Trench Isolation Doped Region Nitrogen Oxidation Void Prevention
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Solution Overview
Problem
In highly-integrated semiconductor memory devices, the reduction in size of active regions leads to increased contact resistance and interference between neighboring regions, making it challenging to maintain stable operation and prevent voids in device isolation trenches, which can result in leakage currents and Hot Electron Induced Punch-Through (HEIP) phenomena.
Innovation Solution
A method involving the formation of trenches with doped regions, varying oxide film thicknesses, and nitride films to ensure complete filling of insulation material without voids, where nitrogen is implanted to create a thicker oxide film at upper sidewalls and a thinner one at lower sidewalls, and the nitride film is removed from the trench bottom to prevent electron trapping and leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the trench width is reduced to increase integration density, then the distance between active regions is reduced, but it becomes difficult to fill the trench completely without generating voids
Solution Approach 1:
The patent changes the physical and chemical parameters of the trench by forming a doped region with nitrogen impurities before oxidation. This doping modifies the oxidation characteristics, enabling the oxide film to have varying thickness distribution that facilitates complete trench filling without voids even when the trench width is reduced for higher integration density.
Solution Approach 2:
The patent performs preliminary actions by forming the doped region and oxide film in the trench before filling with insulation material. The doped region is formed first, followed by oxidation to create the oxide film, which prepares the trench structure to be more receptive to complete insulation material filling without void formation.
2Reliability
If the oxide film is thickly formed to prevent HEIP phenomenon and leakage current, then device stability is improved, but the trench width becomes narrower making filling more difficult
Solution Approach 1:
The patent applies local quality by creating a doped region specifically in the lower portion of the trench and forming an oxide film with non-uniform thickness. The oxide film is thicker at the upper sidewalls where HEIP prevention is critical and thinner at the lower portions where filling difficulty occurs, thus locally optimizing both device stability and fillability.
Solution Approach 2:
The patent changes the oxidation parameters through preliminary nitrogen doping of the trench. This doping alters the oxidation rate and oxide film growth characteristics, enabling the formation of an oxide film with controlled thickness distribution that prevents HEIP phenomenon while maintaining trench fillability.
3Manufacturing precision
If the oxide film is thinly formed to facilitate trench filling, then trench filling becomes easier, but the purpose of preventing HEIP phenomenon and leakage current cannot be properly achieved
Solution Approach 1:
The patent resolves this contradiction by creating local quality variations in the oxide film thickness. The oxide film is formed to be thicker at the upper sidewalls of the trench where HEIP prevention is most effective, and thinner at the lower portions where complete filling is most difficult. This local differentiation simultaneously achieves both trench fillability and device stability.
4Reliability
If deep trench formation is performed to reduce interference between neighboring active regions, then electrical isolation is improved, but the difficulty of complete trench filling increases
Solution Approach 1:
The patent changes the chemical parameters of the trench by introducing nitrogen doping, which fundamentally alters the oxidation behavior. This enables the formation of an oxide film with a specific thickness distribution that facilitates complete filling of deep trenches without voids, thereby achieving both good electrical isolation and complete trench filling.
Solution Approach 2:
The patent performs preliminary nitrogen doping and oxide film formation before trench filling. These preliminary actions modify the trench structure and surface properties, making subsequent insulation material deposition more effective and enabling complete filling of deep trenches without void formation.
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 approach allows for stable operation of semiconductor devices by reducing leakage currents and preventing the HEIP phenomenon, enabling effective electrical isolation between active regions without deep trench formation, thus enhancing integration density and device stability.
Implementation Method 1
forming a doped region by implanting impurities into the trench. The impurities comprise nitrogen
Implementation Method 2
forming an oxide film in the trench by an oxidation process
Implementation Method 3
forming a nitride film at inner sidewalls of the trench
Data Source
AI summary
A semiconductor device and a method for manufacturing the same are disclosed. A method for manufacturing a semiconductor device includes forming a trench for defining an active region over a semiconductor substrate, forming a doped region by implanting impurities into the trench, forming an oxide film in the trench by performing an oxidation process, forming a nitride film at inner sidewalls of the trench, and forming a device isolation film in the trench.