Self-aligned trench formation
First Claim
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1. A method of forming a device, the method comprising:
- forming a layer of polysilicon on a substrate;
forming a first set of trenches in the substrate, wherein remaining portions of the polysilicon layer remain above the substrate in inter-trench regions between trenches of the first set;
filling the first set of trenches with a filler material, wherein the filler material extends upward to at least a level adjacent the remaining portions of the polysilicon layer;
selectively etching the remaining portions of the polysilicon layer from the inter-trench regions;
forming spacers on sidewalls of the filler material in the inter-trench regions; and
etching a second set of trenches into the substrate between the spacers.
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Abstract
Methods for forming a semiconductor device include forming self-aligned trenches, in which a first set of trenches is used to align a second set trenches. Methods taught herein can be used as a pitch doubling technique, and may therefore enhance device integration. Further, employing a very thin CMP stop layer, and recessing surrounding materials by about an equal amount to the thickness of the CMP stop layer, provides improved planarity at the surface of the device.
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Citations
26 Claims
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1. A method of forming a device, the method comprising:
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forming a layer of polysilicon on a substrate; forming a first set of trenches in the substrate, wherein remaining portions of the polysilicon layer remain above the substrate in inter-trench regions between trenches of the first set; filling the first set of trenches with a filler material, wherein the filler material extends upward to at least a level adjacent the remaining portions of the polysilicon layer; selectively etching the remaining portions of the polysilicon layer from the inter-trench regions; forming spacers on sidewalls of the filler material in the inter-trench regions; and etching a second set of trenches into the substrate between the spacers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of forming a device on a substrate, comprising:
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forming an etch stop layer on the substrate; etching a plurality of first trenches through the etch stop layer and the substrate; filling the first trenches with an isolation material that protrudes above the substrate; forming spacers on sidewalls of the protruding portion of the isolation material; etching a plurality of second trenches between the spacers; filling the second trenches with a second filler material; and planarizing the second filler material and stopping planarizing on the etch stop layer. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification