KR100686806B1 - Method of pattern exposure for substrate using laser scanner - Google Patents

Abstract

A method of pattern exposure for a substrate using a laser scanner is provided to increase a processing speed and reduce a position error of a pattern in an exposure system using a scanning optic system. A laser generation unit generates laser pulses and irradiates the laser pulses to a galvanometer(40). The galvanometer reflects the laser pulses to a substrate(60) by operating a scan mirror thereof. A plurality of partial patterns are formed on a predetermined section on the substrate by reflecting the laser pulses to the substrate. The laser generator adjusts a time interval between the laser pulses in order to adjust a position between the partial patterns.

Description

Method of pattern exposure for substrate using laser scanner

1 is a configuration diagram illustrating a part of a basic configuration of a laser scanner;

2 is a configuration diagram for explaining the pulse interval control signal is input to the laser generator while the substrate continuous processing in the laser scanner according to an embodiment of the present invention,

FIG. 3 is a block diagram illustrating a process of correcting a substrate movement direction error due to a mismatch between a stage synchronizing signal and a scanner control cycle start in a laser scanner according to another embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device patterning process using a laser, and more particularly, to a method of performing pattern exposure on the entire surface of a substrate of a display device using a laser scanner.

In order to form a conductive pattern and a phosphor film on a substrate for forming a panel of a display device, printing or photolithography (exposure method) is usually used. The trend of larger screens for display devices continues, and in particular, PDPs (plasma display panels) are aiming for large screens. In addition, in recent years, a multi-faceted method, which is a method of making several substrates from a single plate, has been developed for productivity and cost reduction of a substrate used in a flat panel display product.

Therefore, there is a demand for a method capable of accurately and efficiently exposing a pattern on a large substrate for screen enlargement and a multi-faceted method. When forming a pattern on the display device using photolithography, it is difficult to cover the entire large screen with one exposure, so that a method of dividing the substrate into regions and performing exposure by a stepper method may be proposed and used. However, since the stepper method repeats movement and stoppage, there is a problem that time efficiency is inferior in processing a large screen substrate.

Accordingly, a scanner method of forming a repeating pattern by scanning a substrate in one axis direction or one axis and another axis direction by using a galvanometer while moving the substrate in one axis direction is widely used. In addition, the development of a pattern forming apparatus using a laser that can replace the existing exposure apparatus using an ultraviolet lamp has been made.

The construction of a scanning optical system using a scanner with a galvanometer and continuous processing with a laser by moving a workpiece at a constant speed is already common in many devices that process or expose using a laser. This is the structure used. However, as the substrate becomes larger, the processing speed required for the process is gradually increased to increase the process efficiency. Therefore, errors due to distortion caused by the aberration of the optical system, synchronization problems of the object moving stage and the scanning optical system, and the like appear gradually. This error, in turn, makes it difficult to make high-precision processing of patterns through laser scanners.

The present invention is to solve the above-described problems, substrate pattern exposure using a laser scanner that can reduce the error appearing as the moving speed of the substrate, that is, the required processing speed is increased without improving the performance of the existing laser scanner It is an object to provide a method.

According to an aspect of the present invention for achieving the above object, the substrate pattern exposure method while moving the substrate to be processed at a constant speed in one axial direction, while irradiating a plurality of laser pulses while moving the scan maze of the galvanometer laser pulse In the substrate pattern exposure method using a laser scanner to form a pattern corresponding to at least a predetermined period on the substrate by reflecting through a scan maze, the substrate is irradiated to the substrate by adjusting the time or the period of the laser pulse between the plurality of laser pulses It is characterized by adjusting the position of the laser pattern.

According to another aspect of the present invention for achieving the above object, the substrate pattern exposure method, the substrate pattern exposure method by irradiating a plurality of laser pulses while moving the substrate to be processed at a constant speed in one axial direction of the galvanometer A substrate pattern exposure method using a laser scanner that forms a pattern corresponding to at least a predetermined period on a substrate by reflecting a laser pulse through the scan labyrinth while moving the scan maze, the starting point of the stage synchronization signal of the laser scanner and the starting point of control of the scanner Detecting a time difference of the step; calculating a position error based on the detected time difference; and performing a position correction by varying the speed of the labyrinth direction of the substrate moving axis of the galvanometer of the scanner. It features.

In the method of the present invention, the step of correcting the position of the galvanometer is reflected in the initial acceleration period until the galvanometer maze starts to move and the laser pulse is irradiated, so that the exposure can be performed at the correct position from the first laser pulse shot. desirable.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

When a specific pattern is to be repeatedly processed at regular intervals using a laser, as shown in FIG. 1, a laser pulse or a laser beam is passed through the illumination optical system 20 and the exposure mask or the pattern mask 30 in the laser generator 10. Afterwards, a galvanometer scanner or a galvanometer 40 is used to change the direction, and then the image is imaged on the processed surface or the exposure surface of the substrate 60 on the stage through the imaging optical system 50. use. If a pattern shape is not particularly required, a circular passage may be used without an exposure mask. When a processing object such as a substrate is a large area, the substrate 60 is mounted on a stage so as to be movable on the workpiece in each axial direction forming a three-dimensional shape. The maze reflecting the laser in the galvano scanner can be achieved using one labyrinth 42 which can be adjusted in both axial directions or two labyrinths which are adjusted in each axial direction. These two approaches can be used interchangeably with each other. Here, for example, two axial mazes are used, one in each axial direction.

When exposure occurs, one of the two axial labyrinths of the scanner becomes the main scan maze, and the stage for moving the workpiece moves in a direction perpendicular to the main scanning direction, so that continuous processing occurs. In this case, when the exposure is performed while the auxiliary scan maze that is in charge of the auxiliary scan direction of the galvano scanner, that is, the axis capable of adjusting the laser pulse reflection in the moving direction of the substrate, moves at a constant speed in the same direction in consideration of the moving speed of the substrate. Despite the movement of the substrate, parallel patterns can be obtained in the main scan direction.

Usually, the main scan axis maze shifts from left to right for one motion signal alternately from right to left for the next motion signal, and the secondary scan axis labyrinth moves up and down in the direction of substrate 60 movement of the stage, , Quickly return to the initial position down and then move up to the bottom. In addition, a plurality of laser pulses are usually generated for one operation signal, and a plurality of repeated pattern exposures are performed for a predetermined period in the main axial direction. The laser pulse image is formed side by side in the main scan axis direction on the substrate 60, but the image by the two mazes of the galvanometer 40 is formed in a diagonal direction on a fixed stage basis. In the initial acceleration section of the maze, no pulse is generated so that the pattern is not exposed until the initial position is obtained.

For this processing, pulses of a predetermined time interval are generated according to the movement of the stage, and a signal synchronized in the control circuit board 70 may be input to the maze driving motor and the laser generator 10 of the galvano scanner.

In such a configuration, in order to increase the accuracy of the exposure process, a method of increasing the precision of the galvano scanner and the stage driving should be generally used. In addition to increasing the accuracy of the scanner and the stage, two techniques are used to improve the accuracy of the exposure process.

The first is to change the scan angular velocity of the galvanometer 40 to correct the aberration of the scan lens used throughout the scanner. If a high positional accuracy is required, the positional error occurring in the image field should be compensated for by the aberration of the scanning lens or the error of the optical alignment. In general, a method of mathematically setting a model by measuring distortion of an image area and compensating for a previously measured distortion when controlling a movement of a scanner is used. As a modeling method, a well-known technique that can obtain a model with sufficiently high precision by statistically analyzing the measurement data can be used. Therefore, in the case of a high speed raster scan, the result is that the angular velocity of the labyrinth of the galvanometer 40 is not constant but changes.

The second is to synchronize the movement of the stage and the scanner. After the stage starts moving at a constant speed, it generates a signal every time it passes a certain distance, and the scanner receives this signal and performs one process (exposure operation). With this configuration, the vertical error of the pattern does not accumulate, and it is possible to compensate for the influence due to the speed of the stage.

In the precision compensation method as described above, as the processing speed, that is, the moving speed of the substrate 60 increases, the precision may decrease due to the following causes.

First, when compensating aberration distortion through the scanner speed, the labyrinth of the galvanometer 40 cannot follow the constant velocity angular motion and follows a complicated speed trajectory with time. If the processing speed is high, the reaction of the motor driving the maze cannot be made quickly enough. Therefore, the tracking performance along the speed trajectory for the aberration distortion compensation in the maze driving becomes worse, and as a result, the error increases at the position where the pattern is formed.

Next, in the synchronization problem between the stage and the galvanometer 40, the control circuit board 70 of the galvanometer measures the signal coming out of the stage at regular intervals, and when the signal is detected, the processing is performed. Therefore, in the case of the vertical direction error in the main scan direction, the position error corresponding to the product of the control period of the scan controller and the stage speed is the maximum error. In other words, the longest time from when the stage signal is generated until the scanner responds is the same as the control period of the scan controller, and the stage progresses during this time, so the distance multiplied by the distance becomes a position error.

The present invention provides a method of avoiding two problems in which the precision of the position of pattern formation at the high speed machining is inferior, and maintaining the precision of the pattern formation position even at the high speed machining.

According to the first aspect of the method, in order to correct distortion aberration, unlike the method of changing the rotational angular velocity of the labyrinth of the galvanometer 40 of the scanner to maintain a constant interval of a plurality of patterns formed during one operation, exposure is The aberration is corrected by adjusting the generation interval of the laser pulse during the operation. In this method, the maze angular velocity of the galvanometer 40 can be kept constant or given a constant change.

That is, irrespective of compensation by the movement of the galvanometer 40 maze to compensate for the positional error in the main scan direction, the laser generator in the control circuit board 70 of the galvanometer in the laser scanner as shown in FIG. The method of compensating the laser pulse period by changing the interval between the pulse generating signals (trigger signal) is also introduced in the (100).

When using this method, the labyrinth of the galvanometer 40 always performs constant velocity angular motion, that is, if the scan speed is constant, precise tracking performance is shown even at high speed. On the other hand, when the aberration of the lens of the scanning optical system 20 is large, the period variation range of the laser pulse can be kept small while adjusting the scan speed of the galvanometer 40 maze within one exposure operation. In this case, it is possible to change the laser pulse generation period in a relatively small width while changing the maze operation within the range that the speed tracking performance is maintained over time. Therefore, the period change of the laser pulse becomes severe, and it is possible to prevent the instability of the laser power, especially in a solid state laser or a gas laser.

According to a second aspect of the method of the present invention, first, after the signal is generated at the stage to compensate for an error caused by the time taken from the signal of the stage to the operation of the scanner, the time from the signal to the reaction of the stage is measured. . Then, the position error corresponding to this time is calculated and input to the galvanometer of the scanner to increase the initial acceleration of the maze to compensate for this error. The galvanometer controls the movement of the maze to move it toward the stage.

For the sake of clarity, let x be the main scan axis and y the minor scan axis perpendicular to it. The stage for moving the substrate as the workpiece moves in the y direction. In this case, the x-axis scan maze moves at a relatively very high speed compared to the y-axis scan maze and the y-axis scan maze moves at the same speed as the stage. After the synchronous signal comes out of the stage, the scan maze starts to accelerate, and when the constant velocity section is reached, the laser pulse is emitted to process.

At this time, the position error calculated according to the time difference from the stage signal to the scanner response is reflected in the position command of the y-axis scan maze, and the amount of error reflected is very small compared to the overall motion of the x-axis scan maze. Acceleration of the y-axis scan maze may end before the scan maze finishes the initial acceleration. 3 is a schematic system configuration diagram for error correction by a synchronization signal.

The two waveforms of Fig. 3 represent the stage synchronizing signal D and the control period signal E of the scanner, respectively. The time difference between the synchronization signal D and the scanner control period signal E is indicated by t. Each signal is input to a time difference detector 80 to obtain a time difference t, which is multiplied by a constant 72 such as the moving speed of the substrate 60 in the multiplier 71 of the control circuit board 70 '. The result of the multiplication is in the accumulator 75, which is added to the x- and y-axis displacement values obtained from the register 73 to generate new displacement data, and controls to adjust the scan maze of the galvanometer 40 according to the displacement data. The controller 77 of the circuit board 70 'gives a change signal in the form of a current for correcting the position of the scan maze. This signal is given to the scan labyrinth drive motor of the galvanometer 40 to change the laser pulse scan position on the substrate 60 on the stage, like a dashed line arrow to a solid line arrow.

According to the present invention, in the exposure system for continuously processing the same pattern using a scanning optical system using a laser scanner, while increasing the processing speed, it is possible to precisely reduce the position error of the pattern.

Claims (8)

While moving the substrate to be processed at a constant speed in one axial direction, The laser generator generates a plurality of laser pulses and irradiates them with a galvanometer, In the galvanometer is a substrate pattern exposure method using a laser scanner to form a plurality of partial patterns corresponding to at least a predetermined period on the substrate by reflecting the plurality of laser pulses to the substrate while moving the built-in scan maze, And controlling the position of the plurality of partial patterns by adjusting a time interval between the plurality of laser pulses in the laser generator. The method of claim 1, The scan maze of the galvanometer consists of an adjustable portion in one axis direction and the other axis direction perpendicular to the one axis direction in which the substrate is moved, Move the scan maze portion in one axial direction in the one axial direction and simultaneously move the scan maze portion in the other axial direction to irradiate the laser pulse to the substrate, The method of exposing a substrate pattern using a laser scanner, characterized in that the plurality of partial patterns are arranged at a predetermined interval in at least a predetermined section of at least one row in the other axial direction. The method according to claim 1 or 2, The scan maze is a substrate pattern exposure method using a laser scanner, characterized in that for moving the laser pulse at a constant angular velocity. The method of claim 2. And the scan maze is adjusted to be equal to the moving speed of the substrate in the one axial direction during the time when the laser pulse is irradiated. The method according to claim 1 or 2, And said scan maze moves at varying angular velocities during the time the laser pulse is irradiated. While moving the substrate to be processed at a constant speed in one axial direction, The laser generator generates a plurality of laser pulses and irradiates them with a galvanometer, In the galvanometer is a substrate pattern exposure method using a laser scanner to form a plurality of partial patterns corresponding to at least a predetermined period on the substrate by reflecting the plurality of laser pulses to the substrate while moving the built-in scan maze, Detecting a time difference between a start point of a synchronization signal of a stage for moving the substrate and a start point of a scan control of the galvanometer; Calculating a displacement error in the substrate moving direction in consideration of the detected time difference and the moving speed of the substrate; And performing position correction by changing the substrate moving axial velocity of the built-in scan maze of the galvanometer reflecting the error. The method of claim 6, The step of performing the position correction is a substrate pattern exposure method using a laser scanner, characterized in that the initial acceleration section of the scan maze in the galvanometer. The method of claim 6, And performing pattern exposure on the substrate after scanning the plurality of laser pulses and reflecting the scan labyrinth of the galvanometer after performing the position correction. Way.

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