A Design for Selective Wet Etching of Si3N4/SiO2 in Phosphoric Acid Using a Single Wafer Processor. Issue 4 (22nd March 2018)

• Record Type: Journal Article
• Authors: Chien, Ying-Hsueh Chang; Hu, Chi-Chang; Yang, Chi-Ming
• Is Part Of: Journal of the Electrochemical Society. Volume 165:Issue 4(2018)
• Page Start: H3187
• Page End: H3191
• Publication Date: 2018-03-22
• Subjects: phosphoric acid -- single-wafer processor -- wet etching selectivity; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0281804jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Using single-wafer processors in the wet process implementation is a tendency for advanced semiconductor manufacturing due to the advantages of free contamination, flexible process control, and an improved particle removal efficiency without pattern damage. However, in the process of silicon nitride removal, not only the cost concern of phosphoric acidic consumption but also the process performances including etching rate, uniformity, and selectivity, are the barrier that makes this process hard to be switched to the single-wafer type from the bench type. Here we propose a novel design which introduces an upper-wafer heater plate to keep high temperatures of the phosphoric acid etchant in order to overcome the common issues of low etching rate, poor uniformity, and low selectivity in single-wafer processors suffering in the nitride strip process. In this work, the interactive influences of the operation variables, such as rotation speed, puddle time, and temperature, in the single wafer processor on the etching rate, uniformity, and selectivity are investigated to gain a deep understanding on this process. The etching selectivity obviously decreases from ca. 100 to 60 when the H3 PO4 temperature is increased from 144 to 154°C while the introduction of a heater plate has been demonstrated to sharply promote the etching selectivity.