Silicon Wafer Gate Oxide Breakthrough via RTA and BMD Control
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Solution Overview
Problem
Existing semiconductor wafers composed of single-crystal silicon do not fully meet the requirements for producing electronic components with NAND logic, particularly in terms of electrical breakdown resistance and thermal budget constraints.
Innovation Solution
A semiconductor wafer with a denuded zone extending at least 20 μm deep and a region with nuclei that can be developed into bulk microdefects (BMDs) with a peak density of not less than 6.0×10^9/cm^3, achieved through a process involving CZ method growth, RTA treatments in different atmospheres, and heat treatments in nitrogen-oxygen atmospheres to control oxygen concentration and vacancy density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single crystal of silicon is grown by the CZ method with regulated drawing speed and axial temperature gradient to form a neutral region, then the concentration of interstitial silicon atoms and vacancies is controlled below the defect formation threshold, but the resulting semiconductor wafer does not completely meet the requirements for producing electronic components with NAND logic, particularly in terms of electrical breakdown resistance and BMD density
Solution Approach 1:
The patent applies preliminary action by performing RTA treatments and heat treatments before the final device fabrication to pre-establish the desired vacancy distribution and BMD nuclei configuration. The sem wafers are subjected to RTA treatment in oxidizing atmosphere followed by nitriding atmosphere, and then heat treatment in nitrogen-oxygen atmosphere to pre-form the required structural characteristics (denuded zone with low vacancy density and inner region with BMD nuclei) before actual device manufacturing begins
Solution Approach 2:
The patent employs parameter changes by systematically varying temperature, atmosphere composition, and treatment duration to transform the silicon wafer properties. Specifically, RTA treatment uses temperatures of 900-1100°C in oxidizing then nitriding atmospheres, followed by heat treatment at 800-1000°C in nitrogen-oxygen atmosphere for extended periods (16-48 hours). These parameter variations enable precise control over oxygen concentration (4.5×10^17 to 5.5×10^17 atoms/cm³) and vacancy density distribution, achieving both high electrical breakdown resistance and sufficient BMD peak density (≥6.0×10^9/cm³)
2Manufacturing precision
If the semiconductor wafer is subjected to extensive heat treatment to develop high density BMDs, then the BMD peak density increases to at least 6.0×10^9/cm^3, but the thermal budget increases which may conflict with manufacturing constraints
Solution Approach 1:
The patent applies preliminary action by performing RTA treatments and heat treatments before the final device fabrication to pre-establish the desired vacancy distribution and BMD nuclei configuration. The sem wafers are subjected to RTA treatment in oxidizing atmosphere followed by nitriding atmosphere, and then heat treatment in nitrogen-oxygen atmosphere to pre-form the required structural characteristics (denuded zone with low vacancy density and inner region with BMD nuclei) before actual device manufacturing begins
Solution Approach 2:
The patent employs parameter changes by systematically varying temperature, atmosphere composition, and treatment duration to transform the silicon wafer properties. Specifically, RTA treatment uses temperatures of 900-1100°C in oxidizing then nitriding atmospheres, followed by heat treatment at 800-1000°C in nitrogen-oxygen atmosphere for extended periods (16-48 hours). These parameter variations enable precise control over oxygen concentration (4.5×10^17 to 5.5×10^17 atoms/cm³) and vacancy density distribution, achieving both high electrical breakdown resistance and sufficient BMD peak density (≥6.0×10^9/cm³)
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 solution provides a semiconductor wafer with high electrical breakdown resistance of the gate oxide and the ability to form a high density of BMDs, suitable for producing electronic components with NAND logic under small thermal budgets, while maintaining low vacancy density and controlling oxygen precipitate formation.
Implementation Method 1
a single crystal of silicon is grown by the CZ method
Implementation Method 2
the axial temperature gradient G at the interface between the single crystal and the melt
Implementation Method 3
an RTA (rapid thermal anneal) treatment of the semiconductor wafer in an oxidizing atmosphere
Implementation Method 4
heating the semiconductor wafer to a temperature of 800° C. over a period of four hours and to a temperature of 1000° C. over a period of 16 hours
Implementation Method 5
nuclei which can be developed by means of a heat treatment into BMDs (bulk micro defects)
Data Source
AI summary
Semiconductor wafers useful for NAND circuitry and having a front side, a rear side, a middle and a periphery, have an Nv region which extends from the middle to the periphery;a denuded zone which extends from the front side to a depth of not less than 20 μm into the interior of the semiconductor wafer, where the density of vacancies in the denuded zone, determined by means of platinum diffusion and DLTS is not more than 1×1013 vacancies/cm3;a concentration of oxygen of not less than 4.5×1017 atoms/cm3 and not more than 5.5×1017 atoms/cm3;a region in the interior of the semiconductor wafer which adjoins the denuded zone and has nuclei which can be developed by means of a heat treatment into BMDs having a peak density of not less than 6.0×109/cm3, where the heat treatment comprises heating the semiconductor wafer to a temperature of 800° C. over a period of four hours and to a temperature of 1000° C. over a period of 16 hours. The wafers are produced by a unique RTA treatment of Nv wafers.