| 摘要 |
PURPOSE:To improve the electric characteristics of a semiconductor element by shortening the base forming step converting a forming method for the base of a bipolar transistor. CONSTITUTION:A P type impurity diffusion is performed at relatively low temperature such as 850-1,000 deg.C, a glass layer formed in the diffusing step is then removed, a product is inserted into a core tube of a furnace of low temperature state of 700-850 deg.C, and the furnace temperature is raised at the rate of 1- 10 deg.C/min. Thereafter, H2-O2 burning at 900-1,050 deg.C or oxidation of 5-50min with dry O2 is performed for the purpose of controlling the layer resistance. Subsequently, the furnace temperature is raised at the rate of 1-10 deg.C/min, inert gas such as N2 is fed at high temperature of 1,100-1,250 deg.C for 10-900min, thereby deciding the diffusion depth. Thereafter, the furnace temperature is lowered at the rate of 1-10 deg.C, the oxidation is performed with H2-O2 burning at 900-1,050 deg.C for 5-300min, thereby forming oxidation becoming the diffusion mask of the next step, and then the furnace temperature is lowered at the rate of 1-10 deg.C, thereby producing a product from the furnace. |
