Polysilicon Triggered SCR Holding Voltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional silicon-controlled rectifiers (SCRs) face challenges in increasing holding voltage without raising trigger voltage, leading to potential latch-up and decreased ESD capability due to current crowding and increased trigger voltage when connected in series.
Innovation Solution
A polysilicon resistance triggered stack SCR structure is developed, featuring disconnected fields and doped regions with varying ion doses, which separates maximum electric field and current density, maintaining current value at second breakdown and increasing holding voltage without elevating trigger voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional schemes are used to increase holding voltage, then holding voltage is improved, but trigger voltage increases and ESD capability decreases
Solution Approach 1:
The patent segments the doped regions into multiple discrete zones with progressively increasing ion doses. The segmented second-type doped region and segmented first-type doped region create distinct current paths that prevent current crowding while maintaining high holding voltage. This segmentation allows the electric field and current density to be distributed across multiple locations rather than concentrated in a single area.
Solution Approach 2:
The patent applies local quality by creating doped regions with different ion doses at different locations. The entire first-type doped region has a higher ion dose than the first-type field, which in turn has a higher ion dose than the first-type well. Similarly, the segmented second-type doped region has higher ion dose than the second-type first field. This gradient in local doping quality enables precise control of electric field distribution and current density throughout the device structure.
2Strength
If SCRs are connected in series to increase holding voltage, then holding voltage increases proportionally, but trigger voltage also increases proportionally
Solution Approach 1:
The patent changes the doping parameters (ion dose) to achieve the desired voltage characteristics. By increasing the ion dose of the entire first-type doped region relative to the first-type field, and increasing the ion dose of the segmented second-type doped region relative to the second-type first field, the patent adjusts the electrical parameters to maintain low trigger voltage while achieving high holding voltage through the series connection of multiple SCR units.
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 enhances holding voltage while maintaining or reducing trigger voltage, preventing latch-up and maintaining ESD capability, even when SCRs are connected in series, by utilizing polysilicon resistance to adjust trigger voltage proportionally with the number of SCRs.
Implementation Method 1
polysilicon resistance triggered stack SCR structure... utilizing polysilicon resistance to adjust trigger voltage proportionally with the number of SCRs
Implementation Method 2
doped regions with varying ion doses... Ion dose of the entire first-type doped region is greater than ion dose of the first-type field, ion dose of which is further greater than ion dose of first-type well
Data Source
AI summary
A silicon-controlled rectifier (SCR) includes a first-type field, a second-type first field and a second-type second field disconnectedly formed in a first-type well; an entire first-type doped region formed within the first-type field; a segmented second-type doped region formed within the second-type first field; and a segmented first-type doped region formed within the second-type second field.