JP2007095816A - Substrate testing apparatus and substrate testing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate testing apparatus and a substrate testing method for testing whether the mesa direction is adequate direction to the standard linear line within a short period of time with non-destructive system. <P>SOLUTION: The substrate testing apparatus 10 comprises: an LED sensor 2 for detecting location of an orientation flat OF provided at the edge of a compound semiconductor substrate W having an arc type edge E; an imaging unit 4 for imaging a plurality of patterns P formed by the etching on the front surface S of the compound semiconductor substrate W; and an analyzing unit 6 for determining the mesa direction Dm using an image obtained from the imaging unit 4, and computing an angle θ formed with the standard linear line L connecting the center O of the compound semiconductor substrate W and location A of the orientation flat OF and the determined mesa direction Dm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a substrate inspection apparatus and a substrate inspection method.

  When a wafer is manufactured by slicing an ingot made of a compound semiconductor such as GaAs, cracks or damage occurs on the surface of the wafer. In order to remove this crack or damage, it is necessary to wet-etch the entire surface of the wafer. At this time, a pattern resulting from etching anisotropy is formed on the surface of the wafer. A method of identifying the mesa direction (specific crystal orientation) by irradiating the surface on which this pattern is formed with laser light and observing the reflected image is known (see Patent Document 1). Further, a method for forming a pattern similar to the above pattern by etching the entire back surface of the compound semiconductor wafer is known (see Patent Document 2).

  For example, when the (100) plane of a wafer made of a compound semiconductor such as GaAs or InP is etched, a mesa shape appears in a cross section parallel to the (0-11) plane of the pattern and is orthogonal to the (0-11) plane (0 -1-1) An inverted mesa shape appears in a cross section parallel to the plane (see Non-Patent Document 1). In this case, the [0-11] direction is the mesa direction, and the [0-1-1] direction is the reverse mesa direction.

  On the other hand, when the (−100) plane of the wafer is etched, an inverted mesa shape appears in a cross section parallel to the (0-11) plane of the pattern, and a mesa shape appears in a cross section parallel to the (0-1-1) plane. appear. In this case, the [0-11] direction is the reverse mesa direction, and the [0-1-1] direction is the mesa direction.

Further, as a mark indicating the crystal orientation of the semiconductor wafer, a notch such as an orientation flat or a notch is usually formed on the edge of the semiconductor wafer. The notch is located in a predetermined direction from the center of the semiconductor wafer. The position of the notch is determined using, for example, the crystal orientation obtained by using an X-ray diffractometer (see Non-Patent Document 2).
JP-A-2-240505 Japanese Utility Model Publication No. 60-125726 Edited by Japan Institute of Mechanical Engineers, Technical Research Institute, “Processing Technology Data File (Review 9)”, March 1985, 2.2.2, p. 1-17 Edited by UCS Semiconductor Fundamental Technology Study Group, "Science of Silicon", Realize Inc., June 28, 1996, p. 232-233

  In recent years, processing accuracy required in a process using a compound semiconductor substrate is increasing. In order to increase the processing accuracy, it is important to inspect whether the mesa direction is an appropriate direction with respect to a reference straight line connecting the center of the compound semiconductor substrate and the position of the notch.

  Therefore, an object of the present invention is to provide a substrate inspection apparatus and a substrate inspection method capable of inspecting whether or not the mesa direction is an appropriate direction with respect to a reference straight line in a short time and in a nondestructive manner.

  In order to solve the above-described problems, a substrate inspection apparatus according to the present invention includes a notch position detection unit that detects a position of a notch provided at an edge of a compound semiconductor substrate having an arcuate edge, and the compound semiconductor substrate. An imaging unit that images a plurality of patterns formed on the surface by etching, a mesa direction using an image obtained from the imaging unit, and a reference that connects the center of the compound semiconductor substrate and the position of the notch An analysis unit that calculates an angle between the straight line and the determined mesa direction;

  According to the substrate inspection apparatus of the present invention, it can be seen how much the angle formed by the reference straight line and the mesa direction deviates from a desired angle. Therefore, it can be inspected in a short time and nondestructively whether the mesa direction is an appropriate direction with respect to the reference straight line.

  A notch position detecting step for detecting a position of a notch provided at the edge of the compound semiconductor substrate having an arcuate edge, and an imaging step for imaging a plurality of patterns formed by etching on the surface of the compound semiconductor substrate; The mesa direction is determined using the image obtained in the imaging step, and the angle formed by the reference straight line connecting the center of the compound semiconductor substrate and the position of the notch and the determined mesa direction is calculated. Analysis step.

  According to the substrate inspection method of the present invention, it can be seen how much the angle formed by the reference straight line and the mesa direction deviates from a desired angle. Therefore, it can be inspected in a short time and nondestructively whether the mesa direction is an appropriate direction with respect to the reference straight line.

  A substrate inspection apparatus according to the present invention includes a notch position detection unit that detects a position of a notch provided on an edge of a compound semiconductor substrate having an arc-shaped edge, and a plurality of mirror-polished surfaces of the compound semiconductor substrate. An ellipsometry measuring device that performs ellipsometry measurement from the direction, and a mesa direction is determined using a plurality of phase difference data obtained from the ellipsometry measuring device, and the center of the compound semiconductor substrate and the position of the notch are determined. And an analysis unit that calculates an angle formed by the reference straight line to be connected and the determined mesa direction.

  According to the substrate inspection apparatus of the present invention, it can be seen how much the angle formed by the reference straight line and the mesa direction deviates from a desired angle. Therefore, it can be inspected in a short time and nondestructively whether the mesa direction is an appropriate direction with respect to the reference straight line.

  The substrate inspection method of the present invention includes a notch position detecting step for detecting a position of a notch provided at an edge of a compound semiconductor substrate having an arcuate edge, and a plurality of mirror polishing surfaces on the compound semiconductor substrate. An ellipsometry measurement step for performing ellipsometry measurement from the direction, and determining a mesa direction using a plurality of phase difference data obtained in the ellipsometry measurement step, and the center of the compound semiconductor substrate and the position of the notch And an analysis step of calculating an angle formed by a reference straight line connecting the two and the determined mesa direction.

  According to the substrate inspection method of the present invention, it can be seen how much the angle formed by the reference straight line and the mesa direction deviates from a desired angle. Therefore, it can be inspected in a short time and nondestructively whether the mesa direction is an appropriate direction with respect to the reference straight line.

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate test | inspection apparatus and board | substrate test | inspection method which can test | inspect for a short time and nondestructive whether a mesa direction is an appropriate direction with respect to a reference straight line are provided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

[First Embodiment]
FIG. 1 is a perspective view schematically showing the substrate inspection apparatus according to the first embodiment. A substrate inspection apparatus 10 shown in FIG. 1 includes an LED sensor 2 (notch position detection unit) that detects a position A of an orientation flat OF (notch) provided on an edge of a compound semiconductor substrate W having an arcuate edge E. ).

  Here, the reference straight line L connecting the position A of the orientation flat OF and the center O of the compound semiconductor substrate W is orthogonal to the direction in which the orientation flat OF extends. Note that a notch may be provided as a notch in place of the orientation flat OF. In the case of a notch, the deepest part of the notch groove is the position of the notch. Moreover, you may provide an index flat in the edge of the compound semiconductor substrate W as needed.

  The compound semiconductor substrate W is placed on the stage 8, for example. Examples of the compound semiconductor substrate W include III-V group compound semiconductor substrates such as a GaAs substrate, InP substrate, InSb substrate, InAs substrate, GaSb substrate, and GaP substrate. In one embodiment, the compound semiconductor substrate W is a 4-inch wafer made of InP doped with iron atoms (Fe). The compound semiconductor substrate W is obtained, for example, by slicing an ingot with a wire saw or the like and then forming an orientation flat OF by peripheral processing. A jig 18 for centering the compound semiconductor substrate W is preferably disposed outside the edge of the compound semiconductor substrate W. When the jig 18 contacts the edge of the compound semiconductor substrate W, the compound semiconductor substrate W is centered.

  In order to suck the compound semiconductor substrate W to the stage 8, it is preferable that a vacuum pump 26 is connected to the stage 8 via a pipe 16. The stage 8 is preferably connected to the stepping motor 14 via the rotating shaft 12. The compound semiconductor substrate W can be rotated by rotating the stage 8. When the light from the LED sensor 2 is irradiated to the edge of the compound semiconductor substrate W while rotating the compound semiconductor substrate W, the position A of the orientation flat OF can be detected. The wavelength of light emitted from the LED sensor 2 is preferably 600 to 700 nm.

  The substrate inspection apparatus 10 includes an imaging unit 4 that images a plurality of patterns P formed on the surface S of the compound semiconductor substrate W by etching. The surface S may be a (100) plane, or may be a plane tilted from several degrees to several tens of degrees from the (100) plane. The imaging unit 4 is, for example, a CCD camera equipped with a microscope. The plurality of patterns P are arranged along the mesa direction Dm. The pattern P is a recess having a shape resulting from, for example, wet etching anisotropy. The pattern P has, for example, an elliptical shape as viewed from the normal direction of the surface S. The pattern P is formed, for example, by immersing the compound semiconductor substrate W in an etching solution. When the compound semiconductor substrate W is, for example, a 4-inch wafer made of InP doped with iron atoms, it is 10 at 60 ° C. using a predetermined etching solution (sulfuric acid: hydrogen peroxide water: water = 1: 1: 3). It is preferable to perform etching for a minute.

  The substrate inspection apparatus 10 determines the mesa direction Dm using the image obtained from the imaging unit 4, and also determines the mesa direction Dm that connects the center O of the compound semiconductor substrate W and the position A of the orientation flat OF, and the determined mesa. A computer 6 (analysis unit) that calculates an angle θ formed with the direction Dm is provided. The computer 6 is connected to the imaging unit 4 by a conducting wire 20. Image data captured by the imaging unit 4 is transmitted to the computer 6 through the conductor 20. When the computer 6 analyzes the image data, the mesa direction Dm is determined. Information on the mesa direction Dm is recorded in the computer 6.

  Further, the computer 6 is connected to the LED sensor 2 by a conductive wire 22 and is connected to the stepping motor 14 by a conductive wire 24. The computer 6 can obtain the data of the position A of the orientation flat OF from the LED sensor 2 and the stepping motor 14. Thereby, the reference straight line L can be determined. Information on the reference straight line L is recorded in the computer 6. Therefore, the computer 6 can calculate the angle θ formed by using the information on the reference straight line L and the information on the mesa direction Dm.

  According to the substrate inspection apparatus 10 of the present embodiment, it can be seen how much the angle θ formed by the reference straight line L and the mesa direction Dm deviates from a desired angle. For example, when the surface S is a (100) plane, the mesa direction Dm is the [0-11] direction. In this case, it is desirable that the reference straight line L is along the [0-1-1] direction which is the reverse mesa direction. Therefore, the desired angle is 90 °. Further, when the surface S is a (-100) plane, the mesa direction Dm is the [0-1-1] direction. In this case, the reference straight line L is preferably along the [0-1-1] direction, which is the mesa direction Dm. Therefore, the desired angle is 0 °.

  Therefore, according to the substrate inspection apparatus 10, it is possible to inspect for a short time and nondestructively whether or not the mesa direction Dm is an appropriate direction with respect to the reference straight line L. Further, when the substrate inspection apparatus 10 is used, the inspection can be automated and the front and back of the compound semiconductor substrate W can be identified.

  2 and 3 are plan views schematically showing the compound semiconductor substrate in each step of the substrate inspection method according to the first embodiment. The substrate inspection method according to the present embodiment is preferably performed using the substrate inspection apparatus 10. For example, the compound semiconductor substrate W can be inspected by sequentially performing the following steps. The centering process may not be performed.

(Centering process)
As shown in FIG. 2A, the compound semiconductor substrate W is centered by bringing the jig 18 into contact with the edge of the compound semiconductor substrate W. Thereafter, the compound semiconductor substrate W is fixed to the stage 8 by sucking the compound semiconductor substrate W using the vacuum pump 26.

(Notch position detection process)
As shown in FIG. 2B, the position A of the orientation flat OF provided on the edge of the compound semiconductor substrate W having the arcuate edge E is detected. When the light from the LED sensor 2 is irradiated to the edge of the compound semiconductor substrate W while rotating the compound semiconductor substrate W, the position A of the orientation flat OF can be detected. Information on the position A of the orientation flat OF is recorded in the computer 6. After detecting the position A of the orientation flat OF, the rotation of the compound semiconductor substrate W is stopped.

(Imaging process)
As shown in FIG. 3A, a plurality of patterns P formed by etching on the surface S of the compound semiconductor substrate W are imaged. Thereby, the image I is obtained. FIG. 4 is a diagram illustrating an example of an image I obtained by imaging the surface S of the compound semiconductor substrate W.

(Analysis process)
As shown in FIG. 3A, the mesa direction Dm is determined using the image I obtained in the imaging process. Information on the mesa direction Dm is recorded in the computer 6. The mesa direction Dm is determined by detecting the edge of the pattern P, for example. Specifically, for example, first, the image I is binarized. In that case, the elongated pattern P resulting from the mesa pattern is emphasized. Next, a stained glass treatment is performed. At this time, the stained glass is cut into a mesh. Each frame constituting the mesh is a rectangle having a length slightly shorter than the length of the elongated pattern P and a width slightly narrower than the pattern P. Here, for example, when the white portion showing the pattern P occupies 95% or more of the area of the rectangle, the rectangle is displayed in white, and when it is less than 95%, the rectangle is displayed in black. This stained glass process is performed while rotating the stained glass, for example, by 1 ° with respect to the image I. After the stained glass treatment at each angle, the area displayed in white is calculated. Such stained glass processing and calculations are performed over 180 °. Thereafter, the area obtained by calculation is plotted against the angle and approximated by a sine curve. Furthermore, the angle that maximizes the area is calculated. This angle indicates the mesa direction Dm. Note that the edge of the pattern P can be emphasized by devising the illumination method in the imaging step.

  Further, the reference straight line L connecting the center O of the compound semiconductor substrate W and the position A of the orientation flat OF can be determined from the information of the position A of the orientation flat OF recorded in the computer 6. As shown in FIG. 3B, the computer 6 is used to calculate an angle θ between the reference straight line L and the determined mesa direction Dm.

  According to the substrate inspection method of this embodiment, it can be seen how much the angle θ formed by the reference straight line L and the mesa direction Dm deviates from a desired angle. For example, when the surface S is a (100) plane, the mesa direction Dm is the [0-11] direction. In this case, it is desirable that the reference straight line L is along the [0-1-1] direction which is the reverse mesa direction. Therefore, the desired angle is 90 °.

  Therefore, according to the above-described substrate inspection method, it can be inspected in a short time and nondestructively whether or not the mesa direction Dm is an appropriate direction with respect to the reference straight line L. In addition, when the substrate inspection method of this embodiment is used, the inspection can be automated and the front and back of the compound semiconductor substrate W can be identified.

[Second Embodiment]
FIG. 5 is a perspective view schematically showing a substrate inspection apparatus according to the second embodiment. The substrate inspection apparatus 110 shown in FIG. 5 includes an LED sensor 2 (notch position detection unit) that detects a position A of an orientation flat OF (notch) provided on the edge of the compound semiconductor substrate 100W having an arcuate edge E. ).

  Here, the reference straight line L connecting the position A of the orientation flat OF and the center O of the compound semiconductor substrate 100W is orthogonal to the extending direction of the orientation flat OF. Note that a notch may be provided as a notch in place of the orientation flat OF. In the case of a notch, the deepest part of the notch groove is the position of the notch. Moreover, you may provide an index flat in the edge of the compound semiconductor substrate 100W as needed.

  The compound semiconductor substrate 100W is placed on the stage 8, for example. Examples of the compound semiconductor substrate 100W include III-V group compound semiconductor substrates such as a GaAs substrate, InP substrate, InSb substrate, InAs substrate, GaSb substrate, and GaP substrate. In one embodiment, the compound semiconductor substrate 100W is a 3-inch wafer made of GaAs doped with silicon atoms (Si). The compound semiconductor substrate 100W is obtained, for example, by slicing an ingot with a wire saw or the like and then forming an orientation flat OF by outer periphery processing. Thereafter, it is preferable that both surfaces of the compound semiconductor substrate 100W are lapped and one surface is polished (polished). Further, it is preferable that the polished surface is washed with an organic solvent, washed with dilute ammonia water, and rinsed with ultrapure water. Then, it is preferable to dry the surface rinsed, for example using a spin dryer. In this way, a compound semiconductor substrate 100W having a mirror-polished surface 100S is obtained.

  A plurality of optical sensors 118 for centering the compound semiconductor substrate 100W are preferably arranged outside the edge of the compound semiconductor substrate 100W. The sensor 118 can detect the edge of the compound semiconductor substrate 100W. Based on the position data from the sensor 118, the compound semiconductor substrate 100 </ b> W is centered using the substrate holder 109.

  In order to suck the compound semiconductor substrate 100 </ b> W to the stage 8, a vacuum pump 26 is preferably connected to the stage 8 via a pipe 16. The stage 8 is preferably connected to the stepping motor 14 via the rotating shaft 12. By rotating the stage 8, the compound semiconductor substrate 100W can be rotated. When the light from the LED sensor 2 is irradiated to the edge of the compound semiconductor substrate 100W while rotating the compound semiconductor substrate 100W, the position A of the orientation flat OF can be detected. The wavelength of light emitted from the LED sensor 2 is preferably 600 to 700 nm.

  The substrate inspection apparatus 110 includes an ellipsometry measuring instrument 107 that performs ellipsometry measurement from a plurality of directions on the mirror-polished surface 100S of the compound semiconductor substrate 100W. The surface 100S may be a (100) plane, or may be a plane inclined by several degrees to several tens of degrees from the (100) plane. For example, the normal direction of the surface 100S may be a direction inclined by 2 degrees from the <100> direction to the <110> direction. The ellipsometry measuring instrument 107 is, for example, a light source 104 capable of making light (monochromatic coherent light and polarized light) having a wavelength of 450 to 460 nm incident on the surface 100S, and light detection capable of detecting reflected light from the surface 100S. Device 105. In addition, when using a GaAs substrate as the compound semiconductor substrate 100W, it is preferable to use light within a wavelength range of a wavelength of 380 to 480 nm or a wavelength of 600 to 900 nm. In addition, when an InP substrate is used as the compound semiconductor substrate 100W, it is preferable to use light in a wavelength range of 200 to 300 nm or 350 to 450 nm. In these cases, since the sensitivity of anisotropy becomes high, ellipsometry measurement can be performed with high sensitivity.

  The substrate inspection apparatus 110 determines the mesa direction Dm using a plurality of phase difference data obtained from the ellipsometry measuring device 105, and connects a reference straight line L connecting the center O of the compound semiconductor substrate 100W and the position A of the orientation flat OF. And a computer 106 (analysis unit) that calculates an angle θ formed with the determined mesa direction Dm. The computer 106 is connected to the photodetector 105 by a conductive wire 121. The phase difference data obtained from the photodetector 105 is transmitted to the computer 106 through the conducting wire 121. When the computer 106 analyzes the phase difference data, the mesa direction Dm is determined. Information on the mesa direction Dm is recorded in the computer 106.

  Further, the computer 106 is connected to the LED sensor 2 by a conducting wire 22 and is connected to the stepping motor 14 by a conducting wire 24. The computer 106 can obtain the data of the position A of the orientation flat OF from the LED sensor 2 and the stepping motor 14. Thereby, the reference straight line L can be determined. Information on the reference straight line L is recorded in the computer 106. Therefore, the computer 106 can calculate the angle θ formed by using the information on the reference straight line L and the information on the mesa direction Dm.

  According to the substrate inspection apparatus 110 of the present embodiment, it can be understood how much the angle θ formed by the reference straight line L and the mesa direction Dm deviates from a desired angle. For example, when the surface 100S is a (100) plane, the mesa direction Dm is the [0-11] direction. In this case, it is desirable that the reference straight line L is along the [0-1-1] direction which is the reverse mesa direction. Therefore, the desired angle is 90 °. Further, when the surface 100S is a (-100) plane, the mesa direction Dm is the [0-1-1] direction. In this case, the reference straight line L is preferably along the [0-1-1] direction, which is the mesa direction Dm. Therefore, the desired angle is 0 °.

  Therefore, according to the substrate inspection apparatus 110, it can be inspected in a short time and nondestructively whether or not the mesa direction Dm is an appropriate direction with respect to the reference straight line L. Further, when the substrate inspection apparatus 110 is used, the inspection can be automated and the front and back of the compound semiconductor substrate 100W can be identified.

  FIG. 6 is a plan view schematically showing a compound semiconductor substrate in each step of the substrate inspection method according to the second embodiment. FIG. 7 is a view for explaining the substrate inspection method according to the second embodiment. The substrate inspection method according to this embodiment is preferably implemented using the substrate inspection apparatus 110. For example, the compound semiconductor substrate 100W can be inspected by sequentially performing the following steps. The centering process may not be performed.

(Centering process)
As shown in FIG. 6A, the compound semiconductor substrate 100 </ b> W is centered by moving the compound semiconductor substrate 100 </ b> W using the substrate holder 109 based on the position data from the sensor 118. Thereafter, the compound semiconductor substrate 100 </ b> W is sucked using the vacuum pump 26 to fix the compound semiconductor substrate 100 </ b> W to the stage 8.

(Notch position detection process)
As shown in FIG. 6B, the position A of the orientation flat OF provided on the edge of the compound semiconductor substrate 100W having the arcuate edge E is detected. When the light from the LED sensor 2 is irradiated to the edge of the compound semiconductor substrate 100W while rotating the compound semiconductor substrate 100W, the position A of the orientation flat OF can be detected. Information on the position A of the orientation flat OF is recorded in the computer 106. After detecting the position A of the orientation flat OF, the rotation of the compound semiconductor substrate 100W is stopped.

(Ellipsometry measurement process)
As shown in FIG. 7A, ellipsometry measurement is performed from a plurality of directions on the mirror-polished surface 100S of the compound semiconductor substrate 100W. The ellipsometry measurement is performed at an arbitrary point on the surface 100S. In this embodiment, for example, ellipsometry measurement is performed from a plurality of directions at the center O of the compound semiconductor substrate 100W.

First, by ellipsometry measurements taken from a first direction to obtain a phase difference delta ₁ and s-polarized light and ρ polarization. Next, ellipsometry measurement is performed from the second direction intersecting the first direction by rotating the ellipsometry measuring instrument 105 relative to the compound semiconductor substrate 100W. This gives the phase difference delta ₂ between the s-polarized light and ρ polarization.

  Note that the first direction and the second direction mean light traveling directions when incident light and reflected light of ellipsometry measurement are projected onto the surface 100S of the compound semiconductor substrate 100W.

In the present embodiment, the first direction is set to a direction orthogonal to the reference straight line L, for example, and is set to 0 ° (reference). Further, the second direction, for example, from 0 ° to a predetermined angle beta ₁ rotated direction. As a predetermined angle beta ₁ for example 1 °, it may be subjected to ellipsometry measurement for each to 1 ° rotation of the compound semiconductor substrate 100W. In this case, the compound semiconductor substrate 100W may be rotated 360 ° to obtain 360 pieces of phase difference data, or may be rotated 180 ° to obtain 180 pieces of phase difference data.

(Analysis process)
FIG. 7B is a graph for explaining the analysis process in detail. The horizontal axis β of the graph indicates the rotation angle from 0 ° when the direction orthogonal to the reference straight line L is 0 °. The vertical axis Δ of the graph indicates the phase difference obtained by ellipsometry measurement.

As shown in FIG. 7B, using the phase difference Δ ₁ and phase difference Δ ₂ (phase difference data) obtained in the ellipsometry measurement step, a sine characteristic unique to the compound semiconductor substrate 100W to be measured. Determine the wave SS. In the sine wave SS, the phase difference obtained when the ellipsometry measurement is performed from the mesa direction Dm is maximized, and the phase difference obtained when the ellipsometry measurement is performed from the reverse mesa direction Dn is minimized. Therefore, the mesa direction Dm can be determined by calculating the rotation angle (−α) at which the sine wave SS is maximized. Information on the mesa direction Dm is recorded in the computer 106. In one embodiment, the maximum value of the sine wave SS is 142 °, and the minimum value of the sine wave SS is 141.5 °.

  When the compound semiconductor substrate 100W is rotated 360 ° to obtain 360 pieces of phase difference data, the mesa direction Dm can be determined with high accuracy by fitting the plotted phase difference data with a sine wave. Further, when 180 phase difference data are obtained by rotating the compound semiconductor substrate 100W by 180 °, the mesa direction Dm is determined with high accuracy by calculating a rotation angle at which the plotted phase difference data is maximized or minimized. be able to.

  Further, the reference straight line L connecting the center O of the compound semiconductor substrate 100W and the position A of the orientation flat OF can be determined from the information on the position A of the orientation flat OF recorded in the computer 106. As shown in FIG. 7A, the computer 106 is used to calculate an angle θ between the reference straight line L and the determined mesa direction Dm.

  According to the substrate inspection method of this embodiment, it can be seen how much the angle θ formed by the reference straight line L and the mesa direction Dm deviates from a desired angle. For example, when the surface 100S is a (100) plane, the mesa direction Dm is the [0-11] direction. In this case, it is desirable that the reference straight line L is along the [0-1-1] direction which is the reverse mesa direction. Therefore, the desired angle is 90 °.

  Therefore, according to the above-described substrate inspection method, it can be inspected in a short time and nondestructively whether or not the mesa direction Dm is an appropriate direction with respect to the reference straight line L. In addition, when the substrate inspection method of this embodiment is used, the inspection can be automated and the front and back of the compound semiconductor substrate 100W can be identified.

  As mentioned above, although preferred embodiment of this invention was described in detail, this invention is not limited to the said embodiment.

It is a perspective view showing typically the substrate inspection device concerning a 1st embodiment. It is a top view which shows typically the compound semiconductor substrate in each process of the board | substrate inspection method concerning 1st Embodiment. It is a top view which shows typically the compound semiconductor substrate in each process of the board | substrate inspection method concerning 1st Embodiment. It is a figure which shows an example of the image which imaged the surface of the compound semiconductor substrate. It is a perspective view which shows typically the board | substrate inspection apparatus which concerns on 2nd Embodiment. It is a top view showing typically a compound semiconductor substrate in each process of a substrate inspection method concerning a 2nd embodiment. It is a figure for demonstrating the board | substrate inspection method which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... LED sensor (notch position detection part), 4 ... Imaging part, 6,106 ... Computer (analysis part), 10,110 ... Substrate inspection apparatus, 100S ... Mirror-polished surface of compound semiconductor substrate, 107 ... Ellipso Measurement instrument, A ... orientation flat position (notch position), Dm ... mesa direction, E ... arc edge, I ... image, L ... reference straight line, O ... compound semiconductor substrate center, OF ... orientation flat (Notches), P: plural patterns, S: surface of compound semiconductor substrate, W, 100W: compound semiconductor substrate, θ: angle formed, Δ ₁ , Δ ₂ ... phase difference.

Claims (4)

A notch position detector for detecting the position of the notch provided at the edge of the compound semiconductor substrate having an arc-shaped edge;
An imaging unit that images a plurality of patterns formed by etching on the surface of the compound semiconductor substrate;
Analysis for determining a mesa direction using an image obtained from the imaging unit and calculating an angle formed by a reference straight line connecting the center of the compound semiconductor substrate and the position of the notch and the determined mesa direction And
A board inspection apparatus comprising: A notch position detecting step for detecting the position of the notch provided at the edge of the compound semiconductor substrate having an arc-shaped edge;
An imaging step of imaging a plurality of patterns formed by etching on the surface of the compound semiconductor substrate;
The mesa direction is determined using the image obtained in the imaging step, and the angle formed by the reference straight line connecting the center of the compound semiconductor substrate and the position of the notch and the determined mesa direction is calculated. Analysis process,
A substrate inspection method. A notch position detector for detecting the position of the notch provided at the edge of the compound semiconductor substrate having an arc-shaped edge;
An ellipsometry measuring instrument for performing ellipsometry measurement from a plurality of directions on the mirror-polished surface of the compound semiconductor substrate;
A mesa direction is determined using a plurality of phase difference data obtained from the ellipsometry measuring instrument, a reference straight line connecting the center of the compound semiconductor substrate and the position of the notch, and the determined mesa direction An analysis unit for calculating an angle formed;
A board inspection apparatus comprising: A notch position detecting step for detecting the position of the notch provided at the edge of the compound semiconductor substrate having an arc-shaped edge;
An ellipsometry measurement step of performing ellipsometry measurement from a plurality of directions on the mirror-polished surface of the compound semiconductor substrate;
A mesa direction is determined using a plurality of phase difference data obtained in the ellipsometry measurement step, a reference straight line connecting the center of the compound semiconductor substrate and the position of the notch, and the determined mesa direction An analysis process for calculating the angle formed by
A substrate inspection method.

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