Segmented Silicon Nitride Films for Reduced Wafer Interfacial Strain
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Solution Overview
Problem
Current methods for depositing films on semiconductor wafers with a different coefficient of thermal expansion (CTE) than the wafer often result in delamination or fracture, especially on large wafers, due to intrinsic stress and mismatched CTE, which complicates adhesion and increases production costs.
Innovation Solution
A method involving the selective deposition and removal of silicon nitride layers on semiconductor wafers, with fill materials like silicon dioxide, to create gaps and planarize surfaces, reducing strain and enabling the deposition of CTE-mismatched films across large wafer areas, including 300 mm wafers, by using techniques such as dicing saws and etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If films with different CTE are deposited on semiconductor wafers, then the film functionality is achieved, but delamination or fracture occurs due to intrinsic stress and CTE mismatch
Solution Approach 1:
The patent applies segmentation by introducing periodic gaps in the silicon nitride film along dicing lanes, dividing the continuous film into segmented regions. This segmentation reduces the cumulative stress in the CTE-mismatched film, preventing delamination and fracture while maintaining film functionality across the entire wafer surface.
Solution Approach 2:
The patent extracts the problematic stress-carrying portions of the film by removing material along dicing lanes to create gaps. By taking out these specific regions, the intrinsic stress is relieved, allowing the remaining film portions to maintain strong adhesion to the substrate without the damaging effects of cumulative stress.
2Reliability
If gaps are created in the silicon nitride layer to relieve strain, then adhesion is improved, but the structural continuity of the film is disrupted
Solution Approach 1:
The film is deliberately segmented into continuous regions over active device areas and gaps along dicing lanes. This segmentation strategy maintains structural integrity where needed while creating stress-relief zones where gaps are introduced, balancing adhesion improvement with functional continuity.
Solution Approach 2:
The patent applies local quality by making the film structure non-uniform: continuous over active regions to maintain functionality, and discontinuous (with gaps) along dicing lanes to relieve stress. Each region has different structural properties optimized for its specific function.
3Reliability
If multiple deposition and removal cycles are performed to create gaps, then strain is reduced and adhesion is improved, but the manufacturing process complexity increases
Solution Approach 1:
The gaps are created preliminarily by removing material before the final film deposition is complete. By performing the removal action during the deposition sequence rather than as a separate post-processing step, the patent integrates stress relief into the manufacturing flow, reducing overall process complexity.
Solution Approach 2:
The patent merges multiple functions into the deposition sequence: film deposition, gap creation through removal, and stress relief are combined in an integrated process flow. The gaps are formed as part of the deposition sequence itself, combining what could be separate operations into a unified manufacturing step.
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 allows for the successful deposition of CTE-mismatched films on wafers of any size, increasing production capacity and reducing costs by alleviating strain and improving adhesion, thereby enhancing the reliability and efficiency of the film deposition process.
Implementation Method 1
depositing a first portion of a silicon nitride layer on the silicon wafer
Implementation Method 2
depositing a first portion of a silicon nitride layer on the silicon wafer
Implementation Method 3
A first fill material is deposited on the first portion of the silicon nitride layer and into the one or more first gaps
Data Source
AI summary
In some embodiments a method comprises depositing a first silicon nitride layer on a top surface of a semiconductor wafer and forming one or more first gaps in the first silicon nitride layer. The one or more first gaps can relieve stress formed in the first silicon nitride layer. A first fill material is deposited on the first silicon nitride layer and the first silicon nitride layer is planarized. A second silicon nitride layer is deposited across the first silicon nitride layer and one or more second gaps are formed in the second silicon nitride layer. The one or more second gaps can relieve stress formed in the second silicon nitride layer. A second fill material is deposited across the second silicon nitride layer and the second silicon nitride layer is planarized.