Tungsten Etching via Continuous and Pulsed RF Plasma
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional deposition processes for tungsten-containing materials in semiconductor fabrication often result in the formation of voids and seams within high aspect ratio features, leading to performance degradation and contamination in integrated circuits.
Innovation Solution
A method involving the use of continuous and pulsed RF plasma etching with nitrogen-containing and fluorine-containing gases to preferentially etch tungsten from the top of features, followed by subsequent deposition without nucleation delay, ensuring complete filling of features and minimizing seam formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional deposition process is used to deposit tungsten-containing materials, then the entire exposed surface area is covered, but voids and seams form inside high aspect ratio features
Solution Approach 1:
The patent applies preliminary action by performing an etch operation before deposition to modify the feature geometry. The etch process creates a modified profile with reduced overhang at the feature opening, which preliminary prepares the structure for subsequent complete tungsten filling without voids or seams
Solution Approach 2:
The patent changes process parameters by using a mixed nitrogen-containing and fluorine-containing plasma environment during etching, and by controlling plasma power and gas flow rates. These parameter changes enable selective tungsten removal and surface modification that prevents seam formation during subsequent deposition
2Productivity
If continuous wave plasma is used for etching tungsten, then etching efficiency is maintained, but nitridation of tungsten surface occurs
Solution Approach 1:
The patent applies periodic action by pulsing the plasma discharge during etching. The plasma is turned on and off in cycles, allowing controlled exposure to reactive species. This periodic action maintains etching efficiency while reducing cumulative nitridation effects on the tungsten surface
Solution Approach 2:
The patent changes plasma parameters by using a mixed nitrogen and fluorine plasma chemistry and controlling plasma power levels. The fluorine-containing species provide etching capability while the controlled nitrogen exposure and plasma conditions minimize unwanted nitridation of the tungsten surface
3Manufacturing precision
If plasma power is increased to improve etching uniformity, then etch thickness non-uniformity is reduced, but seam formation is exacerbated
Solution Approach 1:
The patent changes plasma parameters by using a mixed nitrogen and fluorine gas chemistry with controlled power levels. This parameter combination achieves adequate etch uniformity while the specific chemical environment prevents seam formation by controlling surface modification and deposition behavior
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
The method effectively eliminates seam formation and enhances the filling of high aspect ratio features with tungsten, improving the performance and reliability of integrated circuits by ensuring uniform deposition and reducing contamination.
Implementation Method 1
exposing the substrate to a continuous wave (CW) plasma generated from a nitrogen-containing and fluorine-containing gas; and exposing the substrate to a pulsed plasma generated from the nitrogen-containing and fluorine-containing gas, wherein the tungsten is preferentially etched from the top of the feature
Implementation Method 2
The pulsed plasma has a lower concentration of nitrogen radicals and can mitigate the effects of nitridation on the tungsten surface
Implementation Method 3
The pulsed plasma has a lower concentration of nitrogen radicals and can mitigate the effects of nitridation on the tungsten surface
Data Source
AI summary
Methods for etching tungsten and other metal or metal-containing films using a nitrogen-containing etchant gas are provided. The methods involve exposing the film to a continuous wave (CW) plasma and switching to a pulsed plasma toward the end of the etching operation. The pulsed plasma has a lower concentration of nitrogen radicals and can mitigate the effects of nitridation on the tungsten surface. In some embodiments, subsequent deposition on etched surfaces is performed with no nucleation delay. Apparatuses for performing the methods are also provided.