Method of forming a fin field effect transistor

Abstract

The invention provides a method for forming a fin type field effect transistor. The method comprises the following steps: etching a semiconductor substrate so as to form a plurality of fin-shaped vertical columns, depositing grid electrode material layers so as to cover the fin-shaped vertical columns and the exposed surface of the substrate, preparing a hard mask layer so as to cover the surfaces of the grid electrode material layers in a preset area, preparing a sacrificial layer, removing the hard mask layer above the planes of the top of the grid electrode material layers in the preset area so as to retain the hard mask layer on two sides of the fin-shaped vertical columns in the preset area, etching the grid electrode material layers and the fin-shaped vertical columns in the preset area by adopting the hard mask layer on two sides of the grid electrode material layers in the preset area as etching masks, thereby breaking the grid electrode material layers on two sides of the fin-shaped vertical columns in the preset area into two independent parts. According to the method, SiN is introduced as the hard masks, so that Fins of different groups are in different heights for self-alignment of later photos.

Description

technical field [0001] The invention relates to the field of semiconductor preparation, in particular to a method for forming a fin field effect transistor. Background technique [0002] With the continuous development of semiconductor technology, traditional planar devices can no longer meet people's needs for high-performance devices. FinFET (Fin Field‐Effect Transistor, Fin Field Effect Transistor) is a three-dimensional device, including fins formed vertically on the substrate and stacked gates intersecting the fins. This design can greatly improve circuit control and reduce leakage current (leakage), and can also greatly shorten the gate length of the transistor. [0003] In some processes, it is necessary to separate the two gates of the FinFET to form a drive gate and a control gate, respectively. [0004] Figure 1A Shown is the state of the FinFET before separation, the two ends are the source (source, S) and the drain (drain, D) of the device, the gate electrode ...

AI Technical Summary

Problems solved by technology

[0005] At present, there are two ways to separate the gate electrodes on both sides of the FinFET. One is to use chemical mechanical polishing to remove the gate at the top of the Fin. Refer to Figure 2A As shown in -2B, a number of raised fin-shaped pillars 3 are formed on the semiconductor substrate including the buried oxide layer (BOX) 2 and the substrate 1, and a barrier layer (stopper) is also prepared on the top of the fin-shaped pillars 3 4. The gate electrode material layer 5 covers the upper surface of the fin-shaped pillar 3, the barrier layer 4 and the exposed semiconductor substrate, and the gate electrode material layer is polished by CMP (Chemical Mechanical Polishing), and the barrier layer 4 for the grinding stop layer, thus forming Figure 2B structure shown, but this method is difficult to integrate 4T-FinFET and 3T-FinFET together

[0006] Another way is to add a mask, refer to Figure 3A As shown in -3B, a layer of photoresist 6 is coated on the gate electrode material layer 5, and the gate at the top of the specified Fin is etched away by photolithography, but this method is a huge problem for the alignment of the pattern. challenges that are not applicable in FinFET devices with smaller critical dimensions

Images