JP2013083491A - Surface inspection system for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of more accurately detecting a saw mark or measuring the size of the saw mark on a surface of a semiconductor wafer with smaller or simpler configuration.SOLUTION: A surface inspection system for a semiconductor wafer irradiates a surface of a semiconductor wafer W in an oblique direction with light which is parallel light on an incident plane, images a linear region 3a on the surface of the semiconductor wafer W with line sensor cameras 3 and 4, thereby detects reflected light or scattered light of the irradiation light from the surface of the semiconductor wafer W, and detects a linear convexoconcave or measures the size of the linear convexoconcave on the surface of the semiconductor wafer W on the basis of intensity of the reflected light or scattered light. The system detects the linear convexoconcave or measuring the size of the linear convexoconcave of the semiconductor wafer W, by irradiating, with light source devices 1 and 2, the linear region 3a to be imaged by the line sensor cameras 3 and 4 in a direction parallel to the line, with a direction of the linear convexoconcave arranged so as to be orthogonal to a direction of the line.

Description

  The present invention irradiates the surface of a semiconductor wafer with light and detects reflected light or scattered light from the surface of the semiconductor wafer, thereby detecting linear unevenness on the surface of the semiconductor wafer or the size of the unevenness. The present invention relates to a semiconductor wafer surface inspection system for measuring the thickness.

  2. Description of the Related Art Conventionally, semiconductor wafers for manufacturing semiconductor elements and solar cells are often manufactured by slicing an ingot with a wire saw after the ingot is generated. Processing traces such as a wire saw when slicing the ingot into a semiconductor wafer remain as linear irregularities on the surface of the semiconductor wafer. It is known that such a large degree of unevenness on the surface causes inconveniences such as a reduction in conversion efficiency of light energy to electric energy and a shortened life in the case of a solar cell. Therefore, in the manufacturing process of a semiconductor wafer, it is necessary to inspect for linear irregularities (hereinafter also referred to as saw marks) on the surface of the semiconductor wafer, and to remove semiconductor wafers whose irregularities exceed an allowable range. .

  As a method for measuring the linear unevenness on the surface of the semiconductor wafer, an area sensor camera or a line sensor camera that irradiates the surface of the semiconductor wafer obliquely from above with a light source device and reflects or scattered light from the linear unevenness It is possible to shoot with In this method, the light source device has a direction in which a concave portion or a convex portion in which the linear irregularity is formed extends so that incident light is scattered in the linear irregularity (the direction of the line in the linear irregularity. It was also arranged to irradiate the semiconductor wafer from a direction orthogonal to “the direction of linear unevenness”.

  And the length of the light emission part which light-emits light directly in a light source device needed to be about 2 to 3 times the length of the area | region which should be image | photographed on the surface of a semiconductor wafer. Otherwise, when the surface of the semiconductor wafer is photographed with an area sensor camera or a line sensor camera, the irradiation light intensity in the photographing region becomes uneven or vignetting occurs at both ends of the photographing region. This is because there may occur. This has hindered the cost reduction of the light source device, and has been a factor preventing simplification of the entire system configuration and cost reduction.

  In addition, when using the above method in the manufacturing process of a semiconductor wafer, a region parallel to the direction of the linear irregularities is photographed while moving the semiconductor wafer in a direction perpendicular to the direction of the linear irregularities by a belt conveyor. In some cases, unevenness was measured by photographing the surface with a line sensor. In this method, the height of the linear unevenness on the surface of the semiconductor wafer is continuously measured based on the temporal change of the light reception signal by each sensor element of the line sensor. However, in such a system, there is a case where jitter, which is a speed unevenness of the belt conveyor, affects the measurement result.

  In addition, when the above method is used in the manufacturing process of the semiconductor wafer, the light source devices arranged on the upper and lower sides of the semiconductor wafer are irradiated with light on the upper and lower sides of the semiconductor wafer and are arranged on the upper and lower sides of the semiconductor wafer. A system that measures the unevenness of both sides at once with a line sensor is also known. In such a system, the light source device that measures the lower surface of the semiconductor wafer in particular needs to irradiate the semiconductor wafer with light in the space between the belt conveyors, so that a wide space between the belt conveyors is ensured. There is a need to reduce the movement stability of the semiconductor wafer during measurement, which may cause vibration. In addition, it is physically difficult to make the irradiation light from the light source device incident obliquely directly on the lower surface of the semiconductor wafer in the space between the belt conveyors. It was necessary to refract. This has hindered miniaturization and simplification of the system.

JP 2002-365234 A JP 2002-340811 A JP 2002-340537 A

  The present invention has been devised in view of the above-mentioned problems, and the object of the present invention is to detect linear irregularities existing on the surface of a semiconductor wafer with a smaller size or a simpler configuration and with higher accuracy. Or providing a technique capable of measuring the size thereof.

In the present invention, the surface of the semiconductor wafer is irradiated with light that is parallel light at least on the incident surface from an oblique direction, and a line-shaped region on the surface of the semiconductor wafer is imaged with an imaging device, so that from the surface of the semiconductor wafer. The reflected light or scattered light of the irradiation light is detected, and linear irregularities on the surface of the semiconductor wafer are detected or the size thereof is measured based on the intensity.
And the light source device irradiates light from a direction parallel to the line of the line-shaped region photographed by the photographing device,
In the semiconductor wafer, the linear unevenness is detected or the size of the linear unevenness is determined in a state where the direction of the line in the linear unevenness is perpendicular to the direction of the line. The greatest feature is being measured.

More specifically, it is a semiconductor wafer surface inspection system that detects linear irregularities on the surface of a semiconductor wafer or measures the size of the linear irregularities,
A light source device that irradiates light that is parallel light on the incident surface from a direction oblique to the surface of the semiconductor wafer;
A photographing device for photographing a line photographing region that is a line-shaped region on the surface of the semiconductor wafer,
The light source device is arranged to irradiate light from a direction parallel to the line with respect to a line photographing region photographed by the photographing device,
In the state where the semiconductor wafer is arranged so that the uneven direction which is a direction parallel to the line in the linear unevenness is perpendicular to the direction of the line, the linear unevenness is detected, or the line The size of the concavo-convex shape is measured.

  That is, in the present invention, the light source device irradiates light from a direction parallel to the line direction of the line photographing region photographed by the photographing device. In addition, the linear unevenness is detected or the size of the linear unevenness is measured in a state where the uneven direction, which is the direction of the line in the linear unevenness, is orthogonal to the line direction of the line imaging region. (Hereafter, it is also simply referred to as “linear irregularities are measured”). According to this, since the light source device may irradiate light in a range that covers the line imaging region from a direction parallel to the line direction of the line imaging region, the light emitting unit that is a portion that emits light in the light source device The width of can be made smaller.

  In the present invention, since the semiconductor wafer is in a state where the uneven direction is perpendicular to the direction of the line in the line imaging region at the time of measurement, reflected light or scattered light from the surface of the semiconductor wafer in the line imaging region The linear unevenness can be measured with higher accuracy than the spatial intensity distribution.

In the present invention, the apparatus further includes a transport device that supports the semiconductor wafer and moves the wafer to pass through the line imaging region,
The transport device moves the supported semiconductor wafer in the uneven direction so that the supported semiconductor wafer passes through the line imaging region in a state where the uneven direction and the line direction are orthogonal to each other. Also good.

  That is, a semiconductor wafer is mounted on the transport device in a direction that moves in the uneven direction, and the transport device is configured so that the uneven direction and the direction of the line in the line imaging region are orthogonal to each other. Then, the line imaging region is passed through the semiconductor wafer. According to this, an imaging device will image | photograph when the linear unevenness | corrugation extended in the direction orthogonal to a line imaging | photography area | region moves to an uneven | corrugated direction.

  Here, in the conventional system, the line direction of the line imaging region and the uneven direction are parallel, and the transport device moves the semiconductor wafer in a direction orthogonal to the uneven direction. Therefore, in the conventional system, as the transport device moves, the imaging device detects reflected light or scattered light whose intensity periodically changes with time. Linear irregularities were measured from the periodic change of the intensity of the reflected light or scattered light or its integrated value.

  On the other hand, in the present invention, when measuring the linear unevenness, the reflected light or scattered light from the line photographing area photographed by the photographing device is not time-dependent as in the conventional system. Do not make periodic changes. Instead, the intensity change of the reflected light or scattered light due to the linear unevenness appears as a spatial change on the line of the light intensity imaged in the line imaging region. That is, in the present invention, linear unevenness is measured based on the periodic change of the intensity of the reflected light or scattered light from the surface of the semiconductor wafer or the integrated value thereof. Therefore, in the present invention, even if jitter occurs in the movement of the transporting device, it does not affect the measurement accuracy of linear unevenness measurement.

Further, in the present invention, the transport device includes a plurality of belt conveyors arranged in parallel with a predetermined interval in the moving direction of the semiconductor wafer,
The light source device includes a light source device for lower surface that irradiates light from a lower side of the semiconductor wafer to a lower surface of the semiconductor wafer,
The lower surface light source device may be arranged to irradiate light on a lower surface of the semiconductor wafer in a space between the belt conveyor and the belt conveyor.

  2. Description of the Related Art Conventionally, there has been known a system that includes a light source device and a photographing device on the lower side of a semiconductor wafer and measures linear irregularities on the lower surface of the semiconductor wafer. In such a system, the light source device irradiates light to the line imaging region from a direction parallel to the moving direction of the semiconductor wafer by the transport device when viewed from the lower side. It was necessary to be longer than the line length (about 3 times).

  Therefore, in the conventional system, a certain amount of space is provided between the belt conveyor and the belt conveyor in the transport device, and in this space, it is necessary to measure the linear unevenness on the lower surface of the semiconductor wafer. . More specifically, it is necessary to arrange the light source device and the photographing device in a space between the belt conveyor and the belt conveyor. As a result, downsizing of the entire system is hindered, and the space between the belt conveyor and the belt conveyor needs to be increased, which may make it difficult to move the semiconductor wafer smoothly.

On the other hand, in the present invention, the light source device is arranged to irradiate light from a direction parallel to the line with respect to the line photographing region, and the transport device is such that the semiconductor wafer is perpendicular to the uneven direction and the line direction. In such a state, the semiconductor wafer is moved in the concavo-convex direction so as to pass through the line imaging region, and as a result, the light source device emits light from the side with respect to the moving direction of the semiconductor wafer. According to this, it is possible to arrange the light source device on the side surface of the space between the belt conveyor and the belt conveyor, and as a result, the space between the belt conveyor and the belt conveyor can be reduced. Can be transported stably. Further, it is not necessary to arrange a mirror in the space between the belt conveyor and the simplification of the structure of the entire system and cost reduction can be promoted.

  In the present invention, the light source device further includes an upper surface light source device that irradiates an upper surface of the semiconductor wafer from an upper side of the semiconductor wafer, and the upper surface light source device and the lower surface light source device are integrated. You may make it comprise. According to this, it becomes possible to simplify the structure of the whole system.

In the present invention, the light source device includes a light emitting unit configured in a line segment having a length equal to or longer than the width of the region to be photographed in the semiconductor wafer,
Furthermore, two reflecting mirrors having a reflecting surface perpendicular to the light emitting unit at both ends or inside of the light emitting unit are provided to face each other, and in the optical path between the light emitting unit and the semiconductor wafer, the irradiation light in the optical path Are reflected from each other on the opposite reflecting mirror side.

More specifically, a light source device that irradiates light that is parallel light on the incident surface from an oblique direction with respect to the surface of the semiconductor wafer;
An imaging device for imaging the surface of the semiconductor wafer,
Detecting irregularities on the surface of the semiconductor wafer based on the intensity of scattered light or reflected light of the light emitted from the light source device obtained by photographing the surface of the semiconductor wafer with the imaging device, or A semiconductor wafer surface inspection system for measuring the size of irregularities,
The light source device is
A light emitting section configured in a line shape having a length equal to or greater than the width of the area to be imaged in the semiconductor wafer and including the area to be imaged in the length direction;
Two flat plate reflecting mirrors provided on a plane orthogonal to the line segment at both ends or both ends of the light emitting section and having reflecting surfaces facing each other in an optical path between the light emitting section and the semiconductor wafer;
It is characterized by having.

  Here, as described above, the length of the light emitting unit of the light source device needs to be about three times the width of the region to be photographed of the semiconductor wafer. This is because when the light emitting portion is shorter than this length, the intensity of the irradiated light in the region to be photographed may be non-uniform or vignetting may occur in the region to be photographed. However, it may be difficult to make the length of the light emitting unit of the light source device about three times the width of the region to be imaged of the semiconductor wafer in terms of the size and cost of the device. According to the present invention, due to the two reflecting mirrors, the width of the light emitting portion apparently becomes about three times the area to be photographed from the semiconductor wafer. Therefore, in practice, even if the width of the light emitting portion is not much different from the width of the region to be photographed, it is possible to suppress unevenness and vignetting of the irradiation light intensity.

  In the present invention, the flat reflector is provided such that the reflecting surface is disposed between an end portion of the light emitting portion and an end surface on the end portion side of the region to be photographed. Also good. For example, when the length of the light emitting part is longer by d on both sides than the width of the area to be photographed, the reflecting surface of the flat reflector is arranged in the range of the width d. . By doing so, there is no gap between the actual light emitting part and the real image of the light emitting part reflected on the flat reflector, and an apparently continuous light emitting part can be formed.

  In this case, the end on the light emitting unit side of the flat plate reflecting mirror is a central end point of vignetting that occurs when there is no flat plate reflecting mirror on the light emitting unit side end surface of the area to be photographed, and the end of the light emitting unit. It is better to be on the light emitting part side than the straight line connecting This makes it possible to form an apparently continuous light emitting portion more reliably.

  Further, in the present invention, the flat reflector has an end on the side opposite to the light emitting part of the flat reflector with respect to the light emitting part rather than an end face on the light emitting part side of the region to be photographed. It may be provided so as to be arranged on the far side. Thereby, it is possible to suppress the occurrence of vignetting in a portion on the side opposite to the light emitting portion in the region to be photographed.

  In this case, the end of the flat reflector opposite to the light emitting portion is the point farthest from the flat reflector in the light emitting portion, the point of line symmetry with respect to the reflecting surface, and the end face of the semiconductor wafer opposite to the light emitting portion. It is good to arrange | position on the side far from a light emission part from the straight line which connected the point by the side of a flat reflector. Accordingly, vignetting can be more reliably suppressed with respect to the entire region to be photographed (even for the portion on the opposite side of the light emitting portion).

Further, the present invention provides a light source device that irradiates light that is parallel light on the incident surface from an oblique direction with respect to the surface of the semiconductor wafer;
An imaging device for imaging the surface of the semiconductor wafer,
Based on the intensity of the scattered light or reflected light of the light emitted from the light source device obtained by photographing the surface of the semiconductor wafer with the photographing device, linear unevenness on the surface of the semiconductor wafer is detected. Or a semiconductor wafer surface inspection system for measuring the size of the linear irregularities,
The light source device is
The semiconductor wafer surface inspection system irradiates the light from the center of curvature of the line of the line-shaped unevenness when the line of the line-shaped unevenness on the surface of the semiconductor wafer is curved. May be.
Alternatively, from the oblique direction with respect to the surface of the semiconductor wafer, irradiate light that is parallel light on the incident surface,
Photographing the surface of the semiconductor wafer;
Based on the intensity of the scattered light or reflected light from the surface of the semiconductor wafer of the irradiated light obtained by photographing the surface of the semiconductor wafer, linear irregularities on the surface of the semiconductor wafer are detected, Or a method for inspecting the surface of a semiconductor wafer for measuring the size of the linear irregularities,
A method for inspecting a surface of a semiconductor wafer, comprising: irradiating the light from the center of curvature of the line of the line-shaped unevenness when a line in the line-shaped unevenness on the surface of the semiconductor wafer is curved. May be.

  Here, as described above, in the conventional system, the length of the light emitting unit of the light source device is required to be about three times the width of the region to be imaged of the semiconductor wafer, and the light emitting unit has this length. If it is shorter than this, the irradiation light intensity in the area to be photographed may be non-uniform or vignetting may occur in the area to be photographed. In this regard, when the linear irregularities on the surface of the semiconductor wafer are not linear but are bent (bent) (for example, in the case of a bow), the curvature center side (bending is negative). It has been empirically known that vignetting is less when irradiated from the direction or inside the bow.

Accordingly, in the present invention, when the line in the linear unevenness on the surface of the semiconductor wafer is accompanied by bending (bending), from the curvature center side (direction in which the bending becomes negative) of the line of the linear unevenness, The light was irradiated. According to this, even when the length of the light emitting part is not sufficiently long, it is possible to reduce the influence of vignetting as much as possible. In the above description, the center of curvature of the concavo-convex line indicates a direction in which the undulation of the concavo-convex line is negative, or a direction in which the bent line appears to be concave, or inside the bow in the concavo-convex form.

Further, the present invention provides a light source device that irradiates light that is parallel light on the incident surface from an oblique direction with respect to the surface of the semiconductor wafer;
An imaging device for imaging the surface of the semiconductor wafer,
Based on the intensity of the scattered light or reflected light of the light emitted from the light source device obtained by photographing the surface of the semiconductor wafer with the photographing device, linear unevenness on the surface of the semiconductor wafer is detected. Or a semiconductor wafer surface inspection system for measuring the size of the linear irregularities,
The light source device is
A surface inspection system for a semiconductor wafer that irradiates the light from the opposite side of the center of curvature of the line of the line-shaped unevenness when a line in the line-shaped unevenness on the surface of the semiconductor wafer is curved. It may be.
Alternatively, from the oblique direction with respect to the surface of the semiconductor wafer, irradiate light that is parallel light on the incident surface,
Photographing the surface of the semiconductor wafer;
Based on the intensity of the scattered light or reflected light from the surface of the semiconductor wafer of the irradiated light obtained by photographing the surface of the semiconductor wafer, linear irregularities on the surface of the semiconductor wafer are detected, Or a method for inspecting the surface of a semiconductor wafer for measuring the size of the linear irregularities,
A method for inspecting a surface of a semiconductor wafer, comprising: irradiating the light from a side opposite to a center of curvature of the line of the line-shaped unevenness when a line in the line-shaped unevenness on the surface of the semiconductor wafer is curved. It may be.

  That is, in the case where the linear irregularities are not linear but accompanied by a bend, for example, when there is a demand for particularly measuring a part of the linear irregularities, the linear curvature is opposite to the center of curvature. Light may be irradiated from the side. Then, it is possible to obtain information limited to a partial region of the linear unevenness (for example, a region where the linear unevenness is more perpendicular to the incident direction of light) by a simple method. .

Further, the present invention is a semiconductor wafer surface inspection system for detecting unevenness on the surface of a semiconductor wafer or measuring the size of the unevenness,
A light source device that irradiates light that is parallel light on the incident surface from an oblique direction with respect to the entire surface of the semiconductor wafer;
An imaging device for imaging the entire surface of the semiconductor wafer,
The unevenness is detected based on a two-dimensional intensity distribution of scattered light or reflected light of the light emitted from the light source device obtained by photographing the entire surface of the semiconductor wafer with the photographing device. Or a semiconductor wafer surface inspection system for measuring the size of the irregularities,
The semiconductor wafer surface inspection system may be characterized in that the semiconductor wafer is a solar cell wafer, and the unevenness is an unevenness caused by electrodes provided on the surface of the solar cell wafer.

  In this case, since the formation state of the electrode for taking out the electric power generated in the solar cell can be measured with high accuracy, the quality improvement of the solar cell can be promoted more easily or surely.

  The means for solving the above-described problems of the present invention can be used in combination as much as possible.

  In the present invention, linear irregularities existing on the surface of a semiconductor wafer can be detected or measured in size with a smaller or simpler configuration with higher accuracy.

It is a figure for demonstrating the phenomenon which arises when parallel light injects into a semiconductor wafer in Example 1 of this invention from a light source. It is a figure which shows schematic structure of the semiconductor wafer surface inspection system in Example 1 of this invention. It is a figure which shows the outline of the image of the surface of the semiconductor wafer image | photographed with the CCD camera in Example 1 of this invention. It is a figure which shows schematic structure of the light source device in Example 1 of this invention. It is a figure which shows schematic structure of the other example of the light source device in Example 1 of this invention. It is a figure for demonstrating comparatively the conventional light source device and the light source device which concerns on Example 1 of this invention. It is a figure for demonstrating arrangement | positioning of the light irradiation part, semiconductor wafer, and mirror in Example 1 of this invention. It is a graph which shows the change of the required length of a mirror by the position of the mirror in Example 1 of this invention. It is a figure which shows the effect of the mirror in Example 1 of this invention. It is a figure which shows the relationship between the incident direction of light with respect to the curve of the linear unevenness | corrugation in Example 2 of this invention, and vignetting. It is a figure for demonstrating the conventional in-line type semiconductor surface inspection system. It is a figure for demonstrating the semiconductor surface inspection system which concerns on Example 3 of this invention. It is a figure for comparing and explaining the signal acquisition method of the conventional system and the semiconductor surface inspection system which concerns on Example 3 of this invention. It is a figure shown about the other example of the light source device which concerns on Example 3 of this invention.

  Hereinafter, a semiconductor wafer surface inspection system according to the present invention will be described in detail with reference to the drawings.

[Example 1]
First, a phenomenon that occurs when parallel light is obliquely incident on the surface of a semiconductor wafer from the light source will be described with reference to FIG. In FIG. 1, an average surface of a semiconductor wafer is an xz plane (z-axis is an axis perpendicular to the paper surface), and a minute surface inclined by an angle θ around the z-axis from the x-axis is irradiated with parallel light of intensity I _0. Think about the case. The incident direction of the irradiation light is inclined by an angle θ ₀ around the z axis with respect to the x axis. In FIG. 1, the incident surface of the irradiation light is an xy plane. Most of the irradiation light is specularly reflected on the surface of the semiconductor wafer, but actually, this minute surface is also composed of a finer rough surface, and diffuse reflection (irregular reflection or scattering) occurs on each rough surface. Assuming that this surface is a uniform diffusion surface, the intensity I of light traveling in the y-axis direction perpendicular to the surface of the semiconductor wafer is given by equation (1).

Here, _Kd is a constant representing the reflectance. According to the equation (1), it appears that the intensity obtained by multiplying the intensity on the plane inclined obliquely with respect to the light source by the reflectance becomes the observed intensity, but actually defines the properties of the uniform diffusion surface. It was obtained as a result of photometric considerations taking Lambert's cosine law into account. As described above, the scattered light or reflected light handled in the present invention is generated by the fine diffusion surface of the semiconductor wafer rather than by the sharp edges of the irregularities generated on the surface of the semiconductor wafer. It contains information that has a high correlation with the shape.

（２）式によれば、ｙ軸方向で得られた光の強度Ｉは半導体ウェハの表面の傾きθの関数となる。（２）式においてθの前の係数にＣＯＳθ_０が含まれており、この値が大きいほど表面の傾きに対する感度が大きいことを示している。従ってθ_０が小さくなるように、光源からの照射光は半導体ウェハの表面に平行に近い浅い角度で入射することが望ましい。 In general, the inclination angle θ due to surface roughness is considered to be sufficiently small. Therefore, when the above equation is modified under this condition, equation (2) is obtained.

According to the equation (2), the light intensity I obtained in the y-axis direction is a function of the inclination θ of the surface of the semiconductor wafer. In the equation (2), COSθ ₀ is included in the coefficient before θ, and the larger the value, the higher the sensitivity to the surface inclination. Therefore, it is desirable that the irradiation light from the light source is incident at a shallow angle close to parallel to the surface of the semiconductor wafer so that θ ₀ becomes small.

（３）式より、半導体ウェハの垂直上方に例えばＣＣＤからなるエリアセンサカメラまたはラインセンサカメラを設置して半導体ウェハの表面の画像を撮影した際に、その散乱光または反射光の強度分布は半導体ウェハの表面形状の傾きの分布を表していることが分かる。 Furthermore, the following equation (3) can be obtained by modifying the equation (2).

From equation (3), when an area sensor camera or line sensor camera made of, for example, a CCD is installed vertically above the semiconductor wafer and an image of the surface of the semiconductor wafer is taken, the intensity distribution of the scattered light or reflected light is the semiconductor It can be seen that this represents the distribution of the inclination of the surface shape of the wafer.

If the surface shape is y (x) and the intensity distribution is I (x), θ = dy / dx, and therefore the following equation (4) can be obtained.

（５）式において、右辺にはｔに比例する項が現れるが、表面粗さを記述するには、形状の変動分だけを求めればよいので、この項は直線的に変化する分として補正により取り除くことができる。また、この式の中にはいくつかの定数が含まれているが、これらの値は、表面粗さの判っている試験片をこの方法で測定して較正することにより求めることが可能である。 If this is integrated between x = 0 and x = t, the size of the surface of the semiconductor wafer at x = t can be obtained. Therefore, the following (5) can be obtained as an expression representing the size of the surface of the semiconductor wafer.

In Eq. (5), a term proportional to t appears on the right side, but in order to describe the surface roughness, it is only necessary to obtain the variation of the shape. Can be removed. In addition, some constants are included in this equation. These values can be obtained by measuring and calibrating a test piece having a known surface roughness by this method. .

  As is clear from the above, when an area sensor camera or line sensor camera is installed vertically above the semiconductor wafer and an image of the surface of the semiconductor wafer is taken according to equation (3), the reflected light from the surface of the semiconductor wafer Alternatively, the distribution of the inclination of the surface shape of the semiconductor wafer can be obtained from the intensity I (x) of the scattered light. Further, by integrating I (x) by the equation (5), the distribution of the size of the surface irregularities of the semiconductor wafer can be acquired.

  Next, a schematic configuration of the semiconductor wafer surface inspection system 50 in the present embodiment using the above principle will be described with reference to FIG. In the following, an example in which a so-called saw mark is measured as an example of surface irregularities of a semiconductor wafer will be described. The semiconductor wafer surface inspection system 50 includes a light source device 52 that irradiates light obliquely to the semiconductor wafer W to be evaluated. The light source device 52 uses an LED light source or the like capable of entering parallel light into the semiconductor wafer W at least on the incident surface. The wavelength of the LED light source is not particularly limited. In addition, an area sensor camera 54 as an imaging device provided with a CCD as a sensor is installed so that the semiconductor wafer W can be imaged from substantially vertically above. The area sensor camera 54 is electrically connected to an arithmetic unit 56 that transmits image data of the photographed semiconductor wafer W and derives the size of the irregularities of the saw marks, which are linear irregularities on the surface of the semiconductor wafer W. Yes. Further, a display unit 58 for displaying the inspection result by the arithmetic unit 56 is electrically connected to the arithmetic unit 56.

  In order to improve the measurement sensitivity in the semiconductor wafer surface inspection system 50, as described above, it is necessary to make incident light having a high parallelism and uniform illuminance incident on the surface of the semiconductor wafer W as shallow as possible. For this purpose, it is better to increase the distance between the light source device 52 and the semiconductor wafer W. Considering this and the size of the entire system, the semiconductor wafer surface inspection system 50 is configured to irradiate the semiconductor wafer W with the irradiation light from the light source device 52 using a mirror 53.

  At that time, the angle between the incident light and the surface of the semiconductor wafer W was 5 ° (incident angle was 85 °). In addition, the area sensor camera 54 that captures an image of the surface of the semiconductor wafer W preferably has a large number of pixels in order to ensure sufficient lateral resolution during image analysis. In this embodiment, the area sensor camera 54 has 960 × 960 pixels in the entire observation field. As for the camera lens 54a, it is necessary to put the entire semiconductor wafer W in the field of view, but in order to avoid distortion around the image, a lens having a focal length of 12 mm was used at the expense of a longer working distance. Image data captured by the area sensor camera 54 is transmitted to the arithmetic unit 56.

  In the arithmetic unit 56, from the above image data, the external dimensions of the semiconductor wafer W, the presence or absence of external chipping, crystal defects, cracks occurring on the surface, and the like are detected. In addition, the size of the unevenness of the saw mark is derived. The detection result is stored in the memory in the arithmetic unit 56 and displayed on the display unit 58. The arithmetic unit 56 and the display unit 58 may be configured by a personal computer system, or may be created by forming a circuit and a program independently.

  FIG. 3 shows an example of an image of the surface of the semiconductor wafer W taken by the CCD area sensor camera 54 of 960 × 1280 pixels in this embodiment. In FIG. 3, the intensity distribution obtained by photographing the light scattered or reflected at the saw mark is schematically shown as a band. As shown in the above-described equation (3), this difference in strength represents a difference in surface inclination at that portion. In FIG. 3, the irradiation light is incident from the upper side to the lower side in the drawing.

In order to calculate the surface unevenness curve from the image of the intensity distribution of the scattered light or reflected light shown in FIG.
The intensity of the scattered light or reflected light measured along each pixel row on the CCD image is integrated according to the above-described equation (5). As a result, it is possible to instantaneously obtain surface unevenness curves corresponding to the number of columns of the image. However, since the surface unevenness is obtained as a result of a stochastic phenomenon, in this embodiment, the average value of the size of the surface unevenness of the entire observation region is given as a numerical value. Hereinafter, a specific method at that time will be described.

  The obtained scattered light or reflected light intensity data is averaged for each row in the arithmetic unit 56, and an integral calculation is performed from these values to obtain a curve of surface irregularities in the column direction. By doing so, random surface roughness other than the saw mark is averaged, and only the feature of the saw mark can be extracted. Then, the size of the saw mark is evaluated as the PV value (difference between the maximum value and the minimum value) on the curve of the obtained surface unevenness. As a result, it is possible to more easily extract the saw mark and measure its size. In this case, the direction in which the line by the saw mark extends (corresponding to the uneven direction; hereinafter also referred to as “the direction of the saw mark”) must be parallel to the row of the image. When the saw mark direction is deviated from the image row direction, the surface unevenness curve is evaluated to be small, so care must be taken.

  Next, the light source device 52 will be described. FIG. 4 shows an example of the main part of the light source device 52. As described above, the light source device 52 is required to have a very high parallelism in the plane of incidence on the semiconductor wafer W. On the other hand, high parallelism is not required in a plane perpendicular to the incident surface. That is, since the distribution curve of the size of the surface irregularities gives a cross-sectional shape along a virtual straight line drawn on the surface, in this embodiment, the incident surface of the irradiation light from the light source device 52 is taken as a cross section. This is because importance is attached to the shape of the surface irregularities.

  Further, in FIG. 1, when the surface of the semiconductor wafer W is also tilted around the x-axis, the illuminance of the irradiation light on the surface is affected by the tilt, so that it differs from the tilt around the true z-axis. Measurement results may be obtained. However, if the irradiation light from the light source device 52 is not parallel to the incident surface and the direction perpendicular to the incident surface, light rays from many irradiation sources irradiate one point on the surface of the semiconductor wafer W. The influence of the inclination of the surface of the wafer W around the x axis on the illuminance can be suppressed. In consideration of these points, the light source device 52 uses, as the light source 52a of the light source device 52, a linear LED light source 52a as a light emitting unit in which a plurality of LEDs are arranged in a row in a direction perpendicular to the incident surface. The light emitted from the LED array is imaged on the slit 52c placed behind it by the first cylindrical lens 52b, and a part of the light is diffused again after passing through the slit 52c, and is reflected by the second cylindrical lens 52d. Parallel light.

  The parallelism of the light that has passed through the second cylindrical lens 52d on the incident surface increases as the width of the slit 52c decreases. On the other hand, since there is no lens effect in the longitudinal direction (perpendicular to the incident surface) of the first cylindrical lens 52b and the second cylindrical lens 52d, light from individual LEDs diverges. In this way, it is possible to form irradiation light that is parallel light in the direction parallel to the incident surface and divergent light in the direction perpendicular to the incident surface. Here, the intensity of the divergent light decreases with distance, but if the length of the LED row is sufficiently long, the intensity becomes uniform around the center. In addition, the degree of uniformity of the irradiation light intensity can be further improved by sufficiently increasing the distance between the light source device 52 and the semiconductor wafer W as described above.

  Next, another example of the light source device 52 will be described. In this example, first, a light source 52e as shown in FIG. 5 is used. In this case, the light emitted from the separately provided light emitting element 52h is incident on one end of the optical fiber bundle 52g, and the emission side end of the optical fiber bundle 52g is linearly arranged in one or more rows. A light emitting part 52f as a light emitting part is formed. According to this, it is possible to obtain a linear light source with higher accuracy, and it is possible to give a degree of freedom in the arrangement of the light emitting elements themselves, and the layout of the entire apparatus can be facilitated.

  Further, in this example, the optical system for simplifying the light emitted from the light source 52a or the light source 52e into parallel light in the direction parallel to the incident surface and diverging light in the direction perpendicular to the incident surface is simplified. Yes. That is, as shown in FIG. 5, the light emitted from the light source 52e is converted into parallel light in the direction parallel to the incident surface and divergent light in the direction perpendicular to the incident surface by the cylindrical lens 52k. With this configuration, the light source device 52 can be configured more easily, and the layout of the entire device can be facilitated and the cost can be reduced.

  Incidentally, in the semiconductor wafer surface inspection system 50 described above, the light source device 52 has to irradiate the entire surface of the semiconductor wafer W with light, and particularly with respect to the direction of the saw mark, the width of the semiconductor wafer W is 3. It was necessary to irradiate light from a light emitting part having a width of about twice. In other words, the width of the light source 52a and the light emitting portion 52f is required to be about three times the width of the semiconductor wafer W. This is because the light intensity on the surface of the semiconductor wafer W can be made more uniform by emitting light from the light emitting portion having a width about three times the width of the semiconductor wafer W, and is photographed by the photographing device 54. This is because the occurrence of vignetting in the image of the semiconductor wafer W can be prevented. FIG. 6A schematically shows the relationship between the width of the light irradiation unit 52f, which is a light emitting unit, and the width of the semiconductor wafer W in the saw mark direction when the light source device 52 shown in FIG. 5 is used. . In addition, the mirror 53 is abbreviate | omitted in Fig.6 (a) and FIG.6 (b) mentioned later.

  However, securing a light emitting portion having a width about three times the width of the semiconductor wafer W to be measured in the saw mark direction can hinder cost reduction of the light source device 52 and hinder downsizing of the entire system. On the other hand, in the present embodiment, in the optical path between the light irradiation unit 52f that is the light emitting unit of the light source device 52 and the semiconductor wafer W, as shown in FIG. A pair of mirrors 52m and 52n were installed in parallel with each other at an interval equivalent to the width so that the reflecting surfaces were on surfaces facing each other.

  In this case, the width of the light irradiation part 52f and the width of the semiconductor wafer W are substantially equal. However, by creating a real image of the light irradiation part 52f by the mirrors 52m and 52n, the width of the semiconductor wafer W is reduced to 3%. It is possible to obtain the same effect as the installation of the double light irradiation unit 52f. As a result, the cost of the optical device 52 can be reduced, and downsizing of the system can be promoted. 6 illustrates an example in which the mirrors 52m and 52n are applied to the optical device 52 illustrated in FIG. 5, but the light emitting unit of the optical device 52 illustrated in FIG. 4 or other types of optical devices is illustrated. Of course, it can be applied.

  FIG. 7 shows the arrangement of the light irradiation unit 52f, the mirrors 52m and 52n, and the semiconductor wafer W when a real image of the light irradiation unit 52f is created by the mirrors 52m and 52n. In FIG. 7, the semiconductor wafer W is represented by a square ABCD having a length a on one side. The hatched region Wa in the semiconductor wafer W is an irradiation region by the light irradiation unit 52f in a state where vignetting has occurred. The size of the light irradiation part 52f is indicated by KL, and is larger by d on both sides than the length a of one side of the semiconductor wafer W. The distance between the light irradiation part 52f and the semiconductor wafer W is represented by h.

The mirror 52n for making the light source appear larger is represented by IJ, and is assumed to be placed away from the semiconductor wafer W by x. Further, it is assumed that the light irradiation unit 52f side of the semiconductor wafer W has a length y on the light irradiation unit 52f side and z on the opposite side. From this figure, the region of the semiconductor wafer illuminated by the light irradiation part 52f of length KL is EFGH, and the other areas are not illuminated unless the light irradiation part 52f is larger. That is, light must be irradiated by the real image MN by the mirror 52n of the light irradiation unit 52f indicated by the line segment KL. Considering this, the mirror 52n must be within a corner where the point H looks at the real image LN of the light irradiation unit 52f. Therefore, the upper end of the mirror 52n is a point I where HL and the mirror surface intersect. Considering the C point in the same way, the lower end of the mirror 52f is a point J where CN and the mirror surface intersect. The other points G and D are illuminated by the image of the light irradiation unit 52f.

となる。例えば、ｄ／ａ＝０．２、ｈ／ａ＝３、ｓ／ａ＝０．２と置き、ｘ／ａの関数としてｙ／ａ、ｚ／ａの値を計算した結果を図８に示す。図８から分かるように、ミラー５２ｎの長さはｙ＋ｚで表されるから、ミラー５２ｎの位置が半導体ウェハＷから離れるほど、ミラー５２ｎに必要な長さは大きくなる。より短いミラー５２ｎを使用可能とするためには、ｘ＝０すなわち、半導体ウェハＷにミラー５２ｎを接しておけばよいことになる。 From the above, when y and z are displayed as a function of x

It becomes. For example, assuming that d / a = 0.2, h / a = 3, and s / a = 0.2, the results of calculating y / a and z / a as a function of x / a are shown in FIG. . As can be seen from FIG. 8, the length of the mirror 52n is expressed by y + z. Therefore, the longer the position of the mirror 52n is from the semiconductor wafer W, the greater the length required for the mirror 52n. In order to use the shorter mirror 52n, x = 0, that is, the mirror 52n may be in contact with the semiconductor wafer W.

  The values y and z shown in FIGS. 7 and 8 are the minimum values for preventing the vignetting of the light emitted from the light source device 52 on the semiconductor wafer W. Therefore, by using y and z that are greater than or equal to the values of y and z corresponding to x shown in FIGS. 7 and 8, it is possible to prevent the occurrence of vignetting more reliably. On the other hand, when y and z smaller than the values of y and z corresponding to x shown in FIGS. 7 and 8 are used, a gap is generated between the actual light irradiation unit 52f and the real image by the mirror 52n. However, vignetting may occur partially, or vignetting may occur in a region of the semiconductor wafer W opposite to the light irradiation unit 52f.

  FIG. 9 shows a CCD image when the mirror 52f is photographed while being slightly separated from the right side of the semiconductor wafer W. In any of the images, the left side of the semiconductor wafer W is chipped, whereas the right side is almost entirely visible, and the effect of the mirror 52n can be confirmed. However, the brightness of this part is darker than that of the central part, which is not sufficient for an image. This is because the length of the mirror 52n is short and the virtual light source that can be projected by the mirror 52n cannot be used sufficiently. In order to improve this, it is necessary to make the mirror 52n larger than the present one and determine the arrangement for placing the mirror 52n in consideration of the above calculation result.

  The semiconductor wafer surface inspection system to which the present invention is applied is not limited to the system having the configuration described above. Further, in the above embodiment, the intensity data of the scattered light or reflected light obtained by the area sensor camera 54 is averaged for each row by the arithmetic unit 56, and the integral calculation is performed from these values, and the column direction The example of obtaining the surface unevenness curve for the above has been described, but the contents of the data processing in the system to which the present invention is applied are not limited to the above. For example, the arithmetic unit 56 may be a system that performs frequency analysis on the surface unevenness curve using Fourier transform to obtain the amplitude density distribution for each frequency.

In the above description, an example in which the irregularities on the surface of the semiconductor wafer are saw marks has been described. However, the present invention can also be applied to irregularities on other surfaces of the semiconductor wafer. For example, when the semiconductor wafer is a solar cell wafer, the unevenness on the surface may be unevenness due to electrodes formed on the wafer surface. More specifically, the present invention may be applied to identification of irregularities by bus bars or fingers of a solar cell wafer. As described above, in the present invention and all the embodiments, the irregularities on the surface of the semiconductor wafer include not only saw marks but also irregularities caused by other causes, and formations of different materials on the surface.

  If it does so, it will become possible to detect formation abnormality of a bus bar and a finger of a wafer for solar cells more easily or surely.

[Example 2]
Next, a second embodiment of the present invention will be described. Here, as shown in the first embodiment, in the conventional system, the length of the light emitting unit of the light source device needs to be about three times the width of the region to be imaged of the semiconductor wafer. When the portion is shorter than this length, the irradiation light intensity in the area to be photographed may be non-uniform or vignetting may occur in the area to be photographed. In this regard, when the linear unevenness on the surface of the semiconductor wafer is not linear but is bent (bent) (for example, when it is bowed), the curvature center side of the bent (bending is negative). It is empirically known that vignetting is less when the light is irradiated from the same direction. FIG. 10A shows vignetting when light is incident from the opposite side of the center of curvature of the linear unevenness. FIG. 10B shows vignetting when light is incident from the center of curvature of the linear unevenness. As can be seen from FIG. 10, vignetting is less when light is incident from the center of curvature of the linear unevenness (the direction in which bending is negative) (the area where reflected light and scattered light can be obtained is wider). ing.

  Therefore, in this embodiment, when the line in the linear unevenness on the surface of the semiconductor wafer is accompanied by bending (deflection), from the center of curvature of the line of the linear unevenness (direction in which the bend is negative). The light was irradiated. According to this, even when the length of the light emitting part is not sufficiently long, it is possible to reduce the influence of vignetting as much as possible. In the present embodiment, all the system configurations described in the first embodiment can be used. Also, in this embodiment, conversely, when the linear irregularities are not linear but accompanied by bending, and when it is particularly desired to measure a part of the linear irregularities, the center of curvature is relative to the linear irregularities. The light may be irradiated from the opposite side. Then, it is possible to obtain information limited to a partial region of the linear unevenness (for example, a region where the linear unevenness is more perpendicular to the incident direction of light) by a simple method. . The matters described in the first embodiment and the second embodiment can be used in combination or independently as necessary.

Example 3
Next, Embodiment 3 of the present invention will be described. In the present embodiment, as shown in the first embodiment, the area sensor camera 54 does not measure the saw mark by photographing the entire surface of the semiconductor wafer W, but uses a CCD as a sensor. An example of a system for measuring a saw mark by photographing only a linear region on the surface of the semiconductor wafer W will be described.

  FIG. 11 shows a conventional semiconductor wafer surface inspection system 100 based on the premise that the saw marks on the surface of the semiconductor wafer W are continuously measured on the production line. FIG. 11A is a plan view of the system, and FIG. 11B is a side view as seen from a direction orthogonal to the moving direction of the semiconductor wafer W on the production line. As shown in FIG. 11A, in the conventional system, the semiconductor wafer W is placed on the belt conveyors 105a and 105c so that the direction of the saw mark is perpendicular to the moving direction in the production line.

In the conventional system 100, the light source device 101 that irradiates the semiconductor wafer W enters the semiconductor wafer W from a direction orthogonal to the saw mark direction. In other words, the light source device 101 as a light emitting unit is formed by arranging point light sources in parallel with the direction of the saw mark. Light irradiated from the light source device 101 is reflected or scattered (reflected) in a line-shaped imaging region (hereinafter also referred to as a line imaging region) 103a formed in parallel with the saw mark direction on the surface of the semiconductor wafer W. Light or scattered light) is detected by a line sensor camera 103 as an imaging apparatus shown in FIG.

  In this conventional example, along with the movement of the semiconductor wafer W by the transfer device 105 using the belt conveyors 105a, 105c, etc. (it is natural that belt conveyors other than 105a, 105c may be included), the line sensor camera When unevenness due to saw marks passes under 103, reflected light or scattered light according to the height enters the line sensor camera 103. Therefore, the size of the unevenness of the saw mark can be measured based on the temporal change of the detection signal by each sensor element of the line sensor camera 103. The transport device 105 corresponds to a transport device in this embodiment.

  Here, when the reflected light or scattered light from the linear region on the surface of the semiconductor wafer W is detected using the line sensor camera 103 as described above, the light source device 101 is in a direction orthogonal to the direction of the saw mark ( Regarding the movement direction of the semiconductor wafer W, it is not necessary to irradiate the entire width of the semiconductor wafer W, and it is sufficient to irradiate only the line width of the line imaging region 103a. On the other hand, regarding the direction of the saw mark, the light source device 101 needs to irradiate light with a width of about 2 to 3 times the width of the semiconductor wafer W, as described above. This also caused the necessity of using an expensive light source device 101 and hindered cost reduction of the entire system.

  In the above system, as shown in FIG. 11B, the light source device 101 and the line sensor camera 103 are provided on the upper side of the semiconductor wafer W, and the lower side is provided on the lower side of the semiconductor wafer W. A light source device 102 and a lower line sensor camera 104 are provided. Then, it is possible to measure unevenness due to saw marks from above and below the semiconductor wafer W. In this case, the lower light source device 102 and the lower line sensor camera 104 need to be arranged using the space 105b between the belt conveyor 105a and the belt conveyor 105c in the transport device 105. As a result, it is necessary to widen the space 105b between the belt conveyor 105a and the belt conveyor 105c, and it may be difficult to smoothly transfer the semiconductor wafer W by the transfer device 105. More specifically, the distance between the belt conveyor 105a and the belt conveyor 105c is increased, and the vibration during the movement of the semiconductor wafer W may be increased.

  Further, as shown in FIG. 11B, the lower light source device 102 is obstructed by the belt conveyors 105a and 105c, and irradiates light obliquely with respect to the surface of the semiconductor wafer W at an angle similar to that of the upper light source device 101. It was sometimes difficult. Accordingly, in practice, it is necessary to take measures such as bending the irradiation light from the lower light source device 106 using the mirror 106, which may be disadvantageous in terms of the number of parts and the cost of parts.

  Further, in the above conventional example, as described above, since the size of the saw mark is measured based on the temporal change of the signal intensity in each sensor of the line sensor camera 103 and the lower line sensor camera 104, the conveyance is performed. In some cases, jitter, which is the speed unevenness of the apparatus 105, affects the measurement result.

Next, the semiconductor wafer surface inspection system 10 according to the present embodiment configured in view of the above inconvenience will be described with reference to FIG. 12A is a plan view of the semiconductor wafer surface inspection system according to the present embodiment, FIG. 12B is a side view of the production line as viewed from the moving direction of the semiconductor wafer W, and FIG. 12C is the production line. 4 is a side view seen from a direction orthogonal to the moving direction of the semiconductor wafer W. FIG. As can be seen from FIG. 12A, in this embodiment, the semiconductor wafer W is transferred by the transfer device 5 in a direction parallel to the direction of the saw mark.

  Further, the line sensor camera 3 is set so that the direction of the line sensor (not shown) is orthogonal to the direction of the saw mark, so that the line imaging region 3a is also set to be orthogonal to the direction of the saw mark. . Furthermore, the light source device 1 is disposed so as to irradiate light to the line imaging region 3a from a direction parallel to the line of the line imaging region 3a. Note that the light emitted from the light source device 1 has a high degree of parallelism on the incident surface, which is the same in this embodiment. As a result, in this embodiment, it is possible to irradiate light to an area that is sufficiently longer than the length of the line photographing area 3a without increasing the width of the light source device 1 as in the conventional example described above. It is.

  Moreover, as shown in FIG.12 (c), since the lower side light source device 2 in a present Example is narrow enough, and is irradiating light from the outer side surface of the belt conveyor 5a of the conveying apparatus 5, The space 5b between the belt conveyor 5a and the belt conveyor 5c in the transport device 5 can be kept small. Therefore, the transfer device 5 can move the semiconductor wafer W more smoothly, and vibration during movement of the semiconductor wafer W can be suppressed. Moreover, since it is not necessary to change the direction of the irradiation light from the lower light source device 2 by a mirror or the like, the number of parts and cost of the system can be reduced.

  In the present embodiment, the semiconductor wafer W is arranged so as to move in the direction of the saw mark, and constitutes the line sensor camera 3 instead of the temporal change of the detection signal in each sensor element of the line sensor camera 3. The size of the saw mark is measured based on the change of the detection signal between the sensor elements, that is, the spatial change. Therefore, it is possible to reduce as much as possible the influence on the measurement result of the jitter of the transport device 5.

  In FIG. 13, the figure which compared the aspect of the signal detection in the conventional system mentioned above and the system of a present Example is shown. As shown in FIG. 13A, in the conventional system, a temporal change in signal intensity due to reflected light or scattered light from each minute region of the line imaging region 103a is detected, and this temporal change or its time integration is detected. The saw mark is measured based on the value. On the other hand, in the semiconductor wafer surface inspection system 10 according to the present embodiment, as shown in FIG. 13B, the signal intensity distribution (spatial change) from each minute region in the line imaging region 3a at a certain moment or Based on the integrated value, the saw mark is measured. Of course, in the system according to the present embodiment, processing such as taking a temporal average may be performed on the distribution (spatial change) of the signal intensity from each minute region or its integral value.

  In the above-described embodiment, the light source device 1 and the lower light source device 2 are configured by separate light sources. However, it is as if the light emitted from the same light source device is separated using an optical element. You may use as two light sources. FIG. 14 shows a configuration example when the light source device and the lower light source device are integrated. In FIG. 14, the light irradiation part 11 of the optical fiber is arranged on the side surface of the semiconductor wafer W. Here, the semiconductor wafer W moves perpendicular to the paper surface. In FIG. 14, the belt conveyor is omitted.

Two stages of fiber output ends 11 a and 11 b are arranged in the light irradiation unit 11. Only one fiber output end 11a and 11b may be provided in a direction perpendicular to the paper surface, or a plurality of fiber output ends 11a and 11b may be arranged. A condensing lens 12 is provided in front of the light irradiation unit 11 so that the optical axis center thereof coincides with the thickness center of the semiconductor wafer W. Further, the distance between the condensing lens 12 and the fiber output ends 11 a and 11 b coincides with the focal length of the condensing lens 12.

  According to this configuration, it is possible to irradiate the upper surface of the semiconductor wafer W by making the light emitted from the upper fiber output end 11 a into the substantially parallel light by the condenser lens 12. Similarly, it is possible to irradiate the lower surface of the semiconductor wafer W using light emitted from the lower fiber output end 11b as substantially parallel light. With such a configuration, the light source that irradiates the upper surface of the semiconductor wafer W and the light source that irradiates the lower surface can be integrally configured, and the assembly of the system can be further simplified. In addition, in the example shown in FIG. 14, 11a and 11b may be LED issuing units instead of the fiber output ends, and the condensing lens 12 may be configured by a cylindrical lens or a Fresnel lens. Further, the condensing lens 12 is not necessarily constituted by one lens, and may be constituted by, for example, two lenses each having an optical axis inclined toward the semiconductor wafer W side.

  In the above-described embodiment, the example in which the linear irregularities on the surface of the semiconductor wafer are saw marks has been described. However, the present invention can also be applied to the measurement of linear irregularities other than the saw marks. Moreover, as a semiconductor wafer, it is applicable also to a solar cell other than the wafer for semiconductor element manufacture. Furthermore, the present invention is not limited to a system that measures the angle and size of linear irregularities, but also performs frequency analysis on the linear irregularities using Fourier transform to obtain the amplitude density distribution for each frequency. It is also applicable to the system.

DESCRIPTION OF SYMBOLS 1, 52, 101 ... Light source device 2, 102 ... Lower light source device 3, 103 ... Line sensor camera 3a, 103a ... Line imaging | photography area | region 4, 104 ... Lower line sensor camera 5 105 ... Conveying devices 5a, 105a ... Belt conveyors 10, 50, 100 ... Semiconductor wafer surface inspection system 11 ... Light irradiation units 11a, 11b ... Fiber output end 52 ... Light source device 52f: Light irradiation parts 52m, 52n: Mirror 54 ... Area sensor camera 56 ... Arithmetic device 58 ... Display device W ... Semiconductor wafer

Claims (12)

A semiconductor wafer surface inspection system for detecting linear irregularities on the surface of a semiconductor wafer or measuring the size of the linear irregularities,
A light source device that irradiates light that is parallel light on the incident surface from a direction oblique to the surface of the semiconductor wafer;
A photographing device for photographing a line photographing region that is a line-shaped region on the surface of the semiconductor wafer,
The light source device is arranged to irradiate light from a direction parallel to the line with respect to a line photographing region photographed by the photographing device,
In the state where the semiconductor wafer is arranged so that the uneven direction which is a direction parallel to the line in the linear unevenness is perpendicular to the direction of the line, the linear unevenness is detected, or the line A surface inspection system for a semiconductor wafer, characterized in that the size of the uneven surface is measured. Further comprising a transport device that supports the semiconductor wafer and moves it so as to pass through the line imaging region,
The transport device moves the supported semiconductor wafer in the uneven direction so that the supported semiconductor wafer passes through the line imaging region in a state where the uneven direction and the line direction are orthogonal to each other. The semiconductor wafer surface inspection system according to claim 1. The transport device includes a plurality of belt conveyors arranged in parallel with a predetermined interval in the moving direction of the semiconductor wafer,
The light source device includes a light source device for lower surface that irradiates light from a lower side of the semiconductor wafer to a lower surface of the semiconductor wafer,
3. The semiconductor wafer according to claim 2, wherein the lower surface light source device is arranged to irradiate light on a lower surface of the semiconductor wafer in a space between the belt conveyor and the belt conveyor. Surface inspection system. The light source device further includes an upper surface light source device that irradiates the upper surface of the semiconductor wafer from the upper side of the semiconductor wafer,
4. The semiconductor wafer surface inspection system according to claim 3, wherein the upper surface light source device and the lower surface light source device are integrally formed. A light source device that irradiates light that is parallel light on the incident surface from a direction oblique to the surface of the semiconductor wafer;
An imaging device for imaging the surface of the semiconductor wafer,
Detecting irregularities on the surface of the semiconductor wafer based on the intensity of scattered light or reflected light of the light emitted from the light source device obtained by photographing the surface of the semiconductor wafer with the imaging device, or A semiconductor wafer surface inspection system for measuring the size of irregularities,
The light source device is
A light emitting section configured in a line shape having a length equal to or greater than the width of the area to be imaged in the semiconductor wafer and including the area to be imaged in the length direction;
Two flat plate reflecting mirrors provided on a plane orthogonal to the line segment at both ends or both ends of the light emitting section and having reflecting surfaces facing each other in an optical path between the light emitting section and the semiconductor wafer;
A surface inspection system for a semiconductor wafer, comprising: The flat plate mirror is provided such that the reflection surface is disposed between an end portion of the light emitting portion and an end surface on the end portion side of the region to be photographed. Item 6. A semiconductor wafer surface inspection system according to Item 5.   The flat reflector is disposed such that an end of the flat reflector opposite to the light emitting unit is located farther from the light emitting unit than an end surface of the region to be photographed on the light emitting unit side. 7. The semiconductor wafer surface inspection system according to claim 5, wherein the semiconductor wafer surface inspection system is provided. The light source device is
The said light is irradiated from the curvature center side of the line of the said linear unevenness | corrugation, when the line in the linear unevenness | corrugation in the surface of the said semiconductor wafer is accompanied by a curve. The surface inspection system for a semiconductor wafer according to one item.   The said semiconductor wafer is a wafer for solar cells, The said unevenness | corrugation is an unevenness | corrugation by the electrode provided in the wafer surface for solar cells, The semiconductor wafer as described in any one of Claim 1 to 8 characterized by the above-mentioned. Surface inspection system. A light source device that irradiates light that is parallel light on the incident surface from a direction oblique to the surface of the semiconductor wafer;
An imaging device for imaging the surface of the semiconductor wafer,
Based on the intensity of the scattered light or reflected light of the light emitted from the light source device obtained by photographing the surface of the semiconductor wafer with the photographing device, linear unevenness on the surface of the semiconductor wafer is detected. Or a semiconductor wafer surface inspection system for measuring the size of the linear irregularities,
The light source device is
A surface inspection system for a semiconductor wafer, wherein the light is irradiated from a center of curvature of the line of the line-shaped unevenness when a line in the line-shaped unevenness on the surface of the semiconductor wafer is bent. Irradiate light that is parallel light on the incident surface from an oblique direction with respect to the surface of the semiconductor wafer,
Photographing the surface of the semiconductor wafer;
Based on the intensity of the scattered light or reflected light from the surface of the semiconductor wafer of the irradiated light obtained by photographing the surface of the semiconductor wafer, linear irregularities on the surface of the semiconductor wafer are detected, Or a method for inspecting the surface of a semiconductor wafer for measuring the size of the linear irregularities,
A method for inspecting a surface of a semiconductor wafer, comprising: irradiating the light from the center of curvature of the line of the line-shaped unevenness when a line in the line-shaped unevenness on the surface of the semiconductor wafer is curved. A semiconductor wafer surface inspection system for detecting unevenness on the surface of a semiconductor wafer or measuring the size of the unevenness,
A light source device that irradiates light that is parallel light on the incident surface from an oblique direction with respect to the entire surface of the semiconductor wafer;
An imaging device for imaging the entire surface of the semiconductor wafer,
The unevenness is detected based on a two-dimensional intensity distribution of scattered light or reflected light of the light emitted from the light source device obtained by photographing the entire surface of the semiconductor wafer with the photographing device. Or a semiconductor wafer surface inspection system for measuring the size of the irregularities,
The semiconductor wafer surface inspection system, wherein the semiconductor wafer is a solar cell wafer, and the irregularities are irregularities formed by electrodes provided on the surface of the solar cell wafer.

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