×

Method of forming vertical field effect transistors with different threshold voltages and the resulting integrated circuit structure

  • US 9,960,271 B1
  • Filed: 04/18/2017
  • Issued: 05/01/2018
  • Est. Priority Date: 04/18/2017
  • Status: Active Grant
First Claim
Patent Images

1. A method comprising:

  • forming a stack of sacrificial layers on a semiconductor layer, the stack having a first portion and a second portion, the first portion comprising an extra sacrificial layer as compared to the second portion;

    etching a first multi-layer fin in the first portion and the semiconductor layer and a second multi-layer fin in the second portion and the semiconductor layer; and

    concurrently forming a first vertical field effect transistor using the first multi-layer fin and a second vertical field effect transistor using the second multi-layer fin, the concurrently forming comprising;

    forming a first upper dielectric spacer on the first multi-layer fin and a second upper dielectric spacer on the second multi-layer fin; and

    performing multiple etch processes that remove the sacrificial layers from the first multi-layer fin and the second multi-layer fin, wherein the multiple etch processes comprise;

    initial etch processes that remove all of the sacrificial layers except the extra sacrificial layer on the first multi-layer fin; and

    an isotropic etch process that removes the extra sacrificial layer from the first multi-layer fin and etches back the first upper dielectric spacer and the second upper dielectric spacer,wherein, during the isotropic etch process, the first upper dielectric spacer is partially protected by the extra sacrificial layer until the extra sacrificial layer is removed such that the second upper dielectric spacer is etched back faster than the first upper dielectric spacer and such that, following the isotropic etch process, the first upper dielectric spacer is taller than the second upper dielectric spacer.

View all claims
  • 5 Assignments
Timeline View
Assignment View
    ×
    ×