Gate Contact Plasma Cleaning for Seam-Free Tungsten Fill
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Solution Overview
Problem
The semiconductor industry faces challenges in forming reliable contacts to source/drain regions in finFET devices due to the presence of polymeric residues and etch by-products, which can increase contact resistance and degrade surface quality during the etching process.
Innovation Solution
A post-etch treatment using a plasma formed from a gas mixture of diatomic oxygen and diatomic hydrogen is applied to remove these residues and by-products, followed by a bottom-up deposition process to form conductive fill materials like tungsten, preventing seam formation and improving growth height and incubation time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an etching process is used to form contacts through dielectric layers, then openings can be formed to expose underlying structures, but polymeric residues and etch by-products remain on the surfaces, increasing contact resistance and degrading surface quality
Solution Approach 1:
A plasma treatment step is introduced before the bottom-up deposition of conductive fill material to preemptively remove polymeric residues and etch by-products from the contact opening surfaces. This preliminary cleaning action ensures that the subsequent tungsten deposition occurs on a clean surface, preventing contact resistance issues and eliminating the need for extensive post-etch cleaning.
Solution Approach 2:
The patent utilizes a plasma process with a specific gas composition (oxygen and hydrogen without nitrogen) to convert the harmful polymeric residues and etch by-products into volatile compounds that can be easily removed. The plasma treatment transforms the contaminated surface into a clean, reactive surface that promotes better adhesion and growth of the conductive fill material.
2Reliability
If conventional bottom-up deposition is performed after standard etching, then conductive fill material can be deposited, but seam formation occurs and growth height and incubation time are degraded due to surface contamination
Solution Approach 1:
The plasma treatment is performed as a preliminary step immediately before the bottom-up deposition process. This treatment modifies the surface chemistry of the contact openings, removing organic residues and creating a surface that is more receptive to tungsten nucleation and growth, thereby preventing seam formation and reducing incubation time delays.
Solution Approach 2:
The patent changes the chemical composition parameters of the plasma treatment by using a gas mixture of oxygen and hydrogen while explicitly excluding nitrogen. This parameter change in the plasma chemistry creates optimal surface conditions for subsequent tungsten deposition, enhancing contact reliability and deposition quality.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively removes polymeric residues and etch by-products, reduces nitrogen profiles, and enhances contact growth heights, leading to improved contact reliability and reduced incubation time delays compared to previous methods.
Implementation Method 1
performing a post etching treatment wherein the post etching treatment includes forming a plasma comprising oxygen and hydrogen
Implementation Method 2
forming a plasma comprising oxygen and hydrogen, wherein the plasma does not include nitrogen
Implementation Method 3
performing a bottom-up deposition process to fill the first opening
Data Source
AI summary
Semiconductor devices and methods of manufacturing the semiconductor devices are described herein. A method includes forming a gate electrode, a gate electrode contact layer over the gate electrode, forming a dielectric layer over the gate electrode contact layer, and performing an etch through the dielectric layer, the etch forming an opening that exposes the gate electrode contact layer. The method further includes performing a post-etch treatment on the opening formed by the etch process by exposing the opening to a plasma. The method further includes forming gate electrode contacts in the openings after the post-etch treatment by a bottom-up deposition process.