DRAM Bit Line Selector Layout for Lower Voltage Drop and Noise
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Solution Overview
Problem
The design of the bit line select unit in Dynamic Random Access Memory (DRAM) faces challenges such as voltage drop, time delay, coupling effect, and noise effect due to misaligned active regions and conductive contacts, leading to poor performance and manufacturing difficulties.
Innovation Solution
A semiconductor structure with a bit line select unit featuring a symmetrical 'H' shape arrangement of gates and connection lines, ensuring straight bit lines and balanced conductive contacts, reducing coupling and noise effects while simplifying the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional bit line select unit design is used, then device functionality is achieved, but voltage drop and time delay occur due to misaligned active regions and conductive contacts
Solution Approach 1:
The patent employs asymmetric layout adjustment where active regions are intentionally misaligned relative to each other, and conductive contacts are positioned asymmetrically to connect bit lines. This asymmetric design optimizes the electrical connection paths to reduce voltage drop and time delay while maintaining proper transistor functionality.
Solution Approach 2:
The patent introduces a third dimension (vertical stacking) by forming conductive contacts that extend through multiple layers to connect misaligned active regions. This dimensional approach allows optimization of electrical paths without compromising the planar layout, reducing both voltage drop and time delay effects.
2Reliability
If traditional bit line select unit design is used, then device functionality is achieved, but coupling effect and noise effect increase due to misaligned structures
Solution Approach 1:
The asymmetric positioning of active regions and conductive contacts creates optimized electrical isolation between adjacent bit lines. By carefully designing the asymmetric layout, the patent reduces capacitive coupling and noise interference between neighboring signal lines while maintaining functional connectivity.
3Adaptability or versatility
If misaligned active regions and conductive contacts are used, then device functionality is achieved, but manufacturing precision and consistency become difficult to control
Solution Approach 1:
The patent incorporates alignment marks and reference structures in the preliminary design stage that guide the formation of misaligned active regions and conductive contacts. These pre-planned alignment features enable precise control of the intended misalignment, ensuring manufacturing consistency while achieving the desired electrical performance.
Solution Approach 2:
The patent systematically varies geometric parameters such as active region dimensions, contact positions, and layer offsets to optimize both the electrical performance and manufacturability. By carefully controlling these parameters within specific ranges, the design achieves robust performance across manufacturing variations.
Data Source
AI summary
A semiconductor structure and a memory are provided. The semiconductor structure includes multiple active regions, a column selector and multiple bit lines. The column selector includes a first gate, a second gate, a third gate, a fourth gate and a connection line. The first gate and the second gate intersect at a first node, the third gate and the fourth gate intersect at the second node, and the connection line connects the first node and the second node. Each of the multiple bit lines includes a first portion, a second portion and a connection portion. Each of the multiple bit lines is connected to a respective one of the multiple active regions, the active regions connected to different bit lines among the multiple bit lines are different.