Thermal decomposition kinetics of polysilanes: Disilane, trisilane, and tetrasilane

Abstract

The decomposition kinetics of disilane with added butadiene, trisilane both neat and with added butadiene, trimethylsilane or H,, and normal and iso-tetrasilane both neat and in the presence of added butadiene are reported. Arrhenius parameters of the primary dissociation reactions are determined: A-factors suggest that polysilane decompositions (1) have similar intrinsic activation entropies (AS* = 6.2 ? 5 e.u.1 and (2) have activation energies which increase with increasing reaction endothermicities. Relative trapping efficiencies of SiH,, Si,H6, SiBH8, C4Hs, Me,SiH, and Hz toward SiHz and SiH,SiH are also determined. Other results include the heat of formation of silylsilylene, AH; (SiH,SiH) = 75.3 Kcal/mol, and the activation energy for 1,l-H, elimination from disilane (EH2 = 57.8 kcal/mol).

Thermochemistry and Kinetics of Silicon Hydride Cluster Formation during Thermal Decomposition of Silane

“…[1][2][3][4][5][6][7] There is also a substantial body of work on the kinetics of gas-phase reactions of small silicon hydrides. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] On the basis of this body of research, models of thermal CVD of silicon from silane can now predict film growth rates and precursor utilization with reasonable accuracy and reliability, at least under conditions where particle formation is negligible. However, understanding of the processes that lead to gas-phase particle nucleation is still quite limited, and models for nucleation and growth of particles in this system do not have the level of predictive capability that has been achieved in modeling film growth rates and gas-phase chemical composition.…”

Kinetics of Substituted Silylene Addition and Elimination in Silicon Nanocluster Growth Captured by Group Additivity

“…For the elimination reaction, classic Arrhenius behavior is observed, and the activation energies increase with increasing strength of the breaking SiÀH bond and decrease with the strength of the forming SiÀH bond. [22] The temperature dependence of the rate coefficient for the unimolecular decomposition reaction of disilane to form silylene and monosilane is linear over all temperatures. The rate coefficients for elimination that we calculate for Reaction 1 are within a factor of 10 over the entire temperature range compared to diverse experimental data, despite mild pressure dependencies present in the experiments, and the largest deviations are present at low temperatures ( Figure 2).…”

“…To a lesser extent, the kinetics of substituted silylene addition to form larger hydrides have been explored. [22,23] Katzer, Sax et al [24][25][26] have performed extensive theoretical investigations on the thermochemistry of silicon hydrides and the effects of anharmonic vibrations on thermochemistry. Interest in the substituted silylene addition and elimination reactions of silicon hydrides extends beyond Si-H systems to hybrid silicones, [27] chlorosilicon hydrides, [28][29][30][31] Si-C hydrides, [32][33][34][35][36] and Si-Ge heterostructures.…”

IR laser-induced co-decomposition of trisilane and thiirane for deposition of polycarbosilthiane films

“…Trisilane thermolysis proceeds at temperatures higher than 610 K [37] and it is initiated by silylene (:SiH 2 ) and silylsilylene (H 3 Si(H)Si:) eliminations which occur with activation barrier (ca. 210-220 kJ/mole [18]) lower than needed for homolysis of the Si-H and Si-Si bonds [38]. Further steps are insertions of the silylenes into Si-H bonds of trisilane and thermolytic products and dehydrogenation, both yielding hydrogenated silicon.…”

“…trisilane [18]) decomposition paths and suitability of higher silanes (e.g. [19][20][21]) to act as precursors to amorphous hydrogenated silicon films.…”