Track: Ph.D. Thesis/Dissertation Presentation

Abstract

In wafer fabrication industry, liquid ammonium hydroxide is commonly used as a cleaning solution. The use of this solution at Chemical Mechanical Planarization (CMP) process has resulted in the presence of ammoniacal nitrogen in CMP's wastewater effluent. In view of new environmental pollution control, Malaysian Department of Environment (DOE) has introduced ammoniacal nitrogen as a new parameter to be regulated under Environment Quality (Industrial Effluents) Regulations 2009 with maximum allowable concentration of 20 parts per million (ppm) effective from 1st january 2015. This paper focuses on evaluating cleaning efficiency of Buffing and Cleaning steps at CMP Oxide process. This is to formulate best chemical and cleaning recipe in mimizing ammonium hydroxide usage. The challenge to this study is to ensure cleaning efficiency at post CMP Oxide process is not compromised. The authors have found that Buffing process has effectively removed almost all particles on wafer surface after polishing steps. This allows Cleaning process to focus in eliminating residues and metallic contaminants to enhance cleanliness of wafer surfaces. At Cleaning stage, the test using high flow of ultra pure water (UPW) and acids with peroxide mixture named SCS shown a comparable particle removal result with diluted ammonia solution. Methods to evaluate effectiveness of these media in removing residues and metallic contaminants are still under development by the authors.