Fundamental research on low energy electron beam assisted selective etching and deposition for submicron LSI fabrication

1. 对传统扫描电子显微镜（SEM）的试样腔进行了改进，使气体通过直径为0.2 mm的气体喷射喷嘴直接喷到试样表面。供气系统连接在SEM试样室上。电子束辅助XeF_2气体选择性刻蚀SiO_2:(1)实验结果表明，通过电子束辐照过程中监测的试样电流或二次电子电流可以确定刻蚀终点。(2)在较低的一次电子能、较低的试样温度、较大的气体流量和较大的电子束电流下，腐蚀速率较高。(3)发现在蚀刻终点的蚀刻孔直径与光束轮廓的尾部直径几乎相等。(4)利用能量为15 keV、电流为50 pA、尾径为0.15 mm的电子束探针，在2mum厚的SiO_2上形成了高径比为10的凹槽。电子束辅助Fe(CO)_5气体选择性沉积SiO_2:(1)在较低的一次电子能、较低的试样温度、较大的气体流量和较大的电子束电流条件下，沉积速率较高。(2)电阻率由沉积铁连接的两条Al金属线之间的电阻测量得到。结果表明，其电阻率比块状铁高出6个数量级以上。原因可能是由于铝表面的氧化。

1. The specimen chamber in a conventional scanning electron microscope (SEM) was modified to direct gas onto the specimen surface through a gas injection nozzle which had a 0.2 mm diameter. The gas supply system was attached to the SEM specimen chamber.2. Electron beam assisted selective etching of SiO_2 by using XeF_2 gas: (1) Experimental results showed that the etching end point could be determined from either the specimen current or the secondary electron current monitored during the electron beam irradiation. (2) The etch rate were higher at lower primary electron energies, lower specimen temperatures, larger gas flow rates and larger electron beam currents. (3) The etched hole diameters at the etching end point are found to be nearly equal to the tail diameters of the beam profiles. (4) A groove with the high aspect ratio of ten was formed in 2mum thick SiO_2 by using an electron beam probe with an energy of 15 keV, a current of 50 pA and a tail diameter-of 0.15mum.3. Electron beam assisted selective deposition on SiO_2 by using Fe(CO)_5 gas: (1) The deposition rate were higher at lower primary electron energies, lower specimen temperatures, larger gas flow rates and larger electron beam currents. (2) The resistivity was estimated from the measurement of resistance between two Al metal lines which were connected by Fe deposition. The result showed a resistivity of more than six orders of magnitude more than bulk Fe. The cause could be due to the oxide of Al surface.