Method of forming a novel composite insulator spacer
First Claim
1. A method of forming composite insulator spacers on the sides of conductive gate structures, on a semiconductor substrate, comprising the steps of:
- growing a gate insulator layer on said semiconductor substrate;
forming conductive gate structures on said gate insulator layer;
depositing a first insulator layer;
depositing a second insulator layer;
performing a first phase of an anisotropic dry etch procedure to form second insulator spacer components on said first insulator layer, with said first phase of said anisotropic dry etching procedure selectively terminating on said first insulator layer; and
performing a second phase of said anisotropic dry etch procedure wherein the etch rate ratio of said first insulator layer to said second insulator layer is between about 1.5 to 1, to 20 to 1, and the etch rate ratio of said first insulator layer to said semiconductor substrate is between about 3 to 1, to 100 to 1, to form first insulator spacer components, resulting in definition of said composite insulator spacers located on sides of said conductive gate structure with said composite insulator spacers comprised of said second insulator spacer components overlying said first insulator spacer components.
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Abstract
A method of defining composite insulator spacers on the sides of conductive gate structures, with reduced risk of semiconductor damage at end point of the composite insulator spacer definition procedure, has been developed. The method features initial deposition of a thin underlying, silicon rich, undoped silica glass (USG), layer, comprised with a refractive index greater than 1.55. After deposition of a TEOS silicon oxide layer a first phase of an anisotropic RIE procedure, using a CF4/CHF3 etch chemistry, is used to selectively define a silicon oxide spacer component, with the first phase of the etch procedure terminating on the underlying silicon rich, USG layer. A second phase of the anisotropic RIE procedure is then employed using C4F8/CO/Ar as an etchant, selectively defining the underlying silicon rich, USG spacer component of the composite insulator spacer, with the second phase of the anisotropic RIE procedure selectively terminating at the surface of the semiconductor substrate, thus reducing the risk of substrate damage.
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Citations
21 Claims
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1. A method of forming composite insulator spacers on the sides of conductive gate structures, on a semiconductor substrate, comprising the steps of:
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growing a gate insulator layer on said semiconductor substrate;
forming conductive gate structures on said gate insulator layer;
depositing a first insulator layer;
depositing a second insulator layer;
performing a first phase of an anisotropic dry etch procedure to form second insulator spacer components on said first insulator layer, with said first phase of said anisotropic dry etching procedure selectively terminating on said first insulator layer; and
performing a second phase of said anisotropic dry etch procedure wherein the etch rate ratio of said first insulator layer to said second insulator layer is between about 1.5 to 1, to 20 to 1, and the etch rate ratio of said first insulator layer to said semiconductor substrate is between about 3 to 1, to 100 to 1, to form first insulator spacer components, resulting in definition of said composite insulator spacers located on sides of said conductive gate structure with said composite insulator spacers comprised of said second insulator spacer components overlying said first insulator spacer components. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of forming composite insulator spacers on the sides of polysilicon gate structures, on a semiconductor substrate, featuring a selective two phase anisotropic reactive ion etch procedure, comprising the steps of:
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growing a silicon dioxide gate insulator layer on said semiconductor substrate;
forming said polysilicon gate structures on said silicon dioxide gate insulator layer;
depositing a silicon rich, undoped silica glass (USG), layer;
depositing a silicon oxide layer;
performing a first phase of said two phase anisotropic RIE procedure to form silicon oxide spacer components on said silicon rich, USG layer, with said first phase of said anisotropic RIE procedure selectively terminating on the top surface of said silicon rich, USG layer; and
performing a second phase of said two phase anisotropic RIE procedure forming silicon rich, USG spacer components, and resulting in definition of said composite insulator spacers on sides of said conductive gate structure with each composite insulator spacer comprised of a silicon oxide spacer component overlying a silicon rich, USG spacer component, with said second phase of said anisotropic RIE procedure selectively terminating on top surface of said semiconductor substrate located in a space between said polysilicon gate structures. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification