Abstract:
In some embodiments, annular via drilling (AVD) technology is presented. In this regard, an annular via is introduced comprising an inner wall and an outer wall, the inner wall and the outer wall coupled with a dielectric layer and extending linearly from a surface of a conductor to a top of the dielectric layer. Other embodiments are also disclosed and claimed.

Description:
FIELD OF THE INVENTION 
       [0001]    Embodiments of the present invention generally relate to the field of integrated circuit package vias, and, more particularly to annular via drilling (AVD) technology. 
       BACKGROUND OF THE INVENTION 
       [0002]    Lasers are commonly used in to remove material during integrated circuit package fabrication. Typically, laser drilling removes a cone-shaped portion of dielectric material which is plated and then laminated to replace the material removed, forming a via that provides vertical interconnection between layers. One potential problem, however, is that the plug material may not provide a coefficient of thermal expansion (CTE) equal to that of the material removed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]    The present invention is illustrated by way of example and not limitation in the figures of the accompanying drawings in which like references indicate similar elements, and in which: 
           [0004]      FIG. 1  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention; 
           [0005]      FIG. 2  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention; 
           [0006]      FIG. 3  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention; 
           [0007]      FIG. 4  is a flow chart of an example method for annular via drilling, in accordance with one example embodiment of the invention; and 
           [0008]      FIG. 5  is a block diagram of an example electronic appliance suitable for implementing an IC package substrate with annular via drilling technology, in accordance with one example embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that embodiments of the invention can be practiced without these specific details. In other instances, structures and devices are shown in block diagram form in order to avoid obscuring the invention. 
         [0010]    Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0011]      FIG. 1  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention. In accordance with the illustrated example embodiment, package substrate  100  includes one or more of substrate core  102 , dielectric material  104 , internal copper conductor  106 , conductor surface  108 , and dielectric surface  110 . 
         [0012]    Substrate core  102  represents a substrate core that may be made of a solid metal such as copper or may comprise multiple conductive layers laminated together. Substrate core  102  may be laminated with dielectric material as part of a substrate build-up and may have insulated traces routed through it. 
         [0013]    Dielectric material  104  represents material such as epoxy resin that has been added to substrate core  102  as part of a build-up process. Conductive traces may be routed within and through-holes may be routed through dielectric material  104  and/or core layer  102 . Internal copper conductor  106  is intended to represent a conductive trace embedded within dielectric material  104 . 
         [0014]      FIG. 2  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention. As part of a process for annular via drilling, for example as described in reference to  FIG. 4 , annular via  202  is formed in dielectric material  104 . 
         [0015]    Annular via  202  includes inner wall  204  and outer wall  206 , both adjacent to dielectric layer  104  and both extending linearly from dielectric surface  110  down to conductor surface  108 . In one embodiment, inner wall  204  and outer wall  206  extend parallel to each other, thereby providing annular via  202  with a uniform thickness. 
         [0016]    In one embodiment, annular via  202  represents a continuous circular (when viewed from above) via of diminishing radius extending inwardly from dielectric surface  110  to conductor surface  108 . In another embodiment, annular via  202  represents a discontinuous circular shape. In still other embodiment, annular via  202  need not be circular and may be any polygonal shape, either continuous or discontinuous. The shape of annular via  202  may be achieved by moving a laser over dielectric layer  104 , by moving substrate  100  under a laser, or by a combination of both. The present invention is not limited to any particular optics design. 
         [0017]      FIG. 3  is a graphical illustration of a cross-sectional view of a partially formed IC package substrate, in accordance with one example embodiment of the invention. As shown, plating, such as copper plating, has been added to annular via  202 . In one embodiment, annular via  202  is electroplated. In another embodiment, annular via  202  is electro-less plated. One skilled in the art would appreciate that plated annular via  202  is substantially flush with dielectric surface  110  and that dielectric material  104  inside of inner wall  204  has not been disturbed, thereby saving processing steps. 
         [0018]    In one embodiment, package substrate  100  is coupled with an integrated circuit die such as a flip chip microprocessor die through a copper bump formed on annular via  202 . In another embodiment, package substrate  100  is laminated with another dielectric layer as part of a continued build-up process. In another embodiment, package substrate  100  includes build-up layers having multiple annular vias stacked concentrically on top of one another. In another embodiment, package substrate  100  represents a high density interconnect (HDI) substrate with embedded thin film active or passive devices (not shown). 
         [0019]      FIG. 4  is a flow chart of an example method for annular via drilling, in accordance with one example embodiment of the invention. It will be readily apparent to those of ordinary skill in the art that although the following operations may be described as a sequential process, many of the operations may in fact be performed in parallel or concurrently. In addition, the order of the operations may be re-arranged or steps may be repeated without departing from the spirit of embodiments of the invention. 
         [0020]    According to but one example implementation, the method of  FIG. 4  begins with lamination ( 402 ) of dielectric material  104  on substrate core  102  (and conductor  106 ). 
         [0021]    Next, annular via drilling ( 404 ) in dielectric material  104  occurs, forming annular via  202 . 
         [0022]    Next, annular via  202  is plated ( 406 ), for example with copper. 
         [0023]    Lastly, further build-up and processing ( 408 ) is performed on substrate  100 . Additional steps may be needed to complete the substrate, such as forming a copper bump coupled with annular via  202 , and to couple the substrate with a microprocessor die, before the processor package can be placed in an electronic device, such as shown in  FIG. 5 . 
         [0024]      FIG. 5  is a block diagram of an example electronic appliance suitable for implementing an IC package substrate with annular via drilling technology, in accordance with one example embodiment of the invention. Electronic appliance  500  is intended to represent any of a wide variety of traditional and non-traditional electronic appliances, laptops, desktops, cell phones, wireless communication subscriber units, wireless communication telephony infrastructure elements, personal digital assistants, set-top boxes, or any electric appliance that would benefit from the teachings of the present invention. In accordance with the illustrated example embodiment, electronic appliance  500  may include one or more of processor(s)  502 , memory controller  504 , system memory  506 , input/output controller  508 , network controller  510 , and input/output device(s)  512  coupled as shown in  FIG. 5 . Processor(s)  502 , or other integrated circuit components of electronic appliance  500 , may be housed in a package including a substrate described previously as an embodiment of the present invention. 
         [0025]    Processor(s)  502  may represent any of a wide variety of control logic including, but not limited to one or more of a microprocessor, a programmable logic device (PLD), programmable logic array (PLA), application specific integrated circuit (ASIC), a microcontroller, and the like, although the present invention is not limited in this respect. In one embodiment, processors(s)  502  are Intel® compatible processors. Processor(s)  502  may have an instruction set containing a plurality of machine level instructions that may be invoked, for example by an application or operating system. 
         [0026]    Memory controller  504  may represent any type of chipset or control logic that interfaces system memory  508  with the other components of electronic appliance  500 . In one embodiment, the connection between processor(s)  502  and memory controller  504  may be referred to as a front-side bus. In another embodiment, memory controller  504  may communicate on a point-to-point link. 
         [0027]    System memory  506  may represent any type of memory device(s) used to store data and instructions that may have been or will be used by processor(s)  502 . Typically, though the invention is not limited in this respect, system memory  506  will consist of dynamic random access memory (DRAM). In one embodiment, system memory  506  may consist of Rambus DRAM (RDRAM). In another embodiment, system memory  506  may consist of double data rate synchronous DRAM (DDRSDRAM). 
         [0028]    Input/output (I/O) controller  508  may represent any type of chipset or control logic that interfaces I/O device(s)  512  with the other components of electronic appliance  500 . In one embodiment, I/O controller  508  may be referred to as a south bridge. In another embodiment, I/O controller  508  may comply with the Peripheral Component Interconnect (PCI) Express™ Base Specification, Revision 1.0a, PCI Special Interest Group, released Apr. 15, 2003. 
         [0029]    Network controller  510  may represent any type of device that allows electronic appliance  500  to communicate with other electronic appliances or devices. In one embodiment, network controller  510  may comply with a The Institute of Electrical and Electronics Engineers, Inc. (IEEE) 802.11b standard (approved Sep. 16, 1999, supplement to ANSI/IEEE Std 802.11, 1999 Edition). In another embodiment, network controller  510  may be an Ethernet network interface card. 
         [0030]    Input/output (I/O) device(s)  512  may represent any type of device, peripheral or component that provides input to or processes output from electronic appliance  500 . 
         [0031]    In the description above, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form. 
         [0032]    Many of the methods are described in their most basic form but operations can be added to or deleted from any of the methods and information can be added or subtracted from any of the described messages without departing from the basic scope of the present invention. Any number of variations of the inventive concept is anticipated within the scope and spirit of the present invention. In this regard, the particular illustrated example embodiments are not provided to limit the invention but merely to illustrate it. Thus, the scope of the present invention is not to be determined by the specific examples provided above but only by the plain language of the following claims.