Semiconductor Substrate Contact Depth for Leak Current Suppression
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Solution Overview
Problem
In semiconductor devices, micro-defects in the substrate can lead to increased carrier diffusion, causing leak current and malfunction between semiconductor elements, particularly as oxygen concentration decreases, affecting the operation of adjacent elements.
Innovation Solution
A semiconductor device design featuring a substrate contact portion that extends deeper than the element isolation insulating films, allowing conductors to contact the semiconductor substrate from a first depth to a second depth, thereby reducing carrier diffusion and suppressing leak current between elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If element isolation insulating films are formed to separate semiconductor elements, then element separation is improved, but carrier diffusion between elements increases causing leak current
Solution Approach 1:
The patent extends the substrate contact portion from the surface to a greater depth than the element isolation insulating films, utilizing the depth dimension to intercept carriers that diffuse through the substrate. This three-dimensional approach complements the planar element separation, creating a vertical barrier that stops carrier diffusion paths without affecting the horizontal element isolation structure.
Solution Approach 2:
The substrate contact portion acts as an intermediary structure between the semiconductor elements. By forming conductive contacts to the substrate at depths below the element isolation films, it mediates the carrier diffusion problem by providing an alternative path for carriers to reach the substrate, preventing them from reaching adjacent elements.
2Ease of manufacture
If substrate contact portion reaches same depth as element isolation insulating films, then manufacturing is simplified, but carrier interception is insufficient leading to leak current
Solution Approach 1:
The patent segments the substrate contact structure into two distinct depth levels: the element isolation insulating films at a first depth, and the substrate contact portions extending to a second depth greater than the first. This segmentation allows each structure to be optimized independently - the element isolation films for surface-level separation and the substrate contacts for deep carrier interception.
Solution Approach 2:
The invention introduces a depth dimension differentiation where substrate contact portions extend deeper than element isolation films. This vertical dimensionality change enables the substrate contacts to intercept carriers that diffuse below the element isolation film level, providing enhanced carrier interception without complicating the horizontal manufacturing process.
3Object-affected harmful factors
If oxygen concentration in substrate is reduced for micro-defect gettering, then metal contamination is reduced, but carrier lifetime increases causing increased diffusion distance
Solution Approach 1:
The substrate contact portion serves as an intermediary structure that addresses the increased carrier diffusion distance caused by reduced oxygen concentration. By extending deeper into the substrate, it intercepts carriers before they can travel long distances and reach adjacent elements, effectively mediating the harm caused by increased carrier lifetime.
Solution Approach 2:
The patent utilizes the depth dimension to counteract the increased horizontal diffusion distance. By extending substrate contacts deeper into the substrate, it creates a vertical interception point that shortens the effective carrier path length, compensating for the increased diffusion distance resulting from reduced oxygen concentration and extended carrier lifetime.
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
This design effectively suppresses malfunction of semiconductor elements by reducing carrier diffusion and increasing the lifetime of carriers, ensuring reliable operation by forming a deeper substrate contact portion that traps diffusing carriers, thereby reducing leak current.
Implementation Method 1
In order to generate micro-defects, oxygen is introduced in advance in the semiconductor substrate. The introduced oxygen is precipitated as SiO2 between lattices by thermal treatment.
Implementation Method 2
micro-defects (BMD: Bulk Micro Defect) are generated in the semiconductor substrate for gettering of metal contamination
Implementation Method 3
The substrate contact portion is formed in a region of the semiconductor substrate positioned between the first element formation region and the second element formation region so as to reach from the main surface side to a second depth deeper than the first depth and is in contact with the semiconductor substrate from the first depth over the second depth
Data Source
AI summary
A semiconductor device includes a high voltage NMOS transistor formation region defined by an element isolation insulating film, a CMOS transistor formation region defined by an element isolation insulating film, and a substrate contact portion. The substrate contact portion is formed in a region of a semiconductor substrate that is positioned between the high voltage NMOS transistor formation region and the element isolation insulating film so as to reach from the main surface side to a position deeper than the bottom of the element isolation insulating film. The substrate contact portion is in contact with the semiconductor substrate from a depth over a depth.