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 6):
The optical system according to  claim 1 ,\n wherein the optical system has an axis of symmetry, wherein, when said optical surface is a surface of a two-dimensional diffraction grating, the optical system is configured to form four output beams of light as a result of diffracting light, from the input beam of light, twice at said optical surface, and wherein wavevectors corresponding to said four output beams of light are inclined at the same angle with respect to the axis of symmetry.

Metadata:
- Claim Count in Document: 83.0
- Percentile: 88.0
- Lexical Diversity: 2.02778
- Patent Class: 356.0
- Transitional Phrase Type: none
- Component Type: 0
- Foreign Priority: False
- Related Applications: ['15800480', '15866696', '15483887', '14880812', '13796316']

Analysis Scores:
- 35 USC 101 Eligibility (BERT): 0.7569437431108814
- 35 USC 102 Novelty (BERT): 0.5306649509045946
- Combined Prediction Score: 0.7343158638902527
- Mean Citation Score: 310.103094
- Max Citation Score: 366.1359
- Similarity Product: 298.4928087293565

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