使用感應式耦合電漿反應式離子蝕刻系統蝕刻氮化矽與氮化鈦:選擇比研究與SC1溶液對氮化鈦溼蝕刻速率研究

Etching of SixNy and TiN Usning Inductively-Coupled Plasma Reactive Ion Etching: Study of Selectivity and Etching Rate of TiN with SC1 Wet Etching

甯榮椿(Rong-Chun Ning)

指導教授 ： 洪銘輝 ； 郭瑞年

國立清華大學/工學院/材料科學工程學系/碩士(2010年)

https://doi.org/10.6843/NTHU.2010.00295

摘要

在本篇論文中，由電漿輔助化學汽相沉積系統成長的SixNy與用濺鍍系統成長的TiN經由感應式耦合電漿反應性離子蝕刻系統進行乾蝕刻，試圖找出使SixNy對TiN有高選擇比的蝕刻條件；也試圖找出TiN對SixNy及非破真空原子層沉積系統成長的Al2O3的SC1溶液在室溫下濕蝕刻選擇比。高SixNy對TiN選擇比以及SC1溶液在室溫下蝕刻TiN的速率都被找出，以利於製造微摻雜汲極結構的金氧半電晶體。在乾蝕刻氣體CHF3/O2的流量為20/10 SCCM的情況下得到了高達9的SixNy對TiN選擇比。此外，本篇論文對SixNy和TiN在不同的射頻功率下，乾蝕刻速率有相反趨勢的現象提出解釋。高射頻功率對蝕刻氣體的高解離程度，使得O2大量減少，因此沉積在SixNy表面防礙蝕刻進行的碳氟化合物高分子薄膜少了被O2反應移除的機會，因此SixNy蝕刻速率降低；高射頻功率也造成離子數量增加，促進離子轟擊效應，清除非揮發性的TiN副產物，因而增加TiN的蝕刻速率。同樣的機制也能用於解釋不同偏壓功率對SixNy和TiN蝕刻的趨勢。而Al2O3與SixNy在室溫下幾乎不被SC1溶液濕蝕刻，也避免了SC1溶液損害Al2O3氧化層與SixNy側壁間隔層的疑慮。論文中除了詳細描述蝕刻過程外，也介紹了各成長系統原理及電漿物理、蝕刻反應。

關鍵字

選擇比 ； 蝕刻 ； CHF3/O2 ； 感應式耦合電漿反應式離子蝕刻 ； 氮化矽 ； 氮化鈦

並列摘要

In order to make the lightly doped drain region structure Ⅲ-Ⅴ MOSFET self-aligned process well-controlled, information about dry etching and wet etching must be investigated. In this thesis, the dry etching of PECVD-SixNy and sputtered TiN was performed with inductively-coupled plasma reactive ion etching system to ascertain the etching rates and selectivity of SixNy to TiN. Wet etching rates of sputtered TiN, in-situ ALD-Al2O3, PECVD-SixNy with SC1 solution were also demonstrated. With the etching chemistry CHF3/O2 whose flow rate was 20/10 SCCM, the highest selectivity of SixNy to TiN as 9.0 was demonstrated with Prf = 200 W, Pbias = 10 W. The etching rates of SixNy and TiN were 170.1 and 18.9 separately in this condition. In addition, the opposite tendencies of etching rate with increasing rf power between SixNy and TiN were explained. For SixNy, high rf power discharged more gaseous etchants, resulting in the reduction of large amount of O2 volumes. Therefore, the fluorocarbon polymer film which was deposited during etching process could be removed with much less O2 and then the etching rate of SixNy would decrease. For TiN, high rf power discharged more gaseous etchants and generated more ions to bombard the TiN surface. This removed TiN dry etching solid byproducts faster, so it enhanced the etching rate. The same mechanism could also explain tendencies of etching rate with increasing bias power of SixNy and TiN. As for wet etching, the etching rate of TiN with SC1 solution was about 9.1 nm/min, while Al2O3 and SixNy etched little with SC1. it meant the damage of Al2O3 gate oxide and SixNy sidewall spacer didn’t need to be worried about. Besides, principles of film deposition instruments, plasma physics, and etching reaction were introduced in this thesis.

並列關鍵字

selectivity ； etch ； CHF3/O2 ； ICP-RIE ； SixNy ； TiN

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