Introduction

1. Canister abnormal scrubber #2 normal scrubber #4 #6 #3 #7 #1 Measurement Technology of Dry Etching Chlorinated Byproducts and Improvement Strategy in Thin Film Transistor Liquid Crystal Display Production Ruei-Hao Shie1, Chang-Chuan Chan21 Occupational Medicine and Industrial Hygiene, National Taiwan University, PhD student2 Occupational Medicine and Industrial Hygiene, National Taiwan University, Professor Centralized air abatement system Cl2 SF6 • Introduction • The advanced TFT-LCD dry etching processes of thin film layers is becoming increasingly preferred instead of conventional wet etching processes, as a new process. • Previous studies have focused on greenhouse-gas removal efficiency using a scrubber, and indicate potential fluorinated or chlorinated compounds of the etched material. Issues relating to the environment, safety, and health are challenging due to a lack of information on the use of chemicals and materials and what process forms byproducts. • Additional needs include characterizing and controlling plasma etching of gas emissions and byproducts. • In this study, we investigated the toxic byproducts in a thin film SF6/Cl2 dry etching gas, and establish a screen method for waste gas abatement equipment performance diagnosis. FTIR O2 FTIR Plasma source CH4 Etch by-products Canister Radical Ion Oxidation chamber + Resist Polymer layer Glass 800-1000 °C Wet scrubber Cooler Etch chamber N2 Fig.1. Fuel-fired combustion/wet scrubbing system (a) (b) • Materials and Methods • The thermal processing unit consists of an oxide combustion chamber, a wet scrubber, a vacuum pump, and a temperature/pressure control system, integrated in an enclosed unit (Fig.1). • This study determines dry etching gas and byproducts using online extractive Fourier transform infrared spectroscopy and a canister sampling / gas chromatography-mass spectrometry method. • A portable photo ionization detector was used to detect total volatile organic compounds after the scrubber. (c) (d) Fig.2. FTIR spectra for etch byproducts, (a)SF6, (b)SO2, (C)HCl, (d) C2H4 (a) (b) • Results • Findings showed sulfur hexafluoride etching gas and three byproducts, including sulfur dioxide, ethylene, and hydrogen chloride by FTIR and fourteen unknown and six byproducts before TPU, and thirteen byproducts after TPU by GC-MS (Fig.2). • The scrubber has high destruction removal efficiency for dry etching unknown byproducts at 1000 °C. • The temperature of partial combustion reactor processing equipment less than 750 °C generates toxic chlorinated byproducts after TPU. This study found thirty-four chlorinated byproducts at the abnormal local scrubber (Fig.3). • The portable photo-ionization detector screen method finds the abnormal scrubber, and the concentration of total volatile organic compounds is more than the normal scrubber after TPU (Fig.4.). (d) (c) 1.Sulfuryl fluoride Abundance 2.Silane, difluorodimethyl - 1000000 3.Methane, chloro - 4.Ethene, chloro - 900000 5.Ethene, 1,2 - dichloro - , (E) - 6.Ethene, 1,1 - dichloro - ; 800000 Methylene Chloride 7.Chloroform 700000 8.Carbon tetrachloride 9.Trichloroethylene 600000 10.Cyclotrisiloxane, hexamethyl - 11.Tetrachloroethylene 500000 12.Cyclotetrasiloxane, octamethyl - 13.3 - Hydroxymandelic acid, ethyl ester, di - TMS 400000 * :Internal standard * * 8 300000 * 200000 * 100000 12 7 6 10 11 9 2 5 1 3 13 4 0 Time -- > 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 Fig.3. Total ion chromatogram of dry etching by-products using the GC-MS, (a) two dry etching process before TPU (b) before and after TPU (c) test result after TPU at 1000 °C (d) test result after TPU at 750 °C • Conclusions • This research establishes dry etching chlorinated byproducts measurement technology and improves the local scrubber strategy. • A local scrubber that is not well maintained generates toxic chlorinated byproducts. • The screen method screens out the abnormal scrubber to modify and improve Fig.4. Screen method by photo ionization detector