JP2830067B2 - Method for manufacturing semiconductor device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device including an EPROM (ultraviolet erasing element), and more particularly to a method for manufacturing a semiconductor device including an EPROM (ultraviolet erasing element). It is about formation.

[Conventional technology]

5 and 6 are cross-sectional views showing the structure of a conventional EPROM and a semiconductor device including the EPROM (microcomputer with built-in EPROM, etc.). FIG. 5 is sealed in a ceramic package, and FIG. 6 is sealed in a cerdip package. It was done. In the figure, (1) is a ceramic lid, (2) is a quartz glass window,
(3) is a bonding wire, (4) is a semiconductor chip, (5) is a lead, and (6) is a sealing glass. In these, a chip (4) containing EPROM or EPRMO is die-bonded to a ceramic package, and each pad and a lead (5) are connected with a bonding wire (3).
It is sealed with a ceramic lid (1) (or a metal lid) with a quartz glass window (2).

Next, the operation will be described. In the above package, there is a gap between the chip (4) surface and the package,
No package stress is applied to the chip (4). However, it is rare that an EPROM is actually written / erased repeatedly over and over, and in most cases, once written, it is used without erasing.

Therefore, OTP (One Time) sealed in an inexpensive resin mold package without sealing an expensive ceramic package
Programmable (write once), ROM, and OTPROM built-in microcomputers are increasing in demand. FIG. 7 is a sectional view showing a structure of a semiconductor device sealed in a conventional resin mold package. In the figure, (3) to (5) are equivalent to those shown in FIG. (11) is a mold resin. In this case, since the mold resin (11) is generally opaque, once written, it cannot be erased again.

Another problem arises by using the mold resin package. Since the mold resin (11) is in contact with the surface of the chip (4), the stress of the mold resin (11) is applied to the chip (4), causing problems such as aluminum slide. An aluminum slide is a phenomenon in which the final protective film on the surface of the chip (4) cannot withstand the stress of the mold resin (11) and cracks occur, causing the aluminum wiring to move. In particular, the stress of the mold resin (11) is concentrated. Frequently occurs on the outer periphery of the chip (4), which poses a problem in reliability. In addition, fine particles, generally referred to as filler, are mixed in the mold resin (1) by a number of +%, and a malfunction of the semiconductor device due to a local stress caused by this is also a problem.

With the miniaturization, the above problems become apparent, and in addition to the improvement of the final protective film, a low elastic modulus film (buffer coat film) for buffering stress may be formed on the final protective film. More. Polyimide is often used as the buffer coat film. However, when polyimide is formed with a thickness of several μm or more that has a low transmittance of ultraviolet rays and provides a sufficient stress buffering effect, almost no ultraviolet rays are transmitted. Therefore, when polyimide is applied as a buffer coat film to an EPROM and a semiconductor device including the EPROM, the EPROM cannot be erased with ultraviolet light after the formation of the buffer coat film.

For this reason, in EPROMs and semiconductor devices including EPROMs, it was not possible to use a buffer coat film in a resin mold package.

FIG. 8 is a flow chart showing a flow from a wafer process to shipping when manufacturing a conventional EPROM and a semiconductor device including the EPROM. As shown in the figure, after the completion of the wafer process, a wafer test including a writing test of the EPROM is performed, the written contents are erased by irradiating ultraviolet rays, and assembly and sealing (assembly) are performed in a resin mold package.

[Problems to be solved by the invention]

Conventional EPRMOs and semiconductor devices including EPROMs are configured as described above, so high reliability could not be obtained because a buffer coat film could not be adopted even if it was formed into a resin mold package. .

The present invention has been made in order to solve the above-described problems, and suppresses a malfunction of an aluminum slide or a semiconductor device due to a stress of a mold resin, and has high reliability.
An object of the present invention is to provide a method for manufacturing an EPROM and a semiconductor device including the EPROM.

[Means for solving the problem]

According to a method of manufacturing a semiconductor device according to the present invention, a buffer coat film is laminated on one surface of a semiconductor chip, and the ultraviolet erasing element formed on one surface of the semiconductor chip is removed. An opening to be exposed is formed in the buffer coat film, the ultraviolet erasing element is irradiated with ultraviolet rays, and the semiconductor chip and the buffer coat film are covered with a mold resin.

[Action]

In the present invention, since the buffer coat film is provided on the chip surface, the stress received from the mold resin is buffered, and malfunction of the aluminum slide or the semiconductor device is suppressed.

〔Example〕

FIG. 1 is a plan view showing a chip layout of a semiconductor device according to a reference example of the present invention, and FIG. 2 is a sectional view showing a structure of a semiconductor device in which the chip of FIG. 1 is sealed in a resin mold package. In the figure, (4) is a semiconductor chip, (5) is a lead, (8) is an EPROM memory cell,
(9) is a bonding pad, (10) is a buffer coat film, and (11) is a mold resin. A bonding pad (9) connected to a lead (5) of the package is arranged on the outer periphery of the chip (4), and most of the chip (4) including the EPROM memory cell (8) (the bonding pad (9) if necessary) The entire surface (other than that) is covered with the buffer coat film (10).

Next, the operation will be described. Buffer coat film (10)
Can relieve the stress from the mold resin (11) and suppress malfunction of the aluminum slide or semiconductor device. As the buffer coat film (10), an organic / inorganic polymer film having a low elastic modulus such as a polyimide resin can be used, and preferably has a thickness of 1 μm or more.

Further, when the buffer coat film (10) is formed on the EPROM and the semiconductor device including the EPROM, it is necessary to change the flow from the wafer process to shipping from the conventional example.

FIG. 3 is a flow chart showing a flow of pressing a wafer process to shipping when manufacturing the semiconductor device of FIG. Although the flow up to the erasing of ultraviolet rays is the same as that shown in the conventional example of FIG. 8, in the case of a resin mold package, erasing cannot be performed after assembly, so that the all-bit write test cannot be performed after assembly. (The write / read test can be performed only in a part of the EPROM memory area that is not used by the user.) Therefore, a completed product test other than the EPROM all bit write test is performed. When writing by the user, it is shipped as it is (blank shipment). It is inevitable that the defect rate will be higher than that of the packaged product with a window because the EPROM all-bit write test cannot be performed in the finished product test. However, if possible, implement the EPROM write / test and ship (write shipment) By doing so, the defect rate can be reduced.

In FIG. 3, a wafer process is performed until a buffer coat film (10) is formed, and a wafer test including a write test of an EPROM is performed. By dropping, a buffer coat film (10) is formed on the surface of the chip (4). Thereafter, the product is sealed in a resin mold package, and a completed product test is performed except for an EPROM all-bit write test as in the case of the conventional example without the buffer coat film (10) before shipment. The relationship between blank shipment and write shipment is the same. In the case where the buffer coat film (10) is present, there is a possibility that a defect generated during the formation of the buffer coat film (10) after ultraviolet erasing may not be detected as compared with the conventional flow of FIG. If bad). Except for this point, the EPROM and EPR can be obtained by making the wafer process to the shipping flow as shown in FIG.
The buffer coat film (10) can be used for a semiconductor device including the OM.

FIG. 4 is a plan view showing a chip layout of a semiconductor device in which a buffer coat film is provided in a portion other than a memory cell and a bonding pad of an EPROM according to an embodiment of the present invention. In the figure, (8) to (10) are the same as those shown in FIG. A buffer coat film as an ultraviolet shielding film laminated on the chip 4 (10)
An opening for exposing the EPROM memory cell (8) is formed in
A buffer coat film (10) is formed on an area around the EPROM memory cell (8). As a result, the EPROM memory cell (8) is directly subjected to the stress of the mold resin (11). However, since the EPROM can be erased after the buffer coat film (10) is formed, the buffer coat film (10) Defects generated during the formation can be detected. or,
As described in the above embodiment, the buffer coat film (10) may be a low elastic modulus organic / inorganic polymer film such as a polyimide resin, and preferably has a thickness of 1 μm or more. Also, the ultraviolet light used for erasing the EPROM here is 100
2 nm using a mercury discharge lamp
Use 54nm UV light. As a result, the writing characteristics of the EPROM can be checked immediately before assembly. E
Exposure of the PROM memory cell (8) to the stress of the mold resin (11) may cause defects such as volatilization of EPROM storage data. However, as a result of the experiment, even if the buffer coat film (10) is not provided, EPROM memory cell (8) has buffer coating film (10)
The lack of coverage does not reduce reliability.

On the other hand, by applying the buffer coat film (10), the occurrence of malfunction in the peripheral portion is suppressed, and in particular, the chip (4)
Aluminum slides due to stress concentrated around can also be suppressed.

〔The invention's effect〕

As described above, according to the present invention, since the chip surface of the EPROM and the semiconductor device including the EPROM is covered with the stress buffer film as the ultraviolet shielding film, the malfunction of the aluminum slide or the semiconductor device due to the stress from the mold resin package is suppressed. Since the EPROM can be erased after the formation of the ultraviolet shielding film, the writing characteristics of the EPROM can be checked immediately before the assembly.

[Brief description of the drawings]

FIG. 1 is a plan view showing a chip layout of a semiconductor device according to a reference example of the present invention, FIG. 2 is a sectional view showing a structure of a semiconductor device in which the chip of FIG. 1 is sealed in a resin mold package, and FIG. FIG. 4 is a flowchart showing a flow from the wafer process to the shipment when manufacturing the semiconductor device of FIG. 2;
FIG. 5 is a plan view showing a chip layout of a semiconductor device in which a buffer coat film is provided on portions other than the memory cells and bonding pads of an EPROM according to another embodiment of the present invention. FIGS. 5 and 6 show conventional EPROMs and EPROMs. FIG. 5 is a cross-sectional view showing the structure of a semiconductor device including a ceramic package, and FIG. FIG. 7 is a cross-sectional view showing the structure of a semiconductor device sealed in a conventional resin mold package, and FIG. 8 is a conventional EP.
9 is a flowchart showing a flow from a wafer process to shipping when manufacturing a semiconductor device including a ROM and an EPROM. In the figure, (4) is a chip, (5) is a lead, and (8)
Is an EPROM memory cell, (9) is a bonding pad, (1)
0) is a buffer coat film, and (11) is a mold resin. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A step of laminating a buffer coat film on one surface of a semiconductor chip and a step of forming an opening in the buffer coat film to expose an ultraviolet ray erasing element formed on one surface of the semiconductor chip. And a step of irradiating the ultraviolet ray erasing element with ultraviolet rays, and a step of covering the semiconductor chip and the buffer coat film with a mold resin.