Method of manufacturing magnetoresistive random access memory (MRAM) device

1. A method for fabricating semiconductor device, comprising:

forming a first magnetic tunneling junction (MTJ) on a substrate;

forming a first top electrode on the first MTJ;

forming a first ultra low-k (ULK) dielectric layer on the first MTJ;

performing a first etching process to remove part of the first ULK dielectric layer and form a damaged layer on the first ULK dielectric layer while the first ULK dielectric layer covers the first MTJ and directly contacts a top surface of the first top electrode; and

forming a second ULK dielectric layer on the damaged layer.

2. The method of claim 1 , wherein the first etching process comprises bombarding nitrogen gas (N 2 ) into the first ULK dielectric layer to form the damaged layer.

3. The method of claim 1 , wherein a top surface of the first ULK dielectric layer comprises a curve, the method comprises:

performing the first etching process to transform the curve into a V-shape.

4. The method of claim 1 , further comprising:

forming the first MTJ and a second MTJ on the substrate

forming the first ULK dielectric layer on the first MTJ and the second MTJ and forming a first opening between the first MTJ and the second MTJ;

performing the first etching process to form a second opening between the first MTJ and the second MTJ; and

performing a second etching process to remove part of the first ULK dielectric layer to form a third opening between the first MTJ and the second MTJ before forming the second ULK dielectric layer.

5. The method of claim 4 , wherein a width of the first opening is less than a width of the second opening.

6. The method of claim 4 , wherein a width of the second opening is less than a width of the third opening.