Optical system of uv laser drilling device

Abstract

The utility model discloses a kind of optical systems of uv laser laser drilling device, it is related to the technical field of semiconductor laser processing.The system includes ultraviolet laser light source unit, facula mode switching unit, Galvano scanning focusing unit, multi-light source alignment unit, real-time optical monitoring unit and focusing processing module, through facula mode adaptive switching (Top-Hat / Gaussian), dynamic focusing compensation, multi-light source alignment and real-time optical monitoring, the problem of poor adaptability, insufficient precision and low yield of existing optical system is solved.This system can realize 10-200μm aperture on ABF film, EMC, wafer processing, and is suitable for high-precision laser drilling process of semiconductor packaging.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser processing technology, specifically to an optical system for a UV laser drilling device, mainly used for ABF film, EMC material and 8-20 inch wafer processing, especially suitable for processing 10-200μm micro-aperture holes, realizing a high-precision optical solution with adaptive spot mode switching, dynamic focus compensation and multi-material alignment. Background Technology

[0002] In the laser drilling process of semiconductor packaging, the optical system is a core component that determines the hole diameter accuracy, hole wall quality (tapering, roundness), and multi-material compatibility. Existing UV laser drilling equipment's optical systems suffer from the following key technical deficiencies: Poor adaptability of beam pattern: Existing equipment mostly uses a single beam pattern, either Top-Hat or Gaussian only, which cannot meet the processing requirements of different apertures. For example, processing a 10μm aperture requires the energy concentration of a Gaussian beam, while processing an aperture of 50-200μm requires the uniform energy distribution of a Top-Hat beam to meet the taper requirements, such as Taper > 80% for bottom holes ≥ 50μm and Taper > 65% for bottom holes > 30μm. The single pattern leads to substandard processing quality for some apertures, such as roundness < 42% for 10μm holes and taper < 90% for 200μm holes.

[0003] Insufficient focusing accuracy compensation: The focusing lens position is mostly fixed and cannot be adjusted in real time according to the thickness of the processed material and the expansion and contraction of the processing area, resulting in the aperture deviation of different positions exceeding the specifications. This is especially prominent when processing large working areas of 500×500mm, where the focusing offset problem in the edge area is more prominent.

[0004] 3. Lack of optical monitoring and feedback: The lack of a real-time optical monitoring unit makes it impossible to simultaneously detect the status of the light spot, the roundness and taper of the hole position during the processing. Offline detection is required after processing. Once the optical parameters deviate, the entire board will be scrapped, and efficiency and losses will increase significantly.

[0005] 4. Poor stability of scanning head accuracy: Galvano scanning heads are prone to angular deviation after long-term operation. The existing system has no real-time correction mechanism, which causes the drilling positioning deviation to gradually increase (exceeding ±10μm). It is necessary to stop the machine for manual correction, which affects the equipment's UPH (number of holes processed per unit time) and makes it impossible to maintain a high-efficiency processing of >500 holes / second.

[0006] Therefore, it is necessary to design an ultraviolet laser drilling optical system with adaptive spot mode switching, dynamic focus compensation, multi-source alignment, and real-time optical monitoring to solve the above-mentioned technical pain points. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies and solve the technical problems existing in the background technology, this utility model proposes an optical system for a UV laser drilling device, including an ultraviolet laser source unit, a spot mode switching unit, a multi-source alignment unit, a real-time optical monitoring unit, a focusing processing module, and a Galvano scanning focusing unit. Each unit is connected in a closed loop through optical paths and electrical signals.

[0008] As a preferred technical solution of this application, the ultraviolet laser source unit uses a laser of the brand name: COHERENT, and a laser energy regulator is provided on the outside of the laser. The left end of the ultraviolet laser source unit is connected to the laser emitter, and the ultraviolet laser source unit has a built-in energy meter and a chiller.

[0009] As a preferred technical solution of this application, the spot mode switching unit consists of a motor drive module, an aperture recognition sensor, a Top-Hat shaping lens, a Gaussian collimating lens, a rotating shaft, and an optical lens. The aperture recognition sensor is installed at the right end of the motor drive module, and a Top-Hat shaping lens and a Gaussian collimating lens are arranged at the right end of the aperture recognition sensor. The Top-Hat shaping lens and the Gaussian collimating lens are connected by a rotating shaft, and an optical lens is installed at the rightmost end of the spot mode switching unit.

[0010] As a preferred technical solution of this application, the multi-light source alignment unit consists of a red / IR / blue light module, a CCD camera, and an image processing module installed sequentially from right to left.

[0011] As a preferred technical solution of this application, the real-time optical monitoring unit consists of an aperture quality inspection camera, a spot monitoring camera, a data processing module, and a data processing display screen. The aperture quality inspection camera is installed at the left end of the spot monitoring camera, the data processing module is set on the outside of the body of the spot monitoring camera, and the data processing display screen is attached to the data processing module.

[0012] As a preferred technical solution of this application, the core component of the Galvano scanning focusing unit is a dual-axis Galvano scanning head, a dynamic focusing lens group is installed at the left end of the dual-axis Galvano scanning head, and a linear scale feedback module is installed and connected at the lower end of the dual-axis Galvano scanning head.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: 1. Enhanced adaptability to multiple scenarios: Through adaptive switching of light spot mode (Top-Hat / Gaussian) and multi-source alignment (red / IR / blue light), it achieves compatible processing of 10-200μm apertures on ABF films, EMC, and wafers without the need to replace optical components, and the switching efficiency is improved by 90%; 2. Significantly optimized machining accuracy: The combination of dynamic focusing compensation and Galvano real-time correction ensures that the hole diameter deviation is <±5μm, the taper qualification rate is >95%, and the roundness is ≥95% throughout the entire working area; 3. Dual improvement in efficiency and yield: Real-time optical monitoring avoids batch defects, with UPH maintained at >650 holes / second; MTBF >200 hours, and equipment stability improved by 30%; 4. Improved ease of operation: The parameter control unit and automatic matching function of the whole machine reduce the time for setting processing parameters for new workpieces from 30 minutes to 5 minutes, thus reducing the skill requirements for operators; 5. Reduced energy consumption and costs: The energy fluctuation of the ultraviolet laser is less than 5%, and combined with dynamic power adjustment, energy consumption is reduced by 15%; the frequency of optical component replacement is reduced, and annual maintenance costs are reduced by 20%. Attached Figure Description

[0014] Figure 1 Schematic diagram of the overall equipment and optical path structure Figure 2 Main view of the overall equipment and optical path structure Figure 3 Schematic diagram of ultraviolet laser source unit structure Figure 4 Schematic diagram of the light spot mode switching unit structure Figure 5 Schematic diagram of multi-source alignment unit structure Figure 6 Schematic diagram of the real-time optical monitoring unit. Figure 7 Schematic diagram of Galvano scanning focusing unit structure In the diagram, the correspondence between component names and drawing numbers is as follows: 1. Ultraviolet laser source unit; 2. Spot mode switching unit; 3. Multi-source alignment unit; 4. Real-time optical monitoring unit; 5. Focusing processing module; 6. Galvano scanning focusing unit; 7. Energy meter; 8. Chiller; 9. Laser emitter; 10. Top-Hat shaping lens; 11. Optical lens; 12. Motor drive module; 13. Aperture recognition sensor; 14. Red / IR / Blue light module; 15. CCD camera; 16. Image processing module; 17. Spot monitoring camera; 18. Aperture quality inspection camera; 19. Data processing module; 20. Dual-axis Galvano scanning head; 21. Dynamic focusing lens group; 22. Linear scale feedback module; 23. Data processing display screen; 24. Rotation axis; 25. Gaussian collimating lens; 26. Laser energy regulator. Detailed Implementation

[0015] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.

[0016] like Figure 1-2 As shown, as a preferred embodiment, this utility model discloses an optical system for a UV laser drilling device, which relates to the field of semiconductor laser processing technology. It includes an ultraviolet laser source unit 1, a spot mode switching unit 2, a multi-source alignment unit 3, a real-time optical monitoring unit 4, a focusing processing module 5, and a Galvano scanning focusing unit 6. Each unit is connected in a closed loop through optical paths and electrical signals.

[0017] The ultraviolet laser source unit 1 primarily outputs a stable laser beam. The beam automatically switches between two beam modes—flat-top and Gaussian—through the beam mode switching unit 2. The switched beam then enters the next core component, the real-time optical monitoring unit 4, which monitors the beam's shape in real time. Subsequently, the light source enters the next component, the multi-source alignment unit 3, to achieve precise beam positioning. After precise positioning, the light source enters the Galvano scanning and focusing unit 6, ensuring that the laser beam's focal point always falls precisely on the workpiece surface to be processed. The focusing and processing module 5, in coordination with the Galvano scanning and focusing unit 6, performs precise and high-quality product processing.

[0018] like Figure 3As shown, in a preferred embodiment, the ultraviolet laser source unit 1 uses a laser from the brand COHERENT. The COHERENT laser is the "energy core" of the laser drilling equipment, and it uses ABF film and EMC. High-precision drilling of semiconductor packaging materials such as materials and wafers provides stable, controllable, and material-adaptive ultraviolet laser energy. The left end of the ultraviolet laser source unit 1 is connected to the laser emitter 9, which is used to emit the laser source emitted by the COHERENT laser. An energy meter 7 and a chiller 8 are installed inside the ultraviolet laser source unit 1. Energy fluctuations may occur during laser emission. The energy meter 7 can monitor the laser output energy in real time. When the laser emits laser light and the energy fluctuation approaches the threshold, it will automatically feed back abnormal information to the laser energy regulator 26. The laser current is compensated by adjusting the laser energy regulator 26. If an error occurs, a shutdown alarm is immediately triggered to avoid scrapping the entire board due to energy abnormality. The chiller 8 installed inside the ultraviolet laser source unit 1 maintains a stable internal temperature of the laser through closed-loop temperature control (accuracy ±0.5℃) to ensure long-term consistency between wavelength and energy output and extend the life of the laser, since the laser generates heat during operation. Temperature changes can cause wavelength drift or energy instability.

[0019] like Figure 4 As shown, in a preferred embodiment, the spot mode switching unit 2 comprises a motor drive module 12, an aperture recognition sensor 13, a Top-Hat shaping lens 10, a Gaussian collimating lens 25, a rotating shaft 24, and an optical lens 11. The aperture recognition sensor 13 is mounted on the right end of the motor drive module 12. The aperture recognition sensor 13 can sense and identify the aperture size. A Top-Hat shaping lens 10 and a Gaussian collimating lens 23 are disposed on the right end of the aperture recognition sensor 13. In the Top-Hat mode (flat-top spot), the spot size can be continuously adjusted within the range of 30-75μm. This mode is suitable for processing medium to large apertures of 50-200μm. In the Gaussian mode (Gaussian spot), the spot size is fixed at 30μm. This mode is specifically designed for micro-apertures of 10-30μm. The Top-Hat shaping lens 10 and the Gaussian collimating lens 25 are... The collimating lens 23 is connected via a rotating shaft 24. Based on the aperture size detected by the aperture recognition sensor 13, the laser beam spot mode (Top-Hat / Gaussian) adjustment is automatically switched. An optical lens 11 is installed at the far right end of the spot mode switching unit 2 for beam propagation.

[0020] like Figure 5As shown, the multi-source alignment unit 3 consists of a red / IR / blue light module 14, a CCD camera 15, and an image processing module 16 installed from right to left. The red / IR / blue light module 14 can switch between red, IR, and blue light modes according to the target imaging requirements of all mainstream materials in semiconductor packaging. This addresses the industry pain point of "different materials → unclear target → inaccurate positioning" caused by the significant differences in surface characteristics and light reflectivity and absorption rates of different processing materials (such as ABF film, EMC, and wafers). A single light source cannot ensure clear imaging of the target (Mark point). A CCD camera 15 is set on the left side of the red / IR / blue light module 14. This component performs algorithmic processing on the acquired images, such as edge detection, center fitting, and distortion correction. It calculates the actual physical coordinates of the target point, compares the actual coordinates with the theoretical design coordinates, and obtains the workpiece placement deviation, including X / Y direction offset, rotation angle, and global expansion and contraction. The deviation data is fed back to the equipment control system to ultimately achieve alignment accuracy.

[0021] like Figure 6 As shown, the real-time optical monitoring unit 4 includes a spot monitoring camera 17 mounted on the left end of the hole quality inspection camera 18 for real-time imaging of the laser beam spot shape. The energy distribution characteristics are analyzed by the data processing module. In Top-Hat mode, the energy uniformity is checked to see if it is ≥90%, and in Gaussian mode, the beam quality factor M² is checked to see if it is ≤1.2. If the spot condition is abnormal, the abnormal condition is simultaneously fed back to the data processing display screen 23, prompting the worker to handle and intervene. A data processing module 19 is set on the outside of the hole quality inspection camera 18. The hole quality inspection camera 18 uses an oblique light source for imaging, immediately capturing the cross-section and surface morphology of the hole after drilling. The data processing module 19 calculates key indicators and compares the real-time monitoring data with preset standards. If deviations occur, an adjustment signal is immediately output to trigger targeted optimization.

[0022] like Figure 7As shown, the core component of the Galvano scanning focusing unit 6 is the dual-axis Galvano scanning head 20. The dual-axis Galvano scanning head 20, under high-speed deflection, drives the laser beam to move rapidly in a two-dimensional plane on the workpiece surface. A dynamic focusing lens group 21 is installed at the left end of the dual-axis Galvano scanning head 20. The dynamic focusing lens group 21 can adjust its focal length in real time according to the thickness changes, surface flatness, or regional expansion and contraction of the workpiece in the overall system settings, ensuring that the focal point of the laser beam always accurately falls on the workpiece surface to be processed. A linear scale feedback module 22 is installed and connected to the lower end of the dual-axis Galvano scanning head 20. The function of the linear scale feedback module 22 is to scan the finished holes punched on the standard calibration plate by the dual-axis Galvano scanning head 20, measuring the deviation between the actual hole position and the theoretical position. When an error occurs, the position of the Galvano scanning focusing unit 6 can be corrected by moving the linear feedback module 22.

[0023] The above embodiments are only used to illustrate the present utility model and are not intended to limit the technical solutions described in the present utility model. Although the present utility model has been described in detail with reference to the above embodiments, the present utility model is not limited to the specific embodiments described above. Therefore, any modifications or equivalent substitutions to the present utility model, and all technical solutions and improvements that do not depart from the spirit and scope of the invention, are covered within the scope of the claims of the present utility model.

Claims

1. An optical system for a UV laser drilling device, characterized in that: It includes an ultraviolet laser source unit (1), a spot mode switching unit (2), a multi-source alignment unit (3), a real-time optical monitoring unit (4), a focusing processing module (5), and a Galvano scanning focusing unit (6). Each unit is connected in a closed loop through optical paths and electrical signals.

2. The optical system of the UV laser drilling device according to claim 1, characterized in that, The ultraviolet laser source unit (1) uses a laser of the brand COHERENT. A laser energy regulator (26) is provided on the outside of the laser. The left end of the ultraviolet laser source unit (1) is connected to a laser emitter (9). An energy meter (7) and a chiller (8) are provided inside the ultraviolet laser source unit (1).

3. The optical system of the UV laser drilling device according to claim 1, characterized in that, The spot mode switching unit (2) consists of a motor drive module (12), an aperture recognition sensor (13), a Top-Hat shaping lens (10), a Gaussian collimating lens (25), a rotating shaft (24), and an optical lens (11). The aperture recognition sensor (13) is installed at the right end of the motor drive module (12). The Top-Hat shaping lens (10) and the Gaussian collimating lens (23) are arranged at the right end of the aperture recognition sensor (13). The Top-Hat shaping lens (10) and the Gaussian collimating lens (23) are connected by a rotating shaft (24). The optical lens (11) is installed at the rightmost end of the spot mode switching unit (2).

4. The optical system of the UV laser drilling device according to claim 1, characterized in that, The multi-source alignment unit (3) is equipped with a red / IR / blue light module (14), a CCD camera (15) and an image processing module (16) from right to left.

5. The optical system of the UV laser drilling device according to claim 1, characterized in that, The real-time optical monitoring unit (4) consists of a hole quality inspection camera (17), a spot monitoring camera (18), a data processing module (19), and a data processing display screen (23). The hole quality inspection camera (17) is installed on the left end of the spot monitoring camera (18), and the data processing module (19) is set on the outside of the body of the spot monitoring camera (18). The data processing display screen (23) is attached to the data processing module (19).

6. The optical system of the UV laser drilling device according to claim 1, characterized in that, The core component of the Galvano scanning focusing unit (6) is a dual-axis Galvano scanning head (20). A dynamic focusing lens group (21) is installed at the left end of the dual-axis Galvano scanning head (20), and a linear scale feedback module (22) is installed and connected at the lower end of the dual-axis Galvano scanning head (20).

Images