Low crosstalk substrate for mixed-signal integrated circuits
View Patent ↗An integrated circuit laminate with a metal substrate for use with high performance mixed signal integrated circuit applications. The metal substrate provides substantially improved crosstalk isolation, enhanced heat sinking and an easy access to a true low impedance ground. In one embodiment, the metal layer has regions with insulation filled channels or voids and a layer of insulator such as unoxidized porous silicon disposed between the metal substrate and a silicon integrated circuit layer. The laminate also has a plurality of metal walls or trenches mounted to the metal substrate and transacting the silicon and insulation layers thereby isolating noise sensitive elements from noise producing elements on the chip. In another embodiment, the laminate is mounted to a flexible base to limit the flexion of the chip.
1. An integrated circuit laminate, comprising:
a generally planar metal substrate;
a silicon integrated circuit layer coupled to said metal substrate; and
a plurality of conductive walls within said silicon integrated circuit layer;
wherein an active portion of said silicon integrated circuit layer is insulated from digital noise produced by a digital circuit portion of said silicon integrated circuit layer;
wherein the plurality of conductive walls are electrically connected to the metal substrate to insulate the digital noise produced by a digital circuit portion.
2. The integrated circuit laminate as recited in claim 1 , wherein said silicon integrated circuit layer is coupled to said metal substrate with an electrically conductive adhesive.
3. The integrated circuit laminate as recited in claim 1 , wherein said silicon integrated circuit layer has a thickness of approximately 4.5 μm or less.
4. The integrated circuit laminate as recited in claim 1 , wherein said metal substrate comprises a metal sheet with a thickness of between approximately 100 μm and approximately 5 mm.
5. The integrated circuit laminate as recited in claim 4 , wherein said metal substrate comprises a copper sheet.
6. The integrated circuit laminate as recited in claim 1 , further comprising an insulating layer disposed between said silicon integrated circuit layer and said metal substrate.
7. The integrated circuit laminate as recited in claim 6 , wherein said insulating layer comprises unoxidized porous silicon.
8. The integrated circuit laminate as recited in claim 6 , wherein said insulating layer comprises an insulator with a thickness of between approximately 4 μm and approximately 100 pm.
9. The integrated circuit laminate as recited in claim 1 , wherein said plurality of conductive walls comprises metal walls with a thickness of between approximately 2.5 pm and approximately 4.5 pm and a width of between approximately 1 μm and approximately 1000 pm.
10. The integrated circuit laminate as recited in claim 1 , wherein said active portion of said silicon integrated circuit layer comprises an analog circuit.
11. The integrated circuit laminate as recited in claim 1 , wherein said active portion of said silicon integrated circuit layer comprises a radio frequency circuit.
12. An electrical circuit assembly, comprising:
a generally planar metal substrate;
a silicon integrated circuit layer coupled to said metal substrate;
wherein said silicon integrated circuit layer comprises a mixed signal circuit having an analog circuit portion and a digital circuit portion; and
a plurality of conductive walls coupled to said metal substrate and transecting said silicon integrated circuit layer, wherein the analog circuit portion of said mixed signal circuit is insulated from digital noise produced by the digital circuit portion.
13. The electrical circuit assembly as recited in claim 12 , wherein said silicon integrated circuit layer is coupled to said metal substrate with an electrically conductive adhesive.
14. The electrical circuit assembly as recited in claim 12 , wherein said silicon integrated circuit layer has a thickness of approximately 4.5 μm or less.
15. The electrical circuit assembly as recited in claim 12 , wherein said metal substrate comprises a metal sheet with a thickness of between approximately 100 μm and approximately 5 mm.
16. The electrical circuit assembly as recited in claim 12 , wherein said metal substrate comprises a copper sheet.
17. The electrical circuit assembly as recited in claim 12 , further comprising an insulating layer disposed between said silicon integrated circuit layer and said metal substrate.
18. The electrical circuit assembly as recited in claim 12 , wherein said analog circuit portion of said mixed signal circuit comprises a radio frequency circuit.
19. An electrical circuit assembly method, comprising:
providing a generally planar metal substrate;
mounting a silicon integrated circuit layer to said metal substrate;
wherein said silicon integrated circuit layer comprises a mixed signal circuit having an analog circuit portion and a digital circuit portion; and
coupling a plurality of conductive walls to said metal substrate, wherein said conductive walls transect said silicon integrated circuit layer, and wherein the analog circuit portion of said mixed signal circuit is insulated from digital noise produced by the digital circuit portion.
20. The electrical circuit assembly method as recited in claim 19 , wherein said metal substrate comprises a copper sheet.
21. The electrical circuit assembly method as recited in claim 19 , further comprising disposing an insulating layer between said silicon integrated circuit layer and said metal substrate.
22. The electrical circuit assembly method as recited in claim 19 , wherein said plurality of conductive walls comprises a metal.
23. An integrated circuit laminate as recited in claim 1 , wherein the plurality of conductive walls are electrically connected to the metal substrate to insulate the digital noise produced by the digital circuit portion.
24. An electrical circuit assembly as recited in claim 12 , wherein the plurality of conductive walls are electrically coupled to said metal substrate to insulate the digital noise produced by the digital circuit portion.
25. An electrical circuit assembly method as recited in claim 19 , wherein the plurality of conductive walls are electrically coupled to said metal substrate to insulate the digital noise produced by the digital circuit portion.