KR100803758B1 - An inspection device for semiconductor wafer - Google Patents

Abstract

An apparatus for inspecting a semiconductor wafer is provided to improve inspection precision by minimizing a position difference between scanning by a line camera and photographing by an area camera. A cassette table(10) on which a cassette(K) having a plurality of wafers(W) is placed is installed on a side of the upper portion of a frame(1). An X-Y stage is installed on the frame, and a wafer taken out from the cassette is placed on the X-Y stage and is transferred in a zigzag type in the X-Y direction. A robot(30) loads/unloads a wafer between the cassette and the X-Y stage. A camera unit(40) includes at least one line camera(C1), an area camera(C2) and infrared lamps, fixed to the frame. The line camera scans a wafer transferred by the X-Y stage. The area camera photographs a defect position found by the line camera. The infrared lamps correspond to the line camera and the area camera. The image photographed by the area camera is displayed by a monitor(50) to an operator that determines whether the wafer is good or bad. A plurality of line cameras can vertically be installed with respect to the transfer path of the wafer.

Description

Semiconductor wafer inspection device {An inspection device for semiconductor wafer}

1 is a perspective view of a semiconductor wafer inspection apparatus according to the present invention;

2 is a front view of a semiconductor wafer inspection apparatus according to the present invention;

3 is a side view of a semiconductor wafer inspection apparatus according to the present invention.

4 is a plan view of a semiconductor wafer inspection apparatus according to the present invention;

5 is a plan view schematically showing a movement path of the wafer, that is, a scan path of the camera in the inspection apparatus of the present invention.

* Explanation of symbols for main parts of the drawings

1 frame 10 cassette table

20: X-Y stage 21: X axis rail

22: linear servomotor 23: lower plate

24: Y-axis rail 25: linear servomotor

26: upper plate 27: seating portion

30: robot 40: camera unit

41,42,43: Clamp 44,45,46: Positioner

50: monitor C1, C1 ': line camera

C2: Area Camera K: Cassette

L1, L1'L2: Infrared lamp W: Wafer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer inspection apparatus. In detail, the wafer is placed on the XY axis to prevent a decrease in inspection accuracy due to positional deviation that may occur due to starting torque when the wafer is placed and rotated on the turntable. Place it on the moving XY stage and move in a zigzag state in the XY direction to scan with a fixed camera, but install a plurality of line cameras at right angles to the wafer's movement path. By outputting it to the screen, the operator can check this and determine the quantity / defect of the wafer.

In general, semiconductor chips are packaged by forming micropatterns on silicon wafers and then cutting them into individual sizes. Before the formation of the micropatterns, a semiconductor chip is formed of defects or scratches and air pockets on the wafer surface or inside the wafer surface. By inspecting for defects in the same wafer, the yield can be increased.

Inspection of the surface and inside of such a wafer can find out which process is a problem in the wafer's manufacturing line, thereby not only providing effective countermeasures for equipment manufacturing and processing, but also improving yield.

On the other hand, defects on the surface and inside of these wafers are visually inspected by an operator by enlarging an image of a part which is expected to be defective by using a normal optical device, that is, a camera. In the related art, a wafer is placed on a turn table. Since the coordinates of the defective parts are memorized by scanning with the scanning camera while rotating them, the photographing camera can take a picture and enlarge it on the monitor to determine whether there is a defect. Since the driving part and the power transmission part of the turntable which use the sine are using the gears and bearings with the clearance, the existence of such clearance inevitably causes the position deviation that the coordinates of the actual scanned point and the photographing point do not coincide completely. Of the inspection accuracy due to position deviation And it was followed by.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a wafer inspection apparatus of a novel method that can solve the problem of deterioration of inspection accuracy due to positional deviation.

In order to achieve the above object, the present invention provides an apparatus for photographing and inspecting a wafer surface and an internal defect, ie, a defect in the wafer surface such as dust, scratches, and air pockets that adhere to the wafer surface. Provided is a semiconductor wafer inspection apparatus which minimizes the occurrence of positional deviation due to the starting torque by placing on the XY stage moved in the axis and scanning in a fixed camera while moving in a zigzag state in the XY direction. A cassette table having a cassette loaded with a plurality of wafers on one side, an XY stage where the wafers drawn from the cassette are placed and moved in a zigzag state in the XY direction, a robot for loading and unloading wafers, and an XY stage At least one line to scan the wafer being moved by A camera unit including a camera, an area camera photographing a defective position found in this line camera, and an infrared lamp corresponding to each of these cameras, and an image captured by the area camera is shown to an operator who judges whether a wafer is defective or not. It is made by including a monitor.

Hereinafter, with reference to the accompanying drawings, preferred embodiments that do not limit the present invention will be described in detail.

1 to 4 are a perspective view, a front view, a side view, and a plan view, respectively, of a semiconductor wafer inspection apparatus according to the present invention, and FIG. 5 schematically shows a wafer movement path, that is, a scan path of a camera, in the inspection apparatus of the present invention. Top view.

1 to 5, the semiconductor wafer inspection apparatus of the present invention includes a cassette table 10 having a cassette K on which a plurality of wafers W are placed on an upper side of the frame 1; ; An X-Y stage 20 installed above the frame 1, the wafer W drawn from the cassette K being placed and moved in a zigzag state in the X-Y direction; A robot (30) for loading and unloading the wafer (W) between the cassette (K) and the X-Y stage (20); At least one line camera C1 fixed to the frame 1 to scan the wafer W moved by the XY stage 20, and an area camera which photographs a defective position found in the line camera C1. A camera unit 40 including C2) and infrared lamps L1 and L2 corresponding to these cameras C1 and C2, respectively; And a monitor 50 for displaying the image photographed by the area camera C2 to an operator who determines the amount / defect of the wafer.

Inside the frame 1, a control box (not shown) for controlling the apparatus of the present invention, including the main body 31 of the robot 30, is embedded, and a cassette table 10 constituting the present invention thereon. ), The XY stage 20 and the camera unit 40 are installed, and the monitor 50 may be installed directly on the frame 1 or in a separate place where the operator is located. 50 is shown as an imaginary line.

The cassette table 10 is a place where a cassette K on which a plurality of wafers W are placed is placed. In the XY stage 20, a wafer W drawn out from the cassette K is placed in the XY direction. It is moved in a zigzag state, which is an X-axis rail 21 installed in the X-axis direction on the frame 1 and the X-axis rail 21 as shown in the side view of FIG. 3 and the top view of FIG. 4. The lower plate 23 moved in the X-axis direction by the linear servomotor 22 from above, and the Y-axis rail 24 provided in the Y-axis direction so as to be orthogonal to the X-axis rail 21 on the lower plate 23. And an upper plate 26 which is moved in the Y-axis direction by the linear servomotor 25 on the Y-axis rail 24, and the wafer W is seated on the upper plate 26. The seating portion 27 is formed.

The seating portion 27 is formed of a circular hole slightly smaller than the diameter of the wafer W so that the illumination of the infrared lamps L1 and L2 provided on the lower portion of the wafer W passes through the wafer W so that the wafer W It can be seen by the cameras C1 and C2 installed on the top of the camera.

The linear servomotors 22 and 25 are direct-driven motors that are directly driven in a straight line as compared to the rotational motors and belts, racks / pinions, ball screws, and the like used in a general motion system. The force is obtained by flowing an electric current through coils located between the magnets in a line. Since the linear servomotor is a direct drive type, the structure is simpler and takes up less space than a motion system using a rotary motor.The non-contact type has the advantage of relatively low noise and abrasion. There is a possible advantage.

The robot 30 is used when loading and unloading a wafer into a device in a conventional wafer manufacturing equipment, and a detailed description thereof will be omitted.

On the other hand, the camera unit 40 includes at least one line camera C1 scanning the wafer W moved by the XY stage 20 and an area camera C2 photographing a defective position found by the line camera C1. ) And infrared lamps L1 and L2 corresponding to the cameras C1 and C2, respectively. In the embodiment shown in the drawing, two line cameras C1 and C1 'are moved along the wafer path (Fig. 5) are installed at regular intervals to be perpendicular to each other, and infrared lamps L1 and L1 'are provided at corresponding positions for each of the line cameras C1 and C1'.

The cameras C1, C1 'and C2 and the infrared lamps L1, L1' and L2 are respectively installed at the corresponding positions of the upper and lower portions of the wafer W, respectively, and the line cameras L1 and L1 'respectively have a manual focus. It is possible to adjust the position up and down by the clamps (41, 42) for adjustment, the area camera (C2) is possible to adjust the approximate height of the top and bottom by the clamp 43, and finely automatic focus adjustment Use an autofocusing function.

On the other hand, the line camera (L1, L1 ') and the area camera (C) is to enable fine positioning adjustment for alignment between each other and the position alignment with the infrared lamp (L1, L1', L2) installed under the wafer (W). Positioner 44, 45, 46 is provided.

The process of inspecting a semiconductor wafer using the wafer inspection apparatus of the present invention configured as described above is as follows.

First, when the robot 30 removes one wafer W from the cassette K and loads it on the seating portion 27 formed on the upper plate 26 of the XY stage 20 and returns to the original position, the XY stage The upper plate 26 of 20 moves in a zigzag state as shown in FIG. 5 by driving the linear servomotors 22 and 25 provided on the X-axis rail 21 and the Y-axis rail 24. As a result, the wafers W move while the cameras C1, C1 ', and C2 are stationary, and the line cameras L1 and L1' scan while forming some overlapping areas with a predetermined width with respect to the wafer W. (W) It finds out whether there are various defects existing on the surface and inside, that is, dust or scratches on the wafer surface, or air pockets inside the wafer. Area camera L2 located behind L1, L1 ') The position corresponding to the stored coordinates which are expected to be defective is photographed and enlarged on the monitor 50, and the operator looks at the enlarged screen on the monitor 50, whether the defect is present, the type of the defect, and the wafer. The wafer W is finally determined to determine the quantity / defect of the wafer. The wafer W is lifted up by the robot 30 and loaded into the cassette K, and the process is automatically repeated sequentially. Wafer inspection will be done.

Therefore, in the present invention, when two line cameras C1 and C1 'are scanned and the coordinates of the defective part are stored, the XY stage 20 composed of two linear servomotors 22 and 25 corresponds to this coordinate. The precise position control is made so that the area camera (C2) can shoot the position where the position is to be taken. Therefore, there is no problem of deterioration of inspection accuracy due to the positional deviation without the occurrence of the deviation between the scan position and the actual shooting position. will be.

As described above, according to the present invention, the wafer is moved on the XY axis of the linear servomotor method in order to prevent the degradation of inspection accuracy due to the positional deviation that may occur due to the starting torque when the wafer is placed and rotated on the turntable. Placed on the XY stage and moved in a zigzag direction in the XY direction, scanning with a fixed line camera to search for a defective location and then accurately photographing the spot detected by the area camera. The inspection accuracy can be improved by minimizing the positional deviation in the shooting stage, and the scanning speed can be widened by installing a plurality of line cameras at right angles to the wafer movement path. To some extent Written has an effect capable of saving the time required for the inspection of the wafer.

Claims (4)

A cassette table 10 in which a cassette K on which a plurality of wafers W are placed is placed on an upper side of the frame 1; An X-Y stage 20 installed at an upper portion of the frame 1 to move the wafer W drawn from the cassette K into a zigzag state in the X-Y direction; A robot (30) for loading and unloading the wafer (W) between the cassette (K) and the X-Y stage (20); At least one line camera C1 fixed to the frame 1 to scan the wafer W moved by the XY stage 20, and an area camera which photographs a defective position found in the line camera C1. A camera unit 40 including C2) and infrared lamps L1 and L2 corresponding to these cameras C1 and C2, respectively; And And a monitor (50) for displaying the image photographed by the area camera (C2) to an operator for determining quantity / defect of the wafer. The method according to claim 1, The line camera (C1) is a semiconductor wafer inspection apparatus, characterized in that a plurality of installed at right angles to the movement path of the wafer (W). The method according to claim 1, The camera (C1, C2) and the infrared lamps (L1, L2) are each provided at a corresponding position of the upper and lower portions of the wafer (W), the semiconductor wafer inspection apparatus. The method according to claim 1, The XY stage 20 is an X-axis rail 21 provided in the X-axis direction on the frame 1, and a lower plate moved in the X-axis direction by the linear servomotor 22 on the X-axis rail 21. 23, a Y-axis rail 24 provided in the Y-axis direction orthogonal to the X-axis rail 21 on the lower plate 23, and a linear servomotor 25 on the Y-axis rail 24. And an upper plate (26) moved in the Y-axis direction by the upper plate (26), wherein a seating portion (27) on which the wafer (W) is seated is formed.

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