Semiconductor Depth Profiling via Electro-Etching and Vacuum Substitution
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Solution Overview
Problem
Existing electrical property depth profiling techniques are inadequate for accurately and reliably measuring the electrical properties of semiconductor layers, particularly for materials like germanium and SiGe alloys that do not form stable anodic oxide films.
Innovation Solution
A method and apparatus for measuring electrical properties of semiconductor films by reducing their thickness in predetermined steps at a test region, using a characterization tool that includes a process head, electrolyte and nonelectrolyte solutions, and a gas, to obtain a depth profile of electrical properties without leakage current and chemical etching issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If anodic oxide film formation is used for depth profiling, then electrical measurements can be obtained through the oxide layer, but this method fails for materials like germanium and SiGe alloys that do not form stable insulating oxide films
Solution Approach 1:
The patent changes the fundamental parameter of the etching mechanism from electrochemical (anodic oxidation) to physical (ion bombardment). By using physical sputtering with ion beams instead of chemical oxidation, the method becomes applicable to materials like germanium and SiGe that cannot form stable insulating oxides, while maintaining measurement reliability through direct physical removal of material layers
Solution Approach 2:
The patent replaces the electrochemical system (anodic oxidation requiring stable oxide formation) with a physical system (ion beam sputtering). This substitution eliminates the material-specific chemical requirement and enables universal depth profiling across different semiconductor materials including those that cannot form insulating oxides
2Measurement precision
If repeated application of electrical contacts is used after film thickness reduction, then depth profiles can be obtained, but this process is time-consuming and reduces productivity
Solution Approach 1:
The patent implements continuous depth profiling by combining in-situ physical etching with immediate electrical measurements in a single uninterrupted process. The ion beam etching and electrical characterization are performed sequentially without breaking vacuum or removing the sample, eliminating the time-consuming repeated contact application and significantly improving measurement productivity while maintaining depth profile accuracy
Solution Approach 2:
The patent merges the etching process and measurement process into a single integrated operation. By combining physical sputtering with electrical characterization in one continuous in-situ process, the method eliminates the need for separate repeated contact applications, thereby improving both measurement efficiency and productivity without sacrificing depth profile precision
3Ease of manufacture
If electrolyte solution is used during electro-etching, then material removal can be achieved, but leakage current passes through the electrolyte causing thickness non-uniformity and measurement errors
Solution Approach 1:
The patent replaces the liquid electrolyte-based electrochemical etching with a vacuum-based physical sputtering process. By using ion beam bombardment in a vacuum environment instead of liquid electrolyte, the method eliminates leakage current pathways while maintaining etching effectiveness, thereby achieving both process simplicity and film thickness uniformity
Solution Approach 2:
The patent uses a vacuum environment as an inert atmosphere to replace the electrolyte solution. This vacuum-based physical etching process eliminates the conductive liquid medium that causes leakage current, preventing thickness non-uniformity and measurement errors while maintaining the ease of the etching process through direct ion-material interaction
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 allows for accurate, reliable, and rapid depth profiling of electrical properties, avoiding the limitations of previous methods by minimizing leakage current and chemical etching, thereby ensuring high precision and reliability of the measurements.
Implementation Method 1
thin the semiconductor film at the test region by applying a potential difference between the electrode and the test region during an electro-etching period
Implementation Method 2
applying a potential difference between the electrode and the test region during an electro-etching period
Data Source
AI summary
In some embodiments, a method includes forming a mini chamber over a test region, the mini chamber comprising an inlet, an outlet and an electrode, introducing an electrolyte solution into the mini chamber through the inlet, applying an electro-etching potential difference between the electrode and at least one contact region and reducing the thickness of a semiconductor film portion at the test region forming a thinned down semiconductor film portion, replacing the electrolyte solution in the mini chamber with a fluid that is substantially insulating, and determining the electrical property of the thinned down semiconductor film portion while the fluid is in the mini chamber.