Stress analysis and characterization of TEOS-based PECVD fabricated SiO2 solid films after thermal annealing

Abstract Stress and wafer warpage of plasma enhanced chemical vapor deposition (PECVD) fabricated SiO 2 solid films are critical factors in high-vacuum semiconductor integrated circuit (IC) manufacturing during annealing. This work investigates the annealing of PECVD-grown SiO 2 solid films (using TEOS precursor, Si(OC 2 H 5 ) 4 ) in a nitrogen (N 2 ) atmosphere. We systematically studied the effects of annealing temperature and time on wafer warpage and explored the underlying change mechanisms using multiple characterization techniques. Results show that wafer warpage of SiO 2 solid films decrease initially and then increase with rising annealing temperature. The optimal condition for minimizing warpage is 550 °C/6 h. To understand microstructural changes, including chemical bond rearrangement and film characteristics, during annealing, we employed patterned wafer geometry, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR), atomic force microscopy, n & k value, weight meter, film thickness and wafer mass tracking. Under optimal annealing, the impurity content in the SiO 2 solid film is reduced while the surface roughness remains unchanged. FTIR, n & k value, film thickness, and wafer mass analyses collectively support a proposed mechanism: hydrogen outgassing via Si–OH bond dissociation. This mechanism explains the observed changes in SiO 2 solid film characteristics. This study provides valuable insights for optimizing stress and wafer warpage of TEOS-based SiO 2 solid films in IC and micro electro-mechanical system fabrication.