Deposition of WSi_x Films from Preactivated Mixture of WF₆/SiH₄

Abstract

WSi x films were formed on a substrate from thermal chemical vapor deposition (CVD) of WF6 and SiH4. Chemical reactions were initiated upstream of the substrate by a preheater, and chemical reactions are radical chain reactions which produce preactivated cursors that are deposited, causing film growth. Because chemical reactions occur upstream of the substrate, film formation occurred even at temperatures as low as 40° C. Compared with films deposited at the same substrate temperature, without preheating, the Si content increased by 50%, the interfacial concentration of residual fluorine decreased by one order of magnitude, and the sticking probability of the precursors on the substrate was the same. The sticking probability was shown to depend solely on the substrate temperature, even for varying degrees of preheating. Deposition on a low-temperature substrate of the preactivated precursors provides a means to deposit conformal WSi x films with low interfacial concentration of fluorine.

Fermi-level depinning in Mo/Si junctions by insertion of amorphous Si-rich Mo silicide film formed via gas-phase reactions of MoF6 with SiH4

“…For W and WSi n films, the reaction mechanism of SiH 4 and WF 6 source gases is well known. [17][18][19][20][21][22][23][24][25][26][27] In contrast, the reaction mechanism for Mo and MoSi n films using SiH 4 and MoF 6 source gases remains to be fully elucidated. [28][29][30] Accordingly, we investigated the n value of MoSi n film depending on the partial pressure ratio (PR) of SiH 4 to MoF 6 .…”

Low Temperature Chemical Vapor Deposition of Silicon-rich Tungsten Silicide Films from Tungsten Hexafluoride - Disilane Pre-activated Mixtures

“…The value of t b /t s is governed by the competition between diffusion and reaction rates in the trench. The reactivity of the film precursors can be analyzed from step-coverage observations (Shimogaki et al 1991, Saito et al 1994, Jun et al 2004 Saito et al 2006a). 3(c) shows a schematic of the micron-sized trench.…”

“…On the basis of the last two findings, the preheating of gas mixtures at the reactor inlet was proposed to promote chain reaction. This process allows conformal step coverage to be achieved in sub-micron trenches with sufficiently high Si contents for VLSI fabrication (Saito et al 1994). In addition, using this process, reduced fluorine concentrations at the solid-solid interface can be obtained at substrate temperatures as low as 150°C.…”

Kinetic modeling of tungsten silicide chemical vapor deposition from WF6 and Si2H6: Determination of the reaction scheme and the gas-phase reaction rates

“…Based on the last two findings, we developed a process to initiate the reactions by preheating the feed gas mixtures. This process allowed us to achieve conformal deposition in sub-micron trenches with sufficient silicon content for VLSI fabrication processes (Saito et al, 1994). It also decreased the fluorine concentration at the solid-solid interface at relatively low substrate temperatures.…”