チップの「頭脳」たるトランジスタは電気の流れを制御する微小なスイッチです。一つのICに文字通り何10億個ものトランジスタが乗っています。より小さく、よりパワフルな電子機器を求める需要の高まりに促され、3D FinFET のような新しい構造のトランジスタや High-kゲート絶縁膜/メタルゲートのような新材料が開発されています。それにより、更なる微細化の進展が可能になっているのです。最新世代のトランジスタ寸法は原子数個分にまで来ており、それ故に製造は困難を極めます。こうした先端デバイスが設計意図通りの性能を発揮できるよう製造するには、並外れた制御精度で微細加工を行う能力が必要なのです。
ラムリサーチのソリューション
Computing power has experienced exponential growth over the last 70 years. This has largely been achieved through transistor scaling. Due to a continuous reduction in the size of transistors, engineers have been able to pack more and more of them onto a single chip[1]. This has led to faster, more powerful, and more energy-efficient devices. Improvements in fabrication processes and materials, along with better circuit design techniques, have enabled this scaling. As transistors have become smaller and more densely packed, we have started to reach limitations caused by the laws of physics.
As transistor sizes shrink, short channel effects make it more difficult for transistor gates to turn a transistor ON and OFF [1]. One method to overcome this problem is to move away from planar transistor architectures toward 3D devices. Gate-all-around (GAA) architectures are an example of this type of 3D device [2]. In a GAA transistor, the gate oxide surrounds the channel in all directions. A key process during the fabrication of GAA transistors involves the channel release step.