Stair Contact Structure for 3D Memory Manufacturing

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Solution Overview

Problem

The manufacturing of stair structures in 3D memory devices requires multiple photo mask and etching steps, leading to increased complexity and cost due to the need for multiple contact points at different levels, which complicates the process and raises costs.

Innovation Solution

A stair contact structure is designed with conductive layers and insulating layers interlaced, where the contact points are arranged along the extending direction of a first etch stop layer to form a stair structure with multiple stages, reducing the distance and overall size of the memory structure, and utilizing a manufacturing method involving dry and isotropic etching processes to create these structures with fewer mask steps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If multiple photo mask steps and etching steps are used to manufacture stair structures with multiple contact points at different levels, then the contact points can be formed at different levels, but the manufacturing cost and process complexity increase greatly

Engineering Contradiction:

Improvecontact points positioningVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent segments the etching process into multiple sequential etching steps, where each step creates contact points at different levels. By using a single photo mask pattern that defines all contact points, the process divides the complex 3D structure formation into manageable sequential etching operations, reducing the need for multiple photo mask steps while maintaining precise contact point positioning.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by forming a complete photo mask pattern that defines all contact points before any etching begins. This single photo mask pattern serves as a template for all subsequent etching steps, allowing the process to pre-determine the positions of all contact points at different levels, thereby eliminating the need for multiple photo mask alignment steps.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If multiple photo mask steps are used to create stair structures, then contact points at different levels can be formed, but the manufacturing cost increases

Engineering Contradiction:

Improvecontact points positioningVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent merges multiple photo mask steps into a single photo mask step. By designing a single photo mask pattern that encompasses all contact point positions across different levels, the process combines what would traditionally require multiple separate photo mask operations into one unified step, directly reducing manufacturing cost while maintaining the ability to form contact points at different levels.

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If traditional manufacturing methods are used for stair structures, then contact points can be formed at different levels, but the overall size and area of the memory structure increase

Engineering Contradiction:

Improvecontact points positioningVSAvoidmemory structure area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent utilizes the vertical dimension to arrange contact points at different levels, rather than spreading them out horizontally. By forming contact points at different heights (z-dimension) through sequential etching steps, the design compactly packs the contact structure vertically, reducing the horizontal footprint and overall area of the memory structure while maintaining precise contact point positioning.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 approach simplifies the manufacturing process, reduces costs, and achieves a smaller memory structure size by allowing multiple etching processes with fewer mask steps, while maintaining effective electrical connections to memory blocks.

Implementation Method 1

performing a dry etching process on the stacking structures

Methodology Applied

Scientific EffectDry etching:

Implementation Method 2

performing an isotropic etching process on the stacking structures

Methodology Applied

Scientific EffectIsotropic etching:

Data Source

PatentUS10340222B2Stair contact structure, manufacturing method of stair contact structure, and memory structure

Publication Date: 2019.07.02 MACRONIX INTERNATIONAL CO LTD

AI summary

A stair contact structure, a manufacturing method of a stair contact structure, and a memory structure are provided. The stair contact structure includes several layers of stacking structures and a first etch stop layer. Each stacking structure includes a conductive layer and an insulating layer. The conductive layers and the insulating layers are interlaced. The first etch stop layer penetrates through the stacking structures and extends along a first horizontal direction. The conductive layers of the stacking structures located at a first sidewall of the first etch stop layer have a plurality of contact points, and the contact points are arranged along the first horizontal direction to form a stair structure having a plurality of stages.