LPCVD WSi2 Films Using Tungsten Chlorides and Silane

Abstract

This paper makes a systematic study of blanket and selective low pressure chemical vapor deposition (LPCVD) films from tungsten chlorides, silane, hydrogen, and argon on silicon as well as on patterned oxidized silicon substrates. Experiments were performed by varying the initial gaseous to ratio or the deposition temperature . Initially, yield and CVD‐phase diagrams of the W‐Si‐Cl‐H‐Ar chemical system were drawn, based on thermodynamic simulations. The deposition of pure phase and mixed solid phases involving W, , , and Si was predicted to occur in relation to process parameters. The corresponding films were grown in a cold‐wall reactor and characterized by x‐ray diffraction, scanning electron microscopy, four‐point probe, and Auger electron spectroscopy studies. Good agreement was found between experimentally observed solid phases and thermodynamically simulated results, under the same conditions. The growth rate of films for an value varying between 0.3 and 1.0 at 873 K reaches a maximum at . The Arrhenius plot of films grown between 773 and 1073 K shows a linear increase in growth rate up to 923 K, followed by saturation at high temperatures. Films processed above 823 K have a smooth surface and interface, indicating that the chloride‐based chemistry does not affect the silicon substrate even at high temperatures. Based on the above mentioned studies, a set of process parameters was defined, and selective LPCVD films were deposited on fine‐patterned oxidized silicon.