Semiconductor Resistors Above Isolation for Low Parasitic Capacitance
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Solution Overview
Problem
In advanced integrated circuits, the reduction in transistor size leads to increased parasitic capacitance in resistive structures formed within the active semiconductor layer, causing performance issues and inefficiencies in chip area usage, while conventional approaches to form resistors above isolation structures result in patterning complexities and increased capacitance.
Innovation Solution
The formation of semiconductor-based resistive structures above isolation structures using a high-k metal gate stack with a semiconductor material, where the semiconductor material is preserved in the resistive structures and selectively replaced in the gate electrode structures, allowing for enhanced capacitive behavior without additional process complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If resistive structures are formed within the active semiconductor layer, then the chip area usage is efficient, but parasitic capacitance increases causing performance issues
Solution Approach 1:
The patent moves resistive structures from the planar active semiconductor layer into the vertical dimension by forming them above isolation structures. This dimensional transition allows resistors to occupy previously unused vertical space above the isolation structures, maintaining efficient chip area usage while physically separating them from the active transistor regions to reduce parasitic capacitance coupling.
2Object-generated harmful factors
If resistors are formed above isolation structures, then parasitic capacitance is reduced, but patterning complexities and increased capacitance occur
Solution Approach 1:
The patent combines the formation of resistive structures with the existing metal gate stack formation process. The same high-k dielectric material deposition and semiconductor material processing steps used for creating metal gate electrodes are also used to form the resistive structures above isolation structures, merging two functions into a unified process sequence that reduces overall patterning complexity.
Solution Approach 2:
The high-k metal gate stack materials and processes are designed to serve dual functions: forming the gate electrode structures for transistors and simultaneously forming the resistive structures above isolation structures. This multi-functionality approach allows a single process sequence to accomplish multiple objectives, reducing the need for additional specialized patterning steps.
3Reliability
If semiconductor material is replaced in gate electrode structures, then transistor performance is enhanced, but resistive structure formation becomes complex
Solution Approach 1:
The patent applies selective material replacement strategy where semiconductor material is replaced by metal materials specifically in the gate electrode regions to enhance transistor performance, while the semiconductor material is preserved in the resistive structure regions above isolation structures. This localized differentiation allows optimal material selection for each functional region without requiring complex global processing changes.
Data Source
AI summary
In a semiconductor device comprising sophisticated high-k metal gate structures formed in accordance with a replacement gate approach, semiconductor-based resistors may be formed above isolation structures substantially without being influenced by the replacement gate approach. Consequently, enhanced area efficiency may be achieved compared to conventional strategies, in which the resistive structures may have to be provided on the basis of a gate electrode metal, while, nevertheless, a low parasitic capacitance may be accomplished due to providing the resistive structures above the isolation structure.