Microfabricated inductors with through-wafer vias

Abstract

The present invention relates to microfabricated inductors with through-wafer vias. In one embodiment, the present invention is an inductor including a first wafer, a first plurality of metal fillings located within the first wafer, and a first plurality of metal conductors connecting the first plurality of metal fillings together to form a first spiral with a first plurality of windings. In another embodiment, the present invention is a method for producing an inductor including the steps of forming a first plurality of vias in a first substrate, filling the first plurality of vias in the first substrate with a first plurality of metal fillings, forming a first plurality of metal conductors, and connecting pairs of the first plurality of metal fillings together using the first plurality of metal conductors to form a spiral.

1 . An inductor comprising:
 a first wafer;   a first plurality of metal fillings located within the first wafer; and   a first plurality of metal conductors connecting the first plurality of metal fillings together to form a first spiral with a first plurality of windings.   
   
   
       2 . The inductor of  claim 1  wherein the first wafer includes a first plurality of vias coated with an insulation material, the first plurality of vias containing the first plurality of metal fillings. 
   
   
       3 . The inductor of  claim 1  wherein the first wafer includes a first plurality of trenches coated with an insulation material, the first plurality of trenches containing the first plurality of metal conductors. 
   
   
       4 . The inductor of  claim 3  wherein each of the first plurality of trenches have a depth to spacing aspect ratio equal to or greater than 2:1. 
   
   
       5 . The inductor of  claim 1  wherein the first plurality of metal fillings is rectangular shaped in cross section. 
   
   
       6 . The inductor of  claim 1  wherein the first plurality of metal fillings is oval shaped in cross section. 
   
   
       7 . The inductor of  claim 1  further comprising:
 a second plurality of metal fillings located within the first wafer, each of the second plurality of metal fillings connected to one of the first plurality of metal fillings to form a metal fillings group conducting in parallel.   
   
   
       8 . The inductor of  claim 1  further comprising:
 a second plurality of metal fillings located within the first wafer; and   a second plurality of metal conductors connecting the second plurality of metal fillings together to form a second spiral including a second plurality of windings, the first spiral connected to the second spiral to form a spiral group conducting in parallel.   
   
   
       9 . An inductor comprising:
 a first wafer;   a first plurality of metal fillings located within the first wafer;   a first plurality of metal conductors connecting pairs of the first plurality of metal fillings together to form a first portion of a first spiral;   a second wafer;   a second plurality of metal fillings located within the second wafer; and   a second plurality of metal conductors connecting pairs of the second plurality of metal fillings together to form a second portion of the first spiral, the first portion of the first spiral and the second portion of the first spiral bonded together to form the first spiral.   
   
   
       10 . The inductor of  claim 9  wherein the first plurality of metal fillings are substantially aligned with the second plurality of metal fillings. 
   
   
       11 . The inductor of  claim 10  wherein the first plurality of metal filings and the second plurality of metal fillings are bonded through a ductile metal bump. 
   
   
       12 . The inductor of  claim 11  wherein the ductile metal bump is a gold bump. 
   
   
       13 . The inductor of  claim 9  wherein
 the first wafer includes a first plurality of vias coated with an insulation material, the first plurality of vias containing the first plurality of metal fillings, and   the second wafer includes a second plurality of vias coated with the insulation material, the second plurality of vias containing the second plurality of metal fillings.   
   
   
       14 . The inductor of  claim 9  wherein
 the first wafer includes a first plurality of trenches coated with an insulation material, the first plurality of trenches containing the first plurality of metal conductors, and   the second wafer includes a second plurality of trenches coated with the insulation material, the second plurality of trenches containing the second plurality of metal conductors.   
   
   
       15 . The inductor of  claim 14  wherein the first plurality of trenches and the second plurality of trenches each have a depth to spacing aspect ratio equal to or greater than 2:1. 
   
   
       16 . The inductor of  claim 9  wherein the first plurality of metal fillings is rectangular shaped in cross section. 
   
   
       17 . The inductor of  claim 9  wherein the first plurality of metal fillings is oval shaped in cross section. 
   
   
       18 . The inductor of  claim 9  further comprising:
 a third plurality of metal fillings located within the first wafer, each of the third plurality of metal fillings connected to one of the first plurality of metal fillings to form a first metal fillings group conducting in parallel; and   a fourth plurality of metal fillings located within the second wafer, each of the fourth plurality of metal fillings connected to one of the second plurality of metal fillings to form a second metal fillings group conducting in parallel.   
   
   
       19 . The inductor of  claim 9  further comprising:
 a third plurality of metal fillings located within the first wafer;   a third plurality of metal conductors connecting pairs of the third plurality of metal fillings together to form a first portion of a second spiral;   a fourth plurality of metal fillings located within the second wafer; and   a fourth plurality of metal conductors connecting pairs of the fourth plurality of metal fillings together, to form a second portion of the second spiral, the first portion of the first spiral and the second portion of the second spiral bonded to form the second spiral, wherein the first spiral and the second spiral are connected to form a spiral group conducting in parallel.   
   
   
       20 . A method for producing an inductor comprising the steps of:
 forming a first plurality of vias in a first substrate;   filling the first plurality of vias in the first substrate with a first plurality of metal fillings;   forming a first plurality of metal conductors; and   connecting pairs of the first plurality of metal fillings together using the first plurality of metal conductors to form a spiral.   
   
   
       21 . The method of  claim 20  further comprising the step of:
 forming an insulating layer within the first plurality of vias.   
   
   
       22 . The method of  claim 20  further comprising the steps of:
 forming a first plurality of trenches within the first substrate;   forming a first insulating layer within the first plurality of trenches; and   forming the first plurality of metal conductors on top of the first insulating layer within the first plurality of trenches.   
   
   
       23 . The method of  claim 22  further comprising the step of:
 increasing a winding density of the spiral by forming each of the first plurality of trenches with a depth to spacing aspect ratio equal to or greater than 2:1.   
   
   
       24 . The method of  claim 23  further comprising the step of forming the first plurality of trenches with deep reactive ion etching using a time sequenced etch and passivation process. 
   
   
       25 . The method of  claim 20  further comprising the step of
 plating metal into photoresist molds to form the first plurality of metal conductors.   
   
   
       26 . The method of  claim 20  wherein the first plurality of metal fillings are formed in a rectangular cross section shape to reduce resistance within the first plurality of metal fillings. 
   
   
       27 . The method of  claim 20  wherein the first plurality of metal fillings are formed in an oval cross section shape to reduce resistance within the first plurality of metal fillings. 
   
   
       28 . The method of  claim 20  further comprising the steps of:
 forming a second plurality of vias in a second substrate;   filling the second plurality of vias in the second substrate with a second plurality of metal fillings;   forming a second plurality of metal conductors;   connecting pairs of the second plurality of metal fillings together using the second plurality of metal conductors; and   connecting the first plurality of metal fillings to the second plurality of metal fillings to form the spiral.   
   
   
       29 . The method of  claim 28  further comprising the step of bonding the first plurality of metal fillings to the second plurality of metal fillings using gold thermocompression bonding. 
   
   
       30 . The method of  claim 28  further comprising the step of plating metal into photoresist molds to form the first plurality of metal conductors and the second plurality of metal conductors. 
   
   
       31 . The method of  claim 28  further comprising the steps of:
 forming a first plurality of trenches within the first substrate;   forming a first insulating layer within the first plurality of trenches;   forming the first plurality of metal conductors on top of the first insulating layer within the first plurality of trenches;   forming a second plurality of trenches within the second substrate;   forming a second insulating layer within the second plurality of trenches; and   forming the second plurality of metal conductors on top of the second insulating layer within the second plurality of trenches.   
   
   
       32 . The method of  claim 31  further comprising the step of
 increasing a winding density of the spiral by forming each of the first plurality of trenches and each of the second plurality of trenches with a depth to spacing aspect ratio equal to or greater than 2:1.   
   
   
       33 . The method of  claim 32  further comprising the step of forming the first plurality of trenches and the second plurality of trenches with deep reactive ion etching using a time sequenced etch and passivation process. 
   
   
       34 . The method of  claim 28  wherein the first plurality of metal fillings and the second plurality of metal fillings are formed in a rectangular cross section shape to reduce resistance within the first plurality of metal fillings and the second plurality of metal fillings. 
   
   
       35 . The method of  claim 28  wherein the first plurality of metal fillings and the second plurality of metal fillings are formed in an oval cross section shape to reduce resistance within the first plurality of metal fillings and the second plurality of metal fillings.