Accelerator Grid Voltage Zoning for Uniform Ion Beam Etching
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Solution Overview
Problem
Ion beam etching (IBE) processes face challenges in achieving uniform etching across tilted wafers due to varying ion beam incidence distances, leading to asymmetry etching behavior, which current technologies cannot effectively address.
Innovation Solution
The implementation of a three-grid ion beam etching system with varying voltages applied to accelerator grid elements to create electric fields of different energies, compensating for the differences in ion beam incidence distances and ensuring uniform etching across the wafer surface by dividing the grid system into zones with distinct voltage supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single voltage is applied to the accelerator grid, then the device complexity is low, but the etching uniformity across the wafer surface deteriorates due to asymmetry etching behavior
Solution Approach 1:
The accelerator grid is divided into multiple independently controllable elements or zones, each receiving a distinct voltage supply. This segmentation allows different regions of the grid to apply different voltages to compensate for varying ion beam incidence distances across the tilted wafer surface, thereby achieving uniform etching while managing complexity through modular voltage control.
Solution Approach 2:
Different voltage values are applied to different regions of the accelerator grid based on the local requirements of each zone. Regions with longer ion beam incidence distances receive higher voltages to increase ion energy and etching rate, while regions with shorter distances receive lower voltages, creating a spatially varying voltage distribution that compensates for geometric asymmetries and achieves uniform etching across the wafer.
2Shape
If the wafer is tilted for directional etching, then the etching directionality is improved, but the etching uniformity across different locations deteriorates due to varying incidence distances
Solution Approach 1:
The voltage parameter applied to the accelerator grid is dynamically changed across different spatial zones to compensate for the geometric effects of wafer tilting. By adjusting the voltage distribution pattern according to the tilt angle and incidence distance variations, the system maintains both directional etching capability and uniformity across the wafer surface, effectively decoupling these two previously conflicting requirements.
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 results in uniformly distributed etching across different locations of a tilted wafer, reducing asymmetry etching behavior and improving the precision and consistency of the IBE process.
Implementation Method 1
a screen grid voltage to supply a screen grid included in a three-grid system to extract ions from plasma within a plasma chamber
Implementation Method 2
varying voltages applied to accelerator grid elements to create electric fields of different energies
Implementation Method 3
a first ion beam through the first hole controlled by the first accelerator grid element has a first incidence distance to the wafer
Data Source
AI summary
The present disclosure relates to an ion beam etching (IBE) system including a process chamber. The process chamber includes a plasma chamber configured to provide plasma. In addition, the process chamber includes an accelerator grid having multiple accelerator grid elements including a first accelerator grid element and a second accelerator grid element. A first wire is coupled to the first accelerator grid element and configured to supply a first voltage to the first accelerator grid element. A second wire is coupled to the second accelerator grid element and configured to supply a second voltage to the second accelerator grid element, where the second voltage is different from the first voltage. A first ion beam through a first hole is controlled by the first accelerator grid element, and a second ion beam through a second hole is controlled by the second accelerator grid element.