O_2/SF_6气氛下光刻胶灰化反应的机理研究

Ashing Mechanism of Photo-Resist in Oxygen-Sulfur Hexafluoride Mixtures

光刻胶的大面积灰化是TFT工艺的核心工艺之一,本文研究了在增强型电容耦合射频放电模式下,SF6比例对光刻胶灰化率的影响,并建立表面反应模型对此进行解释。研究表明,纯O2气体中加入少量SF6,能够有效提高等离子中氧原子浓度和活化光刻胶的生成量,增大光刻胶灰化率。当SF6比例过高时,氟原子与氧原子形成化学吸附位竞争将导致光刻胶灰化率降低,而粒子间碰撞的加剧与溅射产率的下降使这一趋势愈加明显。

Photo-resist ashing, one of the core techniques in fabricating thin film transistor and liquid crystal display was studied. The impacts of the gas flow rates and addition of SF6 into oxygen flow on the ashing rate and uniformity of photo-resist in enhanced capacitively coupled plasma （ECCP） discharge was evaluated. The results show that addition of small amount of SF6 into oxygen significantly increased the ashing rate,possibly because of an increase of atomic oxygen content in the plasma, and because of SF6-induced surface activation of the photo-resist. However, too much addition of SF6 decreased the ashing rate. The possible mechanisms, responsible for the ashing rate enhancement, were tentatively dis- cussed.