KR20170001056A - Method for Etching of Magnetic Thin Films Using Acetic Acid Gas - Google Patents
Method for Etching of Magnetic Thin Films Using Acetic Acid Gas Download PDFInfo
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- KR20170001056A KR20170001056A KR1020150090443A KR20150090443A KR20170001056A KR 20170001056 A KR20170001056 A KR 20170001056A KR 1020150090443 A KR1020150090443 A KR 1020150090443A KR 20150090443 A KR20150090443 A KR 20150090443A KR 20170001056 A KR20170001056 A KR 20170001056A
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- 239000010409 thin film Substances 0.000 title claims abstract description 163
- 238000005530 etching Methods 0.000 title claims abstract description 135
- 238000000034 method Methods 0.000 title claims abstract description 55
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 title claims abstract description 54
- 239000007789 gas Substances 0.000 claims description 87
- 229910019236 CoFeB Inorganic materials 0.000 claims description 83
- 238000001020 plasma etching Methods 0.000 claims description 22
- 239000011261 inert gas Substances 0.000 claims description 18
- 238000000059 patterning Methods 0.000 claims description 8
- 230000008569 process Effects 0.000 claims description 8
- 229910052786 argon Inorganic materials 0.000 claims description 7
- 238000009616 inductively coupled plasma Methods 0.000 claims description 4
- 230000000873 masking effect Effects 0.000 claims description 4
- 229910003321 CoFe Inorganic materials 0.000 claims description 3
- 229910019230 CoFeSiB Inorganic materials 0.000 claims description 3
- 229910019227 CoFeTb Inorganic materials 0.000 claims description 3
- 229910018979 CoPt Inorganic materials 0.000 claims description 3
- 229910001030 Iron–nickel alloy Inorganic materials 0.000 claims description 3
- 229910017028 MnSi Inorganic materials 0.000 claims description 3
- 229910052734 helium Inorganic materials 0.000 claims description 3
- 229910052754 neon Inorganic materials 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 125000000896 monocarboxylic acid group Chemical group 0.000 abstract description 32
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 44
- 230000000052 comparative effect Effects 0.000 description 34
- 238000000151 deposition Methods 0.000 description 17
- 230000008859 change Effects 0.000 description 15
- 238000004833 X-ray photoelectron spectroscopy Methods 0.000 description 13
- 238000004458 analytical method Methods 0.000 description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 11
- 230000003247 decreasing effect Effects 0.000 description 9
- 239000000758 substrate Substances 0.000 description 9
- 230000002829 reductive effect Effects 0.000 description 8
- 150000002500 ions Chemical class 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000000992 sputter etching Methods 0.000 description 7
- 238000006243 chemical reaction Methods 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 5
- 239000002245 particle Substances 0.000 description 5
- 238000004544 sputter deposition Methods 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 238000001636 atomic emission spectroscopy Methods 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 229910052796 boron Inorganic materials 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- -1 FeB Substances 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000001312 dry etching Methods 0.000 description 2
- 238000000445 field-emission scanning electron microscopy Methods 0.000 description 2
- 239000010408 film Substances 0.000 description 2
- 229910052736 halogen Inorganic materials 0.000 description 2
- 150000002367 halogens Chemical class 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 229920002120 photoresistant polymer Polymers 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 239000003039 volatile agent Substances 0.000 description 2
- 238000001039 wet etching Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 229910002090 carbon oxide Inorganic materials 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000000295 complement effect Effects 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- JKWMSGQKBLHBQQ-UHFFFAOYSA-N diboron trioxide Chemical compound O=BOB=O JKWMSGQKBLHBQQ-UHFFFAOYSA-N 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000010849 ion bombardment Methods 0.000 description 1
- 230000005415 magnetization Effects 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000000859 sublimation Methods 0.000 description 1
- 230000008022 sublimation Effects 0.000 description 1
- 238000009834 vaporization Methods 0.000 description 1
- 230000008016 vaporization Effects 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/3065—Plasma etching; Reactive-ion etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
- H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
- H01L21/30604—Chemical etching
- H01L21/30612—Etching of AIIIBV compounds
- H01L21/30621—Vapour phase etching
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
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Abstract
The present invention relates to a method of etching a magnetic thin film and more particularly to a method for etching a magnetic thin film, which is less corrosive and less expensive than a conventional etching method, and re-deposition occurs by a new method of etching using a safe gas of acetic acid (CH 3 COOH) And more particularly, to a method of etching a magnetic thin film which can be applied to all elements and devices using a magnetic thin film by providing an appropriate etching rate and a high anisotropic etching profile, and which is effective for forming a fine pattern.
Description
The present invention relates to a method of etching a magnetic thin film using an acetic acid gas.
Among the various electrical and electronic devices that exist, there are devices and devices that are manufactured using magnetic materials or magnetic thin films. Among them, when a thin film of a magnetic material, that is, a magnetic thin film (magnetic thin film) is used, patterning of the magnetic thin film must be performed. That is, the patterning of the magnetic thin film is completed by completing the deposition of the magnetic thin film and then patterning it to form the mask and removing the exposed portion around the mask pattern by the etching process, and after the subsequent processes are completed, the devices and devices are manufactured .
In general, there are wet etching and dry etching methods for the etching of magnetic thin films. As the size of patterns to be etched is reduced to below a few micrometers, it is difficult to apply wet etching. Therefore, The need for
The dry etching process is called a plasma etching and can be classified into ion milling etching and reactive ion etching due to the chemical reactivity of the plasma. Argon (Ar) plasma is used as an inert gas, and reactive ion etching is performed using various chemical gases.
In general, magnetic thin films are very low chemically reactive materials and are mainly etched using ion milling method. However, the etching of the magnetic thin film using ion milling causes re-deposition around the etched pattern to form a fence shape as shown in FIG. 1 (b). This is due to the etching mechanism in which ion milling etching is performed by sputtering a part of the magnetic material by the collision energy of pure argon (Ar) cations without chemical reaction.
Therefore, when the size of the pattern on the magnetic thin film is reduced to submicrometer or nanometer size or when the interval between the patterns is reduced to the nanometer size, there is a problem that the re-deposition is further intensified. In addition, if the thickness of the magnetic thin film is reduced to less than the nanometer level, there is a problem that the thin film is connected to the thin films on the upper side to cause a short circuit. In case of etching the magnetic thin film for the manufacture of high integration devices, Reactive ion etching with chemical reaction should be applied.
However, when the magnetic thin film is etched by the reactive ion etching method, an inappropriate etching gas is used, or when an inappropriate etching process is applied, redeposition occurs on the side of the etched pattern. Also, the occurrence of redeposition is reduced when the etching is performed under an unoptimized etching gas or etching condition, but the etched side inclination (etching gradient) is very gentle as shown in Fig. 1 (c) There are problems that are difficult to apply.
Korean Patent Laid-Open Publication No. 1998-0006194 discloses a method of etching a transition metal thin film. At least one first gas selected from a halogen gas and a halogen gas and a second gas selected from a carbon oxide gas, a hydrocarbon gas, a nitrogen oxide gas and a nitrogen gas are injected in the form of a mixed gas Thereby converting the transition metal thin film into a volatile compound and performing etching. There is an advantage that etching can be performed at a high etching rate without by-products which are redeposited by vaporization or sublimation of a volatile compound. However, the above method has a problem in that it is not suitable for the etching of magnetic thin films such as nickel, iron, and cobalt due to the property of maintaining the substrate temperature at 200 ° C or higher.
The main object of the present invention is to provide a method of etching a magnetic thin film using acetic acid gas, which can provide a rapid etching rate and a high anisotropic etching profile without inducing corrosion of another thin film without re-deposition around the etched pattern .
According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, including: (a) patterning and masking a magnetic thin film with a mask; (b) plasmaizing a mixed gas containing 20 to 80 vol% of acetic acid gas and 20 to 80 vol% of an inert gas; And (c) etching the magnetic thin film masked in step (a) using the plasma generated in step (b).
In a preferred embodiment of the invention, the magnetic thin film is characterized in that at least one member selected from the group consisting of CoFe, CoFeB, CoFeSiB, CoFeTb, Co 2 MnSi, CoZr, CoZrB, CoZrTb, CoPt, NiFeCo, NiFeCr and NiFe can do.
In one preferred embodiment of the present invention, the inert gas may be at least one selected from the group consisting of He, Ne, Ar, and N 2 .
In a preferred embodiment of the present invention, the mixed gas of step (b) may include 20 vol% to 40 vol% of acetic acid gas and 60 vol% to 80 vol% of inert gas.
In a preferred embodiment of the present invention, the plasmaization in the step (b) is performed by injecting a mixed gas at a pressure in the range of 0.10 Pa to 1.33 Pa, applying a high frequency power of 800 W or more, a DC bias voltage of 200 V to 400 V And the like.
In a preferred embodiment of the present invention, the plasmaization in the step (b) is performed by a group consisting of a high density plasma reactive ion etching method, a self-enhanced reactive ion etching method, and a reactive ion etching method including an inductively coupled plasma reactive ion etching The method may be carried out in one selected method.
The etching method of the magnetic thin film using the acetic acid gas according to the present invention is a new method of etching by using acetic acid (CH 3 COOH) gas which is less corrosive than the conventional etching method and is very inexpensive and safe gas, It can be applied to all devices and devices in which a magnetic thin film is used by providing an appropriate etching rate and a high anisotropic etching profile, and is particularly effective for forming fine patterns.
FIG. 1 schematically shows a side structure before and after thin film etching, wherein (a) is a thin film structure before etching, (b) is a thin film structure etched by a conventional ion milling etching method, Lt; RTI ID = 0.0 > etched. ≪ / RTI >
FIG. 2 is a graph showing etch rate change and etch selectivity of CoFeB thin film and TiN hard mask according to CH 3 COOH gas concentration in CH 3 COOH / Ar mixed gas.
FIG. 3 is a SEM photograph of a CoFeB thin film etched according to CH 3 COOH gas concentration in a CH 3 COOH / Ar mixed gas, wherein (a) is a pre-etch thin film, (b) is a thin film etched in Comparative Example 1 (c) is the thin film etched in Example 1, (d) is the thin film etched in the thin film etched in Example 2, (e) is the thin film etched in the thin film etched in Example 3, The thin film was etched in Comparative Example 2.
4 is a graph showing changes in etch rate and etch selectivity of a CoFeB thin film and a TiN hard mask according to coil high frequency power.
5 (a) is a thin film etched in Comparative Example 4, (b) is a thin film etched in Example 1, and FIG. 5 (c) is a SEM image of a CoFeB thin film etched according to Example 4 .
6 is a graph showing etch rate change and etch selectivity of a CoFeB thin film and a TiN hard mask according to a DC bias voltage.
7 is an SEM photograph of a CoFeB thin film etched according to a DC bias voltage, wherein (a) is a thin film etched in Comparative Example 5, (b) is a thin film etched in Example 5, and (c) (D) is the thin film etched in Example 6.
8 is a graph showing changes in etch rate and etch selectivity of the CoFeB thin film and the TiN hard mask according to the gas pressure in the chamber.
FIG. 9 is a SEM photograph of the CoFeB thin film etched according to the gas pressure in the chamber, in which (a) is the thin film etched in Example 7, (b) is the thin film etched in Example 1, 8. ≪ / RTI >
10 is an SEM photograph of a CoFeB thin film etched in Example 9 according to the present invention.
11 is an OES analysis graph of particles in a plasma according to CH 3 COOH gas concentration (Examples 1 to 3) in a CH 3 COOH / Ar mixed gas.
12 is a graph showing the ratio of the intensities of the components of the particles and the Ar ions in the plasma according to the CH 3 COOH gas concentration in the CH 3 COOH / Ar mixed gas.
Figure 13 Examples 1 and 3 in the CoFeB thin film etching before / after XPS (Co 2P 3/2) is an analysis graph.
Figure 14 is the first embodiment, and CoFeB thin film etching before / after XPS in 3 (Fe 2P 3/2) is an analysis graph.
15 is an XPS (
16 is an XPS (
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In general, the nomenclature used herein is well known and commonly used in the art.
Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise.
(A) patterning and masking a magnetic thin film with a mask; (b) plasmaizing a mixed gas containing 20 to 80 vol% of acetic acid gas and 20 to 80 vol% of an inert gas; And (c) etching the magnetic thin film masked in the step (a) using the plasma generated in the step (b).
Hereinafter, the present invention will be described in detail.
In the method of etching a magnetic thin film according to the present invention, the step (a) is a step of patterning and masking the magnetic thin film with a mask.
In this case, it is preferable to use the CoFe, CoFeB, CoFeSiB, CoFeTb, Co 2 MnSi, CoZr, CoZrB, CoZrTb, CoPt, NiFeCo, NiFeCr and NiFe or the like.
The mask of step 1 is preferably a hard mask, more preferably a Ti or TiN hard mask. Conventionally, a photoresist mask is mainly used, but the photoresist mask is not suitable for application to a magnetic thin film having a low etching rate because the etching rate is very high.
In the method for etching a ruthenium thin film according to the present invention, step (b) is a step of plasma-forming a mixed gas containing 20 to 80 vol% of acetic acid gas and 20 to 80 vol% of an inert gas.
The acetic acid gas performs a reactive ion etching of a magnetic thin film and the inert gas performs a physical etching of a magnetic thin film. In ion milling etching, which is a physical etching method of a general magnetic thin film, re-deposition occurs around an etched pattern, However, in the case of using the mixed gas containing the acetic acid gas and the inert gas, the deposition does not occur around the pattern etched by the complementary action, and the etching rate and the high anisotropic etching profile Can be provided.
If the acetic acid gas in the mixed gas is less than 20 vol%, re-deposition may occur on the side of the etch, which may result in different results from the mask pattern. If the etch rate is too high The etching gradient becomes gentle and re-deposition material may be generated on the etched surface or side surface. Acetic acid gas may be contained in an amount of 20 to 80 vol% based on the total volume of the mixed gas, preferably 20 to 40 vol% % ≪ / RTI >
On the other hand, the inert gas is preferably one selected from the group consisting of He, Ne, Ar, and N 2 gases. The acetic acid gas induces a chemical etch while the inert gases perform a physical etch. If the inert gas is contained in the mixed gas at less than 20 vol%, it is difficult to apply the etched side slope to the etching of the fine pattern, and if it exceeds 80 vol% The inert gas may be used in an amount of 20 to 80 vol% based on the total volume of the mixed gas, and preferably 60 to 80 vol% of the inert gas may be used based on the total volume of the mixed gas. have.
The plasmaization in the step (b) may be performed by one of the methods selected from the group consisting of a high density plasma reactive ion etching method, a magnetically enhanced reactive ion etching method, and a reactive ion etching method including an inductively coupled plasma reactive ion etching method .
In this etching method, a high-density plasma can be generated, and an independent RF power is connected to the substrate to apply a bias voltage to the substrate. Thus, high energy collisions of ions with the substrate are possible, It is chemically reacted with radicals coming from inside and etching proceeds. Also, if the volatility of the reaction product due to the chemical reaction is weak, re-deposition occurs on the etched side, where physical sputtering of the ions on the substrate helps to desorb the redeposition material.
Particularly, in the high density plasma ion etching method, power applied to the external coil transfers energy to electrons in the generated plasma in the chamber to obtain a high density plasma, which is advantageous in that the etching rate is fast and there is no damage due to ion impact.
In addition, reactive ion etching is a technique for removing materials from a wafer surface during reactive chemical processes and physical processes using ion bombardment. Self - enhanced reactive ion etching is a magnetically enhanced reactive ion etching reaction that combines physical and chemical methods. Plasma with a magnetic field has the advantage of maintaining the directionality and uniformity of the etch in the case of etching with high aspect ratio properties, allowing high density plasma and operation at low pressures. However, when using a general low-density reactive ion etching method, it is difficult to obtain the above effects, and accordingly, there is a problem in that an appropriate etching rate and anisotropic etching are not performed.
In this case, the plasma may be performed by injecting the above-described mixed gas at a pressure in the range of 0.10 Pa to 1.33 Pa, applying a high frequency power of 800 W or more, and a DC bias voltage of 200 V to 400 V.
If the mixed gas pressure is less than 0.10 Pa, there is a problem that the amount of gas in the chamber is too small, plasma generation is unstable, and stability and reproducibility of etching are deteriorated. When the gas mixture pressure exceeds 1.33 Pa, Radicals and the like are relatively increased. However, as the average free path of these materials becomes smaller and physical collisions frequently occur, ultimately, a slow etching rate and a low etching gradient are obtained, and the re-deposition of the etched surface Problems may arise.
When the high frequency power of the coil is less than 800 W, there may arise a problem that the inclination of the etching side is gently etched, which may be more than 800 W. In order to prevent the etching damage and maintain the magnetization of the thin film, Or less.
In addition, when the DC bias voltage is less than 200 V, the voltage applied to the etched sample is low, so that the amounts of ions, radicals, and the like generated by the plasmaization are reduced to the sample. In addition, A slow etch rate and a low etch pattern can be obtained and redeposition can occur on the etched side and a high DC bias voltage in excess of 400 V can improve the etch rate and etch slope, Etch damage caused by the etchant may occur, which may cause deterioration of the electrical characteristics of the device to be manufactured in the future.
In the method of etching a magnetic thin film according to the present invention, the step (c) is a step of etching the magnetic thin film masked in the step (a) using the plasma generated in the step (b). The magnetic thin film can be etched at a high speed by inhibiting the deposition of the magnetic thin film through the generated plasma using the mixed gas, and the occurrence of re-deposition on the etched surface can be suppressed.
The etching of step (c) is performed by high energy collision of the ions with the substrate, whereby the broken chemical bonds are chemically reacted with the radicals inside the plasma. At this time, when the volatility of the reaction product due to the chemical reaction is weak, re-deposition occurs on the etched side, and physical sputtering of the ions on the substrate plays a role in helping the re-deposition materials to be desorbed, thereby suppressing re-deposition.
Hereinafter, the present invention will be described in more detail by way of examples. It should be noted, however, that the following examples are illustrative of the invention and are not intended to limit the scope of the invention.
< Example 1>
The CoFeB thin film was masked by patterning the TiN hard mask on the substrate on which the CoFeB thin film was deposited by a known method. The masked substrate was placed at a distance of 120 mm from the ICP coil and a mixed gas of the following Table 1 was flowed at a process pressure of 0.67 Pa. A plasma high frequency power of 800 W and a DC bias of 300 V were applied to form a plasma, The CoFeB thin film masked with the hard mask was etched.
< Example 2 to 9 and Comparative Example 1 to 7>
The etching conditions for Examples 2 to 9 and Comparative Examples 1 to 7 are shown in Table 1, and the etching of the CoFeB thin film except for each condition was performed in the same manner as in Example 1 to etch.
(W)
(Pa)
gas
(vol%)
(vol%)
< Experimental Example 1> Depending on the mixing ratio of the mixed gas CoFeB Thin film and TiN Mask Etching rate analysis
In order to investigate the etching rate and selectivity (= magnetic thin film etching rate / TiN hard mask etching rate) of the CoFeB thin film and the TiN hard mask according to the mixture ratio of CH 3 COOH and Ar as the etching gas, Comparative Examples 1 and 2 and Example The etch rates of the thin films etched at 1 to 3 were measured and the results are shown in FIG. 2, respectively.
As shown in FIG. 2, in the case of Comparative Example 1 using only Ar, which is an inert gas, the etch rate of the thin film and the TiN hard mask was found to be high, but the etching selectivity of the CoFeB thin film to the TiN hard mask was remarkably decreased In the case of Comparative Example 2 using only CH 3 COOH gas, it was confirmed that the etching rate of the CoFeB thin film and the TiN hard mask was reduced.
In the case of Examples 1 to 3, the etching rate of the CoFeB thin film and the TiN hard mask was decreased as the concentration of CH 3 COOH gas was increased. The selectivity for the CoFeB thin film and the TiN mask was found to be When the ratio of CH 3 COOH gas was 25%, the highest selectivity was obtained.
< Experimental Example 2> Depending on the mixing ratio of the mixed gas Etched CoFeB Thin film observation
In order to observe the etching surface of the CoFeB thin film according to the mixing ratio of CH 3 COOH and Ar as the etching gas, the side surfaces of the thin films etched in Comparative Examples 1 and 2 and Examples 1 to 3 were measured with an SEM (Hitachi SE-4300) And the results are shown in Fig. 3, respectively. 3 (a) is a side view of the pre-etching thin film, (b) is a side view of the thin film etched in Comparative Example 1, (c) is a side view of the thin film etched in Example 1, (E) is a side view of the thin film observed in Example 3, and (f) corresponds to a side surface of the thin film etched in Comparative Example 2. FIG.
As shown in FIG. 3, in the case of Comparative Example 1, re-deposition was observed on the side of the etched pattern, and in Example 1 containing 25 vol% CH 3 COOH, the etching gradient of about 80 ° without re- And it was confirmed that as the concentration of CH 3 COOH gas increases as in Examples 2 and 3, the etching slope becomes gentle.
Therefore, it was found that the etching can be effectively performed when the CHF 3 COOH gas and the inert gas (Ar) are mixed to perform the etching of the CoFeB thin film.
< Experimental Example 3> Due to coil high frequency power change CoFeB Thin film and TiN Mask Etching Speed analysis
In order to investigate the etching rate and selectivity (= CoFeB thin film etching rate / TiN hard mask etching rate) of the CoFeB thin film and the TiN hard mask according to the change of the coil high frequency power for the plasmaization, Examples 1 and 4, The etch rate was measured for the etched thin films in FIG. 4, and the results are shown in FIG.
As shown in FIG. 4, as the coil RF power was increased, the etching rate for the CoFeB thin film and the TiN mask was increased. Especially, the etching rate of the CoFeB thin film was higher than the etching rate of the TiN hard mask. The etching selectivity of the CoFeB thin film was also gradually increased. In Examples 1 and 4, the etching rate and etching selectivity were superior to those of Comparative Example 4. In the case of Comparative Example 3, the polymer was formed on the surface of the thin film because the sputtering effect was small, and the etching rate was slowed down.
This means that if the etching selectivity is excellent as in Examples 1 and 4, the desired thin film can be etched even with a thin hard mask, and the etching profile can be improved.
< Experimental Example 4> Depending on coil high frequency power change Etched CoFeB Observation of Thin Film
In order to observe the etching surface of the CoFeB thin film according to the change of the coil high-frequency power for plasmaization, the side of the thin film etched in Comparative Example 4 and Examples 1 and 4 was observed with SEM (Hitachi SE-4300) Are shown in Fig. 5, respectively. 5A is a side view of the thin film etched in Comparative Example 4, FIG. 5B is a side view of the thin film etched in Example 1, and FIG. 5C is a side view of the thin film etched in Example 4 do.
As shown in FIG. 5, in the case of the CoFeB thin films etched in Examples 1 and 4 as compared with the CoFeB thin films etched in Comparative Example 4, It was observed that the etching slope was close to about 70 °.
< Experimental Example 5> DC Depending on the change in bias voltage CoFeB Thin film and TiN Mask Etching rate analysis
In order to investigate the etching rate and selectivity (= CoFeB thin film etching rate / TiN hard mask etching rate) of the CoFeB thin film and the TiN hard mask according to the DC bias voltage change, Examples 1, 5 and 6 and Comparative Examples 5 and 6 The etching rate was measured on the etched thin film, and the results are shown in FIG.
As shown in FIG. 6, the etching rates for the CoFeB thin film and the TiN hard mask are improved as the DC bias voltage increases from 100 V to 400 V in Examples 1, 5 and 6 and Comparative Example 5. It can be seen that the DC bias change affects the etching rate. In addition, it was confirmed that the selectivity of the CoFeB thin film to the TiN hard mask increases as the DC bias voltage increases.
However, in Comparative Example 5 in which the DC bias was 100 V, a negative etching rate was obtained because deposition occurred under the low sputter condition (low Ar concentration) than in the etching. In Comparative Example 6, And the thin film was damaged.
< Experimental Example 6> DC Depending on the change in bias voltage Etched CoFeB Observation of Thin Film
In order to observe the etched surface of the CoFeB thin film according to the DC bias voltage change, the side surfaces of the thin films etched in Examples 1, 5 and 6 and Comparative Example 5 were observed by scanning electron microscopy (FE-SEM, Hitachi S -4300), and the results are shown in Fig. (B) is the thin film etched in Example 5, (c) is the thin film etched in Example 1, (d) is the thin film etched in Comparative Example 5, .
As shown in FIG. 7, in the case of the CoFeB thin films etched in
< Experimental Example 7> Chamber Depending on gas pressure change CoFeB Thin film and TiN hard Etch rate analysis of mask
In order to investigate the etching rate and selectivity (= CoFeB thin film etching rate / TiN hard mask etching rate) of the CoFeB thin film and the TiN hard mask according to the gas pressure change for the plasmaization, Examples 1, 7 and 8 and Comparative Example 7 The etch rates were measured on the etched thin films. The results are shown in FIG.
As shown in FIG. 8, the etching rate for the CoFeB thin film and the TiN hard mask is lowered as the gas pressure in the chamber is increased as in Comparative Example 7. On the other hand, the etching selectivity of the CoFeB thin film to the Ti hard mask And it gradually increased.
This is because the plasma density increases as the chamber pressure increases, but the scattering phenomenon of the particles increases and the mean free path decreases. As a result, the activity of the particles in the plasma is reduced and the etching rate Was decreased.
Therefore, it is understood that the preferable chamber pressure in terms of the etching rate and the selectivity of the thin film is 0.13 to 0.67 Pa.
< Experimental Example 8> Chamber Depending on the gas pressure change Etched CoFeB Observation of Thin Film
In order to observe the etched surface of the CoFeB thin film according to the gas pressure change for the plasmaization, the side surfaces of the etched thin films in Examples 1, 7, 8 and 9 were observed by a scanning electron microscope (FE-SEM, Hitachi S -4300). The results are shown in Figs. 9 and 10. Fig.
As shown in FIG. 9, the etching gradient of the CoFeB thin film etched in Example 7 was observed to be more perpendicular anisotropy than the etching gradient of the CoFeB thin film etched in Examples 7 and 8, and an excellent etching profile was observed as the process pressure was decreased I could confirm.
In addition, as shown in FIG. 10, it can be confirmed that the etched CoFeB thin film in Example 9 has an etching gradient of about 72 degrees.
< Experimental Example 9> Depending on the mixing ratio of the mixed gas OES analysis
In order to analyze changes in the intensity of particles in the plasma depending on the mixture ratio of CH 3 COOH gas and Ar gas in Examples 1 to 3, optical emission spectroscopy (OES) 2000 pro) analysis results.
As shown in FIG. 11, as the concentration of CH 3 COOH gas increases, the intensity of Ar decreases sharply and the concentrations of H, OI, OII, CO, and C increase, This means that it plays an important role in raising the etching gradient.
In addition, each of CH 3 COOH concentration in the [H], [OI], [O II], [CO] , and a value obtained by dividing the strength by [Ar] the strength of the [C] to clearly demonstrated a tendency of the respective species 12. As shown in FIG. 12, as the concentration of CH 3 COOH increased from 25% to 50% in the CH 3 COOH / Ar plasma, the intensity ratio of each species increased. Based on this result, CH 3 COOH As the concentration increases, CoFeB thin film is [O x] may be oxidized due to an increase in the radical, and [H] and [C], which in strength is increased to a CoFeB film surface C x And the formation of a protective film of H y is increased.
< Experimental Example 10> Depending on the mixing ratio of the mixed gas Etched CoFeB Thin-film XPS analysis
In order to investigate the chemical reaction of the CoFeB thin film according to the mixing ratio of CH 3 COOH gas and Ar gas, the Co 3d 5 / 2 , and analyzed by XPS (X-ray photoelectron spectroscopy, ThermoScientific K-alpha). The results are shown in FIG.
As shown in FIG. 13, when the CH 3 COOH gas concentration was increased and the etching rate was increased as in Example 3, the strength of the metal Co was decreased, and the strength of the entire metal oxide was decreased as compared with the pre-etching sample .
Further, in Examples 1 and 5 were analyzed by the Fe 3d / 2 scan a narrow XPS (X-ray Photoelectron spectroscopy, ThermoScientific K-alpha) to the etching of the CoFeB
As shown in FIG. 14, Fe, FeB, Fe 2 B, Fe 3 O 4 , FeO and Fe 2 O 3 compounds were found in a narrow scan of the pre-etching samples. In the case of Example 1 in which 25 vol% CH 3 COOH gas and 75 vol% Ar gas were mixed to be etched, the metal Fe intensity was decreased and the peak intensity of the entire metal oxide compound was decreased as compared with the pre-etching sample. However, it can be seen that in the case of Example 3 where 75 vol% CH 3 COOH gas and 25 vol% Ar gas were mixed and etched, the metal oxide strength was increased with respect to the 25% CH 3 COOH sample.
In addition, in Examples 1 and 3, the CoFeB thin film was analyzed by XPS (X-ray photoelectron spectroscopy, ThermoScientific K-alpha) which was narrowly scanned with B 1 S of the etched CoFeB thin film.
As shown in FIG. 15, B, B 4 C, B 2 O 3 , CoB, Co 2 B, FeB and Fe 2 B compounds were found in a narrow scan of the pre-etching samples. When the etching was performed in Example 1, all of the above-mentioned compound intensities were decreased as compared with the samples before the etching, but when the etching was performed in Example 3, the strength of the metal boride (CoB, Co 2 B, FeB and Fe 2 B) And the intensity of boron oxide (B 2 O 3 ) was increased.
In addition, the CoFeB thin films of Examples 1 and 3 were analyzed by XPS (X-ray photoelectron spectroscopy, ThermoScientific K-alpha) which was narrowly scanned with C 1 S of the etched CoFeB thin films. The results are shown in FIG.
As shown in FIG. 16, it was confirmed that as the concentration of CH 3 COOH was increased, the intensity of the compound composed of C was increased as in Example 3. This result shows that the thin film layer formed on the CoFeB thin film under the high concentration of CH 3 COOH mainly consists of C x H y species because the sputtering effect is low.
While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments, It will be apparent that the scope is not limited. Accordingly, the actual scope of the present invention will be defined by the appended claims and their equivalents.
Claims (6)
(b) plasmaizing a mixed gas containing 20 vol% to 80 vol% of acetic acid gas and 20 vol% to 80 vol% of an inert gas; And
(c) etching the magnetic thin film masked in step (a) using the plasma generated in step (b).
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| KR980006194A (en) | 1996-06-13 | 1998-03-30 | 우성일 | Etching Method of Transition Metal Thin Film |
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