Ion Implant Tilt Angle for Shallower Depth at High Energy
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Solution Overview
Problem
Conventional semiconductor processing apparatuses have limited energy ranges, making it challenging to implant field stop layers at varying depths in power devices of different thicknesses, as they often require separate apparatuses for each device thickness, which is economically inefficient and technologically restrictive.
Innovation Solution
A semiconductor processing system that includes an ion source, accelerator, platen, and platen orientation motor, allowing for higher energy implants with adjustable tilt angles to achieve shallower peak concentration depths, emulating lower energy implant profiles by tilting the workpiece during the implant process, thereby expanding the range of achievable implant energies and depths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single semiconductor processing apparatus is used for different power device thicknesses, then device versatility is improved, but the ability to implant ions at different depths deteriorates due to limited energy range
Solution Approach 1:
The patent applies parameter changes by varying the tilt angle of the workpiece during ion implantation. By changing this geometric parameter, the system achieves different effective implantation depths from a fixed energy source. The tilt angle modification transforms the projection depth of ion penetration, enabling a single apparatus to handle multiple device thicknesses (e.g., 100 μm to 550 μm) with appropriate depth control.
2Use of energy by moving object
If higher energy implants are used, then implant energy is improved, but peak concentration depth becomes deeper than desired
Solution Approach 1:
The patent introduces another dimension by tilting the workpiece at an angle relative to the ion beam direction. This angular dimension transforms the vertical depth problem into a geometric projection problem. The effective implantation depth becomes the product of ion range and cosine of the tilt angle, allowing higher energy implants to achieve shallower effective depths through angular manipulation rather than reducing energy.
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
Enables the creation of field stop layers at precise depths across a range of power device thicknesses using higher energy implants, achieving resistivity profiles similar to those produced by lower energy implants, thus enhancing the versatility and efficiency of semiconductor processing.
Implementation Method 1
an accelerator capable of accelerating hydrogen ions to an implant energy between a minimum value and a maximum value
Implementation Method 2
By tilting the workpiece during an implant, the system can be used to perform implants that are typically performed at implant energies that are less than the minimum implant energy allowed by the system
Data Source
AI summary
A system and method that allows higher energy implants to be performed, wherein the peak concentration depth is shallower than would otherwise occur is disclosed. The system comprises an ion source, an accelerator, a platen and a platen orientation motor that allows large tilt angles. The system may be capable of performing implants of hydrogen ions at an implant energy of up to 5 MeV. By tilting the workpiece during an implant, the system can be used to perform implants that are typically performed at implant energies that are less than the minimum implant energy allowed by the system. Additionally, the resistivity profile of the workpiece after thermal treatment is similar to that achieved using a lower energy implant. In certain embodiments, the peak concentration depth may be reduced by 3 μm or more using larger tilt angles.