Capacitor Formation Using Sacrificial Nitride Layer

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Solution Overview

Problem

In semiconductor memory devices, increasing the height of capacitor columns to enhance capacitance can lead to bending and wobbling, causing shorts due to stress on the BPSG/TEOS lattice portions, especially with smaller pitch and gap margins.

Innovation Solution

A method involving the use of a sacrificial nitride layer above the top lattice portion to reduce stress and prevent bending, comprising multiple layers of silicate and nitride materials, with the sacrificial layer being selectively removed to increase the surface area of the capacitor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the height of capacitor columns is increased to enhance capacitance, then the capacitance is improved, but the capacitor columns are prone to bending and wobbling due to stress on the BPSG/TEOS lattice portions

Engineering Contradiction:

ImprovecapacitanceVSAvoidstructural stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

A sacrificial nitride layer is deposited on the top lattice portion before forming the capacitor column. This preliminary action creates a stress-absorbing structure that prevents bending and wobbling during subsequent processing steps, allowing the capacitor column to maintain its vertical integrity while achieving the required height for sufficient capacitance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The sacrificial nitride layer acts as an intermediary between the top lattice portion and the capacitor column. It absorbs and distributes the stress that would otherwise cause bending, serving as a temporary support structure during fabrication that can be selectively removed later to expose the capacitor surface.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the height of capacitor columns is increased to enhance capacitance, then the capacitance is improved, but the risk of shorts increases due to bending and wobbling

Engineering Contradiction:

ImprovecapacitanceVSAvoidshort circuit risk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The sacrificial nitride layer is deposited in advance to prevent structural defects before they can cause shorts. By stabilizing the capacitor column during formation, the preliminary action eliminates the bending-induced shorts that would otherwise occur with tall, thin capacitor structures.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If a sacrificial nitride layer is deposited to prevent bending, then the structural stability is improved, but the device complexity increases

Engineering Contradiction:

Improvestructural stabilityVSAvoidfabrication process complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The sacrificial nitride layer is deposited as a temporary structure to provide stability during fabrication, then selectively removed to expose the capacitor surface. This discarding of the temporary structure simplifies the final device while having provided the necessary support during the critical formation phase.

Inventive Principle:

Principle #34Discarding and recovering

Solution Approach 2:

The sacrificial nitride layer is selectively removed from specific regions where it is no longer needed, extracting the temporary support structure after it has served its purpose. This extraction reveals the stabilized capacitor column while eliminating the added complexity of the sacrificial material in the final device.

Inventive Principle:

Principle #2Taking out (Extraction)

4Area of stationary object

If the sacrificial layer is selectively removed to increase surface area, then the surface area exposure is improved, but the manufacturing precision requirements increase

Engineering Contradiction:

Improvesurface areaVSAvoidselective removal precision

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The sacrificial nitride layer is removed selectively from specific local regions rather than uniformly across the entire structure. This local quality approach allows precise control over where the layer is removed, enabling surface area enhancement in critical regions while maintaining structural integrity elsewhere through selective etching or removal processes.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS10964475B2Formation of a capacitor using a sacrificial layer

Publication Date: 2021.03.30 MICRON TECHNOLOGY INC

AI summary

Methods, apparatuses, and systems related to forming a capacitor using a sacrificial material are described. An example method includes forming a first silicate material on a substrate. The method further includes forming a first nitride material on the first silicate material. The method further includes forming a second silicate material on the first nitride material. The method further includes forming a second nitride material on the second silicate material. The method further includes forming a sacrificial material on the second nitride material. The method further includes forming a column of capacitor material through the first silicate material, the first nitride material, the second silicate material, the second nitride material, and the sacrificial material. The method further includes removing the sacrificial material to expose a top portion of the capacitor material.