Selective Atomic Layer Etching Using Halogen Precursors
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Solution Overview
Problem
Conventional etching processes face challenges in achieving high selectivity and uniformity, particularly for silicon and metal-containing materials, with issues such as low selectivity, crystallographic etching, and substrate damage from plasma-based methods.
Innovation Solution
The use of halogen-containing precursors, such as xenon difluoride, is employed to form a film on semiconductor and metal-containing materials, allowing for atomic or molecular layer etching with high selectivity and isotropic etching from all crystal planes, while avoiding plasma contact to prevent substrate damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If wet etching is used to remove exposed material, then etching speed is improved, but selectivity between different materials deteriorates and deformation of remaining material occurs
Solution Approach 1:
The invention changes the chemical parameters of the etching process by using halogen-containing precursors (such as XeF2, CF4, SF6) that provide high etching speed while maintaining selectivity. The specific chemical composition and reaction conditions are optimized to achieve both fast etching and precise material differentiation.
Solution Approach 2:
The invention replaces conventional wet chemical etching with a vapor-phase halogen-based etching process. This substitution eliminates the need for liquid chemicals that cause deformation, using instead volatile halogen compounds that provide controlled, deformation-free etching with high selectivity.
2Productivity
If dry etching with local plasma is used to penetrate constrained trenches, then etching capability is improved, but substrate damage from electric arcs occurs
Solution Approach 1:
The invention converts the potentially harmful plasma process into a beneficial controlled vapor-phase reaction. By using halogen-containing precursors in vapor form rather than as plasma, the process eliminates electric arc damage while maintaining the ability to penetrate constrained trenches through controlled chemical reactions.
Solution Approach 2:
The invention uses an inert or controlled atmosphere with halogen-containing precursors that do not create electric arcs. The vapor-phase environment provides a safe, controlled reaction zone that eliminates the harmful electrical discharges associated with plasma-based methods while maintaining etching effectiveness.
3Productivity
If conventional etching is used for pattern transfer, then material removal is achieved, but uniformity and profile control deteriorate
Solution Approach 1:
The invention employs a cyclic process where halogen-containing precursors are introduced, allowed to react and form volatile products, then removed. This periodic introduction and removal of reactants enables precise control over etching depth and profile uniformity while maintaining high material removal efficiency through repeated cycles.
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 highly selective and uniform etching of semiconductor and metal-containing materials, allowing for precise control of etched thickness and profile uniformity, with the potential for reusing etch byproducts, thus improving semiconductor processing efficiency and reducing substrate damage.
Implementation Method 1
contacting an exposed region of a semiconductor material with the halogen-containing precursor such that the halogen-containing precursor is adsorbed on a surface of the exposed region of the semiconductor material
Implementation Method 2
The adsorbed halogen-containing precursor may produce a fluoride of the semiconductor material
Data Source
AI summary
Precursors, such as interhalogens and/or compounds formed of noble gases and halogens, may be supplied in a gaseous form to a semiconductor processing chamber at a predetermined amount, flow rate, pressure, and/or temperature in a cyclic manner such that atomic layer etching of select semiconductor materials may be achieved in each cycle. In the etching process, the element of the precursor that has a relatively higher electronegativity may react with select semiconductor materials to form volatile etching byproducts. The element of the precursor that has a relatively lower electronegativity may form a gas that may be recycled to re-form an precursor with one or more halogen-containing materials using a plasma process.