The first and most striking characteristic shown by the data is the effect of oxygen in the atmosphere during diffusion to produce lower sheet resistivities than is observed in non-oxidizing atmospheres. This is shown in Table I where variation in sheet resistivity as a function of time of diffusion in various nitrogen-oxygen mixtures in presented. Also, one should note that while the sheet resistivity is lower in the early time of the diffusion, the sheet resistivity does not continue to decrease with extended diffusion time as it does in the atmosphere where the oxygen concentration is lower. In addition, with proper selection of the oxygen concentration the sheet resistivity will decrease linearly with the square root of the time characteristic of erfc diffusion profiles. Arsenosilicafilm and Antimonysilicafilm may be diluted with ethyl alcohol or methanol.
Dilution yields a thinner film for constant spin speed.
However, the concentration of arsenic or antimony in the glass layer remains the same. From the data listed there, it is noted that the thinner the dopant film the longer one may allow the diffusion to proceed before there is serious development of rosettes. With Arsenosilicafilm undiluted, about one hour is the maximum heat soak time before surface deterioration occurs. However, the material diluted one to one will not lead to surface deterioration for four hours of diffusion. Also, in the oxygen rich ambients, more difficulty with surface pitting in the masked regions will be experienced.