JPS5895843A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To remove only the desirable region of a passivation film completely, and to obtain the semiconductor device having high reliability by mounting a means, which monitors the completion of the removal of the desirable section of the passivation film, onto a thin-film. CONSTITUTION:A photo-resist film 10 is melted by using a solvent while an aluminum layer 12 adhering onto photo-resist films 9 is also exfoliated from a semiconductor substrate at the same time. The residual aluminum layer forms a monitor section 13 at that time. The passivation film 14 consisting of silicon oxide, etc. is shaped onto the whole on the semiconductor substrate including a section on the monitor section 13 through a method such as sputtering. A photo- resist film 15 with openings at sections on active regions corresponding to positions, from which the passivation film 14 must be removed in order to connect to external circuits, and a section just above the monitor section 13 is shaped. The passivation film 14 is etched while using the photo-resist film 15 as a mask, and the sections corresponding to the openings of the photo-resist film 15 are selectively removed. When the passivation film 14 is incompletely removed at that time, the passivation film 14 also remains on the monitor section 13, and the removal of the passivation film of the desirable region can be monitored.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device, and in particular to an insulating film (passivation film) for protecting the surface of a semiconductor substrate.
The present invention relates to a method of manufacturing a semiconductor device having the following.

In a semiconductor device, after forming desired active regions and wiring metal layers for connecting them to an external circuit, an insulating film (passivation II) is formed over the entire surface of the semiconductor substrate in order to protect the surface of the semiconductor substrate. is well known.

(17) In a semiconductor device having a passivation film, in order to connect the semiconductor device to an external circuit, it is important to completely remove the passivation film only from a desired region of the passivation film. If the removal of the passivation film within the desired region is incomplete, bonding will be incomplete and this will eventually lead to a decrease in the reliability of the semiconductor device. For products that require high reliability, if gold is used as the electrode,
A barrier metal film is required to prevent gold from diffusing into the semiconductor, and an adhesive metal layer is also required to improve the adhesion between this metal layer and the passivation film. It is normal.

When the passivation film is deposited on a conductor substrate having a multilayered gold electrode and the passivation film is to be removed only from a desired area, the top layer of gold can be removed using various chemicals such as passivation film etching solutions. It is difficult to judge whether the desired area of the passivation film has been completely removed, and if the passivation film is stable, it may cause 1-bar etching of the passivation film, and the openings larger than the desired area may be removed. Sometimes it caused. In particular, in a semiconductor device having a fine pattern such as a high-frequency transistor, the size of the opening is inevitably limited, and over-etching of the opening becomes a factor in reducing the reliability of the entire semiconductor device. The present invention has been made in view of the above points, and it is possible to completely remove only the desired area of the passivation film by using means for monitoring whether the removal of the desired portion of the passivation film is completed. The purpose of the present invention is to provide a manufacturing method that allows a highly reliable semiconductor device to be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings, taking as an example a case in which the present invention is applied to the manufacture of a silicon diffused planar transistor element for high frequency use. 1 to 10 are cross-sectional views showing the state of each process step in the above-described embodiment of the present invention. FIG. 1 shows a substrate constituting the collector region (
Forming a base region (2) on a part of one main surface of 1),
Further, an emitter region (3) is formed in a part of the active region, a silicon oxide layer (4) is formed on the main surface, and a base window (2a) and an emitter window (3a) are formed on this silicon oxide layer (4). ) is formed.

FIG. 2 shows that a platinum silicide layer (5) is formed on the emitter window (3a) and the base window (2a) to obtain a low-resistance ohmic contact, also using the usual method. A metal layer (9) for wiring is selected, which has a shape and consists of a titanium layer (6) as an adhesive metal layer, a platinum layer (7) as a barrier metal layer and a gold layer (8) as a top metal layer. This shows the state in which it was formed.

Hereinafter, we will move on to the essential steps of this invention. Figure 3 shows that a photoresist film Q (I) is deposited on the upper surface of the semiconductor substrate in the state shown in Figure 2, and the photoresist openings (11) are formed in the silicon oxide layer outside the active area using ordinary photolithography. (4
) shows a state in which a photoresist pattern is formed on top of the photoresist pattern.

Figure 4 shows the photoresist film 11 including the inside of the opening (11).
A state in which aluminum XOa is formed on the entire upper surface of 10 by a method such as vapor deposition or sputtering is shown.

Continuing on, FIG. 5 shows that the photoresist film QO is dissolved using a solvent such as acetone, and the photoresist film 0 is dissolved.
) was also peeled off from the semiconductor substrate, and the portion that had been adhered to the silicon oxide layer (4) without the photoresist film [opening area (1
The state in which only the portion corresponding to N) remains is shown. This remaining aluminum layer is part of the monitor, which is the key point of this invention.

FIG. 6 further shows a state in which a passivation film (141) made of silicon oxide or the like is formed by sputtering, for example, over the entire semiconductor substrate in the state shown in FIG. 5, including a portion of the monitor.

Next, in Fig. 7, on top of this passivation at+<,
A photoresist film having openings directly above the active region and part of the monitor corresponding to the part where the badging film (I4) is to be removed for connection with an external circuit, which is the purpose of this example. Indicates the state in which 0 phrases have been formed.

FIG. 8 shows the above photoresist film 019 in which a mixed solution of nitrous acid and ammonium fluoride aqueous solution (for example, a reaction ratio of 5:1) is used.
The passivation film C14) made of silicon oxide, for example, is etched using the mask as a mask, and the portions corresponding to the openings in the photoresist film are selectively and completely removed. H is the opening for connecting the emitter, and 0η is the opening for connecting the base. 0 FIG. 9 shows a state in which a portion of the monitor made of aluminum N was subsequently removed using an etching solution such as hydrochloric acid.

The point of this embodiment is that it is possible to monitor whether a desired area of the passivation film has been completely removed by checking whether the monitor portion 01 is completely removed at this stage. That is, at the stage shown in Figure 8,
If the removal of the passivation film ON is incomplete, this means that the passivation film (14+) remains on the monitor part 0, so let's etch the monitor part 01 made of aluminum with an etching solution such as hydrochloric acid. However, since the etching solution does not come into direct contact with the aluminum, a portion of the monitor (11) is not removed as shown in FIG. 04) can be confirmed to have been removed.Moreover, since the gold layer (8) is likely to be exposed in the emitter connection hole θ and the base connection hole (17), this aluminum etching solution will not cause any effect. - I also don't accept it.

Now, FIG. 1θ shows a state in which the photoresist film a has been removed and the work of opening a hole for connection of an external circuit to the passivation film 4 has been completed. The gold layer (8) is exposed in both the emitter connection hole H and the base connection hole 07).

After the M10 diagram, the element can be cut out as a single element by well-known methods such as back lapping, scribing, and pre-king, and mounted in a semiconductor device package to obtain a semiconductor device having desired performance.

In the above embodiment, a silicon planar transistor element having a gold electrode structure consisting of a titanium layer, a platinum layer, and a gold layer in a platinum silicide layer was described, but the present invention is not limited to the gold electrode having the above structure. It is clear that the present invention can be applied to an electrode structure in which the upper layer is a gold layer, and the semiconductor substrate is not limited to silicon, and can be widely applied to the manufacture of semiconductor devices other than planar transistors. Also,
Although a case has been described in which a silicon oxide film formed by sputtering is used as the passivation film and aluminum is used as the material for a part of the monitor, it is of course possible to select any material as long as it is consistent with the gist of the present invention.

In short, in the present invention, when opening a window in a desired region of a buffer film of a semiconductor device having an electrode structure in which the uppermost layer is a gold layer, the window can be easily etched with an etching solution that does not etch the gold, the semiconductor substrate, and the passivation film. A part of the monitor made of a transparent base metal is formed before forming the passivation film, and after the passivation film is formed, a window is opened in the passivation film including the top of this part of the monitor, and the part of the monitor is selectively etched. The key point is to monitor the removal of the passivation film in the desired area by checking whether a part of the monitor is completely removed with the etching solution.
The material for forming part of the monitor may be any material as long as it satisfies the above conditions, but aluminum is extremely suitable because it can be formed by a simple method.

As detailed above, in the manufacturing method of the present invention, the removal of the passivation film can be monitored and the completion of the removal can be detected, so that the openings in the passivation film are not made too large and the semiconductor device with a fine pattern can be manufactured. Even its manufacturing yield and product reliability can be improved.

[Brief explanation of drawings]

FIGS. 1 to 10 are cross-sectional views showing the state at each process step of an embodiment of the present invention. In the figure, (1) is a semiconductor substrate, (2) is a space region, (3) is a collector region, (8) is a gold layer, (9) is a wiring metal layer, (131 hamonitor part (metal film), ( 14)
is a passivation film (protective insulating film), 0@ is an opening for emitter connection, and Oη is an opening for base connection. Note that the same reference numerals in the figures indicate the same or corresponding parts. 〉 〉 \Figure 5 Figure 8 Figure 9 Figure 1O

Claims (2)

[Claims] (1) After forming an active region in a semiconductor substrate and forming a wiring metal counterfeit whose top layer is at least a gold layer in order to take out the electrical function of the active region, the semiconductor substrate including the top layer of the wiring metal layer is formed. A method for manufacturing a semiconductor device comprising the steps of: forming a protective insulating film on a substrate; and forming an opening in the protective insulating film for connecting the wiring (metal layer) to an external circuit; Before forming gold, a gold film that can be easily etched with an etching solution that does not substantially etch the semiconductor substrate and the protective insulating film is formed on a portion of the semiconductor substrate that does not affect the electrical function. Then, the protective insulating film is formed, and an opening is formed in the insulating film on the metal film, so that the metal film is etched with the etching solution. A method for manufacturing a semiconductor device, comprising determining that formation of the opening in the insulating protective film is completed. (2) A method for manufacturing a semiconductor device according to claim 1, characterized in that aluminum is used for the metal film and hydrochloric acid is used for the etching solution.