JPH07183296A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide excellent dimensional accuracy of a viahole of a polyimide resin film and to accurately expose a surface of an Al bonding pad by increasing the shape and the size of the viahole in a second polyimide resin film larger than those of a viahole in a first polyimide resin film layer. CONSTITUTION:The shape and the size of a viahole in a second polyimide resin film 6 is controlled by regulating the developing and etching times with alkaline aqueous solution to be larger than those of a first layer viahole 5. Then, using the obtained first and second polyimide resin films 4, 6 as mask materials, an inorganic insulating layer 3 of an upper part of an Al bonding pad 2 of a wiring layer is dry-etched by using mixed gas of fluorine, and the pad 2 is exposed. An exposed part 7 is formed in shape smaller than that of the pad of the layer 2, thereby obtaining a moisture resistant reliability of a semiconductor device using it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device having a via hole made of a polyimide resin film for protecting the surface of a semiconductor element or the like.

[0002]

2. Description of the Related Art Conventionally, a polyimide resin has been used as a surface protective film or an interlayer insulating film for various electronic parts such as semiconductors. This polyimide resin is PSG, Si
Compared to inorganic insulating films such as O ₂ and SiN, it is possible to form a flat film on a substrate having large irregularities, a thick film of 1 μm or more can be easily formed, and heat resistance is higher than that of other organic materials. Bipolar I because it has advantages such as high price
It has been adopted for the interlayer insulating film of C
Widely used as a line shield film and buffer coat film.

The polyimide resin film is formed by applying a polyamic acid solution on a wafer, which is a semiconductor substrate, by a spin method or the like, and heat-treating it. In addition, it is necessary to form a pattern such as a via hole in the polyimide resin film,
This pattern is formed by a wet etching process using a photoresist. As a method of forming the pattern, (1) a negative resist pattern is formed as a mask material on a polyimide resin film which is heat-treated at 220 to 350 ° C., and then the hydrazine-based solution is used to etch and pattern the polyimide resin film. Method, (2) 1
A method in which a positive resist is formed as a mask material on a polyimide resin film that has been heat-treated at 10 to 160 ° C., and after exposure, patterning is performed by simultaneously developing the positive resist using an alkaline aqueous solution and etching the polyimide resin film. It has been known.

In recent years, in the semiconductor industry, regulations on the use of organic solvents have been tightened and semiconductor production process time has been shortened. In the method (1), a large amount of hydrazine-based solution and phenol-based resist stripping solution are used. However, since the etching process with hydrazine-based solution is batch type and the process is interrupted and the etching time is long, it is difficult to shorten the production process time. Without using,
Further, the method (2) is predominantly used, in which the etching time of the polyimide resin film is shorter than the method (1).

However, in the case of the method (2),
When developing and etching using an alkaline aqueous solution, there is a problem that the Al bonding pad (electrode) portion exposed on the surface of the semiconductor substrate is dissolved or discolored by the alkaline aqueous solution. This problem becomes more serious as the thickness of the polyimide resin film at the time of forming the via hole becomes thicker and as the etching time becomes longer.

In order to solve the above problems, an inorganic insulating film (passivation film such as P-SiN) is formed to form A.
l A polyimide resin film is formed on a semiconductor substrate in which the bonding pad is not exposed, an alkaline aqueous solution that is an etching solution is prevented from coming into contact with the Al bonding pad portion when forming a via hole of the resin film, and after forming the via hole A method is employed in which the via hole is dry-etched to expose the surface of the Al bonding pad using the polyimide resin film as a mask material. However, in such a method, when the film thickness of the polyimide-based resin film is increased, the pattern accuracy of the via hole is deteriorated,
Since the resolution is also lowered, there is a problem that it becomes difficult to expose the surface of the Al bonding pad portion.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and, even when a via hole is formed using a thick polyimide resin film, the dimensional accuracy of the via hole of the polyimide resin film is high. It is intended to provide a method of manufacturing a semiconductor device, which is excellent in exposure and can expose the surface of the Al bonding pad portion with high accuracy.

[0008]

According to the present invention, a polyamic acid solution obtained by reacting an organic tetrabasic acid dianhydride and a diamine in an organic solvent is applied onto a substrate on which an inorganic insulating film is formed. In the method of manufacturing a semiconductor device by forming a via hole of a polyimide resin film after heat treatment and dry-etching the inorganic insulating film on the substrate using the polyimide resin film as a mask material, When forming a via hole, after forming a via hole of the first layer polyimide resin film, further via hole of the second layer polyimide resin film thicker than the first layer polyimide resin film on the via hole In the method for manufacturing a semiconductor device and the method for manufacturing the same, the film thickness of the polyimide resin film of the first layer is within a range of 3 μm or less, and The geometry of the via hole of bromide-based resin film, a method of manufacturing a semiconductor device which larger than the geometry of the via hole of the polyimide resin film of the first layer.

The polyamic acid solution used in the present invention is
For example, a diamine such as 4,4′-diaminodiphenyl ether is dissolved in an organic solvent such as N-methyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, and then 3,3 ′. It can be obtained by adding an organic tetrabasic dianhydride such as 4,4'-benzophenonetetracarboxylic dianhydride and stirring and reacting at a temperature of 50 ° C or lower, more preferably around room temperature or lower. Examples of commercially available polyamic acid solutions include PI
Q, PIX (trade name of Hitachi Chemical Co., Ltd.) and the like.

A photosensitive polyamic acid solution can also be used. There is no particular limitation on the photosensitive polyamic acid, for example, a photosensitive polyamic acid having a photosensitive group introduced by an ester bond to which a sensitizer, a photopolymerization initiator or the like is added, and a polyamic acid having a carbon-carbon double bond. A photopolymerization initiator, a sensitizer, bisazide, etc. added to the amine compound, and a reaction product obtained by reacting polyamic acid with isocyanate ethyl methacrylate such as 1,6-hexanediol diacrylate. Those containing an unsaturated compound, a photopolymerization initiator, a sensitizer and the like are preferably used. These commercially available products include PL-5035, P
L-2135 (trade name, manufactured by Hitachi Chemical Co., Ltd.) and the like can be mentioned.

The polyimide-based resin film is prepared by stirring the above polyamic acid solution at a temperature of 50 to 80 ° C. to adjust the viscosity to a value suitable for use, and then spin-coating the semiconductor substrate, for example.
It can be obtained by heat-treating at a temperature in the range of 100 to 400 ° C. for 3 hours or less with a hot plate, a hot air dryer or the like, and dehydration ring closure. In the present invention, the pattern of the polyimide resin film, the via hole of the polyimide resin film of the first layer is formed, and the polyimide resin of the second layer having a thickness larger than that of the polyimide resin film of the first layer is formed on the via hole. The resin film is formed, and the via hole is formed again. The well-known method using a positive resist as shown below can be adopted for forming the via hole of these polyimide resin films.

First, a positive resist solution is applied onto the polyimide resin film by, for example, spin and heat treated on a hot plate at 110 ° C. for 120 seconds or less to form a positive resist. The positive resist is not particularly limited, and for example, a mixture of novolac resin and naphthoquinonediazide is used, and commercially available products are OFPR-5000 (trade name of Tokyo Ohka Kogyo Co., Ltd.) and RI-7912P (trade name of Hitachi Chemical Co., Ltd.). Etc.

Next, a photomask is placed on the positive resist and exposed to light, and then the exposed portion of the positive resist is developed and the exposed portion is dealt with by a paddle method or the like using an alkali developing solution by a known photo-etching technique. The polyimide resin film is continuously etched to form a via hole. As the alkali developer, 2.38% tetramethylammonium hydroxide aqueous solution (NMD-3: manufactured by Tokyo Ohka Kogyo Co., Ltd.) is used. The positive resist after forming the via hole of the polyimide resin film is removed by a known method using a stripping solution or the like.

In the present invention, the size of the via hole in the polyimide resin film of the first layer is smaller than the area of the Al bonding pad so that the entire surface of the pad is not exposed after dry etching, and the size of the via hole in the substrate. It is preferable that the variation in accuracy is small. If the via hole has a larger dimension than the area of the Al bonding pad, the entire surface of the Al bonding pad is exposed after dry etching, and the frequency of occurrence of defects increases in the subsequent moisture resistance reliability test. The second layer of polyimide resin film is formed on the first layer of polyimide resin film to be thicker than the first layer of polyimide resin film, and the via hole is formed in the same manner as the first layer. Is formed. The thickness of the polyimide resin film of the first layer is preferably in the range of 3 μm or less from the viewpoint of improving the precision of via hole dimensions and fine processing, and the shape dimension of the via hole of the second layer is The size is preferably larger than the shape size of the via hole of the polyimide resin film of the layer. It is preferable that the second layer polyimide resin film has a thickness of 3 to 30 μm from the viewpoints of etching properties and stress relaxation properties at the time of manufacturing a semiconductor device.

As described above, the shape of the via hole made of the first layer polyimide resin film having a small thickness is formed before the shape of the via hole made of the second layer polyimide resin film having a large film thickness, whereby the Al bonding pad is formed. The dimensional accuracy of the pattern formed on the upper part is improved and the dimensional variation is reduced. After the via holes are formed by the first-layer and second-layer polyimide resin films, the inorganic insulating film in the via holes is removed by dry etching, and A on the substrate is removed.
l The surface of the bonding pad is exposed. Oxygen (O ₂ ), carbon tetrafluoride (CF ₄ ), argon (Ar) and the like are used as the reactive gas for dry etching, but other gases may be mixed and used without any problem.

FIG. 1 is an explanatory view showing an embodiment of a method for manufacturing a semiconductor device of the present invention. In FIG. 1, a wiring layer made of Al (aluminum) and an electrode (bonding pad) 2 formed in a predetermined shape on a semiconductor substrate 1 are
It is covered with an inorganic insulating layer 3 which is a so-called passivation film made of a silicon oxide film. On this semiconductor substrate,
The polyamic acid solution is spin-coated, the solvent is removed by heat treatment, and a part of the solution is dehydrated and ring-closed to form the first layer polyimide resin film 4. A phenol novolac-based positive resist is formed on the first-layer polyimide-based resin film 4, exposed through a photomask, and then developed with an alkaline aqueous solution by a known photoetching technique and the first-layer polyimide is developed. The system resin film 4 is etched to form a via hole 5 above the Al bonding pad. Then, the positive resist is stripped and removed using an organic solvent by a paddle method, a spray method, etc., and then heat-treated at a temperature in the range of 200 to 400 ° C. for 3 hours or less to completely dehydrate and ring-close the patterned first layer. A polyimide resin film 4 is obtained (a).

A polyamic acid solution is further spin-coated on the first-layer polyimide resin film 4 in which the via holes are formed so as to be thicker than the first-layer polyimide resin film 4, and a solvent is applied by heat treatment. It is removed and a part of it is dehydrated and ring-closed to form the second layer polyimide resin film 6. Then, a via hole is formed on the Al bonding pad in the same manner as described above to form a via hole 5, and then the positive resist is peeled and removed, followed by heat treatment at a temperature in the range of 200 to 400 ° C. for 3 hours or less to completely remove the positive resist. A second-layer polyimide resin film 6 having a via hole formed by dehydration ring closure is obtained (b). As shown in FIG. 1B, the via hole of the polyimide resin film of the second layer is formed larger than the via hole of the first layer by adjusting the development time with an alkaline aqueous solution and the etching time. . Next, the obtained polyimide resin films 4 and 6 of the first layer and the second layer
Using the as a mask material, the inorganic insulating layer 3 on the Al bonding pad 2 which is a wiring layer is dry-etched using a fluorine-based mixed gas to expose the Al bonding pad 2 (c). The exposed portion 7 has a shape below the Al bonding pad portion of the wiring layer 2 as shown in the top view, and the moisture resistance reliability of the semiconductor device using this is secured.

[0018]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited thereto. Example 1 54.05 g of 4,4'-diaminodiphenyl ether
(0.27 mol) and 1,3-bis (aminopropyl) tetramethyldisiloxane 7.45 g (0.03 mol) were well dissolved in 800 g of N-methyl-2-pyrrolidone with stirring to give 3,3 ', The reaction was carried out while gradually adding 4,4'-benzophenone tetracarboxylic acid dianhydride 48.33 g (0.15 mol) and pyromellitic dianhydride 32.71 g (0.15 mol), and a viscosity of 13 poise (2
A polyamic acid solution having a resin content of 4.6% by weight was obtained.

As shown in FIG. 1 (a), this polyamic acid solution is applied onto a semiconductor substrate 1 on which an Al wiring layer, an electrode 2 and an inorganic insulating film (P-Si ₃ N ₄ ) layer 3 are formed.
After spin coating at 3000 rpm for 30 seconds, heat treatment (prebaking) was performed at 100 ° C. for 60 seconds and further at 130 ° C. for 60 seconds on a hot plate to form a surface protective film made of a polyimide resin film layer 4 having a thickness of 2.8 μm. A phenol novolac resin-based photosensitive resin (positive photoresist, OFPR-5000:
After spin-coating a film (trade name of Tokyo Ohka Kogyo Co., Ltd.) to form a film, only the bonding pad portion and the scribe line, which are predetermined portions of the resin layer 4, are selectively removed. After exposure by a known photo-etching technique through a 70 μm photomask, tetramethylammonium hydroxide aqueous solution developer NMD-3 (concentration 2.38% by weight, product name of Tokyo Ohka Kogyo Co., Ltd.) is etched. 80 at 23 ° C for liquid
The via hole 5 was formed by simultaneously developing the positive resist layer and etching the polyimide resin film layer 4 by the paddle method for a second.

Next, acetic acid for etching only the positive resist layer
After treating with n-butyl by spraying at room temperature for 60 seconds to remove the positive resist, the positive resist was put into a hot air drier, and 2
Heat treatment was performed at 00 ° C. for 30 minutes and then at 300 ° C. for 30 minutes to obtain a first-layer polyimide resin film 4 having a via hole with a thickness of 2 μm. The shape of the via hole was good, the dimensional accuracy was excellent, and there was no variation. Next in FIG.
As shown in (b), the above polyamic acid composition was prepared on the first layer polyimide resin film 4 to have a viscosity of 140 poise and a resin concentration of 18.6% by weight, and spin-coated at 1700 rpm for 20 seconds, and then hot. 9 at 100 ° C using plate
Heat treatment for 0 seconds, then at 125 ℃ for 90 seconds, 35μm
A thick second layer polyimide resin film 6 was formed. Next, a positive resist is formed on the second layer polyimide resin layer film 6 in the same manner as in the above (a), and after exposure, the positive resist is developed by paddle method at 23 ° C. for 260 seconds using NMD-3. The polyimide resin film 6 was simultaneously etched to form a via hole having a larger dimension than that of the via hole of the first polyimide resin layer 4.

The positive resist on the second layer polyimide resin film 6 was peeled off in the same manner as in (a) above, and then the hot air dryer was used for 30 minutes at 200 ° C. and then at 350 ° C. for 6 minutes.
Heat treatment was performed for 0 minutes to form a via hole having a depth (thickness of the second layer polyimide resin layer film) of 20 μm by the second layer. Next, using a dry etching device (CSE-1110 manufactured by ULVAC, Inc.) with the polyimide resin films 4 and 6 as a mask material, a mixed gas having a ratio of oxygen and carbon tetrafluoride of 10/100 SCCM is used and the pressure is 2.5 kg / cm. ^2. Dry etching was performed for 90 seconds by anisotropic etching with an RF power of 450 W, and as shown in FIG.
l The surface of the bonding pad was exposed. The shape of the exposed portion 7 was smaller than the dimension of the Al bonding pad 2 and had good dimensional accuracy, as shown in the top view at the bottom of FIG. The film thickness of the surface protection film composed of the first layer and the second layer polyimide resin film was reduced by 0.7 μm in the second layer polyimide resin film 6 by dry etching,
It was 1.3 μm.

Example 2 In Example 1, a photosensitive polyamic acid composition (PL-5035, viscosity 2 poise, resin content concentration 19.7% by weight, manufactured by Hitachi Chemical Co., Ltd.) was used for the first layer polyimide resin film 4. Was spin-coated at 3300 rpm for 30 seconds and then heat-treated (bribake) at 90 ° C. for 70 seconds using a hot plate to form a polyimide resin film having a thickness of 4.7 μm. Then, after exposing by a known photo-etching technique, N
-Developer PL containing methyl-2-pyrrolidone as a main component-
DEVELOPER-2N (trade name, manufactured by Hitachi Chemical Co., Ltd.)
The polyimide resin film is developed by a static paddle method at 24 ° C. for 60 seconds using a via hole 5 with high dimensional accuracy.
At 30 ° C. at 140 ° C. using a dryer in a nitrogen atmosphere.
Minutes, then 200 ° C for 30 minutes, then 330 ° C for 6 minutes
The thickness of the polyimide resin film obtained by heat treatment for 0 minutes is 2
The second layer polyimide resin film 6 was formed in the same manner as in Example 1 except that the thickness was μm. This surface protective film was able to expose the favorable Al wiring layer and the electrode 2 by the dry etching treatment.

Comparative Example 1 In Example 1, except that a polyimide resin film having a film thickness of 35 μm after bribking was formed as a surface protective film.
Patterning of the polyimide resin film and dry etching of the inorganic insulating film were performed in the same manner as in Example 1. An explanatory view of the method for manufacturing the semiconductor device at this time is shown in FIG. The formation and patterning of the polyimide resin film 10 in FIG. 2A is performed under the same conditions as the formation and patterning of the second layer polyimide resin film of FIG.
Dry etching of the inorganic insulating layer 3 at the bottoms of the via holes 5A and 5B in (a) was also performed in the same manner as in Example 1. The thickness of the polyimide-based resin film 10 after dry etching was 19.3 μm, but the via holes 5A and 5B had a shape close to a round shape, and the dimensional variation within the semiconductor substrate surface was observed. The upper exposed portions 7A and 7B (occurrence of over-etching) also have a round shape as shown in the top view below, and the exposed portion 7B has a larger size of the inorganic insulating film 3 than the Al bonding pad. 2 The entire surface was completely exposed.

[0024]

According to the manufacturing method of the present invention, even when a pattern is formed using a thick polyimide resin film, the pattern shape dimension of the polyimide resin film is excellent, so that the surface of the Al bonding pad portion can be accurately measured. It is possible to obtain a semiconductor device which can be well exposed and is excellent in moisture resistance reliability and the like, and in which few defects occur.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is an explanatory diagram showing a conventional method for manufacturing a semiconductor device.

[Explanation of symbols]

1 ... Semiconductor substrate, 2 ... Al wiring layer and electrode, 3 ... Inorganic insulating film layer, 4 ... First layer polyimide resin film (protective film),
5, 5A, 5B ... Via holes, 6 ... Second layer polyimide resin film (protective film), 7, 7A, 7B ... Exposed part, 10 ... Polyimide resin film.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/28 301 L 8826-4M 21/312 B 7352-4M

Claims (2)

[Claims] 1. A polyamic acid solution obtained by reacting an organic tetrabasic acid dianhydride and a diamine in an organic solvent is applied on a substrate on which an inorganic insulating film is formed, and after heat treatment,
In the method of forming a via hole of a polyimide resin film and manufacturing a semiconductor device by dry-etching the inorganic insulating film on the substrate using the polyimide resin film as a mask material, when forming the via hole of the polyimide resin film In addition, after forming a via hole of the first layer polyimide resin film, further forming a via hole of the second layer polyimide resin film thicker than the first layer polyimide resin film on the via hole. A method for manufacturing a characteristic semiconductor device. 2. The thickness of the polyimide resin film of the first layer is 3
2. The method of manufacturing a semiconductor device according to claim 1, wherein the via hole of the polyimide resin film of the second layer is larger than the via hole of the polyimide resin film of the first layer. .