Semiconductor Etching Cycles for High SiGe Selectivity
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Solution Overview
Problem
Current chemical dry etching techniques face challenges with low etch selectivity, limited lateral etching capability, and defects in semiconductor manufacturing, particularly when dealing with silicon germanium (SiGe) etching, due to high energy ion bombardment and non-uniform by-product accumulation.
Innovation Solution
The Fast Assess Cyclic Switching (FACS) technique is introduced, which shortens the etching duration per cycle to less than 1 second, utilizing incubation time engineering and specific etching chemistries to achieve high and reversible etching selectivity, and improve profile decoration by controlling the duration of the main etch between the incubation times of different material species.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high energy ion bombardment is used for physical etching, then etching speed is improved, but etch selectivity deteriorates and defects are generated
Solution Approach 1:
The patent implements periodic switching between chemical etching mode (for high selectivity) and physical etching mode (for high speed) within a single etching chamber. The system alternates between these two modes during the etching process, allowing it to achieve both high etch selectivity during chemical phases and high etching speed during physical phases, thereby resolving the contradiction between productivity and manufacturing precision
Solution Approach 2:
The patent changes the operational parameters of the etching chamber by adjusting plasma power, gas flow rates, and pressure conditions to switch between chemical-dominated and physical-dominated etching modes. By dynamically modifying these parameters, the system can optimize for either selectivity or speed as needed, resolving the trade-off between etch selectivity and etching speed
2Manufacturing precision
If chemical reaction is used for etching, then etch selectivity is improved, but etching speed deteriorates
Solution Approach 1:
The system employs periodic action by alternating between chemical etching phases (which provide high selectivity) and physical etching phases (which provide high speed). This cyclic switching allows the process to accumulate the benefits of both mechanisms over time, achieving high overall etching speed while maintaining high selectivity through the repeated chemical phases
Solution Approach 2:
The patent merges chemical dry etching and physical dry etching into a single integrated process within one chamber. By combining both etching mechanisms and allowing them to work in sequence, the system achieves the high selectivity of chemical etching and the high speed of physical etching, resolving the contradiction between manufacturing precision and productivity
3Length of moving object
If long etching duration is used, then etching depth is improved, but by-product accumulation increases causing non-uniformity
Solution Approach 1:
The patent applies periodic action by interrupting continuous etching with regular pumping phases that remove by-products from the chamber. This periodic removal of reaction by-products prevents their accumulation on the substrate surface, maintaining profile uniformity even during deep etching operations over extended durations
Solution Approach 2:
The system maintains continuous useful action by immediately resuming etching after each pumping phase, ensuring that the etching process continues without significant interruption. The brief pumping intervals are used to remove by-products while minimizing loss of etching progress, thus maintaining both etching depth and profile uniformity
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
FACS enables significant advancements in etching selectivity and profile control, reducing defects and improving semiconductor structure quality by allowing precise control over etching processes, enhancing the yield and performance of semiconductor manufacturing.
Implementation Method 1
chemical component uses a chemical reaction between etchant gases and the surface material
Implementation Method 2
Products of the chemical reaction may be subsequently removed from the etching chamber
Implementation Method 3
Physical component requires high kinetic energy particle or ion beams to bombard surface atoms. When the high energy particles knock out the atoms from the surface, the material turns into gaseous phase
Implementation Method 4
In dry etching, plasmas or etchant gases remove the material on the substrate
Data Source
AI summary
A technique for semiconductor manufacturing is provided. The technique includes the operations as follows. A semiconductor structure having a first material is received. A plurality of first main etches are performed to the semiconductor structure for a plurality of first durations under the first etching chemistry. A plurality of pumping operations are performed for a plurality of pumping durations, each of the pumping operations being prior to each of the first main etches. Each of the first durations is in a range of from about 1 second to about 2.5 seconds.