Tilted Ion Beam Etching for Symmetric GAA Gate Cavity Widening
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Solution Overview
Problem
The semiconductor industry faces challenges in fabricating three-dimensional designs like gate all around (GAA) transistors, particularly in widening the gate cavity for metal replacement gates, due to limitations in existing ion beam processing techniques which result in pitch walking and etch asymmetry issues.
Innovation Solution
An ion beam processing tool with a plasma source, grid arrangement, and a beam deflector is used to generate a tilted ion beam for directional etching, allowing for a more flexible process window by selectively removing sidewall portions of spacers, thereby widening the gate cavity and reducing capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional ion beam processing techniques are used for material removal, then the etching process can be performed, but pitch walking and etch asymmetry issues occur
Solution Approach 1:
The patent applies asymmetry by introducing a beam deflector that creates a tilted ion beam angle (e.g., 5-15 degrees) relative to the substrate normal. This asymmetric beam incidence angle compensates for the symmetric pitch walking and etch asymmetry problems, enabling precise control of material removal while maintaining process flexibility for gate cavity widening operations
2Adaptability or versatility
If the gate cavity is widened for metal replacement gates, then the process window for gate formation increases, but existing techniques cannot achieve the required precision
Solution Approach 1:
The patent employs dynamics by making the ion beam angle adjustable and controllable through the beam deflector system. The tilted beam angle can be dynamically modified during the etching process to precisely control gate cavity dimensions, enabling flexible gate formation with high manufacturing precision that accommodates various device design requirements
3Manufacturing precision
If tilted ion beam etching is used to remove sidewall portions of spacers, then pitch walking and etch asymmetry are reduced, but additional equipment complexity is introduced
Solution Approach 1:
The patent introduces a beam deflector as an intermediary component between the ion beam source and the substrate. This mediator device tilts the ion beam angle to improve material removal precision and reduce pitch walking, while isolating the complexity of angle control from the core etching process, thereby achieving high precision with manageable equipment complexity
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 tilted ion beam etching process enhances the flexibility of forming metal replacement gates by reducing pitch walking and etch asymmetry, improving the fabrication of GAA transistors and increasing the process window for gate formation.
Implementation Method 1
A plasma source and a grid arrangement positioned proximate the plasma source to generate an ion beam
Implementation Method 2
A plasma source and a grid arrangement positioned proximate the plasma source to generate an ion beam
Implementation Method 3
A beam deflector positioned adjacent the grid arrangement to deflect the ion beam to facilitate a tilted material removal process
Data Source
AI summary
An ion beam processing tool includes a plasma source, a grid arrangement positioned proximate the plasma source to generate an ion beam, a beam deflector positioned adjacent the grid arrangement, and a controller configured to control the beam deflector to deflect the ion beam to generate a tilted ion beam. A method includes generating an ion beam, directing the ion beam at a target, deflecting the ion beam in a first direction to remove a first portion of material from the target, and deflecting the ion beam in a second direction different than the first direction to remove a second portion of material from the target.