Thermal oxidation of silicon using ozone
A method and apparatus for oxidizing materials used in semiconductor integrated circuits, for example, for oxidizing silicon to form a dielectric gate. An ozonator is capable of producing a stream of least 70% ozone. The ozone passes into an RTP chamber through a water-cooled injector projecting into the chamber. Other gases such as hydrogen to increase oxidation rate, diluent gas such as nitrogen or O 2 , enter the chamber through another inlet. The chamber is maintained at a low pressure below 20 Torr and the substrate is advantageously maintained at a temperature less than 800° C. Alternatively, the oxidation may be performed in an LPCVD chamber including a pedestal heater and a showerhead gas injector in opposition to the pedestal.
1. A substrate oxidizing apparatus, comprising: a vacuum chamber having sidewalls arranged about a central axis; a rotatable support within the vacuum chamber for supporting a substrate in a first plane perpendicular to the central axis and rotating the substrate in an angular direction about the central axis, the substrate having a pre-existing surface layer to be oxidized to form an oxide layer on the substrate and the central axis passing through the substrate;
a heat source capable of heating the substrate to an elevated oxidizing temperature; a source of hydrogen gas conveying the hydrogen gas into the chamber only through a single first gas port in the sidewalls, extending in a second plane perpendicular to the central axis, and directing the hydrogen gas perpendicularly to the central axis and towards a central region of the substrate;
an ozonator receiving a flow of oxygen gas, forming an electrically coupled plasma selected from one of a capacitively coupled plasma and an inductively coupled plasma, and capable of producing an ozone-containing gas, an output of the ozonator conveying ozone of the ozone-containing gas into the vacuum chamber through only a single second gas port in the sidewalls, extending in the second plane, and directing the ozone-containing gas perpendicularly to the central axis and towards the central region of the substrate to oxidize the layer in conjunction with the hydrogen gas; and
a pump port in the sidewalls for evacuating the vacuum chamber; wherein the second gas port is angularly displaced in the second plane from the first gas port along a circumference about the central axis by an angular displacement of between 15° and 115° to thereby in conjunction with the rotating support delay reaction of the ozone-containing gas and the hydrogen gas conveyed into the chamber by the first and second gas ports;
wherein said ozonator is capable of producing at least 30% ozone in the ozone-containing gas;
wherein a fluid cooled injector incorporated into the second gas port and extending from the sidewalls along an injector axis perpendicular to the central axis and configured to inject the ozone-containing gas toward the substrate from a distal end of the injector.
2. The oxidizing apparatus of claim 1 , wherein the oxidizing temperature is at least 400° C.
3. The apparatus of claim 1 wherein said ozonator is capable of producing at least 50% ozone.
4. The apparatus of claim 3 , wherein said ozonator is capable of producing at least 90% ozone.
5. The apparatus of claim 1 , wherein the angular displacement is along the angular direction.
6. The apparatus of claim 1 , wherein the angular separation is 90°.
7. The apparatus of claim 1 , wherein the heat source includes a plurality of incandescent lamps directing radiation toward the substrate parallel to the central axis.