Study of Birefringence and Stress Distribution of SiO2 Film Optical Waveguide on Silicon Wafer

Abstract

Silica waveguide planar lightwave circuit (PLC) technology is driving the broad applications of various functional components to meet the increasing demands of the industry due to its advanced performance in large-scale wafer mass production. Despite the intense research interests in understanding and relaxing the stress causing the optical birefringence, not much research has been devoted to investigating the stress distribution. In this article, the thermal stress, growth-caused stress, and structural stress are comparably studied. The birefringence distribution of a 6 μm-thick SiO2 film from the center to the edge on a 6-inch silicon wafer was measured to be 0.0006 to 0.0038, leading to an equivalent stress distribution cross the wafer from −170 to −1000 MPa. This implies that the compressive stress of the thick SiO2 film on the wafer was nonuniformly distributed; however, it gradually increased from the center to the edge. Meanwhile, the measured stress of a SiO2 film decreased with the flow rate of the doped GeH4 gas. The algebraic sum of the above three stresses reached excellent agreement with the measurement results in both distribution form and amplitude. In both research and production, the agreeable optical property distributions between the theoretical calculations and experimental measurements are more sustainable to further improving the yields of SiO2 thick film PLC products.

Experimental Study on the Thickness-Dependent Hardness of SiO2 Thin Films Using Nanoindentation

“…Due to its good chemical stability, optical properties, dielectric properties, abrasion resistance and corrosion resistance, silicon dioxide (SiO 2 ) thin films have received intensive attention within the technology and scientific community [1][2][3][4][5][6][7][8][9], and are widely used in micro-electro-mechanical systems, integrated circuits and optical devices [10][11][12][13][14][15]. Tremendous efforts have been devoted to studying the preparation technology and optical properties of the SiO 2 thin films [16][17][18][19], while little attention has been paid to their mechanical properties. In fact, the mechanical properties of SiO 2 thin films can affect their optical and electrical properties, and can also affect the production yield, serving time and reliability of the SiO 2 thin related devices [16][17][18][19][20][21][22].…”

“…Tremendous efforts have been devoted to studying the preparation technology and optical properties of the SiO 2 thin films [16][17][18][19], while little attention has been paid to their mechanical properties. In fact, the mechanical properties of SiO 2 thin films can affect their optical and electrical properties, and can also affect the production yield, serving time and reliability of the SiO 2 thin related devices [16][17][18][19][20][21][22]. Therefore, in order to optimize the design, and improve the performance, service time and reliability of the SiO 2 thin film-related devices, the mechanical properties of SiO 2 thin films should be studied carefully.…”