Chip with internal signal routing in external element

• US 6,365,975 B1
• Filed: 04/02/1998
• Issued: 04/02/2002
• Est. Priority Date: 04/02/1997
• Status: Expired due to Term

• Current Assignee: Tessera, Inc. (Adeia Inc.)
• Original Assignee: Tessera, Inc. (Adeia Inc.)
• Inventors: Smith, John W., DiStefano, Thomas H.
• Primary Examiner(s): Williams, Alexander O.
• Application Number:
  US09/053,816
• Time in Patent Office: 1,461 Days
• Field of Search: 257/666, 257/678, 257/696, 257/698, 257/690, 257/669.M, 257/778, 257/738, 257/737, 257/777, 257/723, 257/728, 257/686, 257/685, 257/665, 257/48, 361/769, 361/735, 361/767, 361/729, 361/790, 361/765, 361/768, 361/792, 324/755, 324/765
• US Class Current: 257/777
• CPC Class Codes: H01L 2223/6627 Waveguides, e.g. microstrip line, strip line, coplanar line
• CPC Class Codes: H01L 2224/16 of an individual bump connector
• CPC Class Codes: H01L 23/498 Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers shape of the substrate H01L23/13
• CPC Class Codes: H01L 23/52 Arrangements for conducting electric current within the device in operation from one component to another , i.e. interconnections, e.g. wires, lead frames optical interconnections G02B6/00
• CPC Class Codes: H01L 23/538 the interconnection structure between a plurality of semiconductor chips being formed on, or in, insulating substrates H05K takes precedence; manufacture or treatment H01L21/4846 ; mountings per se H01L23/12; materials H01L23/49866
• CPC Class Codes: H01L 2924/1903 including wave guides
• CPC Class Codes: H01L 2924/3011 Impedance
• CPC Class Codes: H05K 1/118 specially for flexible printed circuits, e.g. using folded portions

Abstract

A semiconductor chip is provided with a dielectric element having conductive features interconnecting electronic elements within the chip with one another. The conductive features replace internal conductors, and can provide enhanced signal propagation between elements of the chip. The conductive features on the dielectric element are connected to contacts on the chip by deformable conductive elements such as flexible leads so that the dielectric element remains movable with respect to the chip. The dielectric element may have a coefficient of expansion different from that of the chip itself.

Claims

1. A microelectronic assembly including:

(a) a first semiconductor chip including a plurality of electronic elements and a front surface having contacts thereon, at least some of said electronic elements being connected to said contacts;

(b) a dielectric element separate from said chip and movable with respect to said chip, said dielectric element having a plurality of conductive interconnect traces thereon; and

(c) deformable conductive elements interconnecting said at least some of said contacts with said interconnect traces so that at least some of said electronic elements are connected to one another for transmission of signals therebetween through said traces.

2. An assembly as claimed in claim 1 wherein said dielectric element and said first semiconductor chip have different coefficients of thermal expansion.

3. An assembly as claimed in claim 2 wherein said chip is formed predominantly from silicon and said dielectric element has a coefficient of thermal expansion greater than 10×

10⁶ cm/cm/°

C.

4. An assembly as claimed in claim 2 wherein said dielectric element includes a polymeric body having said traces thereon and wherein said traces are metallic.

5. An assembly as claimed in claim 1 wherein said deformable conductive elements include flexible leads.

6. An assembly as claimed in claim 1 wherein said deformable conductive elements include masses of a fusible electrically conductive material having a melting temperature below about 150°

C.

7. An assembly as claimed in claim 6 wherein said chip is adapted to operate in a range of operating temperatures up to a maximum operating temperature and said melting temperature is at or below said maximum operating temperature.

8. An assembly as claimed in claim 6 further comprising a compliant dielectric material surrounding said masses and confining said fusible material when said fusible material is in a molten state.

9. An assembly as claimed in claim 1 further comprising a compliant dielectric layer disposed between said dielectric element and said chip.

10. An assembly as claimed in claim 9, wherein said dielectric element overlies said front surface of said first semiconductor chip, said compliant layer being disposed between said front surface of said chip and said dielectric element.

11. An assembly as claimed in claim 1 or claim 10 wherein said dielectric element has a bottom surface facing toward said first chip, a top surface facing away from said first chip, and a plurality of terminals accessible at said top surface, said terminals being connected to said chip by said deformable conductive elements.

12. An assembly as claimed in claim 11 further comprising a substrate having electrically conductive elements therein, said terminals on said dielectric element being electrically connected to the conductive elements of said substrate.

13. An assembly as claimed claim 1 further comprising a second semiconductor chip having electronic elements therein juxtaposed with said dielectric element, the electronic elements of said second chip being connected to at least some of said traces.

14. An assembly as claimed in claim 13 wherein some of said traces and said interconnect electronic elements of said first and second chips with one another.

15. An assembly as claimed in claim 1 or claim 10 further comprising an auxiliary circuit element juxtaposed with said dielectric element and connected to at least some of said traces, at least some of said traces connecting electronic elements of said first chip to said auxiliary circuit element.

16. An assembly as claimed in or claim 1 or claim 10 wherein said traces have resistivity less than 2.5 microohms-cm.

17. An assembly as claimed in claim 16 wherein said traces include one or more metals selected from the group consisting of gold, silver, copper and alloys thereof.

18. An assembly as claimed in claim 17 wherein said traces include copper.

19. An assembly as claimed in claim 16 wherein said traces are at least about 10 μ

m wide and at least about 5 μ

m thick.

20. An assembly as claimed in claim 16 wherein said dielectric element includes a dielectric material having dielectric constant of less than about 4.

21. An assembly as claimed in claim 20 wherein said dielectric material consists essentially of polyimide.

22. A method of making a semiconductor device comprising the steps of:

(a) providing a unitary semiconductor structure having a front surface, said semiconductor structure incorporating a plurality of electronic elements within said structure and contacts on said front surface, said electronic elements having signal connections, at least some of said signal connections being connected to said contacts;

(b) assembling a dielectric structure having a electrically conductive features thereon to said semiconductor structure so as to connect the electrically conductive features with said contacts through deformable conductive elements so that at least some signal connections of said electronic elements within said unitary semiconductor structure are connected to one another through said contacts, said deformable conductive elements and said conductive features on said dielectric structure, and so that said dielectric structure remains movable with respect to said semiconductor structure.

23. A method as claimed in claim 22 wherein said unitary semiconductor structure includes a plurality of chips, said assembling step being performed so that electronic elements within each said chip are connected to one another through conductive features within a portion of the dielectric structure associated with that chip, the method further comprising the step of severing said unitary semiconductor structure to separate each said chip from the unitary semiconductor structure so that the portion of the dielectric structure associated with such chip remains with the chip.

24. A method as claimed in claim 23 wherein said dielectric structure is a unitary dielectric structure incorporating a plurality of said portions, said severing step being performed so as to sever said dielectric structure.

25. A method as claimed in claim 23 wherein said dielectric structure includes a plurality of separate components, said assembling step being performed so that one said component is assembled to each said chip.

26. A method as claimed in claim 22 wherein said deformable conductive elements include flexible leads, said assembling step including the step of deforming said flexible leads through a predetermined displacement.

27. A method as claimed in claim 22 further comprising the step of providing a compliant material between said dielectric element and said chip.