JP2008177206A - Substrate holder, surface shape measuring device and stress measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To hold a substrate while preventing deformation in a substrate holder and a surface shape measuring device and a stress measuring device having the substrate holder. <P>SOLUTION: The substrate holding mechanism 20 of a stress measuring device has a portion 201 for supporting a substrate 9 from below without touching by jetting gas on the lower surface 91 side of the substrate 9, and a cylindrical movement regulating portion 202 for regulating movement of the substrate 9 supported by the supporting portion 201 by abutting against the side face of the substrate 9. The supporting portion 201 has a disklike porous member 203 opposing the lower surface 91 of the substrate 9, and the substrate holding mechanism 20 supports the surface of the substrate 9 without touching the supporting portion 201 by jetting gas substantially uniformly and entirely from the upper surface 2031 of the porous member 203. Consequently, the substrate 9 can be held while preventing deformation thereoff. As a result, the surface shape of the substrate 9 can be determined with high precision and the stress in a film on the substrate 9 can be measured with high precision. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a substrate holding device that holds a substrate, and a surface shape measuring device and a stress measuring device including the substrate holding device.

  Conventionally, in the manufacture of semiconductor elements, the surface of a semiconductor substrate (hereinafter simply referred to as “substrate”) has been inspected. In an inspection apparatus that performs such inspection, one of the holding portions that hold the substrate is used. A substrate holding unit that sucks and holds the substrate is used. For example, in the substrate holding part of Patent Document 1, the substrate is placed on a holding member having a concentric flow path formed on the upper surface, and the air in the flow path is sucked by a compressor so that the substrate is held by the holding member. Adsorbed on the top surface.

  Further, as shown in Patent Document 2, a non-contact support device that supports a substrate in a non-contact manner on a floating table that ejects pressurized air is also known. In the non-contact support device, a plurality of ventilation holes penetrating the floating table are formed, and pressurized air is jetted from the upper surface of the floating table through these ventilation holes. Further, in the non-contact support device, an elongated rectangular bearing member is sandwiched between two rectangular floating tables, and the bearing members are provided on both sides of the elongated negative pressure groove for suction and the negative pressure groove. And an elongated rectangular porous body for generating static pressure.

  When the substrate is supported by the non-contact support device, the substrate is supported in a non-contact manner by the pressurized air ejected from the plurality of vent holes of the floating table. Then, above the bearing member between the two levitation tables, the static pressure bearing for the substrate is harmonized with the negative pressure due to the suction of air from the negative pressure groove and the static pressure due to the pressurized air ejected from the porous body. Stiffness is increased.

On the other hand, Patent Document 3 discloses a technique for forming an adsorption surface of an adsorption plate with a thin porous sheet of ultrahigh molecular weight polyethylene in an apparatus that adsorbs and conveys a substrate.
JP 2004-103921 A JP 2004-152941 A JP 2002-173250 A

  By the way, a substrate on which various processes such as film formation and annealing are performed has warping, inclination, and the like, and is not completely flat. For this reason, if a board | substrate is adsorbed and hold | maintained like the board | substrate holding part of patent document 1, a board | substrate will deform | transform slightly.

  Moreover, in the non-contact support apparatus of patent document 2, since the center of a board | substrate is supported in the state bent by pulling a board | substrate toward the negative pressure groove side above a negative pressure groove, the said non-contact support apparatus Is used as a substrate holding part of an apparatus or the like for measuring the surface shape of the substrate, an accurate measurement result cannot be obtained. Further, since the portions other than the center of the substrate are also supported by the non-uniform pressurized air ejected from the plurality of vent holes, the substrate may be deformed.

  The present invention has been made in view of the above problems, and an object thereof is to hold a substrate while preventing the deformation of the substrate.

  The invention according to claim 1 is a substrate holding device for holding a substrate, wherein a portion excluding the entire substrate or an outer edge portion is ejected from a porous member having a flat surface facing the lower surface of the substrate. And a movement restricting portion that abuts against a side surface of the substrate supported by the support portion and restricts movement of the substrate in a direction parallel to the lower surface.

  A second aspect of the present invention is the substrate holding device according to the first aspect, wherein the flat surface of the porous member faces the entire lower surface of the substrate.

  A third aspect of the present invention is the substrate holding device according to the first or second aspect, wherein the substrate is adsorbed to the support portion by sucking a gas through the porous member.

  A fourth aspect of the present invention is the substrate holding apparatus according to any one of the first to third aspects, wherein the substrate is a semiconductor substrate.

  A fifth aspect of the present invention is the substrate holding device according to any one of the first to third aspects, wherein the substrate is a glass substrate for a flat display device.

  The invention according to claim 6 is a surface shape measuring device for measuring the surface shape of the substrate, and holds the substrate by the substrate holding device according to any one of claims 1 to 5 and the substrate holding device. A shape measuring unit configured to measure the shape of the upper surface of the substrate in a non-contact state in a state where the lower surface of the substrate is not in contact with the plane of the porous member.

  The invention according to claim 7 is a stress measuring device for measuring stress in the film on the substrate, and holds the substrate, and the substrate holding device according to any one of claims 3 to 5 The shape measurement unit for measuring the shape of the upper surface of the substrate in a non-contact state in a state where the lower surface of the substrate is not in contact with the plane of the porous member, and the shape measurement unit A curvature radius calculation unit for obtaining a curvature radius of a stress measurement region on the upper surface based on the shape of the upper surface of the substrate, and the lower surface of the substrate is adsorbed to the flat surface of the porous member by the substrate holding device A film thickness measurement unit that optically measures the thickness of the film on the upper surface of the substrate, and a curvature radius and a film thickness in the stress measurement region obtained by the curvature radius calculation unit and the film thickness measurement unit. Base There and a stress calculation unit for obtaining the stress in said film in the stress measurement area.

  In the present invention, the substrate can be held while preventing deformation of the substrate. In the invention of claim 2, the deformation of the substrate can be prevented over the entire substrate. In the invention of claim 3, the substrate can be held in a flat state.

  In the invention of claim 6, the surface shape of the substrate can be obtained with high accuracy. In the invention of claim 7, the stress in the film on the substrate can be obtained with high accuracy.

  FIG. 1 is a diagram showing a configuration of a stress measuring apparatus 1 according to the first embodiment of the present invention. The stress measuring apparatus 1 is an apparatus for measuring stress in a film formed on a main surface of a substantially disk-shaped semiconductor substrate 9 (hereinafter simply referred to as “substrate 9”). The film may be a single layer film or a multilayer film. In the present embodiment, a pattern such as a wiring pattern is not formed on the substrate 9.

  As shown in FIG. 1, the stress measuring apparatus 1 includes a substrate holding mechanism 20 that holds a substrate 9, a moving mechanism 21 that moves the substrate holding mechanism 20 in the X direction and the Y direction in FIG. 1, and a substrate holding mechanism 20. 1, an elevating mechanism 24 that moves up and down in the Z direction, an ellipsometer 3 that acquires information used for polarization analysis on the film on the substrate 9, an optical interference unit 4 that acquires the spectral intensity of the reflected light from the substrate 9, and these The control part 5 which controls the structure of is provided.

  FIG. 2 is a diagram illustrating a configuration of the control unit 5. As shown in FIG. 2, the control unit 5 includes a CPU 51 that performs various arithmetic processes, a RAM 52 that stores programs to be executed or a work area for arithmetic processes, a ROM 53 that stores basic programs, as in a normal computer. A fixed disk 54 for storing various types of information, a display 55 for displaying various types of information to an operator, and an input unit 56 such as a keyboard and a mouse are connected.

  FIG. 3 is a block diagram showing functions realized by the CPU 51 (see FIG. 2) and the like of the control unit 5 performing arithmetic processing according to a program together with other configurations. The gradient vector calculating unit 511 and the surface in FIG. The shape calculation unit 512, the curvature radius calculation unit 513, the stress calculation unit 514, the first film thickness calculation unit 515, and the second film thickness calculation unit 516 correspond to functions realized by the CPU 51 and the like. Note that these functions may be realized by a plurality of computers.

  FIG. 4 is a plan view showing the substrate holding mechanism 20. As shown in FIG. 4, the substrate holding mechanism 20 is circular in plan view. FIG. 5 is a longitudinal sectional view showing the substrate holding mechanism 20. FIG. 5 shows a cross section in a plane including the central axis of the substrate holding mechanism 20. FIG. 5 also shows the substrate 9 held by the substrate holding mechanism 20.

  As shown in FIGS. 4 and 5, the substrate holding mechanism 20 supports the substrate 9 in a non-contact manner from below by ejecting gas (for example, pressurized air) on the lower surface 91 side of the substrate 9. And a cylindrical movement restricting portion 202 that abuts against the side surface of the substrate 9 supported by the support portion 201 and restricts the movement of the substrate 9.

  As shown in FIG. 5, the support portion 201 includes a disk-shaped porous member 203 having a circular plane 2031 (hereinafter referred to as “upper surface 2031”) facing the lower surface 91 of the substrate 9, and a porous member on the upper portion. The base part 204 to which 203 is attached is provided. A circular concave portion is formed on the upper side of the base portion 204 in plan view, and the internal space 205 is formed by closing the concave portion with the porous member 203.

  A vacuum suction port 2041 and a gas supply port 2042 communicating with the internal space 205 are formed on the lower side of the base portion 204, and the internal space 205 is exhausted through a vacuum suction port 2041 and a pipe 2043 (not shown). Connected to the device. The internal space 205 is connected to a gas supply device (not shown) via a gas supply port 2042 and a pipe 2044.

  The porous member 203 is made of porous ceramic, porous stainless steel, or the like. Further, other metal-based porous materials other than stainless steel and plastic-based porous materials may be used as the porous member 203. The porosity of the porous member 203 is preferably 1% or more and 10% or less (more preferably 3% or more and 5% or less).

  In the stress measuring device 1, the valve (not shown) provided in the pipe 2043 is closed, and the valve (not shown) provided in the pipe 2044 is opened, and the pipe 2044 and the gas supply port 2042 are opened from the gas supply device. By supplying the gas to the internal space 205 via the gas, the gas is ejected from the entire upper surface 2031 of the porous member 203 approximately uniformly. As a result, a gas layer is formed between the lower surface 91 of the substrate 9 and the upper surface 2031 of the porous member 203, and the substrate 9 is brought out of contact with the porous member 203 of the support portion 201 through the gas layer. The surface is supported.

  In the substrate holding mechanism 20, since the upper surface 2031 of the porous member 203 faces the entire lower surface 91 of the substrate 9, the entire substrate 9 is supported by the support unit 201 from below without contact. The movement of the substrate 9 in the direction parallel to the lower surface 91 (that is, the direction parallel to the upper surface 2031 of the porous member 203) is regulated by the side surface of the substrate 9 coming into contact with the inner surface of the movement restricting portion 202. Is done. The movement restricting portion 202 is merely in contact with the side surface of the substrate 9 and does not substantially support the weight of the substrate 9 on the side surface. Further, the movement restricting portion 202 does not necessarily have a cylindrical shape, and is, for example, three or more pins arranged at an equal pitch on a circumference centered on the central axis of the substrate holding mechanism 20. Also good.

  By the way, in the stress measuring apparatus 1, the substrate 9 can be sucked and held by the substrate holding mechanism 20. When the substrate 9 is adsorbed, the substrate 9 is placed on the upper surface 2031 of the porous member 203, the valve provided in the pipe 2044 is closed, and the valve provided in the pipe 2043 is opened. The device is driven. Then, gas is sucked through the pipe 2043, the vacuum suction port 2041, the internal space 205, and the porous member 203, so that the substrate 9 is adsorbed on the upper surface 2031 of the porous member 203 of the support portion 201.

  As shown in FIG. 1, the moving mechanism 21 includes an X-direction moving mechanism 22 that moves the substrate holding mechanism 20 in the X direction in FIG. 1, and a Y-direction moving mechanism 23 that moves in the Y direction. In the X-direction moving mechanism 22, a ball screw (not shown) is connected to the motor 221, and when the motor 221 rotates, the Y-direction moving mechanism 23 moves along the guide rail 222 in the X direction in FIG. The Y-direction moving mechanism 23 has the same configuration as the X-direction moving mechanism 22. When the motor 231 rotates, the substrate holding mechanism 20 moves in the Y direction along the guide rail 232 by a ball screw (not shown). In the stress measuring apparatus 1, the irradiation region of the light irradiated onto the substrate 9 from the ellipsometer 3 and the optical interference unit 4 is moved relative to the substrate 9 by the moving mechanism 21.

  The ellipsometer 3 receives the reflected light of the polarized light from the light source unit 31 that emits polarized light (hereinafter referred to as “polarized light”) toward the substrate 9, and the polarized light from the substrate 9, and changes the polarization state of the reflected light. The light receiving unit 32 to be acquired is provided, and data indicating the acquired polarization state is output to the control unit 5.

  The light source unit 31 includes a semiconductor laser (LD) 312 that is a light source that emits a light beam, an LD drive control unit 311 that controls the output of the semiconductor laser 312, a polarizing filter 313, and a wavelength plate (hereinafter referred to as “λ / 4 plate”). ”) 314. In the ellipsometer 3, the light beam emitted from the semiconductor laser 312 of the light source unit 31 enters the polarization filter 313, and linearly polarized light is extracted by the polarization filter 313. The light from the polarization filter 313 enters the λ / 4 plate 314, is converted into circularly polarized light by the λ / 4 plate 314, and passes through the lens 331 at a predetermined incident angle (for example, 72 ° to 80 °). It is guided to the surface of the substrate 9 on the substrate holding mechanism 20. The light source unit 31 (specifically, on the optical path between the semiconductor laser 312 and the polarization filter 313) is provided with an electromagnetic shutter 315 that blocks the light beam. Light irradiation is ON / OFF controlled.

  The light receiving unit 32 includes a rotation analyzer 321 and a photodiode 322. In the ellipsometer 3, the reflected light of the light emitted from the light source unit 31 to the substrate 9 is guided to the rotation analyzer 321 through the lens 332, and the rotation analyzer 321 that rotates about an axis parallel to the optical axis is used. The light is transmitted and received by the photodiode 322. A signal indicating the intensity of light received by the photodiode 322 is output to the first film thickness calculation unit 515 (see FIG. 3) of the control unit 5 via the AD converter 34, and the output of the photodiode 322 is rotated. By associating with the rotation angle of the photon 321, the polarization state of the reflected light is acquired.

  In the stress measuring apparatus 1, a mirror 25 used for confirming the wavelength of light from the light source unit 31 of the ellipsometer 3 is attached to the side of the substrate holding mechanism 20, and the mirror 25 is irradiated from the light source unit 31 to a predetermined level. Are inclined so as to reflect light at an incident angle of above in the vertical direction.

  The light interference unit 4 includes a light source 41 that emits white light as illumination light, a spectroscope 42 that separates reflected light from the substrate 9, a light-shielding pattern imaging unit 43 that acquires a light-shielding pattern image to be described later, and illumination on the substrate 9 A substrate imaging unit 44 that captures an irradiation position of light and an optical system 45, and the illumination light from the light source 41 is guided to the irradiation region on the substrate 9 by the optical system 45 and reflected light from the irradiation region. Is guided to the spectroscope 42, the light shielding pattern imaging unit 43, and the substrate imaging unit 44.

  Specifically, illumination light from the light source 41 is introduced into one end of the optical fiber 451, and illumination light is derived from a lens 452 provided at the other end. The derived illumination light is guided to the aperture stop 453 through the lens 450a. The aperture stop 453 is provided with a predetermined light shielding pattern 453a (for example, a marked line formed in a cross shape), and the illumination light is blocked by the field stop through the lens 450b while the portion corresponding to the light shielding pattern 453a is shielded. 454.

  The illumination light whose field of view is limited by the field stop unit 454 is guided to the half mirror 455 through the lens 450c, and is transmitted to the half mirror 456 through the half mirror 455. The illumination light reflected by the half mirror 456 is applied to the irradiation area on the substrate 9 through the objective lens 457. At this time, the width of the illumination light irradiation region on the substrate 9 corresponds to the field limitation by the field stop unit 454, but the image of the light shielding pattern 453a of the aperture stop unit 453 is not formed on the substrate 9. In the stress measuring apparatus 1, an objective lens 457 having a low magnification (10 times in this embodiment) is used, and the objective lens 457 has a relatively large focal depth of about 4 μm. Is substantially parallel light on the substrate 9.

  Reflected light from the substrate 9 is guided to the half mirror 456 via the objective lens 457, and a part of the light is reflected toward the half mirror 455. The reflected light is further reflected by the half mirror 455 and received by the light shielding pattern imaging unit 43 via the lens 450d. In the optical system from the light shielding pattern 453 a to the light shielding pattern imaging unit 43 via the surface of the substrate 9, the position of the light shielding pattern imaging unit 43 is optically conjugate with the light shielding pattern 453 a, and the light shielding pattern imaging unit 43 has a light shielding pattern. The image 453a is formed, and the image data of the light shielding pattern 453a is output to the inclination vector calculation unit 511 (see FIG. 3) of the control unit 5.

  The reflected light transmitted through the half mirror 456 is transmitted through the half mirror 458 and guided to the half mirror 459, and a part of the light is reflected. The reflected light is guided to the substrate imaging unit 44 through the lens 450e and received. Since the position of the substrate imaging unit 44 is optically conjugate with the position of the surface of the field stop unit 454 and the substrate 9, an image of the irradiation position of the illumination light on the substrate 9 is captured and acquired by the substrate imaging unit 44. The image data is output to the control unit 5.

  The light transmitted through the half mirror 459 is guided to the spectroscope 42 through the lens 450f. In the optical interference unit 4, the reflected light from the irradiation region on the substrate 9 of the light from the light source 41 is received by the spectroscope 42 which is a light receiving unit, and the spectral intensity of the reflected light is acquired. The data is output to the second film thickness calculation unit 516 (see FIG. 3) of the control unit 5. In the optical interference unit 4, the lenses 450 a to 450 f and 452, the optical fiber 451, the aperture stop 453, the field stop 454, the half mirrors 455 456 458 and 459, and the objective lens 457 constitute an optical system 45.

  Next, the flow of measuring the stress in the film on the substrate 9 by the stress measuring device 1 will be described. In the stress measurement apparatus 1, the optical interference unit 4 determines the shape of the upper surface 92 (see FIG. 5) of the substrate 9 (hereinafter referred to as “surface shape”) and the curvature radius of the stress measurement region on the substrate 9. The thickness of the film in the stress measurement region (hereinafter referred to as “film thickness”) is obtained by the ellipsometer 3 or the optical interference unit 4. And the stress in a stress measurement area | region is calculated | required based on these curvature radii and film thickness, and the thickness of the board | substrate 9. FIG.

  In the stress measurement device 1, the optical interference unit 4, the inclination vector calculation unit 511 and the surface shape calculation unit 512 of the control unit 5 are shape measurement units that measure the surface shape of the substrate 9 in a non-contact manner. The ellipsometer 3 and the first film thickness calculation unit 515 of the control unit 5 serve as a film thickness measurement unit that optically measures the thickness of the film on the substrate 9, and the optical interference unit 4 and the second film thickness calculation unit. The calculation unit 516 is another film thickness measurement unit that optically measures the thickness of the film on the substrate 9. When the film on the substrate 9 is relatively thin, the second film thickness calculation unit 516 performs film thickness measurement by the ellipsometry based on the output indicating the polarization state from the ellipsometer 3, and the film is relatively thick. Alternatively, in the case of a multilayer film, the first film thickness calculation unit 515 calculates the film thickness by optical interference while obtaining the spectral reflectance based on the output indicating the spectral intensity from the optical interference unit 4.

  FIG. 6 is a diagram showing a flow of stress measurement by the stress measurement apparatus 1. When the stress in the film on the substrate 9 is measured by the stress measuring device 1 shown in FIG. 1, first, the substrate 9 is placed on the support portion 201 of the substrate holding mechanism 20 shown in FIG. Gas is supplied from the apparatus to the internal space 205 of the substrate holding mechanism 20, and the gas is ejected from the entire upper surface 2031 of the porous member 203. Thus, the substrate 9 is held by the substrate holding mechanism 20 in a state where the lower surface 91 of the substrate 9 is not in contact with the upper surface 2031 of the porous member 203 (step S11).

  Subsequently, the focus is set so that the reference region set on the upper surface 92 of the substrate 9 (that is, a region serving as a reference in the measurement of the surface shape of the substrate 9) is located within the depth of focus of the objective lens 457 shown in FIG. Adjustments are made. In the present embodiment, focus adjustment of the substrate 9 is performed by manually operating the elevating mechanism 24 while visually confirming the image of the reference region of the substrate 9 through the optical system 45.

  When the focus adjustment is completed, the movement of the substrate holding mechanism 20 and the substrate 9 by the moving mechanism 21 is started. Then, the light from the light source 41 of the optical interference unit 4 is a predetermined region on the substrate 9 via the optical system 45 having the objective lens 457 (a region where an inclination vector is obtained as will be described later. In this case, the reflected light from the irradiated area is guided to the light-shielding pattern imaging unit 43 via the objective lens 457, and an image of the light-shielding pattern 453a is acquired. The image data of the light shielding pattern 453a acquired by the light shielding pattern imaging unit 43 is output to the inclination vector calculation unit 511 (see FIG. 3) of the control unit 5.

  As described above, the position of the light-shielding pattern imaging unit 43 is optically conjugate with respect to the light-shielding pattern 453a via the surface of the substrate 9 (since the light-shielding pattern 453a is located almost at the aperture stop position. The light-shielding pattern imaging unit 43 is substantially located at a so-called objective pupil position.) The position of the light-shielding pattern in the image acquired by the light-shielding pattern imaging unit 43 is a method of the illumination light irradiation area of the substrate 9. The position corresponds to the line direction (hereinafter referred to as “tilt vector”).

  The inclination vector calculation unit 511 stores in advance the barycentric position (hereinafter referred to as “reference position”) of the light shielding pattern in the image when the inclination vector faces the vertical direction (that is, the Z direction). By calculating a vector reaching the center of gravity of the light shielding pattern in the acquired image as a starting point, an inclination vector in the irradiation region of the substrate 9 is obtained.

  Specifically, the distance between the objective lens 457 and the surface of the substrate 9 is f, the angle between the vertical direction and the tilt vector (hereinafter referred to as “tilt angle”) is θ, and the position of the objective lens 457 is set. Assuming that the reflected light from the substrate 9 is received and an image of the light shielding pattern 453a is obtained, the position of the light shielding pattern in the acquired image is the direction corresponding to the inclination from the time when the inclination angle of the substrate 9 is 0 °. (F × tan (2θ)).

  Therefore, the image acquired by the light-shielding pattern imaging unit 43 moves in a direction corresponding to the inclination by a distance obtained by multiplying (f × tan (2θ)) by the magnification with respect to the position of the objective lens 457. The direction is the distance and direction between the reference position and the detected center of gravity position. In the tilt vector calculation unit 511, the substrate 9 is calculated based on the vector from the reference position obtained from the output from the light-shielding pattern imaging unit 43 to the center of gravity and the distance f between the objective lens 457 and the surface of the substrate 9. Are accurately determined.

  A plurality of inclination vector measurement areas are set on the substrate 9, and the irradiation area of the light from the light source 41 is moved relative to the substrate 9 by the moving mechanism 21 to the next inclination vector measurement area. Head to. In the stress measuring apparatus 1, the relative movement of the light irradiation region from the light source 41 with respect to the substrate 9 is continuously performed, and light irradiation and light shielding are performed on a plurality of tilt vector measurement regions on the substrate 9. The acquisition of the image of the pattern 453a and the calculation of the inclination vector of the substrate 9 are sequentially repeated (step S12).

  In the stress measurement apparatus 1, since the depth of focus of the objective lens 457 is relatively large, the tilt vector measurement region on the substrate 9 is a reference region (that is, focus adjustment is performed) with respect to the vertical direction (that is, the Z direction in FIG. 1). Even if it is slightly deviated from the image area), if it is located within the range of the focal depth of the objective lens 457, the imaging relationship between the light shielding pattern 453a and the light shielding pattern imaging unit 43 is affected. Therefore, the image of the light shielding pattern 453a can be acquired with high accuracy.

  Further, since the light guided from the objective lens 457 to the substrate 9 is substantially parallel light on the substrate 9, even if the tilt vector measurement region is slightly deviated from the focus depth range, the light shielding pattern 453a. Can be acquired with high accuracy. Thereby, when measuring the inclination vector in each of the plurality of inclination vector measurement areas on the substrate 9, it is possible to perform the measurement quickly and with high accuracy without performing the focus adjustment in each inclination vector measurement area.

  In the optical interference unit 4, the light shielding pattern 453 a and the light shielding pattern imaging unit 43 are optically conjugate, but the light shielding pattern 453 a and the substrate 9 are not conjugate, and the image of the light shielding pattern 453 a is the substrate. No image is formed on 9. For this reason, even when a wiring pattern or the like is formed on the substrate 9, the image of the light shielding pattern 453 a acquired by the light shielding pattern imaging unit 43 is not affected by the wiring pattern or the like on the substrate 9. As a result, regardless of the presence or absence of a wiring pattern or the like on the substrate 9, various types of inclination vectors of the substrate can be obtained easily and with high accuracy.

  When the calculation of the tilt vectors in all the tilt vector measurement regions is completed, the movement of the substrate 9 by the moving mechanism 21 is stopped. Then, based on the inclination vectors of the substrate 9 in the plurality of inclination vector measurement regions on the substrate 9 obtained by the inclination vector calculation unit 511 by the surface shape calculation unit 512 (see FIG. 3) of the control unit 5, A surface shape is obtained (step S13).

Specifically, the height of the reference area (that is, the coordinate value in the Z direction in FIG. 1), which is one of the plurality of inclination vector measurement areas, is Za, and is adjacent to the reference area and the reference area in the X direction. The horizontal distance (that is, the distance in the X direction) from one tilt vector measurement area (hereinafter referred to as “adjacent area”) to be L is L, and the tilt vector of the substrate 9 in each of the reference area and the adjacent area The height Zb of the adjacent region can be obtained by the following equation (1) where θ _a and θ _b are angles formed by the projection of Z on the ZX plane and the Z direction.

(Equation 1)
Zb = Za + (sin θ _a + sin θ _b ) L / 2

  In the surface shape calculation unit 512, the height of each inclination vector measurement region is set to the inclination vector of the substrate 9 in the inclination vector measurement region, and the height and inclination vector of the inclination vector measurement region adjacent to the inclination vector measurement region. Based on this, the calculation is sequentially performed in the order from the reference area.

  The height of one inclination vector measurement region may be an average value of heights obtained through a plurality of paths. For example, the heights of a plurality of inclination vector measurement areas located on a straight line extending in the X direction through an inclination vector measurement area (hereinafter referred to as “calculation target area”) whose height is to be calculated are set as reference areas (or In this case, the height of the calculation target area is calculated in order from the closest (inclination vector measurement area whose height has already been obtained) to obtain the height of the calculation target area, and a plurality of inclination vector measurements positioned on a straight line extending in the Y direction through the calculation target area The height of the area is sequentially calculated from the reference area (or the gradient vector measurement area for which the height has already been obtained) in order from the nearest area to obtain the height of the calculation target area, and the average value of the two obtained heights is It may be the height of the calculation target area.

  In the stress measuring apparatus 1, the reference substrate is brought into non-contact by the substrate holding mechanism 20 with respect to a reference substrate having a flat surface shape (in this embodiment, a substrate on which no film is formed is used). The surface shape measurement process (steps S11 to S13) similar to the above is performed in advance, and the height of the region on the reference substrate corresponding to each inclination vector measurement region of the substrate 9 is obtained. Is stored in the surface shape calculation unit 512.

  The surface shape calculation unit 512 subtracts the heights of the plurality of inclination vector measurement regions of the reference substrate stored in advance from the heights of the plurality of inclination vector measurement regions of the substrate 9 and then the plurality of inclinations of the substrate 9. The height of the area between the vector measurement areas is interpolated by spline interpolation, Bezier interpolation or the like, and the surface shape of the substrate 9 is obtained. Thus, by correcting the height of the inclination vector measurement region of the substrate 9 using the measurement result of the reference substrate, the systematic error of the stress measuring device 1 is corrected and the surface shape of the substrate 9 is obtained with high accuracy. Can do.

  FIG. 7 is a diagram showing the surface shape of the substrate 9. In FIG. 7, the surface shape obtained from the heights of the plurality of gradient vector measurement regions set on the diameter of the disk-shaped substrate 9 is indicated by a solid line 901. As shown in FIG. 7, the substrate 9 is warped upward at the portions on both sides in the diametrical direction (that is, both the left and right sides in FIG. 7) that are measured.

  In FIG. 7, a measurement result of the surface shape of the substrate 9 by another measuring apparatus of the comparative example is indicated by a broken line 902. In the measurement apparatus of the comparative example, the surface shape is measured in a state where the substrate 9 is adsorbed by the adsorption stage. In the measurement device of the comparative example, a part within a radius of 60 mm from the center of the substrate 9 (that is, a part within a range of −60 mm to +60 mm in FIG. 7) is adsorbed by the adsorption stage. Yes. The method of obtaining the inclination vector of each inclination vector measurement region in the measurement device of the comparative example is the same as the method of obtaining the stress measurement device 1 according to the present embodiment.

  As shown in FIG. 7, in the measurement result by the measurement apparatus of the comparative example, the portion adsorbed on the adsorption stage of the substrate 9 is approximately flat unlike the actual shape. The surface shape corresponding to the actual shape of 9 is measured with high accuracy. Although not depicted in FIG. 7, when the substrate 9 having such a shape is not adsorbed and is simply placed on the stage, only the portion near the center of the substrate 9 is supported by the stage. Then, the substrate 9 is deformed so that the portions on both sides in the diameter direction of the substrate 9 hang downward (that is, the warpage of the substrate 9 is reduced). Therefore, even when the substrate 9 is placed on the stage without being attracted, it is difficult to measure the surface shape of the substrate 9 with high accuracy.

  When the surface shape of the substrate 9 is measured, the curvature radius calculating unit 513 (see FIG. 3) of the control unit 5 (for example, calculating the surface shape) based on the surface shape near the stress measurement region set on the substrate 9. Based on the height of the stress measurement region obtained by the part 512 and the heights of the four points around the stress measurement region), the radius of curvature of the stress measurement region is obtained (step S14).

  In addition, when it is known in advance that the curvature of the part in the cross section cut by the ZX plane in the vicinity of the stress measurement region is substantially equal to the curvature of the part in the cross section cut by the ZY plane, the stress measurement is performed. The radius of curvature of the region may be obtained based on, for example, the height of the stress measurement region and the heights of two points located on both sides of the stress measurement region in the X direction. The stress measurement region may coincide with the plurality of inclination vector measurement regions on the substrate 9 or may be set between the plurality of inclination vector measurement regions. In addition, a plurality of stress measurement regions may be set on the substrate 9.

  When the radius of curvature of the stress measurement region is obtained (or in parallel with the calculation of the radius of curvature), the gas supply device is stopped, and the gas from the upper surface 2031 of the porous member 203 in the substrate holding mechanism 20 shown in FIG. Eruption stops. Subsequently, the exhaust device is driven and gas is sucked through the porous member 203, whereby the entire lower surface 91 of the substrate 9 is adsorbed to the upper surface 2031 of the porous member 203, and the substrate 9 is in a flat state. It is held by the holding mechanism 20 (step S15).

  In the stress measuring apparatus 1 shown in FIG. 1, the ellipsometer 3 and the first film thickness calculation unit 515, or the optical interference unit 4 and the second film thickness calculation unit 516, while the substrate 9 is attracted by the substrate holding mechanism 20. In other words, the film thickness on the substrate 9 in the stress measurement region is optically measured (in step S16). Hereinafter, the film thickness measurement by the ellipsometer 3 will be described, and then the film thickness measurement by the optical interference unit 4 will be described.

  When the film thickness is measured by the ellipsometer 3, first, the moving mechanism 21 moves the mirror 25 together with the substrate holding mechanism 20 to the irradiation position of the laser light from the light source unit 31, and the laser light from the light source unit 31. Is reflected by the mirror 25 and guided to the spectroscope 42 of the optical interference unit 4. The spectroscope 42 acquires the spectral intensity of the received light, and as a result, substantially confirms the wavelength of the laser light emitted from the semiconductor laser 312 (hereinafter referred to as “laser wavelength calibration”). The acquired wavelength of the laser beam is output to the first film thickness calculation unit 515 (see FIG. 3) of the control unit 5 and is used when the ellipsometer 3 measures the film thickness.

  Subsequently, illumination light is emitted from the light source 41 of the optical interference unit 4 and an image of the substrate 9 is acquired by the substrate imaging unit 44, and the moving mechanism 21 moves the substrate 9 together with the substrate holding mechanism 20 based on the image. By doing so, the irradiation position of the polarized light from the light source unit 31 of the ellipsometer 3 is matched with the stress measurement region on the substrate 9. When the position adjustment is completed, polarized light is emitted from the light source unit 31 to the substrate 9, and the polarization state of the reflected light is acquired by the light receiving unit 32.

  The first film thickness calculation unit 515 of the control unit 5 uses the incident angle of the polarized light with respect to the stress measurement region and the wavelength of the polarized light from the light source unit 31 acquired by laser wavelength calibration, while the light receiving unit 32 Based on the acquired polarization state (to be precise, the polarization state of light from the light source unit 31 is also used), the thickness of the film in the stress measurement region on the substrate 9 is obtained. When the stress measurement region matches any of the plurality of tilt vector measurement regions, the polarization state of the reflected light from the substrate 9 may be acquired during the tilt vector measurement.

  In the stress measurement apparatus 1, the laser wavelength calibration of the ellipsometer 3 is performed before the film thickness measurement, so that the wavelength of light from the light source unit 31 changes due to changes in ambient temperature, changes in the characteristics of each component of the light source unit 31, and the like. Even in this case, the film thickness can be obtained with high accuracy.

  Next, the film thickness measurement by the optical interference unit 4 will be described. When the film thickness is measured by the optical interference unit 4, first, in the optical interference unit 4, illumination light from the light source 41 is guided to the stress measurement region of the substrate 9 through the optical system 45, and from the substrate 9. Is reflected to the spectroscope 42. Then, the spectral intensity of the reflected light is acquired by the spectroscope 42, and the spectral intensity data of the substrate 9 is output to the second film thickness calculator 516 (see FIG. 3) of the controller 5.

In the stress measurement apparatus 1, the optical interference unit 4 obtains in advance the spectral intensity of a substrate to be referred to (in this embodiment, a silicon substrate, hereinafter referred to as “reference substrate”), and calculates the second film thickness. Stored in the unit 516. In addition, the thickness of the silicon dioxide (SiO ₂ ) natural oxide film generated on the reference substrate is measured in advance by the ellipsometer 3 and the first film thickness calculator 515 and stored in the second film thickness calculator 516. Yes. In the second film thickness calculation unit 516, the (vertical) spectral reflectance of the reference substrate is calculated by theoretical calculation from the film thickness of the natural oxide film measured by the ellipsometer 3, and stored in advance as “theoretical spectral reflectance”. ing.

  The second film thickness calculator 516 obtains the spectral reflectance of the substrate 9 from the spectral intensities of the reference substrate and the substrate 9 based on the theoretical spectral reflectance of the reference substrate. Here, the theoretical spectral reflectance of the reference substrate is Rc (λ), the spectral intensity of the reference substrate is Ic (λ), the spectral intensity of the substrate 9 is Im (λ), and the spectral reflectance of the substrate 9 is Rm (λ). Then, the spectral reflectance Rm (λ) of the substrate 9 can be obtained by Equation 2.

(Equation 2)
Rm (λ) = (Im (λ) / Ic (λ)) × Rc (λ)

  That is, the spectral reflectance of the substrate 9 is obtained by multiplying the spectral intensity of the substrate 9 obtained by the optical interference unit 4 by the ratio of the theoretical spectral reflectance of the reference substrate and the spectral intensity of the reference substrate. In the second film thickness calculation unit 516, the film thickness in the stress measurement region on the substrate 9 is further accurately obtained from the spectral reflectance of the substrate 9. Note that when the stress measurement region matches any one of the plurality of tilt vector measurement regions, the spectral intensity of the reflected light from the substrate 9 may be acquired during the tilt vector measurement.

As described above, when the film thickness measurement is completed, the curvature radius calculation unit 513 and the film thickness measurement unit (that is, the ellipsometer 3 and the first film thickness calculation unit 515 or the optical interference unit 4 and the second interference unit 4) are performed in steps S14 and S16. Based on the curvature radius and film thickness of the stress measurement region obtained by the film thickness calculation unit 516) and the thickness of the substrate 9 input in advance via the input unit 56 (see FIG. 2) of the control unit 5. The stress calculation unit 514 (see FIG. 3) of the control unit 5 obtains the stress in the film in the stress measurement region (step S17). Here, the radius of curvature R and, respectively the thickness and h _f in the stress measurement region, the thickness of the substrate 9 is h, if the Young's modulus and Poisson's ratio of the substrate 9 respectively E and [nu, in stress measurement region The stress σ in the film is obtained by Equation 3.

(Equation 3)
σ = (E / 1−ν) × (h ² / (6Rh _f ))

  As described above, in the stress measurement apparatus 1, the surface shape of the substrate 9 is measured in a state where the lower surface 91 of the substrate 9 is not in contact with the upper surface 2031 of the porous member 203 by the substrate holding mechanism 20. . At this time, in the substrate holding mechanism 20, the substrate 9 is surface-supported without coming into contact with the support portion 201 by ejecting gas from the entire upper surface 2031 of the porous member 203 facing the lower surface 91 of the substrate 9 approximately uniformly. The Thereby, the board | substrate 9 can be hold | maintained, preventing a deformation | transformation of the board | substrate 9, As a result, the surface shape of the board | substrate 9 can be calculated | required with high precision.

  In the substrate holding mechanism 20, since the upper surface 2031 of the porous member 203 faces the entire lower surface 91 of the substrate 9, the deformation of the substrate 9 can be prevented over the entire substrate 9. The shape can be determined with higher accuracy. Furthermore, in the stress measuring device 1, since the surface shape of the substrate 9 is measured in a non-contact manner by the optical interference unit 4, unlike other devices that measure using a contact-type measuring terminal, the stress is measured by a load from the measuring terminal. The deformation of the substrate can be prevented, and the surface shape of the substrate 9 can be obtained with higher accuracy.

  On the other hand, the film thickness on the substrate 9 is optically measured in a state where the lower surface 91 of the substrate 9 is attracted to the upper surface 2031 of the porous member 203 by the substrate holding mechanism 20. In the stress measuring apparatus 1, the substrate 9 can be held in a flat state by adsorbing the substrate 9 by the substrate holding mechanism 20. As a result, the film thickness on the substrate 9 can be obtained with high accuracy while suppressing the influence of the inclination of the upper surface 92 of the substrate 9. Furthermore, the stress in the film on the substrate 9 can be obtained with high accuracy based on the surface shape of the substrate 9 and the film thickness on the substrate 9 thus obtained with high accuracy.

  In the substrate holding mechanism 20, when the adsorption of the substrate 9 is released, particles and the like in the pipe 2043 flow backward with the gas and flow into the internal space 205, but the portion that contacts the lower surface 91 of the substrate 9 is porous. Since the member 203 is used, the porous member 203 serves as a filter, and particles and the like can be prevented from being sprayed and attached to the lower surface 91 of the substrate 9.

  In the optical interference unit 4, a light blocking filter that blocks light having a specific wavelength (for example, infrared light having a wavelength of 800 nm or more) is disposed in the field stop unit 454 except for the central portion. A transmission filter that transmits only light of a wavelength may be attached. Thereby, in the irradiation position of the illumination light on the board | substrate 9, the light of a specific wavelength is irradiated only to the micro area | region corresponding to the center part of a light shielding filter.

  The reflected light of the illumination light is guided to the light shielding pattern imaging unit 43, and only the reflected light corresponding to the minute region is received by the light shielding pattern imaging unit 43, and the light shielding pattern 453a is imaged by the light from the minute region. The Thereby, the inclination vector in the central part of the inclination vector measurement region can be obtained with high accuracy.

  The stress measuring apparatus 1 includes a substrate holding mechanism 20 that holds the substrate 9, a moving mechanism 21, a light source 41 of the optical interference unit 4, an optical system 45, a light shielding pattern 453 a and a light shielding pattern imaging unit 43, and an inclination vector of the control unit 5. Only the calculation unit 511 and the surface shape calculation unit 512 can be used as a surface shape measurement apparatus that measures the surface shape of the substrate 9 with high accuracy without performing stress measurement.

  Next, a stress measuring apparatus according to the second embodiment of the present invention will be described. FIG. 8 is a longitudinal sectional view showing the substrate holding mechanism 20a of the stress measuring device according to the second embodiment. As shown in FIG. 8, in the substrate holding mechanism 20a, the upper surface 2031 of the disk-shaped porous member 203 has an outer edge portion of the lower surface 91 of the substrate 9 (in this embodiment, about several mm from the outer peripheral edge of the lower surface 91). It faces the circular area except for the area up to the inside. In the substrate 9, a disk-shaped portion 93 on the circular region of the lower surface 91 is an effective portion that is finally used as a semiconductor element. In FIG. 8, the part 93 is surrounded by a two-dot chain line, and in the following description, the part 93 is referred to as an “effective part 93”. Other configurations are the same as those of the substrate holding mechanism 20 shown in FIG. 5, and the same reference numerals are given in the following description.

  In the substrate holding mechanism 20 a shown in FIG. 8, the effective portion 93 excluding the outer edge portion of the substrate 9 is surface-supported in a non-contact manner from below by the support portion 201 by ejecting gas from the upper surface 2031 of the porous member 203. . Thereby, it is possible to hold the substrate 9 while preventing the deformation of the substrate 9 at the effective portion 93. As a result, in the stress measuring device according to the second embodiment, the surface shape of the substrate 9 is obtained with high accuracy. be able to.

  In the substrate holding mechanism 20a, the substrate 9 can be held in a flat state by attracting the effective portion 93 of the substrate 9 by the substrate holding mechanism 20a, and the film thickness on the substrate 9 can be obtained with high accuracy. You can also. As a result, as in the first embodiment, the stress in the film on the substrate 9 can be obtained with high accuracy. In the substrate 9 held by the substrate holding mechanism 20a, there is a possibility that the annular portion outside the effective portion 93 may be slightly deformed, but that portion is ultimately used as a semiconductor element. As a result, the stress in the film is not measured.

  Next, a substrate holding mechanism according to a third embodiment of the present invention will be described. FIG. 9 is a plan view showing a substrate holding mechanism 20b according to the third embodiment. In the stress measurement device according to the third embodiment, a rectangular plate-like glass substrate (hereinafter simply referred to as “substrate”) for a flat display device such as a liquid crystal display device, a plasma display device, or an organic EL display device is used. It is held by the substrate holding mechanism 20b. As shown in FIG. 9, the substrate holding mechanism 20b has a rectangular shape in plan view, and has a support portion 201a having a rectangular plate-like porous member 203a, and a side surface of the substrate supported in a non-contact manner by the support portion 201a. A rectangular frame-shaped movement restricting portion 202a is provided.

  In the substrate holding mechanism 20b, gas is ejected from the upper surface 2031 of the porous member 203a, whereby the entire substrate is surface-supported in a non-contact manner by the support portion 201a from below. Thereby, the substrate can be held while preventing the substrate from being deformed, as in the first embodiment. In the substrate holding mechanism 20b, as in the first and second embodiments, the gas is sucked through the porous member 203a, so that the substrate is adsorbed to the support portion 201a and held in a flat state. Also good.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various change is possible.

  In the stress measurement device 1 according to the first embodiment, the surface shape of the substrate 9 is not necessarily required based on the output from the optical interference unit 4. For example, an autofocus mechanism that automatically adjusts the focus with respect to the substrate 9 is provided, and the substrate holding mechanism 20 is lifted and lowered while the substrate 9 is supported in a non-contact manner by the support portion 201, so After the focus adjustment is performed at this position, the surface shape of the substrate 9 may be obtained based on the height of the substrate holding mechanism 20 after the focus adjustment at the plurality of positions.

  The substrate holding mechanism according to the above embodiment is not necessarily used in the stress measurement device (or the surface shape measurement device). In various devices that perform various measurements and processes on the substrate, It may be used as a substrate holding device for holding. Further, it may be used as a single substrate holding device.

  The substrate holding device is a substrate other than a glass substrate for a semiconductor substrate or a flat display device (for example, a plastic substrate on which an organic semiconductor thin film is formed (or will be formed), or a plastic used for a solar cell. (Film substrate) may be used for holding. However, since the substrate holding device can hold the substrate while preventing the deformation of the substrate as described above, it can be used for holding a semiconductor substrate or a glass substrate for a flat display device that requires high-precision measurement and processing. Especially suitable.

It is a figure which shows the structure of the stress measuring device which concerns on 1st Embodiment. It is a figure which shows the structure of a control part. It is a block diagram which shows the function of a control part. It is a top view which shows a substrate holding mechanism. It is a longitudinal cross-sectional view which shows a substrate holding mechanism. It is a figure which shows the flow of stress measurement. It is a figure which shows the surface shape of a board | substrate. It is a longitudinal cross-sectional view which shows the board | substrate holding mechanism which concerns on 2nd Embodiment. It is a top view which shows the board | substrate holding mechanism which concerns on 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stress measuring device 3 Ellipsometer 4 Optical interference unit 9 Substrate 20 Substrate holding mechanism 91 Lower surface 92 Upper surface 201, 201a Supporting portion 202, 202a Movement restricting portion 203, 203a Porous member 511 Inclination vector calculating portion 512 Surface shape calculating portion 513 Curvature radius Calculation unit 514 Stress calculation unit 515 First film thickness calculation unit 516 Second film thickness calculation unit 2031 Upper surface

Claims (7)

A substrate holding device for holding a substrate,
A support part that supports the whole part of the substrate or a part other than the outer edge part from the bottom in a non-contact manner by ejecting gas from a porous member having a flat surface facing the lower surface of the substrate;
A movement restricting portion that abuts against a side surface of the substrate supported by the support portion and restricts movement of the substrate in a direction parallel to the lower surface;
A substrate holding device comprising: The substrate holding apparatus according to claim 1,
The substrate holding apparatus, wherein the flat surface of the porous member faces the entire lower surface of the substrate. The substrate holding apparatus according to claim 1 or 2,
A substrate holding apparatus, wherein a substrate is adsorbed to the support portion by sucking gas through the porous member. A substrate holding apparatus according to any one of claims 1 to 3,
The substrate holding apparatus, wherein the substrate is a semiconductor substrate. A substrate holding apparatus according to any one of claims 1 to 3,
A substrate holding apparatus, wherein the substrate is a glass substrate for a flat display device. A surface shape measuring device for measuring the surface shape of a substrate,
A substrate holding device according to any one of claims 1 to 5, which holds a substrate;
A shape measuring unit for measuring the shape of the upper surface of the substrate in a non-contact state in a state where the lower surface of the substrate is not in contact with the flat surface of the porous member by the substrate holding device;
A surface shape measuring apparatus comprising: A stress measuring device for measuring stress in a film on a substrate,
A substrate holding device according to any one of claims 3 to 5, which holds a substrate;
A shape measuring unit for measuring the shape of the upper surface of the substrate in a non-contact state in a state where the lower surface of the substrate is not in contact with the flat surface of the porous member by the substrate holding device;
A radius-of-curvature calculator that calculates a radius of curvature of the stress measurement region on the upper surface based on the shape of the upper surface of the substrate determined by the shape measuring unit;
A film thickness measuring unit that optically measures the thickness of the film on the upper surface of the substrate in a state where the lower surface of the substrate is adsorbed to the flat surface of the porous member by the substrate holding device;
A stress calculation unit for obtaining a stress in the film in the stress measurement region based on a curvature radius and a film thickness in the stress measurement region obtained by the curvature radius calculation unit and the film thickness measurement unit;
A stress measuring device comprising:

Images