Sacrificial Pillar Dielectric Platform for RF Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor devices formed on conductive silicon substrates face issues with low quality factors and reduced frequency of operation due to parasitic capacitive coupling, leading to limitations in output power and isolation.
Innovation Solution
A semiconductor structure with an embedded dielectric platform that reduces parasitic capacitance by incorporating voids and dielectric materials with a low dielectric constant, providing electrical isolation and increasing the distance between passive components and the substrate, thereby enhancing frequency and breakdown voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If passive devices are formed on conductive silicon substrate, then device integration is achieved, but quality factor decreases due to parasitic capacitive coupling
Solution Approach 1:
A dielectric platform is introduced as an intermediary layer between the passive devices and the conductive silicon substrate. This dielectric platform has a dielectric constant of less than 4.0 and includes voids to reduce parasitic capacitive coupling, thereby improving the quality factor of passive devices while maintaining their integration on the silicon substrate.
Solution Approach 2:
The dielectric platform incorporates voids (air pockets) within its structure to reduce the effective dielectric constant below 4.0. These voids minimize the parasitic capacitance between passive devices and the substrate, enabling high-quality factor passive devices to be formed on conductive silicon substrates for RF applications.
2Area of stationary object
If passive devices are placed close to conductive substrate, then area is reduced, but frequency of operation decreases due to parasitic capacitance
Solution Approach 1:
The dielectric platform serves as a mediator that allows passive devices to be placed close to the substrate while maintaining high frequency of operation. The low dielectric constant material reduces parasitic capacitance, enabling compact device layouts without sacrificing operating frequency for RF applications.
3Productivity
If interconnects are placed close to conductive substrate, then routing density is improved, but frequency of operation is reduced by parasitic capacitive coupling
Solution Approach 1:
The dielectric platform acts as an intermediary layer beneath the interconnects, reducing parasitic capacitive coupling between the interconnects and the conductive silicon substrate. This enables high routing density while maintaining high frequency of operation for RF signal transmission.
4Reliability
If dielectric platform with voids is formed, then parasitic capacitance is reduced, but manufacturing complexity increases
Solution Approach 1:
The dielectric platform is formed with voids using a multi-step process: forming a sacrificial layer, depositing dielectric material, selectively removing portions of the dielectric material to create voids, and removing the sacrificial layer. This controlled approach achieves low effective dielectric constant while managing manufacturing complexity through standardized semiconductor processing techniques.
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
The dielectric platform effectively reduces parasitic capacitance, increases the frequency of operation, and enables the formation of high-quality passive devices with higher breakdown voltages, while minimizing thermal stress and leakage currents.
Implementation Method 1
parasitic capacitive coupling between these passive devices and the conductive silicon substrate
Implementation Method 2
dielectric materials with a low dielectric constant
Data Source
AI summary
Briefly, in accordance with one or more embodiments, a dielectric platform is at least partially formed in a semiconductor substrate and extending at least partially below a surface of a semiconductor substrate. The dielectric platform may include structural pillars formed by backfilling a first plurality of cavities etched in the substrate, and a second plurality of cavities formed by etching away sacrificial pillars disposed between the structural pillars. The second plurality of cavities may be capped to hermetically seal the second plurality of cavities to impart the dielectric constant of the material contained therein, for example air, to the characteristic dielectric constant of the dielectric platform. Alternatively, the second plurality of cavities may be backfilled with a material having a lower dielectric constant than the substrate, for example silicon dioxide where the substrate comprises silicon.