Low-temperature Si(100) etching:: facile abstraction of SiH3(a) by thermal hydrogen atoms

Efficient Si(100) etching by thermal-energy H atoms has been achieved. SiH3(a) was prepared by exposure of Si(100) to disilane (Si2H6) at 105 H. Subsequent exposure to H atoms leads to the ejection of the etching product (SiH4(g)) for substrate temperatures T, between 105 and 480 K. Exposure of SiH3(a) on Si(100)-(2 x 1) to D atoms removed SiH3(a) and, provided that the substrate temperature was below 300 K, continued to etch the substrate by generating SiD3(a) and SiD4(g). Above 300 K, etching stopped when preadsorbed SiH3(a) was consumed. These results provide direct evidence for efficient silicon surface etching by thermal hydrogen atoms at low temperatures. We attribute the etching efficiency to increased stability of SiH3(a) realized at low temperatures. This allows its hydrogenation to compete, forming SiH4 which promptly desorbs. (C) 1997 Elsevier Science B.V.