Methods and apparatus having an integrated circuit attached to fused silica

• US 20070267708A1
• Filed: 05/15/2007
• Published: 11/22/2007
• Est. Priority Date: 05/22/2006
• Status: Active Grant

• Current Assignee: St. Jude Medical Luxembourg Holdings Ii S.A.R.L.
• Original Assignee: CardioMEMS Incorporated
• Inventors: Courcimault, Christophe
• Granted Patent: US 7,812,416 B2
• Time in Patent Office: Days
• US Class Current: 257/414
• CPC Class Codes: B81B 2207/096 through the substrate
• CPC Class Codes: B81C 1/00301 Connecting electric signal lines from the MEMS device with external electrical signal lines, e.g. through vias
• CPC Class Codes: H01L 2224/04026 Bonding areas specifically adapted for layer connectors
• CPC Class Codes: H01L 2224/2612 Auxiliary members for layer connectors, e.g. spacers
• CPC Class Codes: H01L 2224/29101 the principal constituent melting at a temperature of less than 400°C
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/29144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/32225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 2224/32506 comprising an eutectic alloy
• CPC Class Codes: H01L 2224/45015 being circular
• CPC Class Codes: H01L 2224/45099 Material
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48227 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 2224/83101 as prepeg comprising a layer connector, e.g. provided in an insulating plate member
• CPC Class Codes: H01L 2224/838 Bonding techniques
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/48 of an individual wire connector
• CPC Class Codes: H01L 24/83 using a layer connector
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/00012 : Relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• CPC Class Codes: H01L 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/01006 : Carbon [C]
• CPC Class Codes: H01L 2924/01019 : Potassium [K]
• CPC Class Codes: H01L 2924/01024 : Chromium [Cr]
• CPC Class Codes: H01L 2924/01033 : Arsenic [As]
• CPC Class Codes: H01L 2924/01041 : Niobium [Nb]
• CPC Class Codes: H01L 2924/01042 : Molybdenum [Mo]
• CPC Class Codes: H01L 2924/01047 : Silver [Ag]
• CPC Class Codes: H01L 2924/0105 : Tin [Sn]
• CPC Class Codes: H01L 2924/01072 : Hafnium [Hf]
• CPC Class Codes: H01L 2924/01073 : Tantalum [Ta]
• CPC Class Codes: H01L 2924/01074 : Tungsten [W]
• CPC Class Codes: H01L 2924/01077 : Iridium [Ir]
• CPC Class Codes: H01L 2924/01078 : Platinum [Pt]
• CPC Class Codes: H01L 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01082 : Lead [Pb]
• CPC Class Codes: H01L 2924/0132 : Binary Alloys
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/01327 : Intermediate phases, i.e. intermetallics compounds
• CPC Class Codes: H01L 2924/0133 : Ternary Alloys
• CPC Class Codes: H01L 2924/014 : Solder alloys
• CPC Class Codes: H01L 2924/09701 : Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/10253 : Silicon [Si]
• CPC Class Codes: H01L 2924/14 : Integrated circuits
• CPC Class Codes: H01L 2924/1433 : Application-specific integrated circuit [ASIC]
• CPC Class Codes: H01L 2924/15153 : the die mounting substrate comprising a recess for hosting the device
• CPC Class Codes: H01L 2924/15165 : Monolayer substrate
• CPC Class Codes: H01L 2924/15787 : Ceramics, e.g. crystalline carbides, nitrides or oxides
• CPC Class Codes: H01L 2924/15788 : Glasses, e.g. amorphous oxides, nitrides or fluorides
• CPC Class Codes: H01L 2924/16788 : Glasses, e.g. amorphous oxides, nitrides or fluorides
• CPC Class Codes: H01L 2924/19041 : being a capacitor
• CPC Class Codes: H01L 2924/19043 : being a resistor
• CPC Class Codes: H01L 2924/207 : Diameter ranges
• CPC Class Codes: H01L 2924/30105 : Capacitance

Abstract

Disclosed are methods for attaching an integrated circuit to a substrate, and in particular, a fused silica substrate, along with apparatus fabricated using the methods. Exemplary apparatus comprises a glass substrate, a metallic layer disposed on the substrate, and an integrated circuit eutectically bonded to the glass substrate via the metallic layer. The integrated circuit and fused silica substrate form part of a hermetic sensor. In an exemplary sensor, a first trench is formed in a first substrate. A second trench that is deeper than the first trench is formed in the first substrate. A first plurality of electrodes are formed in the first trench. An integrated circuit is attached to the first substrate within the second trench using a solder preform. The integrated circuit may be attached to the first substrate by depositing a Cr/Au film onto either the integrated circuit or first substrate, depositing a Cr/Ni/Au film onto either the first substrate or integrated circuit, placing the an Au/Sn solder preform onto the Cr/Ni/Au film, positioning the integrated circuit on top of the soldered preform so that it contacts the Cr/Au film, and heating the assembly.

Claims

1. Apparatus comprising:

a glass substrate;

a metallic layer disposed on the substrate; and

an integrated circuit eutectically bonded to the glass substrate via the metallic layer.

2. The apparatus recited in claim 1 wherein the metallic layer comprises a solder preform.

3. The apparatus recited in claim 1 wherein the metallic layer comprises one or more layers of metal deposited on the substrate.

4. The apparatus recited in claim 1 wherein:

the glass substrate comprises one or more trenches;

and wherein the apparatus further comprises;

one or more first electrodes disposed on a surface of the one or more trenches;

wire bonds connected between the integrated circuit and the one or more first electrodes;

a second glass substrate comprising one or more second electrodes that cooperate with the one or more first electrodes to form a sensor;

one or more electrical feedthroughs disposed through the glass substrate that are coupled to selected ones of the one or more first electrodes;

wire bonds connected between the integrated circuit and the one or more electrical feedthroughs; and

wherein peripheries of the respective substrates are fused together to form a hermetic sensor.

5. A method comprising:

providing a glass substrate; and

eutectically bonding an integrated circuit to the glass substrate.

6. The method recited in claim 5 wherein the integrated circuit is bonded to the substrate using a solder preform.

7. The method recited in claim 6 which comprises:

deposing the solder preform on the substrate; and

heating the substrate, solder preform and integrated circuit to form a eutectic bond therebetween.

8. The method recited in claim 5 wherein the integrated circuit is bonded to the substrate by:

depositing one or more layers of metal on the substrate to form an alloy; and

heating the substrate, one or more layers of metal and integrated circuit to form a eutectic bond therebetween.

9. The method recited in claim 5 wherein the glass substrate comprises a fused silica substrate.

10. The method recited in claim 5 further comprising:

forming one or more trenches in the glass substrate;

forming one or more first electrodes on the one or more trenches;

connecting wire bonds between the integrated circuit and the one or more first electrodes;

forming one or more second electrodes on a second glass substrate that cooperate with the one or more first electrodes to form a sensor;

forming electrical feedthroughs through the glass substrate

connecting wire bonds between the integrated circuit and the electrical feedthroughs; and

fusing peripheries of the substrates together to form a hermetic sensor.

11. The method recited in claim 5 wherein eutectically bonding the integrated circuit to the glass substrate comprises:

depositing a plurality of metal layers on the integrated circuit that comprise an adhesion layer and a non-oxidizing layer;

depositing a plurality of metal layers on the glass substrate that comprise an adhesion layer, a wetting layer and a non-oxidizing layer;

disposing a solder alloy preform between the deposited pluralities of layers; and

heating the substrate, deposited layers, solder preform and integrated circuit.

12. The method recited in claim 11 wherein heating is between about 100 and 400 degrees C. and held at that temperature for a predetermined time period to affix the integrated circuit to the substrate.

13. The method recited in claim 12 wherein the predetermined time period is about 5 minutes.

14. The method recited in claim 5 wherein:

the plurality of metal layers on the integrated circuit comprise a chromium or titanium layer and a gold layer; and

the plurality of metal layers on the glass substrate comprise a chromium or titanium layer, a nickel layer, and a gold layer.

15. The method recited in claim 5 wherein eutectically bonding the integrated circuit to the glass substrate comprises:

depositing a plurality of metal layers on the integrated circuit that comprise an adhesion layer, a wetting layer and a non-oxidizing layer;

depositing a plurality of metal layers on the glass substrate that comprise an adhesion layer and a non-oxidizing layer;

disposing a solder alloy preform between the deposited layers; and

heating the substrate, deposited layers, solder preform and integrated circuit.

16. The method recited in claim 15 wherein heating is between about 100 and 400 degrees C. and held at that temperature for a predetermined time period to affix the integrated circuit to the substrate.

17. The method recited in claim 16 wherein:

the plurality of metal layers on the glass substrate comprise a chromium or titanium layer and a gold layer; and

the plurality of metal layers on the integrated circuit comprise a chromium or titanium layer, a nickel layer, and a gold layer.

18. The method recited in claim 15 wherein the predetermined time period is about 5 minutes.