Buried Insulator Oxidation for Etching Resistance in 3D Memory
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Solution Overview
Problem
The formation of oxide films in semiconductor devices, particularly in three-dimensional memory structures, often results in inadequate oxidation of coating materials, leading to reduced etching resistance and performance issues due to insufficient penetration of oxidizing species into narrow trenches.
Innovation Solution
A semiconductor device manufacturing method involving the alternation of electrode and insulating layers, with specific oxidation processes for buried insulators, including polysilazane films, to ensure complete oxidation and enhance etching resistance by re-oxidizing the side faces of insulators to form silicon dioxide layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coating liquid is supplied on a substrate and oxidized to form an oxide film, then the oxide film is formed, but if the coating liquid is not sufficiently oxidized, the etching resistance of the oxide film is lowered
Solution Approach 1:
The patent applies preliminary action by forming a first insulator layer (polysilazane film) before the oxidation process, and then performing a re-oxidation process on the side faces of the insulator. This preliminary formation of the insulator layer followed by targeted re-oxidation ensures that the oxidation process can adequately penetrate and treat the material, thereby achieving sufficient etching resistance without requiring excessively aggressive initial oxidation conditions.
Solution Approach 2:
The patent employs strong oxidants by using oxygen plasma or oxygen-containing atmosphere for the re-oxidation process. This accelerated oxidation method enables thorough oxidation of the polysilazane film's side faces, ensuring complete conversion to silicon dioxide and achieving the required etching resistance. The strong oxidizing environment overcomes the limitation of oxidizing species penetration in narrow trenches.
2Ease of manufacture
If the coating liquid is not sufficiently oxidized, then the oxidation process is easier to perform, but the performance of the obtained oxide film such as etching resistance is lowered
Solution Approach 1:
The patent segments the oxidation process into two distinct stages: initial oxidation during insulator formation, and subsequent re-oxidation of the side faces. This segmentation allows each oxidation stage to be optimized independently - the first oxidation can be performed under standard conditions for ease of manufacture, while the second re-oxidation process targets specific regions to ensure complete oxidation and high oxide film performance without complicating the overall manufacturing process.
Solution Approach 2:
The patent applies local quality by performing re-oxidation specifically on the side faces of the insulator where oxidation is most critical for etching resistance. Rather than applying uniform oxidation throughout, the process targets the specific regions (side faces in narrow trenches) that require enhanced oxidation, thereby achieving high oxide film performance while maintaining process simplicity in other areas.
3Productivity
If oxidizing species penetration into narrow trenches is insufficient, then the oxidation process can be performed faster, but etching resistance is reduced
Solution Approach 1:
The patent applies preliminary action by forming the insulator layer completely before performing the re-oxidation process. This allows the main oxidation to proceed rapidly without concern for penetration limitations, and then a subsequent targeted re-oxidation step addresses the narrow trench regions. This approach maintains high productivity during the primary formation while ensuring adequate etching resistance through the follow-up treatment.
Solution Approach 2:
The patent employs periodic action by implementing a two-stage oxidation process with distinct time intervals. The first oxidation stage proceeds rapidly to form the insulator layer, and after a waiting period, a second re-oxidation stage is applied to enhance oxidation in narrow trenches. This periodic approach separates the high-speed formation phase from the quality-enhancement phase, maintaining overall productivity while ensuring adequate etching resistance.
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 improves the etching resistance and performance of buried insulators by ensuring thorough oxidation, reducing the likelihood of recess formation and maintaining the integrity of the insulating layers, thereby enhancing the overall semiconductor device performance.
Implementation Method 1
oxidizing the coating liquid
Implementation Method 2
re-oxidizing the side faces of insulators to form silicon dioxide layers
Data Source
AI summary
In one embodiment, a semiconductor device includes electrode layers and insulating layers alternately provided on a substrate and stacked in a first direction perpendicular to a surface of the substrate, and semiconductor layers provided in the electrode layers and insulating layers, extending in the first direction, and adjacent to each other in a second direction parallel to the surface of the substrate. The device further includes first and second charge trapping layers provided between the semiconductor layers and electrode layers sandwiching the semiconductor layers in a third direction parallel to the surface of the substrate. The device further includes insulators provided between the semiconductor layers being adjacent to each other in the second direction, and including a first insulator having a first width, and a second insulator having a second width longer than the first width and having nitrogen concentration different from that in the first insulator.