Buffered Oxide Etchant Hydrogen Fluoride Measurement
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Solution Overview
Problem
The manufacturing of micro-electronic components faces challenges in accurately detecting and measuring Hydrogen Fluoride (HF) concentrations in buffered oxide etchants due to its toxicity, reactivity, and the complexity of equilibrium mechanisms, leading to dosage errors and inefficiencies in etching processes.
Innovation Solution
A method involving the collection of a representative sample of the buffered oxide etchant, addition of a chromogenic agent, and subsequent spectrometric measurement to determine HF concentration, allowing for precise measurement and adjustment of etch rates during the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If HF bearing mixtures are used for etching, then isotropic etching of silicon is achieved, but measurement precision of HF concentration deteriorates due to toxicity and reactivity
Solution Approach 1:
The patent uses an intermediary chemical reaction system where HF in the etchant reacts with a standard buffer solution to form a predictable pH change. This intermediary step converts the difficult-to-measure HF concentration into a measurable pH value, which can then be quantified using standard pH meters or indicators, thereby solving the measurement precision problem while maintaining etching precision
Solution Approach 2:
The patent transforms the measurement parameter from direct HF concentration measurement to pH measurement. By changing the measurement parameter to something that is not affected by HF's toxicity and reactivity issues, accurate concentration determination becomes feasible through standard pH measurement techniques
2Difficulty of detecting and measuring
If common industry analytical methods are used for HF measurement, then measurement capability is available, but reliability deteriorates due to complex equilibrium mechanisms and toxicity
Solution Approach 1:
The patent introduces a buffer solution as an intermediary that reacts with HF to produce a stable, measurable pH change. This intermediary approach bypasses the complex equilibrium mechanisms of direct HF measurement and eliminates toxicity concerns, as the pH measurement occurs in a controlled buffer environment rather than directly in the toxic HF etchant
Solution Approach 2:
The patent replaces complex chemical analysis methods with a simpler pH measurement system. Instead of using sophisticated analytical instruments to directly measure HF concentration, the invention substitutes this with a straightforward pH measurement of the buffer solution, which is more reliable and easier to implement
3Adaptability or versatility
If HF containing BOE compositions are mixed to obtain desired dosage concentration, then dosage flexibility is improved, but manufacturing precision deteriorates due to loss of exact concentration knowledge
Solution Approach 1:
The patent implements a feedback mechanism where the pH of the mixed etchant solution is measured and used to determine the actual HF concentration. This feedback allows operators to verify the concentration after mixing different compositions, ensuring that the desired dosage precision is achieved regardless of the mixing process, thereby maintaining manufacturing precision while preserving dosage flexibility
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 method enables accurate detection and measurement of HF concentrations, ensuring precise control over etching processes, reducing errors and inefficiencies, and allowing for the use of mixed HF concentrations, thereby improving manufacturing efficiency and product quality.
Implementation Method 1
adding a chromogenic agent to the composition, performing a spectrometric measurement of the composition
Implementation Method 2
performing a spectrometric measurement of the composition, comparing the spectrometric measurement to pre-determined values to identify the quantity of HF
Data Source
AI summary
The invention is directed towards methods and compositions for identifying the amount of hydrofluoric acid in a buffered oxide etching composition. In buffered oxide etching compositions it is very difficult to measure the amount of hydrofluoric acid because it has varying equilibriums and it is toxic so it hard to handle and sample. When used to manufacture microchips however, incorrect amounts of hydrofluoric acid will ruin those chips. The invention utilizes a unique method of spectrographically measuring the hydrofluoric acid when in contact with added chromogenic agents to obtain exact measurements that are accurate, immediate, and safe.