CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the U.S. national phase entry of PCT Patent Application No. PCT/EP2019/065107, which was filed on Jun. 11, 2019, which claims the benefit of priority of European Patent Application No. 18180889.0, which was filed on Jun. 29, 2018, and which is incorporated herein in its entirety by reference.

FIELD

The description herein relates to patterning apparatuses and processes, and more particularly to a method or tool for tuning of an apparatus of a patterning process, such as optical parameters related to a lithographic apparatus.

BACKGROUND

A lithography apparatus is a machine that applies a desired pattern onto a target portion of a substrate. A lithography apparatus can be used, for example, in the manufacture of devices such as integrated circuits (ICs). In that circumstance, a patterning device (e.g., a mask or a reticle) may be used to generate a pattern corresponding to an individual layer of the device, and this pattern can be transferred onto a target portion (e.g. comprising part of, one or several dies) on a substrate (e.g. a silicon wafer) that has, e.g., a layer of radiation-sensitive material (resist), by methods such as irradiating the target portion via a pattern on the patterning device. In general, a single substrate will contain a plurality of adjacent target portions to which the pattern is transferred successively by the lithographic apparatus, one target portion at a time. In one type of lithographic apparatus, the pattern on the entire patterning device is transferred onto one target portion in one go; such an apparatus is commonly referred to as a stepper. In an alternative apparatus, commonly referred to as a step-and-scan apparatus, a projection beam scans over the patterning device in a given reference direction (the “scanning” direction) while synchronously moving the substrate parallel or anti-parallel to this reference direction. Different portions of the pattern on the patterning device are transferred to one target portion progressively. Since, in general, a lithographic projection apparatus will have a demagnification factor M (generally >1), the speed F at which the substrate is moved will be a factor M times that at which the projection beam scans the patterning device.

Prior to transferring the pattern from the patterning device to the substrate, the substrate may undergo various procedures, such as priming, resist coating and a soft bake. After exposure, the substrate may be subjected to other procedures, such as a post-exposure bake (PEB), development, a hard bake and measurement/inspection of the transferred pattern. This array of procedures is used as a basis to make an individual layer of a device, e.g., an IC. The substrate may then undergo various processes such as etching, ion-implantation (doping), metallization, oxidation, chemo-mechanical polishing, etc., all intended to finish off the individual layer of the device. If several layers are required in the device, then the whole procedure, or a variant thereof, is repeated for each layer. Eventually, a device will be present in each target portion on the substrate. These devices are then separated from one another by a technique such as dicing or sawing, whence the individual devices can be mounted on a carrier, connected to pins, etc.

Thus, manufacturing devices, such as semiconductor devices, typically involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes to form various features and multiple layers of the devices. Such layers and features are typically manufactured and processed using, e.g., deposition, lithography, etch, chemical-mechanical polishing, and ion implantation. Multiple devices may be fabricated on a plurality of dies on a substrate and then separated into individual devices. This device manufacturing process may be considered a patterning process. A patterning process involves a patterning step, such as optical and/or nanoimprint lithography using a patterning device in a lithographic apparatus, to transfer a pattern on the patterning device to a substrate and typically, but optionally, involves one or more related pattern processing steps, such as resist development by a development apparatus, baking of the substrate using a bake tool, etching using the pattern using an etch apparatus, etc.

SUMMARY

Optical systems can play a role in the performance of a patterning process. Accordingly, there is provided herein technique to enable patterning process design, modification, control, etc. based on a characteristic of an optical system of a patterning apparatus such as a scanner.

According to an embodiment, there is provided a method for tuning a target apparatus of a patterning process. The method includes obtaining (i) a reference performance, and (ii) measurement data of a substrate subjected to the patterning process at the target apparatus, the measurement data indicative of a performance of the target apparatus; determining, via a processor, a cause of a performance mismatch based on a difference between the reference performance and the performance of the target apparatus, where the cause includes an optical characteristic; and responsive to the cause, adjusting, via the processor, optical parameters associated with an adjustable optical characteristic to reduce the performance mismatch in the optical characteristic.

In an embodiment, the determining the cause includes obtaining a sensitivity model including the optical parameters associated with the adjustable optical characteristic; performing a sensitivity analysis based on the sensitivity model employing the reference performance and the measurement data; and identifying dominant optical parameters that cause the performance mismatch.

In an embodiment, the adjusting the optical parameters is an iterative process. An iteration includes determining values of the dominant optical parameters such that the performance mismatch is reduced; adjusting optical parameters of the target apparatus according to the determined values of the optical parameters; and determining whether the performance mismatch is reduced.

In an embodiment, the optical characteristic is a non-tunable characteristic represented by an apodization map, a phase map, a retardatiaon map, and/or a diattenuation map.

In an embodiment, the adjusting of the optical parameters include adjusting an illumination pupil of the target apparatus when the cause is lens apodization or lens diattenuation.

In an embodiment, the adjusting of the optical parameters include adjusting lens aberrations of the target apparatus when the cause is lens retardation.

In an embodiment, the performance mismatch is minimized.

In an embodiment, the method further includes printing a pattern on the substrate using the target apparatus tuned according to the values of the optical parameters; and obtaining measurement data of the printed pattern; and verifying the performance of the target apparatus against the reference performance based on the measurement data.

In an embodiment, the reference performance is a performance of a reference apparatus different from the target apparatus.

In an embodiment, the reference performance is a performance of the target apparatus determined at a particular time of the patterning process.

In an embodiment, the performance and the reference performance are related to a parameter of the patterning process including critical dimension and/or overlay.

Furthermore, there is provided a method for tuning a target apparatus of a patterning process. The method includes obtaining (i) a reference performance, (ii) measurement data of a substrate subjected to the patterning process at the target apparatus, the measurement data indicative of a performance of the target apparatus, and (iii) a sensitivity model configured to translate an optical characteristic to the performance of the patterning process; determining, via a processor, a performance mismatch based on difference between the reference performance and the measurement data; simulating, via the processor, the sensitivity model to determine a cause of the performance mismatch; and responsive to the cause, adjusting, via the processor, optical parameters corresponding to the optical characteristic of the target apparatus to reduce the performance mismatch.

In an embodiment, the optical characteristic is a non-tunable characteristic represented by an apodization map, a phase map, a retardatiaon map, and/or a diattenuation map.

In an embodiment, the adjusting of the optical parameters include adjusting an illumination pupil of the target apparatus when the cause is lens apodization or lens diattenuation.

In an embodiment, the adjusting of the optical parameters include adjusting lens aberrations of the target apparatus when the cause is lens retardation.

Furthermore, there is provided a computer program product comprising a non-transitory computer readable medium having instructions recorded thereon, the instructions when executed by a computer implementing steps of the method described above.

