US20010000495A1 - Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein - Google Patents
Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein Download PDFInfo
- Publication number
- US20010000495A1 US20010000495A1 US09/730,371 US73037100A US2001000495A1 US 20010000495 A1 US20010000495 A1 US 20010000495A1 US 73037100 A US73037100 A US 73037100A US 2001000495 A1 US2001000495 A1 US 2001000495A1
- Authority
- US
- United States
- Prior art keywords
- integrated circuit
- circuit chip
- metal layer
- metals
- layer
- 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.)
- Abandoned
Links
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L24/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
- H01L21/71—Manufacture of specific parts of devices defined in group H01L21/70
- H01L21/768—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
- H01L21/76898—Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics formed through a semiconductor substrate
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
- H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L24/10—Bump connectors ; Manufacturing methods related thereto
- H01L24/11—Manufacturing methods
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/10—Bump connectors; Manufacturing methods related thereto
- H01L2224/12—Structure, shape, material or disposition of the bump connectors prior to the connecting process
- H01L2224/13—Structure, shape, material or disposition of the bump connectors prior to the connecting process of an individual bump connector
- H01L2224/13001—Core members of the bump connector
- H01L2224/13099—Material
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
- H01L2224/81—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected using a bump connector
- H01L2224/818—Bonding techniques
- H01L2224/81801—Soldering or alloying
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01006—Carbon [C]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01013—Aluminum [Al]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01022—Titanium [Ti]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01032—Germanium [Ge]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01049—Indium [In]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/0105—Tin [Sn]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01074—Tungsten [W]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01078—Platinum [Pt]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01079—Gold [Au]
-
- 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
- H01L2924/01—Chemical elements
- H01L2924/01082—Lead [Pb]
-
- 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
- H01L2924/013—Alloys
- H01L2924/0132—Binary Alloys
- H01L2924/01322—Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
-
- 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
- H01L2924/10—Details of semiconductor or other solid state devices to be connected
- H01L2924/102—Material of the semiconductor or solid state bodies
- H01L2924/1025—Semiconducting materials
- H01L2924/1026—Compound semiconductors
- H01L2924/1032—III-V
- H01L2924/10329—Gallium arsenide [GaAs]
-
- 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
- H01L2924/10—Details of semiconductor or other solid state devices to be connected
- H01L2924/11—Device type
- H01L2924/14—Integrated circuits
-
- 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
- H01L2924/10—Details of semiconductor or other solid state devices to be connected
- H01L2924/11—Device type
- H01L2924/14—Integrated circuits
- H01L2924/141—Analog devices
- H01L2924/1423—Monolithic Microwave Integrated Circuit [MMIC]
-
- 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
- H01L2924/30—Technical effects
- H01L2924/301—Electrical effects
- H01L2924/3011—Impedance
Definitions
- the present invention relates to a method for attaching an integrated circuit chip to a substrate, e.g., a housing or other next level structure, and an integrated circuit chip useful in such a method.
- the method is useful for attaching a high power integrated circuit, e.g., a microwave monolithic integrated circuit (MMIC) to a housing.
- MMIC microwave monolithic integrated circuit
- Integrated circuit chips can be attached to a housing using a manual eutectic attachment technique.
- a eutectic material preform e.g., a gold-tin eutectic material preform
- Scrubbing is generally required for the component attachment and there has been a lack of eutectic material flow control when using a manual eutectic attachment technique.
- most gold-tin eutectic attachments are performed with gold-tin preforms and gold plated surfaces. The gold from the gold plated surface tends to diffuse into the preform. The resultant gold rich composition causes the rework temperature to increase.
- Integrated circuits e.g., high power integrated circuits
- the thermal conductivity of the epoxy material which is used to attach the integrated circuits, especially GaAs or InP integrated circuits, with the automated assembly is about one tenth the thermal conductivity of a eutectic material, e.g., gold-tin, gold-germanium, tin-lead.
- Heat generated by high power integrated circuits, e.g., MMIC's must be removed to keep the operation temperature compatible with the device limitation.
- the lower thermal conductivity of the epoxy adhesive limits the device power or increases the operation temperature.
- the invention provides an integrated circuit chip which includes a substrate, a plurality of transistors provided in the substrate, a circuit pattern provided on a top surface of the substrate and a metal layer comprising at least two metals in substantially eutectic proportions provided on a bottom surface of the substrate, the bottom surface of the metal layer being exposed.
- the integrated circuit chip can be attached to a further substrate, e.g., a housing, using automated attachment techniques.
- the chip can be attached to the housing by picking up the integrated circuit chip with the metal layer provided on the bottom surface thereof and placing the integrated circuit chip, e.g., under programmed control, onto a housing so the bottom surface of the integrated circuit chip faces the housing with the metal layer there between; and then heating the metal layer to a temperature above its eutectic temperature to melt the metal layer and attach the integrated circuit chip to the housing.
- the metal layer can be provided on the bottom surface of the integrated circuit chip by depositing at least one layer of each of the at least two metals and inter diffusing the at least two metals, e.g., in an inert atmosphere to a temperature below the melting point of the metals and at or above a temperature sufficient to inter diffuse the at least two metals.
- the layer can be provided by plating at least one layer of each of the at least two metals on the bottom surface of the integrated circuit chip and inter diffusing the at least two metals. Alternatively, they can be simultaneously plated or vacuum deposited.
- the housing is preferably made of a material, e.g., AlSiC, having a coefficient of thermal expansion close to that of the integrated circuit chip.
- the present invention is especially applicable to high power integrated circuit chips, e.g., microwave monolithic integrated circuits, e.g., those made of GaAs or InP, which generate considerable heat which, according to the present invention, can be conducted away from the chip through the eutectic material.
- the eutectic material can be, e.g., a gold-tin eutectic.
- the eutectic layer when the housing has a gold layer on a surface to which the integrated circuit chip is attached, the eutectic layer, as deposited, can be slightly tin rich (e.g., gold:tin ratio of 78:22) in order to accommodate diffusion of gold from the housing surface to provide the eutectic proportions (80:20).
- a metal barrier layer e.g., nickel for preventing diffusion of materials from said integrated circuit chip into the eutectic metal layer is preferably provided on the back surface of the chip.
- the chip is attached to the housing by heating the metal layer to a temperature above its eutectic temperature, e.g., by heating the metal layer to a temperature 30-55° C. above its eutectic temperature in an inert atmosphere. No scrubbing is required.
- FIG. 1 is a schematic cross-sectional view showing a non-limitative example of a portion of an integrated circuit chip according to the present invention.
- FIG. 2 is a schematic cross-sectional view showing a non-limitative example of an integrated circuit chip according to the present invention prior to its attachment to a housing or next level structure.
- FIG. 1 is a schematic cross-sectional view showing a portion of an integrated circuit chip of the present invention which can be used in a reworkable automated eutectic attachment system.
- FIG. 1 shows a portion of an integrated circuit chip 10 , e.g, a high power integrated circuit chip, e.g., a microwave monolithic integrated circuit (MMIC).
- the chip 10 includes a substrate 12 , e.g., made of GaAs or InP.
- the chip 10 has a top side circuit 14 , a portion of which is shown in FIG. 1.
- the chip 10 also includes a plurality of transistors, one transistor 16 being shown in FIG. 1 and including a drain 18 and source 20 and a gate 22 .
- a via 24 is provided in the substrate 12 .
- Metalization is provided on the bottom side of the chip 10 . In this case, the metalization includes a titanium adhesion layer 26 , a tungsten barrier layer 28 and a gold conductive layer 30 .
- a nickel under-plate layer 32 is provided to prevent gold leaching and eutectic flow as will be described hereinafter.
- a spacer layer 34 e.g., made of nickel, is provided, e.g., by plating.
- the function of the spacer layer 34 will be described hereinafter.
- the eutectic material is deposited on the spacer 34 , e.g., by plating.
- a photolithographic determined pattern (with the use of a photoresist) is used to define the plating area.
- the metals making up the eutectic material are deposited in layers. More specifically, in the embodiment shown in FIG. 1, a gold metal 36 is deposited, a tin layer 38 and a second gold layer 40 .
- the layers are preferably deposited by plating, since plating can be economically used to provide thicker layers.
- Other deposition techniques e.g., vacuum deposition, can also be used.
- Vacuum deposition techniques are preferably used for providing thinner layers, e.g., for smaller components. Vacuum deposition allows deposition of materials which cannot be plated, e.g., gold-germanium.
- the plated gold layer 36 , tin layer 38 and gold layer 40 are then interdiffused by heating in an inert atmosphere at a temperature lower than the melting temperature of the separate elements.
- the layers can be heat treated for approximately three hours at 220° C.
- the heat treatment causes the plated gold surface to change color (from gold to metallic gray).
- the heat treatment can be conducted under any inert atmosphere, e.g., nitrogen.
- the melting temperature of the composite structure (280° C.) is higher than the melting temperature of tin (232° C.).
- FIG. 2 shows the chip 10 after interdiffusion of the metals, e.g., gold and tin, whereby the chip 10 has a metal layer 42 comprising the metals, gold and tin, in substantially eutectic proportions on a bottom surface of the chip 10 .
- the bottom side metalization (titanium layer 26 , tungsten barrier 28 , gold conductive layer 30 and nickel under plate 32 ) on the bottom side of the chip 10 is not shown in FIG. 2 but would cover all areas of the chip 10 except the edge set back portions 44 .
- the chip 10 with the integral eutectic metal layer 42 is picked up by an automated assembly tool, e.g., model 3500 automated assembly machine sold by Palamar of Carlsdad, Calif.
- the automated assembly tool picks up the chip 10 and places it, e.g., on a hot plate with a covering inert gas, e.g., nitrogen.
- the hot plate temperature is set up to be about 40 to 60° C. above the eutectic temperature.
- the attachment surface temperature is 30 to 55° C. above the eutectic temperature.
- the circuit pattern 14 on the component allows the automated assembly machine to precisely pick and place the component within 0.0005 inches of the target location.
- the plating pattern provided by the spacer pattern 34 in combination with the thickness of the eutectic metal layer 42 is designed so that the volume of the eutectic metal layer 42 is approximately equal to the volume (space) of the channels 46 formed between the pattern of spacers 34 .
- the channels 46 are areas that are not plated with spacer material 34 . Since eutectic material which flows away from the chip 10 can short out circuits and prevent other components from being placed, the channels 46 are designed to accommodate the molten eutectic material within the perimeter of the chip 10 so that the molten eutectic material does not flow away excessively from the chip 10 .
- the spacers 34 are provided in the areas that have a need for thermal conduction. The spacers 34 can also control the bond line minimum thickness and can support all bonding pads.
- the housing or next level structure to which the chip 10 is attached is preferably made of a material, e.g., AlSiC, having a coefficient of thermal expansion close to that of the integrated circuit chip.
- a material e.g., AlSiC
- the material of the housing have a coefficient of thermal expansion less than 10 PPM/° C.
- the eutectic metal layer 42 is made slightly gold deficient, i.e., slightly tin rich, e.g., gold:tin ratio of 78:22, in order to accommodate diffusion of gold from the housing surface to provide the eutectic proportions (80:20). This will ensure that reworking can be conducted at the eutectic temperature.
- the under plate layer 32 e.g., nickel, prevents the components backside gold plating 30 from diffusing or dissolving in the molten eutectic material during the attachment process.
- metal layer 42 has been described as a gold-tin eutectic metal layer, other materials can be used as long as the material has a melting point within the range of about 50 to 400° C. Since it is preferable that the material have a limited, precise melting point, eutectic materials are preferred, e.g., gold-tin, gold-germanium, tin-lead.
- the thickness of the metal layer 42 depends on the type of chip, but is preferably in the range of 0.1 to 3.0 mil, more preferably 0.5 to 1.0 mil, especially in the case of MMIC chips. While minimum eutectic material thickness can minimize thermal impedance, the volume of the eutectic material must be sufficient to fill the space between two poorly matched surfaces. A 0.5 mil thick metal layer 42 should be sufficient for surface roughness of up to 40 micro inches.
Abstract
An integrated circuit chip (10) includes a substrate (12), a plurality of transistors (16) provided in the substrate (12), a circuit pattern (14) provided on a top surface of the substrate (12) and a metal layer (42) comprising at least two metals in substantially eutectic proportions provided on a bottom surface of the substrate, the bottom surface of the metal layer (42) being exposed. The integrated circuit chip (10) can be attached to a farther substrate, e.g., a housing, using automated attachment techniques. The chip (10) can be attached to the housing by picking up the integrated circuit chip (10) with the metal layer (42) provided on the bottom surface thereof and placing the integrated circuit chip (10) onto a housing so the bottom surface of the integrated circuit chip (10) faces the housing with the metal layer (42) there between; and then heating the metal layer (42) to a temperature above its eutectic temperature to melt the metal layer and attach the integrated circuit chip (10) to the housing.
Description
- 1. The present invention relates to a method for attaching an integrated circuit chip to a substrate, e.g., a housing or other next level structure, and an integrated circuit chip useful in such a method. In particular, the method is useful for attaching a high power integrated circuit, e.g., a microwave monolithic integrated circuit (MMIC) to a housing.
- 2. Integrated circuit chips can be attached to a housing using a manual eutectic attachment technique. In such a technique, a eutectic material preform, e.g., a gold-tin eutectic material preform, is provided between the integrated circuit chip and the housing. Scrubbing is generally required for the component attachment and there has been a lack of eutectic material flow control when using a manual eutectic attachment technique. In addition, most gold-tin eutectic attachments are performed with gold-tin preforms and gold plated surfaces. The gold from the gold plated surface tends to diffuse into the preform. The resultant gold rich composition causes the rework temperature to increase.
- 3. Integrated circuits, e.g., high power integrated circuits, can be attached to a housing or other next level structure by an automated assembly system using an epoxy adhesive. However, the thermal conductivity of the epoxy material which is used to attach the integrated circuits, especially GaAs or InP integrated circuits, with the automated assembly is about one tenth the thermal conductivity of a eutectic material, e.g., gold-tin, gold-germanium, tin-lead. Heat generated by high power integrated circuits, e.g., MMIC's, must be removed to keep the operation temperature compatible with the device limitation. The lower thermal conductivity of the epoxy adhesive limits the device power or increases the operation temperature.
- 4. Applicants have found that there is a need to replace the low thermal conductivity adhesive with a better thermal conductivity material to enhance heat dissipation and enable high power output. There is also a need to provide a method for attaching an integrated circuit chip to a substrate with a method which is susceptible to automated assembly systems.
- 5. The invention provides an integrated circuit chip which includes a substrate, a plurality of transistors provided in the substrate, a circuit pattern provided on a top surface of the substrate and a metal layer comprising at least two metals in substantially eutectic proportions provided on a bottom surface of the substrate, the bottom surface of the metal layer being exposed. The integrated circuit chip can be attached to a further substrate, e.g., a housing, using automated attachment techniques. The chip can be attached to the housing by picking up the integrated circuit chip with the metal layer provided on the bottom surface thereof and placing the integrated circuit chip, e.g., under programmed control, onto a housing so the bottom surface of the integrated circuit chip faces the housing with the metal layer there between; and then heating the metal layer to a temperature above its eutectic temperature to melt the metal layer and attach the integrated circuit chip to the housing.
- 6. The metal layer can be provided on the bottom surface of the integrated circuit chip by depositing at least one layer of each of the at least two metals and inter diffusing the at least two metals, e.g., in an inert atmosphere to a temperature below the melting point of the metals and at or above a temperature sufficient to inter diffuse the at least two metals. In order to economically deposit the metal layer, especially when larger thicknesses are required, e.g., up to 3.0 mil, the layer can be provided by plating at least one layer of each of the at least two metals on the bottom surface of the integrated circuit chip and inter diffusing the at least two metals. Alternatively, they can be simultaneously plated or vacuum deposited.
- 7. The housing is preferably made of a material, e.g., AlSiC, having a coefficient of thermal expansion close to that of the integrated circuit chip. The present invention is especially applicable to high power integrated circuit chips, e.g., microwave monolithic integrated circuits, e.g., those made of GaAs or InP, which generate considerable heat which, according to the present invention, can be conducted away from the chip through the eutectic material.
- 8. The eutectic material can be, e.g., a gold-tin eutectic. When the housing has a gold layer on a surface to which the integrated circuit chip is attached, the eutectic layer, as deposited, can be slightly tin rich (e.g., gold:tin ratio of 78:22) in order to accommodate diffusion of gold from the housing surface to provide the eutectic proportions (80:20). A metal barrier layer, e.g., nickel for preventing diffusion of materials from said integrated circuit chip into the eutectic metal layer is preferably provided on the back surface of the chip.
- 9. The chip is attached to the housing by heating the metal layer to a temperature above its eutectic temperature, e.g., by heating the metal layer to a temperature 30-55° C. above its eutectic temperature in an inert atmosphere. No scrubbing is required.
- 10.FIG. 1 is a schematic cross-sectional view showing a non-limitative example of a portion of an integrated circuit chip according to the present invention.
- 11.FIG. 2 is a schematic cross-sectional view showing a non-limitative example of an integrated circuit chip according to the present invention prior to its attachment to a housing or next level structure.
- 12.FIG. 1 is a schematic cross-sectional view showing a portion of an integrated circuit chip of the present invention which can be used in a reworkable automated eutectic attachment system. FIG. 1 shows a portion of an
integrated circuit chip 10, e.g, a high power integrated circuit chip, e.g., a microwave monolithic integrated circuit (MMIC). Thechip 10 includes asubstrate 12, e.g., made of GaAs or InP. Thechip 10 has atop side circuit 14, a portion of which is shown in FIG. 1. Thechip 10 also includes a plurality of transistors, onetransistor 16 being shown in FIG. 1 and including adrain 18 andsource 20 and agate 22. Avia 24 is provided in thesubstrate 12. Metalization is provided on the bottom side of thechip 10. In this case, the metalization includes atitanium adhesion layer 26, atungsten barrier layer 28 and a goldconductive layer 30. - 13. A nickel under-plate layer 32 is provided to prevent gold leaching and eutectic flow as will be described hereinafter.
- 14. On the bottom surface of the nickel under-plate, a
spacer layer 34, e.g., made of nickel, is provided, e.g., by plating. The function of thespacer layer 34 will be described hereinafter. The eutectic material is deposited on thespacer 34, e.g., by plating. A photolithographic determined pattern (with the use of a photoresist) is used to define the plating area. In the embodiment shown in FIG. 1, the metals making up the eutectic material are deposited in layers. More specifically, in the embodiment shown in FIG. 1, agold metal 36 is deposited, atin layer 38 and asecond gold layer 40. The layers are preferably deposited by plating, since plating can be economically used to provide thicker layers. Other deposition techniques, e.g., vacuum deposition, can also be used. Vacuum deposition techniques are preferably used for providing thinner layers, e.g., for smaller components. Vacuum deposition allows deposition of materials which cannot be plated, e.g., gold-germanium. - 15. The plated
gold layer 36,tin layer 38 andgold layer 40 are then interdiffused by heating in an inert atmosphere at a temperature lower than the melting temperature of the separate elements. For example, for gold and tin, the layers can be heat treated for approximately three hours at 220° C. The heat treatment causes the plated gold surface to change color (from gold to metallic gray). The heat treatment can be conducted under any inert atmosphere, e.g., nitrogen. The melting temperature of the composite structure (280° C.) is higher than the melting temperature of tin (232° C.). FIG. 2 shows thechip 10 after interdiffusion of the metals, e.g., gold and tin, whereby thechip 10 has ametal layer 42 comprising the metals, gold and tin, in substantially eutectic proportions on a bottom surface of thechip 10. The bottom side metalization (titanium layer 26,tungsten barrier 28,gold conductive layer 30 and nickel under plate 32) on the bottom side of thechip 10 is not shown in FIG. 2 but would cover all areas of thechip 10 except the edge set back portions 44. - 16. The
chip 10 with the integraleutectic metal layer 42 is picked up by an automated assembly tool, e.g., model 3500 automated assembly machine sold by Palamar of Carlsdad, Calif. The automated assembly tool picks up thechip 10 and places it, e.g., on a hot plate with a covering inert gas, e.g., nitrogen. The hot plate temperature is set up to be about 40 to 60° C. above the eutectic temperature. The attachment surface temperature is 30 to 55° C. above the eutectic temperature. Thecircuit pattern 14 on the component allows the automated assembly machine to precisely pick and place the component within 0.0005 inches of the target location. - 17. The plating pattern provided by the
spacer pattern 34, in combination with the thickness of theeutectic metal layer 42 is designed so that the volume of theeutectic metal layer 42 is approximately equal to the volume (space) of thechannels 46 formed between the pattern ofspacers 34. Thechannels 46 are areas that are not plated withspacer material 34. Since eutectic material which flows away from thechip 10 can short out circuits and prevent other components from being placed, thechannels 46 are designed to accommodate the molten eutectic material within the perimeter of thechip 10 so that the molten eutectic material does not flow away excessively from thechip 10. Thespacers 34 are provided in the areas that have a need for thermal conduction. Thespacers 34 can also control the bond line minimum thickness and can support all bonding pads. - 18. The housing or next level structure to which the
chip 10 is attached is preferably made of a material, e.g., AlSiC, having a coefficient of thermal expansion close to that of the integrated circuit chip. In the case of MMIC chips made of GaAs or InP, it is preferred that the material of the housing have a coefficient of thermal expansion less than 10 PPM/° C. Since the housing surface would typically have a gold layer thereon, it is preferred that theeutectic metal layer 42, as deposited, is made slightly gold deficient, i.e., slightly tin rich, e.g., gold:tin ratio of 78:22, in order to accommodate diffusion of gold from the housing surface to provide the eutectic proportions (80:20). This will ensure that reworking can be conducted at the eutectic temperature. - 19. The under plate layer 32, e.g., nickel, prevents the components backside gold plating 30 from diffusing or dissolving in the molten eutectic material during the attachment process.
- 20. While the
metal layer 42 has been described as a gold-tin eutectic metal layer, other materials can be used as long as the material has a melting point within the range of about 50 to 400° C. Since it is preferable that the material have a limited, precise melting point, eutectic materials are preferred, e.g., gold-tin, gold-germanium, tin-lead. - 21. The thickness of the
metal layer 42 depends on the type of chip, but is preferably in the range of 0.1 to 3.0 mil, more preferably 0.5 to 1.0 mil, especially in the case of MMIC chips. While minimum eutectic material thickness can minimize thermal impedance, the volume of the eutectic material must be sufficient to fill the space between two poorly matched surfaces. A 0.5 milthick metal layer 42 should be sufficient for surface roughness of up to 40 micro inches. - 22. It is preferable that picking up of the
integrated circuit chip 10 with themetal layer 42 provided thereon and placing the integratingcircuit chip 10 onto a housing or other next level structure be accomplished using an automated assembly machine under programmed control. Such automated assembly machines are known in the art. Satisfactory results have been obtained using a Palomar Model 3500 machine. Applicants have previously used the Palomar Model 3500 for accurate placement of chips using epoxy adhesive. Applicants have modified the Palomar Model 3500 machine to operate at higher temperatures to achieve attachment using the eutectic metal layer. While the Palomar Model 3500 is able to apply scrubbing action to the components, applicants have found that component surface damage, e.g., scratches, can occur. Therefore, scrubbing is neither recommended nor required.
Claims (31)
1. A method for attaching an integrated circuit chip to a substrate, comprising the steps of:
providing an integrated circuit chip;
providing a metal layer comprising at least two metals in substantially eutectic proportions on a bottom surface of the integrated circuit chip;
picking up the integrated circuit chip with the metal layer provided on the bottom surface thereof and placing the integrated circuit chip onto a substrate so the bottom surface of the integrated circuit chip faces the substrate with the metal layer there between; and
heating the metal layer to a temperature above its eutectic temperature to melt the metal layer and attach the integrated circuit chip to the substrate.
2. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises the steps of depositing at least one layer of each of the at least two metals and inter-diffusing the at least two metals.
claim 1
3. A method according to , wherein the step of inter diffusing the at least two metals comprises heating the at least one layer of each of the at least two metals in an inert atmosphere to a temperature below the melting point of the metals and at or above a temperature sufficient to inter diffuse the at least two metals.
claim 2
4. A method according to , wherein the step of depositing at least one layer of each of the at least two metals comprises plating at least one layer of each of the at least two metals on the bottom surface of the integrated circuit chip.
claim 2
5. A method according to , wherein the step of depositing at least one layer of each of the at least two metals comprises vacuum depositing at least one layer of each of the at least two metals on the bottom surface of the integrated circuit chip.
claim 2
6. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises simultaneously depositing the at least two metals in substantially eutectic proportions.
claim 1
7. A method according to , wherein the substrate is a housing.
claim 1
8. A method according to , wherein the housing is made of a material having a coefficient of thermal expansion close to that of the integrated circuit chip, and wherein the housing has a gold layer on a surface to which the integrated circuit chip is attached.
claim 7
9. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises depositing gold and tin in substantially eutectic proportions on the bottom surface of the integrated circuit chip.
claim 8
10. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises the steps of depositing at least one layer of each of gold and tin and inter diffusing the layers of gold and tin.
claim 9
11. A method according to , wherein, in the step of depositing at least one layer of each of gold and tin, a weight ratio of gold:tin is about 78:22.
claim 10
12. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises depositing gold and tin in substantially eutectic proportions on the bottom surface of the integrated circuit chip.
claim 1
13. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises the steps of depositing at least one layer of each of gold and tin and inter diffusing the layers of gold and tin.
claim 12
14. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises depositing the at least two metals by plating and wherein a thickness of the metal layer is 0.1-3.0 mil.
claim 1
15. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises depositing the at least two metals by plating and wherein a thickness of the metal layer is about 0.5-1.0 mil.
claim 1
16. A method according to , wherein the step of heating the metal layer to a temperature above its eutectic temperature comprises heating the metal layer to a temperature 30-55°C. above its eutectic temperature.
claim 1
17. A method according to , wherein the step of heating the metal layer to a temperature above its eutectic temperature comprises heating the metal layer to a temperature 30-55° C. above its eutectic temperature in an inert atmosphere.
claim 1
18. A method according to , wherein the step of providing the metal layer comprising at least two metals in substantially eutectic proportions on the bottom surface of the integrated circuit chip comprises providing the metal layer on a barrier layer for preventing diffusion of materials from said integrated circuit chip into the metal layer.
claim 1
19. A method according to , wherein the barrier layer comprises nickel.
claim 1
20. A method according to , wherein the integrated circuit chip is a high power integrated circuit chip.
claim 1
21. A method according to , wherein the high power integrated circuit chip comprises GaAs or InP and the substrate comprises AlSiC.
claim 20
22. A method according to , wherein the high power integrated circuit chip is a microwave monolithic integrated circuit chip.
claim 20
23. A method according to , wherein the step of picking up the integrated circuit chip with the metal layer provided on the bottom surface thereof and placing the integrated circuit chip onto the substrate is accomplished using an automated assembly machine.
claim 1
24. A method according to , wherein the step of picking up the integrated circuit chip with the metal layer provided on the bottom surface thereof and placing the integrated circuit chip onto the substrate is done under programmed control.
claim 1
25. An integrated circuit chip, comprising a substrate, a plurality of transistors provided in the substrate, a circuit pattern provided on a top surface of the substrate and a metal layer comprising at least two metals in substantially eutectic proportions provided on a bottom surface of the substrate, wherein a bottom surface of the metal layer is exposed.
26. An integrated circuit chip according to , wherein the at least two metals in substantially eutectic proportions are plated on the substrate and the metal layer has a thickness of 0.1-3.0 mil.
claim 25
27. An integrated circuit chip according to , wherein the metal layer comprises a layer containing gold and tin in substantially eutectic proportions.
claim 25
28. An integrated circuit chip according to , wherein the metal layer comprises a layer containing gold and tin having a weight ratio of gold:tin of about 78:22.
claim 25
29. An integrated circuit chip according to , wherein the metal layer comprises a layer containing gold and tin having a weight ratio of gold:tin in a range of 76:24-80:20.
claim 25
30. An integrated circuit chip according to , wherein the metal layer comprises at least one layer of gold and at least one layer of tin.
claim 25
31. An integrated circuit chip according to , wherein a thickness of each of the at least one layer of gold and at least one layer of tin provide a weight ratio of gold:tin in a range of 76:24-80:20.
claim 25
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/730,371 US20010000495A1 (en) | 1999-06-07 | 2000-12-05 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US09/327,772 US6294402B1 (en) | 1999-06-07 | 1999-06-07 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
US09/730,371 US20010000495A1 (en) | 1999-06-07 | 2000-12-05 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/327,772 Division US6294402B1 (en) | 1999-06-07 | 1999-06-07 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
Publications (1)
Publication Number | Publication Date |
---|---|
US20010000495A1 true US20010000495A1 (en) | 2001-04-26 |
Family
ID=23278005
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/327,772 Expired - Lifetime US6294402B1 (en) | 1999-06-07 | 1999-06-07 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
US09/730,371 Abandoned US20010000495A1 (en) | 1999-06-07 | 2000-12-05 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/327,772 Expired - Lifetime US6294402B1 (en) | 1999-06-07 | 1999-06-07 | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein |
Country Status (1)
Country | Link |
---|---|
US (2) | US6294402B1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2834283B1 (en) * | 2001-12-28 | 2005-06-24 | Commissariat Energie Atomique | PROCESS AND AREA OF SEALING BETWEEN TWO SUBSTRATES OF A MICROSTRUCTURE |
US20030198032A1 (en) * | 2002-04-23 | 2003-10-23 | Paul Collander | Integrated circuit assembly and method for making same |
US6902872B2 (en) * | 2002-07-29 | 2005-06-07 | Hewlett-Packard Development Company, L.P. | Method of forming a through-substrate interconnect |
AU2003275108B2 (en) * | 2003-09-17 | 2009-08-27 | Samsung Electronics Co., Ltd. | Method of forming a through-substrate interconnect |
DE102005024430B4 (en) * | 2005-05-24 | 2009-08-06 | Infineon Technologies Ag | Process for coating a silicon wafer or silicon chip |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3802065A (en) * | 1972-03-16 | 1974-04-09 | Gen Electric | Method and structure for mounting semiconductor chips |
US5089439A (en) * | 1990-02-02 | 1992-02-18 | Hughes Aircraft Company | Process for attaching large area silicon-backed chips to gold-coated surfaces |
US5027997A (en) * | 1990-04-05 | 1991-07-02 | Hughes Aircraft Company | Silicon chip metallization system |
US5156998A (en) * | 1991-09-30 | 1992-10-20 | Hughes Aircraft Company | Bonding of integrated circuit chip to carrier using gold/tin eutectic alloy and refractory metal barrier layer to block migration of tin through via holes |
US5470787A (en) * | 1994-05-02 | 1995-11-28 | Motorola, Inc. | Semiconductor device solder bump having intrinsic potential for forming an extended eutectic region and method for making and using the same |
JP3613838B2 (en) * | 1995-05-18 | 2005-01-26 | 株式会社デンソー | Manufacturing method of semiconductor device |
-
1999
- 1999-06-07 US US09/327,772 patent/US6294402B1/en not_active Expired - Lifetime
-
2000
- 2000-12-05 US US09/730,371 patent/US20010000495A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
US6294402B1 (en) | 2001-09-25 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CA2032266C (en) | Integrated circuit solder die-attach design and method | |
EP2224479B1 (en) | Metal-ceramic composite substrate and method of its manufacture | |
EP0061593B1 (en) | Solder support pad for semiconductor devices | |
US4577398A (en) | Method for mounting a semiconductor chip | |
KR940001149B1 (en) | Chip bonding method of semiconductor device | |
US6833289B2 (en) | Fluxless die-to-heat spreader bonding using thermal interface material | |
US6235551B1 (en) | Semiconductor device including edge bond pads and methods | |
US4451972A (en) | Method of making electronic chip with metalized back including a surface stratum of solder | |
JP3559432B2 (en) | Method of forming a semiconductor metallization system and its structure | |
CN103811437A (en) | Microelectronic package having direct contact heat spreader and method of manufacturing same | |
US6309965B1 (en) | Method of producing a semiconductor body with metallization on the back side that includes a titanium nitride layer to reduce warping | |
WO2005096731A2 (en) | Heat spreader constructions, integrated circuitry, methods of forming heat speader contruictions, and methods of forming integrated circuitry | |
US5198695A (en) | Semiconductor wafer with circuits bonded to a substrate | |
EP0631313A1 (en) | Semiconductor device containing a through hole | |
US6294402B1 (en) | Method for attaching an integrated circuit chip to a substrate and an integrated circuit chip useful therein | |
US7078272B2 (en) | Wafer scale integration packaging and method of making and using the same | |
US6586279B1 (en) | Method of integrating a heat spreader and a semiconductor, and package formed thereby | |
US5917236A (en) | Packaging system for field effects transistors | |
US20220384298A1 (en) | Electronic device comprising an electronic chip mounted on top of a support substrate | |
KR19980024894A (en) | Semiconductor body with a layer of solder material | |
JP2980066B2 (en) | Semiconductor device | |
US5483105A (en) | Module input-output pad having stepped set-back | |
JP2703908B2 (en) | Compound semiconductor device | |
US20230369166A1 (en) | Power semiconductor module arrangement and method for producing the same | |
JPS62122157A (en) | Electrode structure of heat sink for photosemiconductor |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |