JP5093759B2 - Displacement detection apparatus, exposure apparatus, and device manufacturing method - Google Patents

Description

  The present invention relates to a displacement detection apparatus, an exposure apparatus, and a device manufacturing method. More specifically, the present invention relates to an apparatus for optically detecting a displacement of a surface position of a surface to be measured.

  In JP-A-4-366711, light from a light source is projected onto a test surface via an objective lens, and the surface position of the test surface (based on reflected light from the test surface via the objective lens ( A displacement detector that detects a displacement at a position along the normal direction of the surface to be measured is described. Specifically, in the displacement detection device disclosed in this publication, a laser beam is condensed on a test surface through an objective lens, and light reflected by the test surface and passed through the objective lens is received by a four-divided sensor. To do. Then, using the astigmatism method, the displacement of the surface position of the test surface is detected based on the output signal of the quadrant sensor.

JP-A-4-366711

  When detecting the displacement of the surface position of the back surface of the glass substrate using the displacement detection device disclosed in Patent Document 1, for example, a relatively large detection error occurs due to the influence of foreign matter (dust etc.) adhering to the surface. There are things to do.

  The present invention has been made in view of the above-described problems. For example, the displacement detection device can suppress the influence of a foreign matter attached to the surface of a glass substrate and can detect the displacement of the surface position of the back surface with high accuracy. The purpose is to provide.

In order to solve the above-described problem, in the first embodiment of the present invention, in the displacement detection device for detecting the displacement of the surface position of the test surface
The first to third light beams for guiding the first to third light beams to the first to third positions of the test surface to form first to third condensing points at or near the test surface, respectively. An optical system common to the third light;
First to third displacement information at the first to third positions is detected based on the first to third lights reflected from the test surface, respectively, and the most similar among the three displacement information. And a detection system that detects the displacement of the surface position of the test surface based on the two pieces of displacement information.

  According to a second aspect of the present invention, there is provided an exposure apparatus comprising the displacement detection device of the first aspect and exposing a predetermined pattern onto a photosensitive substrate.

In the third embodiment of the present invention, using the exposure apparatus of the second embodiment, an exposure step of exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate to which the predetermined pattern is transferred, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

  In the displacement detection device of the present invention, the first to third lights are respectively guided to the first to third positions of the test surface by the common optical system, and the first to third lights are placed on or near the test surface. A condensing point is formed. Then, the first to third displacement information at the first to third positions is detected based on the first to third light reflected by the test surface, and the most similar among these three displacement information. The displacement of the surface position of the test surface is detected based on the two pieces of displacement information.

  Therefore, for example, when detecting the displacement of the surface position of the back surface of the glass substrate, even if the foreign matter adheres to any one of the regions through which the first to third light passes on the front surface, The displacement of the surface position of the back surface of the glass substrate can be detected based on the two pieces of displacement information obtained by the two lights not affected by the above. In other words, the displacement detection device of the present invention can detect the displacement of the surface position of the back surface with high accuracy, for example, while suppressing the influence of foreign matter adhering to the surface of the glass substrate.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically showing a configuration of a displacement detection device according to an embodiment of the present invention. In the present embodiment, the present invention is applied to a displacement detection device that detects the displacement of the surface position of the back surface of the glass substrate using the astigmatism method. In FIG. 1, the Z-axis is in the normal direction of the back surface 20a of the glass substrate 20, the Y-axis is in the direction parallel to the paper surface of FIG. 1 in the back surface 20a, and the X-axis is in the direction perpendicular to the paper surface of FIG. Each is set.

  Referring to FIG. 1, the displacement detection device of the present embodiment includes, for example, a light source LS such as a laser diode and light from the light source LS on the back surface (surface opposite to the device side) 20a of the glass substrate 20. An irradiation optical system IL for condensing light and a detection system DS for detecting the displacement of the surface position of the back surface 20a based on the light reflected by the back surface 20a, which is the test surface. The irradiation optical system IL includes a collimating lens 1, a grating 2, a polarization beam splitter 3, a quarter wavelength plate 4, and an objective lens 5 in the order of incidence of light from the light source LS.

  The detection system DS includes an objective lens 5, a quarter wavelength plate 4, a polarizing beam splitter 3, a condensing lens 6, a cylindrical lens 7, and light in the order of incidence of reflected light from the back surface 20a of the glass substrate 20. And a detector 8. In addition, the detection system DS includes a signal processing unit 9 connected to the light detection unit 8. In the displacement detection device of the present embodiment, the light source LS supplies light in the s-polarized state to the polarization separation surface 3a of the polarization beam splitter 3, for example. The light emitted from the light source LS enters the grating 2 through the collimator lens 1.

  The 0th-order diffracted light L1, the + 1st-order diffracted light L2, and the −1st-order diffracted light L3 generated by the diffraction action of the grating 2 are incident on the polarization beam splitter 3. In FIG. 1 and related FIGS. 5 and 6, the 0th-order diffracted light L1 generated by the grating 2 is indicated by a solid line, the + 1st-order diffracted light L2 is indicated by a two-dot chain line, and the −1st-order diffracted light L3 is indicated by a broken line. The three s-polarized light beams L 1, L 2, and L 3 incident on the polarization beam splitter 3 are reflected by the polarization separation surface 3 a and emitted from the polarization beam splitter 3, and then enter the quarter wavelength plate 4.

  The three lights L1, L2, and L3 converted into the circularly polarized state through the quarter wavelength plate 4 enter the surface 20b of the glass substrate 20 through the objective lens 5. The three lights L1, L2, and L3 incident on the front surface 20b propagate through the inside of the glass substrate 20 and then enter the back surface 20a. The three lights L1, L2, and L3 reflected by the back surface 20a propagate through the glass substrate 20, are emitted from the front surface 20b, and then enter the objective lens 5.

  In the present embodiment, the three lights L1, L2, and L3 generated by the grating 2 form a condensing point on the back surface 20a that is the test surface or in the vicinity thereof. Hereinafter, in order to simplify the description, it is assumed that the three light beams L1, L2, and L3 form condensing points at different positions on the back surface 20a. The three reflected lights L1, L2, and L3 that pass through the objective lens 5 are converted into the p-polarized state via the quarter-wave plate 4 and then enter the polarization beam splitter 3. The three p-polarized reflected lights L1, L2, and L3 incident on the polarization beam splitter 3 pass through the polarization separation surface 3a, exit from the polarization beam splitter 3, and then enter the condenser lens 6.

  The three reflected lights L1, L2, and L3 that pass through the condenser lens 6 reach the light detection unit 8 via the cylindrical lens 7 that has positive refractive power in the XZ plane and has no refractive power in the YZ plane. The cylindrical lens 7 has a function of generating astigmatism in the three reflected lights L1, L2, and L3 that have passed through the polarization beam splitter 3. The cylindrical lens 7 can also be disposed on the front side of the condenser lens 6 (on the side of the polarization beam splitter 3). As shown in FIG. 2, the light detection unit 8 includes three four-divided sensors 81, 82, and 83 arranged at intervals along the Y direction. Further, for example, when the light source LS itself has necessary and sufficient astigmatism, the cylindrical lens 7 may be omitted. As such a light source LS, a laser diode can be used.

  The center quadrant sensor 81 is positioned so as to receive the 0th-order diffracted light L1 generated by the grating 2, and for example, a linear region extending in a direction that forms 45 degrees with the + X direction and the + Y direction, the + X direction, and the -Y direction. It has four light receiving parts 81a, 81b, 81c, 81d equally divided by a linear region extending in the direction and 45 degrees. In other words, the four light receiving portions 81 a, 81 b, 81 c, 81 d are arranged point-symmetrically with respect to the center point of the four-divided sensor 81.

  The four-divided sensor 82 on the left side in FIG. 2 is positioned so as to receive the + 1st order diffracted light L2, and has four light receiving portions 82a, 82b, 82c, and 82d that are arranged point-symmetrically like the four-divided sensor 81. The right quadrant sensor 83 in FIG. 2 has four light receiving portions 83a, 83b, 83c, and 83d that are positioned so as to receive the −1st-order diffracted light L3 and are arranged point-symmetrically in the same manner as the quadrant sensor 81. . The output of the light detection unit 8, that is, the output signals S 1, S 2, S 3 of the four-divided sensors 81, 82, 83 are supplied to the signal processing unit 9.

  First, in order to facilitate understanding of the operation of the displacement detection apparatus of the present embodiment, an operation in a normal configuration example using the astigmatism method (hereinafter referred to as “comparative example”) will be described. In the comparative example, the installation of the grating 2 is omitted from the configuration of FIG. As a result, the number of lights forming a condensing point on the back surface 20a that is the test surface or in the vicinity thereof is one, and the number of the four-divided sensors provided in the light detection unit 8 is also one corresponding to this. It is. Hereinafter, the single light corresponding to the above-described 0th-order diffracted light L1 is reflected by the back surface 20a of the glass substrate 20 so that the operation of the comparative example can be understood with reference to FIG. It is assumed that a single quadrant sensor 84 corresponding to 81 is reached (see FIG. 3).

  In the comparative example, when the back surface 20a of the glass substrate 20 is at a predetermined position (for example, the focal position of the objective lens 5) in the optical ideal state, the reflected light from the back surface 20a is 4 as shown in the center of FIG. In the divided sensor 84, a circular light distribution 84e centering on the center point of the four light receiving portions 84a to 84d is formed. When the back surface 20a of the glass substrate 20 moves in the Z direction from the predetermined position, the light distribution formed in the quadrant sensor 84 by the action of the cylindrical lens 7 as an aberration generating member is the moving direction (+ Z of the back surface 20a). Direction or -Z direction) and the amount of movement along the Z direction, as shown schematically by reference numerals 84ea and 84eb on the left and right sides of FIG. 3, the vicinity of the center point of the four light receiving portions 84a to 84d It changes to an elliptical shape with the center.

The output signal S of the quadrant sensor 84 is expressed by the following equation (1). In the formula (1), Sa is a value corresponding to the received light amount of the light receiving unit 84a, and Sb is a value corresponding to the received light amount of the light receiving unit 84b adjacent to the light receiving unit 84a. Sc is a value corresponding to the amount of light received by the light receiving portion 84c facing the light receiving portion 84a, and Sd is a value corresponding to the amount of received light of the light receiving portion 84d facing the light receiving portion 84b. The same applies to the output signals S1, S2, S3 of the quadrant sensors 81, 82, 83 in the present embodiment.
S = (Sa + Sc)-(Sb + Sd) (1)

  A relationship as shown in FIG. 4 is established between the output signal S of the quadrant sensor 84 expressed by the equation (1) and the displacement D of the surface position of the back surface 20a of the glass substrate 20. In FIG. 4, the horizontal axis represents the displacement D, and the vertical axis represents the output signal S of the quadrant sensor 84. The S-shaped line (S curve) representing the relationship between the output signal S and the displacement D has high linearity in a predetermined range centered on the origin (point of S = D = 0).

  In the signal processing unit 9 to which the output signal S of the quadrant sensor 84 is supplied, the movement direction (that is, the sign of the displacement D) of the back surface 20a of the glass substrate 20 is obtained based on the sign of the change amount of the output signal S, and the output signal Based on the absolute value of the amount of change in S, the amount of movement along the Z direction of the back surface 20a of the glass substrate 20 (that is, the absolute value of the displacement D) is obtained. Specifically, the signal processing unit 9 determines the sign and absolute value of the displacement D of the surface position of the back surface 20a from the initial state where the output signal S of the quadrant sensor 84 is zero, for example, as the output signal of the quadrant sensor 84. Calculation is based on the sign and absolute value of S.

  In the comparative example, foreign matter (dust) as indicated by reference numeral 21 in FIG. 1 is formed in a region where the incident light beam on the back surface 20a of the glass substrate 20 passes through the front surface 20b or a region where the light beam emitted from the back surface 20a passes through the front surface 20b. If a water droplet or the like is attached, the light reaching the four-divided sensor 84 is affected by the foreign material 21, and a detection error occurs.

  In the present embodiment, as clearly shown in FIG. 5, the three light beams L1, L2, and L3 generated by the grating 2 are different from each other on the surface 20b of the glass substrate 20 via the objective lens 5. After passing through R2 and R3, condensing points are formed at different positions P1, P2 and P3 on the back surface 20a. The three lights L1, L2, and L3 reflected by the back surface 20a pass through the regions R1, R2, and R3 on the front surface 20b again, pass through the objective lens 5, and finally differ from each other into four-divided sensors 81 and 82. , 83 is reached.

  Thus, the quadrant sensor 81 obtains the displacement information of the surface position at the first position P1 based on the first light L1 reflected at the first position P1 on the back surface 20a. In the quadrant sensor 82, displacement information of the surface position at the second position P2 is obtained based on the second light L2 reflected at the second position P2 on the back surface 20a. In the quadrant sensor 83, displacement information of the surface position at the third position P3 is obtained based on the third light L3 reflected at the third position P3 on the back surface 20a.

  Therefore, for example, as shown in FIG. 1, when the foreign matter 21 is attached to the passage region R3 of the third light L3 on the surface 20b of the glass substrate 20 (strictly, at least a part of the foreign matter 21 is in the passage region R3. The displacement information obtained by the four-divided sensor 83 is influenced by the foreign substance 21, and is substantially different from the displacement information obtained by the four-divided sensor 81 and the displacement information obtained by the four-divided sensor 82. become.

  Specifically, for example, as shown in FIG. 2, the light distribution 81e formed by the first light L1 on the quadrant sensor 81 and the light distribution 82e formed by the second light L2 on the quadrant sensor 82 are similar to each other. However, the light distribution 83e formed by the third light L3 on the quadrant sensor 83 is substantially different from the light distributions 81e and 82e. In other words, the output signal S1 of the quadrant sensor 81 and the output signal S2 of the quadrant sensor 82 have values similar to each other, but the output signal S3 of the quadrant sensor 83 is substantially different from the output signals S1 and S2. It becomes a different value. In this case, the signal processing unit 9 detects that the output signal S3 is affected by the foreign matter 21 by comparing the output signals S1, S2, and S3, and based on the output signals S1 and S2, the glass substrate The displacement D of the surface position of the back surface 20a of 20 is calculated.

  More specifically, for example, the offset X2 of the origin of the S curve of the quadrant sensor 82 and the offset X3 of the origin of the S curve of the quadrant sensor 83 are set in advance with respect to the origin of the S curve of the quadrant sensor 81 serving as the center reference. Ask. Further, the slope (linearity) of the S curve in a predetermined range centered on the origin of the S curve of the quadrant sensor 81 is obtained in advance by measurement, for example, as a change rate K1 of the signal S1 with respect to a change in the surface position. Similarly, the slope of the S curve in a predetermined range centered on the origin of the S curve of the four-divided sensors 82 and 83 is obtained in advance, for example, by measurement as the rate of change K2 and K3 of the signals S2 and S3 with respect to the change in the surface position.

Thus, the surface position displacement measurement values D1, D2, and D3 at the positions P1, P2, and P3 on the back surface 20a are based on the signals S1, S2, and S3 obtained by the four-divided sensors 81, 82, and 83. It calculates | requires by Formula (2)-(4).
D1 = S1 × K1 (2)
D2 = (S2 + X2) × K2 (3)
D3 = (S3 + X3) × K3 (4)

  Output signals S1, S2, and S3 of the four-divided sensors 81, 82, and 83 are expressed by the following equations (1a), (1b), and (1c), respectively. In Expression (1a), S1a is a light receiving unit 81a, S1b is a light receiving unit 81b, S1c is a light receiving unit 81c, and S1d is a value corresponding to the amount of light received by the light receiving unit 81d. In Expression (1b), S2a is a light receiving portion 82a, S2b is a light receiving portion 82b, S2c is a light receiving portion 82c, and S2d is a value corresponding to the amount of light received by the light receiving portion 82d. In Expression (1c), S3a is a light receiving unit 83a, S3b is a light receiving unit 83b, S3c is a light receiving unit 83c, and S3d is a value corresponding to the amount of light received by the light receiving unit 83d.

S1 = (S1a + S1c) − (S1b + S1d) (1a)
S2 = (S2a + S2c)-(S2b + S2d) (1b)
S3 = (S3a + S3c)-(S3b + S3d) (1c)

  The signal processing unit 9 compares | D1-D2 |, | D1-D3 |, and | D2-D3 |, and selects a combination of displacement measurement values that minimizes the value. Then, for example, an average value (Di + Dj) / 2 of the two selected displacement measurement values Di and Dj is obtained as the displacement D of the surface position of the back surface 20a that is the test surface. When the foreign matter 21 is attached to the third light L3 passage region R3, the value of | D1-D2 | is minimized, so the surface position calculated based on the signal S1 obtained by the four-divided sensor 81 An average value (D1 + D2) / 2 of the measured displacement value D1 of the above and the measured displacement value D2 of the surface position calculated based on the signal S2 obtained by the quadrant sensor 82 is obtained as the displacement D.

  As described above, in the present embodiment, the three lights L1, L2, and L3 generated by the grating 2 are placed at different positions on the back surface 20a of the glass substrate 20 by the common optical system (3, 4, 5). They are led to P1, P2, and P3, respectively, and condensing points are formed at positions P1, P2, and P3, respectively. Then, based on the three lights L1, L2, and L3 reflected at positions P1, P2, and P3 on the back surface 20a, displacement measurement values D1, D2, and D3 are detected as displacement information at the positions P1, P2, and P3, respectively. The displacement D of the surface position of the back surface 20a is detected based on the two most similar displacement information among the three displacement information D1, D2 and D3.

  Therefore, even if the foreign material 21 adheres to any one of the regions R1, R2, and R3 through which the three lights L1, L2, and L3 pass on the surface 20b of the glass substrate 20, the influence of the foreign material 21 is affected. The displacement D of the surface position of the back surface 20a of the glass substrate 20 can be detected based on the two displacement information obtained by the two lights not received. In other words, in the displacement detection device of the present embodiment, it is possible to detect the displacement D of the surface position of the back surface 20a with high accuracy while suppressing the influence of the foreign matter 21 attached to the front surface 20b of the glass substrate 20.

In the present embodiment, it is assumed that the distance between the centers of two light beams adjacent to each other on the surface 20b of the glass substrate 20 adheres to the diameters of the passage regions R1, R2, and R3 of the light beams on the surface 20b and the surface 20b. By setting it to be larger than the sum of the diameter of the foreign matter 21, the two lights are not affected by the foreign matter 21 at the same time, and the detection accuracy can be improved reliably. That is, in order to prevent one foreign substance from affecting only one quadrant sensor, it is necessary to satisfy the following conditional expression (5).
p> 2 × NA × t / n + d (5)

  In conditional expression (5), p is the distance between the centers of two adjacent light beams on the surface 20b of the glass substrate 20, as shown in FIG. NA is the numerical aperture of the objective lens 5, t is the thickness (dimension in the Z direction) of the glass substrate 20, and n is the refractive index of the optical material forming the glass substrate 20. d is the diameter of the foreign material 21. In other words, the conditional expression (5) indicates that the distance p between the centers of two light beams adjacent to each other on the surface 20b of the glass substrate 20 is a diameter of a circle circumscribing the light beam passage regions R1, R2, and R3 on the surface 20b (= 2 × NA × t / n) and the maximum value d of the diameter of a circle circumscribing the foreign material 21 that is supposed to adhere to the surface 20b.

  In the above-described embodiment, the cylindrical lens 7 as an aberration generating member that generates astigmatism in the three lights L1, L2, and L3 that have passed through the polarization beam splitter 3, and three reflections from the back surface 20a of the glass substrate 20. By using three four-divided sensors 81 to 83 as photoelectric conversion units that photoelectrically convert the light L1, L2, and L3, respectively, the displacement of the surface position of the back surface 20a that is the test surface is detected by the astigmatism method. Yes. However, the present invention is not limited to the astigmatism method, and the present invention is applied to a displacement detection device that detects the displacement of the surface position of the surface to be measured using, for example, a knife edge method or a critical angle method. Can do.

  Hereinafter, with reference to FIG. 6 and FIG. 7, a configuration example of a displacement detection device that detects displacement of the surface position of the back surface of the glass substrate by the knife edge method will be described. The modification of FIG. 6 has a configuration similar to that of the embodiment of FIG. 1, but a light shielding member 10 is used instead of the cylindrical lens 7, and three two-divided sensors 91-91 are substituted for the three four-divided sensors 81-83. 1 is different from the embodiment of FIG. Hereinafter, the configuration and operation of the modified example of FIG. 6 will be described with a focus on differences from the embodiment of FIG.

  In the modification of FIG. 6, three reflected lights L1, L2, and L3 that have passed through the condenser lens 6 are incident on the light shielding member 10. The light shielding member 10 has an edge 10a extending in the Y direction perpendicular to the optical axis AX of the apparatus, and has a function of shielding a portion in the + X direction from the optical axis AX among the three reflected light beams L1, L2, and L3. As shown in FIG. 7, the light detection unit 8 ′ includes three two-divided sensors 91, 92, and 93 that are arranged at intervals along the Y direction. The center two-divided sensor 91 is positioned so as to receive the 0th-order diffracted light L1 generated by the grating 2, and has two light receiving portions 91a and 91b equally divided by a linear region extending in the Y direction.

  In other words, the two light receiving portions 91 a and 91 b are arranged symmetrically with respect to a line segment that extends in the Y direction through the center point of the two-divided sensor 91. The two-divided sensor 92 on the left side in FIG. 7 is positioned so as to receive the + 1st-order diffracted light L 2, and has two light receiving portions 92 a and 92 b that are arranged symmetrically similarly to the two-divided sensor 91. The right divided sensor 93 in FIG. 7 has two light receiving parts 93 a and 93 b that are positioned so as to receive the −1st order diffracted light L <b> 3 and are arranged symmetrically similarly to the two divided sensor 91.

The output signal S1 of the two-divided sensor 91 is expressed by the following equation (6). In Expression (6), S1a is a value corresponding to the amount of light received by the light receiving unit 91a, and S1b is a value corresponding to the amount of light received by the light receiving unit 91b. The same applies to the output signal S2 of the two-divided sensor 92 and the output signal S3 of the two-divided sensor 93.
S1 = S1a-S1b (6)

  In the modification of FIG. 6, when the foreign matter 21 is attached to the third light L3 passage region R3, the light distribution 91c formed in the two-divided sensor 91 by the first light L1 as shown in FIG. The light distribution 92c formed by the second light L2 on the two-divided sensor 92 is similar to each other, but the light distribution 93c formed by the third light L3 on the two-divided sensor 93 is different from the light distributions 91c and 92c. Will be substantially different. In other words, the output signal S1 of the two-divided sensor 91 and the output signal S2 of the two-divided sensor 92 have values similar to each other, but the output signal S3 of the two-divided sensor 93 is substantially different from the output signals S1 and S2. It becomes a different value.

  In the modification of FIG. 6, for example, based on the signals S1, S2, and S3 obtained by the two-divided sensors 91, 92, and 93 by the same method as in the embodiment of FIG. The surface position displacement measurement values D1, D2 and D3 at P3 are obtained. Next, | D1-D2 | is compared with | D1-D3 | and | D2-D3 |, and a combination of displacement measurement values that minimizes the value is selected. Then, for example, an average value (Di + Dj) / 2 of the two selected displacement measurement values Di and Dj is obtained as the displacement D of the surface position of the back surface 20a that is the test surface.

  Therefore, even if the foreign material 21 adheres to any one of the regions R1, R2, and R3 through which the three lights L1, L2, and L3 pass on the surface 20b of the glass substrate 20, the influence of the foreign material 21 is affected. The displacement D of the surface position of the back surface 20a of the glass substrate 20 can be detected based on the two displacement information obtained by the two lights not received. In other words, in the modified example of FIG. 6 as well, in the same way as in the embodiment of FIG. 1, the influence D of the foreign material 21 attached to the front surface 20b of the glass substrate 20 is suppressed, and the displacement D of the surface position of the back surface 20a is reduced. It can be detected with high accuracy.

  In the above-described embodiment and modification, the three lights L1, L2, and L3 form a condensing point on the back surface 20a that is the test surface. However, without being limited to this, in order to make it less susceptible to the surface roughness of the back surface 20a, for example, the condensing points of the three lights L1, L2, and L3 in the vicinity of the back surface 20a, for example, inside the glass substrate 20 May be formed.

  In the embodiment and the modification described above, the 0th-order diffracted light L1, the + 1st-order diffracted light L2, and the −1st-order diffracted light L3 are generated from the light supplied from the light source LS by the diffraction action of the grating 2. However, an appropriate optical element other than the grating can be used as the light splitting member that splits the light from the light source into first to third light.

  In the embodiment and the modification described above, the polarization beam splitter 3 having the polarization separation surface 3a as a deflecting member for reflecting the three lights L1, L2, and L3 generated by the grating 2 and guiding them to the objective lens 5. Is used. However, the present invention is not limited to this, and various forms of this type of deflecting member are possible. For example, a normal beam splitter having no polarization separation surface can be used as this type of deflecting member. In general, the first to third light generated by the light splitting member is reflected or transmitted by a polarization type or normal type beam splitter and guided to an objective lens, and is then polarized or amplitude splitting through a surface to be measured. The first to third lights transmitted or reflected by the beam splitter can be photoelectrically converted.

  In the case of using an amplitude division type beam splitter, light that does not contribute to detection of displacement of the surface position is generated, and as a result, a light amount loss occurs. In this case, if necessary, the light quantity change of the light source can be monitored using light that does not contribute to the detection of the displacement of the surface position, and stabilization thereof can be achieved. Similarly, when a polarizing beam splitter is used, light that does not contribute to the detection of the displacement of the surface position can be actively generated as needed, and the light quantity change of the light source can be monitored using this light.

  Further, in the above-described embodiment and modification, the operation of the displacement detection device is described by paying attention to the influence of the foreign matter 21 attached to the surface 20b of the glass substrate 20. However, not only the foreign matter 21 adhering to the surface 20b but also striae, foreign matter, bubbles, etc. in the glass substrate 20 may cause detection errors. In the embodiment of FIG. 1 and the modification of FIG. 6, not only the influence of the foreign matter 21 attached to the front surface 20 b but also the influence of striae, foreign matter, bubbles, etc. in the glass substrate 20 is suppressed, and the surface position of the back surface 20 a Can be detected with high accuracy.

  Moreover, in the above-mentioned embodiment and modification, in the state which fixed the apparatus, the displacement of the surface position of the back surface 20a of the glass substrate 20 which is a test surface is detected. However, the present invention is not limited to this. For example, the objective lens 5 or the entire apparatus is moved in the Z direction so that the detected displacement D is always a constant value (for example, zero). The displacement of the surface position of the test surface can also be detected based on the above.

  In the above-described embodiment and modification, the present invention has been described by taking the displacement detection device that detects the displacement of the surface position of the back surface 20a of the glass substrate 20 as an example. However, the present invention is not limited to this, and the back surface of the glass substrate. The present invention can be similarly applied to the detection of the displacement of the test surface other than the above. In other words, various forms are possible for the application example of the displacement detection apparatus according to the embodiment of FIG. 1 or the modification of FIG.

  Hereinafter, a configuration example in which the displacement detection apparatus according to the above-described embodiment or modification is applied to the detection of the displacement of the surface position of the substrate stage in the exposure apparatus will be described with reference to FIG. The exposure apparatus shown in FIG. 8 includes an ArF excimer laser light source that is an exposure light source, for example, and includes an illumination system 61 that includes an optical integrator (homogenizer), a field stop, a condenser lens, and the like. The illumination system 61 illuminates a mask (reticle) M on which a pattern to be transferred is formed by exposure light emitted from a light source.

  The illumination system 61 illuminates, for example, the entire rectangular pattern region of the mask M, or an elongated slit-shaped region (for example, a rectangular region) along the X direction in the entire pattern region. The light from the pattern of the mask M forms a pattern image of the mask M on a unit exposure region of a wafer (photosensitive substrate) W coated with a photoresist via a projection optical system PL having a predetermined reduction magnification. That is, in the unit exposure area of the wafer W, a rectangular area similar to the entire pattern area of the mask M or a rectangular area elongated in the X direction (optically corresponding to the illumination area on the mask M) A mask pattern image is formed in the (static exposure region).

  The mask M is held parallel to the XY plane on the mask stage MS. The mask stage MS incorporates a mechanism for finely moving the mask M in the rotation directions around the X direction, the Y direction, and the Z axis. The mask stage MS is provided with a movable mirror (not shown), and a mask laser interferometer (not shown) using this movable mirror determines the position of the mask stage MS (and thus the mask M) in the X direction, Y direction and rotational direction. Measure in real time.

  The wafer W is held on the Z stage 62 in parallel with the XY plane. The Z stage 62 is mounted on an XY stage 63 that moves along an XY plane parallel to the image plane of the projection optical system PL, and a focus position (position in the Z direction) and an inclination angle (wafer W with respect to the XY plane) of the wafer W. The tilt of the surface). The Z stage 62 is provided with a movable mirror (not shown), and a wafer laser interferometer (not shown) using this movable mirror is able to determine the position of the Z stage 62 in the X direction, the Y direction, and the rotational direction around the Z axis in real time. measure. The XY stage 63 is placed on the base 64 and adjusts the position of the wafer W in the X direction, the Y direction, and the rotation direction.

  The output of the mask laser interferometer and the output of the wafer laser interferometer are supplied to a main control system (not shown). The main control system controls the position of the mask M in the X direction, the Y direction, and the rotation direction based on the measurement result of the mask laser interferometer. That is, the main control system transmits a control signal to a mechanism incorporated in the mask stage MS, and this mechanism finely moves the mask stage MS based on the control signal, thereby rotating the mask M in the X direction, Y direction, and rotation. Adjust the direction position.

  Further, the main control system adjusts the focus position and the tilt angle of the wafer W in order to align the surface of the wafer W with the image plane of the projection optical system PL by the autofocus method and the autoleveling method. Take control. That is, the main control system transmits a control signal to a wafer stage drive system (not shown), and the wafer stage drive system drives the Z stage 62 based on the control signal, so that the focus position and tilt angle of the wafer W are controlled. Make adjustments.

  The main control system controls the position of the wafer W in the X direction, the Y direction, and the rotation direction based on the measurement result of the wafer laser interferometer. That is, the main control system transmits a control signal to the wafer stage drive system, and the wafer stage drive system drives the XY stage 63 based on the control signal, whereby the position of the wafer W in the X direction, the Y direction, and the rotation direction is determined. Make adjustments.

  In the step-and-repeat method, the pattern image of the mask M is collectively exposed to one unit exposure area among a plurality of unit exposure areas set vertically and horizontally on the wafer W. Thereafter, the main control system transmits a control signal to the wafer stage drive system, and moves the XY stage 63 stepwise along the XY plane by the wafer stage drive system, thereby projecting another unit exposure region of the wafer W to the projection optical system. Position with respect to PL. Thus, the operation of collectively exposing the pattern image of the mask M to the unit exposure area of the wafer W is repeated.

  In the step-and-scan method, the main control system transmits a control signal to a mechanism incorporated in the mask stage MS, and also transmits a control signal to the wafer stage drive system, in accordance with the projection magnification of the projection optical system PL. While the mask stage MS and the XY stage 63 are moved at the speed ratio, the pattern image of the mask M is scanned and exposed to one unit exposure region of the wafer W. Thereafter, the main control system transmits a control signal to the wafer stage drive system, and moves the XY stage 63 stepwise along the XY plane by the wafer stage drive system, thereby projecting another unit exposure region of the wafer W to the projection optical system. Position with respect to PL. Thus, the operation of scanning and exposing the pattern image of the mask M to the unit exposure area of the wafer W is repeated.

  That is, in the step-and-scan method, the position of the mask M and the wafer W is controlled using a wafer stage drive system and a wafer laser interferometer, etc., and the short side direction of a rectangular (generally slit-shaped) still exposure region By moving (scanning) the mask stage MS and the XY stage 63 synchronously along the Y direction, the mask M and the wafer W are equal to the long side of the static exposure region on the wafer W. The mask pattern is scanned and exposed to an area having a width and a length corresponding to the scanning amount (movement amount) of the wafer W.

  The exposure apparatus of the present embodiment includes one or a plurality of displacement detection devices 60 for detecting the displacement of the surface position of the Z stage (substrate stage) 62 that supports the wafer (photosensitive substrate) W. The displacement detection device 60 has the same configuration as the device according to the embodiment of FIG. 1 or the modification of FIG. The displacement detection device 60 is used as, for example, the Z sensors 72a to 72d described in the pamphlet of International Publication No. 2007/097466, and the surface position of the rear surface of the glass substrate for an optical encoder provided on the substrate stage, that is, the substrate stage. The displacement of the surface position of the surface is detected.

  Next, a device manufacturing method using the exposure apparatus according to the embodiment of FIG. 8 will be described. FIG. 9 is a flowchart showing a semiconductor device manufacturing process. As shown in FIG. 9, in the semiconductor device manufacturing process, a metal film is vapor-deposited on the wafer W to be a substrate of the semiconductor device (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the exposure apparatus of the above-described embodiment, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W (step S44: exposure process), and the transfer of the wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred is performed (step S46: development process). Thereafter, using the resist pattern generated on the surface of the wafer W in step S46 as a mask, processing such as etching is performed on the surface of the wafer W (step S48: processing step).

  Here, the resist pattern is a photoresist layer in which unevenness having a shape corresponding to the pattern transferred by the exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. is there. In step S48, the surface of the wafer W is processed through this resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W or film formation of a metal film or the like. In step S44, the exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as the photosensitive substrate, that is, the plate P.

  FIG. 10 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 10, in the manufacturing process of the liquid crystal device, a pattern formation process (step S50), a color filter formation process (step S52), a cell assembly process (step S54), and a module assembly process (step S56) are sequentially performed.

  In the pattern forming process of step S50, a predetermined pattern such as a circuit pattern and an electrode pattern is formed on the glass substrate coated with a photoresist as the plate P using the exposure apparatus of the above-described embodiment. In this pattern formation process, an exposure process for transferring the pattern to the photoresist layer using the exposure apparatus of the above-described embodiment and development of the plate P to which the pattern is transferred, that is, development of the photoresist layer on the glass substrate are performed. And a developing step for generating a photoresist layer having a shape corresponding to the pattern, and a processing step for processing the surface of the glass substrate through the developed photoresist layer.

  In the color filter forming process in step S52, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning direction.

  In the cell assembly process in step S54, a liquid crystal panel (liquid crystal cell) is assembled using the glass substrate on which the predetermined pattern is formed in step S50 and the color filter formed in step S52. Specifically, for example, a liquid crystal panel is formed by injecting liquid crystal between a glass substrate and a color filter. In the module assembling process in step S56, various components such as an electric circuit and a backlight for performing the display operation of the liquid crystal panel are attached to the liquid crystal panel assembled in step S54.

  In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

It is a figure showing roughly the composition of the displacement detection device concerning the embodiment of the present invention. It is a figure which shows schematically the structure of the photon detection part in this embodiment. It is a figure which shows roughly the structure of the photon detection part in a comparative example. It is a figure which shows the relationship between the output signal of a 4-part dividing sensor, and the displacement of the surface position of a to-be-tested surface. It is a figure explaining the conditions where one foreign material affects only one 4-part dividing sensor. It is a figure which shows roughly the structure of the displacement detection apparatus concerning the modification using a knife edge method. It is a figure which shows schematically the structure of the photon detection part in the modification of FIG. It is a figure explaining the structural example which applied the displacement detection apparatus with respect to the detection of the displacement of the surface position of the substrate stage in exposure apparatus. It is a flowchart which shows the manufacturing process of a semiconductor device. It is a flowchart which shows the manufacturing process of liquid crystal devices, such as a liquid crystal display element.

Explanation of symbols

LS Light source IL Irradiation optical system DS Detection system 2 Grating 3 Polarizing beam splitter 4 1/4 wavelength plate 5 Objective lens 7 Cylindrical lens 8 Light detection unit 9 Signal processing unit 20 Glass substrate 20a The back surface of the glass substrate

Claims (11)

In the displacement detection device that detects the displacement of the surface position of the test surface,
The first to third light beams for guiding the first to third light beams to the first to third positions of the test surface to form first to third condensing points at or near the test surface, respectively. An optical system common to the third light;
First to third displacement information at the first to third positions is detected based on the first to third lights reflected from the test surface, respectively, and the most similar among the three displacement information. And a detection system that detects the displacement of the surface position of the surface to be measured based on the two pieces of displacement information. The common optical system forms a condensing point of the first to third lights on the back surface of the substrate as the test surface or in the vicinity thereof,
The distance between the centers of two light beams adjacent to each other on the surface of the substrate is the diameter of a circle circumscribing the light beam passage region on the surface of the substrate and a circle circumscribing a foreign material assumed to adhere to the surface of the substrate. The displacement detection device according to claim 1, wherein the displacement detection device is set to be larger than the sum of the maximum diameter and the maximum value. The common optical system includes a light dividing member that divides light from a light source into the first to third lights, and an objective lens disposed in an optical path between the light dividing member and the test surface. Have
2. The detection system according to claim 1, wherein the detection system detects a displacement of a surface position of the test surface based on the first to third light reflected by the test surface and passed through the objective lens. 3. The displacement detection device according to 2. The common optical system includes a beam splitter that reflects or transmits the first to third light generated by the light splitting member and guides the light to the objective lens,
The displacement detection apparatus according to claim 3, wherein the detection system includes first to third photoelectric conversion units that photoelectrically convert the first to third lights transmitted or reflected by the beam splitter. . The displacement detection apparatus according to claim 4, wherein each of the first to third photoelectric conversion units includes a quadrant sensor. The detection system includes an aberration generating member that is disposed in an optical path between the beam splitter and the photoelectric conversion unit and generates astigmatism in the first to third lights that have passed through the beam splitter. The displacement detection device according to claim 5, characterized in that: The detection system includes a light shielding member that partially blocks the first to third lights that have passed through the beam splitter;
The displacement detection apparatus according to claim 4, wherein each of the first to third photoelectric conversion units includes a two-divided sensor. The displacement detection apparatus according to claim 4, wherein the beam splitter has a polarization separation surface. An exposure apparatus comprising the displacement detection apparatus according to claim 1, wherein a predetermined pattern is exposed on a photosensitive substrate. A substrate stage for supporting the photosensitive substrate;
The exposure apparatus according to claim 9, wherein the displacement detection device detects a displacement of a surface position of the substrate stage. An exposure process for exposing the predetermined pattern to the photosensitive substrate using the exposure apparatus according to claim 9 or 10,
Developing the photosensitive substrate to which the predetermined pattern is transferred, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

Images