Engineering of the spin on dopant process on silicon on insulator substrate

Chiara Barri,Giulio Tavani,Erfan Mafakheri,Marco Abbarchi,Francesco Scotognella,Michele Perego,Daniel Chrastina,Andrea Barzaghi,Mario Lodari,Jacopo Frigerio,Luca Fagiani,Elisa Arduca,Monica Bollani,Alexey Fedorov

doi:10.1088/1361-6528/abbdda

Abstract

We report on a systematic analysis of phosphorus diffusion in silicon on insulator thin film via spin-on-dopant process (SOD). This method is used to provide an impurity source for semiconductor junction fabrication. The dopant is first spread into the substrate via SOD and then diffused by a rapid thermal annealing process. The dopant concentration and electron mobility were characterized at room and low temperature by four-probe and Hall bar electrical measurements. Time-of-flight-secondary ion mass spectroscopy was performed to estimate the diffusion profile of phosphorus for different annealing treatments. We find that a high phosphorous concentration (greater than 1020 atoms cm−3) with a limited diffusion of other chemical species and allowing to tune the electrical properties via annealing at high temperature for short time. The ease of implementation of the process, the low cost of the technique, the possibility to dope selectively and the uniform doping manufactured with statistical process control show that the methodology applied is very promising as an alternative to the conventional doping methods for the implementation of optoelectronic devices.

Highlights

The functionality of semiconductors relies strongly on the impurities that can be added to the intrinsic materials to change their electrical, physical, and optical properties
We report on a systematic analysis of phosphorus diffusion in silicon on insulator thin film via spin-on-dopant process (SOD)
The dopant is first spread into the substrate via SOD and diffused by a rapid thermal annealing process

Summary

Introduction

The functionality of semiconductors relies strongly on the impurities that can be added to the intrinsic materials to change their electrical, physical, and optical properties. The advantage of SOD over the aforementioned methods relies in its low cost, simple control of the process and its adaptability to different platforms, achieving a uniformity of the coated film on large substrates. It eliminates the need for dangerous gases and their related safety precautions, it is more environmentally friendly, and reduces manufacturing costs. In this work we systematically investigate the diffusion of phosphorous from a SOD source in silicon on insulator (SOI) wafers, RTA treatments are performed using different temperatures and process times, leading to the optimization of the desired final doping concentration. A localized doped Si-based nanodevice is tested as validation of the SOD procedure

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