EP0224646A2 — Method for removing protuberances at the surface …

Claim 1

Independent Claim 92 words

Method for removing protuberances at the surface of a semiconductor wafer, comprising the steps of: a) preparing a semiconductor substrate having an irregular surface provided with protuberances, b) blanket depositing a layer of a polishing stop barrier onto said irregular surface, c) chem-mech polishing said surface to remove only the portions of said polishing stop barrier layer located at the top and at the sidewalls of the protuberances and the underlying glass as well, while the other portions located on the planar surfaces of said polishing stop barrier layer, remain substantially unattacked.

Claim 2

Dependent Claim 92 words

Method for removing protuberances at the surface of a semiconductor wafer, comprising the steps of: a) preparing a semiconductor substrate having an irregular surface provided with protuberances, b) blanket depositing a layer of a polishing stop barrier onto said irregular surface, c) chem-mech polishing said surface to remove only the portions of said polishing stop barrier layer located at the top and at the sidewalls of the protuberances and the underlying glass as well, while the other portions located on the planar surfaces of said polishing stop barrier layer, remain substantially unattacked.

Claim 3

Dependent Claim 10 words

Method according to claim 1, wherein said protuberances are glassy.

Claim 4

Dependent Claim 16 words

Method according to claim 1, wherein the material forming said polishing stop barrier layer is Si₃N₄.

Claim 5

Dependent Claim 15 words

Method according to claim 3, wherein the thickness of said layer is about 100 nm.

Claim 6

Dependent Claim 12 words

Method according to claim 3 wherein said protuberances are comprised of SiO₂.

Claim 7

Dependent Claim 30 words

Method according to claim 5 wherein SiO₂ protuberances are the so-called "bird' heads" which normally result from the Recessed Oxidation Isolation (ROI) process, at the periphery of the ROI regions.

Claim 8

Dependent Claim 41 words

Method according to claim 6 wherein an SiO₂ water based slurry is used comprising 8 liters of fifty weight percent colloidal silicon, 150gr of the sodium salt of dichloroisocyanic acid, 450gr of Na₂ CO₃ H₂O and 32 liters of deionized water.

Claim 9

Dependent Claim 18 words

Method according to claim 7 wherein the polishing rate between SiO₂ and Si₃N₄ is between 4:1 and 40:1.

Claim 10

Dependent Claim 13 words

Method according to claim 8 wherein said polishing ratio is selected around 6:1.

Claim 11

Dependent Claim 36 words

Method according to claim 9 wherein the chem-mech polishing parameters are: slurry flow rate 400-500 cc/min on a two side free polisher and 100-200 cc/min on a single side polisher, polishing pressures 2.5 psi, and temperature.

Claim 12

Dependent Claim 205 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxidation Isolation (ROI) region having a polysilicon filled deep trench therein comprising the steps of: a) providing a silicon substrate with an ROI region exhibiting an SiO₂ "bird' head" causing an irregular surface of said substrate; b) depositing a layer of a Si₃N₄ polishing stop barrier onto said irregular surface; c) depositing a trench etch masking layer of SiO₂ onto the structure; d) forming a trench in the ROI region; e) growing a thin layer of thermal SiO₂ on the exposed silicon in the trench; f) depositing a layer of Si₃N₄ by CVD; g) depositing a layer of SiO₂ by CVD; h) RIE etching to remove the Si₃N₄ and SiO₂ layers at the bottom of said trench; i) depositing a layer of polysilicon; and, j) chem-mech polishing the surface of the structure to remove both said polysilicon layer except in said trench and said trench etch masking layer and to remove partially the portions of said polishing stop barrier located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portion located on the planar surfaces of said polishing stop barrier remain substantially unattacked.

Claim 13

Dependent Claim 205 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxidation Isolation (ROI) region having a polysilicon filled deep trench therein comprising the steps of: a) providing a silicon substrate with an ROI region exhibiting an SiO₂ "bird' head" causing an irregular surface of said substrate; b) depositing a layer of a Si₃N₄ polishing stop barrier onto said irregular surface; c) depositing a trench etch masking layer of SiO₂ onto the structure; d) forming a trench in the ROI region; e) growing a thin layer of thermal SiO₂ on the exposed silicon in the trench; f) depositing a layer of Si₃N₄ by CVD; g) depositing a layer of SiO₂ by CVD; h) RIE etching to remove the Si₃N₄ and SiO₂ layers at the bottom of said trench; i) depositing a layer of polysilicon; and, j) chem-mech polishing the surface of the structure to remove both said polysilicon layer except in said trench and said trench etch masking layer and to remove partially the portions of said polishing stop barrier located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portion located on the planar surfaces of said polishing stop barrier remain substantially unattacked.

Claim 14

Dependent Claim 136 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate passivated with a composite SiO2/Si3N4 ROI mask stack and having a recess formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Claim 15

Dependent Claim 136 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate passivated with a composite SiO2/Si3N4 ROI mask stack and having a recess formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Claim 16

Dependent Claim 23 words

Method of claim 11 wherein previous to step b), a layer of thermal oxide is grown on the exposed silicon in the recess.

Claim 17

Dependent Claim 133 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate having a recess formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄ within said periphery of said regions; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Claim 18

Dependent Claim 133 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate having a recess formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄ within said periphery of said regions; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Claim 19

Dependent Claim 138 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate having narrow as well as wide recesses formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄ within said periphery of said wide regions; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Claim 20

Dependent Claim 138 words

Method of forming a substantially planar integrated structure provided with a Recessed Oxide Isolation (ROI) Region without "bird's head" or "bird's beak" characteristics comprising the steps of: a) providing a silicon substrate having narrow as well as wide recesses formed therein to expose silicon at the ROI region locations; b) depositing an SiO₂ layer onto the structure, which in particular fills the recess; and c) provides SiO₂ protuberances at the periphery of the ROI region; d) depositing a layer of Si₃N₄ within said periphery of said wide regions; and e) chem-mech polishing the surface of the structure to remove the portions of said Si₃N₄ layer located at the top and at the sidewalls of the protuberances and the underlying SiO₂ as well while the other portions located on the planar surfaces of said Si₃N₄ layer remain substantially unattacked.

Method for removing protuberances at the surface of a semiconductor wafer using a chem-mech polishing technique

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