KR101837370B1 - Method for deposition of amorphous carbon layer using plasmas - Google Patents

Method for deposition of amorphous carbon layer using plasmas Download PDF

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KR101837370B1
KR101837370B1 KR1020160014414A KR20160014414A KR101837370B1 KR 101837370 B1 KR101837370 B1 KR 101837370B1 KR 1020160014414 A KR1020160014414 A KR 1020160014414A KR 20160014414 A KR20160014414 A KR 20160014414A KR 101837370 B1 KR101837370 B1 KR 101837370B1
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carbon film
boron
precursor
film
plasma
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KR20170093003A (en
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양재영
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주식회사 테스
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    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
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    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
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    • H01L21/02115—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates characterised by the material of the layer the material being carbon, e.g. alpha-C, diamond or hydrogen doped carbon
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    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
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    • H01L21/02107—Forming insulating materials on a substrate
    • H01L21/02109—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates
    • H01L21/02205—Forming insulating materials on a substrate characterised by the type of layer, e.g. type of material, porous/non-porous, pre-cursors, mixtures or laminates the layer being characterised by the precursor material for deposition
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    • H01L21/02225—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer
    • H01L21/0226—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process
    • H01L21/02263—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase
    • H01L21/02271—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition
    • H01L21/02274—Forming insulating materials on a substrate characterised by the process for the formation of the insulating layer formation by a deposition process deposition from the gas or vapour phase deposition by decomposition or reaction of gaseous or vapour phase compounds, i.e. chemical vapour deposition in the presence of a plasma [PECVD]
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    • H01L21/02436—Intermediate layers between substrates and deposited layers
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Abstract

The present invention relates to a method of depositing an amorphous carbon film using a plasma in a semiconductor process, and more particularly, to a method for depositing an amorphous carbon film using plasma in a semiconductor process, in which a precursor material is intermittently The present invention relates to a deposition method of an amorphous carbon film having an increased etch selectivity by forming a multilayer film structure in which a carbon film doped with dopant and a carbon film doped with no dopant are alternately deposited through a circulation injection method.

Description

[0001] The present invention relates to a method for depositing an amorphous carbon layer using plasma,

The present invention relates to a method of depositing an amorphous carbon film using a plasma in a semiconductor process, and more particularly, to a method for depositing an amorphous carbon film using plasma in a semiconductor process, in which a precursor material is intermittently The present invention relates to a deposition method of an amorphous carbon film having an increased etch selectivity by forming a multilayer film structure in which a carbon film doped with dopant and a carbon film doped with no dopant are alternately deposited through a circulation injection method.

For example, a multilayer insulating film (oxide film, nitride film) is laminated on a substrate in 32 layers (64 layers) and a layer of a multi-layer insulating film After selectively removing only the nitride film, a gate material of the transistor is deposited to form a device.

At this time, in order to selectively remove only the nitride film from the multilayer insulating film (O / N), a narrow and long hole (contact hole, plug) that vertically penetrates the stacked insulating film must be formed.

For this, a carbon film hard mask is deposited on the insulating film and etched. In the future, it is required that the corrosion resistance of the hard mask is increased as the number of layers of the insulating film is continuously increased to 48, 64,

In order to increase the corrosion resistance of the hard mask, a method of increasing the thickness of the thin film or increasing the etching selectivity of the thin film is mainly used. The method of increasing the thickness of the thin film is a pattern aspect ratio (A / R; aspect ratio is increased to make it difficult to pattern the lower layer film. Therefore, in recent years, there has been a tendency that technology development is performed by increasing the etching selectivity of the thin film.

Thus, in the following [Prior Art Document 1], there is disclosed a technique for increasing the etch selectivity by implanting a dopant into an amorphous carbon film hard mask. However, the hard mask doped with the dopant into the entire thin film is etched There is a problem that removal is difficult.

In order to solve the problems of the prior art document [1], a technique of alternately forming a doped and a non-doped thin film in [Prior Art Document 2] is disclosed.

However, in the case of [Prior Art Document 2] described above, since a method of turning on / off the plasma generating power for forming the amorphous carbon film hard mask in a multi-layered structure is used, in the repeated plasma ignition, Arcing phenomenon due to current flow or irregular flickering of the plasma are frequently caused, resulting in process instability.

As described above, since the thin film is difficult to be formed due to difficulty in the deposition process by the intermittent plasma generating power source, the sidewall roughness appearing on the side wall of the pattern due to the difference in the etching rate between the respective layers in the etching process, The defect of the same shape is often transferred to the etching pattern of the underlying film.

 Therefore, these methods are still inadequate to cope with an increase in the etch selectivity of the amorphous carbon film hard mask material more seriously requested in recent years.

[Prior Art Document 1] Japanese Laid-Open Patent JP 2013-524508 (published on Mar. 6, 2013)

[Prior Art Document 2] Korean Published Patent Application No. KR 2011-0063386 (published on June 10, 2011)

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above, and it is an object of the present invention to provide an amorphous carbon film which is alternately doped with a dopant- A deposition method of an amorphous carbon film capable of remarkably increasing the etch selectivity by forming a multilayer film in which layers are alternately deposited by a method of interrupting supply and interruption of dopant precursors, instead of a method of intermittently controlling the plasma And a hard mask material using the same.

It is another object of the present invention to provide a method of forming an undoped thin film as a lift-off layer before deposition of a multilayer film, And a hardmask material using the same. The present invention also provides a method for depositing an amorphous carbon film and a hard mask material using the same, wherein a hard mask is more easily removed after etching by forming a multi-layer structure in which layers are alternately deposited on the upper layer.

According to an aspect of the present invention, there is provided a method of manufacturing a plasma reactor, including: a first step of supplying a hydrocarbon precursor in a plasma reactor to deposit a first carbon film on a substrate; supplying a hydrocarbon precursor and a boron precursor in the reactor A second step of depositing a second carbon film containing boron on the first carbon film, a step of stopping the supply of the boron precursor, and supplying the hydrocarbon precursor to deposit the third carbon film on the second carbon film And a fourth step of repeating the third step and the second step and the third step to form a thin film in which the second carbon film and the third carbon film are alternately stacked on the first carbon film.

In addition, the first to fourth steps are continuously performed, and the supply and stop of the boron precursor are performed by controlling the intermittent opening / closing valve for gas supply, and the plasma generating power applied to the reactor for thin film deposition Is maintained in an ON state.

The first carbon film is an amorphous carbon film containing no boron and serves as a desorption layer, and the first carbon film is deposited thicker than the second carbon film or the third carbon film.

The first carbon film may be deposited to a thickness of 5 to 200 nanometers, and the second carbon film and the third carbon film may be deposited to a thickness of 1 to 20 nanometers.

In order to shorten the intermittent time for supplying and stopping the boron precursor in the second to fourth steps, when the supply of the boron precursor is stopped after the supply of the boron precursor is stopped, the control unit is controlled so as to be reopened before being fully-closed.

As described above, in the method of depositing an amorphous carbon film using plasma according to the present invention, in the deposition of an amorphous carbon film on a substrate by supplying a carbon precursor, intermittent supply and interruption of boron used as a dopant is performed, The etching selectivity ratio can be increased by alternately depositing the deposited thin film and the undoped thin film.

Also, the method of depositing an amorphous carbon film using plasma according to the present invention is characterized in that, in order to perform the above-mentioned alternate deposition, the plasma is kept in a discharged state while interrupting supply and interruption of boron, And thus it is possible to prevent the abnormal rise of the substrate temperature even when the magnitude of the applied power is increased.

The method of depositing an amorphous carbon film using plasma according to the present invention is characterized in that an undoped thin film which is easily chemically removed before deposition of the multilayer film is formed as a desorption layer on a substrate and a boron- The non-doped layers are alternately deposited to form a multi-layered structure, which makes it possible to more easily remove the hard mask material after etching.

The method of depositing an amorphous carbon film using plasma according to the present invention uses a method of intermittently controlling the boron precursor instead of the conventional plasma discharge intermittent method, It is possible to remove the defect of the pattern side wall after the etching despite the difference in the etching rate between the boron-doped thin film and the undoped thin film because the thin film can be deposited at a nanometer level.

1 is a sectional view of a plasma apparatus for depositing an amorphous carbon film using plasma according to the present invention,
FIG. 2 is a process flow diagram for depositing an amorphous carbon film using plasma according to the present invention, FIG.
3 is a schematic view of a boron precursor circulation injection method for depositing an amorphous carbon film using plasma according to the present invention,
FIGS. 4A and 4B are structural diagrams of an amorphous carbon film using plasma according to the present invention. FIG.
FIG. 5 is a graph showing changes in etch selectivity according to the boron content of the amorphous carbon film using the plasma according to the present invention,
FIG. 6A is a graph showing an SIMS (Secondary Ion Mass Spectrometry) analysis graph of an amorphous carbon film using a plasma according to the present invention,
FIG. 6B is a graph showing an FT-IR (Fourier Transform-Infrared) absorbance spectrum of an amorphous carbon film using a plasma according to the present invention,
6C is a graph showing a Raman spectroscopy spectrum of an amorphous carbon film using plasma according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a cross-sectional view of a plasma apparatus for depositing an amorphous carbon film using plasma according to the present invention.

A plasma generating apparatus 1 according to the present invention includes a reactor 2, a showerhead 3, a substrate support 4, a radio frequency (RF) power source 5 and a first electrode 6.

The showerhead 3 is disposed on the upper side inside the reactor 2 and injects the process gas injected through the gas supply line S connected to an external gas supply device into the reactor.

At this time, the first electrode 6 is electrically connected to the high-frequency power source 5 to serve as an electrode for plasma discharge. In the present invention, the showerhead 3 is electrically connected to the first electrode 6 (3a) to function as a single electrode together with the first electrode (6) will be described as an example.

Accordingly, the high-frequency (13.56 MHz) power generated in the high-frequency power source 5 is applied to the inside of the reactor 2 through the showerhead 3.

A substrate supporting part 4 for receiving and supporting the substrate W transferred into the reactor 2 is provided on the lower side of the reactor 2 in opposition to the showerhead 3.

The substrate support 4 may include a temperature control means and may function as a ground electrode and may include a high frequency (RF, e.g., 2 MHz) power source or a direct current DC) power supply to the second electrode (bias electrode).

When the substrate W is carried into the substrate supporting part 4, the inside of the reactor 2 is controlled to a vacuum state by an external vacuum system (not shown), and the process gas is supplied. Then, the high- To form plasma in the reactor (2) between the showerhead (3) and the substrate support part (4).

Since the plasma generating device 1 uses the high frequency power source 5 and the grounding performance is important, the substrate supporting part 4 is composed of a metal heater or a ceramic heater, and a grounding wire is built in the substrate supporting part driving part 9 And may be provided with a separate additional ground line 8 to further enhance the grounding performance.

Also, in the present invention, a high-frequency filter unit 7 optimized for the high-frequency power applied to the showerhead 3 is provided to eliminate signal interference occurring around the reactor 2.

FIG. 2 is a process flow diagram for depositing an amorphous carbon film using plasma according to the present invention, and FIG. 3 is a schematic view of a boron precursor circulation injection method for depositing an amorphous carbon film using plasma according to the present invention.

Hereinafter, a method for depositing an amorphous carbon film using plasma according to the present invention will be described for each of the steps of FIG. 2 and FIG. 3 for convenience of description.

(Step S10: first carbon film deposition through first process gas injection and plasma generation)

2, the substrate W is carried into the substrate supporting part 4 in the reactor 2, and the inside of the reactor 2 is evacuated when the substrate W is seated, And supplies the process gas through the head 3.

At this time, the substrate supporting part 4 is preheated and holds the substrate temperature at a temperature necessary for the deposition process (preferably 300 to 500 ° C) after the substrate W is brought into the chamber.

The process gas is supplied from the outside through the gas supply line S and is injected into the reactor 2 through the showerhead 3.

The process gas contains a hydrocarbon (C x H y ) precursor. In the deposition of the amorphous carbon film, various known hydrocarbon precursors having a benzene ring or a plurality of double bonds as a carbon source may be used singly or as a mixture Can be used.

Since they are mainly present in a liquid state at room temperature, a liquid precursor is vaporized at a predetermined temperature (for example, 60 to 85 ° C) through a vaporizer such as a bubbler (not shown) To the inside of the reactor (2).

In the present invention, the case where C 7 H 14 (methyl-cyclohexane; hereinafter referred to as a first process gas) is used as the hydrocarbon precursor will be described as an example.

The first process gas can easily control the thin film characteristics such as the deposition rate, the etching selectivity, the extinction coefficient, and the stress, and the conventional process gas can be used for the conventional process gases such as toluene (C 7 H 8 ) and ethylbenzene (C 8 H 10 ) There is an advantage that the generation of reaction by-products is small and the pollution can be reduced.

The supply amount of the first process gas may be set in accordance with the process target value such as the thickness and the film quality of the amorphous carbon film to be deposited. In the present invention, the supply amount of the first process gas is 200 to 1000 slm (standard liter per minute) An inert gas such as argon gas (100 to 500 sccm, standard cubic centimeter per minute) and argon gas (100 to 3000 sccm) may be supplied together with the first process gas to stabilize the plasma and improve the thickness and the deposition uniformity .

When the introduction of the substrate W and the supply of the first process gas are completed, high-frequency power is applied to the showerhead 3 above the reactor 2 through the high-frequency power source 5 to generate plasma.

In order to form the amorphous carbon film using the plasma according to the present invention, the RF power is applied in the range of 500 to 2500 Watts to generate plasma, and the process pressure inside the reactor 2 is adjusted to facilitate the plasma discharge It is preferable to set the range to 1 to 10 Torr, but it is obvious that the process conditions can be appropriately changed according to the desired thin film thickness, characteristics, and the like.

Thereafter, an amorphous carbon film (hereinafter referred to as a first carbon film) containing carbon (C) and hydrogen (H) is deposited on the substrate W by dissociating the first process gas using the plasma.

Since the first carbon film does not contain a dopant (boron), the first carbon film can be easily etched by a mixed gas of fluorocarbon (CF 4 , C 4 F 8, etc.) and oxygen (O 2 ) Ashing and lift-off, so that it acts as a lift-off layer.

Therefore, it is preferable that the thickness of the first carbon film is as thick as possible, but it can be changed in conjunction with the doping concentration and thickness of the upper alternate deposition layer to be described later.

Accordingly, in the embodiment of the present invention, the thickness of the first carbon film is controlled to 5 to 200 nanometers (nm), and the second carbon film or the third carbon film is deposited relatively thicker than the thickness of the second carbon film or the third carbon film.

(Step S20: second process gas injection and second carbon film deposition)

When the step S10 is completed, the first carbon film containing no dopant is deposited on the substrate W.

Then, in order to form a multi-layered structure, a dopant is doped into the upper portion of the first carbon film, a separate process gas containing the dopant is additionally supplied into the reactor 2. In the present invention, A boron-containing precursor (hereinafter referred to as a second process gas) is further supplied while the supply of the first process gas is maintained to deposit an amorphous carbon film doped with boron (hereinafter referred to as a second carbon film).

The boron-containing precursor may be a known compound such as diborane (B 2 H 6 ), trimethylboron (B (CH 3 ) 3 ), triethylboron (TEB) Use diborane.

Meanwhile, in the conventional method of forming a multilayered film, a method of separating the doping step and the plasma discharge and stopping at the supply and the stopping point of the dopant precursor when depositing the dopant-doped amorphous carbon film is used.

As described above, in the case of depositing the multilayer film through a plurality of deposition steps, discharge and interruption of the plasma must be repeated, so that the discharge becomes unstable at the time of plasma ignition.

Accordingly, in order to solve the problems of the prior art, in the step S20 of the present invention, the second process gas is controlled to ON / OFF in the reactor 2 in the range of 1000 to 10000 slm according to the doping level. (Hereinafter, referred to as cyclic feed-through) is used in order to sustain the discharge by continuously holding the plasma in the ON state of the high-frequency power.

(Step S30: stop of injecting the second process gas and deposition of the third carbon film)

After the second carbon film is deposited on the first carbon film by supplying the second process gas in step S20, the supply of the second process gas is stopped in step S30.

When the supply of the second process gas is stopped, only the first process gas is supplied into the reactor 2, and the third carbon film containing no boron is deposited using the first process gas.

At this time, as in step S20, the plasma discharge state is continuously maintained in step S30, so that discharge instability due to the interruption and resumption of the plasma ignition can be solved.

(Step S40: Repeat Steps S20 to S30)

When the deposition of the third carbon film is completed in step S30, steps S20 to S30 are repeated to alternately deposit the second carbon film and the third carbon film on the third carbon film in order to form a multilayer structure.

The alternate deposition for forming the multilayer film may be formed by adjusting the thickness and the number of repetitions according to the process target value of the hard mask thin film. In the present embodiment, the repetition times are not limited to 80-150 times.

In the present embodiment, two thin films are alternately (ABAB...) Deposited by repeating the steps S20 to S30 in forming the multilayer film as an example. (For example, ABCABC ...) may be deposited with three or more deposition conditions.

That is, in the case of the step S30, the supply of the second process gas is completely blocked in the present embodiment. However, the present invention is not limited to this, 3 carbon film may be smaller than the second carbon film.

In the case of step S20, the second carbon film may be formed of a plurality of layers having different boron contents by controlling the supply amount or the concentration of the second process gas so as to be changed.

Thus, by varying the supply amount or the concentration of the second process gas in step S20, various multilayer film structures other than the above-described alternate vapor deposition of two or three kinds of thin films can be formed.

As described above, when boron is doped into the amorphous carbon film to increase the etching selectivity of the thin film, boron reacts with fluorine (F), which is a main component of the etching gas, when etching the hard mask, and boron trifluoride 3 ), but it has characteristics that it is not easy to etch because of its low volatility.

Therefore, if the content of boron in the thin film is increased, the etch selectivity is increased due to the corrosion resistance of boron as described above. However, there is a problem that it is difficult to remove the thin film after etching, so there is a limit to increase the content of boron.

Accordingly, in order to increase the etching selectivity of the thin film while reducing the boron content, there has been proposed a method of alternately depositing a boron-doped thin film and an undoped thin film to form a multi-layered hard mask. In this method, (ON / OFF) of the plasma is interrupted when the supply of the plasma is interrupted.

However, when a multi-layer structure is formed while plasma generation is interrupted (ON / OFF), there is a problem that it is difficult to deposit each thin layer thinly due to the characteristics of PECVD having a high deposition rate, and the thickness of the doped thin layer becomes thick There is a problem that it is difficult to remove by etching.

In contrast, according to the present invention, when the doping layer and the non-doped layer are alternately deposited, the discharge of the plasma can be continued to eliminate instability of the plasma discharge, and the thickness of each alternating layer can be formed thin Thereby improving the etch selectivity and facilitating the removal of the hard mask after etching.

That is, when the thickness of the thin film is very thin to several nanometers, the grain size of the thin film becomes smaller than that of the thick film, so that the density of the film becomes very dense and the density increases. Which leads to an increase in rain.

Also, the etch selectivity ratio of the amorphous carbon film hard mask according to the present invention can be further increased by the increase of the etch selectivity due to the boron implantation and the effect of increasing the etch selectivity ratio by realizing the very thin film.

In addition, since the etching selectivity ratio increase effect of the thin film is realized, the amount of boron doped in the thin film can be reduced correspondingly, so that the hard mask can be more easily removed after the etching.

In addition, as described later, when a multilayer structure is formed by repeatedly depositing a very thin film, it is possible to increase the density while forming a thick film as a whole. As a result, the etch selectivity can be more effectively .

In order to alternately deposit a very thin film as described above, the embodiment according to the present invention is characterized in that when supplying or stopping the second process gas, the gas guide member (for example, the opening and closing valve of the gas supply device) (Or intermittent) according to the first intermittent method (hereinafter referred to as first intermittent method).

In this case, since the thickness of each layer is related to the intermittent time, if the intermittent time is reduced, the thickness of each layer can be thinly deposited.

For this purpose, in the present invention, in addition to the case of fully open and completely closed, the valve may be interrupted in a partially open and partially closed manner, (Hereinafter referred to as a second intermittent method) in which the intermittent time is further shortened (i.e., the thickness of the thin film is made thinner) by increasing the response speed.

That is, in an embodiment of the present invention, in addition to the first intermittent mode for circulating the second process gas, a method of completely closing the opening / closing valve after opening the opening / closing valve by 80% or closing the opening by 80% It is possible to control the intermittent time in units of 0.1 second through the second intermittent mode in which the reopening operation is performed before the opening / closing valve is fully opened or before the fully opened state.

In this case, since the circulation injection system and the opening / closing valve opening control method are the same as those described above, the reaction time of the opening / closing valve is controlled in units of 0.5 second, It can be deposited very thinly in a thickness of a meter.

The valve opening / closing method according to the present invention can further adjust the reaction time of the valve by adjusting the opening and closing range of the valve. If necessary, the opening / closing valve can be finely (for example, 5 to 10% The doping concentration in the thin film can be adjusted by continuously supplying the second process gas in a minute amount as in the case of alternating (for example, ABCABC ...) deposition of the three kinds of thin films.

Accordingly, the reaction time of the opening / closing valve can be controlled to be several seconds or less (preferably, 1 second or less) through the intermittent mode as described above. In this embodiment, however, The second carbon film can be ultra-thin deposited to a thickness of 6 to 10 nanometers (nm).

In addition, since the plasma is continuously maintained in a discharged state by using the precursor circulation injection method as described above, the problem of discharge failure at the time of plasma re-ignition, which is caused by controlling the ignition of the plasma at the time of supplying and stopping the process gas, There is an effect that can be solved.

In addition, since there is no discharge failure phenomenon as described above, the temperature rise of the substrate supporting part 4 in the reactor 2 is insignificant. Therefore, the RF power applied for the plasma discharge under the same condition is increased by 20 to 30% As a result, the process margin is increased.

As a result, as described above, the amorphous carbon film hard mask of the multilayer film structure formed by the plasma deposition method of the amorphous carbon film according to the present invention has remarkably improved etch selectivity compared with the conventional one, facilitates removal of the hard mask after etching, The instability of the plasma discharge can be solved and the process margin can be ensured.

(Step S50: multi-layer film deposition completion step)

When the formation of the multilayer structure is completed in step S50, the plasma discharge and the supply of the process gas are stopped, and the substrate W is discharged to the outside of the reactor to complete the deposition process.

The characteristics of the amorphous carbon film using the plasma according to the present invention as described above were analyzed, and the results are described below.

FIGS. 4A and 4B are structural views illustrating the structure of an amorphous carbon film using plasma according to the present invention, using a scanning electron microscope (SEM) and a transmission electron microscope (TEM).

4 (a), the amorphous carbon film using plasma according to the present invention is formed by repeating the deposition process of the second carbon film and the third carbon film 80 times, that is, when 160 layers of alternating layers are formed The thickness of the entire thin film is 1.21 micrometers. In the TEM (right side) photograph of FIG. 4A, the detailed structure is shown. From the left side of the photograph (red box, substrate side) , The top of the thin film).

FIG. 4B is an enlarged view of the TEM photograph of FIG. 4A. The thickness of each layer except for the minimum value and the maximum value from the left side (substrate side) to the right side (thin film upper side) of the photograph is 7.2 nm (3σ = 2.23) It can be seen that a very thin and uniform thin film is deposited as compared with the case of using the conventional PECVD apparatus.

This means that it is possible to constitute a multilayer film by depositing a very thin film which is difficult to realize in the conventional PECVD apparatus by controlling the opening degree of the opening / closing valve for circulating injection of the precursor.

Particularly, the result of the TEM photograph corresponds to the case where the intermittent time of the second process gas is adjusted to 0.5 seconds, and the intermittent time of the second process gas is adjusted to 0.5 seconds or less (in the case of the present invention, Deposition of thin films is also possible.

FIG. 5 is a graph showing changes in etch selectivity depending on the boron content of the amorphous carbon film using the plasma according to the present invention.

As a result of the etching process according to the boron content of the second carbon film, the etching selectivity ratio tends to increase sharply when the boron content is 35% or more, and the etch selectivity ratio to the insulating film at a boron content of 40% : 1 or more, which is remarkably improved as compared with the conventional (3 to 5: 1).

In addition, when the boron content was about 30%, the etching selectivity was about 7: 1, but the removal of the hard mask after etching was good.

Accordingly, it is possible to selectively control the appropriate level of boron content in consideration of the hard mask removal characteristic and the etching selectivity ratio, thereby increasing the process margin.

FIG. 6A is a SIMS (Secondary Ion Mass Spectrometry) analysis graph of an amorphous carbon film using plasma according to the present invention, showing a composition distribution, that is, a concentration (Y-axis) along the depth (X axis) direction of a thin film.

In the single layer graph of FIG. 6A, when the amorphous carbon film using the plasma according to the present invention is formed into a single film structure rather than a multilayer structure, an amorphous carbon film is formed to a thickness of about 1.25 micrometers in the depth direction of the substrate, It can be seen that the concentration is uniformly injected.

The multilayer graph of FIG. 6A shows that the amorphous carbon film using the plasma according to the present invention has a multi-layered structure. When the composition of the thin film is carbon (C), hydrogen (H), and boron (B) As shown in FIG.

It can be seen from the Y-axis that the amorphous carbon film using plasma according to the present invention contains boron as a dopant based on a hydrocarbon (C x H y ) film, and boron is uniformly applied alternately to each layer constituting the multilayer film It can be confirmed that it is injected.

FIG. 6B is a graph showing an infrared spectroscopy (FT-IR) absorption spectrum of an amorphous carbon film using plasma according to the present invention, and the chemical structure of components constituting the thin film can be understood.

The FTIR is a measurement of the absorption of energy corresponding to the vibration and rotation of the molecular skeleton that changes when the infrared light is irradiated on the sample. The position frequency (wavenumber) at which the infrared light is absorbed is determined according to the chemical structure and properties of the sample, Absorption intensity is related to the concentration of constituents.

Therefore, as shown in the upper graph of FIG. 6B, the amorphous carbon film using the plasma according to the present invention has the strongest CH bonds (high wave number, 2858, 2448 cm -1 ) and BH x (1209, 1089 cm -1 ) The bonding is relatively weak in the nature of the dopant implantation, but boron is effectively injected into the thin film through the high peak.

Further, in the lower graph of FIG. 6B, the BH x peak change was tracked with time after the deposition. The A peak immediately after the deposition, the B peak after 24 hours of deposition, and the C peak after 168 hours of deposition.

This indicates that the BH x peak (1209, 1089 cm -1 ) does not significantly change in the region originally monitored in the upper graph of FIG. 6 b despite the environment change over time after deposition. As a result, Is a stable process with little change in film quality over time.

6C is a graph showing a Raman spectroscopy spectrum of an amorphous carbon film using plasma according to the present invention.

Raman spectroscopy employs a large energy source to measure the change in the wavelength of light, which allows the chemical structure of the film to be analyzed.

In FIG. 6C, the X axis represents the energy difference between the incident light and the scattered light, and the Y axis represents the peak intensity, that is, the concentration of the substance.

In general, the amorphous carbon film is analyzed in the region of 800 to 2000 cm -1 . In the graph, the G-peak (~ 1478 cm -1 ) is common in graphite-like materials, , And the D-peak (disordered peak, ~ 1230 cm -1 ) indicates the presence of defect (defect or substitution) in the thin film due to sp3 bonding of carbon.

The D-peak means that a sp3 bond is formed by a plurality of substitution reactions by the injection of boron into the amorphous carbon film, and the G-peak means that the carbon maintains the sp2 bond. Consequently, the amorphous carbon film according to the present invention sp2 and sp3 bonds and has a high film density.

The deposition method of the amorphous carbon film using plasma and the hard mask material using the plasma provided by the present invention can be applied not only to the 3D-NAND memory fabrication process but also to various fields of the semiconductor process. Particularly, It can be used in the definition process of the semiconductor fabrication process such as the related deposition process.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, And improvements are also within the scope of the present invention.

1: Plasma generator 2: Reactor
3: Showerhead 4: Substrate support
5: high-frequency power source 6: first electrode
7: High-frequency filter unit 8: Additional ground electrode
9:

Claims (9)

A first step of supplying a hydrocarbon precursor in a plasma reactor to deposit a first carbon film of a non-doped layer on a substrate;
A second step of supplying a hydrocarbon precursor and a boron precursor in the reactor to deposit a second carbon film of a doping layer containing boron on the first carbon film;
A third step of stopping the supply of the boron precursor and supplying the hydrocarbon precursor to deposit the third carbon film of the undoped layer on the second carbon film; And
And a fourth step of repeating the second step and the third step to form a thin film in which a second carbon film and a third carbon film are alternately stacked on the first carbon film,
Wherein the plasma generating power applied to the reactor continuously during the alternate deposition of the doped layer and the non-doped layer is maintained in an ON state.
The method according to claim 1,
Wherein the first step to the fourth step are continuously performed, and the supplying and stopping of the boron precursor is performed by interrupting the opening / closing valve for gas supply.
delete The method according to claim 1,
Wherein the first carbon film is an amorphous carbon film containing no boron,
Wherein the first carbon film is deposited thicker than the second carbon film or the third carbon film.
The method according to claim 1,
Wherein the first carbon film is a lift-off layer. 2. The method of claim 1, wherein the first carbon film is a lift-off layer.
The method according to claim 1,
The first carbon film is deposited to a thickness of 5 to 200 nanometers,
Wherein each layer of the second carbon film and the third carbon film is deposited to a thickness of 1 to 20 nanometers.
The method according to claim 1,
In the second to fourth steps, in order to shorten the interruption time for supplying and stopping the boron precursor,
Wherein when the supply of the boron precursor is stopped after the supply of the boron precursor is restarted, the opening and closing valve of the gas supply device is controlled to be reopened before being fully-closed.
A first step of supplying a hydrocarbon precursor in a plasma reactor to deposit a first carbon film of a non-doped layer on a substrate;
A second step of supplying a hydrocarbon precursor and a boron precursor in the reactor to deposit a second carbon film of a doping layer containing boron on the first carbon film;
A third step of stopping the supply of the boron precursor and supplying the hydrocarbon precursor to deposit the third carbon film of the undoped layer on the second carbon film; And
And a fourth step of repeating the second step and the third step to form a multilayer film in which a second carbon film and a third carbon film are alternately stacked on the first carbon film,
In the second step, the boron precursor is supplied while changing the supply amount or concentration, and the second carbon film is formed of a plurality of layers having different boron contents depending on the supply state of the boron precursor,
Wherein the plasma generating power applied to the reactor continuously during the alternate deposition of the doped layer and the non-doped layer is maintained in an ON state.
A first step of supplying a hydrocarbon precursor in a plasma reactor to deposit a first carbon film of a non-doped layer on a substrate;
A second step of supplying a hydrocarbon precursor and a boron precursor in the reactor to deposit a second carbon film of a doping layer containing boron on the first carbon film;
A third step of reducing the supply of the boron precursor and depositing a third carbon film of a doping layer having a lower content of boron than the second carbon film on the second carbon film; And
And a fourth step of repeating the second step and the third step to form a multilayer film in which a second carbon film and a third carbon film are alternately stacked on the first carbon film,
Wherein the plasma generating power applied to the reactor continuously during the alternate deposition of the second carbon film and the third carbon film is maintained in an ON state.
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