Self-Aligned Contact Formation via Dummy Isolation and Dielectric Replacement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In modern semiconductor technology nodes, the small size of transistor devices leads to precision challenges in contact etching, causing misalignment between MOSFET devices and metal interconnect layers, resulting in poor electrical connections and potential damage to transistor gates due to increased RC constant and overlay shift variation.
Innovation Solution
The method involves forming self-aligned contacts by interspersing gate lines and dielectric lines over an active area, cutting them into sections, depositing dummy isolation material between sections, and replacing parts of the dielectric lines with contact metal to prevent misalignment, thereby ensuring precise electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional contact etching is used in modern technology nodes, then manufacturing process is simple, but manufacturing precision deteriorates due to misalignment between MOSFET devices and metal interconnect layers
Solution Approach 1:
The method performs preliminary patterning of mandrel structures and dielectric lines before contact hole formation. By pre-positioning these reference structures and using them to define contact locations, the alignment precision is improved without requiring complex real-time alignment procedures during contact etching.
Solution Approach 2:
The patent introduces mandrel structures and dielectric lines as intermediary reference elements that mediate between the lithography pattern and the final contact positions. These intermediaries serve as alignment templates that guide subsequent etching steps, ensuring precise contact placement without direct complex alignment between metal interconnect and MOSFET devices.
2Length of moving object
If contact size is reduced to match smaller transistor devices, then device scaling is achieved, but reliability deteriorates due to increased RC constant and potential gate damage
Solution Approach 1:
The patent replaces direct mechanical alignment procedures with a pattern-based self-alignment mechanism. Instead of relying on mechanical overlay alignment between separate lithography steps, the method uses patterned mandrels and dielectric lines that automatically define contact positions through their geometric relationships, eliminating alignment errors and ensuring reliable electrical connections.
Solution Approach 2:
The method changes the parameter of contact formation from direct etching to a multi-step pattern transfer process. By altering the formation mechanism and using intermediate patterning steps, the effective contact dimensions are precisely controlled while maintaining reliability through improved alignment and reduced RC constants.
Data Source
AI summary
The present disclosure relates to methods of forming a self-aligned contact and related apparatus. In some embodiments, the method forms a plurality of gate lines interspersed between a plurality of dielectric lines, wherein the gate lines and the dielectric lines extend in a first direction over an active area. One or more of the plurality of gate lines are into a plurality of gate line sections aligned in the first direction. One or more of the plurality of dielectric lines are cut into a plurality of dielectric lines sections aligned in the first direction. A dummy isolation material is deposited between adjacent dielectric sections in the first direction and between adjacent gate line sections in the first direction. One or more self-aligned metal contacts are then formed by replacing a part of one or more of the plurality of dielectric lines over the active area with a contact metal.