JPS5850020B2 - semiconductor equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing a semiconductor device.

In a method for connecting an external lead wire that is electrically connected to a semiconductor element, the electrode terminal on the semiconductor element has a height of 10 to 20 mm.
A method is used in which a protruding gold electrode of μ is provided and a stem made of metal foil, which serves as an external lead, is thermocompression bonded to the protruding electrode.

In this connection method, when forming protruding electrodes on a semiconductor element, the electrode terminals are removed because it is necessary to protect the internal wiring of the element (a protective film is provided over the entire surface of the semiconductor).

Conventionally, this protective film is made of glass, which prevents the inside of the device from being attacked by the various chemicals used to form the electrodes, and at the same time maintains the properties of the semiconductor device in a permanently stable manner. It also plays a protective role.

A glass protective film having such a role has advantages such as excellent workability, high electrical insulation, and chemical resistance.

On the other hand, since it is formed on semiconductors, metals, etc. that have different incompatibility coefficients, the breakable property peculiar to glass becomes a decisive drawback.

Cracks may occur due to heat treatment during the semiconductor element mounting process or thermal shock due to changes in the usage environment.
This causes deterioration of device characteristics and decreases reliability.

The present invention relates to a protective film on the surface of a semiconductor element, which improves the yield in the lead connection processing process by compensating for the drawbacks of a glass protective film, and is capable of producing a semiconductor device that can permanently maintain stable operation of the element characteristics. A manufacturing method is provided.

The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view of a lead connection of a semiconductor device having a conventional glass protective film.

That is, a metal film electrode 2 as an internal wiring is provided on the surface of the semiconductor element 10.

A glass protective film 4 with a thickness of 1 to 2 μm is formed on the entire surface of the metal electrode except for the external connection electrode 3 by, for example, a chemical vapor deposition method.

Regarding the external connection electrode 3, after forming the glass protective film 4, a protruding electrode 5 is formed by selectively applying gold to a thickness of 10 to 20 microns using electroplating or the like.

On the other hand, as an external lead wire, tin 7 or Au is plated on a copper foil 6 formed in the shape of a stem in advance, and the lead 6 and the protruding electrode 5 are bonded by thermocompression to connect the leads.

Regarding the thermocompression bonding process of external leads, for example, tin 7 on copper 6
The plated lead wires are heated to a temperature higher than the eutectic temperature of Au-8n (280 DEG C.) to form eutectic solder at the joint and connect the leads.

Further, when using a Cu81J-board plated with Au7, the Au-Au leads are connected by suppressing heating to 300°C or higher.

In either case, a shock due to heat suppression is applied to the semiconductor element, and cracks are likely to occur in the glass protective film around the electrodes.

Although this crack itself does not affect the electrical characteristics, the effect of protecting the semiconductor element from contamination to permanently maintain a stable moving body is lost, and the reliability is significantly reduced.

On the other hand, FIG. 2-2 is a sectional view of a semiconductor element provided with a protective film according to the present invention and an external lead connected thereto.

Until the protruding electrodes 5 are formed, all steps are the same as in the conventional method.
A protruding electrode 5 of 20 μm of Au is formed, and the other surfaces are covered with a glass protective film of 1 to 2 μm.

In the present invention, after forming the Au protruding electrodes 5 as shown in FIG. 2-1, a protective film 4 is further provided on the glass protective film.

This protective film is made of a fluororesin such as Teflon resin (this product name will be used hereinafter).

That is, a thermoplastic Teflon resin sheet is pasted over the entire surface of the semiconductor element.

In this case, the surface of the semiconductor element is uneven due to protruding electrodes, wiring, and the like.

Therefore, in the process of gluing Teflon resin sheets,
It is often thought that it is difficult to form a uniform protective film due to the presence of air bubbles inside, but the following method can be used to adhere to the glass protective film with a uniform thickness and without any air bubbles inside. can be done easily.

First, a Teflon resin sheet with a thickness of, for example, 10 μm is placed on the surface of a semiconductor element having protruding electrodes on a hot plate at 100°C to 150°C (a temperature at which the Teflon resin sheet does not melt), and an elastic material such as a silicone rubber plate is placed on the surface of the semiconductor element having protruding electrodes. etc. to suppress it.

In this step, the Teflon resin sheet is shaped to match the irregularities on the surface of the semiconductor element.

Next, in this molded state, the Teflon resin sheet is melted on a hot plate at 260'C to 300C.

By applying a surface activation treatment to the semiconductor element surface in advance, the melted and softened Teflon resin more firmly conforms to the unevenness of the semiconductor surface and fuses to a uniform thickness without incorporating air bubbles. do.

With respect to the Teflon resin layer adhered over the entire surface of the semiconductor element, a hole is made in the Teflon resin layer for external lead connection at a position corresponding to the external terminal electrode 5, as shown in FIG. 2-2.

A photoresist method is used for processing the Teflon resin.

As a method of etching the Teflon resin, for example, a plasma etching method in oxygen gas discharge is used.

As shown in FIG. 2-2, the entire surface of the semiconductor element thus formed, except for the external electrode terminals, is covered with glass and a 70 μm Teflon resin layer.

The effects when external lead wires are connected as shown in FIGS. 2-3 to the semiconductor element protected by the method according to the present invention are as follows.

(1) Teflon resin is not only chemically stable but also non-hygroscopic, and its water vapor permeability is extremely low at 0.01% or less for a 10μ thick film.

Therefore, contamination of semiconductor elements can be permanently prevented.

Further, it can be used continuously in a temperature range of -250°C to +200°C, has strong and flexible mechanical properties, and does not crack due to thermal shock.

(2) The surface of the semiconductor element is protected by Teflon resin with a thickness of 10 μm, which prevents the leads connected to the external connection terminals on the semiconductor element from coming into contact with the periphery of the semiconductor element and causing an electrical short circuit. It has a preventive effect.

By the way, in the past, when a glass protective film was used, the glass protective film could only be formed as a thin layer of 1 to 2 μm, and many defects occurred due to the external electrode lead coming into contact with the semiconductor element and causing electrical short circuits. Was.

[Brief explanation of the drawings] Fig. 1 is a sectional view of the device for explaining a conventional example, Fig. 2-1
Figures 2-3 are process diagrams for explaining one embodiment of the present invention. In the figure, 4...Glass coating, 4'...
...Fluororesin layer, 6...Lead wire.

Claims (1)

[Claims] 1. A step of selectively forming a plurality of metal electrodes as wiring on the surface of a semiconductor element, a step of forming a glass film serving as a surface protection film on the plurality of metal electrodes and the exposed surface of the semiconductor element, and A step of removing the glass coating on the externally connected metal electrode and forming a protruding electrode on the removed portion, forming a fluororesin on the protrusion electrode and the glass coating, and melting the fluororesin. a step of heating after the step to melt the fluororesin and fusion-bond it on the protruding electrode and the glass coating; and a step of removing the fluororesin on the protruding electrode to form the protruding electrode. 1. A method for manufacturing a semiconductor device, comprising the steps of: exposing a protruding electrode; and connecting an external lead wire to the exposed protruding electrode.