Self-aligned Back Side Deep Trench Isolation for Pixel Sensors

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Forming back side isolation structures in semiconductor devices is challenging due to degradation of existing electronic circuits and difficulties in filling trenches with isolating material, especially when done after device formation.

Innovation Solution

A self-aligned back side deep trench isolation (BDTI) structure is formed by selectively removing substrate material without lithography, aligning deep trenches with front side structures, and filling them without damaging existing circuits, providing suitable isolation and electrical connection to buried layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If back side isolation structures are formed after device formation, then isolation between adjacent circuits is improved, but existing electronic circuits are degraded

Engineering Contradiction:

Improveisolation between adjacent circuitsVSAvoiddegradation of existing electronic circuits

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The method performs preliminary actions by forming the deep trenches and filling them with isolating material before completing the device formation process. Specifically, the deep trenches are formed in the substrate, filled with dielectric material, and planarized before the electronic circuits are fully formed, thereby preventing degradation of existing circuits while achieving isolation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The isolation structure is segmented into two parts: a first isolation structure formed on the front side of the substrate, and a second isolation structure formed on the back side. This segmentation allows each isolation structure to be formed independently at different stages, with the second structure providing additional isolation without affecting the first structure or the electronic circuits

Inventive Principle:

Principle #1Segmentation

2Reliability

If deep trenches are formed and filled with isolating material, then isolation effectiveness is improved, but manufacturing complexity increases

Engineering Contradiction:

Improveisolation effectivenessVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The deep trench isolation structure serves multiple functions: it provides electrical isolation between adjacent circuits, acts as a mechanical support structure, and enables back side access to the substrate. The same trench structure is used for both isolation and as a vehicle to deliver isolating material to the back side, eliminating the need for separate structures

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The method merges the formation of the deep trench isolation structure with the substrate thinning process. The deep trenches are formed and filled during the same manufacturing stage when the substrate is being thinned from the back side, combining two separate processes into one, thereby reducing manufacturing complexity

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10128293B2Self-aligned back side deep trench isolation structure

Publication Date: 2018.11.13 PARABELLUM STRATEGIC OPPORTUNITIES FUND LLC

AI summary

A pixel sensor device is disclosed. The device includes a shallow trench isolation structure, a well region and a backside isolation structure. The well region and diode region is adjacent to the shallow trench isolation structure. The backside isolation structure is self-aligned with and arranged over the shallow trench isolation structure. The backside isolation structure is adjacent to the diode region.