JPH0936093A - Method and device for detecting etching point of semiconductor wafer - Google Patents

Abstract

(57) Abstract: A semiconductor wafer etching point detecting method and detecting apparatus capable of easily and surely detecting an etching point. A CPU includes a horizontal H-shaped image capturing group 16a of a large number of pixels of an image sensor in order to reduce the amount of data processed for detecting an etching point.
Enable the detection result by. Image capture group 16a
Has two sides that determine the area of the rectangular region 6 and surely intersects the scribe line 3a. Of many pixels in the image capturing group 16a, the scribe line 3a
The cycle of intensity change detected by the pixel intersecting with becomes shorter,
The point corresponding to this pixel is determined as the etching point.

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 an etching point in a semiconductor wafer etching process in a semiconductor device manufacturing process.

A method of detecting a laser interference waveform is used to detect an etching end point in a semiconductor wafer etching process. The end point detection method by detecting the laser interference waveform is to detect the progress of etching by irradiating a portion (etching point) of the semiconductor wafer to be etched with laser light and detecting the interference waveform of the reflected light. . In order to carry out this end point detection method, it is required to easily and surely find the etching point of the semiconductor wafer.

[0003]

2. Description of the Related Art A plurality of chips are formed on a semiconductor wafer, and individual chips are formed by cutting the semiconductor wafer along scribe lines. This scribe line is also an etching point in the semiconductor wafer etching process. Therefore, conventionally, an arbitrary point on the scribe line is selected as an optimum point for accurately detecting this interference waveform in order to detect the etching end point by detecting the laser interference waveform.

In order to detect a scribe line as an etching point of a semiconductor wafer, the orientation flat of the semiconductor wafer is aligned with a reference line, and the semiconductor wafer is arranged so that each scribe line is parallel and orthogonal to the reference line. It After that, a scribe line is obtained by a known image processing method, or a scribe line is obtained based on predesignated teaching information.

[0005]

However, the conventional method for detecting a scribe line requires, for example, a condition such that the orientation flat of the semiconductor wafer is aligned with the reference line in order to easily detect the scribe line. Therefore, it takes a lot of time to detect the scribe line, and the scribe line cannot be detected when the semiconductor wafer is arranged so that the scribe line has an arbitrary direction with respect to the reference line.
Further, during the process of detecting a scribe line by image processing, if strong light enters from the outside, image recognition becomes difficult, and the scribe line (etching point) cannot be reliably detected.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an etching point detecting method and an etching point detecting apparatus capable of easily and surely detecting the etching point. is there.

[0007]

To achieve the above object, the invention of claim 1 irradiates a laser beam onto the semiconductor wafer during the etching process of the semiconductor wafer on which a plurality of chips are formed, The change in the intensity of the interference waveform of the reflected light at a large number of points in a rectangular area having an area that can include the chip was detected, and the point corresponding to the interference waveform with a short intensity change period was detected as the etching point.

According to the second aspect of the present invention, the semiconductor wafer is irradiated with the laser beam during the etching process of the semiconductor wafer in which the scribe lines for partitioning the plurality of chips are also etched, and the diagonal line is longer than the diagonal line of one chip. The change in the intensity of the interference waveform of the reflected light at a large number of points in the rectangular area is detected, and the point corresponding to the interference waveform having a short intensity change period is detected as the etching point.

According to a third aspect of the present invention, a change in the intensity of the interference waveform of a large number of consecutive points on at least two sides that determines the area of the rectangular region or the intensity of the interference waveform of a large number of consecutive points on the diagonal of the rectangular region. The change was detected, and the point corresponding to the interference waveform having a short intensity change period was detected as an etching point.

According to a fourth aspect of the present invention, during the etching process of the semiconductor wafer on which a plurality of chips are formed, the intensity change of the interference waveform of the reflected light of the laser light with which the semiconductor wafer is irradiated is detected to detect the semiconductor wafer. A semiconductor wafer etching point detecting device for detecting an etching point, comprising: a light detecting sensor for detecting a change in intensity of an interference waveform of a large number of points in a rectangular area having an area capable of containing one chip; And a determination unit that determines, as an etching point, a point corresponding to an interference waveform having a short intensity change period based on the detection result of the sensor.

According to a fifth aspect of the present invention, during the etching process of the semiconductor wafer in which the scribe lines for partitioning the plurality of chips are also etched, a change in the intensity of the interference waveform of the reflected light of the laser light with which the semiconductor wafer is irradiated is detected. A semiconductor wafer etching point detecting device for detecting an etching point of a semiconductor wafer by changing the intensity of interference waveforms of reflected light at a large number of points in a rectangular region having a diagonal line longer than the diagonal line of one chip. And a determination unit that determines, as an etching point, a point corresponding to an interference waveform having a short intensity change period based on the detection result of the light detection sensor.

According to the invention of claim 6, the determining means is continuous on at least two sides for determining the area of the rectangular region among the intensity changes of the interference waveform detected by the photodetection sensor at a large number of points in the rectangular region. The validation means is provided for validating only the intensity change of the interference waveform of a large number of points or the intensity change of the interference waveform of a large number of consecutive points on the diagonal of the rectangular region.
Then, the determining means determines, as an etching point, a point corresponding to the interference waveform having a short intensity change period, based on the intensity change of the interference waveform of the many points validated by the validating means.

(Operation) In the invention of claim 1, the cycle of intensity change of the interference waveform of the laser reflected light at the etching point of the semiconductor wafer becomes short. Since one chip has at least one etching point, the cycle of the intensity change is detected by detecting the intensity change of the interference waveform of the reflected light at a large number of points in a rectangular area having an area that can include one chip. At least one point corresponding to the short interference waveform is detected as an etching point.

According to the second aspect of the present invention, the scribe lines for partitioning the plurality of chips are also etched, and the scribe lines are flat over a relatively wide range in the semiconductor wafer. Therefore, the influence of laser light diffraction, scattering, etc. It is hard to receive. Therefore, since the rectangular area having a diagonal line longer than the diagonal line of one chip includes at least one point on the scribe line, by detecting the intensity change of the interference waveform of the reflected light at many points in the rectangular area,
A point on the scribe line is easily and surely detected as an etching point.

According to the third aspect of the present invention, at least two sides that determine the area of the rectangular region or the diagonal lines of the rectangular region intersect with the scribe line, so that only changes in the intensity of the interference waveform at some points in the rectangular region are detected. Thus, the intersecting point on the scribe line can be easily and surely detected as the etching point.

According to the fourth aspect of the present invention, the cycle of intensity change of the interference waveform of the laser reflected light at the etching point of the semiconductor wafer becomes short. At least 1 per chip
There are two etching points. The photodetection sensor detects the intensity change of the interference waveform of the reflected light at a large number of points in a rectangular area having an area that can include one chip. Based on the detection result of the light detection sensor, a point corresponding to the interference waveform having a short intensity change cycle is determined as the etching point by the determination means.

In the invention of claim 5, the scribe line for partitioning a plurality of chips is also etched. The photodetection sensor detects the intensity change of the interference waveform of the reflected light at many points in a rectangular area having a diagonal line longer than the diagonal line of one chip. Since this rectangular region includes at least one point on the scribe line, the determining means can easily and reliably detect the point on the scribe line as an etching point.

In the sixth aspect of the invention, the intensity change of the interference waveform at a large number of points in the rectangular area is detected by the photodetection sensor. Among the detection results, only the change in the intensity of the interference waveform at a large number of points on at least two sides that determine the area of the rectangular region or the change in the intensity of the interference waveform at a large number of points on the diagonal of the rectangular region is effective by the validating means. Becomes Since the two sides of the rectangular area or the diagonal lines of the rectangular area validated by the validating means intersect the scribe line, the determining means can easily and reliably detect a point on the scribe line as an etching point.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is embodied in a semiconductor wafer etching point detecting apparatus will be described below with reference to FIGS.

As shown in FIG. 1, the etching chamber 1
The inside of is kept at a low pressure, and the etching gas is introduced into the etching chamber 1 under predetermined conditions. Then, the etching gas is turned into plasma by microwaves or the like, and the semiconductor wafer 3 mounted on the stage 2 is etched. The semiconductor wafer 3 is an etching point at which the scribe lines 3a (shown in FIGS. 3 and 4) that partition the plurality of chips 3b are also etched.

The etching point detecting device 10 detects the etching point by detecting the interference waveform of the laser reflected light during the etching process of the semiconductor wafer 3.

The etching point detection device 10 comprises a semiconductor laser 11, a lens 12, a half mirror 13, a camera 14, and a control device 17. The semiconductor laser 11 emits laser light having a predetermined wavelength. The lens 12 emits laser light emitted from the semiconductor laser 11 into one chip 3
The parallel light is such that it is irradiated onto the rectangular region 6 having a diagonal line longer than the diagonal line of b. Such a rectangular area 6 is
As shown in FIGS. 3 and 4, the rectangular region 6 includes a part of the scribe line 3b regardless of the position of the orientation flat 3c of the semiconductor wafer 3. In the present embodiment, the rectangular area 6 has an area that can completely include one chip 3b. In this specification, the term “include” means the same as the case of including.

The half mirror 13 irradiates the laser beam collimated by the lens 12 through the detection window 4 of the etching chamber 1 so as to be orthogonal to the semiconductor wafer 3 being etched. At this time, the laser light is reflected on the surface of the film to be etched of the semiconductor wafer 3 and is also reflected on the surface of the lower layer of the film to be etched. The two reflected lights cause interference depending on their phases. The half mirror 13 reflects the reflected light from the semiconductor wafer 3 onto the camera 14
Reflect to the side.

The camera 14 is provided with a lens 15 and an image sensor 16 as a light detecting sensor formed of a CCD. The lens 15 refracts the reflected light from the half mirror 13 and projects it on the image sensor 16. As shown in FIG. 2, the image sensor 16 is composed of a large number of pixels arranged in the vertical and horizontal directions, and these large numbers of pixels detect changes in the intensity of the interference waveform of the reflected light at a large number of points in the rectangular area 6. Then, an electric signal corresponding to the detected intensity of the reflected light is output to the control device 17.

The control device 17 includes an analog-digital converter (A / D converter) 18, a CPU 19 as a validating means and a determining means, a ROM 20 and a RAM 21.
The A / D converter 18 inputs the electric signal output from the image sensor 16 and converts it into a digital signal. RAM
Reference numeral 21 stores the digital signal output from the A / D converter 18 as data. The ROM 20 stores a control program including a program for detecting the etching point of the semiconductor wafer 3.

The CPU 19 uses the control program stored in the ROM 20 to reduce the amount of data to be processed for detecting the etching point.
As shown in FIG. 2, the A / D conversion by the A / D converter 18 is controlled so that the detection result by the horizontal H-shaped image capturing group 16a among the six pixels can be validated. . This is because the image capturing group 16a has two sides that determine the area of the rectangular region 6 and surely intersects the scribe line 3a as shown in FIG. Then, as shown in FIG. 5, among a large number of pixels in the image capturing group 16a, the cycle of the intensity change corresponding to the point on the scribe line 3a indicated by the solid circle becomes short as shown in FIG. 6 (a). . In addition, among many pixels in the image capturing group 16a, the intensity change cycle corresponding to a point indicated by a broken line circle (a point not on the scribe line 3a) becomes long as shown in FIG. 6B. This is because the etching points are etched rapidly, and the points that are not the etching points are hardly etched.

As the image capturing group of the image sensor 16 validated by the CPU 19, an image capturing group 16b having a vertical U-shape shown in FIG. 7 and an image capturing group 16c matching a diagonal line as shown in FIG. 8 are also included. It can be set. This is because the vertical U-shaped image capturing group 16b shown in FIG. 7 also has two sides that determine the area of the rectangular region 6 and surely intersects the scribe line 3a. Further, the image capturing group 16c shown in FIG. 8 coincides with the diagonal line of the rectangular region 6 longer than the diagonal line of the chip 3b, so that it surely intersects the scribe line 3a at least at one place.

Then, based on the control program of the ROM 20, the CPU 19 corresponds to the interference waveform having a short period of intensity change among the data of the intensity change of the interference waveform of a large number of points of the image capturing group 16a stored in the RAM 21. The point to be etched is determined as the etching point. In the semiconductor wafer 3, the points determined as the etching points include not only the points on the scribe line 3a but also the etching points on the chip 3b.

As described above, in this embodiment, in the semiconductor wafer 3 in which the scribe lines 3a for partitioning the plurality of chips 3b are also etched, the area of the rectangular region 6 having an area capable of containing one chip 3b is determined. The image capturing group 16a having at least two sides is set. Therefore, the point where the image capturing group 16a intersects the scribe line 3a can be easily and reliably detected as an etching point.

Further, in this embodiment, the CPU 19 is
As shown in FIG. 2, among a large number of pixels of the image sensor 16, the detection result by the horizontal H-shaped image capturing group 16a is validated, so that the amount of data to be processed for detecting the etching point is large. Can be reduced, and the etching point detection process can be performed at high speed.

The present invention can be embodied by being arbitrarily modified as follows. (1) As an image sensor in the camera 14, FIG.
As shown in, the image sensor 25 in which a large number of pixels are arranged in a horizontal H shape may be used. That is, the image sensor detects only the intensity change of the interference waveform of a large number of continuous points on at least two sides that determine the area of the rectangular region 6 or the intensity change of the interference waveform of a large number of continuous points on the diagonal of the rectangular region 6. You may make it use what was formed in the detectable shape. According to this configuration, the CPU 19 does not need to enable the pixels of the image sensor, and the CPU 19 determines the etching point faster based on only the intensity change of the interference waveform of many points detected by the image sensor 25. be able to.

(2) One chip 3b detected by the image sensor 16 is eliminated while eliminating the pixel activation processing of the image sensor 16 by the CPU 19.
Based on changes in the intensity of the interference waveform of the reflected light at all points in the rectangular region 6 having an area that can completely include, the point corresponding to the interference waveform with a short intensity change period is determined as the etching point. Good. In this case, the amount of data for determining the etching point is larger than that in the above-described embodiment, but the arrangement conditions of the semiconductor wafer 3 for detecting the etching point and the like are unnecessary, and the conventional etching is performed. The etching point can be detected easily and surely as compared with the point detection method.

(3) The rectangular area is made to match the size of one chip, and based on the intensity change of the interference waveform of the reflected light at all points in this rectangular area, an interference waveform having a short intensity change cycle is obtained. The corresponding point may be determined as the etching point. When such a rectangular region is arranged at an arbitrary position with respect to the semiconductor wafer 3, the rectangular region overlaps a plurality of chips, and the rectangular region includes a part of the plurality of chips, but these parts are combined. This is because one chip has at least one etching point.
Also in this case, the amount of data for determining the etching point is larger than that in the above-described embodiment, but the arrangement condition of the semiconductor wafer 3 for detecting the etching point and the like are unnecessary, and the conventional etching is performed. The etching point can be detected easily and surely as compared with the point detection method.

The technical ideas other than the claims that can be understood from the above-described embodiments will be described below along with their effects. (B) The photodetector sensor only changes the intensity of the interference waveform at a number of consecutive points on at least two sides that determine the area of the rectangular region or the intensity of the interference waveform at a number of consecutive points on the diagonal of the rectangular region. The etching point detection device for a semiconductor wafer according to claim 5, wherein the etching point detection device is formed in a shape capable of detecting the above.

According to this structure, the etching point can be determined at a higher speed based only on the intensity change of the interference waveform of a large number of points detected by the light detection sensor.

[0036]

As described above in detail, according to the inventions of claims 1 and 2, the etching point of the semiconductor wafer can be easily and surely detected.

According to the invention of claim 3, in addition to the effect of the inventions of claims 1 and 2, the etching point can be determined at high speed. The inventions of claims 4 and 5 have the same effects as the inventions of claims 1 and 2.

The invention of claim 6 has the same effect as the invention of claim 3.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an etching point detection device according to an embodiment.

FIG. 2 is an explanatory diagram showing an example of capturing pixels by an image sensor.

FIG. 3 is an explanatory diagram showing a relationship between a semiconductor wafer and a rectangular area.

FIG. 4 is an explanatory diagram showing a relationship between a semiconductor wafer and a rectangular area.

FIG. 5 is an explanatory diagram showing an example of capturing pixels on a scribe line.

FIG. 6A is a waveform diagram showing an interference waveform on an etching point, and FIG. 6B is a waveform diagram showing an interference waveform other than the etching point.

FIG. 7 is an explanatory diagram showing another image sensor.

FIG. 8 is an explanatory diagram showing another image sensor.

FIG. 9 is an explanatory diagram showing another image sensor.

[Explanation of symbols]

 3 Semiconductor Wafer 3a Scribe Line 3b Chip 6 Rectangular Area 16 Image Sensor as Light Detection Sensor 19 CPU as Determining Means and Validating Means

Front page continuation (72) Inventor Kazuyuki Uchida 1844-2, Kozoji-cho, Kasugai-shi, Aichi Prefecture Fujitsu Viersuai Co., Ltd. Within the corporation

Claims (6)

[Claims] 1. During the etching process of a semiconductor wafer having a plurality of chips formed thereon, the semiconductor wafer is irradiated with laser light to reflect light reflected from a large number of points in a rectangular area having an area capable of containing one chip. A method for detecting an etching point of a semiconductor wafer, which detects an intensity change of an interference waveform and detects a point corresponding to an interference waveform having a short intensity change period as an etching point. 2. A plurality of rectangular regions each having a diagonal line longer than a diagonal line of one chip by irradiating the semiconductor wafer with a laser beam during an etching process of a semiconductor wafer in which a scribe line for partitioning a plurality of chips is also etched. A method for detecting an etching point of a semiconductor wafer, which detects an intensity change of an interference waveform of reflected light at the point, and detects a point corresponding to the interference waveform having a short intensity change period as an etching point. 3. An intensity change in the interference waveform of a large number of consecutive points on at least two sides that determine the area of the rectangular region or an intensity change of the interference waveform of a large number of consecutive points on the diagonal of the rectangular region is detected. 3. The method for detecting an etching point of a semiconductor wafer according to claim 2, wherein a point corresponding to an interference waveform having a short intensity change cycle is detected as an etching point. 4. The etching point of the semiconductor wafer is detected by detecting a change in the intensity of the interference waveform of the reflected light of the laser light with which the semiconductor wafer is irradiated during the etching process of the semiconductor wafer having a plurality of chips formed thereon. An etching point detection device for a semiconductor wafer, which is configured to detect, and a photodetection sensor for detecting a change in intensity of an interference waveform of a large number of points in a rectangular region having an area capable of containing one chip, An etching point detection device for a semiconductor wafer, comprising: a determination unit that determines, as an etching point, a point corresponding to an interference waveform having a short intensity change cycle based on the detection result of the detection sensor. 5. The semiconductor by detecting a change in intensity of an interference waveform of reflected light of a laser beam applied to the semiconductor wafer during an etching process of the semiconductor wafer in which a scribe line for partitioning a plurality of chips is also etched. A semiconductor wafer etching point detecting device for detecting an etching point of a wafer, which detects an intensity change of an interference waveform of reflected light at a large number of points in a rectangular region having a diagonal line longer than a diagonal line of one chip. And a determination unit that determines, as an etching point, a point corresponding to an interference waveform having a short intensity change cycle based on a detection result of the optical detection sensor. 6. The deciding means decides the area of the rectangular region among a plurality of consecutive intensity changes of the interference waveform detected by the photodetection sensor at a large number of points of the rectangular region. Of the interference waveform of the point or the interference waveform of a large number of consecutive points on the diagonal of the rectangular region, the validating means for validating only the change, the determining means is valid by the validating means. 6. The etching point detecting device for a semiconductor wafer according to claim 5, wherein a point corresponding to an interference waveform having a short intensity change cycle is determined as an etching point based on the intensity change of the interference waveform at the point.