KR100223929B1 - Auto-correcting apparatus and control method of orthogonality of bar mirror in stepper for manufactuing semiconductor device - Google Patents

Abstract

The present invention is to ensure the linearity of the stage by ensuring the orthogonality detection and correction of the bar mirror of the stepper for the exposure process for semiconductor device manufacturing more accurately and automatically.

To this end, the present invention is a piezoelectric element (4) which is installed to be coupled to one side of at least one of the bar mirror (X) Y mirror (2), (3) installed on the X stage (1), and the mirror A piezoelectric element driving unit 5 for applying a predetermined voltage to the piezoelectric element 4 for position correction of the piezoelectric element; A sending control unit 6 is provided to set the bar mirror of any one of the X and Y bar mirrors 3 installed on the X stage 1 as a reference axis, and the other side, not the bar mirror set as the reference axis. While moving the stage by a certain pitch along the longitudinal direction of the bar mirror, the amount of bar mirror distortion with respect to the reference axis is detected using a laser interferometer and linearized to determine the position compensation amount of the bar mirror, and then the piezoelectric element driving uni Automatic device for correcting the mirror mirror orthogonality of the stepper for the semiconductor device manufacturing process, in which the position of the mirror is changed by applying a predetermined voltage to the piezoelectric element 4 by transmitting the drive signal, thereby ensuring the orthogonality of the mirror. It is a way.

Description

Automatic Barrier Orthogonality Corrector of Stepper for Semiconductor Device Manufacturing Process and Its Control Method

The present invention relates to an automatic device for correcting the bar mirror orthogonality of a stepper for a semiconductor device manufacturing process and a control method thereof. More specifically, the bar mirror orthogonality detection and the orthogonality correction of an exposure process for a semiconductor device can be performed. This can be done automatically so that the straightness of the stage can be guaranteed.

In general, an exposure process stepper for manufacturing a semiconductor device is a device for exposing a surface of a wafer by irradiating a wafer after reducing an image of an enlarged photosensitive plate at a predetermined magnification by using an optical lens. Will be used.

On the other hand, the stepper, which is an exposure apparatus for a conventional semiconductor device manufacturing process, ensures the straightness of the stage only when the X bar mirror 2 and the Y bar mirror 3 are kept in an orthogonal state, so that there is no overlay defect during exposure. Accurate exposure is performed.

To this end, the conventional stage movement distance detection system is a helium-neon laser 15 (He-Ne Laser) that provides a light source for distance detection, as shown in Figures 1 to 4, irradiated from the laser 15 Beam Bender 16 for converting the path of the beam, Beam Splitter 17 for splitting the beam path in two directions, Planar Mirror Interferer 23 for changing the characteristics of the beam, Planar mirror An X bar mirror 2 and a Y bar mirror 3 for receiving and reflecting light emitted from the interferer 23, a receiver 18 for receiving light reflected from the bar mirror, and pulses the received beam. a pulse converter 13 for converting pulses, and a stage drive board (not shown) for calculating and reading pulse waves, and a control unit 6 for controlling the devices. Unit).

On the other hand, the stage drive system is comprised as follows.

X stage unit equipped with X and Y axis mirrors, Y stage unit on which the X stage 1 is placed, and balls installed to transfer power to each stage for driving the X stage unit and Y stage unit It consists of a screw and the X stage drive motor 19 and the Y stage drive motor 20 to impart rotational force to each of the ball screws.

In the conventional stepper configured as described above, the X and Y stage unit driving motors 19 and 21 are driven to drive each stage in the X or Y direction, using a laser 15 interferometer for each reference axis of the mirror. The amount of torsion is measured, which will be described in more detail with reference to FIG. 2.

First, the beam from the laser 15 of the laser interferometer is routed through the beam bender 16 and enters the beam splitter 17, and is then spectroscopically separated by 50% in the beam splitter 17 in the X and Y directions. Will be moved to.

At this time, the frequency component f ₁ of the beam spectroscopically passed through the beam splitter 17 is directed to the receiver 18 through the path as shown in FIG. 3 in the interference plane mirror, and the frequency component f ₂ is the plane mirror interferer. Passing through (23) through the λ / 4 polarizer 21 as the f ₂ ′ component, into the mirror, then reflected off the mirror and back through the λ / 4 polarizer 21 into the interference plane mirror, f ₂ ″ It becomes a component and is directed to the receiver.

Here, the frequency component f ₁ is a P wave (longwave), the frequency component f ₂ is an S wave (horizontal wave), and since the f ₂ wave has passed through the λ / 4 polarizer 21 twice, the phase is changed λ / 2 times and P It becomes a wave.

On the other hand, the frequency components f ₁ and f ₂ ″ introduced into the receiver are synthesized and input to an auto detector in the receiver 18.

In the above path, the light component input to the receiver is converted into an electric signal (pulse) and sent to the pulse converter 13.

At this time, the phase of the electrical signal output from the receiver 18 changes depending on the position of the mirror, and the pulse converter 13 generates an up / down pulse in the direction of the abnormal change.

In addition, the number of pulses output at this time is proportional to the amount of change in the position of the mirror.

On the other hand, when the reference signal of the laser 15 enters the pulse converter 13, the phase difference with the measurement signal is calculated and pulsed and input to the control unit 6 through the interface board 14, whereby The control unit 6 accordingly calculates the amount of torsion with respect to the reference axis of the bar mirror and displays it on the control panel.

Using this principle, as shown in FIG. 4, it is possible to measure whether the stage moves with straightness by calculating the distance for each pitch with respect to the stage moving distance.

However, such a conventional mirror mirror system is not orthogonality is maintained when the mirror is deviated from the normal position, the straightness of the stage is poor.

In this case, since overlapping circuit patterns do not coincide with each other during exposure, they cause overlay defects that deviate from each other. Thus, the operator measures the error amount by coordinates to prevent the error and adjusts the wrong amount by using the adjustment bolt 24. This has to be corrected manually, which causes various problems.

That is, since the correction is made manually and the operation is not easy, it takes a lot of time to correct, and there are many problems such as contamination of the mirror and the possibility of damage by the operator's hand.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the barometric orthogonality detection of the stepper equipment for an exposure process for manufacturing a semiconductor device is performed more accurately, while the orthogonality correction of the mirror is automatically performed. SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic correction device for a bar mirror orthogonality of a stepper for an element manufacturing process and a control method thereof.

1 is a perspective view showing a stage system of a conventional stepper

2 is a block diagram showing a conventional laser interferometer

3 is a block diagram of a conventional mirror mirror torsion measurement and correction system

Figure 4 is a plan view of the main portion of the conventional bar mirror configuration

5 is a side view of the portion A of FIG.

6 is a perspective view showing a stage system of the present invention.

7 is a plan view showing the configuration of the mirror mirror driving apparatus of FIG.

8 is a longitudinal sectional view showing part B of FIG.

Figure 9 is a block diagram of the amount of measurement and correction system of the mirror mirror torsion of the present invention

10 is a plan view of the main portion showing the mirror mirror driving apparatus according to the present invention;

Explanation of symbols for the main parts of the drawings

1: X stage 2: X mirror

3: Y bar mirror 4: Piezoelectric element

5: Piezoelectric element drive unit 6: Control unit

7: Mounting groove 8: Mount frame

9: supporting rod 10: elastic member

11: Thread 12: Screw for pressure adjustment

In order to achieve the above object, the present invention is a piezoelectric element installed on one side of any one of the bar mirror of the X Y Y mirror installed on the X stage, and the piezoelectric element is expanded or contracted to correct the position of the mirror A piezoelectric element driving unit for applying a predetermined voltage to the piezoelectric element, a control unit for determining a correction amount of the bar mirror and sending a driving signal according to the correction amount to the piezoelectric element driving unit, and the other side of the bar mirror installed with the piezoelectric element. A bar mirror orthogonal degree automatic correction device of a stepper for a semiconductor device manufacturing process comprising a bar mirror support and restoring force imparting means, which is installed to be in contact with and provides support and restoring force to the bar mirror when the piezoelectric element is expanded and contracted.

On the other hand, another aspect of the present invention for achieving the above object is a piezoelectric element provided on one side of at least one bar mirror among the X and Y bar mirror provided on the X stage, and for the position correction of the bar mirror Stepper bar mirror having a piezoelectric element driving unit for applying a predetermined voltage to the piezoelectric element so that the piezoelectric element expands or contracts, and a control unit for transmitting a signal of a driving amount corresponding to the correction amount determined to the piezoelectric element driving unit. In the orthogonal automatic correction method, one of the X and Y mirrors installed on the X stage is set as the reference axis, and the stage is moved along the longitudinal direction of the other mirror rather than the bar mirror set as the reference axis. Moving the stage by a predetermined pitch; and for the axis orthogonal to the bar mirror set as the reference axis when the stage is moved by the predetermined pitch in the step. Detecting the amount of distortion of the mirror in the quasi-axis direction using a laser interferometer, and determining the amount of correction of the position of the mirror by linearizing the amount of distortion in the reference axis direction for each point from the reference position detected in the step And transmitting a driving signal to the piezoelectric element driving unit according to the correction amount determined in the step, and applying a predetermined voltage to the piezoelectric element from the piezoelectric element driving unit to vary the position of the mirror. A method of controlling a bar mirror orthogonality automatic correction device of a stepper for a semiconductor device manufacturing process performed.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 6 to 10.

Fig. 6 is a perspective view showing a stage system of the present invention, Fig. 7 is a plan view showing the bar mirror configuration of Fig. 6, and Fig. 8 is a longitudinal sectional view showing part B of Fig. 7, and the present invention is on the X stage 1. Piezoelectric element 4 which is installed to be coupled to one of the bar mirrors of any one of the X and Y bar mirrors 2 and 3 provided, and any of the X and Y bar mirrors 2 and 3 The piezoelectric element driving unit 5 which applies a predetermined voltage to the piezoelectric element 4 so that the piezoelectric element 4 expands or contracts to correct the position of the mirror, and the piezoelectric element driving unit 5 according to the amount of correction A control unit 6 for transmitting and transmitting a driving amount and a bar mirror on which the piezoelectric element 4 is installed, and providing support and restoring force to the bar mirror when the piezoelectric element 4 is expanded or contracted. Mirror support and restoring force imparting means.

At this time, the mirror support and restoring force applying means is coupled to the other side of the piezoelectric element (4) on the X stage (1) and the mounting frame (8) having a cylindrical installation groove (7) in the center, and the cylindrical installation A support rod having a flange portion 9a having a diameter larger than the diameter of the main shaft of the support rod 7 is formed at one end of the bar mirror side in the groove 7 so as to be movable forward and backward along the axial direction of the mount frame 8. (9) and an elastic member 10 such as a compression spring that is fitted on an outer circumferential surface of the support rod 9 to impart elasticity to the support rod 9.

At this time, one end of the compression spring, which is an elastic member, may be directly fixed to one end of the bar mirror 3 side of the support rod 9.

In addition, the thread 11 is formed on the inner surface of the inlet of the cylindrical installation groove 7 so that the size of the restoring force of the elastic member 10 is variable, and the screw 11 is tightened or loosened to move forward and backward. The pressure adjusting screw 12 that can vary the magnitude of the restoring force of the elastic member 10 is configured to be fastened.

Referring to the embodiment of the operation and operation of the present invention configured as described above as follows.

Fig. 9 is a block diagram of a bar mirror torsion measurement and correction system according to the present invention, and Fig. 10 is a plan view of main parts of the bar mirror driving device according to the present invention, in which the Y stage 22 constituting the stepper is driven from the reference point by the Y stage 22. As the motor 20 moves by a predetermined pitch in the Y-axis direction according to the driving of the motor 20, the amount of distortion at each point is measured using a laser interferometer.

At this time, the amount of twist refers to the amount of the bar mirror is twisted in the X-axis direction from the Y axis serving as a reference axis, the embodiment described later is described by taking the case that the piezoelectric element 4 is installed on the Y bar mirror (3) as an example. .

Here, since the operating principle of the laser interferometer for the amount of twist measurement at each point is the same as described previously, description thereof is omitted.

On the other hand, when the Y stage 22 is moved by a predetermined pitch, the amount of twist of the bar mirror in the X-axis direction at each point detected by the laser interferometer is controlled by the control unit via the pulse converter 13 and the interface board 14. (6), the control unit 6 calculates the amount of movement of the mirror.

Thereafter, the amount of twisting at each point is processed and linearized again in the control unit 6, whereby the position correction amount of the Y bar mirror according to the correction data value previously input to the data storage unit of the control unit 6 Is calculated.

In this way, when the Y bar mirror 3 position correction amount is calculated and then the drive amount for each position is signaled and transmitted from the control unit 6 to the piezoelectric element drive unit 5, the piezoelectric element drive unit 5 In the above, the position of the Y bar mirror 3 is adjusted by applying a voltage to the piezoelectric element 4.

That is, the piezoelectric element 4 is varied in the position of the Y bar mirror by being stretched or compressed according to the applied voltage.

At this time, the operation of the piezoelectric element 4 and the bar mirror support and restoring force applying means will be described in more detail with reference to FIG. 8.

For example, when the piezoelectric element 4 is tensioned by applying a voltage proportional to a correction amount in a state in which powers of different polarities are connected to the piezoelectric element 8, the Y bar mirror 3 is shown in FIG. The support rod 9 is pushed while moving to the right in the drawing, so that the support rod 9 compresses and compresses the compression spring which is the elastic member 10 embedded in the installation groove 7 of the mount frame 8. do.

Therefore, in this case, the support rod 9 and the elastic member 10 serve as a stopper that prevents the Y bar mirror 3 from moving rapidly in response to the displacement of the piezoelectric element 4.

On the other hand, when the deviation occurs in the opposite direction as described above, when the voltage according to the correction amount is applied in the state that the polarity of the power applied to both sides of the piezoelectric element 4 is changed, the piezoelectric element 4 is compressed in the opposite manner as described above. In this case, the support rod 10 pushes the Y bar mirror 3 to the left in the drawing of FIG. 8 by the restoring force of the elastic member 10 to correct the amount of twist of the Y bar mirror 3.

At this time, the flange portion 9a formed at one end of the bar mirror side of the support rod 10 is caught by the inner surface of the installation groove 7 so that the support rod 10 does not escape the installation groove 7. do.

On the other hand, Table 1 below shows an example of the X-axis movement distance measurement value for each point of the bar mirror according to the present invention.

TABLE 1

Y-coordinate value (unit: ㎛) X coordinate of steady state X coordinate value of abnormal state First point 2.5 2.5 2.5 2nd branch 10,000 2.5 3.0 Third point 20,000 2.5 3.2 4th branch 30,000 2.5 3.4 Point 5 40,000 2.5 3.6 6th branch 50,000 2.5 3.8 Branch 7 60,000 2.5 4.0 Branch 8 70,000 2.5 4.2 Branch 9 80,000 2.5 4.4 10th Branch 90,000 2.5 4.6 Branch 11 100,000 2.5 4.8 Branch 12 110,000 2.5 5.0 Branch 13 120,000 2.5 5.2 Branch 14 130,000 2.5 5.4 Branch 15 140,000 2.5 5.6 Branch 16 150,000 2.5 5.8 Branch 17 160,000 2.5 6.0 Branch 18 170,000 2.5 6.2

On the other hand, in the embodiment of the present invention, because the length of the bar mirror is divided into 18 points for convenience, the number of measuring points and distance can be arbitrarily determined by the operator.

The present invention allows the bar mirror orthogonality detection of the stepper equipment for an exposure process for semiconductor device manufacturing to be performed more accurately, while the orthogonality correction of the bar mirror is automatically performed.

In other words, by automatically detecting and correcting the orthogonality of the bar mirror by regular correction operation, the straightness of the stage caused by the orthogonality of the bar mirror is disturbed due to the vibration of the stage movement is eliminated. It is possible to prevent phosphorus defects.

In addition, since the orthogonality of the bar mirror is automatically corrected, the time required for correcting the orthogonality of the mirror is reduced, and the possibility of contamination of the bar mirror by the operator's hand that has occurred in the past can be reduced. The yield of the device manufacturing process is improved.

Claims (5)

A piezoelectric element installed to be coupled to one side of one of the X and Y bar mirrors installed on the X stage, A piezoelectric element driving unit for applying a predetermined voltage to the piezoelectric element such that the piezoelectric element is expanded or contracted to correct the position of the mirror; A control unit for determining a correction amount of the mirror and sending a driving signal according to the correction amount to the piezoelectric element driving unit; Stepper for the semiconductor device manufacturing process characterized in that the piezoelectric element is installed in contact with the other side of the bar mirror installed is provided with a mirror support and restoring force imparting means for imparting support and restoring force to the bar mirror during the expansion and contraction action of the piezoelectric element Bar mirror orthogonal automatic correction device. The method of claim 1, The mirror support and restoring force imparting means A mount frame coupled to the other side of the piezoelectric element on the X stage and having a cylindrical installation groove in the center thereof; A support rod having a flange portion having a diameter larger than that of the main shaft of the support rod so as not to escape the installation groove at one end of the bar mirror side; The bar mirror orthogonality automatic correction device of a stepper for semiconductor device manufacturing process, characterized in that it is composed of an elastic member inserted on the outer peripheral surface of the support rod to give elasticity to the flange of the support rod. The method of claim 2, A thread is formed on the inner surface of the inlet of the cylindrical installation groove, and the pressure adjusting screw is fastened to the thread, and the magnitude of the restoring force of the elastic member is variable according to tightening or loosening the pressure adjusting screw to move the screw forward and backward. A bar mirror orthogonal degree automatic correction apparatus of the stepper for semiconductor device manufacturing processes to be used. The method of claim 2 or 3, Automatic bar mirror orthogonality correction device of a stepper for semiconductor device manufacturing process, characterized in that the elastic member is a compression spring. Applying a predetermined voltage to the piezoelectric element so as to expand or contract the piezoelectric element provided on one side of at least one bar mirror among the X and Y bar mirrors installed on the X stage, and to correct the position of the bar mirror. In the method for automatically correcting the mirror mirror orthogonal degree of a stepper having a piezoelectric element driving unit and a control unit for signaling and transmitting a driving amount corresponding to the correction amount determined to the piezoelectric element driving unit, Setting the bar mirror of any one of the X and Y bar mirrors installed on the X stage as a reference axis to move the stage by a predetermined pitch in the longitudinal direction of the other bar mirror rather than the bar mirror set as the reference axis; Detecting the amount of bar mirror distortion in a direction of a reference axis with respect to an axis orthogonal to the bar mirror set as a reference axis when the stage is moved by a predetermined pitch using a laser interferometer; Determining the position correction amount of the mirror by linearizing the amount of distortion in the reference axis direction for each point from each of the reference positions detected in the step; Transmitting a driving signal to the piezoelectric element driving unit according to the correction amount determined in the step; A method of controlling a bar mirror orthogonality automatic correction device of a stepper for a semiconductor device manufacturing process, characterized in that the step of varying the position of the bar mirror by applying a predetermined voltage from the piezoelectric element driving unit to the piezoelectric element is performed sequentially.

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