Localized Trap-Rich Substrate for Low-Distortion RF ICs
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Solution Overview
Problem
Current silicon-on-insulator (SOI) substrates, particularly fully depleted SOI (FD-SOI) substrates, face issues with parasitic surface conduction and harmonic distortion due to fixed electric charges in the buried insulating layer, which affect radiofrequency integrated circuits, and the production of trap-rich regions to mitigate these issues often results in surface roughness detrimental to integrated circuit operation.
Innovation Solution
A substrate with a trap-rich region localized to specific domains containing radiofrequency components, where the semiconductor film and buried insulating layer do not extend, allowing for the reduction of harmonic distortion and crosstalk while maintaining a smooth surface finish by using a polycrystalline semiconductor layer and an interface zone with a different crystal structure in the radiofrequency domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trap-rich region is produced in the substrate to reduce parasitic surface conduction and harmonic distortion, then the electrical performance of radiofrequency components is improved, but surface roughness is generated that is detrimental to integrated circuit operation
Solution Approach 1:
The patent applies local quality by creating trap-rich regions only in specific domains containing radiofrequency components, while leaving domains with non-radiofrequency components free of such regions. This localized approach allows the substrate to have different properties in different areas: trap-rich regions for RF components to reduce parasitic effects, and smooth regions for non-RF components to maintain manufacturing precision and avoid surface roughness issues.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively limits harmonic distortion and crosstalk in radiofrequency components without affecting the surface roughness of the semiconductor film, ensuring correct operation of non-radiofrequency components and maintaining the integrity of the substrate's surface finish.
Implementation Method 1
a high density of surface states liable to trap free charge carriers. This trapping of free charge carriers with surface states greatly decreases the parasitic surface-conduction effect
Implementation Method 2
at least one interface zone in the internal wall of said trench, said interface zone having a different structure from the crystal structure of said polycrystalline semiconductor layer and from the crystal structure of said subjacent portion of the substrate
Data Source
AI summary
An integrated circuit includes a substrate having at least one first domain and at least one second domain that is different from the at least one first domain. A trap-rich region is provided in the substrate at the locations of the at least one second domain only. Locations of the at least one first domain do not include the trap-rich region.