JP4249813B2 - Identifier marking apparatus and marking method for semiconductor wafer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a laser beam identifier on a wafer surface in a semiconductor wafer manufacturing process for quality control of a semiconductor wafer in a device process (a process subsequent to the semiconductor wafer manufacturing process, for example, a pattern baking process, a chip bonding process, etc.). The present invention relates to an identifier marking apparatus for marking a semiconductor wafer and a marking method thereof.
[0002]
[Prior art]
Generally, a semiconductor wafer is manufactured through the following steps.
(1) The ingot is cut to obtain a sliced wafer, and then washed.
(2) The sliced wafer is cleaned after lapping.
(3) Clean the wrapped wafer after etching.
(4) Mirror polishing and cleaning the etched wafer.
(5) Dry the cleaned wafer.
[0003]
Furthermore, a step of marking an identifier made of a character or a barcode for identifying the type of the semiconductor wafer on the wafer surface using laser light, and a step of inspecting the stamped identifier may be added as appropriate. . This is because the stamped identifier is read in the device process so that a semiconductor wafer suitable for each device process can be confirmed.
[0004]
By the way, in order to ensure reading in the device process, this identifier must satisfy a depth standard of, for example, 70 ± 20 μm, and the depth in the finish of the semiconductor wafer manufacturing process must be fixed. Therefore, if the marking of the identifier is performed after the mirror polishing process, it is desirable to perform the marking before etching or lapping because the marking dust causes generation of particles.
[0005]
However, when this identifier is engraved on the wrapped wafer, there is a problem that depending on the etching solution used in the subsequent etching, the marking waste generated by the marking of the identifier can cause a stain. In addition, if the identifier is engraved before the lapping process with a large machining allowance, it is difficult to set the depth of the identifier in the mirror polishing finish, and not only the standards required from the device process cannot be observed. The identifier itself may even disappear.
[0006]
As a method for solving these problems, a sliced wafer is formed on the basis of a thickness measurement value at the center of a sliced wafer that has been conventionally measured for another purpose of making the thickness after lapping constant. Some are classified into a plurality of groups, and each group is stamped with an identifier having a depth in consideration of a lapping allowance. According to this method, the marking debris generated by the marking of the identifier is removed by cleaning after lapping, so that it cannot be stained by etching.
[0007]
On the other hand, the inspection of the stamped identifier is also important in order to ensure reading of the identifier in the device process. Therefore, detection of defects such as misalignment, distortion, bent characters, etc. of the stamped identifier is performed by, for example, extracting the wafer after the identifier is stamped by the stamping device, and monitoring the stamped portion of the identifier on the extracted wafer. This was done by enlarging and visually inspecting the characters and barcodes of the identifiers.
[0008]
[Problems to be solved by the invention]
First, in the conventional engraving process, even if sliced wafers are classified according to their thicknesses, there is a limit to the number of classification groups, and even sliced wafers classified in the same group have a thickness. When there is a large variation, there is a problem that an identifier satisfying the standard required from the device process cannot be engraved.
[0009]
In addition, since the classification process must be provided in the process before the marking process, the number of classification processes increases, and the sliced wafers cannot be processed in the slice order, which is inefficient.
[0010]
On the other hand, in the inspection process of the identifier, in the inspection in which the image displayed on the monitor is visually checked after the identifier is engraved, an inspection error of the operator occurs, and it is difficult to perform an accurate inspection. Moreover, for the reason of manufacturing efficiency, the extraction frequency can be performed only about one for every 100 semiconductor wafers manufactured, and it is difficult to inspect all manufactured semiconductor wafers by this method. It was.
[0011]
The present invention makes it possible to reliably read the identifiers in the device process by setting the depth of the identifiers after the mirror finish, and to efficiently mark the sliced wafers in the sliced order. An object of the present invention is to provide an identifier marking apparatus and a marking method for a semiconductor wafer, which can be performed.
[0012]
In addition, the present invention makes it possible to accurately inspect the identifiers imprinted on the semiconductor wafer and easily inspect all the identifiers, whereby the semiconductor wafer imprinted with the defective identifier is distributed to the market. It is an object of the present invention to provide an identifier marking apparatus for a semiconductor wafer and a marking method thereof, which can prevent the occurrence of the problem and, as a result, reliably read the identifier in the device process.
[0013]
[Means for Solving the Problems]
The present invention, the thickness of the semiconductor wafer was measured with a thickness meter, its all SANYO was based on the measured value to control the marking by the laser head, and more specifically, the control device, thickness The number of pulses of the irradiation laser light from the laser head is controlled based on the value measured by the measuring instrument.
[0014]
Further, the present invention captures an identifier image imprinted on a semiconductor wafer by a laser head with a camera, collates the read information of the identifier obtained by processing the captured image with the imprint information, and lasers based on the collation result The marking by the head is controlled.
[0015]
Furthermore, the present invention measures the thickness of the semiconductor wafer with a thickness measuring instrument, determines the processing conditions of the identifier from the measured value and the stamp information, and the identifier is stamped on the semiconductor wafer using the laser light under the conditions. An identifier image is captured by a camera, and the identifier read information obtained by processing the captured image is collated with the marking information, and the marking by the laser beam is controlled based on the collation result.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is an enlarged side sectional view of a semiconductor wafer manufactured according to the first embodiment of the present invention, and FIG. 2 is a schematic view showing a marking device according to the first embodiment of the present invention.
[0018]
The marking step in the present embodiment is positioned next to the step of cutting the ingot corresponding to (1) to obtain a sliced wafer in the semiconductor wafer manufacturing step already described in the prior art.
[0019]
First, the marking device will be described with reference to FIG. As shown in FIG. 2A, the marking apparatus 10 measures the thickness of the sliced wafer 2 by holding the bottom surface of the sliced sliced wafer 2 and rotating it horizontally, for example. A reflection-type thickness measuring device 3 and a laser head 4 for marking an identifier on the sliced wafer 2 by laser light are provided. The thickness measuring device 3 preferably measures the thickness of the identifier (scheduled) position of the identifier on the sliced wafer 2 or a position close to the marking position. Usually, the identifier is stamped on the periphery of the wafer. In this embodiment, the thickness of an arbitrary point on the peripheral edge of the sliced wafer 2 held on the turntable 5 can be measured. The value measured by the thickness measuring device 3 is output to the control device 7, and the control device 7 slices the laser oscillator 6 through the laser head 4 based on the measurement signal output from the thickness measuring device 3. The number of pulses of laser light emitted toward the wafer 2 is controlled to control the marking depth.
[0020]
The marking operation by the marking device 10 is performed as follows.
[0021]
First, the sliced wafer 2 cut from the ingot is placed and held on the turntable 5 in a certain direction, and then the turntable 5 is rotated so that the marking position 11 is below the thickness measuring device 3. Here, the thickness measuring device 3 measures the thickness of the marking position 11 in the sliced wafer 2 and outputs a measurement signal to the control device 7.
[0022]
Next, as shown in FIG. 2B, the turntable 5 is rotated so that the marking position 11 of the sliced wafer 2 is positioned below the laser head 4 of the marking apparatus 10. From the laser head 4, laser light is irradiated from the laser oscillator 6 toward the marking position of the sliced wafer 2 and stamped. At this time, the control device 7 controls the number of pulses of the laser light irradiated through the laser head 4 based on the measurement signal from the thickness measuring device 3 as follows.
[0023]
As shown in FIG. 1A, if the value measured by the thickness measuring device 3 is the thickness T1 at the stamping position 11, the thickness T2 after the mirror finish is known in advance, and the machining allowance T3 until the mirror finish is completed. Is calculated. Further, the finishing marking depth D1 which is a standard required from the device process has already been input to the control device 7, and the machining of the identifier 1 to be stamped on the sliced wafer 2 by adding the allowance T3 thereto. A stamping depth D2 is obtained. By the way, the correspondence between the number of pulses of the laser beam to be irradiated and the processing marking depth can be obtained in advance by an experiment or the like. Accordingly, the control device 7 controls the laser oscillator 6 by selecting the number of pulses of the laser beam corresponding to the depth D2 from the above-described correspondence relationship based on the processing marking depth D2 obtained as described above. .
[0024]
As shown in FIG. 1B, the sliced wafer 2 with the identifier 1 thus engraved is then processed up to a mirror finish, thereby removing the semiconductor allowance T3. The finish marking depth D1 of the identifier 1 is always a constant value.
[0025]
According to this embodiment, the depth of the identifier 1 after the mirror finish can be set constant, and thereby the identifier 1 can be reliably read in the device process.
[0026]
In addition, since the sliced wafer 2 can be engraved in the order of slicing, it is not necessary to provide a previous process such as classification according to the thickness as in the prior art, and the process can be shortened and work efficiency can be reduced accordingly. Can also be processed and shipped in the sliced order.
[0027]
Next, a second embodiment of the present invention will be described.
[0028]
FIG. 3 is a schematic configuration diagram showing a marking device according to the second embodiment of the present invention, and FIG. 4 is a flowchart showing a marking procedure using the marking device of FIG.
[0029]
As in the first embodiment, the marking process in the present embodiment is a semiconductor wafer manufacturing process described in the prior art, and the ingot corresponding to (1) is cut to obtain a sliced wafer. It is positioned next to the process.
[0030]
First, the marking device according to this embodiment will be described.
[0031]
As shown in FIG. 3, the marking device 20 is connected to a turntable 22 that holds the bottom surface of the sliced sliced wafer 21 and rotates in the horizontal direction, and a laser head 23 that marks the sliced wafer 21 with an identifier. A marking device main body 24, a reading device main body 26 to which a reading camera 25 for reading a stamped identifier is connected, and an information processing device 27 to which the marking device main body 24 and the reading device main body 26 are connected to constitute a control device. Has been.
[0032]
The marking device main body 24 is inputted with the stamp information of the identifier to be stamped by a keyboard 24a, a mouse (not shown) or the like, and the entered stamp information can be confirmed on the screen 24b. And also sent to the information processing device 27. The laser head 23 connected to the marking device main body 24 is disposed above the sliced wafer 21 so as to face the marking position. Further, the reading camera 25 is also disposed above the sliced wafer 21 so as to face the sliced wafer 21, and when an identifier engraved on the sliced wafer 21 as described later is positioned below, an image of the identifier is displayed. It comes to capture. The identifier image captured by the reading camera 25 is input to the reading device body 26. The image captured by the reading camera 25 is displayed on the screen 26 a of the reading device main body 26, the image processing is performed by the reading device main body 26, the identifier is read, and the read information is sent to the information processing device 27. It is supposed to be.
[0033]
The marking work by the marking device 20 is performed by a sequence according to the flow shown in FIG.
(1) The thickness of the sliced wafer is measured, and the thickness information is input to the marking device main body 24 (S1). The thickness may be automatically measured by installing the thickness measuring device 3 described in the first embodiment in FIG. 3 or may be separately measured and input. May be.
(2) Marking information such as characters and barcodes that are identifiers to be stamped is input to the stamping device main body 24 (S2).
(3) The marking device main body 24 determines the processing conditions of the identifier, for example, the shape (size and position) and the marking depth based on the input thickness information and the marking information of the identifier, and marks the identifier (S3). This is because the turntable 22 is rotated so that the marking position of the sliced wafer 21 held on the turntable 22 faces the laser head 23, and in this state, the laser light is irradiated onto the sliced wafer 21 from the laser head 23. By doing so, the identifier is imprinted.
(4) The stamped identifier is read by the reader main body 26 (S4). This is done by rotating the turntable 22 and positioning the stamped identifier of the sliced wafer 21 held on the turntable 22 below the reading camera 25. The image captured by the reading camera 25 is displayed on the screen 26 a and is subjected to image processing by the reading device main body 26 to read the shape of the identifier and the like, and this reading information is sent to the information processing device 27.
(5) The information processing device 27 collates the read information from the reading device body 26 with the marking information from the marking device body 24 (S5).
(6) In the information processing device 27, if the collation result is within the predetermined allowable value, an instruction to send the wrapping process is issued (S6), and an error is obtained and stamped as error information for stamp correction. An input is made to the apparatus main body 24 (S7). This error information is used, for example, for correction of the laser intensity or the like during the engraving work on the next sliced wafer 21.
(7) If the collation result is outside the predetermined allowable value, the lapping process feed is stopped (S8) and the marking operation is stopped (S9).
[0034]
As described above, according to the second embodiment, the identifier engraved on the sliced wafer 21 by the laser irradiation is positioned at a position facing the reading camera 25 by the subsequent rotation of the turntable 22, and this reading is performed. The read information based on the image information captured by the camera 25 is compared with the stamp information, whereby the inspection of the stamped identifier, that is, its quality is determined. For this reason, it is possible to accurately inspect the stamped identifier without involving the operator's hand. Further, since the identifier is inspected every time it is engraved by the laser beam, all of the identifiers can be easily inspected. In other words, according to the present embodiment, it is possible to prevent the semiconductor wafer with a defective identifier from being distributed to the market, and as a result, it is possible to reliably read the identifier in the device process. it can.
[0035]
Furthermore, in this embodiment, the identifier marking process and the inspection process are performed on the sliced wafer before the lapping process. This is because, if the inspection process is performed after the etching process or after the final manufacturing process, if a defect is found and the cause of the defect is on the identifier marking device side, a large number of defective products are produced. As a result, there arises a problem that the time and cost required to complete the etching process or the final manufacturing process are wasted. However, in this embodiment, the inspection is performed almost simultaneously with the engraving, and when the defect is detected, the lapping process feeding is stopped and the engraving operation is stopped, so that the generation of defective products can be prevented as much as possible. .
[0036]
In the second embodiment, the engraving process and the inspection process are performed after the process of cutting the ingot to obtain a sliced wafer, so that it is possible to prevent the generation of defective products as much as possible. In terms of the effect that the identifiers imprinted on the semiconductor wafer can be accurately inspected and all the identifiers can be inspected easily, this inspection step can be obtained even between other steps.
[0037]
In the two embodiments described above, the tables 5 and 22 are rotated in a horizontal plane. For example, the tables 5 and 22 are rotated in a vertical plane, and the thickness of the vertically arranged wafer is increased. Measurement, engraving, and image capture of identifiers may be performed. Further, instead of rotation, translation may be performed.
[0038]
【The invention's effect】
According to the present invention, the depth of the identifier after the mirror finish can be set constant, so that the identifier can be reliably read in the device process, and sliced in the sliced order. The marking work can be efficiently performed on the wafer.
[0039]
Further, according to the present invention, since the identifier imprinted on the semiconductor wafer can be accurately inspected and all the identifiers can be easily inspected, the semiconductor wafer imprinted with the defective identifier can be distributed to the market. As a result, it is possible to reliably read the identifier in the device process.
[Brief description of the drawings]
FIG. 1 is an enlarged side sectional view of a semiconductor wafer manufactured according to a first embodiment of the present invention.
FIG. 2 is a schematic view showing a marking device according to the first embodiment of the present invention.
FIG. 3 is a schematic configuration diagram showing a marking device according to a second embodiment of the present invention.
4 is a flowchart showing a marking procedure using the marking device of FIG. 3;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Identifier 2 Sliced wafer 2a Semiconductor wafer 3 Thickness measuring device 4 Laser head 5 Turntable 6 Laser oscillator 7 Controller 10 Stamping device 11 Stamping position 20 Stamping device 21 Sliced wafer 22 Turntable 23 Laser head 24 Stamping device main body 24a Keyboard 24b Screen 25 Reading camera 26 Reading device body 26a Screen 27 Information processing device D1 Finishing stamping depth D2 Processing stamping depth T1 Thickness T2 Finishing thickness T3 Trade allowance

Claims (10)

A table for supporting and moving the semiconductor wafer;
A thickness measuring instrument for measuring the thickness of the semiconductor wafer;
A laser head for imprinting an identifier on the semiconductor wafer using a laser beam;
Have a, a control device for controlling the marking by the laser head based on the measured value by the thickness measuring device,
The control device controls the number of pulses of laser light emitted from the laser head based on the value measured by the thickness measuring device, and is an identifier marking device on a semiconductor wafer.   2. The apparatus for marking an identifier on a semiconductor wafer according to claim 1, wherein the thickness measuring device measures a thickness of a peripheral portion of the semiconductor wafer.   2. The apparatus for marking an identifier on a semiconductor wafer according to claim 1, wherein the thickness measuring device measures a thickness of a marking position on the semiconductor wafer or a position close to the marking position. A table for supporting and moving the semiconductor wafer;
A stamping device body into which the stamping information of the identifier is input;
A laser head for imprinting an identifier on the semiconductor wafer using a laser beam;
A camera for capturing an image of an identifier engraved on the semiconductor wafer by the laser head;
A reader for processing the image captured by the camera and reading the identifier engraved on the semiconductor wafer;
A control device for checking the reading information of the identifier by the reading device and the marking information, and controlling the marking by the laser head based on the checking result
An apparatus for marking an identifier on a semiconductor wafer, comprising: 5. The apparatus for marking an identifier on a semiconductor wafer according to claim 4 , wherein the control device checks the shape of the identifier. The table identifier marking device to a semiconductor wafer according to any one of claims 1 to 5, characterized in that a rotary table which rotates in a horizontal plane. In the method for marking an identifier on a semiconductor wafer, the laser wafer is used to mark the identifier on the semiconductor wafer.
Measuring the thickness of the semiconductor wafer;
A step of obtaining a required processing depth of the identifier in consideration of the measured thickness of the semiconductor wafer, a predetermined marking depth, and a thickness of the semiconductor wafer after the thickness measurement step to a final manufacturing step; ,
A step of marking the semiconductor wafer with an identifier having the determined processing depth using a laser beam;
A method of marking an identifier on a semiconductor wafer, comprising: In the method for marking an identifier on a semiconductor wafer, the laser wafer is used to mark the identifier on the semiconductor wafer.
Marking the identifier on the semiconductor wafer using laser light;
Capturing an image of the stamped identifier with a camera, and reading the identifier stamped from the captured image;
Collating this read information with preset marking information, and controlling the marking by laser light based on the matching result;
A method of marking an identifier on a semiconductor wafer, comprising: In the method for marking an identifier on a semiconductor wafer, the laser wafer is used to mark the identifier on the semiconductor wafer.
Measuring the thickness of the semiconductor wafer;
Determining the processing conditions of the identifier using the measured thickness of the semiconductor wafer and preset marking information;
A step of marking an identifier on the semiconductor wafer using a laser beam under the obtained processing conditions;
Capturing an image of the stamped identifier with a camera, and reading the identifier stamped from the captured image;
Collating this reading information and the marking information, and controlling the marking by the laser beam based on the matching result;
A method of marking an identifier on a semiconductor wafer, comprising: The collation identifier marking method of the semiconductor wafer according to claim 8 or 9, characterized in that is carried out with respect to the shape of the identifier.

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