JP4320802B2 - Microscope with electric stage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a microscope with an electric stage for observing an inspection object such as a silicon wafer, and in particular, it is possible to set an optimum stage movable range for an inspection object having a plurality of types and sizes. It relates to a microscope.
[0002]
[Prior art]
The wafer inspection apparatus includes a macro inspection unit that observes the entire wafer taken upside down, for example, by inverting the wafer taken out of the wafer carrier, and a micro inspection microscope unit that optically enlarges and inspects the wafer. The microscope part in the conventional wafer inspection apparatus is to place the wafer as the inspection object on the stage, and move the stage electrically or manually to move the desired observation part of the inspection object into the field of view of the microscope. It is necessary.
[0003]
In that case, the stage driven by electric power generally has a movable range determined in advance by the specification, and the movable range is fixed, and in many cases, the stage is a square that covers the entire range of the maximum inspection object. Set to range. Then, in response to the operator operating the stage operation means such as a joystick, the stage moves in the X direction and the Y direction within the above movable range. Also in the case of manual operation, the stage can be freely moved within the movable range.
[0004]
[Problems to be solved by the invention]
However, if the size of the object to be inspected is smaller than the movable range of the stage, moving the stage with the joystick may cause the visual field range to be outside the object to be inspected, so the operator carefully moves the stage. It is necessary to let In particular, when it is desired to observe the inspection object at a high magnification, when the field of view of the microscope protrudes outside the inspection object, the stage is moved again so as to be positioned at a desired site on the inspection object. It is difficult as long as observation is performed through a high-magnification optical system. Also, when operating the joystick with a high magnification, it is difficult to smoothly operate to the position of the desired observation site unless the stage moving speed is set to a low speed, and if the stage moving speed is set to a low speed, Travel time is longer. Therefore, it is necessary to operate the joystick while observing at a low magnification once, move the stage, confirm that it has moved to the vicinity of the desired observation site, switch to a high magnification, and move and adjust the minute range. Yes, the operation becomes complicated.
[0005]
Further, when observing a silicon wafer, the movable range of the stage is set for an 8-inch wafer having a maximum shape, for example. When a 6-inch or 4-inch wafer is observed with such a microscope, the stage can be driven until the field of view is outside the wafer shape, and the same problem as described above remains.
[0006]
Further, in the observation of the wafer, there are a request for observation along the periphery of the wafer, a request for observation along the edge of the chip on which the pattern in the wafer is printed, and the like. Even in such a case, if the movable range of the stage is wider than the end or surrounding shape to be observed, in order to perform observation along the end or surrounding to be observed, the stage is moved at a low speed while observing at a high magnification. Or moving at a low magnification and repeating the operation of switching to a high magnification.
[0007]
A system has been developed that automatically moves to the observation range or part by displaying the object to be inspected on a monitor screen using a personal computer and specifying the range and part to be observed. Such a system is large and increases the cost of the inspection device.
[0008]
Therefore, the object of the present invention is to variably set the movable range of the stage according to the size, shape or predetermined inspection range of the object to be inspected without increasing the cost, thereby improving the operability by the operator. The object is to provide a microscope with an electric stage.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a microscope having a stage that can be driven in the XY directions and an optical system that expands an object to be inspected placed on the stage.
In response to a driving operation input, the stage is instructed to be driven, the stage position information is received, the stage movable range is determined according to the input information related to the inspection range of the inspection object, and the stage is moved out of the stage movable range. A stage drive control unit for prohibiting the drive of the stage in response to the drive operation input instructing movement of the stage.
[0010]
According to the above invention, the movable range of the stage is set according to the inspection range of the object to be inspected, and movement outside the range is prohibited. The range is prevented from moving outside the inspection range of the object to be inspected, and the operability can be improved. In addition, when it is necessary to perform inspection along the periphery of the inspection range, the operability is further improved.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. However, such an embodiment does not limit the technical scope of the present invention.
[0012]
FIG. 1 is an overall configuration diagram of a wafer inspection apparatus having a microscope with an electric stage according to the present invention. The wafer inspection apparatus 100 includes a carrier mounting mechanism unit 20 that mounts the wafer carrier 21, a macro inspection mechanism unit 30 that visually inspects the front and back surfaces of the wafer 60, and a microscope that performs micro inspection by enlarging the surface of the wafer 60. 10. The wafer inspection apparatus 100 shown in FIG. 1 is usually placed on a work desk, and an operator sits in front of a microscope and operates buttons and a joystick 52 of the operation unit 50.
[0013]
The plurality of wafers housed in the wafer carrier 21 are taken out by the first transport mechanism 34 and placed on the buffer unit 32 having the suction unit. The buffer unit 32 directs the front surface or back surface of the wafer 60 toward the operator as necessary. The state is illuminated by the illumination device 62, and the operator can perform the macro inspection while sitting at the position of the microscope. Thereafter, the second transport mechanism 36 receives the wafer 60 from the buffer unit 32 and places it on a syringe (not shown) of the stage 12 of the microscope 10. The wafer is sucked and fixed by a syringe, and the movement of the stage 12 moves the desired observation position of the wafer within the field of view of the microscope.
[0014]
The stage provided in the microscope 10 can be moved in the X direction and the Y direction by an electric driving means (not shown). When the operator operates the joystick 52 in a desired direction, a stage drive control unit (not shown) moves the stage 12 in that direction.
[0015]
FIG. 2 is a diagram showing a stage and a stage drive control unit in the present embodiment. The stage 12 includes an X drive means 13X having a drive motor for driving in the X direction and a rotary encoder for detecting the movement distance, and a Y drive having a drive motor for driving in the Y direction and a rotary encoder for detecting the movement distance. Means 13Y, a sensor 14X for detecting the origin of the stage in the X direction, a sensor 14Y for detecting the origin of the stage in the Y direction, and a reflective sensor for detecting the size of the wafer 60 which is an inspection object placed on the syringe 15 16 are provided.
[0016]
The wafer 60 placed on the second transfer mechanism 36 shown in FIG. 1 is placed on the syringe 15 of the stage 12 so that the center of the wafer is located substantially at the center of the syringe.
[0017]
The stage drive control unit 70 is a control unit using a microcomputer, for example. That is, the memory unit 73 in which the stage drive control program is recorded and the CPU 72 that executes the program are connected via a common bus 71. Further, an interface 74 connected to the stage sensors 14X, 14Y, 16 and the driving means 13X, 13Y and an interface 76 connected to the operation unit joystick 52, the operation button 53, and the like are also connected via the bus 71. .
[0018]
In accordance with the stage drive control program, the stage drive control unit 70 receives the position information of the stage origin from the sensors 14X and 14Y and the movement amount information from the drive means 13X and 13Y, as will be described later, and always determines the current position of the stage 12. Recognize and record in the memory unit 73. Further, the diameter of the wafer 60 is detected according to the detection signal from the sensor 16, the stage movable range is determined according to the inspection range designation information for designating the shape of the stage movable range from the operation button 53, and necessary information is stored in the memory. Record in part 73. Then, in response to an operation signal in a predetermined direction from the joystick 52, the drive means 13X and 13Y are instructed to drive the stage within the determined stage movable range.
[0019]
Information on the diameter of the wafer 60 may be detected while the wafer is being transferred by the wafer transfer mechanisms 34 and 36 in the macro inspection mechanism unit 30 shown in FIG. In that case, wafer size information from the macro inspection mechanism 30 is supplied via the communication line and the interface 75.
[0020]
FIG. 3 is a diagram illustrating an example of the stage movable range. For example, when an 8-inch wafer is placed on the stage, the sensor 16 detects the wafer size. According to the information from the sensor 16, the stage drive control unit 70 sets the stage movable range as a circular area 64 of 8 inches. Here, it is assumed that the stage movable range is a circular area when there is no specific instruction from an operation button or the like. Then, it is determined whether or not the position after movement exceeds the stage movable range 64 from the current stage position that is constantly monitored and the operation signal from the joystick 52, and if so, the drive of the stage 12 is prohibited. Is done. That is, even if the operator operates the joystick 52, the stage is not driven in a direction in which the visual field range exceeds the stage movable range 64.
[0021]
Next, when the 6-inch wafer 61 is placed on the stage, the reflective sensor 16 detects the size. According to the information from the sensor 16, the stage drive control unit 70 sets the stage movable range as a circular area 62 of 6 inches. Similarly to the above, the driving of the stage is limited to the set stage movable range 62.
[0022]
FIG. 4 is a diagram illustrating another example in which the shape of the stage movable range is different. In FIG. 3, a circular area along the outer periphery of the wafer is set as the stage movable range, whereas in the example of FIG. 4, a rectangular shape 66 surrounding the die pattern 65 on which the exposure pattern in the wafer is printed is formed. The stage movable range is set. For this purpose, the operator moves the four points a, b, c, and d within the field of view of the microscope, and supplies the coordinates of each point to the stage drive controller 70. When the stage movable range is designated to be rectangular by the operation button 53 or the like, the stage movable range 66 shown in FIG. 4 is set from the coordinates of the four points.
[0023]
Alternatively, when the position of the die pattern to be baked is known in advance with respect to the shape of the wafer, the rectangular area can be automatically set according to the detected wafer diameter size.
[0024]
In this way, when the coordinates of a predetermined point that defines the inspection range are supplied by the operator's stage drive, a predetermined region in the wafer as the inspection object is designated as the inspection region, and the field of view of the microscope is The stage movable range can be set so as not to deviate from the inspection area. In the example of FIG. 4, the stage movable range is set in the region where the die pattern 65 is formed. Therefore, the operability can be improved when it is desired to inspect around the pattern around the die pattern 65.
[0025]
FIG. 5 is a flowchart of the stage drive control program. The point that the drive of the stage is limited within the stage movable range will be described according to this flowchart. After the power is turned on, the electric stage 12 is driven to a predetermined end of the movable range by the X and Y driving means 13, and the stage drive control unit 70 detects the reference point (origin) of the stage 12 based on the signal from the sensor 14, The data is recorded in the memory unit 73 (S10). Further, the stage drive control unit 70 detects the diameter of the wafer 60 placed on the stage 12 based on a signal from the sensor 16 (S12). Since the types of diameters of the wafer 60 are determined to be, for example, 8 inches, 6 inches, 5 inches, and 4 inches, as shown in FIG. 2, a reflective sensor is provided at a position sandwiching the outer peripheral edge of each size wafer. By arranging 16, it is possible to detect which diameter the wafer is.
[0026]
In the example of FIG. 5, if the wafer is 6 inches, step S <b> 14 and the subsequent steps are executed, and if the wafer is 8 inches, the steps S <b> 16 and the subsequent steps are executed. Assuming that the wafer size is 6 inches, the stage drive controller 70 sets the movable range of the stage to a circle 62 in FIG. That is, stage movable range setting data with a radius R = 3 inches is recorded in the memory unit 73. Alternatively, as described above, when an operation signal indicating that the position of the predetermined four points in the wafer is supplied and the rectangular range is set is supplied by the operator's operation, the movable range of the stage is 66 in FIG. Such a rectangular area is set. That is, stage movable range setting data in which the X coordinate is from A to B and the Y coordinate is from C to D is recorded in the memory unit 73 (S18). Pattern 1 in FIG. 5 means the movable area 62 or the movable area 66 described above.
[0027]
Therefore, when the stage drive operation is performed by the operator using the joystick 52 (S20), the stage drive control unit 70 moves to the stage drive operation signal direction from the current stage coordinates, and the stage coordinates (X, Y). Is determined to exceed the stage movable range of pattern 1 (S22). For example, if the stage movable range is set to a circle having a radius R, it is determined whether X ² + Y ² <R ² . If the stage movable range is set to the rectangular range, it is determined whether A <X <B and C <Y <D. If the movable range is not exceeded, in response to the supplied stage drive operation signal, a drive signal is given to the drive means 13 to drive the stage 12 in the instructed direction (S24). If it exceeds the movable range, the stage drive is stopped regardless of the supplied stage drive operation signal (S26).
[0028]
Said process S20, S22, S24, S26 is repeated for every predetermined sampling period. Therefore, even if the stage starts to be driven once in response to the drive operation signal, if the stage is further driven halfway, the stage is stopped when it exceeds the stage movable range (pattern 1). In other words, when the operator continues to operate the joystick in a desired direction, the stage can be moved to the end position of the stage movable range and automatically stopped. Further driving is prohibited regardless of the driving operation.
[0029]
Even when the wafer size is 8 inches, the drive control is the same as in the case of 6 inches. Whether or not the coordinates (X, Y) of the stage when it is moved from the current position exceeds the stage movable range (pattern 2) is set to the pattern 2 which is the wafer movable range corresponding to the wafer size of 8 inches. Is checked (S32), and if it exceeds, the driving operation of further stages is stopped (S26).
[0030]
【The invention's effect】
As described above, according to the present invention, the stage movable range can be set to the inspection range according to the size of the inspection object or a desired inspection range, and when an operation exceeding the set movable range is given, the stage The operation of the microscope is stopped, so that even if the operator performs an operation using a joystick, the field of view of the microscope is not shifted outside the inspection object or outside the desired inspection range, improving operability. can do. Further, when it is desired to observe the periphery of the object to be inspected, or when it is desired to observe the periphery of a specific inspection range, the field of view of the microscope stops at the peripheral position, so that the operability can be improved.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a wafer inspection apparatus having a microscope with an electric stage according to the present invention.
FIG. 2 is a diagram showing a stage and a stage drive control unit in the embodiment.
FIG. 3 is a diagram illustrating an example of a stage movable range.
FIG. 4 is a diagram showing another example of the stage movable range.
FIG. 5 is a flowchart of a stage drive control program.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Microscope 12 Stage 13 Stage drive means 14 and 16 Sensor 52 Joystick 70 for stage drive operation Stage drive control part

Claims (3)

In a microscope having a stage that can be driven in the XY direction and an optical system that expands a semiconductor wafer that is placed on the stage and has an exposure pattern ,
Means for detecting the size of the semiconductor wafer;
In response to a drive operation input, the drive of the stage is instructed, and the position information of the exposure pattern with respect to the shape of the semiconductor wafer is included. The position information of the stage, the detected wafer size information, and the semiconductor wafer Based on the position information of the exposure pattern with respect to the shape, the stage movable range is determined so that the region corresponding to the exposure pattern on the semiconductor wafer becomes the visual field range of the microscope, and the movement outside the stage movable range is performed. An electric stage-equipped microscope, comprising: a stage drive control unit that prohibits driving of the stage in response to the drive operation input to be instructed. In claim 1 ,
A transport mechanism for transporting the semiconductor wafer onto the stage;
It said means for detecting the size of the semiconductor wafer, the semiconductor wafer is motorized stage with a microscope, characterized by detecting the size of the semiconductor wafer until placed on the stage. In claim 1 or 2 ,
The semiconductor wafer is substantially circular;
The stage-movable range is a range surrounding the exposure pattern having a rectangular shape in the semiconductor wafer.

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