Thin film head, producing method thereof and magnetic disk apparatus

1. A thin film head having reading part and recording part comprising:

an upper magnetic pole front end layer; and

a lower magnetic pole having a lower magnetic main layer, a lower magnetic pole front end portion above the lower magnetic main layer, and a projection step portion above the lower magnetic pole front end portion;

wherein a length of the lower magnetic pole front end portion in a depth direction is smaller than a length of the lower magnetic main layer in the depth direction;

wherein a length of the projection step portion in the depth direction is smaller than the length of the lower magnetic main layer in the depth direction;

wherein a width of the lower magnetic pole front end portion in a track width direction is smaller than a width of the lower magnetic main layer in the track width direction;

wherein a width of the projection step portion in the track width direction is smaller than the width of the lower magnetic pole front end portion in the track width direction; and

wherein the upper magnetic pole front end layer has a magnetic pole expansion position; and

wherein a length in the depth direction from an air bearing surface to the magnetic pole expansion position is less than a length from the air bearing surface to a gap depth position of the lower magnetic pole front end portion.

2. A thin film head according to claim 1 , further comprising:

an insulating layer sharing edges of the lower magnetic pole front end portion and the projection step portion;

a coil covered with the insulating layer; and

a gap layer formed on the projection step portion and the insulating layer;

wherein a taper surface is formed on an upper surface of the lower magnetic pole front end portion.

3. A thin film head according to claim 2 , wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

4. A thin film head according to claim 2 , wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 10°, and not greater than 60°.

5. A thin film head according to claim 1 , wherein multiple taper surfaces are formed on an upper surface of the lower magnetic pole front end portion.

6. A thin film head according to claim 5 , wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

7. A thin film head according to claim 5 , wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 10°, not greater than 60°.

8. A thin film head having reading part and recording part comprising:

an upper magnetic pole front end layer; and

a lower magnetic pole having a lower magnetic main layer, a lower magnetic pole front end portion and a projection step portion;

wherein the lower magnetic pole front end portion is formed between the lower magnetic main layer and the projection step portion;

wherein each of the lower magnetic main layer, the lower magnetic pole front end portion, and the projection step portion has a first edge exposed to an air bearing surface and a second edge in a depth direction;

wherein a distance between the first and second edge of the lower magnetic pole front end portion is shorter than a distance between the first and second edge of the lower magnetic main layer;

wherein the upper magnetic pole front end layer has a first magnetic pole expansion position and a second magnetic pole expansion position;

wherein the first magnetic pole expansion position is formed between the air bearing surface and the second magnetic pole expansion position; and

wherein a length in a depth direction from the air bearing surface to the first magnetic pole expansion position is less than a length from the air bearing surface to a gap depth position of the lower magnetic pole front end portion.

9. A thin film head according to claim 8 , further comprising:

an insulating layer formed from the second edae of the projection step portion; and

a gap layer formed on the insulating layer and the projection step portion;

wherein a taper surface is formed on an upper surface of the lower magnetic pole front end portion;

wherein a width of the lower magnetic pole front end portion in a track width direction is smaller than a width of the lower magnetic main layer in the track width direction;

wherein a width of the projection step portion in the track width direction is smaller than the width of the lower magnetic pole front end portion in the track width direction; and

wherein the second edge of the projection step portion and the second edge of the lower magnetic pole front end portion are made on a same plane.

10. A thin film head according to claim 9 , wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

11. A thin film head according to claim 9 , wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 10°, and not greater than 60°.

12. A thin film head according to claim 8 , wherein multiple taper surfaces are formed on an upper surface of the lower magnetic pole front end portion.

13. A thin film head according to claim 12 , wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

14. A thin film head according to claim 12 , wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 10°, and not greater than 60°.

15. A thin film head according to claim 8 , wherein an expansion angle at the first magnetic pole expansion position is less than an expansion angle at the second magnetic pole expansion position.

16. A thin film head having reading part and recording part comprising:

an upper magnetic pole front end layer; and

a lower magnetic pole having a lower magnetic main layer, a lower magnetic pole front end portion above the lower magnetic main layer, and a projection step portion above the lower magnetic pole front end portion;

wherein the lower magnetic main layer, the lower magnetic pole front end portion, and the projection step portion are exposed to an air bearing surface;

wherein a length of the lower magnetic pole front end portion in a depth direction is smaller than a length of the lower magnetic main layer in the depth direction;

wherein a length of the projection step portion in the depth direction is smaller than the length of the lower magnetic main layer in the depth direction;

wherein a width of the lower magnetic pole front end portion in a track width direction is smaller than a width of the lower magnetic main layer in the track width direction;

wherein a width of the projection step portion in the track width direction is smaller than the width of the lower magnetic pole front end portion in the track width direction; and

wherein a taper surface is formed on upper surface of the lower magnetic pole front end portion, which is formed adjacent to the projection step portion.

17. A thin film head according to claim 16 , further comprising:

a first coil and a second coil;

an insulating layer covering the first coil; and

a gap layer formed on the projection step portion and the insulating layer;

wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

18. A thin film head according to claim 16 ,

wherein the second coil is formed above the first coil;

wherein the insulating layer is formed between the gap layer and the lower magnetic main layer;

wherein the lower magnetic pole front end portion and the projection step portion are formed between the insulating layer and the air bearing surface;

wherein an angle formed by the taper surface and a surface of the lower magnetic main layer is at least 10°, and not greater than 60°.

19. A thin film head having reading part and recording part comprising:

an upper magnetic pole front end layer; and

a lower magnetic pole having a lower magnetic main layer, a lower magnetic pole front end portion, and a projection step portion;

wherein the lower magnetic pole front end portion is formed between the lower magnetic main layer and the projection step portion;

wherein each of the lower magnetic main layer, the lower magnetic pole front end portion, the projection step portion each has a first edge exposed to an air bearing surface and a second edge in a depth direction;

wherein a distance between the first and second edge of the lower magnetic pole front end portion is shorter than a distance between the first and second edge of the lower magnetic main layer; and

wherein multiple taper surfaces are formed on an upper surface of the lower magnetic pole front end portion.

20. A thin film head according to claim 19 , further comprising:

an insulating layer formed from the second edge of the projection step portion; and

a gap layer formed on the insulating layer and the projection step portion;

wherein a width of the lower magnetic pole front end portion in a track width direction is smaller than a width of the lower magnetic main layer in the track width direction;

wherein a width of the projection step portion in the track width direction is smaller than a width of the lower magnetic pole front end portion in the track width direction; and

wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 20°, and not greater than 40°.

21. A thin film head according to claim 19 , wherein each of angles formed by each of the multiple taper surfaces and a surface of the lower magnetic main layer is at least 10°, and not greater than 60°.