Stacked chip system

[0001] The present invention relates to a stacked chip system and particularly to a stacked chip system using through-silicon vias.

[0002] To save precious layout space or increase interconnection efficiency, multiple chips of integrated circuits (ICs) can be stacked together as a single IC package. To that end, a three-dimensional (3D) stack packaging technology is used to package the chips of integrated circuits. Through-silicon vias (TSVs) are widely used to accomplish the 3D stack packaging technology. A through-silicon via is a vertical conductive via completely passing through a silicon wafer, a silicon board, a substrate of any material or die. Nowadays, the 3D integrated circuit (3D IC) technology is applied to a lot of fields such as memory stacks, image sensors or the like.

[0003] Usually manufacturing a single chip of integrated circuits involve more than several hundred steps and failure of one of the steps or a tiny particle on the chip would destroy the chip. Applying 3-D integrated circuit (3D IC) technology does not make this situation better but worse due to much more extra steps needed, so there is a need to increase the fault tolerance of a chip thereby increasing the yield of a wafer.

[0004] A stacked chip system is provided to comprise a first chip, a second chip, a first group of through silicon vias (TSVs) connecting the first chip and second chip and comprising at least one first VSS TSV, at least one first VDD TSV, a plurality of first signal TSVs and at least one first redundant TSV and a second group of through silicon vias (TSVs) connecting the first chip and second chip and comprising at least one second VSS TSV, at least one second VDD TSV, a plurality of second signal TSVs and at least one second redundant TSV, wherein all the first group of TSVs are coupled by a first selection circuitry configured to select the at least one first redundant TSV and bypass at least one of the rest of the first group of TSVs, and wherein the at least one first redundant TSV and the at least second redundant TSV are coupled by a second selection circuitry configured to allow one of them to replace the other.

[0011] The following is the detailed description of the preferred embodiments of this invention. All the elements, sub-elements, structures, materials, arrangements recited herein can be combined in any way and in any order into new embodiments, and these new embodiments should fall in the scope of this invention defined by the appended claims. A person skilled in the art, upon reading this invention, should be able to modify and change the elements, sub-elements, structures, materials, arrangements recited herein without being apart from the principle and spirit of this invention. Therefore, these modifications and changes should fall in the scope of this invention defined only by the following claims.

[0012] There are a lot of embodiments and figures in this application. To avoid confusions, similar components are represented by same or similar numerals. To avoid complexity and confusions, only one of the repetitive components is marked. Figures are meant to deliver the principle and spirits of this invention, so the distance, size, ratio, shape, connection relationship, etc. are examples instead of realities. Other distance, size, ratio, shape, connection relationship, etc. capable of achieving the same functions or results can be adopted as equivalents.

[0013] FIG. 1 shows a schematic view of a stacked chip system operating in normal mode in accordance with an embodiment of the present invention. System 500 comprises chips, chip 1 and chip 2, (or dies if they are not separated from their wafers yet) stacked together and multiple through-silicon vias (TSVs) coupling these two chips in electrically connection. TSV 11, TSV 12, TSV 13 . . . TSV 1n and TSV 1R forms a first TSV group and they may all physically embedded within the chip 1 or chip 2. It is noted that the first group of TSVs should comprise at least one VSS TSV (one of TSV 11-TSV 1n), at least one VDD TSV (another one of TSV 11-TSV 1n), some signal TSVs (the rest of TSV 11-TSV 1n) and at least one redundant TSV (TSV 1R). VSS TSV is configured to couple operation voltage VSS (in most cases VSS can be electrical ground, but in some cases VSS is a voltage less than VDD in strength) to the integrated circuits (not shown) in the chip 2; VDD TSV is configured to couple positive operation voltage (VDD) to the integrated circuits (not shown) in the chip 2; and signal TSVs are configured to relay operational signals such as clock signal to the integrated circuits in the chip 2. In FIG. 1, chip 1 is the signal input side and chip 2 is the signal output side. However, the present invention is not limited thereto as long as one of chip 1 and chip 2 is the signal input side and the other one of chip 1 and chip 2 is the signal output side.

[0014] The system 500 also comprises multiple multiplexers (hereafter referred to as mux/muxes) within the chip 1 (mux 112, mux 113, mux 114 . . . mux 11n and mux 11R), multiple multiplexers within the chip 2 (mux 211, mux 212, mux 213 . . . mux 21n and mux 21R), multiple buffers within the chip 1 (buffer 111, buffer 112, buffer 113 . . . buffer 11 (n−1) and buffer 11n) and multiple buffers within the chip 2 (buffer 212, buffer 213, buffer 214 . . . buffer 21n and buffer 21R). These TSVs, muxes and buffers route signal pathes and get the input signals (input 111, input 112, input 113 . . . input 11n) to cross the chip boundary and become output signals (output 211, output 212, output 213 . . . output 21n) respectively. It is noted that the muxes within chip 1 and chip 2 are controlled either by internal or external logic. Furthermore, for the two digits following a symbol such as TSV 11, the first digit represents its group and the second digit represents its position/order within the group; the second digit starts from one. TSV 1n means this TSV is the n^th TSV in the first TSV group; TSV 1R means this TSV is the redundant TSV in the first TSV group. For the three digits following a symbol such as mux 113, the first digit represents its chip, the second digit represents its group and the third digit represents its position/order within the group; the third digit starts from one.

[0015] Still refer to FIG. 1, which shows the signal pathes (shown by thick dashed line - - - ) when all the TSVs are valid. Input 111 would go through TSV 11 and mux 211 and become output 211; input 112 would go through mux 112, TSV 12 and mux 212 and become output 212 . . . input 11n would go through mux 11n, TSV 1n and mux 21n and become output 21n. In this case, all the buffers, mux 11R, TSV 1R and mux 21R are not used.

[0016] Now refer to FIG. 2, which shows a schematic view of a stacked chip system operating in defected mode in accordance with an embodiment of the present invention. In FIG. 2, the TSV 12 marked by a big “X” is invalid and can not be used to relay signal from chip 1 to chip 2. The muxes controlled by either internal or external logic would create new signal paths (shown by thick dashed line . . . ) to bypass the invalid TSV 12, select the redundant TSV 1R and reroute the input signals to where they supposed to arrive. In this case, input 111 still goes through TSV 11 and max 211 as usual but all other inputs (input 112, input 113 . . . input 11n) would be “shifted” to the next mux in chip 1 and goes through the next TSV. For example, input 112 would go through buffer 112, mux 113, TSV 13, buffer 213 and mux 212 and become output 212; input 113 would go through buffer 113, mux 114, TSV 14, buffer 214 and mux 213 and become output 213 . . . input 11n would go through buffer 11n, mux 11R, TSV 1R, buffer 21R and mux 21n and become output 21n.

[0017] Now refer to FIG. 3, which shows a schematic top view of a group of through-silicon vias (TSVs) in accordance with an embodiment of the present invention. The first group of TSVs is an example of one of the groups of TSVs. Each group of TSVs may form an array (3×3 array in FIG. 3 and the redundant TSV may be placed in the center of this array. In this case, TSV li can be on of TSV 11, TSV, 12 . . . TSV 18 and it could be a VSS TSV, a VDD TSV or a signal TSV. Refer to FIGS. 1-3, that means n is equivalent to 8. However, the present invention is not limited thereto, the array may be bigger (4×4, 3×4 . . . , that is having more TSVs) or smaller (2×2, 2×3 . . . , that is having less TSVs) as long as each array comprises at least one VSS TSV, at least one VDD TSV, at least one signal TSV and at least one redundant TSV.

[0018] Now refer to FIG. 4, which shows a schematic top view of a chip comprising multiple groups of through-silicon vias (TSVs) in accordance with an embodiment of the present invention. As shown in FIG. 4, the chip 1 or chip 2 may comprise multiple groups of TSVs. Although these groups of TSVs are in the same size (all 3×3 arrays, that is having same amount of TSVs), the present invention is limited thereto. These groups of TSVs may have different sizes (that is having different amount of TSVs) as long as they can be arranged within the same chip without breaking design rule or causing manufacturing problems.

[0019] Now refer to FIG. 5, which shows a schematic view of a stacked chip system in accordance with another embodiment of the present invention.

[0020] System 600 shown in FIG. 5 is very similar to the system 500 shown in FIGS. 1 and 2. Unlike system 500 connecting all the TSVs within the same group by muxes and buffers, system 600 connects all the redundant TSVs from different groups (TSV 1R from the first group, TSV 2R from the second group, TSV 3R from the third group . . . TSV mR from the M^th group) together in the same way, so they can back up each other.

[0021] According to the present invention, the yield of stacked chip system can be improved by adding extra redundant TSVs and some control logic into one or both of the chips. By doing so, the redundant TSVs can replace invalid TSVs to deliver the complete functions.

[0022] While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.