Production silicon molecular beam epitaxy apparatus for 4-in.-diam wafers

Abstract

A high output production silicon molecular beam epitaxy apparatus for 4‐in.‐diam wafers is described. Throughput time in an ordinary operation is as short as 20 min/wafer with the help of cassette loading and high growth rates around 20 A/s. Silicon is deposited from a sweep eb‐gun with a hearth capacity of 50 cm3. Rotation of the wafer yields a thickness uniformity of <±5% across a 4‐in. wafer. Antimony as a dopant is evaporated from a conventional Knudsen cell and doping uniformity of <±10% is obtained. The uniformity variation reflects temperature variations of ±5 °C across a typical wafer. Good heating uniformity is achieved with a graphite meander heater. Low temperature cleaning of the substrate surface is also described.