Inverted Selectivity Remote Plasma Etch for Silicon Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing remote plasma etch processes are limited in selectivity towards various silicon-containing materials, particularly failing to selectively etch silicon-containing films with different oxygen concentrations effectively.
Innovation Solution
A method involving a remote plasma etch with inverted selectivity, where silicon-containing films with less oxygen are etched faster than those with more oxygen, using a fluorine-containing precursor like nitrogen trifluoride and optionally ammonia, to achieve conformal trimming of polysilicon and selective etching of silicon carbon nitride films while retaining silicon oxycarbide.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional remote plasma etch processes are used, then silicon oxide layers are selectively etched, but silicon-containing films cannot be etched selectively based on oxygen concentration
Solution Approach 1:
The patent inverts the conventional selectivity behavior of remote plasma etch processes. Instead of etching silicon oxide faster than silicon (conventional behavior), the process is modified to etch silicon-containing films with less oxygen faster than those with more oxygen, achieving inverted selectivity that enables new applications in polysilicon trimming and silicon carbon nitride etching
Solution Approach 2:
The patent modifies process parameters including gas composition (fluorine-containing precursor, ammonia, hydrogen), pressure, and temperature to achieve inverted selectivity. By adjusting these parameters, the etch process selectively removes silicon-containing films based on their oxygen concentration, enabling precise control over etch selectivity
2Productivity
If silicon-containing films are etched faster, then productivity increases, but silicon oxide removal cannot be avoided with conventional processes
Solution Approach 1:
The patent inverts the conventional etch selectivity to achieve oxide-deselective etching of silicon-containing films. By reversing the selectivity behavior, the process etches silicon and silicon-rich films faster while preserving silicon oxide, thereby increasing productivity without the harmful loss of oxide material
3Manufacturing precision
If conventional selective etch processes are used, then pattern transfer is achieved, but conformal trimming of polysilicon is not possible
Solution Approach 1:
The patent applies inverted selectivity to enable conformal polysilicon trimming while preserving underlying silicon oxide. This inverted approach allows precise thickness control of polysilicon layers without removing the oxide layer, achieving both manufacturing precision and process versatility
Solution Approach 2:
The process achieves local quality control by selectively etching polysilicon regions while preserving silicon oxide regions. The inverted selectivity enables different etch rates for different materials in the same structure, allowing precise local trimming of polysilicon thickness
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 enables new process flows for finer linewidth structures, allowing for selective etching of silicon-containing films without significant silicon oxide removal, and preferentially etching silicon carbon nitride over silicon oxycarbide, enhancing the versatility of etching processes.
Implementation Method 1
flowing a fluorine-containing precursor into a remote plasma region fluidly coupled to the substrate processing region while forming a plasma in the first plasma region to produce plasma effluents
Implementation Method 2
etching the silicon-containing region faster than the oxygen-and-silicon-containing region by flowing the plasma effluents into the substrate processing region
Data Source
AI summary
A method of etching patterned heterogeneous silicon-containing structures is described and includes a remote plasma etch with inverted selectivity compared to existing remote plasma etches. The methods may be used to conformally trim polysilicon while removing little or no silicon oxide. More generally, silicon-containing films containing less oxygen are removed more rapidly than silicon-containing films which contain more oxygen. Other exemplary applications include trimming silicon carbon nitride films while essentially retaining silicon oxycarbide. Applications such as these are enabled by the methods presented herein and enable new process flows. These process flows are expected to become desirable for a variety of finer linewidth structures. Methods contained herein may also be used to etch silicon-containing films faster than nitrogen-and-silicon containing films having a greater concentration of nitrogen.