Contact-to-Gate Shorting via Sacrificial Pillars in SRAM
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Solution Overview
Problem
As semiconductor devices shrink in size, current processes struggle to maintain yield with smaller SRAM cell layouts, leading to inefficiencies in forming conductive paths between fins for contact-to-gate shorting.
Innovation Solution
A method involving a wafer with a substrate, fins, and a hard mask, where sacrificial pillars and gates are formed, followed by a replacement metal gate process to fill openings with metal, ensuring direct contact between the gate metal and pillars, thereby enhancing yield and reducing contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If current processes are used with smaller SRAM cell layouts, then device size decreases, but manufacturing yield deteriorates
Solution Approach 1:
The patent applies preliminary action by forming sacrificial pillars and sacrificial gates before the final gate structure is created. The sacrificial pillars are formed first, then sacrificial gates are formed over them, establishing a preliminary structure that guides subsequent processing steps. This preliminary configuration enables precise formation of conductive paths between fins while maintaining control over the final gate alignment, thereby preserving manufacturing yield even as cell layouts shrink.
Solution Approach 2:
The patent uses sacrificial pillars and sacrificial gates as intermediary structures. The sacrificial pillars serve as mediators that define the position and geometry of the final conductive paths. The sacrificial gates act as intermediaries that transfer the pattern from the sacrificial pillars to the final gate structure. These intermediary elements enable precise positioning without requiring direct manipulation of the final gate, thus maintaining manufacturing yield during scaling.
2Area of moving object
If components are placed closer together to reduce cell layout size, then area decreases, but manufacturing precision requirements increase
Solution Approach 1:
The patent segments the gate formation process into multiple distinct stages: forming sacrificial pillars, forming sacrificial gates over the pillars, removing sacrificial pillars to create openings, and finally forming the metal gate. This segmentation allows each step to be optimized independently for precision, with each stage contributing to the final component placement accuracy. The sacrificial pillars are formed with precise dimensions, and the sacrificial gates are formed with precise alignment to these pillars, ensuring high manufacturing precision even when components are placed closer together.
Solution Approach 2:
The preliminary formation of sacrificial pillars with precise dimensions and positions establishes a reference framework before the final gate structure is created. This preliminary action ensures that when components are placed closer together, the precise relative positioning is maintained through the sacrificial structure guidance, reducing the direct precision requirements on the final gate formation step.
3Device complexity
If sacrificial pillars and gates are formed with direct contact, then conductive path formation is simplified, but process complexity increases
Solution Approach 1:
The patent merges the formation of conductive paths with the gate formation process itself. By forming sacrificial gates directly over sacrificial pillars with contact between them, the conductive path formation is combined with the gate structure creation. The removal of sacrificial pillars automatically creates the conductive path openings, and the metal fill step simultaneously forms both the gate metal and the conductive path metal. This merging simplifies the overall device structure while the systematic process steps manage the fabrication complexity.
Solution Approach 2:
The sacrificial pillars and sacrificial gates serve as intermediary structures that simplify the final conductive path formation. Instead of directly forming complex conductive paths between fins, the sacrificial structures mediate this process by providing a temporary framework that is removed to create the desired conductive paths. This intermediary approach reduces the direct complexity of conductive path formation while the systematic removal and fill processes manage the overall fabrication complexity.
Data Source
AI summary
Semiconductor devices and methods of fabricating the semiconductor devices for forming conductive paths between fins for contact-to-gate shorting. One method includes, for instance: obtaining wafer with a substrate, at least one fin, at least one hard mask, and an oxide layer; etching the oxide layer to reveal at least one of a portion of the hard masks; forming sacrificial pillars over the substrate; forming sacrificial gates, wherein at least one sacrificial gate contacts at least one sacrificial pillar; growing an epitaxial layer between the at least one sacrificial gate and the at least one sacrificial pillar; starting a RMG process on the sacrificial gates; etching to remove the sacrificial pillars and form pillar openings; and completing the RMG process to fill the pillar openings and the gate openings with a metal.