JPS5942978B2 - Wafer appearance inspection equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a wafer visual inspection apparatus.

Semiconductor pieces (pellets) forming circuit elements used in the manufacture of semiconductor devices and the like are obtained by cutting thin semiconductor plates (wafers) several inches in size.

By the way, as a wafer appearance inspection apparatus for inspecting the appearance of this wafer, the following ones have been used conventionally. In this system, the wafer is loaded (unloaded) onto a stage that vacuum-chucks the wafer using a non-contact air transport mechanism called an air bearing mechanism.
Positioning is performed by detecting the orientation flat (orientation flat) using mechanical, optical, and electrical mechanisms, and then the stage is moved in the plane X and Y directions to observe and inspect the entire wafer surface or a partial area. By the way, the biggest bottleneck in the wafer visual inspection apparatus is the drive mechanism of the stage.

The drive mechanism generally uses a mechanical Chessman system or an electric Chessman system driven by a motor, but as the diameter of wafers has recently increased to 3 to 4 inches, it has become necessary to The range of movement of the stage will also become wider. In this case, the former mechanical Thiesmann method has low drive stop precision (trackability) and is difficult to miniaturize the mechanism. In the latter electric Chessman method, the stage is driven by a motor, so when the motor is driven, the stage moves at a constant speed. Therefore, the operator must stop the motor drive as soon as the operator reaches the predetermined observation area while looking through the microscope. For this reason, when the operator turns on the motor drive switch, he or she has to keep looking to see if a characteristic predetermined area appears within the field of view, and when he or she confirms it, he or she has to stop the switch and move the stage in the opposite direction once it has passed. A predetermined area cannot be seen within the field of view at once. Since the field of view shakes during this operation, the operator may become dizzy or feel sick, similar to seasickness, which reduces work efficiency. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a wafer visual inspection apparatus having a mechanism in which the stage can be driven simply and downsized.

Another object of the present invention is to provide a wafer visual inspection apparatus that prevents workers from becoming sick and allows them to continue their work efficiently.

In order to achieve such an object, the present invention includes a stage that attracts and holds the wafer in contact with the wafer, a rotation mechanism that rotates this stage by a preset angle, and a rotation mechanism that rotates the stage in one direction and at least the radius of the wafer to be inspected. A moving mechanism that automatically moves the stage (by rotation, it is possible to cover the entire surface of the inspection area), and a fine movement mechanism that is independent of this moving mechanism and that moves the stage at low speed in the plane The present invention will be explained below with reference to Examples.

FIG. 1 is a plan view showing an embodiment of the wafer appearance inspection apparatus of the present invention.

As shown in the figure, a stage 3 for holding a wafer 2 by vacuum suction is disposed at the center of the apparatus main body 1. Also,
A part of the apparatus main body 1 is provided with a storage section in which a cartridge 3 for storing wafers 2 is placed. This housing portion can be moved up and down in stages, and the amount of movement can also be adjusted. Further, a conveyance path 6 having jetties 5 on both sides through which the wafer 2 passes is provided between the storage section and the stage 3. This conveyance path 6 extends in an L-shape as can be seen in the figure. The transport path 6 is provided with a loader mechanism 7 and an unloader mechanism 8 for transporting the wafer 2 as shown by arrows. These loader/unloader mechanisms 7 and 8 are composed of two rows of injection holes called air bearings that are inclined in a certain direction, and ride on the air injected from these injection holes, and also move the wafer along the flow direction. 2 moves. Therefore, the loader/unloader mechanisms 7, 8 are simply driven by the switches 0N, 0FF for pressurizing compressed air to these injection holes. Further, a pusher A9 is provided on the side of the accommodating portion of the cartridge 4, and is configured to move back and forth once when actuated to push the wafers 2 in the cartridge 4 onto the transport path 6.

Also, at this time, a pair of light sources 10 are placed on both sides of the cartridge 4.
A light receiving section (phototransistor) 11 is disposed, and depending on whether or not the obliquely traveling light beam 12 is blocked, the wafer 2
It is designed to detect the presence or absence of Further, when the wafer 2 is not detected by this wafer detection mechanism, the storage section moves up in stages until the wafer 2 is detected. Further, when the cartridge 4 reaches the top stage (top dead center), a top dead center switch is activated and an END lamp for cartridge replacement is turned on. On the other hand, a stopper pin 13 that moves up and down is provided near the stage 3 to stop the moving wafer 2. Further, at this time, a vacuum stopper B (VAC stopper B) 14 is also provided so that the wafer 2 does not come into strong contact with the stopper pin 13. Further, a wafer directionality detection mechanism 15 is provided, each consisting of a pair of light sources and a light receiving section (phototransistor), which are arranged in parallel around a part of the periphery of the wafer 2 which is held by suction on the soil of the stage 3. A linear orientation flat 6 portion formed by cutting out a portion is detected. Additionally, a vacuum stopper A (VAC stopper A) is also provided on the conveyance path 6 facing the cartridge storage section.
) 17 are installed.

Further, a pusher B18 for pushing the wafer 2 stopped by the VAC stopper A into the cartridge 4 is provided in the transport path. On the other hand, numeral 19 in the figure is a column attachment part of the metallurgical microscope, and the observation part is located almost at the base of the stage.

Further, reference numeral 20 is an electrically operated chase man that operates the slight movement of the stage 3. Furthermore, 21 is an operation panel. Next, an example of a drive mechanism for the stage 3 will be explained with reference to FIG. 2.

That is, the stage 3 having suction holes 22 on its upper surface for vacuum suctioning the wafer 2 is fixed to the rotating shaft 24 of the motor 23 . Further, the suction hole 22 of the stage 3 communicates with a pipe joint 26 that is fitted into the lower shaft portion 25 in an airtight manner and rotatably with respect to each other, and this pipe joint 26 is connected to a vacuum source. There is. Therefore, vacuum suction can be performed even if the stage 3 rotates. Further, the motor 23 is driven by a motor 27 to move the fine movement
It is fixed to the direction table 28. Further, this fine movement X-direction table 28 is supported by a fine movement Y-direction table 30 which is moved in the Y direction by a motor 29. The fine movement mechanism 31 consisting of the fine movement X-direction table 28 and the fine movement Y-direction table 30 is supported by a Y-direction table 34 of a high-speed movement mechanism 33 that moves at high speed in the Y direction by a motor 32. Further, although not shown, the stage 3 can be moved up and down with respect to the rotating shaft 24 of the motor 23 without changing its direction. Here, one specification of the drive mechanism of the stage is shown in the table below.

Note that XO and YO are the center positions of the stage. Next, the automatic inspection state will be explained with reference to the flowchart of FIG. 4 and FIG. 3.

First, turn on the power switch on the operation panel (ON).
The lamp will then light up to indicate that the power is on. Then, the home return switch is turned ON, and the cartridge 4 containing the wafer 2 is lowered to the bottom dead center. When this descent is detected by a mital switch or the like, the start lamp lights up. Next, after setting the preset switch, turn the start switch ON. Then,
The cartridge 4 moves by an amount of elevation set for a first step or a board inspection, and then stops. Here, the wafer detection mechanism operates to detect whether or not the wafer 2 is present on the forward side of the pusher A, and if not, the cartridge 4 is raised again. When the presence of the wafer 2 is detected, the pusher A9 advances to push the wafer 2 in the cartridge 4 onto the transport path 6. On this occasion,
The feeder mechanism 7 and the VAC stopper Bl4 turn ON, and the stopper pin 13 protrudes onto the conveyance path 6 (UP).
do. Therefore, the wafer 2 moves along the transport path 6 in a non-contact state on the air flow, is vacuum-adsorbed by the AC stopper B14 and stops, and the stop position is regulated by the stopper pin 13. Also, during this time Pushsia A9
then retreat and prepare for the next loading.

Further, after the VAC stopper B14 is turned OFF and a wafer is detected, the holding VAC 22 is turned ON and the stage 3 is held by vacuum suction. Next, the stage rises to a certain height and approaches the objective lens of the metallurgical microscope. Further, at this time, the stopper pin 13 goes down and the loader mechanism 7 also goes OFF. Thereafter, while rotating the stage 3, the wafer orientation detection mechanism 15 detects the wafer 2.
The orientation flat opening 6 of the wafer is detected to determine the orientation of the wafer, and first, as shown in FIG. 3, the center position A of the wafer 2 is detected.

For this inspection, use a Chiesman and fine movement mechanism 3.
Run 1. After the inspection of point A is completed, the push button switch (SW waterfall 1) on the knob of the Chessman 20 is turned ON to make a predetermined movement.
In this case, SW/1610N means the operation of the high-speed movement mechanism 31, and as a result, part A of the stage 3 is located directly below the objective lens 35 of the metallurgical microscope, as shown in FIG. Therefore, the Chessman 20 is operated to inspect point A. Next, SW7f6l is turned ON, the coordinates are moved to the plus side of the Y axis, and the Chessman 20 is operated again to inspect point B. Next, when SW7f6l is pressed sequentially, the stage rotates 90 degrees at a time (uses a 90 degree rotation cam), and the objective lens 35 is sequentially rotated.
Points C, D, and E of the wafer 2 are located directly below the point.
Therefore, the points C, D, and E are inspected each time. Thereafter, by turning the SW waterfall 1 to 0N, the high-speed movement mechanism 33 is activated, and the area immediately below the objective lens 35 returns from point E to point A (indicated by the dotted line arrow in FIG. 3).However, point B, point C, E
It is also possible to return to the origin (point A) from this point. Further, when a return to the origin is detected in this state, the stage 3 is lowered and the holding AC 22 is turned off. At the same time, the unloader mechanism 8 and the AC stopper Al7 are turned ON, the wafer 2 is carried out from the stage 3, and the conveyance path 6 is advanced.
It is stopped with AC stopper Al7. Next, when the unloader mechanism 8 becomes 0FF, the AC stopper Al7 also stops (
0FF), the pusher B moves back and forth to accommodate the wafer 2 in the cartridge 4, and the unit inspection operation is completed. According to this embodiment, since a structure is adopted in which the desired wafer portion is moved to the inspection point (directly below the objective lens) using the rotation of the stage, the movement distance (stroke) is longer than that of the conventional one. It will be half as short as the previous one.

Therefore, the design of the wafer appearance inspection device is easy and the cost is low. Another advantage is that the inspection can be interrupted from any inspection point and the next wafer can be inspected.
Furthermore, since the stage is automatically moved between each inspection point, there is no need to observe the wafer with a microscope as in the past.

Furthermore, since the observation area at each inspection point is only as large as the movement capacity of the fine movement mechanism, it is less likely that the operator will have to search the inspection area for a long time, and workers will be less likely to get seasick. Therefore, work efficiency is also improved. Note that the present invention is not limited to the above embodiments.

For example, other generally known techniques may be used for the stage raising mechanism, the stage fine movement/high speed movement mechanism, the stage wafer suction/holding mechanism, etc. Furthermore, the movement of each part in the above embodiment may be performed by single-acting operation, and the movement distance may also be freely set. Furthermore, the object to be inspected is not limited to a wafer. As described above, according to the wafer visual inspection apparatus of the present invention, the drive of the stage for mounting and holding the wafer is simplified and downsized, so the apparatus becomes inexpensive. Further, since the wafer visual inspection apparatus of the present invention has an easy-to-use structure, it can be incorporated into an assembly line, which has the practical advantage of being easy to use.

Furthermore, according to the wafer visual inspection device of the present invention, the worker does not need to constantly look into a metallurgical microscope, so phenomena similar to seasickness are less likely to occur, and work efficiency can be improved. It has many effects.

[Brief explanation of drawings]

FIG. 1 is a plan view of the wafer visual inspection apparatus of the present invention, and FIG.
FIG. 3 is a schematic diagram showing a drive mechanism for moving the stage, FIG. 3 is an explanatory diagram showing the movement of a wafer during inspection operation, and FIG. 4 is a flowchart during automatic inspection. 1... Equipment body, 2... Wafer, 3
... Stage, 4... Cartridge,
5... Jetty, 6... Conveyance path, 7...
...Loader mechanism, 8...Unloader mechanism, 9
...Pushya A, 10...Light source, 11
...... Light receiving part (phototransistor), 12...
... Luminous flux, 13 ... Stopper pin, 14 ...
...Vacuum stopper B (VAC stopper B), 15.
・゜・・・Wafer orientation detection mechanism, 16...
Orientation flat, 17... Vacuum stopper A (VAC stopper A), 18... Pusher B, 19... Column mounting part, 20...
...Cheeseman, 21...Operation panel, 22.
...Suction hole (holding AC), 23 ... Motor, 24 ... Rotating shaft, 25 ... Shaft part,
26...Pipe joint, 27...Motor, 2
8...Fine X-direction table, 29...
・Motor, 30...Fine movement Y direction table, 3
1...Fine movement mechanism, 32...Motor, 3
3...High-speed movement mechanism, 34...Y-direction table, 35...Objective lens.

Claims (1)

[Scope of Claims] 1. In a wafer appearance inspection apparatus that sucks and holds a circular wafer on a stage and moves this stage in a plane direction to observe a desired part of the wafer, the stage is moved after observing the center of the wafer. The stage is automatically moved a predetermined distance outside the radius of the wafer to observe a predetermined area of the wafer, and then the stage is automatically controlled to rotate by a predetermined angle to observe each area, and after the final observation is completed. A wafer appearance inspection apparatus characterized by performing an appearance inspection by automatically moving a stage in a radial center direction and returning it to its origin. 2 Movement to each observation position is performed by a high-speed movement mechanism,
The wafer appearance inspection apparatus according to claim 1, wherein the fine adjustment of the observation position is performed by a fine movement mechanism.