JPS5860545A - Preparation of semiconductor device - Google Patents

Abstract

PURPOSE:To improve the memory retention characteristic by forming a laminated body of resin both by coating and dropping methods and thereby increasing the thickness of a film and the uniformity thereof. CONSTITUTION:A wafer 1 is coated with resin 3, and the wafer whereon the resin 3 is left only in a prescribed part by photoengraving is cut in a prescribed size, whereby a chip 7 is formed. Next, the chip 7 is fixed at a prescribed position 8 in a semiconductor vessel 5, wire bonding with an Al wire 9 is conducted thereafter, liquid resin 10 is dropped thereon and cured by heating, and then sealing is made by a cover 11.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of manufacturing a semiconductor device with improved memory retention characteristics of a large-capacity semiconductor memory element.

The cause of unstable memory retention in the above-mentioned large-capacity storage elements is the direct decay of five radioactive elements, such as clan and thorium, which are generally contained in trace amounts in semiconductor containers that house semiconductor elements. The α particles generated during this process penetrate into the semiconductor device, and due to the energy possessed by the α particles, an 'Ic dissociation phenomenon occurs in the semiconductor device, and a large number of electrons generated by ionization temporarily dissipate. It confuses memory and action.

Currently, a method of coating the surface of a semiconductor element with a highly purified resin is often used as a method for shielding alpha particles from entering a semiconductor element. With reference to FIGS. 1 and 2, coating methods that are currently widely used and their drawbacks will be described.

FIG. 1 shows a method of applying resin to a predetermined portion of a quefer in a quefer state. First, as shown in Figure O1, the quefer (1) is fixed on a spinner (2), and the resin (3) is uniformly applied to the surface of the quefer (1).

Figure 1 f shows resin (3) and quahar 11) with uniform vehicle weight. Next, as shown in FIG.
◇This is a method in which the thus formed wafer is cut into predetermined dimensions and then mounted inside a semiconductor container.

In this case, the resin film thickness can be controlled by the viscosity of the resin and the rotation speed of each biner, but due to the limitations of photolithography and the limits of film thickness control, to-go =
It has the drawback that it can only be manufactured with a film thickness of about 10 microns with good reproducibility, and it is difficult to obtain a film thickness of several tens of microns or more.

FIG. 8 shows a method of cutting the wafer into chips (4), fixing them in a predetermined semiconductor container (5), completing predetermined wire bonding, and dropping the sickle and drop-shaped resin (6). This method has the disadvantage that there is a large difference in film thickness between the center of the drop and the periphery after the drop is heated and cured. In addition, depending on the type of liquid resin, the liquid resin does not spread well, and there is a drawback that extra man-hours are required, such as mechanically spreading the resin after dropping or blowing compressed air to spread the resin.

The present invention has been made to address the drawbacks of the above methods. An embodiment thereof is shown and explained in FIG. 8. First of all
Coat the wafer fil K resin (3) in the same manner as shown in the figure, and use photolithography to cut the wafer into a predetermined size, leaving the resin (3) only in the predetermined portions, to form a chip (7). . This chip (7) is securely fixed at a predetermined position (81) in the semiconductor container (5).

After that, wire bonding is performed using an Al wire (9), and then a liquid resin (lα) is dropped, and the resin is cured by heating and sealed with a lid (11).

As described above, since the present invention uses both the coating method and the dropping method to form a resin laminate, it is possible to easily obtain a film thickness of several 105 chrome or more for the entire resin layer. As the variation in distribution becomes smaller, the limit of the thinnest resin layer becomes clear. Further, by dropping droplet-shaped resin onto the cured resin, the spread of the resin can be improved and the uniformity of the film thickness can be improved.

Furthermore, by increasing the film thickness and improving uniformity, the memory retention characteristics of the semiconductor memory element can be significantly improved.

Note that the components of the resin layer selectively formed on the surface of the quefer and the components of the liquid resin further dropped thereafter do not necessarily have to be the same.

[Brief explanation of the drawing]

1 and 8 are sectional views showing a conventional example, and FIG. 8 is a sectional view showing a first embodiment of the present invention. ill Quahar, +21 spinner, 131 resin, (4)
Chip, (6) Semiconductor container, (61 Liquid resin, (7) Chip, (111 Predetermined position of container, AI thin wire, Ua liquid liquid resin, (■) Sealing lid O Agent Shin Kuzuno - Figure 1 rr : Q diagram

Claims (1)

[Claims] A step of applying a resin that shields alpha rays to the surface of the wafer on which a semiconductor memory element is formed, a step of cutting the wafer coated with the resin into a predetermined shape to form a chip, and a step of fixing the chip to a semiconductor container. A method for manufacturing a semiconductor device, the method comprising the steps of: performing wire bonding, and then dropping a liquid resin that blocks alpha rays onto the resin to form a resin laminate.