Quantitative Analysis of Trace Metals in Silicon Nitride Films by a Vapor Phase Decomposition/Solution Collection Approach

Abstract

A new approach is presented to analyze trace metals in silicon nitride films, using analytical techniques currently used in the semiconductor industry. Sample preparation involves decomposition of the nitride matrix by exposure to moist hydrofluoric acid followed by a short heat‐treatment at 300°C and collection of metallic impurities by the droplet scanning method. Analysis for metals was performed by total reflection X‐ray fluorescence. Lower detection limits compare favorably with published values obtained with other approaches and techniques that necessitate much higher quantities of sample. In view of possible applications of silicon nitride as a high‐dielectric‐constant material, the analysis of silicon nitride films (1–200 nm) deposited by low‐pressure chemical vapor deposition reveals that the deposition process is the major source of metallic impurities in the films, in contrast with currently used silicon dioxide films where wafers are the major source of metallic impurities. © 2000 The Electrochemical Society. All rights reserved.