JP2009236655A - Displacement detecting apparatus, exposure apparatus, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement detecting apparatus can detect the displacement of a surface position of a surface to be inspected with high accuracy, by preventing the occurrence of detection errors resulting from variations in temperature and wavelength. <P>SOLUTION: The apparatus detects the displacement of the surface position of a surface to be detected by projecting light from a light source (LS) to the surface to be inspected (20a) through a measuring objective lens (4), based on reflected light from the surface to be inspected through the measuring objective lens, and includes a light-splitting member (2) which splits the light from the light source into a plurality of beams of light, guides a first beam of light out of the plurality of beams of light as measuring light along a measuring optical path, and guides a second beam of light as reference light out of the plurality along a reference optical path, and a detection system (13, 14) for detecting the displacement of the surface position of the surface to be inspected based on measurement information contained in measuring light reflected by the surface to be inspected and reference information contained in the reference light. <P>COPYRIGHT: (C)2010,JPO&INPIT

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

  In the displacement detection device disclosed in Patent Document 1, the internal temperature of the optical element fluctuates according to a change in the environmental temperature, and in particular, the detection displacement drift (fluctuation) tends to occur due to the fluctuation of the internal temperature of the objective lens. Moreover, detection displacement drift is likely to occur due to fluctuations in the wavelength of light supplied by the light source. In other words, it is necessary to stabilize the ambient temperature and wavelength with high accuracy in order to suppress the occurrence of displacement drift due to temperature fluctuations and wavelength fluctuations, and hence the occurrence of detection errors.

  The present invention has been made in view of the above-described problems, and is a displacement that can detect the displacement of the surface position of the surface to be detected with high accuracy while suppressing the occurrence of detection errors due to temperature fluctuations and wavelength fluctuations. An object is to provide a detection device.

In order to solve the above problems, in the first embodiment of the present invention, light from a light source is projected onto a test surface via a measurement objective lens, and reflected light from the test surface via the measurement objective lens. In the displacement detection device for detecting the displacement of the surface position of the test surface based on
The light from the light source is divided into a plurality of lights, the first light of the plurality of lights is guided as a measurement light along the measurement optical path, and the second light of the plurality of lights is referred to as a reference light A light splitting member that guides along the optical path;
And a detection system that detects a displacement of the surface position of the test surface based on measurement information included in the measurement light reflected by the test surface and reference information included in the reference light. Displacement detecting device is provided.

  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 according to one aspect of the present invention, the reference light passes through a reference optical path having conditions (environment temperature, optical element, optical path length, etc.) corresponding to the measurement optical path through which the measurement light passes. In particular, the reference light passes through a reference objective lens that is disposed at a position corresponding to the measurement objective lens through which the measurement light passes and has optical characteristics corresponding to the measurement objective lens. Further, the measurement light and the reference light are light obtained by dividing light from a common light source by a light dividing member, and have the same wavelength. In other words, the wavelength variation of the reference light matches the wavelength variation of the measurement light.

  Therefore, unlike the measurement light reflected by the test surface, the reference light does not include information on the displacement of the surface position of the test surface, but, like the measurement light, the reference light relates to the effects of temperature fluctuations and wavelength fluctuations. Contains information. As a result, in the displacement detection device of the present invention, the measurement information included in the measurement light reflected by the test surface and the reference information included in the reference light are not substantially affected by temperature fluctuations or wavelength fluctuations. Consequently, it is possible to detect the displacement of the surface position of the surface to be detected with high accuracy while suppressing the occurrence of detection errors due to temperature fluctuations and wavelength fluctuations.

  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 the first embodiment of the present invention. In the first 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 apparatus of the first embodiment includes a light source LS such as a laser diode. The light emitted from the light source LS has a polarization plane inclined by a predetermined angle with respect to the XY plane and the YZ plane, and enters the polarization beam splitter 2 through the collimator lens 1. Light incident on the polarization beam splitter 2 and reflected by the polarization separation surface 2a, that is, light in the s-polarized state, enters the quarter-wave plate 3 as measurement light L1.

  The measurement light L1 that has been in a circularly polarized state via the quarter-wave plate 3 enters the glass substrate 20 via the measurement objective lens 4. The measurement light L1 propagating through the glass substrate 20 and reflected by the back surface 20a is emitted from the glass substrate 20 and then enters the measurement objective lens 4. The measurement light L1 incident on the glass substrate 20 forms a condensing point on the back surface 20a that is the test surface or in the vicinity thereof. The measurement light L1 that has passed through the measurement objective lens 4 is converted into the p-polarized state via the quarter-wave plate 3, and then returns to the polarization beam splitter 2.

  On the other hand, the light that has entered the polarization beam splitter 2 and passed through the polarization separation surface 2a, that is, the light in the p-polarized state, enters the quarter-wave plate 5 as reference light L2. The reference light L 2 that has been circularly polarized through the quarter-wave plate 5 is incident on the reference substrate 7 through the reference objective lens 6. The reference objective lens 6 is disposed at a position corresponding to the measurement objective lens 4 and has optical characteristics corresponding to the measurement objective lens 4.

  The reference substrate 7 is disposed at a position corresponding to the glass substrate 20 and has optical characteristics corresponding to the glass substrate 20. However, the glass substrate 20 moves in the Z direction, but the reference substrate 7 is fixed in the Y direction. The reference light L <b> 2 propagating through the reference substrate 7 and reflected by the back surface 7 a is emitted from the reference substrate 7 and then enters the reference objective lens 6. The reference light L2 incident on the reference substrate 7 forms a condensing point on the back surface 7a that is the reference surface or in the vicinity thereof.

  The reference light L <b> 2 that has passed through the reference objective lens 6 is converted into the s-polarized state via the quarter-wave plate 5, and then returns to the polarization beam splitter 2. As described above, the polarization beam splitter 2 splits the light from the light source LS into two lights, guides the reflected light (first light) as the measurement light L1 along the measurement optical path, and transmits the transmitted light (second light). ) As a reference light L2 is configured as a light splitting member. Then, the polarization separation surface 2a of the polarization beam splitter 2 gives different polarization states to the measurement light L1 and the reference light L2.

  The p-polarized measurement light L1 that has returned to the polarization beam splitter 2 passes through the polarization separation surface 2a and enters the Wollaston prism 8. The s-polarized reference light L2 that has returned to the polarization beam splitter 2 is reflected by the polarization separation surface 2a and enters the Wollaston prism 8. The Wollaston prism 8 has a function of deflecting and emitting in a direction corresponding to the polarization state of incident light. Therefore, the measurement light L1 incident in the p-polarization state and the reference light L2 incident in the s-polarization state are incident on the condenser lens 9 after being deflected by the Wollaston prism 8 according to different polarization states. .

  The measurement light L1 that has passed through the condenser lens 9 reaches the measurement quadrant sensor 31 (not shown in FIG. 1; see FIG. 2) of the light detection unit 13 via the cylindrical lens 10 and the polarizing plate 11. The reference light L2 that has passed through the condensing lens 9 reaches the reference quadrant sensor 32 (not shown in FIG. 1; see FIG. 2) of the light detection unit 13 via the cylindrical lens 10 and the polarizing plate 12. The cylindrical lens 10 has a positive refractive power in the XZ plane and no refractive power in the YZ plane, and has a function of generating astigmatism in the measurement light L1 and the reference light L2 that have passed through the polarization beam splitter 2.

  The polarizing plate 11 is disposed so that only light in the p-polarized state is transmitted, and has a function of blocking noise light included in the measurement light L1 from entering the measurement quadrant sensor 31. The polarizing plate 12 is disposed so that only light in the s-polarized state is transmitted, and has a function of blocking noise light included in the reference light L2 from entering the reference quadrant sensor 32. Note that the cylindrical lens 10 may be disposed on the front side of the condenser lens 9 (on the side of the polarization beam splitter 2). Further, the installation of the polarizing plates 11 and 12 can be omitted. Further, for example, when the light source LS itself has necessary and sufficient astigmatism, the cylindrical lens 10 may be omitted. As such a light source LS, a laser diode can be used.

  As shown in FIG. 2, the light detection unit 13 includes a measurement quadrant sensor 31 and a reference quadrant sensor 32 that are arranged at intervals along the Y direction. The measurement quadrant sensor 31 is positioned so as to receive the measurement light L1, for example, a linear region extending in a direction forming 45 degrees with the + X direction and the + Y direction, and a direction forming 45 degrees with the + X direction and the −Y direction. And four light receiving portions 31a, 31b, 31c, and 31d that are equally divided by a linear region extending in the direction.

  In other words, the four light receiving portions 31 a, 31 b, 31 c, and 31 d are arranged point-symmetrically with respect to the center point of the four-divided sensor 31. The reference quadrant sensor 32 is positioned so as to receive the reference light L2, and has four light receiving portions 32a, 32b, 32c, and 32d that are arranged point-symmetrically like the measurement quadrant sensor 31. The output of the light detection unit 13, that is, the output signal Sm of the measurement quadrant sensor 31 and the output signal Sr of the reference quadrant sensor 32 are supplied to the signal processing unit 14.

  First, in order to facilitate understanding of the operation of the displacement detection apparatus of the first 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 components related to the reference light L2, that is, the quarter wavelength plate 5, the reference objective lens 6, the reference substrate 7, the polarizing plate 12, and the reference four-divided sensor 32 from the configurations of FIGS. The installation of is omitted. Further, in the comparative example, the installation of the Wollaston prism 8 is unnecessary. Hereinafter, with reference to FIG. 1, the light corresponding to the measurement light L <b> 1 is reflected by the back surface 20 a of the glass substrate 20 and corresponds to the measurement quadrant sensor 31 so that the operation of the comparative example can be understood. It is assumed that a single quadrant sensor 33 (see FIG. 3) is reached.

  In the comparative example, when the back surface 20a of the glass substrate 20 is in a predetermined position (for example, the focal position of the objective lens 4) in the optical ideal state, the reflected light from the back surface 20a is divided into four sensors as shown in FIG. In 33, a circular light distribution 33e centering on the center point of the four light receiving portions 33a to 33d 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 33 by the action of the cylindrical lens 10 as an aberration generating member is the moving direction of the back surface 20a (+ Z Direction or -Z direction) and the amount of movement along the Z direction, as shown schematically by reference numerals 33ea and 33eb on the left and right sides of FIG. 3, the vicinity of the center point of the four light receiving portions 33a to 33d It changes to an elliptical shape with the center.

The output signal S of the quadrant sensor 33 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 33a, and Sb is a value corresponding to the received light amount of the light receiving unit 33b adjacent to the light receiving unit 33a. Sc is a value corresponding to the amount of light received by the light receiving unit 33c facing the light receiving unit 33a, and Sd is a value corresponding to the amount of received light of the light receiving unit 33d facing the light receiving unit 33b. The same applies to the output signal Sm of the measurement quadrant sensor 31 and the output signal Sr of the reference quadrant sensor 32 in the first 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 33 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 33. 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 14 to which the output signal S of the quadrant sensor 33 is supplied, the moving 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 14 uses, for example, 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 33 is zero as the output signal of the quadrant sensor 33. Calculation is based on the sign and absolute value of S.

  In the comparative example, the internal temperature of the optical element fluctuates according to the change in the environmental temperature, and in particular, the detection displacement drift (fluctuation) easily occurs due to the fluctuation of the internal temperature of the objective lens 4. Moreover, detection displacement drift is likely to occur due to fluctuations in the wavelength of light supplied by the light source LS. Specifically, in the comparative example according to the normal design, when the internal temperature of the objective lens 4 changes by 1 ° C., a displacement drift of about 760 nm occurs. When the objective lens 4 is made of PMMA (polymethylmethacrylate: acryl) and the focal length is 4 mm, a displacement drift of about 160 nm occurs when the wavelength of light changes by 1 nm.

  As described above, in the first embodiment, the reference light L2 passes through the reference light path having conditions (environmental temperature, optical elements to pass through, optical path length, etc.) corresponding to the measurement light path through which the measurement light L1 passes. In particular, the reference light L2 passes through the reference objective lens 6 which is disposed at a position corresponding to the measurement objective lens 4 through which the measurement light L1 passes and has optical characteristics corresponding to the measurement objective lens 4. The measurement light L1 and the reference light L2 are light obtained by dividing light from a common light source LS by the polarization beam splitter 2 and have the same wavelength. In other words, the wavelength variation of the reference light L2 matches the wavelength variation of the measurement light L1.

  Therefore, the reference light L2 reflected by the fixed reference surface (back surface 7a of the reference substrate 7) is different from the measurement light L1 reflected by the test surface (back surface 20a of the glass substrate 20) that moves in the Z direction. The information on the displacement of the surface position of the test surface is not included. However, like the measurement light L1, the reference light L2 includes information regarding the influence of temperature fluctuations and the influence of wavelength fluctuations. As a result, based on the measurement information included in the measurement light L1 reflected by the surface to be measured and the reference information included in the reference light L2 reflected by the reference surface, it is not substantially affected by temperature variation or wavelength variation. The displacement of the surface position of the test surface can be detected. In other words, in the first embodiment, it is possible to detect the displacement of the surface position of the surface to be detected with high accuracy while suppressing the occurrence of detection errors due to temperature fluctuations and wavelength fluctuations.

That is, in the signal processing unit 14, based on the difference (Sm−Sr) obtained by subtracting the output signal Sr of the reference quadrant sensor 32 from the output signal Sm of the measurement quadrant sensor 31, the back surface 20 a of the glass substrate 20. The displacement D of the surface position is calculated. Specifically, the signal processing unit 14 obtains the displacement D of the surface position of the back surface 20a by the following equation (2). In Equation (2), Km is the slope (linearity) of the S curve in a predetermined range centered on the origin of the S curve of the measurement quadrant sensor 31, and is the rate of change of the signal Sm with respect to the change of the surface position. . The change rate Km is obtained in advance by measurement, for example.
D = (Sm−Sr) × Km (2)

The output signal Sm of the measurement quadrant sensor 31 and the output signal Sr of the reference quadrant sensor 32 are expressed by the following equations (3) and (4), respectively. In Equation (3), Sma is a light receiving portion 31a, Smb is a light receiving portion 31b, Smc is a light receiving portion 31c, and Smd is a value corresponding to the amount of light received by the light receiving portion 31d. In Equation (4), Sra is a light receiving unit 32a, Srb is a light receiving unit 32b, Src is a light receiving unit 32c, and Srd is a value corresponding to the amount of light received by the light receiving unit 32d.
Sm = (Sma + Smc) − (Smb + Smd) (3)
Sr = (Sra + Src) − (Srb + Srd) (4)

  In the first embodiment described above, the position and optical characteristics of the reference objective lens 6 do not necessarily correspond to the position and optical characteristics of the measurement objective lens 4. Further, the position and optical characteristics of the reference substrate 7 do not necessarily correspond to the position and optical characteristics of the glass substrate 20. However, in order to achieve highly accurate detection by matching the conditions between the reference optical path and the measurement optical path as much as possible, between the reference objective lens 6 and the measurement objective lens 4 and between the reference substrate 7 and the glass substrate 20. It is desirable that the position and the optical characteristics correspond to each other.

  In the first embodiment described above, the cylindrical lens 10 as an aberration generating member that generates astigmatism in the measurement light L1 and the reference light L2 that have passed through the polarization beam splitter 2, and measurement photoelectric conversion that photoelectrically converts the measurement light L1. Using the astigmatism method, the displacement of the surface position of the back surface 20a is detected by using the four-divided sensor 31 as a unit and the four-divided sensor 32 as a reference photoelectric conversion unit that photoelectrically converts the reference light L2. is doing. 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. 5 and FIG. 6, a configuration example of a displacement detection device that detects the displacement of the surface position of the back surface of the glass substrate by the knife edge method will be described. The modified example of FIG. 5 has a configuration similar to that of the first embodiment of FIG. 1, but uses a light shielding member 15 instead of the cylindrical lens 10 and two two-divided sensors instead of the two four-divided sensors 31 and 32. The point which uses 41 and 42 is different from 1st Embodiment. 5, elements having the same functions as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. Hereinafter, the configuration and operation of the modified example of FIG. 5 will be described with a focus on differences from the first embodiment.

  In the modification of FIG. 5, the measurement light L <b> 1 and the reference light L <b> 2 that have passed through the condenser lens 9 are incident on the light shielding member 15. The light shielding member 15 has an edge 15a extending in the Y direction orthogonal 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 of the measurement light L1 and the reference light L2. In other words, the edge 15a of the light shielding member 15 extends in parallel with a surface (YZ plane) on which the Wollaston prism 8 deflects the measurement light L1 and the reference light L2. As shown in FIG. 6, the light detection unit 13 ′ includes two two-divided sensors 41 and 42 that are arranged at intervals along the Y direction.

  6 includes two light receiving portions 41a and 41b that are positioned so as to receive the measurement light L1 and are equally divided by a linear region that extends in the Y direction. In other words, the two light receiving portions 41 a and 41 b are arranged symmetrically with respect to a line segment extending in the Y direction through the center point of the two-divided sensor 41. 6 includes two light receiving portions 42a and 42b which are positioned so as to receive the reference light L2 and are arranged symmetrically like the measurement two-divided sensor 41.

The output signal Sm of the measurement two-divided sensor 41 and the output signal Sr of the reference two-divided sensor 42 are expressed by the following equations (5) and (6). In Expression (5), Sma is a value corresponding to the amount of light received by the light receiving unit 41a, and Smb is a value corresponding to the amount of light received by the light receiving unit 41b. In Expression (6), Sra is a value corresponding to the amount of light received by the light receiving unit 42a, and Srb is a value corresponding to the amount of light received by the light receiving unit 42b.
Sm = Sma−Smb (5)
Sr = Sra-Srb (6)

  In the modification of FIG. 5, the light distribution 41c formed by the measurement light L1 on the two-divided sensor 41 and the reference light L2 are formed on the two-divided sensor 42 in response to the occurrence of the displacement D of the surface position of the back surface 20a of the glass substrate 20. The light distribution 42c is different. Thus, in the modified example of FIG. 5 as well, in the same manner as in the first embodiment, the above-described equation (2) is used to suppress the occurrence of detection errors due to temperature fluctuations and wavelength fluctuations, and The displacement D of the surface position of the back surface 20a can be detected with high accuracy.

  In the first embodiment, the Wollaston prism 8 is used to deflect the measurement light L1 and the reference light L2 in a direction corresponding to the polarization state, thereby leading the measurement light L1 to the measurement quadrant sensor 31. The reference light L2 is guided to a reference quadrant sensor 32 different from the measurement quadrant sensor 31. However, the present invention is not limited to this, and as shown in the modified example of FIG. 7, the optical path separation action of the Wollaston prism 8 can be achieved by using the corner cube 16 instead of the reference substrate 7.

  In the modification of FIG. 7, the reference light L <b> 2 that has passed through the polarizing beam splitter 2, the quarter wavelength plate 5, and the reference objective lens 6 is incident on the corner cube 16. The reference light L2 propagating through the corner cube 16 and sequentially reflected by the plurality of reflecting surfaces is emitted from the corner cube 16 along an optical path different from the incident optical path to the corner cube 16 and then the reference objective lens 6. Is incident on. Thus, due to the action of the corner cube 16, the optical path of the measurement light L1 from the polarization beam splitter 2 to the measurement quadrant sensor 31 and the reference quadrant sensor 32 from the polarization beam splitter 2 can be obtained without using the Wollaston prism 8. The optical path of the reference light L2 heading toward is separated.

  In the modification of FIG. 7, instead of the corner cube 16, another optical member having a function of sequentially reflecting the reference light L <b> 2 by a plurality of reflecting surfaces and emitting it along an optical path different from the incident optical path, for example, a triangle A prism or the like can be used. Although not shown, the corner cube 16 may be used in place of the reference substrate 7 in the modification of FIG. In other words, in the basic configuration of the modified example of FIG. 7, for example, a technique such as a knife edge method or a critical angle method can be used.

  FIG. 8 is a diagram schematically showing a configuration of a displacement detection apparatus according to the second embodiment of the present invention. The second embodiment has a configuration similar to that of the first embodiment, but the configuration of the reference optical path is different from that of the first embodiment. In the second embodiment, unlike the first embodiment, the Wollaston prism 8 is not used. 8, elements having the same functions as those shown in FIG. 1 are denoted by the same reference numerals as those in FIG. Hereinafter, the configuration and operation of the second embodiment will be described with a focus on differences from the first embodiment.

  In the second embodiment, the measurement light L1 reflected by the back surface 20a of the glass substrate 20 is measured by the measurement objective lens 4, the quarter wavelength plate 3, the polarization beam splitter 2, the condensing lens 9, the cylindrical lens 10a, and the polarizing plate. 11 and reaches the measurement quadrant sensor 31 of the light detection unit 13a. On the other hand, the reference light L2 that has passed through the polarization beam splitter 2 reaches the reference quadrant sensor 32 of the light detection unit 13b via the quarter-wave plate 5, the reference objective lens 6, and the cylindrical lens 10b.

  The cylindrical lenses 10a and 10b have a positive refractive power in the XZ plane and no refractive power in the YZ plane, like the cylindrical lens 10 in the first embodiment. However, the cylindrical lens 10a generates astigmatism only in the measurement light L1, and the cylindrical lens 10b generates astigmatism only in the reference light L2. In addition, the light receiving surface of the reference quadrant sensor 32 of the light detection unit 13b is disposed to be inclined with respect to the XZ plane in order to prevent the reflected light from entering the measurement optical path and becoming noise light.

  In the second embodiment, unlike the first embodiment, there is no common optical path portion between the reference optical path through which the reference light L2 passes and the measurement optical path through which the measurement light L1 passes. As a result, the reference light L2 and the measurement light L1 have substantially the same conditions regarding the environmental temperature, but have different conditions regarding the optical element that passes therethrough, the optical path length, and the like. However, also in the second embodiment, as in the first embodiment, the reference light L2 is arranged at a position corresponding to the measurement objective lens 4 through which the measurement light L1 passes and has optical characteristics corresponding to the measurement objective lens 4. Pass through the reference objective 6. Further, the measurement light L1 and the reference light L2 are light obtained by dividing the light from the common light source LS by the polarization beam splitter 2 and have the same wavelength, and fluctuations in the wavelength of the reference light L2 are measured. This coincides with the fluctuation of the wavelength of the light L1.

  Therefore, unlike the measurement light L1, the reference light L2 does not include information on the displacement of the surface position of the test surface, but, like the measurement light L1, includes information on the effects of temperature fluctuations and wavelength fluctuations. Yes. As a result, similarly to the first embodiment, the second embodiment is substantially affected by temperature fluctuations and wavelength fluctuations based on the measurement information included in the measurement light L1 and the reference information included in the reference light L2. Instead, the displacement of the surface position of the back surface 20a of the glass substrate 20 as the test surface can be detected.

Specifically, in the second embodiment, the signal processing unit 14 obtains the displacement D of the surface position of the back surface 20a of the glass substrate 20 by the following equation (7). In equation (7), the rate of change Kr is the slope of the S curve in a predetermined range centered on the origin of the S curve of the reference quadrant sensor 32 (different from the slope of the S curve of the measurement quadrant sensor 31). Yes, for example, it is calculated from the change rate Km obtained in advance by measurement and the design data.
D = Sm × Km−Sr × Kr (7)

  In the second embodiment described above, the cylindrical lens 10a as a first aberration generating member that generates astigmatism in the measurement light L1 that has passed through the polarization beam splitter 2, and the reference light L2 that has passed through the polarization beam splitter 2 are astigmatism. A cylindrical lens 10b as a second aberration generating member that generates aberration, a four-divided sensor 31 as a measurement photoelectric conversion unit that photoelectrically converts the measurement light L1, and a four-division as a reference photoelectric conversion unit that photoelectrically converts the reference light L2. Using the sensor 32, the displacement of the surface position of the back surface 20a, which is the test surface, is detected by the astigmatism method. However, without being limited to the astigmatism method, for example, a knife edge method or a critical angle method can be applied to the basic configuration of the second embodiment.

  In the embodiment and the modification described above, the light from the light source LS is divided into two lights, the reflected light is guided along the measurement optical path as the measurement light L1, and the transmitted light is guided along the reference optical path as the reference light L2. A polarization beam splitter 2 having a polarization separation surface 2a is used as a light splitting member for guiding. However, the present invention is not limited to this, and various forms are possible for this type of light splitting member. For example, a normal beam splitter having no polarization separation surface can be used as this type of light splitting member.

  In general, a polarization beam or a normal beam splitter can guide reflected light or transmitted light along the measurement optical path as measurement light and guide transmitted light or reflected light along the reference optical path as reference light. However, when a normal beam splitter is used, light that does not contribute to the detection of the displacement of the surface position is generated, and as a result, a light amount loss occurs. Further, in the above-described embodiment and modification, the light quantity change of the light source can be monitored and stabilized by using the reference quadrant sensor 32 as necessary.

  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 measurement objective lens 4 or the entire apparatus is moved in the Z direction so that the detected displacement D is always a constant value (for example, zero), and the measurement objective lens 4 or the entire apparatus is moved in the Z direction. The displacement of the surface position of the test surface can also be detected based on the amount of movement.

  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 above-described embodiment or modification.

  Hereinafter, a configuration example in which the displacement detection device 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 of FIG. 9 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 FIG. 8 or the modification of FIG. 5 or 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. 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. 9 will be described. FIG. 10 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 10, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a 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. 11 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 11, 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 detector concerning a 1st embodiment of the present invention. It is a figure which shows schematically the structure of the photon detection part in 1st 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 which shows roughly the structure of the displacement detection apparatus concerning the modification which applied the knife edge method with respect to 1st Embodiment. It is a figure which shows schematically the structure of the photon detection part in the modification of FIG. It is a figure which shows roughly the structure of the displacement detection apparatus concerning the modification using a corner cube instead of a reference board in 1st Embodiment. It is a figure which shows schematically the structure of the displacement detection apparatus concerning 2nd Embodiment of this invention. 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 2 Polarizing beam splitter 3, 5 1/4 wavelength plate 4 Measurement objective lens 6 Reference objective lens 7 Reference substrate 8 Wollaston prism 10 Cylindrical lens 13 Photodetection unit 14 Signal processing unit 20 Glass substrate 20a Back surface of glass substrate

Claims (16)

Light from the light source is projected onto the test surface via the measurement objective lens, and the displacement of the surface position of the test surface is detected based on the reflected light from the test surface via the measurement objective lens. In the displacement detection device,
The light from the light source is divided into a plurality of lights, the first light of the plurality of lights is guided as a measurement light along the measurement optical path, and the second light of the plurality of lights is referred to as a reference light A light splitting member that guides along the optical path;
And a detection system that detects a displacement of the surface position of the test surface based on measurement information included in the measurement light reflected by the test surface and reference information included in the reference light. Displacement detector. A reference objective lens disposed at a position corresponding to the measurement objective lens in the reference optical path and having optical characteristics corresponding to the measurement objective lens;
The displacement detection apparatus according to claim 1, wherein the measurement objective lens is disposed in an optical path between the light splitting member and the test surface. The displacement detection apparatus according to claim 2, further comprising a measurement photoelectric conversion unit that photoelectrically converts the measurement light reflected by the test surface and passed through the measurement objective lens and the light splitting member. A reference photoelectric conversion unit that photoelectrically converts the reference light that is incident on the reference surface through the reference objective lens and reflected by the reference surface and that has passed through the reference objective lens and the light splitting member is provided. The displacement detection apparatus according to claim 3. The displacement detection device according to claim 4, wherein each of the measurement photoelectric conversion unit and the reference photoelectric conversion unit includes a quadrant sensor. An aberration generating member that is arranged in an optical path between the light splitting member and the measurement photoelectric conversion unit and the reference photoelectric conversion unit and generates astigmatism in the measurement light and the reference light that has passed through the light splitting member. The displacement detection apparatus according to claim 5, further comprising: A light shielding member that is arranged in an optical path between the light splitting member and the measurement photoelectric conversion unit and the reference photoelectric conversion unit and partially blocks the measurement light and the reference light that have passed through the light splitting member;
The displacement detection device according to claim 5, wherein each of the measurement photoelectric conversion unit and the reference photoelectric conversion unit includes a two-divided sensor. The light splitting member has a polarization separation surface that gives different polarization states to the measurement light and the reference light,
A light beam is disposed in an optical path between the light splitting member and the measurement photoelectric conversion unit and the reference photoelectric conversion unit, and at least one of the measurement light and the reference light is deflected in a direction according to a polarization state of light. The displacement detection device according to claim 4, further comprising a deflection member that performs the above-described operation. The displacement detection apparatus according to claim 4, wherein the reference surface includes a plurality of reflection surfaces that sequentially reflect the reference light. The displacement detection apparatus according to claim 3, further comprising a reference photoelectric conversion unit that photoelectrically converts the reference light that has passed through the reference objective lens. The displacement detection device according to claim 10, wherein each of the measurement photoelectric conversion unit and the reference photoelectric conversion unit includes a quadrant sensor. A first aberration generating member that is arranged in an optical path between the light splitting member and the measurement photoelectric conversion unit and generates astigmatism in the measurement light that has passed through the light splitting member;
And a second aberration generating member that is disposed in an optical path between the light splitting member and the reference photoelectric conversion unit and generates astigmatism in the reference light that has passed through the light splitting member. Item 12. The displacement detection device according to Item 11. A first light shielding member that is arranged in an optical path between the light splitting member and the measurement photoelectric conversion unit and partially blocks the measurement light that has passed through the light splitting member;
A second light shielding member that is disposed in an optical path between the light splitting member and the reference photoelectric conversion unit and partially shields the reference light that has passed through the light splitting member;
The displacement detection apparatus according to claim 10, wherein each of the measurement photoelectric conversion unit and the reference photoelectric conversion unit includes a two-divided sensor. 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 14, 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 14 or 15;
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