Method of generating multiple oxides by plasma nitridation on oxide
First Claim
1. A method of forming three different gate oxide thicknesses on a substrate comprising:
- (a) providing a substrate with isolation regions that separate active areas where circuits are to be formed, with one said active area having a nitrogen implant near the substrate surface,(b) growing a first oxide layer on active areas of said substrate,(c) removing selected portions of the first oxide layer including the oxide over the nitridated active area,(d) growing a second oxide layer on active areas of said substrate,(e) annealing said substrate,(f) nitridating all oxide regions, and(g) annealing said substrate;
wherein the first oxide layer is comprised of an HfO2/silicate layer which is formed by first growing an SiO2 layer with a thickness of about 3 Angstroms using an RTO method followed by depositing an HfO2/silicate later with a thickness in a range of 2 to 30 Angstroms.
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Abstract
A method of forming multiple gate oxide thicknesses on active areas that are separated by STI isolation regions on a substrate. A first layer of oxide is grown to a thickness of about 50 Angstroms and selected regions are then removed. A second layer of oxide is grown that is thinner than first growth oxide. For three different gate oxide thicknesses, selected second oxide growth regions are nitridated with a N2 plasma which increases the dielectric constant of a gate oxide and reduces the effective oxide thickness. To achieve four different gate oxide thicknesses, nitridation is performed on selected first growth oxides and on selected second growth oxide regions. Nitridation of gate oxides also prevents impurity dopants from migrating across the gate oxide layer and reduces leakage of standby current. The method also reduces corner loss of STI regions caused by HF etchant.
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Citations
12 Claims
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1. A method of forming three different gate oxide thicknesses on a substrate comprising:
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(a) providing a substrate with isolation regions that separate active areas where circuits are to be formed, with one said active area having a nitrogen implant near the substrate surface, (b) growing a first oxide layer on active areas of said substrate, (c) removing selected portions of the first oxide layer including the oxide over the nitridated active area, (d) growing a second oxide layer on active areas of said substrate, (e) annealing said substrate, (f) nitridating all oxide regions, and (g) annealing said substrate; wherein the first oxide layer is comprised of an HfO2/silicate layer which is formed by first growing an SiO2 layer with a thickness of about 3 Angstroms using an RTO method followed by depositing an HfO2/silicate later with a thickness in a range of 2 to 30 Angstroms. - View Dependent Claims (3, 4, 5)
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2. A method of forming three different gate oxide thicknesses on a substrate comprising:
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(a) providing a substrate with isolation regions that separate active areas where circuits are to be formed, with one said active area having a nitrogen implant near the substrate surface, (b) growing a first oxide layer on active areas of said substrate, (c) removing selected portions of the first oxide layer including the oxide over the nitridated active area, (d) growing a second oxide layer on active areas of said substrate, (e) annealing said substrate, (f) nitridating all oxide regions, and (g) annealing said substrate; wherein the first oxide layer is comprised of an HfO2/silicate layer and wherein selected portions of the HfO2/silicate layer are removed by patterning a photoresist on said substrate and then etching exposed HfO2/silicate layer with a dilute HF solution. - View Dependent Claims (7, 8, 9)
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6. A method of forming three different gate oxide thicknesses on a substrate comprising:
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(a) providing a substrate with isolation regions that separate active areas where circuits are to be formed, with one said active area having a nitrogen implant near the substrate surface, (b) growing a first oxide layer on active areas of said substrate, (c) removing selected portions of the first oxide layer including the oxide over the nitridated active area, (d) growing a second oxide layer on active areas of said substrate, (e) annealing said substrate, (f) nitridating all oxide regions, and (g) annealing said substrate; wherein the first layer is comprised of an HfO2/silicate layer and wherein the HfO2/silicate layer is used to make a integrated circuit with DRAM functionality, a thicker SiO2 gate oxide is used to make a MOSFET which is part of a low power logic circuit, and a thinner SiO2 gate oxide used to make a MOSFET as part of a high performance logic circuit. - View Dependent Claims (10, 11, 12)
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Specification