JPH0228340A - Method of mounting semiconductor chip - Google Patents

Abstract

PURPOSE:To enable face down mounting on a semiconductor chip having electrode pads without forming a connecting metallic projection by using metallic balls as connecting materials. CONSTITUTION:Resin paste 3 is formed by printing on metallic patterns 22 for connecting with a semiconductor chip 7 installed on the surface of a heat resisting insulating substrate 1 to mount the semiconductor chip 7 thereon and metallic balls 4 are stuck at the same height on the resin paste 3, directly connected with both the metallic patterns 22 for connection on the surface of the substrate 1 and electrode pads 21 on the semiconductor chip 7, and pressurized and heated. Therefore, metal and metal are substantially connected with each other. This enables easily mounting a semiconductor by face down bonding method.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a semiconductor chip having connection electrode pads.
Regarding the mounting method of mounting and connecting directly to a heat-resistant insulating board face-down, conventional metal protrusions for connection (hereinafter referred to as "bumps") are used.

), the semiconductor chip is provided on the surface of a heat-resistant insulating substrate on which the semiconductor chip is mounted, with the aim of realizing face-down mounting of the majority of semiconductor chips that have electrode pads (AN aluminum) without forming an electrode pad. A process of printing and forming a resin paste on the surface of a metal pattern for connection with a chip, a process of adhering and fixing a metal ball to the resin paste while leaving the resin paste uncured, and a process after the resin paste is cured. , a step of making the connection electrode pad surface of the semiconductor chip face the surface of the heat-resistant insulating substrate; a step of aligning the position of the metal ball and the connection electrode pad position of the semiconductor chip; and the step of aligning the connection electrode pad of the semiconductor chip with each other. and the metal ball are connected to each other by applying pressure and heating.

[Industrial Application Field] The present invention relates to a semiconductor chip mounting method applied to hybrid ICs, thermal heads, etc.

In recent years, semiconductor manufacturing technology has progressed rapidly, and semiconductor chips are becoming larger and more dense.

The above-mentioned changes that have accompanied the advancement of technology have led to an increase in the number of electrode pads for external connections, even though semiconductor chips are becoming smaller.

There is a need for a mounting method that uses a semiconductor chip having a large number of electrode pads as described above and is no inferior to conventional methods from the standpoint of mass production technology, and it has become necessary to fundamentally improve existing technology.

[Prior Art] Conventionally, the most commonly used method is the wire bonding mounting method.

As shown in FIGS. 4(a) and 4(b), this method involves connecting electrode pads 21 on the semiconductor chip 7 placed on the surface of the heat-resistant insulating substrate 1 and connecting electrode pads 21 provided on the surface of the heat-resistant insulating substrate 1. The bonding wire 4 is connected between the connection metal pattern 22
1.

However, this method has been improved against the background of the above-mentioned technological progress, and a new method using face-down method as shown in FIGS. 5(a) and 5(b) has been developed.

Place the semiconductor chip directly on the board by face-down,
The most commonly used connection method has been the flip-chip mounting method.

In this method, bumps 42 are provided in advance on the semiconductor chip 7 to be mounted face-down, and the positions of the bumps 42 on the semiconductor chip side and the connecting metal pattern 22 on the surface of the heat-resistant insulating substrate are
After aligning the positions with each other, it was mounted by applying pressure and heating.

However, recently, 1) a method in which a through hole is made in advance at the position of the connecting electrode pad of the semiconductor chip on the substrate surface, the semiconductor chip is placed, and then a conductive resin is poured into the through hole and solidified (JP-A-59-1
2) A bump is formed on an insulating substrate different from a circuit board on which a semiconductor chip is placed, and the bump is transferred to the semiconductor chip side using a tool (Japanese Patent Laid-Open No. 61 - Invention described in Publication No. 50339) and 3) Bumps are printed in advance at the positions where semiconductor chips are to be placed on the connection metal pattern on the surface of the circuit board, and a conductive resin layer is further provided on the bumps. Improvements have been made in various ways, such as mounting a chip (invention described in Japanese Patent Laid-Open No. 61-94330).

[Problem to be solved by the invention]

The conventional flip-chip mounting method for forming bumps has the following advantages.

1) As shown in FIG. 4, the mounting area 9 can be smaller compared to wire bonding.

2) The position on the substrate where the connecting metal pattern 22 is to be provided is not limited to the outer periphery of the semiconductor chip 7, but can be freely selected as long as it is an area occupied by the semiconductor chip 7.

3) All wires can be connected at the same time with one alignment, making work more efficient.

4) Superior mechanical connection reliability compared to wire bonding.

However, it has the following disadvantages: 1) Most semiconductor chips having connection electrode pads cannot be used, and 2) bumps must be provided in advance on the semiconductor chip, which is a technical difficulty.

On the other hand, a common drawback among the known champions who have attempted to improve bump formation is the technical difficulty in practical application as a mass production technique.

Add individual explanations.

First, in the invention described in JP-A-59-188955, the conductive resin is in contact with both the connection metal pattern and the connection electrode pad of the substrate.

By the way, since the conductive resin itself does not have conductivity and obtains conductivity by mixing fine metal particles into the resin, the electrical resistance of the connection portion increases.

In addition, the majority of semiconductor chips with connection electrode pads use AI (aluminum) as the base material for the connection electrode pads, and the natural formation of an oxide film on the surface of the AI electrode pads due to oxygen in the air is unavoidable. becomes.

For this reason, the connection with the connection electrode pad is actually made through the oxide film, and stable contact cannot be obtained.

In other words, 3) There is a problem with the reliability of electrical connections.

In addition, due to the viscosity of the conductive resin itself, there is a problem that air bubbles may enter the area that needs to be sealed.

Furthermore, in the invention described in JP-A-61-50339, it is extremely difficult to form bumps.

That is, 4) forming the metal protrusions provided on a separately prepared insulating substrate is troublesome, and the transfer process is technically extremely difficult.

To be more specific, in this known example, an electrolytic plating method is used to form the metal protrusions.

At this time, after forming a metal film forming an electrode for plating, an insulating film is formed on the metal film.

However, the metal film must be easily peeled off after the metal protrusions are formed and must have a certain degree of strength.

It is extremely difficult to strike a balance that satisfies this condition.

Furthermore, the formation of the metal protrusions is even more troublesome because it requires a series of complicated steps of photolithography, ie, cleaning, vapor deposition, resist coating, mask pattern formation, and development.

As described above, even if it is possible to use it in principle or experimentally, there are many problems when it comes to practical application in mass production.

On the other hand, in the invention described in JP-A No. 61-94330,
The bump must be formed on the circuit board by a method such as printing, and a small amount of conductive resin must be formed in a very small area on the hump.

In other words, if this method is used, 5) It is essential to accurately perform two printings overlapping each other, which is currently an extremely difficult problem in terms of printing technology.

The present invention addresses disadvantages 1) to 5 of the similar known examples described above.
) The challenge is to overcome all of them.

In other words, in addition to inheriting the point that flip-chip mounting has already mentioned as its greatest advantage, ``space-saving, high-density mounting is possible efficiently,'' it also has the ability to The aim is to realize technically easy face-down bonding using semiconductor chips while improving the reliability of electrical connections.

[Means to solve the problem]

See FIGS. 1(a) to (d).

In order to solve this problem, a process of printing and forming a resin paste 3 on the surface of a metal pattern 22 for connection with the semiconductor chip 7 provided on the surface of the heat-resistant insulating substrate 1 on which the semiconductor chip 7 is placed is performed. , a step of adhering and fixing the metal ball 4 to the resin paste 3 while the resin paste 3 remains uncured; and after curing the resin paste 3, the surface of the connection electrode pad 21 of the semiconductor chip 7 is a step of aligning the position of the metal ball 4 with the position of the connection electrode pad 21 of the semiconductor chip 7; and a step of aligning the connection electrode pad 21 and the metal ball 4 with each other. The semiconductor chip 7 is mounted by a step of connecting the two to each other by applying pressure and heating.

[Operation] In the present invention, a resin paste is printed and formed on a metal pattern for connection with a semiconductor chip provided on the surface of a heat-resistant insulating substrate on which a semiconductor chip is placed.

The metal balls adhering to the resin paste are later kept at a constant height, and later come into direct contact with both the connection metal pattern on the substrate surface and the electrode pads and nodes on the semiconductor chip side, and are pressed and heated. It essentially connects the metals together.

Therefore, connection problems caused by conductive resin can be solved.

On the other hand, when considering the actual manufacturing process, it is possible to form a substitute for a hump extremely easily without using a complicated photolithography process, and there is no loss in the advantages of the conventional method.

[Example] An example of the present invention will be described below with reference to the drawings.

See Figure 1(a).

Using a heat-resistant insulating substrate 1 made of 99.5χ alumina, a Ta-N resistive film and a NiCr/^U conductive film were coated with DC
The entire surface is formed by magnetron sputtering.

Next, using a photolithography process, a Ta-N resistive film,
Form a NiCr/Au conductor pattern. At this time, the portion on which the semiconductor device is mounted is formed as a connection metal pattern 22 corresponding to the semiconductor pair knob pattern.

See Figure 1(b).

After this, a polyimide-based Ag(ill) conductive resin paste 3 is applied as a resin paste 3 to the position on the heat-resistant insulating substrate 1 to be connected to the electrode pad 21 on the side of the semiconductor chip 7.
Printing is performed using a 25-mesh stainless steel mask.

See Figure 1(c).

The metal ball 4 forming the connection member is made of AI (aluminum).
I used ^U (gold) in consideration of its affinity with

Metal balls 4 made of Au (gold) with a diameter of 50 to 60 μm are scattered on the heat-resistant insulating substrate 1 and adhered to the conductive resin paste 3, and then unnecessary metal balls 4 are swung and dropped.

The weight of the metal ball 4 itself is extremely light, and the viscosity of the conductive resin paste 3 is sufficient to prevent the metal ball 4 from falling even with slight shaking.

Therefore, removing the extra balls while leaving the attached metal balls 4 is easily possible if the degree of rocking is balanced.

In addition, the printing area of the conductive resin paste 3 is as follows:
It is possible to form the film to the extent that only individual parts can be attached.

Therefore, the required number of metal balls 4 will be attached to a predetermined position.

The heat-resistant insulating substrate 1 thus became as shown in FIG. 1(c).
, with the metal ball 4 attached, conductive resin paste 3
Heat at 150°C for 1 hour and at 300'C for 1 hour to cure.

See Figure 2.

In order to make the height of the metal sphere 4 adhered to the heat-resistant insulating substrate 1 using the conductive resin paste 3 constant, the surface of the metal sphere 4 is adjusted to an accuracy of ±5 μm on the heat-resistant insulating substrate 1 using the parallel adjustment tool 8. The distance 51 between the surface of the upper connection metal pattern 22 and the connection electrode pad 21 of the parallel adjustment tool 8 is approximately 5.
Pressure is applied to 0 μm.

See FIG. 1(d) and FIG. 3, which is a partially enlarged view thereof.

A heat-resistant insulating substrate work on which metal balls 4 are attached at constant intervals 51 is heated to 350° C. to 400° C. on a hot plate 6.

Meanwhile, the crimping tool 5 is also heated to 350°C to 400°C.

The connection metal pattern 22 on the surface of the heat-resistant insulating substrate 1 and the connection electrode pad 21 pattern on the semiconductor chip 7 side are aligned separately, and after the alignment is completed, the heat-resistant insulating substrate 1 and the semiconductor chip 7 are placed facing each other. While maintaining the parallelism of the semiconductor chip 7 by ±5 μm, each connection electrode pad 21 is bonded under pressure of 100 g to 300 g.

The present invention has been described above with reference to embodiments. According to the method of the present invention, it is possible to overcome the drawback of the conventional method that flip-chip mounting is not possible without providing bumps, and in addition, it is possible to overcome the drawback of the conventional flip-chip mounting method. The advantages are not compromised in any way, and the reliability of the electrical connection can be sufficiently improved.

Note that the present invention can be modified in various ways, especially regarding the attachment of the metal balls 4, in accordance with the spirit of the present invention.

For example, the metal ball 4 may be made of a material other than Au (gold), and the resin paste 3 may be freely selected from copper paste, silver paste, gold paste, etc.

Furthermore, in the above embodiment, a conductive resin paste was used as the resin paste 3, but the present invention is not limited to this.
For example, if the resin paste 3 ensures that the metal ball 4 comes into direct contact with the connecting electrode pad 21, an insulating paste may be used as the resin paste 3.

Similarly, other heat-resistant insulating materials such as glass may be used for the heat-resistant insulating substrate 1.

Further, when mounting the semiconductor chip 7, ultrasonic waves may be used in combination.

〔Effect of the invention〕

As explained above, according to the present invention, the reliability of electrical connection is also sufficient compared to the method of improving conventional flip-chip mounting.

In other words, in the present invention, the metal balls essentially form the connection member, and the resin is merely used as a glue to adhere the metal balls.

Therefore, the problems of electrical resistance and electrical connection problems caused by the conductive resin paste have been solved.

Further, the metal sphere, the connecting electrode pad, and the connecting metal pattern are configured to cause metal diffusion by heating and pressurizing to obtain an essential metal-to-metal connection.

On the other hand, if we look at the manufacturing process, we can see that the complicated photolithography process used in conventional examples to form bumps or their substitutes is a series of cleaning, vapor deposition, resist coating, mask pattern formation, and development. This process is completely unnecessary.

At the same time, there is no need to print the bumps accurately and also to print the conductive resin paste accurately on the bumps.

In view of the above considerations, the present invention makes it possible to extremely easily mount semiconductors by the face-down bonding method, thereby expanding the range of applications of flip-chip mounting.

Therefore, there is a large profit in terms of manufacturing costs.

Moreover, a large number of semiconductor chips that could not be used in the past can now be used through an easy manufacturing process without sacrificing the advantages of the conventional method and with equivalent special pretreatment.

[Brief explanation of the drawing]

Figures 1 (a) to (d) are process explanatory diagrams (side views) according to embodiments of the present invention, Figure 2 is an enlarged explanatory diagram (side view) of the parallel adjustment process, and Figure 3 is: An enlarged explanatory diagram (side view) of the connection part between the substrate and the semiconductor chip, FIGS. 4(a) and 4(b) are explanatory diagrams of the wire bonding mounting method (top view (a) and side view (b)), Figure 5 (a
) to (b) are explanatory diagrams (top view (a) and side view (b)) of the flip-chip mounting method. Metal pattern resin paste for connecting electrode pads for connecting heat-resistant insulated substrates (4-electroconductivity) Metal ball bonding wire bumps (metal protrusions for connection) Crimping tool hot plate Semiconductor chip parallel adjustment tool mounting area. Bill OleWg Den Oyomanodo 67r-Butoplate 7, +4 conductors Navua Chichiku Ibo process-enlarged explanatory diagram (IvIl1 figure) Quick drawing Kisaihan and Ubo Hoken, Tep and Saiju Nuigun (4 Liumian map) Rear wire binding method nil light (top view (σ) and 41 road 1δ (b grass map)

Claims (1)

[Claims] Semiconductor chip (7) having a connection electrode pad (21)
In a mounting method in which the semiconductor chip (7) is placed directly on the surface of the heat-resistant insulating substrate (1) face-down, the heat-resistant insulating substrate (1)
) a step of printing and forming a resin paste (3) on the surface of a metal pattern (22) for connection with the semiconductor chip (7) provided on the surface of the semiconductor chip (7); Ball (4
) to the resin paste (3), and after curing the resin paste (3), the connecting electrode pad (21) surface of the semiconductor chip (7) is attached to the heat-resistant insulating substrate (1). a step of aligning the position of the metal ball (4) and the position of the connection electrode pad (21) of the semiconductor chip (7) with each other; A method for mounting a semiconductor chip (7), comprising the step of connecting the spheres (4) to each other by applying pressure and heating.