Microstructured Ion Energy Filter for Precise Wafer Doping
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Solution Overview
Problem
Existing energy filters for ion implantation in substrates are mechanically vulnerable and require a thick support layer, leading to increased primary ion energy and non-uniform dopant depth distribution.
Innovation Solution
A microstructured energy filter with multiple layers and cavities, featuring partition walls and column-shaped structural elements, designed to operate with minimal primary ion energy, ensuring mechanical stability and precise dopant depth distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a microstructured membrane is used as an energy filter, then the dopant depth profile can be precisely controlled, but the mechanical stability deteriorates
Solution Approach 1:
The energy filter is divided into multiple discrete layers (first layer, second layer, third layer, etc.) with cavities between them. Each layer can be independently optimized for thickness and material composition, allowing precise control of ion energy modulation while distributing mechanical stresses across multiple segments rather than a single vulnerable membrane.
Solution Approach 2:
The energy filter employs composite structure with different layers potentially made of different materials (e.g., silicon nitride, silicon dioxide, silicon carbide). This allows combining materials with different properties - some layers optimized for ion interaction precision, others for mechanical strength and stability, achieving both precise dopant depth control and robust mechanical performance.
2Strength
If a thick support layer is added to increase mechanical stability, then the primary ion energy increases due to braking properties
Solution Approach 1:
Instead of a single thick support layer, the structure uses multiple thin layers separated by cavities. The support function is distributed across several thin layers rather than concentrated in one thick layer, reducing the total material thickness that ions must traverse while maintaining mechanical stability through the distributed architecture.
Solution Approach 2:
The energy filter incorporates cavities (porous spaces) between layers that reduce the effective material density and thickness in the ion path. These void spaces allow ions to pass through with minimal braking while the surrounding structural framework maintains mechanical integrity, achieving low energy loss without sacrificing strength.
3Area of stationary object
If the energy filter area is increased for larger substrates, then the mechanical vulnerability increases
Solution Approach 1:
The large-area energy filter is segmented into multiple layers and cavities arranged in a modular fashion. This segmentation creates a grid-like structural framework that provides mechanical support across the entire large area, preventing the membrane from becoming vulnerable despite the increased dimensions required for larger substrate wafers.
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 solution provides improved mechanical stability, allows for larger substrate diameters, and achieves uniform and precise dopant depth profiles with reduced contamination, while maintaining low primary ion energy.
Implementation Method 1
The invariably structured, monoenergetic ion beam is modulated in energy as a function of the point of entry into the substrate when it passes through the microstructured energy filter
Data Source
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Figure 3(a)~3(d)
AI summary
The invention relates to an energy filter (20) for use in the implantation of ions into a substrate (12), which energy filter is microstructured in order to set a doping-material depth profile and/or a defect depth profile in the substrate (12), which profiles are brought about by the implantation, and has two or more layers or layer portions (14) which are arranged one behind the other in the height direction of the energy filter (20). The energy filter (20) also has a plurality of cavities (16), each of which is arranged between at least two layers or layer portions (14), wherein intermediate walls (18) delimit the cavities (16) and interconnect the at least two layers or layer portions (14).