Etching solution and trench isolation structure-formation process employing the same
View Patent ↗The present invention provides an etching solution less affected by trench structures and also provides an isolation structure-formation process employing the solution. The etching solution contains hydrofluoric acid and an organic solvent. The organic solvent has a δH value defined by Hansen solubility parameters in the range of 4 to 12 inclusive and the saturation solubility thereof in water is 5 wt % or more at 20° C. This solution can be adopted instead of known etching solutions used in conventional production processes of semiconductor elements.
1. A process for forming a shallow trench isolation structure, comprising the steps of:
coating a composition containing insulating material onto a substrate surface provided with a trench structure, to form a coating layer;
firing the coated substrate to harden the insulating material, so as to form an insulating layer;
polishing the insulating layer so as to remove the part formed on the flat surface of the substrate and to leave the part formed in the trenches on the substrate and
subjecting the insulating layer after polished to etching treatment by use of an etching solution containing hydrofluoric acid and an organic solvent, wherein said hydrofluoric acid is contained in an amount of 0.06 to 2 wt % based on the total weight of the solution, and wherein said organic solvent has a δH value defined by Hansen solubility parameters in the range of 4 to 12 inclusive and the saturation solubility thereof in water is 5 wt % or more at 20° C. and wherein said insulating material is a polysilazane compound and said insulating layer is a siliceous film and further wherein the etching solution removes evenly the insulating layer by etching where the widths of the trenches are different from each other.
2. The process according to claim 1 for forming a shallow trench isolation structure, which further comprises the step of polishing the insulating layer formed on the substrate after the step of firing.
3. The process according to claim 2 for forming a shallow trench isolation structure, wherein the step of polishing is carried out according to chemical mechanical polishing.
4. The process according to claim 1 for forming a shallow trench isolation structure, wherein the etching solution containing hydrofluoric acid comprises 0.1 to 1 wt % hydrofluoric acid.
5. The process according to claim 1 for forming a shallow trench isolation structure, wherein the organic solvent is chosen from the group consisting of acetoaldehyde, acetone, acetylacetone, allyl acetoacetate, butyric acid, crotonic acid, diethyl ether, diethyl ketone, diethyl glycol butyl ether acetate, diethyl glycol monobutyl ether, dimethoxymethane, dimethyl diketone, dimethyl ether, dipropylene glycol monomethyl ether acetate, ethyl acetate, ethyl acetoacetate, ethylene glycol dimethyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monomethyl ether acetate, iso-butyric acid, methacrylic acid, methyl acetate, methyl acetoacetate, methyl ethyl ether, methyl ethyl ketone, methyl formate, methylglyoxal, glutaric acid dimethyl ester, 2,4-pentanedione, propionaldehyde, propylene glycol monoethyl ether, propylene glycol monoethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate and tripropylene glycol monomethyl ether.
6. The process according to claim 1 for forming a shallow trench isolation structure, wherein the organic solvent is chosen from the group consisting of acetone, crotonic acid, ethyl acetoacetate, ethylene glycol monomethyl ether acetate, methyl ethyl ketone, 2,4-pentanedione, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate.
7. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer is done at a temperature between 300 to 900° C. for 15 minutes to 3 hours.
8. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer is done in steam containing oxygen or an inert gas.
9. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer is done in steam containing oxygen or an inert gas wherein the concentration of steam is higher than 1 wt %.
10. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer is done in steam containing oxygen or an inert gas wherein the concentration of steam is higher than 10 wt %.
11. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer is done in steam containing oxygen or an inert gas wherein the concentration of steam is higher than 20 wt %.
12. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer wherein the coating layer has a thickness of 20 to 150 nm.
13. The process according to claim 1 for forming a shallow trench isolation structure wherein firing the coated substrate to harden the insulating material, so as to form an insulating layer wherein the coating layer has a thickness of 30 to 100 nm.