Semiconductor Memory Device Boron Gate Transistor Hydrogen Diffusion Control
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Solution Overview
Problem
Semiconductor memory devices face defects in boron gate transistors due to boron diffusion from the gate electrode through the gate insulating film, exacerbated by high hydrogen concentrations, leading to device failures.
Innovation Solution
A semiconductor memory device design featuring a second insulating film with a lower hydrogen diffusion coefficient, positioned to surround the boron gate transistor region, effectively suppresses hydrogen diffusion and reduces transistor defects by creating a guard ring region that partitions the memory cell and peripheral areas, thereby controlling hydrogen distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single insulating film is used to cover the semiconductor substrate, then the structure is simple and manufacturing is easy, but hydrogen diffusion cannot be effectively suppressed leading to boron gate transistor defects
Solution Approach 1:
The single insulating film is divided into two distinct insulating films: a first insulating film with higher hydrogen diffusion coefficient and a second insulating film with lower hydrogen diffusion coefficient. This segmentation allows each film to perform different functions - the first film provides general insulation while the second film specifically suppresses hydrogen diffusion to prevent boron gate transistor defects.
Solution Approach 2:
The second insulating film with lower hydrogen diffusion coefficient is specifically positioned in regions where hydrogen diffusion causes problems (peripheral regions and regions adjacent to memory cell arrays). This local quality approach applies the hydrogen-blocking property only where needed, rather than uniformly across the entire device, optimizing both reliability and manufacturing complexity.
2Reliability
If the memory cell array and peripheral circuit regions are not partitioned, then the circuit area is minimized, but hydrogen diffusion affects both regions causing transistor defects
Solution Approach 1:
The semiconductor substrate is partitioned into a memory cell array region and a peripheral circuit region using the second insulating film as a boundary. This segmentation creates a physical barrier that prevents hydrogen diffusion between regions while maintaining compact layout, thus improving reliability without significant area penalty.
Solution Approach 2:
The second insulating film acts as an intermediary barrier between the memory cell array region and peripheral circuit region. It specifically blocks hydrogen diffusion paths that would otherwise connect these regions, protecting boron gate transistors in the peripheral circuit from hydrogen-induced defects while maintaining close proximity between functional blocks.
3Reliability
If hydrogen diffusion is not suppressed, then the manufacturing process is simpler, but boron gate transistors exhibit defects due to hydrogen embrittlement
Solution Approach 1:
The insulating film structure is segmented into two layers with different hydrogen diffusion characteristics. The second insulating film is specifically designed with lower hydrogen diffusion coefficient to block hydrogen paths during manufacturing and operation, preventing boron gate transistor defects without requiring complex additional manufacturing steps.
Solution Approach 2:
The insulating film structure uses composite materials with different hydrogen diffusion coefficients. The first insulating film (higher diffusion coefficient) provides general insulation while the second insulating film (lower diffusion coefficient) specifically suppresses hydrogen diffusion. This composite structure achieves reliable hydrogen blocking while maintaining manufacturing feasibility.
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 solution effectively suppresses hydrogen diffusion into the boron gate transistor, reducing defect rates and maintaining high integration levels while minimizing circuit area increments.
Implementation Method 1
a second insulating film which is in contact with the first insulating film and has a smaller diffusion coefficient of hydrogen (H) than the first insulating film
Data Source
AI summary
A semiconductor memory device includes: a semiconductor substrate; a memory cell array provided in a first region; a first transistor provided in a second region; a second transistor provided in a third region; and an insulative laminated film. The first and second transistors each include a semiconductor layer, a gate electrode, and a gate insulating film. A concentration of boron (B) in the gate electrode of the second transistor is higher than that of the first transistor. The insulative laminated film includes a first insulating film contacting the surface of the semiconductor substrate, and a second insulating film having a smaller diffusion coefficient of hydrogen (H) than that of the first insulating film. The second insulating film has a first portion contacting the semiconductor portion, and the first portion surrounds the third region.