JPS60210850A - Manufacture of semiconductor ic device - Google Patents

Abstract

PURPOSE:To obtain the titled device regardless of the thickness of protection film and without the adverse effect of the dispersion of a fuse medium by a method wherein the fuse medium is covered with a protection film in the part other than the section to be fused, and is irradiated with laser beams. CONSTITUTION:An SiO2 film 2, a poly Si 3 (fuse medium), and a PSG4 are superposed on the inactive region of an Si substrate 1. The PSG4 is opened 7 and the protection film 6 is deposited, which is then opened 8 smaller than the hole 7, thus exposing the poly Si 3. Next, the poly Si 3 is fused 9 by irradiation with laser beams I through the hole 8. This construction enables secure fusion with good reproducibility without being influenced by the thickness of the protection film 6, because of direct irradiation of the poly Si 3. Further, the protection film 6 allows the deposition of the substance dispersing by fusion entirely on the film 6, resulting in no harmfulness.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a method for manufacturing a large-scale integrated circuit device (VLSI). This invention relates to an improvement in the method of electrically replacing a defective circuit section with the above-mentioned redundant circuit when a defective circuit section occurs during the manufacturing process.
Even if a problem occurs, the method of replacing it with a redundant circuit is
This method is expected to significantly improve the manufacturing yield of I, and is suitable for dynamic RAM of 256 kilobits or more (
Random Access Memory).

FIG. 1A''-C is a cross-sectional view showing the main stages of the conventional method. First, as shown in FIG. 1A, the semiconductor substrate (
A medium, such as a polysilicon line (3), which acts as a switching fuse is placed on the non-active area of
), and then surface flattening and bonding properties. . Oi,
. Yeah. Suyka, x (psoffZ.

A protective film (4) made of glass (BPSG) is formed. On the other hand, as shown in Figure 1B, neodymium:Yttri, aluminum garnet (Nd:YA
G) A hole (5) is formed in the protective film (4) using a laser, an argon (Ar) ion laser, etc., and the polysilicon line (3) is fused at that portion. Next, Figure 1C
As shown in the figure, the upper part is covered with a passivation film (6) such as a plasma nitride film to protect the surface and prevent impurities and moisture from entering.

On the upper side, the protective film (4) was also removed at the same time by laser beam I, but it only caused damage such as cracks to the protective film (4), and the polysilicon line (3) may be partially removed. is the power of the laser beam.

Figure 2 shows the relationship between the thickness of the PSG film (4) and its laser light reflection coefficient when the protective film (4) KPSG film is used. In the diagram shown, PSG
The light absorption of the polysilicon line (3) under the film (4) varies greatly depending on the thickness of the PSG film (4).

Therefore, a problem arises in the reproducibility of the melting of the polysilicon line (3) due to a change in the thickness of the PEG film (4).

In addition to the conventional method described above, there is also a method in which the polysilicon line (3) is fused with a laser before depositing the protective film (4), but this method prevents polysilicon from scattering. In addition to the serious problem of causing a short circuit in an undesired area due to the scattered polysilicon, there is also concern that it may cause a raised level difference in the area to which the scattered polysilicon is attached, which may have an adverse effect on subsequent processes.

Note that although we have explained K only for fusing, in some cases, contrary to fusing, it is possible to dope impurities to both ends of the polysilicon, and then shine a laser beam on the high-resistance polysilicon in the middle to inject impurities into that region. A method of electrically connecting by diffusing from both sides may also be used.

FIG. 3 is a flow diagram showing the VLSI manufacturing process when using the above conventional method. In the "wafer process", the form shown in FIG. Then, there is a step of cutting and replacing the polysilicon wire (3) that functions as a fuse using "laser cutting." This is a completely different process from the conventional wafer manufacturing process, and there are many problems in managing the clean room and avoiding wafer contamination due to these processes.

[Summary of the invention]

This invention was made in view of the above points, and it is possible to form a passivation film in the area where the fuse medium is to be switched with a redundant circuit by irradiating the laser beam with the laser beam, and then directly expose the fuse medium only in that area. Then, by irradiating the laser beam with K, it is possible to protect the film without being affected by the thickness of the protective film as in the conventional example.
This invention provides a method for manufacturing a VLSI that does not have any adverse effect on the circuit even if the fuse medium is scattered by laser beam irradiation. [Embodiment of the Invention] Figures 4A to 4E show the main steps of an embodiment of the invention. FIG. 5 is a sectional view showing the state at each stage, and FIG. 5 is a diagram showing the flow of the process.

First, as shown in FIG. 4A, in the same way as in FIG. PSG films (4) are sequentially formed. This PEG film (
4) In the circuit section, patterning and etching are normally performed in a process called contact. In this example, this process is used to create a PSG film (
An opening (7) is formed only in 4). Next, as shown in FIG. 4C, a passivation film (6) is deposited including the inside of the opening (7), and then, as shown in FIG. A hole is made in the membrane (6) (
7) Form an opening (8) with a smaller diameter and expose the polysilicon line (3) at its bottom. The above process is a process for forming an opening for taking out a pad portion for wire bonding after metal wiring in the manufacturing of a normal semiconductor device, and corresponds to the "wafer etching process" K in the flowchart of FIG. The wafer has now almost completed its processing process and is ready for the "test process".
be passed around. This test examines the circuit function, and for defective parts, the polysilicon wire (3) serving as the fuse medium is blown out in a "laser blowing" process and replaced with a redundant circuit. In this embodiment, as shown in FIG. 4, the process step is completed by irradiating the polysilicon line (3) with a laser beam through the opening (8) to form a fusing portion (9). Thereafter, as shown in Fig. 5, the ``fusion part chip retest'' is carried out, and then the ``assembly process'' is started.

In this way, the laser beam irradiation for fusing the polysilicon line (3) is directly applied to the polysilicon line (3), so it is not affected by the thickness of the PEG film as in the conventional method. , fusing can be performed reliably with good reproducibility. Furthermore, in the method of this embodiment, the laser beam (2) is irradiated with the entire upper surface covered with the passivation film (6) except for the portion of the polysilicon line (3) to be irradiated with the laser beam (2). Even if there is resistance to adhesion of substances scattered by melting, it is all due to the passivation film (6)
It is completely harmless because it is above.

〔Effect of the invention〕

As explained above, in the method of the present invention, a redundant circuit section is created in a VLSI, and when a defective section occurs during the manufacturing stage of the VLSI, a laser beam is emitted on the required part of the fuse medium formed inside the VLSI. When replacing the defective part with the redundant circuit section by irradiating it to fuse or conduct, the laser beam irradiation is performed after forming passivation i on the entire upper surface except for the area to be irradiated with the laser beam. Since the fuse medium is directly exposed and is not affected by the thickness of the protective film, it is possible to obtain a method for manufacturing a semiconductor integrated circuit device in which the circuit is not adversely affected even if the fuse medium is scattered by laser beam irradiation.

[Brief explanation of the drawing]

Figure 1 A-0 is a cross-sectional view showing the state at the main stage of the conventional method, Figure 2 is a diagram showing the relationship between the thickness of the P8G retention film on the fuse medium and the laser beam reflection coefficient. 4. A flow diagram illustrating the manufacturing process of VL8 I using this conventional method. FIG. It is a flow diagram of a process. In the figure, (1) is a semiconductor substrate, (2) is an oxide film, (
3) is a fuse medium (polysilicon line), (4) is a protective film (PSG film), and (G) is a passivation film. In addition, the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A redundant circuit section is formed in the semiconductor integrated circuit device, and when a defective section occurs in a part of the semiconductor integrated circuit device, a laser beam is irradiated to the required part of the fuse medium formed inside the semiconductor integrated circuit device. When replacing the defective part with the redundant circuit section by melting it or making it conductive, a passivation film is formed on the entire upper surface of the semiconductor integrated circuit device except for the required portion of the fuse medium, and then the laser beam is irradiated. A method for manufacturing a semiconductor integrated circuit device that is characterized by performing 0 (2) The method of manufacturing a semiconductor integrated circuit device according to claim 1, wherein the passivation film is formed so as not to expose an end of the protective film on the fuse medium.