JPS63133654A - Optically erasable semiconductor storage device - Google Patents

Abstract

PURPOSE:To lower the heat-treatment temperature required during a production process and to limit the use of an expensive construction material to a light-transmitting window plate by a method wherein the light-transmitting window plate composed of quartz or hard glass is installed directly above an optically erasable semiconductor memory chip of an assembled structure and the light-transmitting window plate is exposed and is then sealed by a resin material. CONSTITUTION:An optically erasable semiconductor memory chip 3 is fixed to a substrate-supporting part 1 of a lead frame; a light-transmitting window plate 7 composed of quartz or hard glass is installed directly above said optically erasable semiconductor memory chip 3 at an assembled structure where electrodes on the memory chip 3 and inner leads 2 are connected by metal thin wires 4; then, this assembly is sealed with a resin material 10 in such a way that said light-transmitting window plate 7 is exposed. For example, a transparent resin layer 8 composed of a gel-like silicon material or the like is laid between the optically erasable semiconductor memory chip 3 and the light-transmitting window plate 7. In addition, a groove 11 is made around the light-transmitting window plate 7 during a sealing and molding process; an epoxy resin material 12 is buried into the groove 11 after the molding process and is then set at a temperature of 150-200 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photo-erasable semiconductor memory device in which information is erased using light.

2. Description of the Related Art Conventional packages for photo-erasable semiconductor memory devices are mainly ceramic packages.

This ceramic package consists of structural members such as a ceramic base and cap, a lead frame, quartz glass for forming a transparent window, and lead low-melting glass for bonding the base, cap, quartz glass, and cap. There is.

When a semiconductor memory chip is mounted in this ceramic package to produce a photo-erasable semiconductor memory device, it costs 400 yen.
A paste mainly composed of gold or silver powder is applied onto a base maintained at a temperature of ~600'C, a semiconductor memory chip (made of silicon) is placed on the paste surface, and further,
After rubbing several times and heat treatment to make it stick to the base, place the cap on the base, and fix it with a spring clip to prevent the cap and base from misaligning and to apply appropriate pressure. s
Heat treatment is essential when enclosing the semiconductor memory chip by passing it through an o'c oven and melting the low melting point glass disposed at the sealing portion of the cassop and base. Moreover, the time required for this heat treatment extends to several tens of minutes.

Problems to be Solved by the Invention Similar to other semiconductor integrated circuit chips, the pattern size of semiconductor memory chips is rapidly becoming finer.
As three-dimensional dimensions continue to shrink, the characteristics of semiconductor memory devices are becoming more susceptible to thermal influences or mechanical stress based on thermal stress than ever before.

Therefore, when a photo-erasable semiconductor memory chip having a fine pattern is mounted in a ceramic package that requires heat treatment at 400 to 600'C for several tens of minutes, the characteristics will be seriously affected.

Furthermore, the constituent members of the ceramic package are all made of expensive materials, and the package on which the semiconductor chip is mounted is expensive, which poses a problem that becomes an obstacle to lowering the product price.

Means to Solve the Problems In order to solve the above problems, the present invention uses a ceramic material (1) that avoids the use of expensive components such as glass or low-melting glass, and can be packaged by heat treatment at low temperatures. This realizes a structure in which a photo-erasable semiconductor memory chip is mounted in a plastic package.

In other words, the feature of the photo-erasable semiconductor memory device of the present invention is that the photo-erasable semiconductor memory chip is fixed to the substrate supporting portion of the lead frame, and a thin metal wire is used between the electrodes on the same erasable semiconductor memory chip and the inner leads. A light-transmitting window plate made of quartz or hard glass is disposed directly above the optically erasable semiconductor memory chip of the connected assembled structure;
Furthermore, these have a structure in which the transparent window plate is exposed and sealed with resin.

Function: Since the photo-erasable semiconductor memory device of the present invention has a resin-sealed structure, the heat treatment temperature required during its manufacturing process can be lowered. Also.

The use of expensive components is limited to the light-transmitting window panel.

Embodiment An embodiment in which the photo-erasable semiconductor memory device of the present invention is realized as a plastic sealed dual in-line package (hereinafter referred to as DIP) structure will be described below with reference to FIGS. 1 to 6.

1 to 6 show process diagrams for realizing the DIP structure.

First, as shown in FIG. 1, a photo-erasable semiconductor memory chip (hereinafter referred to as semiconductor (abbreviated as chip) 3 is fixed. Fixation by gold-silicon eutectic method is 400-500
Carry out under inert gas at °C. On the other hand, fixation using the silver paste method.

After the semiconductor chip 3 is attached to the substrate supporting part 1 with silver paste, the silver paste is cured in an atmosphere at a temperature of 150 to 300'C. Next, the bonding pad 6 formed on the semiconductor chip 3 is connected to the tip of the inner lead 2 of the lead frame using a thin wire 4 made of gold or copper. For this connection, for example, a thermocompression pole bonding method is employed. then 1
As shown in FIG. 2, a gel-like transparent resin 6 such as silicone which exhibits elasticity in a cured state is applied onto the surface of the semiconductor chip 30, and is further cured in a dry air atmosphere at 150'C. The coating thickness of the transparent resin 6 is set to be approximately the same as the highest point of the wire 4.

Thereafter, as shown in FIG. 3, a light-transmitting window plate 7 made of quartz or hard glass with an appropriate thickness is prepared, and one side of the plate 7 is coated with the same transparent resin 8 as that applied to the top surface of the semiconductor chip 3. Further, on the transparent window plate 7, the coated transparent resin 8 and the transparent resin 6 covering the semiconductor chip 3 fixed on the lead frame are made to face each other, and then the two are brought into contact with each other. It is cured again in a dry air atmosphere at 160'C to 200C. Through this process, an integral structure is formed in which the semiconductor chip 3 and the light-transmitting window plate 7 face each other via the transparent resin layer 9 in which both transparent resins are integrated (FIG. 4).

The integral structure formed as described above is placed in a plastic mold, and only the carbon blank, which is a light shielding agent, is removed. The soil is formed to form a structure. The temperature during molding is 160 to 180"C. Figure 6 shows the state after molding, and the light-transmitting window plate 7 is not completely embedded in the epoxy resin 10. Board 7
A groove 11 is formed around it so that only a part of it is embedded.
Set it up.

Next, as shown in FIG. 6, an epoxy-based embedding resin 12 is poured into the groove 11, which is gel-like when in use and has similar properties to the surrounding epoxy resin 1o after hardening.
Cure at a temperature of 160-200"C.

Note that the embedding resin 12 has a thermal expansion coefficient that is intermediate between those of the transparent window plate 7 and the epoxy resin 10, and no mold release agent was mixed therein, and a large amount of adhesive was mixed therein. It is desirable that it be located between the light-transmitting window plate 7 and the epoxy resin 1o to provide a buffering effect against thermal expansion against temperature changes. It goes without saying that the embedding resin 12 should be one that does not contain carbon black, which is a light shielding agent.

Through the above process, a photo-erasable semiconductor memory device of the present invention having a DIP structure is completed.

In the explanation above, the DIP structure is exemplified, but the package structure is not limited to this.

Effects of the Invention The photo-erasable semiconductor memory device of the present invention can be manufactured using ordinary molding resin, and the maximum processing temperature for one packaging is a low temperature of 200'C or less, so there is no characteristic variation due to heat. Even if this structure is adopted for a photo-erasable semiconductor memory device with a fine pattern that is easy to accept, there is no risk of causing characteristic fluctuations.

Furthermore, since no expensive structural members are required except for the light-transmitting window plate, it is possible to suppress a rise in product prices.

[Brief explanation of the drawing]

1 to 6 are process diagrams showing an example of the manufacturing process of a photo-erasable semiconductor memory device of the present invention. 1... Board support part, 2... Inner lead, 3... Semiconductor memory chip, 4...
・Wire, 6...Ponding pad 16.
8...Transparent resin, 7...Translucent window plate,
9...Transparent resin layer, IQ...Epoxy resin, 11...Groove, 12...Filled resin. Name of agent: Patent attorney Toshio Nakao and one other person
Rizuka Castle Mound Q Rizuka

Claims (2)

[Claims] (1) The photo-erasable semiconductor memory chip is fixed to the substrate supporting portion of the lead frame, and the electrodes on the photo-erasable semiconductor memory chip and the inner leads are connected by thin metal wires. A light erasing device characterized in that a light-transmitting window plate made of quartz or hard glass is disposed directly above the memory chip, and further, the light-transmitting window plate is exposed and sealed with a resin. type semiconductor memory device. (2) A photo-erasable semiconductor memory device according to claim 1, characterized in that a gel-like transparent resin is interposed between the photo-erasable semiconductor memory chip and the light-transmitting window plate. .