Method of depositing silicone dioxide films

1. A method of forming a silicon dioxide film on a substrate, including the steps of:

supplying TEOS via a carrier gas, supplying oxygen or a source of oxygen, and supplying hydrogen as precursors to a chamber containing the substrate, wherein a ratio of a rate of flow of the carrier gas for the TEOS to a rate of flow of hydrogen, to the chamber, is in a range between 0.67:1 and 2:1;

producing a plasma from the precursors; and

performing plasma enhanced chemical vapour deposition using the plasma and while the temperature in the chamber is in a range of 125 to 175° C. to deposit silicon dioxide on the substrate.

2. A method according claim 1 further comprising treating the deposited silicon dioxide with a hydrogen plasma as a post deposition treatment.

3. A method according to claim 2 wherein the hydrogen plasma post deposition treatment is performed after a vacuum break.

4. A method according to claim 2 wherein the hydrogen plasma treatment is carried out at the same temperature as that at which the silicon dioxide is deposited on the substrate by the plasma enhanced chemical vapour deposition.

5. A method according to claim 2 wherein the plasma is produced by exciting the precursors with RF power having a high frequency RF component and a low frequency RF component.

6. A method according to claim 5 wherein the high frequency component is a component having a frequency of 13.56 MHz and power level in a range of 600 to 1200 W and the low frequency component is a component having a frequency of 350 kHz to 2 MHz and power level in a range of from 300 to 500 W.

7. A silicon dioxide film made according to a method as claimed in claim 1 .