Inductor on microelectronic die
A microelectronic device has bump bonds and an inductor on a die. The microelectronic device includes first lateral conductors extending along a terminal surface of the die, wherein at least some of the first lateral conductors contact at least some of terminals of the die. The microelectronic device also includes conductive columns on the first lateral conductors, extending perpendicularly from the terminal surface, and second lateral conductors on the conductive columns, opposite from the first lateral conductors, extending laterally in a plane parallel to the terminal surface. A first set of the first lateral conductors, the conductive columns, and the second lateral conductors provide the bump bonds of the microelectronic device. A second set of the first lateral conductors, the conductive columns, and the second lateral conductors are electrically coupled in series to form the inductor. Methods of forming the microelectronic device are also disclosed.
1. A method, comprising:
forming a first metal column on a first bond pad of a die;
forming a first metal strip on the die;
forming a second metal column on the first metal strip; and
forming a second metal strip on the first and second metal columns and over the die, in which the second metal strip has a pair of bent segments and a straight segment coupled between the pair of bent segments.
2. The method of claim 1 , further comprising:
forming a third metal column on the first metal strip or on the die;
forming a fourth metal column on a second bond pad of the die; and
forming a third metal strip on the third and fourth metal columns and over the die, in which the third metal strip has a second pair of bent segments and a second straight segment coupled between the second pair of bent segments.
3. The method of claim 2 , further comprising:
forming a seed layer on the die, the seed layer including at least one of: titanium, tungsten, chromium, or nickel,
wherein the first metal strip is formed on the seed layer.
4. The method of claim 1 , wherein a thickness of the first metal strip is between 3 microns and 30 microns.
5. The method of claim 2 , wherein:
each of the first through fourth metal columns includes copper;
a respective width of each of the first through third metal columns is between 25 microns and 50 microns;
a respective length of each of the first through third metal columns is between 25 microns and 300 microns; and
a respective height of each of the first through third metal columns is between 30 microns and 100 microns.
6. The method of claim 2 , further comprising:
forming a first seed layer on the first metal strip; and
forming a second seed layer on the first, second, third, and fourth metal columns,
wherein:
the second metal column and the third metal column are formed on the first seed layer;
the second and third metal strips are formed on the second seed layer; and
each of the first and second seed layers includes at least one of: titanium, chromium, or nickel.
7. The method of claim 2 , wherein
the second and third metal strips include copper.
8. The method of claim 2 , wherein a respective thickness of each of the second and third metal strips is between 3 microns to 30 microns.
9. The method of claim 2 , further comprising:
forming a first layer of die attach material on the second metal strip; and
forming a second layer of die attach material on the third metal strip,
wherein the die attach material includes at least one of: a solder, or an adhesive.
10. The method of claim 2 , further comprising:
forming a magnetic material around at least parts of the first through third metal strips and at least parts of the first through fourth metal columns.
11. The method of claim 10 , wherein the magnetic material includes magnetic particles, and a molding compound in which the magnetic particles are suspended.
12. The method of claim 10 , wherein the first through fourth metal columns and the first through third metal strips are part of an inductor electrically coupled between the first and second bond pads, in which the inductor has a linear configuration.
13. The method of claim 10 , further comprising forming a fourth metal strip on the die and between the first and second bond pads,
wherein the first through fourth metal columns and the first through fourth metal strips are part of an inductor having a toroidal configuration.
14. The method of claim 2 , further comprising:
forming a fifth metal column on a third bond pad on the die; and
forming a fourth metal strip on the fifth metal column over the die; and
forming a layer of die attach material on the fourth metal strip.
15. The method of claim 2 , further comprising:
forming a fourth metal strip having a first end on a third bond pad on the die;
forming a fifth metal column on a second end of the fourth metal strip, the second end being opposite to the first end; and
forming a layer of die attach material on the fifth metal column, in which the fifth metal column is between the layer of die attach material and the fourth metal strip.
16. The method of claim 6 , further comprising:
forming a first patterned mask layer on the die, wherein the first metal strip is formed through the patterned first mask layer, and the first seed layer is formed on the patterned first mask layer and the first metal strip;
forming a second patterned mask layer on the first seed layer to expose part of the first seed layer, wherein the first, second, third, and fourth metal columns are formed through the patterned first mask layer and the patterned second mask layer on the exposed part of the first seed layer, and the second seed layer is formed on the first, second, third, and fourth metal columns and on the patterned second mask layer; and
forming a third patterned mask layer on the second seed layer to expose part of the second seed layer, wherein the second and third metal strips are formed through the patterned third mask layer on the exposed part of the second seed layer.
17. The method of claim 16 , wherein the first, second, third, and fourth metal columns and the first through third metal strips are formed by an electroplating process or an electroless plating operation.
18. The method of claim 17 , wherein the electroplating process or the electroless plating operation is performed in a plating bath.
19. The method of claim 16 , further comprising:
removing the third patterned mask layer;
removing part of the second seed layer not covered by the second and third metal strips;
removing the second patterned mask layer; and
removing part of the first seed layer not covered by the first, second, third, and fourth metal columns.
20. The method of claim 16 , wherein the first, second, and third patterned mask layers are formed by at least one of: a photolithographic process, an additive process, or a laser ablation process.