JP2009246027A - Apparatus and method of positioning wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus of positioning a wafer capable of correctly measuring an amount of eccentricity and a notch angle without causing a slack of an outer peripheral end of a wafer, cracks on an edge, chipping or the like. <P>SOLUTION: The apparatus of positioning a wafer includes a support table 4 for holding a thin circular wafer 3 having a notch 3b at an edge 3a along a circumference while aligning the center of the wafer 3 with a position of a rotating axis for turning it, a reflective laser sensor 1 for radiating laser light 2 to the edge 3a of the wafer 3 and capturing its reflected light to detect the position of the edge 3a and the position of the notch 3, and a computation device 11 for calculating the amount of eccentricity and an eccentric direction of the wafer 3 and a rotation angle position of the notch 3b from the position data of the sensor 1. An outline of the support table 4 is larger than an outer diameter of the wafer 3. The whole surface of the wafer 3 can be mounted within a range of the support table 4. The apparatus is thus characterized. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention moves a center point of a semiconductor wafer (hereinafter referred to as “wafer”) to the rotation center of a support table, and aligns the notch of the wafer in a predetermined direction to position the wafer. The present invention relates to a positioning detection apparatus and a positioning method.

  Of the wafer manufacturing and inspection processes, for example, processes that require positional information of the wafer, such as wafer processing and various inspections, it is necessary to accurately place the wafer on each apparatus. The wafer positioning detection apparatus according to the present invention is an apparatus for accurately arranging the position of the center point of the wafer and the notch position of the edge portion of the wafer at a predetermined position as a pre-stage operation of the above process. The wafer positioning method according to the method is a method of transporting a wafer whose position has been corrected using the detection device to a process that requires the position information.

  Conventional wafer positioning detection devices are equipped with a circular table called a support table large enough to place a wafer on the rotation axis, and the support table is rotated around the rotation axis together with the wafer, from the rotation axis to the wafer outer circle. The eccentric radius and the rotation angle of the wafer were detected by a displacement sensor and an angle sensor, and the amount of eccentricity at the center of the wafer and the position of the notch portion were calculated from the detected data by an arithmetic unit. Based on this information, in the positioning detection device, the wafer is moved in the X-axis and Y-axis directions on the support table by a dedicated moving device, and further rotated to move the notch to a predetermined angular position, thereby moving the wafer to a predetermined position. It was placed at a position and angle.

  For example, Patent Documents 1 and 2 disclose wafer positioning detection devices. In conventional wafer positioning and detection devices such as these devices, the position of the edge and notch of the wafer can be detected by measuring the amount of light transmitted and received through the wafer edge by an optical sensor, This was done by reading the image from the top with a camera.

  At present, a method using an optical sensor is frequently used because of cost, and in this case, the wafer support table is implemented with a configuration smaller than the wafer diameter. In the case of an image processing method using a camera, the wafer edge can be measured by illuminating from above even if the table diameter is larger. However, in the case of a method using an optical sensor, it is described in Patent Document 1. This is because the table diameter is made smaller and the above-described method is used to irradiate the above-mentioned transmitted light onto the wafer edge portion protruding into the air, and it is necessary to make the support table smaller than the wafer diameter.

JP-A-5-343501 Japanese Patent Laid-Open No. 2003-152055

However, when the back surface of the wafer is ground and its thickness is reduced to, for example, 100 μm or less, the conventional positioning detection device causes the outer peripheral edge of the wafer to come off from the periphery of the support table, and accurate position measurement is performed. It was difficult. Further, if the measurement is performed in a state where the outer peripheral edge of the wafer is bent, the wafer may be damaged such as cracking or chipping of the edge.
Further, in the conventional wafer positioning method, the wafer is moved in the X-axis and Y-axis directions on the support table by the dedicated moving device based on the detection information, and the eccentric amount of the wafer center is corrected. Positioning took a long time.

  The present invention solves the above-mentioned problems and provides a wafer positioning detection device capable of accurately measuring an eccentricity deviation and a notch angle without causing any cracking or chipping of the outer peripheral edge of the wafer or cracks. It is an object of the present invention to provide a wafer positioning method capable of shortening the required time.

In order to solve the above-mentioned problem, the invention of claim 1 is a support for rotating a thin disk-shaped wafer having a notch portion at the outer peripheral edge portion while keeping the center of the wafer and the position of the rotation axis aligned. From the table, a displacement sensor that irradiates the edge portion of the wafer with the laser beam, captures the reflected light and detects the position of the edge portion and the position of the notch portion, and the position data of the displacement sensor. An arithmetic unit for calculating the amount of eccentricity of the wafer, the direction of eccentricity, and the rotational angle position of the notch portion, and the outer shape of the support table is larger than the outer diameter of the wafer, and the entire surface of the wafer is within the range of the support table. It can be mounted. Accordingly, it is possible to prevent the occurrence of a crack at the outer peripheral edge of the wafer, a crack at the edge portion, and a chip, and accurately measure the eccentric amount at the wafer center, the eccentric direction, and the rotation angle position of the notch.
The invention of claim 2 further includes an air blow nozzle for cleaning the edge portion, and a chamber for preventing the airflow from the air blow nozzle from being scattered outside. As a result, the edge portion of the wafer to be measured and the periphery of the positioning detection device can always be kept clean.
According to a third aspect of the present invention, there is provided, from the arithmetic device, such that the notch portion of the wafer, which has been subjected to the detection and calculation by the wafer positioning detection device according to the first or second aspect, has a predetermined rotational angle position. The support table is rotated based on the obtained rotation angle position of the notch portion, and the suction pad is aligned with the wafer center based on the eccentric amount and the eccentric direction of the wafer obtained from the arithmetic unit. The wafer is sucked and transferred to the next process. Thus, the wafer can be positioned at a predetermined position and angle in a short time.

  As described above, the present invention prevents the occurrence of cracks and chipping at the outer peripheral edge of the wafer, the occurrence of cracks and chipping, and accurately measures the eccentricity of the wafer center and the rotation angle position of the notch, thereby predetermining the wafer. Can be positioned in a short time and transferred to the next process.

Hereinafter, an embodiment of a wafer positioning detection apparatus and positioning method of the present invention will be described with reference to the drawings.
1 and 2 are schematic views of a wafer positioning detection apparatus according to the present embodiment. Reference numeral 1 denotes a reflective laser sensor body, reference numeral 2 denotes parallel laser light, reference numeral 3 denotes a wafer, and reference numeral 4 denotes a support table.

  The main part of the wafer 3 positioning detection device of the present embodiment includes a support table 4, a reflective laser sensor 1, and an arithmetic device 11.

  As shown in FIG. 1, the support table 4 is disposed on a rotating plate 9 attached to the tip of the rotating shaft 8 perpendicularly to the rotating shaft 8, and the wafer 3 is placed on the support table 4. Fixed by vacuum suction. The support table 4 is configured with an outer dimension larger than the outer diameter of the wafer 3 so that the edge portion 3 a of the mounted wafer 3 does not protrude from the outer peripheral end of the support table 4.

  As shown in FIG. 1, the reflection type laser sensor 1 is disposed above the outer peripheral portion of the support table 4. As shown in FIG. 2, the parallel laser light 2 is emitted from the light projecting portion to the edge portion 3a of the wafer 3. Then, the reflected light is taken into the sensor 1 from the light receiving portion, and the edge position of the wafer 3 is detected. For this reason, the reflection type laser sensor 1 is arranged in a direction in which the irradiation straight line drawn by the parallel laser light 2 intersects the outer circumference circle of the wafer perpendicularly.

In the wafer positioning detection apparatus having the above-described configuration, the cleaning air nozzle 5 is disposed above the support table 4, and the nozzle tip of the air nozzle 5 is directed to the edge detection position.
Further, a cup-shaped chamber 6 for preventing scattering of cleaning air from the air nozzle 5 is installed around the support table 4.

  Further, a robot hand 7 serving as a transfer device for the wafer 3 is disposed above the wafer positioning detection device having the above-described configuration. The robot hand 7 is provided with a pad 10 for attracting and fixing the wafer 3 at the lower end of the robot hand 7. However, in addition to the robot hand 7 that places the wafer 3 on the support table 4, another robot hand 7 that sucks and transports the wafer 3 after the arithmetic processing is provided.

Next, the function of each part will be described.
The positioning of the wafer 3 is performed using the positioning detection apparatus of the present invention at a stage before the positional information of the wafer 3 is transferred to a process that requires it as described above. First, the wafer 3 attracted and fixed to the pad 10 by the robot hand 7 is transferred from the previous process and placed on the support table 4. At this stage, position information such as the eccentricity of the center of the wafer 3 has not been measured, and the robot hand 7 can only place the center position of the wafer 3 in the vicinity of the rotation axis of the support table 4. That is, the center of the wafer 3 is basically eccentric with respect to the rotation axis of the support table 4.
This amount of eccentricity has a different direction and dimension for each wafer 3. The notch position of the edge of the wafer 3 is also placed on the support table 4 at a different angular position every time.

  Therefore, the eccentricity amount and the notch angle position of the wafer 3 are accurately detected by the positioning detection device, and then the wafer 3 positioned at the predetermined center position and notch angle position by the robot hand 7 based on the information. Need to be transported. Hereinafter, the operations of the detection stage and the positioning stage will be described in order (see FIG. 4).

First, the operation at the detection stage of each information of the wafer 3 will be described.
The wafer 3 is placed on the support table by the transfer robot hand 7 (S1), and the support table rotates (S2). The reflective laser sensor 1 having the above configuration irradiates the object to be measured with the parallel laser light 2 emitted from the light projecting unit as shown in FIGS. 1 to 3 and captures the reflected light beam on the light receiving unit. Edge positions are detected (S3). This is necessary to detect the amount of displacement of the edge portion 3a during rotation due to the eccentricity of the wafer 3 and the notch angle position. Specifically, the light amount of the reflected light is evaluated by the arithmetic unit 11 to detect which part of the parallel laser light 2 is reflected from the surface of the wafer 3. 3 is detected until necessary data is obtained over the entire circumference of the wafer 3 (S4).

  The edge position data and the data of the shaft rotation encoder (not shown) are processed by the arithmetic unit 11 to obtain the eccentric amount of the wafer 3 and the angular position of the notch (S5). Although this specific calculation method is not a feature of the present invention, various methods have been conventionally known.

  An outline method will be described with reference to FIG. By analyzing the amount of reflected light that returns to the reflective laser sensor 1, measurement data (the R dimension in FIG. 3B) about the position of the edge portion 3a and the position of the notch portion 3b is obtained. As for the position of the edge portion 3a, the R dimension itself indicates the position of the edge, and the arithmetic unit 11 analyzes the change in the R dimension data at each rotation position of the wafer 3 to determine the eccentric amount of the center of the wafer. obtain.

  The position of the notch portion 3b is obtained from R dimension data and wafer rotation angle data. That is, the arithmetic unit 11 analyzes the change in the R dimension at each rotation angle of the wafer rotation from the acquired R dimension data and wafer rotation angle data, and identifies the rotation angle having a sudden change as the notch position. The angular position of the notch portion 3b is obtained.

Next, the operation of the wafer 3 positioning stage will be described.
Based on the angular position of the notch of the wafer 3 obtained by the arithmetic unit 11, first, the support table 4 is rotated and the notch position is stopped according to a predetermined position in the conveyance to the next process (S6).
Next, the arithmetic unit 11 obtains the eccentric amount and the eccentric direction of the center of the wafer 3 at the stop position, and based on these, the robot hand 7 adjusts the predetermined position to the central position of the wafer 3 in the X-axis direction and the Y-direction. It moves in the axial direction (direction perpendicular to the paper surface) (S6), and finally descends in the Z-axis direction to attract the wafer 3 by the pad 10. After that, the robot hand 7 sucks and moves up while maintaining a predetermined position angle of the fixed wafer 3 (S7), and carries to the next process.

In the above configuration, air is blown from the air nozzle 5 before irradiating the laser beam, and dust and water droplets on the edge portion 3a of the wafer 3 and the outer peripheral portion of the support table 4 are blown away for cleaning. If dust or water droplets adhere to these portions, the reflected light of the reflective laser sensor 1 is scattered, and the edge portion 3a of the wafer 3 may not be detected accurately.
Further, the air flow is prevented from being scattered around the cup-shaped chamber 6 disposed around the support table 4 having the above-described configuration.

  Here, in the wafer edge position detection and notch position detection apparatus using the conventional transmission type laser position detector, there was a risk of defects due to the drooping of the wafer edge, cracks, chipping, etc. as described above. Regardless, the reason why the system using the support table and the reflection type laser sensor having an outer shape larger than the outer diameter of the wafer as in the present invention has not been conceived will be described.

  Conventionally, the reflection type laser sensor itself has been commercially available, and it seems that the use of this in the present invention has been naturally considered. However, the reflection type laser sensor was initially worried about detection of the edge portion 3a. That is, the edge portion 3a has a surface angle that is not stable as compared with the flat portion of the base of the main body. Therefore, when the reflected light of the laser does not return firmly to the light receiving portion (when the amount of light is insufficient), it cannot be recognized as the edge position. There was a fear. Further, if there is an object not to be measured like the current support table in the vicinity of the edge, there is a possibility that the reflected light from the object is erroneously detected as being from the edge portion 3a.

  On the other hand, since the transmission type laser sensor is a method for detecting the laser light reaching the light receiving portion, the possibility of erroneous detection of the edge portion 3a is low, and it was regarded as a technology on the safe side at that time. For this reason, the defect such as the drooping at the edge of the wafer has a background that a transmission type laser sensor has been used. To put it simply, the reflection type was afraid of false detection and could not be used very much.

  The above problems are caused by the performance of the reflective laser sensor itself, and even after these performances are improved and the edge position can be sufficiently detected as in the present case, the above-mentioned experience will try to escape to the safe side. It is thought that consciousness to work worked.

  The present invention breaks the preconception, proves by experiment that the performance of the reflection type laser sensor has sufficient accuracy required for edge detection in this case, and adopting this proves a problem. This makes it possible to eliminate problems such as defects, cracks, chipping, etc. caused by dripping at the edge of the wafer.

  In the above configuration, the reflection type laser sensor is used as the displacement sensor. However, the present invention is not limited to this, and other reflection type optical displacement sensors may be used.

  As described above, in the present embodiment, it is possible to configure the outer shape of the support table to be larger than the outer diameter of the wafer by using the reflection type laser sensor as the edge detection means of the wafer, and to reduce the edge of the wafer. In addition to performing accurate edge position detection, cracking and chipping of the edge portion can be prevented.

  In the present embodiment, the wafer positioning detection device performs only notch angle alignment and does not perform eccentricity correction. Instead, the transfer robot hand is moved to a predetermined position based on the amount of eccentricity information obtained by the positioning detection device, and the wafer is attracted and fixed. The amount correction operation can be omitted, and the wafer can be positioned in a shorter time.

It is a schematic diagram of the wafer positioning detection apparatus showing an embodiment of the present invention. It is a schematic diagram which shows the light projection / reception system of a reflection type laser sensor same as the above. It is a figure which shows the detail of the detection part of the wafer positioning detection apparatus of this embodiment, (a) Top view, (b) shows a front view. It is a flowchart of the wafer positioning operation | movement of the wafer positioning detection apparatus of this embodiment. It is a schematic diagram for demonstrating the detection method of the edge position of a wafer and a notch position by a reflection type laser sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reflection type laser sensor 2 Parallel laser beam 3 Wafer 3a Edge part 3b Notch part 4 Support table 5 Air nozzle 6 Cup-shaped chamber 7 Robot hand 8 Rotating shaft 9 Turntable 10 Pad 11 Computing device

Claims (3)

A thin disk-shaped wafer having a notch portion at the outer peripheral edge portion, holding the wafer in alignment with the center of the wafer and the position of the rotation axis, and a rotating support table;
A displacement sensor that irradiates the edge portion of the wafer with the laser light and captures the reflected light to detect the position of the edge portion and the position of the notch portion;
An arithmetic unit that calculates the amount of eccentricity of the wafer, the direction of eccentricity, and the rotational angle position of the notch from the position data of the displacement sensor,
An apparatus for detecting and positioning a wafer, wherein an outer diameter of the support table is larger than an outer diameter of the wafer, and the entire surface of the wafer can be placed within the range of the support table.   2. The wafer positioning detection according to claim 1, further comprising: an air blow nozzle for cleaning the edge portion; and a chamber for preventing the airflow from the air blow nozzle from being scattered outside. 3. apparatus. The notch portion obtained from the arithmetic device is set so that the notch portion of the wafer subjected to the detection and calculation by the wafer positioning detection device according to claim 1 or 2 has a predetermined rotation angle position. Based on the rotation angle position, the support table is rotated,
A wafer positioning method comprising: adsorbing the wafer with the suction pad aligned with the center of the wafer based on an eccentric amount and an eccentric direction of the wafer obtained from the arithmetic unit, and transporting the wafer to the next process.

Images