Phosphosilicate Glass Plasma Treatment for Mask Adhesion
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Solution Overview
Problem
Inadequate cleaning methods for semiconductor wafers, such as jet scrubbers and chemical cleaning, fail to effectively remove phosphine residual layers from PSG layers, leading to surface contamination and issues with mask layer adhesion, increasing costs and cycle time.
Innovation Solution
Exposing the phosphine residual surface portion of a PSG layer to a reactant plasma, specifically using oxygen-based gases like N2O at reduced RF power, integrates the residual phosphine into the PSG layer, allowing for its removal and preventing mask popping without the need for intervening scrubbing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If jet scrubber or wet chemical cleaning is used to remove phosphine residual layers, then cleaning capability is improved, but process complexity and cost increase
Solution Approach 1:
The patent extracts the harmful phosphine residual layer through a simple plasma exposure step that selectively removes phosphine-containing species from the PSG layer surface without requiring complex jet scrubber equipment or multiple chemical cleaning steps
Solution Approach 2:
The patent replaces the mechanical jet scrubber system with a plasma-based chemical process that uses reactive species to selectively remove phosphine residuals, eliminating the need for high-velocity fluid injection equipment and complex mechanical cleaning apparatus
2Object-affected harmful factors
If additional cleaning steps are added to remove phosphine residuals, then surface cleanliness is improved, but cycle time increases
Solution Approach 1:
The patent combines the phosphine removal function with the existing PSG layer formation process by performing plasma exposure immediately after deposition within the same processing sequence, eliminating the need for separate cleaning steps and reducing total cycle time
Solution Approach 2:
The patent performs plasma treatment as a preliminary step before mask layer deposition, ensuring the surface is ready for subsequent processing without requiring intermediate cleaning operations that would extend the manufacturing cycle
3Ease of manufacture
If phosphine residual surface portion is not integrated into PSG layer, then deposition process is simpler, but mask layer adhesion deteriorates
Solution Approach 1:
The patent changes the surface chemistry parameters of the PSG layer by exposing it to plasma, which modifies the surface composition to integrate phosphine residuals and create a surface that promotes strong adhesion of subsequent mask layers while maintaining the simplicity of the original deposition process
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 reduces cycle time and costs by eliminating the need for additional cleaning steps, saving approximately $0.60 per wafer and 10,000 lot hours over 40 weeks, while ensuring proper adhesion of masking layers and minimizing mask popping issues.
Implementation Method 1
exposing the phosphine residual surface portion to a reactant plasma
Implementation Method 2
the reactant plasma may comprise oxygen
Implementation Method 3
forming the PSG layer and exposing the phosphine residual surface portion may be performed in an RF plasma chamber
Data Source
AI summary
A method for making semiconductor devices may include forming a phosphosilicate glass (PSG) layer on a semiconductor wafer, with the PSG layer having a phosphine residual surface portion. The method may further include exposing the phosphine residual surface portion to a reactant plasma to integrate at least some of the phosphine residual surface portion into the PSG layer. The method may additionally include forming a mask layer on the PSG layer after the exposing.