JPH09318552A - Method and apparatus for detecting crystal orientation of substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for detecting the crystal orientation automatically based on the quantity of light reflected from the surface of a semiconductor wafer irradiated with light and for automating the processing line of the semiconductor wafer. SOLUTION: When the surface of a GaAs semiconductor wafer 1 is irradiated with a light 9 from a projector 2 at an angle θ1 in the range of 10 deg.<θ1<30 deg., a reflected light 10 can be detected at a predetermined angle θ2 (45 deg.<θ2<135 deg.) because the irregularities on the surface have a predetermined regularity. Crystal orientation of the GaAs semiconductor wafer is determined by a direction dependent on a position where the difference of intensity of reflected light 10 thus detected is highest, i.e., the position of a photodetector set 14 in case of the most intense reflection light 10, and a direction dependent on the position of the photodetector set 14 in case or the least intense reflection light 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for detecting the crystallographic direction of a substance, and more particularly to a method and apparatus for detecting the crystallographic direction of a compound semiconductor wafer.

[0002]

2. Description of the Related Art It is conventionally known that a crystal has a certain symmetry, and two planes which always form the same angle with a certain crystal direction can be obtained. Further, in the case of semiconductor wafers such as GaAs semiconductor wafers, it is important to detect the crystallographic direction of the wafer when preparing a thin sample. For example, when a mesa etch is used in manufacturing a laser diode with a GaAs semiconductor wafer, the crystal directions of the GaAs semiconductor wafer (<011> direction and <01T> direction)
Must be strictly distinguished. Such a crystal direction is generally called a mesa direction. Hereinafter, T in <01T> means bar 1 or inversion 1.

The mesa direction of this semiconductor wafer can be detected by a method generally called an etching method. In such an etching method, the crystal orientation of the semiconductor wafer is detected by a semiconductor wafer that detects the crystal orientation, a corrosive agent (etching solution) that corrodes the semiconductor wafer, and a microscope.

FIG. 3 is a flow chart showing a conventional method for detecting a crystal orientation by etching a semiconductor wafer.
Such an etching method is also called a corrosion method. For example, a GaAs semiconductor crystal is subjected to a different shape treatment such as marking in advance so that the crystal direction can be easily understood (step 2).
0), slicing the GaAs semiconductor crystal into GaAs semiconductor wafers (step 30), treating one of the GaAs semiconductor wafers with a corrosive agent such as potassium hydroxide (KOH) (step 40), and dislocation thereof. Etch pits are selectively etched to form etch pits (step 50), and the mesa direction of the GaAs semiconductor wafer is detected by observing the direction of the etch pits with a microscope (step 60).

FIG. 4 shows the crystal mesa direction of the GaAs semiconductor wafer 1. The etching pattern (crystal pattern) 8 is short in the <001> direction and long in the <01T> direction.

Further, when a GaAs semiconductor wafer is etched with an ammonia-based etching solution or the like, an etching pattern having a unique fine concavo-convex pattern appears on the slice processed surface or the lap processed surface. By observing this with a microscope magnified about 400 times, the mesa direction of the GaAs semiconductor wafer can be known.

In this way, the crystal orientation of the compound semiconductor wafer has been detected by the conventional etching method using a microscope.

[0008]

However, according to the conventional etching method as shown in FIG. 3, since the etching pattern of the fine unevenness peculiar to the semiconductor wafer is visually observed with a microscope, the mesa of the semiconductor wafer is not observed. When detecting the direction, there is a problem that the detection of the mesa direction cannot be automated.

Further, particularly in the case of detecting the mesa direction during the manufacturing process of the semiconductor wafer, the etching pattern of the minute unevenness pattern peculiar to the semiconductor wafer is visually observed with a microscope, and therefore the detection of the mesa direction is automated. There is a problem in that productivity may be deteriorated due to cases such as interruption of the manufacturing process due to failure.

Therefore, an object of the present invention is to provide a highly productive low-cost semiconductor wafer which can automatically detect the mesa direction of the semiconductor wafer during the manufacture of the semiconductor wafer and can automate the semiconductor wafer processing line. A method and an apparatus for detecting a crystal mesa direction.

[0011]

In order to achieve the above-mentioned object, the present invention irradiates the surface of a semiconductor wafer with light to reflect the light, measures the amount of received light of the reflected light, and Provided is a method for detecting the crystal orientation of a semiconductor wafer according to the amount of received light.

In order to achieve the above object, a light projecting means for irradiating the surface of the semiconductor wafer with light, a light receiving means for receiving the reflected light and measuring the amount of received light, and a crystal orientation of the semiconductor wafer according to the amount of received light There is provided a crystal orientation detecting device for detecting a crystal orientation of a semiconductor wafer, which comprises:

That is, the semiconductor wafer crystal orientation detection method and apparatus according to the present invention are based on the fact that the detection of the crystal mesa orientation of the semiconductor wafer is based on the difference in the amount of reflected light received.
It is possible to automatically detect the mesa direction of the semiconductor wafer at the time of manufacturing the semiconductor wafer and to automate the semiconductor wafer processing line.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The method and apparatus for detecting the crystal mesa direction of a semiconductor wafer according to the present invention will be described in detail below.

FIG. 1 shows an embodiment of the present invention. This device comprises a GaAs semiconductor wafer 1 and a photo-sensing set 14 consisting of a light projector 2 and a light receiver 3.

The GaAs semiconductor wafer 1 is subjected to an etching process and has fine irregularities (patterns) on its surface. Further, the irregularities on the surface have a shape having a certain regularity (see FIG. 4).

The light projector 2 is installed at an angle Θ1 with respect to the GaAs semiconductor wafer 1, and the light receiver 3 is made of GaAs.
It is installed at an angle Θ2 with respect to the semiconductor wafer 1.

Here, in general, when light is applied to a light-reflecting surface having fine irregularities on the surface, the reflected light is scattered in various directions. With the structure of the present invention, the angle θ 1 from the projector 2 is set. When the light 9 is applied to the surface of the GaAs semiconductor wafer 1 in the range of 10 ° <Θ1 <30 °, the reflected light 10 has a constant angle Θ2 (45 ° <45 ° <45 ° <45 ° <45) since the unevenness of the surface has a certain regularity. It can be detected at Θ2 <135 °).

The direction obtained by the position where the detected difference in intensity of the reflected light 10 is the largest, that is, the position of the photodetection set 14 in the case of the strongest reflected light 10 (<01
1>) and the light detection set 1 for the weakest reflected light 10
The direction (<01T>) obtained by the position of 4 is G
It becomes the crystal mesa direction of the aAs semiconductor wafer.

FIG. 2 shows another embodiment of the present invention. This device comprises a GaAs semiconductor wafer 1 and a projector 2
And a photodetector 3, a photodetector set 14, a photodetector set 15 including a projector 4 and a photodetector 5, and two signal lines 13
And a signal comparator 6 and an output signal line 7.

When the inspection sample is the GaAs semiconductor wafer 1, it is known that the crystal direction in which the difference in the intensity of reflected light is maximum is vertical (90 °). The optical detection set 14 is installed on the X-axis and the optical detection set 15 is installed on the Y-axis. The two light projectors 2 and 4 of each of the light detection sets 14 and 15 are installed at an angle Θ1 (Θ1 = 10 °) with respect to the GaAs semiconductor wafer 1, and the two light receivers 3 and 5 are GaAs semiconductor wafer 1 respectively. Is installed at an angle Θ2 (Θ2 = 100 °). Further, in the projector 2 and the projector 4, the emitted light 9 and the emitted light 11 are respectively G
Each of the aAs semiconductor wafers 1 is installed so as to reflect at a point A on the surface of the semiconductor wafer 1.

A signal line 13 is connected to each of the light receiver 3 and the light receiver 5, and a signal comparator 6 is connected to the other end of the signal line 13. The signal line 7 is connected to the signal output side of the signal comparator 6.

Here, the emitted light 9 from the projector 2 is Ga
The light is reflected at a point A on the surface of the As semiconductor wafer 1, and the reflected light 10 enters the light receiver 3. Similarly,
The emitted light 11 from the projector 4 is the GaAs semiconductor wafer 1
The light is reflected at a point A on the surface, and the reflected light 12 enters the light receiver 5.

The two light detection sets 14 and 15 maintain their relative angle α at a right angle (α = 90 °) and change their positions so that the emitted light is always reflected at the point A.

Here, a signal proportional to the amount of the reflected light 10, 12 detected by the light receivers 3, 5 at each position is input to the signal comparator 6 through the two signal lines 13.

The two input signals are compared by the signal comparator 6, and which of the outputs of the two photodetection sets is larger (or smaller) is determined at the position where the difference is maximum, and the mesa direction is detected. A signal is output from the output signal line 7.

With the configuration of the crystal mesa direction detecting device of the semiconductor wafer as described above, the method of detecting the mesa direction is particularly the detection method based on the difference in the amount of received reflected light. The mesa direction can be automatically detected, and the semiconductor wafer processing line can be automated.

The embodiment of the present invention has been described above. In FIG. 2, the relative angle α between the two photodetection sets 14 and 15 is kept at a right angle (α = 90 °), and the emitted light is always reflected at the point A. In the case of changing the position so that the two light detection sets 14 and 15 are rotated,
s It does not matter whether the semiconductor wafer 1 is rotated about the point A.

In addition, with one optical detection set, GaA
s The mesa direction can also be detected by rotating the semiconductor wafer 1 to detect the position where the amount of received reflected light is the maximum point and the position where it is the minimum amount.

Further, the substance for detecting the crystal orientation is not limited to the semiconductor wafer as long as the surface irregularities are directional.
Depending on the crystal orientation pattern, the angle α in FIG.
Can be appropriately changed to correspond.

[0031]

As described above, according to the method and apparatus for detecting the crystal direction of a substance of the present invention, the method for detecting the crystal direction is the detection method based on the difference in the amount of received reflected light. It has become possible to automatically detect the mesa direction of a semiconductor wafer at the time of manufacturing the wafer and to automate the semiconductor wafer processing line.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an embodiment of a device for detecting a crystal mesa direction of a semiconductor wafer according to the present invention.

FIG. 2 is a schematic view showing an embodiment of a device for detecting a crystal mesa direction of a semiconductor wafer according to the present invention.

FIG. 3 is a flow chart of a conventional method for detecting a crystal mesa direction of a semiconductor wafer.

FIG. 4 is a diagram showing an etching pattern of crystals of a semiconductor wafer.

[Explanation of symbols]

 1 GaAs semiconductor wafer 2 light emitter 3 light receiver 4 light emitter 5 light receiver 6 signal comparator 7 signal line 8 etching pattern 9 light 10 reflected light 11 light 12 reflected light 13 signal line 14 light detection set 15 light detection set

Claims (4)

[Claims] 1. A method for detecting a crystallographic direction of a substance, wherein the surface of the substance is irradiated with light to be reflected, the reflected light is received and the amount of received light is measured, and the crystallographic direction of the substance is determined by the amount of received light. A method for detecting a crystal orientation, which comprises: 2. A method for detecting the crystallographic direction of a substance, wherein the surface of the substance is irradiated with light to be reflected, the reflected light is received and the amount of received light is measured, and the direction of irradiation of the light is changed. Then, the crystal direction is detected by comparing the received light amount which changes depending on the irradiation direction of the light. 3. An apparatus for detecting a crystallographic direction of a substance, comprising: a light projecting unit that irradiates the surface of the substance with light; a light receiving unit that receives the reflected light and measures a light receiving amount thereof; A crystal orientation detecting device having a crystal orientation detecting means for detecting a crystal orientation of a substance. 4. A device for detecting the crystallographic direction of a substance, a light projecting unit for irradiating the surface of the substance with light, a light receiving unit for receiving the reflected light and measuring the amount of received light, and the light projecting unit. And a direction moving means for changing the direction of the light receiving means with respect to the substance, and a light receiving amount comparison means connected to the light receiving means and comparing the light receiving amount changed by the direction moving means to determine the crystal direction. Crystal orientation detector.