Self-aligned Insulation Structure for DRAM Trench Capacitors

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Solution Overview

Problem

The existing methods for forming insulation structures in DRAM processes require an additional mask to define the position, leading to misalignment and exposure of shallow trench isolation and deep trench capacitors to damaging processes like ion well implantation and thermal annealing.

Innovation Solution

A self-alignment method where the deep trench opening is used to form a first oxide layer and a first silicon layer directly, eliminating the need for an additional mask and ensuring precise alignment and protection of the substrate and trench structures before the completion of the insulation structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an additional mask is used to define the position of the insulation structure, then the insulation structure can be formed, but misalignment occurs between the insulation structure and the deep trench capacitor

Engineering Contradiction:

Improvealignment precisionVSAvoidmask process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The deep trench opening serves a dual function: it defines the capacitor region and simultaneously defines the position of the insulation structure. The insulation structure is formed using the deep trench opening as a self-aligned mask, eliminating the need for separate alignment processes and achieving precise positioning without additional masking steps.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The deep trench opening is used for multiple purposes: it defines the capacitor formation region and also serves as the mask for forming the insulation structure. This multi-functional use of the same structural feature eliminates the need for separate alignment processes and reduces manufacturing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If an additional mask is used to define the insulation structure position, then insulation can be formed, but the shallow trench isolation and deep trench capacitor are exposed to damaging processes

Engineering Contradiction:

Improveinsulation effectivenessVSAvoidcollateral damage from ion implantation and thermal annealing

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The insulation structure is formed before the ion implantation and thermal annealing processes. By using the deep trench opening as a self-aligned mask, the insulation structure is created in advance, providing protection to the shallow trench isolation and deep trench capacitor during subsequent damaging processes.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The insulation structure acts as a protective barrier formed beforehand to shield the shallow trench isolation and deep trench capacitor from harmful effects of ion implantation and thermal annealing. This pre-formed insulation layer prevents collateral damage to these sensitive structures.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If conventional masking methods are used, then the insulation structure can be formed, but an additional mask and alignment process are required

Engineering Contradiction:

Improveinsulation structure formationVSAvoidprocess time

Core Design Contradiction:

Ease of manufactureVSLoss of time

Solution Approach 1:

The deep trench opening automatically serves as the mask for forming the insulation structure, eliminating the need for separate mask fabrication and alignment processes. This self-aligned approach simplifies manufacturing and reduces process time by combining multiple steps into one.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The formation of the insulation structure is merged with the existing deep trench opening structure. Instead of using a separate mask, the insulation structure is formed directly using the deep trench opening as the defining feature, combining what would otherwise be separate process steps.

Inventive Principle:

Principle #5Merging (Combining)

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 method reduces misalignment and protects the substrate and trench structures from collateral damage, improving the yield of DRAM production by eliminating the need for an additional mask and ensuring precise insulation coverage.

Implementation Method 1

an oxidation step is carried out so that the surface of the Si forms a first oxide layer serving as the needed insulation structure

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS8207596B2Self-alignment insulation structure

Publication Date: 2012.06.26 MARLIN SEMICON LTD

AI summary

An insulation structure is provided. The insulation structure includes a deep trench filled with silicon and disposed in a substrate, a first oxide layer serving as the insulation structure and disposed on the surface of the silicon in the deep trench, a first silicon layer disposed on the first oxide layer, a gate disposed on the first silicon layer and a shallow trench isolation adjacent to the deep trench.