Heterogeneous conformal CVD of arsenosilicate glass

Claim 2

A process for fabricating a semiconductor device having a conformal dielectric coating of arsenosilicate glass disposed over underlying material layers having a topography which includes abrupt changes in vertical elevation, said process comprising the steps of locating said semiconductor device with said underlying material layers within chemical vapor deposition apparatus; maintaining the temperature of said device below about 500° C. while controllably admitting a gaseous mixture comprising SiH 4 , O 2 , AsH 3 and non-reactive diluent into the environment of said device wherein the volume ratio of silane to arsine lies in the range 3.8:1 to 11.7:1, with the volume ratio of oxygen to silane in the range of 18.5:1 to 41:1 so as to establish a predominantly heterogeneous deposition reaction onto the surface of said device and thereby achieve said conformal dielectric coating.

Claim 3

A process as in claim 1 wherein the temperature of said device is maintained between 400° C. and 450° C.

Claim 4

A process as in claim 1 further comprising the step of back gettering the device after producing the conformal arsenosilicate glass coating.

Claim 5

A process as in claim 1 wherein the arsenosilicate glass layer conformally overlies a metalization material layer on said device.

Claim 6

A process as in claim 1 further comprising the step of depositing a metalization layer over the conformal layer of arsenosilicate glass.

Claim 7

A process as in claim 5 further comprising the step of depositing an additional layer of arsenosilicate glass over the metalization layer by repeating said previously recited maintaining step.

Claim 8

In a process for depositing a layer of arsenosilicate glass onto an underlying substrate via a chemical vapor deposition process including supplying a gaseous mixture of silane, oxygen, arsine and a non-reactive diluent and reacting the gaseous mixture to deposit an arsenosilicate film onto the substrate, the improvement comprising: (1) selectively adjusting the amount of arsine gas supplied to the gaseous mixture to control the silane/oxygen reaction and maintain a heterogeneous decomposition reaction onto the surface of the substrate substantially to the exclusion of a homogeneous reaction of silane and oxygen wherein the volume ratio of silane to arsine lies in the range 3.8:1 to 11.7:1, with the volume ratio of oxygen to silane in the range 18.5:1 to 41:1; and (2) depositing the arsenosilicate layer onto and in conformity with a substrate having a topography including abrupt changes in vertical elevation.

Claim 9

In a process for depositing a layer of arsenosilicate glass onto an underlying substrate via a chemical vapor deposition process including supplying a gaseous mixture of silane, oxygen, arsine and a non-reactive diluent and reacting the gaseous mixture to deposit an arsenosilicate film onto the substrate, the improvement comprising: (1) selectively adjusting the amount of arsine gas supplied to the gaseous mixture to control the silane/oxygen reaction and maintain a heterogeneous decomposition reaction onto the surface of the substrate substantially to the exclusion of a homogeneous reaction of silane and oxygen wherein the volume ratio of silane to arsine lies in the range 3.8:1 to 11.7:1, with the volume ratio of oxygen to silane in the range 18.5:1 to 41:1; and (2) depositing the arsenosilicate layer onto and in conformity with a substrate having a topography including abrupt changes in vertical elevation.

Claim 10

A method as claimed in claim 7 wherein the reaction is carried out at a temperature between 400° C. and 450° C.

Claim 11

A method as in claim 7 used in fabricating a semiconductor device, the method including the step of producing a layer of arsenosilicate glass as a conformal coating onto a semiconductor device then and thereafter maintained at temperatures less than about 500° C.

Claim 12

A method as claimed in claim 7, the method further comprising carrying out a back gettering step after the arsenosilicate glass is produced.

Claim 13

A method as claimed in claim 9 wherein the arsenosilicate glass lies over a metallisation layer.

Claim 15

A method as claimed in claim 12, the method further comprising the step of depositing an additional layer of arsenosilicate glass over the metallisation layer.