JP4041373B2 - Dry etching method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of forming a photoresist pattern on a laminated film including at least a metal film or a metal oxide film, and patterning the laminated film by dry etching using the resist pattern as a mask.
[0002]
The present invention relates to (1) fields related to metal wiring patterns (semiconductor patterns, liquid crystal patterns, display element patterns, etc.), (2) fields related to optical elements (polarizing elements, polarizing plates, etc.), and (3) fields related to reflective optical elements. (Reflective liquid crystal, elements utilizing reflection, etc.) can be used.
[0003]
[Prior art]
Conventionally, when performing dry etching of a multilayer film containing aluminum as a main component, dry etching processing is performed by changing etching conditions in accordance with the structure of the film (see Patent Documents 1 and 2).
[0004]
Specifically, as the etching gas species, “CHF” _Three + BCl _Three "," Fluorine gas (CHF _Three Except) + BCl _Three Or CF _Four + Cl ₂ ”And other fluorine-based and chlorine-based mixed gases, and Cl ₂ Or BCl _Three If the film structure to be etched is a two-layer structure, two steps are required, and if the film structure is to be etched, three steps are required. In this method, dry etching is performed while changing the etching gas composition according to the film configuration.
[0005]
Also, since aluminum easily reacts with chlorine and isotropically proceeds, isotropic etching is performed by forming a protective film on the side wall while performing etching in order to obtain anisotropy. A method of suppressing and maintaining a good finished shape is employed. As a method for forming the sidewall protective film, there are a method using a decomposition product from a photoresist, or a method using a reaction product generated by an etching reaction by adding a deposition gas.
[0006]
[Patent Document 1]
JP 2000-150477 A
[Patent Document 2]
JP 2000-260759 A
[0007]
[Problems to be solved by the invention]
However, if a decomposition product from the resist is attached to the side wall as a side wall protective film in order to suppress isotropic etching, the selectivity with respect to the resist is lowered. That is, the resist selection ratio and shape control are in a trade-off relationship, and it is extremely difficult to perform good shape transfer while maintaining the resist selection ratio. Further, a step of removing the sidewall protective film is required.
[0008]
In addition, when dry etching is performed while changing the etching gas composition in accordance with the remaining film structure as the etching progresses, a history at the time of changing the conditions remains, and a step is generated on the boundary surface of the film. In addition, since it takes time for the plasma to stabilize when the conditions are changed, the perpendicularity temporarily deteriorates at the boundary surface of the film.
[0009]
The present invention enables dry etching under certain conditions in a method of forming a photoresist pattern on a laminated film including a metal film or a metal oxide film, and patterning the laminated film by dry etching using the resist pattern as a mask. The object of the present invention is to eliminate the step on the boundary surface of the film and to form a good shape while maintaining the selectivity to resist by not forming the side wall protective film.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a dry etching method according to the present invention performs etching by a plasma etching method, and uses a mixed gas containing Ar gas as a fluorine gas and a chlorine gas as an etching gas, from the start to the end of etching. It is characterized by being continuously performed under the same etching conditions in the same etching chamber.
[0011]
By generating plasma with “a mixed gas of fluorine-based gas, chlorine-based gas and Ar gas”, it is possible to perform continuous dry etching in the same etching chamber and under the same etching conditions, eliminating the step on the boundary surface of the film. A vertical patterning shape can be formed.
[0012]
That is, by adding Ar gas, radical components can be suppressed, ion density can be increased, and side etching can be prevented to improve the verticality. That is, Ar gas is characterized by being energetically easy to ionize (ionize) in plasma and inert. Therefore, when colliding with other non-ionized molecules, there is an action of promoting ionization. Moreover, since it has a sputtering effect, it also has an effect of preventing the formation of a protective film.
[0013]
In conventional metal film dry etching methods, fluorine-based gas and resist products are used for side wall adhesion for the purpose of shape control to maintain a good shape, so the selectivity to resist decreases, and the selectivity to resist and shape control However, in the present invention, the addition of Ar gas maintains the shape controllability and makes it difficult to form a sidewall protective film, so that the resist selection ratio does not decrease compared to the conventional method. .
[0014]
Since the dry etching method of the present invention continuously etches under the same etching conditions, it is possible to eliminate the step at the boundary surface of the film.
The film adhering to the side wall is a reaction product of fluorine and resist, but in the present invention, the addition of Ar gas lowers the partial pressure of the fluorine-based gas, and the generation of the reaction product with fluorine is suppressed accordingly. In addition, the generation of a film corresponding to a conventional sidewall protective film can be more effectively prevented.
[0015]
In order to further exert the effect of Ar gas addition, the composition of the etching gas is set so that the Ar gas is equal to or greater than the total of the fluorine-based gas and the chlorine-based gas, expressed as a volume ratio under the same pressure. Is preferred.
Such a preferable Ar gas addition rate is that when the total volume of the fluorine-based gas and the chlorine-based gas is 1, the volume ratio of Ar gas is 1-2.
[0016]
The present invention can also be applied when the laminated film includes at least an aluminum film. A mixed gas of fluorine-based gas and chlorine-based gas as an etching gas is convenient for increasing the etching rate of a metal or metal compound thin film, but aluminum chloride is formed on the surface layer of a metal film mainly composed of aluminum by the chlorine-based gas. As a result, “aged corrosion (after-corrosion)” of the aluminum film occurs. “Erosion over time” means that chlorine molecules react with aluminum over a long period of time from the end of the process to the use of the product, and the aluminum film is corroded. In a semiconductor, the aluminum wiring is disconnected.
[0017]
When using a "mixed gas of fluorine-based gas and chlorine-based gas only" to etch a metal multilayer film containing aluminum, aluminum reacts with fluorine-based gas to form aluminum fluoride due to the difference in vapor pressure. However, it tends to react with chlorine-based gas to form aluminum chloride. When etching is completed in this state, chlorine and aluminum remaining on the aluminum surface react to cause a phenomenon that the aluminum film is eroded over time.
[0018]
Therefore, in the present invention, since “Ar gas is added” to the etching gas, the chlorine component adhering to the sample is vaporized by sputtering with argon ions, and erosion over time can be prevented.
[0019]
Further, when the laminated film includes at least an aluminum film, the ratio of the fluorine-based gas and the chlorine-based gas in the etching gas is preferably set so that the number of chlorine atoms is less than the number of fluorine atoms. .
[0020]
Even in the present invention, the fluorine-based gas is CF. _Four As chlorine-based gas, BCl _Three Can be used. Other fluorinated and chlorinated gases such as CHF _Three Or Cl ₂ For example, a conventionally used gas can also be used.
[0021]
CF other than Ar gas in etching gas _Four And BCl _Three The ratio is expressed as a volume ratio under the same pressure, and 1: 1 to 5: 2 is appropriate.
It is also preferable to remove the photoresist after the etching process by an ashing process using oxygen gas plasma. This ashing process also removes chlorine-based components on the boundary surface and surface, and is more effective in preventing erosion over time.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Next, examples of the present invention will be described.
Example 1
FIG. 1 shows a metal film including an aluminum film or an aluminum oxide film, a metal oxide film, SiO 2 by the method of the present invention. ₂ It is a figure for demonstrating the Example which dry-etches the multilayer film which consists of films | membranes on a fixed condition, and is the figure which showed the process in order with sectional drawing of the target object.
[0023]
This embodiment will be described according to the process shown in FIG.
(A) An Al film 2 having a thickness of 70 nm on a quartz substrate 1 (thickness 1 mm), and an SiO film having a thickness of 20 nm for improving adhesiveness thereon. ₂ A film 3 and a Cr film 4 having a thickness of 30 nm are formed on the film 3 by sputtering, CVD, or vapor deposition.
[0024]
Next, a photoresist layer (model number: THMRip2250-13 manufactured by Tokyo Ohka Kogyo Co., Ltd.) 5 is applied on the Cr film 4. The coating thickness is applied so that the thickness is 3 to 4 μm after pre-baking. The prebaking condition is a hot plate at 130 ° C. for 45 seconds.
[0025]
The resist layer 5 is patterned by a normal lithography process to form a pattern having a length of 10 to 20 μm and a width of 2.5 to 5 μm. Thereafter, post-baking is performed at 130 ° C. for 180 seconds using a hot plate.
[0026]
(B) Next, using the laminated films 2, 3, and 4 as a mask, the resist pattern 5 is used as a mask, and continuously etched in the same etching chamber and under the same etching conditions in a “mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas”. To do. Among etching conditions, the etching gas has a mixing ratio of “CF _Four : BCl _Three : Ar = 7: 3: 10 "is used. Here, the mixing ratio representing the composition of the mixed gas is a volume ratio under the same pressure, for example, a flow rate ratio of gas introduced into the etching chamber. The same applies to the following embodiments. The upper electrode RF power is 1250 W, the lower electrode RF power is 600 W, the pressure is 1.5 mTorr, the etching end point is detected at the wavelength of SiFx (λ = 777 nm, etc.), and stopped by just etching. As an etching apparatus, an ICP (inductively coupled plasma) etching apparatus capable of obtaining high-density plasma is used.
[0027]
(C) After etching, the resist layer 5 is removed by oxygen gas plasma. At this time, the chlorine component on the boundary surface and the surface is also removed at the same time.
However, the Al film 2 may be replaced with another metal film such as a chromium film or Si, or an oxide film or a nitride film thereof. SiO ₂ Instead of the film 3, another oxide film or nitride film may be formed. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0028]
(Operational effect of Example 1)
In the prior art, metal films such as Cr and Al, these oxide films, SiO ₂ In a multilayer film made of an oxide film such as the above, dry etching is proceeded while changing gas conditions in accordance with the remaining film configuration accompanying the progress of etching. On the other hand, in this embodiment, high-density plasma is generated with “a mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas”, and from the start to the end of etching, (1) in the same etching chamber and under the same etching conditions, 2) Enables continuous dry etching.
[0029]
(Example 2)
2 shows a metal film, a metal oxide film and SiO. ₂ This is a diagram for explaining an embodiment of dry etching that enables side etching to be prevented without forming a side wall protective film under a certain condition by combining multilayer films, and the process is illustrated by a cross-sectional view of an object. It is the figure shown in order.
[0030]
This embodiment will be described in accordance with the process of FIG.
(A) By the same step as step (a) in FIG. 1, a metal film 7 made of aluminum having a thickness of 70 nm is formed on a quartz substrate (thickness 1 mm) 1, and SiO having a thickness of 20 nm is formed thereon. ₂ A Cr film 4 having a film thickness of 30 nm is formed on the film 3, and a resist layer is applied on the Cr film 4, and a resist pattern 5 is formed by a normal lithography process. The completed state is the same as that in FIG. However, the metal film 7 is not limited to an aluminum film, and may be a chromium film, another metal film such as Si, or an oxide film or a nitride film thereof. SiO ₂ Instead of the film 3, another oxide film or nitride film may be formed. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0031]
(B) The multilayer films 7, 3, and 4 are continuously etched under the same etching conditions in the same etching chamber using “the mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas” with the resist pattern 5 as a mask.
[0032]
Etching gas conditions are as follows: (1) Mixing ratio “CF” which prevents the product of fluorine and resist carbon _Four : BCl _Three : Ar = 1: 1: 2 ”and (2) Ar gas is added. As other conditions, upper electrode RF power: 1250 W, lower electrode RF power: 600 W, pressure: 1.5 mTorr, the etching end point is detected at the wavelength of SiFx (λ = 777 nm, etc.) and stopped by just etching. As the etching apparatus, an ICP etching apparatus capable of obtaining high-density plasma is used.
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
[0033]
(Effect of Example 2)
In the prior art, metal film, metal oxide film, SiO ₂ In a multilayer film in which films are combined, a protective film is formed on the side wall while etching is progressed to obtain a good shape, thereby preventing side etching. In the present invention, CF _Four : BCl _Three (2) Ar gas without forming a sidewall protective film by using a mixed gas of Ar, and (1) mixing ratio (1: 1: 2) that prevents formation of a product of fluorine and carbon of resist. Addition removes radical components to increase ion density and improve verticality.
[0034]
(Example 3)
FIG. 3 is a view for explaining an embodiment for preventing erosion over time in dry etching of a multilayer film containing aluminum by the method of the present invention, and is a view sequentially showing steps in cross-sectional views of an object. .
[0035]
This embodiment will be described according to the process shown in FIG.
(A) An Al film 2 having a thickness of 70 nm is formed on a quartz substrate (thickness 1 mm) 1, and a Cr film 4 having a thickness of 30 nm is formed thereon by a sputtering method, a CVD method or a vapor deposition method.
Next, a photoresist layer (model number: THMRip2250-13 manufactured by Tokyo Ohka Kogyo Co., Ltd.) 5 is applied on the Cr film 4. The coating thickness is applied so that the thickness is 3 to 4 μm after pre-baking. The prebaking condition is a hot plate at 130 ° C. for 45 seconds.
[0036]
The resist layer 5 is patterned by a normal lithography process to form a pattern having a length of 10 to 20 μm and a width of 2.5 to 5 μm. Thereafter, post-baking is performed at 130 ° C. for 180 seconds using a hot plate.
[0037]
(B) The multilayer film containing aluminum is continuously etched with “mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas” using the resist pattern 5 as a mask in the same etching chamber under the same etching conditions. This etching gas has a mixing ratio “CF” in which the number of chlorine atoms contained in the mixed gas is less than the number of fluorine atoms. _Four : BCl _Three : Ar = 5: 2: 10 ”, and (2) a feature is that Ar gas was added. In this etching, the upper electrode RF power is 1250 W, the lower electrode RF power is 600 W, the pressure is 1.5 mTorr, the etching end point is detected at the wavelength of SiFx (λ = 777 nm, etc.), and stopped by just etching. The apparatus uses an ICP that provides a high density plasma.
[0038]
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
However, instead of the Al film 2, a chromium film or another metal film may be used, or an oxide film thereof may be used. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0039]
(Effect of invention of Example 3)
In the prior art, in order to etch a metal multilayer film containing Al, the use of “mixed gas of fluorine-based gas and chlorine-based gas” causes chlorine to react with fluorine-based gas and aluminum to form aluminum fluoride. Reacts with system gases to form aluminum chloride. If chlorine remains, the metal multilayer film containing aluminum is eroded over time. Therefore, in this embodiment, (1) the reaction ratio between chlorine and aluminum is lowered by setting the mixture ratio so that the number of chlorine atoms contained in the mixed gas is smaller than the number of fluorine atoms. Further, (2) Ar gas is added to vaporize the chlorine component adhering to the sample by sputtering to prevent erosion over time. Further, after the etching is completed, oxygen gas plasma is introduced to remove the chlorine-based components on the boundary surface and the surface.
[0040]
Example 4
Metal film, metal oxide film, SiO ₂ With reference to FIG. 1, which is the same as that of the first embodiment, an embodiment in which a multilayer film composed of a film or the like eliminates a step at the boundary surface of the multilayer film will be described.
(A) Similar to step (a) in FIG. 1, an Al film 2 having a thickness of 70 nm is formed on a quartz substrate (thickness 1 mm) 1, and a Cr film having a thickness of 30 nm is formed thereon (or a metal oxide film thereof). Cr ₂ O _Three Film) 4 is formed, a resist layer is applied on the Cr film 4, and a resist pattern 5 is formed by a normal lithography process. However, in this embodiment, SiO between the Al film 2 and the Cr film 4 is used. ₂ The membrane 3 was omitted.
[0041]
(B) Using this resist film 5 as a mask, this multilayer film is continuously etched in the same etching chamber and under the same etching conditions with “a mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas”. The etching condition is a mixture ratio CF _Four : BCl _Three : Ar = 7: 3: 10 mixed gas, upper electrode RF power: 1250 W, lower electrode RF power: 600 W, pressure: 1.5 mTorr, etching end point detected by SiFx wavelength (λ = 777 nm, etc.) Stop with just etching. The apparatus uses an ICP that provides a high density plasma.
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
[0042]
However, the Al film 2 may be replaced with another metal film such as a chromium film or Si, or an oxide film or a nitride film thereof. In this embodiment, the SiO of FIG. 1 omitted. ₂ Instead of the film 3, another oxide film, nitride film, or metal film may be formed. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0043]
(Effect of Example 4)
In the prior art, metal films, these oxide films, SiO ₂ When performing dry etching of a multilayer film such as a film, since the dry etching is performed while changing the condition of "single or mixed gas of fluorine-based gas + chlorine-based gas" according to the film configuration, the history at the time of condition change remains A step is generated on the boundary surface of the film. Further, since it takes time for the plasma to stabilize when the conditions are changed, the perpendicularity temporarily deteriorates at the boundary surface of the film during this time, and side etching is promoted. Therefore, this embodiment is carried out under a certain condition to eliminate the step at the film interface in the multilayer film. Furthermore, since there is no change in conditions, the plasma is stable and the verticality is improved.
[0044]
(Example 5)
FIG. 4 is a diagram for explaining an example of a high selection ratio of resist to resist in dry etching of a metal film and a multilayer film made of an oxide film thereof according to the method of the present invention. FIG.
[0045]
This embodiment will be described in accordance with the process of FIG.
(A) On a quartz substrate (thickness 1 mm) 1, a Cr film 4 a having a film thickness of 30 nm and further Cr film having a film thickness of 30 nm thereon. ₂ O _Three The film 4b is formed by sputtering, CVD, or vapor deposition.
Next, Cr ₂ O _Three A photoresist layer is applied onto the film 4b in the same manner as in the embodiment of FIG. 1, and after pre-baking, the resist layer is patterned by a normal lithography process, and post-baking is performed to form a resist pattern 5.
[0046]
(B) This multilayer film is made of “fluorine gas, chlorine gas and Ar gas mixed gas” and “CF _Four : BCl _Three = 7: 3 "and" (CF _Four + BCl _Three ): Ar gas mixture ratio is increased so that Ar = 10: 10 to 10:20, and etching is continuously performed in the same etching chamber and under the same etching conditions. Etching conditions are: upper electrode RF power: 1250 W, lower electrode RF power: 600 W, pressure: 1.5 mTorr, the etching end point is detected at the wavelength of SiFx (λ = 777 nm, etc.) and stopped by just etching. As the etching apparatus, an ICP etching apparatus capable of obtaining high-density plasma is used.
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
[0047]
By adding this Ar gas, the selectivity to resist was greatly improved.
However, other metal films may be used in place of the Cr film 4a, or oxide films or nitride films thereof may be used. Cr ₂ O _Three Instead of the film 4b, another metal oxide film may be formed. Further, the film thickness is not limited to the above.
[0048]
(Effect of Example 5)
In the prior art, when performing dry etching of a metal film, a reaction product of an etching gas and a resist is used for side wall adhesion in order to maintain a good shape, so that there is a problem that the selectivity to resist is lowered. For this reason, in this example, the Ar gas was added and the Ar gas mixture ratio was increased by using a “fluorine gas / chlorine gas / Ar gas mixed gas”, so that a high resist selectivity ratio could be realized. It was.
[0049]
(Example 6)
Metal film, metal oxide film, SiO ₂ With reference to FIG. 1, which is the same as that of the first embodiment, an embodiment in which a multilayer film composed of a film or the like eliminates a step at the boundary surface of the multilayer film is described.
(A) Similar to step (a) in FIG. 1, an Al film 2 having a thickness of 70 nm is formed on a quartz substrate (thickness 1 mm) 1, and an SiO film having a thickness of 20 nm is formed thereon. ₂ The film 3 and further a Cr film with a thickness of 30 nm (or Cr which is a metal oxide film thereof) ₂ O _Three Film) 4 is formed, a resist layer is applied on the Cr film 4, and a resist pattern 5 is formed by a normal lithography process.
[0050]
(B) Using the resist pattern 5 as a mask, this multilayer film is continuously etched in the same etching chamber and under the same etching conditions with “a mixed gas of fluorine-based gas, chlorine gas, and Ar gas”. The etching condition is a mixture ratio CF _Four : Cl ₂ : Ar = 2: 1: 3 mixed gas, upper electrode RF power: 800-1000 W, lower electrode RF power: 400-500 W, pressure: 2-3 mTorr, etching end point is wavelength of SiFx (λ = 777 nm, etc.) ) And stop at just etching. The apparatus uses an ICP that provides a high density plasma.
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
[0051]
However, the Al film 2 may be replaced with another metal film such as a chromium film or Si, or an oxide film or a nitride film thereof. SiO ₂ Instead of the film 3, another oxide film or nitride film may be formed. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0052]
(Effect of Example 6)
In Example 4, the object was achieved by performing continuous etching with “a mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas” in the same etching chamber and under the same etching conditions. In this embodiment, the etching gas is “fluorine gas and Cl”. ₂ By changing the gas mixture ratio, the upper electrode RF power, the lower electrode RF power, and the pressure continuously, instead of “gas and Ar gas mixed gas”, the step on the film interface in the multilayer film is eliminated. . Furthermore, in this embodiment, since there is no change in conditions during etching, the plasma is stable and the verticality is improved.
[0053]
(Example 7)
Metal film, metal oxide film, SiO ₂ With reference to FIG. 1, which is the same as that of the first embodiment, an embodiment in which a multilayer film composed of a film or the like eliminates a step at the boundary surface of the multilayer film will be described.
(A) Similar to step (a) in FIG. 1, an Al film 2 having a thickness of 70 nm is formed on a quartz substrate (thickness 1 mm) 1, and an SiO film having a thickness of 20 nm is formed thereon. ₂ The film 3 and further a Cr film with a thickness of 30 nm (or Cr which is a metal oxide film thereof) ₂ O _Three Film) 4 is formed, a resist layer is applied on the Cr film 4, and a resist pattern 5 is formed by a normal lithography process.
[0054]
(B) Using the resist pattern 5 as a mask, this multilayer film is continuously etched in the same etching chamber and under the same etching conditions with “a mixed gas of fluorine-based gas, chlorine gas, and Ar gas”. The etching condition is a mixture ratio CF _Four : (BCl _Three + Cl ₂ ): Ar = 2: 1 (0.5: 0.5): 3 gas mixture is used, upper electrode RF power: 1000 W, lower electrode RF power: 500 W, pressure: 2-3 mTorr, etching end point is SiFx Detection is performed at a wavelength (λ = 777 nm, etc.) and the etching is stopped by just etching. The apparatus uses an ICP that provides a high density plasma.
(C) After etching, the resist layer 5 is removed by oxygen gas plasma.
[0055]
However, the Al film 2 may be replaced with another metal film such as a chromium film or Si, or an oxide film or a nitride film thereof. SiO ₂ Instead of the film 3, another oxide film or nitride film may be formed. Further, instead of the Cr film 4, another metal film or a metal oxide film thereof may be formed. Further, the film thickness is not limited to the above.
[0056]
(Effect of Example 7)
In Example 1, a high-density plasma was generated by “a mixed gas of fluorine-based gas, chlorine-based gas, and Ar gas”, and the object was achieved by continuously etching the multilayer film in the same etching chamber and under the same etching conditions. . In this embodiment, the etching gas is “fluorine gas and (BCl _Three + Cl ₂ By changing the gas mixture ratio, the upper electrode RF power, the lower electrode RF power, and the pressure continuously and etching, the step of the film boundary surface in the multilayer film is eliminated. did. Furthermore, in this embodiment, since there is no change in conditions during etching, the plasma is stable and the verticality is improved.
[0057]
【The invention's effect】
As described above, according to the present invention, in dry etching of a multilayer film including a metal film or a metal oxide film, plasma is generated with a mixed gas including Ar gas, and the multilayer film is the same in the same etching chamber with the plasma. Since the etching is continuously performed under the etching conditions, the step at the boundary surface of the film is eliminated, and the target vertical patterning shape is controlled to maintain the resist selectivity ratio.
[Brief description of the drawings]
FIG. 1 is a process cross-sectional view for explaining an embodiment.
FIG. 2 is a process cross-sectional view for explaining another embodiment.
FIG. 3 is a process cross-sectional view for explaining still another embodiment.
FIG. 4 is a process cross-sectional view for explaining still another embodiment.
[Explanation of symbols]
1 Quartz substrate
7 Metal film
2 Al film
3 SiO ₂ film
4,4a Cr film
4b Cr ₂ O _Three film
5 Photoresist film

Claims (3)

In a method of forming a photoresist pattern on a laminated film including a metal film or a metal oxide film, and patterning the laminated film by dry etching using the resist pattern as a mask,
Etching is performed by plasma etching method,
Using a mixed gas containing Ar gas in fluorine gas and chlorine gas as etching gas,
The composition of the mixed gas is expressed as a volume ratio under the same pressure, and the ratio of the fluorine-based gas and the chlorine-based gas is 1: 1 to 5: 2, and the total volume of the fluorine-based gas and the chlorine-based gas is 1 When the volume ratio of Ar gas is 1-2,
CF ₄ gas is used for the fluorine-based gas, BCl ₃ gas or a mixed gas of BCl ₃ and Cl ₂ is used for the chlorine-based gas ,
A dry etching method characterized by performing continuously under the same etching conditions in the same etching chamber from the start to the end of etching.   The dry etching method according to claim 1, wherein the laminated film includes at least an aluminum film. The dry etching method according to claim 1 or 2 , wherein the photoresist after the etching process is finished is removed by an ashing process using oxygen gas plasma.

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