A novel method of fabricating ZnO/diamond/Si multilayers for surface acoustic wave (SAW) device applications

• Published in: Thin solid films Vol. 416; no. 1; pp. 190 - 196
• Main Authors: Seo, Soo-Hyung, Shin, Wan-Chul, Park, Jin-Seok
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 02.09.2002; Elsevier Science
• Subjects: Acoustic wave devices, piezoelectric and piezoresistive devices; Applied sciences; Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Diamond; Dielectric, ferroelectric, and piezoelectric devices; Electronics; Exact sciences and technology; Low-dimensional structures (superlattices, quantum well structures, multilayers): structure, and nonelectronic properties; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Multilayers; Physics; Plasma processing and deposition; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Surface roughness; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Multilayers; Diamond; Surface roughness; Plasma processing and deposition; Atomic force microscopy; Scanning electron microscopy; Raman spectra; Inorganic compounds; Transition element compounds; Diamonds; Surface acoustic wave devices; Roughness; Surfaces; Oxides; Surface treatments; Crystal growth from vapors; Chemical etching; Experimental study; Thin films; Zinc oxides; Selective growth; II-VI semiconductors; Nonmetals; Silicon; PECVD; Pretreatment
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/S0040-6090(02)00725-3

A novel process for fabricating ZnO/diamond/Si for a surface acoustic wave device is as follows: to form a trench of 10 μm in depth, the Si wafer is chemically etched by employing the SiO 2 layer as a mask. Selective growth of polycrystalline diamond film is carried out by a microwave plasma CVD using nominal conditions of 700 W microwave power, 40 torr pressure, 0.5% CH 4/H 2 ratio, 630 °C temperature, and −200 V bias enhancement for initial nucleation. After removing the SiO 2 layer, indirect bonding of a Si handle wafer is performed at low temperatures of approximately 90 °C. Finally, the bottom Si wafer is mechano-chemically polished until the surface (backside) of the diamond is exposed. Raman and field emission SEM observations show that a high quality diamond film is selectively grown only on the trenched Si region. It has also been found from the AFM results that the backside surface roughness of the exposed diamond film is measured to be lower than 10 nm.