Method of forming silicon dioxide

In a method of forming an optical waveguide preform comprising:

• a. providing a glass cylindrical member having a first index of refraction;
• and
• b. depositing a glass layer comprising SiO.sub.2 on a surface of the glass cylindrical member, the SiO.sub.2 glass layer having a second index of refraction, wherein the improvement comprises:
• in step (b) initially combining and reacting gaseous SiH.sub.2 Cl.sub.2 and a gaseous oxidant, selected from the group consisting of O.sub.2, CO.sub.2 N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient at a temperature ranging from about 450.degree. C to about 1200.degree. C to directly form a uniform SiO.sub.2 layer at a rate which is substantially temperature independent.

In an improved method of forming a clad optical fiber comprising:

• a. providing a glass tube having a first index of refraction;
• b. depositing a SiO.sub.2 glass layer on a surface of the glass tube, and SiO.sub.2 glass layer having a second index of refraction;
• c. heating the structure so formed to the drawing temperature of the materials thereof;
• and
• d. drawing the heated structure to reduce the cross-sectional area thereof and to collapse the SiO.sub.2 deposited glass tube to form the core of the fiber and the cladding of the fiber, wherein the improvement comprises:
• in step (b), combining and reacting a gaseous mixture comprising at least SiH.sub.2 Cl.sub.2 and a gaseous oxidizing agent, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient at a temperature ranging from about 450.degree. C to about 1200.degree. C to directly form and deposit a uniform SiO.sub.2 layer on the surface at a rate which is substantially temperature independent.

In an improved method of forming a clad optical fiber comprising:

• providing a substantially cylindrical starting member;
• applying a first coating of SiO.sub.2 to the outside peripheral surface of the member;
• applying a second coating of SiO.sub.2 over the outside peripheral surface of the first coating, the second coating having an index of refraction less than that of the first coating;
• removing the cylindrical starting member;
• heating the structure so formed to the drawing temperature of the materials thereof;
• and
• drawing the heated structure to reduce the cross-sectional area thereof and to collapse the first coating of SiO.sub.2 to form the core of the fiber and the second coating forming the fiber cladding, wherein the improvement comprises:
• initially forming and reacting a gaseous mixture comprising at least SiH.sub.2 Cl.sub.2 and a gaseous oxidant, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient at a temperature ranging from about 450.degree. C to about 1200.degree. C to directly form a uniform SiO.sub.2 glass coating at a rate which is substantially temperature independent.

A method of treating a semiconductive wafer which comprises:

• a. initially exposing in a liquid phase free ambient a surface of the wafer maintained at a temperature ranging from about 450.degree. C to 1200.degree. C to a reaction mixture comprising gaseous SiH.sub.2 Cl.sub.2 and an oxidizing gas, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, to directly deposit a surface film comprising SiO.sub.2 thereon at a substantially temperature independent rate;
• b. selectively treating said deposited surface to remove a portion of said film therefrom to expose an underlying surface area;
• and
• c. treating said underlying surface area with a conductivity type determining impurity to diffuse said impurity in a region of the semiconductive wafer underlying said underlying surface area.

In a method of forming a planar semiconductor device which comprises the steps of:

• a. forming an oxide coating on a surface of a semiconductor body;
• b. removing a selected portion of the oxide coating to expose the surface of the semiconductor body;
• c. treating the exposed surface to controllably diffuse a selected impurity into the semiconductor body;
• and
• d. reforming a continuous oxide coating on the surface of the body, wherein the improvement comprises;
• in at least step (a) directly formina a unifrom SiO.sub.2 coating on the surface at a substantially temperature independent rate by initially exposing the surface maintained at a temperature ranging from between 450.degree. C to 1200.degree. C, to a mixture comprising gaseous SiH.sub.2 Cl.sub.2 and an oxidizing gas, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient.

In a method of fabricating planar semiconductor devices which comprises the steps of:

• a. forming an oxide layer on a surface of a semiconductor body of a first conductivity type;
• b. forming an opening in the oxide layer to expose the surface of the semiconductor body;
• c. predepositing a first selected impurity on the exposed surface;
• d. controllably diffusing at an elevated temperature the first impurity into the semiconductor body to form a P-N junction extending to the surface;
• e. reforming a continuous layer of oxide on the surface;
• f. forming a second opening in a portion of the reformed oxide above the region of the semiconductor body into which the first impurity has been diffused to expose the surface;
• g. predepositing a second selected impurity on the exposed surface;
• h. diffusing at an elevated temperature the second selected impurity into the semiconductor body to form a second P-N junction between the first mentioned P-N junction and the surface;
• and
• i. reforming a continuous layer of oxide on the surface, wherein the improvement comprises:
• in at least step (a) directly forming a uniform SiO.sub.2 layer on the surface at a substantially temperature independent rate by initially exposing the surface, at a temperature ranging from 450.degree. C to 1200.degree. C, to a mixture comprising gaseous SiH.sub.2 Cl.sub.2 and an oxidizing gas, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient.

In a method of fabricating a planar junction semiconductor device which comprises the steps of:

• a. forming an oxide layer on a surface of a semiconductor body;
• b. opening a hole in the oxide layer to expose a desired limited portion of the surface of the semiconductor body;
• c. predepositing a first selected impurity on the exposed portion of the surface;
• d. diffusing the first impurity into the semiconductor body to form a P-N junction which extends to the surface;
• e. forming a continuous layer of oxide on the surface;
• f. opening a hole in the oxide layer above the region of the semiconductor body into which the first impurity has been diffused to expose the surface;
• g. predepositing a second impurity on the exposed surface;
• h. diffusing the second impurity into the semiconductor body to form a second P-N junction between the first P-N junction and the surface;
• i. reforming a continuous layer of oxide on the surface;
• j. opening a plurality of holes in the oxide layers to expose a portion of each of the regions of the body containing the diffused impurities;
• k. depositing a layer of metal on the surface of the oxide layers which fills the plurality of openings and makes ohmic contact with the exposed surface of each of the regions;
• and
• l. selectively removing portions of the metal layer to provide separate conductive paths to each of the regions, wherein the improvement comprises:
• in at least step (a) directly forming a uniform SiO.sub.2 layer on the surface at a substantially temperature independent rate by initially exposing the surface, at a temperature ranging from 450.degree. C to 1200.degree. C, to a gaseous mixture comprising SiH.sub.2 Cl.sub.2 and an oxidant therefor, selected from the group consisting of O.sub.2, CO.sub.2, N.sub.2 O, H.sub.2 O and mixtures thereof, in a liquid phase free ambient.