Semiconductor Resistor Doped Well Parasitic Capacitance
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Solution Overview
Problem
Resistors in semiconductor devices, particularly in ICs, face self-heating issues due to being formed on insulators, leading to non-linear behavior and distortion in AC signals, especially in higher power and AC applications, where effective heat dissipation is lacking.
Innovation Solution
A resistor structure is designed with a doped well in a semiconductor layer, featuring a dopant concentration gradient, which reduces parasitic capacitance and enhances heat dissipation, allowing for the use of thinner dielectric layers that minimize impedance to heat transfer, and can be integrated with existing fabrication processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resistors are formed on insulator material to reduce parasitic capacitance, then parasitic capacitance is reduced, but heat dissipation capability deteriorates causing self-heating
Solution Approach 1:
The insulator layer is segmented into multiple thinner insulator layers separated by semiconductor layers. This segmentation allows heat to dissipate through the semiconductor layers while maintaining the electrical insulation function, thus resolving the contradiction between reducing parasitic capacitance and improving heat dissipation.
Solution Approach 2:
Semiconductor layers are introduced as intermediary layers between the insulator layers. These intermediary semiconductor layers serve as thermal pathways for heat dissipation while the insulator layers maintain electrical isolation, thus mediating between the conflicting requirements of low parasitic capacitance and effective heat dissipation.
2Temperature
If thicker dielectric layers are used to improve heat dissipation, then heat dissipation improves, but impedance to heat transfer increases
Solution Approach 1:
Different layers are assigned different thermal properties: insulator layers provide electrical isolation while semiconductor layers provide thermal conduction pathways. This local differentiation of material properties allows the structure to achieve both heat dissipation and low thermal impedance simultaneously.
Solution Approach 2:
The resistor structure uses a composite arrangement of insulator layers and semiconductor layers. This composite structure combines the electrical insulation properties of dielectric materials with the thermal conduction properties of semiconductor materials, achieving both heat dissipation and low thermal impedance.
3Power
If resistors operate at higher power levels, then power handling capability improves, but distortion increases due to self-heating
Solution Approach 1:
The segmented structure with alternating insulator and semiconductor layers provides multiple thermal pathways for heat dissipation. This enables the resistor to operate at higher power levels by efficiently conducting heat away from the resistive elements, thereby preventing self-heating-induced distortion while maintaining high power handling capability.
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 structure enables operation at higher power levels with reduced distortion, maintaining heat transfer capabilities while reducing parasitic capacitance and impedance, thus improving performance in higher power and AC applications.
Implementation Method 1
a type of the first dopant and at least one concentration of the first dopant being selected to provide a depletion region in the well at an operating voltage of the resistor structure
Implementation Method 2
resistors formed on insulators are subject to self-heating... it would therefore be advantageous to have resistor structures with improved heat dissipation
Data Source
AI summary
A resistor body is separated from a doped well in a substrate by a resistor dielectric material layer. The doped well is defined by at least one doped region and can include a dopant gradient in the doped well to reduce parasitic capacitance of the resistor structure while retaining heat dissipation properties of the substrate. The resistor body is formed in a cavity in a dielectric layer deposited on the substrate, which deposition can be part of a concurrent fabrication, such as part of forming shallow trench isolations, and the cavity can be lined with the resistor dielectric material.