Process for manufacturing an SOI wafer by oxidation of buried channels
First Claim
1. A process for manufacturing an SOI wafer, comprising:
- forming cavities in a substrate of semiconductor material;
growing an epitaxial layer of monocrystalline type on top of said substrate and said cavities to obtain a wafer of monocrystalline semiconductor material embedding said cavities, said cavities being completely surrounded by said monocrystalline material;
forming second trenches extending in said epitaxial layer up to said cavities; and
oxidizing said cavities to form at least one continuous region of buried oxide.
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Accused Products
Abstract
A process that includes the steps of forming, in a wafer of monocrystalline silicon, first trenches extending between portions of the wafer; etching the substrate to remove the silicon around the first trenches and forming cavities in the substrate; covering the walls of the cavities with an epitaxial growth inhibiting layer; growing a monocrystalline epitaxial layer on top of the substrate and the cavities so as to obtain a monocrystalline wafer embedding buried cavities completely surrounded by silicon; forming second trenches extending in the epitaxial layer as far as the cavities; removing the epitaxial growth inhibiting layer; oxidizing the cavities, forming at least one continuous region of buried oxide; depositing a polysilicon layer on the entire surface of the wafer and inside the second trenches; removing the polysilicon layer on the surface and leaving filling regions inside the second trenches; and oxidizing, on the top, portions of said filling regions so as to form field oxide regions.
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Citations
23 Claims
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1. A process for manufacturing an SOI wafer, comprising:
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forming cavities in a substrate of semiconductor material;
growing an epitaxial layer of monocrystalline type on top of said substrate and said cavities to obtain a wafer of monocrystalline semiconductor material embedding said cavities, said cavities being completely surrounded by said monocrystalline material;
forming second trenches extending in said epitaxial layer up to said cavities; and
oxidizing said cavities to form at least one continuous region of buried oxide. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
forming first trenches in said substrate;
said first trenches extending between portions of said wafer; and
etching said substrate to remove said semiconductor material around said first trenches.
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3. The process of claim 2 wherein said etching is carried out in TMAH.
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4. The process of claim 3 wherein said etching is time-controlled.
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5. The process of claim 2 wherein forming first trenches comprises:
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forming a first hard mask of insulating material; and
anisotropically etching said substrate, using said first hard mask.
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6. The process of claim 1, further comprising, after forming said cavities, coating walls of said cavities with a layer inhibiting epitaxial growth.
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7. The process of claim 1 wherein forming second trenches comprises forming a hard mask and etching said epitaxial layer.
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8. The process of claim 1 further comprising:
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filling said second trenches with filling regions of semiconductor material; and
oxidizing upper portions of said filling regions so as to form regions of monocrystalline epitaxial silicon that are insulated at the sides and at the bottom.
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9. The process of claim 8 wherein filling said second trenches comprises:
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depositing a semiconductor material layer over the entire surface of the wafer; and
removing said semiconductor material layer on said surface of said wafer.
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10. The process of claim 1 wherein said cavities extend along the entire area of said wafer.
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11. The process of claim 1 wherein said cavities extend only on a part of the area of said wafer.
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12. The process of claim 1, further comprising, before forming first trenches, doping said substrate of semiconductor material.
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13. A process for manufacturing an SOI wafer, comprising:
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forming first trenches in a substrate of semiconductor material;
etching the first trenches to form cavities in the substrate of semiconductor material;
growing an epitaxial layer of monocrystalline silicon on top of the substrate of semiconductor material to cover the trenches and the cavities formed therein;
forming second trenches in the epitaxial layer to extend as far as the cavities; and
oxidizing the cavities to form at least one continuous region of buried oxide. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A process for the manufacture of an SOI wafer by oxidation of buried channels, the process comprising:
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forming first trenches in a wafer of monocrystalline silicon, the first trenches extending between portions of the wafer;
etching the wafer to remove the silicon around the first trenches and forming cavities in the wafer;
covering the walls of the cavities with an epitaxial growth inhibiting layer;
growing a monocrystalline epitaxial layer on top of the substrate and the cavities so as to obtain a monocrystalline wafer embedding buried cavities that are completely surrounded by silicon;
forming second trenches extending in the epitaxial layer as far as and in communication with the cavities;
removing the epitaxial growth inhibiting layer; and
oxidizing the cavities to form at least one continuous region of buried oxide. - View Dependent Claims (20, 21, 22)
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23. A process for manufacturing an SOI wafer, comprising in sequence, the steps of:
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forming cavities in a substrate of semiconductor material;
growing an epitaxial layer of monocrystalline type on top of said substrate and said cavities to obtain a wafer of monocrystalline semiconductor material embedding said cavities, said cavities being completely surrounded by said monocrystalline material;
forming second trenches extending in said epitaxial layer up to said cavities; and
oxidizing said cavities to form at least one continuous region of buried oxide.
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Specification