Low Capacitance Semiconductor Device Using BCB Passivation
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Solution Overview
Problem
Conventional methods to reduce parasitic capacitance in semiconductor diodes for RF circuits are costly and often impact other performance parameters, limiting their applicability, especially in packageless discrete diodes where manufacturing costs must be minimized.
Innovation Solution
A semiconductor device with a diode and a passivation layer featuring multiple consecutive layers of benzocyclobutene (BCB) material, which provides enhanced capacitive isolation between conductive layers, reducing capacitance while maintaining planarization and mechanical protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional methods such as air bridges or mesas are used to reduce capacitance coupling, then capacitance is reduced, but manufacturing costs increase and other performance parameters are impacted
Solution Approach 1:
The patent changes the dielectric parameter by using a low-k dielectric material with k<4.0 instead of conventional passivation materials. This parameter change reduces the capacitance coupling between metal layers while maintaining standard fabrication processes, thus lowering manufacturing costs compared to air bridges or mesas
Solution Approach 2:
The patent employs a composite structure combining low-k dielectric material with conventional passivation layers. This composite approach achieves capacitance reduction comparable to air bridges while maintaining the mechanical protection and planarization benefits of passivation layers, avoiding the complexity and cost of mesa structures
2Object-generated harmful factors
If isolation between metal layers is increased to reduce capacitive coupling, then capacitance is reduced, but device complexity and fabrication steps increase
Solution Approach 1:
The low-k dielectric layer serves multiple functions: it provides electrical isolation to reduce capacitive coupling, maintains planarization for subsequent processing, and offers mechanical protection. This multi-functionality achieves capacitance reduction without adding the fabrication complexity of air bridges or mesas
3Object-generated harmful factors
If conventional passivation materials are used, then planarization and mechanical protection are maintained, but capacitance coupling remains high
Solution Approach 1:
The patent changes the dielectric constant parameter by using low-k material with k<4.0, which directly reduces capacitance coupling while maintaining the planarization and mechanical protection functions of conventional passivation materials, thereby improving electrical isolation
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 use of BCB layers effectively minimizes capacitance, reducing signal and power loss in RF circuits while maintaining cost-effectiveness and improving electrical isolation, making it suitable for high-frequency applications.
Implementation Method 1
A top passivation layer formed of a material having a low dielectric constant k (i.e., low-k dielectric material) is positioned below a metallization layer
Implementation Method 2
The low-k material is spun on, for example, and thus provides planarization of the top surface of the diode device
Data Source
AI summary
A semiconductor device includes a diode, a passivation layer and a conductive layer. The diode includes an epitaxial layer on a semiconductor substrate, and first and second diode contacts on different planes. The passivation layer has a planar top surface, and includes multiple consecutive layers of a benzocyclobutene (BCB) material formed on the diode, an aggregate thickness of the passivation layer exceeding a thickness of the epitaxial layer. The conductive layer is formed on the top surface of passivation layer, the conductive layer connecting with the first and the second diodes contact through first and second openings in the passivation layer, respectively. The passivation layer enhances a capacitive isolation between the conductive layer and the diode.