Journal of Crystal Growth, Vol.277, No.1-4, 104-113, 2005
Susceptor honing and contact stress in Si epitaxy
Silicon epiwafers are grown in a RF-heated vapor phase epitaxy (VPE) reactor using a dish-shaped susceptor pocket. Due to the columnar growth of the silicon carbide coating, high nodules are present on the pocket surface. As a result, the physical contact between wafer and pocket comprises discrete contact spots defined by nodules. To improve the wafer contact, the susceptor is diamond-honed to reduce the height of high nodules. Susceptor honing changes the Surface morphology of the pocket. The shape of nodule changes from ball-like to truncated-conic to disk-like with increasing extent of honing. This alters the stress profile at local contact points across the wafer. In this work, the influence of susceptor honing on nodule shape and induced wafer damage is studied. The pressure distribution at the contact spot is calculated using a model involving an elastic half-plane and a flat punch with rounded corner. The predicted pressure profile is compared with the experimentally observed wafer damage before and after honing. (c) 2005 Elsevier B.V. All rights reserved.