JP3360185B2 - Organic material film peeling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing an organic material film such as a photoresist film, a resist film, and a protective film formed on a base substrate. When selectively implanting impurity ions or selectively performing dry etching in a semiconductor device manufacturing process, a micromachining process, or the like, the resist film used as a mask is completely removed after the process is completed. It is necessary to remove it.

However, the surface of the resist film is carbonized by ion irradiation in steps such as ion implantation and dry etching, or a polymer containing phosphorus (P) or boron (B) as a dopant to be implanted is formed and deteriorated. In some cases, it is difficult to remove (peel) this.

[0003]

2. Description of the Related Art Conventionally, as a method of stripping a resist film, a plasma ashing apparatus is used to generate a plasma mainly composed of an oxygen (O ₂ ) gas, and the underlying substrate on which the resist film is formed is removed from the plasma. By ashing and locating downstream enough distance for the ions to disappear,
There is known a downflow ashing method in which damage to an underlying substrate due to bombardment of ions in plasma is reduced and a resist film is peeled off by radicals of oxygen and hydrogen.

There is also known a method of increasing the ashing rate by adding a fluorine-based gas to oxygen (O ₂ ) gas using this ashing apparatus. There has also been proposed a method in which a resist film on a base substrate is treated in a plasma using an RIE apparatus or the like, and ashing is performed while hitting the surface of the altered resist film with ions by ion irradiation.

[0005]

According to the conventional method for removing a resist film, however, no problem occurs when the resist film that has been formed and is not deteriorated is removed.
When the surface is carbonized by ion irradiation in a dry etching step, an ion implantation step, or the like, or is altered by forming a polymer containing phosphorus (P) or boron (B) as a dopant to be implanted, oxygen (O ₂ ) gas is used. Since the ashing rate is low, there is a problem that a residue of the carbonized or altered resist film remains.

According to the ashing method to which a fluorine-based gas is added, the ashing rate is improved, but the surface of the wafer exposed in the opening of the resist film, polysilicon (Si) as a wiring layer, insulating material There is a problem of damaging silicon dioxide (SiO ₂ ) or the like (underlying substrate). In the case of the plasma ashing method using ion irradiation by an RIE apparatus or the like, the ashing rate of the carbonized or altered resist film is improved, but particles of the underlying substrate material are sputtered from the underlying substrate and re-adhered to the resist film. As a result, it was found that an undersubstrate material deposition layer was formed, which was not removed by a later dry etching, and that a residue was formed. It has been found that this problem similarly occurs not only in the resist film but also in the ashing and patterning steps of an organic material film such as a protective film.

FIG. 3 is an explanatory view of a conventional method of peeling an organic material film using ion irradiation, and (A) to (C) show each step. In this figure, 41 is a base substrate,
42 is a resist film, 43 is an opening, 44 is a deteriorated resist layer, 45 is ions in plasma, 46 is a reaction product of the resist, 47 is sputter-etched particles, and 48 is a base substrate material deposition layer.

A conventional ashing method using ion irradiation will be described with reference to FIG.

First step (refer to FIG. 3A). Polysilicon (Si) as a wiring layer and a silicon (Si) as an insulating material are used.
Silicon oxide (SiO _Two) On the underlying substrate 41
Using the formed resist film 42 having the opening 43 as a mask
Implanting impurity ions into the underlying substrate 41
The surface of the film 42 is carbonized, or
A polymer containing phosphorus (P) and boron (B) is formed.
To form an altered layer (hereinafter referred to as “resist altered layer”) 44
I will. In addition to the case of impurity ion implantation,
The resist film 42 can also be formed by plasma processing such as etching.
Is carbonized.

Second Step (See FIG. 3B) After the dry etching or ion implantation is completed, the resist film 42 used in this step is exposed to plasma, and the physical energy of ions 45 in the plasma is utilized. Ashing the resist altered layer 44. By the step of ashing the deteriorated resist layer 44 by this plasma,
Since the surface of the underlying substrate 41 made of Si or SiO ₂ exposed on the bottom surface of the opening 43 of the resist film 42 is also hit with ions at the same time, sputter etching particles 47 made of the material constituting the underlying substrate 41 are generated. The etching particles 47 are re-adhered to the side walls of the opening 43 of the resist film 42 after the removal of the deteriorated resist layer 44, thereby forming a base substrate material deposition layer 48.

Third step (see FIG. 3C) Thereafter, ashing of the resist film 42 with oxygen radicals or the like is continued to turn the resist film 42 into a reaction product 46 of the resist such as carbon dioxide and water vapor. Remove.

According to this method, in the ashing for removing the resist film 42, since the etching rate of the base substrate material deposition layer 48 generated in the previous process is small, the ashing of the resist film 42 is performed. 48 remains on the base substrate 41, and a problem arises in that flatness is impaired when an insulating film or the like is further formed thereon.

An object of the present invention is to provide a method for removing an organic material film which can completely remove an organic material film having an opening formed on a substrate.

[0014]

In the method of removing an organic material film according to the present invention, in order to solve the problems], the base substrate to form an organic material film having apertures, plasma treatment in a gas containing an organic compound gas containing carbon hydrocarbons deposited film the open mouth provide Reinforced
A first step in protecting the formed and lower ground substrate, the organic material film in an oxygen-containing gas and facilities the plasma treatment
Adding a second step of removing the hydrocarbon deposition film and
It is characterized by that.

In this case, in the first step, the plasma treatment can be performed in a gas containing an organic compound gas having carbon in a range of 5 to 30% by volume. Hydrocarbons as compound gases,
Alternatively, an organic compound gas including C, H, and O elements having functional groups such as a hydroxyl group and an aldehyde group can be used.

In this case, in the first step, at least one of oxygen and carbon dioxide or at least one of hydrogen, steam and hydrogen peroxide may be added to the organic compound gas having carbon. it can.

In this case, in the second step, plasma can be generated while supplying a gas containing oxygen at a controlled flow rate, and the underlying substrate having the organic material film can be arranged downstream of the plasma. .

In these cases, the organic material film can be used as a resist film.

[0019]

FIG. 1 is a view for explaining the principle of the method of peeling an organic material film according to the present invention, wherein (A) to (C) show respective steps.
In this figure, 1 is a base substrate, 2 is a resist film, 3 is an opening, 4 is a deteriorated resist layer, 5 is ions in plasma,
6 is a hydrocarbon deposition film, and 7 is a resist reaction product.

First Step (See FIG. 1A) A substrate (base substrate) on which polysilicon (Si) as a wiring layer and silicon dioxide (SiO ₂ ) as an insulating film are formed.
When the impurity is ion-implanted into the underlying substrate 1 using the resist film 2 having the opening 3 formed on the substrate 1 as a mask,
Alternatively, when the base substrate 1 is dry-etched,
The surface of the resist film 2 is carbonized, or a polymer containing phosphorus (P) or boron (B), which is an impurity to be implanted, is formed to form the altered layer 4.

Second Step (See FIG. 1B) After ion implantation or dry etching is completed, a resist film 2 having an opening 3 is formed by using a gas plasma containing an organic compound gas having carbon. The first step is performed on the underlying substrate.

During the processing of the first step, the carbon of the organic compound gas having carbon and the organic compound gas having carbon itself or hydrogen such as a reaction gas or a carrier gas react with each other to form a gas in the opening 3. A hydrocarbon deposition film 6 is formed on the surface of polysilicon (Si) or silicon dioxide (SiO ₂ ), and the surface of the wiring layer or the insulating film is protected from ion irradiation by the hydrocarbon deposition film 6. The surface of Si) or silicon dioxide (SiO ₂ ) can be prevented from being physically sputter-etched.

At this time, a gas for chemically etching single crystal silicon (Si), polysilicon (Si), silicon dioxide (SiO ₂ ), etc. of the base substrate 1 such as fluorine and halogen is contained in the processing gas. Since the wiring layer and the insulating film are not etched, the wiring layer and the insulating film are not damaged or have a reduced thickness.

On the other hand, the carbonized or altered layer of the resist film is removed as a resist reaction product 7 such as water vapor or carbon dioxide due to the interaction of the ion bombardment with hydrogen radicals or oxygen radicals generated by dissociation of the processing gas. You.

Third Step (See FIG. 1C) After the carbonization of the resist film and the altered layer are removed, the second step, a plasma treatment using a gas mainly containing oxygen, is performed to form the resist film 2 and The hydrocarbon deposition film 6 is removed.

As the plasma treatment, it is desirable to reduce the ion bombardment on the surface of the base substrate by using a plasma downstream process in which a base substrate having an organic material film is placed downstream of the plasma. According to the method for stripping an organic material film of the present invention, the resist film can be completely stripped without leaving a residue on the base substrate because there is no underlying substrate material deposition layer generated in the conventional technique.

In this step, when hydrogen is added to the organic compound gas having carbon, the altered layer containing phosphorus (P) implanted into the resist during the ion implantation step is converted into a volatile substance to be effectively removed. Can be. Also, when water vapor, hydrogen peroxide, oxygen, and carbon dioxide are added to an organic compound gas having carbon, the resist film becomes carbon monoxide (CO).
And can be effectively removed by converting to carbon dioxide (CO ₂ ).

In the second step of performing plasma treatment on the resist film remaining on the substrate in a gas containing oxygen, the density of the plasma is controlled by supplying a gas containing oxygen at a controlled flow rate. By optimizing ashing, and using a plasma downstream process in which an underlying substrate having a resist film is disposed downstream of plasma to eliminate ions, damage to the underlying substrate due to ion irradiation can be reduced.

As described above, the method for removing an organic material film according to the present invention
Although the case where the resist film is stripped has been described as an example, the present invention is directed to a photoresist film, a resist film, a polyimide film, and the like, or patterning a wide range of organic material films, or
It can be applied when peeling.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
An apparatus that can be used in the method for removing an organic material film of the present invention will be described.

FIG. 2 is an explanatory view of the structure of an apparatus for carrying out the organic material film peeling method of the present invention. In this figure, 11 is a first chamber, 12 is a mass flow controller, 13 is a shower-type counter electrode, 14 is a processing chamber, 15
Is an exhaust port, 16 is a pressure control valve, 17 is a vacuum pump,
18 is a substrate to be processed, 19 is an RF device, 20 is a thermostat, 2
1 is an RF power supply, 22 is a transfer arm, 23 is a transfer chamber, 24
Is a second chamber, 25 is a processing stage, 26 is a heater, 27 is a mass flow controller, 28 is a plasma generation chamber, 29 is a shower head, 30 is a plasma processing chamber, 31 is an exhaust port, 32 is a pressure control valve, and 33 is a vacuum. A pump, 34 is a microwave power supply, 35 is a magnetron, 36 is a waveguide, and 37 is a microwave transmission window.

This apparatus is of a two-chamber type including a first chamber 11 and a second chamber 24, and is configured to perform a two-step process according to the present invention. Then, a gas constituting a processing gas is introduced into the first chamber 11, which is a parallel plate RIE apparatus, at a controlled flow rate through a mass flow controller 12. The processing gas is supplied into the processing chamber 14 through a plurality of openings of the shower-type counter electrode 13 in a lattice shape, a mesh shape, or the like. Is exhausted by the vacuum pump 17 while controlling the pressure.

RF device 19 on which substrate 18 to be processed is placed
Is a water-cooled type, and the temperature of the cooling water is controlled by a thermostat 20. Then, the RF power source 21 is applied to the RF electrode 19.
13.56 MHz RF power is supplied to generate plasma of a processing gas, and the processing target substrate 18 is subjected to the first step processing.

After the processing of the first step is completed, the substrate to be processed 18 passes through the transfer chamber 23 while being decompressed by the transfer arm 22 and flows down the microwave (μ-wave) in the second chamber 24. The wafer is conveyed to the apparatus and placed on a processing stage 25 heated by a heater 26. Then, the flow rate of the gas constituting the processing gas is controlled by the mass flow controller 27,
It is introduced into the chamber 24.

This processing gas is introduced into the plasma generation chamber 28, passes through the shower head 29, and passes through the plasma processing chamber 3.
0, passes through the exhaust port 31 and passes through the pressure control valve 32
The plasma generation chamber 28 and the plasma processing chamber 3
It is evacuated by the vacuum pump 33 while controlling the pressure in 0 to a predetermined pressure.

The processing gas is generated by the microwave power source 34 and the magnetron 35 and is converted into plasma in the plasma generation chamber 28 by the microwaves guided through the waveguide 36 and the quartz transmission window 37 into the plasma generation chamber 28. And used for the processing of the second step.

According to the processing in the second step, since the microwave electric field is cut off by the shower head 29, the electric field is not generated in the plasma processing chamber 30, and ions and electrons pass through the shower head 29 at the stage of passing through the shower head 29. Since they recombine and disappear, there is no ion bombardment on the substrate 18 to be processed, and ashing proceeds by a chemical reaction of electrically neutral particles such as oxygen radicals.

In order to confirm the effect of the method for stripping an organic material film of the present invention, the apparatus described with reference to FIG. 2 was used, methane was used as an organic compound gas having carbon, and hydrogen and steam were added thereto. The results of experiments conducted using a mixed gas of hydrogen / steam / benzene in which benzene was adopted as a mixed gas of / steam / methane and an organic compound gas having carbon, and hydrogen and steam were added thereto.

The sample used in these experiments was SiO ₂
A novolak resin-based positive resist is applied to a thickness of about 1 μm on a 6-inch diameter Si substrate on which 150 ° is formed.
After baking for 90 seconds on a hot plate at 0 ° C., phosphorus (P) was ion-implanted at an ion energy of 70 keV and at a dose of 1 × 10 ¹⁶ / cm ² . By this ion implantation of P, about 25% from the surface is formed on the resist film.
A carbonized and altered layer having a depth of 00 ° was generated.

(First Embodiment) A base substrate on which a resist film is formed is transported to a processing chamber 14 (see FIG. 2, the same applies hereinafter).
Hydrogen, steam, and methane were introduced into the first chamber 11 at a ratio of 400/100/150, respectively, to generate plasma, and the first step of ashing was performed.

At this time, the etching rate of the altered layer of the resist film was 2100 ° / min. After removing the carbonized and altered layer of the resist film by the processing of the first step, the base substrate 18 having the resist film is transferred to the second chamber 24, which is a microwave downflow chamber, and the second step processing is performed. Was.

Although the ashing gas is O ₂ , the ashing rate of the unaltered resist film at this time is 60.
00 ° / min. When the processing time of the first step was 90 seconds and the processing time of the second step was 90 seconds, the resist film carbonized and altered by ion implantation could be completely removed without leaving any residue. At this time, no decrease in the SiO ₂ film thickness of the base substrate 18 was observed.

(Second Embodiment) An undersubstrate 18 on which a resist film is formed is transported to the processing chamber 14 and the first chamber 1
Hydrogen, steam, and benzene were added to each of them at 400/100.
The plasma was generated by introducing at a rate of / 50, and the ashing process in the first step was performed.

At this time, the etching rate of the deteriorated resist layer was 1,800 ° / min. After the carbonization and the altered layer of the resist film are removed by the processing of the first step, the substrate to be processed 18 is transferred into the second chamber 24, which is a microwave downflow chamber, where oxygen (O ₂ ) is processed. The process of the second step of converting to gas was performed. The ashing rate of the unaltered resist film at this time was 6000 ° / min.

When the first step processing time was 90 seconds and the second step processing time was 90 seconds, the ion-implanted resist could be completely removed without leaving any residue. At this time, the SiO ₂
No decrease in film thickness was observed.

In the first and second embodiments, 23% by volume of methane, which is an organic compound having carbon, and 9% by volume of benzene are contained, but 5 to 30% by volume of organic compound gas having carbon is contained. When it was included, the surface of the underlying substrate was covered with a hydrocarbon layer to prevent the underlying substrate material from being sputtered by ion irradiation in plasma, and the resist film could be completely removed. When the amount of the organic compound having carbon is less than 5% by volume, the thickness of the hydrocarbon layer is insufficient to protect the surface of the underlying substrate, and when the amount of the organic compound is more than 30% by volume, the hydrocarbon layer becomes excessive. Deposited on the surface, making it difficult to peel off.

In this case, oxygen, carbon monoxide (CO) and carbon dioxide (C) added to the organic compound having carbon are used.
O ₂ ) has the effect of converting the resist film to carbon monoxide (CO) or carbon dioxide (CO ₂ ) and effectively removing the resist film during ashing, and hydrogen and water vapor form the resist film. There is an effect that the altered layer containing phosphorus (P) can be converted into a volatile substance to be effectively removed.

[0048]

As described above, when the organic film peeling method of the present invention is used, the wiring layer formed on the underlying substrate,
An organic material film such as a carbonized or altered resist film can be effectively removed without damaging an insulating film, an element, and the like, and greatly contributes to a semiconductor device manufacturing technology field, a micromachining technology field, and the like. .

[Brief description of the drawings]

FIG. 1 is a view for explaining the principle of a method for peeling an organic material film of the present invention, wherein (A) to (C) show respective steps.

FIG. 2 is an explanatory view of an apparatus for carrying out the organic material film peeling method of the present invention.

FIG. 3 is an explanatory view of a conventional method of peeling an organic material film using ion irradiation, and (A) to (C) show respective steps.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 base substrate 2 resist film 3 opening 4 resist altered layer 5 ions in plasma 6 hydrocarbon deposition film 7 resist sputtered particles 11 first chamber 12 mass flow controller 13 shower-type counter electrode 14 processing chamber 15 exhaust port 16 pressure control valve 17 vacuum Pump 18 Substrate to be processed 19 RF device 20 Constant temperature bath 21 RF power supply 22 Transfer arm 23 Transfer chamber 24 Second chamber 25 Processing stage 26 Heater 27 Mass flow controller 28 Plasma generation chamber 29 Shower head 30 Plasma processing chamber 31 Exhaust port 32 Pressure control valve Reference Signs List 33 vacuum pump 34 μ power supply 35 magnetron 36 waveguide 37 μ transmission window 41 base substrate 42 resist film 43 opening 44 resist altered layer 45 ions in plasma 46 base substrate sputter etch Grayed particles 47 substrate material deposit 48 underlying substrate material deposition layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 H01L 21/027

Claims (8)

(57) [Claims] To 1. A base substrate to form an organic material film having an opening, by forming a hydrocarbon deposit film the open mouth and facilities plasma treatment in a gas containing an organic compound gas containing carbon
First step and said organic material film and said carbon Kamizu in containing oxygen gas and facilities the plasma treatment to protect the lower ground substrate
A method for removing an organic material film, comprising adding a second step of removing the element deposited film . 2. The method for removing an organic material film according to claim 1, wherein the first step includes 5 to 30% by volume of an organic compound gas having carbon. 3. The method according to claim 1, wherein in the first step, the organic compound gas having carbon is a hydrocarbon or an organic compound gas including C, H, and O elements having functional groups such as a hydroxyl group and an aldehyde group. The method for peeling an organic material film according to claim 1 or 2, wherein 4. The method according to claim 1, wherein in the first step, at least one of oxygen and carbon dioxide is added to the organic compound gas having carbon. Method of removing organic material film. 5. The method for removing an organic material film according to claim 1, wherein hydrogen is added to the organic compound gas having carbon in the first step. . 6. The method according to claim 1, wherein in the first step, at least one of water vapor and hydrogen peroxide is added to the organic compound gas having carbon.
The method for stripping an organic material film according to any one of the above. 7. The method according to claim 2, wherein in the second step, plasma is generated while supplying a gas containing oxygen at a controlled flow rate, and a base substrate having an organic material film is disposed downstream of the plasma. The method for stripping an organic material film according to any one of claims 1 to 6. 8. The method for stripping an organic material film according to claim 1, wherein the organic material film is a resist film.