Characterization of silicon nitride thin films deposited by reactive sputtering and plasma-enhanced CVD at low temperatures

Abstract

Low-temperature deposition has been required for preparing SiNx films of high density, high refractive index, and low hydrogen content for various applications. We examine the characteristics of SiNx films deposited at low temperature by reactive sputtering and plasma-enhanced CVD under different conditions. The results reveal that we can give an outline of the preparation conditions that provide the properties of SiNx films required for various applications. The pretreatment of the Si target improves the properties of the sputter-deposited SiNx films by reducing the amount of oxygen incorporation.

Review—Silicon Nitride and Silicon Nitride-Rich Thin Film Technologies: Trends in Deposition Techniques and Related Applications

“…Additionally, the literature generally refers to crystalline and amorphous silicon nitride with different ratios of silicon to nitrogen as silicon nitride (namely, a-SiN x , or c-SiN x with 0 < x < 1.33), although a few reports described significantly higher N/Si ratio. 25 Table I presents nominal properties for silicon nitride. The data compilation should be considered as a guide by the reader for bulk or crystalline (c-SiN x ), polycrystalline (pc-SiN x ), amorphous nonhydrogenated (a-SiN x ) and hydrogenated (a-SiN x :H) thin films.…”

“…Most common applications for sputtered SiN x films consist primarily of a barrier/passivation coating and etch stop in microelectromechanical systems (MEMS); 74,116 high refractive index material for solar cells, 25 through-Si vias for three-dimensional (3D) semiconductor devices, electroluminescent devices, and display devices; 25,31 and high κ dielectric layer in stacked high-dielectric constant (κ) structures for non-volatile memory (NVM) devices. 75 A unique application is as a host material for Si nanocrystals as active light emitters for uses in PL and optoelectronic devices.…”

“…Alternatively, in another report, the N/Si ratio in SiN x films was controlled by employing RF Magnetron sputtering to produce Si-rich films, and PE-CVD to yield N-rich films. 74 A pertinent report 25 compared the properties of SiN x films grown by RF magnetron sputtering and PE-CVD at low temperature. The resulting findings indicated that sputtering was more appropriate than PE-CVD in yielding higher quality SiN x films with enhanced density, with the lower density in the PE-CVD coatings being attributed to the inclusion of hydrogen (due to the lower processing temperature employed).…”

“…In this context, Takeyama, 25 King, 11,12 and Meng, 13 present valuable historical reviews of silicon nitride PVD, CVD, and ALD deposition techniques.…”

“…In this respect, Tables II and III present details of very recent vapor phase deposition techniques of SiN x thin films, along with a synopsis of intended applications. 15,16,[20][21][22][23][24][25][31][32][33][34][36][37][38] More specifically, Table II summarizes PVD and CVD work, while Table III focuses exclusively on atomic layer deposition ALD.…”