Field Emission Ion Source for Semiconductor Implantation
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Solution Overview
Problem
As semiconductor wafers increase in size, maintaining within-wafer uniformity (WiWU) becomes challenging due to limitations in ion beam current and filament-based electron source devices, which affect productivity and wafer yield.
Innovation Solution
An ion generation apparatus with an electron beam source device featuring a field emission array, where electrons from the array and a cathode collide with dopant gases to generate a higher ion beam current, increasing productivity and uniformity through enhanced ion implantation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If filament-based electron source devices are used to generate ion beam, then the ion beam can be produced for doping semiconductor wafers, but the ion beam current is limited and the filament lifetime is short, reducing productivity
Solution Approach 1:
The patent changes the fundamental parameter of electron generation from thermionic emission (filament-based) to field emission. This parameter change enables much higher electron current density and eliminates the lifetime limitation of filaments, directly resolving the contradiction between productivity and filament lifetime.
2Productivity
If larger semiconductor wafers are used to improve throughput, then the wafer area increases by 125%, but the within wafer uniformity becomes more difficult to maintain due to limitations in ion beam current
Solution Approach 1:
By changing from thermionic emission to field emission, the patent achieves higher ion beam current that can uniformly cover larger wafer areas (450mm and beyond), maintaining manufacturing precision while improving throughput.
3Productivity
If thermionic electrons are generated from heated filament to collide with dopant precursors, then plasma comprising dopant ions can be generated, but the ion beam current is limited affecting doping efficiency
Solution Approach 1:
The patent replaces the thermal-mechanical process of thermionic emission with an electrical-field-based field emission process. This substitution eliminates the need for heating and enables much higher electron current density, directly increasing ion beam current and doping efficiency.
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 increased ion beam current improves doping efficiency and productivity for larger wafers, maintaining uniformity and extending filament lifetime, thereby enhancing overall ion implantation processes.
Implementation Method 1
an electron beam source device comprising a field emission array having a plurality of emitters for generating electrons in vacuum under an electric field
Implementation Method 2
the electrons from the field emission array and a cathode configured so that the electrons from the field emission array collide with the cathode, and the cathode emits secondary electrons. The electrons collide with the dopant gas to ionize the dopant molecules to generate plasma
Data Source
AI summary
An apparatus comprises an ionization chamber for providing ions during a process of ion implantation, and an electron beam source device inside the ionization chamber. The electron beam source device comprises a field emission array having a plurality of emitters for generating electrons in vacuum under an electric field.