COP Removal from Silicon Wafers via Surface Area Expansion
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Solution Overview
Problem
Semiconductor devices, particularly those like JFET, MOSFET, and IGBT, face issues with crystal originated particles (COPs) formed during Czochralski silicon wafer growth, leading to enhanced leakage current and weakened gate dielectrics due to defects such as D-defects and COPs, which are challenging to remove effectively.
Innovation Solution
A method involving increasing the surface area of crystalline silicon bodies by forming polysilicon layers, porous layers, or using laser irradiation, followed by oxidation at high temperatures to generate interstitial silicon atoms that dissolve COPs, thereby reducing their concentration and improving device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If Czochralski method is used for single-crystal growth, then large silicon wafers (12" and above) can be produced, but crystal originated particles (COPs) and dislocation loops are formed
Solution Approach 1:
The invention segments the removal process into multiple steps: first increasing surface area through mechanical or chemical means, then performing oxidation to remove COPs. This segmentation allows effective COP removal while preserving the large wafer size capability of the Czochralski method.
Solution Approach 2:
The invention performs preliminary action by increasing the surface area of the silicon wafer before the oxidation step. This preliminary surface modification enables more effective COP removal during subsequent oxidation, addressing the crystal quality issue before device fabrication begins.
2Reliability
If oxidation is performed at high temperature for long duration, then COPs are effectively removed, but processing time and energy consumption increase
Solution Approach 1:
The invention performs preliminary surface area enhancement before oxidation, which accelerates the subsequent oxidation process. This allows effective COP removal in shorter time and at lower temperatures compared to direct oxidation of flat surfaces.
Solution Approach 2:
The invention changes the surface area parameter before oxidation, creating a more reactive surface that undergoes oxidation faster and at lower temperatures. This parameter modification resolves the contradiction between removal efficiency and processing time/energy consumption.
3Productivity
If surface area is increased to enhance COP removal, then oxidation efficiency improves, but additional processing steps are required
Solution Approach 1:
The invention merges the surface area enhancement step with subsequent processing steps. The surface modification is performed as a preliminary treatment that integrates well with existing fabrication processes, minimizing additional complexity while maximizing COP removal efficiency.
Solution Approach 2:
The surface area enhancement method is designed to be universal and compatible with various subsequent processing steps. The modified surface structure serves multiple purposes: enhancing oxidation efficiency and providing a foundation for subsequent device fabrication steps.
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 effectively reduces COPs, enhancing the integrity of gate dielectrics and minimizing leakage current, thereby improving the reliability and efficiency of semiconductor devices.
Implementation Method 1
oxidizing the increased surface area at a temperature of at least 1000° C. and for a duration of at least 20 minutes
Implementation Method 2
generate interstitial silicon atoms that dissolve COPs
Data Source
AI summary
A method for removing crystal originated particles from a crystalline silicon body having opposite first and second surfaces includes: increasing a surface area of at least one of the first and second surfaces by an etch process; and oxidizing the increased surface area at a temperature of at least 1000° C. and for a duration of at least 20 minutes.