Semiconductor Memory Bit Line Contact Indent Structure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor elements become more highly integrated, the miniaturization of circuit patterns leads to challenges in increasing reliability and performance in semiconductor memory devices, particularly in the design and fabrication of wiring lines and node pads that intersect each other.
Innovation Solution
The semiconductor memory device incorporates a substrate with an active area defined by an element separation layer, featuring a bit line contact with an indent area recessed into the substrate and an upper area, where the width of the indent area decreases as distance from the bit line increases, and a slope forming a boundary with the substrate, enhancing electrical connections and reducing contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If circuit patterns are miniaturized to increase integration density, then the quantity of semiconductor elements increases, but contact resistance and reliability deteriorate
Solution Approach 1:
The bit line contact transitions from a conventional planar structure to a three-dimensional structure with an indent area recessed into the substrate. The indent area has a width that decreases as distance from the bit line increases, creating a tapered geometry that extends vertically into the substrate. This dimensional change increases the effective contact area and volume without occupying additional lateral space, thereby maintaining low contact resistance while supporting higher integration density.
Solution Approach 2:
The contact geometry parameters are optimized by creating a slope with a substantially straight line shape in the indent area, where the width varies continuously with distance from the bit line. The starting point of the slope is positioned at a controlled depth below the upper surface of the element separation layer. These parameter changes enable precise control over the contact profile to minimize resistance while accommodating miniaturized circuit patterns.
2Quantity of substance
If circuit patterns are miniaturized to increase integration density, then the quantity of semiconductor elements increases, but manufacturing precision requirements worsen
Solution Approach 1:
The manufacturing process controls the indent area geometry by defining specific parameters: the slope forms a substantially straight line shape, the width decreases progressively with distance from the bit line, and the starting point of the slope is positioned at a controlled depth below the element separation layer surface. These well-defined parameters enable precise fabrication through standardized etching and deposition processes, making the complex three-dimensional geometry manufacturable despite miniaturization requirements.
3Adaptability or versatility
If wiring lines and node pads are designed to intersect, then device functionality improves, but contact resistance increases
Solution Approach 1:
The bit line contact uses a three-dimensional indent structure that extends vertically into the substrate, allowing the contact to pass through or alongside intersecting wiring lines and node pads. This vertical dimension enables the contact to maintain direct electrical connection to the active area while avoiding interference from horizontally intersecting conductors, thus preserving low contact resistance while achieving the required device functionality with intersecting lines.
Solution Approach 2:
The indent area acts as an intermediary structure that mediates between the bit line and the active area, providing a gradual transition zone. The tapered geometry of the indent area, with width decreasing from the bit line端 towards the substrate depth, creates a smooth electrical transition that minimizes resistance while allowing the contact to navigate around intersecting wiring structures.
Data Source
AI summary
A semiconductor memory device includes a substrate including an active area defined by an element separation layer, the active area including a first portion and second portions defined on both sides of the first portion a bit line crossing the active area and extending in a first direction on the substrate, and a bit line contact disposed between the substrate and the bit line and directly connected to the first portion of the active area. The bit line contact includes an indent area recessed into the substrate and an upper area on the indent area, a width of the indent area decreases as a distance from the bit line increases, the indent area includes a slope forming a boundary with the substrate and having a straight line shape, and a starting point of the slope of the indent area is lower than an upper surface of the element separation layer.