JP2002289580A - Ashing method, plasma treatment method and mask manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mask manufacturing method which can restrain thickness reduction of a chromium film to a minimum when a substrate on which the chromium film is formed is treated by using plasma. SOLUTION: The mask manufacturing method is provided with a resist film forming process for forming a resist film 102 on the chromium film 101 formed on a quartz substrate 100, a patterning process for patterning the resist film 102, an etching process for etching the chromium film 101 by applying the resist film 102 to a mask, and an ashing process for eliminating the resist film 102. The ashing process is provided with a reaction gas introducing process for introducing reaction gas into a vacuum chamber 11 which accommodates the quartz substrate 100, a plasma generating process for generating plasma in the vacuum chamber 11, a substrate temperature adjusting process for adjusting a temperature of the quartz substrate 100, and an excluding process for excluding ions in plasma P to the chromium film 101.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ashing method, a plasma processing method, and a mask manufacturing method in a process for manufacturing a semiconductor device or a liquid crystal display device, and more particularly to a method capable of suppressing a decrease in the thickness of a chromium film.

[0002]

2. Description of the Related Art A chromium film is used as a light-shielding material of a photomask used in a lithography process of manufacturing a semiconductor device or as a wiring material of a thin film transistor for driving a liquid crystal display. When processing this chromium film into a fine pattern, etching is performed using a photoresist as a mask. After the etching, a so-called ashing process for removing the photoresist using plasma such as oxygen plasma is performed.

FIG. 4 is a view showing a plasma processing apparatus 1 for performing an ashing process using such a plasma. The plasma processing apparatus 1 includes a reaction vessel 2 that houses a quartz substrate 100. A quartz window 3 is fitted into the opening 2a of the reaction vessel 2, and a microwave (2.4
5 GHz) is introduced. Further, a gas inlet 4 for introducing oxygen gas from the outside, an electrode 5 on which the quartz substrate 100 to be processed is placed, and an exhaust mechanism for reducing the pressure inside the reaction vessel 2 are provided. Note that a high frequency bias current (13.56 MHz) is applied to the electrode 5.

[0004]

The ashing method described above has the following problems. That is, when ions in the plasma enter the chromium film, the chromium film may be cut off. When the chromium film is scraped, the film thickness is reduced, so that the light-shielding property is impaired as a photomask, and the resistance is increased as a wiring material of a transistor, so that desired performance cannot be obtained.

Accordingly, the present invention provides an ashing method, a plasma processing method, and a mask, which can minimize a decrease in the thickness of a chromium film when a plasma treatment is performed on a substrate having a chromium film formed on the surface. It is intended to provide a manufacturing method.

[0006]

Means for Solving the Problems In order to solve the above problems and achieve the object, an ashing method, a plasma processing method and a mask manufacturing method of the present invention are configured as follows.

(1) In an ashing method for removing a resist formed on an upper surface of a chromium film on a substrate, in the presence of ozone or active oxygen, the temperature of the substrate is adjusted and ions are applied to the chromium film. It is characterized by removing and removing the resist.

(2) In an ashing method for removing a resist formed on an upper surface of a chromium film on a substrate by using plasma, a reactive gas introducing step of introducing a reactive gas into a container accommodating the substrate; A plasma generation step of generating plasma inside the substrate, a substrate temperature adjustment step of adjusting the temperature of the substrate, and an elimination step of eliminating ions in the plasma with respect to the chromium film. .

(3) In the ashing method described in the above (2), the removing step is a pressurizing step of converging the plasma to a position away from the substrate by increasing a pressure in the container. There is a feature.

(4) In the ashing method described in the above (2), the removing step is a magnetic field applying step of applying a magnetic field to the container to converge the plasma at a position away from the substrate. It is characterized by the following.

(5) In the ashing method described in the above (2), in the elimination step, means for suppressing a flow of ions to the substrate side between the substrate and the plasma is provided. The method is characterized in that it is a step of suppressing ions in the plasma with respect to the film.

(6) In a plasma processing method for processing a substrate surface with an exposed chromium film using plasma, a reactive gas introducing step of introducing a reactive gas into a container accommodating the substrate; The method is characterized by comprising a plasma generating step for generating, a substrate temperature adjusting step for adjusting the temperature of the substrate, and an eliminating step for eliminating ions in the plasma from the chromium film.

(7) In a mask manufacturing method for forming a mask that partially transmits light by selectively forming a chromium film on a substrate, a chromium film forming step of forming a chromium film on the substrate; A resist film forming step of forming a resist film on the chromium film; a patterning step of exposing and developing the resist film to pattern the resist film; an etching step of etching the chromium film using the resist film as a mask; An ashing step of removing a film, wherein the ashing step is a reaction gas introduction step of introducing a reaction gas into a container containing the substrate, a plasma generation step of generating plasma in the container, A substrate temperature adjusting step of adjusting the temperature, and an elimination step of eliminating ions in the plasma with respect to the chromium film. For example, characterized in that is.

(8) In the method of manufacturing a mask according to (7), the removing step includes a step of increasing the pressure in the container to converge the plasma at a position away from the substrate. It is characterized by being.

(9) In the mask manufacturing method according to the above (7), the excluding step includes applying a magnetic field to the container to converge the plasma at a position away from the substrate. It is characterized by being.

(10) In the mask manufacturing method according to the above (7), in the removing step, means for suppressing a flow of ions to the substrate side between the substrate and the plasma is provided. The method is characterized in that the step is a step of suppressing ions in the plasma with respect to the chromium film.

[0017]

FIG. 1 is a longitudinal sectional view showing a plasma processing apparatus 10 used in a mask manufacturing method according to a first embodiment of the present invention, and FIGS. 2A to 2E show a mask manufacturing method. It is explanatory drawing which shows the process in FIG. Plasma processing device 1
0 is used for an ashing process for removing the photoresist R.

The plasma processing apparatus 10 has a vacuum chamber (reaction vessel) 11. A quartz plate 12 is fitted in the opening 11a of the vacuum chamber 11, and a microwave (2.45 GHz) is introduced by a slot antenna (not shown) arranged outside the quartz plate 12. Further, a gas inlet 13 for introducing oxygen gas from the outside.
And a table-shaped electrode 14 on which the quartz substrate 100 to be processed is placed, and a vacuum pump 15 for reducing the pressure in the vacuum chamber 11. A current application unit 16 for applying a high frequency bias current (13.56 MHz) to the electrode 14 and a temperature adjustment unit 17 for adjusting the temperature of the electrode 14 are provided. Also, in FIG. 1, reference numeral 18 denotes a mesh in which a large number of openings are provided in a plate-like member (for example, a metal plate).

Next, the plasma processing apparatus thus configured
A method for manufacturing a mask using the device 10 will be described. Most
First, as shown in FIG. 2A, 6 inch square quartz
A chromium film 101 is formed on a substrate 100 by sputtering.
A film having a thickness of 100 nm, and a photoresist
Strike (ZEP-7000 manufactured by Zeon Corporation) 102
Prepare a coating of 00 nm. Next, 10kv,
5.0μ coulomb / cm ²Exposure under the conditions of
As shown in (b), the developer is sprayed and developed. Next
In addition, as shown in FIG.
₂/ O₂= 80/20 sccm (He, H₂, HCl,
NH₃RIE (etchin) under the condition of 200W.
G) Perform the processing.

Next, an ashing process for removing the photoresist 102 remaining on the chromium film 101 is performed. That is, the quartz substrate 100 is connected to the electrode 14 of the plasma processing apparatus 10.
Place on top. O ₂ gas is introduced into the vacuum chamber 11, evacuated by a vacuum pump 15, and is evacuated by a pressure adjustment valve (not shown) provided in a stage preceding the vacuum pump 15.
Adjust the pressure in 1. Next, plasma P is generated and maintained by supplying microwave power.

The processing conditions are as follows: O ₂ : 1000 sccm, pressure 7
The treatment was performed for 5 minutes under the conditions that the pressure was 0 Pa, the microwave power was constant at 1000 W, the substrate temperature was 25 to 250 ° C., and the high-frequency power applied to the electrode 14 was 0 or 100 W.

By this ashing process, the photoresist 102 is partially removed and patterned as shown in FIG. 2D. At this time, the thickness of the chromium film 101 has hardly decreased. The reason will be described later. Finally, as shown in FIG. 2E, a protective film 103 is formed and a mask is formed.

Next, in the ashing process, the chromium film 10
The reason why the film thickness of No. 1 does not decrease will be described. The amount of scraping was measured by a contact step meter. FIG. 3 is a graph showing the substrate temperature dependence of the etching rate in the O ₂ plasma treatment of the chrome film 101 and the photoresist 102 when the high-frequency power applied to the electrode 14 is set to 0. The ashing speed of the photoresist 102 increases as the substrate temperature increases. On the other hand, the chromium film 101
Is hardly etched at 150 ° C. or lower.
The reason is derived from the relationship between the melting point and the boiling point of chromium oxide.

[0024]

[Table 1]

Table 1 shows melting points and boiling points of main chromium oxides. CrO ₃ is highly volatile and has a viscosity of about 150 as shown in FIG.
It is considered that the etching phenomenon of the chromium film 101 by the O ₂ plasma at a temperature of ° C. depends on the volatility of CrO ₃ .

On the other hand, when the mesh 18 is removed,
When the temperature of the quartz substrate 100 is room temperature, and the high-frequency power applied to the electrode 14 is 0 W, the frequency is 1.1 nm / min.
In the case of 00W, the chromium film 101 was etched at 7.3 nm / min. From this, it is considered that when the quartz substrate 100 on which the chromium film 101 exists is exposed to O ₂ plasma, the volatilization of CrO ₃ is promoted by the ion assist effect, and the chromium film 101 is etched. Therefore, the effect of the mesh 18 reduces the ion assist effect.

As described above, in the mask manufacturing method according to the first embodiment, when the ashing process is performed on the quartz substrate 100 on which the chromium film 101 is formed by using the plasma By reducing the amount of oxygen ions incident on the side, the ion assist effect can be reduced and the temperature of the quartz
By cooling to 0 ° C. or less, the chromium film 101 can be prevented from evaporating. For this reason, damage to the chromium film 101 is reduced, and a decrease in film thickness can be prevented. Therefore, it is possible to maintain the light-shielding property of the photomask and avoid an increase in the wiring resistance of the thin film transistor.

Note that, in the above-described embodiment, O
₍₂ ) It is essential to suppress the volatilization of the most volatile CrO ₃ among chromium oxides generated by the reaction between oxygen radicals (active oxygen) in the plasma and chromium. Therefore, not only O ₂ single gas plasma but also ozone,
The same effect can be obtained by a plasma treatment in which a rare gas or a gas containing no halogen such as N ₂ , CO, or CO ₂ is added to the O ₂ gas.

FIG. 4 is a view showing a plasma processing apparatus 20 used in a mask manufacturing method according to a second embodiment of the present invention. The plasma processing apparatus 20 includes a vacuum chamber (reaction vessel) 21. A plasma generation chamber 23 is connected to the vacuum chamber 21 via a pipe 22. For example, a microwave (2.45 GHz) is introduced into the plasma generation chamber 23 from the outside.

The vacuum chamber 21 has a table-like electrode 24 on which the quartz substrate 100 to be processed is placed.
And a vacuum pump 2 for reducing the pressure in the vacuum chamber 21
6 is provided. The current application unit 2 applies a high frequency bias current (13.56 MHz) to the electrode 24.
A temperature adjusting unit 28 for adjusting the temperatures of the electrode 7 and the electrode 24 is provided.

In the plasma processing apparatus 20 according to the second embodiment, the formation, exposure and development of the chromium film 101 and the photoresist 102 are performed in the same manner as in the mask manufacturing method according to the first embodiment. Do.

Next, an ashing process for removing the photoresist 102 remaining on the chromium film 101 is performed. That is, the quartz substrate 100 is placed on the electrode 24 of the plasma processing apparatus 20.
Place on top. O ₂ gas is introduced into the plasma generation chamber 23, and microwave power is supplied to generate and maintain the plasma P.

On the other hand, a vacuum pump 2
The gas is exhausted in step 6, and the pressure in the vacuum chamber 21 is adjusted. When ashing is performed under the same processing conditions, the photoresist 1
02 is removed, but the thickness of the chromium film 101 hardly decreases. This is because the plasma generation chamber 23 in which the plasma P is formed and the vacuum chamber 21 in which the ashing process is performed.
This is because the ion assist effect due to the ions in the plasma P can be reduced because they are separated from each other.

As described above, in the mask manufacturing method according to the second embodiment, when performing the ashing process on the quartz substrate 100 on which the chromium film 101 is formed using the plasma processing apparatus 20, the plasma P and the quartz are used. By separating the substrate 100 from the substrate 100, the ion assist effect can be reduced. For this reason, damage to the chromium film 101 is reduced, and a decrease in film thickness can be prevented. Therefore, it is possible to maintain the light-shielding property of the photomask and avoid an increase in the wiring resistance of the thin film transistor.

As a method for separating the plasma P from the quartz substrate 100, the plasma P is condensed on one side (at a position away from the quartz substrate 100) of the vacuum container by applying a high pressure to the inside of the vacuum container. Some of them are pressurized, while others apply a magnetic field to the vacuum vessel to converge the plasma to one side of the vessel (at a position away from the quartz substrate 100).

The present invention is not limited to the above embodiment. That is, in the above-described embodiment,
Although it is used for the ashing process for removing the photoresist, it may be used for removing the residue on the chromium film.
In addition, it goes without saying that various modifications can be made without departing from the spirit of the present invention.

[0037]

According to the present invention, when processing is performed using plasma on a substrate having a chromium film formed on its surface, it is possible to minimize a decrease in the thickness of the chromium film.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a plasma processing apparatus used for a mask manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a process chart showing the mask manufacturing method.

FIG. 3 is a graph showing a relationship between a substrate temperature and an etching rate in an ashing step of the mask manufacturing method.

FIG. 4 is a diagram showing a configuration of a plasma processing apparatus used for a mask manufacturing method according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a plasma processing apparatus used for a conventional ashing process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Plasma processing apparatus 11 ... Vacuum chamber (reaction vessel) 12 ... Quartz plate 13 ... Gas inlet 14 ... Electrode 15 ... Vacuum pump 16 ... Current application part 17 ... Temperature adjustment part 18 ... Mesh 100 ... Quartz substrate 101 ... Chromium film 102: photoresist 103: protective film

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) H05H 1/46 H01L 21/88 B (72) Inventor Goji Motokawa 1 Komukai Toshiba-cho, Saiwai-ku, Kawasaki-shi, Kanagawa Inside the Toshiba Microelectronics Center (72) Inventor Tetsuo Takemoto 1 at Komukai Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Microelectronics Center (72) Inventor Masami Watase Sachi-ku, Kawasaki-shi, Kanagawa No. 1, Muko Toshiba, Toshiba Microelectronics Center Co., Ltd. (72) Inventor Hidehiro Watanabe No. 1, Komukai Toshiba, Koyuki, Kawasaki, Kanagawa Prefecture, Japan Toshiba Micro Electronics Center F-term (reference) 2H095 BB17 BB18 BB31 BB38 BC08 4G075 AA24 AA30 CA47 DA01 EB42 EB44 EC21 FA02 FA03 FB02 FB06 FB11 5F004 BA20 BB14 BD01 CA04 DA26 DA27 DB26 5F033 HH07 QQ07 QQ12 XX00 5F046 MA12

Claims (10)

[Claims] An ashing method for removing a resist formed on an upper surface of a chromium film on a substrate, wherein the temperature of the substrate is adjusted and ions are eliminated from the chromium film in the presence of ozone or active oxygen. An ashing method, comprising: 2. An ashing method for removing a resist formed on an upper surface of a chromium film on a substrate by using plasma, wherein a reaction gas introducing step of introducing a reaction gas into a container containing the substrate; Ashing comprising: a plasma generation step of generating plasma; a substrate temperature adjustment step of adjusting the temperature of the substrate; and an elimination step of eliminating ions in the plasma with respect to the chromium film. Method. 3. The ashing method according to claim 2, wherein the removing step is a pressurizing step of increasing the pressure in the container to converge the plasma at a position away from the substrate. 4. The ashing method according to claim 2, wherein said removing step is a magnetic field applying step of applying a magnetic field to said container to converge said plasma at a position distant from said substrate. 5. The exclusion step is a step of providing a means for suppressing the flow of ions to the substrate side between the substrate and the plasma, and suppressing ions in the plasma with respect to the chromium film. The ashing method according to claim 2, wherein: 6. A plasma processing method for processing a substrate surface with an exposed chromium film using plasma, comprising: a reactive gas introducing step of introducing a reactive gas into a container accommodating the substrate; and generating a plasma in the container. A plasma processing method, comprising: a plasma generating step of causing a plasma to be generated; a substrate temperature adjusting step of adjusting a temperature of the substrate; and an elimination step of eliminating ions in the plasma from the chromium film. 7. A mask manufacturing method for forming a mask that partially transmits light by selectively forming a chromium film on a substrate, comprising: a chromium film forming step of forming a chromium film on the substrate; A resist film forming step of forming a resist film on the chromium film; a patterning step of exposing and developing the resist film to pattern the resist film; an etching step of etching the chromium film using the resist film as a mask; An ashing step of removing a gas; a step of introducing a reaction gas into a container accommodating the substrate; a step of introducing a reaction gas; a plasma generation step of generating plasma in the container; and a temperature of the substrate. Adjusting the temperature of the substrate, and removing the ions in the plasma with respect to the chromium film. Mask manufacturing method characterized by that example. 8. The mask manufacturing method according to claim 7, wherein said removing step is a pressurizing step in which the plasma is converged at a position distant from said substrate by increasing a pressure in said container. . 9. The mask manufacturing method according to claim 7, wherein the removing step is a magnetic field applying step of applying the magnetic field to the container to converge the plasma at a position away from the substrate. . 10. The elimination step is a step of providing a means for suppressing the flow of ions to the substrate side between the substrate and the plasma, and suppressing ions in the plasma with respect to the chromium film. The method for manufacturing a mask according to claim 7, wherein: