JPH0736446U - Wafer lifetime measuring device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To provide a lifetime measuring apparatus in which there is no fear of misalignment when a wafer is placed on a stage and the measurable wafer has a wide dimensional range. [Structure] A through hole 8 is provided in the center of a movable table 2 and a stage 1 provided thereon, and a pipe 3 is provided in the through hole 8 so as to be able to move up and down by elevating devices 26 and 31, and suction is applied to the pipe 3. A vacuum suction device is connected via a tube 30.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a wafer lifetime measuring apparatus.

[0002]

[Prior art]

 Energy from an external energy source is applied to the wafer placed on the stage, carriers are generated in the wafer by this energy, the attenuation characteristics of the generated carriers are measured, and the lifetime of the wafer is measured from the measured attenuation characteristics. It is known how to measure. (See, for example, JP-A-61-101045, JP-A-61-114543, and JP-A-2-248062)

The basic configuration of the apparatus used in the above-mentioned wafer lifetime measuring method is, as shown in the outline in FIG. 2, a microwave device 37, a laser element 38, and a wafer W installed on a frame 36. The microwave generator (not shown), the microwave waveguide 40, and the laser element 38 that constitute the microwave device 37 are configured so as not to vibrate in order to perform stable measurement. The microwave device 37, the microwave from the laser element 38, and the irradiation position (measurement point) of the laser light are usually fixed.

On the other hand, the stage 39 is usually mounted on a moving base (not shown) and horizontally moved in both the X-axis and Y-axis directions together with the moving base by a device for driving the moving base. There is one that horizontally moves in one direction of the Y-axis and rotates, and this movement allows the entire surface of the wafer W to be moved to a fixed irradiation position for measurement. An insulator 41 is provided on the upper surface of the stage 39.

Further, as shown in FIG. 3, the lifetime measuring apparatus having the above-described configuration includes a room temperature type (see FIG. 3b) for measuring the wafer W at room temperature without incorporating a heating means in the stage 39, and a stage 39. There is a heating type (see FIG. 3c) in which a heater 42 is incorporated in the wafer W and the wafer W is heated to a predetermined temperature (about 200 ° C.) and measured.

By the way, in order to measure the lifetime of the wafer W by the lifetime measuring apparatus, the wafers W are transferred one by one from the storage yard to a predetermined position on the stage 39 and placed after the measurement. The wafer W after the measurement needs to be taken out from the stage 39 to the storage yard. This transfer requires a pre-process for centering and orientation adjustment before placing the wafer W on the stage 39, so that it can be engaged with the adjustment table used in this pre-process. A transfer hand 45 having a forked end 43 with a forked end as shown in FIG. 2 and an opening 44 connected to a vacuum suction device (not shown) is generally provided on the upper surface of the base of the fork end 43. Used for. In the case of a room temperature type lifetime measuring apparatus, the stage 39 is formed to have a diameter (d) smaller than the fork end 43 (R × 2) of the fork end 43 of the transfer hand 45 and the wafer W without any trouble. A stage 39 having a diameter capable of being mounted is generally used, and the lifetime of the wafer W is measured. (See Figure 3a)

However, in the case of the temperature rising type lifetime measuring apparatus, in order to uniformly heat and hold the wafer W at a predetermined temperature, the diameter of the stage 39 needs to be substantially the same as the diameter of the wafer W. For this reason, the transfer hand 45 cannot be used like the above-mentioned normal temperature type lifetime measuring device, and as shown in FIG. 3c, the insulator 46, the stage substrate 47, the heater 48, and the heater constituting the stage 39 are formed. The pressing plate 49, the heat insulating material 50, and the movable table 51 are provided with three to four through-holes 52 on the concentric circumference, and the through-holes 52 are provided with vertically movable wafer support pins 53. To place the wafer W on the stage 39, the wafer W on the transfer hand 45 is supported by raising the wafer support pins 53, and then the transfer hand 45 is retracted to support the wafer W. When the wafer W is placed on a predetermined position on the stage 39 by lowering the pin 53 and then the wafer W on the stage 39 is taken out after measurement, the wafer support pin 53 is raised and the wafer W is placed above the stage 39. Wafer W after being pushed up and supported Is advanced to transfer hand 45 between the stage 39, then, so that taken out in favor of the wafer W on the transfer hand 45 by lowering the wafer support pins 53. Even in the case of the room temperature type lifetime measuring device described above, the diameter of the stage 39 is the diameter of the wafer W when it is necessary to prevent the wafer W from bending and make the microwave reflection state more uniform. In some cases, the diameter may be set to be almost the same.

[0008]

[Problems to be solved by the device]

 However, when the stage 39 is provided with a plurality of through-holes 52 and the wafer support pins 53 that can be moved up and down are provided in the stage 39 like the above-mentioned temperature rising type lifetime measuring apparatus, the wafer support pins 53 are the forks of the transfer hand 45. Since the outer diameter of the wafer W is smaller than the concentric circumference outside the end 43, the wafer W having a smaller outer diameter cannot be measured, and the measurable range of the wafer W is narrowed. Further, since the wafer support pin 53 becomes a hindrance to the rotation, the method of moving the stage 39 in any one of the X-axis and the Y-axis and rotating in one direction has a complicated rotation mechanism. Next, it becomes difficult to hire. In addition, when the wafer W is placed on the wafer support pins 53 from the transfer hand 45 or while being lowered onto the stage 39, the wafer W is liable to be laterally displaced due to a slight shock or vibration. When placed on the upper surface, air may remain between the mirror-finished upper surface of the stage 39 and the lower surface of the wafer W, causing a misalignment. There is a problem such as.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to drive a stage in which movement and rotation in one axis direction, which can be relatively compact, are combined. It is to provide a lifetime measuring device which can adopt the method, has no misalignment when mounting the wafer on the stage, and has a wide measurable wafer size range.

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, the wafer lifetime measuring apparatus according to the present invention is provided with a through hole at the center of a moving table and a stage provided on the moving table, and a tube can be moved up and down by an elevating device in the through hole. And a vacuum suction device is connected to this tube.

Further, in the above wafer lifetime measuring apparatus, a void cutting groove may be formed on the upper surface of the stage.

Further, in the above-mentioned wafer lifetime measuring apparatus, the tube may be connected with an air supply device and a vacuum suction device via a switching valve.

[0013]

[Action]

 In the above invention, a through hole is provided in the center of the stage, and a pipe connected to a vacuum suction device is provided in the through hole so that the pipe can be moved up and down. Therefore, the stage and the pipe are integrally moved in one axial direction. And can be rotated. In addition, since the tube is connected to the vacuum suction device, when the wafer is moved from the transfer hand to the stage and placed, the lower part of the wafer is sucked down and firmly held by the tube, and then it is lowered and held. Since it is placed on the top surface of the J, there is no misalignment. Also, since the tube is installed only in the center of the stage and moves up and down while holding the center of the lower surface of the wafer, wafers with the smallest diameter that can be placed on the transfer hand can be handled without any problems, and the measurable wafer size range Can be widened.

Further, by forming a vacuum kerf except in the central portion of the upper surface of the stage, proper adhesion between the wafer and the upper surface of the stage due to vacuum suction is obtained in the central portion of the stage, and at the same time, wafer separation after lifetime measurement is performed. Can be done easily.

[0015]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front sectional view of a lifetime measuring apparatus according to the present invention, in which a microwave device, a laser element, and their supporting bases are omitted. In the figure, 1 is a stage, 2 is a moving base, and 3 is a moving base. Shows the up and down pipe.

The stage 1 is composed of a disk in which an insulator 4, a stage body 5, a heater 6 and a heater retainer 7 are laminated from the top, a through hole 8 is provided in the center thereof, and the insulator 4 has an upper surface. Is provided with a predetermined number of vacuum kerfs 9 which are open to the outer peripheral edge.

The moving table 2 has a moving frame 11 in which a cylindrical body 10 is erected in the center and a flange 13 at the upper end rotatably provided in the cylindrical body 10 with a bear ring 12 interposed therebetween. 2 cylindrical bodies 14 are provided so that a bearing block 15 provided on the lower surface of the movable base 11 is engaged with a rail 16 so as to be movable in one direction (X-axis direction), and a lower portion of the second cylindrical body 14 is provided. A belt 21 is provided between the pulley 17 fitted to the outer periphery and the pulley 20 of the turning stepping motor 19 provided on the movable base 11 via the bracket 18, so that the second cylindrical body 14 can be turned. Is configured as follows. The stage 1 is attached to the flange 13 of the second cylindrical body 14 with a bolt 22.

The hoisting pipe 3 integrally has a support portion 23 having an enlarged diameter at its upper end, and an insulator 24 is applied to its upper end surface. The up-and-down tube 3 is inserted into the through hole 8 of the stage 1 and the second cylindrical body 14, receives the supporting portion 23 by the flange 25 of the through hole 8, and supports the compressing spring 26 and the stop ring from below. 27 are inserted and the spring force of the compression spring 26 causes the compression spring 26 to be embedded in the through hole 8. Further, the block 29 is slidably supported by a bearing portion 28 provided in the lower portion of the second cylindrical body 14 and concentric with the through hole 8 and has an L-shaped through hole at its lower end. Is installed.

Incidentally, 30 is a suction pipe connected to a suction device (not shown), and 31 is a push-up cylinder for pushing up the hoisting pipe 3.

The lifetime measurement of the wafer W by the lifetime measuring device having the above configuration is performed as follows. The push-up cylinder 31 is operated to raise the piston 32 to raise the support portion 23 of the up-and-down tube 3 to a predetermined height for receiving the wafer W, while transferring the pretreated wafer W to the transfer hand 45 (the same structure as the conventional one). ), And stop advancing to a predetermined position above the supporting portion 23 (stage 1). The vacuum suction of the elevating tube 3 is started and the transfer hand 45 is lowered. By this lowering, the wafer W is stably placed on the upper end surface of the supporting portion 23 of the elevating tube 3. The transfer hand 45 puts the wafer W on the upper end surface of the support portion 23, and then retracts. The push-up cylinder 31 is operated to lower the piston 32. Due to this lowering, the spring force of the compression belt 26 causes the supporting portion 23 to lower to the same height as the upper surface of the stage 1, and the wafer W is placed on the upper surface of the stage 1. In this mounting, since the supporting portion 23 holds the wafer W while sucking it, the air between the upper surface of the stage 1 and the lower surface of the wafer W is sucked and the wafer W can be closely attached. Further, the stage 1 can be placed at a predetermined position on the upper surface of the stage 1 without causing any misalignment. After the placement, a predetermined lifetime measurement is performed while continuing vacuum suction. In this measurement, the procedure for moving the measurement point of the wafer W to the irradiation position (measurement point) of the microwave device and the laser element is to move the moving base 11 through the bearing block 15 along the rail 16 by a driving device (not shown). This is performed by rotating the stage 1 together with the second cylindrical body 14 by driving the rotating stepping motor 19 while moving in the direction. These movements and rotations are generally performed by a controller (not shown).

After the above-described measurement, the procedure for taking out the wafer W from the stage 1 is performed by releasing the contact since the wafer W is in close contact with the upper surface of the stage 1. That is, the push-up cylinder 31 is actuated, the piston 32 is raised, and the support portion 23 of the lifting tube 3 is slightly raised, so that the wafer W can be separated from the upper surface of the stage 1. After this separation, the wafer W is sucked and held on the upper end surface of the supporting portion 23 by vacuum suction and raised to a predetermined height. Next, the transfer hand 45 is advanced to the lower surface of the wafer W, the vacuum suction is stopped, the transfer hand 45 is raised, and the wafer W is placed on the transfer hand 45 and retracted.

As described above, the operation of placing the wafer W from the transfer hand 45 on the upper surface of the stage 1 and taking out the wafer W from the upper surface of the stage 1 to the transfer hand 45 is performed by vacuum suction by the support portion 23 of the up-and-down tube 3. Since it is performed, the outer diameter of the support portion 23 can be made small to stably hold the wafer W, and thus the diameter of the adjusting table used in the pretreatment (mainly depending on the maximum diameter of the wafer W to be handled) is determined. The wafer W having the smallest diameter that can be stably placed on the fork end 43 of the transfer hand 45 can be handled without any trouble.

In the above embodiment, the temperature rising type life time measuring device in which the heater 6 is incorporated in the stage 1 has been described as an example, but the present invention is not limited to this example, and the heater 6 is not limited thereto. Also, the same effect as the above can be obtained even if it is a normal temperature type lifetime measuring device which does not include the heater holder 7 or such a normal temperature type lifetime measuring device.

Further, in the above embodiment, the heater 6 is incorporated in the stage 1, and when the life time of the wafer W is measured at room temperature, the heater 6 is turned off. Further, when the temperature is raised, the heater 6 can be set to a desired temperature by the controller, and both the room temperature type and the temperature raising type can be used.

Further, in the above-described embodiment, an example has been described in which the ascending / descending drive of the ascending / descending tube 3 is performed by ascending by the pushing-up cylinder 31 and descending by the compression spring 26, but the present invention is not limited to this example. Instead of the push-up cylinder 31, a pulse motor may be provided and a pinion and a rack that meshes with the pinion may be combined with the output shaft of the motor, or a cam may be provided on the output shaft of the motor. When the pulse motor is used in this way, the push-up speed and position of the hoisting pipe 3 can be accurately controlled.

Further, in the above-described embodiment, as a preferred example, an example in which a predetermined number of vacuum cut grooves 9 are radially provided on the upper surface of the insulator 4 of the stage 1 has been described, but the present invention is not limited to this example. Alternatively, the vacuum kerf 9 may be omitted, and even in such a case, the closely attached wafer W can be separated from the upper surface of the stage 1 by the above-described separation procedure. Further, the example in which only the suction device is provided in the hoisting pipe 3 via the suction pipe 30 has been described, but a switching valve may be provided in the hoisting pipe 3 or the suction pipe 30 and an air supply device may be provided side by side. In this case, When separating the adhered wafer W from the upper surface of the stage 1, the separation is facilitated by switching to the air supply device by the switching valve.

[0027]

[Effect of device]

 As described above, in the wafer lifetime measuring apparatus according to the present invention, a stage drive system that combines movement and rotation in one axis direction can be adopted. Also, since the tube is connected to a vacuum suction device, when the wafer is transferred from the transfer hand to the stage and placed on it, the central part of the lower surface of the wafer is suctioned by the tube and firmly held on the stage. It can be lowered, and it can be placed on the upper surface of the mirror-finished stage without misalignment. In addition, since the tube is installed only in the center of the stage and moves up and down while holding the center of the lower surface of the wafer, wafers with the smallest diameter that can be placed on the transfer hand can be handled without any problems, and the measurable wafer size range is limited. Can be widened.

[Brief description of drawings]

FIG. 1 is a front sectional view of a wafer lifetime measuring apparatus according to the present invention, in which a microwave device, a laser element, and a support frame for these elements are omitted.

FIG. 2 is a basic configuration diagram of a conventional wafer lifetime measuring apparatus.

FIG. 3 is an explanatory view of a stage structure of a conventional wafer lifetime measuring apparatus, in which a is a room temperature type top view and b is a.
And a side view of the temperature rising type is shown.

FIG. 4 is a top view of a transfer hand.

[Explanation of symbols]

1: Stage 2: Mobile stand 3:
Hoisting pipe 4: Insulator 5: Stage body 6:
Heater 7: Heater holder 8: Through hole 9:
Vacuum kerf 10: Cylindrical body 11: Mobile stand 12:
Bearing 13: Flange 14: Second cylinder 15:
Bearing block 16: Rails 17, 20: Pulley 18:
Bracket 19: Stepping motor 21: Belt 22:
Bolt 23: Support 24: Insulator 25:
Brim 26: Compression spring 27: Stop ring 28:
Bearing part 29: Block 30: Suction tube 31:
Lifting cylinder 32: Piston

Claims (3)

[Scope of utility model registration request] 1. A through hole is provided in a central portion of a movable table and a stage provided thereon, and a tube is provided in the through hole so that the tube can be moved up and down by an elevating device, and a vacuum suction device is connected to the tube. A wafer lifetime measuring device characterized in that 2. The wafer lifetime measuring apparatus according to claim 1, wherein a vacuum kerf is formed on the upper surface of the stage. 3. The wafer lifetime measuring apparatus according to claim 1, wherein an air supply device and a vacuum suction device are connected to the tube via a switching valve.