Integrated circuits with magnetic core inductors and methods of fabrications thereof
In one embodiment, a method of forming a semiconductor device includes forming a first inductor coil within and/or over a substrate. The first inductor coil is formed adjacent a top side of the substrate. First trenches are formed within the substrate adjacent the first inductor coil. The first trenches are filled at least partially with a magnetic fill material. At least a first portion of the substrate underlying the first inductor coil is thinned. A backside magnetic layer is formed under the first portion of the substrate. The backside magnetic layer and the magnetic fill material form at least a part of a magnetic core region of the first inductor coil.
1. A method of forming a semiconductor device, the method comprising:
forming a first inductor coil within and/or over a substrate, the first inductor coil formed adjacent a top side of the substrate, wherein metal lines of the first inductor coil are formed in a plurality of metal levels over the substrate;
forming first trenches within the substrate adjacent the first inductor coil;
filling the first trenches at least partially with a magnetic fill material;
thinning at least a first portion of the substrate underlying the first inductor coil; and
forming a backside magnetic layer under the first portion of the substrate, wherein the backside magnetic layer and the magnetic fill material form at least a part of a magnetic core region of the first inductor coil.
2. The method of claim 1 , wherein the first trenches are formed around the first inductor coil.
3. The method of claim 1 , wherein the first inductor coil surrounds at least one trench of the first trenches.
4. The method of claim 1 , wherein forming first trenches within the substrate adjacent the first inductor coil comprises laterally etching portions of the substrate between adjacent trenches.
5. The method of claim 1 , wherein thinning at least a first portion of the substrate underlying the first inductor coil comprises globally thinning the substrate from a backside of the substrate, the backside being opposite to the top side.
6. The method of claim 1 , wherein thinning at least a first portion of the substrate underlying the first inductor coil comprises etching a backside opening underneath the first inductor coil, and wherein forming a backside magnetic layer comprises filling the backside opening with the backside magnetic layer.
7. The method of claim 1 , wherein the magnetic fill material and the backside magnetic layer comprise a ferromagnetic or ferrimagnetic material.
8. The method of claim 1 , wherein the magnetic fill material comprises a material selected from the group consisting of MnZn ferrite, NiZn ferrite, NiFe ferrite, NiCuZn alloy, mu-metals, iron, nickel, and combinations thereof.
9. The method of claim 1 , further comprising:
forming a second inductor coil within and/or over the substrate, the second inductor coil formed adjacent the top side of the substrate, wherein the second inductor coil is formed adjacent the first inductor coil;
forming second trenches within the substrate adjacent the second inductor coil;
filling the second trenches at least partially with the magnetic fill material;
thinning at least a second portion of the substrate underlying the first inductor coil; and
forming the backside magnetic layer under the second portion of the substrate, wherein the backside magnetic layer and the magnetic fill material form at least a part of a magnetic core region of the second inductor coil.
10. The method of claim 5 , wherein forming a backside magnetic layer comprises depositing a blanket layer of the backside magnetic layer under the backside of the substrate.
11. The method of claim 5 , wherein forming a backside magnetic layer comprises filling in a mold compound comprising magnetic particles.
12. The method of claim 5 , wherein forming a backside magnetic layer comprises forming the backside magnetic layer locally underneath the first inductor coil.
13. A method of forming a semiconductor device, the method comprising:
forming a first inductor coil within and/or over a substrate, the first inductor coil formed adjacent a top side of the substrate, wherein metal lines of the first inductor coil are formed in a plurality of metal levels over the substrate;
forming first trenches within the substrate adjacent the first inductor coil;
filling the first trenches with a magnetic fill material;
attaching a carrier to the top side of the substrate; and
encapsulating the substrate and the first inductor coil with a magnetic mold compound.
14. The method of claim 13 , wherein the magnetic mold compound and the magnetic fill material form at least a part of a magnetic core region of the first inductor coil.
15. The method of claim 13 , wherein the first trenches are formed around the first inductor coil.
16. The method of claim 13 , wherein the first inductor coil surrounds at least one trench of the first trenches.
17. The method of claim 13 , wherein the magnetic mold compound comprises magnetic particles comprising a material selected from the group consisting of MnZn ferrite, NiZn ferrite, NiFe ferrite, NiCuZn alloy, mu-metals, iron, nickel, and combinations thereof, and wherein the magnetic fill material comprises a material selected from the group consisting of MnZn ferrite, NiZn ferrite, NiFe ferrite, NiCuZn alloy, mu-metals, iron, nickel, and combinations thereof.
18. The method of claim 13 , further comprising:
thinning the substrate before attaching the carrier;
separating the carrier from the encapsulated substrate and the first inductor coil; and
singulating the encapsulated substrate and the first inductor coil into individual chips after separating the carrier.
19. A method of forming a semiconductor device comprising:
forming metal lines of a first inductor coil within and/or over a substrate, the metal lines disposed adjacent a top side of the substrate than an opposite back side, wherein the metal lines of the first inductor coil are formed in a plurality of metal levels over the substrate;
forming first trenches within the substrate adjacent the first inductor coil;
at least partially filling the first trenches with a magnetic fill material; and
forming a magnetic material under a first portion of the substrate, wherein at least a part of a magnetic core region of the first inductor coil comprises the magnetic material and the magnetic fill material.
20. The method of claim 19 , wherein the first trenches are formed around the first inductor coil.
21. The method of claim 19 , wherein the first inductor coil surrounds at least one trench of the first trenches.
22. The method of claim 19 , wherein the magnetic material is formed under substantially the entire back side of the substrate.
23. The method of claim 19 , wherein the magnetic material comprises a mold compound comprising magnetic particles.
24. The method of claim 19 , further comprising forming an embedded wafer level ball grid array (eWLB) package.
25. The method of claim 19 , further comprising injection molding to form an injection molded package.
26. The method of claim 23 , wherein forming the magnetic material under the first portion of the substrate comprises encapsulating the substrate with the magnetic material.
27. The method of claim 26 , further comprising forming a wafer level ball grid array (eWLB) package.