Semiconductor Device Latch-Up Prevention via Segmented Buried Layer
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Solution Overview
Problem
The latch-up effect in CMOS devices due to parasitic Silicon Controlled Rectifier (SCR) components causes unintended high-current generation, leading to device damage, necessitating a solution to prevent this occurrence.
Innovation Solution
The semiconductor device design includes a P-type substrate, N-type region, P+ doped regions, a P-type buried layer, and a N-type doped region, with epitaxial layers and isolation structures to form isolated PMOS devices, which prevent the formation of parasitic SCR components by ensuring the lower surface of high-voltage N-type well regions are not in direct contact with the substrate, and guard rings are used to eliminate SCR paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the N-type well region is directly formed on the P-type substrate, then the device structure is simple, but the parasitic SCR component is triggered causing latch-up effect
Solution Approach 1:
The patent divides the direct contact interface between N-type well region and P-type substrate into separate segments by introducing a P-type buried layer and a N-type doped region. This segmentation breaks the continuous parasitic SCR path, preventing latch-up while maintaining structural organization.
Solution Approach 2:
The patent introduces a P-type buried layer as an intermediary between the N-type well region and the P-type substrate. This intermediary layer acts as a barrier that disrupts the parasitic SCR formation, preventing the latch-up effect without requiring complete redesign of the device structure.
2Reliability
If guard rings are added to eliminate SCR paths, then latch-up is prevented, but device complexity increases
Solution Approach 1:
The patent merges the latch-up prevention function into the existing device structure by integrating the P-type buried layer and N-type doped region with the N-type well region formation process. This merging approach eliminates the need for separate guard ring structures while achieving the same protective effect.
Solution Approach 2:
The P-type buried layer serves multiple functions: it acts as a barrier to prevent parasitic SCR formation, provides structural support, and maintains the electrical characteristics of the device. This multi-functionality reduces the need for additional dedicated latch-up prevention structures.
3Ease of manufacture
If the lower surface of N-type well region contacts the substrate, then manufacturing is easier, but high-current damage occurs due to latch-up
Solution Approach 1:
The patent applies preliminary action by forming the P-type buried layer before creating the N-type well region. This preliminary structure is already in place to prevent parasitic SCR formation, ensuring that subsequent manufacturing steps can proceed without risk of latch-up while maintaining ease of manufacture.
Data Source
AI summary
A semiconductor device, including: a P-type substrate; an N-type region, contacting with the P-type substrate; a N+-type doped region, disposed in the N-type region; a first P+-type doped region, disposed in the N-type region; a second P+-type doped region, disposed in the N-type region; a P-type buried layer, disposed in the P-type substrate under the N-type region and contacting with the N-type region; and a N-type doped region, disposed in the P-type substrate under a contact surface between the P-type buried layer and the N-type region.