Asymmetric Current Path Lengths in Temperature Sensing Diodes
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Solution Overview
Problem
Conventional temperature sensing diodes in semiconductor devices face accuracy issues due to variations in parasitic resistance, which affect the accuracy of temperature detection using the temperature dependency of forward voltage drop (Vf).
Innovation Solution
The semiconductor device incorporates a cathode region and an anode region with a pn junction, where the length of the current path in the region with a higher sheet resistance is shorter, and the current paths are optimized to satisfy the ratio 0.1 <= Lnx/Lpx <= 0.9, reducing parasitic resistance and improving temperature detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ion implantation is used to form n-type and p-type regions in the temperature sensing diode, then the diode can detect temperature through forward voltage drop characteristics, but the parasitic resistance varies due to channeling phenomenon and dose variation, reducing detection accuracy
Solution Approach 1:
The patent applies local quality by creating asymmetric current path lengths in the n-type and p-type regions. Specifically, the current path length in the n-type region (Ln) is made different from the current path length in the p-type region (Lp), with the ratio Ln/Lp controlled within 0.1 to 0.9. This local structural differentiation compensates for the non-uniform impurity distribution caused by channeling, stabilizing the parasitic resistance and improving temperature detection accuracy.
Solution Approach 2:
The patent changes the geometric parameters of the diode structure, specifically the current path lengths in the n-type and p-type regions. By controlling the ratio Ln/Lp within a specific range (0.1 to 0.9), the patent optimizes the balance between the voltage drops across the two regions, compensating for parasitic resistance variations and improving measurement precision.
2Measurement precision
If the current path lengths in n-type and p-type regions are equal, then the structure is symmetric and simple to manufacture, but the forward voltage drop varies significantly due to parasitic resistance, reducing temperature sensing accuracy
Solution Approach 1:
The patent deliberately introduces asymmetry into the diode structure by making the current path length in the n-type region (Ln) different from the current path length in the p-type region (Lp). The ratio Ln/Lp is controlled within 0.1 to 0.9, creating an asymmetric configuration that compensates for parasitic resistance effects and stabilizes the forward voltage drop, thereby improving temperature sensing accuracy despite the increased structural complexity.
3Reliability
If higher dose of n-type impurity ions is used to form the n-type region, then the n-type region can be properly formed by compensating p-type ions, but the sheet resistance of the n-type region becomes higher and more variable, increasing parasitic resistance
Solution Approach 1:
The patent applies local quality by differentiating the current path lengths in the n-type and p-type regions. By making the current path length in the n-type region (Ln) shorter relative to the p-type region (Lp), with the ratio Ln/Lp controlled within 0.1 to 0.9, the patent compensates for the higher and more variable sheet resistance in the n-type region, thereby reducing the overall parasitic resistance and improving manufacturing precision.
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 enhances the accuracy of temperature detection by minimizing the variation of forward voltage drop (Vf), leading to improved temperature sensing capabilities.
Implementation Method 1
The temperature sensing diode 500 detects the temperature of the semiconductor chip by using the temperature characteristics of forward voltage drop Vf
Implementation Method 2
At the ion implantation into the polysilicon layer 58, some of the implanted impurity ions penetrate the polysilicon layer 58 by the channeling phenomenon
Implementation Method 3
some of the implanted impurity ions penetrate the polysilicon layer 58 by the channeling phenomenon (the range of ion implantation into polysilicon is longer than the range of ion implantation into a monocrystal)
Data Source
AI summary
A semiconductor device includes: an interlayer insulating film covering: a cathode region and an anode region to form a pn junction with each other; a cathode electrode provided on the interlayer insulating film and connected to the cathode region through a first contact hole; and an anode electrode provided on the interlayer insulating film and connected to the anode region through a second contact hole. Among current paths in the cathode and anode regions, the current path in one of the cathode and anode regions that has a larger sheet resistance is shorter than the other current path, the current path in the cathode region extending from an interface of the pn junction to an end of the first contact hole closest to the interface, the current path in the anode region extending from the interface to an end of the second contact hole closest to the interface.