GAA Nanosheet Channel Cleaning for Precise Inner Spacer Etching
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving precise patterning and etching of gate all around (GAA) transistor structures, particularly in forming nanosheet profiles and inner spacers, which affect the performance and efficiency of semiconductor devices.
Innovation Solution
A method involving hydrogen radical treatment and surface cleaning processes is employed to remove oxygen impurities and native oxides from semiconductor layers, followed by selective chemical dry etching to create precise recesses in the first semiconductor layers, while preserving the integrity of the second semiconductor layers, using a processing tool that controls temperature, pressure, and gas mixtures to enhance etching selectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to pattern GAA transistor structures, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to inability to achieve precise nanosheet profiles and inner spacer formation
Solution Approach 1:
The manufacturing process is divided into multiple sequential steps: hydrogen radical treatment to remove oxygen impurities, surface cleaning to remove native oxides, and selective chemical dry etching to create precise recesses. Each step targets a specific cleaning or etching function, enabling precise control over the nanosheet profiles and inner spacer formation that cannot be achieved with conventional single-step etching processes.
Solution Approach 2:
Hydrogen radical treatment and surface cleaning processes are performed before the selective chemical dry etching to remove oxygen impurities and native oxides from the semiconductor layers. This preliminary action prepares the surface for precise etching by eliminating contaminants that would otherwise interfere with the etching selectivity and precision of the subsequent chemical etching step.
2Manufacturing precision
If oxygen impurities and native oxides are present on semiconductor layers, then manufacturing simplicity is maintained, but manufacturing precision deteriorates due to interference with etching selectivity
Solution Approach 1:
Hydrogen radicals are used to convert the harmful oxygen impurities and native oxides into water molecules that can be easily removed. The hydrogen radicals react with oxygen-containing compounds to form volatile products, transforming the harmful oxygen contamination into a beneficial cleaning effect that enables subsequent precise etching.
Solution Approach 2:
Hydrogen radicals serve as an intermediary substance that facilitates the removal of oxygen impurities and native oxides. The hydrogen radicals mediate between the oxygen-containing contaminants and the etching process, reacting with them to form removable compounds and enabling the selective chemical etching to proceed with high precision.
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 method improves the precision of GAA transistor structures by effectively removing oxygen impurities and native oxides, ensuring accurate etching and enhancing the performance and efficiency of semiconductor devices.
Implementation Method 1
hydrogen radical treatment and surface cleaning processes is employed to remove oxygen impurities
Implementation Method 2
selective chemical dry etching to create precise recesses in the first semiconductor layers
Data Source
AI summary
A method includes forming a dummy gate structure over a semiconductor structure over a substrate. Gate spacers are formed on sidewalls of the dummy gate structure. The semiconductor structure is recessed to form recesses on opposite sides of the dummy gate structure. A channel portion of the semiconductor structure remains beneath the dummy gate structure. A first oxygen-removal process is performed to the channel portion, using hydrogen radicals, to remove oxygens in the channel portion. A second oxygen-removal process, using a hydrogen-containing gas mixture, is performed to remove an oxide layer formed on sidewalls of the channel portion. The hydrogen radicals used in the first oxygen-removal process have sizes smaller than the hydrogen-containing gas mixture used in the second oxygen-removal process. Source/drain structures are deposited in the recesses and connected to the channel portion. The dummy gate structure is replaced with a metal gate structure.