Selective Nitrogen Incorporation in Semiconductor Substrates
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Solution Overview
Problem
As semiconductor devices, particularly floating gate NAND flash memory chips, scale down, manufacturers face challenges with geometry, uniformity, tolerance, and reliability due to rising aspect ratios, necessitating improved manufacturing processes.
Innovation Solution
A nitrogen-containing plasma is generated and selectively applied to silicon regions of a substrate to incorporate nitrogen, using a selective plasma nitridation process that preferentially forms Si-N bonds over Si-O bonds, enhancing the incorporation of nitrogen into silicon areas while minimizing oxide regions, through methods like high-pressure plasma and remote plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional nitridation processes are used, then nitrogen can be incorporated into silicon regions, but selectivity is poor and oxide regions are also affected
Solution Approach 1:
The patent applies parameter changes by utilizing high-pressure plasma conditions (e.g., 1-100 Torr, preferably 10-50 Torr) and specific RF power levels (e.g., 100-1000 Watts) to enhance the selectivity of nitrogen incorporation into silicon regions while minimizing oxidation of oxide regions. The high pressure promotes selective chemical reactions at silicon surfaces over oxide surfaces, resolving the contradiction between achieving nitrogen incorporation and maintaining selectivity.
Solution Approach 2:
The patent replaces conventional thermal or low-pressure plasma nitridation with high-pressure plasma processing. This substitution changes the reaction mechanism from thermal diffusion or low-pressure plasma chemistry to high-pressure plasma chemistry, where increased pressure enhances the selectivity of nitrogen incorporation into silicon while reducing unwanted oxidation reactions, thereby improving both manufacturing precision and device reliability.
2Productivity
If device dimensions are scaled down, then higher integration density is achieved, but aspect ratios increase and manufacturing uniformity deteriorates
Solution Approach 1:
The patent utilizes parameter changes by operating at high pressure (1-100 Torr) with controlled RF power to achieve uniform nitrogen incorporation across devices with high aspect ratios. The high pressure promotes more uniform plasma distribution and reaction kinetics, ensuring consistent nitrogen incorporation even in deep, narrow structures, thereby maintaining manufacturing precision despite increased integration density and aspect ratios.
3Reliability
If nitrogen incorporation is enhanced, then device performance improves, but process selectivity may deteriorate
Solution Approach 1:
The patent replaces conventional nitridation methods with high-pressure plasma processing, which fundamentally changes the reaction dynamics. The high pressure enhances nitrogen incorporation efficiency and device performance while simultaneously improving selectivity by suppressing oxidation reactions. This substitution resolves the contradiction by enabling both enhanced nitrogen incorporation and maintained process selectivity through pressure-controlled plasma chemistry.
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 improves the selectivity and uniformity of nitrogen incorporation, enhancing the reliability and performance of floating gate NAND flash memory devices by selectively forming nitrides in silicon regions, thereby addressing scaling challenges and reliability issues.
Implementation Method 1
generating a nitrogen containing plasma, exposing a surface of a substrate containing silicon regions and silicon oxide regions to the nitrogen containing plasma
Implementation Method 2
selectively incorporating nitrogen into the silicon regions of the substrate... selective plasma nitridation process that preferentially forms Si-N bonds over Si-O bonds
Data Source
AI summary
Methods and apparatus for selective one-step nitridation of semiconductor substrates is provided. Nitrogen is selectively incorporated in silicon regions of a semiconductor substrate having silicon regions and silicon oxide regions by use of a selective nitridation process. Nitrogen containing radicals may be directed toward the substrate by forming a nitrogen containing plasma and filtering or removing ions from the plasma, or a thermal nitridation process using selective precursors may be performed. A remote plasma generator may be coupled to a processing chamber, optionally including one or more ion filters, showerheads, and radical distributors, or an in situ plasma may be generated and one or more ion filters or shields disposed in the chamber between the plasma generation zone and the substrate support.