氧氣電漿灰化彩色濾光片間隔柱之製程研究與光譜分析

Oxygen Plasma Ashing of Photo Spacer and It’s Spectral Analysis

廖啟發(Chi-Fa Liao)

指導教授 ： 魏大欽

中原大學/工學院/化學工程研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000316

摘要

本研究利用氧氣電漿去除光阻做成的間隔柱(Photo Spacer)，加入NF3、氦氣和氮氣及改變其流量配比，觀察各種操作參數對灰化速率的影響，並以放射光譜儀（Optical Emission Spectroscopy，OES）觀察物種激發態的波峰強度值，推算各物種濃度，氣體解離率，探討各種物種濃度變化對灰化速率的影響。
研究發現，去除光阻以氧氣為主要的反應氣體，添加氦氣能提升灰化速率，並以OES全譜圖觀察得到各物種強度值，推算出氧氣及NF3的解離率均與氦氣流量呈正相關，推測可能是氦的電子激發態，與氧氣、NF3發生潘寧碰撞而有離子化及解離的效果，（1）離子化產生O2+及NF2+正離子轟擊，提供反應能量和造成懸鍵，（2）解離氧氣、NF3產生氧、氟原子；所以有助提升灰化速率。
需添加NF3，乃光阻中含有少量的矽，藉由解離出的氟原子去除之；此外NF3流量增加有助於氧氣解離，可能是因為氟原子能直接將氧氣解離為氧原子及氧—氟錯化物；雖然光阻去除同時需要氧、氟原子，但是過多的氧原子會稀釋氟原子，反之亦然，都不利於灰化速率，發現即便在不同的氧氣流量下，最佳的灰化速率均發生於氧氣與NF3流量比為10:1。

關鍵字

灰化速率 ； 光阻去除 ； 氧氣電漿 ； O2/NF3/He

並列摘要

This study aims to probe into the correlation between photoresist ashing rates and concentration of various active species in the plasma. variations in ashing rates were observed by manipulating different flow ratios and recipes of Photo Spacer (PS) made by photoresist stripped from oxygen plasma, with the addition of NF3, helium and nitrogen. The peak intensity values of species excited state watched by Optical Emission Spectroscopy (OES) are used to calculate the concentration of each species and gas dissociation rates.
This study reveals that oxygen is the main gas to strip of photoresist, and the ashing rate can be improved with helium as an additive. The calculated result indicates that it’s a positive correlation between the dissociation rate of oxygen and NF3 and the helium flow rate observed by OES. We suggest that helium excited states are triggers for Penning collisions and then cause the ionization and dissociation effects. The results are (1) ionization produces O2+ and NF2+ positive ion bombardment and therefore provides reaction energy and resulting dangling bonds, (2) dissociation of oxygen and NF3 produce oxygen and fluorine atoms. Therefore, the helium excited states help to enhance the ashing rate.
NF3 is needed to remove silicon related bondings with dissociation fluorine atoms because the photoresist contains a small amount of silicon atoms. The increase of NF3 flow can help to increase oxygen dissociation, and this could be cause from fluorine atoms dissociating oxygen molecules to form oxygen atoms and oxygen-fluorine compound. Photoresist removal also needs oxygen and fluorine atoms, but too much oxygen gas addition will dilute the fluorine atoms, and vice versa. The best ashing rate occurs in the oxygen flow rate 10 times of NF3 even under different oxygen flow rate.

並列關鍵字

oxygen plasma ； O2/NF3/He ； photoresist removal ； ashing rate

參考文獻

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