DECOMPOSITION OF SILICON HYDRIDES FOLLOWING DISILANE ADSORPTION ON POROUS SILICON SURFACES

Disilane (Si2H6) is used for silicon chemical vapor deposition (CVD) a nd is a potential precursor for atomic layer epitaxy (ALE) on silicon surfaces. In this study, Fourier transform infrared (FTIR) transmissio n spectroscopy was employed to examine the adsorption and decompositio n of disilane on high surface area Porous silicon surfaces. The FTIR s pectra revealed that disilane dissociatively adsorbs on porous silicon surfaces at 200 K to form a large fraction of SiH3 surface species an d some SiH2 and SiH surface species. The Si-H(x) stretching modes betw een 2125-2156 cm-1, the SiH3 degenerate deformation mode at 862 cm-1 a nd the Si-H2 scissor mode at 907 cm-1 were then employed to monitor th e decomposition of the surface hydride species during thermal annealin g. Between 200-600 K, the SiH3 Species decreased and were depleted fro m the silicon surface. Concurrently, the SiH2 surface species were obs erved to increase between 200-440 K and subsequently to decrease betwe en 440-620 K. Only monohydride species remained on the porous silicon surface at 620 K. Above 640 K, the SiH surface species decreased concu rrently with H-2 desorption. Adsorption studies were also conducted at various isothermal temperatures. These disilane adsorption and decomp osition experiments provide important insights to the surface chemistr y during silicon CVD and ALE processing.