METALLIC ARSENIC CONTROL DURING ANNEALING OF GaAs IN AsH3
Original Publication Date: 1985-Dec-01
Included in the Prior Art Database: 2005-Feb-19
The presence of metallic As requires control for contamination and safety purposes in annealing of gallium arsenide (GaAs) in arsine (AsH3). The control is achieved, as shown in the figure, through the use of a bulb with selected cross section and one end in a heated zone to prevent back diffusion and through the use of quartz wool in the exhaust area. There are two primary areas where metallic As causes difficulty. First, at the input end of the anneal tube where AsH3 is decomposed to As2, As4, and H2, some of the As2 and As4 can back diffuse and deposit on cool areas at the input end of the anneal tool. This can be prevented by using a "bulb", as shown at the left side of the figure. The front end of the bulb is in the hot area of the anneal tool, and the back end is in the cool input area.