Sukti Chatterjee, Sr. Member of Technical Staff, Applied Materials Inc.
Shrikant Swaminathan, Mechanical Engineer Manager, Applied Materials Inc.
Miaojun Wang, Process Engineer, Applied Materials Inc.
Fei Wang, Director, Applied Materials Inc.
Lance Scudder, Director, Applied Materials Inc
Pravin K Narwankar, Managing Director, Applied Materials Inc.
X-ray photoelectron spectroscopy (XPS) analyzes the surface chemistry of materials. It is also known as electron spectroscopy for chemical analysis (ESCA) and is commonly used to measure elemental composition/stoichiometry of thin film coatings in different industries. We have applied this technique to develop Atomic Layer Deposition (ALD) AlOx coating (of < 50 nm thick) processes by testing deposited film composition to identify the O/Al ratio.
Our pharmaceutical program customers questioned whether XPS is an appropriate metrology technique to detect process variation in the coating composition. This presentation demonstrates the adequacy of XPS by using Gauge R&R in JMP 17. We designed our testing experiments using measurement systems analysis (MSA) designs platform, and a fast replicate crossed model was used with six sample coupons on two different kinds of substrates (silicon coupons and active pharmaceutical ingredient [API] pellets). Each sample was split into four parts and all 24 (6 X 4) samples were measured independently by two different vendors blindly.
The data distribution was reviewed using a variety of methods: X-bar and R control chart, performed repeatability, reproducibility, part-to-part variation testing, calculated Gauge R&R (P/TV), P/PV, P/T in MSA Gauge R&R platform. Also, the evaluating the measurement process (EMP) platform was used to determine interclass correlation (ICC) and to identify if any interaction exists with either substrate type or vendor. Both MSA platforms confirmed that part variation is significantly higher than precision level, hence XPS is adequate to detect the variation in the process