Storage Node Electrode Bridging Prevention in DRAM Fabrication
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Solution Overview
Problem
Highly integrated semiconductor memory devices, such as DRAM, face issues with bridging between storage node electrodes due to surface tension, leading to electrical shorts and device failures, and are prone to galvanic corrosion, which degrades reliability.
Innovation Solution
A method of fabricating semiconductor memory devices involves forming storage node electrodes within holes in a mold insulating film, covering them with a capping film, and selectively removing the mold insulating film using wet etching to expose sidewalls, thereby reducing bridging and preventing galvanic corrosion by supporting the electrodes and controlling the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the density and height of storage node electrodes are increased to improve capacitance and integration, then the capacitance and integration capacity are improved, but the probability of bridging between adjacent electrodes increases
Solution Approach 1:
The mold insulating film is formed to cover the storage node electrodes before the bridging problem occurs. This preliminary protective structure prevents surface tension from causing electrode contact during subsequent wet etching or washing operations, allowing high-density electrode structures to be manufactured without bridging failures.
Solution Approach 2:
The mold insulating film acts as an intermediary protective layer between adjacent storage node electrodes. It physically separates the electrodes during critical processing steps, preventing direct contact caused by surface tension while allowing the electrodes to maintain their high-density configuration for improved capacitance.
2Ease of manufacture
If wet etching is used to remove the mold insulating film, then the etching process is simple and cost-effective, but surface tension of water film causes storage node electrodes to contact each other
Solution Approach 1:
The mold insulating film is applied in advance to counteract the harmful surface tension effect. During wet etching, this film prevents water from directly contacting the storage node electrodes, thereby eliminating the surface tension force that would otherwise cause bridging, while still allowing the use of simple wet etching chemistry.
3Area of moving object
If the separation distance between storage node electrodes is decreased to increase density, then the integration density is improved, but the bridge probability increases due to reduced spacing
Solution Approach 1:
The mold insulating film structure is established before electrodes are positioned at high density. This pre-formed protective framework allows electrodes to be placed closer together for improved integration density while the film prevents bridging that would normally occur at such small separations.
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 prevents or reduces bridging between storage node electrodes and minimizes voids under the electrodes, allowing for higher density and increased capacitance without compromising device reliability, enabling the production of high-capacity semiconductor memory devices.
Implementation Method 1
selectively removing, including wet etching, the mold insulating film to expose a sidewall of at least one storage node electrode
Implementation Method 2
One is a surface tension (Fs) that works to attract the storage node electrodes 70 to each other
Implementation Method 3
the other one is an elastic force (Fe) that is works in a direction opposite to that of surface tension
Data Source
AI summary
In one aspect, a method of fabricating a semiconductor memory device is provided which includes forming a mold insulating film over first and second portions of a semiconductor substrate, where the mold insulating film includes a plurality of storage node electrode holes spaced apart over the first portion of the semiconductor substrate. The method further includes forming a plurality of storage node electrodes on inner surfaces of the storage node electrode holes, respectively, and forming a capping film which covers the storage node electrodes and a first portion of the mold insulating film located over the first portion of the semiconductor substrate, and which exposes a second portion of the mold insulating film located over the second portion of the semiconductor substrate. The method further includes selectively removing, including wet etching, the mold insulating film to expose a sidewall of at least one storage node electrode among the storage node electrodes covered by the capping film, and removing the capping film by dry etching to expose upper portions of the storage node electrodes.