference spot 103 is the foreign matter 10.
When it is deviated by a value Δ from 2, the photoelectric detector (sensor) 110 is passed through the lens 104 and the field lens 105.
It is an explanatory view of the one-color condition of the interference wavefront of the incident light (the condition that the interference fringes are one-color in the light receiver).

In the figure, 106 is scattered light and 107 is reference light. In the figure, when the size of the sensor 110 is φ, the inclination of the wavefront when the sensor surface 110 is shifted by one color is θ = λ / φ (rad) (9) where the wavelength used is λ. When converted into the spot deviation δ by the lens 104 in the figure, the focal lengths of the lens 104 and the lens 105 are f
_{When 1} and f ₂ are set, δ = f ₂ · θ (10).

When the longitudinal magnification of the lens 104 is β, the amount of deviation Δ on the reticle surface 101 is Δ = δ / | β | (11). Therefore, for example, φ = 15 mm, λ = 0.488 μm, β = −0.36
When f ₂ = 49.7 mm, Δ = 4.4 μm, and the one-color condition on the reticle 101 side is Δ ≦
It becomes 4.4 μm. Therefore, it is not preferable that the scattered light from the spot 102 of the reference light and the dust (foreign matter) 103 deviate more than this amount.

Next, by considering the estimation of the contrast between the interference fringes on the sensor surface 110 and the beat signal from the number of stripes standing on the sensor surface 110 and the area ratio of light and dark, how the contrast of the beat signal changes will be considered. Calculate and show. Note _{C T = (S 1 -S 2} ) when the maximum of S ₁ of the beat signal of the contrast electric signal obtained as shown in FIG. 7 (photoelectric conversion signals), the minimum and S ₂ / (S ₁ + S ₂ ) It is defined in (12).

FIG. 8 is an explanatory view showing the situation of the number of interference fringes and the area ratio of light and dark on the sensor surface (circular opening) 110.
8 (a), (b), (c), and (d), the angle θ formed by the reference light 107 and the scattered light 106 from the foreign matter on the sensor surface 110 increases little by little, and on the opening of the sensor 110, The case where λ / 2, λ, 3 / 2λ, and 2λ are shown. If the sensor surface 110 is completely one color, the maximum contrast can be obtained, but if the reference wave and the scattered wave from the foreign matter form a tilt and the state becomes as shown in FIG. The signal appears to be small.

FIG. 9 is an explanatory diagram of a result of calculating how the contrast of the beat signal is lowered when there is a spot shift on the reticle in consideration of these circumstances. Specific values are φ = 15 mm, λ = 0.488 μm, β = −
When 0.36, f = 49.7 mm, as can be seen from FIG. 9, when deviation occurs on the reticle, the amplitude of the beat signal becomes small, and it is erroneously recognized as if it were scattering from a small dust. Become.

Therefore, in the present invention, the vertical movement of the scanning stage system 22 for reticle scanning shown in FIG. 1 is monitored by the displacement amount detecting means 111, and the signal based on the foreign matter detected by the interference based on the variation value of the scanning stage system 22 is detected. The slice level (reference signal), which serves as a reference when determining the size of a foreign substance based on the value of (beat signal), is made variable by the determination circuit 112. This allows the processing circuit 100 to more accurately determine the size of the foreign matter.

The displacement amount detecting means 111 is the scanning stage system 2
It is composed of a displacement sensor that monitors whether the surface (position of 20) of the reticle 21 moves up and down in the Z direction with the second scan. As the displacement sensor 111, for example, an optical micro KL130A (trade name) may be used,
Other photo detection systems may be configured. Light Micro KL13
0A has a stroke of 160 μm and a resolution of 0.1 μm or more.

FIG. 10 is a schematic view of a main part of a photodetection system as a displacement amount detecting means according to this embodiment. 1 in FIG.
13 is a light source (laser diode or LED), 114 is a lens for projecting light on the surface of the reticle 21, 115 is a lens on the light receiving side, and is reflected from the surface of the reticle 21 on the sensor 116 for detecting the light position. Is projecting light. 11
9 is a spot on the sensor 116. Reticle 21
Is displaced to the position 21a indicated by the dotted line, the spot 119
Hits a point 118 on the reticle 21, and the reflected light hits a point 120 on the sensor 116 for detecting the light position.

Therefore, in this embodiment, the difference between the positions of the point 120 and the spot 119 on the sensor 116 is detected to quantitatively detect the vertical movement of the reticle 21. For example, if a PSD (position sensor) or a two-divided sensor is used as the sensor 116, a resolution of the order of 0.1 μm can be obtained. The signal relating to the vertical movement of the reticle 21 thus obtained is input to the determination circuit 112 as a slice level setting system that makes the set value of the slice level determined by the correspondence between the foreign matter and the signal after the beat signal processing system 30 variable. . As shown in FIG. 9, the beat signal output changes depending on the amount of deviation from the predetermined vertical position of the reticle 21 (the state in which the reference light 15a and the illumination light 15b match on the reticle 21), even with a foreign matter of the same size ( descend).

Therefore, in this embodiment, the slice level (reference signal) is lowered by the determination circuit 112 according to the amount of deviation. Thus, the size of the foreign matter is detected with high accuracy.

FIG. 11 is a schematic view of the essential portions of Embodiment 2 of the present invention. In this embodiment, as compared with the first embodiment shown in FIG. 1, the position of the reflected light of the laser beam 15b from the surface of the reticle 21 is detected by the sensor 122 for detecting the light position, and the scanning stage system 22 for reticle scanning is used. The vertical movement is detected, the vertical movement amount of the reticle 21 is converted by the processing system 123, and the slice level is made variable by the determination circuit 124 as the slice level setting system using the signal from the processing system 123. However, other configurations are the same.

In the present embodiment, the sensor 122 and the processing system 123 constitute one element of the displacement amount detecting means.

FIG. 12 is a schematic view of the essential portions of Embodiment 3 of the present invention. Compared to the first embodiment shown in FIG. 1, this embodiment detects a vertical movement amount of the scanning stage system 22 by a displacement sensor 125 as a displacement amount detecting means, and the displacement sensor 1
Slice level setting system (decision circuit) from signals from 25
The difference is that the slice level is set at 126, and the other configurations are the same.

Although the surface of the reticle 21 is irradiated with light in this embodiment, the amount of vertical movement of the reticle 21 is detected by detecting the reflection of light from the lower surface of the reticle 21 or the lower surface of the scanning stage system 22. Is also good.

In the heterodyne interferometer shown in each of the above embodiments, the method of applying the reference light and the illuminating light to the foreign matter is included in the paper surface, but the method of causing interference is not limited to this. The scattered light may be in the case of an interferometer that receives light in a direction perpendicular to the paper surface or in a direction included in a surface close to the paper surface, and various interferometry methods can be applied.

FIG. 13 is a block diagram of essential parts of a method of manufacturing a semiconductor device having a foreign matter inspection apparatus of the present invention.

This embodiment shows the case where the circuit pattern provided on the original plate such as a reticle or a photomask is printed on a wafer and applied to a manufacturing system for manufacturing a semiconductor device. The system roughly includes an exposure device, a master plate storage device, a master plate inspection device (foreign material inspection device), and a controller, which are arranged in a clean room.

In FIG. 13, 901 is a far-ultraviolet light source such as an excimer laser, and 902 is a unitized illumination system. P. The original plate 903 set to the above is simultaneously illuminated from above with a predetermined NA (numerical aperture). Reference numeral 909 denotes a projection lens, which forms a circuit pattern formed on the original plate 903 on the wafer 9 such as a silicon substrate.
It is projected and printed on 10. At the time of projection printing, the wafer 910 is moved by 1 according to the step feed of the moving stage 911.
The exposure is repeated while shifting each shot. An alignment system 900 aligns the original plate 903 and the wafer 910 with each other prior to the exposure operation. Alignment system 9
00 has at least one original plate observing microscope system.

An exposure apparatus is constituted by the above members.

Reference numeral 914 denotes an original plate storage device, which stores a plurality of original plates inside. Reference numeral 913 is an inspection device (foreign substance inspection device) for detecting the presence or absence of a foreign substance on the original plate, and includes the configuration shown in each of the previous embodiments. The inspection device 913 is configured so that the selected original plate is pulled out from the storage device 914 and the exposure position E.E. P. The original is inspected for foreign matter before being set to.

The principle and operation of the foreign matter inspection at this time utilize those shown in the above-mentioned respective embodiments. The controller 918 controls the sequence of the entire system, and controls the operation commands of the storage device 914 and the inspection device 913 as well as the sequence of basic operations of the exposure apparatus, such as alignment / exposure / wafer step feed.

The manufacturing process of a semiconductor device using the system of this embodiment will be described below.

First, the original plate 90 to be used from the storage device 914.
3 is taken out and set in the inspection device 913.

Then, the inspection device 913 inspects the foreign matter on the original plate 903. As a result of the inspection, when it is confirmed that there is no foreign matter, the original plate is exposed to the exposure position E. P. Set to.

Next, the semiconductor wafer 910 which is the exposure target is set on the moving stage 911. And step &
According to the step feed of the moving stage 911 by the repeat method, the semiconductor wafer 9
The original plate pattern is reduced and projected on each area of 10 and exposed.
This operation is repeated.

When the entire surface of one semiconductor wafer 910 has been exposed, the semiconductor wafer 910 is accommodated and a new semiconductor wafer is supplied, and similarly, the exposure of the original pattern is repeated by the step & repeat method.

The exposed wafer which has been exposed is subjected to known predetermined processing such as development and etching by an apparatus provided separately from the present system. After this, an assembling process such as dicing, wire bonding and packaging is performed to manufacture a semiconductor device.

According to this embodiment, it is possible to manufacture a highly integrated semiconductor device having a very fine circuit pattern, which was difficult to manufacture in the past.

FIG. 14 is a block diagram showing an embodiment of an original plate cleaning inspection system for manufacturing a semiconductor device. The system roughly has an original plate storage device, a cleaning device, a drying device, an inspection device, and a controller, which are arranged in a clean chamber.

In FIG. 14, reference numeral 920 denotes an original plate accommodating device, which accommodates a plurality of original plates and supplies the original plates to be cleaned. Reference numeral 921 denotes a cleaning device, which cleans the original plate with pure water. A drying device 922 dries the washed original plate. Reference numeral 923 denotes an original plate inspection device, which includes the configuration of the above-described embodiment, and inspects foreign substances on the cleaned original plate. A controller 924 controls the sequence of the entire system.

The operation will be described below. First, the original plate to be cleaned is taken out from the original plate storage device 920 and supplied to the cleaning device 921. The original plate cleaned by the cleaning device 921 is sent to the drying device 922 to be dried. After drying, it is sent to the inspection device 923, and the inspection device 923 inspects the foreign matter on the original plate using the method of the previous embodiment.

If no foreign matter is confirmed as a result of the inspection, the original plate is returned to the storage device 920. If foreign matter is confirmed,
This original plate is returned to the cleaning device 921 for cleaning, and the drying device 9
After the drying operation is performed at 22, the inspection device 923 performs a re-inspection, and this is repeated until the foreign matter is completely removed. Then, the completely cleaned original plate is returned to the storage device 920.

Thereafter, the cleaned original plate is set in the exposure apparatus, and the circuit pattern of the original plate is printed on the semiconductor wafer to manufacture a semiconductor device. This makes it possible to manufacture a highly integrated semiconductor device having a very fine circuit pattern, which has been difficult to manufacture in the past.

[0082]

According to the present invention, it is possible to detect minute foreign matters, defects, etc., which were difficult to detect in the past, with a high S / N ratio.

By applying the present invention to a semiconductor manufacturing apparatus, it is possible to manufacture a highly integrated semiconductor device, which has been difficult to manufacture in the past.

Further, according to the present invention, even if there is a driving error of the scanning stage and the scanning stage fluctuates slightly in the vertical direction, it is possible to detect the foreign substance information on the inspection surface provided on the scanning stage with high accuracy. Therefore, it is possible to achieve the foreign matter inspection apparatus and the semiconductor device manufacturing method using the same, which can easily obtain a high-resolution semiconductor device.

[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 enlarged explanatory view of a part of FIG.

FIG. 3 is a heterodyne interference signal obtained by the detection means of FIG.

4 is an explanatory diagram of the light spot of FIG.

FIG. 5 is a block diagram of a main part of a signal processing system according to the present invention.

FIG. 6 is an optical path diagram of heterodyne interference according to the present invention.

FIG. 7 is an explanatory diagram of a beat signal according to the present invention.

FIG. 8 is an explanatory diagram of interference fringes on the incident surface of the detection means according to the present invention.

FIG. 9 is an explanatory diagram of a spot deviation interval and a beat signal contrast according to the present invention.

FIG. 10 is a schematic view of a displacement amount detecting means according to the present invention.

FIG. 11 is a schematic view of a main part of a second embodiment according to the present invention.

FIG. 12 is a schematic view of a main part of a third embodiment according to the present invention.

FIG. 13 is a schematic view of a main part of a method for manufacturing a semiconductor device according to the present invention.

FIG. 14 is a block diagram of the original plate cleaning inspection system according to the present invention.

FIG. 15 is a schematic view of a main part of a conventional foreign matter inspection device.

[Explanation of symbols]

 1 Laser Light Source 2 Polarizing Plate 4 Collimator Lens 5, 12, 15 Polarizing Beam Splitter 6, 7, 18, 19 Mirror 8, 10 Driver 9, 11 Acousto-Optical Element 13 Polygon Mirror 21 Inspection Surface 22 Scanning Stage System 1001 Detecting Unit 111, 122,125 Displacement amount detecting means 112,124,126 Judgment circuit 100 Processing circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location H01L 21/30 515 F (72) Inventor Toshihiko Tsuji 3-30-2 Shimomaruko, Ota-ku, Tokyo Non non corporation

Claims (4)

[Claims] 1. A light beam from a light source is used to scan an inspection surface using a scanning system, scattered light from the inspection surface is received by a detection means, and a processing circuit uses a signal from the detection means. When detecting the foreign substance information on the inspection surface by using the reference signal from the determination circuit, the determination circuit detects the reference signal based on the signal from the displacement amount detecting means for detecting the vertical position variation of the inspection surface. The foreign matter inspection device is characterized by adjusting the. 2. A first light beam having a wavelength λ1 in a first polarization state and a second light beam having a wavelength λ2 in a second polarization state in which the polarization state and the wavelength of the first light beam are different from each other, and at least the first light beam is scanned. The inspection means scans the inspection surface through the system and detects the heterodyne interference light between the second light flux and the light flux that is in the second polarization state among the light fluxes that are scattered on the inspection surface and whose polarization state is changed. When the detection circuit detects the foreign substance information on the inspection surface by using the signal from the detection means and the reference signal from the determination circuit, the determination circuit detects the position variation in the vertical direction of the inspection surface. A foreign matter inspection apparatus, wherein the reference signal is adjusted based on a signal from a displacement amount detecting means to be detected. 3. The foreign material inspection apparatus carries the original plate into a foreign matter inspection apparatus, and the foreign matter inspection apparatus inspects foreign matter information such as presence / absence and size of the foreign matter on the inspection surface of the original sheet, and the foreign matter inspection apparatus performs the inspection. When it is determined that there is no foreign matter on the surface or the size of the foreign matter is less than a predetermined size, the original plate is set at the exposure position of the exposure device, and when it is determined that there is a foreign matter of a predetermined size, cleaning is performed by the cleaning device. After that, inspect again with the foreign matter inspection device,
When it is judged that the foreign matter of a predetermined size is gone, the original plate is set at the exposure position of the exposure device, the pattern on the original plate is exposed and transferred onto the wafer, and the original plate transferred by the exposure is subjected to a developing process. When manufacturing a semiconductor device by means of the above, the foreign substance inspection apparatus scans the inspection surface with a light beam from a light source using a scanning system, receives scattered light from the inspection surface by a detection means, and outputs the scattered light from the detection means. Of the foreign substance information on the inspection surface by the processing circuit using the signal of the above-mentioned signal using the reference signal from the determination circuit, and the determination circuit detects the displacement amount for detecting the vertical position fluctuation of the inspection surface. A method of manufacturing a semiconductor device, wherein the reference signal is adjusted based on a signal from the means. 4. The foreign material inspection apparatus carries the original plate into a foreign matter inspection apparatus, and the foreign matter inspection apparatus inspects foreign matter information such as presence / absence and size of the foreign matter on the inspection surface of the original sheet, and the foreign matter inspection apparatus performs the inspection. When it is determined that there is no foreign matter on the surface or the size of the foreign matter is less than a predetermined size, the original plate is set at the exposure position of the exposure apparatus, and when it is determined that there is a foreign matter of a predetermined size, the cleaning apparatus cleans it. After that, inspect again with the foreign matter inspection device,
When it is determined that the foreign matter of a predetermined size is gone, the original plate is set at the exposure position of the exposure device, the pattern on the original plate is exposed and transferred onto a wafer, and the original plate transferred by the exposure is subjected to a development processing step. When manufacturing a semiconductor device by means of the above, the foreign matter inspection apparatus uses the first light flux of wavelength λ1 in the first polarization state and the second light flux of wavelength λ2 in the second polarization state in which both the polarization state and the wavelength are different from each other. At least the first light flux is scanned on the inspection surface through the scanning system, and the light flux that has been changed to the second polarization state among the light fluxes that have been scattered on the inspection surface and have changed the polarization state, and the second light flux. The heterodyne interference light of is detected by the detecting means, the signal from the detecting means is used to detect the foreign substance information on the inspection surface by using the reference signal from the determining circuit, and the determining circuit is Detects vertical position fluctuation of the inspection surface A method of manufacturing a semiconductor device, wherein the reference signal is adjusted based on a signal from a displacement amount detecting means.