JP2003324093A - Method for manufacturing semiconductor device and the semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching method in which no deposition is left when etching an inorganic film to which a heat resistant polymer protection film is applied. <P>SOLUTION: In a semiconductor manufacturing method that comprises forming an inorganic film on the surface of a semiconductor element, applying a heat resistant polymer protection film on the inorganic film, patterning the protection film, and then performing the dry-etching of the exposed inorganic film; the dry-etching is performed by mixed gas consisting of fluorinated methane and oxygen or hydrogen. The fouorinated methane is selected from tetrafluoromethane, trifluoromethane, difluoromethane, and fluoromethane. <P>COPYRIGHT: (C)2004,JPO

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 coated with a heat-resistant polymer protective film, and more particularly to a method for etching an inorganic film via the heat-resistant polymer protective film coated on a semiconductor element. It is about.

[0002]

2. Description of the Related Art Conventionally, a polyimide resin having excellent heat resistance and excellent electrical and mechanical properties has been used for a surface protective film and an interlayer insulating film of a semiconductor device. There is a demand for significantly improved heat resistance cycle resistance, heat shock resistance, etc. due to the trend toward larger size, larger size, thinner package, smaller size, and surface mounting by solder reflow. Has become. On the other hand, a technique of imparting photosensitivity to the polyimide resin itself has recently attracted attention, and if this is used, a part of the pattern forming process can be simplified and there is an effect of shortening the process and improving the yield, but at the time of development. Since a solvent such as N-methyl-2-pyrrolidone is required, there is a problem in safety and handleability.

Therefore, recently, a positive type photosensitive resin which can be developed with an alkaline aqueous solution has been developed. For example, Japanese Patent Publication No. 1-46862 discloses a positive photosensitive resin composed of a polybenzoxazole precursor and a diazoquinone compound. It has high heat resistance, excellent electrical characteristics, and fine workability, and has potential as a resin for not only wafer coating but also interlayer insulation.

Such a photosensitive resin has been widely used in recent years as a surface protective film or an interlayer insulating film of a semiconductor device, and is composed of a polybenzoxazole precursor and a diazoquinone compound having a particularly high resolution. In the case of a positive type photosensitive resin, a method of dry etching through the positive type photosensitive resin is applicable when processing the inorganic film formed on the wiring. However, when the inorganic film is processed, when the layer structure is complicated, there is a phenomenon that a deposit, which is a reaction product with the gas used at the time of etching, remains, which causes a problem such as poor appearance. This deposit is generally called deposition and is difficult to remove. Therefore, a removing process such as chemical treatment is required.

[0005]

The present invention relates to a method for manufacturing a semiconductor device coated with a heat-resistant polymer protective film, and particularly to a deposition method for etching an inorganic film coated with the heat-resistant polymer protective film. It is an object of the present invention to provide a method for manufacturing a semiconductor device, which is characterized in that dry etching treatment is performed without leaving any residue.

[0006]

According to the present invention, a semiconductor element is provided with an inorganic film, a heat-resistant polymer protective film is applied on the inorganic film, and the heat-resistant polymer protective film is patterned. In the method of dry etching the post-exposed inorganic film, a semiconductor device is manufactured by dry etching with a mixed gas of fluorinated methane and oxygen or hydrogen. In a further preferred embodiment, the fluorinated methane is selected from tetrafluoromethane, trifluoromethane, difluoromethane and fluoromethane, the mixed gas is composed of fluorinated methane and oxygen, and the oxygen is 4 to 25 relative to the fluorinated methane. % By volume, or the mixed gas is composed of fluorinated methane and hydrogen, hydrogen is 10 to 30% by volume with respect to the fluorinated methane, and the heat resistant polymer protective film is a polybenzoxazole film or a polyimide film, The heat-resistant polymer protective film is a heat-treated protective film, and the pressure in the system during the dry etching treatment is 0.
It is a method of manufacturing a semiconductor device having a pressure of 5 to 5 Pa. Also,
A semiconductor device manufactured by using the above-described semiconductor device manufacturing method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A method of manufacturing a semiconductor device according to the present invention is a dry etching method in which an etching atmosphere is kept at a constant process pressure and a gas is made into plasma for etching an inorganic film having a heat-resistant polymer protective film. This is a method of processing. As a heat resistant polymer protective film,
Polybenzoxazole, polyimide, benzocyclobutene, etc. are used. Above all, the present invention is suitable for polybenzoxazole and polyimide. For example, polybenzoxazole is represented by the following formula.

[0008]

[Chemical 1]

As the inorganic film, Si, SiO ₂ , Si
Substrates made of ₃ N ₄ , Ta, Ti, Ta ₂ O ₅ , TaN, Al and the like can be mentioned. Dry etching is preferably performed at high output. Although the maximum output specification that can be set differs depending on the device, by performing the process under a higher output condition, processing can be performed without leaving deposition and the etching rate is improved, so that the etching process can be performed in a shorter time.

The gas used during etching is preferably a mixed gas of fluorinated methane and oxygen or hydrogen. Examples of the fluorinated methane include tetrafluoromethane, trifluoromethane, difluoromethane and fluoromethane, and among these, particularly preferable ones are tetrafluoromethane, trifluoromethane and difluoromethane. These fluorinated methanes may be used alone or as a mixture.

Further, in the case of a mixed gas composed of fluorinated methane and oxygen, the proportion of oxygen is 4 to fluorinated methane.
-25% by volume is preferred. In the case of a mixed gas composed of fluorinated methane and hydrogen, the proportion of hydrogen is preferably 10 to 30% by volume with respect to fluorinated methane. The ratio of oxygen to fluorinated methane is less than 4% by volume or the ratio of hydrogen is 1
When the content is less than 0% by volume, the deposition generated during etching is not removed, and when the ratio of oxygen to fluorinated methane exceeds 25% by volume or the ratio of hydrogen exceeds 30% by volume, heat-resistant polymer protection Roughness of the surface of the membrane can cause cosmetic problems. Si, SiO ₂ ,
By selecting the optimum dry etching processing conditions for the inorganic film such as Si ₃ N ₄ , Ta, Ti, Ta ₂ O ₅ , TaN, etc., etching processing can be performed without leaving deposition.

The lower the process pressure set during etching, the better. By keeping the pressure in the system low, it is possible to discharge the reaction product, which is a reaction product during etching, without stopping it. The process pressure in the system is 0.5 Pa to 5 Pa, preferably 1 Pa to 4 Pa. If it is less than the lower limit, plasma cannot stand up, and etching cannot be performed. If it is more than the upper limit, the deposition generated during etching may not be removed. Known methods can be used for other methods of manufacturing the semiconductor device.

[0013]

EXAMPLES The present invention will be specifically described below with reference to examples. Example 1 * Preparation of Polybenzoxazole Precursor 132.8 g (0.8 mol) of terephthalic acid, 33.2 g (0.2 mol) of isophthalic acid and 1-hydroxy-1,
360.4 g of dicarboxylic acid derivative obtained by reacting with 270.3 g (2 mol) of 2,3-benzotriazole
(0.9 mol) and hexafluoro-2,2-bis (3-
Amino-4-hydroxyphenyl) propane 366.3
g (1.0 mol) was placed in a 4-neck separable flask equipped with a thermometer, a stirrer, a raw material inlet, and a dry nitrogen gas inlet tube, and 3000 g of N-methyl-2-pyrrolidone was added and dissolved. . After that, use an oil bath at 75 ° C for 1
The reaction was carried out for 2 hours.

Next, 500 g of N-methyl-2-pyrrolidone
32.8 g (0.2 mol) of 5-norbornene-2,3-dicarboxylic acid anhydride dissolved in was added, and the reaction was terminated by further stirring for 12 hours. After filtering the reaction mixture, the mixture was poured into a mixed solution of water / methanol = 3/1, the precipitate was collected by filtration, sufficiently filtered with water, and then dried under vacuum to be represented by the general formula (1). , X is the following formula X-1, and Y is the following formula Y-1.
And a polyamide (A- in which Y-2 and E are the following formula E-1:
1) got.

[0015]

[Chemical 2]

Preparation of Positive Photosensitive Resin Composition 100 g of the synthesized polyamide (A-1) and 25 g of diazoquinone (Q-1) having the structure of the following formula were added to N-methyl-
It was dissolved in 200 g of 2-pyrrolidone and stirred for 3 hours. Thereafter, the stirring was stopped, the mixture was allowed to stand at room temperature, and the appearance was visually observed after 3 hours. No bubbles were observed. Then, it filtered with the 0.2-micrometer fluororesin filter and obtained the photosensitive resin composition.

[0017]

[Chemical 3]

* Preparation of cured film of polybenzoxazole The film was formed on the wafer substrate by the plasma CVD method using the resin precursor varnish for the heat-resistant polymer protective film containing the polybenzoxazole precursor synthesized by the above method. A coating film was obtained by coating the coated 7000Å Si ₃ N ₄ film with a spin coater or the like and then drying it with a hot plate or the like. This coating film was exposed and developed to form a pattern.
Further, this wafer is placed in an oven at 150 ° C. for 30 minutes for 32
The polybenzoxazole resin precursor is ring-closed by heating at 0 ° C. for 30 minutes to form a polybenzoxazole cured film.

* Etching of inorganic film Next, the wafer was etched by using an etching apparatus L-210D-L (manufactured by Anerva Co., Ltd .; maximum output 300 W) to obtain oxygen: tetrafluoromethane = 7.7: 92.3 volume%. Output power of 250 W, process pressure of 1 due to mixed gas
The inorganic film was etched at Pa for 7 minutes. At this time, the decrease in the thickness of the polybenzoxazole cured film was about 0.8 μm.

* Evaluation after Inorganic Film Etching Treatment A square pattern opening of 10 μm × 10 μm was observed using a scanning electron microscope, and as a result of confirming the residual deposition, no deposition was observed.

Example 2 The same evaluation as in Example 1 was conducted except that the polybenzoxazole film in Example 1 was replaced with a polyimide film. The method for forming the polyimide precursor and the cured film will be described below.

* Preparation of Polyimide Precursor In a four-necked separable flask equipped with a thermometer, a stirrer, a raw material charging port and a dry nitrogen gas inlet port, 4,4'-diaminodiphenyl ether (190.2 g, 0.95 mol) was added.
1,3-bis (3-aminopropyl) -1,1,3,3
-12.4 g (0.05 mol) of tetramethyldisiloxane was taken, and anhydrous N-methyl-2-pyrrolidone was added thereto and dissolved in such an amount that the solid content ratio of the total raw materials became 15% by weight. did. Then, the flask was immersed in an aqueous solution at 0 to 50 ° C., and 218.1 g (1 mol) of purified pyromellitic dianhydride was added while suppressing heat generation. After the tetracarboxylic dianhydride was dissolved, the system temperature was raised to 20
The temperature was kept at 0 ° C. and the reaction was continued for 10 hours. The dry nitrogen gas was allowed to flow throughout the entire process from the preparation of the reaction to the removal of the product. The obtained product was a pale yellow viscous solution, and the intrinsic viscosity of a 0.5% by weight N-methyl-2-pyrrolidone solution was 1.10 (30 ° C.).

* Preparation of Polyimide Cured Film A resin precursor varnish for a heat-resistant polymer protective film containing the synthesized polyimide precursor was used to coat an inorganic film formed on a wafer substrate with a spin coater or the like. Then, it dried with a hot plate etc. and obtained the coating film. This coating film was exposed and developed to form a pattern. Further, this wafer is heated in an oven at 150 ° C. for 30 minutes and 320 ° C. for 30 minutes to cause a ring closure reaction of the polyimide resin precursor to form a polyimide cured film. After coating on a silicon wafer with a spin coater, it was dried on a hot plate at 145 ° C. for 1 minute to obtain a coating film having a film thickness of about 14 μm. Positive photoresist OFPR-800 (Tokyo Ohka Kogyo Co., Ltd.)
Applied by a spin coater, dried at 100 ° C. for 1 minute, and passed through a reticle to obtain 200 mJ / c.
Exposure is performed by irradiating m ² of ultraviolet rays, and then 2.38%
The exposed portion was dissolved and removed by immersing it in the tetramethyl hydroxide aqueous solution for 60 seconds, and then rinsed with pure water for 30 seconds to form a pattern. Then, the resist was peeled off by immersing in butyl acetate for 1 minute. This wafer is placed in an oven at 150 ° C for 30 minutes and 230 ° C for 30 minutes.
Min., Heating at 350 ° C. for 30 minutes to perform a polyimide ring closure reaction to obtain a polyimide cured film having a final film thickness of about 8 μm.

Example 3 The same evaluation as in Example 1 was carried out except that the ratio of oxygen: tetrafluoromethane volume% was changed to 20:80. << Example 4 >> In Example 1, the process pressure was set to 3 Pa.
The same evaluation as in Example 1 was carried out except that << Example 5 >> In Example 1, the output was 250 at a volume ratio of hydrogen: tetrafluoromethane = 14.3: 85.7.
The same treatment and evaluation as in Example 1 were performed except that the etching treatment was performed for 11 minutes at W and a process pressure of 3 Pa. Example 6 The same processing and evaluation as in Example 1 except that etching was performed for 11 minutes at an output of 250 W and a process pressure of 3 Pa at a volume ratio of hydrogen: tetrafluoromethane = 25: 75. I went.

<< Comparative Example 1 >> In Example 1, the output is 1
Example 1 except that the etching treatment was performed by setting to 50 W.
The same evaluation as was done. << Comparative Example 2 >> In Example 1, the process pressure was 8 Pa.
The same evaluations as in Example 1 were carried out except that the etching treatment was carried out by setting to 1. << Comparative Example 3 >> The same evaluation as in Example 1 was performed except that the etching treatment was performed in Example 1 at a volume% ratio of oxygen: tetrafluoromethane = 33.3: 66.7. << Comparative Example 4 >> The same evaluation as in Example 1 was performed, except that the etching treatment was performed in Example 5 at a volume ratio of hydrogen: tetrafluoromethane = 7.7: 92.3.

The evaluation results are shown in Table 1.

[Table 1]

[0027]

According to the present invention, an etching treatment can be performed without leaving deposition during etching of an inorganic film coated with a heat-resistant polymer protective film.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H025 AA10 AB16 CB25 DA40 FA41                 2H096 AA25 HA24                 5F004 AA04 AA05 AA14 CA02 CA03                       DA00 DA01 DA15 DA16 DA24                       DA26 DB00 DB01 DB03 DB07                       DB08 DB09 DB12 DB13 EA03

Claims (8)

[Claims] 1. A semiconductor element is provided with an inorganic film, a heat-resistant polymer protective film is applied on the inorganic film, and the heat-resistant polymer protective film is pattern-processed and then exposed. A method of manufacturing a semiconductor device, characterized in that in the method of dry etching, a dry etching process is performed with a mixed gas of fluorinated methane and oxygen or hydrogen. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the fluorinated methane is selected from tetrafluoromethane, trifluoromethane, difluoromethane and fluoromethane. 3. The method for manufacturing a semiconductor device according to claim 1, wherein the mixed gas is composed of fluorinated methane and oxygen, and oxygen is 4 to 25% by volume with respect to the fluorinated methane. 4. The method of manufacturing a semiconductor device according to claim 1, wherein the mixed gas is composed of fluorinated methane and hydrogen, and hydrogen is 10 to 30% by volume with respect to the fluorinated methane. 5. The method for manufacturing a semiconductor device according to claim 1, wherein the heat-resistant polymer protective film is a polybenzoxazole film or a polyimide film. 6. The method for manufacturing a semiconductor device according to claim 1, wherein the heat-resistant polymer protective film is a heat-treated protective film. 7. The method of manufacturing a semiconductor device according to claim 1, wherein the pressure in the system during the dry etching treatment is 0.5 to 5 Pa. 8. A semiconductor device manufactured by using the method for manufacturing a semiconductor device according to claim 1.