Memory Packages Having Stair Step Interconnection Layers
Disclosed are IC package structures having stair stepped layers and which have no plated vias. Such structures can be fabricated either as discrete packages or as strips such as might be beneficial in for use with memory devices wherein critical or high speed signals can be routed along the length of the multi-chip strip package without having to have the signals ascend and descend from the interconnection substrate on which the assembly is mounted to the IC package termination and back as the signal transmits between devices.
This application is a continuation of U.S. patent application Ser. No. 11/381,357 filed on May 2, 2006, which is a continuation-in-part of U.S. patent application Ser. No. 10/987,187, filed on Nov. 12, 2004, now U.S. Pat. No. 7,388,279, which claims the benefit of U.S. Provisional Application 60/519, 945 filed Nov. 12, 2003, and of U.S. Provisional Application 60/676,863, filed May 2, 2005, all of which are incorporated by reference in their entirety herein.
FIELD OF THE INVENTIONThe present invention relates to the field of high speed electronic interconnections for memory and the packaging of semiconductor integrated circuits for use therewith.
BACKGROUNDMemory integrated circuits “ICs” for use with most computers operate at speeds slower than current generation central processing unit “CPU” ICs creating a condition generally referred to as the “memory bottleneck”. In such condition, the CPU must remain in a wait state until the memory data is written or retrieved. The problem has been addressed, in part, by improved memory system designs. However as electronic systems move into the multi-gigabit per second data rate range, a significant gap remains between top-end operating rates of CPU ICs and memory ICs. Part of this ongoing disparity is due to the limits of current interconnection design, which often results, particularly at higher frequencies, in disturbances that contribute to signal distortion. For example, signal distortion can often be due, at least in part to so-called parasitic effects resulting from traditional interconnect designs. Because signal speed and signal integrity are two primary goals in digital signal transmission, interconnect designs that assure signal integrity during data transmission are key. Controlling signal integrity begins with the design of the circuit. Choices made in terms of circuit layout, and the materials used and the general architecture of the complete assembly, will all have impact of the quality if the signal transmission and its ultimate integrity.
Because parasitic effects and signal discontinuity are primary sources of signal disturbance, one of the major objectives in maintaining signal integrity is to eliminate or minimize the parasitic effects and electrical discontinuities impinging upon a signal. Parasitic effects and electrical discontinuities are caused by a number of factors such as sharp changes in direction, changes in material, circuit feature flaws and even interconnections, such as solder balls used to connect IC packages to next level interconnection substrates. All these can affect signal integrity by introducing undesirable changes in impedance and creating signal reflections. There is also concern about signal skew, cause by differing signal lengths, which is important in assuring proper signal timing.
The first place in an electronic system such parasitic effects are encountered, beyond those encountered within the IC structure itself, is the IC package which is used to connect the IC die to a next level interconnection system. While current generation IC packages are presently reasonably well suited to meeting current needs, as the electronics industry moving to ever higher data signaling rates, the formerly minor concerns associated with packages and interconnection paths have now reached a level of critical importance.
The net effect of this complex web of interactive elements is that they collectively combine to make it extremely difficult to predict and design for reliable high performance at higher processing speeds. Additionally, at higher processing speeds, parasitic effects and signal discontinuities and reflections can contribute to the thermal demands placed on a system. Thus, as memory circuit speeds climb, there is need for new approaches to design of memory package interconnections to overcome the looming and highly complex electrical and thermal problems associated with traditional approaches to IC memory packaging.
The present invention is best illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which
Disclosed herein using descriptions and figures are IC package structures having stair step connections for use with memory devices and which improve control of the quality of an electronic signal that passes though a memory chip package and between memory chips. Moreover, the nature of the memory package assembly disclosed offers a structure better suited to thermal management than current package designs.
The embodiments disclosed herein address the limitations of current design and manufacturing practices employed in the fabrication of electronic memory device and system interconnections and the present inability of those design and manufacturing practices to address fully and adequately the needs for improved electronic signal integrity as the electronic signal transitions between memory chips on an electronic memory module.
An objective of the present disclosure to describe memory package structures which provide direct and uniform controlled impedance across the surface of a memory package by routing high speed signals on a controlled impedance first layer.
Another objective is to describe a first layer having one or more signal paths which provides a substantially skew free address line for clocking signals on the package while routing other signals, such as power and ground, on a second stair stepped layer wherein both metal layers are interconnected to the IC memory die.
It is yet another objective of the present disclosure to describe memory package structures which reduce the number of I/O required on the package due to the package structure's ability to transmit data directly between chips within the package.
It is yet another objective of the present disclosure to describe memory package structures which provide for improved thermal dissipation.
The present embodiments offer novel alternative approaches to addressing and meeting the stated objectives thus solving certain problems associated with current design approaches. Throughout this disclosure, many specific details are recited which are not essential to make or use the embodiments described herein. Accordingly, these details are offered for purposes of clarity and enablement, and are not intended to limit the spirit and scope of the embodiments described herein, which includes variations and equivalent structures and processes. For example, the IC die (IC chip) is shown in the attached drawings as having two central rows of bond pads. The depiction of this detail is not intended to limit the scope or application of IC chips described herein. Alternative embodiments such as those comprising a single row of bond pads, or more than two rows of bond pads are fully intended as falling within the scope of the embodiments described herein. The advantages are best illustrated with figures as show herewith, wherein:
The support base structure 602 has a plurality of cavities 603 having an appropriate size and shape for receiving respective IC die 501. According to an alternative embodiment, an individual die may be abutted directly against an adjacent die within a single cavity formed in the support base (carrier) structure 602, thereby eliminating the need for individual cavities 603 sized to securely receive a respective die. The die terminations 507 are arranged in dual lines along the center of each IC die (501). The dual-path alignment of die terminations 507 shown in
A first dielectric layer 601 has a plurality of apertures 604 (analogous to 505a), each aperture forming an elongated linear shape configured to provide access to the dual line formation of the die terminations 507 formed on an upper surface of a respective die 501. The apertures, however, may be formed in any shape which will allow for exposure of and access to the die terminations 507. Conductors 605 disposed on the upper surface of the first dielectric layer include narrow conductive trace portions 606b that either terminate at large circular surface region 606a (analogous to 504d of
A plurality of second dielectric (insulating base material) layers 503 have elongated apertures 505b conforming to a shape and location of the arrays of die terminations 507. By making the die terminations accessible through the aligned upper and lower apertures 505b, 604, conductive bond wires can be coupled to respective die terminations during fabrication. A second plurality of electrical conductors 504b are arranged on the surface of the second dielectric layer in a predetermined arrangement to facilitate direct connection between a conductor 504b and its respective die termination 507. The conductors 504b on the plurality of second dielectric layers are also depicted as having a large circular surface region 504d and a narrow conductive trace 504c, as described in
These upper dielectric layers 503 with circuits 504b are shown as individual and discrete circuit structures which are bonded to the base circuit layer 601. According to a first alternative embodiment, a single contiguous dielectric upper layer is disposed atop the lower dialectic layer 601 and secured by appropriate means. According to another alternative embodiment, the upper dielectric layer 503 could be fabricated on the base layer 601 using a build up layer or similar process. Moreover, while the structure of
When the assembly is complete, it may be desirable to remove the support base by a suitable means to reduce the height of the completed assembly at which time an optional thin overmold (not shown) may be applied.
A second (upper) dielectric layer 503 is disposed above the interior dielectric layer, and has a single aperture 504b extending down the center portion of the layer 530. As discussed above, the shape and location of apertures on the respective layers is according to the location of the bond pads and circuit connection points on an IC die to which the various dielectric layers are coupled. The size of the apertures is sufficient to grant access to the bond pads and connection points during fabrication, according to the size of the tools used in fabrication. Circuit paths 504b are disposed on the upper surface of the upper layer 503. The circuit paths include rounded planar surface areas 504d for interconnection with a next level electronic element, and narrow trace sections 504c extending to the periphery of the aperture 504b and oriented in predetermined positions for interconnection with respective terminals on the IC die.
The enlarged view above
Returning briefly to
In
Owing to the limitations of space in
Restating here for emphasis, while the structures illustrated in this disclosure have shown with wire bonds being made to two rows of central bond pads on the IC die, the structures are not so limited and could also be used for created using a single bond pad in the center of the IC die or at the edges of the IC die or combinations thereof.
Although the invention has been described briefly with reference to specific exemplary embodiments thereof, it will be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention as set forth in the appended claims. Moreover, many specific details have been included herein which are not essential to make and use every embodiment of the invention. These details have been included to assist the reader in more easily understanding and comprehending the embodiments described herein. Accordingly, the specification and drawings of this disclosure should be regarded in an illustrative rather than a restrictive sense.
Claims
1-10. (canceled)
11. An electrical assembly comprising:
- a first IC memory package with a first plurality of memory dies including a first memory die, each memory die having an active surface with a plurality of die terminals disposed thereon, the first memory die having a first die terminal in electrical continuity with first and second die bond-pads formed on the active surface.
12. The electrical assembly of claim 11 wherein a surface region of the first die terminal is coextensive with at least part of a surface region of the first die bond-pad.
13. The electrical assembly of claim 11 wherein the first die bond-pad and second die-bond pad are electrically coupled, at least in part, by a signal trace.
14. The electrical assembly of claim 13 wherein the signal trace is formed on the active surface of the first memory die.
15. The electrical assembly of claim 11, the first IC memory package further comprising:
- a first dielectric layer with an active surface having a first plurality of circuit traces disposed thereupon, including a first circuit trace, the first plurality of circuit traces having first and second terminal ends; and,
- a first bond wire with a first end coupled to the first circuit trace and a second end coupled with the first die bond-pad.
16. The electrical assembly of claim 15 further comprising a second wire bond coupling the second die bond-pad to a second circuit trace.
17. The electrical assembly of claim 16 wherein the first dielectric layer comprises a back surface coupled to the active surfaces of the first plurality of memory dies.
18. The electrical assembly of claim 17, wherein the first dielectric layer comprises a first plurality of apertures configured to expose at least some of the die bond-pads on the active surfaces of the first plurality of memory dies.
19. The electrical assembly of claim 18 further comprising a second dielectric layer with an active surface and a back surface, the active surface having a second plurality of circuit traces disposed thereupon, each of the second plurality of circuit traces having first and second ends, wherein the back surface of the second dielectric layer is coupled to the active surface of the first dielectric layer.
20. The electrical assembly of claim 19 wherein the second dielectric layer covers at least a portion of some of the first plurality of signal traces, the second dielectric layer comprising a second plurality of apertures configured in a stair step arrangement with at least some of the first plurality of apertures, and wherein the second plurality of apertures are configured to expose the first end of at least some of the first plurality of circuit traces.
21. The electrical assembly of claim 20 wherein the second plurality of circuit traces includes the second circuit trace.
22. The electrical assembly of claim 20 wherein the first plurality of circuit traces includes the second circuit trace.
23. The electrical assembly of claim 11, wherein the first plurality of memory dies are disposed on a first carrier.
24. The electrical assembly of claim 23 wherein the first carrier comprises a plurality of cavities, and wherein the first memory die is disposed in a first cavity, and the second memory die is disposed in a second cavity.
25. The electrical assembly of claim 23 wherein an edge of a first memory die in the first IC memory package abuts an edge of a second memory die in the first IC memory package.
26. The electrical assembly of claim 11 further comprising:
- a printed circuit board wherein said first IC memory package is mounted on the printed circuit board;
- a plurality of edge connector terminals disposed along at least one edge of the printed circuit board;
- a second IC memory package mounted on the printed circuit board, wherein the first and second IC memory packages are electrically coupled to the edge connector terminals on the printed circuit board.
27. The electrical assembly of claim 26 further comprising:
- an advanced memory buffer mounted on the printed circuit board and electrically coupled to the first and second IC memory packages.
28. An electrical assembly with a first IC memory package, the first IC memory package comprising:
- a first memory die having an active surface with a plurality of die bond pads disposed thereon, including first and second die bond pads
- a first dielectric layer having a back surface disposed against the active surface of the first memory die, and an active surface with a first plurality of circuit traces disposed thereon, including a first circuit trace with first and second terminal ends configured to couple with corresponding conductive members; and,
- a first bond wire with a first end coupled to the first die bond pad and a second end coupled to a first section of the first circuit trace between the first and second terminal ends.
29. The electrical assembly of claim 28, wherein the first dielectric layer comprises a first aperture exposing the first die bond pad and a second aperture exposing the second die bond pad, the first and second apertures being separated by a first dielectric bridge, wherein the first circuit trace spans the first dielectric bridge.
30. The electrical assembly of claim 29, wherein the first memory die comprises two parallel rows of die bond pads, including a third die bond pad adjacent the first die bond pad and exposed by the first aperture, and a fourth die bond pad adjacent the second die bond pad and exposed by the second aperture.
31. The electrical assembly of claim 30, wherein the first plurality of circuit traces further comprises a second circuit trace with first and second terminal ends, the first IC memory package further comprising a second bond wire with a first end coupled with the fourth die bond pad and a second end coupled with a first section of the second circuit trace between the first and second terminal ends.
32. The electrical assembly of claim 31, wherein the second circuit trace spans the first dielectric bridge abreast the first circuit trace.
33. The electrical assembly of claim 32, wherein the first dielectric layer further comprises third and fourth apertures separated by a second dielectric bridge, the third and fourth apertures exposing respective third and fourth die bond pads disposed on the active surface of the second memory die.
34. The electrical assembly of claim 33, wherein the first circuit trace further spans the second dielectric bridge.
35. The electrical assembly of claim 34, the first IC memory package further comprising a second bond wire with a first end coupled to the first circuit trace, and a second end coupled to the third die bond pad.
36. The electrical assembly of claim 29, the first IC memory package further comprising:
- a second dielectric layer with a back surface disposed against the active surface of the first dielectric layer, and an active surface that has a second plurality of conductive circuit traces disposed thereon, including a second circuit trace; and,
- a second bond wire electrically coupled from the second die bond pad to the second circuit trace.
37. The electrical assembly of claim 36, wherein the second dielectric surface comprises a third aperture disposed above, and in stair step relationship with the first and second apertures.
38. The electrical assembly of claim 34, the first IC memory package further comprising a third memory die with an active surface having a plurality of die bond pads, including a fifth die bond pad electrically coupled to the first circuit trace by a wire bond.
39. The electrical assembly of claim 26 wherein the first circuit trace has a first end engaging a first conductive member of a next level electrical component, a second end engaging a second conductive member of a next level electrical component, and wherein the first bond wire is coupled to the first circuit trace between the first and second ends.
40. The electrical assembly of claim 39 wherein the first IC memory package is mounted on a memory card having edge connection terminals, the electrical assembly further comprising:
- an advanced memory buffer mounted on the memory card and electrically coupled with the first IC memory package; and,
- a second IC memory package mounted on the memory card and electrically coupled with the advanced memory buffer.
41. An electrical assembly with a first IC memory package, the first IC memory package comprising:
- a plurality of memory dies including first and second memory dies, each memory die having an active surface that has at least three parallel rows of die bond pads, including first and second outer rows, and a third inner row disposed between the outer rows;
- a first dielectric layer with an active surface that has a first plurality of circuit traces disposed thereon, including first and second circuit traces, wherein the active surface of the first dielectric layer faces the active surface of the first memory die, and wherein a first die bond terminal in the first outer row is coupled to the first circuit trace by a conductive bump, and a second die bond terminal in the second outer row is coupled to the second circuit trace by a second conductive bump.
42. The electrical assembly of claim 41 further comprising a second dielectric layer with a back surface coupled to the first dielectric layer, and an active surface with a second plurality of circuit traces disposed thereon, including a third signal trace.
43. The electrical assembly of claim 42 further comprising a bond wire with a first end coupled to a die bond pad in the third row of die bond pads, and a second end coupled to the third signal trace.
44. The electrical assembly of claim 41 wherein the plurality of memory dies are disposed on a carrier.
45. The electrical assembly of claim 44 wherein the carrier comprises a plurality of cavities, and wherein the first memory die is disposed in a first cavity, and the second memory die is disposed in a second cavity.
46. The electrical assembly of claim 44 wherein an edge of a first memory die in the first IC memory package abuts an edge of the second memory die in the first IC memory package.
47. The electrical assembly of claim 41 wherein the first IC memory package is mounted on a memory card having edge connection terminals, the electrical assembly further comprising:
- an advanced memory buffer mounted on the memory card and electrically coupled with the first IC memory package; and,
- a second IC memory package mounted on the memory card and electrically coupled with the advanced memory buffer.
Type: Application
Filed: Dec 15, 2008
Publication Date: Apr 9, 2009
Inventor: Joseph Charles Fjelstad (Maple Valley, WA)
Application Number: 12/335,372
International Classification: H01L 23/48 (20060101); H01L 23/58 (20060101);