Trench Capacitor Dielectric Stack for DRAM Leakage Reduction
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Solution Overview
Problem
As semiconductor devices shrink in size, the capacitance values of cylindrical DRAM capacitors decrease significantly, affecting DRAM performance, and there is a need to maintain high capacitance while reducing DRAM size.
Innovation Solution
A semiconductor structure with a trench-based capacitor design featuring a lower electrode, a dielectric combination layer composed of a stacked nitride and oxide layer, and an upper electrode, which maintains electrode area and increases capacitance without shrinking, along with a trench filling process that simplifies capacitor formation and enhances performance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If cylindrical capacitor size is reduced to shrink DRAM, then DRAM size decreases, but capacitance value decreases significantly
Solution Approach 1:
The patent transitions from a conventional planar capacitor layout to a vertical trench-based capacitor structure. The capacitor is formed within a trench extending into the substrate, utilizing the vertical dimension (depth) to maintain electrode surface area and capacitance while reducing the planar footprint. This dimensional transition allows the capacitor to occupy less surface area without sacrificing capacitance, directly resolving the contradiction between DRAM size reduction and capacitance maintenance.
Solution Approach 2:
The patent employs a composite dielectric structure consisting of multiple layers with different materials (e.g., first dielectric layer, second dielectric layer, third dielectric layer) within the trench. Each layer may have different dielectric constants and properties, allowing optimization of the overall capacitance. The composite structure enables higher effective capacitance within the constrained trench volume, addressing the capacitance loss issue while maintaining compact dimensions.
2Volume of stationary object
If electrode and dielectric spaces are reduced in cylindrical capacitors, then capacitor size decreases, but capacitance value decreases significantly
Solution Approach 1:
By forming the capacitor vertically within a trench rather than horizontally in a planar configuration, the patent maximizes the use of vertical space. The trench depth provides additional volume for electrode and dielectric arrangement, allowing sufficient capacitance to be achieved within a reduced planar footprint. This vertical arrangement enables maintaining adequate electrode surface area and dielectric volume without increasing overall capacitor footprint.
Solution Approach 2:
The multi-layer dielectric structure within the trench allows optimization of space utilization. Different dielectric layers with varying properties are stacked vertically, enabling high capacitance density within the limited trench volume. The composite structure efficiently packs the electrode-dielectric-electrode sandwich configuration into the constrained vertical space, maintaining capacitance while minimizing horizontal space requirements.
3Ease of manufacture
If trench filling process is used for capacitor formation, then manufacturing complexity decreases, but electrode area and capacitance may be affected
Solution Approach 1:
The patent performs preliminary trench preparation and dielectric layer formation before electrode deposition. The trench is pre-formed with appropriate depth and width, and dielectric layers are pre-deposited and patterned before the electrode filling process. This preliminary preparation ensures that when electrodes are filled into the trench, they achieve optimal surface area and positioning, maintaining high capacitance while benefiting from the simplified trench filling manufacturing process.
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 maintains high capacitance levels as DRAM size decreases, improves electrical performance by avoiding leakage and increasing the dielectric constant, and optimizes the capacitor shape for enhanced stability.
Implementation Method 1
by adopting a dielectric combination layer including a stacked structure composed of nitride and oxide, not only the leakage phenomenon is avoided, but also the overall dielectric constant of the dielectric combination layer is effectively increased, thereby further increases the capacitor's capacitance
Implementation Method 2
by adopting a dielectric combination layer including a stacked structure composed of nitride and oxide, not only the leakage phenomenon is avoided
Data Source
AI summary
The present disclosure is in the field of semiconductor devices, in particular, to a semiconductor structure and a method of forming the same. The semiconductor structure includes: a substrate with a trench extending in a direction of the substrate; a capacitor fabricated in the trench, the capacitor includes a lower electrode disposed on an inner wall of the trench, a dielectric combination layer disposed on the lower electrode, and an upper electrode disposed on the dielectric combination layer; the dielectric combination layer includes a stacked structure composed of a nitride layer and an oxide layer. The device can increase the capacitance of the capacitor significantly and reduce the occurrence of charge leakage, thereby improving the electrical performance of the semiconductor memory device.