Abstract:
Disclosed is a method for determining an overlay error between at least two layers in a multiple layer sample. An imaging optical system is used to measure multiple measured optical signals from multiple periodic targets on the sample, and the targets each have a first structure in a first layer and a second structure in a second layer. There are predefined offsets between the first and second structures A scatterometry overlay technique is used to analyze the measured optical signals of the periodic targets and the predefined offsets of the first and second structures of the periodic targets to thereby determine an overlay error between the first and second structures of the periodic targets. The scatterometry overlay technique is a phase based technique, and the imaging optical system is configured to have an illumination and/or collection numerical aperture (NA) and/or spectral band selected so that a specific diffraction order is collected and measured for the plurality of measured optical signals. In one aspect, the number of periodic targets equals half the number of unknown parameters.
Abstract:
Disclosed is a scatterometry mark for determining an overlay error, critical dimension, or profile of the mark. The mark includes a first plurality of periodic structures on a first layer, a second plurality of periodic structures on a second layer, and a third plurality of periodic structures on a third layer that is underneath the first and second layer. The third periodic structures are perpendicular to the first and second structures, and the third periodic structures have one or more characteristics so as to result in a plurality of lower structures beneath the third periodic structures being screened from significantly affecting at least part of a spectrum of a plurality of scattered signals detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures or at least one of such detected scattered signals.
Abstract:
The disclosure is directed to designing and using an overlay target with orthogonal underlayer dummyfill. According to various embodiments, an overlay target may include one or more segmented overlay pattern elements forming at least one overlay target structure. The overlay target may further include one or more inactive pattern elements forming at least one dummyfill target structure. Each of the one or more inactive pattern elements may include dummyfill segmented along an axis orthogonal to a segmentation axis of at least one proximately disposed overlay pattern element. In some embodiments, each of the target structures or layers may be formed from a separate process layer successively disposed upon a substrate, such as a silicon wafer. In some embodiments, the overlay and dummyfill target structures may be twofold or fourfold rotationally symmetric to allow for certain manufacturing or metrology advantages.
Abstract:
A metrology design and verification framework is provided, which includes methods and systems for metrology structure identification in an integrated circuit design data block, design rule checking, hierarchal design of metrology target structures to minimize random errors, and metrology design rule verification of metrology target design files. In-die metrology targets are identified using various filtering methods and/or designed as hierarchical structure within dies or outside the dies. Particularly, metrology target design files are generated, which are hierarchical in structure and compatible with design rule checks. Design rule check takes into account the hierarchical and often repetitive target designs in the verification process. Layouts may be verified using design rule checks at different levels of design rules, which may be combined to remove rule violations and errors prior to actual target production.
Abstract:
A semiconductor fabrication system includes a target design device and a multi-stage fabrication tool configured to fabricate one or more layers of a sample using the fabrication process. The target design device receives metrology design rules associated with a metrology tool in which the metrology design rules include criteria for one or more physical attributes of metrology targets measurable with the metrology tool. The target design device may further receive process design rules associated with a fabrication process in which the process design rules include criteria for determining process stages of the fabrication process required to fabricate structures with selected physical attributes. The target design device may further generate a target design library including a plurality of metrology targets that satisfy the metrology design rules for the metrology tool and the process design rules for the fabrication process, wherein the target design library includes specifications for fabricating the plurality of metrology targets using two or more process stages of the fabrication process based on the process design rules.
Abstract:
Disclosed is a scatterometry mark for determining an overlay error, critical dimension, or profile of the mark. The mark includes a first plurality of periodic structures on a first layer, a second plurality of periodic structures on a second layer, and a third plurality of periodic structures on a third layer that is underneath the first and second layer. The third periodic structures are perpendicular to the first and second structures, and the third periodic structures have one or more characteristics so as to result in a plurality of lower structures beneath the third periodic structures being screened from significantly affecting at least part of a spectrum of a plurality of scattered signals detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures or at least one of such detected scattered signals.
Abstract:
Metrology may be implemented during semiconductor device fabrication by a) modeling a first measurement on a first test cell formed in a layer of a partially fabricated device; b) performing a second measurement on a second test cell in the layer; c) feeding information from the second measurement into the modeling of the first measurement; and after a lithography pattern has been formed on the layer including the first and second test cells, d) modeling a third and a fourth measurement on the first and second test cells respectively using information from a) and b) respectively.
Abstract:
A semiconductor fabrication system includes a target design device and a multi-stage fabrication tool configured to fabricate one or more layers of a sample using the fabrication process. The target design device receives metrology design rules associated with a metrology tool in which the metrology design rules include criteria for one or more physical attributes of metrology targets measurable with the metrology tool. The target design device may further receive process design rules associated with a fabrication process in which the process design rules include criteria for determining process stages of the fabrication process required to fabricate structures with selected physical attributes. The target design device may further generate a target design library including a plurality of metrology targets that satisfy the metrology design rules for the metrology tool and the process design rules for the fabrication process, wherein the target design library includes specifications for fabricating the plurality of metrology targets using two or more process stages of the fabrication process based on the process design rules.
Abstract:
Metrology may be implemented during semiconductor device fabrication by a) modeling a first measurement on a first test cell formed in a layer of a partially fabricated device; b) performing a second measurement on a second test cell in the layer; c) feeding information from the second measurement into the modeling of the first measurement; and after a lithography pattern has been formed on the layer including the first and second test cells, d) modeling a third and a fourth measurement on the first and second test cells respectively using information from a) and b) respectively.
Abstract:
The disclosure is directed to designing and using an overlay target with orthogonal underlayer dummyfill. According to various embodiments, an overlay target may include one or more segmented overlay pattern elements forming at least one overlay target structure. The overlay target may further include one or more inactive pattern elements forming at least one dummyfill target structure. Each of the one or more inactive pattern elements may include dummyfill segmented along an axis orthogonal to a segmentation axis of at least one proximately disposed overlay pattern element. In some embodiments, each of the target structures or layers may be formed from a separate process layer successively disposed upon a substrate, such as a silicon wafer. In some embodiments, the overlay and dummyfill target structures may be twofold or fourfold rotationally symmetric to allow for certain manufacturing or metrology advantages.