JPS59130463A - Integrated circuit device - Google Patents

Abstract

PURPOSE:To shorten the delivery time from order receiving to shipment and improve the moisture resistance by a method wherein an oxide film with the formation of phosphorus glass is provided on one main surface of a semiconductor substrate, a plurality of holes reaching to one main surface of the substrate are provided through this insulation film, a group of holes of these holes are filled with a vapor grown oxide film, and the remaining holes are filled with a metal which forms a conductor contacting one main surface of the substrate. CONSTITUTION:An Si gate 23 and N<+> regions 22 serving as the source and drain are formed, according to normal processes, on the Si substrate of a specific resistance 4OMEGA-cm. All the contact holes 26 are bored by using the first contact mask, next a vapor grown oxide film 27 is formed 0.5mu over the entire surface of a wafer, and then heat treatment is performed for 20min in a steam atmosphere of 900 deg.C in order to make this Si oxide film dense. Then, using the second contact mask, desired contact holes 26' are bored according to an ROM code, and an aluminum wiring 24 is formed, resulting in the formation of an ROM.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an integrated circuit device, and particularly to a read only memory (hereinafter abbreviated as ROM).

Resistors, capacitors, diodes, etc. can be used as elements of the ROM matrix, and in the early days of digital computers, ROMs using simple diodes were used, but now it is common to use MO8 type transistors. With the spread of microcomputers,
Many codes have come to be used for ROM, which is one of its components.

Except for programmable ROM (FROM), which can be electrically programmed and erased by ultraviolet irradiation or electrically, general ROM is called mask ROM, and code selection is based on the MO8 type that makes up the ROM matrix. This is done by selecting the presence or absence of a transistor gate or contact, etc. using a gate mask or a contact mask, but in order to shorten the period from receiving an order to shipping a ROM code, it is recommended to select it as close to completion as possible. However, nowadays it is common to use contacts.

First, a conventional mask ROM using a contact selection method will be explained using FIG. FIG. 1(A) is a top plan view of the structure of a silicon game hMO8 type ROM, and FIG. 111(B) shows a cross-sectional structure taken along line xx' in FIG. 1(A). be. In this figure, the ROM code has been selected by a contact mask. In this structure, the portion of the oxide film 11 that contacts the aluminum wiring 14 becomes phosphorous glass.

It is normal to have However, due to the presence of a small amount of water in the phosphorus glass, P, O, + 3H
, O-+ 2H, PO.

This reaction causes phosphoric acid, which deteriorates the aluminum wiring, so this structure has very low moisture resistance.

To solve this problem, a vapor-grown silicon oxide film with a thickness of 0.1 to 1.0 μm is formed between the phosphorus glass layer and the aluminum, and this silicon oxide film is heat-treated to make it denser. A method is being considered that does not allow direct contact between the wires. However, in this case, the thickness of the silicon oxide film at the contact portion becomes thicker, which causes new drawbacks such as making contact e-etching difficult and making it easier for the aluminum to break at the contact portion.

In order to solve this problem, contact holes are formed using the same contact mask before and after forming the vapor phase grown silicon oxide film. According to this method, when drilling the first contact hole, the shape of the contact is opened with a taper ← in the center, so the level difference in the oxide film in the contact hole after the next vapor-phase grown silicon oxide film is laid is reduced. This has the advantage that there are fewer abrupt steps in the oxide film, making it less likely that the aluminum step will break at the contact area.
Since the process of forming a contact hole, forming a silicon oxide film by vapor phase growth, and forming a contact hole is long, there is a disadvantage that the delivery time from receiving an order to shipping the %ROM code is delayed.

It is an object of the present invention to provide an effective semiconductor device, particularly an effective ROM structure, which solves the various drawbacks mentioned above.

The present invention is characterized in that a first insulating film, for example, an oxide film with phosphorus glass formed on the surface, is provided on the entire surface of the semiconductor substrate, and a plurality of holes are provided in the first insulating film that reach the entire surface of the substrate. One group of the plurality of holes is filled with a second insulating film, such as a vapor-grown oxide film, and one group of remaining holes is filled with a conductive material, such as wiring, which contacts the entire surface of the substrate. It is filled with metal that forms the

The present invention and embodiments will be explained below with reference to FIG.

Referring to Figure 2, it has a (5X1) plane and has a specific resistance of 4Ω-
A silicon gate 23, a source, and a drain N0 region 22 are formed on a silicon substrate of Om according to a normal process. Here, all contact holes 26 are opened using the first contact mask. Next, a vapor phase grown silicon oxide film 2'7 is deposited on the entire surface of the wafer to a thickness of 0.5 μm.
90°C to densify the silicon oxide film.
Heat treatment is performed for 20 minutes in a steam atmosphere. Then,
The ROM is completed by drilling desired contact holes 26' using the second contact e-mask according to the ROM code and forming aluminum wiring 24.

ROMs using this method can be stocked at the stage where all contacts are drilled using the first contact mask common to all codes and a vapor-phase grown silicon oxide film is formed, so after receiving an order for a ROM code, , the advantage is that the contact can be made only once and the delivery time from order to shipment can be greatly shortened, the advantage is that the phosphor glass and aluminum wiring are not directly welded, and the moisture resistance is very good. The intersection between the polysilicon wiring and the aluminum wiring also becomes thicker by the amount of the vapor-grown silicon oxide film, so the capacitance is reduced and the interaction between the potential of the polysilicon wiring and the potential of the aluminum wiring, so-called cross talk, is reduced. , there are advantages such as increased speed.

Although the embodiments of the present invention have been described using an N-channel type MO8IC as an example, it goes without saying that the present invention can also be applied to ROMs using P-channel type and complementary type MOE3 (0MO8). Further, although the example in which a vapor-phase grown silicon oxide film is spread on phosphor glass has been described, the silicon oxide film may be grown by sputtering or the like.

Heat treatment for densification of the silicon oxide film has the best yield when performed in a steam atmosphere, but it is also possible to perform heat treatment in a steam atmosphere. It could be the atmosphere, etc. It goes without saying that if the growth temperature of the silicon oxide film is high and the film is already sufficiently densified at the stage of growth, no heat treatment is required to densify the film. Furthermore, although the film thickness of the vapor-phase grown silicon oxide film is 0.5 μm, it is effective to take any value between 0.1 μm and 1.0 μm depending on the device. Further, the heat treatment for densifying the silicon oxide film is effective in the range of 700-1100°C.

[Brief explanation of the drawing]

FIG. 1(A) is a plan view of a ROM according to the prior art, and FIG. 1(B) is a cross-sectional view of FIG. 2 is a sectional view showing one embodiment of the present invention. In the figure, 11.2111@・thermal silicon oxide film, 12, 22...N diffusion layer (source/drain region) )
, ls, 2s...polysilicon (gate), 14,2
4φ...aluminum wiring, 15°25 working, 0 gate oxide film,
16...contact holes, 26...contact holes opened with the first mask, 26'...contacts opened with the second mask. No. 1 Loquat (A)

Claims (1)

[Claims] (1) A first insulating film is provided on the entire surface of a semiconductor substrate, and a second insulating film is provided on the first insulating film and extends over the second insulating film. In an integrated circuit device in which a wiring layer of a conductor is provided and a plurality of holes reaching the main surface are provided in the first insulating film, a group of holes among the plurality of holes are formed on the first insulating film. The remaining holes among the plurality of holes are filled with the conductive material, so that the wiring layer is formed in the remaining holes on the main surface. An integrated circuit device characterized in that it is in contact with. (2) The second insulating film is a silicon oxide film grown in a vapor phase, and the first insulating film is an insulating film having a phosphorus glass layer formed on its surface. ). (8) Claim (1) characterized in that the hole filled with a conductive or electric material is selectively determined by a memory code, and the integrated circuit device is a read-only memory. Or the integrated circuit device according to item 2. (4) The integrated circuit device according to claim (2), wherein the second insulating film has a thickness of α1 to LOμ.