FIELD

The present description relates to a method, system and program for determining contribution to a fingerprint of a parameter.

BACKGROUND

A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g., including part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. These target portions are commonly referred to as “fields”.

In lithographic processes, it is desirable to frequently measure the structures created forming a circuit pattern, e.g., for process control and verification. Various tools for making such measurements are known, including scanning electron microscopes, which are often used to measure critical dimension (CD), and specialized tools to measure overlay (which is the accuracy of alignment of two layers in an at least partially patterned substrate). Various techniques can be used to measure performance of the lithographic process. This in turn allows sophisticated process corrections to be included in the control of the operations performed by the lithographic apparatus.

SUMMARY

After exposure of the substrate, i.e. when the patent is transferred under the substrate, various different processes can be carried out on the substrate. Thus, different processing tools may be used on a substrate. However, each processing tool may slightly vary the overlay fingerprint. There are methods of reducing the effects of variations induced by processing tools, for example by adjusting lithographic apparatus actuators and improving the control. However, each substrate may be provided with the same correction meaning that the variation induced on each substrate is not individually dealt with.

One issue is that a number of different devices may be provided to carry out the processing of a substrate. There may be a number of different types of device used to process a substrate in different ways, e.g. an etching device and a polishing device. Additionally, there may be a multiple of the same type of device available to be used for each substrate. Thus, there may be multiple etching and/or polishing devices which could be used on each substrate and each substrate may be processed using a different combination of devices from a plurality of devices. Each of the devices may have a different effect on the fingerprint of a parameter and it is not necessarily clear what the effect of an individual device is on the parameter of the substrate.

An embodiment of the present invention has, for example, an aim of determining a contribution from a device out of a plurality of devices to a fingerprint of a parameter, the parameter being associated with processing of a substrate.

According to an aspect, there is provided a method for determining a contribution of a device out of a plurality of devices to a fingerprint of a parameter, the parameter being associated with processing of a substrate, the method comprising: obtaining parameter data and usage data, wherein the parameter data is based on measurements for multiple substrates having been processed by the plurality of devices, and the usage data indicates which of the devices out of the plurality of the devices were used in the processing of each substrate; and determining the contribution using the usage data and parameter data.

According to an aspect, there is provided a system comprising a processor configured to determine a contribution of a device out of a plurality of devices to a fingerprint of a parameter, the parameter being associated with processing of a substrate, the processor being configured to: obtain parameter data and usage data, wherein the parameter data is based on measurements for multiple substrates having been processed by the plurality of devices, and the usage data indicates which of the devices out of the plurality of devices were used in the processing of each substrate; and determine the contribution using the usage data and the parameter data.

According to an aspect, there is provided a program for controlling determining a contribution of a device out of a plurality of devices to a fingerprint of a parameter, the parameter being associated with processing of a substrate, the program comprising instructions for carrying out a method comprising: obtaining parameter data and usage data, wherein the parameter data is based on measurements for multiple substrates having been processed by the plurality of devices, and the usage data indicates which of the devices out of the plurality of devices were used in the processing of each substrate; and determining the contribution using the usage data and the parameter data.

