Enhanced densification of silicon oxide layers
View Patent ↗Densifying a multi-layer substrate includes providing a substrate with a first dielectric layer on a surface of the substrate. The first dielectric layer includes a multiplicity of pores. Water is introduced into the pores of the first dielectric layer to form a water-containing dielectric layer. A second dielectric layer is provided on the surface of the water-containing first dielectric layer. The first and second dielectric layers are annealed at temperature of 600° C. or less. In an example, the multi-layer substrate is a nanoimprint lithography template. The second dielectric layer may have a density and therefore an etch rate similar to that of thermal oxide, yet may still be porous enough to allow more rapid diffusion of helium than a thermal oxide layer.
1. A method comprising:
providing a substrate with a first dielectric layer, wherein the first dielectric layer defines a multiplicity of water-containing pores and wherein providing the substrate with the first dielectric layer further comprises forming the first dielectric layer on the substrate and contacting the first dielectric layer with a fluid comprising water;
providing a second dielectric layer on the water-containing first dielectric layer; and
steam annealing the first and second dielectric layers at a temperature of 600° C. or less.
2. The method of claim 1 , wherein the substrate is impermeable to water.
3. The method of claim 1 , wherein steam annealing the first and second dielectric layers at a temperature of 600° C. or less increases the density of the first dielectric layer and the second dielectric layer.
4. The method of claim 1 , wherein before steam annealing, the first dielectric layer comprises SiO x , wherein x≠2.
5. The method of claim 1 , wherein the first dielectric layer comprises a silicon-containing polymer.
6. The method of claim 1 , wherein providing the second dielectric layer on the first dielectric layer comprises a chemical vapor deposition process or a spin coating process.
7. The method of claim 6 , wherein providing the second dielectric layer on the first dielectric layer comprises a spin coating process, and the spin coating process comprises spin coating a polysilazane film or a spin-on-glass film on the water-containing first dielectric layer.
8. The method of claim 1 , wherein a ratio of an etch rate of the second dielectric layer after annealing to an etch rate of thermal oxide is between 1:1 and 1.25:1.
9. The method of claim 1 , wherein forming the first dielectric layer on the substrate comprises a spin coating process or a chemical vapor deposition process.
10. The method of claim 1 , wherein the fluid is a vapor or a liquid.
11. The method of claim 1 , wherein contacting the first dielectric layer with a fluid comprising water comprises chemical mechanical planarization of the first dielectric layer.
12. The method of claim 1 , wherein contacting the first dielectric layer with a fluid comprising water comprises contacting the first dielectric layer with an aqueous solution or water.
13. A device fabricated by the method of claim 1 .
14. A method of fabricating an imprint lithography template, the method comprising:
providing a fused silica substrate with a porous layer, wherein the porous layer defines a multiplicity of water-containing pores and wherein providing the fused silica substrate with the porous layer further comprises forming the porous layer on the fused silica substrate and contacting the porous layer with a fluid comprising water;
providing a cap layer on the water-containing porous layer; and
steam annealing the porous layer and the cap layer at a temperature of 600° C. or less to increase a density of the cap layer.
15. The method of claim 14 , wherein providing the cap layer on the water-containing porous layer comprises spin-coating a polymerizable material on the water-containing porous layer.
16. The method of claim 15 , further comprising patterning the polymerizable material to form a patterned cap layer on the water-containing porous layer.
17. The method of claim 15 , further comprising pre-baking the polymerizable material before steam annealing the porous layer and the cap layer.
18. An imprint lithography template fabricated by the method of claim 14 .