JPS6379950A - Article having corrosion-resisting protective film and its production - Google Patents

Abstract

PURPOSE:To manufacture an article having a corrosion-resisting protective film containing an Al-alloy film, a PdO or PtO film, and an alumina film, by forming an Al-Pd or Al-Pt alloy film on an article and then by subjecting the above to heat treatment in an oxygen-containing atmosphere. CONSTITUTION:The Al alloy film 4 to which <3% Pd or Pt is added is formed on the surface of the article 1 by sputtering, vacuum vapor deposition, etc. Subsequently, the above coated surface is heat-treated together with the article 1 in an oxygen-containing gas, so that PdO or PtO film 6 is formed in the alumina film 5, by which the protective film containing three-component films of Al-Pd or Al-Pt alloy film 4, PdO or PtO film 6, and alumina film 5 is formed. In this way, the article excellent in bondability and having corrosion- resisting protective film showing high corrosion resistance against chlorine, high-temp. water, etc., can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is applicable to articles requiring corrosion resistance, such as mechanical parts,
The present invention relates to an electrode structure suitable for highly reliable electrode wiring in a large-scale integrated circuit, and a method for manufacturing the same.

[Conventional technology]

Conventionally, in semiconductor devices using plastic packages, metal interconnects between elements or within elements are generally formed of thin aluminum wires or aluminum films.

In such an aluminum wiring strip, since the LEII is sealed with a resin or the like, various ions are likely to be liberated as moisture enters through the gaps and adhere to the wiring strip along with the moisture. As a result, corrosion during use has become a problem.

Therefore, two to three types of aluminum alloys have been proposed to completely prevent corrosion of metal wiring bands.

As shown in Japanese Unexamined Patent Publication No. 56-16647, an Al-Cu alloy has been developed as an A2#1 wire between semiconductor elements, but it has not been found to improve corrosion resistance for plastic packages.

Furthermore, as shown in Japanese Patent Application Laid-open No. 142988/1988, the %Al-Mn alloy was developed for use in Al films, but it has the disadvantage of poor bondability (also called bondability) with Al or Au wires. Contains.

Furthermore, an aluminum alloy containing all metals that have a smaller ionization tendency than Al is disclosed in Japanese Patent Application Laid-open No. 1241/1983, p, A/! In the examples, silver, palladium, gold, and platinum are cited as metals with a smaller ionization tendency. However, this aluminum alloy contains silver,
Since it contains palladium, gold, and platinum in a weight ratio of 0.1% or more, precipitates segregate at grain boundaries and are corroded by PCT (Pressure Hooker Test, 121°C, 2 atmospheres saturated steam corrosion test). There was a problem.

Furthermore, as the width of the wiring pattern becomes narrower and becomes a sub-micron pattern of approximately α8 μm, the problem arises that corrosion that occurs in areas where the concentration of added elements is low can lead to fatal wire breaks due to variations in the film composition distribution. It also has

[Problem that the invention seeks to solve]

The above-mentioned conventional technology does not give consideration to the corrosion resistance of wiring widths of 1 μm or less, and has a practically important problem in that corrosion breaks occur in fine wiring portions.

It is an object of the present invention to provide an article having a corrosion-resistant protective film free from the above-mentioned drawbacks and a method for manufacturing the same, which particularly improves the corrosion resistance of fine aluminum wiring and the reliability of plastic-packaged semiconductors. It's about doing.

[Means for solving problems]

To summarize the present invention, the first invention of the present invention relates to an article having a corrosion-resistant protective film, wherein the protective film is k
It is characterized by containing a five-component film: an alloy film of L and Pa or HPt, a PdO or PtO film, and an alumina film.

Further, a second invention of the present invention relates to a method for manufacturing an article having a corrosion-resistant protective film, wherein
It is characterized by including the steps of completely forming the l-Pct or Al-Pt alloy film, and heat-treating in an oxygen-containing atmosphere to produce the preservative film of the first invention.

In the method of the present invention, annealing in a normal hydrogen atmosphere may be performed after the step of forming the Al alloy film and before the oxidation heat treatment step.

The surface of the protective film in the present invention is preferably an oxide film containing alumina as a main component.

The present invention will be explained in detail below based on the accompanying drawings, but the objects of the present invention include not only aluminum wiring films but also a wide range of products such as mechanical parts that require corrosion-resistant protective films. It is clear that 0 FIG. 1 is a schematic cross-sectional view showing the structure of the protective film of one example of the article of the present invention, where 1 is the article, 4 is the Al alloy film, 5 is the alumina film, and 6 is the PdO or It means a PtO film.

As shown in FIG. 1, first Pi or Pt'! i 3%
The A4 alloy film 4 added below is formed on the entire surface of the article 1. The method may be a conventional method, but Al-Pd or Al-P
It is preferable to use t-alloy gold, sputtering, vacuum evaporation, ion blasting or CVD. Next, the article 1 is heat-treated in a gas containing oxygen, either by performing conventional hydrogen annealing in advance or without performing hydrogen annealing in a conventional manner.
An O or PtO film 6 is generated. This further improves the corrosion resistance of the article over conventional protective films.

When the product is aluminum wiring (Al itself is a metal wire mainly composed of Al), the corrosion of the aluminum base that makes up the entire aluminum wiring occurs after hydrogen atoms invade the aluminum film and diffuse into the interstitial space. , caused by precipitation at aluminum grain boundaries. Therefore, the surface of the aluminum wiring is coated with Pc1O or PT according to the present invention.

When covered with aluminum wiring, these oxides have a catalytic effect, converting hydrogen atoms into hydrogen molecules, preventing hydrogen atoms from penetrating into the interior of the aluminum wiring, and improving corrosion resistance. By providing a Pdo or PtO film in the alumina film of the casing, the corrosion potential of the aluminum wiring film can be shifted to a negative potential, that is, a direction in which corrosion is less likely to occur. Thereby, even if the aluminum wiring film comes into contact with water containing corrosive ions, the aluminum base can be prevented from dissolving.

Note that since the Al alloy is added near the surface of the aluminum wiring film, the wiring film does not become hard. As a result, when the aluminum wiring film is deformed during bonding, the oxide film on the surface is broken and a new metal surface of aluminum is exposed, resulting in a good bond.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Embodiment 1 FIG. 2 is a schematic cross-sectional view of a semiconductor device which is an embodiment of the present invention. In FIG. 2, numeral 11 is a silicon chip, 12 is a PEG film, 13 is a Vi protective film, 14 is a wiring conductor,
15 is a wire, 16 is a lead frame, 17 is an Al alloy film, and 18 is an epoxy resin mold.

As shown in FIG. 2, the semiconductor device t includes a silicon chip 11 placed on the upper surface of the central portion of a lead frame 16, a PEG (phosphorus glass) film 12 entirely formed on the silicon chip by CVD, and further After laminating the wiring conductor 14 on this PEG film by sputtering, the wiring conductor 14 is covered with a protective film 13. It is configured to be connected to the conductor 14 via a wire (aluminum wire) 15.

The Al alloy film 17 on the lead frame was prepared by the ion plate ink method, and the aluminum wiring conductor 14 on the silicon chip was prepared by the sputtering method. Al alloy film 1 on lead frame
7 has a film thickness of 5 μm.5 The aluminum wiring conductor 14 on the silicon chip has a film thickness of 0.8 μm.5 The bonding wire 15 uses an aluminum wire with a diameter of 30 μm, and the mold 18 is made using a conventional epoxy resin.

FIG. 3 is an enlarged schematic view of the abrasive surface of the wiring conductor 14 portion in FIG. .

The aluminum base 2 is an A7 alloy containing 1% silicon, and an Al alloy film 4 containing 1% Pd or 1% Pt is laminated thereon. After annealing it with hydrogen, the alumina film 5 and P(10 or PtO@6) are formed by heating it to 350° C. or higher in an oxygen-containing atmosphere.

For the tabulation, aluminum base '17500A was used.

Al alloy film '1500A is formed continuously. The thickness of the alumina film 5 produced by the oxidation heat treatment is 50 Å, and the thickness of the PdO or PtO film sandwiched therebetween is 2 OA.

Test Example 1 TEG (Te5t Element Group) of the resin molded semiconductor device according to the present invention shown in FIG.
) f was prepared and the moisture resistance was evaluated by PCT.

Table 1 shows the time required for the TEG wiring conductor to corrode and break. Note that the percentage in the composition column is Ndochi.

Table 1 As is clear from Table 1, the results of PCT at TEG,
The Al alloy film 4 shown in Fig. 6 showed good moisture resistance.
is a TEG using a film made by laminating an Al alloy added with 105 to 1% by weight of Pd or Pt,
On the contrary, the one with the lowest moisture resistance was the TE layered with a pure Al film.
It was G.

Test Example 2 A comparison of the corrosion resistance between an aluminum wiring film containing an Al-Pa alloy film subjected to conventional hydrogen annealing and one heated in an oxygen-containing gas after hydrogen annealing according to the present invention was conducted. FIG. 4 shows a graph of the relationship between PCT corrosion time (hours, vertical axis) and wiring width (μm1, horizontal axis).

As is clear from FIG. 4, as a result of examining corrosion disconnection in fine wiring portions using PCT, it was found that the wiring of the present invention exhibits more than 10 times the reliability of conventional wiring in patterns with a wiring width of 1.2 μm or less. I understand.

This is because in the conventional method, the surface of the wiring film under the protective film is oxidized, making it difficult to form a surface retaining film. Since the organic protective film allows moisture to pass through, the underlying wiring becomes susceptible to corrosion, and if the protective film on the aluminum surface is weak even in one area, it will corrode and the minute patterns will break.

Test Example 5 Figures 5 and 6 show the amount of Pd or pt added (
This is a graph showing the relationship between weight % (horizontal axis) and annual natural corrosion 't (normalized value with pure A7 as 1, vertical axis).

From each figure, to suppress annual natural corrosion, Pd or pt
It can be seen that it is suitable to limit the amount of addition to the range of 0.001 to 1.5% by weight. [Addition of less than 1% by weight of LO has little effect on reducing the annual natural corrosion amount;
When the weight percentage is exceeded, the annual natural corrosion amount tends to increase on the contrary.

Test Example 4 Figure 7 shows the results of measuring the detection intensity of PdO contained in the alumina film on the surface of the aluminum wiring film by XPS (photoelectron spectroscopy), and plots the Pd0 detection intensity (arbitrary scale, vertical axis) and p
It is a graph showing the relationship with a-added children (weight %, horizontal axis).

As is clear from Figure 7, the amount of Pi added is 0.01
If the amount is less than 1.0% by weight, pao is hardly detected, and if the addition amount exceeds 1.0% by weight, the detection intensity becomes constant and does not increase any further.

This result shows that a uniform PdO film can be formed in the alumina film by adding 0.1 to 1.0.2% Pd.

Test Example 5 Table 2 shows the bondability between the aluminum wiring film and the gold wire and copper wire. Note that the percentages in the composition column of Table 2 are weight - h.

Table 2 From Table 2, it can be seen that the amount of P (1 or pt added) is 0.01 to 1.
In the range of 5% by weight, the wiring film of the present invention can be compared to conventional Al-
It exhibits bondability equivalent to a wiring film of 1% by weight S1,
It can be seen that the protective film of the present invention is suitable as a semiconductor wiring film.

〔Effect of the invention〕

As explained above, according to the present invention, an article having a corrosion-resistant protective film superior to that of the prior art is provided.

In particular, the present invention has the remarkable effect of being able to provide a resin-sealed semiconductor device that has excellent bondability and is highly corrosion resistant in environments with various ions such as chlorine that corrode aluminum, and high-temperature water environments. .

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a protective a film of an example of the article of the present invention, FIG. 2 is a schematic cross-sectional view of a semiconductor device that is an example of the present invention, and FIG. Figure 4 is a graph showing the relationship between annealing sound effect PcT corrosion time and wiring width; Figure 5 is a graph showing the relationship between the Pd addition lid in the alloy film on the upper surface of the wiring film and the annual natural corrosion amount. Figure 6 is a graph showing the relationship between the amount of added PTL and Figure 7 is the relationship between the amount of P(l added and the XPS detection intensity of PdO contained in the surface alumina film). This is a graph showing.

Claims (1)

[Claims] 1. In an article having a corrosion-resistant protective film on the surface, the protective film is an alloy film of Al and Pd or Pt, PdO or Pt.
An article having a corrosion-resistant protective film characterized by containing a three-component film of an O film and an alumina film. 2. In the method of manufacturing an article with corrosion-resistant protection on the surface, first forming an Al-Pd or Al-Pt alloy film on the article, heat-treating in an oxygen-containing atmosphere,
Production of an article having a corrosion-resistant protective film, characterized in that it includes each step of producing a protective film containing a three-component film of an alloy film of L and Pd or Pt, a PdO or PtO film, and an alumina film. Method.