Method of forming a glass interposer with thermal vias
The present invention relates generally to integrated circuit (IC) chip packaging, and more particularly, to a structure and method of forming a glass interposer having thermally conductive vias in addition to electrically conductive vias. The thermally conductive vias help dissipate heat from one or more IC chips, through the glass interposer, into an organic carrying, and then, into an underlying substrate where it can be dissipated.
1. A method comprising:
forming vias in a glass interposer;
filling the vias with a thermally conductive material, wherein the thermally conductive material is electrically insulating;
removing the thermally conductive material from a portion of the vias; and
depositing an electrically conductive material in the portion of the vias, on the thermally conductive material, and on the glass interposer.
2. The method of claim 1 , wherein the forming vias in the glass interposer comprises:
etching an entire thickness of the glass interposer.
3. The method of claim 1 , wherein the forming vias in the glass interposer comprises:
etching the glass interposer to form an opening that extends only through an upper portion of the glass interposer, such that the vias have a bottom that is separated from a bottom surface of the glass interposer by a lower portion of the glass interposer.
4. The method of claim 3 , further comprising:
removing the lower portion of the glass interposer to expose the bottom of the vias;
forming a bottom seed layer on an exposed portion of the glass interposer and the exposed bottom vias;
forming a bottom conductive material on the bottom seed layer;
forming an opening in the bottom conductive material and the bottom seed layer;
forming an insulator in the opening and on the bottom conductive material; and
forming a solder connection on the bottom conductive material.
5. The method of claim 1 , wherein the depositing the electrically conductive material in the portion of the vias, on the thermally conductive material, and on the glass interposer comprises:
forming a seed layer on exposed surfaces of the glass interposer and the thermally conductive material; and
forming a layer of conductive metal on the seed layer.
6. The method of claim 5 , wherein the layer of conductive metal comprises copper, aluminum, titanium, platinum, or alloys thereof.
7. The method of claim 1 , wherein the filling the vias with the thermally conductive material comprises:
depositing the thermally conductive material in the vias and on the glass interposer, wherein the thermally conductive material comprises polysilicon, aluminum nitride, or diamond-like carbon; and
performing a planarization process, such that the thermally conductive material is contained within the vias.
8. The method of claim 1 , wherein the removing the thermally conductive material from the portion of the vias comprises:
depositing an etch stop layer on the interposer and the thermally conductive material;
removing portions of the etch stop layer to expose the portion of the vias; and
removing the thermally conductive material from the portion of the vias, selective to the interposer.
9. The method of claim 1 , further comprising:
removing portions of the electrically conductive material to expose the glass interposer;
forming an insulator on the exposed glass interposer.
10. The method of claim 1 , further comprising:
forming a solder connection on the electrically conductive material.