Deep ultraviolet laser slow decay device and power adjusting method thereof

Abstract

The application discloses a kind of deep ultraviolet laser slow attenuators and power adjusting method thereof, belong to laser power control technical field, including optical path adjusting module, execution module, control module and signal feedback module.The application is realized laser power gradient adjustment by OD value accurate matching multiple sets of neutral density filter;Adopt the pneumatic structure of graphite piston-borosilicate glass cylinder, match special double-path vacuum control loop, realize the smooth movement of filter 5~8mm / s, avoid power mutation, simultaneously have the characteristics of lubrication-free clean operation, wide temperature range adaptation;Automatic reset to 100% power safety position when power failure, ensure the safety of subsequent start and process continuity of equipment.

Description

Technical Field

[0001] This invention relates to the field of laser power control technology, specifically to a deep ultraviolet laser slow attenuator and its power adjustment method. Background Technology

[0002] Lasers are the core light source in advanced semiconductor manufacturing processes and are widely used in wafer defect detection, particle detection, film thickness measurement, photolithography alignment, and precision micromachining of compound semiconductors.

[0003] In practical industrial applications, semiconductor laser equipment does not operate continuously at maximum power. Customers need to adjust the laser power in a gradient range of 1% to 100% according to different process requirements. Existing laser power adjustment solutions have the following core defects: single power, lack of precise level matching design, inability to achieve precise attenuation at multiple levels, and difficulty in adapting to the needs of refined semiconductor processes. Summary of the Invention

[0004] The purpose of this invention is to provide a deep ultraviolet laser slow attenuator and its power adjustment method to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, this invention provides the following technical solution: a deep ultraviolet laser slow attenuator, comprising an optical path adjustment module, an execution module, a control module, and a signal feedback module; The optical path adjustment module includes an incident end, an exit end, and at least two filters disposed between the incident end and the exit end, arranged along the horizontal optical axis. The execution module is used to drive the filter to move into / out of the laser optical path; The control module includes a power source and a control branch pipeline. The output end of the power source is connected to the execution module through the control branch pipeline and provides extension and retraction power to the extension and retraction end of the execution module. The signal feedback module includes a position switch for detecting the extension and retraction status of the extension and retraction end of the execution module and a pressure switch for detecting and controlling the kinetic energy in the shunt pipeline. The position switch and the pressure switch are all signal-connected to an external control unit.

[0006] Furthermore, the execution module is a vacuum cylinder, the power source is a vacuum source, the piston and cylinder body of the vacuum cylinder are made of graphite and borosilicate glass respectively, the piston is provided with a magnetic ring, and the position switch is a magnetic switch.

[0007] Furthermore, the filter is mounted on the telescopic end of the vacuum cylinder via a heat-insulating mirror mount with a high damage threshold.

[0008] Furthermore, the surface of the filter is coated with an anti-reflective film.

[0009] Furthermore, the vacuum source is a vacuum pump / vacuum generator, and a vacuum filter, a vacuum pressure gauge, a safety valve, and an electrically controlled solenoid valve are sequentially installed on the control branch pipeline from the vacuum source to the vacuum cylinder. A two-way vacuum throttle valve is installed at the connection between the control branch pipeline and the vacuum cylinder. The vacuum filter, vacuum pressure gauge, safety valve, and electrically controlled solenoid valve are connected to an external control unit.

[0010] Furthermore, a vacuum pressure reducing valve for controlling the vacuum level is installed on the control branch line located between the vacuum filter and the vacuum pressure gauge, and the vacuum pressure reducing valve is signal-connected to an external control unit.

[0011] Furthermore, a buffer pad is provided at the end of the inner wall of the vacuum cylinder.

[0012] Furthermore, the electrically controlled solenoid valve is a two-position three-way vacuum solenoid valve, and the slow attenuator also includes a power failure safety reset structure, which is a spring used to drive the extension and retraction end of the vacuum cylinder to contract.

[0013] A power regulation method based on a deep ultraviolet laser slow attenuator includes the following steps: S1: Initial Reset: When the slow attenuator is powered on, the external control unit starts the vacuum source and adjusts the two-position three-way vacuum solenoid valve to connect the vacuum cylinder entry chamber and the pressure relief end. The spring resets and drives the piston to move towards the exit chamber. The piston then drives the filter to exit the laser path through the telescopic end and the heat insulation mirror seat in sequence. After the magnetic switch in the vacuum cylinder exit chamber is detected, it feeds the signal back to the external control unit. S2: Adjusting the power level based on power demand: The external control unit controls the corresponding vacuum cylinder to drive the filter to enter / exit the laser optical path according to the required power, and the spring to deform / reset in order to adjust the power level. Then, the filter entry / exit status is detected by magnetic switch and pressure switch to lock the power level. S3: Power failure protection: When the slow attenuator suddenly loses power, the two-position three-way vacuum solenoid valve is de-energized and opens to release pressure. At the same time, the spring resets and pushes the piston to drive both filters out of the laser optical path, thereby locking the 100% power level and realizing power failure protection.

[0014] The beneficial effects achieved by this invention patent are as follows: 1. By combining at least two neutral density filters with precisely matched OD values, precise attenuation of laser at multiple levels can be achieved, perfectly adapting to the different process power requirements of semiconductor laser equipment from 1% to 100%, solving the problems of single gradient and low attenuation accuracy in existing adjustment schemes.

[0015] 2. The combination of graphite piston and borosilicate glass cylinder achieves ultra-low friction and lubrication-free operation, completely avoiding lubricant contamination of the semiconductor clean production line, resulting in no wear during long-term operation and a significantly extended service life.

[0016] 3. Under vacuum drive, the cylinder movement speed is precisely controlled at 5-8 mm / s through a two-way vacuum throttle valve, and with the help of a buffer pad, the filter can be smoothly inserted / removed.

[0017] 4. By using a spring in conjunction with a two-position three-way vacuum solenoid valve to automatically release pressure after power failure, it is ensured that all filters are removed from the laser beam path when the equipment loses power, and the laser power level is reset to 100% power level, ensuring the safety of subsequent equipment startup and the continuity of the process. 5. The vacuum pressure gauge, combined with the vacuum pressure reducing valve, effectively controls the vacuum level in the branch pipeline within the range of -60kPa to -80kPa, thereby achieving the effect of adjusting the stability of the vacuum level and further ensuring that the cylinder movement speed is accurately controlled within 5 to 8 mm / s. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the layout of a deep ultraviolet laser slow attenuator in Example 1; Figure 2 This is a cross-sectional view of the vacuum cylinder in Example 1; Figure 3 This is a flowchart of a power adjustment method for a deep ultraviolet laser slow attenuator in Example 2. Detailed Implementation

[0019] The present invention will be further described below with reference to the accompanying drawings.

[0020] Example 1

[0021] like Figure 1 As shown, Embodiment 1 discloses a deep ultraviolet laser slow attenuator, comprising: Optical path adjustment module, execution module, control module, and signal feedback module; The optical path adjustment module includes an incident end 1, an exit end 2 arranged along the horizontal optical axis, and at least two filters 3 (perpendicular to the horizontal optical axis) disposed between the incident end 1 and the exit end 2. The execution module is used to drive the filter 3 to move into / out of the laser optical path; The control module includes a power source and control branch lines. The output end of the power source is connected to the execution module in sequence through the electrically controlled solenoid valve a13 and the control branch line, and provides extension and retraction power to the extension and retraction end of the execution module. The signal feedback module includes a position switch 7 for detecting the extension and retraction status of the extension and retraction end of the actuator module and a pressure switch 6 for detecting and controlling the kinetic energy in the shunt pipeline. Both the position switch 7 and the pressure switch 6 are signal-connected to an external control unit (PLC / relay).

[0022] Furthermore, such as Figure 1-2 As shown, the execution module is a vacuum cylinder, the power source is a vacuum source, the piston 4 of the vacuum cylinder and the cylinder body of the vacuum cylinder are made of graphite and borosilicate glass respectively, the piston 4 is equipped with a magnetic ring 41, and the position switch 7 is a magnetic switch. Specifically, piston 4 divides the inner wall of the vacuum cylinder into an entry chamber and an exit chamber. There are two position switches 7, which are respectively located in the entry chamber and the exit chamber. The vacuum source is connected to the entry chamber of the vacuum cylinder through a control split line. When the filter 3 is inserted, the magnetic ring 41 is parallel to and in contact with the magnetic switch in the entry chamber, and vice versa. Specifically, when filter 3 is inserted, pressure switch 6 detects a vacuum level of -60 to -80 kPa, and when filter 3 is removed, pressure switch 6 detects a vacuum level of >0 kPa to normal atmospheric pressure. Specifically: Graphite has self-lubricating properties and forms a nanoscale transfer film on the glass surface, thereby reducing the friction between the inner wall of the cylinder and the piston. At the same time, no lubricating oil needs to be added, and no debris is generated due to wear.

[0023] Furthermore, such as Figure 1 As shown, the filter 3 is installed on the telescopic end of the vacuum cylinder through two heat-insulating mirror mounts 32 with high damage thresholds.

[0024] Furthermore, the surface of filter 3 is coated with an anti-reflective film.

[0025] Furthermore, such as Figure 1 As shown, the vacuum source is a vacuum pump / vacuum generator. A vacuum filter 12, a vacuum pressure gauge 10, a safety valve 9, and an electrically controlled solenoid valve 8 are sequentially installed on the main pipeline of the control branch line from the vacuum source to the vacuum cylinder. A two-way vacuum throttle valve 5 is installed at the connection between the control branch line and the vacuum cylinder. The vacuum filter 12, vacuum pressure gauge 10, safety valve 9, and electrically controlled solenoid valve 8 are connected to an external control unit. Specifically: Vacuum filter 12 filters the air in the control branch pipeline to prevent debris or impurities in the air from flowing between the vacuum source and the vacuum cylinder and increasing losses. When the vacuum pressure gauge 10 detects an overload in the control branch pipeline, it sends the information to the external control unit. The external control unit then activates the safety valve 9 to release pressure, thereby preventing equipment damage. The two-way vacuum throttle valve 5 controls the air flow rate, thereby precisely controlling the cylinder movement speed at 5-8 mm / s, thus preventing the piston 4 from generating debris due to high-speed impact on the inner wall of the cylinder.

[0026] Furthermore, such as Figure 1 As shown, a vacuum pressure reducing valve 11 is installed on the control branch line between the vacuum filter 12 and the vacuum pressure gauge 10 to control the vacuum level to -60 to -80 kPa gauge pressure. The vacuum pressure reducing valve 11 is connected to an external control unit. When the vacuum pressure gauge 10 detects that the control branch line exceeds -60 kPa or is lower than -80 kPa, it feeds back information to the external control unit. The external control unit controls the vacuum pressure reducing valve 11 to adjust the valve core opening degree, thereby achieving the effect of adjusting the stability of the vacuum level.

[0027] Furthermore, such as Figure 2 As shown, a buffer pad 43 is provided at the inner wall end of the vacuum cylinder. The buffer pad 43 is configured to provide buffer when the piston 4 contacts the inner wall of the cylinder end, further preventing the piston 4 from generating debris due to high-speed impact on the inner wall of the cylinder, so as to achieve smooth entry / exit of the filter. Preferably, the cushioning pad 43 is made of polyurethane.

[0028] Furthermore, such as Figure 1 As shown, the electrically controlled solenoid valve 8 is a two-position three-way vacuum solenoid valve. The input and output ends of the two-position three-way vacuum solenoid valve are used to connect the vacuum source and the vacuum cylinder, and the other end of the two-position three-way vacuum solenoid valve is a pressure relief end for pressure relief. Furthermore, the electrically controlled solenoid valve is a two-position three-way vacuum solenoid valve, and the slow attenuator also includes a power failure safety reset structure, which is a reset spring used to drive the extension and retraction end of the vacuum cylinder to contract. Preferred, such as Figure 2 As shown, the spring 42 is disposed in the cylinder body, and the two ends of the spring 42 abut against the polyurethane buffer pad 43 on the inner wall end of the cylinder body near the heat insulation mirror seat 32 and the end of the piston 4 near the heat insulation mirror seat 32, respectively. Preferably, the spring 42 is disposed outside the cylinder body, and the two ends of the spring 42 are fixedly connected to the heat insulation mirror seat 32 and the end of the cylinder body on the opposite side, respectively.

[0029] Example 2

[0030] Please see Figure 3 A power regulation method based on a deep ultraviolet laser slow attenuator includes the following steps: S1: Initial Reset: The slow attenuator is powered on, the external control unit starts the vacuum source, and adjusts the two-position three-way vacuum solenoid valve to connect the vacuum cylinder entry chamber and the pressure relief end. The spring 42 is decompressed and fully extended. The spring 42 pushes the piston 4 to move towards the exit chamber. The piston 4 then drives the filter to exit the laser light path (the path the laser passes through) through the telescopic end and the heat insulation mirror seat in sequence. After the magnetic switch in the vacuum cylinder exit chamber is detected, it feeds back the signal to the external control unit. S2: Adjusting the power level based on power demand: The external control unit controls the corresponding vacuum cylinder to drive the corresponding filter 3 to enter / exit the laser optical path according to the required power, and the spring deforms / resets to adjust the power level. Then, the magnetic switch and pressure switch 6 detect the filter entry / exit status and lock the power level. Specifically, the required power level adjustment is any degree between 1% and 100%, the number of filters 3 is 99, the transmittance of one of the filters 3 is 99%, and under the premise of keeping the transmittance of the filter 3 with 99% transmittance in the laser optical path (power level 99%), for each additional filter 3 inserted, the sum of the transmittance of the filters 3 superimposed in the laser optical path decreases by 1%.

[0031] Furthermore, there are two filters 3, one of which has a transmittance of 22%. The sum of the transmittances of the two filters is 5%. The filter 3 with a transmittance of 22% has an OD (optical density / optical density) of 0.657, while the other filter 3 has an OD of 0.644 and a transmittance of 22.7%. The total OD of the two filters is approximately 1.301, corresponding to a laser transmittance of 5%. The required power adjustment levels are 5% / 22% / 100%. If the power needs to be adjusted to 22%, the external control unit controls the two-position three-way vacuum solenoid valve on the control branch line connected to the vacuum cylinder with the transmittance to connect the input and output ends. The negative pressure generated by the vacuum source is delivered to the cutting cavity of the vacuum cylinder through the control branch line. The negative pressure drives the piston 4 in the vacuum cylinder to drive the filter 3 with a transmittance of 22% to cut into the laser beam path through the telescopic end and the heat insulation mirror seat 32 in sequence. At this time, the spring 42 deforms. At the same time, the magnetic switch and pressure switch 6 located in the cutting cavity of the vacuum cylinder are both detected and fed back to the external control unit, thereby completing the locking of the 22% power level. If it is necessary to adjust to the 5% power level, the external control unit controls the two two-position three-way vacuum solenoid valves to connect the input and output ends. The two vacuum cylinders push the two filters 3 into the laser beam path respectively. The spring 42 deforms. At the same time, the magnetic switch and pressure switch 6 located in the vacuum cylinder insertion chamber are detected and locked. If it is necessary to adjust to the 100% power level, the external control unit controls the two two-position three-way vacuum solenoid valves to connect the vacuum cylinder entry chamber and the pressure relief end. The spring 42 returns to its original position and drives the piston 4 to drive the two filters 3 to exit the laser beam path. At the same time, the magnetic switch and pressure switch 6 located in the vacuum cylinder exit chamber are detected and then locked to the 100% power level. S3: Power failure protection: When the slow attenuator suddenly loses power, the two-position three-way vacuum solenoid valve is de-energized and automatically depressurizes. At the same time, the spring 42 resets and drives the piston 4 to drive both filters 3 out of the laser optical path, thereby completing the locking of the 100% power level and realizing power failure protection.

[0032] Specifically, the power level lock when filter 3 is inserted into the laser optical path is as follows: the vacuum source continuously and stably outputs negative pressure to the vacuum cylinder's insertion chamber when filter 3 is fully inserted into the laser optical path, or the solenoid valve 8 is fully closed, maintaining the negative pressure from the solenoid valve 8 to the vacuum cylinder's insertion chamber at the negative pressure when filter 3 is fully inserted into the laser optical path.

[0033] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A deep ultraviolet laser slow attenuator, characterized in that, It includes an optical path adjustment module, an execution module, a control module, and a signal feedback module; The optical path adjustment module includes an incident end, an exit end, and at least two filters disposed between the incident end and the exit end, arranged along the horizontal optical axis. The execution module is used to drive the filter to move into / out of the laser optical path; The control module includes a power source and a control branch pipeline. The output end of the power source is connected to the execution module through the control branch pipeline and provides extension and retraction power to the extension and retraction end of the execution module. The signal feedback module includes a position switch for detecting the extension and retraction state of the extension and retraction end of the execution module and a pressure switch for detecting and controlling the kinetic energy in the shunt pipeline. Both the position switch and the pressure switch are signal-connected to an external control unit.

2. The deep ultraviolet laser slow attenuator according to claim 1, characterized in that: The execution module is a vacuum cylinder, the power source is a vacuum source, the piston and cylinder body of the vacuum cylinder are made of graphite and borosilicate glass respectively, the piston is provided with a magnetic ring, and the position switch is a magnetic switch.

3. The deep ultraviolet laser slow attenuator according to claim 2, characterized in that: The filter is mounted on the telescopic end of the vacuum cylinder via a heat-insulating mirror mount with a high damage threshold.

4. The deep ultraviolet laser slow attenuator according to claim 3, characterized in that: The surface of the filter is coated with an anti-reflective film.

5. A deep ultraviolet laser slow attenuator according to claim 4, characterized in that: The vacuum source is a vacuum pump / vacuum generator. A vacuum filter, a vacuum pressure gauge, a safety valve, and an electrically controlled solenoid valve are sequentially installed on the control branch line from the vacuum source to the vacuum cylinder. A two-way vacuum throttle valve is installed at the connection between the control branch line and the vacuum cylinder. The vacuum filter, vacuum pressure gauge, safety valve, and electrically controlled solenoid valve are connected to an external control unit.

6. A deep ultraviolet laser slow attenuator according to claim 5, characterized in that: A vacuum pressure reducing valve for controlling the vacuum level is installed on the control branch line located between the vacuum filter and the vacuum pressure gauge. The vacuum pressure reducing valve is signal-connected to an external control unit.

7. A deep ultraviolet laser slow attenuator according to claim 6, characterized in that: A buffer pad is provided at the end of the inner wall of the vacuum cylinder.

8. A deep ultraviolet laser slow attenuator according to claim 7, characterized in that: The electrically controlled solenoid valve is a two-position three-way vacuum solenoid valve, and the slow attenuator also includes a power failure safety reset structure, which is a spring used to drive the extension and retraction end of the vacuum cylinder to contract.

9. A power adjustment method for a deep ultraviolet laser slow attenuator, characterized in that: Includes the following steps: S1: Initial Reset: The slow attenuator is powered on, the external control unit starts the vacuum source, and adjusts the two-position three-way vacuum solenoid valve to connect the vacuum cylinder entry chamber and the pressure relief end. The spring is decompressed and fully extended. The spring pushes the piston to move towards the exit chamber. The piston then drives the filter to exit the laser optical path through the telescopic end and the heat insulation mirror seat in sequence. After the magnetic switch is detected in the vacuum cylinder exit chamber, it feeds the signal back to the external control unit. S2: Adjusting the power level based on power demand: The external control unit controls the corresponding vacuum cylinder to drive the filter to enter / exit the laser optical path according to the required power, and the spring to deform / reset in order to adjust the power level. Then, the filter entry / exit status is detected by magnetic switch and pressure switch to lock the power level. S3: Power failure protection: When the slow attenuator suddenly loses power, the two-position three-way vacuum solenoid valve is de-energized and opens to release pressure. At the same time, the spring resets and pushes the piston to drive both filters out of the laser optical path, thereby locking the 100% power level and realizing power failure protection.

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