Transient Annealing of Boron Implanted Devices
- PDF / 2,702,639 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 69 Downloads / 197 Views
TRANSIENT ANNEALING OF BORON IMPLANTED DEVICES S. R. Wilson, W. M. Paulson, C. J. Varker, A. Lowe, R. B. Gregory, R. H. Reuss, S. Y. Wu, J. D. Whitfield Semiconductor Research and Development Laboratory, Motorola, Inc. 5005 E. McDowell Road, Phoenix, AZ 85008
ABSTRACT Shallow-junction semiconductor devices have been fabricated using ion implantation and transient annealing with a Varian IA-200 isothermal annealer. Boron implanted diodes, npn bipolar transistors and CMOS ring oscillators have been fabricated and are compared to furnace annealed devices. Boron implanted diodes have been annealed with the RIA and yield acceptably low leakage currents, comparable to furnace annealed devices. The RIA devices have recombination lifetimes of %10 psec. The bipolar transistors subjected to a transient anneal have good base-collector and emitterbase junctions as well as gains of 'u1OO in good agreement with the design of the device. MOSFETs and CMOS ring oscillators were fabricated using self-aligned polysilicon gates. The transient annealed devices were equal or superior to devices which were furnace annealed at 800'C for 10 min. The low temperature furnace anneal was necessary to minimize short channel effects. The transient anneal resulted in ring oscillators which were a factor of two faster than furnace samples that were annealed. INTRODUCTION State of the art semiconductor devices/circuits have device geometries approaching I um. As these dimensions continue to shrink the need to form shallow junctions with minimal dopant diffusion will increase. The shallow junction can be formed by ion implantation, but the dopants, especially boron, tend to diffuse rapidly during the high temperature anneals which are necessary to activate the dopant and anneal the crystal damage. Several papers have reported using lasers, electrons beams and arc lamps to anneal implants with minimal diffusion [1]. Recently several authors [2-4] have reported the use of incoherent radiation to anneal implanted silicon. The incoherent annealing is not limited by throughput and thin film interference problems associated with laser annealing of devices. Complete activation and removal of damage with only slight diffusion has been reported [2-4]. However, very little device data has been reported [5]. In this paper we report results obtained from boron implanted devices annealed with a Varian IA-200 rapid isothermal annealer. Infrared radiation from a resistance heated sheet of graphite is used to heat the wafer [2]. The annealer has been3 described previously. The devices examined include large area (5.8 x 1O- /cm2 ) diodes, shallow junction bipolar transistors and narrow channel (
