Hydrogen peroxide etching and stability of p-type poly-SiGe films

In this paper, a model is developed for the etching of as-deposited, in-situ, boron-doped, LPCVD poly-SiGe films in hydrogen peroxide. The model is corroborated by etching results for poly-SiGe alloys with Ge content between 55 and 70%. The results indicate that Ge content in the 55 to 65% range is desirable for maintaining high selectivity with respect to poly-Ge sacrificial layers in a peroxide etch while attaining a polycrystalline film structure (at about 425/spl deg/C, 50% Ge content poly-SiGe films are amorphous). The drift in residual stress of poly-SiGe films at room temperature in dry and wet ambients is also reported. Finally, the etching of in-situ, boron-doped, LPCVD poly-Ge films in hydrogen peroxide is studied.