Semiconductor Bitline Contact Pit for Drive Current
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Solution Overview
Problem
The miniature size of semiconductor devices, particularly DRAM with structures smaller than 17 nm, limits electrical performance and storage efficiency due to reduced drive current between the recessed transistor and bitline structure.
Innovation Solution
A semiconductor structure and fabrication method involving a bitline contact groove with a pit formed at its bottom, where the bitline lead fills the pit, increasing contact area and enhancing charge transfer speed between the bitline lead and the first active area, and a conductive plug is electrically connected to the second active area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the structure size of semiconductor devices is miniaturized to increase integration density, then the integration density is improved, but the drive current decreases
Solution Approach 1:
The patent introduces a three-dimensional pit structure within the bitline contact groove, transitioning from a planar contact interface to a volumetric contact region. This dimensional change increases the contact area between the bitline lead and the first active area without increasing the lateral footprint, thereby maintaining integration density while improving drive current through enhanced electrical contact.
Solution Approach 2:
The patent implements a nested structure where the pit is formed within the bitline contact groove, and the bitline lead is embedded within the pit. This nested arrangement maximizes the use of vertical space, increasing the contact area between conductive elements without expanding the overall device area, thus resolving the contradiction between miniaturization and drive current maintenance.
2Speed
If the contact area between bitline lead and active area is increased to improve charge transfer speed, then the electrical performance is improved, but the device area increases
Solution Approach 1:
The patent utilizes the vertical dimension by forming a pit structure that extends downward from the bitline contact groove surface. This increases the contact area between the bitline lead and the first active area in the vertical direction rather than expanding laterally, thereby improving charge transfer speed without increasing the device footprint.
Solution Approach 2:
The patent applies local quality enhancement by concentrating the contact area increase in the specific region of the bitline contact groove where the pit is formed. The pit creates a localized region of enhanced electrical contact between the bitline lead and the first active area, improving charge transfer speed at this critical interface without affecting or expanding the overall device area.
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 improves the performance of semiconductor devices by increasing the contact area and charge transfer speed, thereby overcoming limitations in electrical performance and storage efficiency.
Implementation Method 1
etching the semiconductor substrate by using the etch stop layer as a mask to form a pit at the bottom of the bitline contact groove
Data Source
AI summary
An embodiment provides a method for fabricating a semiconductor structure. The method includes: providing a semiconductor substrate having an active area, the active area including a first active area and a second active area isolated from each other; forming a bitline contact groove on the semiconductor substrate, the bitline contact groove exposing the first active area; forming an etch stop layer covering a sidewall of the bitline contact groove, the etch stop layer exposing a partial area of the first active area at a bottom of the bitline contact groove; etching the semiconductor substrate by using the etch stop layer as a mask to form a pit at the bottom of the bitline contact groove, the pit being at least partially positioned in the first active area; removing the etch stop layer; forming a bitline structure; and forming a conductive plug electrically connected to the second active area.