Polysilicon Source Terminal Structure for Edge Seam Sealing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

In three-dimensional integrated circuit device structures, ensuring proper electrical connection between memory cells and source terminals is challenging due to seam formation in conductive materials, which can lead to disconnection during manufacturing, especially affecting cells near the edge of the array.

Innovation Solution

An isotropic etch is used to create a bulbous-shaped opening in a trench, filling it with polysilicon material to form a source terminal, where the polysilicon material is thicker at the edge, sealing any seams and reducing the likelihood of disconnection from reactive species in subsequent processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If polysilicon material is deposited to fill the trench uniformly, then the manufacturing process is simple, but seams form in the conductive material leading to disconnection

Engineering Contradiction:

Improveelectrical connection reliabilityVSAvoidpolysilicon thickness profile complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The polysilicon material is configured with non-uniform thickness where the edge portion is thicker than the center portion. This local variation in quality ensures that seams formed during deposition are sealed at the edges by the thicker material, preventing disconnection while maintaining manufacturing feasibility.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The trench opening is formed with a bulbous shape having curved surfaces instead of straight vertical walls. This curvature allows the deposited polysilicon material to form a thicker layer at the edges and thinner at the center, naturally sealing seams without requiring complex multi-step deposition processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Reliability

If the polysilicon material thickness is increased at edges, then seams are sealed and disconnection is prevented, but the manufacturing precision requirement increases

Engineering Contradiction:

Improveseam sealing effectivenessVSAvoidpolysilicon thickness control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The bulbous-shaped trench opening is formed in advance before polysilicon deposition. This preliminary shaping of the trench with curved surfaces ensures that subsequent uniform polysilicon deposition automatically results in thicker material at the edges and thinner at the center, achieving seam sealing without requiring precise thickness control during deposition.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The curved geometry of the trench opening itself performs the sealing function. When polysilicon is deposited, the thicker material naturally accumulates at the edges due to the bulbous shape, automatically sealing seams without requiring additional processing steps or precise thickness modulation during deposition.

Inventive Principle:

Principle #25Self-service

3Reliability

If a bulbous-shaped opening is created, then edge polysilicon thickness increases to seal seams, but the etching process complexity increases

Engineering Contradiction:

Improveseam protectionVSAvoidtrench formation process

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The mechanical approach of creating complex trench geometries through multiple etching steps is replaced by using a single isotropic etch process that naturally forms bulbous-shaped openings. The curved surfaces and edge thickening are achieved through the etching chemistry and process parameters rather than mechanical machining or multiple sequential etches.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 thicker edge polysilicon material effectively protects seams from etching agents, reducing the risk of pillar disconnection from the source terminal, thereby enhancing the reliability of electrical connections within the integrated circuit device.

Implementation Method 1

An isotropic etch is used to create a bulbous-shaped opening in a trench

Methodology Applied

Scientific EffectIsotropic etching:

Implementation Method 2

filling it with polysilicon material to form a source terminal

Methodology Applied

Scientific EffectMaterial deposition: Deposition (physical)

Data Source

PatentUS20240081070A1Intervening polysilicon materials that are thicker at distal edges than at pillars defining memory cells and related apparatuses, systems, and methods

Publication Date: 2024.03.07 MICRON TECHNOLOGY INC

AI summary

Source terminals of memory devices and related apparatuses, computing systems, and methods are disclosed. An apparatus includes a first polysilicon material, a second polysilicon material offset from the first polysilicon material, an intervening polysilicon material between the first polysilicon material and the second polysilicon material, and pillars defining memory cells. The pillars extend through the second polysilicon material and a proximal portion of the intervening polysilicon material into the first polysilicon material. The one or more insulative materials are at a distal edge of the intervening polysilicon material. The intervening polysilicon material is thicker at the distal edge than at the pillars. A method includes removing, using an isotropic etch process, portions of the first polysilicon material and the second polysilicon material in a trench and forming the intervening polysilicon material between the first polysilicon material and the second polysilicon material.