Sacrificial Metal Alignment for CMOS Sensor Openings
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Solution Overview
Problem
Existing methods face difficulties in accurately aligning openings over CMOS sensors and other semiconductor structures, which is crucial for forming microlenses and filters, leading to inefficiencies in semiconductor fabrication.
Innovation Solution
The use of sacrificial metal-containing materials for alignment, where a penultimate metal layer is formed over the substrate and aligned with a sacrificial metal layer to define the opening, allowing for precise metal-to-metal alignment and subsequent removal to create the opening, enabling better alignment and integration of color filter and lens materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional alignment methods are used to form openings over CMOS sensors, then the fabrication process can proceed, but alignment precision deteriorates leading to misalignment between openings and sensors
Solution Approach 1:
The patent introduces an intermediary alignment mark structure formed from metal-containing material that serves as a reference for subsequent opening formation. This intermediary structure mediates between the sensor array and the openings, enabling precise alignment through metal-to-metal alignment processes rather than direct alignment between openings and sensors
Solution Approach 2:
The alignment mark structure is formed in advance before the openings are created. By preliminarily establishing a metal-based alignment reference that can be precisely aligned with the sensor array, the patent enables accurate opening placement without requiring complex real-time alignment during the opening formation process
2Manufacturing precision
If additional masks and alignment structures are added to improve opening alignment, then alignment precision improves, but device complexity increases
Solution Approach 1:
The metal-containing alignment mark structure serves multiple functions: it acts as an alignment reference for opening formation, serves as a sacrificial material during processing, and can be integrated with existing metal interconnect layers. This multi-functionality eliminates the need for separate dedicated alignment marks, reducing overall device complexity while maintaining alignment precision
Solution Approach 2:
The patent merges the alignment mark function with existing metal-containing structures in the fabrication process. By combining the alignment reference function with metal layers that are already part of the device architecture, the patent avoids adding separate complexity while achieving precise alignment
Data Source
AI summary
Some embodiments include methods of forming openings in which a metal-containing structure is formed over a region of a semiconductor substrate. A patterned metal-containing material is formed over the metal-containing structure, with the metal-containing material having a gap extending therethrough. An entirety of the metal-containing structure is removed through the gap to leave an opening over the region of the semiconductor substrate. The region of the semiconductor substrate may comprise CMOS sensors, and one or both of filter material and microlens material may be formed within the opening.