PATENT CLAIM ANALYSIS

Application Number: 15889412
Application Type: Utility
Filing Date: 2018-02
Publication Date: 2018-06
Patent Classification: ["356", "508000"]

Abstract:
An encoder head configured for use with a lithographic exposure tool. The head is devoid of the multiplicity of optical corner-cubes and includes, instead, a single, geometrically substantially perfect cuboid of optically-isotropic material complemented, in operation, with a birefringent lens to form a contraption that, as a unit, splits a single beam of light delivered to the contraption into four measurement (sub-)beams of light (two in xz-plane, two in yz-plane) and causes each of measurement sub-beams to interact with the wafer-stage diffraction grating at the same location twice: upon the first pass by the grating and upon the second pass by the grating. The use of the contraption solves problems of (i) structural complexity of a conventional encoder head for use in an exposure tool, (ii) burdensome alignment of the multitude of optical prisms in the process of forming such encoder head, and (iii) cyclic non-linear errors associated with measurements involving conventional corner-cubes-based encoder heads while, at the same time, reducing the geometrical footprint of the encoder head. The contraption is complemented with a birefringent prismatic element positioned across the axis of the contraption between the cuboid and the birefringent lens.

Claim (Index 30):
An encoder head for use in a lithographic exposure system in optical communication with a diffractive grating of the exposure system, the encoder head comprising:\n a first optical sub-system containing a combination of\n a single, substantially geometrically perfect cuboid of optically isotropic material, said cuboid having an axis; \n an optically-birefringent plane-parallel plate disposed substantially symmetrically about the axis; and \n an optically-birefringent lens disposed symmetrically about the axis; \n wherein the first optical subsystem is positioned\n to transmit light from an input light beam, delivered to the encoder head along the axis, \n to interact with the diffractive grating for a first time at a first area on a surface of the diffractive grating and, as a result of such interaction, \n to form a first beam of light directed from the diffraction grating to the first optical sub-system, and \n wherein the first beam of light, that has traversed the first sub-system twice, is incident at the diffraction grating to interact with the surface of the diffraction grating for a second time at a second area, the first and second area overlapping each other.

Metadata:
- Claim Count in Document: 83.0
- Percentile: 88.0
- Lexical Diversity: 2.02778
- Patent Class: 356.0
- Transitional Phrase Type: open
- Component Type: 1
- Foreign Priority: False
- Related Applications: ['15800480', '15866696', '15483887', '14880812', '13796316']

Analysis Scores:
- 35 USC 101 Eligibility (BERT): 0.7343793930966314
- 35 USC 102 Novelty (BERT): 0.5283541991082882
- Combined Prediction Score: 0.7137768736977971
- Mean Citation Score: 310.103094
- Max Citation Score: 366.1359
- Similarity Product: 300.2006425634265

Labels:
- Claim Label 101: 1
- Claim Label 102: 0
- Claim Label 103: 0
- Claim Label 112: 1
- Combined Label: 0
- Label 101 Adjusted: 1

Dataset: test