Korean Patent Application No. 10-2016-0138587, filed on Oct. 24, 2016, in the Korean Intellectual Property Office, and entitled: “Method of Atomic Layer Etching and Method of Fabricating Semiconductor Device Using the Same,” is incorporated by reference herein in its entirety.
Embodiments relate to a method of atomic layer etching and a method of fabricating a semiconductor device using the same.
With the high integration of semiconductor devices, an extremely fine etching process is required in semiconductor manufacturing processes. Accordingly, an atomic layer etching process in which an atomic layer-level etching is performed may be desirable.
The embodiments may be realized by providing a method of atomic layer etching, the method including providing a layer including atomic layers each having first atoms and second atoms, the second atoms being different from the first atoms; and sequentially removing each of the atomic layers, wherein removing each of the atomic layers includes providing a first etching gas that reacts with the first atoms such that the first etching gas is adsorbed on the first atoms; purging the first etching gas that is not adsorbed on the first atoms; removing the first atoms on which the first etching gas is adsorbed; providing a second etching gas that reacts with the second atoms such that the second etching gas is adsorbed on the second atoms; purging the second etching gas that is not adsorbed on the second atoms; and removing the second atoms on which the second etching gas is adsorbed.
The embodiments may be realized by providing a method of atomic layer etching, the method including providing a layer that includes atomic layers each having two or more kinds of atoms; and sequentially removing each of the atomic layers, wherein removing each of the atomic layers includes sequentially removing each kind of the atoms, sequentially removing each kind of atom including providing an etching gas that reacts with each kind of atom such that the etching gas is adsorbed on the atoms, purging the etching gas that is not adsorbed on the atoms, and bombarding a surface of the atomic layer with ions or radicals of an inert gas.
The embodiments may be realized by providing a method of fabricating a semiconductor device, the method including providing a wafer; providing a layer on the wafer such that the layer includes atomic layers each having first atoms and second atoms, the second atoms being different from the first atoms; and sequentially removing each of the atomic layers from the wafer, wherein sequentially removing the each of the atom layers includes providing a first etching gas onto the wafer to be adsorbed on the first atoms; purging the first etching gas which is not adsorbed on the first atoms; removing from the wafer the first atoms on which the first etching gas is adsorbed; providing a second etching gas onto the wafer to be adsorbed on the second atoms; purging the second etching gas which is not adsorbed on the second atoms; and removing from the wafer the second etching gas on which the second etching gas is adsorbed.
The embodiments may be realized by providing a method of fabricating a semiconductor device, the method including providing a wafer; providing a plurality of stacked atomic layers on the wafer, each atomic layer of the stacked atomic layers having two or more different kinds of atoms; and sequentially removing the atomic layers from the plurality of stacked atomic layers, wherein sequentially removing the atomic layers from the plurality of stacked atomic layers includes repeatedly sequentially removing the different kinds of atoms from each atomic layer, sequentially removing the different kinds of atom from each atomic layer including repeating, a number of times equal to the number of different kinds of atoms, a cycle of providing a gas that has an affinity to one kind of the two or more different kinds of atoms such that the gas is adsorbed on the one kind of atom, purging portions of the gas that are not adsorbed on the one kind of atom, and bombarding the one kind of atom having the gas adsorbed thereon with ions or radicals of an inert gas.
Features will be apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which:
It will be hereinafter described in detail exemplary embodiments in conjunction with the accompanying drawings.
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The first energy may be greater than a binding energy between the first etching gas 212 and the first atom 210 and less than a binding energy between the atomic layers 201 to 204. As a result, no peeling may occur between the atomic layers 201 to 204, and other unwanted portions may not be physically etched by an excessive energy.
The ions or radicals of the inert gas may be created from, e.g., inductively coupled plasma, capacitively coupled plasma, wave heated plasma, electron cyclotron resonance, a neutral beam source, or an ion beam source.
Remaining byproduct gases may be purged when the removal step S23 of the first atoms 210 is terminated.
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The first and second atoms 210 and 220 may be different from each other, and chemical reaction formulas related thereto may be different from each other and thus the first and second energies may also be different from each other. The second energy may be greater than a binding energy between the second etching gas 222 and the second atom 220 and less than a binding energy between the atomic layers 201 to 203. As a result, no peeling may occur between the atomic layers 201 to 203, and other unwanted portions may not be physically etched by an excessive energy.
A different kind of atom may make its chemical reaction formula different, and an etching gas or binding reaction energy may be differently changed. If a single etching gas were to be applied or various etching gases were to be simultaneously supplied so as to remove a layer including two or more kinds of atoms, some atoms could be hardly or barely removed or an excess energy could be applied to prevent some atoms from being hardly removed. The aforementioned cases could cause severe etching damage. The method according to an embodiment may help minimize or eliminate etching damage by suitably changing the etching gas and energy in accordance with the kind of atom.
A determination step S30 may be made to determine whether the layer 200 is etched to a desired thickness (after performing a cycle 20) by changing the etching gases. If the layer 200 is not etched to a desired thickness, the cycle S20 may be repeated until the layer 20 is etched to the desired thickness.
In an implementation, the layer 200 may be, e.g., a silicon nitride (Si3N4) layer, the first atom 210 may be, e.g., silicon (Si), the second atom 220 may be, e.g., nitrogen (N), the first etching gas 212 may be, e.g., nitrogen trifluoride (NF3), and the second etching gas 222 may be, e.g., methane (CH4). The nitrogen trifluoride (NF3) may be supplied to be adsorbed on the silicon to constitute a monolayer. The nitrogen trifluoride (NF3) may be decomposed into nitrogen (N) and fluorine (F) by bombardment of ions or radicals of an inert gas having a first energy. At the same time, the fluorine may combine with the silicon to produce silicon tetraflouride (SiF4), which evaporates, thereby removing the silicon atoms. The methane (CH4) may be adsorbed on the nitrogen to constitute a monolayer. Due to bombardment of ions or radicals of an inert gas having a second energy, the methane (CH4) may combine with the nitrogen to produce hydrogen cyanide (HCN), which evaporates, thereby removing the nitrogen atoms.
In an implementation, the layer 200 may be, e.g., a silicon oxide (SiO2) layer, the first atom 210 may be, e.g., silicon (Si), the second atom 220 may be, e.g., oxygen (O), the first etching gas 212 may be, e.g., nitrogen trifluoride (NF3), and the second etching gas 222 may be, e.g., methane (CH4). A principle of removing the silicon atoms may be the same as that discussed above. The methane (CH4) may be supplied and adsorbed on the oxygen to constitute a monolayer, and the methane (CH4) may be decomposed into carbon and hydrogen by bombardment of ions or radicals of an inert gas having a second energy. At the same time, the carbon may combine with the oxygen to produce carbon dioxide (CO2), which evaporates (e.g., is a gas), thereby removing the oxygen atom.
In an implementation, the layer 200 may be, e.g., a molybdenum disulfide (MoS2) layer, the first atom 210 may be, e.g., molybdenum (Mo), the second atom 220 may be, e.g., sulfur (S), the first etching gas 212 may be, e.g., carbon monoxide (CO), and the second etching gas 222 may be, e.g., hydrogen (H2). The carbon monoxide (CO) may be supplied and adsorbed on the molybdenum (Mo), and the molybdenum (Mo) may combine with the carbon monoxide to produce molybdenum hexacarbonyl (Mo(CO)6), which evaporates, thereby removing the molybdenum (Mo). The hydrogen may be supplied and adsorbed on the sulfur (S), and the sulfur (S) may combine with the sulfur (S) to produce hydrogen sulfide (H2S), which evaporates, thereby removing the sulfur (S).
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The gas supply elements 31 to 34 may include gas supply lines 31 and 32, a flow controller 32, and a gas supply unit 34. The gas supply lines 31 and 32 may provide various gases to top and/or side portions of the chamber 10. For example, the gas supply lines 31 and 32 may include a vertical gas supply line 31 penetrating the cover 11 and/or a horizontal gas supply line 32 penetrating the side portion of the chamber 10.
The vertical and horizontal gas supply lines 31 and 32 may directly supply gases into the plasma space P of the chamber 10. The various gases may include an etching gas, a purge gas, and a bombarding gas. For example, the purge gas may include at least one of argon (Ar), helium (He), neon (Ne), and xenon (Xe). The bombarding gas may include at least one of argon (Ar), neon (Ne), and xenon (Xe). The flow controller 33 may control supply amounts of gases introduced through the gas supply lines 31 and 32 into the chamber 10. The gas supply unit 34 may store the etching, purge, and bombarding gases, and the stored gases may be supplied to the gas supply lines 31 and 32.
A wafer W may be placed on the electrostatic chuck 40. The electrostatic chuck 40 may include a temperature controller 41 therein. A temperature of the electrostatic chuck 40 may be controlled by the temperature controller 41, which may include a heater and/or a cooler and control. The electrostatic chuck 40 may be supported by and may rotate on a supporter 42.
The bias elements 51 to 53 may include an electrode plate 51, a bias RF matcher 52, and a bias RF generator 53. The electrode plate 51 may attract radicals or ions included in plasma produced within the chamber 10. The bias RF matcher 52 may match impedance of bias RF by controlling bias voltage and bias current applied to the electrode plate 51. The bias RF generator 53 may generate a RF signal. For example, the RF signal may have a frequency of about 13.56 MHz. The bias RF generator 53 and the source RF generator 25 may be synchronized or non-synchronized with each other through a synchronizer 90.
The gas exhaust elements 61 and 62 may include a gas exhaust line 61 and a gas exhaust pump 62. The gas exhaust pump 62 may exhaust gasses through the gas exhaust line 61 from the chamber 10.
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In an implementation, an atomic layer etching may be performed on the layer 200 including two different kinds of atoms 210 and 220. In an implementation, the layer 200 may include more than two kinds of atoms. For example, an etching target layer may include three kinds of atoms.
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In an implementation, the first to third atoms 310, 320, and 330 may be different from each other. The first to third etching gases 312, 322, and 332 may be different from each other, or two of the first to third etching gasses 312, 322, and 332 may be the same. In an implementation, chemical equations or reactions may be so different that the first to third energies may be different from each other.
In an implementation, the layer 300 may be, e.g., a silicon oxynitride (SiON) layer, the first atom 310 may be, e.g., silicon, the second atom 320 may be, e.g., oxygen, the third atom 330 may be, e.g., nitrogen, the first etching gas 312 may be, e.g., nitrogen trifluoride (NF3), and the second and third etching gases 322 and 332 may be, e.g., methane (CH4).
In an implementation, an atomic layer etching may be performed on a layer including three kinds of atoms. In an implementation, if n (where, n is greater than three) kinds of atoms are included, n kinds of etching gases may be supplied to a cyclic process for etching one atomic layer. In an implementation, some of the etching gases may be the same, because energies required for corresponding reactions may be different, and process conditions may be different from each other. As atoms are removed by using appropriate etching gases or changing process conditions, it may be possible to minimize or eliminate etching damages and to precisely remove atoms included in layers.
By way of summation and review, various layers constituting a semiconductor device may include, e.g., a layer including one kind of atom, such as a single crystal silicon layer, a polysilicon layer, and a copper layer; and a layer including two or more kinds of atoms, such as a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a metal oxide layer, a metal nitride layer, and a silicon-germanium layer.
A semiconductor device may be fabricated to have high integration and excellent performance through a semiconductor manufacturing process to which the present atomic layer etching method is applied. As one example, an etching target layer may be formed on a semiconductor substrate, and a mask pattern may be formed on the etching target layer. The atomic layer etching method may be employed to etch the etching target layer.
In an atomic layer etching method according to exemplary embodiments, a layer including two or more kinds of atoms may be etched for each of atomic layers by sequentially supplying etching gases which are suitable for etching various kinds of atoms, respectively. Accordingly, the various kinds of atoms may be sequentially etched such that etching damage may be minimized or eliminated due to no need to use excessive energy and a precise etching may be performed on each of atomic layers.
As a result, when an atomic layer etching method according to an embodiment is applied to a semiconductor manufacturing process, a high-performance, highly-integrated semiconductor device may be achieved.
The embodiments may provide a method of atomic layer etching capable of minimizing etching damage and precisely etching a layer including two or more kinds of atoms.
The embodiments may provide a method of fabricating a highly integrated semiconductor memory device having excellent performance.
Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.
Number | Date | Country | Kind |
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10-2016-0138587 | Oct 2016 | KR | national |