JP2001196418A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem in which the connection pad of an insulating base cannot be surely, firmly, and electrically connected to the electrode of a semiconductor device due to the deformation of the insulating base. SOLUTION: A semiconductor device is composed of an insulating base 1 equipped with connection pads 3 on its top surface and a semiconductor element 2 equipped with electrodes 2a on its under surface, where the semiconductor element 2 is mounted on the insulating base 1, and the connection pads 3 and the electrodes 2a are connected together through the intermediary of an anisotropic conductive film 4 which is formed by dispersing conductive particles 4a into a resin film 4b. The top surface of the connection pad 3 is set at 15 μm or below in evenness, the maximum height (Ry) of the surface roughness of the connection pad 3 is set 1/2 or above as large as the average diameter of the conductive particles 4a dispersed into the anisotropic conductive film 4 and set at 10 μm or below, and an organic resin insulating layer 6 is interposed between the side of the connection pad 3 and the anisotropic conductive film 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device mounted on an information processing apparatus such as a computer, and more particularly to a semiconductor device in which electrodes of a semiconductor element are connected to connection pads of a wiring board via an anisotropic conductive film. The present invention relates to a semiconductor device comprising:

[0002]

2. Description of the Related Art Conventionally, a semiconductor device includes a semiconductor element, a wiring board on which the semiconductor element is mounted, and an anisotropic conductive film (ACF) in which the semiconductor element and the wiring board are electrically and mechanically connected and mounted. And the like.

The wiring substrate is made of ceramics such as an aluminum oxide sintered body, and has an insulating base having a semiconductor element mounting portion on an upper surface, tungsten, molybdenum, copper, and the like.
It is made of a metallized metal layer such as silver and is formed by connection pads formed on the surface of the mounting portion.

Further, the anisotropic conductive film includes conductive particles (average diameter of about 1 to 10 μm) made of a metal such as gold, silver, and copper, and an organic resin having these metals adhered to the surface thereof. It has a structure in which it is dispersed in a resin film having a thickness of 10 to 50 μm and made of an organic resin such as a thermosetting resin, a thermoplastic resin, or a photocurable resin.

In such a semiconductor device, for example, a semiconductor element is mounted on a mounting portion of an insulating base such that a connection pad formed on the mounting portion and a connection pad on a lower surface of the semiconductor element are opposed to each other. The semiconductor device, the anisotropic conductive film, and the wiring board are pressed vertically, and the resin film of the anisotropic conductive film is cured at the same time. The connection pad of the insulating base and the electrode of the semiconductor element are appropriately flattened by sandwiching the conductive particles of the anisotropic conductive film by the pressing,
Electrical connection is made via the conductive particles, and at the same time, the insulating base and the semiconductor element are joined via the resin film.

[0006]

However, in the above-described conventional semiconductor device, when the insulating substrate made of an aluminum oxide-based sintered body or the like is fired, the insulating substrate is liable to be deformed such as warp. The flatness of the upper surface of all the connection pads formed on the mounting portion surface of the insulating base due to warpage or the like is high, typically as high as 30 μm or more, and there is a large variation in the position in the vertical direction. When the electrodes of the device are connected via the anisotropic conductive film, the force for sandwiching the conductive particles in the anisotropic conductive film varies greatly between the plurality of connection portions, and each connection pad and the electrode of the semiconductor device are connected to each other. The conductive particles cannot be sandwiched between the conductive particles at a uniform pressure, and the contact areas between the connection pads and the electrodes and the conductive particles vary, so that the electrical resistance of the connection portion varies from a predetermined resistance value. There is a problem that it may become impossible to accurately operate.

The connection pad formed by the metallized metal layer has a maximum surface roughness Ry (JI).
S standard) is less than 0.5 μm, and the average diameter of the conductive particles (1 to 1)
10 μm), which captures conductive particles,
Since the holding function is weak, it is difficult to capture and hold a sufficient number of conductive particles on the connection surface when the anisotropic conductive film is sandwiched between the connection pad and the electrode of the semiconductor element and pressed. There is also a problem that the contact area between the pad and the electrode of the semiconductor element is reduced, the contact resistance is increased, and the electrical characteristics of the semiconductor device may be degraded.

Further, in the above-mentioned conventional semiconductor device, the connection pads have a narrower pitch (about 10 to reduce the size of the semiconductor device).
0 μm or less), a plurality of conductive particles of the anisotropic conductive film are connected in a horizontal direction, and adjacent connection pads are electrically short-circuited via the connected conductive particles, As a result, there is also a problem that the semiconductor device cannot be operated normally and stably.

[0009]

According to the present invention, there is provided a semiconductor device comprising:
An insulating substrate having a plurality of connection pads on an upper surface and a semiconductor element having a plurality of electrodes on a lower surface. The semiconductor element is mounted on the insulating substrate, and each connection pad and each electrode are electrically conductive in a resin film. A semiconductor device connected via an anisotropic conductive film in which particles are dispersed, wherein the flatness of the upper surface of all of the connection pads is set to 15 μm or less and the maximum height (Ry) of the surface roughness of each connection pad. Is 以上 or more to 10 μm with respect to the average diameter of the conductive particles of the anisotropic conductive film.
An insulating layer made of an organic resin is interposed between a side surface of the connection pad and the anisotropic conductive film.

The semiconductor device according to the present invention is characterized in that the thickness of the insulating layer is 1 μm or more.

According to the semiconductor device of the present invention, since the flatness of the upper surface of all the connection pads is set to 15 μm or less, the connection pads and the electrodes of the semiconductor element are formed by dispersing metal particles in a resin film. When connecting via an anisotropic conductive film, pressure can be applied almost uniformly to all connection pads, and the force for sandwiching conductive particles between the connection pads and the electrodes of the semiconductor element is equal between each connection pad Thus, it is possible to effectively prevent the electric resistance of each connection portion from varying.

Further, according to the semiconductor device of the present invention, the maximum height Ry of the surface roughness of each connection pad is 以上 to 10 μm with respect to the average diameter of the conductive particles of the anisotropic conductive film.
Since the surface is moderately rough, when the anisotropic conductive film is interposed between the connection pad and the electrode of the semiconductor element and pressurized, the conductive particles are easily placed in the valley of the upper surface of the connection pad having the moderately rough surface. And ensure that it is retained, so that a sufficient number of conductive particles are captured on the connection surface,
As a result, the contact resistance between the connection pad and the electrode of the semiconductor element is made sufficiently low, so that a semiconductor device having excellent electrical characteristics can be obtained.

Further, according to the semiconductor device of the present invention, since the insulating layer made of an organic resin is interposed between the side surface of the connection pad and the anisotropic conductive film, the connection pads are formed at a narrow pitch. Even if a plurality of conductive particles of the anisotropic conductive film are connected in a lateral direction between adjacent connection pads, the connected conductive particles and each connection pad are insulated by the insulating layer on the side of the connection pad, and as a result, Adjacent connection pads are not electrically short-circuited, and the semiconductor device can always operate normally and stably.

[0014]

Next, the present invention will be described with reference to the accompanying drawings. FIG. 1 is a sectional view showing one embodiment of the semiconductor device of the present invention, wherein 1 is an insulating base, 2 is a semiconductor element, 3 is a connection pad, and 4 is an anisotropic conductive film.

The insulating substrate 1 is made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body,
It is a substantially rectangular plate made of an electrically insulating material such as a silicon carbide sintered body or a glass ceramic sintered body, and has a semiconductor element mounting portion 1a for mounting a semiconductor element in the center of the upper surface thereof. The semiconductor element 2 is mounted on the semiconductor element mounting portion 1a using the anisotropic conductive film 4.

When the insulating substrate 1 is made of, for example, a sintered body of aluminum oxide, an organic binder, a solvent, a plasticizer, a dispersant, etc. suitable for a raw material powder of aluminum oxide, silicon oxide, magnesium oxide, calcium oxide and the like. Is added to form a slurry, and a plurality of ceramic green sheets are obtained by forming the sheet into a sheet by employing a conventionally known doctor blade method, calender roll method, or the like. It is manufactured by performing a punching process, laminating the layers up and down as necessary, and firing this at a temperature of about 1600 ° C.

A plurality of connection pads 3 connected to the electrodes 2a of the semiconductor element 2 are formed on the surface of the mounting portion 1a of the insulating base 1 so as to correspond to the electrodes 2a of the semiconductor element. A plurality of wiring conductors 5 are formed to extend from the pad 3 to the lower surface of the insulating base 1. The semiconductor element 2 is joined to the mounting portion 1a, and the electrode 2a of the semiconductor element 2 is electrically connected to the connection pad 3. Thus, the semiconductor device is completed as a semiconductor device. If the lead portion of the wiring conductor 5 is connected to an external electric circuit, the semiconductor element 2 is electrically connected to the external electric circuit.

The connection pad 3 and the wiring conductor 5 are made of a metal material such as tungsten, molybdenum, copper, silver, etc.
For example, in the case of a metal powder having a high melting point such as tungsten, molybdenum, or manganese, a suitable organic solvent is added to the metal powder having a high melting point, and a metal paste obtained by adding and mixing a solvent is thickened by a conventionally known screen printing method. The mounting portion 1a of the insulating base 1 is formed by applying a film method and printing and coating the surface of the ceramic green sheet serving as the insulating base 1 in advance.
To the lower surface.

The semiconductor element 2 has an electrode 2a such as a gold bump formed on the lower surface thereof.
Thereby, the lower surface is joined to the mounting portion 1a, and the electrodes 2a are electrically connected to the connection pads 3.

The anisotropic conductive film 4 functions as an adhesive for bonding the semiconductor element 2 to the mounting portion 1a of the insulating base 1, and also connects the electrode 2a of the semiconductor element 2 to the connection pad 3.
And acts as a conductive adhesive member to be electrically connected to the substrate.

The anisotropic conductive film 4, as shown in FIG.
Conductive particles made of a metal such as silver, copper, gold, nickel, tin, lead or an alloy thereof, or an organic resin such as polystyrene having these metals adhered to the surface (the average diameter is 1 to 10 μm
A) A structure in which 4a is dispersed in a resin film 4b made of a thermosetting resin such as an epoxy resin having a thickness of 10 to 50 μm, a thermoplastic resin such as a polyethylene resin, a photocurable resin such as an acrylic resin, or the like. The resin film 4b functions as an adhesive for bonding the semiconductor element 2 to the mounting portion 1a, and the conductive particles 4a function as a conductive member for connecting the electrode 2a of the semiconductor element 2 to the connection pad 3. I do.

The mounting of the semiconductor element 2 on the mounting portion 1 a by the anisotropic conductive film 4 is performed, for example, by mounting the mounting portion 1 of the insulating base 1.
a, a plurality of connection pads 3 on the surface of the mounting portion 1a and the electrodes 2a of the semiconductor element 2 are vertically aligned, and then the semiconductor element 2 is mounted thereon. The semiconductor device 2, the anisotropic conductive film 4, and the insulating base 1 are pressed and heated so that a load of about 50 to 150 gf is applied to each connection pad vertically, and the connection pad 3 and the electrode 2a are heated. A large number of conductive particles 4 between
a is captured and held, and is pressurized to be appropriately flattened and sandwiched with a wide contact area, so that both are electrically connected with low electric resistance, and at the same time, the resin film 4b is thermally cured. As a result, the position of the conductive particles 4a is fixed, and the insulating base 1 and the semiconductor element 2 are joined.

In this case, when the flatness of the upper surface of the plurality of connection pads 3 exceeds 15 μm, the pressure for compressing the anisotropic conductive film 4 in each connection pad 3 varies, and each connection pad 3 and the semiconductor element A difference occurs in the contact resistance between the second electrode 2a and the second element 2a, so that the semiconductor element 2 cannot be operated accurately. Therefore, the flatness of the upper surface of all the connection pads 3 is specified to be 15 μm or less.

When the maximum height Ry of the surface roughness of the connection pad 3 is less than half the average diameter of the conductive particles 4a in the anisotropic conductive film 4, the average diameter of the conductive particles 4a ( (Generally 1 to 10 μm), the depth of the valleys 3a on the surface of the connection pad 3 for capturing and holding this is too shallow, and the action of capturing and holding the conductive particles 4a is extremely low.
When the semiconductor element 2 is mounted on the mounting portion 1a using the anisotropic conductive film 4, a large number of conductive particles 4a are formed between the connection pad 3 and the electrode 2a of the semiconductor element due to deformation of the resin film 4b due to pressure. And the conductive particles interposed between the connection pad 3 and the electrode 2a are insufficient, and the contact resistance between them is increased. When Ry exceeds 10 μm and becomes rough, the depth of the valley 3 a on the surface of the connection pad 3 becomes too deep compared to the average diameter of the conductive particles 4 a in the anisotropic conductive film 6,
Many of the held conductive particles 4a are hidden in the valleys 3a, and the conductive particles 4a cannot be effectively flattened to increase the contact area between the connection pad 3 and the electrode 2a. Increase the contact resistance. Therefore, the connection pad 3 needs to have the maximum height Ry of the surface roughness in the range of not less than 乃至 to not more than 10 μm with respect to the average diameter of the conductive particles 4 a of the anisotropic conductive film 4.

Further, an insulating layer 6 made of an organic resin is interposed between the side surface of the connection pad 3 and the anisotropic conductive film 4.

The insulating layer 6 functions to prevent electrical connection between the side surface of the connection pad 3 and the conductive particles 4a of the anisotropic conductive film, and the space between adjacent connection pads 3 is reduced and adjacent. Even if a plurality of conductive particles 4a located between the connection pads 3 are connected in a horizontal direction, the short-circuit between the adjacent connection pads 3 is effectively prevented by the insulating layer 6, so that the semiconductor element 2 Can be operated normally and stably.

The insulating layer 6 is made of an organic resin such as an epoxy resin or a polyimide resin. For example, if the insulating layer 6 is made of an epoxy resin, the insulating layer 6 is formed on the upper surface of the mounting portion 1a of the insulating base 1.
Before mounting the semiconductor element 2, a thermosetting epoxy resin precursor is printed and applied to a predetermined thickness and heated and cured to form a predetermined thickness on the surface of the insulating base 1 and the connection pad 3 of the mounting portion 1 a. Epoxy resin film, and then
By performing planar polishing from the upper surface of the epoxy resin film and exposing the upper surface of the connection pad 3, it is possible to adhere the side surface of the connection pad 3 with a predetermined thickness.

At the same time, by this planar polishing, the flatness of the upper surface of all the connection pads 3 can be increased and the surface thereof can be appropriately roughened. The maximum height Ry of the surface roughness of the pad 3 can be in the range of 以上 to 10 μm with respect to the average diameter of the conductive particles 4 a of the anisotropic conductive film 4.

The insulating layer 6 has a thickness of 1 μm.
If the thickness is less than 10 mm, the side surface of the connection pad 3 cannot be completely covered with the insulating layer 6, and it is difficult to effectively prevent an electrical short circuit between the adjacent connection pads 3. Therefore, the thickness of the insulating layer 6 is preferably set to 1 μm or more, and particularly preferably set to about 10 μm.

The coefficient of thermal expansion of the organic resin forming the insulating layer 6 is similar to that of the organic resin forming the resin film 4b of the anisotropic conductive film 4 (about 90% to 11%).
0%), even if heat acts on the insulating layer 6 and the anisotropic conductive film 4, the two can be firmly joined without generating large thermal stress between them. Therefore, in order to further increase the long-term reliability of the semiconductor device and to keep the bonding between the insulating layer 6 and the anisotropic conductive film 4 strong, the thermal expansion coefficient of the organic resin forming the insulating layer 6 must be anisotropic. It is preferable that the thermal expansion coefficient of the organic resin forming the resin film 4b of the conductive conductive film 4 is approximated (about 90% to 110%).

Further, the connection pads 3 and the wiring conductors 5
When a metal having excellent corrosion resistance such as nickel and gold, and excellent in bonding property and wettability with solder is applied to the exposed surface to a thickness of 1 to 20 μm by plating, the connection pad 3 and the wiring Oxidation and corrosion of the conductor 5 can be effectively prevented, and the connection of the wiring conductor 5 to the external electric circuit board can be made easy and reliable. Therefore, the wiring conductor 5 and the connection pad 3
It is preferable that a metal having excellent corrosion resistance, such as nickel and gold, and having excellent bonding properties and wettability with solder is applied to the exposed surface to a thickness of 1 to 20 μm by plating.

It should be noted that the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention.
Although the insulating layer 6 is formed from the side surface of the connection pad 3 to the surface of the insulating base 1, the insulating layer 6 is formed only on the side surface of the connection pad 3 by using a photocurable epoxy resin and employing photolithography technology. It may be made to adhere to.

[0033]

According to the semiconductor device of the present invention, since the flatness of the upper surface of all the connection pads is set to 15 μm or less, the connection pads and the electrodes of the semiconductor element are formed by dispersing metal particles in a resin film. When connecting via the anisotropic conductive film, the pressure can be applied almost uniformly to all the connection pads, and the force for sandwiching the conductive particles between the connection pads and the electrodes of the semiconductor element is applied between the connection pads. Thus, it is possible to effectively prevent the electric resistance of each connection portion from varying.

According to the semiconductor device of the present invention, the maximum height Ry of the surface roughness of each connection pad is set to １ ／ to 10 μm with respect to the average diameter of the conductive particles of the anisotropic conductive film.
Since the surface is moderately rough, when the anisotropic conductive film is interposed between the connection pad and the electrode of the semiconductor element and pressurized, the conductive particles are easily placed in the valley of the upper surface of the connection pad having the moderately rough surface. And ensure that it is retained, so that a sufficient number of conductive particles are captured on the connection surface,
As a result, the contact resistance between the connection pad and the electrode of the semiconductor element is made sufficiently low, so that a semiconductor device having excellent electrical characteristics can be obtained.

Further, according to the semiconductor device of the present invention, since the insulating layer made of an organic resin is interposed between the side surface of the connection pad and the anisotropic conductive film, the connection pads are formed at a narrow pitch. Even if a plurality of conductive particles of the anisotropic conductive film are connected in a lateral direction between adjacent connection pads, the connected conductive particles and each connection pad are insulated by the insulating layer on the side of the connection pad, and as a result, Adjacent connection pads are not electrically short-circuited, and the semiconductor device can always operate normally and stably.

[Brief description of the drawings]

FIG. 1 is a sectional view showing one embodiment of a semiconductor device of the present invention.

FIG. 2 is a sectional view of a principal part of the semiconductor device shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Insulating base 2 ... Semiconductor element 2a ... Electrode 3 ... Connection pad 4 ... Anisotropic conductive film 4a ... Conductive particles 4b ... Resin film 5 ... ... Wiring conductor 6 ... Insulating layer

Claims (2)

[Claims] An insulating substrate having a plurality of connection pads on an upper surface; and a semiconductor element having a plurality of electrodes on a lower surface. The semiconductor element is mounted on the insulating substrate, and each connection pad and each electrode are connected to each other. A semiconductor device connected via an anisotropic conductive film formed by dispersing conductive particles in a resin film, wherein the flatness of the upper surface of all the connection pads is 15 μm or less, and the maximum surface roughness of each connection pad is Height (R
y) is set to １ ／ to 10 μm with respect to the average diameter of the conductive particles of the anisotropic conductive film, and an insulating layer made of an organic resin is provided between the side surface of the connection pad and the anisotropic conductive film. A semiconductor device characterized by being interposed. 2. The semiconductor device according to claim 1, wherein said insulating layer has a thickness of 1 μm or more.