Apparatus and method for forming controlled deep trench top isolation layers
First Claim
1. A method for controlling isolation layer thickness in trenches for semiconductor memories comprising the steps of:
- providing a deep trench having a storage node formed therein, the storage node having a buried strap;
depositing an isolation layer on the buried strap for providing electrical isolation for the storage node;
forming a masking layer on the isolation layer to mask a portion of the isolation layer in contact with the buried strap; and
removing the isolation layer other than the portion masked by the mask layer.
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Accused Products
Abstract
A method for controlling isolation layer thickness in deep trenches for semiconductor memories in accordance with the present invention includes the steps of providing a deep trench having a storage node formed therein, the storage node having a buried strap, depositing an isolation layer on the buried strap for providing electrical isolation for the storage node, forming a masking layer on the isolation layer to mask a portion of the isolation layer in contact with the buried strap and removing the isolation layer except the portion masked by the mask layer such that control of a thickness of the isolation layer is improved. A method for fabricating vertical transistors by recessing a substrate to permit increased overlap between a transistor channel and buried strap outdiffusion when the transistor is formed is also included. A semiconductor device is also disclosed.
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Citations
25 Claims
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1. A method for controlling isolation layer thickness in trenches for semiconductor memories comprising the steps of:
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providing a deep trench having a storage node formed therein, the storage node having a buried strap; depositing an isolation layer on the buried strap for providing electrical isolation for the storage node; forming a masking layer on the isolation layer to mask a portion of the isolation layer in contact with the buried strap; and removing the isolation layer other than the portion masked by the mask layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for fabricating a memory cell having trench isolation comprising the steps of:
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providing a deep trench having a storage node formed therein, the storage node having a buried strap; depositing an isolation layer on the buried strap for providing electrical isolation for the storage node; forming a masking layer on the isolation layer to mask a portion of the isolation layer in contact with the buried strap; selectively etching the isolation layer relative to the masking layer to leave the portion masked by the masking layer; opening up an isolation trench in communication with the deep trench by removing at least a portion of the substrate adjacent to the deep trench; filling the isolation trench with a dielectric material to provide trench isolation. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for fabricating a vertical transistor comprising the steps of:
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providing a substrate having trenches formed therein, each trench having a storage node formed therein, the storage node having a buried strap; forming an isolation layer on the buried strap; laterally etching the substrate to form a recess into the substrate such that the recess extends beyond sides of the trench, the recess being in communication with the trench; and forming a gate conductor in the recess such that a channel is formed adjacent to the gate conductor for providing electrical conduction between the buried strap and a conductive line upon activation of the gate conductor. - View Dependent Claims (22, 23, 24)
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25. A method for fabricating a vertical transistor for semiconductor memories with deep trenches comprising the steps of:
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providing a substrate having deep trenches formed therein, each deep trench having a storage node formed therein, the storage node having a buried strap recessed below a top surface of the substrate; forming an isolation layer on the buried strap and on trench sidewalls; depositing a dummy layer on the isolation layer; opening up an isolation trench in communication with the deep trench by removing at least a portion of the substrate adjacent to the deep trench; filling the isolation trench with a dielectric material to provide trench isolation; selectively etching the dummy layer relative to the dielectric material and the isolation layer; removing the isolation layer from the trench sidewalls; and forming a vertical transistor adjacent to the portion of the substrate that was removed.
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Specification