JP2808957B2 - Position detecting method and exposure apparatus using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting method and an exposure apparatus using the same, for example, a mask or a reticle (hereinafter, referred to as a "mask") in a proximity type exposure apparatus for manufacturing semiconductor devices or a so-called stepper. ), Etc., before performing relative positioning (alignment) between a mask and a wafer when exposing and transferring a fine electronic circuit pattern formed on a first object surface such as a wafer onto a second object surface such as a wafer. The present invention relates to a position detecting method suitable for positioning a light beam for alignment and an alignment pattern to be performed, and an exposure apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, in an exposure apparatus for manufacturing a semiconductor, relative positioning of a mask and a wafer has been an important factor for improving performance. In particular, in recent exposure apparatuses, alignment is required to have an alignment accuracy of, for example, submicron or less in order to achieve high integration of semiconductor elements.

In many alignment apparatuses, a so-called alignment pattern (also referred to as "alignment mark") for alignment is provided on a so-called scribe line on a mask and a wafer surface, and position information obtained from the scribe line is used. Alignment of both.

Conventionally, when aligning a light beam with an alignment pattern on a substrate surface (mask or wafer), the light beam and the alignment pattern are set based on mechanical precision so as to be at predetermined positions. I was

[0005] On the other hand, the present applicant has filed Japanese Patent Application No. 2-143.
No. 869 proposes a position detecting device which performs positioning of an alignment light beam and an alignment pattern in a stepper with high accuracy by detecting a peak position of a diffracted light amount from a linear diffraction grating.

At this time, as shown in FIG. 15A, an alignment pattern 50 for positioning the mask and the wafer is provided on a so-called scribe line 21 around an electronic circuit pattern 22 on the surface of the mask 21 as shown in FIG. Separately, patterns 100a, 100a shown in FIG.
b is provided.

[0007] Then, diffracted light of a predetermined order from the diffraction grating pattern 100 is guided to a sensor (not shown), and from the maximum value of the intensity of the output signal from the sensor, the matching state between the light beam and the diffraction grating pattern 100 is determined. That is, the positional relationship between the light beam and the diffraction grating pattern is determined. By utilizing the positional relationship at this time, the light beam is accurately incident on a predetermined position of the alignment pattern 50.

FIG. 16 shows the light beams 72a and 72 at this time.
b and each pattern 100a, 1 of the diffraction grating pattern 100
FIG. 9 is an explanatory diagram showing a positional relationship with the image data 00b.

In FIG. 1, the size of the light beams 72a and 72b is set in accordance with the size of the normal alignment pattern 50. The light beams 72a and 72b are
As shown in FIG. 17, a predetermined order of diffracted light, which is moved within the plane (mask plane) and diffracted by the diffraction grating pattern, is incident on a sensor (not shown).
The output signal from the sensor is maximized when it is accurately incident on a predetermined position of 00a or 100b.

Now, assuming that the positions of the light beams in the Y and X directions at which the output signal from the sensor is maximum are y _P and x _P , respectively, the position of the alignment pattern 50 on the mask and the diffraction grating pattern 100 (100a, 100b) ) Is known in advance from the mask pattern design value,
The light beam is set on the alignment pattern 50 by using the values of x _P and y _P at this time.

[0011]

[Problems to be Solved by the Invention] Japanese Patent Application No. 2-14386
In the position detecting device proposed in No. 9, the alignment accuracy between the light beam originally desired to be aligned and the alignment pattern may be affected by the material of the alignment pattern, manufacturing errors, and the like.

[0012] The influence of the alignment of the light beam with the alignment pattern at this time is particularly important when performing high-precision alignment in a stepper.

Usually, the width of a scribe line on a wafer surface and a mask provided with an alignment mark is 50 μm to 10 μm.
It is about 0 μm. The scribe line width is 250 μm to 5 μm on the reticle surface with a stepper having a projection magnification of 5 times.
The thickness is 50 μm to 100 μm in an X-ray exposure close-contact (proximity) apparatus, and is provided so that the alignment mark can be accommodated in an area of this width. Thus, the alignment pattern is set within the scribe line width.

In order to efficiently irradiate an alignment pattern provided in such a small area with a light beam (light beam) from an alignment head (optical head, light projecting means), the light beam has a size corresponding to the size of the alignment pattern. It is necessary to reduce the diameter. Further, it is necessary to irradiate a light beam to an accurate position with respect to the alignment pattern.

In general, when the alignment pattern is irradiated with a light beam incorrectly, the amount of light (signal light) detected by the sensor decreases accordingly. If the light flux diameter is sufficiently large with respect to the size of the alignment pattern, the alignment pattern can be irradiated with a substantially uniform light amount distribution.

However, when irradiating the light beam efficiently and irradiating the circuit pattern area other than the alignment pattern area, unnecessary scattered light becomes noise from the circuit pattern. It is necessary to irradiate with a light beam having a substantially equal size corresponding to the size.

Generally, when the diameter of the light beam is reduced in this manner, the light amount distribution of the light beam becomes non-uniform on the alignment pattern surface on the mask (reticle) surface.

Further, when the irradiation position of the light beam on the alignment pattern is significantly shifted, the spot position of the diffracted light (ie, the information on the shift between the mask and the wafer) obtained from the alignment pattern when the mask and the wafer are slightly shifted. This differs from the case where the irradiation position of the light beam to the alignment pattern is not shifted. That is, if the irradiation position of the light beam irradiated on the alignment pattern shifts, an error occurs in the alignment detection.

Therefore, the positioning accuracy of the light beam (light projecting means) and the alignment mark (the first object or the second object) is improved, and by setting the optimum light beam diameter, the alignment can be made more accurate. However, if it is attempted to improve the positioning accuracy of the light beam on the alignment mark surface only by a mechanical system, there is a problem that it is difficult to achieve long-term stability without complicating the system and increasing its size. .

In the method of positioning the light beam and the alignment pattern based on the change in the intensity of the light amount, the intensity of the diffracted light may change due to the manufacturing error and material of the alignment pattern for each test object (mask or wafer). There was a limit on the alignment accuracy.

According to the present invention, the positioning of the incidence of a light beam from a light projecting means (optical head) on a physical optical element which is an alignment mark provided on a first object or a second object is performed with high accuracy by a simple method. It is an object of the present invention to provide a position detecting method capable of reducing the mechanical accuracy and the assembling accuracy and the like and performing the subsequent relative position detection of the first object and the second object with high accuracy, and an exposure apparatus using the same.

[0022]

[Means for Solving the Problems]

(A) The position detecting method according to the present invention is a position detecting method for irradiating a substrate with a light beam and detecting a position of an optical head for receiving the light beam from the substrate in a predetermined direction with respect to the substrate. By forming a diffraction grating pattern having a width in the direction smaller than the width in the direction of the light beam on the substrate on the substrate, the position of the light beam and the diffraction grating pattern in the direction can be shifted. Accordingly, the incident position of the predetermined order diffracted light generated from the diffraction grating pattern on the sensor in the optical head is changed, and the predetermined order diffracted light is irradiated by irradiating the light beam to the diffraction grating pattern. The diffracted light of the predetermined order is incident on a sensor in the optical head, and the diffracted light of the predetermined order is incident on the sensor. Position is detected and is characterized by detecting the position of the optical head based on the deviation from a predetermined position of the incident position the detected.

In particular, (a-1) a reference diffraction grating pattern having a width in the direction that is sufficiently larger than the width of the light beam in the direction on the substrate is formed on the substrate; By irradiating the light beam in the pattern, a reference diffracted light is generated in substantially the same direction as the diffracted light of the predetermined order, the reference diffracted light is incident on the sensor, and the reference diffracted light is incident on the sensor. An incident position is detected, and the detected incident position is set as the predetermined position.

(B) In the positioning method according to the present invention, a substrate is irradiated with a light beam, and the position of an optical head for receiving the light beam from the substrate in a predetermined direction with respect to the substrate is detected. In a positioning method for positioning the optical head at an arbitrary position with respect to the substrate based on the diffraction grating, the substrate has a diffraction grating having a width in the direction smaller than the width of the light beam on the substrate in the direction. By forming the pattern, the incident position of the diffracted light of a predetermined order generated from the diffraction grating pattern on the sensor in the optical head changes in accordance with the positional deviation of the light beam and the diffraction grating pattern in the direction. Irradiating the diffraction grating pattern with the light beam to generate the diffracted light of the predetermined order, Light is incident on a sensor in the optical head, an incident position of the diffracted light of the predetermined order on the sensor is detected, and the detected incident position is shifted based on a deviation from a predetermined position. It is characterized in that the position is detected.

In particular, (b-1) a reference diffraction grating pattern having a width in the direction that is sufficiently larger than the width of the light beam in the direction on the substrate is formed on the substrate; By irradiating the light beam in the pattern, a reference diffracted light is generated in substantially the same direction as the diffracted light of the predetermined order, the reference diffracted light is incident on the sensor, and the reference diffracted light is incident on the sensor. Detecting an incident position and setting the detected incident position as the predetermined position.

(B-2) A zone plate pattern for positioning is formed at a predetermined distance from the diffraction grating pattern on the substrate in a predetermined direction, and the optical head is positioned at the center of the light beam. Positioning the optical head so as to hit a predetermined portion of the zone plate pattern.

(B-3) The substrate is formed of a mask on which a circuit pattern is formed, and the diffraction grating pattern and the zone plate pattern are formed around the circuit pattern.

(B-4) The optical head directs the light beam to the mask along an incident optical path inclined with respect to the surface of the mask, and the optical head is on the same side of the surface of the mask as the incident optical path. Receiving the light beam emitted from the mask along at least one outgoing optical path inclined to the light, wherein the diffraction grating pattern allows the diffracted light of the predetermined order to be emitted from the mask along the outgoing optical path. Be configured to

The features are as follows.

(C) In the method of manufacturing a semiconductor device according to the present invention, a light beam is irradiated along an incident optical path inclined with respect to the surface of the mask, and the incident optical path is transmitted from the mask to the surface of the mask. An optical head that receives the light beam emitted along at least one emission optical path inclined to the same side detects a position in a predetermined direction with respect to the mask, and based on the detection, moves the optical head to the mask. A signal which is positioned with respect to a zone plate pattern, makes the light beam incident on a zone plate mark of a wafer via the zone plate pattern of the mask, and receives a signal affected by the zone plate pattern and the zone plate mark. Emitting light along the emission optical path, receiving the signal light by the optical head, and using the signal light After detecting the misalignment between the mask and the wafer, aligning the mask and the wafer in accordance with the detection, exposing the wafer through a circuit pattern of the mask, and exposing the circuit pattern of the mask on the wafer. Forming a diffraction grating pattern having a width in the direction smaller than the width in the direction of the light beam on the mask on the mask. The incident position of a predetermined order of diffracted light generated from the diffraction grating pattern on a sensor in the optical head is changed in accordance with the positional deviation of the light beam and the diffraction grating pattern in the direction, and the diffraction of the light beam is performed. By irradiating a grating pattern, diffracted light of the predetermined order is generated along the outgoing optical path. The diffracted light of the order is incident on a sensor in the optical head, the incident position of the diffracted light of the predetermined order on the sensor is detected, and the detected incident position is shifted based on a deviation from a predetermined position. It is characterized in that the position of the optical head is detected.

In particular, (c-1) a reference diffraction grating pattern having a width in the direction sufficiently larger than the width of the light beam in the direction on the mask is formed on the mask; By irradiating the light beam in the pattern, a reference diffracted light is generated in substantially the same direction as the diffracted light of the predetermined order, and the reference diffracted light is incident on the sensor.
Detecting the incident position of the reference diffraction light on the sensor,
The detected incident position is set as the predetermined position.

(D) The exposure apparatus of the present invention irradiates the mask with a light beam along an incident optical path inclined with respect to the surface of the mask, and the light beam is radiated from the mask to the surface of the mask. An optical head for receiving the light beam emitted along at least one emission optical path inclined to the same side,
Detecting means for receiving an output from at least one sensor in the optical head to detect a position of the optical head in a predetermined direction with respect to the mask and a position of the wafer with respect to the mask; Means for positioning the optical head with respect to the zone plate pattern of the mask, and means for positioning the mask and the wafer based on detection by the detection means, wherein the optical head is A signal emitted along the emission optical path under the action of the zone plate pattern and the zone plate mark by causing the light beam to enter the zone plate mark of the wafer via the zone plate pattern of the mask. In an exposure apparatus configured to receive light, the mask is A reference grating pattern having a width in the direction sufficiently larger than the width of the light beam on the mask in the direction; and a width in the direction smaller than the width of the light beam in the direction on the mask. A diffraction grating pattern is formed, and the incident position of a predetermined order of diffracted light generated from the diffraction grating pattern on the sensor in the optical head according to the positional deviation of the light beam and the diffraction grating pattern in the direction is detected. The optical head is configured to receive the reference diffraction light generated along the emission optical path by irradiating the light beam in the reference diffraction grating pattern with the sensor, and the reference head receives the reference diffraction light. Outputting a first signal corresponding to the incident position of the diffracted light and irradiating the diffraction grating pattern with the light beam. The sensor receives the diffracted light of the predetermined order generated along the emission optical path and outputs a second signal corresponding to the incident position, and the detecting means uses the first and second signals to generate the second signal. A position of the optical head in the direction with respect to the mask is detected.

[0033]

1 and 2 are diagrams for explaining the principle of a position detecting method according to the present invention.

FIG. 3 is a view showing a state in which the positional relationship between the light beam and the alignment pattern is known in advance, for example, a diffraction grating pattern, before determining the positional relationship between the light beam and the alignment pattern for performing alignment. 2 shows a case where the positional relationship is determined.

FIG. 1A shows a diffraction grating pattern 1001,
1B shows a positional relationship between the light beams 1002 and 1004, and FIGS. 1B and 1C show changes in light spots 1010, 1011 and 1010a on the sensor surface 1008. FIG.

FIG. 2 shows a diffraction grating pattern 1001 (100
The arrangement relationship between the light projecting means 1007 and the light receiving means 1008 for 2) is shown.

In FIG. 1A, light beams 1004 and 100
5 and the direction in which alignment is desired (X
Pattern 10 with a small diffraction grating pattern in
01 and a large pattern 1002 are provided on the substrate 1000.

As shown in FIG.
When the light beam 1004 is incident on the
The diffracted light 1009 from No. 1 is the pattern 100 in which a part of the light beam 1004 is cut off at the edge of the pattern 1001
1 becomes a diffracted light irradiated from a position deviated from the center of the pattern 1, and the pattern 1 is applied to the sensor surface 1008 as shown in FIG.
A light spot 1010 that changes in accordance with the displacement between the light beam 001 and the light beam 1004 is formed.

In this case, the pattern 1001 is the pattern 1
Δ in the X direction in which alignment is desired, as in 001a.
If the position is shifted by X, the position of the edge moves, and the light spot 1010a by the diffracted light on the sensor surface 1008 is moved.
Moves to a position shifted from the position of the light spot 1010 by ΔXa.

On the other hand, when the light beam 1005 is incident on a sufficiently large pattern 1002 as shown in FIG. 1A, the diffracted light 1009a from the pattern 1002 is cut off at the edge of the pattern 1002. No light spot 1011 on the sensor surface 1008
To form In this case, even if the pattern 1002 is shifted by ΔX in the X direction in which the alignment is desired to be performed, the diffracted light does not move on the sensor surface 1008 and the position of the light spot 1011 remains.

Therefore, in the present invention, the center of the light beam is defined as the position of the luminous flux of the diffracted light from the pattern 1002 (a pattern that generates the diffracted light that is not limited by the aperture) and the pattern 1001 smaller than the light beam diameter.
The positional relationship between the light beam and the pattern 1001 (1002) is determined by aligning the positions of the luminous fluxes of the diffracted light from the (pattern generating the diffracted light limited by the aperture).

In the present invention, since the pattern 1001 for generating the diffracted light limited by the aperture represents a position on the object 1000, an alignment pattern (not shown) arranged at an arbitrary position on the object 1000 from this position. A light beam is incident on a predetermined position.

FIG. 3 shows an alignment pattern 10 on a mask (object) 1000 in the position detecting method according to the first embodiment of the present invention.
FIG. 4 is a schematic diagram showing a state in which a light beam (1004, 1005, 1006) is incident on a diffraction grating pattern (1001, 1002). FIG. 1002,100
FIG. 5 is a schematic view showing a state in which the light that has been incident on 3) and diffracted is incident on the sensor 1008, and FIG.
FIG. 4 is an explanatory diagram showing a light beam incident position on a surface.

In FIG. 3, first, the light beams (1004, 10
05) and the diffraction grating pattern (1001, 1002). After obtaining the positional relationship at this time, the alignment pattern 10 whose positional relationship with the diffraction grating patterns (1001, 1002) is known in advance.
3 shows a case where a light beam is incident on a predetermined position.

In FIG. 3, a pattern 1001 is a pattern for generating diffracted light limited by an aperture.
Reference numeral 002 denotes a pattern that generates diffracted light that is not limited by an aperture. Each of the patterns 1001 and 1002 is formed of, for example, a line and space linear diffraction grating of about 1.5 μm.

The alignment pattern 1003 is a pattern for finally performing positioning with the light beam, is on the same plane (object plane 1000) as the pattern 1001, and
Direction is set at a position separated by a known amount y ₁ in the Y direction at the same position.

A light beam 1005 shows a spot of the light beam when it is incident on the pattern 1002 which is not restricted by the aperture. The light beam 1004 is a pattern 1 which is restricted by the aperture.
001 shows the spot of the light beam when it is incident.

FIG. 5A shows the sensor surface 10.
8 shows the position of the light beam when viewed from the front, and FIGS. 5B and 5C show the intensity distribution of the light beam on the sensor surface 1008, respectively.

Next, a procedure for performing positioning in the direction (X direction) in which the light beam is to be aligned with the alignment pattern 1003 will be described.

The light beam (irradiation optical system) and the sensor 1
Reference numeral 008 is housed in an optical head (alignment head) and moves integrally.

First, the approximate position is adjusted so that the light beam is irradiated into the pattern 1002 for positioning the light beam. The pattern 1002 for positioning has a large pattern size, and the light beam 1005 emits diffracted light without being restricted by the edge of the pattern 1002. This diffracted light produces an intensity distribution as shown in FIG. Even if the light beam and this pattern 1002 are relatively shifted, the intensity distribution does not change. Therefore, the incident position of the diffracted light on the sensor surface 1008 is determined as a reference position.

The reference position can be obtained, for example, by using the sensor 1008 as a one-dimensional CCD line sensor, using the position of the bit showing the maximum intensity as the reference position, or calculating the center of gravity of the light quantity distribution from the light intensity of each bit. And the like can be applied.

Next, the light beam is moved by a predetermined amount y ₀ in the direction (Y) orthogonal to the direction in which the position is to be aligned, and is irradiated onto the positioning pattern 1001. Pattern 10 for positioning
01 has a small pattern size, and the light beam 1004 emits diffracted light whose aperture is limited at the edge of the pattern 1001. This diffracted light is shown on the sensor surface 1008 in FIG.
This produces an intensity distribution as shown by

In this case, when the center of the light beam and the pattern for positioning are shifted by ΔX in the X direction in which the alignment is desired to be performed, the diffracted light beam is changed according to the shift amount.
ΔX shifts on eight surfaces.

Therefore, it is desired to move the light beam (optical head, alignment head), for example, so that the diffracted light beam comes to the reference position on the sensor surface 1008, thereby aligning the light beam with the object 1000. Move. As described above, the positioning pattern 1001 on the object 1000 and the light beam are positioned.

Finally, the light beam (optical head, alignment head) is moved by a known predetermined amount (y ₁ ) to the alignment pattern 1003 on the object 1000, thereby positioning the alignment pattern 1003 and the light beam.

FIG. 6 to FIG. 10 are explanatory views of a part of the exposure apparatus according to the second embodiment of the present invention and each element related thereto.

FIG. 6 is a schematic view of a main part of an exposure apparatus, and shows a case where the present invention is applied to positioning of an alignment light and an alignment pattern in an X-ray proximity exposure apparatus. FIG. 7 is an explanatory diagram on the surface of the mask 23 in FIG.

In FIG. 7, in order to align the alignment light beam with the alignment mark 50, an outer cross-shaped diffraction grating pattern (cross mark) 20 is used as a pattern for positioning the light beam as a circuit pattern of the mask 23. It is provided at each of the four corners of the scribe line 21 around the area 22.

The alignment heads (optical heads) 14 are provided corresponding to the four sides of the mask 23, respectively, and detect these corresponding patterns.

FIG. 8 focuses on one alignment head, and shows the positional relationship between the corresponding cross mark 20, the position of the diffracted light reflected from the diffraction grating of the cross mark 20, and the sensor 26 for detecting the position. . FIG. 8A shows the sensor surface 26, and FIG. 8B shows the cross mark 20 on the mask surface 23.

The cross mark 20 is formed by a line-and-space grid of, for example, 1.5 μm parallel to the X direction. The size of the entire pattern is 1 mm in both the X and Y directions
It is about.

FIG. 9 is an explanatory diagram showing an optical path from the time when the light beam from the light source 27 enters the cross mark 20 to the time when the light beam is diffracted and enters the sensor 26.

The light source 27 is, for example, a laser diode (L
D, wavelength λ = 0.785 μm). FIG. 9 shows an optical path in which an alignment light beam from the light source 27 is incident on the cross mark 20 and diffracted light of a predetermined order diffracted is incident on the sensor 26.

FIG. 10 shows diffracted light of each order when a light beam 72 is incident on a diffraction grating 71 having a general grating pitch P.

Generally, as shown in FIG. 10, when light 72 is incident on a reflection type diffraction grating 71, the incident light 72 is reflected and diffracted. At this time, the grating pitch of the diffraction grating 71 is P, the wavelength of the incident light 72 is λ, the incident angle (the angle made with the normal to the diffraction grating 71) is θ _i , and the normal of the diffraction grating 71 of the n-th order reflected diffraction light. When angle a (exit angle) theta _n and _{Psinθ i -Psinθ n = nλ (n} = 0, ± 1, ± 2, ···) becomes · · · · · (a1). From this, the exit angle θ _n is

[0067]

(Equation 1) Given by

For example, λ = 0.780 μm, θ _i = 17
Degrees, P = 3 μm, θ ₀ = θ _i = 17 degrees θ ₂ = −13.1575 degrees

Here, the sign of the exit angle θ ₂ is minus because the reflected and diffracted light is diffracted toward the incidence side with respect to the normal line of the diffraction grating 71 at an angle of 13.1575 degrees with respect to the normal line as shown in FIG. Means. The sensor 26 in FIG. 9 detects the diffracted light 75 at this time.

Next, a method for detecting the positional relationship between the light beam and the alignment mark 50 in this embodiment will be described.

In the configuration shown in FIG. 6, a light beam is incident on one of the cross marks 20 shown in FIG. 7, for example, the center of the cross mark 20R from the light source 27 installed in the alignment head (optical head) 14. This light beam is shown in FIG.
The light beam 24 is incident on a positioning pattern 20a like a light beam 24 shown in FIG.

At this time, even if the mask 23 is moved in the X direction, since the size of the pattern 20a is large, the incident area of the light beam 24 is within the diffraction grating, so that the sensor shown in FIG. The position of incidence on 26 is unchanged. The position of the light spot image 24a on the surface of the sensor 26 at this time is set as a reference position.

[0073] then allowed incident alignment head 14 a predetermined amount y ₀ upward in the Y direction, or by moving downward a light beam to the pattern 20b of the cross mark 20R. At this time, if the relative positions of the alignment head 14 and the mask 23 match, the diffracted light enters the central position on the surface of the sensor 26 as a light spot image 24a.

However, if there is a displacement .DELTA.X in the X direction as shown in FIG. 8B, the light beam deviates from the center of the pattern 20b, so that the median value of the diffracted light incident on the surface of the sensor 26 is as shown in the light spot image 25c. It breaks.

(Note that the predetermined amount y of the alignment head 14 is
The moving direction of ₀ may be either the upward direction or the downward direction, but measurement is performed by moving in the vertical direction, and if averaging is performed, other error components such as rotation of the mask 23 can be reduced and highly accurate evaluation can be performed. It is preferred. The displacement detected at this time is used as the displacement between the alignment head 14 and the mask 23, and the alignment head 14 is moved to the median value of the sensor 26, whereby the position is aligned in the X direction with the accuracy of the pitch resolution of the sensor 26. Has been realized.

Finally, the alignment head 14 is moved by a known amount to a predetermined position of the alignment mark 50 which is displaced from the positioning cross pattern 20 which has been positioned with the light beam by a known amount. The beam is positioned on the alignment pattern 50.

Thereafter, a light beam is made incident on the alignment pattern 50, and relative positioning between the mask 23 and the wafer 19 is performed by utilizing the diffracted light passing through the light beam.
The method at this time is substantially the same as the method disclosed in Japanese Patent Application No. 2-143869, for example.

Next, the configuration of FIG. 6 will be described.

The light beam from the light source 27 is incident on the lens system 5 as a parallel light beam by the collimator lens 2.
The lens system 5 converts the incident light beam into a desired beam diameter, reflects the light beam on a mirror 6, and sets the Xray-resistant window 7 (X as an exposure light source).
AA alignment mark (hereinafter, referred to as “AA mark”) for detecting a positional deviation as an alignment pattern 50 on the surface of the mask 23 as a first object after passing through (when a ray is used), or an AF for detecting a surface interval. The light is incident on an alignment mark (hereinafter, referred to as an “AF mark”).

The AA mark and the AF mark are provided at four places on the scribe line around the mask 23.
Reference numeral 19 denotes a wafer as a second object, which is arranged close to the mask 23 (at an interval of 10 μm to 100 μm), and an AA mark to be aligned with the mask 23 is provided on a scribe line on its surface. AA mark and AF
The mark is composed of a physical optical element such as a one-dimensional or two-dimensional zone plate.

Reference numeral 10 denotes a light receiving lens, which condenses diffracted light 16 of a predetermined order passing through the AA mark and the AF mark on the surface of the mask 23 on the surface of the light receiving means 11. The light receiving means 11 is configured by providing two line sensors, an AA line sensor 12 for detecting a displacement and an AF line sensor 13 for detecting a surface interval, on the same substrate.

Then, as disclosed in Japanese Patent Application No. 2-143869, the relative displacement between the mask 23 and the wafer 19 is detected using the output signal from the AA line sensor 12, and Is used to detect the surface distance between the mask 23 and the wafer 19.

When the relative positioning between the mask 23 and the wafer 19 is completed, the circuit pattern on the mask 23 is exposed to light from an illumination system (not shown).
It is transferred onto a surface, and then a semiconductor device is obtained through a known process.

FIGS. 11A and 11B show a third embodiment of the present invention.
It is explanatory drawing of the cross mark 20 (diffraction grating pattern) on the surface of the sensor 31 and a mask which concerns on the position detection method of FIG. 8, the configuration of the cross mark 20 and the sensor 31 and the alignment direction are different from those of the second embodiment in FIG.

The left and right patterns 28a of the cross mark 20 in FIG.
Direction is smaller than the beam diameter. The dimension of the central pattern 28b in the Y direction is larger than the beam diameter of the light beam 29 in the Y direction. In the figure, the light beam is positioned in the Y direction. One-dimensional sensor 31
Performs detection in the Y direction.

FIG. 12 shows the light source 3 on the cross mark 20 in FIG.
The light beam from the light source 2 enters and is reflected and diffracted, and the sensor 31
FIG. 4 is an explanatory view showing a state where light is incident on the light source.

In this embodiment, if the light beam 29 is incident on the center of the cross mark 20, a light spot image 29 is formed at the center on the sensor 31 surface. At this time, even if the mask 23 is moved in the Y direction, the position of the light spot image 29a generated at the center on the surface of the sensor 31 does not change.

At this time, the alignment head 14 is moved to one side in the X direction with the position of the light spot image 29a as a reference, and the light beam 30 is made incident on the pattern 28a. Then, the displacement of the light spot image on the sensor 31 is detected.

At this time, when the light beam comes to a position deviated from the center of the pattern 28a like the light beam 30, the center of light quantity of the light spot image 30a on the surface of the sensor 31 is shifted from the center. The driving of the alignment head 14 in the Y direction is controlled using the displacement signal from the sensor 31 obtained at this time. Thus, the relative positioning of the alignment head 14 and the mask 23 in the Y direction is performed with an accuracy of about 1 μm.

In this embodiment, the positioning in the X direction is performed by the method of the second embodiment, and the positioning in the Y direction is performed by the method of the third embodiment.
The positioning between the light beam and the alignment pattern may be performed in two directions orthogonal to each other. Further, in order to avoid interference between the two sensors for the X direction and the Y direction at this time, diffracted lights of different orders among the diffracted lights from the cross mark 20 may be used for each sensor.

FIGS. 13A and 13B show a fourth embodiment of the present invention.
FIG. 6 is an explanatory diagram of a sensor 38 and a deformed cross mark 34 on a mask according to the position detection method of FIG.

In the present embodiment, the sensor 38 is formed of a two-dimensional sensor.
4 is different from the second embodiment in FIG.

The cross mark 34 has a longer left and right projection pattern, a two-stage width in the Y direction, and a tip pattern 34a having a width in the Y direction of about 50 μm.

FIG. 14 shows the light source 3 on the cross mark 34 in FIG.
The light beam from the light source 9 is reflected and diffracted by the sensor 38.
FIG. 4 is an explanatory view showing a state where light is incident on the light source.

In this embodiment, if the positioning of the light beam from the light source 39 with the light beam from the alignment head 14 and the alignment pattern on the mask surface has been completed, the light beam from the light source 39 shown in FIG.
As shown in FIG. 3 (B), the light beam 3
Inject as shown in FIG.

Assuming that the mask can be moved in the X direction and the Y direction, even if the mask is moved within a range of ± 400 μm in the X direction, the position of the light spot 35a diffracted from the cross mark 34 incident on the surface of the sensor 38 changes. do not do. At this time, the center of the light spot 35a on the surface of the sensor 38 is the reference position.

When the mask is moved by Y _{0 in the} Y direction from the position of the light beam 35, the light spot on the surface of the sensor 38 is shifted in the X direction according to the amount of shift between the pattern and the light beam in the X direction. Move to position.

Next, the mask is moved by X ₀ in the X direction from the position of the light beam 35, so that the light beam 37 is incident on the pattern 34a having the narrow cross mark 34. At this time, if the light beam 37 is shifted from the center in the Y direction, the light spot on the surface of the sensor 38 moves to the position of the light spot 37a with respect to the shift amount in the Y direction.

The sensor 38 is operated by a series of such operations.
The amount of deviation of the median value of the light spot on the surface from the reference value is detected in the X and Y directions.

In this embodiment, the two-dimensional image sensor 1
When the mask driving unit controls the driving of the mask by using the shift amount in the X direction and the Y direction from 8 as a signal, positioning in the X direction and the Y direction can be performed with the same accuracy as in the second and third embodiments.

Further, this embodiment is characterized in that only one alignment mark on the scribe line is required. That is, in the second and third embodiments, two patterns are required in the X direction and the Y direction, and the positioning step requires two positioning operations, and two light sources and two image sensors are required.

On the other hand, in this embodiment, the displacement in the X direction and the Y direction can be detected with one deformed cross mark, and only one process is required, so that the two-dimensional image sensor and the pattern can be detected at one corner. There is a feature that only one pair is required.

[0103]

According to the present invention, an alignment pattern for a light beam as described above is provided on the first object plane, and a light beam is incident on the alignment pattern from a light projecting means (alignment head). A position detection method and an exposure apparatus using the same that use diffraction light of a predetermined order generated from the alignment pattern to appropriately set a positional relationship between a light projecting unit (alignment head) and a first object. can do.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of a position detection method according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship among a light projecting unit, a light receiving unit, and a positioning pattern according to the present invention.

FIG. 3 is an explanatory diagram of a pattern according to the position detection method according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of an optical system according to a first embodiment of the present invention.

FIG. 5 is an explanatory diagram of a light spot on a sensor surface according to the first embodiment of the present invention.

FIG. 6 is a schematic diagram of a main part of a part of an exposure apparatus according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram on a mask surface according to a second embodiment of the present invention;

FIG. 8 is an explanatory diagram of an alignment pattern, a cross mark, and a sensor according to the second embodiment of the present invention.

FIG. 9 is an explanatory diagram of an optical system according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram of diffracted light diffracted by a diffraction grating.

FIG. 11 is an explanatory diagram of a pattern and a sensor according to a position detection method according to a third embodiment of the present invention.

FIG. 12 is an explanatory diagram of an optical system according to a third embodiment of the present invention.

FIG. 13 is an explanatory diagram of a pattern and a sensor according to a position detection method according to a fourth embodiment of the present invention.

FIG. 14 is an explanatory diagram of an optical system according to a fourth embodiment of the present invention.

FIG. 15 is an explanatory view of a conventional alignment pattern on a mask surface.

16 is an explanatory diagram of the alignment pattern of FIG.

FIG. 17 is an explanatory diagram of a sensor output signal obtained by a conventional position detection method.

[Explanation of symbols]

 1000 Substrate (mask) 1001, 1002 Diffraction grating pattern 1003 Alignment pattern 1004, 1005, 1006 Light beam 1007 Light source 1008 Sensor 20 Cross mark 23 Mask 24 Light beam 26, 31 Sensor 27, 32 Light source 50 Alignment pattern

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-78005 (JP, A) JP-A-64-76022 (JP, A) JP-A-61-124131 (JP, A) JP-A-2- 238308 (JP, A) JP-A-4-36605 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/027

Claims (10)

(57) [Claims] 1. A position detection method for irradiating a substrate with a light beam and detecting a position of an optical head for receiving the light beam from the substrate in a predetermined direction with respect to the substrate, wherein the substrate is provided on the substrate. By forming a diffraction grating pattern having a width in the direction smaller than the width of the light beam in the direction above, the diffraction grating pattern is changed in accordance with a positional shift in the direction of the light beam and the diffraction grating pattern. The incident position of the diffracted light of a predetermined order resulting from the light incident on the sensor in the optical head is changed, and the light beam is irradiated on the diffraction grating pattern to generate the diffracted light of the predetermined order. Is incident on the sensor in the optical head, the incident position of the predetermined order diffracted light on the sensor is detected, A position detecting method comprising: detecting a position of the optical head based on a deviation of a detected incident position from a predetermined position. 2. A reference diffraction grating pattern having a width in the direction, which is sufficiently larger than the width of the light beam in the direction on the substrate, is formed on the substrate, and the light in the reference diffraction grating pattern is formed in the reference diffraction grating pattern. By irradiating a beam, a reference diffracted light is generated in substantially the same direction as the predetermined order diffracted light, and the reference diffracted light is incident on the sensor.
Detecting the incident position of the reference diffraction light on the sensor,
2. The position detecting method according to claim 1, wherein the detected incident position is set as the predetermined position. 3. A substrate is irradiated with a light beam, a position of an optical head for receiving the light beam from the substrate in a predetermined direction with respect to the substrate is detected, and the optical head is mounted on the substrate based on the detection. In a positioning method for positioning at an arbitrary position with respect to the substrate, by forming a diffraction grating pattern having a width in the direction smaller than the width in the direction of the light beam on the substrate on the substrate, The incident position of a predetermined order of diffracted light generated from the diffraction grating pattern on a sensor in the optical head is changed in accordance with the positional deviation of the light beam and the diffraction grating pattern in the direction, and the diffraction of the light beam is performed. By irradiating the grating pattern with the predetermined order diffracted light, the predetermined order diffracted light is detected by a sensor in the optical head. And detecting an incident position of the diffracted light of the predetermined order on the sensor, and detecting a position of the optical head based on a deviation of the detected incident position from a predetermined position. And positioning method. 4. A reference diffraction grating pattern having a width in the direction that is sufficiently larger than the width of the light beam in the direction on the substrate is formed on the substrate, and the light is included in the reference diffraction grating pattern. By irradiating a beam, a reference diffracted light is generated in substantially the same direction as the predetermined order diffracted light, and the reference diffracted light is incident on the sensor.
Detecting the incident position of the reference diffraction light on the sensor,
4. The method according to claim 3, wherein the detected incident position is set as the predetermined position. 5. A zone plate pattern for positioning is formed at a predetermined distance from the diffraction grating pattern on the substrate in a predetermined direction, and the center of the light beam is moved to the zone plate by the optical head. 4. The positioning method according to claim 3, wherein the optical head is positioned so as to hit a predetermined portion of the pattern. 6. The positioning device according to claim 5, wherein said substrate is formed of a mask on which a circuit pattern is formed, and wherein said diffraction grating pattern and said zone plate pattern are formed in a peripheral portion of said circuit pattern. Method. 7. The optical head directs the light beam to the mask along an incident light path inclined with respect to the surface of the mask, and the optical head is inclined with respect to the surface of the mask on the same side as the incident light path. Receiving the light beam emitted from the mask along at least one emission optical path, wherein the diffraction grating pattern is configured such that the diffraction light of the predetermined order is emitted from the mask along the emission optical path. 7. The positioning method according to claim 6, wherein the positioning is performed. 8. A mask is irradiated with a light beam along an incident optical path inclined with respect to the surface of the mask, and at least one inclined from the mask to the same side as the incident optical path with respect to the surface of the mask. An optical head that receives the light beam emitted along an emission optical path detects a position in a predetermined direction with respect to the mask, and based on the detection, positions the optical head with respect to a zone plate pattern of the mask. Irradiating the light beam onto the zone plate mark of the wafer via the zone plate pattern of the mask, and transmitting the signal light affected by the zone plate pattern and the zone plate mark along the emission optical path. The optical head receives the signal light, and the signal light is used to shift the position of the mask and the wafer. And after aligning the mask and the wafer according to the detection, exposing the wafer through the circuit pattern of the mask, and transferring the circuit pattern of the mask onto the wafer, thereby manufacturing a semiconductor device. In the manufacturing method, by forming a diffraction grating pattern having a width in the direction smaller than the width of the light beam on the mask in the direction on the mask, the light beam and the diffraction grating pattern are formed. By changing the position of incidence of a predetermined order of diffracted light generated from the diffraction grating pattern on a sensor in the optical head in accordance with the displacement in the direction, and irradiating the diffraction grating pattern with the light beam, A predetermined order diffracted light is generated along the emission optical path, and the predetermined order diffracted light is generated in the optical head. Incident on a sensor, detecting an incident position of the diffracted light of the predetermined order on the sensor, and detecting a position of the optical head based on a deviation of the detected incident position from a predetermined position. Manufacturing method of a semiconductor device. 9. A reference diffraction grating pattern having a width in the direction that is sufficiently larger than a width in the direction of the light beam on the mask is formed on the mask;
By irradiating the light beam in the reference diffraction grating pattern, reference diffraction light is generated in substantially the same direction as the diffraction light of the predetermined order, the reference diffraction light is incident on the sensor, and the reference diffraction light is applied to the sensor. 9. The method according to claim 8, wherein an incident position of the reference diffracted light is detected, and the detected incident position is set as the predetermined position. 10. A mask is irradiated with a light beam along an incident optical path inclined with respect to the surface of the mask, and at least one inclined from the mask to the same side as the incident optical path with respect to the surface of the mask. An optical head for receiving the light beam emitted along an emission optical path; and at least one of the optical head for detecting a position of the optical head with respect to the mask in a predetermined direction and a position of the wafer with respect to the mask. Detecting means for receiving outputs from the two sensors, means for positioning the optical head with respect to the zone plate pattern of the mask based on the detection by the detecting means, and the mask and the wafer based on the detection by the detecting means Means for positioning the light beam through the zone plate pattern of the mask. And exposing the light beam to the zone plate mark of the wafer to receive signal light emitted along the emission optical path under the action of the zone plate pattern and the zone plate mark. In the apparatus, the mask is smaller than a reference diffraction grating pattern having a width in the direction sufficiently larger than the width of the light beam on the mask in the direction and a width of the light beam on the mask in the direction. A diffraction grating pattern having a small width in the direction is formed, and a predetermined order of diffracted light generated from the diffraction grating pattern in the optical head in accordance with the displacement of the light beam and the diffraction grating pattern in the direction is formed in the optical head. The incident position on the sensor is set to change, the optical head, By irradiating the light beam into the reference diffraction grating pattern, the sensor receives reference diffraction light generated along the emission optical path, and outputs a first signal corresponding to the incident position of the reference diffraction light. Irradiating the diffraction grating pattern with the light beam and receiving the diffracted light of the predetermined order generated along the emission optical path by the sensor, outputting a second signal corresponding to the incident position, and performing the detection. An exposure apparatus, wherein means detects a position of the optical head in the direction with respect to the mask using the first and second signals.