Extending Metal Gate in Semiconductor FinFET Isolation
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Solution Overview
Problem
Existing semiconductor manufacturing processes are inadequate for continued device scaling-down, particularly in achieving higher levels of integration and performance due to limitations in shrinking device sizes on a chip.
Innovation Solution
A 'gate-last' process is employed, where a dummy gate structure is formed first and then replaced by a metal gate structure, allowing the metal gate to extend into the isolation structure, thereby improving performance by increasing the effective area and adjusting electrical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If device scaling-down continues to achieve higher integration levels, then circuit integration increases, but manufacturing precision and tolerance control become inadequate
Solution Approach 1:
A dummy gate structure is formed preliminarily during the manufacturing process, which serves as a placeholder that enables subsequent processing steps. This preliminary structure allows the isolation structure to be formed and processed first, and the actual metal gate is formed later, accommodating the challenges of scaling by decoupling the gate formation timing from other critical dimensions.
Solution Approach 2:
The gate structure formation process is segmented into distinct phases: first forming a dummy gate structure, then forming the isolation structure, and finally replacing the dummy gate with the actual metal gate. This segmentation allows independent optimization of each structure's dimensions and timing, addressing the manufacturing precision challenges at scaled dimensions.
2Area of stationary object
If device size is shrunk to increase integration, then chip area utilization improves, but existing manufacturing processes become inadequate
Solution Approach 1:
The dummy gate structure is formed in advance as a preliminary action that occupies the gate region during isolation structure formation. This allows the isolation trenches to be defined and filled with proper dimensional control, while the actual metal gate dimensions are determined later, making the overall process more manageable at scaled dimensions.
Solution Approach 2:
The dummy gate structure serves as an intermediary element that facilitates the formation of both the isolation structure and the subsequent metal gate. It acts as a placeholder that enables proper spacing and alignment during manufacturing, making the scaled-down device easier to manufacture by providing reference structures during critical processing steps.
3Area of moving object
If metal gate extends into isolation structure, then effective area increases and performance improves, but manufacturing complexity increases
Solution Approach 1:
The dummy gate structure is formed preliminarily to define the gate region, and the isolation structure is formed around it. The metal gate is then formed to extend into the isolation structure by utilizing the already-formed dummy gate as a template and the isolation structure as an extension path, achieving increased effective area without proportionally increasing complexity.
Solution Approach 2:
The metal gate structure is merged with the isolation structure by allowing the gate to extend into the isolation region. This merging is facilitated by the preliminary dummy gate formation and subsequent selective removal processes, creating a unified structure that increases effective area while using existing process steps rather than adding separate complex operations.
Data Source
AI summary
A semiconductor structure and a method for forming the same are provided. The semiconductor structure includes a substrate and a fin structure formed over the substrate. The semiconductor structure further includes an isolation structure formed around the fin structure and a gate structure formed across the fin structure. In addition, the gate structure includes a first portion formed over the fin structure and a second portion formed over the isolation structure, and the second portion of the gate structure includes an extending portion extending into the isolation structure.