DRAM Word and Bit Line Trench Layout for Accurate Isolation
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Solution Overview
Problem
Existing processes for fabricating word line and bit line structures in DRAM are complex and costly, with challenges in alignment accuracy and potential for short circuits between these structures.
Innovation Solution
A method involving a base substrate with insulating material layers and trenches, where second trenches are formed intersecting the first, and third trenches are etched through these to create bit line structures, with word line structures insulated from bit line structures to prevent short circuits and improve alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If existing processes are used to fabricate word line and bit line structures, then the structures can be formed, but the fabrication process becomes complicated and costs increase
Solution Approach 1:
The patent combines the formation of second trenches (for word lines) and third trenches (for bit lines) into a single etching process. The mask layer defines both trench types simultaneously, allowing word line and bit line structures to be created in one fabrication step rather than separate processes, thereby simplifying the overall fabrication process and reducing costs
2Manufacturing precision
If third trenches are formed without using second trench masks, then additional masks are needed, but alignment accuracy of third trenches deteriorates
Solution Approach 1:
The mask layer serves multiple functions: it defines the positions of both second trenches (for word lines) and third trenches (for bit lines), and also provides insulation between the two structures. By making the mask layer multi-functional, the patent eliminates the need for separate masks for each trench type, maintaining high alignment accuracy while reducing mask structure complexity
3Reliability
If word line and bit line structures are formed without insulation, then fabrication is simpler, but the risk of short circuits increases
Solution Approach 1:
The mask layer acts as an intermediary insulating structure between the word line and bit line structures. By positioning the mask layer to extend across both trench types, it provides electrical isolation that prevents short circuits while being formed in the same process step, thus improving reliability without significantly increasing device complexity
Data Source
AI summary
Embodiments relate to a semiconductor structure and a formation method. The method includes: providing a base substrate, where the base substrate includes a substrate and an insulating material layer, the substrate includes a plurality of first trenches arranged at intervals along a first direction, and the insulating material layer fills each of the plurality of first trenches; etching the base substrate to form a plurality of second trenches arranged at intervals along a second direction, the second direction intersecting the first direction; removing a part of a material of the substrate below the plurality of second trenches to form third trenches below the plurality of second trenches, the third trenches penetrating through each of the plurality of second trenches; filling a conductive material into the third trenches to form bit line structures; and forming word line structures in the plurality of second trenches.