JPS61132917A - Microscopic device - Google Patents

Abstract

PURPOSE:To move automatically the prescribed position of a substrate into the visual field of observation without using a prealignment by converting a substrate coordinate system to a stage coordinate system in accordance with a conversion equation and controlling an X-Y stage with converted coordinate values. CONSTITUTION:Coordinate values in the substrate coordinate system of a prescribed position on a wafer 1 are stored in a storage means 14. The conversion equation between the substrate coordinate system and the stage coordinate system is stored in an arithmetic storage means 13. Contents of storage means 13 and 14 are inputted to a converting means 15, and the coordinate values of the substrate coordinate system are converted to those of the stage coordinate system, and X-direction and Y-direction motors 5 and 9 are driven and controlled by the converted coordinate values. Thus, the prescribed position on the wafer is automatically brought into the visual field of an observing device 11 even through the wafer 1 is placed on a stage 2 without prealignment.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention is applied to a microscope apparatus for observing a pattern on a substrate formed by a wafer or a mask.

(Background of the Invention) Microscope equipment is used to inspect fine patterns formed on the surface of semiconductor wafers during and at the final stage of each process in the manufacturing process of integrated circuits such as SI, Vl, and 81. In order to improve the efficiency of pattern inspection by observing the same spot on multiple wafers, the wafer to be inspected is placed accurately in a predetermined position on the microscope stage in a predetermined direction. An automatic transfer device is used. Conventionally, this type of device uses a printer having a plurality of rotating rollers in contact with the outer circumference of the wafer and a photoelectric detector for positioning and orienting the wafer. Many of them are equipped with an alignment device, and the position and direction of the wafer is determined by observing the outer peripheral shape of the wafer, which is held by a plurality of rotating rollers and rotated in the circumferential direction, using a photoelectric detector.

The thus aligned wafer is carried onto an XY stage by a loading arm or the like. The wafer on the X-Y stage is pre-aligned, so it is in a predetermined position and direction. - If the configuration is configured so that the X and Y coordinates of the X-Y coordinate system set on the Y stage are read out using an encoder, etc., even if the wafer is different, the specified position will be automatically located within the observation field by specifying the coordinates. The X-Y stage can be controlled to bring the

However, such a pre-alignment device performs pre-alignment using the outer circumference of the wafer, and therefore has the disadvantage that it cannot correct the deviation between the outer circumference and the printed pattern, and also complicates the microscope apparatus.

Although the above description has been made regarding a semiconductor wafer, it similarly applies to the case of observing a pattern on a mask or other patterned substrate.

Moreover, the same thing can be said not only for a plurality of substrates on which the same pattern is formed, but also for a single substrate when re-examination is considered.

(Objective of the Invention) The object of the present invention is to solve these drawbacks and provide a microscope device that automatically brings a predetermined position on a substrate within the observation field of view without using pre-alignment. shall be.

(Overview of the Invention!) The present invention defines a predetermined position on a board with the board as a reference, stores it as a coordinate value in a nine-board coordinate system, and converts this coordinate value into
- By coordinate transformation between the substrate coordinate system on the substrate on the Y stage and the stage coordinate system determined based on the X-Y stage, the coordinates are converted to the coordinate values of the stage coordinate system, Rather than controlling the stage, the pre-alignment device is replaced with a coordinate value input operation and arithmetic processing for setting the substrate coordinate system, resulting in a simple configuration.

(Example) The present invention will be described below based on the example shown in the drawings.

FIG. 1 is a block diagram of a first embodiment of the present invention. The X-direction stage 2 on which the wafer 1 is placed is placed on the Y-direction stage 3, and a piece (not shown) formed on the lower surface of the stage 2 is rotated by degrees in a groove formed in the X-direction in the Y-direction stage 3. The lead screw 4 is screwed into and passes through a female threaded hole formed in this piece. One end of the lead screw 4 is fixed to one end of the rotating shaft of the X-direction motor 5,
A rotary encoder 6 is attached to the other end of the rotation shaft of the motor 5.
The rotation axis of is fixed. The motor 5 and the rotary encoder 6 are fixed on the Y-direction stage 3 with a fixture (not shown). Therefore, when the X-direction motor 5 rotates, the X-direction stage 2 and the Y-direction stage 3 are placed on the base 7, and a piece (not shown) formed on the lower surface of the stage 3 is placed in the groove formed in the KY direction of the base 7. The female screw hole K and lead screw 8 formed in this piece are fitted so as not to rotate.
are screwed together and penetrated. One end of the lead screw 8 is fixed to one end of a rotating shaft of a Y-direction motor 9, and a rotating shaft of a rotary encoder 10 is fixed to the other end of the rotating shaft of the motor 9. Therefore, when the Y-direction motor 9 rotates, the Y-direction stage 3 moves in the Y-direction, and the rotary encoder 1
From 0, a nine Y coordinate signal is output corresponding to the Y coordinate value.

The wafer 1 on the X-direction stage 2 is observed by an observation device 11 placed above the stage 2.

Input specifying means 12, which is constituted by a key switch or the like, instructs calculation storage means 13 to read the X coordinate signal and Y coordinate signal obtained from rotary encoder 6.10. The calculation storage means 13 calculates a conversion formula between the wafer coordinate system predetermined on the wafer and the stage coordinate system of the X-Y stage 2.3 from the input X-coordinate signals and Y-coordinate signals of the two pairs of friends. ,Remember. The storage means 14 stores coordinate values of measurement points determined on the wafer 1 in a predetermined wafer coordinate system. The conversion means 15 inputs the storage contents of the calculation storage means 13 and the storage contents of the memory element flL14, and converts the coordinate values stored in the storage means 14 into an X coordinate signal in the stage coordinate system using a conversion formula by the calculation storage means. and a Y coordinate signal.

The operation command means 16 is a measurement switch 16 that outputs a measurement signal for bringing the measurement point of the sea urchin/.1 to the center of the visual field.
It has a. The control means 17 receives the X coordinate signal and the Y coordinate signal from the conversion means 15.

A measurement signal from the operation command means 16 is input. When the control means 17 inputs the measurement signal obtained by turning on the measurement switch 16a, the X-coordinate signal and Y-coordinate signal from the conversion means 15 are converted into the X-coordinate signal and Y-coordinate signal from the rotary encoder 6.10. so that X is equal to
A drive circuit 18 for driving the direction motor 5 and the Y direction motor 9. In: Inputs a signal.

The adjustment lever 20 is always at the neutral point.
a, and the tilting force is applied to the tilting direction of the operating lever 20a,
The motor drive circuit 21 drives the motor 5 according to the input signal.
, 9.

Next, the principle of the coordinate transformation used in FIG. 1 will be explained with reference to FIG. 2. A certain chip that has no chips on the wafer is defined as the origin chip 2a... If there is a boundary line between chips (wafer street line) in the center above, the chip to the right of the boundary line is defined as the origin chip 2a. The point at the lower left corner of the origin chip 2a determined in this way is defined as the origin, the direction parallel to the orientee 71 flat in the chip arrangement is defined as the X axis, and the direction perpendicular thereto is defined as the τ axis.

If the X-Y coordinate system of the X-Y stages 2 and 3 is as shown by the dashed line in FIG. 2, then the origin 0 of the wafer coordinate system and an arbitrary point A on the τ axis of the wafer coordinate system X of
−Y coordinate system, respectively, (X(l t y
o) , (X,,Y,), mutual transformation between the wafer coordinate system and the stage coordinate system consists of the following combination of movements.

That is, since the amount of parallel movement ΔX in the X-axis direction is ΔX=, the amount of parallel movement ΔY in the Y-axis direction is ΔY=Y0, and the amount of rotational movement α with respect to the origin 0 (Xor Y6) is:
Since cos α = whip 1 sin (X':! mu 10), the conversion formula from the stage coordinate system to the wafer coordinate system is (sub)
(-:?Monijo::) (Omi = Goomi 斤... (The conversion formula from the wafer coordinate system to the stage coordinate system is (kai) = 6?
2 = -2 =) (Atsu + (7)... It is given by (2).

Therefore, in FIG.
As defined in FIG.
Move stages 2 and 3 (as shown in Figure 3, align the lower left corner of chip 2a with the intersection of crosshairs 11b; 2b in Figure 3 is the Quartz street line), and input designation. The coordinate value (X
otYo) is input into the calculation storage means 13. After that, operate the operating lever 20a of the joystick I again to move the X-Y stages 2 and 3, bring an arbitrary point A on the Y axis of the wafer coordinate system to the center of the field of view 11a, and specify the input. The means 12 calculates the coordinate values (X, , Y,
) is input into the calculation storage means 13. Arithmetic storage means 1
3 is the coordinate value ('x4t Yo) t in the stage coordinate system input from the rotary encoder 6, lO
Formula (2) is obtained from (Xat Y@). The storage means 14 stores the coordinate values of measurement points determined in advance in the wafer coordinate system, and the conversion means 15 substitutes the coordinate values of the storage means 14 into the arithmetic expression (formula (2)) from the calculation storage means 13. Then, the coordinate values in the X-Y coordinate system are determined and controlled so that the position of the coordinate values in the wafer coordinate system stored in the storage means 14, that is, the measurement point, is brought to the center of the field of view of the observation device 11. The information is input to the means 17. Control means 1
? When the measurement switch 16a of the operation command means 16 is turned on, the encoder 6.1 changes the coordinate value of the conversion means 14.
The detectors 5 and 9 are driven so that the coordinate value is equal to the coordinate value from 0. Signals are input to drive circuits 18 and 19. and,
When the coordinate values from the encoder 6.10 match the coordinate values from the conversion means 15, the control means 17 stops inputting signals to the drive circuits 18 and 19 so as to stop driving the motors 5 and 9. At this time, the measurement point of the wafer 1 is located at the center of the observation device 11.

In this way, even if the wafer 1 is placed on the X-direction stage 2 without alignment, the coordinates of the origin of the wafer coordinate system defined on the wafer and the position 1a of any point on the Y' axis can be adjusted.
A predetermined position on the wafer 1, that is, a measurement point, can be brought to the center of the field of view of the observation device 11 by simply capturing the coordinate signal of the stage coordinate system compatible with the IC.

In addition, in FIG. 1, the conversion means 15 and the operation command means 1
6, a plurality of measurement points are stored in the storage means 14, and each time the measurement switch 16a is turned on,
If the coordinates of the measurement points in the storage means 14 are sequentially read out, it is possible to sequentially bring a plurality of measurement points to the center of the field of view.

Specifically, for example, a counter corresponding to the number of memorized measurement points is provided, and this counter sequentially counts the measurement signals, and the readout address of the storage means 14 is switched according to the output of the counter. Just leave it there.

Furthermore, it is also possible to use a coordinate value setting means that can arbitrarily set the coordinate values of the measurement points. That is, a signal input means is provided for inputting the coordinates of the origin 0 in the wafer coordinate system of the wafer l and an arbitrary point A on the Y axis, and a conversion formula from the stage coordinate system to the wafer coordinate system is determined using equation (1). A calculation means is provided, the measurement points of the wafer 1 are sequentially brought to the center of the field of view, coordinate signals in the stage coordinate system are inputted by the signal input means, and the equation (
From 1), the coordinate values (X', Y') in the wafer coordinate system
What is necessary is to provide a writing means for calculating and sequentially storing them in the storage means 14. Of course, this -f@ inclusion may be performed manually in advance.

By storing a large number of measurement points in this way, fHJ
- It is especially effective when observing a large number of wafers 1 in a pattern.

Note that the X-Y stage 2.3 motors 5, 90 and tally encoders 6, 10 used in FIG. It has a built-in up/down counter to output positive and negative pulses according to The structure is such that degrees can be made to correspond to the positive and negative values of each coordinate value and output as the code material ρ count value of the up/down counter.

Of course, it is obvious that in addition to the rotary encoder 6.100, an Otsunia encoder may be used.

In addition, in FIG. 1, calculation storage means 13, storage means 1
4. Each function of the converting means 15 and the controlling means 17 can be replaced by a microcomputer M.

An example of using the control system computer in this way will be explained with reference to the block diagram in FIG. 4 and the flowcharts in FIGS. 5 and 6.

In FIG. 4, the same parts as in FIG. 1 are given the same reference numerals. In FIG. 4, the rotary encoder 6 shown in FIG. 1 has an X coordinate detection section 6a and an X coordinate storage counter 6b.
The rotary encoder IO is composed of a Y coordinate detection section 10a and a Y coordinate storage counter 10b. Furthermore, the X-axis motor control circuit 1g corresponds to the drive circuit 18 in FIG.
A function is added to stop the X-axis motor 5 when the coordinate signal and the X-coordinate signal from the X-coordinate detection section 6a become equal. The Y-axis motor control circuit 1g corresponds to the drive circuit 19, but similarly to the X-axis motor control circuit 1g, the Y-coordinate signal from the microcombi or Ichita M and the Y-coordinate signal from the Y-coordinate detection section 6a are A function is added to stop the Y-axis motor 9 when they become equal.

The micro combinator M is operated according to the flowchart K for specifying measurement points shown in FIG. 5, the observation flowchart shown in FIG.

First, the operation of specifying a measurement point will be explained using FIG. After placing the wafer on the X-direction stage 2, the keyboard 2
When the No. 2 measurement point designation mode key 22a is turned on, the combiator M operates according to the flowchart shown in FIG. First, bring the origin 0 of the wafer to the center of the field of view, and use the coordinate system Kaki-2.
2b, the X coordinate signal from the X coordinate storage counter 6b and the Y coordinate signal from the Y coordinate storage counter 10b are stored in a predetermined position in the storage section of the micro combinator M (step 5). After inputting the X-Y coordinates of the origin O in the stage coordinate system, bring any position on the Y axis of the wafer to the center of the field of view as the reference point A, and turn on the coordinate system Kaki-22b. As shown in FIG.
Step 52 to determine whether the two coordinates are the same or not.
), if the coordinates are not the same, it is determined that a correct coordinate designation operation has been performed, and from the two coordinates stored in steps 50 and 51, a conversion formula from the stage coordinate system to the wafer coordinate system is calculated as shown in equation (1). (Step 53). Next, using the number N of measurement points as a factor (step 54), the coordinate formula Kaki-2
25 is turned on (step 55).

That is, by bringing an arbitrary position of the wafer to the center of the visual field and turning on the coordinate key 22b, the coordinates at that time are stored in the storage section of the micro combinator M (step 56). Micro Combiator M has a keyboard 22
The coordinates of the measuring point are recorded until the programming end key 22C is turned on (step 57). The number of measurement points can be found by counting the number of times the coordinate key 22b is turned on in step 58. When the programming end key 57 is turned on (step 57). The coordinates in the stage coordinate system stored in step 56 are converted into coordinates in the wafer coordinate system according to equation (1) obtained in step 53 (step 59), and stored in the memory (step 60). Specifying the measurement point in this way 20-
The chart ends. The coordinate values stored by the step marks correspond to the stored coordinate values in the storage means In of FIG.

Next, the operation during observation will be explained using FIG. 6, which is a flowchart of observation. When the observation key 22d is turned on, the sixth
The flowchart in the figure begins. Steps 61 and 62
, 63 are the same as steps 51 and 52 in FIG. In step 64, a conversion formula from the wafer coordinate system to the stage coordinate system is calculated as shown in equation (2). When the observation start key 22C is turned on (step 65), the number of observations C is set to 1, and the number of observations C is set to 1 in step 66. Read the coordinate values of the corresponding address (step lower) and use the formula (2) obtained in step 64.
) into coordinate values in the stage coordinate system (step 68). Of these coordinate values, the X coordinate value is input to the X-axis motor control circuit 1g, and the Y coordinate value is input to the Y-axis motor control circuit ig<(step 69). When the stage movement end symbol is input from the X-axis motor control circuit 1g and the Y-axis motor drive circuit 1q (X step 70), it is determined whether or not the end key 226 has been turned on (step 71).
, the process ends when the number of observations C becomes larger than the number N of measurement points (step 72). If the number of observations C is smaller than the number N of measurement points, the process returns to step 67 while counting the number of observations C in step 72 (step 73). In this way, the observation flowchart ends.

Note that the X-axis motor control circuit Ig in the above explanation,
The microcomputer M can have a determination function for determining whether the stage has moved to a predetermined coordinate position in the Y-axis motor control circuit 1g. For that,
In step 70 of FIG.
are the X coordinate memory counter 6b and the Y coordinate memory cuff/re 10b.
until the value of matches the coordinate value found in step 68.
X-axis motor control circuit 1g to drive motors 5 and 9
, it is sufficient to input a drive signal to the Y-axis motor control circuit 1g. The microcomputer M can determine whether the movement of the stage has ended or not by checking whether the coordinate values obtained by the counters 6b and 10b match the target coordinate values.

(Effects of the Invention) As described above, according to the present invention, a predetermined position on the substrate can be automatically brought into the observation field of view without using a pre-alignment device.

In the case where a pre-alignment device is used, a substrate with a two-dimensional image is transported onto an X-Y stage by a loading arm, etc., but in the present invention, transportation errors caused by the loading arm, etc. and pattern misalignment errors caused by printing on the wafer periphery are eliminated. It is more accurate because there is no room for intervention.

[Brief explanation of drawings]

Figure 1 is a diagram of the first embodiment of the present invention, Figure 2 is a diagram for explaining operations for coordinate transformation when a wafer is used as a substrate, and Figure 3 is a diagram showing the field of view of the observation device. diagram showing,
FIG. 4 is a block diagram of a second embodiment of the present invention, and FIGS. 5 and 6 are flowcharts of a microcomputer used in the second embodiment of FIG. 4. (Explanation of symbols of main parts) 1...Wafer, 2...X direction stage, 3...Y
Direction stage, 4, 8... Lead screw, 5... X direction motor, 6.10... Rotary encoder, 7.
... base, 9 ... Y-direction motor, 11 ... observation device, 12 ... input designation means, 13 ... calculation storage means,
14... Storage means, 15... Conversion means, 16...
Operation command means, 17... Control means, 18°19...
Drive circuit, M... microcomputer.

Claims (1)

[Scope of Claim] A microscope apparatus for observing a pattern on a substrate constituted by a wafer or a mask, comprising: an X-Y stage; a drive means for driving the X-Y stage in the X-Y direction; An observation device for observing a pattern on a substrate placed on a Y stage;
coordinate signal output means for outputting a coordinate signal and a Y-coordinate signal; storage means for storing coordinate values of measurement points in a substrate coordinate system defined with the substrate as a reference; and X-coordinates at at least two input positions. Signal and Y
calculation storage means for calculating and storing a conversion formula between the substrate coordinate system and the stage coordinate system from a set of coordinate signals; and calculating the coordinate values stored in the storage means using the conversion formula by the calculation storage means a converting means for converting into an X coordinate signal and a Y coordinate signal, and a control signal to the driving means so that the X coordinate signal and Y coordinate signal output by the coordinate signal output means are equal to each of the converted coordinate signals. a control means for inputting a coordinate signal for determining a substrate coordinate system into the calculation storage means;
A microscope apparatus comprising: operation command means for operating the control means.