Patent Application
20160329275
This U.S. non-provisional patent application claims priority under 35 U.S.C. §119 of Korean Patent Application No. 10-2015-0063970, filed on May 7, 2015, the entire contents of which are hereby incorporated by reference.
The inventive concept relates to packages, and more particularly, to a package substrate surface-treated using aluminum and a semiconductor package including such package substrate.
As an electronic component has a high density, various surface treatment technologies for a printed circuit board (PCB) have been developed. A metal plating method as one of the surface treatment technologies for the PCB has been used. The metal plating method may include an electroplating method and an electroless metal plating method. As the PCB has become higher in component density and the metal plating layer has become thinner, a surface of the PCB has been electroless-treated in order to simplify a process for the PCB and reduce a noise in the PCB.
Since an electroless nickel immersion gold (ENIG), and an electroless nickel electroless palladium immersion gold (ENEPIG) have a good solder joint reliability and a good wire bonding reliability, they have been used in various fields as well as in PCB and a package substrate.
According to one aspect of the inventive concept, a package substrate is provided. The package substrate includes an insulating substrate having a top surface and a bottom surface, a circuit pattern disposed on at least one of the top surface of the insulating substrate, and a multilayer conductive joint unit disposed on the circuit pattern. The multilayer conductive joint unit comprises a nickel layer which is in contact with the circuit pattern, and an aluminum layer on the nickel layer and connected to a semiconductor chip mounted on the insulating substrate.
In one embodiment of the inventive concept, the multilayer conductive joint unit further comprises a metal layer between the nickel layer and the aluminum layer.
In another embodiment of the inventive concept, the metal layer comprises titanium (Ti), tantalum (Ta), titanium nitride (TiN), tantalum nitride (TaN), gold (Au), silver (Ag), or tungsten (W).
In another embodiment of the inventive concept, a thickness of the contact pad is 0.1 μm˜1 μm.
In another embodiment of the inventive concept, the insulating substrate comprises a core unit, an upper interconnection layer disposed on a top surface of the core unit, an upper insulating layer disposed on the upper interconnection layer, a lower interconnection layer disposed on a bottom surface of the core unit, and a lower insulating layer disposed on the lower interconnection layer.
In another embodiment of the inventive concept, the nickel layer is an electroless plating layer.
In another embodiment of the inventive concept, the insulating substrate further comprises a solder resist layer disposed on the circuit pattern. The solder resist layer has a hole exposing a part of the circuit pattern.
In another embodiment of the inventive concept, the nickel layer and the aluminum layer are disposed inside the hole of the solder resist layer.
In another embodiment of the inventive concept, the nickel layer is provided to cover a top surface and a side surface of the circuit pattern.
In another embodiment of the inventive concept, the nickel layer is provided to cover a part of a top surface of the circuit pattern.
In another embodiment of the inventive concept, the substrate comprises a PCB (printed circuit board) or a flexible PCB.
According to another aspect of the inventive concept, a package substrate is provided. The package substrate comprises a copper pad, an insulating layer, and a multilayer conductive joint unit. The copper pad is disposed on a top surface of the insulating layer. The joint unit comprises a nickel layer in contact with the copper pad, and a contact pad disposed on the nickel layer. The contact pad includes metallic compound including aluminum.
In one embodiment of the inventive concept, the contact pad is made of Al or Al—Cu.
In another embodiment of the inventive concept, the multilayer conductive joint unit further comprises a metal layer disposed between the nickel layer and the contact pad. The metal layer comprises titanium (Ti), tantalum (Ta), titanium nitride (TiN), tantalum nitride (TaN), gold (Au), silver (Ag), or tungsten (W).
In another embodiment of the inventive concept, the multilayer conductive joint unit further comprises an aluminum oxide layer formed on a top surface of the contact pad. The bonding wire penetrates the aluminum oxide layer to electrically connect the contact pad and the semiconductor chip.
In another embodiment of the inventive concept, the package substrate further comprises a semiconductor chip mounted on the package substrate. The semiconductor chip is electrically connected to the package substrate by a bonding wire, and the bonding wire penetrates the aluminum oxide layer to electrically connect the contact pad and the semiconductor chip.
In another embodiment of the inventive concept, the package substrate further comprises a solder resist layer disposed on the copper pad and the insulating layer. The solder resist layer exposes a part of the copper pad and a side wall of the hole surrounds the multilayer conductive joint unit.
According to another aspect of the inventive concept, a package substrate is provided. The package substrate comprises a core unit, an insulation layer disposed on the core unit, a circuit pattern disposed on the insulation layer, and a multilayer conductive joint unit disposed on the circuit pattern. The multilayer conductive joint unit comprises a bottom conductive layer and a contact pad. The bottom conductive layer is in contact with the circuit pattern.
In another embodiment, the bottom layer of the multilayer conductive joint unit comprises a nickel layer, and the multilayer conductive joint further includes a middle metal layer between the nickel layer and the contact pad to increase an adhesive strength between the nickel layer and the contact pad.
In another embodiment, the package substrate further comprises a solder resist layer disposed on the insulating layer and the circuit pattern. The solder resist layer includes a hole exposing a top surface of at least a part of the circuit pattern and the multilayer conductive joint is disposed inside the hole.
In another embodiment, the package substrate further comprises a solder resist layer disposed on the circuit pattern. The solder resist layer includes a hole exposing a top surface and a side surface of a pad of the circuit pattern. The nickel layer covers the top surface and the side surface of the pad of the circuit pattern, the contact pad covers a top and a side surface of the nickel layer such that a side surface of the contact pad contacts sidewalls of the hole, and a top surface of the contact pad is exposed to air to form the aluminum oxide layer.
In another embodiment, the contact pad is made of Al, Al—Cu, Al—Si or Al—Cu-Si.
According to another aspect of the inventive concept a method of manufacturing a package substrate is provided. The method includes forming a solder resist layer on an insulating layer and a circuit pattern disposed on the insulating layer so that a part of the circuit pattern is exposed, forming a nickel layer electrically connected to the exposed circuit pattern, and forming a contact pad on the nickel layer. The contact pad is wire-bonded to a semiconductor chip mounted on the package substrate.
In one embodiment of the inventive concept, the contact pad is formed by an inkjet method.
In another embodiment of the inventive concept, the inkjet method includes coating the nickel layer with an aluminum precursor or aluminum nano particles.
In another embodiment of the inventive concept, the contact pad is formed by a plating method using an ionic liquid and an organic solution, a dipping process, a screening process or a slot die process.
In another embodiment of the inventive concept, the contact pad is formed by a sputtering method.
In another embodiment of the inventive concept, the bonding wire is connected to the contact pad by penetrating an aluminum oxide layer formed on the contact pad.
Preferred embodiments of the inventive concept will be described below in more detail with reference to the accompanying drawings. The embodiments of the inventive concept may, however, be embodied in different forms and should not be constructed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Similar numbers refer to similar elements throughout.
Embodiments of inventive concepts will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. Like numbers refer to like elements throughout.
Embodiments of the inventive concept may be described with reference to cross-sectional illustrations, which are schematic illustrations of idealized embodiments of the present invention. As such, variations from the shapes of the illustrations, as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments of the present invention should not be construed as limited to the particular shapes of regions illustrated herein, but are to include deviations in shapes that result from, e.g., manufacturing. For example, a region illustrated as a rectangle may have rounded or curved features. Thus, the regions illustrated in the figures are schematic in nature and are not intended to limit the scope of the present invention.
Referring to
In some embodiments, the package substrate 100 may include an insulating substrate having a top surface and a bottom surface, circuit patterns 140a, 140b disposed on the top surface and the bottom surface of the insulating layer respectively; and a multilayer conductive joint unit 190 disposed on the circuit patterns,
In some embodiments, the package substrate 100 may include a core unit 110, interconnection layers 120a and 120b, insulation layers 130a and 130b, circuit patterns 140a and 140b, and a multilayer conductive joint unit 190. In some embodiments, the package substrate 100 may be a PCB (printed circuit board) or a flexible substrate.
The core unit 110 may include a resin and a glass fiber. The glass fiber may be one of reinforcing materials and may be obtained by twisting hundreds of strands of glass filaments having a diameter of 5 μm˜15 μm to make a fiber bundle and then weaving the fiber bundle. The glass filament may be ore products whose main ingredient is silica. The glass fiber may have superior heat resistance, superior mechanical strength and superior electric insulation. Alternatively, the package substrate 100 may be a PCB (printed circuit board) or a flexible substrate, which do not include the core unit 110.
The interconnection layers 120a and 120b may be disposed on the core unit 110. The interconnection layers 120a and 120b may include or be made of plating material such as nickel (Ni) or copper (Cu), or polymer having superior thermal conductive property. The interconnection layers 120a and 120b may include an upper interconnection layer 120a disposed on a top surface of the core unit 110 and a lower interconnection layer 120b disposed on a bottom surface of the core unit 110. The upper interconnection layer 120a and the lower interconnection layer 120b may be electrically connected to each other through a first via 125. The first via 125 may penetrate the core unit 110. The first via 125 may include or be made of plating material such as nickel (Ni) or copper (Cu), or polymer having superior thermal conductive property.
The insulation layers 130a and 130b may be disposed on the interconnection layers 120a and 120b, respectively. The insulation layers 130a and 130b may include or be made of resin. The insulation layers 130a and 130b may include an upper insulation layer 130a disposed on the upper interconnection layer 120a and a lower insulation layer 130b disposed on the lower interconnection layer 120b.
The circuit patterns 140a and 140b may be disposed on the insulation layers 130a and 130b, respectively. The circuit patterns 140a and 140b may include or be made of copper (Cu). The circuit patterns 140a and 140b may include an upper circuit pattern 140a disposed on the upper insulation layer 130a and a lower circuit pattern 140b disposed on the lower insulation layer 130b. The upper circuit pattern 140a and the upper interconnection layer 120a may be electrically connected to each other through a second via 135a. The second via 135a may penetrate the upper insulation layer 130a. The lower circuit pattern 140b and the lower interconnection layer 120b may be electrically connected to each other through a third via 135b. The third via 135b may penetrate the lower insulation layer 130b. The second via 135a and the third via 135b may include or be made of plating material such as nickel (Ni) or copper (Cu), or polymer having superior thermal conductive property.
A solder resist layer 150 may be disposed on the upper circuit pattern 140a. The solder resist layer 150 may include a hole 155 exposing a part of a top surface of the upper circuit pattern 140a. The solder resist layer 150 may include or be made of an insulating coating layer. The solder resist layer 150 may protect the upper circuit pattern 140a and may prevent a bridge phenomenon from occurring between the upper circuit patterns 140a.
The multilayer conductive joint unit 190 may be disposed inside the hole 155. The sidewall of the hole 155 may surround or be in contact with side surfaces of the multilayer conductive joint unit 190. In some embodiments, the multilayer conductive joint unit 190 may include a bottom conductive layer disposed on the upper circuit pattern 140a and a contact pad 180 disposed on the nickel layer 160. In some embodiments, the bottom conductive layer may include a nickel layer 160 contact pad. The nickel layer 160 can prevent copper (Cu) from being diffused between the upper circuit pattern 140a and the contact pad 180. The nickel layer 160 may include phosphorus to prevent oxidation of nickel (Ni) included in the nickel layer 160. For example, the nickel layer 160 may include phosphorus of 5 wt %˜12 wt %. A width of the nickel layer 160 may be smaller than width of the upper circuit pattern 140a. A thickness of the nickel layer 160 may be 2 μm˜8 μm.
The contact pad 180 may include or be made of aluminum (Al) or metallic compound including aluminum (Al). For example, the contact pad 180 may comprise Al—Si, Al—Cu or Al—Cu-Si. The contact pad 180 may include a small amount of Silicon and Copper. Silicon may control a size of aluminum crystals contained within the contact pad 180. Copper may prevent migration of aluminum contained within the contact pad 180. A thickness of the contact pad 180 may be 0.1 μm˜1 μm. The contact pad 180 can prevent oxidation of the nickel layer 160 and may be connected to the semiconductor chip 200 by the wire bonding. Since a stable aluminum oxide layer 185 is naturally formed on a surface of the contact pad 180, defects such as a surface discoloration may not occur. For example, the aluminum oxide layer 185 formed may comprise alumina (Al2O3). Aluminum (Al) has good electrical conductivity, is inexpensive. When aluminum is used to replace gold (Au) in a conventional ENIG (electroless nickel immersion gold), the manufacturing cost of the package substrate can be reduced.
The semiconductor chip 200 may be disposed on the package substrate 100. The semiconductor chip 200 may be a logic chip, a memory chip, or combinations thereof.
The bonding wire 300 can electrically connect the package substrate 100 and the semiconductor chip 200. The bonding wire 300 may include or be made of copper (Cu) or gold (Au). The bonding wire 300 can electrically connect a top surface of the semiconductor chip 200 and the contact pad 180 of the package substrate 100. Aluminum has good electrical conductivity but has a high oxidation characteristic. Accordingly, the aluminum oxide layer 185 may be formed at a portion where the contact pad 180 is exposed to air. The aluminum oxide layer 185 may obstruct an electrical connection between the bonding wire 300 and the contact pad 180. Thus, the bonding wire 300 may penetrate the aluminum oxide layer 185 to be directly connected to the contact pad 180.
Referring to
The insulation layers 130a and 130b may be formed by coating insulation material on the upper interconnection layer 120a and the lower interconnection layer 120b and then hardening the insulation material. The upper insulation layer 130a and the lower insulation layer 130b may be formed on the upper interconnection layer 120a and the lower interconnection layer 120b, respectively. The insulation material may include or be made of resin.
Circuit layers 145a and 145b may be formed on the insulation layers 130a and 130b, respectively. An upper circuit layer 145a may be formed on the upper insulation layer 130a and a lower circuit layer 145b may be formed on the lower insulation layer 130b. The circuit layers 145a and 145b may include or be made of copper (Cu).
Referring to
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The contact pad 180 may be formed through an inkjet method, a physical vapor deposition (PVD) method, a plating method using an ionic liquid and an organic solution, a dipping process, a screening process, or a slot die process. The inkjet method may be a method of coating the nickel layer 160 with an aluminum precursor or aluminum nano particles. For example, the aluminum precursor may be alanate (AlH3). The alanate (AlH3) is easily decomposed into aluminum (Al) and hydrogen (H2) at a low temperature (e.g., 150° C.). The alanate (AlH3) may be decomposed at a room temperature using a proper catalyst. Thus, aluminum is easily embodied as an electrical circuit and an electrode using the alanate (AlH3). Alternatively, the contact pad 180 may be formed by coating and then drying the aluminum precursor and the aluminum nano particles.
The slot die process may be a process of applying metallic liquid using a pulsation free pump pulsate or a piston pump. Aluminum can be coated in a uniform thickness using the slot die process.
The screening process may be a process of using a metallic fluid as ink and putting a pressure using a roller.
The dipping process may be a process of dipping a substance into a molten metal (for example, aluminum) to coat the substance with the molten metal.
The plating method using an ionic liquid and an organic solution, and a physical vapor deposition (PVD) method may be performed by the conventional method.
Referring to
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The semiconductor package describe above may be applied to the electronic system. The semiconductor package may be provided in the form of memory device. Referring to
The electronic system 1300 may be embodied by a mobile system, a personnel computer, an industrial computer or a logic system performing a variety of functions. For example, the mobile system may be one of a personal digital assistant (PDA), a portable computer, a web tablet, a mobile phone, a wireless phone, a laptop computer, a memory card, a digital music system and a data transmission/receipt system. When the electronic system 1300 is equipment capable of performing a wireless communication, the electronic system 1300 may be used in a third generation communication interfacing protocol such as CDMA, GSM, NADC, E-TDMA, and CDMA2000.
The semiconductor device to which the technique of the present inventive concept is applied may be provided in the form of a memory card. Referring to
According to embodiments of the inventive concept, a manufacturing cost can be reduced by using an inexpensive aluminum in lieu of gold in the surface treatment for the package substrate.
According to embodiments of the inventive concept, the package substrate surface-treated with aluminum can be wire-bonded to the semiconductor chip. Through the wire bonding process, the bonding wire can penetrate the aluminum oxide layer formed on the contact pad to electrically connect the package substrate and the contact pad.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2015-0063970 | May 2015 | KR | national |
