ASML Holding has been granted a patent for a method of determining the overlay value of a substrate. The method involves obtaining temperature data from the substrate table and using it to calculate the overlay value. The patent also includes a method for determining the performance of a clamping by the substrate table using the determined overlay value. GlobalData’s report on ASML Holding gives a 360-degree view of the company including its patenting strategy. Buy the report here.

According to GlobalData’s company profile on ASML Holding, AI-assisted photolithography was a key innovation area identified from patents. ASML Holding's grant share as of September 2023 was 47%. Grant share is based on the ratio of number of grants to total number of patents.

Method of determining overlay value of a substrate using temperature data

Source: United States Patent and Trademark Office (USPTO). Credit: ASML Holding NV

A recently granted patent (Publication Number: US11774869B2) describes a method and system for determining the overlay value of a substrate. The overlay value refers to the alignment accuracy of different layers of the substrate. The method involves obtaining temperature data from one or more temperature sensors on a substrate table after a substrate has been loaded onto it. The hardware computer then determines the overlay value based on the obtained temperature data over a measurement time period and the variance of the temperature data at different positions on the substrate.

The determined overlay value can be a residual overlay value, which indicates the overlay error of a layer of the substrate after alignment models have been applied. Depending on the overlay value, various actions can be taken, such as scrapping the substrate, re-working it, or thermally reconditioning it. The method also allows for selecting alignment models for determining residual overlay value or evaluating overlay, as well as determining correction values and performing further processes on the substrate based on these values.

The temperature data is obtained from temperature sensors on the substrate table, which measure the temperature of the substrate table. Multiple temperature sensors may be used, and the temperature data includes data from each of these sensors. The measurement time period starts when the substrate is loaded onto the table and lasts between 1 µs and 10 s.

The overlay value can be determined based on the magnitude or gradient of the measured temperature by the temperature sensors over the measurement time period. It can also be determined based on relative values of the measured temperature by different temperature sensors or by comparing the measured temperature to reference values. Importantly, the overlay value is determined in real-time, allowing for immediate feedback and adjustments.

In addition to the method, the patent also describes a substrate support system that includes a substrate table, one or more temperature sensors, and a computing system with a processor. The temperature sensors obtain temperature data by measuring the temperature of the substrate table at different positions, and the computing system uses this data to determine the overlay value of the substrate.

Overall, this patent presents a method and system for accurately determining the overlay value of a substrate based on temperature data obtained from temperature sensors. This can help improve the alignment accuracy of different layers in the production process and enable timely corrective actions.

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