Stepped Semiconductor Isolation Structure for DRAM Leakage Blocking
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Solution Overview
Problem
Recessed access devices in DRAMs experience leakage issues that can reduce performance and lead to failure during margin tests, as activation of one portion can cause leakage to unactivated areas.
Innovation Solution
A semiconductor structure is created with a substrate having a boron-implanted p-type surface, a first dielectric layer, and a second dielectric layer, where the substrate is etched to form a stepped structure, and the dielectric layers are deposited to create a shallow trench isolation, blocking leakage and enhancing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If recessed access device is activated, then access function is improved, but leakage is generated that reduces performance
Solution Approach 1:
The recessed access device is divided into multiple isolated regions by shallow trench isolation structures. The substrate is segmented into first and second regions separated by the isolation structure, preventing leakage from propagating between activated and non-activated portions.
Solution Approach 2:
A shallow trench isolation structure acts as an intermediary barrier between different active regions. The isolation structure includes a first dielectric layer and a second dielectric layer with different materials, creating an intermediate isolation zone that blocks leakage paths while allowing adjacent regions to function independently.
2Object-generated harmful factors
If shallow trench isolation is formed with multiple dielectric layers, then leakage blocking is improved, but manufacturing complexity increases
Solution Approach 1:
Different dielectric materials are used in different layers of the shallow trench isolation structure. The first dielectric layer and second dielectric layer have different material properties optimized for their specific functions, creating local quality variations that enhance overall leakage blocking while maintaining manufacturing feasibility.
Solution Approach 2:
The shallow trench isolation structure employs composite materials consisting of multiple dielectric layers with different properties. This composite structure provides superior leakage blocking compared to single-material isolation, as each layer contributes different electrical and physical characteristics that collectively prevent leakage paths.
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
The boron implantation at the substrate surface effectively blocks leakage, improving semiconductor structure performance and preventing failure during margin tests by isolating active areas effectively.
Implementation Method 1
The first top surface of the substrate is implanted by boron to increase a p-type concentration of the first top surface of the substrate
Data Source
AI summary
A manufacturing method of a semiconductor structure includes: etching a substrate such that the substrate has a first top surface and a second top surface higher than the first top surface; implanting the first top surface of the substrate by boron to increase a p-type concentration of the first top surface of the substrate; forming a first dielectric layer on the substrate; and forming a second dielectric layer on the first dielectric layer.