Controlled Lateral Etching of Titanium Nitride in a CMOS Gate Structure Using DSP+

Abstract

The metal gate electrode is used in advanced CMOS semiconductor devices to address new requirements including high conductivity to minimize delays due to interconnections between devices and tunable work function to allow n and p-type devices to operate in surface channel mode with minimal gate depletion effects. The introduction of metal elements to the CMOS gate, such as titanium nitride can impose significant changes to the device fabrication process. This includes process chemistry to pattern metallic structures and to remove metallic-containing residues. In this paper we will report the results of titanium nitride recession in the metal gate stack using a dilute mixture of sulfuric acid, hydrogen peroxide and hydrofluoric acid known by the trade name DSP+. This paper demonstrates that DSP+ can recess the TiN into the gate stack more efficiently than oxidation/etch solutions allowing tuning of the gate length and ensuring complete sidewall encapsulation of the gate.

Microfabrication and microfluidics for 3D brain-on-chip

“…hydrofluoric acid (HF), which are well-known etchants. 53 Also, the within the MESA+ Nanolab cleanroom obligated standard pre-furnace cleaning of the TiN samples by fuming (100%) and boiling (69%) nitric acid (HNO3) (prior to poly-silicon LPCVD) was found to etch the TiN layer. Moreover, the etchant used for the patterning of the TiN layer, RCA-1, has been identified to lead to non-uniform etching, which is conform literature.…”