JP2003282628A - Bare chip mounting component and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent generation of microcrack, and the like, by not forming a bump on the side of a fragile high frequency semiconductor bare chip of GaAs, or the like, being employed in a portable telephone, or the like, thereby reducing the load when bonding. <P>SOLUTION: The bare chip mounting component comprises a bare chip, i.e., a compound semiconductor device 10, having electrode pads 11 of Au formed on the uppermost surface, and a ceramic wiring board 1 having Au bumps 3 formed on the electrode pads 2. The semiconductor device 10 is subjected to Au-Au bonding through thermocompression not using ultrasonic by touching the electrode pads 11 directly to the Au bumps 3. The load being applied to one Au bump 3 is preferably set at 100 g or less in thermocompression. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bare chip mounting component in which a bare chip is mounted on a substrate by flip chip bonding and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, flip-chip bonding has been mentioned as a mounting technique required for large-capacity, high-speed data communication. In this method, bumps are formed on the bare chip side, electrode pads are formed on the substrate side, and the bare chip is face-down bonded to the substrate surface, not by wire bonding.

Conventionally, a bare chip is directly mounted on a substrate by packaging or face-up by mainly using a wire bonding method, but as the frequency becomes higher, the influence of the wire length of the wire bonding on the characteristics becomes large. As a result, the need for flip-chip bonding that can shorten the wiring length is increasing. In addition, attention has been paid to the miniaturization, thinning, and weight reduction of devices. Examples of the flip chip bonding method include a method using ultrasonic waves, a load, and heat, each of which is properly used depending on a bonding material or the like. The main flip-chip bonding methods are shown below.

(1) When solder is used, the connection is made by heating by reflow.

(2) When a metal such as Au (gold) is used, the connection is made by ultrasonic waves, load and heat. JP 2000
As described in JP-A-232332 and JP-A-2000-306957, Au bumps are formed on the electrodes on the bare chip side by a ball bonding method or a plating method, alignment is performed with the wiring board electrodes, and heat generated using ultrasonic waves is used. Flip chip bonding is performed by pressure bonding.

(3) Thermocompression bonding is performed with a resin such as an anisotropic conductive film interposed. As in JP-A-11-16943, Au bumps are formed on the electrodes on the bare chip side by a ball bonding method, and flip chip bonding is performed by thermocompression bonding using an anisotropic conductive resin or film. As in Japanese Patent Laid-Open No. 2001-257237, Au bumps are formed on the bare chip side or the wiring substrate side by a ball bonding method, and an anisotropic conductive film (ACF) or an anisotropic conductive paste (AC) is used during flip chip bonding.
P) or an insulating resin or the like is used for thermocompression bonding. As in WO98 / 30073, Au bumps are formed on the electrodes on the bare chip side by a ball bonding method, and flip chip bonding is performed by thermocompression bonding using a thermosetting resin.

(4) A metal such as Au is used for connection by load and heat. As in JP-A-5-275491,
Au bumps are formed on both the chip side and the wiring board side by a ball bonding method, the bumps on the wiring board side are flattened by a flattening jig, and then flip chip bonding is performed by load and heat.

[0008]

[Problems to be Solved by the Invention] Using solder (1)
In the case of, the thermal resistance of the solder itself is large, so it is difficult to release the heat generated in the bare chip, which is a semiconductor device, to the wiring board side through the solder bumps. Because it is easy to occur,
There is a problem that the life of the bump is short.

In the case of forming bumps on the bare chip side of (2) to (4), stress is applied to the bare chip by ultrasonic waves to form the stud bumps by the ball bonding method.
There is a possibility that micro-cracks may be generated in a bare chip of a mechanically fragile material such as a compound semiconductor such as GaAs (especially, a thin one having a thickness of about 100 μm). When bumps are formed by the ball bonding method or plating method, the number of processes and the number of handling steps are increased, a dedicated device and jigs and tools are required, which increases stress on the wafer for manufacturing bare chips and chip cost. Is expected to rise.

[0010] As a problem at the time of flip chip bonding,
In the case of (2), since thermocompression bonding with ultrasonic waves is used,
Ultrasonic waves, loads, heat, and loads that are applied to the bare chip semiconductor device itself are large, and microcracks or the like may occur in a thin compound semiconductor device such as GaAs. In cases (3) to (3), since resin (ACF, ACP, NCF, NCP, insulating resin, etc.) is inserted between the bare chip and the wiring board, in a high frequency circuit where a compound semiconductor such as GaAs is used, the dielectric property of the resin The issue is that the rate may affect the characteristics.

Also in the case of (4), since bumps are formed on the bare chip side, there is a possibility of potentially causing microcracks. Further, since the step of flattening with a jig after forming the bumps on the wiring board side is included, the manufacturing cost is increased.

In view of the above points, the present invention reduces load by not forming bumps on the side of a fragile bare chip such as GaAs, which is used for high frequencies (GHz band) of mobile phones, and flip chip bonding. It is an object of the present invention to provide a bare chip mounted component by flip chip bonding which does not require an intervening material such as ACF between the bare chip and the wiring board even in the case of (mounting), and does not use ultrasonic waves, and a manufacturing method thereof. This is effective for bare chips made of brittle materials.

Other objects and novel features of the present invention will be clarified in the embodiments described later.

[0014]

In order to achieve the above object, the bare chip mounted component according to the present invention has an outermost surface of Au.
The bare chip on which the electrode pad is formed and the substrate on which the Au bump is formed are provided, and the bare chip is Au-Au bonded by directly contacting the electrode pad with the Au bump.

In the bare chip mounting component, the bare chip may be a compound semiconductor device, and the substrate may be a ceramic substrate.

In the method of manufacturing a bare chip mounting component according to the present invention, a step of forming Au bumps on the bare chip mounting surface of the substrate, a step of forming an electrode pad with an outermost surface of Au on the bare chip, and the electrode pad being the Au And a step of performing thermocompression bonding in a state of being in direct contact with the bump.

In the method of manufacturing a component mounted with a bare chip, it is preferable that the bare chip is a compound semiconductor device, the substrate is a ceramic substrate, and the load per Au bump is 100 g or less and thermocompression bonding is performed.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a bare chip mounted component and a manufacturing method thereof according to the present invention will be described below with reference to the drawings.

1 to 4, an embodiment of a bare chip mounted component and a method of manufacturing the same according to the present invention will be described. Figure 1
Is an LTCC (low temperaturec)
FIG. 2 is a perspective view showing a wiring substrate 1 and a compound semiconductor device 10 as a bare chip, before flip chip bonding. 2 is an enlarged cross-sectional view of an essential part after flip chip bonding, and FIG. 3 is a compound semiconductor device 10.
4 is an enlarged cross-sectional view showing the electrode film structure of FIG. 4, and FIG. 4 is a process flow chart showing a manufacturing method flow (Au-Au thermocompression bonding method) in the present embodiment.

The embodiments will be described in the order of the process flow diagram of FIG. 4. In the bump forming process # 1, as shown in FIG.
Au bumps 3 are formed on the electrode pads 2 on the bare chip mounting surface of the wiring board 1 by an inexpensive ball bonding method. Au
The bump 3 is used as it is without performing the planarization process. The substrate 1 may be provided with SMD (surface mount component) electrode pads 4 as needed.

On the other hand, the electrode pad surface treatment step # 2 shown in FIG.
Then, in the electrode pad 11 of the compound semiconductor (GaAs etc.) device 10 used for the power amplifier module etc.
u surface treatment. That is, as shown in the electrode film configuration of the compound semiconductor device 10 of FIG.
Etc.) 21, the lower conductor layer (Ti, Cu, etc.) 22, the intermediate conductor layer (Ni, Pt, etc.) 23, and A as the uppermost conductor layer.
The u layer 24 is formed to be the electrode pad 11. This electrode pad surface treatment step # 2 is executed in a wafer state before being separated into individual semiconductor devices 10.

In the chip forming step # 3 of FIG. 4, the wafer after the electrode pad surface treatment in the electrode pad surface treatment step # 2 is subjected to back-grinding, dicing and the like into individual compound semiconductor devices 10 into chips (cut and separated). ) Do.

In the flip chip bonding step # 4 of FIG.
The chip-shaped compound semiconductor device 10 of FIG. 1 is inverted and face down bonding is performed by facing the Au bumps 3 on the substrate side with the electrode pads 11 having an Au outermost surface as shown in FIG. That is, the wiring board 1 and the device 10 are heated and pressed to directly bond the Au bumps 3 and the electrode pads 11 (Au-Au bonding). Its heating,
Do not use ultrasonic vibration at the time of pressurization.

According to the present embodiment, the use of ultrasonic waves at the time of bump formation and bonding on the bare chip side, that is, the compound semiconductor device 10 side is eliminated, and the compound semiconductor device 1
The load applied to 0 can be reduced, and the occurrence of microcracks and the like can be reduced as much as possible. Also,
Since strong bonding is possible, flip chip bonding that does not use ACF, ACP, etc. is possible. The bonding portion is Au-Au bonding between the substrate-side Au bump and the chip-side Au electrode pad, which can be said to be a stable bonding method in terms of electrical characteristics and reliability.

[0025]

EXAMPLES The present invention will be described in detail below with reference to examples.

An embodiment using a compound semiconductor device used for a power amplifier module or the like as a bare chip will be described. In the process of manufacturing a compound semiconductor device, Ti / Ni / Au, Ti / Pt / A as shown in FIG.
u, Cu / Ni / Au, etc., so that the Au layer comes to the outermost surface, the thickness thereof is set to 1000 to 10000Å, and the individual compound semiconductor device 10 as shown in FIG. I chose As the wiring board 1, a 3.5 × 5.5 mm LTCC substrate that can withstand a temperature of 300 ° C. or more at the time of bonding is used, and the electrode pad 11 of the compound semiconductor device 10 and the wiring board 1 are used at the time of flip chip bonding as shown in FIG. The layout is such that the wiring electrodes on the side are aligned. Further, the surface of the electrode pad 2 of the wiring board 1 was also subjected to Au treatment (5000 Å). The diameter of the electrode pad 2 on the wiring board side and the electrode pad 11 on the device side was about 100 μm. Au bumps 3 are formed on the electrode pads 2 of the wiring board 1 by a ball bonding method using heating and ultrasonic waves which are generally used.
The ball bonding method is an inexpensive manufacturing method, and Au bumps can be easily formed in an arbitrary size and shape.
Au is a metal having good thermal conductivity and electrical conductivity, excellent spreadability, and a small ionization tendency, and is suitable for bumps during flip chip bonding.

As shown in FIG. 2, when the wiring substrate 1 having the Au bumps 3 formed thereon and the compound semiconductor device 10 are bonded together, a heating temperature of 300 to 500 ° C. and a time of 1 hour are applied while applying a load of 100 g or less per bump. Thermo-compression bonding was performed in about 30 seconds to enable flip chip bonding. Since the bonding is performed with the load and the heating temperature as described above, the Au bumps are softened by pressure and heat even with respect to the height variation peculiar to the Au bumps and the variation in the thickness direction held by the wiring substrate 1 which is the LTCC substrate. It has been made possible by flip chip bonding that does not require a planarization process. By adopting the above method, the anisotropic conductive film (AC
F), an anisotropic conductive paste (ACP), a non-conductive film (NCF), a non-conductive paste (NCP), an insulating resin, etc. are not used, so that the number of steps is not increased and the manufacturing cost can be suppressed. .

The shear strength test after flip-chip bonding has also confirmed that the compound semiconductor device has a bonding strength at which it breaks. 10 per bump
When a load exceeding 0 g is applied, microcracks may be generated in the compound semiconductor device itself, so a load of 100 g or less per bump is preferable, and the management of the load is important.

As an example, when the electrode of the wiring board and the electrode of the bare chip were joined by the above method, the thermal shock test (-55 ° C.
Connection resistance value after 1000 cycles at
It has been confirmed that the shear strength is the same as the initial strength, and if it is a low-permittivity underfill material (such as an adhesive material provided between the wiring board and the bare chip after bonding) that satisfies the characteristics of the high-frequency circuit, then it will be used as reinforcement It is also possible to use.

Although the embodiments and examples of the present invention have been described above, it should be understood by those skilled in the art that the present invention is not limited thereto and various modifications and changes can be made within the scope of the claims. Would be obvious.

[0031]

As described above, according to the present invention,
The following effects can be achieved.

(1) Even if the bare chip is a very fragile compound semiconductor device used for a power amplifier module or the like, there is no need to directly form bumps on the bare chip side, and the cause of microcracks or the like on the bare chip itself is eliminated. It is possible to reduce.

(2) At the time of flip-chip bonding in which a bare chip is face-down bonded to the wiring board side, ultrasonic waves are not used, and only load and heat are bonded, so that the load on the bare chip such as a compound semiconductor device can be reduced. It is possible.

(3) During the flip-chip bonding, ACF, AC between the electrode pad and the Au bump whose outermost surface is Au.
Since inclusions such as P, NCF, NCP, and insulating resin are not required, it is possible to eliminate the possibility that the inclusions affect the high frequency characteristics.

(4) By flip-chip mounting a bare chip such as a semiconductor device on the wiring board, the wiring length between the wiring board and the bare chip can be extremely shortened, and high frequency can be promoted. .

(5) By controlling the load at the time of flip chip bonding, it is possible to adjust the standoff when inserting the underfill.

(6) Even when an LTCC board is used as the wiring board, the LTCC board is warped, undulated,
Flip-chip mounting that can cope with variations in electrode pad thickness is possible.

(7) Since the bump material is Au, the heat generated in the bare chip of the compound semiconductor device is Au.
It is possible to dissipate heat to the side of a wiring substrate such as a ceramic substrate via the bumps, and it is possible to lower the bare chip temperature.

(8) The wafer is cut and separated to produce individual bare chips, but since bump processing is not required on the wafer side, the cost of the wafer can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a bare chip mounted component and a manufacturing method thereof according to the present invention.

FIG. 2 is an enlarged cross-sectional view of essential parts showing flip chip bonding in the embodiment.

FIG. 3 is an enlarged cross-sectional view showing a bare chip side electrode pad configuration in the embodiment.

FIG. 4 is a process flow chart showing a manufacturing flow of the Au—Au thermocompression bonding process, which is a process of the embodiment.

[Explanation of symbols]

1 wiring board 2 electrode pad 3 Au bump 4 SMD electrode pad 10 Compound semiconductor devices 11 electrode pad 21 wiring material 22 Lower conductor layer 23 Intermediate conductor layer 24 Au layer # 1 bump formation process # 2 electrode pad surface treatment process # 3 Chip process # 4 Flitch-up joining process

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Takaaki Domon             1-13-1, Nihonbashi, Chuo-ku, Tokyo Tea             DC Inc. F-term (reference) 5F044 KK04 KK18 LL15 QQ03

Claims (4)

[Claims] 1. A bare chip having an Au electrode pad formed on its outermost surface and a substrate having an Au bump formed thereon, wherein the bare chip is Au-Au bonded by directly contacting the electrode pad with the Au bump. Bare chip mounted parts characterized by 2. The bare chip mounting component according to claim 1, wherein the bare chip is a compound semiconductor device, and the substrate is a ceramic substrate. 3. A step of forming an Au bump on a bare chip mounting surface of a substrate, a step of forming an electrode pad having an Au outermost surface on a bare chip, and a step of heating the electrode pad in direct contact with the Au bump. A method of manufacturing a bare chip mounted component, comprising a step of crimping. 4. The method of manufacturing a bare chip mounted component according to claim 3, wherein the bare chip is a compound semiconductor device, the substrate is a ceramic substrate, and thermocompression bonding is performed with the load per Au bump being 100 g or less.