JPH11145228A - Stacking fault inspection method and semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently and non-destructively inspect a stacking fault on a surface of a semiconductor wafer. SOLUTION: The surface of a semiconductor wafer 1 is conceptually divided into a plurality of cells. A light spot 41 formed on the surface of the semiconductor wafer 1 is scanned as the stage 10 moves. The image of the cell illuminated by the light spot 41 is picked up by the high-speed image sensor 19 and is stored in the image memory 2.
0 and 21 are stored alternately in cell units. The image processor 22 compares the images in the image memories 20 and 21 with each other and searches for a mismatching portion, thereby detecting a stacking fault existing on the surface of the semiconductor wafer 1. Stacking faults and other abnormalities are identified based on the shape of the mismatched portion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a stacking fault of a semiconductor wafer and a semiconductor wafer inspected by using the method, and more particularly to a method for realizing a nondestructive and efficient inspection. Regarding improvement.

[0002]

2. Description of the Related Art Stacking faults are planar lattice defects formed by disturbing the stacking order of atomic planes of a crystal. In the step of forming a crystalline semiconductor wafer by the Czochralski (CZ) method or the epitaxial growth method, this stacking fault may appear. If stacking faults are present on the surface of a semiconductor wafer on which semiconductor devices are to be formed, the characteristics of the device will be degraded. ing.

FIG. 13 is a process chart showing a conventional method for inspecting for stacking faults present on the surface of a semiconductor wafer. FIG. 13A is a cross-sectional view of the semiconductor wafer 1 to be inspected, and has a cross-sectional structure along a plane orthogonal to the extending direction of the stacking fault 2 that is present on the surface of the semiconductor wafer 1 by way of example. Is schematically shown. Since the stacking fault 2 is a surface defect as described above, it has a planar spread. For this reason, the stacking fault 2 corresponds to FIG.
As shown in (a), the semiconductor wafer 1 exists so as to penetrate from the surface of the semiconductor wafer 1 to a deep portion, and further, although not shown, exists along the surface of the semiconductor wafer 1.

As shown in FIG. 13B, a semiconductor wafer 1 shown in FIG. 13A has a write liquid (HF, H) stored in a corrosion-resistant container 153 made of fluororesin.
Selective wet etching treatment by dipping in an etching solution 154 such as NO ₃ , Cr ₂ O ₃ , Cu (NO ₃ ) ₂ .3H ₂ O, a mixture of H ₂ O, and CH ₃ COOH) Is applied. As a result, a portion where the stacking faults 2 exist on the surface of the semiconductor wafer 1 is selectively etched, and is exposed as a selective corrosion portion 3.

After that, the semiconductor wafer 1 is pulled up from the etching solution 154, and as shown in FIG.
The optical microscope (metallic microscope) 155 is used for surface observation. That is, the irradiation light is focused on the surface of the semiconductor wafer 1 by the lenses 157 and 158 as a light spot 156, and the light spot 156 is scanned (scanned) along the surface of the semiconductor wafer 1. By observing the selective corrosion portion 3 while scanning the light spot 156,
An inspection for stacking faults 2 over the entire surface of the semiconductor wafer 1 is performed.

[0006]

In the conventional method, as described above, by forming the selective corrosion portion 3 on the surface of the semiconductor wafer 1, it is possible to inspect the stacking fault 2 by the optical microscope 155. That is, the conventional method is a destructive inspection, and there is a problem that the stacking fault 2 cannot be detected without damaging the semiconductor wafer 1 to be inspected.

In addition, since the etching solution 154 contains heavy metals such as chromium, inspection is performed in a clean room in which the manufacture of the semiconductor wafer 1 and the manufacture of semiconductor devices using the semiconductor wafer 1 are performed so as not to cause heavy metal contamination. Was done outside, ie offline. For this reason, there was a problem that work efficiency was poor. further,
All work had to be done manually, which also led to reduced work efficiency. In addition, the optical microscope 15
In order for the inspection to be performed through visual observation using 5, 10
There is also a problem in inspection accuracy that only stacking faults 2 having a size of about μm or more can be detected.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the conventional method, and enables non-destructive and efficient inspection of stacking faults on the surface of a semiconductor wafer. It is an object of the present invention to obtain a stacking fault inspection method and to provide a semiconductor wafer inspected by using this method.

[0009]

According to a first aspect of the present invention, there is provided a method for inspecting a stacking fault present on a surface of a semiconductor wafer, wherein the surface is divided into a plurality of cells arranged on the surface. , The step of conceptually dividing, and the light spot capable of irradiating at least one of the plurality of cells, by scanning along the surface, the scanning step of sequentially irradiating the plurality of cells one by one, In accordance with the scanning step, an imaging step of sequentially imaging the plurality of cells irradiated with the light spot one by one, a storage step of storing an image captured in the imaging step, and a storage step of storing the image captured in the storage step. Comparing the two images among the two different cells among the plurality of cells, and searching for an inconsistency, thereby detecting an abnormality including the stacking fault present on the surface. .

In a second aspect of the present invention, in the stacking fault inspection method of the first aspect, the abnormality detecting step includes a step of setting the shape of the mismatched portion in the image to a predetermined shape unique to the stacking fault. A step of selectively detecting only the stacking fault by determining whether or not the stacking fault is within the range.

[0011] A third aspect of the present invention is the stacking fault inspection method according to the first or second aspect, wherein the semiconductor wafer is placed on the semiconductor wafer in an oxygen atmosphere prior to the scanning step.
Forming a semiconductor oxide film having a thickness of 200 Å or more on the surface by performing dry oxidation at a temperature of 1000 ° C. or less.

According to a fourth aspect of the present invention, in the stacking fault inspection method of the first or second aspect, prior to the scanning step, the semiconductor wafer is placed in an ammonia gas atmosphere at 1000 ° C. or lower. Forming a semiconductor nitride film having a thickness of 200 Å or more on the surface by performing annealing at a temperature.

According to a fifth aspect of the present invention, in the stacking fault inspection method for checking stacking faults present on the surface of a semiconductor wafer, a light spot formed by irradiating the surface with laser light in an oblique direction is provided. A scanning step of scanning along the surface, a scattered light detection step of detecting scattered light of the laser light in the scanning step, a storage step of storing a detection result in the scattered light detection step, and the storage An abnormality detection step of detecting an abnormality including the stacking fault present on the surface based on the detection result stored in the step.

According to a sixth aspect of the present invention, in the stacking fault inspection method of the fifth aspect, the abnormality detecting step includes, based on the detection result, changing a pattern shape of a portion of the surface where the scattered light is detected. A step of selectively detecting only the stacking fault by determining whether or not the stacking fault is within a predetermined range of the shape unique to the stacking fault.

According to a seventh aspect of the present invention, in the stacking fault inspection method of the fifth or sixth aspect, the semiconductor layer present on at least the surface of the semiconductor wafer is a single crystal semiconductor layer having a plane orientation of {100}. For stacking faults extending along one of two <110> directions orthogonal to each other along the surface of the single crystal semiconductor layer, the incident direction of the laser light at which the intensity of the scattered light is highest is The specific incident direction, the scattering direction having the highest scattering intensity is defined as the specific scattering direction, and the scanning step includes a first scanning step and a second scanning step performed thereafter, and the scattered light detection step includes A first scattered light detection step and a second scattered light detection step executed thereafter;
In the first scanning step, the laser light is irradiated on the surface from the specific incident direction, and the formed light spot is scanned along the surface, and in the first scattered light detection step, the first scanning is performed. In the step, scattered light in the specific scattering direction is detected, and in the second scanning step, the surface is irradiated with the laser light from a direction rotated by 90 degrees along the surface with respect to the specific incident direction. Scanning the formed light spot along the surface, and in the second scattered light detection step, in the second scanning step, rotated by 90 degrees along the surface with respect to the specific scattering direction. The scattered light in the direction is detected.

According to an eighth aspect of the present invention, in the stacking fault inspection method of the second or sixth aspect, the semiconductor layer present on at least the surface of the semiconductor wafer is a single-crystal semiconductor layer having a plane orientation of {100}. In the scanning step, a scanning direction of the light spot is set to one of two <110> directions orthogonal to each other along a surface of the single crystal semiconductor layer.

The semiconductor wafer according to the ninth aspect is inspected by using the stacking fault inspection method according to any one of the first to eighth aspects, so that the semiconductor wafer is classified as having no stacking fault.

The semiconductor wafer according to the tenth aspect of the present invention is inspected by using the stacking fault inspection method according to any one of the first to eighth aspects, whereby the location of the abnormality is clarified.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> FIG. 1 is a block diagram showing a configuration of an inspection apparatus for automatically and efficiently realizing the inspection methods of the first to third embodiments with high accuracy.
The inspection apparatus 101 itself has the same configuration as a conventionally known apparatus used for inspection after semiconductor elements are formed on a semiconductor wafer. That is, the apparatus 101 includes the stage 10, and the semiconductor wafer 1 to be inspected is placed on the stage 10.
Above the stage 10, a light source 11 is provided, and irradiation light generated by the light source 11 passes through the lens 12, the half mirrors 14, 27, and the objective lens 13 to be applied to the surface of the semiconductor wafer 1. A light spot 41 is formed.

The light source 11 is, for example, a HgXe (mercury xenon) lamp that generates light having a wavelength of 530 nm. The optical axis of the irradiating light is perpendicular to the surface of the semiconductor wafer 1, and as a result,
The optical axis of the reflected light is also perpendicular to the surface of the semiconductor wafer 1. The reflected light passes through the objective lens 13 and the half mirror 27 and is reflected by the half mirror 14, whereby the direction of the reflected light is bent so as to travel to the magnification conversion lenses 15, 16, and 17.

The reflected light passing through the lenses 15, 16 and 17 is split into two directions by the half mirror 18, and is incident on both the camera 23 and the high-speed image sensor 19. The camera 23 and the high-speed image sensor 19 detect the incident reflected light, and
An image of the area illuminated by the light spot 41 on the surface of the camera is captured in real time.

The stage 10 is capable of translation along two horizontal directions X and Y, rotation along a rotation direction θ about a vertical axis, and translation along a vertical direction Z. The movement of the stage 10 along these directions is controlled by the control unit 31. The control unit 31 includes a stage 1
While repeatedly reciprocating 0 along the X direction, for example,
The gradual movement in the Y direction allows the light spot 41 to scan over the entire surface of the semiconductor wafer 1.

In the course of this scanning, the high-speed image sensor 1
9 are stored in two image memories 20, 21.
Is stored while being alternately updated. Then, the image processor 22 detects the stacking fault 2 by comparing the images of the two image memories 20 and 21 with each other.
The high-speed image sensor 19 and the camera 23 are also connected to a display screen 24, and an image captured by the high-speed image sensor 19 and the camera 23 can be enlarged and displayed on the display screen 24 for visual observation.

The apparatus 101 is provided with another light source 25 for realizing an auto-focus function, in addition to the light source 11 for supplying irradiation light for enabling image pickup. The light source 25 generates light having a wavelength of, for example, 650 nm to 700 nm. The generated light is transmitted through a lens 26, half mirrors 28 and 27,
Then, the light spot is formed on the semiconductor wafer 1 through the objective lens 13 in the same manner as the light spot 41.
Then, the reflected light passes through the objective lens 13, the half mirrors 27 and 28, and the lens 29, and then enters the optical sensor 30 functioning as an autofocus sensor.

The optical sensor 30 detects whether or not the light passing through the objective lens 13 is focused on the surface of the semiconductor wafer 1 through the incident reflected light, and supplies the detected result to the control unit 31. I do. The control unit 31 controls the position of the stage 10 in the vertical direction Z based on the supplied result so that the light passing through the objective lens 13 is focused on the surface of the semiconductor wafer 1. As a result, the light spot 41 of the irradiation light generated by the light source 11 is always
Will be focused on the surface.

FIG. 2 is an operation explanatory view showing a procedure for scanning the light spot 41 over the entire surface of the semiconductor wafer 1. In this example, the surface of the semiconductor wafer 1 is oriented so that its plane orientation is {100}, and is scanned along X and Y directions corresponding to two <110> directions orthogonal to each other along the surface. Is performed. That is, the light spot 41 repeats the scanning from one end of the semiconductor wafer 1 to the other end along the scanning line 40 in the X direction, and at the same time, sets the scanning line 40 to the Y direction.
Shift gradually along the direction.

In other words, the scanning of the light spot 41 is
For example, the X direction is set as the main scanning direction, and the Y direction is set as the sub scanning direction. As a result, scanning of the light spot 41 over the entire surface of the semiconductor wafer 1 is performed. The movement of the light spot 41 is a movement relative to the semiconductor wafer 1, and as described above, the control unit 31
Is moved along the X and Y directions to realize scanning of the light spot 41.

FIG. 3 is an enlarged view showing a partial region A on the surface of the semiconductor wafer 1 shown in FIG. FIG.
As shown in (1), the surface of the semiconductor wafer 1 is conceptually divided into regions (here, referred to as “cells”) arranged in a matrix along the X and Y directions that are the main and sub scanning directions. The shape and size of the cell is, for example, a rectangle having a width of several mm on one side.

The light spot 41 sequentially moves from one cell to the next adjacent cell with scanning. That is, the light spot 41 sequentially illuminates each cell in the process of moving along the scanning line 40, for example, in the order of the cells 42, 43, and 45. In FIG. 3, the light spot 41 is at a position that illuminates the cell 43 at the present time. The spread of the light spot 41 created by the light source 11 is large enough to cover one cell,
For example, the diameter is set to about 10 mm.

While the light spot 41 illuminates the cell 42, an image of the cell 42 is captured by the high-speed image sensor 19 and stored in one of the image memories 20 and 21. Further, while the light spot 41 illuminates the next cell 43, an image of the cell 43 is captured by the high-speed image sensor 19, and the image memory 20,
The image of the cell 42 which is the immediately preceding cell in the cell 21 is stored in the other cell.

In the same manner, the images of the irradiated cells are alternately stored in the image memories 20 and 21 as the light spot 41 is scanned. Each of the image memories 20, 21 is readable and writable, and has a storage capacity sufficient to store an image of one cell. As shown in FIG. 3, when a stacking fault 2 exists on the surface of the semiconductor wafer 1, the stacking fault 2 is reflected as a portion having a different luminance in an image of a cell to which the stacking fault 2 belongs. The surface of the semiconductor wafer 1
When the stacking fault 2 is oriented in the {100} direction, the image of the stacking fault 2 is displayed as a linear region extending along one of the two <110> directions.

FIG. 4 is an operation explanatory diagram showing a procedure of image comparison by the image processor 22. In the example of FIG.
The image of the cell 42 is stored in the image memory 20,
The image memory 21 stores an image of the cell 43.
An image of one cell is constituted by a large number of pixels 48 arranged in a matrix. The pixel 48 is a constituent unit of an image, and its width is minute, for example, about 0.2 μm in terms of the width along the surface of the semiconductor wafer 1. That is,
By using the apparatus 101, the surface of the semiconductor wafer 1 can be imaged with a resolution of about 0.2 μm.

The image processor 22 compares the images stored in the two image memories 20 and 21 with each other. The comparison of the images is made by comparing the brightness between each corresponding pixel 48. In the example of FIG. 4, the image of the cell 42 stored in the image memory 20 reflects the stacking fault 2 extending in the Y direction.
The image of the cell 43 stored in 1 reflects another stacking fault 2 extending along the X direction.

The image processor 22 compares each pixel in the area corresponding to the stacking fault 2 of the cell 42 with each pixel in the area 46 of the cell 43 corresponding to the stacking fault 2.
Is detected. Similarly, by comparing each pixel of the area corresponding to the stacking fault 2 of the cell 43 with each pixel of the area 47 of the cell 42 corresponding thereto, the cell 4
The stacking fault 2 existing in 3 is detected.

The position of the detected stacking fault 2 or
The position of the cell including the stacking fault 2 is represented by, for example, a coordinate value or the like, stored in a storage unit built in the image processor 22, and output as needed. An operator who operates the apparatus 101 can grasp the position of the stacking fault 2 existing on the surface of the semiconductor wafer 1 or the position of the cell including the stacking fault 2 by reading the output data.

The inspected semiconductor wafer 1 is sorted into, for example, a defective product including the stacking fault 2 and a non-defective product not including the stacking fault 2, and only the non-defective product is shipped. Alternatively, it is possible to ship all the semiconductor wafers 1 irrespective of whether they are good or defective, together with data on the position of the stacking fault 2.
A semiconductor device maker that has delivered a semiconductor wafer 1 sorts a semiconductor chip including a stacking fault 2 and a semiconductor chip not including the stacking fault 2 after forming predetermined semiconductor elements in the semiconductor wafer 1, and determines a non-defective product including no stacking fault 2 Only the semiconductor chip described above can be used for manufacturing a semiconductor device.

By setting the cell so as to correspond to a region to be cut out as a semiconductor chip, that is, a virtual chip as it is, or to correspond to a region obtained by further dividing the virtual chip into a plurality of parts. In addition, the sorting of the semiconductor chips can be performed more easily. At this time, it is sufficient that only data relating to the position of the cell including the stacking fault 2 is provided as data relating to the position of the stacking fault 2.

Since the resolution of the device 101 can be increased to about 0.2 μm, the stacking fault 2 having a size of about 0.5 μm can be detected by using the apparatus 101. That is, by using the device 101, the inspection accuracy can be dramatically improved as compared with the conventional method. In addition, there is an advantage that the inspection can be performed in a non-destructive manner without damaging the semiconductor wafer 1. Since it is non-destructive, the semiconductor wafer 1 after the inspection can be used for manufacturing semiconductor elements. This enables inspection of all the semiconductor wafers 1.

In addition, since it is not necessary to use a chemical solution containing a heavy metal, the inspection can be performed in a clean room, that is, inline. For this reason, there is an advantage that the work efficiency is improved. Further, since all operations are performed automatically without human intervention, the operation efficiency is improved in this respect as well.

It is to be noted that the semiconductor wafer 1 may have an abnormality other than the stacking fault 2, for example, a defect of another form, a surface scratch, a foreign matter, etc., and it is necessary to detect these abnormalities. Or these abnormalities and stacking fault 2
The method using the device 101 can easily cope with the case where it is necessary to identify These abnormalities other than the stacking fault 2 can be detected by comparing the images in the manner shown in FIG.

As described above, when the surface of the semiconductor wafer 1 is oriented in the {100} direction, the stacking fault 2
Is displayed as a linear region extending along one of the two <110> directions. For this reason, from various types of abnormalities shown in the image of the cell stored in the image memories 20 and 21, linearly extend in any one of two orthogonal <110> directions along the surface. By searching for an abnormality reflected as an existing image, it is possible to identify the stacking fault 2 from other detected abnormalities.

This processing can be easily executed by the image processor 22 at a high speed synchronized with the scanning of the light spot 41. Further, it is also possible to selectively detect only the stacking fault 2 among various abnormalities. In particular, as shown in FIG.
When matching with any of the <110> directions, there is an advantage that the sorting of the stacking fault 2 is easier.

The position of the cell containing the stacking fault 2 and the like is
Since the light spot 41 is stored as data, after the scanning of the light spot 41 is completed, the position of the light spot 41 is again adjusted to the position of the cell where the stacking fault 2 is found based on the stored data, for example. It is also possible to project an image of the cell picked up by 23 or the high-speed image sensor 19 on a display screen 24 and visually check whether or not it is a stacking fault 2 by an operator's visual observation. That is, the accuracy of sorting the stacking faults 2 can be further increased visually.

<Second Embodiment> FIG. 5 is a process diagram showing a pre-processing step applied to a semiconductor wafer 1 to be inspected in a method according to a second embodiment. In the pretreatment, the semiconductor wafer 1 prepared as shown in FIG. 5A is subjected to a dry oxidation treatment in an oxygen atmosphere at a temperature of 1000 ° C. or less. As a result, as shown in FIG. 5B, the oxide film 4 is formed on the surface of the semiconductor wafer 1 in a non-destructive manner without damaging the semiconductor wafer 1. The stacking faults 2 existing on the surface of the semiconductor wafer 1 are covered with the oxide film 4. The thickness T of the oxide film 4 is desirably 20
Set to 0 angstroms or more. Semiconductor wafer 1
Is a silicon wafer, oxide film 4 is formed as a silicon oxide film.

The semiconductor wafer 1 on which the oxide film 4 has been formed
As shown in FIG. 5C, the stacking fault 2 is placed on the stage 10 of the apparatus 101 and is similar to the first embodiment.
To be tested. Since the oxide film 4 is formed on the surface of the semiconductor wafer 1, the high-speed image sensor 19
In addition, in the image captured by the camera 23, the difference in luminance between the portion where the stacking fault 2 exists and the portion where the stacking fault 2 does not exist becomes clearer due to the light interference effect. as a result,
Since the detection sensitivity for the stacking fault 2 is further improved, the inspection accuracy is further improved. Further, the oxide film 4 has an advantage that it can be easily made thicker than a nitride film described later.

<Embodiment 3> FIG. 6 is a process chart showing a pre-processing step applied to a semiconductor wafer 1 to be inspected in the method of Embodiment 3. In the pretreatment, the semiconductor wafer 1 prepared as shown in FIG.
Annealing is performed in a H ₃ (ammonia gas) atmosphere at a temperature of 1000 ° C. or less. As a result, FIG.
As shown in FIG. 3B, the nitride film 5 is formed on the surface of the semiconductor wafer 1 in a non-destructive manner without damaging the semiconductor wafer 1.
Is formed. As a result, the stacking faults 2 present on the surface of the semiconductor wafer 1 are covered with the nitride film 5.
The thickness T of the nitride film 5 is desirably set to 200 Å or more, as in the second embodiment. When semiconductor wafer 1 is a silicon wafer, nitride film 5 is formed as a silicon nitride film.

The semiconductor wafer 1 on which the nitride film 5 has been formed
As shown in FIG. 6C, the stacking fault 2 is mounted on the stage 10 of the apparatus 101 and is similar to the first embodiment.
To be tested. Since the nitride film 5 is formed on the surface of the semiconductor wafer 1, similar to the second embodiment,
In the images captured by the high-speed image sensor 19 and the camera 23, the difference in luminance between the portion where the stacking fault 2 exists and the portion where the stacking fault 2 does not exist becomes clearer due to the light interference effect. As a result, the detection sensitivity for the stacking fault 2 is further improved, and the inspection accuracy is further improved.

<Embodiment 4> FIG. 7 shows Embodiment 4 of the present invention.
It is a block diagram which shows the structure of the inspection apparatus which implement | achieves the inspection method of 5 automatically, efficiently, and with high precision. The inspection apparatus 102 includes a stage 61 similarly to the apparatus 101, and the semiconductor wafer 50 to be inspected is placed on the stage 61. A laser irradiation unit 63 is provided diagonally above the stage 61. The laser light generated by the laser irradiation unit is incident on the surface of the semiconductor wafer 50 placed on the stage 61 as incident light 64. Incident from the direction.

The incident light 64 forms a light spot 65 on the surface of the semiconductor wafer 50 and then is scattered in an oblique direction to form a reflected light 66. A scattered light detection unit 70 that detects laser light is attached to a spatial position deviating from the path of the reflected light 66, for example, a position above the light spot 65. The scattered light detection unit 70 includes, for example, a photomultiplier tube, and detects the scattered light 67 instead of the reflected light 66.

The stage 61 is the stage 1 of the apparatus 101.
Similarly to 0, translation along two horizontal directions X and Y, rotation along a rotation direction θ about a vertical axis, and translation along a vertical direction Z are possible. The movement of the stage 61 along these directions is controlled by the control unit 62. The control unit 62 gradually moves the stage 61 in the Y direction while repeatedly reciprocating the stage 61 in the X direction, for example, so that the light spot 65 is
0 allows scanning over the entire surface.

In the course of this scanning, the result of detection by the scattered light detector 70 is sequentially stored in the image memory 71 as a detection signal. The image processor 72 determines the stacking fault 2 based on the detection signal stored in the image memory 71.
Is detected. Information related to the position of the detected stacking fault 2 is output to the display screen 73 and the list output unit 74 connected to the image processor 72.

The device 102 is the light source 1 of the device 101.
By further providing an optical system from 1 to the camera 23 or the high-speed image sensor 19, the site where the stacking fault 2 is detected is optically enlarged and projected on the display screen 73 in the same manner as in the device 101, and is visually observed. Can also be used. Searching for and projecting a portion where the stacking fault 2 is detected can be automatically performed by the image processor 72.

FIG. 8 shows a semiconductor wafer 5 to be inspected.
FIG. 4 is a cross-sectional view illustrating an example of a structure of No. 0. This semiconductor wafer 50 is a so-called SOI (semiconductor-on-insulato).
r) It is configured as a structured wafer. That is, a semiconductor layer 51 such as silicon is formed on a semiconductor substrate 53 such as silicon via an insulating layer 52 such as a silicon oxide film.
Are formed. Stacking fault 2 appears in semiconductor layer 51. The devices 101 and 102 can inspect not only semiconductor wafers having a bulk structure but also semiconductor wafers having an SOI structure as shown in FIG.

FIG. 9 is an explanatory diagram showing an operation in which the scattered light detector 70 detects the scattered light 67. FIG. 9 shows an example in which the semiconductor wafer 50 has an SOI structure, but the same applies to a semiconductor wafer having a bulk structure. When a laser beam is incident on the surface of the semiconductor wafer 50, that is, the surface of the semiconductor layer 51 as an incident light 64 from an oblique direction, if there is no stacking fault 2 at the light spot 65, the laser light is reflected as reflected light 66. At this time, the scattered light 67 hardly appears.

On the other hand, if the stacking fault 2 exists at the position of the light spot 65, the incident light 64 is scattered by the stacking fault 2 and a scattered light 67 is generated. The scattered light 67 is detected by the scattered light detector 70. That is, the scattered light detector 7
0 detects the stacking fault 2 existing at the position of the light spot 65 through the scattered light 67.

By scanning the light spot 65 along the surface of the semiconductor wafer 50, it becomes possible to inspect the stacking faults 2 over the entire surface of the semiconductor wafer 50. FIG.
0 is an operation explanatory diagram showing a scanning procedure. In this example, scanning of the light spot 65 is performed with the X direction as the main scanning direction and the Y direction as the sub scanning direction. Light spot 6
The diameter of 5 is, for example, about 1 μm. The interval between the scanning lines 68 is set to be substantially equal to the diameter of the light spot 65.

The detection signals obtained by the scattered light detection section 70 are sequentially stored in the image memory 71 at intervals of about the diameter of the light spot 65 along the scanning line 68. FIG.
At 0, rectangular small areas arranged in a matrix in the X and Y directions are drawn. The detection signal of the scattered light detection unit 70 is stored in the image memory 71 together with the position of the light spot 65 for each of the small areas.

In the example of FIG. 10, the small areas 71, 72, 73
In such a small white area, the stacking fault 2 does not exist, and the scattered light 67 is not detected. On the other hand, the stacking faults 2 are present in the hatched small areas 74, 75, and 76, and scattered light 67 is detected in these small areas. Thus, the diameter of the light spot 65 is, for example, 1
If it is μm, the presence / absence of the scattered light 67, that is, the presence / absence of the stacking fault 2 is detected with a positional accuracy of about 1 μm.

The image processor 72 includes the image memory 7
1 is read, and the position where the scattered light 67 is detected is output to the display screen 73 or the list output unit 74. The operator can output the image,
Alternatively, the position where the stacking fault 2 exists can be recognized based on the list. The inspected semiconductor wafers 50 can be sorted and shipped only for non-defective products that do not include the stacking fault 2, or for all semiconductor wafers 50 irrespective of whether they are non-defective or defective products, It is also possible to ship with.

Since the resolution of the device 102 can be increased to about 1 μm, the use of the device 102 makes it possible to detect a stacking fault 2 having a size of about several μm. That is, by using the apparatus 102, the inspection accuracy can be increased as compared with the conventional method. In addition, the inspection can be performed nondestructively without damaging the semiconductor wafer 50, the use of a chemical solution containing heavy metals is unnecessary, so that the inspection can be performed inline, and all operations are performed manually. As in the case of the method using the device 101, the automatic operation can be performed without the use of the device 101.

If there is a possibility that the semiconductor wafer 50 has an abnormality other than the stacking fault 2, for example, a defect of another form, a surface scratch, a foreign substance, etc., and it is necessary to detect these abnormalities, Alternatively, even when it is necessary to discriminate these abnormalities from the stacking fault 2, the method using the device 102 can easily cope with it. These abnormalities other than the stacking fault 2 can be detected as long as the scattered light 67 is generated.

When the surface of the semiconductor layer 51 is oriented in the {100} direction, the image of the stacking fault 2 has two <1
It is projected as a linear area extending along any of the 10> directions. Therefore, the scattered light 67 obtained by reading the detection signal stored in the image memory 71 is obtained.
From the set of detected positions, a stacking fault 2 is identified as one that has a linearly extending pattern shape in one of two <110> directions orthogonal to the surface. It is possible to identify.

This process can be easily executed by the image processor 72. Further, it is also possible to selectively detect only the stacking fault 2 among various abnormalities. In particular, when the direction of the scanning line 68 coincides with any one of the two <110> directions, the stacking faults 2 extend in a direction parallel or perpendicular to the scanning line 68 as illustrated in FIG. The advantage is that the sorting of the stacking faults 2 is easier.

The position of the stacking fault 2 or the like is
Is stored in the image memory 71 as a detection signal, and after the scanning of the light spot 65 is completed, based on the stored data, for example, at a position where the stacking fault 2 is found,
In FIG. 7, the position of a light spot of an optical system (not shown) is aligned, and an image of the cell picked up by a camera or high-speed image sensor 19 is displayed on a display screen 24. Whether or not it is possible can be further confirmed. That is, the accuracy of sorting the stacking faults 2 can be further increased visually.

<Embodiment 5> Apparatus 102 shown in FIG.
Is similar to the fifth embodiment described in the fifth embodiment.
Inspection method is also realized automatically and with high accuracy. FIG.
Is a semiconductor wafer 50 suitable for the inspection method of the fifth embodiment.
FIG. 4 is a cross-sectional view showing an example of the structure of FIG. This semiconductor wafer 5
0 is characterized in that it has an SOI structure as shown in FIG. 8 and that the surface of the semiconductor layer 51 is oriented in the {100} direction.

FIG. 12 shows the semiconductor layer 51 illustrated in FIG.
3 is an enlarged perspective view of the vicinity of the stacking fault 2 in FIG. FIG.
As shown in the figure, the stacking fault 2 formed on the surface of the semiconductor layer 51 is in one direction along the surface of the semiconductor layer 51 <110.
Is formed in a planar shape as a defective surface along the line> and from the surface to the deep part. Moreover, the orientation of the defect plane of the stacking fault 2 also has an orientation in a certain direction related to the crystal axis.

Therefore, as shown in FIG. 12, in the direction of the incident light 64, the strongest scattered light 67 is generated.
There are most desirable directions. The specific direction (specific incident direction) is defined by the angle θ1 with respect to the surface of the semiconductor layer 51 and the azimuth φ1 with respect to the extending direction of the stacking fault 2 (one of the <110> directions). The incident light 64 is (θ
When incident in the specific incident direction defined by (1, φ1), the scattered light 67 is emitted most strongly in another specific direction (specific scattering direction). This specific scattering direction is similarly defined by the angle θ2 with respect to the surface of the semiconductor layer 51 and the azimuth φ2 with respect to the extending direction of the stacking fault 2 (one of the <110> directions).

The inspection method according to the fifth embodiment uses the incident light 64 and the scattered light 6 related to the intensity of the scattered light 67 as described above.
7 is used. That is, as shown in the operation explanatory diagram of FIG. 13, when scanning the light spot 65 over the entire surface of the semiconductor layer 51, the incident light 64 in the (θ1, φ1) direction with one of the <110> directions as a reference. Set the direction of.

At this time, the scattered light detector 70 calculates (θ2, φ
2) Installed at a position where scattered light 67 in the direction can be detected. Thus, scanning along the scanning line 78 in a certain direction is performed. The direction of the scanning line 78 does not necessarily have to match one of the <110> directions. Through this scanning, the stacking fault 2 extending along one of the <110> directions, for example, the defect 2a
Is detected with high detection sensitivity.

Next, the semiconductor wafer 50 is moved around the vertical axis, in other words, along the surface of the semiconductor wafer 50.
After a 90 ° rotation, a similar scan is performed. As a result, a stacking fault 2 extending along another one in the <110> direction, for example, the fault 2b, is detected with high detection sensitivity. This scanning is performed, for example, along a scanning line 79 orthogonal to the scanning line 78.

As described above, in the method of this embodiment, scanning is performed twice, but there is an advantage that the stacking faults 2 along two <110> can be detected with high sensitivity without fail. . Selection of the stacking fault 2 by the image processor 72, display and output of data relating to the position of the stacking fault 2, confirmation by an optical microscope, and the like can be performed in the same manner as in the fourth embodiment.

[0072]

According to the first aspect of the present invention, the surface of the semiconductor wafer is irradiated with light, an image thereof is taken, and a stacking fault is detected based on the taken image. The inspection can be performed nondestructively without adding. Therefore, since there is no need to use a chemical solution containing heavy metals, efficient in-line inspection can be performed. Further, the inspection accuracy is higher than that of the related art, and it is possible to detect a stacking fault having a size of about 0.5 μm.

According to the method of the second invention, it is possible to selectively detect only stacking faults.

In the method of the third invention, a semiconductor oxide film having a thickness of 200 Å or more is formed in advance on the surface of a semiconductor wafer to be inspected. For this reason, the detection sensitivity for stacking faults is further improved by the light interference effect, and the inspection accuracy is further improved. Moreover, there is an advantage that a long time is not required to form the semiconductor oxide film.

In the method according to the fourth invention, a semiconductor nitride film having a thickness of 200 Å or more is formed in advance on the surface of a semiconductor wafer to be inspected. For this reason, the detection sensitivity for stacking faults is further improved by the light interference effect, and the inspection accuracy is further improved.

In the method of the fifth invention, the surface of the semiconductor wafer is irradiated with laser light, the scattered light is detected, and a stacking fault is detected based on the detection result. Inspection can be performed nondestructively. Therefore, since there is no need to use a chemical solution containing heavy metals, efficient in-line inspection can be performed. Furthermore, the inspection accuracy is higher than the conventional technology,
It is possible to detect stacking faults having a size of about several μm.

According to the method of the sixth invention, it is possible to selectively detect only stacking faults.

In the method according to the seventh aspect of the invention, laser light is incident from two specific incident directions rotated by 90 degrees, and scattered light in a specific scattering direction with respect to each of the laser light is detected. For this reason,
The effect is obtained that stacking faults along two <110> directions can be detected with high sensitivity without fail.

In the method according to the eighth aspect, the scanning direction of the light spot is two orthogonal to the surface of the single crystal semiconductor layer.
Since it is set in one of the <110> directions, sorting of stacking faults can be easily performed.

The semiconductor wafer of the ninth invention is obtained as a semiconductor wafer that has been confirmed to be highly accurate, non-destructive, and free from stacking faults through the inspection method according to any one of the first to eighth inventions. Since the semiconductor wafer is non-destructive, the semiconductor wafer subjected to the inspection can be used for manufacturing a semiconductor element.

The semiconductor wafer according to the tenth aspect of the present invention can be obtained as a semiconductor wafer having a highly accurate, non-destructive, abnormal position clarified through the inspection method according to any one of the first to eighth aspects. By selecting only the elements included in the region where no abnormality exists after the semiconductor elements are manufactured, it is possible to ship only non-defective semiconductor elements.

[Brief description of the drawings]

FIG. 1 is a block diagram of an apparatus suitable for the methods of Embodiments 1 to 3.

FIG. 2 is an explanatory diagram of a method according to the first embodiment.

FIG. 3 is an explanatory diagram of a method according to the first embodiment.

FIG. 4 is an explanatory diagram of a method according to the first embodiment.

FIG. 5 is a process chart of a method according to a second embodiment.

FIG. 6 is a process chart of a method according to a third embodiment.

FIG. 7 is a block diagram of an apparatus suitable for the methods of Embodiments 4 and 5.

FIG. 8 is a sectional view showing an example of the structure of a semiconductor wafer.

FIG. 9 is an explanatory diagram of a method according to a fourth embodiment.

FIG. 10 is an explanatory diagram of a method according to a fourth embodiment.

FIG. 11 is a sectional view of a semiconductor wafer used in the method according to the fifth embodiment.

FIG. 12 is an explanatory diagram of a method according to a fifth embodiment.

FIG. 13 is an explanatory diagram of a method according to the fifth embodiment.

FIG. 14 is a process chart of a conventional method.

[Explanation of symbols]

1, 50 semiconductor wafer, 2 stacking fault, 4 oxide film (semiconductor oxide film), 5 nitride film (semiconductor nitride film), 40
Scanning lines, 41, 65 light spots, 42, 43, 45
cell.

Claims (10)

[Claims] 1. A stacking fault inspection method for checking stacking faults present on a surface of a semiconductor wafer, wherein the step of conceptually dividing the surface into a plurality of cells arranged on the surface; A scanning step of sequentially irradiating the plurality of cells one by one by scanning a light spot capable of irradiating at least one of the plurality of cells one by one, and irradiating with the light spot in accordance with the scanning step An imaging step of sequentially imaging the plurality of cells one by one, a storage step of storing an image captured in the imaging step, and an image stored in the storage step being different from the plurality of cells in the plurality of cells. An abnormality detection step of comparing the two to find an inconsistency, thereby detecting an abnormality including the stacking fault present on the surface. 2. The stacking fault inspection method according to claim 1, wherein in the abnormality detecting step, a shape of the mismatched portion in the image is within a preset range of a shape unique to the stacking fault. A stacking fault inspection method comprising a step of selectively detecting only the stacking fault by determining whether or not the stacking fault is present. 3. The stacking fault inspection method according to claim 1, wherein prior to the scanning step, the semiconductor wafer is subjected to dry oxidation in an oxygen atmosphere at a temperature of 1000 ° C. or less. And forming a semiconductor oxide film having a thickness of 200 Å or more on the surface by performing the following. 4. The stacking fault inspection method according to claim 1, wherein prior to the scanning step, the semiconductor wafer is annealed in an ammonia gas atmosphere at a temperature of 1000 ° C. or less. Is performed, the film thickness 2
A stacking fault inspection method, further comprising a step of forming a semiconductor nitride film having a thickness of 00 Å or more. 5. A stacking fault inspection method for checking stacking faults present on a surface of a semiconductor wafer, wherein a light spot formed by irradiating the surface with laser light from an oblique direction is scanned along the surface. A scanning step of causing the scanning step; a scattered light detection step of detecting the scattered light of the laser light in the scanning step; a storage step of storing a detection result in the scattered light detection step; and a detection stored in the storage step. An abnormality detection step of detecting an abnormality including the stacking fault present on the surface based on the result. 6. The stacking fault inspection method according to claim 5, wherein in the abnormality detecting step, a pattern shape of a portion of the surface where the scattered light is detected is set in advance based on the detection result. A stacking fault inspection method comprising a step of selectively detecting only the stacking fault by determining whether the stacking fault is within a range of a shape unique to the stacking fault. 7. The stacking fault inspection method according to claim 5, wherein the semiconductor layer present on at least the surface of the semiconductor wafer is a single-crystal semiconductor layer having a plane orientation of {100}. For a stacking fault extending along one of two <110> directions orthogonal to each other along the surface of the semiconductor layer, the incident direction of the laser light at which the intensity of the scattered light is the highest is defined as a specific incident direction. The scattering direction having the highest scattering intensity is defined as the specific scattering direction, and the scanning step includes a first scanning step and a second scanning step performed thereafter, and the scattered light detection step includes the first scattered light detection. And a second scattered light detection step performed thereafter. In the first scanning step, the laser light is applied to the surface from the specific incident direction, and the formed light spot is applied to the surface. Scanning along the first In the scattered light detecting step, scattered light in the specific scattering direction is detected in the first scanning step, and in the second scanning step, a direction rotated by 90 degrees along the surface with respect to the specific incident direction. Irradiating the surface with the laser light from the above, the formed light spot is scanned along the surface, In the second scattered light detection step, in the second scanning step, with respect to the specific scattering direction A stacking fault inspection method for detecting scattered light in a direction rotated by 90 degrees along the surface. 8. The stacking fault inspection method according to claim 2, wherein the semiconductor layer present on at least the surface of the semiconductor wafer is a single-crystal semiconductor layer having a plane orientation of {100}. In the scanning direction of the light spot,
Two <110 perpendicular to the surface of the single crystal semiconductor layer
> Stacking fault inspection method set in one of the directions. 9. By being inspected using the stacking fault inspection method according to any one of claims 1 to 8,
A semiconductor wafer selected as having no stacking fault. 10. A semiconductor wafer having an abnormal position clarified by being inspected using the stacking fault inspection method according to any one of claims 1 to 8.