Developmental Study of Highly-Uniform Large-Diameter ECR Plasma Reactor

本研究的目的是开发一种用于高速加工12英寸晶圆的大直径电子回旋共振（ECR）等离子体源。我们构建了一种多环天线，该天线由用于微波辐射的环形狭缝同心阵列和用于多环尖端磁场的永磁体组成。2.45 GHz的微波通过同轴馈线进入环形狭缝，与狭缝出口外5mm处的ECR层相遇。在多环尖场中，带电粒子沿方位角方向漂移。这导致了方位角对称等离子体的产生。微波从高磁场侧以r波的形式从狭缝向ECR层传播。注意到等离子体不会在狭缝内产生，因为由于狭缝壁的邻近，带电粒子的损失率很大。在氩气压力为5*10^<-4> Torr的条件下，等离子体源产生的等离子体直径为30 cm，密度为n = 2*10^<11>cm^<-3>。我们通过改变狭缝的数量来测量等离子体参数，发现在最外层的一个狭缝处等离子体均匀性最好。在距离MA天线10厘米处，当n = (8-10)*10^<10>cm^<-3>时，均匀性为*10%。这一结果与连续性方程的数值计算结果是一致的，假设初始震源剖面由裂缝决定。MA天线改进为AMA（可调MA）天线，在r =140和90 mm处有两个环形狭缝。每个狭缝由一个磁控管独立驱动。这意味着微波功率输入的径向轮廓可以通过简单地改变两个磁控管的输出来调节。利用AMA天线，我们可以在离天线较近的距离内产生密度更高、均匀度更高的等离子体。

The purpose of this research is to develop a large diameter electron cyclotron resonance (ECR) plasma source for high-speed processing of 12 inch wafers. We have constructed a multi-annular (MA) antenna which consists of a concentric array of annular slits for microwave irradiation and of permanent magnets for multi-ring cusp magnetic field. The microwave at 2.45 GHz is fed via coaxial line and is distributed into the annular slits to encounter the ECR layr located 5 mm beyond the exit of the slits. Charged particles drift in azimuthal direction in the multi-ring cusp field. This leads to azimuthally symmetric plasma production. The microwave propagates from the slit to the ECR layr from high magnetic field side as R-waves. It is noted that the plasma is not produced inside the slits because the loss rate of charged particles is large due to proximity of slit walls.The plasma source using this MA antenna has produced a plasma of 30 cm in diameter with density n = 2*10^<11>cm^<-3> for Ar gas pressure 5*10^<-4> Torr. We measured plasma parameters by changing the number of the slits to find that the uniformity of the plasma is best for one slit at the outermost location. The uniformity is *10% for 30 cm diameter plasma with n = (8-10)*10^<10>cm^<-3> at 10 cm from the MA antenna. This result is consistent with a numerical calculation of the equation of continuity assuming an initial source profile determined by the slits.The MA antenna has been improved to AMA (adjustable MA) antenna, which has two annular slits at r =140 and 90 mm. Each slit is driven by a magnetron independently. This means that the radial profile of microwave power input is adjustable by simply changing the outputs of two magnetrons. By using AMA antenna, we have achieved plasma production with higher density, higher uniformity at shorter distance from the antenna.