Method for isolating semiconductor devices with use of shallow trench isolation method

1. A method for isolating devices on a substrate by forming a trench, comprising the steps of:

forming a patterned pad nitride layer to open at least one isolation region on the substrate;

forming a first trench and a second trench by etching the exposed substrate;

depositing a first oxide layer to fill the first trench and the second trench by performing an atomic layer deposition (ALD) method, wherein one of pyridine and ammonia is used as a catalyst for lowering a reaction activation energy level;

etching a whole portion of the first oxide layer filled into the second trench; and

depositing a second oxide layer in the second trench by performing a deposition method after etching the whole portion of the first oxide layer in the second trench.

2. The method of claim 1 , wherein the deposition method has a higher deposition rate than the ALD method does to thereby completely fill the second trench with the second oxide layer.

3. The method of claim 1 , further includes the step of:

forming an etch stop layer on the substrate prior to depositing the first oxide layer.

4. The method of claim 3 , wherein the etch stop layer is a liner nitride layer.

5. The method of claim 3 , wherein the etch stop layer is formed by performing a low pressure chemical vapor deposition (LP-CVD) method until reaching a thickness ranging from approximately 10 Å to approximately 200 Å.

6. The method of claim 4 , wherein the etch stop layer is formed by performing a LP-CVD method until reaching a thickness ranging from approximately 10 Å to approximately 200 Å.

7. The method of claim 1 , wherein prior to depositing the first oxide layer, a third oxide layer is formed on the substrate by a thermal oxidation process in order to minimize the deposition thickness of the first oxide layer.

8. The method of claim 1 , wherein the first oxide layer is formed by repeatedly performing a cycle of providing alternately a source gas of silicon selected from a group of Si x Cl y , where x representing an atomic ratio of silicon is in a range from approximately 1 to approximately 4 and y representing an atomic ratio of chlorine is in a range from approximately 1 to approximately 8, and a source gas of oxygen into a reaction chamber.

9. The method of claim 1 , wherein after the deposition of the first oxide layer, a thermal process is performed to densify the first oxide layer.

10. The method of claim 2 , wherein the second oxide layer is deposited by performing one of a high density plasma (HDP)-CVD method, an atmospheric pressure (AP)-CVD method and a sub-atmospheric (SA)-CVD method.

11. The method of claim 1 , wherein a width of the second trench is greater than that of the first trench.