Ion Beam Charge Control via Sheet Resistance Feedback
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Solution Overview
Problem
During semiconductor manufacturing, ion implantation processes face challenges with non-uniformity due to charge accumulation on insulating layers, leading to reduced ion implantation uniformity and potential damage to thin gate oxide layers, which existing methods fail to adequately address.
Innovation Solution
A method involving the formation of an insulation layer pattern on a semiconductor wafer with specific regions to measure sheet resistance variations, allowing for the adjustment of electron addition to the ion beam to neutralize surface charges and achieve uniform ion implantation energy.
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
Solution Approach 1:
The patent converts the harmful charge accumulation effect into a useful measurement signal. By measuring the sheet resistance change caused by charge accumulation in the insulating layer, the system detects the degree of charge buildup and uses this information to adjust the ion beam parameters, thereby compensating for the non-uniformity caused by charge accumulation
Solution Approach 2:
The patent implements a feedback control mechanism where sheet resistance measurements are continuously monitored during ion implantation. The measured sheet resistance values are fed back to control the ion beam current or acceleration voltage, dynamically adjusting the implantation process to maintain uniformity despite charge accumulation effects
2Quantity of substance
If charge accumulation occurs on the insulating layer surface, then a space electric field is established, but this field increases repulsion to the ion beam and reduces implantation amount
Solution Approach 1:
The patent uses sheet resistance measurement as a feedback signal to detect the strength of the electric field caused by charge accumulation. Based on this feedback, the system adjusts ion beam parameters (current or voltage) to compensate for the repulsion force, ensuring consistent ion implantation amount despite the presence of the electric field
3Manufacturing precision
If charges are accumulated on the insulating layer, then sheet resistance changes, but this makes it difficult to control uniform ion implantation energy
Solution Approach 1:
The patent introduces an intermediary measurement approach by using sheet resistance change as an indirect indicator of charge accumulation. Instead of directly measuring the electric field or charge density, the system measures the resulting sheet resistance change, which serves as a proxy signal to control ion implantation energy uniformity
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 by reducing charge repulsion and enhancing ion implantation energy across the wafer surface, providing accurate process parameters for regular production.
Implementation Method 1
a specific amount of electrons is added into the ion beam... adjusting the amount of the added electrons according to the variation of the plurality of sheet resistance values
Implementation Method 2
implanting an ion beam into the wafer... ionized impurity atoms are injected into the surface of the wafer after being accelerated by an electrostatic field
Implementation Method 3
The charged ions 212 form an ion beam under the function of the electrodes... these layers may be filled with charges 211 and the surface of wafer is partially charged
Implementation Method 4
The insulation layer, on which charges are accumulated, will produce an increasingly stronger repulsion to the ion beam when the amount of accumulated charges increases
Data Source
AI summary
A method of controlling charge amount of an ion beam, includes providing a semiconductor wafer; forming an insulation layer on the surface of the wafer, with gaps between parts of 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; measuring a plurality of sheet resistance values along the open region and the narrow and long region; adjusting the amount of the added electrons according to the variation of the plurality of sheet resistance values. 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.