Introduction
As a core component in semiconductor manufacturing, the Showerhead (gas distribution plate) enables uniform gas injection through tens of thousands of micropores on its surface, directly influencing wafer-level film deposition uniformity, etching precision, and plasma distribution stability. With advanced nodes progressing to 3nm and below, micropore machining accuracy requirements have escalated to the sub-micron level, with pore diameter consistency controlled within ±0.5μm. This poses disruptive challenges to traditional machining technologies. This paper systematically analyzes the technical framework of Showerhead micropore machining from dimensions including material properties, processing techniques, technical bottlenecks, and innovation directions.
1. Material Properties and Machining Requirements
1.1 Material Classification and Performance Demands
Showerheads are categorized into metallic and non-metallic types:
Metallic Materials: Primarily aluminum alloy (6061-T6) due to its high thermal conductivity, corrosion resistance, and machinability, widely used in mid-to-low-end processes. High-end applications employ nickel-based alloys or titanium alloys to resist plasma bombardment and high-temperature corrosion.
Non-Metallic Materials: Including chemical vapor-deposited silicon carbide (CVD-SiC), aluminum nitride (AlN), quartz glass, and high-purity ceramics, primarily used in extreme ultraviolet lithography (EUV), atomic layer deposition (ALD), and other critical processes. These materials must meet:
oHigh-temperature resistance: Withstand >600°C reaction chamber temperatures.
oChemical inertness: Resist erosion from corrosive gases like Cl₂ and BCl₃.
oThermal expansion matching: Coefficient of thermal expansion (CTE) close to silicon wafers to prevent high-temperature deformation and seal failure.
1.2 Micropore Design Parameters
Key parameters include:
Pore diameter: 30–100μm (approaching 30μm for advanced nodes).
Pore density: 300–1,200 pores/cm² (~100,000 pores for 12-inch wafers).
Pore shape error: ≤±2μm (controls gas flow consistency).
Gas ejection angle: Precisely controlled to avoid turbulence.
Example: Applied Materials’ ALD Showerhead optimized pore distribution and flow channel design, reducing film thickness deviation between wafer edges and centers from ±3% to ±0.8%, significantly improving yield.
2. Traditional Machining Technologies and Limitations
2.1 Mechanical Drilling and Electrical Discharge Machining (EDM)
Mechanical Drilling: Relies on carbide tools, but tool wear causes diameter deviations up to 5μm and fails to process hard materials like CVD-SiC.
EDM: Suitable for conductive metals but suffers from:
oHeat-affected zone (HAZ): Recast layers on pore walls require post-processing acid washing.
oLow efficiency: Requires >10 tool changes and >20 hours to machine a single 12-inch Showerhead.
2.2 Chemical Etching and Photolithography Masking
Chemical etching defines pore arrays via masks but has drawbacks:
Isotropic corrosion: Results in tapered pore walls, affecting gas ejection directionality.
Mask resolution limits: Photoresist cannot achieve <30μm pore diameters reliably.
3. Innovative Machining Breakthroughs
3.1 Femtosecond Laser Cold Machining
Femtosecond lasers (pulse width <10⁻¹⁵ s) enable "cold machining" with ultrashort pulses, offering:
No HAZ: HAZ width ≤0.2μm, avoiding material microstructure damage.
High precision: Pore diameter deviation ≤±1μm, wall roughness Ra <0.2μm.
Material versatility: Processes hard non-metals like CVD-SiC and AlN.
3.2 Hybrid Machining Process
To overcome single-technology limitations, the industry adopts "laser + grinding" synergy:
1.Laser roughing: Femtosecond lasers rapidly form micropore arrays.
2.Diamond grinding: Micron-scale diamond tools polish pore walls to eliminate laser-induced taper and burrs.
Application: Anhui Boxin Micro Semiconductor achieved mass production of 12-inch Showerheads with pore wall perpendicularity of 90°±0.5°, meeting 5nm process demands.
3.3 Atomic Layer Deposition (ALD) Pore Correction
ALD enables nanoscale coating deposition for pore size adjustment:
Principle: Each 100-cycle (≈10nm) SiO₂ deposition reduces pore diameter by 0.2μm.
Advantage: Correction precision ±0.05μm, superior to traditional chemical vapor deposition (CVD).
4. Technical Challenges and Future Trends
4.1 Current Challenges
Cost pressure: Femtosecond laser systems cost >$5M, with machining costs 3× higher than EDM.
Throughput bottleneck: Single laser units produce only 5–10 12-inch Showerheads/day.
Material defect control: Non-metallic machining risks microcracks, requiring ultrasonic testing and X-ray computed tomography (X-CT) for non-destructive inspection.
4.2 Future Trends
Spatial ALD: Multi-precursor parallel injection to boost deposition rates to 1μm/min, reducing costs.
AI-driven simulation: ANSYS Fluent + machine learning to cut gas flow channel design cycles by >30%.
Domestic substitution acceleration: Chinese firms like Weiss Precision Tools and Dunyuan Polytech have localized PCD microdrills and femtosecond lasers, raising supply chain localization from 15% to 40%.
Conclusion
Showerhead micropore machining epitomizes "small holes, big technology" in semiconductor manufacturing, with precision directly dictating advanced node yield and cost. Breakthroughs in femtosecond lasers, hybrid processes, and ALD correction are addressing sub-micron challenges. Future advancements in materials science, smart manufacturing, and AI will drive Showerhead machining toward higher precision, lower costs, and greater intelligence, underpinning sustained semiconductor innovation.
AMTD provides high-precision Showerhead (gas distribution plate) services for core semiconductor equipment components, including Showerheads, Face Plates, Blocker Plates, Top Plates, Shields, Liners, Pumping Rings, and Edge Rings. These products are widely used in semiconductor and display panel industries, delivering exceptional performance and high market recognition.
Content Sources
1.Weiss Precision Tools, Application of Microdrills in Semiconductor Critical Component Industries.
2.Tokyo Electron (TEL), Technical White Paper: ALD in Showerhead Manufacturing.
Lam Research, Semiconductor Equipment Core Component Machining Technologies.
