Ion Beam Uniformity Control via Magnetic Field Destabilization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Ion implantation in semiconductor wafers faces challenges in maintaining uniformity of the ion beam, particularly at low energy levels, leading to non-uniform characteristics in the implanted substrate due to uneven ion concentration across the beam width.
Innovation Solution
Introducing bias voltage at specific points within a magnetic field, such as a dipole magnetic field, to destabilize the ion beam and cause it to expand, using electrodes that are electrically isolated and powered independently to manage space charge effects, thereby redistributing ion concentration uniformly across the beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the ion beam is maintained at low energy levels for shallow implants, then the implantation depth is reduced, but the ion beam uniformity becomes difficult to maintain leading to non-uniform ion concentration across the beam width
Solution Approach 1:
The patent applies dynamic control by introducing oscillating or time-varying magnetic fields that actively modulate the ion beam profile during implantation. This dynamic approach allows real-time compensation for beam non-uniformity, enabling uniform ion distribution even at low energy levels where traditional static beam control fails.
Solution Approach 2:
The patent changes magnetic field parameters (strength, orientation, temporal characteristics) to control ion beam characteristics. By varying magnetic field parameters dynamically, the system can maintain uniform ion concentration across the beam width while operating at low energy levels, resolving the contradiction between shallow implantation depth and beam uniformity.
2Productivity
If the ion beam concentration is increased to improve implantation efficiency, then productivity increases, but the beam becomes more prone to space charge effects that degrade uniformity
Solution Approach 1:
The patent introduces magnetic fields as an intermediary mechanism that mediates between ion beam concentration and uniformity. The magnetic field acts as a controlling intermediary that can handle high ion currents while maintaining uniform distribution, allowing high productivity without the detrimental space charge effects that would otherwise occur at high concentrations.
Solution Approach 2:
The patent employs oscillating or time-varying magnetic fields that create a dynamic control mechanism, analogous to vibration principles. This temporal modulation prevents space charge accumulation and maintains uniform ion distribution even at high beam intensities, enabling high productivity without sacrificing uniformity.
3Object-generated harmful factors
If traditional electrostatic chucks are used to hold the workpiece, then the workpiece is held securely without mechanical fastening, but the cycle time increases due to the need for unfastening after implantation
Solution Approach 1:
The patent implements periodic or rapid switching of electrostatic field activation. The electrostatic chuck can be rapidly activated for implantation and just as rapidly deactivated for ejection, creating a periodic cycle that minimizes total cycle time. This periodic control allows the workpiece to be held securely during implantation while enabling rapid release, eliminating the time-consuming mechanical unfastening step.
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 technique ensures a more uniform ion implantation by reducing ion concentration uniformly across the beam, enhancing the performance and characteristics of the implanted substrate by maintaining even ion distribution, as shown in the graphs and cross-sectional views.
Implementation Method 1
the coil is energized so as to create a magnetic field within the gap, which deflects the ion beamlets in accordance with the strength and direction of the applied magnetic field
Implementation Method 2
By introducing a bias voltage at certain points within that magnetic field, electrons from the plasma are drawn toward the electrodes, thereby causing the ion beam to expand due to space charge effects
Implementation Method 3
The platen uses electrostatic force to hold the workpiece in position. By creating a strong electrostatic force on the platen, also known as the electrostatic chuck, the workpiece or wafer can be held in place
Data Source
AI summary
An apparatus and method for ion implantation that include destabilizing the ion beam as it passes through magnetic field, preferably a dipole magnetic field is disclosed. By introducing a bias voltage at certain points within the magnetic field, electrons from the plasma are drawn toward the magnet, thereby causing the ion beam to expand due to space charge effects. The bias voltage can be introduced into the magnet in a region where the magnetic field has only one component. Alternatively, the bias voltage can be in a region wherein the magnetic field has two components.