Word Line Trench Opening Profile for Short-Safe Memory Fabrication
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Solution Overview
Problem
Existing semiconductor memory device manufacturing methods face challenges in efficiently forming word lines with precise dimensions and profiles, particularly in creating openings with adequate width ratios and profiles to ensure reliable electrical connections and prevent short circuits.
Innovation Solution
A semiconductor memory device manufacturing method involving the formation of a word line trench with a first width, followed by an oxide liner, word line metal, and a nitride layer patterning to create a second opening with a trapezoidal profile and increased width, utilizing copper or tungsten as the word line metal and polysilicon as the conductive layer, with additional conformal oxide layer deposition and etching to protect these structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional word line trench formation method is used, then the manufacturing process is simple, but the opening width ratio and profile precision are insufficient
Solution Approach 1:
The manufacturing process is divided into multiple sequential steps: forming the word line trench, depositing oxide liner, filling word line metal, adding diffusion barrier, forming conductive layer, and patterning nitride layer. Each step contributes to achieving the precise trapezoidal profile with controlled width ratios, breaking down the complex precision requirement into manageable segments.
Solution Approach 2:
The oxide liner is formed in advance within the word line trench before metal filling, and the nitride layer is deposited and patterned beforehand to create the protective cap structure. These preliminary actions ensure that the final trapezoidal profile and width ratios are achieved with high precision.
2Manufacturing precision
If the word line trench is made deeper to achieve precise profiles, then manufacturing precision is improved, but etching control and device integrity worsen
Solution Approach 1:
The oxide liner acts as an intermediary layer deposited on the trench walls, and the nitride layer cap serves as a protective intermediary that prevents over-etching. These intermediary layers enable precise profile formation by providing controlled etching stops and protection, making the etching process more controllable rather than more difficult.
Solution Approach 2:
The nitride layer is deposited as a protective cap before final etching steps, cushioning against potential over-etching that could damage the underlying structures. This beforehand protection allows for more aggressive and precise etching to achieve the desired trapezoidal profile without compromising device integrity.
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 method ensures precise and reliable formation of word lines with enhanced electrical conductivity and prevents short circuits by using a trapezoidal-profiled nitride material to protect the conformal oxide layer and oxide liner from further etching, thereby improving device integrity and performance.
Implementation Method 1
forming an atomic-layer-deposition conformal oxide layer in the word line trench and over the first, second openings and the nitride layer
Implementation Method 2
forming a nitride material in the word line trench until the second opening is fully filled
Data Source
AI summary
A semiconductor memory device manufacturing method includes the following steps. A word line trench is formed in an active area of a substrate. An oxide liner is formed in the word line trench such that the word line trench has a first width at a first opening of the word line trench after forming the oxide liner. A word line metal is formed in the word line trench. A nitride layer is formed over the active area of the substrate. The nitride layer is patterned to form a second opening that is communicable with the first opening of the word line trench, wherein the second opening has a second width greater than the first width.