Rounded Deep Trench Isolation for Compact BCD Layouts
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Solution Overview
Problem
Integrating different types of semiconductor devices on a single chip, such as BCD devices, poses challenges due to the need for significant space in the chip design layout to provide electrical isolation between components operating at different voltages, which increases the overall BCD layout area and reduces available space for additional logic devices.
Innovation Solution
A single, continuous deep trench isolation structure with rounded corners and intersections is used to electrically isolate BCD layout areas, reducing the required layout area and minimizing sidewall oxide thickness asymmetry, thereby protecting low-voltage devices from high-voltage components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional isolation structures are used to electrically isolate BCD layout areas, then electrical isolation between high-voltage and low-voltage components is achieved, but the layout area increases significantly
Solution Approach 1:
The patent transitions from planar isolation structures to three-dimensional deep trench isolation structures that extend vertically into the substrate. By utilizing the depth dimension, the isolation effectiveness is enhanced while the horizontal footprint is reduced, allowing compact layout of BCD devices.
Solution Approach 2:
The deep trench isolation structures are positioned to define and surround BCD layout areas, with trenches located at strategic positions such as corners and along perimeters. This nested arrangement maximizes isolation efficiency within minimal layout space.
2Ease of manufacture
If deep trench isolation structures with sharp corners are used, then manufacturing is simpler, but sidewall oxide thickness asymmetry increases causing electrical isolation issues
Solution Approach 1:
The patent specifies that deep trench isolation structures should have rounded corners with a minimum radius of curvature (e.g., 0.5 micrometers). This curvature ensures uniform sidewall oxide thickness during thermal oxidation processes, preventing electrical isolation failures while remaining compatible with standard manufacturing capabilities.
3Reliability
If more isolation structures are added to protect low-voltage devices, then electrical protection improves, but device complexity and layout area increase
Solution Approach 1:
The deep trench isolation structures serve multiple functions simultaneously: they provide electrical isolation between high-voltage and low-voltage regions, define BCD layout area boundaries, and prevent substrate breakdown. This multi-functionality reduces the need for additional dedicated protection structures, simplifying the overall device design.
Data Source
AI summary
Devices and methods of manufacture for a deep trench layout area-saving semiconductor structure for use with bipolar-CMOS-DMOS (BCD) devices. A semiconductor device may comprise a first BCD device formed within a first perimeter of a first BCD layout area, and a deep trench isolation structure defining the first perimeter of the first BCD layout area, in which the deep trench isolation structure may comprise a first rounded corner that may define a first corner of the first BCD layout area. A semiconductor device may comprise, a substrate, BCD device formed on the substrate, and a deep trench isolation structure laterally surrounding the BCD device. The deep trench isolation structure, with respect to a top-down view, may comprise vertical portions, horizontal portions, a âTâ-shaped intersection connecting at least one vertical portion and at least one horizontal portion, and a cross-shaped intersection connecting two vertical portions and two horizontal portions.