Three-Step Room-Temperature Cleaning of Bare Silicon Surface for Radical-Reaction-Based Semiconductor Manufacturing

Abstract

In this study, a cleaning method for pregate cleaning which can suppress the generation of the microroughness of silicon-wafer surfaces as well as remove various contaminations such as metallic impurities, organic materials, and particles has been investigated. Functional waters such as ozonized ultrapure water (-UPW), -added UPW (-UPW), and low-concentration HF and hydrogen peroxide solution have been used in this cleaning method at room temperature. The cleaning-process flow is as follows: (i) -UPW cleaning, (ii) diluted HF and mixture including surfactant molecules (FPMS) cleaning with megasonic, and (iii) 30%-isopropyl alcohol/UPW rinsing, i.e., realization of three-step cleaning. After the pregate cleaning, silicon substrates are set into the radical-reaction gate-insulator film-formation process using microwave-excited, high-density plasma equipment, where or ion bombardment onto the substrate surface has been introduced to eliminate absorbed surfactant molecules as well as hydrogen termination, before starting oxygen radical oxidation or radical nitridation . This advanced, three-step room-temperature cleaning is promising for future semiconductor manufacturing in conjunction with the newly developed radical-reaction-based semiconductor manufacturing.