JP3351091B2 - Semiconductor device mounting method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for mounting a semiconductor device mounted face-down.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 3-108734 discloses an example of a face-down flip-chip mounting method in which bumps of a semiconductor chip are joined to wiring electrodes of a wiring board. According to the publication, after bonding the bump to the wiring electrode of the wiring board, a resin liquid is injected into a gap between the semiconductor chip and the wiring board, and the resin liquid is cured to protect the electrode surface and the like, It discloses that the joining strength is improved. Further, the above publication discloses that a resin liquid is previously adhered to an area to be a gap between a semiconductor chip and a wiring board before the bump is bonded to a wiring electrode of the wiring board, and the resin liquid is caused at the time of bump bonding. Fill the gap with this resin liquid, cure this resin liquid to protect the electrode surface, etc.
And that the joint strength between the two is improved.

[0003]

However, the above-mentioned conventional resin liquid filling method has the following problems.
First, in the injection of the resin liquid after the thermocompression bonding of the bumps, the gap between the semiconductor chip and the wiring board is narrow, so that the injection of the resin liquid is not easy, and the injection time becomes long or bubbles (voids) are formed inside. Was involved.

On the other hand, in a method in which a resin liquid is previously adhered to a wiring board or a semiconductor chip, and the resin liquid is pushed and spread at the time of thermocompression bonding of the bumps so that the gap is filled with the resin liquid, There is a possibility that the resin liquid wraps around between the wiring electrodes and leads to defective bonding of the bumps. In particular,
Normally, since a filler made of small pieces of glass is mixed into the resin liquid, the filler may bite between the bumps and the wiring electrodes, which may cause a bonding failure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method of mounting a semiconductor device capable of facilitating the injection of a resin solution without deteriorating the bondability between a bump and a wiring electrode. For that purpose.

[0006]

According to the present invention, there is provided a method of mounting a semiconductor device, comprising: a chip mounting step of bringing a soft projection electrode formed on a connection electrode surface of a semiconductor chip into contact with a connection electrode of a wiring board; , by pressing the connecting electrodes of the wiring substrate by heating the soft protruding electrode at a temperature of less than its melting point, it is plastically deforming the soft protrusion electrodes,
A first bonding step of reducing the height and bonding to a connection electrode of the wiring board; a resin liquid injection step of subsequently injecting a resin liquid into a gap between the semiconductor chip and the wiring board; By heating the electrode under a temperature condition lower than its melting point and pressing the electrode against the connection electrode of the wiring board, the soft projection electrode is further plastically deformed, the height is further reduced, and the connection between the soft projection electrode and the connection electrode of the wiring board is reduced. to strengthen the bonding, then, it is characterized in that the resin solution and a late joining step Ru cured with heat.

[0007] According to a first aspect, implement the resin injection step while sustaining the plastic deformation during the later of the previous term bonding step and the start of the late joining step.

[0008]

According to the present invention, after a soft bump electrode (hereinafter, also referred to as a bump) of a semiconductor chip is brought into contact with a connection electrode of a wiring board, the bump is bonded to the wiring electrode by thermocompression bonding.
The first bonding step for bonding is performed, and then, a resin liquid is injected into a gap between the semiconductor chip and the wiring board, and then the bonding between the bump and the wiring electrode is further strengthened by thermocompression bonding again.
A late bonding step is performed to strengthen the bonding . Thereafter, the resin liquid is cured to bond the chip and the wiring board and to seal the bumps and the electrodes.

According to the present invention, since the resin liquid is injected before the completion of the thermocompression bonding of the bumps, the gap into which the resin liquid is injected can be made much wider than before, and the injection of the resin liquid becomes easier and the air bubbles are reduced. Can be prevented, and the injection time can be shortened. Also, according to the present invention, before the resin liquid is injected , the bonding between the wiring electrode of the wiring board and the bump is opened.
Since starting, less likely to be mediated resin liquid between the bump and the wiring electrodes, it is possible to improve the bonding properties of both. In particular, even when the resin liquid contains a hard filler, the filler hardly bites between the bump and the wiring electrode. This is because, even if there is a filler in the space near the contact area between the bump and the wiring electrode, the cross section of the space in the direction of plastic deformation in the process of plastic deformation of the bump has a substantially triangular shape. This is because the filler and the resin are naturally extruded from the neighboring space to the outside because the neighboring space is lost from the contact area side. In contrast, when the resin liquid is applied to the bump or the wiring electrode before the bump is brought into contact with the wiring electrode, such a pushing force does not sufficiently act near the apex of the bump, and the resin liquid or the filler may not be applied. There is a case where it remains and hinders bonding.

[0010]

[0011]

[0012]

【Example】

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings. A method for mounting the semiconductor device according to the present embodiment will be described with reference to FIG. FIG. 1A shows a state before the bumps 3 of the semiconductor chip (IC chip) 2 are thermocompression-bonded on the glass substrate 1, and FIG. 3 shows a state in which the resin liquid 4 is injected after the thermocompression bonding of the bump 3 is partially performed, and FIG. 1C shows that the thermocompression bonding of the bump 3 is completed after the resin liquid injection. The latter state is shown.

In FIG. 1A, a bump 3 is a solder bump and is formed by plating. The bump 3 may be a bump made of a soft metal such as gold, copper, tin, or the like. May be wetted with a metal bath to form bumps. FIG. 2 shows a sectional view of the bump 3 before thermocompression bonding. An aluminum electrode 23 is formed on the surface (the lower surface in FIG. 2) of the IC chip 2 as a connection electrode on the chip side.
Its surface is covered with a passivation layer 24.
Further, a part of the aluminum electrode 23 is exposed, and a barrier metal 25 made of chromium or titanium is formed on the aluminum electrode 23 in this exposed part. Barrier metal 25
A copper bump 31 is formed thereon, and a solder bump 32 is formed on the surface of the copper bump 31. Solder bump 3
For Pb-63Sn (eutectic solder), the melting point of this solder is 183 ° C. Bump 3
, That is, the total height Ho of the copper bumps 31 and the solder bumps 32 was 100 μm before thermocompression bonding.

In the manufacturing process, after the barrier metal 25 is deposited, continuous plating of copper and solder is performed, and the solder bumps 32 are reflowed at 250 ° C. in an inert gas atmosphere furnace so that the soft bump electrodes ( The solder bumps 32 of the (bump) 3 may be hemispherical. FIG. 3 shows a glass substrate (wiring substrate) 1 before bonding.

A conductive pattern 10 is formed on the glass substrate 1 as a connection electrode on the chip side. Conductive pattern
The iron 10 has a three-layer structure, and has an ITO (indium tin oxide) layer 11 and a nickel layer 12 on soda glass.
And the gold layer 13 are sequentially laminated. This laminated structure,
It is formed by depositing or plating ITO / Ni / Au. Here, the gold layer 13 on the surface is an antioxidant for the ITO layer 11 and the nickel layer 12 as the wiring base material.

Next, the steps will be described. (Chip mounting step) First, the glass substrate (wiring substrate) 1 is placed at a predetermined position, and the IC chip 2 is transported above the glass substrate 1 by a suction head (not shown) to perform alignment (FIG. 1 ( a)). Next, the IC chip 2 is placed at a predetermined position on the glass substrate 1. Thereby, the bump 3 is brought into contact with the conductive pattern 10 on the glass substrate 1. (First bonding step) Thereafter, a predetermined load is applied to one bump 3 from the back surface (the upper surface in FIG. 1) of the IC chip 2 by a heating head (not shown) made of tungsten (W), and the temperature of the heating head is reduced. 5-1 at 120-175 ° C
Hold for 0 seconds. That is, the solder bump 32 of the bump 3
At a temperature lower than the melting point of 183 ° C., the IC chip 2 and the glass substrate 1 are joined while plastically deforming the solder bumps 32 by applying pressure. At this time, since the heating temperature is equal to or lower than the melting point of the solder bump 32, the solder bump 32 is not melted but is soft, and the bonding portion is deformed to be in surface contact. As shown in (b), the original height Ho is reduced to H1.

Here, H1 is about 75% of Ho. (Resin liquid injecting step) Thereafter, the resin liquid 4 is injected into the gap between the IC chip 2 and the glass substrate 1 through the nozzle 5 of the dispenser.
(See FIG. 1B). The resin liquid 4 is a liquid containing an epoxy resin as a main material, and contains about 40 to 70% by weight of a filler made of glass or the like, that is, small pieces.
Of course, it is not necessary to contain a filler. (Late bonding step) Thereafter, a predetermined load greater than that in the previous bonding step is applied to one bump 3 from the back surface (upper surface in FIG. 1) of the IC chip 2 by a heating head (not shown) made of tungsten (W). At the same time, the temperature of the heating head is kept at 120 to 175 ° C. and kept for 5 to 10 seconds. That is, at a temperature lower than the melting point of the solder bump 32 of the bump 3 of 183 ° C., the IC chip 2 and the glass substrate 1 are pressurized and joined while plastically deforming the solder bump 32. Thereby, the solder bumps 32 are further plastically deformed, and the bonding with the conductive patterns 10 on the glass substrate 1 is completed.

At this time, the height of the bump 3 is reduced from the height H1 to H2 as shown in FIG. Here, H2 is set to a value of about 50% of Ho. Further, in the latter bonding step, the excess resin liquid 4 filled between the IC chip 2 and the glass substrate 1 is pushed out. afterwards,
The resin liquid 4 is cured by polymerization or heat, and the operation is completed. Further, the above-mentioned heating may be performed by irradiating a laser to the bump portion without using the heating head.

Here, the joining conditions will be described in detail. The heating time (5 to 10 seconds) can be changed as long as the time is sufficient for conducting heat from the heating head to the substrate side. Further, in this embodiment, the height of the bump 3 was changed by increasing the load per bump from the later bonding step, but the load application time or the descent speed of the heating head was adjusted to adjust the bump 3. May be controlled. That is, in the previous period bonding step, the height of the bump 3 is H1
At this point, the application of the load may be stopped.

The bonding step, that is, the solder bump 32
It is also possible to perform plastic deformation slowly and to complete the injection of the resin liquid 4 before the plastic deformation is completed. Also before
After performing a certain amount of plastic deformation in the early joining process, press the heating head as it is, carry out the resin liquid injection process while maintaining the plastic deformation at a lower speed, and after the resin liquid injection is completed, perform the plastic deformation by the late joining process at high speed May be implemented.

Further, after the start of heating heads year bonding step may or load do is change of the load until the end of the late joining process also brought into contact with the IC chip 2 much remains constant, other resin injection step At times, the heating head may be removed.

Although the conductive pattern 10 (wiring material) is Au / Ni / ITO in the above embodiment, Au, Ni, S
Any solder such as n, Ag, Ag-Pd, Ag-Pt, and Cu may be used, and solder having a composition other than Pb-63Sn may be used for the solder bump 32. Also,
Although the solder bumps 32 are provided on the copper bumps 31 in the above embodiment, the copper bumps 31 may be omitted.

[Brief description of the drawings]

FIG. 1A is a schematic side view showing a state in which bonding of bumps 3 is started. (B) is a schematic side view showing a resin liquid injection step. (C) is a schematic side view showing a state after the completion of the latter bonding step (the bonding step in the present invention).

FIG. 2 is an enlarged sectional view of a bump 3 of FIG.

FIG. 3 is an enlarged side view of the glass substrate 1 of FIG.

[Description of Signs] 1 Glass substrate (wiring substrate) 2 IC (semiconductor) chip 3 Bump 10 Conductive pattern (connection electrode of wiring substrate)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/60 311 H01L 21/56

Claims (2)

(57) [Claims] And 1. A chip-placing step of abutting the connecting electrodes formed on the surface was soft protruding electrodes of the semiconductor chip on the connection electrodes of the wiring board, then the soft protruding electrode temperature below its melting point
Heating and pressing against the connection electrode of the wiring board, the soft projection electrode is plastically deformed, the height is reduced, and the bonding step is performed with the connection electrode of the wiring board. a resin injection step of injecting a resin solution into the gap between the wiring board, then the soft protruding electrode temperature below its melting point
By heating and pressing against the connection electrode of the wiring board, the soft projection electrode is further plastically deformed, the height is further reduced, the bonding with the connection electrode of the wiring board is strengthened , and then the resin mounting method of a semiconductor device, characterized in that it comprises a later bonding step of the liquid Ru was cured by heat. 2. The method for mounting a semiconductor device according to claim 1, wherein the resin liquid injection step is performed while the plastic deformation is maintained between after the first bonding step and before the second bonding step is started.