The invention relates to semiconductor structures and, more particularly, to methods and structures for packaging identically processed chips in a stacked structure.
Constant improvements in the integration density of various electronic components (e.g., transistors, diodes, resistors, capacitors, etc.) have resulted from repeated reductions in minimum feature size. This, in turn, has allowed more components to be integrated into a given chip area. Although improvements in lithography techniques has resulted in considerable size reductions, physical limitations to the density remains a barrier to further improvements. For example, as the component size is reduced and more devices are placed on a single chip, design complexities arise, including, for example, a significant increase in the number and length of interconnections between devices. Also, it is known that an increase in the number and length of interconnections results in both circuit RC delay and power consumption increase.
To solves these issues, stacked dies (chips) are commonly used to increase chip density. In the stacked chip configuration, it is preferred that processed chips have exactly the same design, and be fabricated using a same set of masks in order to increase fabrication efficiency and reduce manufacturing and mask costs. However, since each chip needs to have a set of unique addresses, it becomes difficult to distinguish different chips from each other. For this reason, for example, it has now been recognized that identical memory chips cannot be simply stacked one on top of the other. Instead, a considerable amount of customization is required, which increases fabrication costs. Illustratively, customization requires different mask sets, which results in significant additional costs to the fabrication process.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.
In an aspect of the invention, a latch chain comprises a first latch chain, comprised of a single or multiple latches, associated with a first chip. The first latch chain is structured to read data information from the first chip. The latch chain further comprises a second latch chain, comprised of a single or multiple latches, associated with a second chip. The second latch chain is structured to read data information from the second chip. The first latch chain and the second latch chain are connected to one another such that they form a single latch chain that crosses chip boundaries. The first latch chain and the second latch chain are structured to provide identification information for identifying the first chip and the second chip, respectively.
In an aspect of the invention, a structure comprises a plurality of chips provided in a stacked configuration and each having connections which, when the plurality of chips are stacked, are oriented to permit non-shared, individual signal connections with a solder bump or other type of electrical connection.
In an aspect of the invention, a method comprises independent addressing of identical integrated chips in a through-silicon-via chip stack, which occurs after chip stacking.
In another aspect of the invention, a design structure tangibly embodied in a machine readable storage medium for designing, manufacturing, or testing an integrated circuit is provided. The design structure comprises the structures of the present invention. In further embodiments, a hardware description language (HDL) design structure encoded on a machine-readable data storage medium comprises elements that when processed in a computer-aided design system generates a machine-executable representation of the chip connections, which comprises the structures of the present invention. In still further embodiments, a method in a computer-aided design system is provided for generating a functional design model of the chip connections. The method comprises generating a functional representation of the structural elements of the chip connections.
The present invention is described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention.
The invention relates to semiconductor structures and, more particularly, to methods and structures for packaging identically processed chips in a stacked structure. More specifically, the present invention includes methods and structures for differentiating and controlling individual identical chips in a stacked structure. For example, in embodiments, the present invention includes a post stacked latch chain structure that assembles through through-silicon-vias (TSV). The post stacked latch chain structure allows for post stack address programming (per chip) and additional addressing options. In another approach, patterns for solder bump connections (e.g., C4 connections) or other types of electrical connections between chips such as copper to copper bonds, or intermetallic bonds, are provided in a specific sequence which allows for a four high chip stack by rotating and/or flipping each overlaying chip. Hybrid versions of the rotation technique along with positional self identification is also contemplated by the present invention.
Advantageously, the present invention provides structures that allow for 100% identically processed chips (e.g., memory, processor, ASICS, Test Vehicles, etc.) to be stacked and differentiated. Customization costs can now be avoided, considerably reducing fabrication and design costs. For example, by implementing the methods and structures of the present invention, additional customized masks are no longer required in the processing, thus considerably reducing mask and manufacturing costs.
More specifically, the stacked latch chain structure 100 includes a plurality of identically processed chips 200, 300, etc., provided in a stacked configuration, each having a plurality of latches 130a, 135a, e.g., two or more latches, that read information from shared data pins 110, e.g., clock pin, load pin, set pin and reset pin. In the embodiment shown in
In embodiments, the pins 110 can be any type of data pin which provides discrete address information, control and/or functionality to the chips in the stack. For example, the pins 110 can include a clock pin, load pin, set pin and reset pin. The stacked chips 200, 300 also include control pins, i.e., A0 pin and A1 pin. In embodiments, the plurality of latches 130a, 135a, e.g., two or more latches, read information from the data pins 110, e.g., clock pin, load pin, set pin and reset pin. For example, the clock pin provides a clock value, and triggers the load pin and the set pin. The load pin loads the information into the latches 130a, 135a; whereas, the set pin sets the data information into the latches 130a, 135a. The reset pin can reset the values in the latches 130a, 135a.
The latches 130a, 135a are also connected to data pins 125, which permit data to be serially loaded into the latches 130a, 135a across all the chips 200, 300 . . . n, in the stack. In this way, the latches 130a, 135a form a latch chain that crosses chip boundaries capable of identifying each chip in the stack by using address information obtained from the pins 110, themselves. This allows the structure and method of the present invention to identify each chip, post assembly, and hence discretely control each chip.
In embodiments, the latches 130a, 135a provide pin data (e.g., address information) to storage structures 130b, 135b, respectively. In embodiments, the storage structures 130b, 135b are non-volatile memory or fuses, structured to store each clock value of each pin connection for each chip. For example, the storage structures 130b, 135b can store address information for each pin for each chip. In this way, upon power up, it is possible to read values stored in the storage structures 130b, 135b, for discrete identification and control of the individual chips in a stack.
More specifically, in operation, the post stacked latch chain structure 100 allows serially loading of data into the latches 130a, 135a across all the chips 200, 300 in the stack. The latch storage structures 130b, 135b, e.g., non-volatile memory, can be hard set with the pin data. This pin data can then be compared against two address bits (A0, A1) that make up a chip enable signal. If there is a match with the two address bits (A0, A1), the command enable circuit 400 will provide a control signal to the identified chip in the stack.
It is also possible to reset the latches 130a, 135a, any time, in order to place all the chips into a global command mode (same commands to all chips), or to reload the storage structures 130b, 135b at any time to put the chips into a specific addressable mode. Additionally, normal operation would have the storage structure 130b, 135b set to sequential addresses, and the user to occasionally reset the latches 130a, 135a to address all chips together and/or soft load the latches 130a, 135a to address two or more chips at a time. This scheme works with stacks of any number of chips with no limit (e.g., limit would be the depth of latches and addresses in the silicon design).
More specifically,
In the grid pattern configuration of
In the grid pattern configuration of
In the grid pattern configuration of
In the grid pattern configuration of
In the embodiment of
Design flow 900 may vary depending on the type of representation being designed. For example, a design flow 900 for building an application specific IC (ASIC) may differ from a design flow 900 for designing a standard component or from a design flow 900 for instantiating the design into a programmable array, for example a programmable gate array (PGA) or a field programmable gate array (FPGA) offered by Altera® Inc. or Xilinx® Inc.
Design process 910 preferably employs and incorporates hardware and/or software modules for synthesizing, translating, or otherwise processing a design/simulation functional equivalent of the components, circuits, devices, or logic structures shown in
Design process 910 may include hardware and software modules for processing a variety of input data structure types including netlist 980. Such data structure types may reside, for example, within library elements 930 and include a set of commonly used elements, circuits, and devices, including models, layouts, and symbolic representations, for a given manufacturing technology (e.g., different technology nodes, 32 nm, 45 nm, 90 nm, etc.). The data structure types may further include design specifications 940, characterization data 950, verification data 960, design rules 970, and test data files 985 which may include input test patterns, output test results, and other testing information. Design process 910 may further include, for example, standard mechanical design processes such as stress analysis, thermal analysis, mechanical event simulation, process simulation for operations such as casting, molding, and die press forming, etc. One of ordinary skill in the art of mechanical design can appreciate the extent of possible mechanical design tools and applications used in design process 910 without deviating from the scope and spirit of the invention. Design process 910 may also include modules for performing standard circuit design processes such as timing analysis, verification, design rule checking, place and route operations, etc.
Design process 910 employs and incorporates logic and physical design tools such as HDL compilers and simulation model build tools to process design structure 920 together with some or all of the depicted supporting data structures along with any additional mechanical design or data (if applicable), to generate a second design structure 990.
Design structure 990 resides on a storage medium or programmable gate array in a data format used for the exchange of data of mechanical devices and structures (e.g. information stored in a IGES, DXF, Parasolid XT, JT, DRG, or any other suitable format for storing or rendering such mechanical design structures). Similar to design structure 920, design structure 990 preferably comprises one or more files, data structures, or other computer-encoded data or instructions that reside on transmission or data storage media and that when processed by an ECAD system generate a logically or otherwise functionally equivalent form of one or more of the embodiments of the invention shown in
Design structure 990 may also employ a data format used for the exchange of layout data of integrated circuits and/or symbolic data format (e.g. information stored in a GDSII (GDS2), GL1, OASIS, map files, or any other suitable format for storing such design data structures). Design structure 990 may comprise information such as, for example, symbolic data, map files, test data files, design content files, manufacturing data, layout parameters, wires, levels of metal, vias, shapes, data for routing through the manufacturing line, and any other data required by a manufacturer or other designer/developer to produce a device or structure as described above and shown in
The method as described above is used in the fabrication of integrated circuit chips. The resulting integrated circuit chips can be distributed by the fabricator in raw wafer form (that is, as a single wafer that has multiple unpackaged chips), as a bare die, or in a packaged form. In the latter case the chip is mounted in a single chip package (such as a plastic carrier, with leads that are affixed to a motherboard or other higher level carrier) or in a multichip package (such as a ceramic carrier that has either or both surface interconnections or buried interconnections). In any case the chip is then integrated with other chips, discrete circuit elements, and/or other signal processing devices as part of either (a) an intermediate product, such as a motherboard, or (b) an end product. The end product can be any product that includes integrated circuit chips, ranging from toys and other low-end applications to advanced computer products having a display, a keyboard or other input device, and a central processor.
The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims, if applicable, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. Accordingly, while the invention has been described in terms of embodiments, those of skill in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.
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