JPS62206857A - Forming method for projection-shaped electrode - Google Patents

Abstract

PURPOSE:To simplify an electrode forming process, to improve workability and operating efficiency on the formation of an electrode and to eliminate complicatedness at the time of the exchange of a semiconductor chip by bringing a granular metallic body such as a metallic ball into pressure-contact with a wiring layer formed onto a foundation and fixing the granular metallic body to the wiring layer. CONSTITUTION:A copper ball 51 is brought into pressure-contact with a wiring layer at the position of the formation of an electrode regarding a capillary 47 and a flip chip 53. The copper ball 51 is fastened to the wiring layer by using ultrasonic waves after the pressure contact or at the same time as the pressure contact. The capillary 47 is lifted by a proper quantity after the pressure contact and fixation of the copper ball 51, and a copper wire 43 is gripped by a clamp 45 as the copper wire 43 is left as it is projected to the tip section of the capillary 47 only by desired length. Both the capillary 47 and the clamp 45 are elevated, and the copper wire 43 and the fixed copper ball 51 are separated. Consequently, only the copper ball 51 is bonded and left to the wiring layer. Accordingly, the electrode is shaped by the combination of the simple processes of pressure contacts and fixation, thus improving workability and operating efficiency.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention provides a method for mounting semiconductor chips.
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1-j: no thunder=1-)L! ! l-4-1 (Conventional technology) Conventionally, in order to mount semiconductor chips, semiconductor chips,
A method has been proposed in which protruding electrodes made of copper (Cu) poles and solder (Pb--Sn) are formed on a wiring layer formed on a ground E of a wiring board or other substrate.

FIG. 3 is a sectional view showing a protruding electrode formed by a conventional method. This protruding electrode is formed on the wiring layer 13h provided on the seven-lip chip 11. This wiring layer 13 is generally made of aluminum with silicon added.
T layer (A pattern bad) 17. Oxidized lQ (passivation film) 19. Metal layer as barrier layer 21.23.2
It consists of 5.

This conventional method for forming protruding electrodes will be explained with reference to FIG. 3.

First, the 'MU (P'b-Sn) layer 33 is formed on the wiring layer 13E by plating. At this time, a large number of copper poles 31 are prepared, each of which has a metal (Ni) layer 27 and a metal (gold/Au) layer 28 sequentially formed on their surfaces by pyrolytic plating. This copper pole 31 is normally a fine pole with a diameter of about 125 gm.

Next, the electrode formation position of the wiring layer 13 (A vertical/S1 layer 17
The flip chip 11 is aligned with a metal mask (also referred to as an aperture) provided with a hole at a position corresponding to the portion not covered with the oxide film 19). With this alignment performed, the copper poles 31 described above are poured into the metal mask L and placed one in each hole, so that the copper poles 31 are arranged at all electrode formation positions of the flip chip 11.

After this, with the copper pole 31 placed on the solder layer 33 hill,
The solder layer 33 is melted in a hydrogen atmosphere 2 in a belt furnace, thereby forming a protruding electrode 15 comprising copper poles 31 in the solder layer 33 as shown in cross-section in FIG. 4753.
is formed.

(Problems to be Solved by the Invention) However, in the conventional method described above, the copper poles are positioned using holes provided in the metal mask, but the process involves inserting very fine poles into the holes in the metal mask. The problem is that the formation of the protrusion 1 [pole] cannot be done efficiently and easily because it takes a lot of time to make the hole.

In addition, in order to arrange the poles in 14 [11 layers], it is difficult to align the hole position of the metal mask with the electrode formation position on the ground, and it may be difficult to align the holes on the ground of the flip chip. The problem was that it was bad.

In addition, since the poles are not fixed to the wiring layer, when replacing the semiconductor chip, the poles do not remain biased toward either the semiconductor chip or the wiring board, but instead remain spread out on both the semiconductor chip and the wiring board. However, with the protruding electrodes formed by the conventional method, there is a problem in that replacing the semiconductor chip becomes complicated.

The purpose of this invention is to solve the problems of the conventional method mentioned above, to improve the workability and efficiency of electrode formation by incubating the electrode formation process, and to reduce the complexity of replacing semiconductor chips. An object of the present invention is to provide a method for forming a protruding electrode that can be removed.

(Means for Solving the Problems) In order to achieve this object, according to the method for forming a protruding electrode of the present invention, a wiring layer formed on a semiconductor chip, a substrate, or other suitable base material E is provided. The method is characterized by including a step of bringing a granular metal body such as a metal pole into contact with pressure, and a step of fixing the granular metal body to a wiring layer.

Pressure contact and fixing of the granular metal body may be performed at the same time, or the granular metal body may be pressed into contact with the wiring layer and then fixed while the contact state between the two is maintained. good. The shape of the granular metal body is not limited to the pole shape, and any shape can be used. Also, WA (Cu), gold (Au), aluminum (AIL), and other materials can be used as the forming material of the granular metal body. It can be used as appropriate.

In practicing the invention, it is preferred to make this pressure contact using wire bonding techniques conventionally used to bond wires to IC chips.

Further, in carrying out the present invention, it is preferable to use ultrasonic waves to fix the granular metal bodies.

(Function) According to such a configuration, when forming the protruding electrode, the protruding electrode is formed by a combination of the cylindrical processes of pressurized contact and fixing, without involving the difficult work of inserting the granular metal body into the hole of the metal mask. formation takes place.

Further, according to the configuration of the present invention, by applying the wire punch ink technique described above, it is possible to align the granular metal bodies to the electrode forming positions in the cylinder.

Furthermore, since one granular metal body is fixed to the wiring layer, the granular metal body always remains on the fixed wiring layer when the semiconductor chip is replaced.

(Embodiments) Examples of the present invention will now be described with reference to the drawings. It should be noted that the figures are only schematic illustrations to the extent that the invention can be understood, and the embodiments described below are as follows:
Although preferred specific numerical conditions, materials, and other conditions of this invention are explained below, these are merely examples, and it should be understood that this invention is not limited only to these examples. I want to be understood.

FIGS. 1(A) to 1(F) are explanatory diagrams of the electrode forming process of the example. In this embodiment, a case will be explained in which a conventional wire pointing device is used.

In FIG. 7rSI (A), 41 is a flange, 43 is a copper wire, and the flange 41 is wound with a copper wire 41 having a diameter of 20 gm. Further, 45 indicates a clamp, and 47 indicates a ceramic capillary supported by a pumping arm 49. The copper wire 43 is inserted into the capillary 47 via the clamp 45. At the tip of the copper wire 43, there is a copper hole (granular body) with a diameter of about 100 tiles as a granular metal body.
51 is formed. Here, instead of the copper wire 43,
Gold (Au), aluminum (All) and other metals II! It is also possible to construct a granular metal body using II radiation.

Reference numeral 53 indicates a flip chip, for example, a flip chip, which is provided with a wiring layer on which a protruding electrode is to be formed. This r ground can be a semiconductor chip other than a flip chip, a wiring board, or the like depending on the mounting method.

By the way, in order to bond a wire to an IC chip using a conventional wire bonding device, the end of the wire is first bonded to the bonding butt of the semiconductor chip (first bonding process), and then the other end of the wire is bonded to the bonding butt of the semiconductor chip. The first and second pounds are performed at different times, such as bonding the end to the conductor portion of the wiring board (second bonding process). However, when using a wire bonding machine to carry out this invention, and a second pound at the same position to form a protruding electrode as described in detail below.

When forming protruding electrodes, it is only necessary to press and contact and fix one copper pole 31 at each electrode formation position.Also, in order to avoid damage to the copper pole due to double striking, the first pound is as shown in Fig. 1. As shown in (B) and (C), the copper pole 51 is not pressed into contact with or fixed to the wiring layer (blank firing).

First, by aligning the capillary 47 and the flip chip 53, the copper pole 51 is placed directly on the wiring layer of the 7-lip chip 53, and therefore on the electrode formation position. After aligning these positions, lower the capillary 47 so that the copper pole 51 and the wiring layer do not come into contact with each other (for example, until the copper pole 51 comes to the wiring layer 1zO, 5 mm apart (FIG. 1 CB)). Then, raise the capillary 47 to E (Edict 1 (C)),
Finish the first pound without pounding ffi pole 51.

Next, in the second pound, as shown in FIGS. 1(D) and 1(E), the copper ball 51 is brought into pressure contact with the wiring layer and a preliminary decision is made.

First, while the capillary 47 and the flip chip 53 are held in the same position as at the time of the first pound, the copper pole 51 is pressed into contact with the wiring layer at the electrode forming position. The pressurized contact of the copper pole 51 is with the pounding arm 4
3 and capillary 47 with a load of 50 to too g. After or simultaneously with this pressure contact, the copper pole 51 is fixed to the wiring layer using ultrasonic waves. This fixation is performed by irradiating the copper pole 51, which is in pressurized contact, with ultrasonic waves for only a few seconds m5ec. The wiring layer and the copper pole 5 are connected to each other by pressure contact of the copper pole 51 and at hill wave vibration.
An alloy is formed on the contact surface with copper pole 51, resulting in the formation of an alloy on the contact surface with copper pole 51.
It is thought that the wiring layer and the wiring layer are bonded to each other (Fig. 7JS1 (D)).

After pressurized contact and fixation of the copper pole 51, the capillary 47
A suitable amount of copper wire 43 is raised to the tip of the capillary 47.
The copper wire 43 is held by the clamp 45 while leaving it protruding by a desired length. Next, the capillary 47 and the clamp 45 are both raised L to separate the copper wire 43 and the fixed copper pole 51, and the second pound is completed. As a result, only the copper pole 51 is bonded and remains in the wiring layer (FIG. 1(E)).

Next, as shown in FIG. 1CF), a torch rod 55 is brought close to the tip of the wire 43 protruding from the capillary 47, and a new copper pole 51 is formed at the tip of the copper wire 43 by electric discharge. Thereafter, the torch rod 55 returns the copper pole 51 to a position where it does not interfere with the pressure contact and rI11 determination work at the next electrode forming position.

By repeating the above-described series of operations, all the protruding electrode formation positions of the flip chip 53 are covered with copper poles 5.
1 can be provided to form a protruding electrode.

FIG. 2 is a sectional view showing a protruding electrode formed according to this example. Components that are the same as those shown in FIGS. 1 and 3 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

In the figure, reference numeral 57 indicates a protruding electrode formed on the wiring layer 13. The protruding electrode 57 is formed by covering the copper pole 51 with a metal layer 59. The metal layer 59 is covered with a copper ball 51
It is preferable to perform an electroplating process after fixing the flip chip to the wiring layer 13 (according to electroplating, flip chip 53)
It is possible to easily cover only the electrode forming portion with the metal layer 59 without damaging the portion other than the electrode forming portion. The structure of the protruding electrode 57 can be, for example, a metal layer 57 that is a middle layer made of only solder (Pb-Sn), or a copper pole 51h that has a nickel (Ni) layer, a gold (Au) layer, a solder (Pb) layer, and a nickel (Ni) layer, a gold (Au) layer, and a solder (Pb
-3n) layer may be provided, or a structure may be provided in which only the copper pole 51 is provided without providing the metal layer 57. A suitable configuration may be selected from these configurations depending on the electrical connection Jl of the protruding electrodes when the flip chip 53 is mounted.

Further, the wiring layer 13 provided with the protruding poles 55 is an example of the configuration of the wiring layer, and the configuration of the wiring layer is not limited to this.

According to this embodiment, the step of inserting the copper pole into the hole of the metal mask is eliminated, and improvements in workability and efficiency in forming protruding electrodes can be expected.

Further, according to this embodiment, the wire bonding technique can be used for positioning the copper pole 51 at the electrode forming position instead of using a metal mask as in the conventional case. Therefore, once all the electrode formation positions for one flip chip 53 are set in the wire bonding device, there is no need to perform alignment for each flip chip 53, and from then on, difficult alignment work is required for flip chips 53 of different configurations. Alignment can be easily and efficiently achieved without any complication.

Therefore, the protruding electrode can be formed more easily and efficiently than before.

Further, according to this embodiment, the wiring layer 1 of the flip chip 53
A copper pole 51 is fixed to 3. Flip chip 5
Since all the copper poles 51 provided on the flip chip 53 can be removed together with the flip chip 53 when replacing the flip chip 53, the replacement work is not complicated and can be easily performed.

In the embodiment described above, the first pound is used to pound the copper pole, and the second pound is used to pound the copper pole. However, the first pound may be used to pound the copper pole, and the second pound may be used to pound the copper pole.

In addition, in the embodiment described above, the wire bonding apparatus described in E was applied to carry out the present invention, and one copper pole was bonded in step 2 of the step of bonding the copper pole and the step of performing blank bonding. However, it is also possible to use a device that pounds the copper pole at about 1F without dry firing.

(Effects of the Invention) As is clear from the above description, according to the method for forming a protruding electrode of the present invention, forming a protruding electrode involves the difficult work of inserting a granular metal body into a hole in a metal mask. First, since electrode formation is performed by a combination of simple steps of pressurized contact and fixing, improvements in workability and work efficiency can be expected.

Further, the wire bonding technique for bonding wires to the IC chip can be applied to align the granular metal bodies to the electrode formation positions, and therefore the alignment can be performed more easily and efficiently than before. As a result, the workability and efficiency of electrode formation can be improved.

Further, since the granular gold 1 is fixed to the wiring layer in which the protruding electrodes are to be formed, the replacement work of the semiconductor chip is not complicated and can be easily performed.

[Brief explanation of the drawings] Figure 7JS1 is an explanatory diagram of the embodiment of this invention, 7Jt
The IZ diagram is a cross-sectional view showing a protruding electrode formed in the example, and FIG. 3 is a cross-sectional view illustrating a conventional method for forming a protruding electrode. l3... Wiring layer, 51... Granular metal body 5
3... Base, 57... Protruding electrode. Patent Applicant: Oki Denki Chogyo Co., Ltd. Agent Takashi Ogaki/J Sei Nc/qI f7 Yami 5 I/9 f (/ Oxidation I! ￥ (Ha0. Ashihe - Silane R Satoshi) 2
f, 2J, 2f Metal layer 57° missing B Fudensu 57 Metal A lol □ Latte 77, according to II column, foundation, 14th ζ, translation 1 mo)
``Oga no Ishikuni Figure 2 C Hessy procedural amendment January 20, 1988 Director General of the License Agency Black 1) Retraction speed Indication of property 1985 patent application 04841, name of invention Formation of protruding electrodes Relationship with the person who corrects the method Patent applicant's office (〒-105) 1-7-12 Toranomon, Minato-ku, Tokyo (029) Oki Electric Industry Co., Ltd. Representative Nankai Hashimoto 〒170 廿 (988) 5583, 1-20-5 Higashiikebukuro, Toshima-ku, Tokyo Contents of detailed description of the invention and drawings in the subject subscript As attached (1), page 2 of the specification, lines 8-9, Page 3, line 5 and lines 8-9, page 4, line 5, page 7, line 18, page 8, lines 19 and 20, page 9, line 11, page 11, line 1 and lines 13-14, page 12, lines 2-3, line 14,
Lines 16 and 17-18, page 13, line 2, 3-
Correct "flip chip" in lines 4, 4 and 5 to "semiconductor chip 1." (2), same page 7, lines 18-20, "other than flip chip... . . . "Wiring boards and others" is corrected to "Wiring boards and others other than semiconductor chips J." (3), "Copper pole 31" on page 8, line 14 of the same page is corrected to "Copper pole 51j." (4 ) 0 times, "metal layer 57" in the first line of page 12 is corrected as r metal layer 59J, and "protruding electrode 55" in the fifth line of the same page is corrected as "protruding electrode 51j." (5) Figure 1 (A) of drawing 0 is corrected as shown in the attached correction diagram.

Claims (3)

[Claims] (1) When forming a protruding electrode on a wiring layer formed on a base, a step of bringing a granular metal body into pressure contact with the wiring layer, and a step of fixing the granular metal body to the wiring layer. A method for forming a protruding electrode, the method comprising: (2) The method for forming a protruding electrode according to claim 1, wherein the pressure contact is performed using a wire bonding technique. (3) The method for forming a protruding electrode according to claim 1, wherein the fixing is performed using ultrasonic waves.