Trench Structures for Lateral Dielectric Isolation in Integrated Circuits
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Solution Overview
Problem
Existing integrated circuits fail to achieve lateral dielectric separation of subregions of a buried layer under different active regions and can only contact one level of trench structures, limiting control over individual active regions with unique electrical properties.
Innovation Solution
The integrated circuit design features trench structures with first wall regions that completely cut through the buried layer and second wall regions that extend into the buried layer without cutting through, allowing for dielectric separation and individual electrical contact of buried layer regions, using a two-mask technique and selective filling with conductive or isolating materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If trench structures are used to electrically isolate active regions laterally, then lateral dielectric separation is achieved, but individual electrical contact of buried layer subregions cannot be achieved
Solution Approach 1:
The trench structure is segmented into two distinct parts: a first trench portion that extends through the active layer to the buried layer, and a second trench portion that extends further into the buried layer. This segmentation allows the first trench to provide lateral dielectric separation while the second trench enables individual electrical contact of buried layer subregions, resolving the contradiction between isolation and contact capability.
Solution Approach 2:
The invention transitions from a single-level trench structure to a multi-level trench structure with different depths. The first trench portion operates at one depth level for isolation, while the second trench portion extends to a greater depth for contact, utilizing the vertical dimension to achieve both functions simultaneously without interfering with each other.
2Ease of manufacture
If only one level of trench structure is used, then manufacturing is simpler, but control over multiple active regions with unique electrical properties is limited
Solution Approach 1:
The trench structure is divided into functionally distinct segments: the first trench portion for lateral isolation and the second trench portion for deep electrical contact. This segmentation enables independent control of multiple active regions with unique electrical properties while maintaining manufacturing feasibility through a systematic multi-step process.
Solution Approach 2:
The multi-level trench structure serves multiple functions: the first trench portion provides lateral dielectric separation, while the second trench portion enables individual electrical contact of buried layer subregions. This multi-functionality allows a single trench structure to control multiple active regions with unique electrical properties without requiring separate structures for each function.
3Area of stationary object
If tightly bordering trench structures are used to form extended buried layer, then buried layer coverage is improved, but high temperature processing is required
Solution Approach 1:
The second trench portion is nested within the structure defined by the first trench portion, extending further into the buried layer. This nesting approach allows extended buried layer coverage to be achieved through a controlled multi-step process rather than requiring tightly bordering trenches, thereby reducing the need for high temperature processing.
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 approach provides complete lateral dielectric isolation of active semiconductor regions, reducing sensitivity to interference and enabling the use of low-doped buried layers without parasitic capacitances, allowing for uniform electrical control of multiple layers and preventing the formation of parasitic components.
Implementation Method 1
dielectric wall regions, whereby the dielectric wall regions electrically isolate subregions of the layer, made of active semiconductor material, from one another in the lateral direction
Implementation Method 2
first inner regions, which are filled with electrically conductive material and contact the buried layer in an electrically conductive manner
Data Source
AI summary
An integrated circuit is disclosed that includes a first layer made of active semiconductor material and extending along a first side of a buried layer, and trench structures, which cut through the layer made of active semiconductor material and have dielectric wall regions, whereby the dielectric wall regions isolate electrically subregions of the layer, made of active semiconductor material in the lateral direction, and whereby the trench structures, furthermore, have first inner regions, which are filled with electrically conductive material and contact the buried layer in an electrically conductive manner. The integrated circuit is notable in that the first wall regions of the trench structures completely cut through the buried layer and the second wall regions of the trench structures extend into the buried layer, without cutting it completely. Furthermore, a method for manufacturing such an integrated circuit is disclosed.