Gas Cluster Ion Beam Surface Profile Correction for Metal Gate Uniformity
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Solution Overview
Problem
In semiconductor manufacturing, particularly in FEOL processing, the 'gate-last' process for High-k/Metal Gate integration faces challenges due to non-uniformities caused by chemical-mechanical planarization (CMP), which affect the uniformity and performance of metal gate formation.
Innovation Solution
A method using gas cluster ion beam (GCIB) technology to correct surface profiles by selectively removing materials with sub-nanometer resolution, achieving a uniform surface profile by recessing dielectric materials beneath gate electrode materials and ensuring the final surface is within a predetermined tolerance, thereby addressing non-uniformities introduced by CMP.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If chemical-mechanical planarization (CMP) is used for gate-last process, then surface planarity is improved, but non-uniformities are introduced that affect metal gate formation
Solution Approach 1:
The patent applies preliminary surface profile correction using GCIB etching before metal gate deposition. By measuring the surface profile beforehand and using location-specific processing to recess high spots, the method prepares a more uniform surface in advance, preventing the non-uniformities that would otherwise occur during metal gate formation
Solution Approach 2:
The patent implements location-specific processing where different regions of the substrate receive different etching doses based on their local surface profile characteristics. The GCIB etch dose is modulated as a function of position to selectively recess high spots while preserving low spots, creating locally optimized surface quality for subsequent metal gate deposition
2Manufacturing precision
If location specific processing with variable scan speed is used, then surface profile correction precision is improved, but processing time increases
Solution Approach 1:
The patent applies partial action by focusing the GCIB etching only on regions that require correction (high spots) while using minimal or no etching in regions that are already within specification (low spots). This selective approach achieves the necessary surface profile correction precision while minimizing the total processing time compared to uniform etching of the entire substrate
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 corrects spatial non-uniformities in the surface profile, improving the uniformity and performance of metal gate structures, enhancing the precision and yield of semiconductor devices.
Implementation Method 1
selectively removing at least a portion of the first material using a gas cluster ion beam (GCIB) etching process
Data Source
AI summary
A method for correcting a surface profile on a substrate is described. In particular, the method includes receiving a substrate having a heterogeneous layer composed of a first material and a second material, wherein the heterogeneous layer has an initial upper surface exposing the first material and the second material, and defining a first surface profile across the substrate. The method further includes setting a target surface profile for the heterogeneous layer, selectively removing at least a portion of the first material using a gas cluster ion beam (GCIB) etching process, and recessing the first material beneath the second material, and thereafter, selectively removing at least a portion of the second material to achieve a final upper surface exposing the first material and the second material, and defining a second surface profile, wherein the second surface profile is within a pre-determined tolerance of the target surface profile.