Monolithic Polysilicon Trench Memory Fill
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Solution Overview
Problem
The existing process for constructing trench memory devices, such as DRAM, involves multiple polysilicon materials placed at different times, creating interfaces that increase resistance and process time, leading to reduced performance and higher costs.
Innovation Solution
A method to fill the trench with a single, monolithic conducting material, eliminating interfaces and reducing the number of processing steps, by forming a trench with a collar and node dielectric, and filling it with a monolithic conducting material like polysilicon in a single temporal step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple polysilicon materials are placed at different times, then the trench can be filled with conducting materials, but interfaces are created that increase resistance and process time
Solution Approach 1:
The patent merges multiple separate polysilicon filling operations into a single monolithic conducting material fill. Instead of placing first poly, second poly, and third poly at different times, the invention uses a single conducting material fill that eliminates the need for multiple temporal steps, directly reducing process time while maintaining the trench fill function.
Solution Approach 2:
The patent segments the trench fill process into distinct functional zones within a single material: the monolithic conducting material serves as the buried strap, while separate collar and node dielectric structures provide isolation and capacitance functions. This allows one material to fulfill multiple roles that previously required multiple materials placed at different times.
2Ease of manufacture
If three polysilicon materials are placed within the trench at temporally distinct times, then the trench can be constructed, but the number of processing steps increases
Solution Approach 1:
The patent merges three separate polysilicon filling steps into a single conducting material deposition and fill operation. This reduces the number of processing steps from three distinct polysilicon placements to one monolithic fill operation, simplifying the manufacturing process while achieving the same structural outcome of a filled trench with conducting material.
Solution Approach 2:
The single monolithic conducting material performs multiple functions that previously required three different polysilicon materials: it serves as the buried strap for electrical connection, provides structural filling for the trench, and works in conjunction with the collar and node dielectric to establish the capacitor structure. This multi-functionality reduces process complexity.
Data Source
AI summary
A trench memory filled with a monolithic conducting material and methods for forming the same are disclosed. The trench memory includes a trench that has only a single, monolithic conducting material within the trench. The method includes forming a trench with a collar in the trench; forming a node dielectric on a sidewall of the trench; and filling the trench with a monolithic conducting material, such as polysilicon.