Fin field effect transistor with multi-layer fin for multi-value logic applications and method of forming the same

Abstract

The present invention relates to a fin field effect transistor with multi-layer fins for multi-valued logic applications and a method of forming the same, wherein a method of forming a multi-valued logic transistor with a small footprint and the resulting device are disclosed. Embodiments include forming a plurality of fins on a silicon substrate, each fin being covered with a hard mask; filling the space between the fins and the hard mask with oxide; removing the hard mask and leaving each The fins are recessed, forming pockets in the oxide above each fin; in each of the pockets, a multi-layer silicon base layer is formed, the silicon base layers having a gradually increasing ratio of germanium or carbon content from the bottom to the top layer or Gradually decreasing doping concentration; chemical mechanical polishing of the top of the fin to achieve planarization; recessing the oxide to a depth slightly lower than the top of the fin and making the fin thickness equal to the thickness of each silicon base layer thickness; and forming a high-k dielectric gate and a metal gate electrode above the multi-layer silicon base layer.

Description

technical field [0001] The present invention is concerned with multi-valued logic (MVL) transistors. The present invention relates to FinFET technology nodes applicable to 14 nanometer (nm) - extreme mobility (14XM) and 10 nm and beyond. Background technique [0002] Transistor structures that are traditionally capable of handling multi-valued logic states are often formed as Figure 1A and Figure 1B shown, passing multiple threshold voltages of the transistor (e.g., V t0 , V t1 and V t2 ) and a shared gate electrode 101. Therefore, an NFET actually has N transistors sharing a common gate (ie, has the footprint of N transistors). Such as Figure 1C as shown, Figure 1A and Figure 1B Process four levels of logic signals (or 2 bits), 00, 01, 10, and 11, at the input voltage V g The 2-bit information in is determined by the output current I d Indicated by 2 bits of information. Although multi-valued logic is far more efficient and faster than current binary logic, e...

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Problems solved by technology

Additionally, forming a multiple V t The individual transistors are complex and expensive

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