Abstract:
The present invention provides an integrated circuit with high-frequency signals immune from noises. The integrated circuit has a chip having a first pad and a plurality of second pads, wherein an AC signal and DC signals are transmitted through the first pad and the second pads respectively, a substrate having a first finger and a plurality of second fingers, a first conducting line connected between the first pad and finger respectively of the chip and substrate, and a plurality of second conducting lines connected between the second pads and fingers respectively of the chip and substrate, and surrounding the first conducting line.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to an integrated circuit and a manufacturing method thereof, particularly to an integrated circuit with internal signals immune from noises and a manufacturing method thereof.  
           [0003]    2. Description of the Prior Art  
           [0004]    In an integrated circuit manufacturing process, gold lines are bonded to pads on a chip and fingers on a substrate before molding. Thus, the solder balls or pins of the substrate for connection and signal transmission with external circuits are electrically connected to the pads of the chip.  
           [0005]    [0005]FIG. 1A is a diagram showing an integrated circuit with bonded gold lines arranged conventionally. The integrated circuit comprises a substrate  11 , a chip  12  and gold lines  13   1 ˜ 13   12 . The chip  12  has 12 pads  121  through which 3 ground signals GND 1 ˜GND 3 , 6 data signals D 1 ˜D 6 , one clock signal CLK and 2 strobe signals S 1 ˜S 2  are transmitted. The pads  121  are electrically connected to fingers  111  on the substrate  11 . The substrate  11  further comprises a ground ring  112  and power ring  113 .  
           [0006]    [0006]FIG. 1B is a diagram showing a cross-section of the gold lines  13   1 ˜ 13   12  along a line AA′ in FIG. 1A. The strobe signals S 1  and S 2  are transmitted through the gold lines  13   1  and  13   4 , the clock signal CLK is transmitted through the gold line  13   2 , the ground signals GND 1 ˜GND 3  are transmitted through the gold lines  13   3 ,  13   9  and  13   12 , and the data signals D 1 ˜D 6  are transmitted through the gold lines  13   5 ˜ 13   8 ,  13   10  and  13   11 .  
           [0007]    However, noises are easily generated in the gold lines carrying AC signals such as the clock, strobe and data signals since they interfere with each other, especially for signals with high frequency. The conventional arrangement does not make a proper separation of the gold lines carrying the AC signals from each other. Additionally, the fingers on the substrate are arranged in one single row, which results in small pitches between the gold lines. This increases the probability of improper contact of two adjacent gold lines when molding.  
         SUMMARY OF THE INVENTION  
         [0008]    Therefore, the object of the present invention is to provide an integrated circuit and a manufacturing method thereof wherein gold lines carrying AC signals are separated, each of them is surrounded by gold lines carrying DC signals and the probability of improper contact of gold lines is decreased by large pitches between the lines.  
           [0009]    The present invention provides an integrated circuit with high-frequency signals immune from noises. The integrated circuit has a chip having a first pad and a plurality of second pads, wherein an AC signal and DC signals are transmitted through the first pad and the second pads respectively, a substrate having a first finger and a plurality of second fingers, a first conducting line connected between the first pad and finger respectively of the chip and substrate, and a plurality of second conducting lines connected between the second pads and fingers respectively of the chip and substrate, and surrounding the first conducting line.  
           [0010]    The present invention further provides a method for manufacturing an integrated circuit comprising the steps of providing a substrate and a chip having a first pad and a plurality of second pads, wherein an AC signal and DC signals are transmitted through the first pad and the second pads respectively, forming a first and a plurality of second fingers on the substrate, bonding a first conducting line to the first pad and finger, and bonding to the second pads and fingers a plurality of second conducting lines surrounding the first conducting line. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    The following detailed description, given by way of example and not intended to limit the invention solely to the embodiments described herein, will best be understood in conjunction with the accompanying drawings, in which:  
         [0012]    [0012]FIG. 1A is a diagram showing an integrated circuit with bonded gold lines arranged conventionally.  
         [0013]    [0013]FIG. 1B is a diagram showing a cross-section of the gold lines  13   1 ˜ 13   12  along a line AA′ in FIG. 1A.  
         [0014]    [0014]FIG. 2A is a diagram showing an integrated circuit with bonded gold lines according to a first embodiment of the invention.  
         [0015]    [0015]FIG. 2B is a diagram showing a cross-section of the gold lines  23   1 ˜ 23   12  along a line AA′ in FIG. 2A.  
         [0016]    [0016]FIG. 3A is a diagram showing an integrated circuit with bonded gold lines according to a second embodiment of the invention.  
         [0017]    [0017]FIG. 3B is a diagram showing a cross-section of the gold lines  33   1 ˜ 33   12  along a line AA′ in FIG. 3A.  
         [0018]    [0018]FIG. 4 is a flow chart showing a method for manufacturing an integrated circuit according to one embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]    [0019]FIG. 2A is a diagram showing an integrated circuit with bonded gold lines according to a first embodiment of the invention. The integrated circuit comprises a substrate  21 , a chip  22  and gold lines  23   1 ˜ 23   12 . The chip  22  has 12 pads  221  through which 6 ground signals GND 1 ˜GND 6 , 3 data signals D 1 ˜D 3 , one clock signal CLK and 2 strobe signals S 1 ˜S 2  are transmitted. The pads  221  are electrically connected to fingers  211  arranged in a row on the substrate  21 . The substrate  21  further comprises a ground ring  212  and power ring  213 .  
         [0020]    [0020]FIG. 2B is a diagram showing a cross-section of the gold lines  23   1 ˜ 23   12  along a line AA′ in FIG. 2A. The strobe signals S 1  and S 2  are transmitted through the gold lines  23   2  and  23   4 , the clock signal CLK is transmitted through the gold line  23   6 , the ground signals GND 1 ˜GND 6  are transmitted through the gold lines  23   1 ,  23   3 ,  23   5 ,  23   7 ,  23   9  and  23   11 , and the data signals D 1 ˜D 3  are transmitted through the gold lines  23   8 ,  23   10  and  23   12 .  
         [0021]    Consequently, in the first embodiment, all the gold lines  23   2 ,  23   4 ,  23   6 ,  23   8 ,  23   10  and  23   12  carrying AC signals are separated from each other by the gold lines  23   1 ,  23   3 ,  23   5 ,  23   7 ,  23   9  and  23   11  carrying DC signals (the ground signal). Each of the gold lines carrying the DC signals is placed between two of the gold lines carrying the AC signals, that is to say, each of the gold lines carrying the AC signals is surrounded by two of the gold lines carrying the DC signals. Thus, the interference between the AC signals and the noises resulting therefrom is prevented.  
         [0022]    [0022]FIG. 3A is a diagram showing an integrated circuit with bonded gold lines according to a second embodiment of the invention. The integrated circuit comprises a substrate  31 , a chip  32  and gold lines  33   1 ˜ 33   12 . The chip  32  has 12 pads  321  through which 9 ground signals GND 1 ˜GND 9 , 1 data signals D 1 , one clock signal CLK and one strobe signal S 1  are transmitted. The pads  321  are electrically connected to fingers  311  arranged in two rows on the substrate  31 . The substrate  31  further comprises a ground ring  312  and power ring  313 .  
         [0023]    [0023]FIG. 3B is a diagram showing a cross-section of the gold lines  33   1 ˜ 33   12  along a line AA′ in FIG. 3A. The fingers  311  are arranged in two rows, whereby the lengths and curvatures of the gold lines  33   1 ˜ 33   12  are different. Therefore, the cross-section of the gold lines comprises two levels. Those bonded to the fingers arranged in the right and left row on the substrate  31  in FIG. 3A are respectively in the top and bottom level. The strobe signals S 1  are transmitted through the gold lines  33   3 , the clock signal CLK is transmitted through the gold line  33   8 , the ground signals GND 1 ˜GND 9  are transmitted through the gold lines  33   1 ,  33   2 ,  33   4 ,  33   5 ,  33   6 ,  33   7 ,  33   9 ,  33   10  and  33   12 , and the data signals D 1  is transmitted through the gold lines  33   11 .  
         [0024]    Consequently, in the second embodiment, all the gold lines  33   3 ,  33   8 , and  33   11  carrying AC signals are separated from each other by the gold lines  33   1 ,  33   2 ,  33   4 ,  33   5 ,  33   6 ,  33   8 ,  33   9 ,  33   10  and  33   12  carrying DC signals (the ground signal). Each of the gold lines carrying the AC signals is surrounded by four of the gold lines carrying the DC signals. Thus, the interference between the AC signals and the noises resulting therefrom is prevented. Further, the pitches between the gold lines are twice as large as those in FIGS. 1B and 2B since the gold lines are placed in two levels with different heights, which decreases the probability of improper contact of the gold lines when molding.  
         [0025]    [0025]FIG. 4 is a flow chart showing a method for manufacturing an integrated circuit according to one embodiment of the invention.  
         [0026]    In step  41 , pads are formed on a chip, wherein the pads for AC signal (data, clock or strobe signals for example) transmitting are surrounded by those for DC signal (ground signal for example) transmitting.  
         [0027]    In step  42 , fingers are formed on a substrate and arranged in two rows. In the row closer to the chip, all the fingers are for electrical connection to the pads for DC signal transmission. In the other row, the fingers for electrical connection to the pads for DC and AC signal transmission are alternatively arranged.  
         [0028]    In step  43 , gold lines are bonded to the pads and fingers for the electrical connections described above. Each of the gold lines carrying the AC signals is surrounded by four gold lines carrying the DC signals since the height of those bonded to the fingers in the row closer to the chip is shorter than the height of those bonded to the fingers in the other row in which the fingers for AC and DC signal transmission are alternatively arranged.  
         [0029]    In the second embodiment, the fingers can be arranged in more than two rows so that each of the gold lines for AC signals is surrounded by more than four DC signal gold lines.  
         [0030]    In conclusion, in the invention, the pads and fingers are specially arranged and the number of the pads for DC signal transmission is increased, whereby each of the gold lines for AC signal transmission is surrounded by more than two of those for DC signal transmission and the pitches between them are also enlarged. Thus, the interference between the AC signals and the noises resulting therefrom is prevented and the probability of improper contact of the gold lines is also decreased.  
         [0031]    While the invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements as would be apparent to those skilled in the art. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.