Deep Contact Plug Structure for Planarization Without Guard Regions

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Solution Overview

Problem

Deep plugs in integrated devices face challenges in accurate planarization, leading to non-planarity and potential conductive residues on the chip surface, which interfere with component operation and require guard regions, wasting chip area.

Innovation Solution

The integration of shallow trenches filled with insulating material surrounds deep trenches, allowing for coaxial planarization and eliminating the need for dedicated design rules, reducing the risk of conductive residues and eliminating the need for guard regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If deep trenches are filled with conductive material for deep plugs, then electrical contact to deep regions is achieved, but planarization difficulty causes non-planarity and conductive residues on the front surface

Engineering Contradiction:

Improveelectrical contact reliabilityVSAvoidplanarization precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention segments the trench structure into two distinct parts: deep trenches for electrical contact and shallow trenches for planarization. The shallow trenches are filled with insulating material to create a planar surface, while the deep trenches extend below the shallow trenches to provide electrical contact. This segmentation allows each part to fulfill its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The deep trenches are nested within the shallow trenches structure. The shallow trenches surround and contain the upper portions of the deep trenches, creating a nested configuration where the insulating material in shallow trenches provides planarization while the conductive material in deep trenches provides electrical contact from the front surface.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Reliability

If guard regions are created around deep plugs to prevent electric field interference, then component operation reliability is improved, but chip area is wasted

Engineering Contradiction:

Improvecomponent operation reliabilityVSAvoidchip area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The shallow trenches filled with insulating material act as an intermediary structure between the deep plugs and the surrounding environment. This intermediary layer of insulating material provides electrical isolation and controls the electric field distribution, eliminating the need for additional guard regions and maximizing chip area utilization.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3840031B1Integrated device with deep contact plug and corresponding method of fabrication

Publication Date: 2024.02.14 STMICROELECTRONICS SRL

Figure 1
Figure 2A~2B
Figure 2C~2D

AI summary

An integrated device (100;300) is proposed comprising a deep plug (115). The deep plug (115) comprises a deep trench (120) extending in a semiconductor body (105) from a shallow surface (155) of a shallow trench (150), and a trench contact (140) contacting a conductive filler (135) of the deep trench (120) through the shallow trench (150) at its shallow surface (155). A system (500) comprising at least one integrated device (100;300) as above is also proposed. Moreover, a corresponding process for manufacturing this integrated device (100;300) is proposed.