JP2008016856A - Method for detecting missing transferred object having missing part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for detecting an missing wafer having the missing part from wafers during transfer in a vacuum processing device inexpensively. <P>SOLUTION: Seventeen sets of unit sensors 43 which are a reflection type optical sensor are installed at regular intervals of the width more than that of a wafer W in a line perpendicular to the transfer direction of the wafer in an opening of the ceiling region in valve box 21 of gate valve 20 between transportation room 10 and processing room 13 through a hard glass window 25. When a unit sensor in the center of the line detects the tip of the transferred wafer, a high-speed operating part 48 starts counting at interval of millimeter second unit and accumulating the state that, in all unit sensors, a light projected from a light projecting part is reflected in a normal part of the wafer and is received in a light receiving part. When a back end of the wafer is detected, the counting is stopped. The counting number accumulated in each unit sensor is compared to that of the normal wafer. Since it is not counted in the missing part, the existence of the missing part can be recognized. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for detecting a missing transport object having a missing portion, and more specifically, an optical sensor is provided in a valve box of a gate valve that connects a transport chamber and a processing chamber in a vacuum processing apparatus, and The present invention relates to a method for detecting a missing transport target by determining whether or not there is a missing portion at the peripheral edge of the transport body during transport.

Conventionally, in a vacuum processing apparatus such as a semiconductor manufacturing apparatus, chipping may occur in a wafer. Chipping is a defect such as chipping generated at the peripheral edge of the wafer, but when a wafer having such chipping is subjected to high heat treatment in the apparatus or transported in the apparatus,
Cracks occur from the chipping part. The broken pieces and the like adversely affect subsequent wafers. Moreover, it becomes dust and contaminates the device, and also causes a failure of the device. Therefore, it is necessary to stop the device for a long time and restore it, thereby reducing the operating rate of the device.

  In order to cope with the above problems, there has been proposed a semiconductor manufacturing apparatus in which a wafer chipping detection means is provided in a wafer loading / unloading section adjacent to a processing chamber in the apparatus. FIG. 19 is a diagram showing an embodiment of the semiconductor manufacturing apparatus. In FIG. 19, a plurality of wafers 102 to be processed are placed in a cassette 101 provided in a carry-in / out section 108 of the semiconductor manufacturing apparatus 109. Are accommodated at intervals in the vertical direction. A robot (not shown) is installed in the carry-in / carry-out unit 108. The robot takes out the wafers 102 in the cassette 101 one by one, conveys them in the direction indicated by the arrow A, and places them on the alignment device 103. To do. The wafer 102 is set at a predetermined position on the alignment apparatus 103 with reference to the orientation flat formed on the wafer 2 itself. In such a loading / unloading unit 108, a CCD camera 104 is installed above the alignment device 103, and the wafer 102 is imaged by the CCD camera 104. The imaging data is sent to the image processing apparatus 110 and subjected to image processing, and the presence or absence of chipping in the wafer 102 is determined (see Patent Document 1).

  According to the method of imaging a wafer with a CCD camera, the chipping generated on the wafer can be clearly grasped, but the CCD camera and the image processing apparatus are extremely expensive and greatly increase the apparatus cost, so that the cost can be reduced. This method is difficult to adopt in the required manufacturing field.

JP 2000-252335 A

  The present invention has been made in view of the above-mentioned problems, and without using a CCD camera, a missing transport target having a missing portion is transported with high accuracy from among a large number of transported objects transported in a vacuum processing apparatus. It is an object to provide a detection method that can be detected.

  The above problem can be solved by the configuration of claim 1, and the solution means will be described as follows.

In the method for detecting a missing transport object having a missing portion according to claim 1, the first chamber and the second chamber of the vacuum processing apparatus are connected via a gate valve, and the first chamber and the second chamber are connected to each other. A method of detecting a missing transport object having a missing portion included in a transported object being transported one by one during the transport of the missing transport object,
1. A large number of unit sensors are arranged at equal intervals in the direction perpendicular to the transport direction of the transported body so that the width is equal to or greater than the width of the transported body, and the adjacent unit sensors are distinguished from each other. A step of detecting the tip of the conveyed object by an optical sensor using a combination of a light projecting unit and a light receiving unit using light of a wavelength to be obtained;
2. Based on the detection of the tip, all unit sensors are synchronized, and detection of whether or not the light emitted from the light projecting unit is received by the light receiving unit is started at a very short period, and the light is carried Count the state where light is received by the light receiving part due to reflection by the normal part of the feeder, or the state where the light is not received by the light receiving part due to interruption by the normal part of the transported body
Accumulating the count;
3. A step of stopping counting by detecting the rear end of the object to be transported by an optical sensor;
4). Compare the light reception pattern or non-light reception pattern formed from the count value accumulated for each unit sensor (the integrated value of the count) with the same light reception pattern or non-light reception pattern for normal transported objects, and And a step of determining the presence or absence and detecting the missing transported body.

  Such a method of detecting a missing transported body reduces the transport speed of the missing transported body that is transported between the first chamber and the second chamber of the vacuum processing apparatus by relatively simple means. It is possible to detect with high accuracy without causing it.

  The method for detecting a missing transfer object according to claim 2 is a detection method in which the first chamber is a transfer chamber of a vacuum processing apparatus, the second chamber is a process chamber of a vacuum processing apparatus, and the transfer object is a semiconductor wafer. It is.

  Such a method of detecting a missing transfer object is high without lowering the transfer speed during transfer of the missing wafer transferred between the transfer chamber and the processing chamber of the vacuum processing apparatus by relatively simple means. It can be detected with accuracy.

  According to the detection method of the missing transport object of claim 1, the missing transport object that is transported between the first chamber and the second chamber of the vacuum processing apparatus can be detected with high accuracy during the transport. , Transportation troubles caused by carrying the missing transported body from the first chamber to the second chamber as it is, product defects, stoppage of the device for returning the second chamber to the original state, and a reduction in operating rate Do not invite.

  According to the missing carrier detection method of claim 2, since the missing wafer conveyed between the conveyance chamber and the processing chamber of the vacuum processing apparatus can be detected with high accuracy during conveyance, It does not cause a transport trouble, a processing failure, a stoppage of the apparatus for returning the processing chamber to the original state, and a decrease in the operation rate caused by carrying the processing chamber into the processing chamber as it is.

  In the method for detecting a missing transport object having a missing part according to the present invention, the first chamber and the second chamber are connected via a gate valve, and the transported object transported between the first chamber and the second chamber. This is a method for detecting a missing transport target while it is being transported by an optical sensor when there is a missing transport target having a missing part in the transport body, and can detect it with high accuracy without reducing the transport speed. it can. As the optical sensor, either a reflective optical sensor or a transmissive optical sensor can be used.

  The type of the transported body is not particularly limited as long as it causes a missing portion due to cracking. In the embodiments, a semiconductor wafer is taken up as a transported body. However, for example, a glass substrate or a ceramic sintered body may be used. In addition, as long as the type of the vacuum processing apparatus is such that the first chamber and the second chamber are connected via the gate valve and the transferred object passes between the two chambers through the gate valve, There is no particular limitation. In the embodiment, the vacuum processing apparatus in which a plurality of processing chambers are arranged via gate valves around each outer periphery of the central hexagonal cylindrical transfer chamber is exemplified. It may be a vacuum processing apparatus arranged in a straight line via a gate valve, or a vacuum sintering furnace in which a degassing chamber and a sintering chamber are connected via a gate valve.

  For example, the inside of the gate valve opened between the transfer chamber as the first chamber and the processing chamber as the second chamber is supported by the bifurcated hand at the tip of the arm of the transfer robot in the transfer chamber and transferred horizontally. When a missing wafer having a missing portion in the wafer is detected by an optical sensor, the light projecting portion of the optical sensor is installed through a transparent window at the opening of the valve box ceiling of the gate valve above the wafer. As a light source of the light projecting unit, a continuous wave semiconductor laser emitting a red light having a wavelength of 0.6 μm to 0.7 μm is usually used, and a phototransistor having high sensitivity at a wavelength used by a pair of light receiving units. Is used. In addition, semiconductor lasers that emit visible light or infrared light other than red can be used. Since the optical sensor using the semiconductor laser has high directivity, the light receiving property of the light receiving unit from the light projecting unit can be increased. The light source is not limited to the semiconductor laser, and various types of light sources may be used, and ultraviolet light may be used as the light. Further, for example, a pulse oscillation laser with a high frequency of 1 kHz or more can be used instead of a continuous oscillation laser. As the transparent window to be used, a glass window is used when visible light or infrared light is used for the light of the optical sensor, but a synthetic resin window such as a methacrylate resin is used when the atmosphere of the processing chamber permits. A quartz glass window is used when ultraviolet rays are used.

  When using either a reflection-type optical sensor or a transmission-type optical sensor, it is necessary to avoid misidentifying the bifurcated hand that supports the object to be conveyed as the optical sensor being a part of the object to be conveyed. . That is, in the reflection type optical sensor, when the hand is exposed at the missing part, the light projection from the light projecting part that should pass through the missing part of the transported body is reflected by the hand and received by the light receiving part and exposed. Therefore, the supporting surface of the hand needs to be a low reflection surface that can be distinguished from the transported body. In the transmissive optical sensor, if the hand is exposed at the missing part, the light projecting from the light projecting part that should pass through the missing part is blocked by the hand and not received by the light receiving part, and the exposed hand is normal Since it is mistaken for a part, the hand needs to be transparent. Usually, the hand of the transfer robot is made of a metal such as SUS (stainless steel) or aluminum. In this case, it is desirable that the surface of the hand be a low reflection surface.

  When using a reflection type optical sensor, the valve body of the gate valve may be opened by moving it downward from the closed position in the valve box, or it may be opened by moving it to the side. There may be. On the other hand, in the case of using a transmission type optical sensor, the valve body is moved from the closed position to the side to be opened because the light receiving part is disposed on the bottom surface side of the valve box. Furthermore, when using a reflection-type optical sensor, the light from the light projecting unit is reflected by the normal part of the transported body and received by the light receiving unit. Although detection is performed, in order to avoid misidentifying the reflected light from the valve body whose optical sensor is opened and closed as the reflected light from the conveyed object, the valve body that reflects the light projected from the optical sensor is reflected. It is desirable that the surface be a low reflection surface. In order to obtain a low reflection surface, for example, shot blasting may be directly performed on the reflection surface of the valve body, or the surface may be roughened with a rough polishing cloth. Moreover, you may attach the board | plate material which has the low reflective surface by which the blast process was carried out to a reflective surface.

For the optical sensor, a large number of unit sensors are arranged in a direction perpendicular to the transport direction of the transported body so that the width of the light projecting end is parallel to the surface of the transported body. That is, a line sensor is used. A large number of unit sensors in the line sensor are arranged at equal intervals, and the size of the intervals is determined by the size of the missing portion to be detected. That is, if the interval is large, it is difficult to detect a small missing portion, and the smaller the interval, the smaller the missing portion can be detected. For example, the wafer is divided into n at a constant interval in parallel with the transport direction, and n unit sensors are arranged so that the unit sensors are respectively located at the center of the divided interval. When the front and rear ends of the wafer are detected by the center position unit sensor at the center of the n unit sensors, the center position unit sensor and the wafer are positioned so that the center of the wafer passes under the center position unit sensor. It is desirable to set the positional relationship with the conveyance path. When the number of unit sensors is an odd number, the unit sensor in the middle of the array can be used as the center position sensor. When the number of unit sensors is an even number, the object can be achieved by arranging any one unit sensor in the central portion as a central position unit sensor. In addition, in the case of an even number, although it is not precise, it is arranged so that the middle of two adjacent unit sensors is above the diameter in the wafer transfer direction, and the average of count values described later by the two unit sensors is set. A convenient method in which the value is the count value of the virtual center position sensor may be employed.

  A unit sensor that uses optical fibers at the light projecting end and the light receiving end is preferably used. In the case of a reflection type optical sensor, as shown in FIG. 4 to be described later, the light projecting unit and the light receiving unit of the unit sensor are arranged in parallel with the wafer transport direction, and light is projected from the light projecting unit and reflected by the wafer surface. The light projecting end portion and the light receiving end portion are set to be inclined obliquely downward so that the received light is efficiently received by the light receiving portion. An optical fiber protected with a plastic coating is flexible and easy to maintain at the set position, and has the advantage that the light projecting performance and light receiving performance are less affected by the magnetism and heat of the vacuum processing apparatus itself.

  For example, a missing wafer can be detected by the reflective optical sensor as follows. The wafer transferred by the transfer robot passes through the gate valve at a substantially constant speed, but as described above, the center of the wafer is set so that the center of the wafer passes under the unit position sensor among the many unit sensors. To do. Then, when the center position unit sensor detects the front end of the wafer, all the unit sensors are synchronized by the high speed calculation unit, and the light projected from the light projecting unit is reflected by the normal part of the wafer and is received by the light receiving unit. The counting of the light-receiving state is started at a very short fixed period (for example, 1 millisecond), and the count for each period is accumulated in the register of the high-speed calculation unit. As a matter of course, the light projection from the light projecting unit is not reflected at the missing part and is not received by the light receiving unit, and thus is not counted. The reason for counting in milliseconds as described above is to detect the missing portion with high accuracy by dividing the moving distance of the reflection point due to the transfer of the wafer very short.

  Then, when the central position unit sensor detects the rear end of the wafer, counting of the light receiving state in the light receiving portions of all the unit sensors is stopped. Then, by arranging the count values (integrated values of the counts) obtained for each unit sensor in the order of arrangement of the unit sensors, a light receiving pattern for the wafer is formed, and the light receiving pattern is registered in advance as a normal wafer. The missing wafer is detected in comparison with the similar light receiving pattern attached to. This is because in the missing wafer, the received light is not counted in the missing portion, and the light receiving pattern is destroyed accordingly. When it is determined that the wafer is a missing wafer, an abnormal signal for notifying that is output. After the abnormal signal is output, the operation of the vacuum processing device may be simply stopped, the missing wafer may be taken out and restarted, and the missing wafer may be temporarily isolated and stored in the transfer chamber. You may make it do. Note that the start and stop of counting in a state where the light receiving unit is receiving light may employ a method other than the detection of the front and rear ends of the wafer by the central position unit sensor. Of course, in the case of a normal wafer, a normal signal indicating normality may be output.

  In addition to the line sensors as described above, the optical sensor may be a surface sensor in which two or more line sensors are arranged in parallel within the range allowed by the mounting area of the valve box. The detection accuracy can be improved by detecting the portion and repeating the detection. In addition, the two parallel sensors are arranged side by side so that the unit sensor of the other line sensor is positioned between the two unit sensors of the one line sensor, and these unit sensors are operated as one line sensor. As a result, the density of the unit sensors per unit length of the line sensor can be substantially increased.

  An optical sensor that can be adjusted in sensitivity is preferably used. For example, the light receiving sensitivity is increased when the amount of reflected light from the wafer is small, and the light receiving sensitivity is decreased when the amount of reflected light is large. Furthermore, it is desirable to use at least two or more types of unit sensors having different wavelengths for a large number of unit sensors. Among a large number of arranged unit sensors, adjacent unit sensors are different from each other. What has the light projection part and light-receiving part by the light of a wavelength are combined. With this arrangement, the light projected from the light projecting part of one unit sensor and reflected by the normal part of the transported body reaches the light receiving part of the adjacent unit sensor and is received. This can prevent the missing part from being mistaken as a normal part.

  When starting and stopping the counting of the light receiving state based on the detection of the front and rear ends of the wafer by the central position unit sensor, if the wafer is divided along a straight line in the transport direction passing through the center, The central position unit sensor cannot detect the wafer, and the wafer is not recognized as a missing wafer as it is. The transfer chamber is provided with a position sensor for confirming the presence of the wafer when the wafer is returned from the processing chamber and the arm of the transfer robot is completely folded to the position facing the processing chamber. However, in order to cope with the case where the center position unit sensor does not detect the front end of the wafer, if the wafer that is not detected by the center position unit sensor is detected by the position sensor, the wafer is determined as a missing wafer. It has become. Of course, by constructing a circuit that starts counting the number of received light by detecting the presence of a wafer with any one of a large number of unit sensors, the above-mentioned undetected wafer does not occur. This complicates the circuit configuration of the high-speed arithmetic unit and increases the cost.

  Next, a method for detecting a missing wafer having a missing portion according to the present invention will be described in detail with reference to the drawings by an embodiment in which a reflection type photosensor is provided on a gate valve. FIG. 1 is a partially omitted plan view schematically showing the configuration of a single-wafer vacuum processing apparatus 1, and FIG. 2 is a cross-sectional view taken along the line [2]-[2] in FIG. In the single-wafer type vacuum processing apparatus 1, a sputter processing chamber 13 is connected to a regular hexagonal cylindrical transfer chamber 10 via a gate valve 20, and a loading chamber 11 and other processing chambers 14 as indicated by a one-dot chain line. The unloading chamber 16 is similarly connected. A transfer robot 31 is installed at the center of the transfer chamber 10 so as to be rotatable around a rotation shaft 32. The transfer robot 31 is bent at the end of two arms 33 that can be bent and extended. A semiconductor wafer W having a diameter of 200 mm is placed on the hand (pickup) 34 and transferred. That is, the wafer W taken out from the loading chamber 11 is loaded into the processing chamber 13, and when the processing in the processing chamber 13 is completed, the wafer W is taken out and loaded into the processing chamber 14 for processing. In addition, when a processing chamber is arranged, the processing is performed in the processing chamber, and after the processing is completed, the processing chamber is transferred to the unloading chamber 16.

FIG. 1 shows the state of the valve box 21 of the gate valve 20 in which the wafer W after the processing in the processing chamber 13 is placed on the hand 34 and the valve body 22 is lowered and opened with reference to FIG. The state being conveyed through the contact opening 21g is shown. The sensor head 42 of the reflective optical sensor 41 is attached to the opening 21 w of the ceiling portion of the valve box 21 through the hard glass plate 25. The sensor head 42 includes 17 unit sensors 43 each composed of a combination of a light projecting unit 44 having a light projecting end portion using an optical fiber and a light receiving unit 45 having a light receiving end portion using an optical fiber. Are arranged in a line with a width equal to the diameter of the wafer W in the width direction perpendicular to the transfer direction. The red semiconductor laser used for the light source of the light projecting unit 44 has two wavelengths with wavelengths that can be distinguished from each other within the range of 0.6 to 0.7 μm. The adjacent unit sensors 43 use a combination of a light projecting unit 44 and a light receiving unit 45 having different wavelengths. Light projected from each light projecting unit 44 toward the wafer W passing under the 17 unit sensors 43 arranged in a line and reflected by a normal portion of the wafer W is received by the corresponding light receiving unit 45. However, the missing portion is detected by utilizing the fact that the missing portion is not reflected and is not received by the light receiving unit 45. Then, the detection signal in a state of being received by the light receiving unit 45 is amplified by the sensor amplifier 47 and input to the high speed calculation unit 48. The high speed calculation unit 48 detects the missing wafer W ′ as a result of the calculation. Outputs an abnormal signal.

  The sensor head 42 is installed by removing the cover plate that closes the maintenance opening of the normal gate valve 20, and as shown in the left sectional view of FIG. 3, the valve box 21 of the original gate valve 20. A maintenance opening 21 w is formed in the ceiling portion of the, and the opening 21 w is closed by a lid plate 24. And the valve body 22 shown with a continuous line is in an open position, and the valve body 22 shown with a dashed-dotted line shows the state which plugged up the communication port 21g of the valve box 21, and is in a closed position. As shown in the right sectional view of FIG. 3, and referring also to FIG. 2, the reflection type photosensor 41 of the present embodiment removes the cover plate 24 and replaces the hard glass plate 25 as a cover plate with a transparent window. A fixed opening frame 26 is attached, and a sensor head 42 in which 17 unit sensors 43 in which a light projecting unit 44 and a light receiving unit 45 are arranged along the conveyance direction of the wafer W are arranged on the hard glass plate 25. Is attached. In the sensor head 42, as shown in FIG. 4 to be described later, the light projected from the light projecting end of the light projecting unit 44 is reflected on the surface of the wafer W via the hard glass plate 25 and again hard. The opposite light projecting end and light receiving end are both set obliquely downward inward so as to enter the light receiving unit 45 from the light receiving end through the glass plate 25 most efficiently.

  4 is an enlarged cross-sectional view showing the main part of the sensor head 42 of the reflective optical sensor 41 attached to the ceiling of the valve box 21 of the gate valve 20 shown in FIG. 2, and FIG. It is sectional drawing of a [5]-[5] line direction. 4 and 5, the horizontal distance between the lower end of the light projecting portion 44 of the unit sensor 43 and the lower end of the light receiving portion 45 is 20 mm, and the light projecting portion 44 and the light receiving portion 45 are arranged from the surface of the wafer W. The height h up to the lower end is set to 53 mm. Although not shown, the sensor head 42 has a height h variable within a range of 50 to 65 mm by inserting a spacer between the sensor box 42 and the light receiving portion for the reflected light from the wafer W. The amount of received light by 45 can be adjusted. As described above, the light projected from the light projecting unit 44 of the unit sensor 43 is transmitted through the hard glass plate 25 at a predetermined angle to reach the surface of the wafer W, reflected, and transmitted through the hard glass plate 25 to receive light. It is configured to reach part 45. The opening frame 26 to which the hard glass plate 25 is fixed, the hard glass plate holder 27, and the sensor head fixing member 28 are fixed by positioning bolts 29, and the sensor head 42 is removed for maintenance of the gate valve 20. The reproducibility of the fixed position is ensured when it is fixed again.

  Referring to the right side sectional view of FIG. 3, the valve element 22 is moved up and down for opening and closing. In order to prevent this movement from being mistaken for the passage of the wafer W, the valve element 22 projects light. A SUS plate 23 having a low-reflecting surface by shot blasting the surface is attached to the upper surface serving as a reflecting surface for light projection from the portion 44. Referring to FIG. 5, 17 unit sensors 43 of the sensor head 42 are arranged at the center of each of the parts obtained by dividing the width of the wafer W into 17 parts. Light is projected downward as indicated by an arrow on the surface of W.

  Then, the detection by the reflection type optical sensor 41 of the missing wafer W ′ where the missing portion exists is performed as follows. 4 and 5 and FIGS. 9 and 10 described later, the tip of the wafer W passing through the gate valve 20 is detected by the ninth central position unit sensor 43c from both ends of the 17 unit sensors 43. When the leading edge of the wafer W is detected, the seventeen unit sensors 43 synchronize with each other, and the light projection from each light projecting unit 44 is reflected by the normal part of the wafer W and received by the corresponding light receiving unit 45. Counting is started with a period of 1 millisecond. The missing portion is not reflected and is not received by the light receiving portion 45, and thus is not counted. The count of the state in which light is received by the light receiving unit 45 for each period accompanying the passage of the wafer W is accumulated in the register of the high speed calculation unit 48. Thereafter, when the rear end of the wafer W is detected by the central position unit sensor 43c, the counting in all the unit sensors 43 is stopped. A count value (counted integrated value) for each unit sensor 43 is registered in a register, and compared with a similar count value for each unit sensor 43 for a normal wafer W having no missing portion, to determine the presence or absence of the missing portion. .

  FIG. 6 is a view showing the arrangement of position sensors provided in the transfer chamber 10, and FIG. 6A shows only the position sensor 37, and the other components are not shown. 6B is a partially broken side view in the [B]-[B] line direction in A of FIG. Referring to FIGS. 6A and 6B, the transfer robot faces the loading chamber 11, the processing chamber 13, the processing chamber 14, and the unloading chamber 16 in a state where the arm is completely folded. A position sensor 37 is provided for checking the wafer W placed on the hand when the position is reached. The position sensor 37 is a transmissive optical sensor, and a light projecting portion 38 is attached to the ceiling side, and a light receiving portion 39 is attached to the bottom side together with window frames 38w and 39w with hard glass plates. When the position sensor 37 detects a wafer W that is not detected by the central position unit sensor 43c in the 20 reflection type optical sensors 41, the wafer W is determined as a missing wafer W ′.

  FIG. 7 and FIG. 8 that follow are flowcharts illustrating the process for detecting the missing wafer W ′ having the missing portion described so far, from step (1) to step (10). Since the contents of each step overlap with those described so far, the description thereof will be omitted. However, when the non-overlapping parts are described, when a missing wafer is detected and an abnormal signal is output in step (7), the vacuum processing apparatus itself When trouble has occurred, the operation of the vacuum processing apparatus in step (7) -1 is stopped and the recovery of returning the vacuum processing apparatus in step (7) -2 to the original state is performed. If no trouble has occurred in the device itself and no special operation is required, a route is taken from step (7) to step (8).

  FIG. 9 is a plan view of a normal wafer W having no missing portion, but FIG. 10 shows that the normal wafer W is thrown by the 17 unit sensors 43 of the sensor head 42 from the front end to the rear end in the transfer direction. It is a figure which shows the state in which the light projection from the optical part 44 was received by the light-receiving part 45. FIG. That is, the detection of the state of light being received by the light receiving unit 45 is started from the front end of the wafer W that passes under the 17 unit sensors 43, reaches the rear end of the wafer W, and finishes counting. Is the count value (counted integrated value) for each unit sensor 43, and 17 unit sensors 43 are arranged in the order of arrangement number on the X axis, and each unit is indicated on the Y axis. The count values of detection of the light receiving state by the light receiving unit 45 of the sensor 43 are plotted. As seen in FIG. 10, the count value of the ninth central position unit sensor 43c from the left and right from which the center of the wafer W passes below is about 540, but the unit sensor 43 that is far from the center on both sides counts. The light receiving pattern is such that the count value of the first and 17th unit sensors 43 at both ends is 210 to 220.

  On the other hand, FIG. 11 is a plan view of a missing wafer W ′ where a missing portion Wd exists on the left side after the transfer direction. FIG. 12 shows the missing wafer W ′ in the transfer direction by 17 unit sensors 43. It is the figure which showed the count value of the light reception in the light-receiving part 45 of each unit sensor 43 when detecting the state currently received by the light-receiving part 45 from the front-end | tip to the rear end similarly to FIG. As shown in FIG. 12, the count values of the fifth to eighth unit sensors 43 corresponding to the missing portion Wd of the missing wafer W ′ are small. As described above, the presence / absence of a defective portion is determined by comparing the count value of each unit sensor 43 with the count value in the case of the normal wafer W, but in practice, the difference from the count value of the normal wafer W is appropriately set. When it is within the allowable range, a signal indicating normal is output, and when the difference is larger than the allowable range, a signal indicating abnormal is output.

  FIG. 13 is a plan view of a missing wafer W ″ in which a missing portion Wd exists on the right side in the transport direction. FIG. 14 shows this missing wafer W ″ from the front end in the transport direction by 17 unit sensors 43 as well. It is the figure which showed the count value of the light reception state in the light-receiving part 35 of each unit sensor 43 when detecting the state currently received by the light-receiving part 45 until the rear end. 12, the count value of the 17th unit sensor 43 corresponding to the missing portion Wd of the missing wafer W ″ is small. In the manufacturing process, it differs from the normal wafer W as shown in FIG. By obtaining the light receiving pattern, it is determined that the missing wafer W ″ passes under the 17 unit sensors 43.

FIG. 15 is a plan view of a normal wafer Wr having no missing portion but having a large surface reflectance, and FIG. 16 is a view showing a light receiving pattern similar to that of FIG. 9 with respect to the high reflection normal wafer Wr. is there. FIG. 17 is a plan view of a normal white turbid wafer Wm that does not have a missing portion but is white in appearance and has a low surface reflectance. FIG. 18 is a plan view of the normal turbid wafer Wm shown in FIG. It is a figure which shows the same light reception pattern. As is apparent from comparison between FIGS. 16, 18 and 10 , when there is no missing portion, even if it is a highly reflective normal wafer Wr or a white turbid normal wafer Wm, the light receiving pattern thereof. Is exactly the same as that of the normal wafer W as a reference, and it can be said that the determination of the presence or absence of the missing portion Wd is not affected by the surface reflectance of the wafer or the internal transparency.

  As mentioned above, although the detection method of the to-be-conveyed body which has a missing part of this invention was demonstrated by the Example, of course, this invention is not limited by a Example, Based on the technical idea of this invention, various deformation | transformation Is possible.

For example, in the present embodiment, a vacuum processing apparatus in which a plurality of processing chambers are arranged on the outer periphery of a hexagonal transfer chamber via a gate valve is illustrated, but the vacuum processing apparatus of the present invention includes a single preparation chamber and A vacuum processing apparatus in which a single processing chamber is connected through a gate valve and a vacuum processing apparatus in which a plurality of processing chambers are connected in a straight line through a gate valve are also included.
In this example, a sensor head in which 17 unit sensors are arranged at a pitch of 11.8 mm is used for a wafer having a diameter of 200 mm. However, the diameter of the wafer may be 200 mm or more, for example, 300 mm. Moreover, 200 mm or less may be sufficient. The unit sensor arrangement pitch is not limited to 11.8 mm, and may be 10 mm pitch or 10 mm or less depending on the size of the unit sensor. That is, the upper limit of the number of unit sensors is determined by the size of the diameter of the wafer and the size of the unit sensor used.

  In this embodiment, the sputtering chamber is exemplified as the processing chamber. However, the processing chamber may be a CVD (chemical vapor deposition) chamber, a vapor deposition chamber, an ion implantation chamber, a heat treatment chamber, or a dry etching chamber. is there. Further, the semiconductor wafer is exemplified as the transported body, but the semiconductor wafer may be other than the semiconductor wafer. For example, the present invention is applied to a case where a glass plate or a ceramic thin wafer is the transported body. .

Further, in this embodiment, out of the light projected from the light projecting units of the 17 unit sensors, the presence or absence of the light reflected by the transported wafer and received by the light receiving unit is detected by the high-speed computing unit for 1 millisecond. Counting and accumulating at periodic intervals, comparing the light receiving pattern obtained from the integrated value of the counts of each of the 17 unit sensors with a similar light receiving pattern obtained with a normal wafer, and the presence or absence of a missing portion in the transferred wafer However, it is possible to detect missing wafers by other methods. When using a reflective optical sensor as in the example, the light from the light projecting part is continuously received by the light receiving part at a certain sensitivity level in the part where the wafer is not missing, and is reflected in the missing part. Since no light is received, the light receiving sensitivity level continues to be 0 level. Accordingly, the presence or absence of a missing portion in the transferred wafer is grasped as the time when the reflected light is received and the time when the reflected light is not received for each of the 17 unit sensors. By comparing with the light receiving time, it is possible to determine the presence or absence of a missing portion in the wafer being transferred.

It is a partial abbreviation top view of the vacuum processing apparatus of an example. It is sectional drawing of the [2]-[2] line direction in FIG. FIG. 2 is a cross-sectional view schematically showing an original gate valve and a gate valve to which a reflection type photosensor of the present invention is attached. It is an enlarged view which shows the upper part of the valve box of a gate valve of FIG. 2 , and a reflection type optical sensor. It is sectional drawing of the [5]-[5] line direction in FIG. It is a figure which shows arrangement | positioning of the position sensor of a conveyance chamber, A is a top view, B is a partially broken side view in the [B]-[B] line direction in A. FIG. FIG. 9 is a flowchart showing a missing wafer detection process together with FIG. 8. It is a flowchart following FIG. It is a top view of a normal wafer. It is a figure which shows the light reception pattern of the wafer. It is a top view of a missing wafer of an example. It is a figure which shows the light reception pattern of the wafer. It is a top view of the missing wafer of other examples. It is a figure which shows the light reception pattern of the wafer. It is a top view of a highly reflective normal wafer. It is a figure which shows the light reception pattern of the wafer. It is a top view of a cloudy normal wafer. It is a figure which shows the light reception pattern of the wafer. It is a figure which shows the outline of the semiconductor manufacturing apparatus of a prior art example.

Explanation of symbols

1 Single-wafer vacuum processing apparatus 10 Transfer chamber 13 Processing chamber (sputter chamber)
20 Gate valve 21 Valve box 22 Valve body 23 Low reflection SUS plate 25 Hard glass plate 31 Transfer robot 33 Arm 34 Hand
37 Position sensor 41 Reflection type optical sensor
42 Sensor head 43 Unit sensor
44 Light Emitting Unit 45 Light Receiving Unit 48 High Speed Computing Unit W Wafer

Claims (2)

The first chamber and the second chamber of the vacuum processing apparatus are connected via a gate valve, and are included in the transported body that is transported one by one between the first chamber and the second chamber. A method of detecting a missing transported body having a missing portion to be detected during transport of the missing transported body,
1. A large number of unit sensors are arranged at equal intervals in a direction perpendicular to the transport direction of the transported body so that the width is equal to or greater than the width of the transported body, and the adjacent unit sensors are different from each other. Detecting the tip of the object to be transported by an optical sensor using a combination of a light projecting unit and a light receiving unit using light of a wavelength capable of identifying
2. Based on the detection of the tip, all the unit sensors are synchronized, and detection of whether or not the light projection from the light projecting unit is received by the light receiving unit is started at a very short constant cycle, The state where the light projection is received by the light receiving unit due to reflection by the normal part of the transported body, or the state where the light projection is not received by the light receiving unit due to interruption by the normal part of the transported body is counted. And accumulating the count;
3. Detecting the rear end of the conveyed object by the optical sensor, and stopping the counting;
4). The light receiving pattern or non-light receiving pattern formed from the count value (counted integrated value) accumulated for each unit sensor is compared with a similar light receiving pattern or non-light receiving pattern for a normal transported body, and the missing portion And a step of detecting the missing carrier by determining the presence or absence of the missing carrier.   2. The missing transferred object according to claim 1, wherein the first chamber is a transfer chamber of the vacuum processing apparatus, the second chamber is a process chamber of the vacuum processing apparatus, and the transferred object is a semiconductor wafer. Detection method.

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