Machine Learning Model Training for Lithography Patterning Accuracy

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Solution Overview

Problem

Current device manufacturing processes, particularly in lithography, face challenges in accurately predicting and adjusting patterning processes to achieve precise dimensions and edge placement, leading to inefficiencies and defects in semiconductor device production.

Innovation Solution

A machine learning model, such as a convolutional neural network, is trained to predict physical characteristics associated with substrates by iteratively reducing cost functions based on differences between reference and generated images, allowing for adjustments in patterning processes to improve accuracy and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional patterning processes are used without machine learning prediction, then the manufacturing process is simpler and faster to execute, but the manufacturing precision of critical dimensions and edge placement deteriorates

Engineering Contradiction:
Improvecritical dimension prediction accuracyVSAvoidmodel training and execution complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The machine learning model is trained in advance using historical process data and simulation results before actual production. This preliminary training phase allows the model to learn complex patterning process relationships offline, so that during actual manufacturing, the model can quickly predict critical dimensions and provide optimization recommendations without adding significant real-time computational burden.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The machine learning model acts as an intermediary between traditional patterning processes and advanced lithography systems. It bridges the gap by taking simple process parameters as input and providing enhanced prediction capabilities for critical dimensions, thereby improving manufacturing precision without requiring fundamental changes to the underlying lithography equipment or process flow.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If machine learning model training is implemented to improve prediction accuracy, then the manufacturing precision improves, but the loss of time increases due to iterative model training

Engineering Contradiction:
Improveedge placement prediction accuracyVSAvoidmodel training time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The model training process is segmented into distinct phases: initial model construction using simulation data, iterative refinement using measured process data, and final validation. This segmentation allows parallel processing where simulation-based training can occur independently of physical manufacturing, reducing the overall time impact on production while still achieving high prediction accuracy through multiple refinement iterations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements iterative model training where the model is progressively refined through multiple training cycles. Rather than requiring complete retraining from scratch, the model undergoes partial updates using new measured data, where each iteration incrementally improves prediction accuracy. This approach balances the need for high precision with acceptable training time by performing targeted updates rather than exhaustive retraining.

Inventive Principle:
Principle #16Partial or excessive action

3Manufacturing precision

If iterative cost function reduction is performed to train the model, then the manufacturing precision improves, but the productivity decreases due to multiple training iterations

Engineering Contradiction:
Improvepattern prediction accuracyVSAvoidpatterning process throughput
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Extensive model training and cost function optimization are performed in advance during non-production periods. The model undergoes multiple iterative training cycles using historical data to achieve high prediction accuracy before being deployed for actual patterning processes. Once trained, the model provides rapid predictions during production without requiring repeated iterative optimization, thereby maintaining high manufacturing precision while preserving production throughput.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The machine learning model creates a virtual copy of the complex patterning process physics and chemistry. Instead of performing repeated physical trial-and-error experiments to optimize patterns, the trained model provides rapid virtual predictions of critical dimensions and edge placement. This virtual copying allows extensive optimization to be performed computationally rather than physically, improving prediction accuracy without sacrificing production productivity.

Inventive Principle:
Principle #26Copying

Data Source

PatentUS20220284344A1Method for training machine learning model for improving patterning process
Publication Date: 2022.09.08 ASML NETHERLANDS BV
  • US20220284344A1 patent drawing
  • US20220284344A1 patent drawing
  • US20220284344A1 patent drawing

AI summary

A method for training a machine learning model configured to predict values of a physical characteristic associated with a substrate and for use in adjusting a patterning process. The method involves obtaining a reference image; determining a first set of model parameter values of the machine learning model such that a first cost function is reduced from an initial value of the cost function obtained using an initial set of model parameter values, where the first cost function is a difference between the reference image and an image generated via the machine learning model; and training, using the first set of model parameter values, the machine learning model such that a combination of the first cost function and a second cost function is iteratively reduced, the second cost function representing a difference between measured values and predicted values.