Patent Publication Number: US-2003227074-A1

Title: Semiconductor device

Description:
BACKGROUND OF THE INVENTION  
       [0001] The present invention relates to a semiconductor device, and particularly to a semiconductor device whose function to be performed is selected by voltage.  
       [0002] When fabricating two kinds of semiconductor devices having partially different functions, design is made such that one semiconductor device has two kinds of functions and either one of the functions can be selected at the time of fabrication.  
       [0003] A semiconductor device of a BGA (Ball Grid Array) package is designed such that a pad for selecting a function by voltage supplied thereto is provided on a semiconductor chip and the voltage for enabling the selected function can be supplied at the time of fabrication. FIGS. 4A and 4B are views of a semiconductor device of a BGA package, FIG. 4A shows a sectional side view, and FIG. 4B shows a fragmentary plan view with an upper package removed. As shown in FIGS. 4A and 4B, the semiconductor device  10  of the BGA package has a multilayer wiring package board  11 , a semiconductor chip  12  mounted on the package board  11 , and a solder ball  13  connected to a mounting board by soldering.  
       [0004] The package board  11  has a pad  11   a  for bonding connection with a bonding wire  14 . The pad  11   a  is connected to the solder ball  13  by multilayer wiring of the package board  11 . The package board  11  also has pads  11   aa  and  11   ab  for extracting a power supply voltage Vdd and a ground GND supplied to the semiconductor chip  12 . The package board  11  also has a hole  11   b  for connecting wiring in each layer.  
       [0005] The semiconductor chip  12  is designed to have two functions. The semiconductor chip  12  has a pad  12   a  connected to the bonding wire  14 , for inputting or outputting a signal. The semiconductor chip  12  also has a function selecting pad  12   aa  for selecting either one of the two functions. The function selecting pad  12   aa  is supplied with the voltage Vdd or the ground voltage GND, whereby the function is selected.  
       [0006] In order to select one of the functions in fabricating the semiconductor device  10  of the BGA package, the pad  11   aa  and the function selecting pad  12   aa  are connected to each other by a bonding wire  14   a . In order to select the other function in fabricating the semiconductor device  10  of the BGA package, the pad  11   ab  and the function selecting pad  12   aa  are connected to each other by a bonding wire  14   b  (dotted line).  
       [0007] Thus, with the semiconductor device of the BGA package, one of the two kinds of functions can be selected by bonding connection at the time of fabrication of the semiconductor device. Incidentally, fabricating two different kinds of semiconductor devices by bonding connection is described as bonding option.  
       [0008] In contrast to the semiconductor device of the BGA package, a semiconductor device of for example a flat package or the like without a multilayer wiring board is designed such that voltage for selecting a function is inputted from a lead frame when the semiconductor device is mounted on a mounting board. FIGS. 5A and 5B are views of a semiconductor device of a flat package, FIG. 5A shows a sectional side view, and FIG. 5B shows a fragmentary plan view with an upper package removed. As shown in FIGS. 5A and 5B, the semiconductor device  20  of the flat package has a package  21 , a semiconductor chip  22 , and a lead frame  23  fixed to the package  21 , for inputting or outputting a signal of the semiconductor chip  22  from or to the outside.  
       [0009] The semiconductor chip  22  is designed to have two functions. The semiconductor chip  22  has a pad  22   a  connected to a bonding wire  24 , for inputting or outputting a signal. The semiconductor chip  22  also has a function selecting pad  22   aa  for selecting either one of the two functions. The function selecting pad  22   aa  is supplied with a voltage Vdd or a ground voltage GND, whereby the function is selected. The function selecting pad  22   aa  is connected to a lead frame  23   a  by a bonding wire  24   a.    
       [0010] In order to select one of the functions in using the semiconductor device  20  of the flat package, the voltage Vdd is supplied to the lead frame  23   a  from the mounting board when the semiconductor device  20  is mounted on the mounting board. In order to select the other function in using the semiconductor device  20  of the flat package, the ground voltage GND is supplied to the lead frame  23   a  from the mounting board.  
       [0011] Thus, in the case where the semiconductor device is without a multilayer board, the voltage to be supplied to the lead frame is determined at the time of mounting the semiconductor device onto the mounting board, whereby one of the two kinds of functions is selected and used.  
       [0012] However, when the semiconductor device as described above is used in an electronic apparatus, it is concerned that the semiconductor device may be used in a manner different from original specifications of the electronic apparatus by isolating the lead frame from the mounting board and inputting a voltage for changing the function of the semiconductor device. Thus, there is a desire for a semiconductor device that allows a function thereof to be selected and determined by bonding connection at the time of fabrication.  
       SUMMARY OF THE INVENTION  
       [0013] The present invention has been made in view of the above, and it is accordingly an object of the present invention to provide a semiconductor device that allows a function thereof to be selected and determined at the time of fabrication.  
       [0014] According to the present invention, there is provided a semiconductor device for selecting a function to be performed by voltage, including: a semiconductor chip having a function selecting pad supplied with one of a first selection voltage or a second selection voltage for selecting a function, a first voltage pad for outputting the first selection voltage, and a second voltage pad for outputting the second selection voltage; and a lead frame bonding-connected to one of the first voltage pad or the second voltage pad and bonding-connected to the function selecting pad, for inputting one of the first selection voltage and the second selection voltage to the function selecting pad.  
       [0015] With such a semiconductor device, the semiconductor chip has the function selecting pad, the first voltage pad, and the second voltage pad, and the first selection voltage of the first voltage pad or the second selection voltage of the second voltage pad is inputted to the function selecting pad by bonding connection thereof with the lead frame. It is therefore possible to select and determine the function at the time of fabrication. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0016]FIG. 1 is a plan view of a semiconductor device according to the present invention with an upper part of a flat package removed;  
     [0017]FIG. 2 is a sectional view of the semiconductor device of FIG. 1;  
     [0018]FIG. 3 is an enlarged view of a function selecting pad and voltage pads in FIG. 1 and a vicinity thereof;  
     [0019]FIGS. 4A and 4B are views of a semiconductor device of a BGA package, FIG. 4A shows a sectional side view, and FIG. 4B shows a fragmentary plan view with an upper package removed; and  
     [0020]FIGS. 5A and 5B are views of a semiconductor device of a flat package, FIG. 5A shows a sectional side view, and FIG. 5B being a fragmentary plan view with an upper package removed. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
     [0021] A preferred embodiment of the present invention will hereinafter be described with reference to the drawings.  
     [0022]FIG. 1 is a plan view of a semiconductor device according to the present invention with an upper part of a flat package removed. FIG. 2 is a sectional view of the semiconductor device of FIG. 1. As shown in FIG. 1 and FIG. 2, the semiconductor device  1  has: a flat package  2 : a lead frame  3  fixed to the flat package  2 , for inputting or outputting a signal from a mounting board; a lead frame  4  fixed to the flat package  2 , for use in selecting a function of the semiconductor device  1 ; a mount  5  fixed on an upper surface of the flat package  2 ; and a semiconductor chip  6  designed to have two functions A and B and mounted on the mount  5 .  
     [0023] The semiconductor chip  6  has pads  6   a  provided on a periphery thereof for inputting and outputting signals. A pad  6   a  is bonding-connected to the lead frame  3  by a bonding wire  7 . The semiconductor chip  6  also has a function selecting pad  6   aa  supplied with a selection voltage for selecting the function A or B and voltage pads  6   ab  and  6   ac  for outputting voltage for selecting functions.  
     [0024] A layout of the semiconductor chip  6  is designed such that a power supply voltage Vdd and a ground GND supplied to the semiconductor chip  6  are outputted to the voltage pads  6   ab  and  6   ac  at the time of mounting the semiconductor device  1  onto the mounting board. It is assumed that the semiconductor chip  6  performs the function A when the voltage Vdd is supplied to the function selecting pad  6   aa , and that the semiconductor chip  6  performs the function B when the ground GND is supplied to the function selecting pad  6   aa.    
     [0025]FIG. 3 is an enlarged view of the function selecting pad and the voltage pads in FIG. 1 and a vicinity thereof. As shown in FIG. 3, when the semiconductor device  1  is fabricated to have the function A, at the time of the fabrication, the lead frame  4  and the function selecting pad  6   aa  are bonding-connected to each other by a bonding wire  7   a , and further the voltage pad  6   ab  and the lead frame  4  are bonding-connected to each other by a bonding wire  7   b . Thereby, when the semiconductor device  1  is mounted on the mounting board, the voltage Vdd is supplied to the function selecting pad  6   aa , and hence the semiconductor device  1  performs the function A.  
     [0026] When the function B is selected in fabricating the semiconductor device  1 , at the time of the fabrication, the lead frame  4  and the function selecting pad  6   aa  are bonding-connected to each other by the bonding wire  7   a , and further the voltage pad  6   ac  and the lead frame  4  are bonding-connected to each other by a bonding wire  7   c  (dotted line). Thereby, when the semiconductor device  1  is mounted on the mounting board, the ground GND is supplied to the function selecting pad  6   aa , and hence the semiconductor device  1  performs the function B.  
     [0027] Thus, the function of the semiconductor device according to the present invention can be selected and determined by the bonding connection at the time of the fabrication.  
     [0028] Further, with an electronic apparatus incorporating the semiconductor device, it is possible to prevent change in specifications of the electronic apparatus through unauthorized functional change by a user who purchased the electronic apparatus, for example.  
     [0029] Incidentally, since the lead frame connected to the function selecting pad is a non-connection lead frame, the lead frame does not need to be extended to the outside of the flat package, and the lead frame may be formed to be of such a size as to be housed inside the package, and fixed.  
     [0030] As described above, according to the present invention, the semiconductor chip has the function selecting pad, the first voltage pad, and the second voltage pad, and the first selection voltage of the first voltage pad or the second selection voltage of the second voltage pad is inputted to the function selecting pad by bonding connection thereof with the lead frame. It is thereby possible to select and determine the function at the time of fabrication.  
     [0031] Since the above description of the preferred embodiments is for illustrative purposes only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims.