High frequency field-effect transistors and method of making same

Abstract

A high frequency insulated gate field effect transistor comprises a semiconductor body of one type of conductivity, a base region of the same type of conductivity as the semiconductor body but with a higher impurity concentration than the body, and drain and source regions of the opposite type of conductivity. A portion of the base region is disposed between the drain region and the source region and the impurity concentration of the base region is reduced from the source region toward the drain region and is less at its junction with the drain region than that of the drain region. Such transistor can be incorporated in an integrated circuit as an amplifier transistor with a depletion type transistor as a load transistor. A common region serves both as a drain region of the amplifier transistor and a source region of the load transistor. A process of making the transistor and the integrated circuit comprises masking a semiconductor body, forming windows in the mask and successively diffusing through the same window both a first impurity to form the base region and a second impurity to form the source region.