Conductive Cap Structure for Trench Capacitor Gap Sealing

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Solution Overview

Problem

The formation of trench capacitors in mobile devices faces challenges such as photoresist trapping and delamination issues due to high aspect ratios, leading to cracking and warping of substrates, and the use of dielectric cap structures can introduce electrical barriers and stress, increasing manufacturing costs and reducing yield.

Innovation Solution

A conductive cap structure is formed over the electrode layer to seal gaps without filling them, using physical vapor deposition (PVD) for the first conductive layer and metal-organic chemical vapor deposition (MOCVD) for a second conductive layer, which reduces stress on the substrate and prevents photoresist buildup, thereby minimizing cracking and delamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If dielectric cap structures are used to seal gaps in trench capacitors, then gap sealing is achieved, but electrical barriers are introduced and stress increases leading to cracking and delamination

Engineering Contradiction:

Improvegap sealing effectivenessVSAvoidelectrical barrier effect and substrate stress

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the material parameter of the cap structure from dielectric material to conductive material. This parameter change transforms the cap from an electrical barrier into an electrical conductor, eliminating the electrical barrier effect while maintaining gap sealing functionality. The conductive material also has different mechanical properties that reduce substrate stress.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the previously harmful conductive material (which would cause short circuits if used in gap sealing) into a beneficial solution. By using conductive material for the cap structure, the invention eliminates electrical barrier effects and reduces stress-related cracking and delamination, while the conductivity becomes a functional advantage for electrical connectivity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Productivity

If high aspect ratio trenches are formed for trench capacitors, then capacitor density is improved, but photoresist trapping occurs leading to manufacturing defects

Engineering Contradiction:

Improvecapacitor densityVSAvoidphotoresist trapping and delamination

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The conductive cap structure is formed before final electrode patterning steps. This preliminary action seals the high aspect ratio trench gaps early in the manufacturing process, preventing photoresist from being trapped in subsequent photolithography steps, thereby maintaining manufacturing precision while preserving high capacitor density.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If discrete passive devices are mounted on PCBs, then device functionality is achieved, but surface area consumption increases limiting mobile device size

Engineering Contradiction:

Improvedevice functionalityVSAvoidPCB surface area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple discrete passive devices (capacitors) into a single integrated passive device (IPD) structure. Multiple trench capacitors are formed in an array on a single substrate and packaged together as one integrated circuit, dramatically reducing the PCB surface area required while maintaining full device functionality.

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

The conductive cap structure reduces warping and cracking of substrates, maintains electrical integrity by not acting as a barrier, and lowers manufacturing costs by avoiding precursor trapping and outgassing issues.

Implementation Method 1

using physical vapor deposition (PVD) for the first conductive layer

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 2

metal-organic chemical vapor deposition (MOCVD) for a second conductive layer

Methodology Applied

Scientific EffectMetal-organic chemical vapor deposition: Chemical Vapour Deposition

Data Source

PatentUS11088239B2Cap structure for trench capacitors

Publication Date: 2021.08.10 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Various embodiments of the present application are directed towards a trench capacitor with a conductive cap structure. In some embodiments, the trench capacitor comprises a lower capacitor electrode, a capacitor dielectric layer overlying the lower capacitor electrode, and an upper capacitor electrode overlying the capacitor dielectric layer. The capacitor dielectric layer and the upper capacitor electrode are depressed into the substrate and define a gap sunken into the substrate. The conductive cap structure overlies and seals the gap on the upper capacitor electrode. In some embodiments, the conductive cap structure comprises a metal layer formed by physical vapor deposition (PVD) and further comprises a metal nitride layer formed overlying the metal layer by chemical vapor deposition (CVD). In other embodiments, the conductive cap structure is or comprises other suitable materials and/or is formed by other deposition processes.