3D Memory Contact Plug Tapering for Uneven Insulating Films
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Solution Overview
Problem
The formation of contact plugs in three-dimensional semiconductor memories is complicated due to differences in film thickness between insulating films on uppermost and adjacent word lines, making it difficult to achieve precise plug formation.
Innovation Solution
The semiconductor device employs a contact plug design with discontinuous diameter changes at boundaries between different portions, allowing for tapered shapes that facilitate penetration through varying film thicknesses, ensuring electrical connectivity across electrode layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a contact plug is formed to penetrate through insulating films with different thicknesses, then electrical connectivity is achieved, but the manufacturing process becomes complicated and difficult to control
Solution Approach 1:
The contact plug is designed with a tapered shape where the diameter varies along the penetration direction. The first diameter at the upper end is larger than the second diameter at the lower end, creating local quality variations that facilitate penetration through insulating films of different thicknesses. This tapered geometry allows the plug to navigate through varying film thicknesses more easily while maintaining reliable electrical connectivity.
2Reliability
If the film thickness of the insulating film on the uppermost word line is increased, then insulation performance is improved, but the step of forming the contact plug becomes more complicated
Solution Approach 1:
The contact plug's diameter parameter is changed along its length, creating a tapered shape. The first diameter is set larger than the second diameter to accommodate variations in insulating film thickness. This parameter change in the plug's geometry allows it to penetrate through thicker insulating films on the uppermost word line without increasing the overall device complexity or complicating the formation process.
Data Source
AI summary
A semiconductor device includes a first insulating film, a second insulating film on the first insulating film, a first electrode layer on the second insulating film, second electrode layers above the first electrode layer and spaced apart from each other in a first direction, a third insulating film on each of the first electrode layer and the second electrode layers, a fourth insulating film on the third insulating film, a third electrode layer on the fourth insulating film, fourth electrode layers above the third electrode layer and spaced apart from each other in the first direction, a first plug electrically connected to the first electrode layer, a second plug electrically connected to any one of the second electrode layers, a third plug electrically connected to the third electrode layer, and a fourth plug electrically connected to any one of the fourth electrode layers.