Combination usage of noble gases for dry etching semiconductor wafers

Claim 1

A method of dry etching an overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying layer within an etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting gases to within the etching reactor to provide a gas mixture at a preselected pressure, the gas mixture comprising at least two noble gases of different molecular weights which are present within the etching reactor at a preselected ratio relative to one another, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the preselected ratio of the lighter noble gas to that of the heavier noble gas being at least approximately 2:1 by volume; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the overlying layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying layer.

Claim 2

A method of dry etching an overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying layer within an etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting gases to within the etching reactor to provide a gas mixture at a preselected pressure, the gas mixture comprising at least two noble gases of different molecular weights which are present within the etching reactor at a preselected ratio relative to one another, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the preselected ratio of the lighter noble gas to that of the heavier noble gas being at least approximately 2:1 by volume; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the overlying layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying layer.

Claim 19

A method of controlling sidewall passivation, minimizing loading effects, improving etch selectivity to an underlying layer and achieving improved uniformity from center to edge in an anisotropic reactive gas ion beam etch within a parallel plate etching reactor of an unmasked area of an overlying layer relative to an underlying layer on a semiconductor silicon substrate wafer, the method comprising: with said wafer in the reactor, injecting preselected quantities of at least two noble gases of different molecular weights into the etching reactor along with reactive gases, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the quantity of the lighter noble gas exceeding the quantity of the heavier noble gas by a ratio of at least approximately 2:1 by volume.

Claim 20

A method of controlling sidewall passivation, minimizing loading effects, improving etch selectivity to an underlying layer and achieving improved uniformity from center to edge in an anisotropic reactive gas ion beam etch within a parallel plate etching reactor of an unmasked area of an overlying layer relative to an underlying layer on a semiconductor silicon substrate wafer, the method comprising: with said wafer in the reactor, injecting preselected quantities of at least two noble gases of different molecular weights into the etching reactor along with reactive gases, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the quantity of the lighter noble gas exceeding the quantity of the heavier noble gas by a ratio of at least approximately 2:1 by volume.

Claim 28

A method of reactive ion etching a SiO 2 overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying polysilicon layer within an etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting gases to within the etching reactor to provide a gas mixture at a preselected pressure, the gas mixture within the reactor comprising SF 6 and CHF 3 at an approximate respective volume ratio of from 1:4 to 1:15, ±5%, and at least two noble gases of different molecular weights, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the lighter noble gas and heavier noble gas being present at an approximate respective volume ratio of from 2:1 to 10:1, ±5%; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the SiO 2 layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying polysilicon layer.

Claim 29

A method of reactive ion etching a SiO 2 overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying polysilicon layer within an etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting gases to within the etching reactor to provide a gas mixture at a preselected pressure, the gas mixture within the reactor comprising SF 6 and CHF 3 at an approximate respective volume ratio of from 1:4 to 1:15, ±5%, and at least two noble gases of different molecular weights, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas, the lighter noble gas and heavier noble gas being present at an approximate respective volume ratio of from 2:1 to 10:1, ±5%; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the SiO 2 layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying polysilicon layer.

Claim 38

A method of reactive ion etching a SiO 2 overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying polysilicon layer within a small gap parallel plate etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting SF 6 , CHF 3 , and at least two different molecular weight noble gases into the etching reactor at preselected flow rates, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas; the flow rate of the SF 6 being between 4.0 and 8.0 sccm, the flow rate of the CHF 3 being between 35.0 and 60.0 sccm, the flow rate of the lighter noble gas being between 50.0 and 200.0 sccm, and the flow rate of the heavier noble gas being between 10.0 and 50.0 sccm; the lighter noble gas and heavier noble gas being injected at an approximate respective volume ratio rate of from 2:1 to 10:1, ±5%; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the SiO 2 layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying polysilicon layer.

Claim 39

A method of reactive ion etching a SiO 2 overlying layer on a semiconductor silicon substrate wafer selectively relative to an underlying polysilicon layer within a small gap parallel plate etching reactor, the method comprising: positioning said wafer within the etching reactor; injecting SF 6 , CHF 3 , and at least two different molecular weight noble gases into the etching reactor at preselected flow rates, one of the noble gases being defined as the lighter noble gas, another being defined as the heavier noble gas; the flow rate of the SF 6 being between 4.0 and 8.0 sccm, the flow rate of the CHF 3 being between 35.0 and 60.0 sccm, the flow rate of the lighter noble gas being between 50.0 and 200.0 sccm, and the flow rate of the heavier noble gas being between 10.0 and 50.0 sccm; the lighter noble gas and heavier noble gas being injected at an approximate respective volume ratio rate of from 2:1 to 10:1, ±5%; and applying a preselected amount of electrical power to the etching reactor with the wafer and preselected ratio of at least two noble gases therein for a preselected amount of time to selectively obtain a desired etch of the SiO 2 layer, the etch producing high wafer center-to-edge etch uniformity and being highly selective to the underlying polysilicon layer.