Browse Prior Art Database

Ion-Implanted Polysilicon Process With Optimized Sidewall Profile

IP.com Disclosure Number: IPCOM000043565D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 52K

Publishing Venue

IBM

Related People

Chanclou, R: AUTHOR [+5]

Abstract

Doped polycrystalline silicon (polysilicon) is widely used in the semiconductor industry, and more particularly for FET products, as a field plate, gate electrode and/or the interconnection lines. In these applications, the tapered edge of the doped polysilicon pattern is desired to improve the edge coverage of the overlying material which may be either a passivating layer or a metal land. When polysilicon N-type doped with phosphorous atoms in an open-tube diffusion process with POCl3 or in situ doped during polysilicon deposition, the phosphorus concentration profile within the film is flat (Fig. 1, profile A). If ion implantation is used as the doping method, a low temperature anneal (35 min. at 800ŒC), to recrystallize the polysilicon, may lead to a non-uniform profile (Fig. 1, profile B).

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 93% of the total text.

Page 1 of 2

Ion-Implanted Polysilicon Process With Optimized Sidewall Profile

Doped polycrystalline silicon (polysilicon) is widely used in the semiconductor industry, and more particularly for FET products, as a field plate, gate electrode and/or the interconnection lines. In these applications, the tapered edge of the doped polysilicon pattern is desired to improve the edge coverage of the overlying material which may be either a passivating layer or a metal land. When polysilicon N-type doped with phosphorous atoms in an open-tube diffusion process with POCl3 or in situ doped during polysilicon deposition, the phosphorus concentration profile within the film is flat (Fig. 1, profile A). If ion implantation is used as the doping method, a low temperature anneal (35 min. at 800OEC), to recrystallize the polysilicon, may lead to a non-uniform profile (Fig. 1, profile B). Therefore, as the polysilicon etch rate during etching is enhanced where the dopant (phosphorous or arsenic) concentration is higher, the etch profile in some manner reproduces the concentration profile. Thus, it is possible to smooth the polysilicon etch profile if the dopant (phosphorus) ion energy is low enough (40 KeV). To keep high throughput from the ion implanter and low energy phosphorus ions, the P+2 beam at 80 KV has been selected. Standard profiles after poly etch and after reoxidation (end of process) are shown on Fig. 2 and compared to the proposed P+2 process in Fig. 3 with really improved side...