JP4608178B2 - Electronic device and electronic device forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic device having a plurality of protruding electrodes (bumps) or an electronic device forming method in which a bonding method between protruding electrodes is improved.
[0002]
[Prior art]
As a conventional technique for joining electrodes included in an electronic device, Japanese Patent Laid-Open No. 2002-289768 (Patent Document 1) discloses a semiconductor device.
[0003]
FIG. 5 shows an embodiment described in Patent Document 1, and the bump electrode 121 of the second semiconductor chip 102 is bonded onto the first semiconductor chip 101 having the bump electrode 111 formed on the surface. The COC type is formed. The bump electrodes 111 and 121 of the first and second semiconductor chips 101 and 102 are each made of a first metal having a relatively high melting point such as Au, and the joint portions of the bump electrodes 111 and 121 are the first metal. Formed of an alloy layer 103 of the second metal and the second metal, and the second metal is made of a material that can be melted at a temperature lower than the melting temperature of the first metal and alloyed with the first metal. Is described.
[0004]
Japanese Patent Application Laid-Open No. 11-121687 (Patent Document 2) discloses a technique for reliably conducting and connecting semiconductor chips.
[0005]
Furthermore, Japanese Patent Laid-Open No. 11-163051 (Patent Document 3) states that “a plurality of semiconductor chips are stacked in the thickness direction, and electrode pads provided on the stacked surface of the semiconductor chips are anisotropic. A mounting structure of a semiconductor chip electrically bonded through a conductive film, wherein the electrode pad has a conductive protective layer on the surface, and the semiconductor chip is used for wire bonding in a region that is not a laminated surface. A semiconductor chip mounting structure is disclosed in which the electrode pad for wire bonding also has the conductive protective layer on the surface thereof.
[0006]
In such a conventional technique, it is assumed that a metal having the same hardness is used for two opposing electrodes to be joined.
[0007]
In any conventional technique, two opposing electrodes to be bonded have the same bonding area. That is, when it sees about a joint surface, two electrodes on the upper and lower sides have the same planar shape.
[0008]
[Patent Document 1]
JP 2002-289768 A (first page, FIG. 1)
[0009]
[Patent Document 2]
Japanese Patent Application Laid-Open No. 11-121687 (first page, FIG. 2)
[0010]
[Patent Document 3]
Japanese Patent Laid-Open No. 11-163051 (first page, FIG. 1)
[0011]
[Problems to be solved by the invention]
However, when an excessive force is applied between the substrates above and below the joined electrodes, the two opposing electrodes that are joined have the same hardness, so both electrodes collapse together. Can occur. As a result, the substrate having the crushed electrode is also mechanically strained, resulting in inconvenience that the electric circuit is damaged and the performance is deteriorated.
[0012]
Further, in the conventional technique, since the joining surface shapes of the joined electrodes are the same, there arises a problem that the joining strength between the electrodes changes due to the bump position deviation. Therefore, it is necessary to strictly manage the joining conditions, which is a problem in the manufacturing process.
[0013]
Therefore, in view of the above points, an object of the present invention is to provide an electronic device and a method for forming an electronic device that eliminates the drawback of causing mechanical distortion in both substrates due to simultaneous damage of two bonded electrodes. It is to provide.
[0014]
Another object of the present invention is to provide an electronic device and an electronic device forming method that facilitates management of bonding conditions by making the bonding strength constant regardless of the deviation amount of the bump position.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention according to claim 1 is directed to an electronic device formed by bonding opposing electrodes respectively provided on a first substrate and a second substrate. The substrate is a silicon IC substrate, and has a first hardness formed on the first substrate and is made of a first gold made by coating a metal surface containing Ni, Ti, Cr, W, etc. with Au. A projecting electrode, and the second substrate is a silicon wiring substrate, and includes a second gold projecting electrode made of only Au having a second hardness formed on the second substrate , first the first hardness at the gold projecting electrode, when measured by a micro Vickers hardness measurement method, the second rather high compared to the hardness of the second gold projecting electrode, the first The bondable area of the gold protruding electrode is determined so that the second gold protruding electrode can be bonded. The first gold protruding electrode and the second gold protruding electrode are fixed by thermocompression bonding or ultrasonic bonding so as to be larger than the possible area, and the first substrate and the second When joining the substrates, only the second gold protruding electrode having the second hardness is crushed and the first gold protruding electrode having the first hardness is not crushed. The first substrate is prevented from being mechanically strained .
[0019]
According to a second aspect of the present invention, in the method for forming an electronic device formed by bonding opposing electrodes provided on the first substrate and the second substrate, respectively, the first substrate is a silicon IC substrate. the on the first substrate having a first hardness, Ni, Ti, Cr, the surface of the metal containing and W to form a first gold protruding electrodes coated with Au, the second The substrate is a silicon wiring substrate, a second gold protruding electrode made only of Au having a second hardness is formed on the second substrate , and the first gold protruding electrode in the first gold protruding electrode is formed . the hardness, when measured by a micro Vickers hardness measurement method, the second rather high compared to the hardness of the second gold projecting electrode, is bondable area of the first gold projecting electrode, To be larger than the bondable area of the second gold protruding electrode, The first gold protruding electrode and the second gold protruding electrode are fixed by thermocompression bonding or ultrasonic bonding, and the second substrate is bonded to the second substrate at the time of bonding the first substrate and the second substrate. Only the second gold protruding electrode having a hardness of crushes, and the first gold protruding electrode having the first hardness is not crushed. It is characterized by preventing the occurrence of distortion .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0024]
FIG. 1A shows a cross-sectional configuration of an electronic device according to an embodiment to which the present invention is applied. In this figure, 2 is a first substrate, 4 is a second substrate, 6 is a first gold protruding electrode (hereinafter referred to as a first Au bump), and 8 is a second gold protruding electrode ( Hereinafter, this is referred to as a second Au bump). Here, when measured by the micro Vickers hardness measurement method, the hardness of the first Au bump 6 is higher than the hardness of the second Au bump 8. Further, in order to fix the first and second Au bumps 6 and 8, a bonding technique using thermocompression bonding or ultrasonic bonding is used.
[0025]
FIG. 1B is an explanatory view showing a state before the first and second Au bumps 6 and 8 are fixed. In this figure, S1 indicates the bondable area of the first Au bump 6. S <b> 2 indicates a bondable area of the second Au bump 8.
Here, the shapes of both bumps are set so that S1> S2.
[0026]
Examples of the first substrate 2 include silicon (IC, silicon wiring substrate), GaAs (Hall element, LED, transistor), GaP chip (LED), crystal (vibrator, filter), lithium tantalate (SAW filter). ) Etc. are used. As the second substrate 4, for example, silicon (IC, silicon wiring substrate), printed wiring board, ceramic substrate, TAB substrate, polyimide film substrate, or the like is used.
[0027]
FIG. 2 is an explanatory diagram showing a cross-sectional structure of the first Au bump 6. In this figure, three types of structures are illustrated. That is, the first Au bump shown as 6A is an electrode containing Ni, Ti, Cr, W, etc. inside gold. The 1st Au bump shown as 6B is an electrode formed by coat | covering gold | metal | money only to the joint surface side among the surfaces of these metals whose hardness is higher than gold. The 1st Au bump shown as 6C is an electrode formed by coat | covering gold | metal | money on the whole surface of these metals whose hardness is higher than gold | metal | money.
[0028]
FIG. 3 shows an electronic device according to another embodiment. In this figure, 12 is a first substrate, 14 is a second substrate, 16 is a first gold protruding electrode (first Au bump), 18 is a second gold protruding electrode (second Au Au bump). Similar to the embodiment shown in FIG. 1, when measured by the micro Vickers hardness measurement method, the hardness of the first Au bump 16 is higher than the hardness of the second Au bump 18. In order to fix these first and second Au bumps 16 and 18, a bonding technique using thermocompression bonding or ultrasonic bonding is used. Further, as in the embodiment shown in FIG. 1, the area of the bondable plane that the first Au bump 16 has is larger than the area of the bondable plane that the second Au bump 18 has.
[0029]
In the embodiment shown in FIG. 3, unlike the embodiment shown in FIG. 1, the second Au bump 18 is not located at the central portion of the first Au bump 16. That is, when viewed from the embodiment shown in FIG. 1, in FIG. 3, the bump position is deviated. However, as long as the bonding surface of the second Au bump 18 is included in the bonding surface of the first Au bump 16, there is an advantage that the bonding strength between the two bumps does not change.
[0030]
FIG. 4 is an explanatory diagram for specifically explaining the effect of the present invention. In the conventional example, when a large force is applied between the first substrate and the second substrate, the two Au bumps are crushed together, so that mechanical distortion also occurs in each substrate. Thus, the conventional example has a problem in reliability in terms of mechanical strength. On the other hand, in the present invention, only the second Au bump, which is weak in hardness, is crushed and the first Au bump is not crushed, so the first substrate is not damaged. In other words, only the second substrate receives damage to the substrate due to the collapse of only the second Au bump.
[0031]
In addition, since the softer electrode (= second Au bump) having a smaller area is damaged, the damage area of the second substrate can be further narrowed.
[0032]
Furthermore, since the bondable plane area (S2: see FIG. 1B) in the second Au bump is smaller than the bondable plane area (S1) in the first Au bump, even if the bump position shift occurs, There is no adverse effect on the bonding strength between the two Au bumps. As a result, in the present invention, management of joining conditions becomes easy.
[0033]
【The invention's effect】
As described above, according to the present invention, it is possible to eliminate the disadvantage that the two gold protruding electrodes that are joined are damaged at the same time, thereby causing mechanical distortion in both substrates. In addition, according to the present invention, it is possible to easily manage the bonding conditions by making the bonding strength constant regardless of the deviation amount of the bump position.
[Brief description of the drawings]
FIG. 1 is a cross-sectional configuration diagram of an electronic device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a cross-sectional structure of a first gold protruding electrode (first Au bump).
FIG. 3 is a cross-sectional configuration diagram showing an electronic device according to another embodiment.
FIG. 4 is an explanatory diagram for specifically explaining the effect of the present invention.
FIG. 5 is a diagram showing an embodiment described in Patent Document 1.
[Explanation of symbols]
2 First substrate 4 Second substrate 6 First gold protruding electrode (first Au bump)
8 Second gold protruding electrode (second Au bump)

Claims (2)

In an electronic device formed by bonding opposing electrodes provided on the first substrate and the second substrate,
The first substrate is a silicon IC substrate, and has a first hardness formed on the first substrate , and a metal surface containing Ni, Ti, Cr, W, etc. is coated with Au . 1 gold protruding electrode;
The second substrate is a silicon wiring substrate, and includes a second gold protruding electrode made of only Au having a second hardness formed on the second substrate ,
First hardness in the first gold protruding electrodes, as measured by micro Vickers hardness measurement method, rather high compared to the second hardness at the second gold projecting electrode,
The first gold protruding electrode and the second gold protruding electrode so that a bondable area of the first gold protruding electrode is larger than a bondable area of the second gold protruding electrode; The gold protruding electrode is fixed by thermocompression bonding or ultrasonic bonding,
When the first substrate and the second substrate are joined, only the second gold protruding electrode having the second hardness is crushed, and the first gold protruding shape having the first hardness is collapsed. An electronic device characterized in that mechanical distortion is prevented from occurring in the first substrate by preventing the electrodes from collapsing . In the method for forming an electronic device formed by bonding opposing electrodes provided on the first substrate and the second substrate, respectively,
The first substrate is a silicon IC substrate, a first gold having a first hardness on the first substrate and having a metal surface containing Ni, Ti, Cr, W, etc. coated with Au. Forming a protruding electrode,
The second substrate is a silicon wiring substrate, to form a second gold projected electrodes composed only Au having a second hardness on the second substrate,
First hardness in the first gold protruding electrodes, as measured by micro Vickers hardness measurement method, rather high compared to the second hardness at the second gold projecting electrode,
The first gold protruding electrode and the second gold protruding electrode so that a bondable area of the first gold protruding electrode is larger than a bondable area of the second gold protruding electrode; The gold protruding electrode is fixed by thermocompression bonding or ultrasonic bonding,
When the first substrate and the second substrate are joined, only the second gold protruding electrode having the second hardness is crushed, and the first gold protruding shape having the first hardness is collapsed. A method of forming an electronic device , characterized in that mechanical distortion is prevented from occurring in the first substrate by preventing the electrodes from collapsing .

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