Method for isolating semiconductor devices
View Patent ↗A method of isolating semiconductor devices including forming a pad layer on a semiconductor substrate, forming a trench by etching the semiconductor substrate to a predetermined depth using the pad layer as an etch barrier, implanting ion impurities into a bottom of the trench so as to increase an oxidation rate thereat, performing heat treatment for activating ion implanted impurities, growing a liner oxide film on a bottom and a sidewall of the trench, forming an isolation film on the liner oxide film so as to fill the trench, and smoothing the isolation film.
1. A method for isolating semiconductor devices, comprising the steps of:
forming a pad layer including at least one pad nitride film on a semiconductor substrate;
forming a trench by etching the semiconductor substrate to a predetermined depth using the pad layer as an etch barrier;
forming a sacrificing oxide film on a front surface including the trench;
forming a nitride sidewall on the sacrificing oxide film at a sidewall of the trench;
performing impurity ion implantation on a bottom of the trench exposed to an outside of the sidewall of the nitride film so as to increase an oxidation rate thereat;
performing heat treatment for activating implanted ion impurities;
removing the nitride sidewall and the sacrificing oxide film;
growing a liner oxide film on both the bottom and the sidewall of the trench;
forming a nitride film on the liner oxide film so as to fill the trench; and
smoothing the isolation film.
2. The method of claim 1 , wherein the step of forming a nitride sidewall comprises the steps of:
depositing the nitride film on the sacrificing oxide film; and
etching back the nitride film.
3. The method of claim 1 , wherein the step of performing impurity ion implantation includes implanting an impurity selected from n type impurity, p type impurity, and a nitride ion.
4. The method of claim 1 , wherein the step of performing impurity ion implantation includes implanting impurities with an energy in a range of about 25 to about 100 keV and a dose of impurity of about 1×10 12 cm −3 to about 1×10 18 cm −3 .
5. The method of claim 1 , wherein the trench has an inclined profile.
6. The method of claim 1 , wherein the step of removing the nitride sidewall includes removing the nitride sidewall using a phosphoric acid solution and the step of removing the sacrificing oxide film includes removing the sacrificing oxide film using hydrofluoric acid.