US20010055703A1 - Method for the controlling of certain second phases in aluminum nitride - Google Patents
Method for the controlling of certain second phases in aluminum nitride Download PDFInfo
- Publication number
- US20010055703A1 US20010055703A1 US09/311,812 US31181299A US2001055703A1 US 20010055703 A1 US20010055703 A1 US 20010055703A1 US 31181299 A US31181299 A US 31181299A US 2001055703 A1 US2001055703 A1 US 2001055703A1
- Authority
- US
- United States
- Prior art keywords
- paste
- layer
- aluminum nitride
- greensheet
- substrate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 title claims abstract description 38
- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000005245 sintering Methods 0.000 claims abstract description 20
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 7
- 150000001875 compounds Chemical class 0.000 claims description 23
- 239000000843 powder Substances 0.000 claims description 19
- 239000011230 binding agent Substances 0.000 claims description 16
- HOOWDPSAHIOHCC-UHFFFAOYSA-N dialuminum tricalcium oxygen(2-) Chemical compound [O--].[O--].[O--].[O--].[O--].[O--].[Al+3].[Al+3].[Ca++].[Ca++].[Ca++] HOOWDPSAHIOHCC-UHFFFAOYSA-N 0.000 claims description 15
- 239000000758 substrate Substances 0.000 claims description 15
- 239000002245 particle Substances 0.000 claims description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 11
- 239000003870 refractory metal Substances 0.000 claims description 11
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 4
- -1 yttrium aluminate compound Chemical class 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 3
- 239000000292 calcium oxide Substances 0.000 claims description 3
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 2
- XFWJKVMFIVXPKK-UHFFFAOYSA-N calcium;oxido(oxo)alumane Chemical compound [Ca+2].[O-][Al]=O.[O-][Al]=O XFWJKVMFIVXPKK-UHFFFAOYSA-N 0.000 claims 1
- 239000000919 ceramic Substances 0.000 abstract description 40
- 238000001465 metallisation Methods 0.000 abstract description 15
- 229910052751 metal Inorganic materials 0.000 abstract description 14
- 239000002184 metal Substances 0.000 abstract description 14
- 230000007547 defect Effects 0.000 abstract description 12
- 238000007792 addition Methods 0.000 abstract description 5
- 239000007788 liquid Substances 0.000 abstract description 3
- 238000013459 approach Methods 0.000 abstract description 2
- 238000000354 decomposition reaction Methods 0.000 abstract 1
- 238000002474 experimental method Methods 0.000 abstract 1
- 239000000654 additive Substances 0.000 description 14
- 239000012071 phase Substances 0.000 description 11
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 9
- 229910052721 tungsten Inorganic materials 0.000 description 9
- 239000010937 tungsten Substances 0.000 description 9
- 239000011575 calcium Substances 0.000 description 6
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 4
- 230000000996 additive effect Effects 0.000 description 4
- 229910052791 calcium Inorganic materials 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- PIGFYZPCRLYGLF-UHFFFAOYSA-N Aluminum nitride Chemical compound [Al]#N PIGFYZPCRLYGLF-UHFFFAOYSA-N 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000000280 densification Methods 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000003475 lamination Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- 229910014779 CaAl4 Inorganic materials 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 229910001650 dmitryivanovite Inorganic materials 0.000 description 1
- 238000004100 electronic packaging Methods 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 238000007731 hot pressing Methods 0.000 description 1
- 229910001707 krotite Inorganic materials 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000009974 thixotropic effect Effects 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
- C04B41/51—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal
- C04B41/5133—Metallising, e.g. infiltration of sintered ceramic preforms with molten metal with a composition mainly composed of one or more of the refractory metals
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
- C04B41/88—Metals
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L23/00—Details of semiconductor or other solid state devices
- H01L23/12—Mountings, e.g. non-detachable insulating substrates
- H01L23/14—Mountings, e.g. non-detachable insulating substrates characterised by the material or its electrical properties
- H01L23/15—Ceramic or glass substrates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
- C04B2111/00844—Uses not provided for elsewhere in C04B2111/00 for electronic applications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/0001—Technical content checked by a classifier
- H01L2924/0002—Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/03—Use of materials for the substrate
- H05K1/0306—Inorganic insulating substrates, e.g. ceramic, glass
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K1/00—Printed circuits
- H05K1/02—Details
- H05K1/09—Use of materials for the conductive, e.g. metallic pattern
- H05K1/092—Dispersed materials, e.g. conductive pastes or inks
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T428/00—Stock material or miscellaneous articles
- Y10T428/26—Web or sheet containing structurally defined element or component, the element or component having a specified physical dimension
- Y10T428/263—Coating layer not in excess of 5 mils thick or equivalent
- Y10T428/264—Up to 3 mils
- Y10T428/265—1 mil or less
Definitions
- the present invention relates to densified ceramics bodies for electronic components and, in particular, to a densified ceramic body which is relatively free of surface defects.
- AlN Aluminum nitride
- AlN is of great interest as a material for electronic packages because of its high thermal conductivity and close match in thermal expansion to silicon.
- AlN can be densified at relatively low temperatures (1500-1700° C.) by additions of various low-melting-temperature compounds. Because of its high equilibrium vapor pressure, densification of the AlN ceramic can only be accomplished by hot pressing or liquid phase sintering.
- Electronic packages using AlN as a dielectric are typically processed from ceramic tape or greensheets.
- Greensheets consist of aluminum nitride powder, sintering aids, and an organic binder.
- the electrical conductor in the package is formulated into a paste made of refractory metal powder, ceramic additives, and organic binder. These two components are used in the process illustrated in FIGS. 1 A- 1 D.
- the paste 12 , 14 is screened essentially in a blanket pattern on the top sheet 16 of the greensheet stack 10 , as illustrated in FIG. 1A, where up to 80% of the surface of the greensheet may be covered by the paste. Often, two different pastes are deposited, one on top of the other.
- One paste may be added to provide adhesion to the ceramic and another to offer a surface which has sufficient exposed metal to allow plating.
- Greensheets are provided with through holes called vias which are also filled with conductive paste.
- the sheets 16 are then laminated by applying sufficient heat and pressure and the result is illustrated in FIG. 1B.
- the laminated stack 18 is then heated to remove the organic binder from the paste 12 , 14 and from the greensheet 16 . Further heating sinters the powders of both the paste and the greensheet.
- the resulting stack is illustrated in FIG. 1C.
- the sintering aids form a liquid which further aids densification of the ceramic body 20 .
- any component of the liquid sintering aids has a high vapor pressure, the liquid phase will tend to wick to the surface(s) of the part. The surface of the part may then tend to have an accumulation of sintering aid byproducts.
- the byproducts may be in the form of particles 22 which protrude above the surface as illustrated in FIG. 1D.
- the protruding particles 22 are especially undesirable on the surface of an electronic chip carrier because the particles present a debris hazard in clean room operations and may also damage a chip during the chip attach process. The chip damage problem is especially exaggerated when the metal covers a high area percent of the ceramic.
- MLC multilayer ceramic
- the ink typically contains a solvent, a metal powder, a binder, and ceramic additives.
- the particle size of the metal powder and the volume fraction of the ceramic additives are chosen in order to assure a shrinkage match between the metallization and the ceramic.
- the ceramic additives are typically similar to that of the powder mixture in the greensheet. In cases where there is a surface metal feature to which IO devices (wire bonds, pins, tape automated bonding (TAB), etc.) will be attached, mechanical adhesion between the metal and the ceramic is required.
- IO devices wire bonds, pins, tape automated bonding (TAB), etc.
- the sintering aid may have a tendency to move toward the surface during the sinter cycle. Since a highly loaded system will have few areas which are not covered by metallization, the liquid phase may accumulate in these areas. Furthermore, the liquid phase is likely to decompose into phases which are of a high hardness. This decomposed phase may cause an electronic package to violate specifications for surface defect height or to cause concerns about clean room contamination. In some extreme cases, the surface second phase may cause bulges in the metallization.
- a further object of the invention is to provide a method of producing a ceramic body which is substantially free of surface defects.
- the sintered aluminum nitride body comprising a substrate of aluminum nitride having a microstructure containing a compound of aluminum oxide and calcium oxide.
- the substrate has on at least a portion of a surface thereof a layer comprising a sintered mixture of a refractory metal, tricalcium aluminate, a yttrium aluminate compound in the substrate being precipitated uniformly throughout the microstructure of the substrate except in the portion of the substrate adjacent to the layer wherein the microstructure of the substrate is depleted of the compound.
- the present invention relates to a method of making the substrate with a depletion zone.
- the method for reducing formation of particles in surface and subsurface microstructures of aluminum nitride bodies comprises the steps of: a) providing a greensheet comprising aluminum nitride powder, a sintering aid and a binder; b) providing a paste comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate or other phases in the calcia-alumina system; c) applying the paste to at least a portion of a surface of the greensheet; and d) heating the greensheet and paste for a time and temperature sufficient to sinter the greensheet and paste.
- the present invention relates to a paste composition for application to a greensheet for aluminum nitride bodies containing compounds from the calcia-alumina system.
- the paste application reduces formation of particles in surface and subsurface microstructures thereof comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate or the phases of the calcia-alumina system.
- tricalcium aluminate is the additive, it is added in a range of from about 1 to about 35 percent by volume of the paste, with 22 percent by volume being preferred.
- FIG. 1A-D illustrates the prior art metallization process and the resulting ceramic with second phase particles in the surface of the ceramic.
- FIG. 2A is an illustration of a stack of greensheets screened with first and second layers of metal paste.
- FIG. 2B is an illustration of the screened stack of FIG. 1 after lamination.
- FIG. 2C is an illustration of the laminated stack of FIG. 2 after binder burnoff and sintering.
- FIG. 2D is a greatly enlarged illustration of the circled area of FIG. 2C illustrating a ceramic body with a depleted zone which is free of second phase particles.
- FIGS. 2 A-D of the drawings in which like numerals refer to like features of the invention.
- Features of the invention are not necessarily shown to scale in the drawings.
- the metal paste of the present invention comprises a refractory metal powder such as tungsten, a binder such as ethyl cellulose, and sintering aid compounds.
- Various sintering aids and compounds were added to metallization pastes, such as tungsten pastes, at various volume percents. Total ceramic additives may range from 5 to 65 volume percent of the non-organic portion of the paste, with 55 volume percent being preferred.
- additives included aluminum nitride (AlN), and ceramic sintering aid compounds such as aluminum oxide (Al 2 O 3 ), tricalcium aluminate or C3A (3CaO*Al 2 O 3 ), a calcium aluminoborate glass and compounds in the calcium alumina system including CaO, Ca 3 O, Ca3Al 2 O 6 , Ca 12 Al 14 O 33 , CaAl 2 O 4 , CaAl 4 O 7 , CaAl 12 O 19 , and Al 2 O 3
- the composition of calcium aluminoborate is disclosed in U.S. Pat. No. 5,482,903 which is hereby incorporated by reference. Where tricalcium aluminate is the additive, it is added in a range of from about 1 to about 35 percent by volume, with 22 percent by volume being preferred.
- the method for reducing formation of particles in surface and subsurface microstructures of aluminum nitride bodies is illustrated in FIG. 2A-D and comprises the steps of providing a greensheet comprising aluminum nitride powder, a sintering aid and a binder; providing a paste comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate and aluminum nitride powder; applying the paste to at least a portion of a surface of the greensheet; heating the greensheet and paste for a time and temperature sufficient to sinter the greensheet and paste.
- first and second layers 12 , 14 of metal paste are applied to green sheets 16 which are placed one on top of another in the stack 10 .
- a lamination process is performed and a laminated stack 18 is produced.
- the sintering step follows and produces the densified ceramic 20 of FIG. 2C.
- FIG. 2D illustrates a greatly enlarged encircled section of FIG. 2C with a metalized 24 layer and a depletion zone 26 .
- Metal paste may be applied in one or two layers in accordance with the present invention. Where the paste is applied in only one layer the paste may comprise aluminum nitride and tricalcium aluminate in a range from about 1 to 35 percent by volume.
- the second layer may have a greater concentration of tungsten.
- the first layer may comprise tricalcium aluminate in a range of from about 1 to about 35 percent by volume of the paste.
- the second layer may comprise aluminum nitride or a compound which does not react with the ceramic, or no additive at all (pure tungsten).
- the product produced by the above methods has been found to have a unique microstructure in AlN ceramic containing yttrium aluminates, whereby there is localized control of microstructure and phases which result in a zone of from 10 microns to 200 microns deep into the part underneath surface screened or I/O metallization.
- the depleted zone is substantially free of precipitated yttrium aluminates but may contain a wetted phase.
- pastes were blanket screened providing at least 80% coverage of the greensheet.
- the metalization was deposited in either one or two layers.
- the screened sheets were stacked and laminated at 6000 psi at 75° C. for 5 minutes and then the laminated parts were sintered at 1600° C. for 24 hours.
- the aluminum nitride ceramic contains sintering aids of approximately 2% by volume calcium aluminoborate (CAB) glass and approximately 1% by volume Y 2 O 3 Also, other tests yielded similar results when only one paste layer with similar components was screened. TABLE 1 Minimum Average Maximum First Layer zone zone zone Test Paste Second Layer width, width width, No.
- Additives* Paste Additives microns microns microns 1 55% AlN 100% tungsten 0 0 0 2 28% AlN, no second layer 24 32 41 7% C3A 3 21% AlN, no second layer 53 69 82 14% C3A 4 44% AlN, no second layer 59 61 65 11% C3A 5 33% AlN, no second layer 106 115 123 22% C3A 6 28% AlN, 100% tungsten 24 32 47 7% C3A 7 21% AlN, 100% tungsten 12 57 88 14% C3A 8 44% AlN, 100% tungsten 24 41 82 11% C3A 9 33% AlN, 100% tungsten 59 115 206 22% C3A
- the present invention has a unique fingerprint, a zone in the ceramic which is free of second phase particles.
- the zone starts at the metallization and extends down into the ceramic for some 5 to 100 microns in depth.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Ceramic Products (AREA)
Abstract
Description
- 1. Field of the Invention
- The present invention relates to densified ceramics bodies for electronic components and, in particular, to a densified ceramic body which is relatively free of surface defects.
- 2. Description of Related Art
- Aluminum nitride (AlN) is of great interest as a material for electronic packages because of its high thermal conductivity and close match in thermal expansion to silicon. AlN can be densified at relatively low temperatures (1500-1700° C.) by additions of various low-melting-temperature compounds. Because of its high equilibrium vapor pressure, densification of the AlN ceramic can only be accomplished by hot pressing or liquid phase sintering.
- Electronic packages using AlN as a dielectric are typically processed from ceramic tape or greensheets. Greensheets consist of aluminum nitride powder, sintering aids, and an organic binder. The electrical conductor in the package is formulated into a paste made of refractory metal powder, ceramic additives, and organic binder. These two components are used in the process illustrated in FIGS.1A-1D. The
paste top sheet 16 of thegreensheet stack 10, as illustrated in FIG. 1A, where up to 80% of the surface of the greensheet may be covered by the paste. Often, two different pastes are deposited, one on top of the other. One paste may be added to provide adhesion to the ceramic and another to offer a surface which has sufficient exposed metal to allow plating. Greensheets are provided with through holes called vias which are also filled with conductive paste. Thesheets 16 are then laminated by applying sufficient heat and pressure and the result is illustrated in FIG. 1B. The laminatedstack 18 is then heated to remove the organic binder from thepaste greensheet 16. Further heating sinters the powders of both the paste and the greensheet. The resulting stack is illustrated in FIG. 1C. In the sinter cycle, the sintering aids form a liquid which further aids densification of theceramic body 20. If any component of the liquid sintering aids has a high vapor pressure, the liquid phase will tend to wick to the surface(s) of the part. The surface of the part may then tend to have an accumulation of sintering aid byproducts. The byproducts may be in the form ofparticles 22 which protrude above the surface as illustrated in FIG. 1D. The protrudingparticles 22 are especially undesirable on the surface of an electronic chip carrier because the particles present a debris hazard in clean room operations and may also damage a chip during the chip attach process. The chip damage problem is especially exaggerated when the metal covers a high area percent of the ceramic. - Processing of electronic packages is greatly aided by use of a multilayer ceramic (MLC) technology, in which greensheets are cast using AlN and metallization is applied in the form of thixotropic ink or paste. The ink typically contains a solvent, a metal powder, a binder, and ceramic additives. The particle size of the metal powder and the volume fraction of the ceramic additives are chosen in order to assure a shrinkage match between the metallization and the ceramic. The ceramic additives are typically similar to that of the powder mixture in the greensheet. In cases where there is a surface metal feature to which IO devices (wire bonds, pins, tape automated bonding (TAB), etc.) will be attached, mechanical adhesion between the metal and the ceramic is required. Here, ceramic additives to the ink are also of great value, in that they may provide an interlocking feature between the ceramic and metal.
- In some electronic packaging applications, however, there is a need for coverage of much of the surface of the ceramic with metallization. It is possible for 70% or more of the ceramic surface to be taken up by metal features. The specifications for the surfaces of these packages have very stringent limits on the height of bumps or bulges in the ceramic, in order to prevent damage to die which are later attached to the packages. There is also a strong desire to limit the potential for the ceramic to be a source of particulate contamination in a clean room environment.
- In a package with high surface metal loading, however, a problem with the sintering aid may occur. The sintering aid may have a tendency to move toward the surface during the sinter cycle. Since a highly loaded system will have few areas which are not covered by metallization, the liquid phase may accumulate in these areas. Furthermore, the liquid phase is likely to decompose into phases which are of a high hardness. This decomposed phase may cause an electronic package to violate specifications for surface defect height or to cause concerns about clean room contamination. In some extreme cases, the surface second phase may cause bulges in the metallization.
- Accordingly, it is highly desirable to develop aluminum nitride bodies with minimal surface defects.
- Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a ceramic surface for an electronic component whereby the surface is substantially free of surface defects.
- It is another object of the present invention to provide an aluminum nitride body with minimal surface defects.
- A further object of the invention is to provide a method of producing a ceramic body which is substantially free of surface defects.
- It is yet another object of the present invention to provide a method of producing an aluminum nitride body with minimal surface defects.
- Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
- The above and other objects, which will be apparent to those skilled in the art, are achieved by the present invention which in a first aspect relates to a ceramic substrate with a depletion zone. The sintered aluminum nitride body comprising a substrate of aluminum nitride having a microstructure containing a compound of aluminum oxide and calcium oxide. The substrate has on at least a portion of a surface thereof a layer comprising a sintered mixture of a refractory metal, tricalcium aluminate, a yttrium aluminate compound in the substrate being precipitated uniformly throughout the microstructure of the substrate except in the portion of the substrate adjacent to the layer wherein the microstructure of the substrate is depleted of the compound.
- In another aspect, the present invention relates to a method of making the substrate with a depletion zone. The method for reducing formation of particles in surface and subsurface microstructures of aluminum nitride bodies comprises the steps of: a) providing a greensheet comprising aluminum nitride powder, a sintering aid and a binder; b) providing a paste comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate or other phases in the calcia-alumina system; c) applying the paste to at least a portion of a surface of the greensheet; and d) heating the greensheet and paste for a time and temperature sufficient to sinter the greensheet and paste.
- In another aspect, the present invention relates to a paste composition for application to a greensheet for aluminum nitride bodies containing compounds from the calcia-alumina system. The paste application reduces formation of particles in surface and subsurface microstructures thereof comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate or the phases of the calcia-alumina system.
- The preferred embodiments are as follows. Where tricalcium aluminate is the additive, it is added in a range of from about 1 to about 35 percent by volume of the paste, with 22 percent by volume being preferred.
- The features of the invention believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The invention itself, however, both as to organization and method of operation, may best be understood by reference to the detailed description which follows taken in conjunction with the accompanying drawings in which:
- FIG. 1A-D illustrates the prior art metallization process and the resulting ceramic with second phase particles in the surface of the ceramic.
- FIG. 2A is an illustration of a stack of greensheets screened with first and second layers of metal paste.
- FIG. 2B is an illustration of the screened stack of FIG. 1 after lamination.
- FIG. 2C is an illustration of the laminated stack of FIG. 2 after binder burnoff and sintering.
- FIG. 2D is a greatly enlarged illustration of the circled area of FIG. 2C illustrating a ceramic body with a depleted zone which is free of second phase particles.
- In describing the preferred embodiment of the present invention, reference will be made herein to FIGS.2A-D of the drawings in which like numerals refer to like features of the invention. Features of the invention are not necessarily shown to scale in the drawings.
- The metal paste of the present invention comprises a refractory metal powder such as tungsten, a binder such as ethyl cellulose, and sintering aid compounds.
- The addition of sintering aid compounds (to be described more fully below) to surface metallization paste has been found to be effective in overcoming the surface defect problems described above. These additives have been determined to help prevent the formation of surface defects by the creation of a depletion zone, near the surface of the ceramic, which is free of precipitated second phase particles. The additive compounds are of the calcia-alumina system.
- Various sintering aids and compounds were added to metallization pastes, such as tungsten pastes, at various volume percents. Total ceramic additives may range from 5 to 65 volume percent of the non-organic portion of the paste, with 55 volume percent being preferred. These additives included aluminum nitride (AlN), and ceramic sintering aid compounds such as aluminum oxide (Al2O3), tricalcium aluminate or C3A (3CaO*Al2O3), a calcium aluminoborate glass and compounds in the calcium alumina system including CaO, Ca3O, Ca3Al2O6, Ca12Al14O33, CaAl2O4, CaAl4O7, CaAl12O19, and Al2O3 The composition of calcium aluminoborate is disclosed in U.S. Pat. No. 5,482,903 which is hereby incorporated by reference. Where tricalcium aluminate is the additive, it is added in a range of from about 1 to about 35 percent by volume, with 22 percent by volume being preferred.
- The method for reducing formation of particles in surface and subsurface microstructures of aluminum nitride bodies is illustrated in FIG. 2A-D and comprises the steps of providing a greensheet comprising aluminum nitride powder, a sintering aid and a binder; providing a paste comprising a refractory metal powder, a binder and a compound selected from the group consisting of tricalcium aluminate and aluminum nitride powder; applying the paste to at least a portion of a surface of the greensheet; heating the greensheet and paste for a time and temperature sufficient to sinter the greensheet and paste.
- In the first step illustrated in FIG. 2A, first and
second layers green sheets 16 which are placed one on top of another in thestack 10. Next, as illustrated in FIG. 2B, a lamination process is performed and alaminated stack 18 is produced. The sintering step follows and produces the densifiedceramic 20 of FIG. 2C. FIG. 2D illustrates a greatly enlarged encircled section of FIG. 2C with a metalized 24 layer and adepletion zone 26. - Metal paste may be applied in one or two layers in accordance with the present invention. Where the paste is applied in only one layer the paste may comprise aluminum nitride and tricalcium aluminate in a range from about 1 to 35 percent by volume.
- Where a two layer method is used, the second layer may have a greater concentration of tungsten. The first layer may comprise tricalcium aluminate in a range of from about 1 to about 35 percent by volume of the paste. The second layer may comprise aluminum nitride or a compound which does not react with the ceramic, or no additive at all (pure tungsten).
- The product produced by the above methods has been found to have a unique microstructure in AlN ceramic containing yttrium aluminates, whereby there is localized control of microstructure and phases which result in a zone of from 10 microns to 200 microns deep into the part underneath surface screened or I/O metallization. The depleted zone is substantially free of precipitated yttrium aluminates but may contain a wetted phase.
- In tests, the results of which are described in Table 1, pastes were blanket screened providing at least 80% coverage of the greensheet. The metalization was deposited in either one or two layers. The screened sheets were stacked and laminated at 6000 psi at 75° C. for 5 minutes and then the laminated parts were sintered at 1600° C. for 24 hours.
- The parts were then examined in cross section for evidence of a depletion zone. Four pieces were mounted and a photograph at approximately 200× magnification was taken in a scanning electron microscope (SEM) under conditions which would highlight the yttrium aluminate particles. On each photo, the width of the depletion zone on each side was measured.
- It is important to note that the aluminum nitride ceramic contains sintering aids of approximately 2% by volume calcium aluminoborate (CAB) glass and approximately 1% by volume Y2O3 Also, other tests yielded similar results when only one paste layer with similar components was screened.
TABLE 1 Minimum Average Maximum First Layer zone zone zone Test Paste Second Layer width, width width, No. Additives* Paste Additives microns microns microns 1 55% AlN 100% tungsten 0 0 0 2 28% AlN, no second layer 24 32 41 7% C3A 3 21% AlN, no second layer 53 69 82 14% C3A 4 44% AlN, no second layer 59 61 65 11% C3A 5 33% AlN, no second layer 106 115 123 22% C3A 6 28% AlN, 100 % tungsten 24 32 47 7% C3A 7 21% AlN, 100 % tungsten 12 57 88 14% C3A 8 44% AlN, 100 % tungsten 24 41 82 11% C3A 9 33% AlN, 100% tungsten 59 115 206 22% C3A - The test results illustrate that it is possible to control the microstructure of the ceramic directly under the surface metalization by unique additions to the metallization paste layer. Additions of tricalcium aluminate or similar compounds of the calcia-alumina system are shown to greatly reduce the amount of sintering aid byproduct—on the surface after sintering. Typical manufacturing of ceramic packages with blanket metallization requires plateability and a high degree of adhesion to the ceramic. The approach of the present invention addresses these concerns.
- It should also be noted that the present invention has a unique fingerprint, a zone in the ceramic which is free of second phase particles. The zone starts at the metallization and extends down into the ceramic for some 5 to 100 microns in depth.
- While the present invention has been particularly described, in conjunction with a specific preferred embodiment, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present invention.
Claims (10)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/311,812 US6306528B1 (en) | 1997-07-02 | 1999-05-13 | Method for the controlling of certain second phases in aluminum nitride |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/887,375 US6004624A (en) | 1997-07-02 | 1997-07-02 | Method for the controlling of certain second phases in aluminum nitride |
US09/311,812 US6306528B1 (en) | 1997-07-02 | 1999-05-13 | Method for the controlling of certain second phases in aluminum nitride |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/887,375 Division US6004624A (en) | 1997-07-02 | 1997-07-02 | Method for the controlling of certain second phases in aluminum nitride |
Publications (2)
Publication Number | Publication Date |
---|---|
US6306528B1 US6306528B1 (en) | 2001-10-23 |
US20010055703A1 true US20010055703A1 (en) | 2001-12-27 |
Family
ID=25391014
Family Applications (3)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/887,375 Expired - Fee Related US6004624A (en) | 1997-07-02 | 1997-07-02 | Method for the controlling of certain second phases in aluminum nitride |
US09/311,812 Expired - Fee Related US6306528B1 (en) | 1997-07-02 | 1999-05-13 | Method for the controlling of certain second phases in aluminum nitride |
US09/311,811 Expired - Fee Related US6200373B1 (en) | 1997-07-02 | 1999-05-13 | Method for controlling of certain second phases in aluminum nitride |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US08/887,375 Expired - Fee Related US6004624A (en) | 1997-07-02 | 1997-07-02 | Method for the controlling of certain second phases in aluminum nitride |
Family Applications After (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/311,811 Expired - Fee Related US6200373B1 (en) | 1997-07-02 | 1999-05-13 | Method for controlling of certain second phases in aluminum nitride |
Country Status (1)
Country | Link |
---|---|
US (3) | US6004624A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050158666A1 (en) * | 1999-10-15 | 2005-07-21 | Taiwan Semiconductor Manufacturing Company, Ltd. | Lateral etch inhibited multiple etch method for etching material etchable with oxygen containing plasma |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3685656B2 (en) * | 1999-06-30 | 2005-08-24 | 太陽誘電株式会社 | Manufacturing method of multilayer ceramic electronic component |
US6395337B1 (en) * | 1999-07-30 | 2002-05-28 | International Business Machines Corporation | Substrate with ceramic coating for camber modification and method for making |
JP4787568B2 (en) * | 2004-11-16 | 2011-10-05 | 日本碍子株式会社 | Bonding agent, aluminum nitride bonded body, and manufacturing method thereof |
AT509204B1 (en) * | 2010-05-21 | 2011-07-15 | Siemens Vai Metals Tech Gmbh | COATING FOR MACHINE PARTS USED IN THE MANUFACTURE OF RAW STEEL OR STEEL |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5820160B2 (en) * | 1978-06-17 | 1983-04-21 | 日本碍子株式会社 | Ceramic body with metallized layer |
US4770953A (en) * | 1986-02-20 | 1988-09-13 | Kabushiki Kaisha Toshiba | Aluminum nitride sintered body having conductive metallized layer |
US4833108A (en) * | 1987-03-28 | 1989-05-23 | Narumi China Corporation | Sintered body of aluminum nitride |
CA1284536C (en) * | 1987-07-03 | 1991-05-28 | Akira Sasame | Member for semiconductor apparatus |
US5290375A (en) * | 1989-08-05 | 1994-03-01 | Nippondenso Co., Ltd. | Process for manufacturing ceramic multilayer substrate |
US5292552A (en) * | 1989-12-20 | 1994-03-08 | Sumitomo Electric Industries, Ltd. | Method for forming metallized layer on an aluminum nitride sintered body |
US5370907A (en) * | 1990-06-15 | 1994-12-06 | Sumitomo Electric Industries, Ltd. | Forming a metallized layer on an AlN substrate by applying and heating a paste of a metal composed of W and Mo |
US5424261A (en) * | 1993-12-22 | 1995-06-13 | The Carborundum Company | Low temperature sintering route for aluminum nitride ceramics |
US5482903A (en) * | 1993-12-22 | 1996-01-09 | International Business Machines Corporation | Aluminum nitride body utilizing a vitreous sintering additive |
US5541145A (en) * | 1993-12-22 | 1996-07-30 | The Carborundum Company/Ibm Corporation | Low temperature sintering route for aluminum nitride ceramics |
US5552232A (en) * | 1994-12-21 | 1996-09-03 | International Business Machines Corporation | Aluminum nitride body having graded metallurgy |
KR100436870B1 (en) * | 1995-07-19 | 2004-08-12 | 가부시끼가이샤 도꾸야마 | Aluminum nitride bonding structure |
-
1997
- 1997-07-02 US US08/887,375 patent/US6004624A/en not_active Expired - Fee Related
-
1999
- 1999-05-13 US US09/311,812 patent/US6306528B1/en not_active Expired - Fee Related
- 1999-05-13 US US09/311,811 patent/US6200373B1/en not_active Expired - Fee Related
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20050158666A1 (en) * | 1999-10-15 | 2005-07-21 | Taiwan Semiconductor Manufacturing Company, Ltd. | Lateral etch inhibited multiple etch method for etching material etchable with oxygen containing plasma |
Also Published As
Publication number | Publication date |
---|---|
US6004624A (en) | 1999-12-21 |
US6200373B1 (en) | 2001-03-13 |
US6306528B1 (en) | 2001-10-23 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US5604018A (en) | Ceramic oxide circuit board | |
US5254191A (en) | Method for reducing shrinkage during firing of ceramic bodies | |
US6139666A (en) | Method for producing ceramic surfaces with easily removable contact sheets | |
KR100756776B1 (en) | Aluminum nitride joined article and method for manufacture thereof | |
KR19990077529A (en) | The container for use in manufacturing a semiconductor and a method thereof | |
EP0100232A2 (en) | Substrate for semiconductor apparatus | |
US4935285A (en) | Ceramic substrates for microelectronic circuits and process for producing same | |
KR930004627B1 (en) | Metallized aluminum nitride substrate | |
US6200373B1 (en) | Method for controlling of certain second phases in aluminum nitride | |
KR940010095B1 (en) | Method of reducing shrinkage during firing of green ceramic bodies | |
US5613181A (en) | Co-sintered surface metallization for pin-join, wire-bond and chip attach | |
Barlow et al. | Multilayer ceramics | |
JP4688460B2 (en) | Glass ceramic multilayer wiring board with built-in capacitor | |
US5932043A (en) | Method for flat firing aluminum nitride/tungsten electronic modules | |
JP3683067B2 (en) | Aluminum nitride sintered body | |
JPH08109069A (en) | Aluminum nitride sintered compact | |
JP3171695B2 (en) | Manufacturing method of aluminum nitride circuit board | |
JP2736949B2 (en) | High strength aluminum nitride circuit board and method of manufacturing the same | |
JP3244309B2 (en) | Manufacturing method of aluminum nitride sintered body | |
JP3307862B2 (en) | Ceramic substrate | |
JP3658539B2 (en) | Aluminum nitride multilayer substrate | |
JP3198139B2 (en) | AlN metallized substrate | |
JP2659068B2 (en) | High thermal conductive AIN sintered body having metallized layer and high thermal conductive substrate using the same | |
JPH07307539A (en) | Circuit board and manufacture thereof | |
JP2022094464A (en) | Green sheet of silicon nitride and production method thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY Free format text: PAYER NUMBER DE-ASSIGNED (ORIGINAL EVENT CODE: RMPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
CC | Certificate of correction | ||
FPAY | Fee payment |
Year of fee payment: 4 |
|
REMI | Maintenance fee reminder mailed | ||
LAPS | Lapse for failure to pay maintenance fees | ||
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20091023 |
|
AS | Assignment |
Owner name: GLOBALFOUNDRIES U.S. 2 LLC, NEW YORK Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:INTERNATIONAL BUSINESS MACHINES CORPORATION;REEL/FRAME:036550/0001 Effective date: 20150629 |
|
AS | Assignment |
Owner name: GLOBALFOUNDRIES INC., CAYMAN ISLANDS Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:GLOBALFOUNDRIES U.S. 2 LLC;GLOBALFOUNDRIES U.S. INC.;REEL/FRAME:036779/0001 Effective date: 20150910 |