Process for producing ceramic circuit structures having conductive vias

• US 5,337,475 A
• Filed: 12/17/1992
• Issued: 08/16/1994
• Est. Priority Date: 03/20/1991
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Neisser, Mark O., Kim, Young-Ho, Shaw, Thomas M., Cooper, Emanuel I., Park, Jae M., Knickerbocker, Sarah H., Walker, George F., Rita, Robert A., Farooq, Shaji, Duncombe, Peter R., Kim, Jungihl, Shaw, Robert R., Giess, Edward A., Muller-Landau, Friedel, Vallabhaneni, Rao, Aoude, Farid Y., Van Hise, Jon A., Brownlow, deceased, James M.
• Primary Examiner(s): Arbes, Carl J.
• Application Number:
  US07/992,091
• Time in Patent Office: 607 Days
• Field of Search: 29/852, 29/842, 264/61, 428/901
• US Class Current: 29/852
• CPC Class Codes: H01B 1/16 the conductive material comprising metals or alloys
• CPC Class Codes: H01L 21/486 Via connections through the substrate with or without pins
• CPC Class Codes: H01L 21/4867 Applying pastes or inks, e.g. screen printing H01L21/486 takes precedence
• CPC Class Codes: H01L 23/49883 the conductive materials containing organic materials or pastes, e.g. for thick films for printed circuits H05K1/092
• 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 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H05K 1/0306 Inorganic insulating substrates, e.g. ceramic, glass
• CPC Class Codes: H05K 1/092 Dispersed materials, e.g. conductive pastes or inks
• CPC Class Codes: H05K 3/4611 by laminating two or more circuit boards H05K3/4652 takes precedence
• CPC Class Codes: H05K 3/4629 laminating inorganic sheets comprising printed circuits, e.g. green ceramic sheets
• CPC Class Codes: Y10S 428/901 Printed circuit
• CPC Class Codes: Y10T 29/49147 Assembling terminal to base
• CPC Class Codes: Y10T 29/49165 by forming conductive walled aperture in base
• CPC Class Codes: Y10T 428/12472 Microscopic interfacial wave or roughness
• CPC Class Codes: Y10T 428/12556 Organic component
• CPC Class Codes: Y10T 428/12604 Film [e.g., glaze, etc.]
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/24322 Composite web or sheet
• CPC Class Codes: Y10T 428/24802 Discontinuous or differential coating, impregnation or bond [e.g., artwork, printing, retouched photograph, etc.]
• CPC Class Codes: Y10T 428/25 : Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/251 : Mica
• CPC Class Codes: Y10T 428/252 : Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
• CPC Class Codes: Y10T 428/2982 : Particulate matter [e.g., sphere, flake, etc.]
• CPC Class Codes: Y10T 428/2991 : Coated

Abstract

Improved vie-filling compositions for producing conductive vias in circuitized ceramic substrates, particularly multi-layer substrates, without cracking and/or loss of hermetic sealing. The via-filling compositions comprise pastes containing a mixture of (a) ceramic and/or glass spheres of substantially- uniform diameter between about 0.5 and 6 μm, (b) conductive metal particles or spheres having a maximum dimension or diameter between about 1/3 and 1/4 of the diameter of the ceramic and/or glass spheres, and (c) a binder vehicle. The formed conductive via bodies comprise a uniform conductive skeletal network of sintered metal particles densely packed within a uniform matrix of the co-sintered ceramic and/or glass spheres, which matrix is hermetically fused and integrated with ceramic layers forming the wall of the via in the ceramic circuit substrate.

Claims

1. A process for producing a ceramic circuit structure comprising the steps of:

(a) forming at least one self-supporting layer of dielectric glass-ceramic composition having a low sintering temperature, below 1000°

C.;

(b) forming at least one via in at least one of said layers;

(c) filing said via with a via-fill composition comprising a mixture of a major amount by volume of contacting spheres of a glass-ceramic material similar in composition to the glass-ceramic composition of said self-supporting layer, said spheres having a substantially uniform average diameter which is less than about 10% of the diameter of said via, said spheres having a diameter which is between about 0.5 μ

m and 6 μ

m, and a minor amount by volume of particles of a low-resistive metal which have a maximum size less than about 1/3 the diameter of said glass-ceramic spheres and which fill the spaces between said contacting spheres and which have a melting temperature above the sintering temperature of said glass-ceramic composition; and

(d) heating the structure resulting after step (c) to a temperature above the glass transition temperature of the glass-ceramic composition of said at least one layer and of said spheres but below about 1000°

C., to cosinter said glass-ceramic spheres, said metal particles and said at least one glass-ceramic layer to form a ceramic circuit structure in which each via is filled with a conductive via body comprising a major amount by volume of said glass-ceramic composition which is integrated with and hermetically sealed to said at least one glass-ceramic layer and comprises a continuous skeletal network of said sintered metal particles contained with a glass-ceramic matrix formed from said glass-ceramic spheres, each said via body providing a conductive path.

2. A process according to claim 1 in which the glass-ceramic composition of said at least one dielectric layer and that of said glass-ceramic spheres both comprise a cordierite-type glass having a similar thermal coefficient of expansion.

3. A process according to claim 1 in which said via-fill composition is applied as a paste comprising a minor amount of an organic binder material, and the structure resulting after step (c) is initially heated in step (d) to a burn-off temperature below the glass transition temperature to burn-off said organic binder material prior to heating to the cosintering temperature.

4. A process according to claim 1 in which said metal particles comprise spheres of said metal.

5. A process according to claim 1 in which said metal comprises copper.

6. A process according to claim 1 in which said metal comprises an alloy of copper and up to 2% by weight berrylium, having a TCE similar to the TCE of said ceramic material.

7. A process according to claim 1 in which said metal comprises a mixture of copper and an iron-cobalt alloy having a TCE similar to the TCE of said ceramic material.

8. A process according to claim 8 in which said iron-cobalt alloy is selected from the group consisting of Fe-31Ni-(4-6)Co, (36-37)Fe-(53-55)Co-(9-10)Cr, and 37Fe-30Ni-25Co-8Cr.

9. A process for producing a multilayer ceramic circuit structure comprising the steps of:

(a) forming at least two self-supporting layers of dielectric glass-ceramic composition having a low sintering temperature, below 1000°

C.;

(b) forming at least one vertical via hole through at least one of said layers;

(c) filing said via hole(s) with a via-fill composition comprising a mixture of a major amount by volume of contacting spheres of glass-ceramic material having a substantially uniform average diameter which is less than about 10% of the diameter of said via hole(s), said spheres having a diameter which is between about 0.5 μ

m and 6 μ

m, and a minor amount by volume of particles of a low-resistive metal which have a maximum size less than about 1/3 the diameter of said glass-ceramic spheres and which fill the spaces between said contacting spheres and which have a melting temperature above the sintering temperature of said glass-ceramic composition;

(d) applying a thin electrically-conductive body to the surface of said layer(s) containing said via hole(s) to provide communication between said conductive body and said via-fill composition;

(e) forming a laminate of said layers having said conductive body confined therebetween; and

(f) heating said laminated to a temperature above the glass transition temperature of the glass-ceramic composition of said layers and of said spheres but below about 1000°

C., and below the melting point of said metal particles, to cosinter said glass-ceramic layers to form a multilayer ceramic circuit structure in which each via is filled with a conductive via body which is integrated with and hermetically sealed to said glass-ceramic layers and comprises a continuous skeletal network of said metal contained within a major amount by volume of glass-ceramic matrix formed from said glass-ceramic spheres, each said via body providing a conductive path between a surface of said structure and at least one said conductive body insulated between said layers.

10. A process according to claim 9 in which the glass-ceramic composition of said dielectric layers and that of said glass-ceramic spheres both comprise a cordierite-type glass having a similar thermal coefficient of expansion.

11. A process according to claim 9 in which said via-fill composition is applied as a paste comprising a minor amount of an organic binder material, and the laminate is initially heated in step (f) to a burn-off temperature below tile glass transition temperature to burn-off said organic binder material prior to heating to the cosintering temperature.

12. A process according to claim 9 in which said metal particles comprise spheres of said metal.

13. A process according to claim 9 in which said metal comprises copper.

14. A process according to claim 9 in which said metal comprises an alloy of copper and up to 2% by weight beryllium, having a TCE similar to tile TCE of said ceramic material.

15. A process according to claim 9 in which said metal comprises a mixture of copper and all iron-cobalt alloy having a TCE similar to the TCE of said ceramic material.

16. A process according to claim 15 in which said iron-cobalt alloy is selected from the group consisting of Fe-31Ni-(4-5)Co, (36-37)Fe-(53-55)Co-(9-10)Cr, and Fe-30Ni-25Co-8Cr.