Angled Gas Cluster Ion Beam Removal in Small Pitch Metal Structures
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Solution Overview
Problem
The challenge of removing metal-containing materials from small pitch structures in semiconductor devices, particularly those with high aspect ratios and narrow dimensions, leads to issues such as uneven deposition, structural deformation, and poor electrical conductivity due to the difficulty in controlling etching processes.
Innovation Solution
Employing a gas cluster ion beam (GCIB) at an irradiation angle between 5° to 85° relative to the substrate surface to selectively remove undesired metal-containing materials from the top and sidewalls of recesses while preserving the integrity of the metal layers at the bottom, followed by controlled etching to ensure uniform deposition of interconnect metals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used to remove metal-containing materials from small pitch structures, then the etching process can be performed, but uneven deposition and structural deformation occur due to difficulty in controlling the etching process
Solution Approach 1:
The patent changes the fundamental parameters of the etching process by using gas cluster ion beams instead of conventional plasma etching. This involves changing the ion source, beam energy, and irradiation angle parameters to achieve selective removal of metal-containing materials while preserving the structural integrity of small pitch structures with high aspect ratios
Solution Approach 2:
The patent replaces the chemical-mechanical etching process with a physical ion beam process. The gas cluster ion beam uses physical sputtering and knock-on displacement mechanisms to remove material, substituting the chemical reactions and physical sputtering of conventional plasma etching with a more controllable ion beam mechanism that better preserves structural integrity
2Quantity of substance
If metal-containing materials are deposited in recesses with high aspect ratios, then the recesses can be filled, but uneven deposition occurs making it difficult to control the etching process
Solution Approach 1:
The patent applies local quality by using angled ion beam irradiation that selectively removes material from specific regions (sidewalls and top surface) while preserving material at the bottom of recesses. This creates a non-uniform etching profile that compensates for the uneven deposition, ensuring uniform metal layer thickness at the bottom where it is most needed for electrical connectivity
Solution Approach 2:
The patent performs preliminary action by removing undesired metal-containing materials from the sidewalls and top surfaces before final metal deposition. This pre-processing step creates optimized recess geometries that enable subsequent uniform metal deposition and prevent future etching control issues
3Productivity
If the etching process is made more aggressive to remove metal-containing materials, then material removal efficiency increases, but structural deformation and loss of electrical conductivity occur
Solution Approach 1:
The patent applies partial action by using ion beam irradiation at controlled angles and energies to remove only the undesired portions of metal-containing materials from sidewalls and top surfaces, while deliberately preserving the metal layers at the bottom of recesses. This selective removal achieves sufficient material removal efficiency without excessive etching that would damage the conductive pathways and reduce electrical conductivity
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 method prevents structural deformation and ensures uniform metal deposition, maintaining electrical conductivity and preventing voids, thereby enhancing the reliability and performance of semiconductor devices.
Implementation Method 1
a gas cluster ion beam is directed at a major surface plane of a substrate with a first irradiation angle, alpha, between the gas cluster ion beam and the major surface plane of from 5° to 85° to remove at least a portion of undesired metal-containing material
Implementation Method 2
GCIB processes can enhance a patterned layer by smoothing the surfaces of features by trimming random protrusions from exposed surfaces using a gas cluster ion beam
Data Source
AI summary
Undesired metal-containing material is removed from semiconductor substrates during fabrication of features in semiconductor devices in a method where at least a portion of the metal-containing material is removed from the semiconductor substrate by directing a gas cluster ion beam at the material at an irradiation angle α between the gas cluster ion beam and the major surface plane of from 5° to 85°. Various techniques of directing a gas cluster ion beam at the semiconductor substrate are described.