KR100383910B1 - Apparatus for recognizing marked character - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a marking character recognition apparatus, wherein a semiconductor wafer is placed on a side of a cassette at a predetermined angle without having to remove the semiconductor wafer and move it to a predetermined position in order to recognize marking characters formed on a plurality of semiconductor wafers loaded in the cassette. As the photographing device moves up and down, it recognizes the marking characters of the wafers located in all slots in the cassette, thereby preventing the contamination occurring during the transfer of the semiconductor wafer and reducing the process for recognizing the marking characters. It is about.

As described in detail above, according to the present invention, the marking characters of the wafers stored in the cassette are read without removing them from the cassette, thereby preventing contamination of the wafer, and the process is performed by reading the marking characters without taking out each wafer. It is effective to shorten the progress time.

In addition, since the contamination of the wafer is prevented as described above, the quality of the semiconductor wafer is improved, and the cost loss due to the occurrence of the defective wafer is reduced.

In addition, since the blurring of the image according to the focal length caused when the marking character is inclined at a predetermined angle by the camera using the asymmetric lens according to the present invention is compensated for, the wafer marking character recognition apparatus according to the present invention accurately displays the marking character. It can be recognized, which improves the accuracy of the process and contributes to process reliability.

Description

Apparatus for recognizing marked character}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recognizing wafer marking characters in a cassette. The present invention relates to an apparatus for recognizing marking characters formed on a plurality of semiconductor wafers loaded in a cassette. As the photographing apparatus disposed on the side moves up and down, it recognizes marking characters of the wafers located in all slots of the cassette, thereby preventing contamination caused during the transfer of the semiconductor wafer and shortening the process for recognizing marking characters. It relates to a wafer marking character recognition device.

In general, wafers thinly cut into silicon thin plates after crystallization and crystallization of silicon having an element symbol tetravalent with high purity are used for manufacturing a semiconductor device, and a predetermined number of wafers are usually housed in one cassette for efficiency in processing. The semiconductor process proceeds.

The wafers housed in the cassette are formed with marking characters such as symbols, letters, and numbers in predetermined areas on each wafer for process progress and wafer history management, and a number of processes for forming integrated circuits on the wafer are performed. Various devices for forming and reading such marking characters have been introduced and developed.

Further, an apparatus for taking out a wafer from each slot in the cassette by using a stepping motor to read marking characters of the wafer stored in the cassette, a robot unit for transferring the taken out wafer to a predetermined reading position, and the like may further be described. It is well-developed and is well-published in, for example, patent application 97-0076816 (application name; wafer mark detection system), patent application 96-035572 (application name: method for recognizing marking characters on a semiconductor wafer).

However, such a conventional method has usually been performed to remove the wafer from the cassette in which the wafer is stored to read the marking characters of the wafer, and to move the wafer to a position for reading the marking characters of the wafer. There is a problem that cannot be overlooked in the semiconductor manufacturing process for forming a fine integrated circuit.

Problems caused by the above-mentioned causes may include problems due to environmental factors in a manufacturing line where a manufacturing process for forming a circuit on a semiconductor wafer is performed, and problems due to an apparatus for taking out a wafer. Specifically, it is as follows.

In general, semiconductor manufacturing processes are conducted within very strict cleanliness standards. For example, the US Federal Standard and the NASA standards are generally used in which dust particles of 0.5um or more per square meter or less are generally used. In order to maintain the environmental conditions within the manufacturing line within this specification, a down-flow clean air conditioning system which regulates the flow of air from the ceiling to the floor in the manufacturing line is generally widely used.

Under these circumstances, the wafers stored in the cassette are exposed directly to the flow of air flowing downward when exposed outside the cassette, and fine dusts of 0.5 μm or less present in the manufacturing line are formed on the fine circuit pattern formed on the wafer. In many cases, it is a major cause of wafer contamination.

In addition, contact contamination caused by a robot or teaser which is generally used in moving the removed wafer to the marking character reading position is also a major cause of wafer contamination.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems described above, and an object of the present invention is to enable the recognition of marking characters on a wafer without the semiconductor wafer stored in the cassette being taken out of the cassette.

Another object of the present invention is to be able to recognize a marking character without contacting the wafer in the process of recognizing the marking character on the semiconductor wafer.

Another object of the present invention will be described in more detail in the configuration and operation to be described later.

1 is a partial perspective view of a preferred embodiment according to the present invention.

2 is a partial perspective view of another embodiment according to the present invention.

Figure 3 is an exploded perspective view of the camera fixing part for fixing the camera according to the present invention.

4 is a cross-sectional view showing the action of the asymmetric lens according to the present invention.

5 is a cross-sectional view showing yet another embodiment of the present invention.

According to an aspect of the present invention, there is provided a marking character recognition apparatus comprising: a cassette accommodating plate accommodating a cassette in which wafers are respectively accommodated in a plurality of slots; A marking character recognition unit configured to be inclined at a predetermined angle with a direction in which the wafer is accommodated in a slot, and configured of an asymmetric lens having different focal lengths of upper and lower portions to recognize marking characters on the wafer; And a marking character recognition for changing the recognition position at which the marking character of the wafer accommodated in the cassette is recognized by transferring one of the marking character recognition unit or the cassette accommodating plate in a direction perpendicular to the direction in which the wafer is stored in the slot. And position changing means.

Preferably, a stepping motor is used as the marking character recognition position changing means, and the predetermined angle is an angle in the range of -30 ° to -45 ° from horizontal to be inclined between the wafers stored in the cassette in the marking character recognition unit. Recognize marking characters on the wafer by looking at them.

In addition, the marking character recognition unit additionally configured to adjust the wavelength to 300 ~ 800 ㎚ is additionally configured to take a clearer picture of the marking character image.

Hereinafter, with reference to the drawings will be described in more detail.

1 is a preferred embodiment according to the present invention. In FIG. 1, a cassette 40 for accommodating a wafer is accommodated in the cassette accommodating plate 10.

One side of the cassette 40 is open to accommodate the wafer 45, and the other side of the cassette 40 is formed with a bent jaw so that the accommodated wafer 45 is not separated from the cassette.

Then, the wafer 45 accommodated in the cassette 40 is aligned so that the marking characters on the wafer 45 are located on the open side of the cassette 40 before being accommodated in the cassette storage plate 10.

At this time, the camera 20 is preferably used as the marking character recognition unit 20 for recognizing the marking characters on the wafer 45, and the camera fixing plate 25 so that the lens of the camera 20 is directed toward the open side of the cassette. It is disposed in the), between the camera 20 and the camera fixing plate 25, the angle adjusting unit 27 for adjusting the horizontal angle and the vertical angle of the camera 20 is disposed.

And, both sides of the camera 20 is preferably attached to the illumination device 85, as a wavelength used for the illumination device 85 is used an illumination device 85 that can adjust the wavelength to 300 ~ 800nm.

This is because the marking characters have different colors depending on the type of film formed on the wafer on which the marking characters are formed. In general, the wavelength of the light is preferably adjustable within the above-mentioned range for good photographing regardless of the colors of the wafer. .

As shown in FIG. 3, the camera fixing plate 25 includes a lead screw through groove 29 and a guide shaft through groove 32. A lead screw 33 penetrates through the lead screw through groove 29 so that the lower side is a stepping motor. It is fixed by the (39), the guide shaft through the groove 32, the guide shaft 34 is penetrated, the camera fixing plate 25 is applied to the rotational force from the lead screw 33, but the guide shaft 34 Since it is prevented from rotating by the guide shaft 34, it is linearly moved up or down.

The angle adjusting part 27 is a guide in which a camera position variable plate 23 to which the camera 20 is fixed, and a guide groove 21 for guiding the upper and lower fixing angles of the camera position variable plate 23 are formed in a semicircular shape. Screws to the plate 21, the variable position plate fixing groove 28 extending from the side of the camera position plate 23 and protrudes through the guide groove 21, and the variable position plate fixing groove 28 And a position variable plate fixing bolt 26 for fixing the camera position variable plate 23, and a through groove for fixing the angle adjusting part 27 to a portion extending horizontally from the lower portion of the guide plate 21. This is formed so that the angle adjusting part fixing bolt 22 is fixed.

1 to 3 as described above, in order to photograph and read the marking characters 47 of the plurality of wafers 45 accommodated in the cassette 40 sequentially, the camera disposed to be inclined with the wafer 45 ( The camera 20 should be moved so that 20) rises or falls by a height corresponding to one wafer gap.

As a means for moving the camera 20 as described above, the stepping motor 39 briefly mentioned above, the first rotating gear 36 connected to the rotating shaft of the stepping motor 39, and the first rotating gear 36 are provided. The camera fixing plate 25 is rotated by the second rotating gear 35 geared to the shaft of the lead screw 33 to rotate the lead screw 33 and the rotational force applied from the lead screw 35. It is composed of a guide shaft 34 formed to guide through the camera fixing plate 25 so as not to.

According to the configuration as described above, the operation of the embodiment of the present invention is as follows.

After the cassette 40 containing the plurality of wafers 45 is accommodated in the cassette storage plate 10, when a user generates a wafer marking character recognition command through an input device such as a keyboard, the stepper motor 39 sends a motor to the stepping motor 39. The driving signal is applied, and a photographing start signal is applied to the camera 20.

When the stepping motor 39 drives the step by the motor driving signal, the first rotary gear 36 connected to the shaft of the stepping motor 39 rotates, and the second rotation geared to the first rotary gear 36 rotates. The gear 35 rotates in conjunction.

As the second rotary gear 35 rotates, the lead screw 33 also starts to rotate, and the camera fixing plate (not shown) is inserted into a portion where the lead screw 33 penetrates the camera fixing plate 25. 25 is linearly moved up and down as the lead screw 33 is rotated without rotation.

At this time, the guide shaft 34 guides the camera fixing plate 25 to stably linearly move up and down. The camera fixing plate 25 moves up and down by the above-described action, and the cassette 40 moves. The marking character 47 formed on the wafer 45 accommodated therein is photographed.

The photographed marking character 47 is transmitted to a central controller (not shown) for reading an image, and the central controller (not shown) reads the marking characters 47 included in the transmitted image to each wafer ( Information on the history of 45), the unique number of the wafer 45, and the like is displayed on a monitor (not shown).

In the marking character recognition apparatus as described above, the marking character is photographed by the camera 20 which looks at an interval between the wafers 45 without removing the wafer 45 from the cassette 40 in which the wafer 45 is stored. As a result, the process of removing the wafer 45 from the cassette 40 is unnecessary, which reduces the wafer contamination generated during the exposure of the wafers 45 to the airflow of the downflow method.

In order to recognize the marking characters 47 on the wafer 45, the steps of moving the wafer 45 to a predetermined position, photographing the same, and then inserting the wafer 45 back into the cassette 40 are omitted, which simplifies the process and reduces the process progress time. It works.

FIG. 2 is another embodiment of the present invention, although the same components as those shown in FIG. 1 have been given different reference numerals, but are identified as essentially the same components.

The camera 60 which recognizes the marking characters on the wafer 45 is fixed inclined toward the cassette 40 side, and the cassette storage plate 50 on which the cassette 40 containing the plurality of wafers 45 is placed is a camera ( 60) is an arrangement to move up and down to the position where the image is input.

At this time, the camera 60 is fixed within a range of -30 ° to -45 ° from the horizontal, the cassette storage plate 50 is a lead screw through groove (not shown) and a guide shaft through groove (not shown) as shown in FIG. ) Is formed.

In addition, a lower portion of the lead screw 73 penetrating through the lead screw through groove (not shown) is connected to the first rotary gear 75 connected to the shaft of the stepping motor 70 as shown in FIG. 1. 76) is formed.

The guide shaft 74 penetrates the guide shaft 74 and the upper and lower sides of the guide shaft penetrating groove (not shown) are fixed to the upper and lower sides, and the upper and lower portions of the cassette accommodating plate 50 are linearly moved up and down by receiving rotational force of the lead screw 73. Configured to guide the exercise.

The process of recognizing the marking character of the wafer by the configuration as described above is as follows.

After the cassette 40 containing the plurality of wafers 47 is accommodated in the cassette accommodating plate 50, when a user generates a wafer marking character recognition command through a keyboard, a motor driving signal is applied to the stepping motor 70. The camera 60 receives a shooting start signal.

When the stepping motor 70 drives the stepping by the motor driving signal, the first rotary gear 75 connected to the shaft of the stepping motor 70 rotates, and the second rotation geared to the first rotating gear 75. The gear 76 interlocks and rotates.

As the second rotary gear 76 rotates, the lead screw 75 also starts to rotate, and the cassette is accommodated by a bearing (not shown) inserted into the portion through which the lead screw 75 penetrates the cassette holder plate 50. The plate 50 does not rotate but linearly moves up and down as the lead screw 75 rotates.

At this time, the guide shaft 74 guides the cassette receiving plate 50 to stably linearly move up and down, and the cassette receiving plate 50 moves up and down by the above-described action. The marking character 47 formed on the wafer 45 accommodated in the plate 50 is photographed.

The photographed marking character 47 transmits an image to a central processing unit (not shown), and the central processing unit (not shown) reads the marking character 47 included in the transmitted image of each wafer 45. Information about the history, the unique number of the wafer 45, and the like is displayed on the monitor unit (not shown).

4 is a cross-sectional view of the asymmetric lens 80 used by the camera used in the present invention to shoot a tilted image as a non-tilted image.

According to FIG. 4, the asymmetric lens 80 has a radius R1 from the center to the bottom of the lens and a radius R2 from the top of the lens having different lengths, and preferably the radius R1 of the lower side near the incident image is close to the image. Is shorter than the radius R2 on the far upper side.

According to the action of the asymmetric lens 80, the inclined image is incident and photographed by the camera as a normal image, and is applied to a central controller (not shown) for reading the image so that the marking characters of the wafer are read.

FIG. 5 is a plan view illustrating another embodiment of the present invention, and according to FIG. 5, the marking character recognition module 400, the wafer alignment module 500, the wafer transfer unit 600, the signal input unit 700, and the central controller 800 are described. ) And a monitor 900.

In more detail, the marking character recognition module 400 includes a first fixing plate 110 in which a cassette in which a wafer 145 is accommodated in a plurality of slots is accommodated, and a slot formed in the cassette 140 interlocked with the stepping motor 130. It is fixed to the camera moving shaft 134 that moves up and down corresponding to the position, and the angle adjusting plate 127 configured to rotate a horizontal circumference corresponding to 60 ° on the camera moving shaft 133, and is stored in the cassette slot. The first camera 120 reads the marking characters of the wafer 145.

The cassette 140 is accommodated in an upper portion of the first fixing plate 110, and a cassette edge holder 141 is formed at each corner of the first fixing plate 110 to fix the stored cassette 140.

The camera moving shaft 133 is vertically formed from the front to face the first fixing plate 110 from the front of the first fixing plate 110, and a driving signal from the central controller 200 is provided at the lower end of the camera moving shaft 133. Stepped motor 130 is applied is connected is configured to move up and down to a height corresponding to each slot of the cassette 140 accommodated in the first fixing plate 110.

The first camera 120 is fixed to the angle adjusting plate 127 fixed to the camera fixing plate (not shown) of the camera moving shaft 133, the lens used in the first camera 120 is formed asymmetrically, up and down An asymmetric lens is constructed.

The wafer alignment module 500 includes a second fixing plate 150 through which the cassette 140 is accommodated, and a second fixing plate moving shaft configured to penetrate the second fixing plate 150 to move the second fixing plate 150 up and down. 173 and the second camera 160 disposed on a predetermined side surface of the region where the second fixing plate 150 moves up and down.

One end of the second fixed plate moving shaft 173 penetrates through the second fixed plate 150, and the other end of the second fixed plate moving shaft 173 is gear-coupled to the main shaft of the stepping motor 170 to be linked with the rotational movement of the auxiliary shaft by the rotation of the main shaft. Descent movement is performed.

In this case, the stepping motor 170 may control the rising and falling of the second fixing plate moving shaft 173 by the height corresponding to the interval between the slots in the cassette 140 accommodated on the second fixing plate 150.

The second camera 160 is fixed to a side spaced apart from the moving path of the second fixing plate 150 that moves up and down as the second fixing plate moving shaft 173 moves up and down, and is fixed to the second camera 160. It is also fixed to the side by the camera angle control plate 167, the rotation guide groove is formed like the first camera 120.

The wafer transfer unit 600 is formed in the center of the mutual modules to relay the wafer 145 between the marking character recognition module 400 and the cassette 140 accommodated in the wafer alignment module 500, and is defined in the wafer transfer unit 600. The moving part driving robot 210 which drives to move up and down and the forward and backward movement on the track and the wafer 145 stored in the cassette 140 are moved forward, ascending, backward and descending. It consists of a wafer input and output unit 220 to perform.

For example, a vacuum suction unit 230 for vacuum suction is formed at an end of the wafer input and output unit 220 so that the wafer input and output unit 220 can take out or insert the wafer 145 stored in the cassette 140. do.

The signal input unit 700 is a keyboard for inputting a control command according to the present invention, and the user inputs the control command, which is formed on a predetermined side surface.

The control command input from the signal input unit 700 is converted into a control signal of a predetermined code and applied through a control signal line (not shown) connected to the central control unit 800 to be described later.

The central control unit 800 reads a signal through an image signal line (not shown) connected from the first camera 120 and the second camera 160 and a control signal line (not shown) connected to the signal input unit 700. And a control signal, and is connected to the monitor 900 through an output line (not shown) connected to the monitor 900.

The monitor 900 is configured to receive an output signal applied through an output line (not shown) connected to the central controller 800 and display the same on a screen.

The operation of the embodiment having the configuration as described above is as follows.

First, the semiconductor wafer 145 is accommodated in a plurality of slots formed in the cassette 140, and the flat zone of the wafer 145 is aligned at an open portion of the cassette 140, and the wafer is positioned at the flat zone portion. Marking character of is formed.

According to the present invention, after the user uploads the cassette 140 containing the wafer 145 to the first fixing plate 110 on the marking character recognition module 400, the user stores the cassette 140 stored in the cassette 140 through the signal input unit 700. A control command for recognizing the marking character of the wafer 145 is input.

The control command is converted into a control signal of a predetermined code by the signal input unit 700 and applied to the central control apparatus 800 through a control signal line (not shown).

The central controller 800 calculates an applied control signal to generate an output signal, and the generated output signal is applied to the stepping motor 130 connected to the camera moving shaft 133.

The stepping motor 130 steps the camera movement shaft 133 up and down so that the first camera 120 fixed to the camera movement shaft 133 stops at a position where the cassette slot can be photographed at a predetermined angle. .

Preferably, the angle at which the first camera 120 photographs the cassette slot is set within a range of 30 ° to 45 °, and each scanning is performed from the upper slot to the lower slot of the cassette fixed to the first fixing plate 110. An image signal including an image of the marking character generated by photographing the wafer marking character in the slot is applied to the central controller 800 through an image signal line (not shown).

The central control unit 800 performs a process of reading a marking character reading signal applied through an image signal line (not shown) to generate information of a wafer stored at an address designated for each slot.

The generated wafer information includes information such as a process step progressed up to the present time and a process progress step to be performed next, and the central controller generates an alarm signal when a wafer is found that should not be included in the current inspection step.

In addition, an output signal indicating a storage state of the wafers 145 stored in the slots in the cassette 140 is generated and applied to the monitor unit 900 through a signal line (not shown).

The monitor 900 receives an output signal from the central controller 800, and displays a screen showing the slots of the cassette 140, and marking characters of the stored wafers are displayed in each slot.

At this time, while the user monitors through the monitor 900, a predetermined control signal is input through the signal input unit 700, for example, the user receives a wafer (housed in the cassette 140 in the marking character recognition module 800). When the control signal desired for aligning the 145 in the wafer alignment module 500 is input in the correct order, the signal is applied to the central controller 800 to apply a driving command to the wafer transfer device 600.

In order to align the wafers in order, the wafer transfer device 600 removes the wafer 145 from the marking character recognition module 400 and puts it in a cassette stored in the wafer alignment module 500, and is applied by the above-described central controller 800. Before the driving command is applied, the second fixing plate 150 of the wafer alignment module 500 is set to be positioned at the same height as the first fixing plate 110, and the wafer 145 is removed from the marking character recognition module 400. The wafer transfer device 600 under vacuum suction moves up and down to the position of the slot to be placed in the cassette 140 fixed to the second fixing plate 150, and is arranged horizontally with the position of the slot. The wafer is put down by a process such as fine descent and reverse.

As described above, when the second fixing plate 150 in the wafer alignment module 500 is fixed to receive the wafer, a process of confirming whether the received wafers are correctly received in each slot in order may be additionally performed. have.

As described above, when the second fixing plate 150 descends by a height corresponding to one slot, the second fixing plate 150 enters into the video screen of the second camera 160 from the slot of the lowest portion of the cassette, and the second camera 160 In the cassette, the marking characters are sequentially photographed from the marking characters of the wafer accommodated in the lowest slot to the marking characters of the wafer accommodated in the highest slot of the cassette, and transmitted to the central controller 800.

The central controller 800 reads the video signal applied from the second camera 160 through an image signal line (not shown) and checks whether it is correctly stored in a predetermined slot.

The process of reading the video signal to generate the necessary read data is as follows.

Binary coding of the applied video signal removes noise and removes information required for recognition, segmentation process of extracting character strings and separating characters from preprocessed video signal, and recognition using dynamic programming Matching Process Finally, the recognition result is derived through the post-processing process based on the recognition matching degree.

The output signal generated as a result of the checking process is transmitted to the monitor unit 900 through a signal line (not shown), and the monitor unit 900 is provided in the cassette 140 accommodated on the second fixing plate 150. Marking characters of the wafers stored in each slot are displayed.

According to this process, the marking character recognition module 400 recognizes the marking characters on the wafer without removing the wafer 145 from the cassette 140, thereby reducing the contamination of the wafer since the wafer is not exposed to the air conditioning of the downflow method.

Then, the steps necessary to recognize the marking characters on the wafer, for example, the step of taking out the wafer from the cassette, the step of transferring the removed wafer to the marking character recognition position, the marking character recognized wafer into the cassette Steps and the like are not required, and according to the present invention, the camera recognizes the marking characters of the wafer in the fixed cassette as the camera moves, or the camera holds the wafer stored in the cassette while the cassette containing the wafer moves up and down. Make sure that the marking character is read.

As described in detail above, the present invention has been described in detail with respect to preferred embodiments, but those skilled in the art to which the present invention pertains, various embodiments of the present invention without departing from the spirit and scope of the present invention It will be appreciated that the present invention may be modified or modified as described above.

As described in detail above, according to the present invention, the marking characters of the wafers stored in the cassette are read without removing them from the cassette, thereby preventing contamination of the wafer, and the process is performed by reading the marking characters without taking out each wafer. It is effective to shorten the progress time.

In addition, since the contamination of the wafer is prevented as described above, the quality of the semiconductor wafer is improved, and the cost loss due to the occurrence of the defective wafer is reduced.

In addition, since the blurring of the image according to the focal length caused when the marking character is inclined at a predetermined angle by the camera using the asymmetric lens according to the present invention is compensated for, the wafer marking character recognition apparatus according to the present invention accurately displays the marking character. It can be recognized, which improves the accuracy of the process and contributes to process reliability.

Claims (5)

A cassette accommodating plate accommodating a cassette in which wafers are accommodated in a plurality of slots, respectively; A marking character recognition unit configured to be inclined at a predetermined angle with a direction in which the wafer is accommodated in a slot, and configured of an asymmetric lens having different focal lengths of upper and lower portions to recognize marking characters on the wafer; And Marking character recognition position to change the recognition position is recognized by the marking character of the wafer accommodated in the cassette by transferring any one of the marking character recognition unit or the cassette receiving plate in the direction perpendicular to the wafer received in the slot Marking character recognition device characterized in that it comprises a changing means. The marking character recognition apparatus according to claim 1, wherein a lead screw connected to a stepping motor and a stepping motor is used as the marking character recognition position changing means. The apparatus of claim 1, wherein the predetermined angle is an angle within a range of -30 ° to -45 ° from horizontal. The marking character recognition apparatus of claim 1, wherein the marking character recognition unit additionally comprises an illumination device capable of adjusting the wavelength to 300 to 800 nm. delete