Surface treatment and deposition for reduced outgassing
A method of forming a dielectric layer is described. The method first deposits a silicon-nitrogen-and-hydrogen-containing (polysilazane) layer by radical-component chemical vapor deposition (CVD). The silicon-nitrogen-and-hydrogen-containing layer is formed by combining a radical precursor (excited in a remote plasma) with an unexcited carbon-free silicon precursor. A silicon oxide capping layer may be formed from a portion of the carbon-free silicon-nitrogen-and-hydrogen-containing layer to avoid time-evolution of underlying layer properties prior to conversion into silicon oxide. Alternatively, the silicon oxide capping layer is formed over the silicon-nitrogen-and-hydrogen-containing layer. Either method of formation involves the formation of a local plasma within the substrate processing region.
1. A method of forming a dielectric layer on a substrate, the method comprising the sequential steps of:
forming a carbon-free silicon-nitrogen-and-hydrogen-containing layer on the substrate in a first substrate processing region containing the substrate by:
flowing an unexcited precursor into a remote plasma region to produce a radical-precursor,
combining a carbon-free silicon-containing precursor with the radical-precursor in the first substrate processing region, wherein the first substrate processing region is devoid of plasma during the forming the carbon-free silicon-nitrogen-and-hydrogen-containing layer, and
depositing a carbon-free silicon-nitrogen-and-hydrogen-containing layer over the substrate, wherein the carbon-free silicon-nitrogen-and-hydrogen-containing layer is flowable during deposition and flows into a trench on a deposition surface of the substrate as the carbon-free silicon-nitrogen-and hydrogen-containing layer deposits; and
forming a silicon oxide capping layer on the carbon-free silicon-nitrogen-and-hydrogen-containing layer by:
flowing an oxygen-containing precursor into a second substrate processing region containing the substrate,
flowing a silicon-containing precursor into the second substrate processing region,
forming a plasma from the oxygen-containing precursor and the silicon-containing precursor in the second substrate processing region, and
depositing the silicon oxide capping layer over the carbon-free silicon-nitrogen-and-hydrogen-containing layer
wherein the dielectric layer comprises the carbon-free silicon-nitrogen-and-hydrogen-containing layer and the silicon oxide capping layer; and
converting the underlying carbon-free silicon-nitrogen-and-hydrogen-containing layer to silicon oxide despite an intervening presence of the silicon oxide capping layer.
2. The method of claim 1 wherein a temperature of the substrate is greater than or about 25° C. and less than or about 125° C. during formation of the carbon-free silicon-nitrogen-and-hydrogen-containing layer.
3. The method of claim 1 wherein the substrate temperature is less than or about 200° C. during formation of the silicon oxide capping layer.
4. The method of claim 1 wherein a thickness of the silicon oxide capping layer is about 10 nm or more.
5. The method of claim 1 wherein the unexcited precursor comprises nitrogen and the radical precursor is a radical-nitrogen precursor.
6. The method of claim 1 wherein the unexcited precursor comprises at least one of N 2 H 2 , NH 3 , N 2 and H 2 and the carbon-free silicon-containing precursor comprises one of H 2 N(SiH 3 ), HN(SiH 3 ) 2 or N(SiH 3 ) 3 .
7. The method of claim 1 wherein the first substrate processing region is the second substrate processing region.
8. The method of claim 1 wherein forming a plasma from the oxygen-containing precursor and the silicon-containing precursor in the second substrate processing region comprises applying a plasma power of below or about 1000 W.
9. The method of claim 1 wherein a thickness of the silicon oxide capping layer is greater than or about 50 nm.