Insulating Cover Film for Semiconductor Layer Isolation
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Solution Overview
Problem
Forming multiple types of semiconductor layers in a single layer can lead to contact between them, potentially altering their characteristics and affecting transistor performance.
Innovation Solution
A semiconductor device with a multilayer interconnect structure, where each transistor has a distinct semiconductor layer and gate insulating film, with an insulating cover film preventing direct contact between layers, allowing for independent control of transistor characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple types of semiconductor layers are formed in one identical layer, then the degree of freedom in circuit design is improved, but the characteristics of the semiconductor layers may change due to contact between layers
Solution Approach 1:
An insulating cover film is introduced as an intermediary layer between the first semiconductor layer and the second semiconductor layer. This cover film prevents direct contact between the two semiconductor layers, thereby maintaining their respective characteristics while allowing both types of transistors to coexist in the same interconnect layer, thus resolving the contradiction between design flexibility and layer characteristic stability.
2Reliability
If an insulating cover film is formed over the first semiconductor layer, then contact between semiconductor layers is prevented, but the device structure becomes more complex
Solution Approach 1:
The insulating cover film serves multiple functions: it acts as a barrier to prevent contact between semiconductor layers, provides insulation, and serves as part of the gate insulating film structure for the second transistor. By making the cover film multi-functional, the patent reduces the need for additional separate layers, thereby mitigating the increase in device complexity while maintaining reliability.
Data Source
AI summary
An interlayer insulating film is formed. Then a first gate electrode and a second gate electrode are buried in the interlayer insulating film. Then, an anti-diffusion film is formed over the interlayer insulating film, over the first gate electrode, and over the second gate electrode. Then, a first semiconductor layer is formed over the anti-diffusion film which is present over the first gate electrode. Then, an insulating cover film is formed over the upper surface and on the lateral side of the first semiconductor layer and over the anti-diffusion film. Then, a semiconductor film is formed over the insulating cover film. Then, the semiconductor film is removed selectively to leave a portion positioned over the second gate electrode, thereby forming a second semiconductor layer.