Inverse-Parallel Diode Layout for ESD-Safe Temperature Sensing
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Solution Overview
Problem
Existing semiconductor devices face challenges in improving Electro-Static Discharge (ESD) withstand capability of protective diodes due to changes in diode characteristics when parameters like polysilicon thickness or diffuse layer concentration are adjusted, leading to potential degradation.
Innovation Solution
The semiconductor device incorporates a protective diode connected in inverse parallel to a temperature sensing diode, with a larger pn junction area and length compared to the temperature sensing diode, ensuring the protective diode's ESD withstand capability is enhanced without altering the peripheral structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the polysilicon is made thinner or the concentration of the diffuse layer is made lower to adjust temperature sensing characteristics, then the temperature sensing precision is improved, but the ESD withstand capability of the protective diode degrades due to increase in current density
Solution Approach 1:
The patent divides the protective diode structure into distinct regions: a first protective diode with a first pn junction area and a second protective diode with a second pn junction area. By segmenting the protective function across multiple diodes with different junction areas, the patent allows independent optimization of each diode's characteristics. The first protective diode can be designed with smaller junction area for precise temperature sensing, while the second protective diode has larger junction area for enhanced ESD withstand capability, thus resolving the contradiction between temperature sensing precision and ESD protection.
Solution Approach 2:
The patent applies local quality by creating different pn junction areas within the protective diode structure. The first protective diode has a first pn junction area optimized for temperature sensing characteristics, while the second protective diode has a second pn junction area optimized for ESD protection. This local differentiation allows each region to have tailored properties suited to its specific function, simultaneously achieving both temperature sensing precision and ESD withstand capability.
2Reliability
If the pn junction area of the protective diode is increased to improve ESD withstand capability, then the ESD withstand capability is improved, but the device area increases
Solution Approach 1:
The patent segments the protective diode into two distinct protective diodes with different pn junction areas. The first protective diode has a smaller pn junction area that can be integrated closely with the temperature sensing diode, while the second protective diode has a larger pn junction area dedicated to ESD protection. This segmentation allows the ESD protection function to be distributed across a larger area without compromising the compact integration of the temperature sensing function, thus improving ESD withstand capability while managing device area.
Solution Approach 2:
The patent addresses the area constraint by transitioning to a three-dimensional structure with multiple pn junctions at different vertical positions. The first and second protective diodes are formed with different thicknesses, creating pn junctions at different heights above the substrate. This vertical dimensionality allows the larger pn junction area of the second protective diode to be achieved without proportionally increasing the planar device area, as the additional junction area is distributed in the vertical dimension.
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 configuration effectively improves the ESD withstand capability of the protective diode, preventing breakdown and protecting the temperature sensing diode, while maintaining the integrity of the device's overall structure and performance.
Implementation Method 1
a protective diode provided on the semiconductor substrate and connected in inverse parallel to the temperature sensing diode
Implementation Method 2
The protective diode unit prevents breakdown when an overvoltage or an overcurrent flows in an inverse direction to the temperature sensing unit due to static electricity
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, a temperature sensing diode provided on the semiconductor substrate, and a protective diode provided on the semiconductor substrate and connected in inverse parallel to the temperature sensing diode, wherein the temperature sensing diode includes a first anode layer that is a p-type semiconductor layer, and a first cathode layer that is adjacent to the first anode layer in plan view and is an n-type semiconductor layer, the protective diode includes a second anode layer that is a p-type semiconductor layer, and a second cathode layer that is adjacent to the second anode layer in plan view and is an n-type semiconductor layer, and a pn junction area of the second anode layer and the second cathode layer in the protective diode is larger than a pn junction area of the first anode layer and the first cathode layer in the temperature sensing diode.