JPH06291097A - Fine working method of polyimide resin film - Google Patents

Abstract

PURPOSE:To form a forward taper on a contact hole section, and prevent the disconnection of an upper layer wiring, by a method wherein the dry etching of an layer insulating film is performed by using mixed gas of flon based gas and oxygen, and over etching is performed by using only oxygen gas when etching is ended. CONSTITUTION:Polycrystalline silicon is deposited on a glass substrate 101, and a lower layer wiring 102 is obtained by patterning the silicon to be in a specific form. Polyimide resin as an layer insulating film 103 is spread and baked. Photoresist 104 is formed and used as the etching mask of an layer insulating film 103, which is etched by using CHF3 gas and O2 gas. By observing the intensity change of SiF4 plasma light emission, the etching end point of the layer insulating film 103 is detected. When the lower layer wiring 102 under a part to be etched of the layer insulating film 103 is exposed, the intensity of SiF4 plasma light emission increases. From this time point, the supply of CHF3 gas is stopped, and over etching is performed by using only O2 gas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for finely processing a polyimide resin film used for multilayer wiring of liquid crystal display devices and semiconductor devices.

[0002]

2. Description of the Related Art As a method for finely processing a polyimide resin film, a method using a hydrazine-based etchant after the polyimide resin film is completely cured, a method in which wet etching is performed at the same time as the upper layer photoresist development at the time of semi-curing, and a dry etching after the complete curing There are four types, that is, the one to be performed, and the one to perform patterning like an ordinary photoresist by making a polyimide resin photosensitive. But 2-3 μm
In order to obtain the following pattern dimensions, dry etching is desirable in terms of accuracy. In the case of dry etching, the main gas used is oxygen, but in this case, it is advantageous for the etching mask on the polyimide resin to have resistance to oxygen plasma in terms of patterning.
As described on page 46 of the monthly issue, a metal thin film such as a Mo thin film may be used as an etching mask of polyimide resin.

[0003]

When the aspect ratio of the contact hole opened in the polyimide resin is large, it is more difficult for the upper layer wiring to be broken if the contact hole has a forward tapered cross section. However, when dry etching is used and a non-receding mask such as a metal thin film is used, the cross-sectional shape is vertical or overhanging. Therefore, the upper layer wiring is likely to be broken.

Therefore, it is desirable to give the contact shape a forward taper while performing dry etching.
For that purpose, a material that recedes during etching such as photoresist must be selected as an etching mask. By the way, for detecting the etching end point of an organic thin film such as a polyimide resin, usually, the intensity change of CO plasma emission is used.
This detection method is difficult to use when an organic thin film is also used as an etching mask like a photoresist.

[0005]

[Means for Solving the Problems]

(Means 1) In the present invention, in the fine processing of an interlayer insulating film using an organic resin such as a polyimide resin, after curing the interlayer insulating film, dry etching of the interlayer insulating film is performed by a mixed gas of a chlorofluorocarbon-based gas and oxygen. The plasma is used to perform the etching, and when it is determined that the etching of the interlayer insulating film is completed, the supply of the fluorocarbon gas is stopped and the overetching is performed using only the oxygen gas.

(Means 2) According to the present invention, the underlying film of the etched portion of the interlayer insulating film is a silicon-containing layer such as silicon or silicon oxide, and the interlayer insulating film is finely processed using an organic resin such as a polyimide resin. After the interlayer insulating film is cured, dry etching of the interlayer insulating film is performed by plasma using a mixed gas of CFC-based gas and oxygen, and the etching end point is detected by SiF4 or S.
It is characterized by comprising a step of monitoring by plasma emission of iF.

(Means 3) In the present invention, in the fine processing of an interlayer insulating film using an organic resin containing nitrogen such as a polyimide resin, a step of curing the interlayer insulating film and an orthodiazo as an etching mask of the interlayer insulating film. Using a naphthoquinone-novolak resin-based photoresist, a step of sequentially applying the photoresist, pre-baking, exposing, and developing, and further performing a post-baking after the photoresist is exposed to the whole surface, and the interlayer insulating film with oxygen. It is characterized by comprising a step of performing dry etching using gas.

(Means 4) According to the present invention, in the fine processing of an interlayer insulating film using an organic resin containing nitrogen such as a polyimide resin, a step of curing the interlayer insulating film and an orthodiazo as an etching mask of the interlayer insulating film. Using a naphthoquinone-novolak resin-based photoresist, a step of sequentially performing coating, pre-baking, exposure, and development of the photoresist, a step of further post-baking the interlayer insulating film, and a step of forming the interlayer insulating film. The method is characterized by comprising a step of performing dry etching using oxygen gas, and a step of monitoring the detection of the etching end point of the interlayer insulating film by NO plasma emission.

[0009]

【Example】

Example 1 A lower layer wiring 102 is obtained by depositing 1000 liters of polycrystalline silicon on a glass substrate 101 and patterning it into a predetermined shape. Thereafter, as the interlayer insulating film 103, a polyimide resin such as RN812 manufactured by Nissan Chemical Co., Ltd. is applied so as to have a thickness of about 2 μm, and the resin is baked in a nitrogen atmosphere at 300 ° C. using an oven. Next, a photoresist 104 having a film thickness of about 3 μm is formed,
It is used as an etching mask for the interlayer insulating film 103. For the etching of the interlayer insulating film 103, reactive ion etching (hereinafter referred to as RIE) method was used as dry etching. Etching is 50 mTorr, RF input is 193 mW / cm2, CHF
3 gas flow rate was 1 sccm and O2 gas flow rate was 20 sccm. The etching end point of the interlayer insulating film 103 was detected by observing the intensity change of SiF4 plasma emission during this etching. Although the SiF4 plasma emission intensity increases when the lower wiring 102 under the portion to be etched of the interlayer insulating film 103 is exposed, the supply of CHF3 gas was stopped from this point and overetching was performed only with O2 gas. After the etching is completed, the photoresist 104 is removed with a stripping solution.
Is removed, and the processing step of the interlayer insulating film 103 is completed.

According to the above embodiment, the interlayer insulating film 103 is
Not only the accelerated etching by adding the element can be performed, but also when the lower layer film of the etched portion of the interlayer insulating film 103 is a silicon-containing film such as polycrystalline silicon or silicon oxide, the etching end point can be detected by observing SiF4 plasma emission. It has become possible. Therefore, at the same time when the lower layer wiring is exposed, the supply of the CFC-based gas can be stopped, and the lower layer wiring is CHF3.
Even with a material that is etched with a chlorofluorocarbon-based gas, the progress of etching of the lower layer wiring can be prevented.

At the same time, since the photoresist can be used as an etching mask, it is possible to give the contact hole shape a forward taper.

Further, in this embodiment, S is used to detect the etching end point.
Although an example using iF4 plasma emission is shown, it is also possible to use SiF plasma emission.

(Embodiment 2) 1000 liters of polycrystalline silicon is deposited on a glass substrate 201 and patterned into a predetermined shape to obtain a lower wiring 202. After that, as the interlayer insulating film 203, a polyimide resin such as RN812 manufactured by Nissan Chemical Co., Ltd. is applied to a film thickness of about 2 μm,
The resin is baked in a nitrogen atmosphere at 300 ° C. using an oven. Next, a novolac resin photoresist 204, which uses orthodiazonaphthoquinone as a photosensitive group such as TSMR8700 manufactured by Tokyo Ohka Kogyo Co., Ltd., is applied, prebaked, exposed, and developed in order to a film thickness of about 3 μm.
After that, the photoresist 204 is entirely exposed to 150
Post-baking is performed in an air atmosphere at 1 ° C. for 1 hour to obtain an etching mask. R is used for etching the interlayer insulating film 203.
The IE method was used. Etching was performed at 50 mTorr, RF input of 193 mW / cm @ 2, and O2 gas flow rate of 20 sccm. At the time of this etching, the etching end point of the interlayer insulating film 203 was detected by observing the intensity change of NO plasma emission of wavelength 2560Å. After the etching was completed, the photoresist 204 remaining was peeled off with a peeling solution, and the process of processing the interlayer insulating film 203 was completed.

The exposure of the entire surface of the photoresist in the examples is carried out in order to release N2 from the orthodiazonaphthoquinone, which is a photosensitive group in the photoresist, by irradiation with light. Photoresist 204 that is an etching mask
When the N element is departed from, the NO plasma emission signal due to the N element in the interlayer insulating film clearly appears, and therefore, the end point of the interlayer insulating film 203 can be easily detected. At the same time, since the photoresist can be used as an etching mask, the contact hole shape of the interlayer insulating film 203 can be given a forward taper angle.

[0015]

According to the present invention, it is possible to use a photoresist that recedes during etching as an etching mask for an interlayer insulating film using a polyimide resin. Therefore, the contact hole shape of the interlayer insulating film has a forward taper angle. It has become possible to set up.

In addition, a step of providing a metal thin film serving as an etching mask on the interlayer insulating film, a step of patterning the metal thin film, and a step of peeling off the metal thin film after the etching of the interlayer insulating film have been conventionally required. Since it can be omitted, the process can be simplified and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional view illustrating a process described in a first embodiment.

2A and 2B are cross-sectional views illustrating a process described in Embodiment 2.

FIG. 3 is a cross-sectional view showing a process of a conventional example.

[Explanation of symbols]

 101, 201, 301 Glass substrate 102, 202, 302 Lower layer wiring 103, 203, 303 Interlayer insulating film 104, 204, 304 Photoresist 305 Metal thin film

Claims (4)

[Claims] 1. In the microfabrication of an interlayer insulating film using an organic resin such as a polyimide resin, after the interlayer insulating film is cured, dry etching of the interlayer insulating film is performed by a plasma using a mixed gas of Freon gas and oxygen. And a method of finely processing a polyimide resin film, characterized in that the supply of a CFC-based gas is stopped when it is determined that the etching of the interlayer insulating film is completed, and the over-etching is performed only with oxygen gas. 2. The interlayer insulating film, wherein a lower layer film to be etched is a silicon-containing layer such as silicon or silicon oxide, and the interlayer insulating film is finely processed by using an organic resin such as a polyimide resin. After the film is hardened, the dry etching of the interlayer insulating film is performed by plasma using a mixed gas of Freon gas and oxygen, and the detection of the etching end point is monitored by plasma emission of SiF4 or SiF. , Microfabrication method for polyimide resin film. 3. In the microfabrication of an interlayer insulating film using an organic resin containing nitrogen such as a polyimide resin, a step of curing the interlayer insulating film and an orthodiazonaphthoquinone-novolak resin system as an etching mask of the interlayer insulating film. Using a photoresist, coating the photoresist,
It is characterized by comprising a step of sequentially performing pre-baking, exposure, and development, a step of performing post-baking after further exposing the whole surface of the photoresist, and a step of dry etching the interlayer insulating film using oxygen gas. , Microfabrication method for polyimide resin film. 4. In the microfabrication of an interlayer insulating film using an organic resin containing nitrogen such as a polyimide resin, a step of curing the interlayer insulating film and an orthodiazonaphthoquinone-novolak resin system as an etching mask of the interlayer insulating film. Using a photoresist, coating the photoresist,
Pre-baking, exposure, and development are performed in sequence, further post-baking is performed after exposing the interlayer insulating film to the entire surface, dry etching of the interlayer insulating film using oxygen gas, and the interlayer insulating film The method for microfabrication of a polyimide resin film, comprising the step of monitoring the detection of the etching end point of No. 2 by NO plasma emission.