DRAM Contact Structure With Vertical Pads for Lower Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As the critical dimension of dynamic random access memory (DRAM) shrinks, the contact resistance between the capacitor contact and the active area increases, reducing the reliability of memory devices.
Innovation Solution
The implementation of conductive pads vertically disposed between conductive plugs and active areas to reduce contact resistance, enhancing reliability and performance by minimizing misalignment issues during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the critical dimension of DRAM is shrunk to achieve lightness and smallness, then the size of electronic products is reduced, but the contact resistance between capacitor contact and active area increases
Solution Approach 1:
The contact structure is divided into multiple segments: conductive pad, conductive plug, and capacitor contact. The conductive pad is formed as a separate intermediate structure between the conductive plug and active area, breaking the direct contact path into manageable segments that can be independently optimized for alignment and electrical connection.
Solution Approach 2:
The conductive pad extends in the vertical dimension between the conductive plug and active area, creating a multi-layered contact structure. This vertical extension provides additional contact area and tolerance for misalignment in the lateral dimensions, effectively transitioning from a 2D contact problem to a 3D solution.
2Volume of moving object
If the critical dimension is reduced, then device miniaturization is achieved, but manufacturing precision becomes more difficult to maintain
Solution Approach 1:
The conductive pad is positioned locally between the conductive plug and active area, creating a localized compensation structure. This local addition provides alignment tolerance specifically at the contact interface without affecting the overall device dimensions, allowing different parts of the structure to have different functional qualities.
Solution Approach 2:
The conductive pad acts as a cushioning structure that anticipates and compensates for potential misalignment issues before they affect the electrical connection. By providing an intermediate contact area with larger dimensions, it cushiones against the effects of manufacturing variations that would otherwise directly impact the capacitor contact alignment.
3Reliability
If conductive pads are added to reduce contact resistance, then reliability is improved, but device complexity increases
Solution Approach 1:
The conductive pad formation is merged with the existing contact structure fabrication process. The pad is formed using the same conductive material and deposition techniques as the conductive plug, combining multiple functions into a unified fabrication sequence that minimizes additional process complexity.
Solution Approach 2:
The conductive pad serves multiple functions: it reduces contact resistance, provides alignment tolerance, and acts as an electrical interconnection element. This multi-functionality justifies the additional structure by delivering several benefits simultaneously rather than requiring separate solutions for each problem.
Data Source
AI summary
Provided is a memory device including a substrate, a plurality of bit-line structures, a plurality of conductive plugs, and a plurality of conductive pads. The substrate has a plurality of active areas. The plurality of bit-line structures are disposed on the substrate in parallel. The plurality of conductive plugs are respectively disposed aside the plurality of bit-line structures, and are electrically connected to the plurality of active areas. The plurality of conductive pads are vertically disposed between the plurality of conductive plugs and the plurality of active areas. One of the conductive plugs has a bottom area falls within a range of a top area of a corresponding conductive pad.