半導體微影奈米尺寸的穩定性控制

Abstract

一個新的Reticle設計，利用鑽石高熱傳導，在傳統的pellicle-reticle底端增加一層鑽石薄膜，鑽石材料取代pellicle。這個方法將會幫助未來微影(photo-lithography)製程進展到35nm以下， 光罩(reticle)因長時間受到光熱能的影響而產生微量膨脹變形問題獲得改善。曝光能量是影響關鍵尺寸 (Critical Dimension)的重要因素，曝光能量會改變線寬(Line-Width)與白邊(white wall)的大小，且線寬與白邊這兩者與曝光能量為線性關係( >0.85)，但是如果曝光能量太高或太低將會使線寬不穩定。曝光能量之所以能影響關鍵尺寸的原因是光阻(Photo-Resist)吸收到比較高的能量時與顯影液接觸會產生比較劇烈的中和(Neutralized)反應，所以越高曝光能量時線寬會越小，且關鍵尺寸會因為邊緣受到高的能量而產生光阻吸收能量不均勻的現象,因為這個原因所以要得到更小的關鍵尺寸並不能把曝光能量刻意的加高,如果要使用這種方式,則必須更改用適合這種能量的光阻. 如果要取得更小的線寬則必須使用解析度(resolution)較佳的光阻與波長較短的光源.但是高曝光能量卻能使得光阻底部吸收到更多的反射能量而使得白邊變小。但是如果曝光能量太低，將使得光阻吸收到能量不足而無法與TMAH(Tetramethylammonium Hydroxide)產生中和反應，而無法形成圖形。

A new reticle is designed that takes advantage of the high value of thermal conductivity of diamond to add a layer of diamond film to the bottom of traditional pellicle-reticle; that is, the new reticle replaces the pellicle with a diamond material. This method may help maintain the future manufacturing process of photo-lithography below 35 nm and can improve the problem of slightly out of shape reticle caused by the long-term effects of light and thermal energy. Exposure dose is one of the most important factors that affects CD (Critical Dimension) bar since it can change the dimension of line-width and white wall. In this work, both line-width and white wall present a linear relationship ( >0.85) with respect to the exposure dose. However, too high or too low of exposure dose would impose the instability of line-width. The reason for exposure dose to affect CD bar is that when absorbing high energy the photo-resist (PR) can produce more severely neutralized reaction as it in contact with developer. Therefore, the higher the exposure dose the smaller is the line-width. Also, CD bar would reveal inhomogeneous phenomenon caused by absorbing high energy via the edge of PR. Due to this reason, increasing the exposure dose intentionally is not an appropriate method to obtain a smaller CD bar. When it comes to using exposure energy to obtain the desirable CD, PR capable of being exposed with higher energy should be considered. If it becomes necessary to obtain much smaller line width, then it is necessary to use PR of better resolution in conjunction with a light source containing a much lower wavelength. But, higher exposure dose would cause the bottom of PR to absorb more reflective energy and make white wall become smaller. On the contrary, if exposure dose becomes too low, PR would not form a pattern due to the fact that the absorption of exposure energy by PR is not strong enough to produce a neutralized reaction when in contact with TMAH (Tetramethylammonium Hydroxide).