Apparatus for sputtering and operation method thereof

1. A sputtering apparatus, comprising:

a magnetron structure including an outer pole and an inner pole, configured to erode a target according to a predetermined erosion rate profile symmetric to a central axis of the magnetron structure, wherein:

the outer pole and the inner pole of the magnetron structure are arranged in accordance with a predetermined normalized loop length profile,

the predetermined normalized loop length profile includes a portion of a normalized loop length being substantially constant for about 0.4 of a radius of the target from the central axis, and

the predetermined erosion rate profile includes:

a first peak rate in proximity to the central axis; and

a second peak rate located at about from 0.7 to 0.75 of the radius of the target from the central axis, the first peak rate being substantially equal to the second peak rate.

2. The apparatus of claim 1 , wherein the outer pole has a first magnetic polarity and the inner pole has a second magnetic polarity opposite to the first magnetic polarity, the inner pole being surrounded by the outer pole.

3. The apparatus of claim 1 , wherein the normalized loop length transforms from a substantially constant profile to an increasing profile at about 0.4 of the radius of the target.

4. The apparatus of claim 3 , wherein the increasing profile comprises a nonlinear curve beyond 0.4 of the radius of the target.

5. The apparatus of claim 2 , wherein the inner pole comprises a terminal portion pointing toward the central axis.

6. The apparatus of claim 5 , wherein a portion of the magnetron structure outside a boundary and being tangential to a circle centering at the central axis is substantially greater than a portion of the magnetron inside the boundary and being tangential to the circle, the boundary enclosing the terminal portion of the inner pole and a terminal portion of the outer pole.

7. A sputtering apparatus, comprising:

a magnetron structure, comprising:

a first portion outside a boundary;

a second portion inside the boundary; and

an outer pole and an inner pole,

wherein:

an amount of the first portion being tangential to a circle centering at a central axis is substantially greater than an amount of the second portion being tangential to the circle,

the inner and outer poles are arranged in accordance with a predetermined normalized loop length profile that has a portion of a normalized loop length being substantially constant for about 0.4 of a radius of a target from the central axis, and

the magnetron structure is configured to erode the target according to a predetermined profile of erosion rate that includes:

a first peak rate near the central axis of the magnetron structure; and

a second peak rate at about from 0.7 to 0.75 of the radius of the target from the central axis.

8. The apparatus of claim 7 , wherein the profile includes a third peak rate at around 0.5 of the radius of the target from the central axis.

9. The apparatus of claim 7 , wherein the outer pole of a first magnetic polarity is arranged in a closed band and, the inner pole enclosed by the outer pole includes a second magnetic polarity opposite to the first magnetic polarity.

10. The apparatus of claim 9 , wherein the inner pole comprises a terminal portion in proximity to the central axis.

11. The apparatus of claim 9 , wherein a distance between the inner pole and the outer pole is substantially constant.

12. The apparatus of claim 10 , wherein the boundary comprises a circular shape surrounding the terminal portion of the inner pole.

13. The apparatus of claim 7 , wherein the amount of the second portion being tangential to a circle is approximately constant inside the boundary.

14. The apparatus of claim 12 , wherein the first portion sweeps through more than 270 degrees around the central axis.

15. A method of sputtering, comprising:

positioning a wafer at a predetermined distance from a target;

rotating a magnetron structure with respect to a central axis, wherein:

the magnetron structure includes an outer pole and an inner pole that are arranged in accordance with a predetermined normalized loop length profile, and

the predetermined normalized loop length profile includes a portion of a normalized loop length being substantially constant for about 0.4 of a radius of the target from the central axis; and

eroding the target according to a predetermined erosion rate profile, the target on the central axis being eroded at a first rate, the target near from 0.5 to 0.55 of the radius thereof being eroded at about 0.5 of the first rate; and the target near from 0.7 to 0.75 of the radius thereof being eroded at about 1.1 of the first rate.

16. The method of claim 15 , wherein the outer pole of a first magnetic polarity has a closed loop, the inner pole is enclosed by the outer pole, and the inner pole includes a second magnetic polarity opposite to the first magnetic polarity.

17. The method of claim 16 , wherein positioning the wafer at the predetermined distance from the target includes: positioning the wafer from about 40 millimeters to 70 millimeters from the target.

18. The method of claim 15 , wherein the target comprises titanium nitride.

19. The method of claim 16 , wherein: the magnetron structure is configured to have a first portion outside a boundary and a second portion inside the boundary, and an amount of the first portion being tangential to a circle centering at the central axis is substantially greater than an amount of the second portion being tangential to the circle.

20. The method of claim 19 , wherein the boundary comprises a shape of a circle and encloses the central axis and terminal portions of the inner pole and the outer pole.

21. The method of claim 20 , wherein the boundary comprises a radius in a range of from about 70 mm to about 80 mm.