Inner Wall Shotpeening for Ultra-Pure Gas Delivery Tubes in the Semiconductor Industry
Engineered a closed-loop, non-metallic micro-blasting unit for 316L semiconductor tubes. The system delivers uniform Ra 0.8–1.2 µm pre-EP roughness with zero embedded particles, boosting EP yield from 89% to 98.5% and securing qualified supplier status at multiple advanced-node fabs.
A manufacturer of ultra-pure gas delivery systems in Wuxi supplies 316L Electropolished (EP) tubes (10–30 mm in diameter) to semiconductor fabs nationwide. Prior to electropolishing, the inner walls must be uniformly roughened to an Ra of 0.8–1.2 µm to ensure the subsequent EP process achieves the required chromium enrichment and surface smoothness. While mechanical drawing marks and residual oxides must be completely removed, any embedded metallic particles are strictly unacceptable, as they would cause particulate contamination in downstream fab gas pipelines.
Solution
DISA provided a closed-loop micro-blasting unit utilizing exclusively non-metallic ceramic beads (ZrO₂/SiO₂ composite, 50–90 µm). The blasting lance features a flexible shaft with a 1.5 mm outer diameter, coated in PEEK to prevent iron contamination, and is equipped with a single 0.5 mm sapphire nozzle. Working pressure is precisely regulated at 0.12 MPa via a digital pressure controller with an accuracy of ±0.3%. The entire abrasive circuit is dedicated solely to 316L stainless steel; a physically isolated, independent circuit is used for Alloy 627 tubes, completely eliminating any risk of cross-alloy transfer.
Inline Metrology & Cleaning
Post-blasting, each tube passes through an inline laser scatter instrument that maps the Ra profile at six axial positions. The tubes then undergo a four-stage ultrasonic cleaning process using 18 MΩ DI water, followed by nitrogen purging and hot-air drying. This ensures the inner bore is entirely free of loose abrasives or particulates before entering the EP line. The system logs all measurement data and links it to the tube’s heat number, establishing a comprehensive digital traceability record for fab compliance.
Results
The EP yield rate (the percentage of tubes meeting final Cr/Fe ratio and roughness specifications) surged from 89% to 98.5%, while the rework rate dropped by 70%. Within a single quarter, the tube manufacturer achieved qualified supplier status for gas systems at two 28 nm fabs and one 14 nm fab. The digital quality records were accepted directly by all three fab clients without requiring any additional documentation.
