JP4320796B2 - Pattern position measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pattern position measuring apparatus that measures the position of a pattern formed on the surface of a substrate such as a mask, reticle, or wafer.
[0002]
[Prior art]
Conventionally, a pattern position measuring apparatus has been used to detect whether a pattern formed on a mask, reticle, or wafer (hereinafter referred to as a substrate) is formed as designed. In a conventional pattern position measuring apparatus, a substrate on which a pattern is formed is placed on a substrate placing portion on a stage, and an operator coordinates coordinates of the position on the substrate with respect to a predetermined reference axis (hereinafter referred to as measurement position coordinates) from an input device. The input device sends a measurement start request including the measurement position coordinates to the control device. The control device that has received the measurement start request drives the stage while monitoring the position information of the stage from the interferometer system, and moves the stage to an initial position where the pattern of the region including the measurement position coordinates can be measured. Next, the stage is sequentially moved from an initial position in a predetermined direction (for example, a direction of a predetermined reference axis) according to a command from the control device, and relative scanning is performed while irradiating the substrate surface with spot light from the optical device. During this relative scanning, if spot light hits the pattern edge on the substrate surface, the scattered light is received by the light receiving element. An edge detection signal from the light receiving element is input to the control device. The control device to which the edge detection signal is input reads the position of the pattern edge from the interferometer system, and displays the relationship between the position of the pattern edge and the measurement position coordinate on the display device. Thus, the operator can detect whether or not the pattern is formed on the substrate as designed by appropriately setting the measurement position coordinates.
[0003]
[Problems to be solved by the invention]
In the above-described pattern position measuring apparatus, it is common to measure a pattern composed of components parallel to a predetermined reference axis, for example, a cross pattern, with respect to the substrate. Therefore, when the operator designates the measurement position coordinates described above in order to detect whether or not a pattern is formed at a predetermined position, the coordinates of the design reference point (such as the design coordinate value of the pattern center) ( Hereinafter, the measurement position coordinates can be calculated by simply adding the distance to the measurement target position to the design value coordinates of the reference point).
[0004]
However, recently, a pattern formed on a substrate has become complicated, and a pattern obtained by rotating a conventional pattern with respect to a reference coordinate axis on a substrate (hereinafter referred to as an oblique pattern) has come to be used. Therefore, it is necessary to measure the coordinates and line width of the oblique pattern with a pattern position measuring device. However, when measuring an oblique pattern, it is necessary to recalculate the measurement position coordinates using a trigonometric function from the center coordinates (design value) and the pattern angle (design value). However, the operator himself must perform this calculation again. In addition, there is a problem in that the overall throughput (processing amount per unit time) is reduced as a result.
[0005]
An object of the present invention is to provide a pattern position measuring apparatus that can reduce the troublesomeness of an operator and improve the throughput of the pattern position measuring process.
[0006]
[Means for Solving the Problems]
1 to FIG. 3 showing an embodiment of the present invention, the above object is to provide a two-dimensional pattern (1) formed on the surface of a substrate (10) placed on a stage (15). In a pattern position measuring apparatus for measuring a specific position, a function for obtaining a design value coordinate of a predetermined position based on a design value coordinate of a reference point of the pattern (1), a design value angle, and a distance from the reference point is stored. A storage unit (22), an input unit (23) for inputting design value coordinates, design value angles, and distances, and design of a predetermined position by substituting the input design value coordinates, design value angles, and distances into functions. This is achieved by a pattern position measuring apparatus comprising a calculation unit (24) for calculating value coordinates.
Here, the distance from the reference point may be a distance in the reference axis direction on the two-dimensional plane from the reference point, or may be a linear distance from the reference point to a predetermined position.
[0007]
According to the pattern position measuring apparatus of the present invention, when the design value coordinates, the design value angle, and the distance from the reference point are input from the input unit (23), the design value coordinates input by the calculation unit (24), The design value coordinates at a predetermined position are calculated by substituting the design value angle and distance into the function stored in the storage unit (22). Therefore, the design value coordinates of the predetermined position of the pattern (1) can be calculated easily and quickly, and the throughput of the pattern position measurement process is improved.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
A pattern position measuring apparatus according to an embodiment of the present invention will be described with reference to FIGS. First, a schematic configuration of the pattern position measuring apparatus according to the present embodiment will be described with reference to FIG.
[0009]
The substrate 10 having a predetermined pattern formed on the surface is placed on a substrate placing portion (not shown) provided on the stage 15. An objective lens 11 is disposed on the substrate 10 through a slight gap. An optical device 12 is disposed on the objective lens 11, and the pattern image on the surface of the substrate 10 is enlarged by the objective lens 11 and formed at a predetermined position in the optical device 12. A laser light source is provided in the optical device 12 and projects a laser spot onto the substrate 10 through the objective lens 11. In general, since the substrate pattern has fine uneven edges, scattered light or diffracted light is generated at the edge portion when the spot light is scanned relatively. The four light receiving elements 50 a, 50 b, 51 a, 51 b provided around the objective lens 11 receive the scattered light and the like, detect edges, and output edge detection signals to the main controller 20. Since this edge detection method is disclosed in detail in Japanese Patent Publication No. 56-25964, description thereof is omitted here.
[0010]
The stage 15 on which the substrate 10 is placed moves two-dimensionally on the XY plane (horizontal plane) by a driving device 150 having a motor or the like. A control signal is input to the drive device 150 from the main control unit 20.
[0011]
The X-axis and Y-axis interferometer systems 14 a and 14 b irradiate the laser beam for length measurement onto the reflecting surface of the movable mirrors 13 a and 13 b fixed to the upper end of the stage 15. That is, the position (coordinate value) on the XY plane of the surface of the substrate 10 on the optical axis of the objective lens 11 is detected, and a position signal indicating the detected position is output, and this position signal is sent to the main controller 20. Entered.
[0012]
The main control device 20 includes a display device 21 such as a display device, a keyboard, a mouse device, and the like, and an input device that inputs design value coordinates of a pattern reference point, a design value angle, and a distance from the reference point. 23 is connected. The main controller 20 is connected to a storage device 22 that stores a design value coordinate of a pattern reference point, a design value angle, and a function for obtaining a design value coordinate at a predetermined position based on the distance from the reference point. ing. The main controller 20 calculates the design value coordinates at a predetermined position by substituting the design value coordinates, the design value angle, and the distance input from the input device 23 into a predetermined function stored in the storage device 22. 24.
[0013]
Next, an example of an oblique pattern used in this embodiment will be described with reference to FIG. FIG. 2 shows an oblique cross pattern.
The center design coordinate value (Xc, Yc) and the pattern design value angle θ of the pattern 1 are known. The distance L from the center of the pattern 1 to the measurement position is input by operator judgment. From these three parameters, the measurement position coordinates (Xm, Ym) are calculated by the following equation. The following equation is stored in the storage device 22 in the present embodiment.
[0014]
Xm = Xc + L × tan (π / 2−θ)
Ym = Yc + L
In FIG. 2, if the coordinate system is the first quadrant, the distance L in FIG. 2 is a negative value. The measurement direction is assumed to be the X direction.
[0015]
Next, a display example on the display device 21 of the present embodiment will be described with reference to FIG. In the display example shown in FIG. 3, the center design coordinate value (Xc, Yc) and the pattern design value angle θ of the pattern 1 to be substituted into the above formula, the distance from the center of the pattern 1 to the measurement position, and the measurement direction are as follows: It is possible to input from each input field displayed in the window format. The operator can input necessary numerical values while looking at this window.
[0016]
Next, the operation of the pattern position measuring apparatus according to this embodiment will be described. First, an operation for calculating design value coordinates at a predetermined position of a pattern designated by an operator will be described.
On the display screen as shown in FIG. 3, the operator can select the center design coordinate value (Xc, Yc) and pattern design value angle θ of the pattern to be substituted into the above formula, the distance from the center of the pattern to the measurement position, and the like. Enter. When the input is completed, the completion button at the lower left of the window shown in FIG. 3 is pressed.
[0017]
When the completion button is pressed, the input numerical data is sent to the arithmetic device 24. The arithmetic device 24 reads the above formula stored in the storage device 22 and substitutes the numerical data into the formula to design value coordinates. Is calculated.
Next, the pattern position measurement operation based on the calculated design coordinate value will be described.
In a state where the substrate 10 is placed on the stage 15, the main controller 20 receives the measurement start request from the input device 23, monitors the position information from the interferometer systems 14 a and 14 b, and controls the drive device 150. Control the stage 15 to move to the initial position. In this state, the initial position on the substrate 10 is on the optical axis of the objective lens 11 of the optical device 12.
Next, the main controller 20 controls the driving device 150 to sequentially move the stage 15 from the initial position, and relatively scans the spot light from the optical device 12 on the substrate surface. When spot light strikes the pattern edge on the substrate surface, scattered light is generated, and an edge detection signal is input to the main controller 20 from the light receiving elements 50a, 50b, 51a, 51b. The main controller reads the position of the pattern edge when the edge detection signal is input from the interferometer systems 14a and 14b. Whether or not the pattern on the substrate is formed as designed can be detected from the difference between the position information from the interferometer system and the calculated design value coordinates.
[0018]
Thus, according to the pattern position measuring apparatus of the present embodiment, when the design value coordinates, the design value angle, and the distance from the reference point are input from the input device 23, the design value input by the arithmetic device 24 is input. The design value coordinates at a predetermined position are calculated by substituting the coordinates, design value angle, and distance into the function stored in the storage device 22. Therefore, the design value coordinates of the predetermined position of the pattern can be calculated easily and quickly, and the throughput of the pattern position measurement process can be improved.
[0019]
The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the above-described embodiment, the oblique cross pattern has been described. However, the present invention is not limited to this, and can be applied to an oblique L-shaped pattern or an oblique I-shaped pattern instead of the oblique cross pattern. .
[0020]
【The invention's effect】
As described above, according to the present invention, design value coordinates of a predetermined position of a pattern can be calculated easily and quickly, and the throughput of processing related to pattern position measurement can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a schematic configuration of a pattern position measuring apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an oblique pattern formed on a substrate.
FIG. 3 is a diagram illustrating an example of a display screen for inputting design value coordinates, design value angles, and distances of a reference point of a pattern.
[Explanation of symbols]
1 pattern 10 substrate 11 objective lens 12 optical device 14a, 14b interferometer system 15 stage 20 main control device 21 display device 22 storage device 23 input device 24 arithmetic devices 50a, 50b, 51a, 51b light receiving element 150 driving device

Claims (1)

A pattern position measuring device for measuring a two-dimensional position of a pattern formed on a surface of a substrate placed on a stage ,
A stage provided with a substrate mounting for mounting a substrate on which a predetermined pattern is formed;
A driving device for driving the stage;
A laser light source, irradiating light emitted from the laser light source onto the substrate via an objective lens to project a laser spot, and magnifying the image of the pattern on the substrate surface with the objective lens to An optical device that forms an image at a predetermined position;
An input unit for inputting a design value coordinate of a reference point of the pattern, a design value angle, and a distance from the reference point;
A storage unit that stores a function for obtaining a design value coordinate at a predetermined position based on a design value coordinate of the input reference point of the pattern, the design value angle, and a distance from the reference point;
A calculation unit that calculates the design value coordinates of a predetermined position by substituting the input design value coordinates of the reference point of the pattern, the design value angle, and the distance from the reference point into a function stored in the storage device And
When the pattern position measuring apparatus allows the design value coordinates of the reference point of the pattern, the design value angle, and the distance from the reference point to be input to the input unit, the calculation unit is input to the input unit. The design value coordinate of the predetermined position is calculated by substituting the design value coordinate of the reference point of the pattern, the design value angle, and the distance from the reference point into a function stored in the storage unit, and the driving device Moves the stage to an initial position, the optical device projects a laser spot on the substrate with the light emitted from the laser light source through the objective lens, and the driving device moves the stage from the initial position. By moving the spot, the spot is relatively scanned on the surface of the substrate, the position information of the pattern edge when the edge detection signal of the pattern is output is obtained, and the pattern edge is obtained. Position information of the said from the difference between the calculated design value coordinate, a pattern position measuring device and detecting whether the pattern is formed as designed.

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