Sacrificial Material Freezing for Semiconductor Feature Collapse Prevention
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Solution Overview
Problem
High aspect ratio features in semiconductor processing are prone to collapse due to capillary forces from residual solvent after wet cleaning, leading to defects and inoperability in semiconductor devices.
Innovation Solution
A sacrificial material with a freezing point below the solvent's boiling point is used to fill and obstruct openings between features, preventing solvent retention and subsequent feature collapse by sublimating when exposed to a specific temperature and pressure range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wet cleaning is performed to remove residue, then cleaning effectiveness is improved, but capillary forces from residual solvent cause feature collapse
Solution Approach 1:
A sacrificial material is deposited into the openings between features before wet cleaning to preemptively prevent solvent retention. This preliminary action blocks the openings that would otherwise trap solvent and generate capillary forces during drying, thereby preventing feature collapse while maintaining cleaning effectiveness
Solution Approach 2:
The sacrificial material acts as an intermediary substance that temporarily occupies the openings between features. It mediates between the cleaning process and the features by preventing direct contact between residual solvent and the features, eliminating the capillary force mechanism that causes collapse
2Strength
If openings are obstructed to prevent solvent retention, then feature collapse is prevented, but openings must be removed afterward
Solution Approach 1:
The sacrificial material is selected to undergo phase transitions (melting and/or sublimation) at specific temperatures. After wet cleaning, the sacrificial material is removed by heating to melt or sublime it, converting it from a solid blocking material into a liquid or gas that can be easily evacuated, thus simplifying the removal process
Solution Approach 2:
The removal of sacrificial material is achieved by changing temperature parameters. Heating the structure to specific temperature ranges causes the sacrificial material to melt or sublime, fundamentally changing its physical state from a solid obstacle to a removable liquid or gas phase material
3Reliability
If sacrificial material is used to block openings, then solvent retention is prevented, but the sacrificial material must have specific freezing point properties
Solution Approach 1:
The sacrificial material is selected based on specific parameter thresholds: freezing point above ambient temperature and freezing point below solvent boiling point. These parameter constraints ensure the material remains solid during handling and cleaning, then transitions to liquid or gas for removal, providing reliable solvent retention prevention
Solution Approach 2:
The sacrificial material's phase transition properties are exploited to achieve both functions: remaining solid at room temperature to effectively block openings and prevent solvent retention, then transitioning to liquid or gas phase at elevated temperatures for easy removal, thus balancing reliability with processability
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 effectively reduces the likelihood of feature collapse during processing, maintaining structural integrity and preventing defects in semiconductor devices by ensuring the sacrificial material remains solid until sublimation, thus avoiding capillary-induced toppling.
Implementation Method 1
removing the sacrificial material via sublimation by exposing the sacrificial material to a particular temperature and pressure range
Implementation Method 2
A sacrificial material with a freezing point below the solvent's boiling point is used to fill and obstruct openings
Implementation Method 3
the sacrificial material can be removed by melting or sublimation
Data Source
AI summary
The present disclosure includes apparatuses and methods related to freezing a sacrificial material in forming a semiconductor. In an example, a method may include solidifying, via freezing, a sacrificial material in an opening of a structure, wherein the sacrificial material has a freezing point below a boiling point of a solvent used in a wet clean operation and removing the sacrificial material via sublimation by exposing the sacrificial material to a particular temperature range.