Tungsten Gap Fill Nucleation with Thermal Etch for High-Aspect Openings
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Solution Overview
Problem
In semiconductor device manufacturing, conventional methods face challenges in forming tungsten features with good gap fill characteristics and low stress, as they often conflict with high deposition throughput, leading to issues like pinching-off at the top region of high aspect ratio features.
Innovation Solution
A method involving the use of a molybdenum-based etchant during tungsten CVD deposition to suppress growth at field and top regions, including forming a nucleation layer by exposing a substrate to a tungsten-containing precursor gas and etching with a molybdenum-based etchant gas, followed by depositing a bulk layer, all within a single processing chamber to improve gap fill and reduce stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional tungsten CVD deposition is used to fill high aspect ratio features, then deposition throughput is improved, but gap fill characteristics deteriorate due to pinching-off at the top region
Solution Approach 1:
A nucleation layer is deposited on the top region of the high aspect ratio feature before the main gap fill deposition. This preliminary layer creates a controlled surface that prevents pinching-off during subsequent tungsten deposition, allowing continuous filling without compromising gap fill characteristics or deposition throughput
Solution Approach 2:
The nucleation layer is formed in advance to prepare the surface for optimal tungsten deposition. This preliminary action ensures that the top region has the appropriate surface properties for uniform tungsten growth, preventing pinching-off and enabling both high throughput and good gap fill
2Manufacturing precision
If deposition time is extended to improve gap fill, then manufacturing precision improves, but deposition throughput decreases
Solution Approach 1:
The deposition process is divided into two distinct segments: a nucleation layer deposition step and a main gap fill deposition step. This segmentation allows each step to be optimized independently - the nucleation layer is deposited quickly to prepare the surface, then the main fill proceeds efficiently without pinching-off, achieving both precision and throughput
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 enhances the gap fill properties and reduces stress in tungsten features, improving the throughput and capacity for tungsten gap fill processing by preventing pinching-off and ensuring uniform deposition profiles.
Implementation Method 1
exposing the formed tungsten-containing layer to an etchant gas, wherein exposing the tungsten-containing layer to the etchant gas etches at least a portion of the tungsten-containing layer disposed at a top region of each of the plurality of openings
Implementation Method 2
exposing the substrate to a tungsten-containing precursor gas to form a tungsten-containing layer over a surface of each of the plurality of openings
Data Source
AI summary
A method of forming an interconnect structure over a substrate includes forming a nucleation layer over a surface of the substrate. The surface of the substrate comprises a plurality of openings, and the process of forming the nucleation layer includes (a) exposing the substrate to a tungsten-containing precursor gas to form a tungsten-containing layer over a surface of each of the plurality of openings, (b) exposing the formed tungsten-containing layer to an etchant gas, wherein exposing the tungsten-containing layer to the etchant gas etches at least a portion of the tungsten-containing layer disposed at a top region of each of the plurality of openings, and repeating (a) and (b) one or more times. The method further includes forming a bulk layer over the formed nucleation layer.