Optimize Laser Drilling Parameters for Metallization Wrap Through Cells to Minimize Defects

Overview of Technical Issues:

During laser drilling of metallization wrap-through cells, the laser beam creates harmful thermal effects by excessively heating the silicon substrate, causing microcracks, melting, and recast layer formation that degrade electrical performance, while simultaneously providing insufficient ablation of the dielectric layer, leaving residues and irregular hole geometries that prevent reliable metallization contact; the goal is to optimize drilling parameters to eliminate these defects and achieve clean, precise through-holes for high-efficiency cell production.

Problem Direction 1 :

ImproveDielectric layer ablation completeness
VS
ConstraintSubstrate thermal damage resistance

Inspiration 1 : Cross-domain reference

Application Principle: #2 Taking out (Extraction)

Cross-domain Case Inspiration

This patent improves catalyst recovery (reducing loss of substance) while preventing rubber contamination (avoiding object-affected harmful factors) by using chelating agents to selectively [extract] unwanted components from the solution. This mirrors the current need to achieve complete dielectric removal while [extracting] harmful thermal effects before they damage the substrate.
Process for recovery of residual hydrogenation catalyst from hydrogenated nitrile rubber solution
Innovative Solution View detail

Cryogenic liquid film thermal extraction for selective dielectric ablation

Extract thermal energy before substrate damage
How to solve :
  • Apply a flowing liquid nitrogen film (77 K, 0.3–0.5 mm thickness) on silicon surface during laser drilling
  • dielectric ablates at 10 J/cm² while substrate stays below 400 K damage threshold through continuous cryogenic heat extraction
  • Use precision nozzle array (0.2 mm orifice, 2 bar pressure) to deliver laminar LN₂ flow at 50 ml/min per hole, synchronized with laser pulse timing to maintain film stability during 20–50 ns pulse trains
  • Install infrared pyrometer (response time <1 μs) at 45° angle to monitor substrate temperature in real-time
  • abort drilling if temperature exceeds 380 K, ensuring zero microcrack formation while achieving complete dielectric removal verified by energy-dispersive X-ray spectroscopy (EDS) showing <0.5% residual dielectric content
Expected Effect : Substrate temperature <380 K; dielectric removal >99.5%; zero microcracks; recast layer <0.1 μm vs 2–5 μm in conventional thermal drilling
Risk Control :
  • LN₂ film uniformity fluctuation under high-speed drilling
  • thermal shock risk if cooling rate exceeds 10⁶ K/s
  • condensation interference with laser beam transmission

Inspiration 2 : Technology in this field

Search: Ultrashort pulse laser ablation, Selective dielectric removal, Substrate damage prevention, Ablation threshold control, Melt-free laser processing
Existing SolutionView detail

Dual-Laser Sequential Processing with Spatially Displaced Beam Configuration

Use spatially displaced dual-laser system where dielectric ablation occurs in controlled thermal environment
How to solve :
  • Deploy first UV laser (355 nm Nd:YAG) with narrow focused beam at 10-15 J/cm² fluence for dielectric layer ablation, followed by spatially offset second laser (532 nm, 1-5 J/cm²) that locally remelts and anneals the silicon substrate surface to heal crystal defects without bulk melting
  • Configure scan speed ≤150 kHz pulse frequency so second laser pulse spatially falls into thermal-affected zone of first pulse, enabling controlled recrystallization
  • Implement maximum 150 kHz repetition rate with pulse-to-pulse spatial overlap optimized to maintain substrate temperature below melting threshold (1414°C) while achieving complete passivation layer removal at 2-20 J/cm² range
Expected Effect : Complete dielectric removal at 10 J/cm²; substrate microcrack elimination; contact resistance <0.5Ω
Risk Control :
  • Precise spatial and temporal synchronization between dual lasers
  • thermal accumulation control at high repetition rates
  • process window sensitivity to dielectric thickness variation

Problem Direction 2 :

ImproveHole geometry precision
VS
ConstraintSubstrate thermal damage resistance

Inspiration 1 : Cross-domain reference

Application Principle: #3 Local quality

Cross-domain Case Inspiration

This patent improves thermal processing precision by creating [non-uniform temporal thermal profiles] that enable high-temperature film processing while preventing substrate damage, directly paralleling the current need to improve manufacturing precision while avoiding harmful substrate effects through [localized quality] control of energy distribution.
Apparatus for providing transient thermal profile processing on a moving substrate
Innovative Solution View detail

Radially-graded beam intensity profiling for selective layer ablation

Radial beam shaping creates selective ablation zones
How to solve :
  • Design radially-graded beam intensity profile using diffractive optical elements — central zone 12–15 J/cm² for dielectric, outer zone <3 J/cm² at silicon interface
  • Configure beam shaper with flat-top core diameter matching dielectric thickness (0.5–0.8 mm) and Gaussian taper edge (50 μm transition width) to minimize substrate exposure
  • Implement real-time beam profiling feedback using CCD camera monitoring — adjust shaper alignment within ±2 μm to maintain intensity distribution, ensuring central zone ablates dielectric completely while peripheral zone stays below 4 J/cm² silicon damage threshold
Expected Effect : Hole circularity ±5 μm; microcrack density <0.1/mm²; dielectric residue <2%
Risk Control :
  • beam shaper alignment drift during production
  • intensity profile distortion from thermal lensing
  • transition zone width control precision

Inspiration 2 : Technology in this field

Search: Ultrashort pulse laser drilling, Laser energy density control, Substrate cooling technique, Multi-stage laser irradiation, Dry etching post-processing
Existing SolutionView detail

Multi-Burst Laser Drilling with Sequential Energy Modulation for Metallization Wrap-Through Cells

Apply multi-burst drilling strategy where substrate receives multiple low-energy laser exposures with controlled cooling intervals between bursts to achieve complete dielectric removal without substrate damage
How to solve :
  • Implement two-stage burst drilling: first burst uses UV nanosecond laser (wavelength 355nm, pulse width 10-200fs, energy 0.01-1mJ/pulse, repetition rate 1-2kHz) at 3-5 J/cm² to penetrate dielectric layer and create initial through-hole with minimal thermal load
  • allow cooling period of 50-100ms to dissipate heat and stabilize hole entrance
  • second burst applies slightly higher energy 5-8 J/cm² to widen exit and remove residual dielectric while substrate remains below melting threshold
  • adjust silicon substrate surface roughness to Ra 0.05-1μm via plasma etching or photolithography before drilling to promote irregular laser reflection and uniform energy absorption, preventing localized overheating and spattering
  • apply laminar nitrogen gas flow (2-5 m/s) perpendicular to drilling direction to remove debris and plasma without interfering with subsequent holes
  • use galvanometric scanner with movement angles 90-270° relative to gas flow to ensure debris clearance
Expected Effect : Through-hole depth 200-500μm; hole diameter 40-70μm with circularity >95%; recast layer <5μm; microcrack elimination; dielectric residue <2%; processing time 5-9s per 156mm substrate
Risk Control :
  • Burst timing synchronization accuracy
  • surface roughness uniformity across substrate
  • debris management in high-density hole arrays

Problem Direction 3 :

ImproveDielectric layer ablation completeness
VS
ConstraintPulse duration

Inspiration 1 : Cross-domain reference

Application Principle: #19 Periodic action

Cross-domain Case Inspiration

This patent improves material removal completeness (loss of substance) by using [pulsed aspiration cycles] that adapt to clog detection, while preventing excessive duration through dynamic flow monitoring. It demonstrates how [periodic action] with feedback control resolves the contradiction between thorough material removal and process duration constraints, directly paralleling the ablation challenge of complete dielectric removal within nanosecond pulse duration limits.
Aspiration thrombectomy system and methods for thrombus removal with aspiration catheter
Innovative Solution View detail

Burst-mode nanosecond laser drilling with adaptive thermal relaxation intervals

Replace single pulses with burst trains of nanosecond pulses separated by thermal relaxation intervals
How to solve :
  • Deploy burst-mode laser system delivering 5–10 nanosecond pulses per burst at 10–50 MHz intra-burst frequency, each pulse 8–15 ns duration at 1064 nm wavelength
  • Set inter-burst interval to 50–200 μs based on real-time thermal monitoring via infrared pyrometry, allowing substrate cooling below 400°C between bursts while maintaining dielectric ablation momentum
  • Control cumulative fluence at 10–12 J/cm² distributed across burst train, with individual pulse fluence 1.5–2.5 J/cm² to stay below silicon single-pulse damage threshold of 3 J/cm²
Expected Effect : Complete dielectric removal without residues; substrate microcrack density <0.1/mm²; thermal penetration depth <2 μm; hole circularity >0.95; processing speed 500–800 holes/min
Risk Control :
  • intra-burst timing synchronization drift
  • thermal accumulation from insufficient cooling intervals
  • pulse energy stability variation exceeding ±5%

Inspiration 2 : Technology in this field

Search: Nanosecond pre-pulse ablation, Ultrashort pulse ablation, Dual-beam processing, Thermal diffusion control, Post-ablation annealing
Existing SolutionView detail

Nanosecond Pre-Pulse Enhanced Ablation with Picosecond Main Pulse for Selective Dielectric Removal

A nanosecond pre-pulse strategy using dual-beam temporal separation to achieve complete dielectric ablation without substrate damage
How to solve :
  • Apply nanosecond pre-pulse (5-20 ns, λ=532 nm or 1064 nm) at sub-threshold fluence 0.3-0.5 J/cm² to thermally excite dielectric layer and generate seed carriers, followed by picosecond main pulse (10-50 ps, λ=1030-1064 nm) at 0.8-1.5 J/cm² with temporal separation of 50-500 ns
  • The pre-pulse elevates dielectric temperature to 400-600°C without melting silicon (Tm=1414°C), reducing ablation threshold by 40-60% for main pulse while maintaining substrate below damage threshold
  • Optimize inter-pulse delay using pump-probe imaging to synchronize main pulse arrival with peak carrier density in dielectric, ensuring complete SiNx/SiO2 removal with <5 nm residue while limiting silicon heat-affected zone to <200 nm depth
Expected Effect : Ablation threshold reduction 40-60%; substrate damage eliminated; processing window broadened 3-5×
Risk Control :
  • Temporal synchronization stability between dual pulses
  • optical alignment precision for beam overlap
  • cost increase from dual-laser system

Problem Direction 4 :

ImproveHole geometry precision
VS
ConstraintProcess parameter optimization complexity

Inspiration 1 : Cross-domain reference

Application Principle: #6 Universality (Multi-functionality)

Cross-domain Case Inspiration

This patent improves manufacturing precision (precise fuel particle placement and geometry control) while avoiding device complexity deterioration by using additive manufacturing as a [universal] platform where one process definition controls multiple quality outcomes (composition, distribution, geometry), eliminating separate optimization steps for each parameter—directly matching the current need to achieve precise hole geometry while simplifying multi-parameter laser optimization.
Nuclear fuel pebble and method of manufacturing the same
Innovative Solution View detail

Wavelength-selective laser drilling with integrated process control platform

Single wavelength choice controls multiple outcomes simultaneously
How to solve :
  • Select UV laser wavelength (355 nm) that inherently provides high dielectric absorption (>80%) and low silicon absorption (<15%), eliminating separate optimization of energy-material interaction across multiple parameters
  • Implement integrated control platform with pre-calibrated lookup tables mapping dielectric thickness (50–200 μm) to pulse count and energy density, reducing optimization variables from 6 to 2 (pulse count and spot size)
  • Install real-time optical emission spectroscopy to detect dielectric removal completion by monitoring silicon plasma signature, triggering automatic process termination within ±2 pulses to prevent over-drilling
Expected Effect : Parameter optimization reduced from 6-variable to 2-variable space; setup time <30 min; hole diameter tolerance ±5 μm; zero dielectric residue rate >99.5%; substrate damage incidence <0.1%
Risk Control :
  • UV laser source cost and availability
  • lookup table accuracy across dielectric composition variations
  • optical monitoring system calibration drift

Inspiration 2 : Technology in this field

Search: Ultrafast laser drilling, Automated parameter optimization, Tool path algorithm, Real-time process control, Process gas control
Existing SolutionView detail

Defocused Gaussian Beam Drilling with Controlled Ablation Threshold Method

Position the laser focal point at a controlled distance above or below the workpiece surface to achieve clean holes with reduced parameter sensitivity
How to solve :
  • Set focal point offset between 50-200 μm above/below the silicon surface, using preferred range of 50-150 μm to create enlarged spot size at workpiece
  • Adjust spot size at surface to 1.5-2.5 times the desired exit hole diameter, ensuring the ablation threshold intersects the Gaussian beam profile below the 1/e² diameter level
  • Optimize pulse energy so ablation threshold removes dielectric layer completely while keeping substrate exposure below silicon damage threshold, achieving exit diameters smaller than beam 1/e² diameter through threshold-controlled ablation
Expected Effect : Parameter sensitivity reduced by 60%; hole diameter consistency ±2 μm; smooth sidewalls with controlled taper
Risk Control :
  • Focal position calibration accuracy
  • ablation threshold variation across material layers
  • beam profile stability during production

Problem Direction 5 :

ImproveLaser energy density
VS
ConstraintMust not deteriorate

Inspiration 1 : Cross-domain reference

Application Principle: #1 Segmentation

Cross-domain Case Inspiration

This patent improves use of energy by moving object (achieving high energy density for processing) while preventing deterioration of system reliability (avoiding damage to sensitive components). It applies Segmentation by dividing the laser delivery system into two spatial zones with different functions—one for energy concentration and one for protective constraint—directly paralleling the current need to segment laser energy spatially for selective dielectric ablation while protecting the substrate.
Laser processing head and application thereof, and laser processing system and method
Innovative Solution View detail

Dual-zone coaxial beam shaping for selective layer ablation

Coaxial beam shaper creates high-energy core and low-energy annulus for layer-selective ablation
How to solve :
  • Install a diffractive optical element (DOE) to split the laser beam into a high-intensity core (12–15 J/cm², diameter matching dielectric thickness 80–120 µm) and a low-intensity annular guard zone (2–4 J/cm², below Si damage threshold of 5 J/cm²)
  • Use real-time optical coherence tomography (OCT) monitoring at 20 kHz sampling rate to detect dielectric-silicon interface and trigger automatic beam defocusing by +50 µm when residual dielectric <5 µm, reducing core intensity to 6 J/cm²
  • Apply burst mode pulsing with 5-pulse trains at 500 kHz intra-burst frequency, 10 µs inter-burst delay for thermal relaxation, maintaining substrate temperature <400°C while achieving complete dielectric removal
Expected Effect : Dielectric ablation completeness >99.5%; substrate microcrack density <0.1/mm²; hole circularity >0.95; throughput +40% vs single-parameter tuning
Risk Control :
  • DOE alignment precision ±2 µm required
  • OCT signal interpretation accuracy in multi-layer stack
  • thermal accumulation at high repetition rates

Inspiration 2 : Technology in this field

Search: Selective laser ablation threshold, High energy density laser processing, Silicon damage threshold control, Ultrashort pulse laser ablation, Dielectric layer removal process
Existing SolutionView detail

Dual-Wavelength Sequential Laser Ablation with Ultrashort Pulse Pre-Treatment

Use ultrashort laser pulses to achieve selective dielectric ablation through non-thermal mechanisms
How to solve :
  • Apply femtosecond/picosecond laser pulses (150 fs to 10 ps) at 800 nm wavelength with energy density 10-15 J/cm² for initial dielectric layer ablation, exploiting ultrafast expansion of non-thermally decomposed thin silicon layer via electron-hole plasma generation
  • the silicon damage threshold at 800 nm is approximately 1.2 J/cm² for thermal effects but selective damage-free ablation occurs between 100% dielectric removal and substrate damage threshold through non-thermal mechanisms
  • Follow with nanosecond pulse (10-15 ns) at 355 nm or 532 nm wavelength at reduced energy density 2-5 J/cm² for residue removal and localized substrate surface remelting to heal crystal defects without bulk damage
  • pulse overlap control maintains 40-50 μm spacing between pulses at scanning speeds 50-100 mm/s with repetition rates 150-200 kHz
  • implement real-time optical coherence tomography monitoring to detect dielectric layer removal completion and terminate ablation before substrate damage threshold, ensuring energy density remains within the processing window where dielectric ablation is complete but silicon substrate temperature stays below 1412 K melting point
Expected Effect : Complete dielectric ablation at 10-15 J/cm²; silicon substrate damage <0.5×10⁻³ cm⁻¹ absorption change; hole diameter precision ±5 μm
Risk Control :
  • Ultrashort pulse laser system cost and complexity
  • precise temporal and spatial pulse overlap control
  • real-time monitoring system integration and response time

Problem Direction 6 :

ImprovePulse duration
VS
ConstraintMust not deteriorate

Inspiration 1 : Cross-domain reference

Application Principle: #19 Periodic action

Cross-domain Case Inspiration

This patent improves energy delivery efficiency to target tissue while preventing fiber burnback and thermal damage by using [periodic pulse sequences with varying parameters]. It demonstrates how [temporal pulse modulation] can optimize energy deposition per action cycle while controlling unwanted thermal effects, directly paralleling the current need to deliver sufficient ablation energy within nanosecond constraints without substrate thermal diffusion.
Optimization of BPH treatment using holep (holium laser enucleation of prostrate)
Innovative Solution View detail

Burst-mode nanosecond pulse train with adaptive inter-pulse cooling intervals for dielectric ablation

Replace single pulses with burst trains of nanosecond pulses separated by thermal relaxation intervals
How to solve :
  • Deploy burst-mode laser architecture delivering 5–10 nanosecond pulses per burst, each pulse 8–15 ns duration at 2–3 J/cm² fluence, cumulative energy 10–15 J/cm² per burst
  • Set inter-pulse delay at 50–200 ns calculated from thermal diffusion length √(4αt) where α=8.8×10⁻⁵ m²/s for silicon, allowing substrate cooling between pulses while dielectric remains ablating
  • Implement real-time thermal monitoring via integrated pyrometry (response time <10 ns) to dynamically adjust burst repetition rate from 10–100 kHz, maintaining substrate temperature below 900°C damage threshold
Expected Effect : Complete dielectric removal with zero residue; substrate microcrack density <0.1/mm²; thermal penetration depth reduced 70% vs single-pulse; hole circularity >0.95
Risk Control :
  • inter-pulse timing synchronization jitter exceeding 5 ns
  • pyrometer calibration drift under high-flux conditions
  • burst energy stability variation beyond ±3%

Inspiration 2 : Technology in this field

Search: Ultrashort pulse laser ablation, Nanosecond pulse processing, Thermal diffusion control, Pulse energy optimization, Dielectric layer removal
Existing SolutionView detail

Nanosecond Pre-Pulse Enhanced Picosecond Ablation for Dielectric Layer Removal

Apply controlled nanosecond pre-heating to reduce ablation threshold without substrate damage
How to solve :
  • Implement dual-pulse laser system: first pulse at 532 nm wavelength, 10-20 ns duration, fluence 0.3-0.5 kJ/m² to pre-heat substrate surface without melting (temperature rise 200-400°C)
  • second pulse at 355 nm or 1030 nm, 10 ps duration, fluence 0.8-1.2 kJ/m² for ablation, delivered 50-100 ns after pre-pulse to exploit reduced threshold
  • Optimize inter-pulse delay through thermal modeling: delay must exceed electron-phonon coupling time (1-5 ps) but remain within thermal confinement window (<500 ns) to maintain localized heating
  • Control spot overlap at 30-50% with pulse repetition rate 10-50 kHz, scanning speed 100-500 mm/s to ensure complete dielectric removal while preventing heat accumulation
Expected Effect : Ablation threshold reduction 40-60%; substrate amorphization eliminated; hole edge roughness <50 nm
Risk Control :
  • Inter-pulse timing precision and synchronization
  • wavelength-dependent absorption variations in multi-layer stacks
  • thermal accumulation at high repetition rates
Patsnap Eureka Solution

If you want to get more technical solutions, you can try Eureka.