Gas Phase Etching of Low-Resistance Boron-Doped Silicon Wafers
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Solution Overview
Problem
Low-resistance boron-doped p-type silicon wafers with resistivity of 0.016 Ωcm or less exhibit a low recovery rate of recovery liquid after gas phase etching, leading to decreased recovery of metal components and reduced reliability in evaluating metal contamination.
Innovation Solution
A gas phase etching method using an ozone-containing gas and hydrofluoric acid mist, with the ozone concentration between 0.5% to 3.5 mass % and hydrofluoric acid concentration of 41% or more, introduced at specific flow rates to improve the recovery rate of the recovery liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gas phase etching is performed on low-resistance boron-doped p-type silicon wafers (resistivity ≤0.016 Ωcm), then the surface layer area can be decomposed for metal contamination evaluation, but the recovery rate of recovery liquid decreases leading to low recovery of metal components
Solution Approach 1:
The patent changes the chemical parameters of the etching gas by introducing ozone-containing gas (0.5-3.5 mass% concentration) and hydrofluoric acid mist (41 mass% or more concentration) at specific flow rates. This parameter modification transforms the etching chemistry to improve recovery liquid recovery rate while maintaining metal contamination evaluation capability for low-resistance silicon wafers
Solution Approach 2:
The patent introduces ozone as an intermediary substance that modifies the etching process. The ozone-containing gas acts as a mediator between the hydrofluoric acid mist and the silicon wafer surface, enabling effective etching with improved recovery liquid recovery rate for low-resistance boron-doped wafers
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 enhances the recovery rate of the recovery liquid and metal components from the surface of low-resistance boron-doped p-type silicon wafers, improving the reliability of metal contamination evaluation and enabling effective process management for reduced contamination in semiconductor manufacturing.
Implementation Method 1
a method in which an etching gas is brought into contact with a surface of a silicon wafer, and the surface layer area is gas-phase decomposed and etched (gas phase etching)
Implementation Method 2
preparing an etching gas by introducing an ozone-containing gas and hydrofluoric acid mist into a chamber and mixing them
Implementation Method 3
performing gas phase decomposition of a surface layer area of the boron-doped p-type silicon wafer with the resistivity of 0.016 Ωcm or less by bringing the etching gas into contact with the surface of the boron-doped p-type silicon wafer
Data Source
AI summary
The method of etching a boron-doped p-type silicon wafer includes preparing an etching gas by introducing an ozone-containing gas and hydrofluoric acid mist into a chamber and mixing them; and performing gas phase decomposition of a surface layer area of a boron-doped p-type silicon wafer with a resistivity of 0.016 Ωcm or less by bringing the etching gas into contact with a surface of the boron-doped p-type silicon wafer; and further includes introducing the ozone-containing gas into the chamber at a flow rate of 3,000 sccm or more; and preparing the hydrofluoric acid mist by atomizing hydrofluoric acid with a hydrofluoric acid concentration of 41 mass % or more.