JP4734398B2 - Shape measuring device and shape measuring method - Google Patents

Description

  The present invention is based on the projection image of the shape of the end surface (end surface) of the disk-shaped measurement object (mainly semiconductor wafer, other hard disk aluminum substrate, glass substrate, etc.) chamfered. The present invention relates to a shape measuring apparatus and a shape measuring method for measuring.

When manufacturing a semiconductor wafer (hereinafter referred to as a wafer) or manufacturing a device using a wafer, the edge (edge) of the wafer may be damaged or chipped due to contact with other components or a wafer holding member. There is a case. In addition, the wafer may break due to the scratches and chips. It is considered that the ease of occurrence of scratches and chips at the edge of the wafer is related to the shape of the wafer end face (so-called edge profile portion). For this reason, it is important to correctly measure the edge profile of a disk-shaped measuring object represented by a wafer. The shape of the end face here is a profile in the thickness direction (one-dimensional direction) of the wafer, that is, the shape of the cross section in the thickness direction, and is hereinafter referred to as an edge profile.
A typical example of the edge profile measurement method is the nondestructive inspection method (SEMI-MF-) specified in the Semi Standard, which is a standard established by the Semiconductor Equipment and Materials International (SEMI). 928-0305 Standard Method B). In this non-destructive inspection method, light is projected from the direction (first direction) substantially parallel to the front and back surfaces of the wafer on the chamfered edge of the disk-shaped wafer, and the direction of light projection. In this method, a projected image of the end face of the wafer is picked up by a camera from a direction opposite to the surface, and the shape of the end face of the wafer is measured based on the projected image (hereinafter referred to as an optical projection measurement method). The contour of the projected image obtained by this optical projection measurement method represents the cross-sectional shape of the end face of the wafer (the cross-sectional shape cut in the thickness direction).
The optical projection measurement method is shown, for example, in Patent Document 1 as a shape detection method using a shape detector that detects the cross-sectional shape of a wafer. Patent Document 2 proposes an optical system for preventing the occurrence of blurring of edges and diffraction fringes in a projected image in the optical projection measurement method.
FIG. 3A is a diagram illustrating an example of a projection image (black shadow portion) obtained by imaging the end face of the wafer 1 by the optical projection measurement method.

The main purpose of the edge profile measurement is to evaluate whether the end face shape is within an allowable range with respect to a predetermined design shape (appropriateness). For this reason, in the measurement of the edge profile, usually, an index value of the end face shape is calculated by executing predetermined image processing on the projected image of the wafer end face, and whether the calculated index value is within an allowable range. The suitability is determined depending on whether or not. The index values are, for example, a chamfering width k, a chamfering angle θ, a chamfering radius rm (also referred to as a tip R) of the wafer end surface, and the like.
FIG. 4 is a diagram for explaining an example of the index value of the edge profile of the wafer. As shown in FIG. 4, the chamfer width k is determined from the boundary position Q1 (or Q2) between the front and back surfaces of the wafer (surfaces substantially parallel to each other) and the chamfered portion E (end surface) at the end in the projected image. , The width to the apex of the chamfered portion (end surface) (the length in the direction parallel to the front and back surfaces (radial direction of the wafer 1)). Further, the chamfering angle θ is an angle formed by an extension line of the front and back surfaces of the wafer 1 and a tangent to the surface of the chamfered portion E (end surface) near the boundary position Q1 (or Q2) in the projection image. The chamfer radius rm is the radius of the arc when the chamfered portion E (end surface) is approximated by an arc.
JP 7-218228 A JP 2006-145487 A

By the way, the measurement site of measurement objects, which are precision parts such as wafers (semiconductor wafers), usually maintains a clean environment. A state in which an object such as dust is present on the measurement object occurs. In the optical projection measurement method, if there is an adhering substance such as dust on the measurement site (end surface) of the wafer (measurement object), depending on the position of the adhering substance, In some cases, the projected image of the deposit appears as a protrusion. FIG. 3B is a diagram schematically showing a state in which the projection image of the deposit is reflected in the projection image (black shadow portion) obtained by imaging the end face of the wafer 1 by the optical projection measurement method. is there. Note that the size of the projection image of the deposit in FIG. 3B does not necessarily represent the size of the deposit on the actual wafer 1.
As shown in FIG. 3B, when an image of an adhering substance such as dust is reflected in the projection image obtained by the optical projection measurement method, the end surface shape (the index value) of the measurement object is accurately measured. However, there is a problem that a wafer that should be identified as a conforming product is erroneously identified as a nonconforming product.
Therefore, the present invention has been made in view of the above circumstances, and the object of the present invention is to provide an attachment existing on the end face when measuring the shape of the end face of the disk-shaped semiconductor wafer based on the projected image. An object of the present invention is to provide a shape measuring device and a shape measuring method capable of performing a correct shape measurement without being affected by a kimono.

In order to achieve the above object, a shape measuring apparatus according to the present invention projects light from a direction substantially parallel to the front and back surfaces of a semiconductor wafer to a chamfered end of a disk-shaped semiconductor wafer. And a shape measuring device for measuring the shape of the end face of the semiconductor wafer based on the projected image, and an imaging means for picking up a projected image of the end face of the semiconductor wafer from a direction opposite to the light projecting direction In addition, each component shown in the following (1-1) to (1-5) is provided.
(1-1) A rotation support mechanism that supports the semiconductor wafer so as to be rotatable in the circumferential direction.
(1-2) With the rotation support mechanism, the semiconductor wafer is rotated by a predetermined first set angle with respect to a predetermined reference support position, and positive or negative with respect to the first set angle from the first support position. Rotation control means for supporting at two or more support positions including the first support position and the second support position in a range up to a second support position rotated by an opposite predetermined second set angle.
(1-3) An imaging control unit that causes the imaging unit to capture a projected image of the end surface of the semiconductor wafer supported at each of the two or more support positions by the rotation control unit.
(1-4) Index value calculation means for calculating an index value of the end face shape by executing predetermined image processing for each of a plurality of projection images obtained by the processing of the imaging control means.
(1-5) The reference support position is selected by selecting one representative value or calculating one aggregate value based on the plurality of index values calculated by the index value calculation means according to a predetermined rule. Measurement value deriving means for deriving a measurement value of the shape of the end face of the semiconductor wafer corresponding to.
The chamfer width k of the end face of the semiconductor wafer is 0.1 mm to 1.0 mm, the ratio of the chamfer width k to the radius r of the semiconductor wafer is 0.0067 or less, and the first set angle is + δ1, When the second set angle is −δ2, a chamfered portion in the projected image of the end surface of the semiconductor wafer supported at the reference support position is obtained by the processing of the imaging control unit. Each of the plurality of projected images is in a range of 2 ° or more and 6.6 ° or less determined so as to deviate from a region projected as a chamfered portion .
A semiconductor wafer often has a radius r of about 150 [mm] and a chamfer width k of about 0.35 [mm], but the chamfer width k is a minimum of 0.10 [mm] in an intermediate stage of processing. In some cases, the shape of the end face is measured for a semiconductor wafer that has been processed to such a degree as to be processed. Therefore, considering the actual situation of the semiconductor wafer in which r is about 150 [mm] and k is about 0.10 [mm] or more, δ1 and δ2 are each 2 ° or more 6 ° as in the present invention. It is practical to be within a range of .6 ° or less.

For example, the rotation control unit causes the rotation support mechanism to support the semiconductor wafer at three or more support positions including the reference support position, the first support position, and the second support position, and the imaging It is conceivable that the control means causes the imaging means to pick up a projected image of the end face of the semiconductor wafer supported at each of the three or more support positions by the rotation control means.
Since a measurement environment of a semiconductor wafer is usually maintained in a clean environment, a state in which a plurality of deposits adhere to a relatively narrow area of the semiconductor wafer hardly occurs. Even if the deposit is present at one end of the semiconductor wafer, at least one of the plurality of projection images obtained by the imaging control means shows the projection image of the deposit. There is a very high probability that it will not (not formed as a protruding part of the contour).
On the other hand, the end face shape of a semiconductor wafer is usually regarded as the same shape in a relatively narrow region.
Therefore, if one representative value is selected or one aggregated value is calculated based on a plurality of the index values obtained by the index value calculating means, the representative value or aggregated value is not affected by the influence of the deposit. It is possible to obtain a measured value (evaluation value of the end face shape) that is not or very small in the influence of the deposit.
The rule for selecting one representative value is, for example, a rule for selecting a median value, a minimum value, or a maximum value from a plurality of the index values. Further, the rule for calculating the one aggregated value is, for example, a rule of calculating an average value for a predetermined number (including the total number) in order from the smallest or largest of the plurality of index values. is there.
Further, as the index value, either a chamfer width or a chamfer radius of the end face of the semiconductor wafer can be considered. The contents of each index value are as already described based on FIG.

The present invention can also be regarded as a shape measuring method for performing measurement using the shape measuring apparatus according to the present invention described above.
That is, in the shape measuring method according to the present invention, light is projected by the light projecting means from the direction substantially parallel to the front and back surfaces of the semiconductor wafer with respect to the chamfered end portion of the disk-shaped semiconductor wafer. This is a shape measuring method in which a projected image of the end face of the semiconductor wafer is picked up by an imaging means from a direction opposite to the light projecting direction, and the shape of the end face of the semiconductor wafer is measured based on the projected image. It is a measuring method which performs each process shown in 1)-(2-3). (2-1) A first support position in which the semiconductor wafer is rotated by a predetermined first set angle with respect to a predetermined reference support position by a rotation support mechanism that rotatably supports the semiconductor wafer in its circumferential direction. 2 including the first support position and the second support position in a range from the first support angle rotated to a second support position rotated by a predetermined second set angle opposite in polarity to the first set angle. A rotation / imaging process of supporting at two or more support positions, capturing a projected image of the end face of the semiconductor wafer supported at each of the support positions by the image capturing means, and recording the image data in a predetermined storage means.
(2-2) An index value calculation step of calculating an index value of the end face shape by executing predetermined image processing by a predetermined calculation means for each of the plurality of projection images obtained by the rotation / imaging process.
(2-3) According to a predetermined rule, by selecting one representative value based on a plurality of the index values calculated by the index value calculating step or calculating one aggregate value, the reference support position A measurement value deriving step of performing a process of deriving a measurement value of the shape of the end face of the semiconductor wafer corresponding to the above by a predetermined computing means.
The chamfer width k of the end face of the semiconductor wafer is 0.1 mm to 1.0 mm, the ratio of the chamfer width k to the radius r of the semiconductor wafer is 0.0067 or less, and the first set angle is + δ1, When the second set angle is −δ2, a chamfered portion in the projected image of the end surface of the semiconductor wafer supported at the reference support position is obtained by the processing of the imaging control unit. Each of the plurality of projected images is in a range of 2 ° or more and 6.6 ° or less determined so as to deviate from a region projected as a chamfered portion .

In the shape measuring method according to the present invention, the predetermined rule is a rule that selects a median, minimum value, or maximum value from a plurality of the index values, or a smaller one of the plurality of index values. Alternatively, it may be one of the rules for calculating an average value for a predetermined number in order from the largest.
In the rotation / imaging process, the rotation support mechanism supports the semiconductor wafer at three or more support positions including the reference support position, the first support position, and the second support position. It can be considered that the projected image of the end face of the semiconductor wafer supported at each of three or more support positions is captured by the imaging means.
In the shape measuring method according to the present invention, the index value may be any one of a chamfer width, a chamfer angle, and a chamfer radius of the end surface of the semiconductor wafer.
The shape measuring method according to the present invention described above also has the same operational effects as the shape measuring apparatus according to the present invention described above.

  According to the present invention, when measuring the shape of the end face of a disk-shaped semiconductor wafer based on the projected image, correct shape measurement can be performed without being affected by the deposits present on the end face.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings so that the present invention can be understood. The following embodiment is an example embodying the present invention, and does not limit the technical scope of the present invention.
Here, FIG. 1 is a schematic plan view of a shape measuring apparatus X according to an embodiment of the present invention, FIG. 2 is a schematic side view of the shape measuring apparatus X, and FIG. 3 is a diagram showing an example of a projected image of an end face of a semiconductor wafer, FIG. 4 is a diagram for explaining an example of an index value of an edge profile (end surface shape) of a semiconductor wafer, FIG. 5 is a diagram showing a relationship between a support angle and an end position in the semiconductor wafer, and FIG. 6 is a shape measurement. 4 is a flowchart showing a procedure of shape measurement processing by apparatus X.

The shape measuring apparatus X according to the present invention uses a light projecting unit from a direction parallel to the front and back surfaces of the wafer 1 to a chamfered end of the wafer 1 (semiconductor wafer) which is a disk-shaped measurement object. This is a device that projects light, captures a projected image of the end face of the wafer 1 from a direction opposite to the projecting direction, and measures the shape and thickness of the end face of the wafer 1 based on the projected image.
The wafer 1 is made of, for example, a semiconductor having a radius of about 150 [mm] and a thickness of about 0.8 [mm], and its outer peripheral end (peripheral surface) is chamfered.
The configuration of the shape measuring apparatus X will be described below with reference to the plan view shown in FIG. 1 and the side view shown in FIG. In FIG. 2, some of the components shown in FIG. 1 are omitted.
As shown in FIGS. 1 and 2, the shape measuring apparatus X includes a point light source 2 as a light projecting unit, which is a light projecting optical system (an example of a light projecting unit), and converts the light from the point light source 2 into parallel light. The collimator lens 3 is provided. The parallel light is projected from the direction R1 parallel to the front and back surfaces of the wafer 1 to the edge including the end of the wafer 1. The point light source 2 is, for example, a light source that emits white LED light through a pinhole having a diameter of 100 μm to 200 μm. The light emitting portion (pinhole) of the point light source 2 is disposed at the focal position of the collimator lens 3.
Further, the shape measuring apparatus X is a first lens 4 as a camera (corresponding to an imaging means) that captures a projected image of an edge including the end of the wafer 1 from a direction R2 facing the light projection direction R1 with respect to the wafer 1. And an aperture 5, a second lens 6, and an image sensor 7 (CCD or the like).
The first lens 4, the aperture 5, and the second lens 6 constitute a telecentric lens, and light passing through the first lens 4 is input to the image sensor 7, whereby the image sensor 7 projects an image of the edge of the wafer 1. Is imaged.

The interval (distance) between the collimator lens 3 and the first lens 4 is set to about 200 [mm], for example, and the edge of the wafer 1 is arranged in the optical path of parallel light between them.
As described above, the shape measuring apparatus X projects parallel light onto the wafer 1, so that the wafer 1 has a long depth length in the optical axis direction (projection direction R1) of the parallel light. In the image sensor 7, it is possible to obtain a good projection image with a small outline blur. Further, by adopting a point light source 2 using a white LED having a multi-wavelength component instead of a strong single-wavelength light, even if the wafer 1 has a long depth in the light projecting direction R1, In the image sensor 7, a good captured image with few diffraction fringes generated in the vicinity of the contour of the projected image can be obtained.

The shape measuring device X further includes an image processing device 8, a rotation support mechanism 9, and a control device 10.
The image processing device 8 is an arithmetic device that executes image processing based on an image captured by the image sensor 7 (an image including a projected image of the wafer 1). For example, the image processing device 8 executes a predetermined program stored in the storage unit in advance. A DSP (Digital Signal Processor), a personal computer, or the like. As will be described later, the image processing apparatus 8 calculates an index value of the end face shape of the wafer 1 by executing predetermined image processing on an image (projected image) taken by the image sensor 7. The image processing device 8 executes input of a captured image (image data) by the image sensor 7 and image processing based on the captured image in accordance with a control command from the control device 10.
The rotation support mechanism 9 is a device that supports the disk-shaped wafer 1 and adjusts the support angle of the wafer 1 by rotating and stopping the wafer 1 in the circumferential direction around the center point Ow as a rotation axis. It is. The rotation support mechanism 9 includes a rotation encoder (not shown) as an angle detection sensor for detecting the support angle (rotation angle) of the wafer 1, and positions the support position (support angle) of the wafer 1 based on the detected angle. The rotation support mechanism 9 positions the support position of the wafer 1 in accordance with a control command from the control device 10.
The control device 10 is a computer including a CPU and its peripheral devices, and the CPU controls the image processing device 8 and the rotation support mechanism 9 by executing a control program stored in the storage unit in advance ( Device that outputs control commands).

例えば，ウェーハ１の半径ｒ（例えば，設計上の半径）が１５０［ｍｍ］，ウェーハ１の面取り幅ｋ（例えば，設計上の面取り幅）が０．３５［ｍｍ］である場合，δが３．９［度］以上であればよい。即ち，ウェーハ１の面取り部における測定対象部位（基準支持位置において位置Ｐ０に位置する部位）を含む所定範囲（比較的近い範囲）に１つの付着物が存在する場合でも，基準支持位置から＋δ［度］回転させた支持位置（第１の支持位置と称する）と，基準支持位置から−δ［度］回転させた支持位置（第２の支持位置と称する）との２つの支持位置それぞれで支持されたウェーハ１について投影像を得れば，得られた２つの投影像のうちの少なくとも一方は，付着物の影響がない（付着物の投影像が輪郭の突出部として形成されない）ものとなる。
また，基準支持位置と，その基準支持位置から±δ［度］回転させた各支持位置（第１の支持位置及び第２の支持位置）との３つの支持位置それぞれで支持されたウェーハ１について投影像を得れば，得られた３つの投影像のうちの少なくとも２つ以上は，付着物の影響がないものとなる。 Next, features of the shape measuring method according to the present invention will be described with reference to FIG. FIG. 5 is a diagram illustrating the relationship between the support angle and the position of the end portion of the wafer 1.
In FIG. 5, a portion (position) indicated by P <b> 0 is a position where the outline of the chamfered portion of the wafer 1 located at that position becomes a projection image obtained by the shape measuring apparatus X. Here, the support position of the wafer 1 when the part (the chamfered portion) that is the target of the edge profile measurement of the wafer 1 is located at the position P0 is referred to as a reference support position.
Consider a case where the wafer 1 is rotated by a predetermined angle ± δ from the state where it is supported at this reference support position. As shown in FIG. 5, when the wafer 1 is rotated ± δ [degrees] from the reference support position, the measurement target portion (chamfered portion) at the position P0 is a chamfered portion (edge profile portion) in the projection image. The condition for moving to the positions P1 and P2 completely deviating from the image area E is that the angle δ satisfies the following equation (b1).

For example, when the radius r of the wafer 1 (for example, a design radius) is 150 [mm] and the chamfer width k (for example, the design chamfer width) of the wafer 1 is 0.35 [mm], δ is 3 .9 [degrees] or more. That is, even when one deposit is present in a predetermined range (relatively close range) including a measurement target part (part located at position P0 at the reference support position) in the chamfered portion of the wafer 1, + δ [ Degrees] supported at two support positions, ie, a rotated support position (referred to as a first support position) and a support position rotated at −δ [degrees] from a reference support position (referred to as a second support position). If a projection image is obtained with respect to the wafer 1 that has been obtained, at least one of the two obtained projection images is not affected by the deposit (the projection image of the deposit is not formed as a protruding portion of the contour). .
In addition, the wafer 1 supported at each of the three support positions, that is, the reference support position and each support position (first support position and second support position) rotated by ± δ [degrees] from the reference support position. If a projection image is obtained, at least two or more of the obtained three projection images will be free from the influence of the deposits.

On the other hand, the end face shape of the wafer 1 can normally be regarded as the same shape in a relatively narrow region, that is, an inappropriate (non-standard) end face shape can occur in the wafer 1 due to its crystal orientation. The end surface shape of the remaining 7 positions excluding the position where special processing such as notch is performed out of 8 positions where the central angle on the end surface (circumferential surface) is shifted by 45 degrees, and the vicinity range of each of the 7 positions In many cases, the accuracy of chamfering is ensured to such an extent that the end face shape in the range of ± 22.5 degrees in the central angle can be regarded as the same shape. Further, in order to conform to the SEMI standard M1-1103, which is a well-known standard for determining the edge shape of a semiconductor wafer, the chamfer width of the wafer 1 needs to be about 0.5 [mm], which is used as a reference. Even if the variation of various design conditions is taken into consideration, the chamfer width of the wafer 1 is about 1.0 [mm], which is at most twice that. Further, since the radius r of the wafer 1 is about 150 [mm], the ratio (k / r) of the chamfer width k to the radius r of the wafer 1 is at most 0.0067 (= 1.0 / 150). Therefore, even if the angle δ is large, it can be set to about 6.6 [degrees]. If the difference in the support angle of the wafer 1 is within such a relatively small angle (center angle) range (reference support position ± δ), the end face shape of the wafer 1 can be regarded as the same shape.
Therefore, in the measurement of the wafer 1 using the shape measuring device X, two or more including the first support position and the second support position in the range from the first support position to the second support position. A projected image is taken in each state where the wafer 1 is supported at the support position, and an index value of the end face shape is calculated based on each of the obtained plurality of projected images, and 1 based on the calculated index values. One representative value is selected or one aggregated value is calculated. The representative value or the aggregate value obtained in this way is a measured value (end face shape) of the shape of the end face (chamfered portion) located at the position P0 when the wafer 1 is supported at the reference support position, or a shape that can be regarded as the same shape. Evaluation value), and there is no influence of the adhering matter or the measurement value is very small.

Here, as the index value, any one of the chamfering width k and the chamfering radius rm of the end surface of the wafer 1 can be considered. The contents of each index value are as already described based on FIG.
In addition, as a method for selecting one representative value, for example, a median value, a minimum value, or a maximum value may be selected from a plurality of the index values. The attached matter affects the direction in which the contour protrudes beyond the original end face shape with respect to the projected image. When deposits are present near the tip of the end face of the wafer 1, generally, the chamfer width k tends to be larger than the original (when no deposit is present) and the chamfer radius rm tends to be smaller than the original. . On the other hand, when deposits exist in the vicinity of the boundary position between the end surface of the wafer 1 and the front and back surfaces, the chamfer width k tends to be smaller than the original and the chamfer radius rm tends to be larger than the original. For this reason, in a situation where the position where the deposit can be attached can be specified to some extent, the representative value is set to the minimum value or the representative value is set according to the type of index value (chamfer width k, chamfer radius rm, etc.). The maximum value is considered. Further, when calculating three or more index values, it is conceivable that the representative value is the median value regardless of the type of the index value.

In addition, when calculating three or more index values, an average value (an example of an aggregate value) for a predetermined number is calculated in order from the smallest or largest of the index values, and the average value is measured. It can also be considered.
For example, when three index values are calculated and the index value is the chamfer width k, it is conceivable that the average value of two of the three index values in order from the smallest one is used as the measured value. Similarly, when three index values are calculated and the index value is a chamfer radius rm, it is conceivable that an average value for two of the three index values in order from the largest one is used as a measured value. An average value of all the calculated index values may be calculated as a measured value.

この（ｂ２）式における上限側のしきい値「２２．５度」は，４５度ずれた隣の基準支持位置との境界となる角度である。この上限制限を満たすことにより，各基準支持位置に関する測定において，他の基準支持位置に関する測定部位（面取り部）と重複した測定部位について測定することを回避できる。
また，ウェーハ１の半径ｒ（例えば，設計上の半径）が１５０［ｍｍ］，ウェーハ１の面取り幅ｋ（例えば，設計上の面取り幅）が０．３５［ｍｍ］である場合，δは３．９以上に予め設定されている。
なお，基準支持位置で支持されたウェーハ１の測定部位（端面）の表面形状とその近傍部の表面形状との差異が測定誤差となることを回避するためには，角度を表す設定値δがより小さいことが望ましい。
そこで，前記設定値δが次の（ｂ３）式を満たすことが考えられる。

例えば，ウェーハ１の半径ｒ（例えば，設計上の半径）が１５０［ｍｍ］，ウェーハ１の面取り幅ｋ（例えば，設計上の面取り幅）が０．３５［ｍｍ］である場合，δを４．０（≒３．９）に予め設定しておく。
また，前述したように，半径ｒが１５０［ｍｍ］程度，面取り幅ｋが０．１０［ｍｍ］程度以上であるというウェーハ１の実情を（ｂ２）式に適用すると，ウェーハ１については，δ１及びδ２が，それぞれ２°以上２２．５°以下の範囲であることが実用的である。 Next, the procedure of the shape measurement process (shape measurement method) using the shape measurement apparatus X will be described with reference to the flowchart shown in FIG. S1, S2,... Shown below represent identification codes of processing procedures (steps).
First, the control device 10 executes an initial setting process such as initialization of a predetermined counter variable i (i = 1) (S1). At this time, the point light source 2 is turned on and light projection to the wafer 1 is started.
Next, the control device 10 controls the rotation support mechanism 9 so that the wafer 1 has an i-th reference support angle ψ (i) whose support angle (rotation angle of the rotation support mechanism 9) is predetermined. The support position (rotation angle) of the wafer 1 is set so as to be supported at a position rotated by −δ [degrees] with respect to the support position (i-th reference support position) (S2).
Here, the reference support positions are seven positions (first position) except for the case where the notch or the like of the eight positions where the support angle (rotation angle) of the wafer 1 by the rotation support mechanism 9 is shifted by 45 degrees is the measurement position. ˜7th reference support position).
Further, δ is a set value (predetermined set value) representing an angle, and is a set value that satisfies the following equation (b2).

The threshold value “22.5 degrees” on the upper limit side in the equation (b2) is an angle that becomes a boundary with the adjacent reference support position shifted by 45 degrees. By satisfying this upper limit, it is possible to avoid measuring a measurement site that overlaps a measurement site (chamfered portion) related to another reference support position in the measurement related to each reference support position.
Further, when the radius r (for example, design radius) of the wafer 1 is 150 [mm] and the chamfer width k (for example, design chamfer width) of the wafer 1 is 0.35 [mm], δ is 3 .9 or higher.
In order to avoid the difference between the surface shape of the measurement site (end surface) of the wafer 1 supported at the reference support position and the surface shape of the vicinity thereof from being a measurement error, a set value δ representing an angle is set. It is desirable to be smaller.
Therefore, it is conceivable that the set value δ satisfies the following equation (b3).

For example, when the radius r of the wafer 1 (for example, a design radius) is 150 [mm] and the chamfer width k (for example, the design chamfer width) of the wafer 1 is 0.35 [mm], δ is 4 Is set in advance to 0.0 (≈3.9).
Further, as described above, when the actual situation of the wafer 1 that the radius r is about 150 [mm] and the chamfer width k is about 0.10 [mm] or more is applied to the equation (b2), And δ2 are practically in the range of 2 ° or more and 22.5 ° or less, respectively.

Subsequently, in a state where the wafer 1 is supported at the position of the i-th reference support angle ψ (i) −δ [degrees], a projected image of the end surface of the wafer 1 is taken by the image sensor 7, and further, the control device 10. However, by controlling the image processing device 8, the captured image (image data) is captured and stored in a predetermined storage unit (memory or the like provided in the image processing device 8) (S3).
Furthermore, according to the control command of the control device 10, the image processing device 8 (an example of the predetermined calculation means) is predetermined based on the captured image (image of the projected image of the end portion of the wafer 1) captured in step S3. By executing the image processing, an index value of the end face shape of the wafer 1 is calculated, and the calculated value is stored in a predetermined storage unit (memory or the like provided in the control device 10) (S4).
For example, the image processing apparatus 8 calculates the chamfer width k of the end surface (chamfered portion) of the wafer 1 as an index value in step S4.
Note that a method for calculating the chamfer width k based on the projected image of the wafer 1 is well known in the technical field of the shape measurement of the wafer 1, and thus the description thereof is omitted here.

Next, the control device 10 controls the rotation support mechanism 9 so that the wafer 1 has an i-th reference support angle ψ (i) whose support angle (rotation angle of the rotation support mechanism 9) is predetermined. The support position (rotation angle) of the wafer 1 is set so as to be supported at the support position (i-th reference support position) (S5). That is, the wafer 1 is rotated by + δ [degrees] from the state of steps S3 and S4.
Subsequently, in a state where the wafer 1 is supported at the i-th reference support angle ψ (i), the control device 10 and the image processing device 8 perform the same processing as steps S3 and S4 described above (S6, S7). .
Thus, the index value (here, the chamfering width k of the end surface (chamfered portion) of the wafer 1) based on the projection image obtained in a state where the wafer 1 is supported at the i-th reference support angle ψ (i) is obtained. Calculated and stored.
Further, the control device 10 controls the rotation support mechanism 9 so that the wafer 1 has an i-th reference support angle ψ (i) + δ [with a predetermined support angle (the rotation angle of the rotation support mechanism 9). The support position (rotation angle) of the wafer 1 is set so as to be supported at the support position of [degree] (S8). That is, the wafer 1 is rotated by + δ [degrees] from the state of steps S6 and S7.
Subsequently, in a state where the wafer 1 is supported at an angle of the i-th reference support angle ψ (i) + δ [degrees], the control device 10 and the image processing device 8 execute the same processing as steps S3 and S4 described above. (S9, S10).
Thereby, the index value (here, the end face (chamfered portion) of the wafer 1) based on the projection image obtained in a state where the wafer 1 is supported at an angle of the i-th reference support angle ψ (i) + δ [degree]. Chamfer width k) is calculated and stored.

The steps S2, S3, S5, S6, S8, and S9 described above are performed at the support position (hereinafter referred to as the first position) obtained by rotating the wafer 1 by + δ degrees with respect to the i-th reference support position by the rotation support mechanism 9. Including the first support position, the second support position, and the i-th reference support position in a range from a support position) to a support position rotated by −δ degrees (hereinafter referred to as a second support position). It is a process of supporting at three support positions, capturing a projected image of the end face of the wafer 1 supported at each of the support positions by an image sensor 7 (an example of an image capturing means), and recording the image data in a predetermined storage means. , Is an example of the rotation / imaging process. The control device 10 is an example of the rotation control unit and the imaging control unit.
Further, in the steps S4, S7, and S10 described above, predetermined image processing is performed by a processor (calculation means) included in the image processing device 8 for each of the plurality of projection images obtained by the rotation / imaging process. This is a step of calculating an index value of the end face shape of the wafer 1 by executing, and is an example of the index value calculating step.

Next, according to a predetermined rule, the control device 10 selects one representative value based on a plurality of the index values (here, the chamfer width k) obtained by the steps S2 to S10 or one aggregation. By calculating the value, the representative value or the aggregated value is derived (selected or calculated) as a measured value of the end face shape of the wafer 1 corresponding to the i-th reference support position, and the measured value is a predetermined output means. (S11, an example of the measurement value deriving step and the same means).
For example, as described above, the control device 10 selects the minimum value or the median value from the three chamfering widths k (index values), and outputs the measured values as measured values. The average value (an example of an aggregate value) of two values is calculated in order from the smallest value), and the process of outputting it as a measurement value is executed. Note that the measurement value can be output in various ways, such as display of the measurement value on the display device, transmission of the measurement value to another device via the communication means, and writing of the measurement value to the storage means.

Next, the control device 10 counts up (+1) the counter variable i (S12), and determines whether or not the counter variable exceeds a predetermined set value M (S13). When the control device 10 determines that (i> M) is not satisfied, it returns the process to step S2 described above, repeats the processing of steps S2 to S13 again, and determines that (i> M) is satisfied. Terminates the process.
For example, in the measurement of the wafer 1, M is 7, and the first to seventh reference support angles ψ (1) to ψ (7) are set at an angle set by 45 degrees (for example, 0 degrees, 45 degrees, 90 degrees, 135 degrees,..., 270 degrees, 315 degrees).
As a result, in the shape measurement of the wafer 1 using the shape measuring apparatus X, the set value δ (corresponding to δ1 and δ2) representing the angle satisfies the equation (b2) (that is, the equation (b1) is also satisfied. ), For each of the seven reference support positions (i = 1 to 7) of the eight support positions where the support angle of the wafer 1 by the rotation support mechanism 9 is shifted by 45 degrees (steps S2 to S11) (Corresponding to the imaging step, the index value calculating step, and the measured value deriving step). Depending on the measurement requirements, steps S2 to SS11 are performed only for 6 or 5 reference support positions (support positions of a plurality of patterns other than 7 patterns) out of 8 support positions where the support angle of the wafer 1 is shifted by 45 degrees. In some cases, these steps are performed. In addition, the steps S2 to SS11 may be executed with a plurality of support positions where the support angle of the wafer 1 is shifted by an angle other than 45 degrees (for example, 15 degrees) as the reference support position.

When measuring the shape of the end face of the disc-shaped wafer 1 based on the projected image by measuring the shape of the wafer 1 using the shape measuring apparatus X described above, it is not affected by the deposits present on the end face. The correct shape measurement can be performed.
In addition, the effects described above are obtained by changing the shape of the end face (end face) of the disk-shaped measurement object (aluminum substrate for hard disk, glass substrate, etc.) other than the wafer 1 that has been chamfered. Even in the case of measuring based on the projected image, the same can be obtained.
Further, the absolute values (δ) of + δ and −δ, which are rotation angles with respect to the reference support position in the above-described embodiment, do not necessarily have to be the same value, and + δ and −δ are replaced with + δ1 and −δ2. The δ1 and δ2 may satisfy any one of the expressions (b1) to (b3). The set values δ1 and δ2 representing the angles may be δ1 = δ2 or δ1 ≠ δ2.
Further, in the above-described embodiment, the projected image of the end portion of the wafer 1 at each of the three support positions, that is, the reference support position and each support position rotated by + δ degrees and −δ degrees with respect to the reference support position. An example of performing imaging and calculating the index value has been shown, but two or more support positions rotated + δ degrees and −δ degrees with respect to the reference support position, or four or more including the two support positions Regarding the support position, it is also conceivable to perform the imaging of the projected image of the edge of the wafer 1 and the calculation of the index value.
For example, in the range from the support position where the wafer 1 is rotated + δ degrees relative to the reference support position to the support position where the wafer 1 is rotated −δ degrees, the support positions of ± δ degrees and the angle ranges thereof are set to be equal to a plurality of angles. For each of the divided support positions at each angle, it is conceivable to take a projected image of the edge of the wafer 1 and calculate the index value.

Further, it is conceivable that the control device 10 or a computer (not shown) that can communicate with the control device 10 has a function of setting δ by executing a predetermined program.
For example, the control device 10 may be a keyboard for inputting information on the width of the wafer 1 in the radial direction of the shape measurement target area (hereinafter referred to as the measurement target width) and the radius r of the wafer 1. An operation input unit and a communication unit (an example of the measurement target width information input unit) with an external device are provided, and a processor included in the control device 10 calculates δ based on the input information about the measurement target width and radius. It is conceivable to execute a process of calculating and storing (setting) the calculated δ in the storage unit (an example of the set angle calculating means).
Here, the measurement target width is usually a chamfer width k, and in this case, the control device 10 determines the input chamfer width k and radius r, for example, δ = cos ⁻¹ ((r−k) / r. ) Is calculated by applying it to the formula (corresponding to the formula (b3)).
Thereby, δ suitable for the shape of the wafer 1 to be measured can be easily set.

  The present invention can be used mainly for measuring the shape of an end face of a disk-shaped measuring object such as an aluminum substrate or a glass substrate for a semiconductor wafer or other hard disk.

1 is a schematic plan view of a shape measuring device X according to an embodiment of the present invention. The schematic side view of the shape measuring apparatus X. The figure showing an example of the projection image of the end surface of a semiconductor wafer. The figure for demonstrating an example of the index value of the edge profile (end surface shape) of a semiconductor wafer. The figure showing the relationship between the support angle in a semiconductor wafer, and the position of an edge part. The flowchart showing the procedure of the shape measurement process by the shape measuring apparatus X.

Explanation of symbols

X: shape measuring device 1: wafer 2: point light source 3: collimator lens 4: first lens 5: aperture 6: second lens 7: image sensor 8: image processing device 9: rotation support mechanism 10: control device

Claims (8)

Projecting means for projecting light from a direction substantially parallel to the front and back surfaces of the semiconductor wafer with respect to the chamfered end portion of the disk-shaped semiconductor wafer, and a direction of the semiconductor wafer from the direction facing the projecting direction. And a shape measuring device for measuring the shape of the end face of the semiconductor wafer based on the projected image,
A rotation support mechanism for rotatably supporting the semiconductor wafer in its circumferential direction;
The rotation support mechanism rotates the semiconductor wafer by a predetermined first set angle with respect to a predetermined reference support position from a predetermined first set position opposite to the first set angle. Rotation control means for supporting at two or more support positions including the first support position and the second support position in a range up to a second support position rotated by a set angle of 2;
Imaging control means for imaging the projected image of the end face of the semiconductor wafer supported by the rotation control means at each of the two or more supporting positions by the imaging means;
Index value calculating means for calculating an index value of the end face shape by executing predetermined image processing for each of the plurality of projection images obtained by the processing of the imaging control means;
The semiconductor corresponding to the reference support position by selecting one representative value or calculating one aggregate value based on a plurality of the index values calculated by the index value calculating means according to a predetermined rule. Measurement value deriving means for deriving a measurement value of the shape of the end face of the wafer;
Comprising
The chamfer width k of the end face of the semiconductor wafer is 0.1 mm to 1.0 mm, the ratio of the chamfer width k to the radius r of the semiconductor wafer is 0.0067 or less, and the first set angle is + δ1, the first When the set angle of 2 is −δ2, the chamfered portion in the projected image of the end face of the semiconductor wafer supported at the reference support position is obtained by the processing of the imaging control unit. A shape measuring device having a range of 2 ° or more and 6.6 ° or less determined so as to deviate from a region projected as a chamfered portion in each of a plurality of projected images . The rotation control unit supports the semiconductor wafer at the three or more support positions including the reference support position, the first support position, and the second support position by the rotation support mechanism;
The shape measuring apparatus according to claim 1, wherein the imaging control unit causes the imaging unit to capture a projected image of an end face of the semiconductor wafer supported at each of the three or more support positions by the rotation control unit.   The predetermined rule is a rule for selecting a median, minimum value or maximum value from a plurality of the index values, or a predetermined number in order from the smallest or the largest of the plurality of index values. The shape measuring device according to claim 1, wherein the shape measuring device is any one of rules for calculating an average value of.   The shape measuring apparatus according to claim 1, wherein the index value is any one of a chamfer width, a chamfer angle, and a chamfer radius of an end surface of the semiconductor wafer. Light is projected by light projecting means from directions substantially parallel to the front and back surfaces of the semiconductor wafer to the chamfered end portion of the disk-shaped semiconductor wafer, and from the direction opposite to the light projecting direction by the imaging means. A shape measuring method for capturing a projected image of the end face of the semiconductor wafer and measuring the shape of the end face of the semiconductor wafer based on the projected image,
The semiconductor wafer is rotated from the first support position by a predetermined first set angle with respect to a predetermined reference support position by a rotation support mechanism that rotatably supports the semiconductor wafer in the circumferential direction. Two or more support positions including the first support position and the second support position in a range up to a second support position rotated by a predetermined second set angle opposite in polarity to the set angle. A rotation / imaging process in which a projected image of the end face of the semiconductor wafer supported at each of the support positions is captured by the imaging unit and the imaging data is recorded in a predetermined storage unit;
An index value calculation step for calculating an index value of the end face shape by executing predetermined image processing by a predetermined calculation means for each of the plurality of projection images obtained by the rotation and imaging step;
The semiconductor corresponding to the reference support position by selecting one representative value or calculating one aggregate value based on a plurality of the index values calculated by the index value calculating step according to a predetermined rule. A measurement value deriving step in which processing for deriving a measurement value of the shape of the end face of the wafer is executed by a predetermined computing means;
And
The chamfer width k of the end face of the semiconductor wafer is 0.1 mm to 1.0 mm, the ratio of the chamfer width k to the radius r of the semiconductor wafer is 0.0067 or less, and the first set angle is + δ1, the first When the set angle of 2 is −δ2, the chamfered portion in the projected image of the end face of the semiconductor wafer supported at the reference support position is obtained by the processing of the imaging control unit. A shape measuring method characterized by being in a range of 2 ° or more and 6.6 ° or less determined so as to deviate from a region projected as a chamfer in each of a plurality of projected images .   The predetermined rule is a rule for selecting a median, minimum value or maximum value from a plurality of the index values, or a predetermined number in order from the smallest or the largest of the plurality of index values. The shape measuring method according to claim 5, wherein the shape measuring method is any one of rules for calculating an average value.   In the rotation / imaging process, the rotation support mechanism supports the semiconductor wafer at three or more support positions including the reference support position, the first support position, and the second support position. The shape measuring method according to claim 5, wherein a projected image of the end face of the semiconductor wafer supported at each of the above support positions is picked up by the image pickup means.   The shape measurement method according to claim 5, wherein the index value is any one of a chamfer width, a chamfer angle, and a chamfer radius of an end surface of the semiconductor wafer.

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