Picosecond Laser Direct Ablation for High-Throughput IC Trace Formation
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Solution Overview
Problem
Current methods for laser direct ablation in IC substrate manufacturing lack productive and cost-effective techniques suitable for high-volume production, particularly in achieving controlled signal propagation characteristics for embedded electrical traces.
Innovation Solution
The use of a short temporal pulsewidth laser with a high pulse repetition frequency for efficient and controlled material removal, allowing for high throughput and precise formation of electrically conductive traces by selecting optimal pulse parameters such as dose fluence, temporal pulsewidth, and pulse repetition frequency to maintain consistent laser spot overlap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If UV YAG laser direct writing method is used to form embedded traces, then flexibility and rapid design adaptation are improved, but throughput decreases significantly when pattern density increases
Solution Approach 1:
The patent segments the laser processing into multiple passes: a first pass using excimer laser for high-speed bulk material removal, followed by a second pass using UV YAG laser for precise trace formation. This segmentation allows each laser type to operate in its optimal performance regime, resolving the contradiction between throughput and precision.
Solution Approach 2:
The patent implements continuous laser scanning with high pulse repetition frequencies (100-500 kHz) to maintain continuous material removal action, eliminating idle time between pulses and maximizing throughput while maintaining trace precision through controlled pulse overlap.
2Productivity
If excimer laser ablation is used for high throughput processing, then productivity is improved, but resolution and depth control deteriorate compared to UV YAG laser
Solution Approach 1:
The patent divides the processing task into two segments: excimer laser performs the first segment of bulk dielectric removal at high speed, then UV YAG laser performs the second segment of precise trace formation. This segmentation allows excimer to maximize throughput while UV YAG ensures precision, resolving the contradiction.
Solution Approach 2:
The excimer laser performs partial action by removing only the bulk dielectric material to a controlled depth, leaving the final trace formation to the UV YAG laser. This partial action allows excimer to operate at maximum throughput without compromising final precision.
3Productivity
If pulse repetition frequency is increased for high throughput, then productivity is improved, but maintaining sufficient pulse overlap becomes difficult
Solution Approach 1:
The patent dynamically adjusts the relationship between pulse repetition frequency and scanning speed to maintain optimal pulse overlap. By coordinating these parameters, the system achieves high throughput while ensuring consistent material removal through maintained pulse overlap along the trace path.
Solution Approach 2:
The system uses feedback control to monitor and adjust pulse repetition frequency and scanning speed parameters, ensuring that pulse overlap remains within optimal ranges even at high throughput conditions. This feedback mechanism maintains manufacturing precision while maximizing productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables high-speed, productive, and cost-effective processing of dielectric materials, forming precise electrically conductive traces with controlled signal propagation characteristics, improving manufacturing efficiency and reducing material costs.
Implementation Method 1
laser direct ablation (LDA)... forming signal traces having widths that are 10 μm or less... UV YAG laser... excimer laser ablation... short temporal pulsewidth laser with a high pulse repetition frequency for effective LDA processing
Implementation Method 2
generating, using a laser source, a laser beam including the series of laser pulses... providing relative motion between the workpiece and the laser beam... selected velocity
Data Source
AI summary
Laser direct ablation (LDA) produces patterns cut into a dielectric layer for the formation of electrically conductive traces with controlled signal propagation characteristics. LDA processing includes selecting a dose fluence for removing a desired depth of material along a scribe line on a surface of a workpiece, selecting a temporal pulsewidth for each laser pulse in a series of laser pulses, and selecting a pulse repetition frequency for the series of laser pulse. The pulse repetition frequency is based at least in part on the selected temporal pulsewidth to maintain the selected dose fluence along the scribe line. The selected pulse repetition frequency provides a predetermined minimum overlap of laser spots along the scribe line. The LDA process further includes generating a laser beam including the series of laser pulses according to the selected dose fluence, temporal pulsewidth, and pulse repetition frequency.