Thermal Wave Dose Monitoring with Ion Beam Current Correction

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Solution Overview

Problem

Thermal wave (TW) measurements for ion implant dose monitoring are affected by lattice damage relaxation and other process variations, leading to instability and difficulty in controlling implantation processes.

Innovation Solution

A method to derive a corrected thermal wave signal by incorporating measured ion beam current signals to compensate for fluctuations, using a calibration curve to stabilize TW measurements and improve accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If laser annealing is used to accelerate lattice damage relaxation, then the relaxation process is sped up, but the TW signal stability is not adequately improved when other process variations exist

Engineering Contradiction:

Improvelattice damage relaxation speedVSAvoidTW signal stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The patent implements feedback control by continuously monitoring the TW signal and comparing it against reference values to detect deviations caused by process variations. The system automatically adjusts implantation parameters based on this feedback to maintain signal stability and compensate for lattice damage relaxation effects.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes measurement parameters by taking TW measurements at multiple time points after ion implantation (e.g., immediately after implantation and after a delay period). By analyzing the signal evolution over time and comparing measurements at different parameters, the system can distinguish between lattice damage relaxation effects and actual implant dose variations.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If TW measurements are used for dose monitoring, then implant dose can be monitored, but process deviations become difficult to control

Engineering Contradiction:

Improveimplant dose monitoring accuracyVSAvoidprocess control difficulty

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The system uses TW signal feedback to automatically control implantation parameters, creating a closed-loop system that maintains ease of operation while achieving precise dose monitoring. The automated feedback mechanism handles the complexity of process control, allowing operators to simply set target parameters while the system self-regulates.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary TW measurements and characterizations before actual implantation to establish baseline values and calibration curves. This preliminary action prepares the system in advance, making the subsequent implantation process easier to control by having pre-determined reference values and correction factors ready.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If TW signal is used directly for monitoring, then measurements are simple, but signal fluctuations from various sources reduce accuracy

Engineering Contradiction:

Improvemeasurement system simplicityVSAvoidTW signal accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent segments the TW signal analysis into multiple independent components: immediate post-implantation measurements, delayed measurements, and reference measurements. By analyzing these segmented measurements separately and comparing them, the system can isolate and compensate for different sources of signal fluctuation while maintaining measurement simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces time delay as an intermediary parameter between ion implantation and TW measurement. By measuring the TW signal at different time intervals and using the time-dependent signal evolution as a mediator, the system can distinguish between transient effects (like lattice damage relaxation) and permanent implant dose effects, thereby improving accuracy without complicating the measurement setup.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enhances the stability and accuracy of TW measurements by compensating for ion beam current variations, allowing precise monitoring of lattice damage and implant dose distribution.

Implementation Method 1

Thermal wave (TW) measurements are becoming standard for monitoring of ion implantation processes

Methodology Applied

Scientific EffectThermal wave measurement:

Implementation Method 2

It is known to accelerate the lattice damage relaxation process by using laser annealing (so-called laser-forced lattice damage relaxation)

Methodology Applied

Scientific EffectLaser annealing: Annealing

Data Source

PatentUS20250299919A1Ion implant dose monitoring by thermal wave measurement

Publication Date: 2025.09.25 INFINEON TECHNOLOGIES AG

AI summary

A method of deriving a corrected thermal wave signal for improving accuracy of monitoring lattice damage caused by ion beam implantation in a crystalline substrate includes obtaining a measured ion beam current signal indicative of the ion beam current used for ion beam implantation in the substrate. A thermal wave measurement is performed on the crystalline substrate after ion beam implantation to obtain a measured thermal wave signal. The corrected thermal wave signal is calculated based on the measured ion beam current signal and the measured thermal wave signal.