JP2913747B2 - Wafer inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an inspection apparatus for a wafer on which the same semiconductor chip patterns are formed in an aligned manner, with the aim of improving inspection precision and improving productivity. A wafer mounting table that can be moved in a two-dimensional direction, a mechanism control unit that controls the movement of the table, and a predetermined upper part of the table so as to observe or measure the exposed chip pattern of the wafer on the table A wafer inspection apparatus including a measurement observation system fixed to a position and a measurement control unit connected to the measurement observation system, wherein the function control unit is connected to an arithmetic unit having a random number signal generation function. Is configured such that the moving direction of one of the tables and the moving amount in the moving direction can be controlled by a random number signal generated by the arithmetic unit.

[Industrial applications]

The present invention relates to an inspection process for a wafer in which the same semiconductor chip patterns are formed in an aligned manner, and in particular, to improve productivity by increasing the inspection accuracy by randomizing extraction of a chip pattern region to be inspected. The present invention relates to a wafer inspection device.

In the semiconductor device manufacturing field, a semiconductor chip substrate serving as a base is usually obtained by cutting a wafer formed in a matrix in which a plurality of chip patterns are aligned, and obtaining a base semiconductor chip substrate. Since the abnormality of the device itself greatly affects the characteristics of the semiconductor device, the wafer is inspected visually or by a measuring instrument at the time of the wafer.

[Conventional technology]

FIG. 2 is a conceptual diagram showing the configuration of a conventional wafer inspection apparatus, in which (1) is an overall configuration diagram and (2) is a diagram for explaining a measurement state.

 FIG. 3 is a diagram for explaining a problem.

In FIG. 2 (1), on the XY table 3 which moves intermittently at a predetermined pitch in the X and Y directions shown in FIG. A wafer 4 positioned by bringing an orientation flat surface (hereinafter simply referred to as an orientation flat surface) 4a into contact with a bar 3a fixed in the direction is placed, and the surface of the wafer 4 has the orientation flat surface 4a. A plurality of chip patterns 4b are formed in a state of being arranged in a grid shape having one direction.

On the other hand, a measurement observation system 6 fixed with a stay 5 is provided above the XY table 3 at a position corresponding to the table 3, and an eyepiece 6 a attached to the observation system 6 is provided. Can observe one of the chip patterns 4b 'located on the optical axis a of the observation system 6, and measure and control each pattern size, shape, etc. of the chip pattern 4b. The measurement and recording can be performed by the unit 7.

Therefore, according to an instruction from the function control unit 1, the wafer 4 that moves intermittently in the pitch X and Y directions for each one chip pattern 4b is observed and measured by the above-described measurement observation system 6 so that the wafer 4 All chip patterns 4b can be inspected.

In this case, it takes a lot of man-hours to inspect all the chip patterns 4b for all the wafers forming the manufacturing lot.

Therefore, in order to improve productivity, usually, for example, a production lot as a wafer is extracted as a lot to be extracted, and the number of inspection targets is extracted at a regular sampling level, and a chip pattern area for observing and measuring each extracted wafer is limited. I am trying to do it.

In (2) showing the measurement state, a carrier 8 in which a plurality of wafers 4 'to be tested are accommodated in a substantially horizontal and parallel manner so that the chip pattern forming surface is on the upper side on one side of the XY table 3. The wafers 4 'which are arranged and pushed out one by one from the carrier 8 by an arm (not shown) are placed on the XY table 3 as shown by the arrow b to become the wafer 4 shown in (1).

3a indicates the bar described in (1), and 3b indicates a stopper for positioning the wafer 4 'pushed out of the carrier 8.

Therefore, the wafer 4 ′ extruded from the carrier 8 is placed at a predetermined position on the XY table 3 like the illustrated wafer 4.

Then, the XY table 3 and thus the wafer 4 are intermittently moved in the Y direction with respect to the base 2 in accordance with an instruction from the mechanism control unit 1, and the Y on the wafer 4 is roughly
The chip patterns 4b aligned in the directions are observed and measured.

In particular, the XY table 3 in this case has one direction (Y direction).
Since only the movement is performed, by synchronizing the pushing operation from the carrier 8 and the movement of the XY table 3, a plurality of wafers can be efficiently and continuously inspected, and the inspection work with high productivity can be performed. Can be realized.

In FIG. 3, (i) is a plan view showing a wafer on an XY table, and (ii) is a view showing a chip pattern region to be observed and measured.

In (i), 3 is an XY table, 3a is a positioning bar,
3b indicates a stopper for positioning, and 4 indicates a wafer, 4
As in FIG. 2, a represents an orientation flat surface and 4b represents a chip pattern.

Therefore, as described with reference to FIG. 2B, the wafer 4 is intermittently moved in the Y direction to observe and measure the chip patterns 4b aligned on the wafer 4 in the Y direction. The pattern area becomes a shaded area A shown in (ii), and the area A is the same area common to all the test wafers.

Accordingly, for example, there is a pattern defect in the B ₁ and B ₂ areas deviating from the area A as in the wafers 4 _-1 and 4 _-3 , or the P out of the area A as in the wafers _4-2 and 4 _{-4. 1} point, such as when there is a foreign object in _two points P becomes unsuitable as lot inspection results to the wafer can be found these pattern failure and foreign matter.

[Problems to be solved by the invention]

The conventional wafer inspection apparatus has a problem that it is not possible to expect an improvement in productivity due to an increase in inspection accuracy for detecting a pattern defect or a foreign substance located in a region outside the inspection region.

[Means for solving the problem]

The above problems are observed at least in the X and Y two-dimensional directions, a wafer mounting table, a mechanism control unit for controlling the movement of the table, and an exposed chip pattern of the wafer on the table. Or a wafer inspection apparatus comprising a measurement observation system fixedly arranged at a predetermined position above the table so as to be able to perform measurement and a measurement control unit connected to the measurement observation system, and having a random number signal generation function. A wafer inspection apparatus configured such that the mechanism control unit connected to the arithmetic unit can control one moving direction of the table and an amount of movement in the moving direction by a random number signal generated by the arithmetic unit; Solved by

(Operation)

By randomly changing the inspection area for each wafer in the production lot, the inspection accuracy can be improved at least within the lot.

In the present invention, by connecting an operation unit having a random number generation function to a mechanism control unit connected to the XY table, a conventional inspection area in the Y direction is randomly generated in the X direction for each wafer at least in a manufacturing lot. I try to shift.

This means that the inspection area is enlarged when manufacturing lots of wafers are used as compared with the conventional case, so that, for example, the probability of finding a pattern defect or the like due to a mask is improved.

Therefore, productivity can be improved by improving inspection accuracy.

〔Example〕

FIG. 1 is a view showing an example of the configuration of a wafer inspection apparatus according to the present invention. The XY table 3 is stored in a mechanism controller 11 similar to the mechanism controller 1 described in FIG. Although an arithmetic unit 12 having a random number generating function for shifting in the axial direction is connected, the configuration other than the mechanism control unit 11 and the arithmetic unit 12 is exactly the same as that of FIG.

In particular, in this case, a line c in the Y direction passing substantially through the center of the XY table 3 in the X direction and the measurement observation system 6 described in FIG.
The position of the XY table 3 when the optical axis a of the XY table 3 coincides with the optical axis a is set as a reference position of the table 3.
By connecting the random number signal generated from 12 to a circuit for controlling the shift in the X direction of the mechanism control unit 11 connected to the table 3, the XY table is shifted by a pitch corresponding to the random number generated from the arithmetic unit 12. 3 is shifted in the X direction.

Here, the case of a wafer 4 in which about ten or more chip patterns 4b are formed in a direction along the orientation flat surface 4a will be described in detail as an example.

For example, the random number generated from the arithmetic unit 12 is set to 01 to 19, and the mechanism control unit 11 that operates in the X direction by the random number signal is set to the XY table 3 when the random numbers 01 to 09 are transmitted. The table 3 is shifted from the reference position to the "-" side by each digit, and when random numbers 11 to 19 are transmitted, the table 3 is shifted from the reference position to the "+" side by the first digit. It is configured to shift.

In the wafer inspection apparatus having such a configuration, for example, when the random number generated from the arithmetic unit 12 is “07”, the mechanism control unit 11 having received the random number signal 07 moves the XY table 3 and thus the wafer 4 to the reference position. In order to move the wafer 4 in the Y direction as described in FIG. 3 after shifting the wafer 4 in the Y direction as described with reference to FIG. Can be observed and measured.

If the random number generated from the arithmetic unit 12 is, for example, "10", the XY table 3 and thus the wafer 4 are moved in the Y direction on the reference line c without being shifted in the X direction. The chip pattern located in the central region can be observed and measured as it is.

Further, when the random number transmitted from the arithmetic unit 12 to the mechanism control unit 11 is, for example, "14", the XY table 3 and, consequently, the wafer 4 are shifted by four pitches from the reference position to the "+" side along the X axis, ie, to the right After the shift, the chip pattern moves in the Y direction, so that it is possible to observe and measure a chip pattern located in an area four pitches to the left of the reference central area.

This means that when the number of wafers to be extracted from the manufacturing lot is at least 20 or more, all chip patterns formed on the wafer are observed and measured.

On the other hand, the defect caused by the mask occurs at the same location on almost all wafers or in the vicinity thereof.

Therefore, the probability that such a defect is found can be greatly increased as compared with the related art.

In order to make it easier to understand, a process of discovering undiscovered foreign matters, pattern defects, and the like described with reference to FIG. 3 will be described.

Note that the chip pattern area A in FIG.
A chip pattern area corresponding to the reference position of the table 3 is set.

For example, B ₁ regions wafer 4 _-1 pattern defect is located in the left two pitches on the A region serving as a reference.

In the case of the wafer 4 _-1 Therefore, the region as a reference a region B ₁ by causing two pitches shifted right or "+" in the direction of the wafer 4 _-1 turn X-Y table 3 along the X-axis It can be moved to the position of A.

Therefore, the wafer 4 _-1 i.e. X-Y table 3 as described in Figure 3 the wafer 4 _-1 turn X-Y table 3 After two pitches shifted to "+" direction Y
By moving the pattern in the direction, the pattern defect can be found.

Conversely, this means that the pattern defect can be found when the random number “12” is generated from the arithmetic unit 12.

Left in the case of the wafer 4 _-2, since the region the foreign matter P ₁ is located in the right side by one pitch on the A region serving as a reference, the wafer 4 _-2 hence X-Y table 3 along the X-axis or "-" the area of foreign matter P ₁ is positioned only by 1 pitch shift direction can be adjusted to the position of the region a.

This means that when the random number “01” is generated from the arithmetic unit 12, the foreign matter can be found.

In the wafer 4 _-3 and _4-4 as well, it is in the wafer 4, _-3 B ₂ region when random numbers "02" from the arithmetic unit 12 is generated pattern defects, also wafers _4-4 In the foreign matter P ₂ is Will be discoverable.

Therefore, different regions can be observed and measured for each wafer by randomly generated random numbers, so that the inspection accuracy of a wafer as a production lot can be improved.

〔The invention's effect〕

As described above, according to the present invention, it is possible to provide a wafer inspection apparatus in which inspection accuracy is improved and productivity is improved by randomizing extraction of a chip pattern region to be inspected.

In the description of the present invention, XY moving in a two-dimensional direction is used.
The test is performed when a table is used, but the test wafer is provided with a rotation function that can rotate the axis in the same plane.
In the case where a Y table is used, the same effect can be obtained by connecting the random number signal from the arithmetic unit to the circuit for controlling the rotation angle of the mechanism control unit connected to the table in a state corresponding to the rotation angle.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a wafer inspection device according to the present invention, FIG. 2 is a conceptual diagram showing a configuration of a conventional wafer inspection device, and FIG. 3 is a diagram for explaining a problem. In the figure, 3 is a table (XY table), 4 is a wafer, 4a is an orientation flat surface, 4b is a chip pattern, 6 is a measurement observation system, 7 is a measurement control unit, 11 is a mechanism control unit, and 12 is a calculation. , And, respectively.

Claims (1)

(57) [Claims] 1. A table (3) for mounting a wafer movable in at least two dimensions X and Y, and the table (3)
Mechanism control unit (11) for controlling the movement of the wafer, and the exposed chip pattern (4) of the wafer (4) on the table.
b) the table (3) so that it can be observed or measured
Measurement observation system (6) fixedly arranged at a predetermined position above the camera
And a measurement control unit (7) connected to the measurement observation system (6), wherein the function control unit (11) is connected to an operation unit (12) having a random number signal generation function. Is configured such that a moving direction of the table (3) and a moving amount in the moving direction can be controlled by a random number signal generated by the arithmetic section (12). apparatus.