Replacement Gate Isolation Structure to Prevent Metal Gate Shorting
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Solution Overview
Problem
The complexity of semiconductor manufacturing processes is increased by the replacement of polysilicon gate electrodes with metal gate electrodes due to decreased feature sizes, leading to challenges such as shorting at replacement gate structures.
Innovation Solution
The use of high k metal gates formed in cavities created by removing polysilicon dummy gates, ensuring sufficient insulation around the cavity formed by removing the dummy gate, and using spacers to enhance the process window.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polysilicon gate electrodes are replaced with metal gate electrodes to improve device performance, then device performance is improved, but manufacturing process complexity increases and shorting occurs at replacement gate structures
Solution Approach 1:
A dummy polysilicon gate structure is formed in advance before the metal gate electrode replacement process. This preliminary structure serves as a template and protective element throughout the complex manufacturing steps, enabling the replacement process to proceed systematically while preventing shorting between adjacent structures.
Solution Approach 2:
The dummy polysilicon gate acts as an intermediary structure during the transition from polysilicon to metal gate. It mediates the manufacturing process by providing a sacrificial element that can be selectively removed after defining the metal gate regions, thereby simplifying the overall process control and preventing direct shorting between adjacent metal gate structures.
2Productivity
If feature sizes are decreased to increase functional density, then functional density is improved, but manufacturing process complexity increases
Solution Approach 1:
The dummy polysilicon gate is formed in advance at the larger dimension, establishing a defined pattern before any size reduction or complex processing occurs. This preliminary structuring enables subsequent steps to work with well-defined geometries, reducing the complexity associated with direct fabrication of smaller features.
Solution Approach 2:
The gate structure fabrication is segmented into distinct phases: first forming the dummy polysilicon gate structure, then selectively replacing portions with metal gate material. This segmentation allows each phase to be optimized independently, managing the complexity of decreased feature sizes by breaking the process into manageable stages.
Data Source
AI summary
Provided are devices with replacement structures. A device includes a semiconductor structure and an isolation adjacent to the semiconductor structure, wherein the isolation includes a first region having an upper surface at a first height, wherein the isolation includes a second region having an upper surface at a second height, wherein the first height is equal to the second height plus 3 to 20 nanometers (nm); a conductive gate located over the semiconductor structure and over the first region of the isolation at the first height; and a source/drain region located over the second region of the isolation at the second height.