Highly Selective Photoresist Ashing by Addition of Ammonia to Plasma Containing Carbon Tetrafluoride

Makoto Saito, Hideo Eto, Kayoko Omiya, Tetsuya Homma, Takao Nagatomo

研究成果: Article査読

3 被引用数 (Scopus)

抄録

A highly selective photoresist ashing process performed at low temperature using a downflow plusma consisting of a carbon tetrafluoride/oxygen (CF4/O2) gas mixture was developed for the fabrication of thin film transistor liquid crystal displays (TFTLCDs). Although the ashing rate was increased by using the CF4/O2 gas mixture plasma, the etching selectivity for underlying amorphous silicon (a-Si:H) films containing hydrogen decreased. The etching rate of a-Si:H films was decreased by the addition of ammonia (NH3). Since the etching rate of a-Si:H films decreased to zero at NH3 flow rates higher than 15 standard cubic centimeters per minute, an infinitely high etching selectivity for the photoresist films was achieved at room temperature. On the basis of the surface analysis results for a-Si:H films, a mechanism for the high etching selectivity of the photoresist films was proposed. Reaction products that were formed on a-Si:H films by the addition of NH3 gas to CF4/O2 gas mixture plasma obstructed the etching of a-Si:H films by fluorine (F) radicals, resulting in the high selectivity, It was found that the NH3, gas that was added to CF4/O2 gas mixture plasma reacted with a-Si:H. resulting in the formation of a protective reaction product which is considered to be an ammonium salt such as (NH4)2 SiF6

本文言語English
ページ(範囲)G59-G62
ジャーナルJournal of the Electrochemical Society
148
2
DOI
出版ステータスPublished - 2001 12 1

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 再生可能エネルギー、持続可能性、環境
  • 表面、皮膜および薄膜
  • 電気化学
  • 材料化学

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