Conformal and Ultra Shallow Junction Formation Achieved Using a Pulsed-Laser Annealing Process Integrated With a Modified Plasma Assisted Doping Method

Jae Eun Jang,Jaewon Jang,Seunghun Baik,Dong-Jae Kwon,Y S Kim,Hongki Kang,Hyuk-Jun Kwon

doi:10.1109/access.2020.3024636

Abstract

Recently, a shallow and conformal doping profile is required for promising 3D structured devices. In this study, we deposited the dopant phosphorus (P) using modified plasma assisted doping (PaD) followed by an annealing process to electrically activate the dopants. A rapid thermal annealing process (RTP) was the first approach tested for activation but it resulted in a deep junction (>35 nm). To reduce the junction depth, we tried the flash lamp annealing process (FLP) to shorten the annealing time. We also predicted the annealing temperature by numerical thermal analysis, which reached 1,020 °C. However, the FLP resulted in a deep junction (~ 30 nm), which was not shallow enough to suppress short channel effects. Since an even shorter annealing process was required to form a ultra-shallow junction, we tried the laser annealing process (LAP) as a promising alternative. The LAP, which had a power density of 0.3 J/cm2, increased the surface temperature up to 1,100 °C with a shallow isothermal layer. Using the LAP, we achieved a USJ with an activated surface dopant concentration of $3.86\times 10 ^{19}$ cm−3 and a junction depth of 10 nm, which will allow further scaling-down of devices.

Highlights

Over the last few decades, users’ demands and a price war among semiconductor industries have been driving the continuous scaling-down of electronic devices
RAPID THERMAL PROCESS (RTP) Our first attempt to activate the dopants involved the use of rapid thermal annealing process (RTP), which is the most commonly employed method
The starting point (0 nm) of the secondary ion mass spectrometry (SIMS) analysis is where the intensity of Si becomes higher than 95 %, which is the surface of the Si sample

Summary

Introduction

Over the last few decades, users’ demands and a price war among semiconductor industries have been driving the continuous scaling-down of electronic devices. We modified the plasma assisted doping (PaD) method by removing the bias power in order to eliminate damage that is concentrated near the Si substrate and make the dopant profile shallower and abrupt.

Results

Conclusion