Ion Beam Charge Control via Reflectivity Feedback
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Solution Overview
Problem
The challenge in semiconductor manufacturing is achieving uniform ion implantation across a wafer surface due to charge accumulation on insulating layers, which leads to reduced ion implantation uniformity and potential damage to the thin gate oxide layer, as existing methods either fail to effectively control charge potential or require additional complex device structures.
Innovation Solution
A method involving the formation of an insulation layer on the wafer with specific regions to measure light reflectivity changes after ion implantation, allowing for the adjustment of electron addition to the ion beam to neutralize surface charges and optimize ion implantation energy uniformity, thereby reducing crystal lattice damage differences between regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion implantation is performed on a wafer with insulating layers, then doping is achieved, but charge accumulation on the insulating layers causes non-uniform ion implantation and reduces implantation uniformity
Solution Approach 1:
The patent converts the harmful charge accumulation effect into a useful measurement signal. By monitoring the charge potential developed on insulating layers during ion implantation, the system uses this previously harmful phenomenon as an indicator to control and optimize the implantation process, ultimately improving uniformity through feedback control
Solution Approach 2:
The patent implements a feedback control system where the charge potential on insulating layers is continuously monitored during ion implantation. The measured charge potential information is fed back to adjust implantation parameters in real-time, creating a closed-loop control system that maintains optimal implantation uniformity despite charge accumulation effects
2Ease of operation
If charge potential on wafer surface is increased to control ion implantation, then ion beam direction can be controlled, but repulsion to ion beam increases and reduces implantation amount
Solution Approach 1:
The patent uses feedback control to monitor the charge potential on the wafer surface during ion implantation. By measuring the actual charge potential and comparing it to target values, the system dynamically adjusts implantation parameters to maintain optimal control of the ion beam while compensating for repulsion effects, ensuring both controllability and sufficient implantation amount
3Manufacturing precision
If electrons are added to ion beam to neutralize surface charges, then ion implantation uniformity improves, but precise control of electron amount is required to avoid over-neutralization
Solution Approach 1:
The patent implements feedback control where the charge potential on insulating layers is continuously monitored and used to regulate the amount of electrons added to the ion beam. This closed-loop system automatically adjusts electron injection levels based on real-time measurements, achieving precise neutralization without requiring complex manual control mechanisms
Solution Approach 2:
The system uses the charge potential signal generated during implantation itself to control the neutralization process. The charge potential that would normally be harmful is instead utilized as the control signal for electron injection, creating a self-regulating system that automatically maintains optimal implantation conditions
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 improves the uniformity of ion implantation energy by adjusting the electron amount in the ion beam, reducing the repulsion from charged insulation layers and minimizing surface damage, providing accurate process parameters for regular wafer production.
Implementation Method 1
ionized impurity atoms are injected into the surface of the wafer after being accelerated by an electrostatic field
Implementation Method 2
accelerated by an electrostatic field
Implementation Method 3
The secondary electrons will be emitted out when the ions strike the surface of the silicon wafer As a result, these layers may be filled with charges 211 and the surface of wafer is charged
Implementation Method 4
The secondary electrons will be emitted out when the ions strike the surface
Implementation Method 5
emitting a plurality of light beams to the surface of the wafer along the open region and the narrow and long region and measuring a plurality of light reflectivity values
Data Source
AI summary
A method of controlling charge amount of an ion beam includes: providing a semiconductor wafer; forming insulation layer on the surface of the wafer, with gaps between the insulation layer dividing the surface of the wafer into an open region and a narrow and long region; implanting an ion beam into the wafer, in which a specific amount of electrons is added into the ion beam; emitting a plurality of light beams to the surface of the wafer along the open region and the narrow and long region, and measuring a plurality of light reflectivity; adjusting the amount of the added electrons according to the variation of the reflectivity. The method of the present invention can be used to determine whether the amount of added electrons is optimal by monitoring the uniformity of ion implantation, and make adjustment accordingly.