CVD assembly - has structured separate delivery of reaction gas and inert gas to zones of wafer substrate on hot table in chamber

摘要

A semiconductor wafer (1) is placed on a hot table (2) within a CVD reaction chamber (4). Gas blowing units (6a) at a gas head (5) deliver a CVD reactor gas (A) to the central main section of the wafer (1). Separate gas units (6b) delivery simultaneously an inert gas (B) to the edges of the wafer (1). The gas head (5) has a number of gas units (6a,6b), separate from each other. The wafer (1) temp. is held at a given level, and the pressure in the CVD reaction chamber (4) is between 100 Torr and atmospheric pressure. A high quality CVD layer with consistent thickness is deposited on the wafer (1), with reduction in the amt. of reaction gas (A) required and the volume of undesired residual particles. Pref. the two gas units (6a,6b) are on a common plane at a given gap from the wafer (1). The wafer (1) is generally circular, and the first unit (6a) is also circular with a dia. 30-50 mm less than the wafer dia. The second gas unit (6b) is a circular ring round the first gas unit (6a). ADVANTAGE - The system forms a high grade film on the substrate, with consistent thickness and quality, with a reduced consumption of reaction gas.