Wafer Cleaning via Pre-Etch Passivation to Prevent Pitting
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Solution Overview
Problem
Current semiconductor wafer cleaning techniques are costly, inefficient, and fail to achieve low particle counts, undetectable metals, and limited surface roughness, particularly in advanced integrated circuit manufacturing, where stringent requirements for sub-100 nm devices necessitate improved methods to prevent contamination and yield loss.
Innovation Solution
A method involving etching with a HF solution, followed by ozonation and then Standard Clean 1 (SC1) application, with optional steps including rotation and acoustic energy, to prevent surface pitting and enhance cleaning efficiency, conducted in a single chamber or batch processing immersion tanks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard clean 1 (SC1) is used to clean the substrate, then particle removal is improved, but surface pitting occurs
Solution Approach 1:
The method applies preliminary surface passivation or oxide layer growth before SC1 cleaning. By pre-forming a protective layer on the substrate surface, the method prevents the harmful pitting effect that would otherwise occur during the SC1 cleaning process, while still allowing effective particle removal.
Solution Approach 2:
The protective oxide layer or passivation layer serves as a cushioning barrier before the SC1 cleaning step. This beforehand protection absorbs or mitigates the harmful effects of SC1 on the substrate surface, preventing pitting while maintaining cleaning effectiveness.
2Productivity
If aggressive cleaning methods are used to reduce particle counts, then cleaning efficiency is improved, but surface roughness increases
Solution Approach 1:
By applying surface passivation or oxide layer growth before the cleaning process, the method enables the use of more effective cleaning chemistry without the penalty of increased surface roughness. The protective layer acts as a sacrificial barrier that allows aggressive cleaning while preserving surface smoothness.
Solution Approach 2:
The oxide layer or passivation layer serves as an intermediary between the cleaning chemicals and the substrate surface. It mediates the cleaning process by allowing particle removal while preventing direct contact between harsh chemicals and the substrate, thus maintaining surface smoothness.
3Ease of manufacture
If monitor wafers are reclaimed and reconditioned, then cost savings are achieved, but contamination risk increases
Solution Approach 1:
The method applies surface passivation or oxide layer growth as a preliminary step in the reconditioning process of reclaimed monitor wafers. This preliminary protective action ensures that subsequent cleaning and processing steps do not introduce contamination or damage, thereby maintaining reliability while enabling cost-effective reuse.
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 significantly reduces particle counts and surface roughness, achieving lower contamination levels and preventing metal-induced pitting, thereby improving wafer yield and reducing environmental and health concerns.
Implementation Method 1
supplying an etching solution to etch a surface of the substrate
Implementation Method 2
rinsing the substrate with an ozonated solution to passivate the surface of the substrate
Data Source
AI summary
A process/method for cleaning wafers that eliminates and/or reduces pitting caused by standard clean 1 by performing a pre-etch and then passivating the wafer surface prior to the application of the standard clean 1. The process/method may be especially useful for advanced front end of line post-CPM cleaning. In one embodiment, the invention is a method of processing a substrate comprising: a) providing at least one substrate; b) etching a surface of the substrate by applying an etching solution; c) passivating the etched surface of the substrate by applying ozone; and d) cleaning the passivated surface of the substrate by applying an aqueous solution comprising ammonium hydroxide and hydrogen peroxide.