等离子体浸没离子注入圆筒内表面的时空尺度

Dimension effects in plasma immersion ion implantation of cylindrical bore

等离子体浸没离子注入与工件外表面的注入不同 ,存在空间和时间上的尺度。研究结果表明 ,由于内腔 ,如内筒的有限尺寸 ,使注入电压的利用率降低 ,同时使内部等离子体快速耗尽 ,对于特定的内筒 ,利用提高注入电压从而提高注入能量只能在一定的电压范围内实现。在典型的外表面注入工艺条件下 ,内表面离子的耗尽速度是惊人的。如在对于直径 2 0cm的圆筒在 30kV、2× 10 15ions/cm3的条件下 ,等离子体耗尽时间仅为 0 .5 5 μs ,这个时间甚至小于多数脉冲电源的上升沿时间。结果表明 ,内部等离子体源的硬件结构可能是一种有效的解决方法。

Plasma immersion ion implantation is a new technique pertaining to ion implantation. Different from the case of exterior surface treatment, plasma immersion ion implantation of interior surface possesses dimension effects. Consequently it is a challenge to implant the inner wall of a cylindrical bore due to this finite dimension. The ion energy cannot be linearly changed with applied voltage and there exists a saturation value due to overlap effect of plasma sheath. The plasma in the bore may rapidly be depleted, which is attributed to finite plasma volume and plasma-sheath conflowing effect. For instance the plasma depletion time is about 0.55 μs when a bore with a diameter of 20cm is treated under conditions of applied voltage of 30kV and plasma density of 2×10 15 ions/cm 3. Interior plasma-source hardware may be an effective solution.