JPS6144439A - Device for inspecting wafer appearance - Google Patents

Abstract

PURPOSE:To simplify the drive of a stage by providing the titled device with the stage on which a wafer is absorbed, a means of moving the relative position of the optical system and the wafer to X-Y directions, and a means of rotating the stage. CONSTITUTION:When pushed up onto a carrier passage 6 by a pusher 9, the wafer 2 in a cartridge 4 moves over the carrier passage 6 in non-contact and held to the stage 3 by vacuum adsorption. Next, the stage 3 rises to a fixed level and comes close to the objective lens 35 of a metal microscope. Thereafter, the center position A of the wafer 2 is detected by securing the directivity of the wafer 2 under rotation of the stage 3. After the inspection of the point A is finished, a chessman 20 is operated and made to act as predetermined. As a result, the stage 3 is located with the point A fixed immediately under the lens 35, where the point A is inspected. Thereafter, points B-E are successively inspected by locating the points B-E in succession immediately under the lens 35 by manually operating the chessman 20.

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. This involves loading (unloading) the wafer onto a stage that vacuum-chucks the wafer using a non-contact air transport mechanism called an air bearing mechanism, and also allows the wafer to be oriented 1iIi on this stage! ! Straight edge of knowledge (
The positioning is performed by detecting the 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. .

Ru.

By the way, the biggest bottleneck in the wafer visual inspection apparatus is the drive mechanism for the stage. Generally, a mechanical Chessman system and an electric Chessman system driven by a motor are used for the drive mechanism, but as the diameter of wafers has recently increased to 3 to 4 inches, it has become necessary to adapt The movement range of the stage will also become wider.

In this case, the former mechanical chessman method has low drive stop precision (followability) and it is difficult to miniaturize the mechanism.7 In addition, the latter electric chessman method uses a motor to drive the 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. It is not possible to see a certain area within the field of vision at once, and the field of view shakes during this operation, which can lead to dizziness and nausea similar to seasickness, which reduces work efficiency. becomes lower.

Therefore, an object of the present invention is to provide a wafer visual inspection apparatus having a mechanism in which the stage drive is simplified and the mechanism is 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 this purpose, one embodiment of the present invention is as follows:
A stage that holds the wafer by suction, a rotation mechanism that rotates this stage by a preset angle,
A moving mechanism that automatically moves the stage in one direction K and at least the radius of the wafer to be inspected (the entire wafer can be inspected by rotation); X
The present invention will be described below using examples.

FIG. 1 is a plan view showing an embodiment of the wafer visual 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. Further, a part of the main body of the apparatus is provided with a accommodating part in which a cartridge 4 for accommodating the wafer 2 is placed. This housing part moves up and down in stages, and
The amount of movement can also be adjusted to 5. Further, between this accommodation section and the stage 3, there is provided a conveyance path 6 with jetties 5 on both sides through which the wafer 2 passes.As can be seen in the figure, this conveyance path 6 extends in an L-shape. ing. In this transport path 6, wafers 2 as shown by arrow rows are placed.
A loader mechanism 7 and an unloader mechanism 8 are provided for transferring. These loader/unloader mechanisms 7 and 8 consist 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 move the wafer along the flow direction. 2 moves. Therefore, the loader/unloader mechanism 7
, 8 are simply driven by turning ON and OFF switches for feeding compressed air to these injection holes.

Further, a button (
5) 9 is provided and moves forward and backward once by operation,
The Ueno S2 in the cartridge 4 is pushed out onto the transport path 6. In addition, at this time, a pair of light sources 0 and phototransistors 1 are arranged to sandwich the cartridge 4, and the presence or absence of the wafer 2 is detected by the presence or absence of the continuous punch that moves diagonally at the speed of light 12. It has a button.

Further, if the wafer detection mechanism does not detect the wafer S2, 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, the neighborhood busyness in stage 3 is rising (up) and falling (DO).
A stopper pin] 3 is provided to stop the moving Ueno S2. At this time, the vacuum stopper a3) (VAC stopper (B))
4 is also provided. In addition, a wafer orientation detection mechanism 5 consisting of a pair of light sources and a light receiving section (phototransistor) arranged parallel to each other is provided on a part of the periphery of the wafer 2 held by suction on the stage 3. - It is designed to detect the linear orientation flat 6 portion formed by cutting out a part of No. 2. Also, the vacuum stopper (A) (VAC stopper A ) 17 are provided. Also, there is a pusher a3)1 that pushes the wafer 2 stopped by this VAC stopper W into the cartridge 4.
8 is provided in the conveyance path portion.

On the other hand, numeral 9 in the figure is a column attachment part of the metallurgical microscope, and the observation part is located almost directly above the stage. Further, 2o is an electrically operated chessman that operates the slight movement of stage 3. Furthermore, 2
1 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, which has a suction hole 22 on its upper surface for vacuum suctioning the wafer 2, is fixed to a rotating shaft 24 of a motor 23.

Further, the suction hole 22 of the stage 3 communicates with a pipe joint 26 that is fitted into the lower shaft part 25 in an airtight manner and rotatably with 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 fixed to a fine movement X-direction table 28 that is moved by a motor 27 in the plane X direction. Further, this fine movement table 28 for the X direction is supported by a fine movement table 30 for the Y direction, which is moved in the Y direction by a motor 29. And this fine movement X direction table 28
and a fine movement mechanism 31 consisting of a table 30 for fine movement in the Y direction.
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 is provided with a button so that it 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 (X,, Ya) is the center position of the stage.

Next, the automatic inspection state will be explained with reference to the flowchart in FIG. 4 and FIG. 3.

First, turn on the power switch on the control panel.

When turned on (ON), the lamp lights up to indicate that the power is on. Then, the origin 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 microswitch or the like, the start lamp lights up. Next, after setting the preset switch, turn on the start switch.

Then, the cartridge 4 moves by a -step or a rising amount set for installation inspection, etc., 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 button.
Raise the cartridge 4 again. And wafer 2
When the presence of the pusher (A) 9 is detected, the pusher (A) 9 moves forward and pushes out the wafer 2 in the cartridge 4 onto the transport path 6. At this time, loader mechanism 7 and VAC stopper (
B) 14 is turned on, and the stopper bin 13 protrudes (UP) onto the conveyance path 6. Therefore, the wafer 2 moves on the transport path 6 in a non-contact state on the air flow, and the VA
It is stopped by vacuum suction by the C stopper [F]) 14, and the stop position is regulated by the stopper pin 13.

Also, during this time, the bushing (A) 9 retreats to prepare for the next loading. Also, the VAC stopper 03) 14 is
After FF and detecting the wafer, hold VAC
22 is turned on to hold the stage 3 by vacuum suction. Next, K, the stage rises to a certain height and approaches the objective lens of the metallurgical microscope.

Further, at this time, the stopper bin 13 is DOWN-j and the loader mechanism 7 is also turned OFF.

Thereafter, while rotating the stage 3, the wafer orientation detection mechanism 15 detects the orientation flat 16 of the wafer 2 to determine the orientation of the wafer 2. First, as shown in FIG. Detect the ape-man. This inspection is performed by operating the fine movement mechanism 31 using a chessman. After the inspection of point A is completed, press the push button switch (S) located on the knob of Chessman 20.
WI'hl) is turned on and the predetermined movement is performed.

In this case, SWI%1ON 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 full range microscope, as shown in FIG. Therefore, the Chessman 20 is operated to inspect point A. Then 5
Turn on WNnl, move the coordinates to the plus (+) side of the Y axis, operate the chessman 20 again, and perform an eight-point test. Then, when you press 5WNQ1 in sequence, the stage rotates 90 degrees at a time (using a 90 degree rotation cam) to sequentially place wafers 2. Position the 0 point, D point, and E point.

Therefore, the points C, D, and E are inspected each time. Thereafter, by turning on SW$1, the high-speed movement mechanism 33 is activated, and the position immediately below the objective lens 35 returns from point E to point A (indicated by the dotted line arrow in FIG. 3).
It is also possible to return to the origin (point A) from this point. Furthermore, when return to the origin is detected in this state, the stage 3 is lowered and the holding VAC 22 is turned off. At the same time, the unloader mechanism 8 and the VAC stopper (to) 17 are turned on.
The wafer 2 is carried out from the stage 3, advanced along the conveyance path 6, and stopped at the VAC stopper (g) 7. Next, when the unloader mechanism 8 turns OFF, V! A'C stopper 7 is also stopped (OFF), the button (B) moves back and forth to house 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 visual inspection apparatus 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,
Stage raising mechanism, stage fine movement ψ high-speed movement mechanism,
Other generally known techniques may be used for the wafer suction and holding mechanism of the stage. Further, the movement of each part in the above embodiment may be performed by a single action operation, and the movement distance may also be freely set.

Furthermore, the object to be inspected is not limited to Ueno.

According to the 5K wafer visual inspection apparatus of the present invention as described above, the driving of the stage on which the wafer is placed and held 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 apparatus of the present invention, there is no need for the worker to constantly look into a metallurgical microscope, so phenomena similar to seasickness among workers 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/appearance inspection apparatus of the present invention, FIG. 2 is a schematic explanatory diagram showing the drive mechanism for moving the stage, FIG. 3 is an explanatory diagram showing the movement of the wafer during inspection operation, and FIG. FIG. 4 is a flowchart during automatic inspection. DESCRIPTION OF SYMBOLS 1... Apparatus body, 2... Wafer, 3... Stage, 4... Cartridge, 5... Jetty, 6... Transport path, 7... Loader mechanism, 8... Unloader mechanism,
9... Bushy prisoner, 10... Light source, 1]... Light receiving part (phototransistor), ]2... Luminous flux, ]3...
Stopper pin, ]4... Vacuum stopper B (VAC stopper [F])), 15... Wafer orientation detection mechanism,
16...Orientation flat, 17...Vacuum stopper (A) (to V 〇 stopper), 18...Button (B), 19...Column mounting part, 20...Chessman, 21...・Operation panel, 22... Suction hole (
Holding VAC), 23...Motor, 24...Rotating shaft,
25... Shaft portion, 26... Pipe joint, 27... Motor, 28... Table for fine movement Y direction, 29... Motor, 30... Table for fine movement Y direction, 3J... Fine movement mechanism, 32... Motor, 33... High speed movement mechanism, 34
...Y-direction internal table, 35...objective lens. Figure 1

Claims (1)

[Claims] 1. (a) a stage for adsorbing the wafer; (b) an optical system for observing the wafer; and (c) a relative position between the optical system and the wafer in the X and Y directions. A wafer appearance inspection apparatus comprising: (d) means for rotating the stage; and (d) means for rotating the stage.