Patent Publication Number: US-9905611-B2

Title: Variable resistance memory

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 62/217,671, filed Sep. 11, 2015, the entire contents of which are incorporated herein by reference. 
    
    
     FIELD 
     The present embodiment relates to a variable resistance memory. 
     BACKGROUND 
     In recent years, attention is being given to the variable resistance memory as a next-generation memory device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration example of a variable resistance memory according to an embodiment; 
         FIG. 2  is an equivalent circuit diagram illustrating a configuration example of a memory cell array of the variable resistance memory according to an embodiment; 
         FIG. 3  is a bird&#39;s eye view showing a configuration example of the memory cell of the variable resistance memory according to an embodiment; 
         FIG. 4  is a bird&#39;s eye view showing a configuration example of the memory cell of the variable resistance memory according to an embodiment; 
         FIG. 5  is a top view showing a structure example of the memory cell array of the variable resistance memory according to a first embodiment; 
         FIG. 6  is a sectional view showing the structure example of the memory cell array of the variable resistance memory according to the first embodiment; 
         FIG. 7  is a sectional view showing the structure example of the memory cell array of the variable resistance memory according to the first embodiment; 
         FIG. 8  is a sectional view showing the structure example of the memory cell array of the variable resistance memory according to the first embodiment; 
         FIG. 9  is top view showing the structure example of the memory cell array of the variable resistance memory according to the first embodiment; 
         FIG. 10  is a schematic view illustrating an operation example of the variable resistance memory according to the first embodiment; 
         FIG. 11  is a schematic view illustrating an operation example of the variable resistance memory according to the first embodiment; 
         FIG. 12  is a schematic view illustrating an operation example of the variable resistance memory according to the first embodiment; 
         FIG. 13  is a top view showing a structure example of the memory cell array of the variable resistance memory according to a second embodiment; 
         FIG. 14  is a sectional view showing a structure example of the memory cell array of the variable resistance memory according to the second embodiment; 
         FIG. 15  is a top view showing a structure example of the memory cell array of the variable resistance memory according to a third embodiment; 
         FIG. 16  is a sectional view showing a structure example of the memory cell array of the variable resistance memory according to the third embodiment; and 
         FIG. 17  is a sectional view showing a structure example of the memory cell array of the variable resistance memory according to a modification of the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a variable resistance memory includes first and second semiconductor regions arranged in a semiconductor layer a first direction parallel to a surface of the semiconductor layer, a first memory cell provided in the first semiconductor region, the first memory cell including a first transistor having a first gate connected to a word line and a first memory element on the first transistor, wherein the word line extends in a second direction parallel to the surface of the semiconductor layer, and a second transistor provided in the second semiconductor region and connected to one end of the first memory cell via a bit line extending in the first direction, wherein the second semiconductor region extends in a third direction parallel to the surface of the semiconductor layer and the third direction intersects the first and second directions. 
     Hereinafter, the embodiments will be described with reference to the drawings. In the description that follows, the same reference numerals are attached to components having substantially the same function and configuration and a duplicate description is provided only when necessary. 
     With regard to components having a letter or a number attached to the end of a reference sign, if the constituting members with different ends are not distinguished, the letter or the number at the end of the reference sign is omitted. 
     EMBODIMENTS 
     A variable resistance memory according to the embodiments will be described with reference to  FIGS. 1 to 17 . 
     (1) First Embodiment 
     A variable resistance memory according to the first embodiment will be described with reference to  FIGS. 1 to 12 . 
     (a) Configuration Example 
     A configuration example of the variable resistance memory according to the first embodiment will be described with reference to  FIGS. 1 to 9 . 
       FIG. 1  is a schematic diagram showing an outline of a memory system (storage device) including a variable resistance memory according to the present embodiment. 
     In the present embodiment, as shown in  FIG. 1 , a variable resistance memory (memory device)  1  is coupled to a memory controller (or a host device)  200 . For example, the variable resistance memory  1  and the memory controller  200  are provided inside a storage device or a memory system. 
     The memory controller  200  requests the variable resistance memory  1  to write data or read data. 
     For a request to write data, the memory controller  200  sends a write command, an address where the data should be written (hereinafter, called a write address), and data to be written to the variable resistance memory  1 . 
     For a request to read data, the memory controller  200  sends a read command and an address where the data should be read (hereinafter, called a read address) to the variable resistance memory  1 . The memory controller  200  receives data read based on the read command and read address from the variable resistance memory  1 . The memory controller  200  transfers the read data to another device (for example, a host device). 
     Based on the write command, the variable resistance memory  1  writes data from the memory controller  200  into a memory cell array  11 . Based on the read command, the variable resistance memory  1  reads data from inside the memory cell array  11 . 
     The variable resistance memory  1  includes an input/output circuit  12 , a command-address latch circuit  13 , a voltage generator  14 , a sequencer  15 , and a memory core circuit CC. 
     The input/output circuit  12  temporarily holds data from the memory controller  200  and also data from the memory core circuit CC. 
     The command-address latch circuit  13  temporarily holds a command CMD and an address ADR supplied from the memory controller  200 . The command-address latch circuit  13  transfers the command CMD and the address ADR to a circuit inside the variable resistance memory  1  at a certain timing. The command-address latch circuit  13  outputs the command CMD to the sequencer  15 . The command-address latch circuit  13  outputs the address ADR to the memory core circuit CC. 
     The voltage generator  14  generates various voltages for the operation of the variable resistance memory  1  using a power supply voltage supplied from outside. 
     The sequencer  15  receives a control signal CNT from the memory controller  200 . The sequencer  15  controls the operation inside the variable resistance memory  1  based on the command CMD and the control signal CNT. 
     The memory core circuit CC includes a memory cell array  11 , a column decoder  16 , a bit line control circuit  17 , a row decoder  18 , a word line driver  19 , a write circuit  20 , and a read circuit  21  and the like. 
     The memory cell array  11  includes a plurality of memory cells MC. The memory cell MC is connected to a bit line BL, a source line (complementary bit line) SL, and a word line WL. The memory cell array  11  includes selection elements BGT, SGT to select the memory cell MC. 
     For example, the memory cell array  11  has a hierarchical bit line structure. Thus, the bit line BL is connected to a global bit line via the selection element SGT. The source line SL is connected to a global source line via the selection element BGT. 
     The column decoder  16  and the bit line control circuit  17  control a column (bit lines) of the memory cell array  11 . 
     The column decoder  16  decodes a column address of the address ADR. 
     The bit line control circuit (for example, a column switch circuit)  17  selects and activates the bit line BL and a control line based on the decoded column address. 
     The row decoder  18  and the word line driver  19  controls a row (word lines and control lines) of the memory cell array  11 . 
     The row decoder  18  decodes a row address of the address ADR. The row decoder  18  selects and activates the word line WL and a control line based on the decoded row address. 
     The word line driver  19  applies a voltage to the selected word line WL and a selected control line. 
     The write circuit  20  is a circuit to write data into the memory cell MC. The write circuit  20  includes a source/sink circuit to generate a write current (or a write voltage) and the like. 
     The read circuit  21  is a circuit to read data from the memory cell MC. The read circuit  21  includes a sense amplifier circuit and a latch circuit and the like. 
       FIG. 2  is an equivalent circuit diagram showing an example of an internal configuration of a memory cell array of the variable resistance memory. 
     In  FIG. 2 , the internal configuration of a portion (some control unit) inside the memory cell array is shown. 
     In  FIG. 2 , principal components of the memory cell array  11  are illustrated. 
     As shown in  FIG. 2 , a plurality of memory cells MC are arranged in a matrix shape. 
     A plurality of word lines WL(WL&lt; 0 &gt;, WL&lt; 1 &gt;, WL&lt;n−2&gt;, WL&lt;n−1&gt;) are provided inside the memory cell array  11 . n is an integer equal to 2 or greater. The plurality of memory cells MC arranged in the Y direction are connected to a common word line WL. 
     A plurality of bit lines (local bit lines) BL(BL&lt; 0 &gt;, BL&lt; 1 &gt;, BL&lt;m−2&gt;, BL&lt;m−1&gt;) are provided inside the memory cell array  11 . m is an integer equal to 2 or greater. 
     The plurality of memory cells MC arranged in the X direction in a control unit CBK are connected to a common bit line BL. 
     In the present embodiment, the plurality of memory cells MC arranged in the X direction and the Y direction are connected to one source line SL in a control unit CBK. Hereinafter, the source line SL connected to the plurality of memory cells MC in common will be called a common source line SL. Also hereinafter, the control unit of the plurality of memory cells corresponding to one common source line SL will be called a cell block. 
     One or more block gate transistors BGT are provided in the memory cell array  11 . The block gate transistor (also called a source line side select transistor) BGT is an element to select the cell block CBK inside the memory cell array  11 . 
     One end of a current path of the block gate transistor BGT is connected to the common source line SL. The other end of the current path of the block gate transistor BGT is connected to the global source line GSL. 
     The gate of the block gate transistor BGT is connected to a block gate line (control line) BGL. 
     For example, one block gate transistor BGT is provided so as to correspond to one bit line BL. One block gate transistor BGT is provided for the plurality of memory cells connected to the common bit line BL. 
     If, like in the present embodiment, the plurality of memory cells MC are connected to the common source line SL, gates of a plurality of block gate transistors BGT connected to one common source line SL are connected to a common block gate line BGL. In this case, when a block gate line BGL is activated, all memory cells MC connected to the common source line SL are connected to the global source line GSL via the block gate transistor BGT in an ON state. 
     In the present embodiment, a plurality of select gate transistors SGT are provided in the cell block BK so as to correspond to the plurality of bit lines BL in a one-to-one correspondence. 
     One end of the current path of the select gate transistor (also called a bit line side select gate transistor) SGT is connected to one corresponding bit line BL among the plurality of bit lines BL. 
     The other end of the current path of the select gate transistor SGT is connected to the global bit line GBL. The global bit line GBL is connected to the plurality of select gate transistors SGT in common. 
     A plurality of select gate lines SGL(SGL&lt; 0 &gt;, SGL&lt; 1 &gt;, SGL&lt; 2 &gt;, SGL&lt;m−2&gt;, SGL&lt;m−1&gt;) are provided in the cell block CBK. 
     The gate of the select gate transistor SGT is connected to one corresponding select gate line SGL among the plurality of select gate lines SGL. 
     The one selected select gate transistor SGT selectively connects electrically one bit line BL corresponding to the select gate transistor SGT among the plurality of bit lines BL to the global bit line GBL. 
     For example, one global bit line GBL corresponds to one control unit (called a segment in the present embodiment) for the column of the memory cell array  11 . For example, 16 bit lines BL are allocated to one global bit line GBL in one cell block CBK. In this case, 16 select gate lines SGL and 16 select gate transistors SGT are allocated to one global bit line GBL in one cell block CBK. 
     The memory cell MC includes one memory element  3  and one selection element  4 . In a variable resistance memory according to the present embodiment, the memory element  3  is a variable resistance element. The selection element  4  is a field effect transistor (hereinafter, called a cell transistor). 
     A structure example of the memory cell of a variable resistance memory according to the present embodiment will be described using  FIGS. 3 and 4 . 
       FIG. 3  is a bird&#39;s eye view illustrating a structure example of the memory cell of the variable resistance memory according to the present embodiment. 
     As shown in  FIG. 3 , the cell transistor  4  is provided on a semiconductor substrate  100 . For example, the cell transistor  4  is a vertical type transistor. 
     The current path of the vertical type transistor  4  is parallel to a direction (V direction) perpendicular to the surface of the semiconductor substrate  100 . Here, perpendicular means being perpendicular or approximately perpendicular to the surface of the semiconductor substrate  100 . Approximately perpendicular means that a certain angle is within the range of 40°θ≦90° with respect to the surface of the semiconductor substrate  100 . 
     One terminal of the vertical type transistor  4  is positioned on the side of the memory element  3  and the other terminal is positioned on the side of the substrate  100 . In this manner, two terminals as a source/drain of the vertical type transistor  4  are arranged in the direction perpendicular to the surface of the semiconductor substrate  100 . 
     The vertical type transistor  4  as a cell transistor includes a semiconductor portion  40 , a gate electrode  41 , and a gate insulating film  42 . 
     The semiconductor portion (body portion)  40  extends in the V direction. For example, the semiconductor portion  40  has a prismatic shape. The semiconductor portion  40  is joined to the semiconductor substrate  100 . One terminal of the source/drain is provided inside one end (top end) of the semiconductor portion  40  in the V direction and the other terminal of the source/drain is provided inside the other end (bottom end) of the semiconductor portion  40  in the V direction. The semiconductor portion  40  functions as a channel portion (channel region) of the vertical type transistor  4 . 
     The gate electrode  41  is opposed to the side face of the semiconductor portion  40 . The gate insulating film  42  is provided between the side face of the semiconductor portion  40  and the gate electrode  41 . The side face of the semiconductor portion  40  is a surface intersecting the direction parallel to the surface of the semiconductor substrate  100 . 
     If the vertical type transistor  4  has, like the example shown in  FIG. 3 , a double gate structure, the gate electrode  41  includes two electrode portions  410 ,  411 . The two electrode portions  410 ,  411  are opposite to each other across the semiconductor portion  40  in a direction (for example, the X direction) parallel to the surface of the semiconductor substrate  100 . The electrode portion  410  is provided on the gate insulating film  42  covering the side face on one side in the X direction of the semiconductor portion  40  and the electrode portion  411  is provided on the gate insulating film  42  covering the side face on the other side in the X direction of the semiconductor portion  40 . 
     A source line is arranged inside the semiconductor substrate  100  below the vertical type transistor  4 . 
     The memory element  3  is arranged above one terminal of the vertical type transistor (cell transistor)  4 . The bit line BL is arranged above the memory element  3 . 
     Thus, the cell size of the memory cell MC is reduced by the memory element  3  being stacked on the cell transistor  4  in the direction perpendicular to the surface of the semiconductor substrate. 
     In addition, cutoff characteristics of the memory cell MC are improved and also supply characteristics of a current to the memory element  3  are improved by a vertical type transistor being used as the cell transistor  4 . 
     In the present embodiment, the variable resistance memory  1  is a magnetic memory (for example, a magnetic random access memory). The magnetic memory includes a magnetoresistive effect element as the memory element (variable resistance element)  3 . 
     If the memory element  3  is a magnetoresistive effect element, the magnetoresistive effect element  3  is an element including a magnetic tunnel junction (hereinafter, called a MTJ element). 
     The MTJ element  3  as a memory element includes at least a storage layer  30 , a reference layer  31 , and a tunnel barrier layer  32 . The tunnel barrier layer (for example, a film including MgO)  32  is provided between the storage layer  30  and the reference layer  31 . 
     The storage layer  30  is a magnetic layer in which the orientation of magnetization is variable. The reference layer  31  is a magnetic layer in which the orientation of magnetization is invariable. The storage layer  30  and the reference layer  31  are a magnetic layer (for example, a film including CoFeB) having vertical magnetic anisotropy. That the orientation of magnetization is variable indicates that the orientation of magnetization is changed by a predetermined write current. That the orientation of magnetization is invariable indicates that the orientation of magnetization is not changed by a predetermined write current. 
     The resistance value of the MTJ element  3  changes in accordance with the relative relationship between the orientation of magnetization of the reference layer  31  and the orientation of magnetization of the storage layer  30 . If the orientation of magnetization of the storage layer  30  is the same as the orientation of magnetization of the reference layer  31 , the MTJ element  3  has a first resistance value R 1 . If the orientation of magnetization of the storage layer  30  is different from the orientation of magnetization of the reference layer  31 , the MTJ element  3  has a second resistance value R 2  higher than the first resistance value R 1 . 
     First data (for example, “0” data) is associated with the MTJ element  3  in a state having the first resistance value R 1  (first resistance state). Second data (for example, “1” data) is associated with the MTJ element  3  in a state having the second resistance value (second resistance state). 
     Thus, the resistance value of the MTJ element  3  is changed by a magnetization array state of the MTJ element  3  being controlled, allowing the MTJ element  3  to function as a memory element. 
     For example, the resistance state (magnetization array state) of the MTJ element  3  as a memory element is controlled by spin-transfer torque (STT). 
     When data is written into the MTJ element  3 , currents (hereinafter, called write currents) Iw 1 , Iw 2  are passed to the MTJ element  3  to change the orientation of magnetization of the storage layer  30 . Current values of the write currents Iw 1 , Iw 2  are equal to the magnetization reversal threshold or more of the storage layer  30  and less than the magnetization reversal threshold of the reference layer  31 . The magnetization reversal threshold is a current value to reverse the magnetization of a magnetic layer. 
     When the write current Iw (Iw 1 , Iw 2 ) is supplied to the MTJ element  3  in the memory cell selected to write data, the cell transistor  4  is turned on. 
     In an STT type magnetic memory, the orientation of magnetization of the storage layer  30  changes in accordance with the direction of the write current Iw flowing through the MTJ element  3 . 
     If the orientation of magnetization of the storage layer  30  is set to the same state as that of the reference layer  31  (parallel magnetization state), the write circuit  20  passes the write current Iw 1  in the direction from the storage layer  30  to the reference layer  31 . 
     Due to the write current Iw 1 , spin torque resulting from spin in the same orientation as that of the magnetization of the reference layer  31  acts on the magnetization of the storage layer  30 . Accordingly, the orientation of magnetization of the storage layer  30  is aligned with the orientation of magnetization of the reference layer  31 . Therefore, the resistance value of the MTJ element  3  becomes the first resistance value R 1  and the MTJ element  3  holds the first data. 
     On the other hand, if the orientation of magnetization of the storage layer  30  is set to an opposite state to that of the reference layer  31  (anti-parallel magnetization state), the write circuit  20  passes the write current Iw 2  in the direction from the reference layer  31  to the storage layer  30 . 
     Due to the write current Iw 2 , spin torque resulting from spin in the orientation opposite to that of the magnetization of the reference layer  31  acts on the magnetization of the storage layer  30 . Accordingly, the orientation of magnetization of the storage layer  30  is opposite to the orientation of magnetization of the reference layer  31 . Therefore, the resistance value of the MTJ element  3  becomes the second resistance value R 2  and the MTJ element  3  holds the second data. 
     Thus, in the present embodiment, when the current Iw 1  from the source line SL toward the bit line BL is supplied into the MTJ element  3 , “0” data is written into the memory cell MC. When the current Iw 2  from the bit line BL toward the source line SL is supplied into the MTJ element  3 , “1” data is written into the memory cell MC. 
       FIG. 4  is a bird&#39;s eye view illustrating a modification of the memory cell of the variable resistance memory according to the present embodiment. 
     As shown in  FIG. 4 , a vertical type transistor in a surrounding gate structure may also be used as the cell transistor  4 . 
     In the vertical type transistor  4  in a surrounding gate structure, the entire side face of the semiconductor portion  40  is covered with the gate electrode  41  via a gate insulating film  42 P. 
     In the cell transistor  4  in a surrounding gate structure, for example, a semiconductor portion  40 P has a columnar structure. However, the semiconductor portions  40 ,  40 P of the cell transistor  4  do not depend on the gate structure and may be prismatic or columnar. The sectional shape of the semiconductor portions  40 ,  40 P may be trapezoidal. 
     Depending on the internal configuration of the memory cell array  11 , the reference layer  31  may be arranged on the side of the cell transistor  4  and the storage layer  30  may be arranged on the side of the bit line. 
     (b) Structure Example of the Memory Cell Array 
     A structure example of the variable resistance memory according to the present embodiment will be described with reference to  FIGS. 5 to 9 . 
       FIG. 5  is a top view showing a planar structure of the memory cell array of the variable resistance memory according to the present embodiment.  FIGS. 6 to 8  are sectional views showing a sectional structure of the memory cell array of the variable resistance memory according to the present embodiment.  FIG. 6  corresponds to a cross section along a VI-VI line in  FIG. 5 .  FIG. 7  corresponds to a cross section along a VII-VII line in  FIG. 5 .  FIG. 8  corresponds to a cross section along a VIII-VIII line in  FIG. 5 . In  FIGS. 6 to 8 , the illustration of an interlayer insulating film on the semiconductor substrate is omitted to clarify and simplify the illustration. 
     As shown in  FIGS. 5 to 7 , the plurality of memory cells MC are provided in a semiconductor region  101  in the semiconductor substrate (for example, a silicon single crystal substrate)  100  in the memory cell array  11 . Hereinafter, the semiconductor region  101  where a plurality of memory cells are provided will be called the cell block region  101 . The cell block region  101  is a rectangular (flat) semiconductor region. 
     The plurality of memory cells MC are arranged in the cell block region  101  in a matrix shape. 
     A plurality of word lines WL extend in the Y direction on the cell block region  101 . The plurality of word lines WL are arranged in the X direction with predetermined pitches. 
     The word line WL is a conductive layer including at least one of a silicide layer, a metal layer, a semiconductor layer, and a compound layer. 
     The conductive layer  41  as a word line is opposed to the side face of the semiconductor portion  40  of the cell transistor  4  via the gate insulating film  42 . The conductive layer  41  is used as the word line WL and also used as the gate electrode  41  of the cell transistor  4 . 
     The insulating film  42  is provided between the top surface of the semiconductor region  101  and the bottom of the conductive layer  41 . The insulating film is a film formed simultaneously with the gate insulating film  42 . 
     Short-circuits between the conductive layer  41  and the semiconductor region  101  are prevented by the insulating film. The insulating film between the conductive layer  41  and the semiconductor region  101  may also be formed separately from the process of the gate insulating film  42 . 
     The semiconductor portion  40  is a semiconductor region continuing from the semiconductor substrate  100 . For example, the semiconductor portion  40  is a semiconductor region cut out from the semiconductor substrate  100  by photolithography and etching of the semiconductor substrate  100 . In this case, the semiconductor portion  40  continues to the semiconductor substrate  100 . 
     Incidentally, the semiconductor portion  40  may be a film (crystalline layer) formed on the semiconductor substrate  100  by film deposition technology or crystal growth technology. In this case, the semiconductor portion  40  does not continue to the semiconductor substrate  100 . However, even if the semiconductor portion  40  and the semiconductor substrate  100  are made of different members, a current flows between the semiconductor portion  40  and the semiconductor substrate  100 . 
     The cell block region  110  is a region (flat semiconductor region) continuing in the X direction and the Y direction. Thus, as shown in  FIG. 7 , regions where memory cells (cell transistors) adjacent in the Y direction are provided are mutually connected by the semiconductor region  108  without being isolated by an insulating film. Accordingly, a plurality of the semiconductor portions  40  arranged in the Y direction are mutually electrically connected. 
     A neighborhood region (surface layer of the semiconductor region)  110  of a junction of the semiconductor portion  40  and the semiconductor region  101  functions as the common source line SL. For example, the layer (hereinafter, called a common source line layer)  110  is a semiconductor region (diffusion layer) including impurities. With the addition of impurities, the common source line layer  110  has a lower resistance value than a region of the semiconductor substrate  100  including no impurities. 
     In  FIG. 7 , if the cell transistor  4  is, for example, a vertical type transistor in a double gate structure, an insulating film (not shown) is provided in a region  150  between the semiconductor portions  40  adjacent in the Y direction. If the cell transistor  4  is a vertical type transistor in a surrounding gate structure, by contrast, a conductive layer (word line) is provided in the region  150 . 
     A plug  49  is provided on the top end of the semiconductor portion  40 . The memory element (for example, an MTJ element)  3  is provided on the plug  49 . 
     For example, the block gate transistor BGT is provided, as shown in  FIGS. 5 and 6 , in the cell block region  101 . The semiconductor region where the block gate transistor BGT is provided (hereinafter, may also be called a block gate region) continues to a region where the memory cell MC is provided. 
     The block gate region is positioned on the one end side in the X direction of the cell block region  101 . 
     The block gate transistor BGT is a vertical type transistor. The block gate transistor BGT has substantially the same structure as the cell transistor  4 . The block gate transistor BGT is formed simultaneously in a process common to the cell transistor  4 . 
     The block gate transistor BGT includes a semiconductor portion  40 X, a gate electrode  41 X, and a gate insulating film  42 X. 
     The conductive layer as the gate electrode  41 X is opposed to the side face of the semiconductor portion  40 X via the gate insulating film  42 X. The insulating film  42 X is provided between the gate electrode  41 X and the top surface of the semiconductor substrate  100 . The gate electrode (conductive layer)  41 X extends in the Y direction and is shared by the plurality of block gate transistors BGT arranged in the Y direction. The gate electrode  41 X functions as the block gate line BGL. 
     The bottom end of the semiconductor portion  40 X is connected to the semiconductor region  101  (semiconductor substrate  100 ) as a cell block region. Accordingly, one end of the block gate transistor BGT is connected to the common source line  110 . The block gate transistors BGT connected to the same common source line  110  share the gate electrode  41 X. 
     Plugs  49 X, CPX are stacked on the top end of the semiconductor portion  40 X. An intermediate interconnect (metal film) MOX is provided on the plug CPX. The intermediate interconnect MOX is connected to the global source line GSL via a via plug VPX. Accordingly, the other end of the block gate transistor BGT is connected to the global source line GSL. 
     The select gate transistor SGT is provided, as shown in  FIGS. 5 to 8 , in a semiconductor region (hereinafter, called a select gate region)  102  isolated from the cell block region  101 . 
     The select gate region  102  is arranged side by side with the cell block  101  on the other end side in the X direction of the cell block region  101  in the memory cell array  11 . For example, an isolation insulating film (isolation region)  199  including a silicon oxide film is provided in a trench between the select gate region  102  and the cell block region  101 . 
     The semiconductor region as the select gate region  102  is electrically isolated from the cell block region  101  by the isolation insulating film  199 . 
     A plurality of select gate regions  102  are provided in the memory cell array  11 . The plurality of select gate regions  102  are arranged in the Y direction. One select gate region  102  is connected to one global bit line GBL. 
     The plurality of select gate transistors SGT are provided in each of the select gate regions  102 . 
     The select gate transistor SGT is a vertical type transistor. The select gate transistor SGT has substantially the same structure as the cell transistor  4 . The select gate transistor SGT is formed simultaneously in a process common to the cell transistor  4 . 
     The select gate transistor SGT includes a semiconductor portion  40 Z, a gate electrode  41 Z, and a gate insulating film  42 Z. The gate electrode  41 Z is opposed to the side face of the semiconductor portion  40 Z. The gate insulating film  42 Z is provided between the semiconductor portion  40 Z and the gate electrode  41 Z. The gate electrode  41 Z extends in the Y direction and functions as the select gate line SGL. For example, the select gate line SGL is across over the plurality of select gate regions  102  arranged in the Y direction via the isolation region  199 . Accordingly, the plurality of select gate transistors SGT arranged on the same straight line (Y direction) among the plurality of select gate transistors SGT in the different select gate regions  102  are connected to the common select gate line SGL. 
     Two plugs  49 Z, CPZ are stacked on the top end of the semiconductor portion  40 Z. 
     The bit line BL is provided on the plug CPZ of the select gate transistor SGT. 
     The plurality of bit lines (local bit lines) BL extend in the X direction above the semiconductor substrate  100  such as to be across the select gate region  102 , the isolation region  199 , and the cell block region  101 . The plurality of bit lines BL are arranged with predetermined interconnect pitches in the Y direction. 
     The bit line BL is a metal film  120  provided in an interlayer insulating film (not shown) covering the surface of the semiconductor substrate  100 . The metal film  120  as the bit line BL is provided above the plurality of memory elements  4  and select gate transistors SGT arranged in the X direction. 
     The current path of the select gate transistor SGT and the current path of the memory cell MC are connected by the bit line BL. 
     Incidentally, an electric conductor (a plug or an electrode) may be provided between the memory element  3  and the bit line BL. Instead of the plugs CPX, CPZ, an MTJ element in which an electrical breakdown of a tunnel barrier layer is caused and/or a structure in which a conductive layer, instead of the tunnel barrier layer, is sandwiched between magnetic layers may be provided on the top end of the semiconductor portions  40 X,  40 Z. 
     The bottom end of the semiconductor portion  40 Z is connected to the semiconductor region  102 . The bottom end of the semiconductor portion  40 Z is connected to the global bit line GBL via the semiconductor region  102 . To reduce the resistance of the current path that connects the semiconductor portion  40 Z to the global bit line GBL, an impurity region (diffusion layer)  111  may be provided in a surface layer of the semiconductor region  102 . 
     The global bit line GBL and the global source line GSL are positioned at the same interconnect level (height from the substrate surface) and extend in parallel along the X direction. For example, the global source line GSL is arranged between the two global bit lines GBL in the Y direction. 
     As described above, the global source line GSL is connected to the top end of the semiconductor portion  40 X of the block gate transistor BGT via the plugs  49 X, CPX, VPX and the intermediate interconnect MOX. 
     The global bit line GBL is connected to a plug CPA on a fringe  109  in the select gate region  102  via the intermediate interconnect (metal film) MOX and a via plug VPZ. The fringe (contact region)  109  is a semiconductor region continuing to the select gate region  102 . For example, each of the select gate regions  102  arranged in the Y direction is connected to a different global bit line GBL. In accordance with storage capacities or the design (layout) of a variable resistance memory, a plurality of select gate regions (not shown) arranged in the X direction may be provided. In this case, the plurality of select gate regions arranged in the X direction may be connected to the common global bit line GBL. 
     As shown in, for example,  FIG. 7 , elements of peripheral circuits such as a row/column decoder and a bit line control circuit and the like are provided inside the semiconductor substrate  100  common to the cell block region  101 . 
     For example, the semiconductor substrate  100  includes a semiconductor region (hereinafter, called a peripheral circuit region)  106  where peripheral circuits are provided. An isolation insulating film  198  is provided between the peripheral circuit region  106  and the cell block region  101 . 
     A plurality of elements (for example, field effect transistors)  6  are provided in the semiconductor region  106 . In  FIG. 7 , for simplification of illustration, only one field effect transistor is illustrated. 
     The field effect transistor  6  is a transistor in a planar structure. 
     The field effect transistor  6  is provided in a well region  160  in the peripheral circuit region  106 . A gate insulating film  62  is provided on the surface of the well region  160 . A gate electrode  61  is provided on the gate insulating film  62 . Two source/drain regions (diffusion layers)  63 A,  63 B are provided in the well region  160  such as to sandwich a channel region below the gate insulating film  62 . An interconnect MOB is connected to a contact plug CPB on the source/drain regions (diffusion layers)  63 A,  63 B. For example, the contact plug CPB is formed simultaneously with the plugs CPX, CPZ. 
     The current path of the transistor  6  in a planar structure is parallel to the surface of the semiconductor substrate  100 . 
     For example, regarding the position of a member in a direction perpendicular to the surface of the semiconductor substrate  100  (height from the bottom of the semiconductor substrate), the position of the surface of the well region  160  is substantially the same as the position of the top end of the semiconductor portion  40 . 
     To make interconnect capacities arising in, for example, the word line WL, the select gate line SGL, and the block gate line BGL uniform, a dummy interconnect DL ( 41 D) may be provided in the cell block region  101  and the select gate region  102 . The dummy interconnect  41 D is formed simultaneously with the gate electrodes  41 ,  41 X,  41 Z of the vertical type transistors  4 , BGT, SGT respectively. 
     An insulating film  42 D is provided between the bottom face of the dummy interconnect  41 D and the semiconductor regions  101 ,  102 . The insulating film  42 D is formed simultaneously with the gate insulating films  42 ,  42 X,  42 Z of the vertical type transistors  4 , BGT, SGT respectively. Incidentally, a voltage may be applied to the dummy interconnect  41 D to mitigate the influence of interconnect capacities. The dummy interconnect  41 D may be set to a floating state. 
     The dummy interconnect  41 D may not be provided in a memory cell array. 
     In the present embodiment, the select gate region  102  extends in a third direction (Z direction) parallel to the substrate surface. The Z direction is a direction intersecting the X direction and the Y direction. The select gate region  102  extends in an oblique direction along a surface (X-Y plane) parallel to the surface of the semiconductor substrate  100 . 
     In the present embodiment, the plurality of select gate transistors SGT in the select gate region  102  are arranged along the extending direction (Z direction, oblique direction) of the select gate region  102 . 
     As shown in  FIGS. 5 and 8 , regarding a plurality of select gate lines and select gate transistors in the common select gate region  102 , for example, the select gate transistor SGT&lt;k&gt; connected to the k-th select gate line SGL&lt;k&gt; is arranged between the (k−1)-th select gate line (conductive layer) SGL&lt;k−1&gt; and the (k+1)-th select gate line SGL&lt;k+1&gt; in the X direction. k is an integer equal to (m−2) or less. 
     In the one select gate region  102 , the semiconductor portion  40 Z of the select gate transistor SGT&lt;k&gt; is not adjacent to the semiconductor portion  40 Z of the other select gate transistors SGT&lt;k+1&gt;, SGT&lt;k−1&gt; in the X direction. In the one select gate region  102 , the semiconductor portion  40 Z of the select gate transistor SGT is not adjacent to the semiconductor portion  40 Z of other select gate transistors in the Y direction. 
     In the plurality of select gate transistors SGT in the one select gate region  102 , a plurality of the semiconductor portions  40 Z are connected to the common semiconductor region (semiconductor substrate)  102 . For example, the other ends of the current paths of the plurality of select gate transistors SGT are connected to each other by the semiconductor region  102 . The other ends of the current paths of the plurality of select gate transistors SGT in the one semiconductor region  102  are connected to the common plug CPA via the semiconductor region  102 . 
     Each of the select gate transistors SGT in the common select gate region is electrically isolated from each other by the select gate transistor SGT being turned off. 
       FIG. 9  is a schematic top view extracting and showing a select gate region inside a semiconductor substrate in the variable resistance memory according to the present embodiment. 
     As shown in (a) of  FIG. 9 , the select gate region  102  is surrounded by the device isolation region (isolation insulating film)  199 . The select gate region  102  has a rectangular plane shape. 
     In the example of (a) of  FIG. 9 , the select gate region (semiconductor region)  102  in a hexagonal shape is shown, but as long as the shape allows the semiconductor region  102  to extend in the Z direction, the plane shape of the select gate region  102  may be quadrangular (rectangular). In (a) of  FIG. 9 , the select gate region  102  may have a shape in which an edge in the extending direction of the select gate region  102  is rounded. 
     The fringe  109  is provided at an edge of the select gate region  102 . The contact plug CPA is provided on the fringe  109 . 
     As shown in (b) of  FIG. 9 , a select gate region  102 A may have a plane shape extending stepwise. 
     Also, as shown in (c) of  FIG. 9 , a select gate region  102 B may have an elliptic plane shape. The select gate region  102  may have a plane shape having a curve in a certain portion of the semiconductor region. 
     The longitude direction of the select gate region  102  ( 102 A,  102 B) is along the Z direction. 
     In a variable resistance memory according to the present embodiment, as described above, a plurality of select gate transistors SGT are arranged along an extending direction of the semiconductor region  102  in the semiconductor region  102  extending in an oblique direction with respect to the X direction and the Y direction parallel to the substrate surface. 
     Accordingly, in a variable resistance memory according to the present embodiment, the select gate transistors SGT that are independently controlled can be arranged in the memory cell array  11  without forming the fine device isolation region  199 , without using complex manufacturing processes, and without arranging a large exclusive area semiconductor region. 
     Therefore, a variable resistance memory according to the present embodiment can achieve high integration of constituting elements in a memory cell array. 
     (c) Operation Examples 
     Operation examples of the variable resistance memory according to the present embodiment will be described with reference to  FIGS. 10 to 12 . 
     &lt;Write Operation&gt; 
     A write operation of the variable resistance memory according to the present embodiment will be described with reference to  FIGS. 10 and 11 . 
       FIGS. 10 and 11  are schematic diagrams illustrating a write operation of the variable resistance memory according to the present embodiment. In the memory cell array in  FIGS. 10 and 11 , for simplification of illustration and description, two cell blocks CBK and three segments SEG are shown. 
     In  FIGS. 10 and 11 , two block gate lines BGL&lt; 0 &gt;, BGL&lt; 1 &gt; are shown. Three global bit lines GBL and three global source lines GSL are shown. 
     In each of the cell blocks CBK&lt; 0 &gt;, CBK&lt; 1 &gt;, three word lines WL (WL&lt; 0 &gt;, WL&lt; 1 &gt;, WL&lt; 2 &gt;), three bit lines BL (BL&lt; 0 &gt;, BL&lt; 1 &gt;, BL&lt; 2 &gt;), and three select gate lines SGL (SGL&lt; 0 &gt;, SGL&lt; 1 &gt;, SGL&lt; 2 &gt;) are shown. 
     A plurality of memory cells MC in one cell block CBK are connected to a common source line SL even if the memory cells MC are connected to different global bit lines GBL. 
     Here, the description of the above dummy interconnect is omitted. 
     A write operation of the variable resistance memory will be described below. 
     The memory controller  200  sends write commands, addresses, control signals, and data to the variable resistance memory  1  in response to a request from the host (user) during a write operation for the variable resistance memory according to the present embodiment. 
     In the variable resistance memory  1 , the sequencer  15  starts a write operation based on control signals and commands. 
     The voltage generator  14  generates various voltages for the write operation and supplies the generated voltages to each of the circuits  17  to  21 . 
     An address ADR is transferred from the command-address latch circuit  13  to the column decoder  16  and the row decoder  18 . Data DT from outside is transferred to the write circuit  20  via the I/O circuit  12 . 
     Based on the selected address ADR from outside, the potential of each interconnect in the memory cell array  11  is controlled. 
     To select, for example, as shown in  FIG. 10 , the cell block CBK (here, the cell block CBL&lt; 0 &gt;) indicated by the selected address ADR among a plurality of cell blocks in the memory cell array  11 , an H(high)-level voltage is applied to the block gate line BGL indicated by the selected address ADR as a selected voltage. An L(low)-level voltage is applied to the non-selected block gate line BGL in the non-selected cell block CBK&lt; 1 &gt;. 
     Accordingly, in the selected cell block CBK&lt; 0 &gt;, the block gate transistor BGT connected to the selected block gate line BGL is turned on. On the other hand, in the non-selected cell block CBK&lt;l&gt;, the block gate transistor BGT connected to the non-selected block gate line BGL is turned off. 
     In  FIG. 10 , a plurality of block gate transistors BGT in the same cell block CBK (in the same semiconductor region  101 ) are connected to a common block gate line BGL. Thus, even if block gate transistors are connected to different global source lines GSL (block gate transistors belonging to different segments SEG), the block gate transistors in the same cell block CBK (block gate transistors connected to the same common source line SL) BGT are turned on. 
     To select a word line in the memory cell array  11 , the H-level voltage is applied to the word line WL (here, the word line WL&lt; 1 &gt;) indicated by the selected address ADR as the selected voltage and the L-level voltage is applied to the non-selected word line WL. 
     Accordingly, the cell transistor  4  of the memory cell MC connected to the selected word line WL&lt; 1 &gt; is turned on and the cell transistors  4  of the memory cells connected to the non-selected word lines WL&lt; 0 &gt;, WL&lt; 2 &gt; are turned off. 
     Even if memory cells are connected to different global bit lines GBL and local bit lines BL, the memory cell MC connected to the selected word line WL&lt; 1 &gt; in the selected cell block CBK&lt; 0 &gt; is activated. 
     To select, for example, the local bit line BL of the memory cell array  11 , the H-level voltage is applied to the select gate line SGL (here, the select gate line SGL&lt; 1 &gt;) corresponding to the selected bit line BL and the L-level voltage is applied to the non-selected select gate line SGL. 
     Accordingly, the select gate transistor SGT connected to the selected select gate line SGL&lt; 1 &gt; is turned on. On the other hand, the select gate transistors SGT connected to the non-selected select gate lines SGL&lt; 0 &gt;, SGL&lt; 2 &gt; are turned off. 
     Even if the select gate transistors SGT are connected to different global bit lines GBL (select gate transistors belonging to different segments), the select gate transistor SGT connected to the selected select gate line SGL&lt; 1 &gt; in the selected cell block CBK&lt; 0 &gt; is turned on. Accordingly, only the bit line BL corresponding to the selected select gate line SGL&lt; 1 &gt; is selectively connected to the global bit line GBL via the select gate transistor SGT that is turned on. 
     In this manner, a plurality of memory cells MC corresponding to the selected block gate line GBL&lt; 0 &gt;, the selected word line WL&lt; 1 &gt;, and the selected select gate line SGL&lt; 1 &gt; become accessible. 
     However, the order of activating the selected block gate line BGL, the selected word line WL, and the selected select gate line SGL is not limited to the above order. 
     In the present embodiment, a write operation of the variable resistance memory includes writing data twice. 
     In the first data writing (in the present embodiment, called an initialization operation or an erase operation), the same data is written into all memory cells connected to the selected word line WL and the selected select gate line SGL in the selected cell block CBK. In the second data writing, data from outside is written into the memory cell indicated by the selected address. 
     As shown in  FIG. 10 , in the first data writing of the write operation, while a plurality of memory cells connected to the selected word line WL&lt; 1 &gt; are turned on, the potential of all the global source lines GSL in the selected cell block CBK&lt; 0 &gt; is set to the H-level and the potential of all the global bit lines GBL in the selected cell block CBK&lt; 0 &gt; is set to the L-level. 
     Accordingly, a write current Iw flows to the memory cells MC corresponding to the selected word line WL&lt; 1 &gt; and the selected select gate line SGL&lt; 1 &gt; in the direction from the common source line SL toward the bit line BL. 
     The same data (for example, “0” data) is written into the memory cells to which the write current Iw is supplied. 
     For the memory cells MC connected to bit lines corresponding to the non-selected select gate lines SGL&lt; 0 &gt;, SGL&lt; 2 &gt;, the select gate transistor SGT is turned off. Thus, even if the memory cell MC corresponding to the non-selected select gate lines SGL&lt; 0 &gt;, SGL&lt; 2 &gt; is connected to the selected word line WL&lt; 1 &gt;, the write current Iw does not flow into the non-selected memory cell MC. 
     Accordingly, if the memory cell MC has the structure in  FIG. 3  (or  FIG. 4 ), the MTJ element  3  is in a “0” data holding state in all memory cells connected to the selected bit line BL and the selected word line WL. 
     After the first data writing (initialization/erase operation), the second data writing is performed to write data from outside into memory cells (write cells) connected to the selected global bit line GBL&lt; 1 &gt;. 
     As shown in  FIG. 11 , the H-level voltage is applied to the global bit line GBL&lt; 1 &gt; corresponding to the memory cell into which data from outside is to be written (or the memory cell to be restored to a state before “0” is written) MC. 
     The L-level voltage is applied to all the global source lines GSL in the cell block CBK. 
     A voltage of an intermediate potential (M level) lower than the H level is applied to the global bit lines GBL&lt; 0 &gt;, GBL&lt; 2 &gt; corresponding to the memory cells MC into which no data from outside is to be written. The non-selected global bit lines GBL&lt; 0 &gt;, GBL&lt; 2 &gt; are precharged by the M-level potential being applied to the non-selected global bit lines GBL&lt; 0 &gt;, GBL&lt; 2 &gt;. Accordingly, the period secured between the completion of the current write operation and the start of the next operation can be shortened. For example, the current value of a current flowing due to a potential difference between the intermediate level and the L level is sufficiently smaller than the current value of the write current Iw (magnetization reversal threshold of the storage layer). Therefore, even if a potential is applied to the non-selected global bit lines GBL&lt; 0 &gt;, GBL&lt; 2 &gt;, erroneous writing of data into non-selected cells hardly occurs. 
     Due to a potential difference between the global bit line GBL&lt; 1 &gt; at the H level and the global source line GSL&lt; 1 &gt; at the L level, the write current Iw flows into the memory cell (write cell) MC via the select gate transistor SGT and the block gate transistor BGT that are turned on. 
     The write current Iw flows through the MTJ element  3  in a direction from the bit line BL toward the common source line SL. 
     Accordingly, for the selected cell MC connected to the selected global bit line GBL&lt; 1 &gt; in the selected cell block CBK&lt; 0 &gt;, the data holding state of the MTJ element  3  changes from the “0” data holding state to the “1” data holding state. 
     The select gate transistor SGT is turned off in a plurality of memory cells connected to the selected word line WL&lt; 1 &gt; and the non-selected bit line BL and thus, the write current Iw does not flow into the memory cell MC connected to the selected word line and non-selected bit line. 
     In this manner, predetermined data is selectively written into the memory cell MC indicated by the selected address. This completes the second data writing in the variable resistance memory according to the present embodiment. 
     Then, the sequencer  15  causes the potentials of the selected global bit line GBL, the selected select gate line SGL, the selected block gate line BGL, and the selected word line WL to transition from the H level to the L level at a predetermined timing. Also, the sequencer  15  causes the potential of the non-selected global bit lines to transition from the intermediate level to the L level. 
     The write operation including writing data twice in the variable resistance memory according to the present embodiment is completed. 
     As described above, even if, like in the present embodiment, the plurality of memory cells MC in the cell block CBK are configured to be connected to the common source line (provided in the common semiconductor region), predetermined data can be written into the selected cell MC. 
     &lt;Read Operation&gt; 
     A read operation of the variable resistance memory according to the present embodiment will be described with reference to  FIG. 12 . 
       FIG. 12  is a schematic diagram illustrating a read operation of the variable resistance memory according to the present embodiment. 
     The sequencer  15  starts a read operation based on read commands, addresses, and control signals from the memory controller  200  during a read operation for the variable resistance memory according to the present embodiment. 
     The sequencer  15  activates the read circuit  21  during the read operation. Accordingly, one input terminal of a sense amplifier  210  in the read circuit  21  is connected to the global bit line GBL. The other input terminal of the sense amplifier  210  is connected to a reference circuit (reference cell). A reference current (or a reference voltage) Iref is supplied to the other terminal of the sense amplifier by the reference circuit  219 . 
     Based on the selected address, the potential of the selected global bit line GBL is set to the H level and the potential of the selected global source line SL is set to the L level. 
     Like in the write operation, the H-level voltage is applied to the selected block gate line BGL&lt; 0 &gt;, the selected select gate line SGL&lt; 1 &gt;, and the selected word line WL&lt; 1 &gt;. Also, the L-level voltage is applied to the non-selected block gate line BGL, the non-selected select gate line SGL, and the non-selected word line WL. 
     The block gate transistor BGT connected to the selected block gate line GBL&lt; 0 &gt;, the select gate transistor SGT connected to the selected select gate line SGL&lt; 1 &gt;, and the cell transistor  4  connected to the selected word line WL&lt; 1 &gt; are turned on. 
     Incidentally, after the H-level voltage is applied to the selected word line WL, the H-level voltage may be applied to the selected global bit line GBL. 
     After the H-level voltage is applied to the selected block gate line BGL and the selected select gate line SGL, the H-level voltage may be applied to the selected word line WL. Conversely, after the H-level voltage is applied to the selected word line WL, the H-level voltage may be applied to the selected block gate line BGL and the selected select gate line SGL. 
     The read current (cell current) Ird flows to the memory cell MC corresponding to the selected address by the selected global bit line GBL being connected to the global source line GSL via the transistor  4 , SGT, and BGT that are turned on. 
     The sense amplifier  210  compares the read current Ird and the reference current Iref. 
     If the MTJ element  3  is in a low-resistance state (for example, the “0” data holding state), the current value of the read current Ird is larger than that of the reference current Iref. 
     If the MTJ element  3  is in a high-resistance state (for example, the “1” data holding state), the current value of the read current Ird is smaller than that of the reference current Iref. 
     Thus, data stored in the memory cell MC is read by magnitudes of the read current and the reference current being determined in this manner. 
     The data read from the memory cell MC is output from the sense amplifier  210  to a latch circuit (not shown) in the read circuit. 
     The data in the latch circuit is output from the I/O circuit  12  to the memory controller  200  at a predetermined timing based on the control of the sequencer  15 . 
     As described above, the variable resistance memory according to the present embodiment can perform a read operation. 
     (d) Summary 
     As described above, a variable resistance memory according to the present embodiment includes a plurality of select gate transistors SGT to select a memory cell in a control unit. One select gate transistor is provided in a memory cell array so as to correspond to one bit line (local bit line). A select gate line is connected to the gate of the select gate transistor SGT. 
     In the present embodiment, the plurality of select gate transistors SGT are provided in the semiconductor region  102  extending in an oblique direction in a plane parallel to the surface of a semiconductor substrate. The plurality of select gate transistors SGT are arranged in an oblique direction so as to go along the extending direction of the semiconductor region  102 . 
     Accordingly, the plurality of select gate lines SGL can be laid out, like the word lines WL, in a periodic pattern (for example, a line and space pattern) having a predetermined pitch in the memory cell array of the variable resistance memory according to the present embodiment. 
     Therefore, the variable resistance memory according to the present embodiment can achieve high integration of select gate transistors in a memory cell array. 
     Accordingly, in the variable resistance memory according to the present embodiment, patterns of semiconductor regions and interconnects in the memory cell array can be formed without using processing of a high level of difficulty. 
     As described above, a variable resistance memory including a memory cell array in a hierarchical bit line structure like the present embodiment can achieve high integration of constituting elements in the memory cell array and a lower level of difficulty of processing of the memory cell array. 
     As a result, a variable resistance memory according to the present embodiment can reduce the cost of manufacturing the resistance change type memory. 
     (2) Second Embodiment 
     A variable resistance memory according to the second embodiment will be described with reference to  FIGS. 13 and 14 . 
       FIG. 13  is a top view illustrating the structure of the variable resistance memory according to the present embodiment.  FIG. 14  is a sectional view illustrating the structure of the variable resistance memory according to the present embodiment.  FIG. 14  corresponds to a cross section along a XIV-XIV line in  FIG. 13 . 
     A select gate transistor SGTA may include a plurality of semiconductor portions  40 A. 
     In the present embodiment, as shown in  FIGS. 13 and 14 , one select gate transistor SGTA includes a plurality of semiconductor portions  40 A arranged in the Y direction. The semiconductor portion  40 A is formed simultaneously with the semiconductor portion  40  of the cell transistor  4 . Regarding dimensions (for example, the diameter or the length of a diagonal line) of the members  40 ,  40 A in a direction parallel to the surface of the semiconductor substrate  100 , the dimension of the top end of the semiconductor portion  40 A is substantially the same as a dimension D 1  of the top end of the semiconductor portion  40 . 
     In one select gate transistor SGTA, top ends of the plurality of semiconductor portions  40 A are connected to a common interconnect (metal film)  45 . 
     In the X direction, for example, a portion of the plurality of semiconductor portions  40 A in one select gate transistor SGTA is adjacent to the plurality of semiconductor portions  40 A in other select gate transistors SGTA. 
     If one select gate transistor SGTA includes the plurality of semiconductor portions  40 A like in the present embodiment, the effective channel width of the vertical type transistor as the select gate transistor SGTA increases. 
     As a result, in the variable resistance memory according to the present embodiment, the select gate transistor SGTA can supply a relatively large current (for example, a write current) to the memory cell MC. 
     As described above, a variable resistance memory according to the present embodiment can improve operation characteristics of the memory. 
     (3) Third Embodiment 
     A variable resistance memory according to the third embodiment will be described with reference to  FIGS. 15 and 16 . 
       FIG. 15  is a top view illustrating the structure of the variable resistance memory according to the present embodiment.  FIG. 16  is a sectional view illustrating the structure of the variable resistance memory according to the present embodiment.  FIG. 16  corresponds to a cross section along a XVI-XVI line in  FIG. 15 . 
     The shape of a semiconductor portion of a select gate transistor may be different from that of a cell transistor. 
     In the present embodiment, as shown in  FIGS. 15 and 16 , a semiconductor portion  40 B of a select gate transistor SGTB has a rectangular plane shape when viewed from a direction (V direction) perpendicular to the surface of a semiconductor substrate  100 . 
     A dimension D 2  in the Y direction of the semiconductor portion  40 B is longer than a dimension D 3  in the X direction of the semiconductor portion  40 B. The dimension D 2  of the semiconductor portion  40 B is longer than a dimension D 1  of a semiconductor portion  40 . For example, the dimension D 3  of the semiconductor portion  40 B is equal to or longer than the dimension D 1  of the semiconductor portion  40 . Thus, the dimensions (area) of the semiconductor portion  40 B are different from those of the semiconductor portion  40 . 
     Incidentally, the plane shape of the semiconductor portion  40 B may be elliptic. A semiconductor portion in an elliptic shape has a major axis direction in the Y direction. 
     A portion of the certain semiconductor portion  40 B of a plurality of the semiconductor portions  40 B arranged in the Z direction is adjacent to a portion of the other semiconductor portion  40 B in the X direction. 
     In the variable resistance memory according to the present embodiment, the select gate transistor SGTB can increase the effective channel width of the vertical type transistor as the select gate transistor SGTB without increasing the number of interconnects. 
     As a result, in the variable resistance memory according to the present embodiment, the select gate transistor SGTB can supply a relatively large current (for example, a write current) to the memory cell MC. 
     As described above, a variable resistance memory according to the present embodiment can improve operation characteristics of the memory. 
     (4) Modification 
     A modification of the variable resistance memory according to the embodiment will be described with reference to  FIG. 17 . 
       FIG. 17  is a sectional view illustrating the structure of the modification of the variable resistance memory according to the present embodiment. 
     In the modification of the variable resistance memory, as shown in  FIG. 17 , a memory cell allay  11  may be disposed on an interlayer insulating film  190  covering the surface of a semiconductor substrate  100 . 
     In this case, a plurality of transistors  6  of the peripheral circuit is disposed on the semiconductor substrate  100 . 
     The memory cell array  11  is stacked above the transistors  6  via the interlayer insulating film  190 . 
     The memory cell array  11  is covered with an interlayer insulating film  191  on the interlayer insulating film  190 . 
     The memory cell array  11  is connected to the transistors  6  via interconnects (not shown) in the interlayer insulating films  190  and  191 . 
     For example, the cell transistor  4  the select gate transistor SGT are formed by using semiconductor layers (semiconductor thin films)  100 Z disposed on the interlayer insulating film  190 . Each of the cell transistor  4  and the select gate transistor SGT is a vertical type thin film transistor. 
     In order to an increasing of a current drive ability (output current) of the cell transistor  4  and the select gate transistor SGT, a process (for example, a MILC: metal induced lateral crystallization) for an improvement of a crystalline quality of the semiconductor layer  100 Z may be performed to the semiconductor layer  100 Z on the interlayer insulating film  190 . 
     The bottom portion of the isolation insulating film  199  is in contact with the top portion of the interlayer insulating film  190 . 
     The select gate region  102  is independent from the cell block region  101 . 
     As described above, in the modification, the memory cell array  11  is stacked above the peripheral circuit (transistors  6 ) via the interlayer insulating film  190  in a direction (V direction) perpendicular to the surface of the semiconductor substrate  100 . 
     As a result, the variable resistance memory according to the modification of the present embodiment can increase the occupation ratio of the memory cell in the chip of the variable resistance memory and reduce the cost (bit cost) of manufacturing the resistance change type memory. 
     (5) Other 
     A variable resistance memory according to an embodiment can be manufactured using the known film deposition technology, crystal growth technology, and etching technology. 
     In a variable resistance memory according to an embodiment, a magnetoresistive effect element is used as a memory element. However, the memory element used for a variable resistance memory according to an embodiment may be a transition metal oxide type variable resistance element (for example, a nickel oxide film or a titanium oxide film) or a phase change element (for example, a film including a chalcogenide film). 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.