Abstract:
A multi-chip package may include a plurality of semiconductor chips integrated in a single package and sharing one or more command pins. Each of the semiconductor chips may include: a command decoder suitable for decoding a command to generate a buffer enable signal, a mode enable signal, and a mode signal; a data input buffer suitable for buffering data to output internal data, in response to the buffer enable signal and a common test mode signal; a command controller suitable for receiving the mode enable signal to output a test mode enable signal by selectively blocking the mode enable signal based on the internal data and the common test mode signal; and a test controller suitable for generating the common test mode signal and a test mode signal, based on the test mode enable signal and the mode signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority of Korean Patent Application No. 10-2015-0132268, filed on Sep. 18, 2015, which is incorporated herein by reference in its entirety. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Exemplary embodiments of the present invention relate to a semiconductor design technology and more particularly, to a multi-chip package (MCP), system and a test method thereof. 
         [0004]    2. Description of the Related Art 
         [0005]    Mobile applications such as PDA (Personal Digital Assistant), third-generation mobile phone, and digital still camera applications require miniaturization. Generally, satisfactory miniaturization has been achieved through the use of submicron semiconductor fabrication technologies. However, continuous demand for ever increasing miniaturization has tested the limits of existing submicron technologies resulting in extended development periods and increased manufacturing costs. 
         [0006]    To address these limitations, especially for mobile applications, a Multi-Chip Package (MCP) technology has been introduced allowing a variety of semiconductor chips, such as a NOR flash memory, a NAND flash memory, an SRAM, and a UtRAM to be mounted in a single package. Generally, MCPs with a stack of four or more semiconductor chips are known. By employing MCP technology, the internal mounting area can be reduced by 50% or more and the line structure can be simplified as compared to using a plurality of single packages. Thus, MCP technology can reduce the cost of products and increase productivity significantly. 
         [0007]    However, due to the use of many chips, a large number of pins exist in an MCP product that can obstruct manufacturing of the product. For reducing the number of pins, the semiconductor chips included in a single MCP can be configured to share command pins. 
         [0008]    Referring to  FIG. 1A  a conventional MCP is provided including a plurality of semiconductor chips CHIP_A and CHIP_B mounted in a single package. Each of the semiconductor chips CHIP_A and CHIP_B includes a plurality of command pins COMMAND PINs and a plurality of data pins DATA I/O PINs. The data pins DATA I/O PINs are individually provided for each of the semiconductor chips CHIP_A and CHIP_B, while the command pins COMMAND PINs are shared by the semiconductor chips CHIP_A and CHIP_B. 
         [0009]      FIG. 1B  is a circuit diagram of a data input buffer included in each of the semiconductor chips CHIP_A and CHIP_B shown in  FIG. 1A . 
         [0010]    Referring to  FIG. 1B , the data input buffer includes two pull-up PMOS transistors and two pull-down NMOS transistors. When a buffer enable signal BUFEN, which is generated by decoding commands inputted through command pins, is activated, the data input buffer buffers external data DATA inputted through a data pin and outputs the buffered data as internal data DATA_INT. 
         [0011]    When a test operation is performed on the MCP, each of semiconductor chips CHIP_A and CHIP_B included the MCP is respectively targeted. However, since the command pins are shared, the semiconductor chips CHIP_A and CHIP_B cannot be independently tested. After all of the semiconductor chips CHIP_A and CHIP_B enter a test mode, a test operation is performed in response to the same command. Thus, there is a need for a new method capable of independently testing the semiconductor chips included in an MCP without having an influence on the entire area of the MCP. 
       SUMMARY 
       [0012]    Various embodiments are directed to an MCP, having a plurality of semiconductor chips that share one or more command pins and are integrated in one package, which may independently perform a test operation, a test operation method of an MCP, and an MCP system. 
         [0013]    In an embodiment, a multi-chip package (MCP) may include a plurality of semiconductor chips integrated in a single package and sharing one or more command pins. Each of the semiconductor chips may include: a command decoder suitable for decoding a command to generate a buffer enable signal, a mode enable signal, and a mode signal; a data input buffer suitable for buffering data to output internal data, in response to the buffer enable signal and a common test mode signal; a command controller suitable for receiving the mode enable signal to output a test mode enable signal by selectively blocking the mode enable signal based on the internal data and the common test mode signal; and a test controller suitable for generating the common test mode signal and a test mode signal, based on the test mode enable signal and the mode signal. 
         [0014]    In an embodiment, there is provided a test method of a multi-chip package having a plurality of semiconductor chips integrated in one package and sharing at least one command pin. The test method may include: entering a common test mode based on a command inputted through the at least one command pin; selectively activating a masking signal based on data inputted through a data pin; setting an individual test mode based on a command inputted through the at least one command pin when the masking signal is deactivated; deactivating a test mode enable signal by blocking the command inputted through the command pin when the masking signal is activated; deactivating the masking signal according to data inputted through the data pin; and ending the common test mode based on a command inputted through the at least one command pin. 
         [0015]    In an embodiment, a multi-chip package system may include: a multi-chip package comprising a plurality of semiconductor chips which share at least one command pin and are integrated in one package; and a controller suitable for transmitting a command to the multi-chip package and exchanging data corresponding to the command with the multi-chip package. Each of the semiconductor chips of the multi-chip package may comprise a plurality of data pins, and selectively sets a test mode of a semiconductor chip to be tested by blocking a command inputted through the command pin according to a value of data inputted through the data pins in a common test mode. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1A  is a diagram illustrating a conventional Multi-Chip Package (MCP). 
           [0017]      FIG. 1B  is a circuit diagram Illustrating a data input buffer included in each semiconductor chip shown in  FIG. 1A . 
           [0018]      FIG. 2  is a block diagram illustrating a semiconductor chip included in an MCP, according to an embodiment of the present invention. 
           [0019]      FIG. 3  is a detailed diagram of a data input buffer shown in  FIG. 2 . 
           [0020]      FIG. 4  is a detailed diagram of a masking signal generation unit shown in  FIG. 2 . 
           [0021]      FIG. 5  is a detailed diagram of a masking unit shown in  FIG. 2 . 
           [0022]      FIG. 6A  is a detailed diagram of a test controller shown in  FIG. 2 . 
           [0023]      FIG. 6B  is a detailed diagram of a common test mode signal generation unit shown in  FIG. 6A . 
           [0024]      FIGS. 7A and 7B  are block diagrams illustrating an MCP, according to an embodiment of the present invention. 
           [0025]      FIG. 8A  is a block diagram illustrating an MCP, according to an embodiment of the present invention. 
           [0026]      FIG. 8B  is a timing diagram for an operation of the MCP illustrated in  FIG. 8A . 
           [0027]      FIG. 8C  is a flowchart for the operation of the MCP illustrated in  FIG. 8A . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    Various embodiments of the invention will be described below in more detail with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete to those skilled in the art. Throughout the disclosure, like reference numerals refer to like parts throughout the various figures and embodiments of the present invention. It is also noted that in this specification, “connected/coupled” refers to one component not only directly coupling another component but also indirectly coupling another component through an intermediate component. In addition, a singular form may include a plural form as long as it is not specifically mentioned in a sentence. 
         [0029]    Referring now to  FIG. 2  is a block diagram Illustrating a semiconductor chip included in an MCP, according to an embodiment of the present invention. 
         [0030]    Referring to  FIG. 2 , the semiconductor chip may include a command decoder  210 , a data input buffer  220 , a command controller  230 , and a test controller  250 . 
         [0031]    The command decoder  210  may decode a command CMD (i.e., a combination of command signals) inputted from an external device or source through command pins (not illustrated), and may generate command signals required for an internal operation. In an embodiment of the present invention, the command decoder  210  may generate a buffer enable signal BUFEN, a mode enable signal TEST_MD, and a mode signal TM_CODE&lt;0:n&gt; as commands required for internal operation. Each command signal may comprise a plurality of bits. 
         [0032]    The data input buffer  220  may buffer data DATA Inputted from an external device or source through a data pin (not Illustrated) and output internal data DATA_INT, in response to the buffer enable signal BUFEN and a common test mode signal TM_MASK. When any one of the buffer enable signal BUFEN and the common test mode signal TM_MASK is activated, the data input buffer  220  may buffer the data DATA and output the internal data DATA_INT. 
         [0033]    The command controller  230  may receive the mode enable signal TEST_MD and output a test mode enable signal TM_EN. The command controller  230  may selectively block the mode enable signal TEST_MD and output the test mode enable signal TM_EN, in response to the internal data DATA_INT and the common test mode signal TM_MASK. 
         [0034]    More specifically, the command controller  230  may include a masking signal generation unit  232  and a masking unit  234 . 
         [0035]    The masking signal generation unit  232  may receive the internal data DATA_INT and generate a mask enable signal MASKEN, in response to the common test mode signal TM_MASK. When the common test mode signal TM_MASK is activated, the masking signal generation unit  232  may activate the mask enable signal MASKEN according to the value of the internal data DATA_INT. When the common test mode signal TM_MASK is deactivated, the masking signal generation unit  232  may deactivate the mask enable signal MASKEN regardless of the value of the Internal data DATA_INT. 
         [0036]    The masking unit  234  may selectively block the mode enable signal TEST_MD in response to the mask enable signal MASKEN, and output the test mode enable signal TM_EN. 
         [0037]    The test controller  250  may generate the common test mode signal TM_MASK and a test mode signal TM&lt;0:m&gt; for an internal test operation, in response to the test mode enable signal TM_EN and the mode signal TM_CODE&lt;0:n&gt;. 
         [0038]    An operation of the semiconductor chip according to an embodiment of the present invention will now be described. 
         [0039]    The command decoder  210  may decode the command CMD inputted from the outside through the common command pins (not illustrated), and generate the mode enable signal TEST_MD and the mode signal TM_CODE&lt;0:n&gt; composed of a plurality of bits. Since the mask enable signal MASKEN is deactivated at the initial stage, the masking unit  234  may output the mode enable signal TEST_MD as the test mode enable signal TM_EN. The test controller  250  may activate the common test mode signal TM_MASK in response to the test mode enable signal TM_EN and the mode signal TM_CODE&lt;0:n&gt;. Thus, the semiconductor chip may enter the common test mode. 
         [0040]    When the semiconductor chip enters the common test mode, the data input buffer  220  may buffer data DATA inputted through a data pin individually provided for the semiconductor chip and output the buffered data as internal data DATA_INT, in response to the activated common test mode signal TM_MASK. The masking signal generation unit  232  may receive the internal data DATA_INT and selectively activate the mask enable signal MASKEN, in response to the activated common test mode signal TM_MASK. 
         [0041]    When a command for individual test mode setting is inputted from an external device or source through the common command pins, the masking unit  234  may selectively block the mode enable signal TEST_MD according to the corresponding mask enable signal MASKEN, and output the test mode enable signal TM_EN. When the mask enable signal MASKEN is activated, the masking unit  234  may block the mode enable signal TEST_MD, and deactivate and output the test mode enable signal TM_EN. Thus, the test controller  250  may not generate the test mode signal TM&lt;0:m&gt; for an internal test operation. On the other hand, when the mask enable signal MASKEN is deactivated, the masking unit  234  may output the mode enable signal TEST_MD as the test mode enable signal TM_EN. Thus, the test controller  250  may generate the test mode signal TM&lt;0:m&gt; for an internal test operation. 
         [0042]    That is, after entering the common test mode, each of the semiconductor chips may selectively block the mode enable signal TEST_MD according to data inputted through an individual data pin, and output the test mode enable signal TM_EN. Since the semiconductor chip which blocks the mode enable signal TEST_MD does not generate the test mode signal TM&lt;0:m&gt;, the semiconductor chip may not perform an individual test mode setting operation. On the other hand, the semiconductor chip which does not block the mode enable signal TEST_MD may generate the test mode signal TM&lt;0:m&gt;. Thus, an internal circuit (not Illustrated) of the corresponding semiconductor chip may perform an individual test mode setting operation. For reference, the individual test mode setting operation may be performed to set a voltage for a specific test operation, delay amounts of signals, and a margin for compensating a variable caused by a process difference. 
         [0043]    Then, the mask enable signal MASKEN which has been activated according to data DATA inputted through the data pin may be deactivated. 
         [0044]    As the above-described process is repeated, each of the semiconductor chips may perform an independent test mode setting operation. 
         [0045]    Then, when the command CMD is inputted from an external device or source through the common command pins (not illustrated), the test controller  250  may deactivate the common test mode signal TM_MASK in response to the test mode enable signal TM_EN and the mode signal TM_CODE&lt;0:n&gt;. Then, the common test mode may end. 
         [0046]    In the embodiment of the present invention, although the same command is inputted to the respective semiconductor chips at the same time, the commands of the semiconductor chips other than the test target may be selectively blocked. Thus, only the semiconductor chip corresponding to the test target may be independently tested. 
         [0047]    Hereafter, referring to  FIGS. 3 to 68 , the components of  FIG. 2  will be described in more detail. 
         [0048]      FIG. 3  is a detailed diagram of the data input buffer  220  shown in  FIG. 2 . 
         [0049]    Referring to  FIG. 3 , the data input buffer  220  may include an enable signal generation unit  320 , an enable unit  340 , and a driving unit  360 . 
         [0050]    The enable signal generation unit  320  may receive the buffer enable signal BUFFN and the common test mode signal TM_MASK, and generate first and second enable signals BS 1  and BS 2 . In an embodiment, the enable signal generation unit  320  may include a NOR gate NOR 1  and an inverter INV 1 . The NOR gate NOR 1  may receive the buffer enable signal BUFEN and the common test mode signal TM_MASK, and perform a NOR operation for outputting the first enable signal BS 1 . The inverter INV 1  may invert the output of the NOR gate NOR 1  and output the second enable signal BS 2 . 
         [0051]    The enable unit  340  may allow a driving voltage to be supplied to the driving unit  360  in response to the first and second enable signals BS 1  and BS 2 . 
         [0052]    The driving unit  360  may drive data DATA inputted from outside through a data pin (not illustrated) to internal data DATA_INT according to the driving voltage supplied from the enable unit  340 . 
         [0053]    Thus, when any one of the buffer enable signal BUFEN and the common test mode signal TM_MASK is enabled, the data input buffer  220  may buffer the data DATA and output the internal data DATA_INT.  FIG. 4  is a detailed diagram of the masking signal generation unit  232  shown in  FIG. 2 . 
         [0054]    Referring to  FIG. 4 , the masking signal generation unit  232  may include a signal driving unit  420 , a latch unit  440 , and a buffer unit  460 . 
         [0055]    The signal driving unit  420  may receive the common test mode signal TM_MASK and the internal data DATA_INT, and generate a pre-mask signal PRE_MASK. The latch unit  440  may latch the pre-mask signal PRE_MASK and output an inverted pre-mask signal PRE_MASKB. The buffer unit  460  may buffer the inverted pre-mask signal PRE_MASKB and generate the mask enable signal MASKEN. 
         [0056]    The signal driving unit  420  may include a pull-up driving unit PU, a logic circuit  422 , and a pull-down driving unit PD. The pull-up driving unit PU may pull-up drive the pre-mask signal PRE_MASK in response to the common test mode signal TM_MASK, the logic circuit  422  may perform an AND operation on the common test mode signal TM_MASK and the internal data DATA_INT, and the pull-down driving unit PD may pull-down drive the pre-mask signal PRE_MASK in response to an output signal of the logic circuit. 
         [0057]    Thus, when the common test mode signal TM_MASK is activated, the masking signal generation unit  232  may activate the mask enable signal MASKEN according to the value of the internal data DATA_INT. When the common test mode signal TM_MASK is deactivated, the masking signal generation unit  232  may deactivate the mask enable signal MASKEN regardless of the value of the internal data DATA_INT. 
         [0058]      FIG. 5  is a detailed diagram of the masking unit  234  shown in  FIG. 2 . 
         [0059]    Referring to  FIG. 5 , the masking unit  234  may include a first inverter INV 2 , a NAND gate NAND 1 , and a second inverter INV 3 . The first inverter INV 2  may invert the mask enable signal MASKEN, and the NAND gate NAND 1  and the second inverter INV 3  may perform an AND operation on the output of the first inverter INV 2  and the mode enable signal TEST_MD. 
         [0060]    Thus, the masking unit  234  may output the test mode enable signal TM_EN by selectively blocking the mode enable signal TEST_MD in response to the mask enable signal MASKEN. 
         [0061]      FIG. 6A  is a detailed diagram of the test controller  250  shown in  FIG. 2 . 
         [0062]    Referring to  FIG. 6A , the test controller  250  may include a common test mode signal generation unit  610  and a test mode signal generation unit  630 . 
         [0063]    The common test mode signal generation unit  610  may generate the common test mode signal TM_MASK in response to the test mode enable signal TM_EN and the mode signal TM_CODE&lt;0:n&gt;. The test mode signal generation unit  630  may generate the test mode signal TM&lt;0:m&gt; by decoding the mode signal TM_CODE&lt;0:n&gt; in response to the test mode enable signal TM_EN. Since the test mode signal generation unit  630  has substantially the same configuration as the existing configuration, detailed descriptions thereof are omitted herein. 
         [0064]      FIG. 6B  is a detailed diagram of the common test mode signal generation unit  610  shown in  FIG. 6A . 
         [0065]    Referring to  FIG. 6B , the common test mode signal generation unit  610  may include a NAND gate NAND 2  and a second inverter INV 4 . 
         [0066]    The NAND gate NAND 2  receives the test mode enable signal TM_EN and some of bits TM_CODE&lt;0&gt; and TM_ODE&lt;1&gt; of the mode signal and performs an AND operation in company with the second inverter INV 4  on the received signals. 
         [0067]    Thus, when the test mode enable signal TM_EN is activated, the test controller  250  may decode the mode signal TM_CODE&lt;0:n&gt; and generate the test mode signal TM&lt;0:m&gt; for an internal test operation. Furthermore, when the test mode enable signal TM_EN is activated and some of bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; of the mode signal have a value of 11 indicating the common test mode, the test controller  250  may activate the common test mode signal TM_MASK such that the respective semiconductor chips may enter the common test mode. On the other hand, when the test mode enable signal TM_EN is activated and any one of the bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; of the mode signal is zero, the test controller  250  may deactivate the common test mode signal TM_MASK such that the respective semiconductor chips may end the common test mode. 
         [0068]      FIGS. 7A and 7B  are diagrams illustrating an MCP according to an embodiment of the present invention. 
         [0069]      FIG. 7A  illustrates that a plurality of semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN are packaged and mounted on one substrate. That is, the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN are mounted on one substrate to form an MCP. Each of the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN mounted in one package may include a plurality of command pins COMMAND PINs and a plurality of data pins DATA I/O PINs. Among the command pins and the data pins, the data pins may be individually provided for each of the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN, and the command pins may be shared by the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN. For reference, when the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN are mounted in one package to form an MCP, the MCP may receive a command CMD from an external controller  710 , and receive and output data DATA. 
         [0070]      FIG. 7B  illustrates that the semiconductor chips are de-packaged for a test. That is, each of the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN may include a plurality of command pins COMMAND PINs and a plurality of data pins DATA I/O PINs. Among the command pins and the data pins, the data pins may be individually provided for each of the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN, and the command pins may be shared by the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN. For reference, when the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN are de-packaged for a test, the semiconductor chips CHIP 0 , CHIP 1 , . . . , CHIPN may receive the command CMD from a test apparatus  730 , and receive and output the test data DATA. 
         [0071]    Hereafter, referring to  FIGS. 8A to 8C , the configuration and operation of the semiconductor chips mounted in the MCP illustrated in  FIG. 7A  will be described.  FIGS. 8A to 8C  do not illustrate configurations related to normal operations of the respective semiconductor chips, but illustrate only the configuration related to the test operation according to the embodiment of the present invention. Furthermore, the same components as those illustrated in  FIG. 2  will be represented by like reference numerals. 
         [0072]      FIG. 8A  is a block diagram illustrating an MCP according to an embodiment of the present invention. For reference,  FIG. 8  shows a detailed configuration of the respective semiconductor chips of the MCP shown in  FIG. 7A . 
         [0073]    Referring to  FIG. 8A , each of semiconductor chips CHIP 0 , CHIP 1 , and CHIP 2  mounted in one package may include a plurality of command pins COMMAND PINs and a plurality of data pins DATA I/O PINs. The data pins may be individually provided for each of the semiconductor chips CHIP 0 , CHIP 1 , and CHIP 2 , and the command pins may be shared by the semiconductor chips CHIP 0 , CHIP 1 , and CHIP 2 . The semiconductor chips CHIP 0 , CHIP 1 , and CHIP 2  may include command decoders  210 _ 0 ,  210 _ 1 , and  210 _ 2 , data input buffers  220 _ 0 ,  220 _ 1 , and  220 _ 2 , command controllers  230 _ 0 ,  230 _ 1 , and  230 _ 2 , and test controllers  250 _ 0 ,  250 _ 1 , and  250 _ 2 , respectively, which are illustrated in  FIG. 2 . Since the operations of the respective units have been described with reference to  FIG. 2 , detailed descriptions thereof are omitted herein. 
         [0074]      FIG. 8B  is a timing diagram for describing an operation of the MCP shown in  FIG. 8A .  FIG. 8C  is a flowchart for describing the operation of the MCP shown in  FIG. 8A . 
         [0075]    Referring to  FIGS. 8B and 8C , when a command CMD 1  is inputted through the common command pins COMMAND PINs from the external controller  710  of  FIG. 7 , the command decoders  210 _ 0 ,  210 _ 1 , and  210 _ 2  of the respective chips may decode the command CMD 1  and generate the mode enable signal TEST_MD and the mode signal TM_CODE&lt;0:n&gt;. Some of bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; of the mode signal TM_CODE&lt;0:n&gt; may have a value of 11 indicating the common test mode. Since the mask enable signal MASKEN is deactivated at the initial stage, the command controllers  230 _ 0 ,  230 _ 1 , and  230 _ 2  of the respective chips may output the mode enable signal TEST_MD as the test mode enable signal TM_EN. The test controllers  250 _ 0 ,  250 _ 1 , and  250 _ 2  of the respective chips may activate the common test mode signal TM_MASK in response to the test mode enable signal TM_EN and the bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; of the mode signal TM_CODE&lt;0:n&gt;. Thus, the respective semiconductor chips may enter the common test mode at step S 810 . All of the semiconductor chips of the MCP may enter the common test mode at the same time. 
         [0076]    When the semiconductor chips enter the common test mode, the data input buffers  220 _ 0 ,  220 _ 1 , and  220 _ 2  of the respective semiconductor chips may be activated in response to the activated common test mode signal TM_MASK, buffer data DATA inputted through the individual data pins DATA I/O PINs, and output the buffered data as internal data DATA_INT. 
         [0077]    When the data DATA inputted to the first semiconductor chip CHIP 0  has a high level logic, the command controller  230 _ 0  of the first semiconductor chip CHIP 0  may activate the mask enable signal MASKEN at step S 820 . On the other hand, since the data DATA inputted to the second and third semiconductor chips CHIP 1  and CHIP 2  have a low level logic, the command controllers  230 _ 1  and  230 _ 2  of the second and third semiconductor chips CHIP 1  and CHIP 2  may deactivate the mask enable signal MASKEN. 
         [0078]    Then, when a command CMD 2  for individual test mode setting is inputted through the common command pins COMMAND PINs from the external controller, the command decoders  210 _ 0 ,  210 _ 1 , and  210 _ 2  of the respective chips may decode the command CMD 2  and generate the mode enable signal TEST_MD and the mode signal TM_CODE&lt;0:n&gt;. The command controllers  230 _ 0 ,  230 _ 1 , and  230 _ 2  of the respective semiconductor chips may selectively block the mode enable signal TM_EN according to the corresponding mask enable signals MASKEN, and output the test mode enable signal TM_EN. 
         [0079]    When the first semiconductor chip CHIP 0  in which the mask enable signal MASKEN is activated (YES at step S 830 ), the command controller  230 _ 0  may block the mode enable signal TEST_MD and deactivate and output the test mode enable signal TM_EN, at step S 840 . Thus, the test controller  250 _ 0  of the first semiconductor chip CHIP 0  may not generate the test mode signal TM&lt;0:m&gt; for an internal test operation. 
         [0080]    On the other hand, in the case of the second and third semiconductor chips CHIP 1  and CHIP 2  in which the mask enable signal MASKEN is deactivated (NO at step S 830 ), the command controllers  230 _ 1  and  230 _ 2  may activate and output the mode enable signal TEST_MD as the test mode enable signal TM_EN. The test controllers  250 _ 1  and  250 _ 2  of the second and third semiconductor chips CHIP 1  and CHIP 2  may generate the test mode signal TM&lt;0:m&gt; for an internal test operation. Thus, the internal circuits of the second and third semiconductor chips CHIP 1  and CHIP 2  may perform an individual test mode setting operation at step S 850 . For reference, the individual test mode setting operation may be performed to set a voltage for a specific test operation, delay amounts of signals, and a margin for compensating a variable caused by a process difference. 
         [0081]    Then, the data DATA inputted to the first semiconductor chip CHIP 0  may transition from a high level logic to a low level logic. 
         [0082]    Thus, the command controller  230 _ 0  of the first semiconductor chip CHIP 0  may deactivate the mask enable signal MASKEN at step S 860 . 
         [0083]    The individual test mode setting operation may be continuously repeated until the common test mode ends (NO at step S 870 ). 
         [0084]    For example, when the data DATA Inputted to the second and third semiconductor chips CHIP 1  and CHIP 2  have a high level logic, the command controllers  230 _ 1  and  230 _ 2  of the second and third semiconductor chips CHIP 1  and CHIP 2  may activate the corresponding mask enable signals MASKEN at step S 820 . Since the data DATA inputted to the first semiconductor chip CHIP 0  has a high level logic, the command controller  230 _ 0  of the first semiconductor chip CHIP 0  may deactivate the mask enable signal MASKEN. 
         [0085]    Then, when another command CMD 3  for individual test mode setting is inputted through the common command pins COMMAND PINs from the external controller, the command decoders  210 _ 0 ,  210 _ 1 , and  210 _ 2  of the respective chips may decode the command CMD 3  and generate the mode enable signal TEST_MD and the mode signal TM_CODE&lt;0:n&gt;. The command controllers  230 _ 0 ,  230 _ 1 , and  230 _ 2  of the respective semiconductor chips may selectively block the mode enable signal TM_EN according to the corresponding mask enable signals MASKEN, and output the test mode enable signal TM_EN. 
         [0086]    When the second and third semiconductor chips CHIP 1  and CHIP 2  in which the mask enable signal MASKEN is activated (YES at step S 830 ), the command controllers  230 _ 1  and  230 _ 2  may block the mode enable signal TEST_MD and deactivate and output the test mode enable signal TM_EN, at step S 840 . Thus, the test controllers  250 _ 1  and  250 _ 2  of the second and third semiconductor chips CHIP 1  and CHIP 2  may not generate the test mode signal TM&lt;0:m&gt; for an internal test operation. 
         [0087]    On the other hand, in the case of the first semiconductor chip CHIP 0  in which the mask enable signal MASKEN is deactivated (NO at step S 830 ), the command controller  230 _ 0  may activate and output the mode enable signal TEST_MD as the test mode enable signal TM_EN. The test controller  250 _ 0  of the first semiconductor chip CHIP 0  may generate the test mode signal TM&lt;0:m&gt; for an internal test operation. Thus, the Internal circuit of the first semiconductor chip CHIP 0  may perform an individual test mode setting operation at step S 850 . 
         [0088]    Then, the data DATA Inputted to the second and third semiconductor chips CHIP 1  and CHIP 2  may transition from a high level logic to a low level logic. Thus, the command controllers  230 _ 1  and  230 _ 2  of the second and third semiconductor chips CHIP 1  and CHIP 2  may deactivate the mask enable signal MASKEN at step S 860 . 
         [0089]    Then, when a command CMD 4  is inputted through the common command pins COMMAND PINs from the controller, the command decoders  210 _ 0 ,  210 _ 1 , and  210 _ 2  of the respective chips may decode the command CMD 4  and generate the mode enable signal TEST_MD and the mode signal TM_CODE&lt;0:n&gt;. Each of bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; may have a value of 0 indicating that the common test mode ends. The test controllers  250 _ 0 ,  250 _ 1 , and  250 _ 2  of the respective chips may deactivate the common test mode signal TM_MASK in response to the bits TM_CODE&lt;0&gt; and TM_CODE&lt;1&gt; of the mode signal TM_CODE&lt;0:n&gt;. Thus, all of the semiconductor chips of the MCP may end the common test mode (YES at step S 870 ). 
         [0090]    Then, when the semiconductor chips enter the test mode and the command CMD indicating the test operation is inputted through the common command pins COMMAND PINs of the respective semiconductor chips, the command CMD may be decoded to activate the buffer enable signal BUFEN. The data input buffers  220 _ 0 ,  220 _ 1 , and  220 _ 2  of the respective semiconductor chips may be enabled in response to the activated buffer enable signal BUFEN, receive data DATA inputted through the individual data pins DATA I/O PINs, and perform a test operation according to preset individual test modes, at step S 880 . 
         [0091]    In the embodiment of the present invention, although the same command is Inputted to the respective semiconductor chips of the MCP at the same time, the commands of the semiconductor chips other than the test target may be selectively blocked. Thus, only the semiconductor chip corresponding to the test target may be Independently tested. 
         [0092]    Furthermore, the semiconductor chips of the MCP may be independently tested without separate pads added to the respective semiconductor chips. Thus, the area efficiency of the MCP may be improved. 
         [0093]    Although various embodiments have been described for Illustrative purposes, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.