Semiconductor Resistance Element with Opposing Layer Fluctuations
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Solution Overview
Problem
The existing trimming circuits in semiconductor devices face significant resistance value fluctuations due to package stress and heat treatment, affecting the accuracy of oscillation frequency, which is not adequately addressed by current technologies.
Innovation Solution
A resistance element structure is implemented with a repeating pattern of conductive layers and interlayer connections, where the resistance value fluctuations of the lower and upper conductive layers are opposite in nature, effectively canceling out fluctuations caused by aging and package stress, using polysilicon wiring with salicide for the lower layer and aluminum-based wiring for the upper layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polysilicon resistor is used in the trimming circuit, then high resistance can be realized in a small area with a simple manufacturing process, but the resistance value fluctuates during the manufacturing process and after packaging
Solution Approach 1:
The patent uses a composite structure combining polysilicon resistor and metal resistor in series. The polysilicon resistor provides high resistance in small area, while the metal resistor compensates for resistance fluctuations caused by packaging stress and manufacturing variations, achieving stable total resistance without significantly increasing device complexity
Solution Approach 2:
The patent changes the resistance value parameters of individual resistors based on their fluctuation characteristics. By selecting specific resistance values for polysilicon and metal resistors that account for their opposite fluctuation behaviors, the total resistance remains stable despite individual variations
2Reliability
If a single-layer resistance element is used, then the structure is simple, but resistance value fluctuates due to package stress and heat treatment
Solution Approach 1:
The patent creates a composite resistance element with polysilicon and metal resistors connected in series across different wiring layers. This multi-material structure exploits the opposite stress sensitivity of each material to cancel out packaging stress effects, improving reliability while accepting moderate structural complexity
Solution Approach 2:
The patent transitions from a single-layer to a multi-layer structure, utilizing vertical stacking of wiring layers. The polysilicon resistor is formed in one wiring layer while the metal resistor is formed in another layer, with vias connecting them, thereby solving the stability problem through dimensional expansion
3Manufacturing precision
If the resistance element is made more complex to reduce fluctuations, then resistance stability improves, but the manufacturing process becomes more complicated
Solution Approach 1:
The patent combines polysilicon and metal resistors using standard semiconductor manufacturing processes. Both resistor types can be formed using existing deposition and patterning techniques, and their series connection is achieved through常规 via formation, maintaining ease of manufacture while improving resistance consistency
Solution Approach 2:
The patent divides the resistance element into separate polysilicon and metal resistor segments formed in different wiring layers. This segmentation allows each segment to be optimized independently for its specific function while being integrated through standard interlayer via processes
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 solution significantly reduces resistance value fluctuations, enhancing the accuracy of oscillation frequency and improving the reliability of semiconductor devices by minimizing the impact of aging and package stress on the resistance element.
Implementation Method 1
a first conductive layer formed on a first wiring layer on a semiconductor substrate; a second conductive layer formed on a second wiring layer different from the first wiring layer; and an interlayer conductive layer connecting the first conductive layer and the second conductive layer, and the first conductive layer has a resistance-value fluctuation characteristic opposite to a resistance-value fluctuation characteristic of the second conductive layer after a heat treatment
Data Source
AI summary
A resistance element includes a conductor, the conductor having a repeating pattern of: a first conductive layer formed on a first interlayer insulating layer on a semiconductor substrate; a second conductive layer formed on a second interlayer insulating layer different from the first interlayer insulating layer; and an interlayer conductive layer connecting the first conductive layer and the second conductive layer, and the second conductive layer has a resistance-value fluctuation characteristic opposite to a resistance-value fluctuation characteristic of the first conductive layer after a heat treatment.