MOS Device ESD Protection via Segmented SCR Triggering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional ESD protection devices using silicon controlled rectifiers (SCRs) require higher trigger voltages, making them difficult to activate, which can result in device damage before effective ESD protection is achieved, leading to ineffective ESD protection and potential hot spots.
Innovation Solution
A MOS device structure incorporating a substrate, gate, heavily doped regions, and electrodes forms a silicon controlled rectifier (SCR) path without an ESD clamp circuit, allowing for even current distribution and improved ESD protection by activating the SCR at lower voltages, preventing hot spots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a silicon controlled rectifier (SCR) is used for ESD protection without an ESD clamp circuit, then the device complexity is reduced, but the trigger voltage increases making it difficult to activate
Solution Approach 1:
The patent segments the SCR structure into distinct doped regions (first-type first heavily doped region, first-type drift region, second-type first heavily doped region) with specific doping concentrations and geometries. This segmentation allows optimization of each region's properties to achieve lower trigger voltage while maintaining the simplified circuit architecture without ESD clamp.
Solution Approach 2:
The patent applies local quality by creating heavily doped regions with specific doping concentrations (e.g., 1E19 to 1E21 atoms/cm³) in specific locations within the SCR structure. The first-type first heavily doped region is heavily doped to reduce resistance and facilitate earlier breakdown, while the drift region maintains appropriate doping for voltage blocking, achieving localized optimization of trigger characteristics.
2Reliability
If the SCR trigger voltage is reduced for easier activation, then the ESD protection becomes more effective, but the device may become more complex requiring additional structures
Solution Approach 1:
The patent changes physical parameters of the SCR structure, specifically doping concentrations and geometric dimensions. The first-type first heavily doped region uses doping concentrations of 1E19 to 1E21 atoms/cm³ and specific width (0.5 to 5.0 micrometers) to reduce breakdown voltage. The contact geometry is also optimized to be the closest contact to the gate, creating favorable electric field distribution for lower trigger voltage without adding structural complexity.
Solution Approach 2:
The patent performs preliminary action by pre-doping specific regions with appropriate doping concentrations before final device formation. The first-type first heavily doped region is prepared with high doping concentration to create favorable conditions for early breakdown and trigger activation, ensuring the SCR activates at lower voltages while maintaining a relatively simple overall structure.
3Strength
If conventional ESD protection structures are used, then the trigger voltage is higher providing better voltage blocking, but the activation delay causes device damage before protection engages
Solution Approach 1:
The patent applies local quality by creating a heavily doped first-type first heavily doped region with doping concentrations of 1E19 to 1E21 atoms/cm³ in a specific location within the SCR structure. This localized heavy doping reduces the breakdown voltage at that specific region, enabling earlier trigger activation and current sharing before device damage occurs, while other regions maintain appropriate doping for voltage blocking capability.
Solution Approach 2:
The patent changes the doping concentration parameter in the first-type first heavily doped region to 1E19 to 1E21 atoms/cm³, which is higher than conventional structures. This parameter change reduces the electric field strength required for breakdown, enabling trigger activation at lower voltages and earlier timing during ESD events, improving device survival while maintaining voltage blocking through other structured regions.
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 MOS device effectively provides excellent ESD protection by distributing current evenly, avoiding hot spots and meeting high ESD standards without the need for an ESD clamp circuit, as demonstrated by meeting specific ESD specifications in human body and machine models.
Implementation Method 1
ESD is a phenomenon in which charges are accumulated on a non-conductor or a non-grounded conductor and then suddenly transfer and discharge through a discharge path
Implementation Method 2
The second-type first heavily doped region is disposed in the first-type drift region. The contact is electrically connected to the second-type first heavily doped region
Data Source
AI summary
Provided is a metal oxide semiconductor device, including a substrate, a gate, a first-type first heavily doped region, a first-type drift region, a second-type first heavily doped region, a contact, a first electrode, and a second electrode. The gate is disposed on the substrate. The first-type first heavily doped region is disposed in the substrate at a side of the gate. The first-type drift region is disposed in the substrate at another side of the gate. The second-type first heavily doped region is disposed in the first-type drift region. The contact is electrically connected to the second-type first heavily doped region. The contact is the closest contact to the gate on the first-type drift region. The first electrode is electrically connected to the contact, and the second electrode is electrically connected to the first-type first heavily doped region and the gate.