Design and characterization of a plasma etching system and its application to SiO2 etching.

Este trabalho apresenta uma metodologia para o projeto e construção de um equipamento de corrosão por plasma na configuração RIE. Um estudo detalhado da técnica de corrosão por plasma foi realizado para permitir a análise detalhada das características das configurações (equipamentos) existentes. Um estudo da corrosão a seco de SiO² crescido termicamente foi realizado utilizando-se cf/sub/4 e cf/sub/4+h/sub/2 como gases de processo para comprovar a viabilidade do equipamento construído. Este estudo foi aplicado na obtenção de espaçadores para estruturas salicide. Os resultados obtidos comprovam a adequação da metodologia de projeto empregada e a viabilidade do equipamento desenvolvido. Suas características encontram-se dentro da faixa encontrada em literatura para equipamentos de concepção semelhante.This work present a methodology for the design and construction of a RIE plasma etching equipment. A detailed study of the plasma etching technique was done to allow a detailed analysis of the known plasma etching configurations. A study of the plasma etching of thermal SiO2 in CF4 and CF4+H2 plasma was done to endorse the viability of the equipment built. This study was applied in a test-chip in order to get SALICIDEs spacers. The main topics of this work are: a) Study of the plasma etching technique and its configurations; b) Study of the main mechanics involved in the SiO2 plasma etching and the methodology for obtaining SALICIDEs spacers; c) Design of the gas admission system considering the reactant gas consumption during the plasma etching; d) Design of the vacuum system for CF4 carefully considering the losses involved; e) Characterization of the equipment built, with the following main results : i) Preliminary characterization of the equipment: - Effective pump speed in the chamber greater than (2,1±0,6) 1/s at a pressure of 13,3Pa of CF4; - Non-uniformity of etching in argon less than 5% in the range studied; - Self-bias potencial and plasma potencial ratio for argon greater than 3:1 in the range studied; - Electrode temperature during the process less than (30±1) °C in the range studied; ii) Characterization of the SiO2 plasma etching: - Etch rate of (1,17±0,03)nm/s for the operation point chosen in CF4 (13.3Pa, 100W, 21.4sccm); - Non-uniformity of etching less than 3% for the operation point chosen in CF4 (50mm wafers); - Selectivities of 7:1 and 25:1 for SiO2:Si and Si02:AZ1350J respectively (when using a CF4+22.5%H2 mixture at 13,3Pa, 200W and 21.4sccm total flow); - Degree of anisotropy dependant on the mask profile for CF4 processing and equal to 0.9 for CF4+22.5%H2 processing. The results shown endorse the designs methodology employed and the feasibility of the developed equipment.Its characteristics are in between those reported in literature for equipments of similar conception