1. Technical Field
Disclosed embodiments relate to a wire-bond technology for a substrate. More particularly, disclosed embodiments relate to bond fingers on the substrate that are aligned with their respective die pads on silicon.
2. Description of Related Art
A wire-bonding package usually requires significant routing of traces within a printed circuit board (PCB). The advent of wireless technologies has led to a push to miniaturize packaged integrated circuits such that conventional wire bonding has become a hindrance with the push to miniaturize. Additionally, various traces on the surface of the PCB, that are routed to locations remote from the wire bond, can result in significant cross-talk that diminishes the performance of the packaged integrated circuit.
In order to understand the manner in which embodiments are obtained, a more particular description of various embodiments briefly described above will be rendered by reference to the appended drawings. Understanding that these drawings depict only typical embodiments that are not necessarily drawn to scale and are not therefore to be considered to be limiting of its scope, some embodiments will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
The following description includes terms, such as upper, lower, first, second, etc. that are used for descriptive purposes only and are not to be construed as limiting. The embodiments of a device or article described herein can be manufactured, used, or shipped in a number of positions and orientations. The terms “die” and “processor” generally refer to the physical object that is the basic workpiece that is transformed by various process operations into the desired integrated circuit device. A board is typically a resin-impregnated fiberglass structure that acts as a mounting substrate for the die. A die is usually singulated from a wafer, and wafers may be made of semiconducting, non-semiconducting, or combinations of semiconducting and non-semiconducting materials.
Reference will now be made to the drawings wherein like structures will usually be provided with like reference designations. In order to show the structure and process embodiments most clearly, the drawings included herein are diagrammatic representations of embodiments. Thus, the actual appearance of the fabricated structures, for example in a photomicrograph, may appear different while still incorporating the essential structures of embodiments. Moreover, the drawings show only the structures necessary to understand the embodiments. Additional structures known in the art have not been included to maintain the clarity of the drawings.
Formation of the via 120 can be accomplished by various process flows. In an embodiment, the wire-bond pad 116 is first formed, and the via 120 is formed by laser drilling through the lower protective layer 114, the substrate core 110, and finally through the upper protective layer 112. In an embodiment, the laser drilling is operated to stop on the wire-bond pad 116. In an embodiment, laser drilling is done by drilling at a site that is later occupied by wire-bond pad 116. In this embodiment, the laser drilling is done first, and the placement of the wire-bond pad 116 is done subsequently.
A die 124 is depicted mounted upon the mounting substrate 100 at the upper protective layer 112. The die 124 includes an active surface 130 and a backside surface 132. Electrical coupling of the die 124 to the via 120 is done between a die bond pad 126, a bond wire 128, and the wire-bond pad 116. The die bond pad 126 is disposed upon the active surface 130 of the die 124. Although not depicted, the die 124 is adhered to the mounting substrate 100 by a material such as an organic, thermal adhesive or the like. The adhesive is disposed between the backside surface 132 of the die 124 and the upper protective layer 112.
In an embodiment, a process of wirebonding includes reverse wire bonding. The process includes first attaching the bond wire 128 at the wire-bond pad 116, followed by second attaching the bond wire 128 at the die bond pad 126. In an embodiment, a process of wirebonding includes forward wire bonding. The process includes first attaching the bond wire 128 at the die bond pad 126, followed by second attaching the bond wire 128 at the wire-bond pad 116.
The staggered configuration includes substantially the same pitch as the plurality of die bond pads 426. The substantially same pitch is defined by the spacing 430, which is the orthogonal distance, between a first symmetry line 425 and a second symmetry line 427. In other words, the overall pitch of the wire-bond pads 416, 417 is staggered. The staggered wire bond pads 416 and 417 include a second pitch that is quantified by a first substrate bond pad 416 disposed along the first symmetry line 425 and the second substrate bond pad 419 is disposed along the second symmetry line 427. As set forth herein, the first symmetry line 425 and the second symmetry line 427 are spaced apart by a distance substantially equivalent to the first pitch of the die bond pads 426.
In an embodiment, electronic tuning of the package is done by making the first bond wire 428 the same length, or the like, as the second bond wire 429. Although the first wire-bond pad 416 is closer to its respective die bond pad 426 than the second wire-bond pad 417 is to its respective die bond pad (not pictured), the lengths of the respective bond wires 428 and 429 are tuned to achieve a similar signal delay during operation of the die 424.
In an embodiment, a process of wirebonding includes reverse wire bonding. The process includes first attaching the first bond wire 428 at the first wire-bond pad 416, followed by second attaching the first bond wire 428 at a first die bond pad 426. Similarly, the process includes first attaching the second bond wire 429 at the second wire-bond pad 417, followed by second attaching the second bond wire 429 at a second die bond pad (not pictured). In an embodiment, a process of wirebonding includes forward wire bonding. The process includes first attaching the first bond wire 428 at the first die bond pad 426, followed by second attaching the first bond wire 428 at the first wire-bond pad 416. Similarly, the process includes first attaching the second bond wire 429 at a second die bond pad (not pictured), followed by second attaching the second bond wire 429 at the second wire-bond pad 417.
The wire-bond pad 616 is depicted as a raised structure above the upper protective layer 612. In an embodiment, the wire-bond pad 616 is at least flush with the upper protective layer 612. In an embodiment, a via liner 620 is a metallic or otherwise electrically conductive material that provides an electrical path through the mounting substrate 600.
In an embodiment, the first via 618 is filled with an interconnect (not pictured) such as the interconnect 122 depicted in
In an embodiment, a process of wirebonding includes reverse wire bonding. The process includes first attaching the first bond wire 628 at the first wire-bond pad 616, followed by second attaching the first bond wire 628 at a first die bond pad 626. Where a second bond wire is present for a staggered wire-bond pad with respect to the first wire-bond pad 616, the process includes first attaching the second bond wire at the second wire-bond pad, followed by second attaching the second bond wire at a second die bond pad. In an embodiment, a process of wirebonding includes forward wire bonding. The process includes first attaching the first bond wire 628 at the first die bond pad 626, followed by second attaching the first bond wire 628 at the first wire-bond pad 616. Where a second bond wire is present for a staggered wire-bond pad with respect to the first wire-bond pad 616, the process includes first attaching the second bond wire at a second die bond pad (not pictured), followed by second attaching the second bond wire at the second wire-bond pad.
In an embodiment, a process of wirebonding includes reverse wire bonding. The process includes first attaching the first bond wire 728 at the first wire-bond pad 716, followed by second attaching the first bond wire 728 at a first die bond pad 726. In an embodiment, a process of wirebonding includes forward wire bonding. The process includes first attaching the first bond wire 728 at the first die bond pad 726, followed by second attaching the first bond wire 728 at the first wire-bond pad 716.
A first via 820 is depicted penetrating the substrate core 810, the upper protective layer 812, and the lower protective layer 814. A wire-bond pad 816 is depicted directly above the first via 820. In an embodiment, a second via (not pictured) such as the second via 419 in
In an embodiment, a process of wirebonding includes reverse wire bonding as set forth herein. Where a second bond wire is present for a staggered wire-bond pad with respect to the first wire-bond pad 816, the process includes first attaching the second bond wire at the second wire-bond pad, followed by second attaching the second bond wire at a second die bond pad. In an embodiment, a process of wirebonding includes forward wire bonding as set forth herein.
Each first die bond pad 926 is coupled to a respective first wire-bond pad 916 by a first bond wire 928. Similarly, each second die bond pad 927 is coupled to a respective second wire-bond pad 917 by a second bond wire 929. In an embodiment, electronic tuning of the package is done by making the first bond wire 928 the same length, or the like, as the second bond wire 929.
In an embodiment, a process of wirebonding includes reverse wire bonding as set forth herein. Where a second bond wire is present for a second die bond pad 927 with respect to the first die bond pad 926, the process includes first attaching the second bond wire at the first wire-bond pad 926, followed by second attaching the second bond wire at a second die bond pad 927. In an embodiment, a process of wirebonding includes forward wire bonding as set forth herein.
The package 1000 illustrates first and second wire-bond pads 1016 and 1017, respectively, arrayed with a first pitch in relation to the staggered configuration of the first and second die bond pads 1026 and 1027, respectively, each with substantially the same pitch as the wire-bond. The substantially same pitch is defined by the spacing 1030 between a first symmetry line 1032 and a second symmetry line 1034.
In an embodiment, a process of wirebonding includes reverse wire bonding as set forth herein. In an embodiment, a process of wirebonding includes forward wire bonding as set forth herein.
A via 1118 is depicted penetrating the substrate core 1110, the upper protective layer 1112, and the lower protective layer 1114. The wire-bond pad 1116 is depicted as a raised structure above the upper protective layer 1112. In an embodiment, the wire-bond pad 1116 is at least flush with the upper protective layer 1112. In an embodiment, a via liner 1120 is a metallic or otherwise electrically conductive material that provides an electrical path through the substrate core 1110.
A bond wire 1128 is depicted as having been bonded to the wire-bond pad 1116. The metal of the bond wire 1128 is selected from aluminum or an aluminum alloy, gold or a gold alloy, silver or a silver alloy, doré, or platinum or a platinum alloy. One feature of an embodiment is the ability of the heavy plating layer 1117 to bond with bond wire 1128, but not to alloy therewith. In some applications, a bond wire article may be rejected by pulling or cutting the bond wires and repeating the bond wire process flow.
In an embodiment, the flash plating layer 1115 is a precious metal or precious metal alloy. In an embodiment, the flash plating layer 1115 is formed by a deposition process flow that is electroless plating. In an embodiment, the precious metal for the flash plating layer 1115 includes silver, gold, platinum, and combinations thereof. In an embodiment, the flash plating layer 1115 is primarily gold, such as a majority thereof or a plurality thereof. In an embodiment, the flash plating layer 1115 is primarily silver such as a majority thereof or a plurality thereof. In an embodiment, the precious metal for the flash plating layer 1115 includes nickel, palladium, platinum, and combinations thereof. In an embodiment, the flash plating layer 1115 is primarily platinum such as a majority thereof or a plurality thereof. In an embodiment, the precious metal for the flash plating layer 1115 includes cobalt, rhodium, iridium, and combinations thereof. In an embodiment, the flash plating layer 1115 is primarily iridium such as a majority thereof or a plurality thereof.
In an embodiment, the heavy plating layer 1117 is formed of identical material to the flash plating layer 1115. In an embodiment, the heavy plating layer 1117 is at least one of a more noble, or a softer (more ductile) metal than the flash plating layer 1115. In an embodiment, the heavy plating layer 1117 is selected from gold, doré, platinum, and other compositions that are more noble and more ductile than the flash plating layer 1115.
An embodiment includes a heavy plating layer 1117 that resists alloying with the bond wire 1128 during ordinary wire-bonding process flows. In an embodiment, an aluminum or aluminum alloy bond wire 1128 is attached to the heavy plating layer 1117. In an embodiment, a gold or gold alloy bond wire 1128 is attached to the heavy plating layer 1117. In an embodiment, a silver or silver alloy bond wire 1128 is attached to the heavy plating layer 1117. In an embodiment, a doré bond wire 1128 is attached to the heavy plating layer 1117. In an embodiment, a platinum or platinum alloy bond wire 1128 is attached to the heavy plating layer 1117.
In an embodiment, the formation of the heavy plating layer 1117 is carried out according to vapor deposition techniques, or by liquid plating techniques as set forth herein. In an embodiment, formation of the heavy plating layer 1117 is carried out by electroless plating by using a gold-cyanide electroless plating solution, and the Merrill-Crowe or other precipitation technique. In this embodiment, an atom-thick layer of zinc (Zn, not pictured) is pre-plated onto the flash plating layer 1115 by an electroless process that does not substantially cover the upper protective layer 1112, and the gold-cyanide solution is contacted with the zinc which causes the reduction of the gold out of the gold-cyanide complex.
In an electroless plating embodiment, a gold halide solution is Eh-pH manipulated according to the technique pioneered by Pourbaix. In an embodiment, the flash plating layer 1115 acts as an autocatalytic surface to assist the selective precipitation of the heavy plating layer 1117.
In an embodiment, the heavy plating layer 1117 is formed by a chemical vapor deposition (CVD) process that is carried out during which an organometallic gold vapor or a gold halide vapor is metered, blanket deposited, and patterned with an etch. In an embodiment, the heavy plating layer 1117 is formed by a physical vapor deposition (PVD) process that is carried out in which a gold target is impinged under PVD conditions to form a blanket layer of gold that is subsequently patterned into the heavy plating layer 1117.
At 1210, the process can commence by forming the wire-bond pad on a mounting substrate. In an embodiment, the process flow terminates at 1210.
At 1220, the wire-bond pads are staggered. According to a process flow embodiment, the wire-bond pads are staggered and the die bond pads are substantially linear as set forth herein. In an embodiment, the process flow terminates at 1220.
At 1222, the die bond pads are staggered. According to a process flow embodiment, the die bond pads are staggered and the wire-bond pads are substantially linear as set forth herein. In an embodiment, the process flow terminates at 1222.
According to a process flow embodiment, the die bond pads are staggered and the die bond pads are staggered as set forth herein. In an embodiment, the process flow terminates after passing through 1220 and 1222.
At 1230, the process flow includes an embodiment of reverse wire bonding as set forth herein. In an embodiment, the process flow terminates at 1230.
At 1232, the process flow includes an embodiment of forward wire bonding as set forth herein. In an embodiment, the process flow terminates at 1232.
For purposes of this disclosure, a computing system 1300 embodying components in accordance with the claimed subject matter may include any system that utilizes a microelectronic device package, which may include, for example, a data storage device such as dynamic random access memory, polymer memory, flash memory, and phase-change memory. The microelectronic device package can also include a die that contains a digital signal processor (DSP), a micro controller, an application specific integrated circuit (ASIC), or a microprocessor.
Embodiments set forth in this disclosure can be applied to devices and apparatuses other than a traditional computer. For example, a die can be packaged with an embodiment of the substantially same-pitch wire-bond pad to die bond pad configuration, and placed in a portable device such as a wireless communicator or a hand-held device such as a personal data assistant and the like. Another example is a die that can be packaged with an embodiment of the substantially same-pitch wire-bond pad to die bond pad configuration and placed in a vehicle such as an automobile, a locomotive, a watercraft, an aircraft, or a spacecraft.
The Abstract is provided to comply with 37 C.F.R. §1.72(b) requiring an Abstract that will allow the reader to quickly ascertain the nature and gist of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.
In the foregoing Detailed Description, various features are grouped together in a single embodiment for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments of the invention require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separate preferred embodiment.
It will be readily understood to those skilled in the art that various other changes in the details, material, and arrangements of the parts and method stages which have been described and illustrated in order to explain the nature of this invention may be made without departing from the principles and scope of the invention as expressed in the subjoined claims.