Abstract:
A semiconductor memory device architecture and method thereof obtains a high data bandwidth by forming multiple input/output lines. A unit array has a plurality of reference blocks formed in a length direction of the device, each reference block storing a plurality of memory cells. A sub array has a plurality of unit arrays formed in a longitudinal direction perpendicular to the length direction. A word line selects memory cells from within the reference blocks, the word line extending in the length direction. A pair of bit lines and a pair of data input/output lines extend in the longitudinal direction. The pair of data input/output lines are correspondingly connected to 2 n  (n=1,2, . . . ) pairs of bit lines. A read select signal line selects a pair of bit lines from among 2 n  pairs of bit lines connected to one pair of data input/output lines in response to an input of a column address during a read operation. A write select signal line selects a pair of bit lines from among 2 n  pairs of bit lines connected to one pair of data input/output lines in response to an input of a column address during a write operation. A column gate connects the pair of bit lines to the pair of data input/output lines. A column select line extends in the longitudinal direction and controls the column gate, and a pair of main data input/output lines are connected correspondingly through a multiplexer to a plurality of data input/output lines.

Description:
This is a division of application Ser. No. 08/352,090, filed Nov. 30, 1994, U.S. Pat. No. 5,537,346. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a semiconductor memory, and more particularly, to a semiconductor memory device having a high bandwidth and a signal line layout method thereof by achieving a chip architecture formed with multiple input/output lines. 
     2. Description of Related Art 
     An important consideration in semiconductor memory design is to select an appropriate architecture. Parameters indicative of the performance of a semiconductor memory are, for example, power consumption, speed, size and the like are typically determined by the architecture. Therefore, the more flexible the chip architecture is, the more the parameters of the semiconductor memory are satisfied sufficiently. Flexibility of a semiconductor memory means that a basic frame can be maintained even though a peripheral circuit is altered or added and the degree of integration increases. Flexibility also means that these variations can occur easily. 
     Current trends in the industry are the pursuit of both high bandwidth as well as high integration. Furthermore, new memory devices having bandwidth capable of synchronizing with a high system speed instead of with only a simple highly integrated memory device are being developed. There is a need for memory devices in a class with an integrated degree of over 64 Megabit (64 Mb), in particular RAMBUS dynamic RAM or synchronous dynamic RAM having a mother version of 256 Mb dynamic RAM for example, to process 256 data bits in one operating cycle. 
     In order to satisfy the needs of the industry for memory devices to have a high bandwidth, the architecture of a memory device to be used as mother version of 256 Megabit class should have an internal bandwidth of about 256 bits (one cycle). Currently, the industry designs to satisfy this need are trending toward the development of an architecture which increases the internal bandwidth. Meanwhile, as the degree of integration is raised, the size of a memory chip becomes larger and the loading of each signal line increases. Hence, there are difficulties in reading and writing data. 
     FIG. 1 illustrates the architecture of 256 Mb memory published in various papers. The configuration of an internal column related circuit based on the architecture shown in FIG. 1 is disclosed in, for example, U.S. Pat. No. 5,247,482, entitled &#34;Semiconductor Memory Device With High Speed Write Operation&#34;. When a typical folded bit line structure is adopted, 32K word lines and 16K bit lines are needed to achieve a 256 Mb dynamic RAM. Although not excluding a technique for connecting 512 cells to one bit line in the future, since 256 cells per bit line are generally connected, a 2M array is activated by one word line. Assuming that a refresh cycle is 16K, 2 word lines are enabled in the length direction of a chip by the activation of a row address strobe signal RAS and 8M array is activated in 256 Mb. If the activation is performed as shown in FIG. 1 and two pairs of input/output lines are positioned at a sense amplifier region, the number of data obtained in 2M array is 4 which corresponds to the number of input/output lines. Therefore, 16 data bits are obtained in a 256 Mb device. Since 16 data bits are far fewer than are necessary to achieve an internal bandwidth of 256 bits, it is difficult to obtain a high bandwidth with this architecture. Furthermore, since the line loading of an input/output line and junction loading of gate transistors connecting the input/output line to a bit line is large, a voltage of the input/output line during a read operation is not readily developed. During a write operation, the loading of the input/output line is similarly large and the write operation is performed through a gate transistor of an input/output line in the same way as with the read operation. However, because a data input/output line shown in FIG. 1 is directly connected to the bit line through the gate transistor, the input/output line deteriorates the junction loading and the bit line. Therefore, it has been appreciated by the present inventors that the architecture shown in FIG. 1 is not suitable for a highly integrated memory device having a high bandwidth. 
     FIG. 2 illustrates another example of the architecture of a semiconductor memory which has reduced line loading and higher data bandwidth as compared with that of FIG. 1. The architecture of FIG. 2 is described in 1991 SYMPOSIUM ON VLSI CIRCUITS, entitled &#34;Circuit Techniques for a Wide Word I/O Path 64 Mega DRAM&#34;, pp. 133-134. In FIG. 2, the loading of an input/output line is reduced by the use of a sub input/output line and a local input/output line. Data is transmitted to the local input/output line through a differential amplifier stage by incorporating a predetermined number of sense amplifiers into the sub input/output line. During a write operation, with the architecture of FIG. 2, many NMOS transistors have data transmitted thereby. 
     FIG. 3 illustrates the path of data input/output in the architecture of FIG. 2. During a write operation, data on the local input/output line is transmitted to transistor 2 by an enable select signal SEC SELECT having column information of a selected block. When a write enable signal YWRITE, which determines the sub input/output line, is enabled, data is transmitted to the sub input/output line through transistor 4. When a bit line information signal S/A SELECT is enabled to select bit lines connected to one sub input/output line, data is transmitted to the corresponding bit line through transistor 10. Consequently, data from the input/output line to the bit line must be transmitted via as many as three NMOS transistors 2, 4, 10 during a write operation. Thus, the architecture of FIG. 2 of a highly integrated memory device with large line loading is disadvantageous. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide an architecture of a semiconductor memory device and a method for signal line layout thereof which achieves a high bandwidth. 
     It is another object of the present invention to provide an architecture of a semiconductor memory device and a method for signal line layout thereof which achieves device performance having a high speed data access operation during read and write operations. 
     It is still another object of the present invention to provide an architecture of a semiconductor memory device and a method for signal line layout thereof which suppresses sufficiently the otherwise disadvantageous effects of line loading based on a bit line and an input/output line during data transmission. 
     It is a further object of the present invention to provide an architecture of a semiconductor memory device and a method for signal line layout thereof which achieves a high bandwidth and performs a high speed write operation without additional local input/output lines connecting a bit line to a main input/output line. 
     To achieve these and other objects, the present invention provides a semiconductor memory device with an architecture which obtains a desired high bandwidth. 
     A semiconductor memory according to the present invention has an architecture wherein a plurality number of memory cells and a bit line conveying cell data are independently connected to a corresponding input/output line in response to a selection of a word line, thus obtaining a high bandwidth. 
     A semiconductor memory device according to the present invention includes a row decoder arranged such that a word line is formed in the length direction of a chip and a column decoder is arranged such that a bit line and a column select line are formed at right angles with the length direction. 
     A semiconductor memory device according to the present invention has an architecture wherein a main input/output line is correspondingly connected to a plurality of data input/output lines one by one and is provided between a bit line and a data input/output line terminal of a chip. 
     In accordance with one aspect of the present invention, a semiconductor memory device includes a memory cell array having a plurality of reference blocks each storing a plurality of memory cells. A word line extends in the length direction of a chip, and a pair of bit lines have a bit line and a complementary bit line. The pair of bit lines extend in a longitudinal direction perpendicular to the length direction. A pair of data input/output lines have a data input/output line and a complementary data input/output line, the pair of data input/output lines extending in the longitudinal direction, are correspondingly connected to a plurality of bit lines, and are formed over the memory cell array. A column select line extends in the longitudinal direction, is adjacent to the pair of data input/output lines, and controls the connection between the pair of bit lines and the pair of data input/output lines. 
     In accordance with another aspect of the present invention, a signal line layout method of a semiconductor memory device includes the step of forming a memory cell array by arranging a plurality of reference blocks for respectively storing a plurality of memory cells in the form of matrix. A word line is formed for selecting a row of the memory cells to be extended in the length direction of a chip. A pair of bit lines are formed for selecting a column of the memory cells to be extended in a longitudinal direction perpendicular to the length direction. The pair of bit lines have a bit line and a complementary bit line and form a pair of data input/output lines over the memory cell array. The pair of data input/output lines are arranged to be extended in the longitudinal direction, and are correspondingly connected to a plurality of bit lines. The pair of data input/output lines have a data input/output line and a complementary data input/output line. A column select line is formed adjacent to the pair of data input/output lines in the longitudinal direction to control the connection between the pair of bit lines and the pair of data input/output lines. 
     A semiconductor memory device and signal line array method and architecture according to the present invention achieves a high bandwidth memory device. Moreover, layout according to the architecture of the present invention is facilitated in the column direction as well as in the row direction. Since only two data input/output lines for transmitting data are needed between a cell array and an input/output stage of a chip, the layout is improved and a high integration is easily obtained. Furthermore, line loading problems exhibited by conventional architectures are minimized. In particular, bandwidth is increased by adjusting connecting methods between the bit line and the data input/output line, and between the data input/output line and the main data input/output line. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The advantages and features of the present invention will become more apparent from the detailed description herein, with reference to the attached drawings in which like reference characters generally refer to the same parts throughout the views, wherein: 
     FIG. 1 is a schematic diagram showing an example of a conventional chip architecture of a semiconductor memory; 
     FIG. 2 is a circuit diagram showing another example of a conventional architecture of a data input/output line of a semiconductor memory; 
     FIG. 3 is a schematic block diagram showing a data input/output path of the conventional architecture of FIG. 2; 
     FIGS. 4A to 4D are diagrams showing a chip architecture with multiple input/output lines of a semiconductor memory according to the present invention; 
     FIG. 5 is a diagram showing an example of the layout of a data input/output line and a column select line in the device of FIGS. 4A and 4B; 
     FIG. 6 is a partial, more detailed circuit diagram of a column related circuit constructed in accordance with the device architecture of FIGS. 4A and 4B; 
     FIGS. 7A and 7B are timing charts showing read and write operations of the bit line sensing circuit of FIG. 6; 
     FIG. 8 is a schematic block diagram showing a data input/output path of circuit of FIG. 6; 
     FIG. 9 is a block diagram showing a multiplexer of the device of FIGS. 4A and 4B; 
     FIG. 10 is a circuit diagram showing a unit multiplexer 60 constituting a multiplexer of FIG. 9; and 
     FIG. 11 is a circuit diagram showing a circuit for generating a signal φIOPP applied to a multiplexer of FIG. 10. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     In the following description, specific details such as a vertical structure of an input/output line, a bit line sensing circuit, a multiplexer, etc. are provided in order that the present invention may be thoroughly understood. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without these specific details. 
     In the preferred embodiment of the present invention, a &#34;unit array&#34; or &#34;unit memory cell array&#34; represents a memory cell array which can be activated by one word line. A &#34;sub array&#34; means a cell array which can be selected by one row decoder group and one column decoder group and consists of a plurality of unit arrays sharing a data input/output line connected to one multiplexer group. 
     FIGS. 4A and 4B illustrate a chip architecture having multiple input/output lines of a semiconductor memory according to the present invention. FIGS. 4A and 4B are laterally constructed in parallel on the same chip. FIGS. 4A and 4B show the architecture of a memory device constructed in accordance with the present invention, for example, a 256 Mega DRAM. 
     Two banks of memory are shown at the upper and bottom portions of FIGS. 4A and 4B, respectively. Reference numerals 22, 12 designate a sub array and a unit array, respectively. Two sub arrays 22 exist in one bank and sixteen unit arrays 12 exist in one sub array 22. One unit memory cell array 12 consists of 2M (M=2 20 ) bits and one sub array 22 consists of 32M bits (=2M×16). Hence, one bank has 64M bits. A row decoder (R/D) 18 (64M bits are partitioned into two groups of 32M bits each with the row decoder) extends in the length direction of a chip and a memory and is activated in the length direction of the chip, i.e. in the direction of a word line. Therefore, the activation is carried out in the length of the chip by the unit array which exists in the identical line. 
     A bit line, data input/output line and column select line are positioned at right angles with the direction of the word line. In two sub arrays 22 which are adjacent to each other within one bank of FIGS. 4A and 4B, one side of the sub array 22 illustrates a data input/output line IO and the other side thereof shows a column select line CSL in order to avoid the confusion of structures of the data input/output line IO and column select line CSL. Data input/output lines IO and column select lines CSL exist within one sub array 22 as many as the indicated number. To reduce signal interference, it is preferable to form the column select lines so as not to directly adjoin each other, and to form the data input/output lines IO and IO so as not to directly adjoin each other. The architecture shown in FIGS. 4A and 4B is advantageous over the conventional architecture because there is no need to provide local data input/output lines as shown in the conventional architecture of FIG. 2 to extract data simultaneously. Thus, using the architecture of the present invention, a high speed write operation is possible. 
     The unit array 12 constitutes a basic block of the sub array 22 of 32Mbits consisting of 16 blocks of 128Kbits, each consisting of 512 word lines and 512 bit lines (256 pairs of bit lines). Hence, 4096 (256 columns×16) pairs of bit lines exist within one unit array 12. When performing a refresh in units of 16Kbits, one word line and arrays of 2Mbits are activated from one bank of 64M. 
     The number of data input/output lines within 2M bits is now described. If 2 n  pairs of bit lines are connected to one data input/output line, there are 4096/2 n  (=2 m ) pairs of input/output lines. When incorporating the data input/output lines into a multiplexer 20, 2 k  main data input/output lines MIO (consisting of pairs) are obtained. That is, by the activation of a row address strobe signal RAS, 4096/2 n  (=2 m ) data input/output lines and 2 k  main data input/output lines are obtained within 2M, and 2 k  ×4 data bits are obtainable within 256M. 
     For example, if 8 pairs of bit lines are connected to one data input/output line, there are 512 pairs of data input/output lines. If 8 pairs of data input/output lines are grouped into one main data input/output line MIO, 64 pairs of main input/output lines MIO are obtained. Therefore, if there are 64 pairs of main input/output lines with respect to one sub array 22, 256 data bits are obtained in a 256Mbit device. Thus, if it is necessary to increase the number of bits, the architecture according to the present invention has flexibility which allows adjustment of the number of bit line pairs connected to the data input/output line and the number of data input/output line pairs connected to the main data input/output line. 
     To facilitate a better understanding of the architecture of FIGS. 4A and 4B, FIG. 5 illustrates an example of a layout of a data input/output line and a column select line of FIGS. 4A and 4B. The column select line CSL is positioned between the data input/output lines IO and IO and this layout is repeated on the same chip as shown in FIG. 5. Referring again to FIG. 2, since the bit line information signal S/A SELECT needs one line with respect to each bit line, even if it is arranged in the different direction from the data input/output line, and the signal lines SEC SELECT having the column information, YREAD and YWRITE are needed in the same direction. In other words, 2 data input/output lines, one signal line SEC SELECT, and one signal line YREAD or YWRITE are needed. In order to obtain high bandwidth, many data input/output lines are required. Hence, the basic structure of at least 4 lines is repeatedly disposed and the area occupied by a chip becomes larger. However, since the data input/output line and column select line of FIG. 5 consisting of the basic structure of 3 lines are repeatedly positioned on an array, the area occupied by the chip can be reduced. Further, since the layout is positioned over the array, the data input/output line of the necessary amount for high bandwidth is sufficiently inserted. Furthermore, since the column select line is positioned between data input/output lines and column select lines are not adjacent to each other, the coupling which may be generated between data input/output lines IO and IO is suppressed. Meanwhile, in the same substrate, there are layers to which a bit line and a word line are contained, respectively, between a layer to which the data input/output lines IO and IO and the column select line CSL are contained and a substrate, as indicated in FIG. 5. The bit line is formed in the direction of the data input/output lines IO and IO and the column select line CSL. The word line is formed at right angles with the data input/output lines IO and IO and the column select line CSL. In FIG. 5, although the data input/output lines IO and IO and the column select line CSL are repeatedly arranged with a basic structure of 3 lines such as &#34;IO-CSL-IO&#34;, other modifications such as &#34;IO-CSL-IO&#34; and &#34;IO-IO-CSL&#34; are possible. 
     FIG. 6 is a circuit diagram showing a column related circuit of FIGS. 4A and 4B based on the architecture of FIGS. 4A and 4B, i.e. a bit line sensing circuit. A bit line sensing circuit 24 indicated by a dotted line performs a bit line sensing operation. A P-type sense amplifier 32 and an N-type sense amplifier 34 are formed between bit lines BL and BL and amplifies data conveyed on the bit line (also referred to in the art as &#34;developing data on the bit line&#34;). A first write transistor 36 has a gate connected to a write select signal WS and a drain connected to data input/output line IO. A second write transistor 38 has a gate connected to a column select signal CSL. Column select line and column select signal have equivalent meaning and are both referred to as CSL herein. A channel connected between a source of the first write transistor 36 and a bit line BL. A discharge transistor 40 has a gate connected to the column select signal CSL and a source connected to a ground voltage terminal GND. A third write transistor 42 has a gate connected to a write select signal WS and a drain connected to a data input/output line IO. A fourth write transistor 44 has a gate connected to the column select signal CSL and a channel connected between a source of the third write transistor 42 and the bit line BL. A first read transistor 46 has a gate connected to the bit line BL and a source connected to a drain of the discharge transistor 40. A second read transistor 48 has a gate connected to a read select signal RS and a channel connected between the drain of the first read transistor 46 and the data input/output line IO. A third read transistor 50 has a gate connected to the bit line BL and a source connected to the drain of the discharge transistor 40. A fourth read transistor 52 has a gate connected to the read select signal RS and a channel connected between the drain of the third read transistor 50 and the data input/output line IO. 
     In FIG. 6, a memory cell 26 selected by activation of the word line WL is provided. A first equalizing circuit 28I for equalizing the left bit lines BL and BL, first separate transistors 30I for separating the left bit lines BL and BL, a second equalizing circuit 28J for equalizing the right bit lines BL and BL, and second separate transistors 30J for separating the right bit lines BL and BL are provided. The lines for the read select signal RS and the write select signal WS are extended at right angles with the data input/output lines IO and IO or the column select line CSL, i.e., in the same direction as the word line. Control signals φEQI, φISOI, LA, LA, φISOJ and φEQJ are described in Korea Patent Application No. 92-12436, entitled &#34;Row Redundancy Circuit Sharing A Fuse Box&#34;, filed Jul. 13, 1992. The bit line sensing circuit 24 illustrated in FIG. 6 may be practiced by other circuits according to the chip architecture of FIGS. 4A and 4B. 
     The sensing operation of the bit line sensing circuit 24 of FIG. 6, i.e. the read and write operations of cell data, is now described with reference to FIGS. 7A and 7B. 
     During the read operation, it is well known that a row address and a column address are applied by the activation of a row address strobe signal RAS and a column address strobe signal CAS, thus specifying a particular memory cell. Accordingly, 256 data bits are generated by a 256 dynamic RAM. Eight pairs of bit lines are connected to one pair of data input/output lines. Therefore, one column select line CSL selects eight pairs of bit lines connected to specific pairs of data input/output lines. Referring to FIG. 7A, the read select signal RS selects a desired pair of bit lines out of eight pairs of bit lines. The read select signal RS is generated by the combination of a decoded address DCA of 0, 1 and 2. If data stored in the memory cell 26 is transmitted to the bit line BL by the enabled word line WL, a voltage difference between the bit lines BL and BL is generated by a data level and a voltage is amplified (i.e. developed) by the N-type sense amplifier 34. Thus only one of read transistors 46 and 50 is turned on in response to the voltage level of the bit lines BL and BL. The discharge transistor 40 is already in a turn-on state by the column select signal CSL. The read transistors 48 and 52 are turned on by the read select signal RS. Then a precharged voltage of the data input/output line IO or IO is discharged through conductive path, i.e. a switching path. Hence, a voltage difference between the data input/output lines IO and IO is generated and the voltage difference is amplified by amplifier means such as a data input/output line sense amplifier (not shown) Amplifier means need not be provided when the voltage difference between data input/output lines IO and IO is sufficiently generated. In such a case, the voltage difference is transmitted to the main data input/output line MIO of FIGS. 4A and 4B. Consequently, data is transmitted through the read transistor 48 or 52 to the data input/output line by selecting one of n (eight in the present embodiment) pairs of bit lines by the read select signal RS. Through the above described path, the data conveyed on the bit line is transmitted to the main data input/output line MIO. 
     Referring again to FIGS. 4A and 4B, sixteen reference blocks consist of 128K within the unit array 12, and four main data input/output lines MIO are in charge of data conveyed on one reference block. Therefore, within one sub array 22, 64 data bits are obtained through 64 main data input/output lines. 
     During the write operation, if data is supplied through a data input buffer (not shown) from the exterior of a chip and conveyed on the main data input/output line MIO or inlineMIO, the data is again transmitted to the data input/output line IO or IO. The transmitted data performs the write operation rapidly through the write transistors 36 and 38 or 42 and 44, i.e. two NMOS transistors, by the enabled column select signal CSL of a selected column and the write select signal WS. The write select signal WS selects one of n (eight in the present embodiment) pairs of bit lines. 
     FIG. 8 is a block diagram showing a data input/output path of FIG. 6 and illustrates a schematic process of the read and write operations. 
     In the architecture according to the present invention, there is no need to provide the local data input/output line shown in FIG. 2 in order to achieve high bandwidth such as the output of 256 bits. Therefore the line loading problem occurs only in the main input/output line MIO and the data input/output line IO. When considering the achievement of high bandwidth, the architecture according to the present invention minimizes the line loading problem of the convention architecture. Moreover, not only line speed but layout which has a direct influence on the size of a highly integrated memory is facilitated by the architecture of the present invention. In FIG. 2, five signal lines, i.e. a local data input/output line LOCAL I/O, a sub data input/output line SUB I/O, a write enable signal line YWRITE, a read enable signal YREAD, and a column select line CSL are positioned in the column direction. However, since the architecture of the present invention requires only three signal lines, i.e. the main data input/output line MIO, the data input/output line IO, and the column select line CSL, the present invention is advantageous to high integration. Moreover, since the word line WL, the read select line RS, and the write select line WS are positioned in the length direction of a memory device, the bit line, the data input/output line, and the column select line CSL are preferably disposed at right angles to the word line, thereby efficiently achieving the data input/output of multiple bits. If 2 n  pairs of bit lines are connected to a pair of data input/output lines, 2 m  pairs of data input/output lines and 2 m  column select lines are needed. In the basic block of the preferred embodiment of the invention, a pair of data input/output lines and one column select line are arranged at right angles to the word line. In order to extract multiple input/output data bits, the size of layout can be minimized. 
     FIG. 9 illustrates the multiplexer 20 of FIGS. 4A and 4B. In FIG. 9, a plurality of unit multiplexers 60 are shown constituting one multiplexer 20. The architecture of FIG. 9 generates 256 bits and thus one unit multiplexer 60 is constructed with respect to eight pairs of data input/output lines. 
     FIG. 10 shows a circuit diagram of the unit multiplexer 60 of FIG. 9. A first transmission gate 62 connected between the data input/output line IO and the main data input/output line MIO has gates connected to column select signals CSL and CSL. A second transmission gate 64 connected between the data input/output line IO and the main data input/output line MIO has gates connected to column select signals CSL and CSL. A NOR gate 68 receives the complementary column select signal CSL and a signal φIOPP. A first PMOS transistor 70 for equalizing the main data input/output lines MIO and MIO has a gate connected to the output signal of the NOR gate 68 and the channel connected between the main data input/output lines MIO and MIO. Second and third PMOS transistors 72 and 74 for precharging the main data input/output lines MIO and MIO have gates connected to the output signal of the NOR gate 68 and channels connected to the main data input/output lines MIO and MIO. Referring to FIGS. 9 and 10, only selected data input/output lines IO and IO and a column select line CSL corresponding thereto are enabled, and thus data is transmitted to the main data input/output lines MIO and MIO. 
     FIG. 11 shows a circuit for generating the a signal φIOPP FIG. 10. Enabling processes of input signals DCA and COL are shown in FIG. 7A. 
     While the invention has been particularly shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that foregoing and other changes in form and details may be made without departing from the spirit and scope of the present invention.