Asymmetric DRAM Node Pad Arrangement for Photolithography Margin

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Solution Overview

Problem

Conventional DRAM devices face challenges in forming closely spaced pads without conductive bridges due to narrow intervals, which becomes increasingly difficult as semiconductor devices integrate more densely, leading to issues in photolithography processes.

Innovation Solution

The solution involves alternately arranging first and second node pads with specific width and interval configurations on a substrate, along with bit line pads, to form distinct pad columns, allowing for self-aligned formation of pads and storage electrodes, thereby improving process margins and productivity in photolithography.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If pads are arranged closely to increase integration density, then integration density is improved, but conductive bridges may form between pads due to narrow intervals

Engineering Contradiction:

Improveintegration densityVSAvoidconductive bridge formation

Core Design Contradiction:

Quantity of substanceVSReliability

Solution Approach 1:

The patent applies asymmetry by making the second node pads have a greater width in the second direction than the first node pads. This asymmetric design creates different spacing requirements and photolithography process margins for different pad types, allowing closely spaced pads to be formed without conductive bridges while maintaining high integration density

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent introduces a second direction (perpendicular to the first direction) for pad arrangement and width variation. By arranging pads in two directions and varying widths in the second direction, the patent creates additional spatial dimensions for optimization, enabling closer pad spacing without bridge formation while maintaining manufacturability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If photoresist residues remain between closely spaced pads, then photolithography process complexity increases, but pad spacing must be reduced for higher integration

Engineering Contradiction:

Improveintegration densityVSAvoidphotolithography process

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent changes geometric parameters of the pads, specifically making the second node pads wider in the second direction than the first node pads. This parameter variation creates different process margins for different pad structures, allowing the photolithography process to resolve closely spaced pads without bridge formation while maintaining high integration density

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS7714372B2Dynamic random access memory devices and methods of forming the same

Publication Date: 2010.05.11 SAMSUNG ELECTRONICS CO LTD

AI summary

Dynamic random access memory (DRAM) devices include first node pads and second node pads alternately arranged in a first direction on a substrate to form a first pad column. A width of the second node pads in a second direction, perpendicular to the first direction, is greater than a width of the first node pads in the second direction. Storage electrodes are electrically connected to the first node pads and the second node pads. Bit line pads may be arranged in the first direction on the substrate to form a second pad column. The second pad column is adjacent the first pad column and displaced therefrom in the second direction.