JP2009236653A - Displacement detecting apparatus, exposure apparatus, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a displacement detecting apparatus can prevent an effect of contaminations deposited on the surface of a glass substrate for example, and detect a displacement of a surface position of the glass substrate with high accuracy. <P>SOLUTION: The displacement detecting apparatus for detecting a displacement of a surface position of a surface to be inspected 20a, includes an irradiation system (IL: 1, 2, 3, 4, 5) for irradiating a surface of an object 20 as the surface to be inspected, after a focal point P is formed once by an objective lens 5 based on light from a light source LS, and a detection system (DS: 5, 4, 3, 6, 7, 8, 9) for detecting the displacement of the surface position of the surface to be inspected based on light reflected by the surface to be inspected and allowed to pass through the objective lens. <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 case of detecting the displacement of the surface position of the glass substrate using the displacement detection device disclosed in Patent Document 1, for example, it is conceivable to form a laser beam condensing point on the back surface of the glass substrate or in the vicinity thereof. In this case, for example, a relatively large detection error may occur due to the influence of foreign matters (dust etc.) attached to the surface of the glass substrate.

  The present invention has been made in view of the above-described problems, and for example, a displacement detection device capable of detecting the displacement of the surface position of the glass substrate with high accuracy while suppressing the influence of foreign matter attached to the surface of the glass substrate. 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,
An irradiation system for irradiating the surface of the object as the test surface after forming a condensing point once by an objective lens based on light from a light source,
There is provided a displacement detection apparatus comprising: a detection system that detects a displacement of a surface position of the test surface based on light reflected by the test surface and passed through the objective lens.

In the second embodiment of the present invention, in the displacement detection device for detecting the displacement of the surface position of the test surface,
An irradiation system for converging light from a light source by an objective lens and irradiating the surface of the object as the test surface;
A displacement system comprising: a detection system that forms a condensing point once reflected by the test surface and detects a displacement of a surface position of the test surface based on light that has passed through the objective lens. A detection device is provided.

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

In the fourth embodiment of the present invention, using the exposure apparatus of the third 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, light from a light source is irradiated onto the surface of a glass substrate (generally an object), which is a test surface, for example, via an objective lens, and reflected by the surface to be objective. Based on the light that has passed through the lens, the displacement of the surface position of the surface is detected. As a result, since no light enters the inside of the glass substrate, detection errors due to, for example, striae in the glass substrate, foreign matter, bubbles, and surface roughness of the back surface do not occur.

  In addition, once the focal point is formed by the objective lens, the surface of the glass substrate is irradiated with light in a defocused state, and the displacement of the surface position is detected based on the reflected light from the surface. The amount of light incident on the foreign matter on the surface is relatively smaller than the amount of light reflected upon entering the surface, and the influence of the foreign matter on the detection accuracy is greatly reduced. Thus, in the displacement detection device of the present invention, for example, the displacement of the surface position of the glass substrate can be detected with high accuracy 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 the first embodiment of the present invention. In the first embodiment, the present invention is applied to a displacement detection device that detects a displacement of a surface position of a glass substrate using an astigmatism method. In FIG. 1, the Z axis is in the normal direction of the surface 20a of the glass substrate 20, the Y axis is in the direction parallel to the paper surface of FIG. 1 on the 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, an irradiation system IL, and a detection system DS. The irradiation system IL irradiates light onto the surface (surface on the apparatus side) 20a of the glass substrate 20 as the test surface after once forming the condensing point P by the objective lens 5 based on the light from the light source LS. The detection system DS detects the displacement of the surface position of the surface 20a and consequently the displacement of the surface position of the glass substrate 20 based on the light reflected by the surface 20a and passed through the objective lens 5.

  Specifically, the irradiation system IL includes a collimating lens 1, a condenser lens 2, a polarizing 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. Yes. The detection system DS includes the objective lens 5, the quarter wavelength plate 4, the polarization beam splitter 3, the cylindrical lens 6, the condensing lens 7, and 4 in the order of incidence of the reflected light from the surface 20a of the glass substrate 20. A split sensor 8 is provided. Further, the detection system DS includes a signal processing unit 9 connected to the quadrant sensor 8.

  In the displacement detection apparatus of the first 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 polarization beam splitter 3 via the collimator lens 1 and the condenser lens 2. The s-polarized light incident on the polarization beam splitter 3 is reflected by the polarization separation surface 3 a, exits from the polarization beam splitter 3, and then enters the quarter wavelength plate 4.

  The light converted into the circularly polarized state through the quarter-wave plate 4 is incident on the surface 20 a of the glass substrate 20 after forming a condensing point P through the objective lens 5. The light reflected by the surface 20 a as the test surface passes through the objective lens 5, is converted to a p-polarized state by the quarter-wave plate 4, and enters the polarization beam splitter 3. The p-polarized light that has entered the polarization beam splitter 3 passes through the polarization separation surface 3 a, exits from the polarization beam splitter 3, and then enters the cylindrical lens 6.

  The cylindrical lens 6 has a positive refractive power in the XZ plane and has no refractive power in the YZ plane, and has a function of generating astigmatism in the reflected light that has passed through the polarizing beam splitter 3. The light that has passed through the cylindrical lens 6 reaches the quadrant sensor 8 as a photoelectric conversion unit via the condenser lens 7. In addition, the cylindrical lens 6 can also be arrange | positioned in the back side (4-part dividing sensor 8 side) of the condensing lens 7. FIG. Further, for example, when the light source LS itself has necessary and sufficient astigmatism, the cylindrical lens 6 may be omitted. As such a light source LS, a laser diode can be used.

  The four-divided sensor 8 is, for example, equally divided into a linear region extending in the direction of 45 degrees with the + X direction and the + Y direction and a linear region extending in a direction of 45 degrees with the + X direction and the -Y direction. There are two light receiving portions 8a, 8b, 8c, 8d. In other words, the four light receiving portions 8 a, 8 b, 8 c, and 8 d are arranged point-symmetrically with respect to the center point of the quadrant sensor 8. The output signal S of the quadrant sensor 8 is supplied to the signal processing unit 9.

  Prior to the description of the operation of the displacement detection apparatus according to the first embodiment, the inconvenience of a normal configuration example using the astigmatism method (hereinafter referred to as “comparative example”) will be described below. In the comparative example shown in FIG. 3, the condensing lens 2 is removed from the configuration of FIG. 1, and a condensing point is formed on the back surface 20b of the glass substrate 20 or in the vicinity thereof. In the comparative example, when the back surface 20b of the glass substrate 20 is in 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 20b is 4 as shown in the center of FIG. In the divided sensor 8 ′, a circular light distribution 8e ′ centering on the center point of the four light receiving portions 8a ′ to 8d ′ is formed.

  When the back surface 20b of the glass substrate 20 moves in the Z direction from the predetermined position, the light distribution formed on the quadrant sensor 8 ′ by the action of the cylindrical lens 6 as an aberration generating member is the moving direction of the back surface 20b ( + Z direction or −Z direction) and four light receiving portions 8a ′ to 8d ′ as schematically indicated by reference numerals 8ea ′ and 8eb ′ on the left and right sides of FIG. 4 according to the amount of movement along the Z direction. It changes into an elliptical shape centered around the center point of.

The output signal S ′ of the quadrant sensor 8 ′ is expressed by the following equation (1). In Expression (1), Sa ′ is a value corresponding to the received light amount of the light receiving unit 8a ′, and Sb ′ is a value corresponding to the received light amount of the light receiving unit 8b ′ adjacent to the light receiving unit 8a ′. Sc ′ is a value corresponding to the amount of light received by the light receiving unit 8c ′ facing the light receiving unit 8a ′, and Sd ′ is a value corresponding to the amount of received light of the light receiving unit 8d ′ facing the light receiving unit 8b ′. The same applies to the output signal S of the quadrant sensor 8 in the first embodiment.
S ′ = (Sa ′ + Sc ′) − (Sb ′ + Sd ′) (1)

  In the comparative example according to the normal design, there is a difference between the output signal S ′ of the quadrant sensor 8 ′ represented by the equation (1) and the displacement D ′ of the surface position of the back surface 20b of the glass substrate 20 as shown in FIG. The following relationship is established. In FIG. 5, the horizontal axis represents the displacement D ', and the vertical axis represents the output signal S' of the quadrant sensor 8 '. The S-shaped line (S curve) representing the relationship between the output signal S ′ and the displacement D ′ has a high linearity (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 8 ′ is supplied, the moving direction of the back surface 20b of the glass substrate 20 (that is, the sign of the displacement D ′) is based on the sign of the change amount of the output signal S ′. The amount of movement along the Z direction of the back surface 20b of the glass substrate 20 (that is, the absolute value of the displacement D ′) is obtained based on the absolute value of the change amount of the output signal S ′. Specifically, the signal processing unit 9 determines the sign and absolute value of the displacement D ′ of the surface position of the back surface 20b from the initial state where the output signal S ′ of the quadrant sensor 8 ′ is zero, for example. It is calculated based on the sign and absolute value of 'output signal S'.

  In the comparative example of FIG. 3, foreign matter (dust, water droplets, etc.) adheres to a region where the incident light beam on the back surface 20b of the glass substrate 20 passes through the front surface 20a or a region where the light beam emitted from the back surface 20b passes through the front surface 20a. If so, the light reaching the quadrant sensor 8 'is affected by this foreign matter, and a detection error occurs. Further, not only foreign matter adhering to the front surface 20a but also striae, foreign matter, bubbles, and surface roughness of the back surface 20b in the glass substrate 20, for example, affect the light reaching the quadrant sensor 8 ′. It causes an error.

  In the comparative example according to the normal design, as shown in FIG. 6, in a state where the surface position of the back surface 20b of the glass substrate 20 does not change (that is, the glass substrate 20 is fixed in the Z direction), a circular shape with a diameter of 30 μm. When the foreign object moves on the surface 20a along the X direction, the relationship between the X direction position (mm) of the center of the foreign object with respect to the optical axis AX of the apparatus and the detection error (nm) was obtained. Referring to FIG. 6, it can be seen that a detection error of about 45 nm at maximum occurs when the center of the foreign matter attached on the surface 20a is slightly displaced from the optical axis AX. In addition, when a foreign substance exists in the inside of the glass substrate 20, generation | occurrence | production of a bigger detection error is estimated.

  In the first embodiment, light from the light source LS is irradiated onto the surface 20a of the glass substrate 20 through the objective lens 5, and the surface of the surface 20a is reflected on the light reflected by the surface 20a and passed through the objective lens 5. The displacement of the position is detected. That is, in the first embodiment, unlike the comparative example, light does not enter the inside of the glass substrate 20, for example, due to striae in the glass substrate 20, foreign matter, bubbles, and surface roughness of the back surface 20 b. Detection error does not occur.

  Further, in the first embodiment, unlike the comparative example, after the condensing point P is once formed by the objective lens 5, light is irradiated in a defocused state on the surface 20a that is the test surface. The amount of light incident on the foreign matter on the surface 20a can be made relatively small with respect to the amount of light incident on and reflected by 20a, and the influence of the foreign matter on the detection accuracy can be greatly reduced. By the way, in the comparative example, since the condensing point is formed on the back surface 20b of the glass substrate 20 or inside the glass substrate 20, the amount of light incident on the back surface 20b and reflected without being affected by foreign matter or the like is reflected. On the other hand, for example, the amount of light incident on a foreign substance in the glass substrate 20 or a foreign substance on the surface 20a tends to be relatively large. Thus, in the displacement detection device of the first embodiment, it is possible to detect the displacement D of the surface position of the glass substrate 20 with high accuracy while suppressing the influence of the foreign matter attached to the surface 20a of the glass substrate 20.

Specifically, in the first embodiment, the light distribution 8e formed in the four-divided sensor 8 by the reflected light from the surface 20a changes according to the occurrence of the displacement D of the surface position of the surface 20a of the glass substrate 20. The output signal S of the quadrant sensor 8 is expressed by the following equation (2). In Expression (2), Sa is a light receiving unit 8a, Sb is a light receiving unit 8b, Sc is a light receiving unit 8c, and Sd is a value corresponding to the amount of light received by the light receiving unit 8d.
S = (Sa + Sc) − (Sb + Sd) (2)

  In 1st Embodiment according to the normal design corresponding to a comparative example, it is between the output signal S of the 4-part dividing sensor 8 represented by Formula (2), and the displacement D of the surface position of the surface 20a of the glass substrate 20. The relationship shown in FIG. 7 was obtained. In FIG. 7, the horizontal axis represents the displacement D, and the vertical axis represents the output signal S of the quadrant sensor 8. Comparing FIG. 5 and FIG. 7, the S curve obtained in the first embodiment is a predetermined range centered on the origin (point of S = D = 0), similar to the S curve obtained in the comparative example. It can be seen that it has high linearity.

  In the first embodiment, in the signal processing unit 9 to which the output signal S of the quadrant sensor 8 is supplied, the moving direction of the surface 20a of the glass substrate 20 (that is, the sign of the displacement D) based on the sign of the change amount of the output signal S. ) And the amount of movement along the Z direction of the surface 20a of the glass substrate 20 (that is, the absolute value of the displacement D) is obtained based on the absolute value of the change amount of the output signal S. Specifically, the signal processing unit 9 determines the sign and absolute value of the displacement D of the surface position of the surface 20a from the initial state where the output signal S of the quadrant sensor 8 is zero, for example, and the output signal of the quadrant sensor 8. Calculation is based on the sign and absolute value of S.

More specifically, the slope (linearity) of the S curve in a predetermined range centered on the origin of the S curve of the quadrant sensor 8 is obtained in advance, for example, by measurement as the rate of change K of the signal S with respect to the change in the surface position. Based on the signal S obtained by the four-divided sensor 8, the displacement D of the surface position of the surface 20a of the glass substrate 20 is obtained by the following equation (3).
D = S × K (3)

  As in the case of the comparative example in the first embodiment, as shown in FIG. 8, the surface position of the surface 20a of the glass substrate 20 does not change (that is, the glass substrate 20 is fixed in the Z direction). When a circular foreign substance having a diameter of 30 μm moves on the surface 20a along the X direction, the relationship between the X direction position (mm) of the foreign substance center with respect to the optical axis AX and the detection error (nm) was obtained. Referring to FIG. 8, when the center of the foreign matter adhering to the surface 20a is slightly displaced from the optical axis AX, a detection error of about 5 nm at the maximum, that is, a detection error of about 1/9 of the comparative example occurs. I understand that I do not.

  By the way, in 1st Embodiment, when the glass substrate 20 which is a to-be-tested object exists, the return light (reflected light) from the surface 20a injects into each optical member of detection system DS, but glass substrate 20 exists. When not, there is no return light incident on each optical member of the detection system DS. As a result, the internal temperatures of the objective lens 5, the cylindrical lens 6, the condenser lens 7 and the like are likely to change due to the influence of the return light. In particular, when the refractive index changes due to a change in the internal temperature T of the objective lens 5 and the thermal expansion occurs, the focal length f of the objective lens 5 changes, causing a detection error.

The variation rate dF / dT of the focal length of the objective lens 5 due to the change of the temperature T is obtained as follows in consideration of the effect of thermal expansion due to the temperature change and the effect of refractive index change due to the temperature change. First, the focal length variation rate dF ₁ / dT due to the action of thermal expansion is expressed by the following equation (4). In Expression (4), α is a linear expansion coefficient of the optical material forming the objective lens 5.
dF ₁ / dT = α × f (4)

Regarding the effect of refractive index change, the relationship shown in the following equation (5) is established. Further, the relationship shown in the following equation (6) is obtained from the relationship shown in equation (5). In equations (5) and (6), n is the refractive index of the optical material forming the objective lens 5, r1 is the radius of curvature of the surface of the objective lens 5 on the side of the polarizing beam splitter 3, and r2 is the objective lens 5 This is the radius of curvature of the surface of the glass substrate 20 side.
1 / f = (n-1) (1 / r1-1 / r2) (5)
(−1 / f ² ) · df = (1 / r1-1 / r2) · dn (6)

From the equations (5) and (6), the relationship shown in the following equation (7) is obtained. From the relationship shown in the equation (7), the focal length variation rate dF ₂ / dT due to the effect of the refractive index change is expressed by the following equation (8).
df = -f / (n-1) .dn (7)
dF ₂ / dT = −f / (n−1) · (dn / dT) (8)

From the equations (4) and (8), the fluctuation rate dF / dT of the focal length of the objective lens 5 due to the temperature change is expressed by the following equation (9).
dF / dT = dF ₁ / dT + dF ₂ / dT
= Α × f−f / (n−1) · (dn / dT)
= F {[alpha]-(dn / dT) / (n-1)} (9)

Therefore, in the first embodiment, by satisfying the following conditional expression (A), the influence of the change in the internal temperature T of the objective lens 5 is reduced, and the displacement D of the surface position of the glass substrate 20 is highly accurate. Can be detected. In the conditional expression (A), dn / dT is the rate of change of the refractive index n of the optical material of the objective lens 5 with respect to the change of the temperature T, and X is the allowable fluctuation amount of the focal length f of the objective lens 5 with respect to the change of the temperature T. It is.
| F {α− (dn / dT) / (n−1)} | <X (A)

As a specific numerical example, when the focal length f of the objective lens 5 is 4 mm and the variation allowable amount X of the focal length f is 10 nm / ° C., the linear expansion coefficient α is 7.2 × 10 ⁻⁶ [1 / °. C], an optical material BK7 having a refractive index n of 1.51 for light having a wavelength λ = 790 nm and a change rate dn / dT of the refractive index n of 2.6 × 10 ⁻⁶ [1 / ° C]. When the objective lens 5 is formed, the value on the left side of the conditional expression (A) becomes 8.3 [nm / ° C], and the conditional expression (A) can be satisfied.

  If necessary, optical members such as the cylindrical lens 6 and the condensing lens 7 can also be configured to satisfy the conditional expression (A). Further, the fact that the influence of changes in the internal temperature of the objective lens 5 and the like can be reduced by satisfying conditional expression (A) is also described in the second embodiment of FIG. 9 and the modification of FIG. It is the same.

  In the first embodiment, after the condensing point P is once formed by the objective lens 5, the surface 20 a of the glass substrate 20 is irradiated with light, and is reflected by the surface 20 a and passes through the objective lens 5. The displacement of the surface position of the surface 20a is detected. However, the present invention is not limited to this. For example, as shown in the second embodiment in FIG. 9, the light from the light source LS is converged by the objective lens 5 by using, for example, the negative lens 2 a instead of the condenser lens 2. Then, the surface 20a of the glass substrate 20 as the test surface is irradiated, reflected by the surface 20a, once formed a condensing point P ′, and based on the light passing through the objective lens 5, the surface position of the surface 20a Displacement can also be detected.

  Also in the second embodiment, as in the case of the first embodiment, no light enters the inside of the glass substrate 20, for example, striae in the glass substrate 20, foreign matter, bubbles, and surface roughness of the back surface 20 b. As a result, no detection error occurs. In addition, since the surface 20a, which is the test surface, is irradiated with light in a defocused state and displacement is detected based on the reflected light from the surface 20a, the amount of light incident and reflected on the surface 20a On the other hand, the amount of light incident on the foreign matter on the surface 20a can be made relatively small, and the influence of the foreign matter on the detection accuracy can be greatly reduced.

  As a result, also in the displacement detection apparatus according to the second embodiment, it is possible to detect the displacement D of the surface position of the glass substrate 20 with high accuracy while suppressing the influence of foreign matter attached to the surface 20a of the glass substrate 20. In the first embodiment, the collimating lens 1 and the condenser lens 2 can be replaced with one positive lens. Similarly, in the second embodiment, the collimating lens 1 and the negative lens 2a can be replaced with one positive lens.

  Further, in each of the above-described embodiments, the cylindrical lens 6 as an aberration generating member that generates astigmatism in the light that has passed through the polarization beam splitter 3, and the photoelectric conversion unit that photoelectrically converts the reflected light from the surface 20a of the glass substrate 20. The displacement of the surface position of the surface 20a, which is the test surface, is detected by the astigmatism method. 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. 10 and FIG. 11, the structural example of the displacement detection apparatus which detects the displacement of the surface position of the surface of a glass substrate by a knife edge method is demonstrated. The modification of FIG. 10 has a configuration similar to that of the first embodiment of FIG. 1, but a light shielding member disposed on the rear side of the condensing lens 6 instead of the cylindrical lens 6 disposed on the front side of the condensing lens 6. 10 is used, and the two-divided sensor 11 is used instead of the four-divided sensor 8, which is different from the first embodiment. Hereinafter, the configuration and operation of the modified example of FIG. 10 will be described with a focus on differences from the first embodiment.

  In the modification of FIG. 10, the light that passes through the condenser lens 7 enters the light shielding member 10. The light blocking 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 blocking a portion of the incident light in the + X direction from the optical axis AX. As shown in FIG. 11, the two-divided sensor 11 has two light receiving portions 11 a and 11 b that are equally divided by a linear region extending in the Y direction. In other words, the two light receiving portions 11 a and 11 b are arranged symmetrically with respect to a line segment that passes through the center point of the two-divided sensor 11 and extends in the Y direction.

In the modification of FIG. 10, the light distribution 11 c formed by the reflected light from the surface 20 a on the two-divided sensor 11 changes according to the occurrence of the displacement D of the surface position of the surface 20 a of the glass substrate 20. The output signal S1 of the two-divided sensor 11 is expressed by the following equation (10). In Expression (10), S1a is a value corresponding to the amount of light received by the light receiving unit 11a, and S1b is a value corresponding to the amount of light received by the light receiving unit 11b.
S1 = S1a-S1b (10)

  In the modified example of FIG. 10, for example, as in the case of the first embodiment, the surface position of the glass substrate 20 is suppressed by using the above-described formula (3) and suppressing the influence of foreign matters attached to the surface 20 a of the glass substrate 20. Can be detected with high accuracy. Although not shown, the knife edge method can be applied to the basic configuration of the second embodiment shown in FIG.

  In the above-described embodiment and modification, polarization separation is performed as a light guide member that reflects light from the light source to guide the test surface and transmits reflected light from the test surface to guide the photoelectric conversion unit. A polarizing beam splitter 3 having a surface 3a is used. However, the present invention is not limited to this, and various forms are possible for this type of light guide member. For example, an amplitude-dividing beam splitter that does not have a polarization separation surface can be used as this type of light guide member.

  In general, a polarization type or amplitude division type beam splitter reflects or transmits light from a light source and guides it to a test surface, and transmits or reflects reflected light from the test surface and guides it to a photoelectric conversion unit. be able to. 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. However, in this case, if necessary, the light amount change of the light source can be monitored by 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.

  Moreover, in the above-mentioned embodiment and modification, in the state which fixed the apparatus, the displacement of the surface position of the 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.

  Moreover, in the above-mentioned embodiment and modification, although this invention was demonstrated taking the example of the displacement detection apparatus which detects the displacement of the surface position of the surface 20a of the glass substrate 20, it is not limited to this, Other than a glass substrate The present invention can be similarly applied to detection of displacement of the surface of an object. In other words, various forms are possible for the application example of the displacement detection device according to the first embodiment of FIG. 1, the second embodiment of FIG. 9, 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 detection of the displacement of the surface position of the surface of the substrate stage in the exposure apparatus will be described with reference to FIG. The exposure apparatus in FIG. 12 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 this embodiment includes one or a plurality of displacement detection devices 60 for detecting the displacement of the surface position of the surface of a Z stage (substrate stage) 62 that supports a wafer (photosensitive substrate) W. . The displacement detection device 60 has the same configuration as the device according to the first embodiment of FIG. 1, the second embodiment of FIG. 9, 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 detects the displacement of the surface position of the surface of the glass substrate for an optical encoder provided on the substrate stage. As a result, the displacement of the surface position of the surface of the substrate stage is detected.

  Next, a device manufacturing method using the exposure apparatus according to the embodiment of FIG. 12 will be described. FIG. 13 is a flowchart showing a semiconductor device manufacturing process. As shown in FIG. 13, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a semiconductor device substrate (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. 14 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 14, in the liquid crystal device manufacturing process, 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 displacement detection apparatus concerning the comparative example corresponding to 1st Embodiment. It is a figure which shows roughly the structure of the 4-part dividing sensor in a comparative example. It is a figure which shows the relationship between the output signal of the 4-part dividing sensor in a comparative example, and the displacement of the surface position of a to-be-tested surface. It is a figure which shows the relationship between the center position of the foreign material in a comparative example, and a detection error. It is a figure which shows the relationship between the output signal of the 4-part dividing sensor in 1st Embodiment, and the displacement of the surface position of a to-be-tested surface. It is a figure which shows the relationship between the center position of the foreign material in 1st Embodiment, and a detection error. It is a figure which shows schematically the structure of the displacement detection apparatus concerning 2nd Embodiment of this invention. It is a figure which shows the modification which applied the knife edge method with respect to the basic composition of 1st Embodiment of FIG. It is a figure which shows roughly the structure of the 2 division | segmentation sensor 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 system DS Detection system 2, 7 Condensing lens 3 Polarizing beam splitter 4 1/4 wavelength plate 5 Objective lens 6 Cylindrical lens 8 Quad sensor 9 Signal processing unit 11 Split sensor 20 Glass substrate 20a Surface of glass substrate

Claims (11)

In the displacement detection device that detects the displacement of the surface position of the test surface,
An irradiation system for irradiating the surface of the object as the test surface after forming a condensing point once by an objective lens based on light from a light source,
A displacement detection apparatus comprising: a detection system that detects a displacement of a surface position of the test surface based on light reflected by the test surface and passed through the objective lens. In the displacement detection device that detects the displacement of the surface position of the test surface,
An irradiation system for converging light from a light source by an objective lens and irradiating the surface of the object as the test surface;
A displacement system comprising: a detection system that forms a condensing point once reflected by the test surface and detects a displacement of a surface position of the test surface based on light that has passed through the objective lens. Detection device. The focal length of the objective lens is f, the linear expansion coefficient of the optical material forming the objective lens is α, the change rate of the refractive index n of the optical material with respect to the change of the temperature T is dn / dT, and the temperature T When the fluctuation tolerance of the focal length f with respect to the change is X,
| F {α− (dn / dT) / (n−1)} | <X
The displacement detection device according to claim 1, wherein the following condition is satisfied. The irradiation system includes a beam splitter that reflects or transmits light from the light source and guides the light to the objective lens,
The displacement detection device according to claim 1, wherein the detection system includes a photoelectric conversion unit that photoelectrically converts light transmitted or reflected by the beam splitter. The displacement detection apparatus according to claim 4, wherein the photoelectric conversion unit includes a quadrant sensor. 6. The detection system according to claim 5, further comprising 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 light that has passed through the beam splitter. The displacement detection device described. The detection system has a light blocking member that partially blocks light that has passed through the beam splitter,
The displacement detection apparatus according to claim 4, wherein the photoelectric conversion unit 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 surface 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.

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