Substitution of Single Crystalline Silicon for Polysilicon in Transistor Manufacture
Original Publication Date: 1985-Jun-01
Included in the Prior Art Database: 2005-Feb-18
The proposed process utilizes single crystalline silicon in place of polysilicon to reduce the resistance of the base in the extrinsic region. The base region is ion implanted through an oxide layer, using photoresist as a mask. The ion implantation is done at two levels of energy, resulting in two distinct distributions of boron (Fig. 1). A layer of nitride is deposited on top of the oxide and the emitter region defined by photoresist (Fig. 2). Collector reach-through (RT) and recessed oxide isolation (ROI) areas are shown. The nitride/oxide layers and a portion of the silicon base region are etched (Fig. 3). Sidewalls (oxide/nitride/oxide) are deposited and formed and the emitter region ion implanted through screen oxide (Fig. 4). The diffused junction depth at the emitter is adjusted to intersect the base, as shown in Fig.