Temperature Sensing Diode Layout With Bidirectional ESD Protection
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Solution Overview
Problem
Conventional semiconductor devices with protective diodes between MOSFETs and temperature detecting diodes face challenges in effectively protecting the temperature sensing units from electro-static discharge (ESD) and maintaining their temperature sensing characteristics, while also requiring efficient downsizing and reliable operation.
Innovation Solution
Incorporating a bidirectional diode unit arranged between the anode and cathode pads, which includes Zener diodes connected in a serial bidirectional manner to provide quick ESD protection and maintain the temperature sensing unit's integrity, and an output comparison diode unit connected in inverse parallel to the temperature sensing diode for timely replacement detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective diode is provided between MOSFET and temperature detecting diode, then the temperature sensing unit is protected from overvoltage, but the device size increases and ESD protection effectiveness is reduced
Solution Approach 1:
The protective diode and temperature detecting diode are merged into a single integrated structure where the P-type well serves as the anode for both the protective diode and the temperature detecting diode. This combining of functions into one shared structure reduces the overall device area while maintaining protection effectiveness.
Solution Approach 2:
The P-type well region serves multiple functions simultaneously: it acts as the anode for the protective diode, the anode for the temperature detecting diode, and provides ESD protection capability. This multi-functionality eliminates the need for separate protective structures, thereby reducing device area.
2Reliability
If a protective diode is provided between MOSFET and temperature detecting diode, then overvoltage protection is achieved, but ESD protection effectiveness is reduced due to slow response
Solution Approach 1:
The patent employs a dynamic protection mechanism where the protective diode responds differently to different types of voltage stress. For ESD events, the diode's low reverse breakdown voltage enables rapid response. For normal overvoltage conditions, the diode provides steady protection. This dynamic behavior optimizes both ESD response speed and overvoltage protection.
Solution Approach 2:
The protective diode is designed with specific parameter characteristics: a low reverse breakdown voltage (5V or less) and low reverse saturation current. These parameter changes enable the diode to respond quickly to ESD events while maintaining effective overvoltage protection, resolving the contradiction between response speed and protection capability.
3Reliability
If temperature sensing unit is protected from ESD, then sensing characteristics are maintained, but device complexity increases
Solution Approach 1:
The protective diode and temperature detecting diode share common structures including the P-type well and N-type diffusion layer. This merging of protective and sensing functions into a single integrated diode structure maintains temperature sensing characteristics while avoiding the complexity of separate protective components.
Solution Approach 2:
The integrated diode structure performs multiple functions: ESD protection, overvoltage protection, and temperature sensing. By making one structure universal, the patent avoids increasing device complexity while maintaining all required functions including temperature sensing characteristics.
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 solution effectively protects the temperature sensing unit from ESD, maintains its characteristics, allows for downsizing of the semiconductor device, and ensures reliable operation by quickly performing Zener operations and enabling timely replacement of the temperature sensing diode.
Implementation Method 1
a bidirectional diode unit which includes Zener diodes connected in a serial bidirectional manner so as to provide quick ESD protection
Implementation Method 2
temperature sensing unit that includes a temperature sensing diode
Data Source
AI summary
A semiconductor device including: a semiconductor substrate; a temperature sensing unit provided on a front surface of the semiconductor substrate; an anode pad and a cathode pad electrically connected with the temperature sensing unit; a front surface electrode being set to a predetermined reference potential; and a bidirectional diode unit electrically connected in a serial bidirectional way between the cathode pad and the front surface electrode is provided. The output comparison diode unit may be arranged between the anode pad and the cathode pad. The temperature sensing unit may include a temperature sensing diode, and the output comparison diode unit may include a diode connected in inverse parallel to the temperature sensing diode.