Semiconductor Contact Plug With Metal Gate Using Dual Damascene
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor devices face issues with high resistance and electrical shorts due to the use of poly-silicon gates and multiple contact plugs, which degrade performance as devices are miniaturized.
Innovation Solution
A semiconductor structure utilizing a dual damascene process to form a contact plug with a single barrier layer, reducing resistance and avoiding electrical shorts by using copper or tungsten as the metal layer, and incorporating a 'trench first' dual damascene process to improve electrical connectivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple contact plugs are used to connect source/drain, then electrical connectivity is provided, but resistance increases and electrical performance deteriorates
Solution Approach 1:
The patent combines multiple contact plugs into a single unified contact plug structure that connects both source and drain regions. This is achieved by forming one continuous contact plug through the interlayer dielectric layers that makes electrical contact with both source and drain, eliminating the need for separate contact plugs and reducing overall resistance while maintaining connectivity.
2Reliability
If conventional poly-silicon gate is used, then gate electrode function is provided, but boron penetration and depletion effect increase equivalent thickness of gate dielectric layer, reduce gate capacitance, and worsen driving force
Solution Approach 1:
The patent changes the material parameter of the gate electrode from poly-silicon to metal gate materials with appropriate work functions. This parameter change allows the gate to achieve better electrical performance and control capability without suffering from boron penetration and depletion effects that plague poly-silicon gates, thereby maintaining thin gate dielectric layer thickness while improving driving force.
3Volume of moving object
If miniaturization is pursued, then device size is reduced, but electrical short between metal gate and contact plug becomes more likely
Solution Approach 1:
The patent solves the shorting problem by changing the vertical positioning dimension - the contact plug is designed with its upper surface positioned below the gate bottom surface, creating a vertical separation that prevents electrical shorts. This dimensional arrangement ensures that even as devices are miniaturized, the spatial separation between gate and contact plug maintains electrical isolation.
4Reliability
If dual damascene process is used to form contact plug, then boundary of trench portion and via portion is higher than gate top surface, avoiding short phenomenon
Solution Approach 1:
The contact plug is segmented into two distinct portions: a lower trench portion that contacts the source/drain regions and an upper via portion that extends through the interlayer dielectric. This segmentation allows the boundary between portions to be positioned above the gate top surface, preventing shorts while maintaining a manageable structural complexity through clear functional division.
Data Source
AI summary
The present invention provides a semiconductor structure including at least a contact plug. The structure includes a substrate, a transistor, a first ILD layer, a second ILD layer and a first contact plug. The transistor is disposed on the substrate and includes a gate and a source/drain region. The first ILD layer is disposed on the transistor and levels with a top surface of the gate. The second ILD layer is disposed on the first ILD layer. The first contact plug is disposed in the first ILD layer and the second ILD layer and includes a first trench portion and a first via portion, wherein a boundary of the first trench portion and a first via portion is higher than the top surface of the gate. The present invention further provides a method of making the same.