JP2008244078A - Substrate processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To highly accurately calculate the presence or the absence and a degree of an inclination of a substrate put in a substrate processor, such as a film-forming device or an etching device with, using a simple and small equipment. <P>SOLUTION: There are provided two sets of detection parts respectively composed of a light source 3 and a camera 4, a first detection part 5 is arranged onto a view port 2, on the upper wall part of a chamber of a substrate processor; a second detection part 12 is arranged so as to be located inside the chamber. Each light source directly lights up the mirror face of a substrate 7 having the mirror-faced surface; each camera images an image of each light source reflected on the mirror face of the substrate; and an image processing part contrasts an imaged image imaged by each camera with a preregistered reference image and compares the positions of each reference point in the imaged image and in the reference image so as to detect an inclination of the substrate, on the basis of a deviation between the reference points. The light source and the camera are integrally provided in the detection part, and it is preferable that the detection part be arranged above the mirror face side of the substrate. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a substrate processing apparatus for processing a substrate such as a film forming apparatus such as a CVD film forming apparatus, a plasma CVD film forming apparatus, or a MOCVD film forming apparatus, or an etching apparatus such as a dry etching apparatus or a plasma etching apparatus. The tilt of various substrates such as a silicon substrate arranged in the processing apparatus can be easily detected.

If the substrate is tilted during film formation or etching in the substrate processing apparatus, the flow of the film forming gas or etching gas around the substrate is disturbed, and uniform film formation or uniform etching cannot be performed. Sometimes.
For this reason, a method for detecting the tilt of a substrate placed in the substrate processing apparatus has been proposed.

Japanese Patent Application Laid-Open No. 2007-5645 discloses an apparatus for detecting the tilt of a wafer placed on a wafer carrier of an MOCVD vapor phase growth apparatus.
The apparatus includes a light source that irradiates a wafer with directional beam light, and a position detection unit that projects light reflected on the wafer surface through a lens and a reflection unit, and the light projected on the position detection unit. The tilt of the wafer is obtained based on the focal position.

In this detection apparatus, in order to detect the 0.001 degree tilt of the wafer, the distance between the wafer and the position detection means is required to be about 10 m. In order to shorten this distance, Further, as described above, a lens such as a concave lens and a reflecting means including a reflecting plate are provided.
For this reason, the detection apparatus of this prior invention has a complicated apparatus configuration and increases the equipment cost.

Even if the optical path length of the reflected light is shortened by adopting the above-mentioned means, the distance between the wafer and the position detecting means is still about 2.5 m, and the apparatus becomes large. .
JP 2007-5645 A

  Accordingly, an object of the present invention is to make it possible to accurately obtain the presence / absence and degree of inclination of a substrate placed in a substrate processing apparatus with a simple and small facility.

To solve this problem,
The invention according to claim 1 is a substrate processing apparatus provided with a substrate detection device having a detection unit and an image processing unit comprising a light source and a camera,
The light source directly illuminates the mirror surface of the substrate whose one surface is a mirror surface,
The camera captures an image of a light source reflected on the mirror surface of the substrate,
The image processing unit compares a captured image captured by the camera with a pre-registered reference image, compares the positions of the reference points in the captured image and the reference image, and based on a reference point shift. The substrate processing apparatus is characterized by detecting the tilt of the substrate.

  According to a second aspect of the present invention, in the substrate processing apparatus of the first aspect, the light source and the camera are integrated in the detection unit, and the detection unit is disposed above the mirror side of the substrate. is there.

  According to a third aspect of the present invention, two detection units are provided, the first detection unit is disposed in a viewport on the upper wall portion of the substrate processing apparatus, and the second detection unit is located in the chamber. The substrate processing apparatus according to claim 1, wherein the substrate processing apparatus is capable of performing the processing.

  The invention according to claim 4 is the substrate processing apparatus according to claim 1, wherein the substrate processing apparatus is a film forming apparatus or an etching apparatus.

According to the present invention, an arbitrary reference point in the image of the light source reflected on the mirror surface of the substrate is determined. That is, an image when the substrate is flat without being tilted is registered in advance in the memory of the image processing unit as a reference image, and an arbitrary point in the reference image is set as a reference point. In the captured image when the substrate is tilted, the reference point in the reference image moves.
When this movement is recognized, it can be determined that the substrate is inclined, and the direction and degree of inclination can be known from the vector amount of the movement.

  Further, since the light source and the camera constituting the detection unit can be integrated, the size can be reduced, and the tilt of the substrate can be detected by attaching the detection unit to an existing substrate processing apparatus. Therefore, the substrate detection apparatus can be mounted at low cost without increasing the size of the entire substrate processing apparatus.

FIG. 1 is a diagram for schematically explaining the principle of tilt detection, and depicts an image captured by a camera. In FIG. 1, reference numeral 31 is an image of the substrate, 32 is an image of the light source reflected on the mirror surface of the substrate, and 33 is an image of the susceptor.
FIG. 1A shows a captured image when the substrate 31 is not tilted and is placed flat on the susceptor 33, and serves as a reference image. The light source image 32 is located at the center of the substrate image 31.

FIG. 1B is a captured image when the substrate is tilted, and the positions of the light source and the camera are the same as when the image of FIG. The light source image 32 is moved from the center of the substrate image 31 to the peripheral portion. The tilt direction and the tilt degree of the substrate can be detected from the vector amount of the movement of the image 32 of the light source.
In addition, as shown in FIG. 1C, when the light source image 32 itself is distorted, it can be determined that the substrate itself is distorted such as warpage.

  In addition, two detection units are provided, and the first detection unit is disposed in the viewport formed on the upper wall of the chamber, and the second detection unit is disposed in the chamber. The tilt of the substrate being processed can be known by the first detector.

Furthermore, if a function for identifying the boundary between the bright part of the peripheral part of the substrate in the captured image and the dark part of the susceptor and obtaining the positional information of the substrate is added to the image processing unit, the position in the surface of the substrate can be determined. It can also be detected.
If the susceptor can be rotated, the image processing unit may be provided with a function for capturing an image while rotating the susceptor and confirming whether the rotation of the image and the rotation of the susceptor are synchronized. It is possible to determine whether the flat member of the substrate or the susceptor is tilted or the susceptor rotation axis is distorted.

Further, if the image processing unit is provided with a function for detecting the distortion of the substrate, it is possible to detect the warpage of the substrate itself and the presence or absence of the distortion.
As described above, the tilt of the substrate can be detected with high accuracy by an extremely simple and small apparatus configuration.

FIG. 2 shows an example of a substrate processing apparatus according to the present invention. Here, an example of a vapor deposition film forming apparatus by MOCVD is shown.
In FIG. 2, reference numeral 1 indicates an upper wall constituting the chamber of the film forming apparatus, and the upper wall 1 is lifted upward and the chamber is opened.

  A viewport 2 is provided on the upper wall 1. The viewport 2 is configured by forming a through hole in the upper wall 1, attaching a cylindrical tube portion 21 to the through hole, and fixing a hollow annular flange portion 22 to the tip of the tube portion 21. It is a thing. The flange portion 22 is provided with a cooling medium inlet 23 and a cooling medium outlet 24, and a cooling medium such as cooling water is fed into the flange portion 22 from the cooling medium inlet 23 to cool the flange portion 22. The first detection unit 5 attached to the flange portion 22 is not overheated.

  Further, a purge gas inlet 25 is attached to the cylindrical portion 21, and a purge gas such as argon or nitrogen is sent from the purge gas inlet 25 into the view port 2. The generated particulate product does not adhere to the viewport 2.

  A ring-shaped light source unit 3 is attached to the upper portion of the flange portion 22 of the viewport 2. This ring-shaped light source unit 3 is configured by arranging a plurality of light emitting diodes (LEDs) in a line on the same circumference, and the outer peripheral diameter formed by these light emitting diodes is made smaller than the inner peripheral diameter of the cylindrical portion 21. The plurality of light emitting diodes can be seen from below the view port 2.

The central portion of the ring-shaped light source unit 3 is a space, and the CCD camera 4 is attached to this space. The CCD camera 4 includes a lens 41 and a main body 42, and an image picked up by the lens 41 is converted into an electrical signal by a CCD element in the main body 42.
The mounting position of the lens 41 of the CCD camera 4 is determined so that the center axis thereof coincides with the center of the circumference formed by the ring-shaped light source unit 3. Further, the field of view of the lens 41 is determined so that the entire substrate to be imaged is reflected.

An electrical signal from the CCD camera 4 is sent to an image processing unit (not shown) provided separately, and receives an image processing operation described later, so that the tilt of the substrate is detected.
In addition, an inlet portion 25 of a source gas for film formation is provided at the top of the upper wall portion 1.
The ring-shaped light source unit 3 and the CCD camera 4 attached to the view port 2 constitute a first detection unit 5.

In FIG. 2, reference numeral 6 denotes a susceptor of the film forming apparatus. On the susceptor 6, a plurality of substrates 7, 7... Are placed in a circumferential shape, and each substrate 7 rotates and revolves as the susceptor 6 rotates.
A ring-shaped circumferential member 8 is provided outside the susceptor 6, and a flat base 9 is attached to one portion of the outer peripheral portion of the circumferential member 8 +.

A columnar support column 10 is erected on the base 9, and the support column 10 is rotatable with respect to the base 9. Further, a rod-like support arm 11 extending in the lateral direction is attached to the support column 10, and a second detection unit 12 is attached to the tip of the support arm 11.
The second detection unit 12 is the same as the first detection unit 5 and includes a ring-shaped light source unit 13 and a CCD camera 14.

The second detection unit 12 is moved to an operation position immediately above a certain substrate 7 on the susceptor 6 by the rotation of the support column 10, temporarily stopped here, and outside the chamber. It can be retracted to the retreat position.
An electrical signal from the CCD camera 14 of the second detection unit 12 is sent to the image processing unit.

Next, a method for detecting the tilt of the substrate in this film forming apparatus will be described.
First, the chamber of the film forming apparatus is opened, and a plurality of substrates 7, 7... Having at least one surface such as a sapphire substrate are placed on the susceptor 6 so that the mirror surface is the front surface. .

Subsequently, the support column 10 is rotated to stop the second detection unit 12 immediately above a certain substrate 7 on the susceptor 6 to detect the tilt of the substrate 7. If an inclination is detected, a countermeasure is taken so that there is no inclination. This operation is performed on all the substrates 7, 7... Placed on the susceptor 6 by rotating the susceptor 6.
According to the second detection unit 12, it is possible to know whether or not the substrate is tilted before the film formation, and it is possible to prevent the substrate from moving to the film formation process in an inappropriate state.

Next, the second detection unit 12 is retracted to the retreat position outside the chamber, the chamber of the film forming apparatus is closed, and a source gas for film formation is introduced into the chamber from the inlet 25 into the chamber. Perform membrane manipulation.
During this film forming operation, the first detector 6 provided in the view port 2 on the upper wall of the chamber detects the tilt of the substrates 7, 7.
If the tilt of the substrate 7 is detected during the film forming operation, the substrate is likely to be defective, so record it and remove the substrate 7 after the film forming operation is completed.

  According to the first detection unit 5, this can be used as a monitor during film formation, and the tilt of the substrate during film formation can be detected. During the film formation, the temperature inside the chamber becomes high, but since the first detection unit 5 is attached using the view port 2, the first detection unit 5 is not deteriorated by heat.

Next, the operation of detecting the tilt of the substrate in the present invention will be described.
Since the detection operation in the 1st detection part 5 and the 2nd detection part 12 is the same, operation in the 1st detection part 5 is described here.
When the first detection unit 5 is positioned immediately above the substrate 7 to be detected, the light from the ring-shaped light source unit 3 is directly illuminated on the substrate 7. As a result, the light from the ring-shaped light source 3 passes through the view port 2 and reaches the substrate 7, and an image of the ring-shaped light source unit 3 is reflected on the mirror surface of the substrate 7.

An image of the light source 3 is picked up by the CCD camera 4 to form an image signal, and this image signal is sent to the image processing unit for image processing.
This image processing is performed as follows, for example.
First, an image of the ring-shaped light source unit 3 in a correct state where the substrate 7 is not tilted is taken as a reference image.

Assuming a virtual inner circle or outer circle formed by the image of the ring-shaped light source unit 3 reflected in the reference image, the two-dimensional coordinates [X, Y] of the center of the virtual circle are obtained, and this is used as a reference value. Is stored in the memory of the image processing unit.
Next, the image of the ring-shaped light source unit 3 is taken similarly for the other substrate 7 to obtain the two-dimensional coordinates of the center of the virtual circle. Then, the coordinates are compared with the coordinates of the reference value.

  For example, when the coordinates of the reference value are [0, 0], if the coordinates of the other substrate 7 are [0.05, 0], it is determined that the substrate is inclined, and the reference coordinates The amount of movement (vector amount) from [0, 0] can be obtained to know the direction and degree of inclination from this amount of movement.

  When a light source other than the ring light source 3 is used, for example, when a light source composed of one light emitting diode is used, a position where the luminance of the image of the light source reflected on the mirror surface of the substrate 7 is highest is obtained by image processing. You may make it use the two-dimensional coordinate of this position as a reference point.

In the substrate processing apparatus of the present invention, it is possible to obtain the position (horizontal position) in the surface surface of the substrate in addition to the inclination of the substrate.
When the light from the ring-shaped light source 3 is directly illuminated on the substrate 7, the image of the ring-shaped light source 3 is reflected on the mirror surface of the substrate 7, and at the same time, the peripheral portion of the substrate 7 is illuminated to increase the brightness, and the susceptor on the outside 6 has a lower brightness than this, and this state is also picked up by the CCD camera 4 at the same time.

  In the image processing unit, the position of the peripheral portion of the substrate 7 is detected based on the difference in luminance at the boundary surface between the two parts. The position when the substrate 7 is placed at a normal position on the susceptor 6 is recorded in the memory as a reference position. The same operations and processes are performed on the other substrates 7 to detect the position of the peripheral portion of the substrate 7 and compare it with the reference position to detect the displacement of the substrate 7.

As described above, if the image processing unit has a function of detecting the position of the peripheral edge of the substrate, it is possible to know the position in the substrate surface other than the tilt of the substrate.
Further, if the susceptor 6 is rotatable, the image processing unit is provided with a function of capturing an image while rotating the susceptor 6 and confirming whether the rotation of the image and the rotation of the susceptor 6 are synchronized. If this is the case, it is possible to determine whether the substrate 7 or the susceptor 6 is inclined or the susceptor rotation axis is distorted.
Further, if the image processing unit is provided with a function for detecting the distortion of the substrate, it is possible to detect the warpage of the substrate itself and the presence or absence of the distortion.

Specific examples are shown below.
(Example)
As shown in FIG. 2, an MOCVD film forming apparatus equipped with a first detector and a second detector was used. This film forming apparatus mounts 10 2 inch sapphire substrates.
After all 10 substrates are placed, the substrates are sequentially passed directly under the second detection unit, and the light from the ring-shaped light source is directly illuminated for each substrate, and an image reflected on the sapphire substrate is captured. The mounting state was determined by analysis by image processing.

The deviation of the position of the reflected image was within 0.5 mm and the deviation of the position of the outer edge of the substrate was within 1 mm for all 10 substrates, and it was determined that there was no problem.
In view of this, a substrate fragment having a thickness of about 0.5 mm was placed under one substrate, and the substrate was tilted by placing it on the periphery of the mounting portion. At this time, the image of the ring-shaped light source moved in parallel on the screen, and it was confirmed that the degree of inclination was about 0.5 mm from the movement distance.

In this state, a film of gallium nitride (GaN) was formed on the substrate, and a light stripe pattern (fringe) appearing on the surface of the GaN film according to the thickness was observed. When the film was formed on a substrate inclined more than this, the film thickness distribution did not become a concentric distribution from the center of the substrate, and one side was thick and the other side was thin. The other substrates had a concentric distribution with little distribution.
This is presumably because the material gas flow on the tilted substrate is distributed or a thermal temperature distribution is generated.

It is drawing which shows the detection principle in this invention typically. It is a schematic perspective view which shows the principal part of the substrate processing apparatus of this invention.

Explanation of symbols

3 (13) ··· ring light source, 4 (14) · · CCD camera, 5 · · first detector, 7 · · · substrate, 12 · · · second detector

Claims (4)

A substrate processing apparatus provided with a substrate detection apparatus having a detection unit and an image processing unit comprising a light source and a camera,
The light source directly illuminates the mirror surface of the substrate whose one surface is a mirror surface,
The camera captures an image of a light source reflected on the mirror surface of the substrate,
The image processing unit compares a captured image captured by the camera with a pre-registered reference image, compares the positions of the reference points in the captured image and the reference image, and based on a reference point shift. And a substrate processing apparatus for detecting the tilt of the substrate.   The substrate processing apparatus according to claim 1, wherein a light source and a camera are integrated in the detection unit, and the detection unit is disposed above the mirror side of the substrate.   Two detection units are provided, the first detection unit is arranged in a viewport on the upper wall portion of the chamber of the substrate processing apparatus, and the second detection unit can be located in the chamber. 3. The substrate processing apparatus according to claim 1, wherein   4. The substrate processing apparatus according to claim 1, wherein the substrate processing apparatus is a film forming apparatus or an etching apparatus.

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