Ion Beam Milling for Uniform Semiconductor Delayering
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Solution Overview
Problem
Current methods for delayering semiconductor samples, such as wet chemical etching, dry etching, and mechanical polishing, face challenges with non-uniform removal due to variations in material density and etch rates, limiting precise control over the removal of thin layers in semiconductor devices.
Innovation Solution
The use of a broad ion beam mill system with a control system to selectively remove materials at predetermined rates, allowing for precise delayering of semiconductor samples by adjusting operating characteristics like ion beam direction and sample stage angle, ensuring uniform removal of layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet chemical etching is used to remove material from sample surface, then material removal is achieved, but non-uniform removal occurs due to varying etch rates of different materials
Solution Approach 1:
The patent replaces chemical etching processes with physical ion beam milling. The ion beam mill uses accelerated ions to physically sputter and remove material from the sample surface, eliminating the chemical reaction variability that causes non-uniform removal. This mechanical/physical approach provides consistent material removal rates across different materials.
Solution Approach 2:
The patent employs adjustable ion beam parameters including ion energy, ion flux, and beam angle to control the material removal process. By optimizing these parameters, the system achieves uniform etch rates across different materials while maintaining precise control over the delayering process.
2Manufacturing precision
If dry plasma etching is used to remove material, then material removal is achieved, but non-uniformities in material density and etch species concentration adversely affect etch rate
Solution Approach 1:
The patent replaces the complex plasma chemistry process with a simpler physical ion beam milling process. The ion beam mill directly accelerates ions onto the sample surface without requiring complex plasma generation and maintenance, eliminating the non-uniformities caused by plasma species concentration variations.
3Manufacturing precision
If mechanical polishing is used to erode sample surface, then material removal is achieved, but uneven erosion occurs due to variations in stress and feature density
Solution Approach 1:
The patent replaces manual mechanical polishing with automated ion beam milling. The ion beam mill provides uniform material removal through controlled ion bombardment, eliminating the uneven erosion caused by manual polishing variations in stress distribution and feature density.
Solution Approach 2:
The ion beam mill system is self-regulating, where the ion beam automatically adapts to the sample surface topography and material composition, providing consistent material removal without requiring manual intervention or adjustment during the process.
4Manufacturing precision
If focused ion beam is used to remove material in precise locations, then precise material removal is achieved, but milling rate is slow and large areas are difficult to modify
Solution Approach 1:
The patent segments the ion beam into multiple parallel beams or uses a broad beam that can be scanned across the sample surface. This allows simultaneous processing of multiple locations or large areas while maintaining the precision of material removal at each location, thereby increasing overall productivity.
Solution Approach 2:
The patent transitions from a narrow focused beam to a broad beam configuration, adding the dimension of beam width. This allows the system to process large areas efficiently while maintaining precision through controlled beam scanning or parallel beam structures.
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 precise and uniform delayering of semiconductor samples, maintaining the integrity of underlying circuitry and allowing for the exposure of underlying layers across the entire surface, improving the accuracy and consistency of semiconductor fabrication processes.
Implementation Method 1
Reactive ions cause both chemical reactions on a sample and physical bombardment, thereby removing material from the sample
Implementation Method 2
physical bombardment, thereby eroding (knocking-off) the sample
Data Source
AI summary
There is provided a method, system and computer program product to delayer a layer of a sample, the layer comprising one or more materials, in an ion beam mill by adjusting one or more operating parameters of the ion beam mill and selectively removing each of the one or more materials at their respective predetermined rates. There is also provided a method and system for obtaining rate of removal of a material from a sample in an ion beam mill.