KR101596329B1 - Apparatus and method for performing plasma enhanced atomic layer deposition employing very high frequency - Google Patents

Abstract

The present invention relates to a device and a method for performing plasma enhanced atomic layer deposition (PE-ALD) by using a very high frequency (VHF). According to an embodiment of the present invention, an atomic layer deposition device comprises: a chamber providing a place in which a process is performed; a substrate support portion supporting a substrate in the chamber; a gas supply portion supplying a gas to the chamber; an exhaust portion exhausting the gas from the chamber; a plasma generating portion installed in the chamber to generate plasma in the chamber; and a VHF power source applying a signal of a VHF band to the plasma generating portion. Therefore, the atomic layer deposition device improves a deposition rate and thin film density by the PE-ALD.

Description

TECHNICAL FIELD The present invention relates to a PE-ALD apparatus and a method using a VHF,

The present invention relates to an apparatus and a method for performing PE-ALD (Plasma Enhanced Atomic Layer Deposition) using VHF (Very High Frequency).

Atomic Layer Deposition (ALD) processes are being studied to deposit thin films on an atomic layer basis. The atomic layer deposition process has better step coverage than the conventional chemical vapor deposition (CVD) process and can deposit a thin film having a uniform thickness over a wide area, Has been gaining great popularity in the manufacture of semiconductor devices.

Atomic layer deposition processes are classified into thermal ALD and plasma enhanced ALD (PE-ALD) depending on the reactants used in the process. The thermal atomic layer deposition provides a gaseous state of the reactant reacting with the metal precursor material, while the plasma enhanced atomic layer deposition provides the reactant in a plasma state.

Conventional PE-ALD processes typically use a signal having a frequency in the RF band, i.e., 13.56 MHz, to generate plasma. However, the PE-ALD process using the RF band signal has a limitation in the deposition rate and the thin film density, and has a problem in that it can not cope with the manufacture of the semiconductor circuit in which the degree of integration is continuously increased.

It is an object of the present invention to provide an atomic layer deposition apparatus and method for performing a PE-ALD process in which a deposition rate and a thin film density are improved as compared with the prior art.

An atomic layer deposition apparatus according to an embodiment of the present invention includes a chamber for providing a space in which a process is performed; A substrate support for supporting the substrate within the chamber; A gas supply part for supplying gas to the chamber; An exhaust unit for exhausting the gas in the chamber; A plasma generator installed in the chamber to generate plasma in the chamber; And a VHF power source for applying a signal of a VHF (Very High Frequency) band to the plasma generator.

The gas supply unit may supply a metal precursor gas, a plasma source gas, or a purge gas to the chamber.

Wherein the gas supply unit supplies the metal precursor gas for a predetermined first time after the substrate is disposed in the chamber by a predetermined first flow rate, and supplies the purge gas to a predetermined second flow rate , Supplying the plasma source gas by a predetermined third flow rate for a predetermined third time, and supplying the purge gas by the second flow rate for the second time.

Wherein the plasma generating unit includes: an upper electrode and a lower electrode that are disposed to face each other with the substrate therebetween and form an electric field in the chamber; And a coil installed on the upper side or the side of the chamber to form an electromagnetic field in the chamber; Or the like.

The VHF power supply may apply a signal having a frequency of 30 to 300 MHz to the plasma generator.

And an impedance matching unit connected between the VHF power supply and the plasma generating unit to match the output impedance of the VHF power supply with the input impedance of the plasma generating unit.

The atomic layer deposition apparatus may further include a heating unit installed on the substrate supporting unit to heat the substrate.

The gas supply unit may supply trimethylaluminum (TMA), Al (CH ₃ ) ₃ , as the metal precursor gas for about 3 seconds or longer by 1 sccm.

The gas supply may supply oxygen to the plasma source gas by 200 sccm for 2 seconds or longer.

The gas supply unit may supply argon with the purge gas for about 6 seconds or longer by 50 sccm.

The VHF power supply may apply a signal having a frequency of 60 MHz to the plasma generator.

The heating unit may heat the substrate to 150 to 200 ° C.

According to an aspect of the present invention, there is provided an atomic layer deposition method including: supplying a metal precursor gas to a chamber in which a substrate is disposed; Purging the chamber by supplying purge gas to the chamber; Applying a VHF band signal to a plasma generation unit installed in the chamber while supplying a plasma source gas to the chamber; And purging the chamber by supplying the purge gas to the chamber.

The step of applying the signal of the VHF band may include: applying a signal having a frequency of 30 to 300 MHz to the plasma generation unit.

The step of supplying the metal precursor gas may comprise: supplying trimethylaluminum to the chamber by 1 sccm for 3 seconds or longer.

The step of applying a signal in the VHF band while supplying the plasma source gas may comprise: supplying oxygen to the chamber for 200 sccm for 2 seconds or longer.

The step of applying a signal in the VHF band while supplying the plasma source gas may include: applying a signal having a frequency of 60 MHz to the plasma generation unit.

The purging of the chamber may comprise: supplying argon to the chamber for a time of 6 seconds or longer, by 50 sccm.

The atomic layer deposition method may further include heating the substrate to a predetermined temperature before supplying the metal precursor gas.

The step of heating the substrate to a predetermined temperature may include: heating the substrate to 180 ° C.

According to the embodiment of the present invention, the deposition rate and the thin film density by the PE-ALD process can be improved as compared with the prior art.

According to the embodiment of the present invention, the productivity of the semiconductor process can be improved by improving the deposition rate and the thin film density by the PE-ALD process.

1 is a schematic diagram of an atomic layer deposition apparatus according to an embodiment of the present invention.
2 is a diagram illustrating a process of providing a process gas and a VHF signal according to an embodiment of the present invention.
3 is an exemplary flow diagram of an atomic layer deposition method in accordance with an embodiment of the present invention.
FIG. 4 is a graph comparing the film deposition rate according to an embodiment of the present invention using a VHF signal with a film deposition rate according to a comparative example using an RF signal.
FIGS. 5 and 6 are XRR analysis graphs showing thin film densities of the comparative examples using RF signals and thin film densities of the examples using VHF signals, respectively.

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

1 is a schematic diagram of an atomic layer deposition apparatus 10 according to an embodiment of the present invention.

1, the atomic layer deposition apparatus 10 includes a chamber 110, a substrate support 120, a gas supply unit 130, an exhaust unit 140, a plasma generation unit 150, and a VHF power source 160 < / RTI >

The chamber 110 provides a space in which the process is performed. The substrate support 120 supports the substrate S in the chamber 110. The gas supply unit 130 supplies gas to the chamber 110. The exhaust unit 140 discharges gas in the chamber 110. The plasma generating unit 150 is installed in the chamber 110 to generate plasma in the chamber 110. The VHF power supply 160 applies a VHF (Very High Frequency) signal to the plasma generator 150.

According to an embodiment of the present invention, the gas supply unit 130 may supply a metal precursor gas, a plasma source gas, or a purge gas to the chamber 110. In other words, the gas supply unit 130 can supply various kinds of gases (in particular, the metal precursor gas and the plasma source gas) alternately without supplying them at the same time.

2 is a diagram illustrating a process of providing a process gas and a VHF signal according to an embodiment of the present invention.

Referring to FIG. 2, the gas supply unit 130 may include a substrate 110, a substrate S disposed in the chamber 110, a metal precursor gas introduced into the chamber 110 for a first predetermined time t ₁ , 1 flow rate. Then, the gas supply unit 130 may supply purge gas to the chamber 110 by a second predetermined flow rate for a predetermined second time t ₂ .

Thereafter, the gas supply unit 130 may supply the plasma source gas to the chamber 110 for a predetermined third flow rate for a predetermined third time t ₃ . Then, the gas supply unit 130 may supply the purge gas by the second flow rate for the second time t ₂ .

As described above, the gas supply unit 130 supplies a process gas to the chamber 110 in the order of a metal precursor gas, a purge gas, a plasma source gas, and a purge gas to deposit a thin film of atomic layer unit on the substrate S .

Further, the gas supply unit 130 repeats a cycle a predetermined number of times by supplying the metal precursor gas, the purge gas, the plasma source gas, and the purge gas in one cycle, thereby forming the thin film on the substrate S. It can be deposited to a target thickness.

Referring to FIG. 1 again, the plasma generator 150 receives a signal in the VHF band from the VHF power supply 160 and converts the plasma source gas supplied to the chamber 110 into a plasma state.

According to one embodiment, the plasma generating unit 150 may include an upper electrode and a lower electrode that are installed to face each other with the substrate S therebetween, and form an electric field in the chamber 110. That is, the plasma generator 150 may be a capacitively coupled plasma (CCP) type plasma source. The plasma generating unit 150 shown in FIG. 1 includes an upper electrode 150 disposed on an upper portion of a chamber 110 and a lower electrode (not shown) disposed on a substrate supporting unit 120.

According to another embodiment, the plasma generating unit may include a coil installed on the upper side or the side of the chamber 110 to form an electromagnetic field in the chamber 110. In other words, the plasma generator 150 may be a plasma source of ICP (Inductively Coupled Plasma) type.

According to an embodiment, the plasma generator may include both a coil, which is an ICP type plasma source, and a parallel plate electrode, which is a CCP type plasma source.

The VHF power supply 160 supplies a signal in the VHF band to the plasma generator 150 to supply power required for plasma generation.

According to an exemplary embodiment of the present invention, the VHF power supply 160 may apply a signal having a frequency of 30 to 300 MHz to the plasma generator 150, , 13.56 MHz), various values can be used without being limited to 30 to 300 MHz.

Referring to FIG. 2, the VHF power supply 160 may supply a VHF band signal to the plasma generator 150 while the plasma source gas is supplied to the chamber 110. Accordingly, the signal of the VHF band may be applied to the plasma generator 150 during the third time.

1, the atomic layer deposition apparatus 10 is connected between a VHF power supply 160 and a plasma generation unit 150 and is connected to the output impedance of the VHF power supply 160 and the output impedance of the plasma generation unit 150 And an impedance matching unit 170 for matching the input impedance.

The atomic layer deposition apparatus 10 may be provided on the substrate S and may be a shower head for uniformly supplying the plasma generated by the plasma generation unit 150 onto the substrate S. [ (180).

Although not shown in FIG. 1, the atomic layer deposition apparatus 10 may further include a heating unit installed on the substrate supporting unit 120 to heat the substrate S. The heating unit may achieve a processing temperature for forming a thin film on the substrate S by maintaining or adjusting the substrate S at a predetermined temperature during the process.

The exhaust unit 140 may discharge gas or reaction by-products remaining in the chamber 110 by using a pump or the like, out of the chamber. Also, the exhaust unit 140 may adjust the pressure in the chamber to a predetermined pressure during the process.

According to an embodiment of the present invention, the gas supply unit 130 may supply trimethylaluminum (TMA) or Al (CH ₃ ) ₃ to the chamber 110 as a metal precursor gas. The gas supply unit 130 may supply oxygen (O ₂ ) to the chamber 110 as a plasma source gas. Also, the gas supply unit 130 may supply argon (Ar) to the chamber 110 as a purge gas.

Accordingly, the atomic layer deposition apparatus 10 can deposit an aluminum oxide (Al ₂ O ₃ ) thin film on the substrate S on an atomic layer basis.

3 is an exemplary flow diagram of an atomic layer deposition method 20 according to an embodiment of the present invention.

The atomic layer deposition method 20 for depositing the metal oxide thin film on the substrate S by atomic layer can be performed using the atomic layer deposition apparatus 10 according to the embodiment of the present invention described above.

3, the atomic layer deposition method 20 includes a step S210 of supplying a metal precursor gas to a chamber 110 in which a substrate S is disposed, a purge gas A step S220 of purging the chamber 110 by supplying a plasma source gas to the chamber 110 and a signal of a VHF band to the plasma generating unit 150 installed in the chamber 110 S230), and purging the chamber 110 by supplying the purge gas to the chamber 110 (S240).

The atomic layer deposition method 20 may repeat the cycle of steps S210 to S240 described above one cycle at a predetermined number of times to deposit a thin film on the substrate S by a target thickness .

According to one embodiment, the step (S210) of supplying the metal precursor gas may include supplying trimethyl aluminum (TMA) to the chamber 110 for 1 sccm for 3 seconds or longer.

According to one embodiment, the step S230 of applying the signal in the VHF band while supplying the plasma source gas includes supplying oxygen (O ₂ ) to the chamber 110 for 200 sccm for 2 seconds or longer Step < / RTI >

The step of applying the signal of the VHF band (S230) may include applying a signal having a frequency of 30 to 300 MHz to the plasma generator 150.

Specifically, the step of applying the signal of the VHF band (S230) may include a step of applying a signal having a frequency of 60 MHz to the plasma generation unit 150. [

According to one embodiment, purging the chamber 110 (S240) may include supplying argon (Ar) to the chamber 110 for about 6 seconds or longer, by 50 sccm.

According to an embodiment of the present invention, the atomic layer deposition method 20 may further include heating the substrate S to a predetermined temperature before supplying the metal precursor gas (S210).

The step of heating the substrate S to a predetermined temperature may include heating the substrate S to 150 to 200 ° C, specifically to 180 ° C.

Hereinafter, a process of depositing a metal oxide thin film on a substrate using a PE-ALD process using a VHF band signal according to an embodiment of the present invention will be described. Then, a thin film deposition rate and a thin film density are measured using a PE - Comparison with thin film deposition rate and thin film density by ALD process.

In this embodiment, a p-type Si wafer was used as a substrate for atomic layer deposition of a metal oxide thin film. During the process, the temperature of the substrate was maintained at 180 DEG C, and the pressure in the chamber was maintained at 24 mTorr.

In order to atomically deposit aluminum oxide (Al ₂ O ₃ ) on the substrate, trimethyl aluminum (TMA) was used as a metal precursor, and oxygen (O ₂ ) was used as a source gas for forming a plasma. Then, argon (Ar) was used as a purge gas for purging the chamber.

First, trimethyl aluminum gas was supplied to the chamber for 1 sccm for 3 seconds to provide a metal precursor to the substrate. Thereafter, the chamber was purged by supplying argon gas to the chamber by 50 sccm for 6 seconds.

Then, in order to form a metal oxide thin film from the metal precursor adsorbed on the substrate, a 60 MHz VHF signal is supplied to the chamber while oxygen gas is supplied to the chamber for 1 second by 200 sccm in the first embodiment of the present invention , Trimethylaluminum gas was reacted with oxygen plasma. Thereafter, the chamber was purged by supplying argon gas to the chamber by 50 sccm for 6 seconds.

The thin film forming cycle was repeated 100 times, and then the thickness of the aluminum oxide thin film was measured with an Elli-SE-F apparatus manufactured by Ellipso Technology, and the measured thickness was divided by 100 to calculate the thickness of the thin film deposited per cycle .

Also, in the second and third embodiments of the present invention, oxygen gas was supplied to the chamber at 200 sccm for 3 seconds and 5 seconds, respectively, and the rest of the procedure was carried out in the same manner as in the first embodiment. Then, RF signals of 13.56 MHz were supplied to the chamber according to the first to third comparative examples, and the remaining processes were performed in the same manner as in the first to third embodiments.

FIG. 4 is a graph comparing the film deposition rate according to an embodiment of the present invention using a VHF signal with a film deposition rate according to a comparative example using an RF signal.

Referring to FIG. 4, in the first to third embodiments in which an aluminum oxide (Al ₂ O ₃ ) thin film is deposited on a Si substrate by a PE-ALD process using a signal in the VHF band, It can be seen that the thickness of the thin film to be grown per cycle (i.e., the thin film deposition rate) is larger than that of the first to third comparative examples.

The first to third comparative examples in which the oxygen plasma generated using the RF band signal is exposed to the metal precursor TMA for 1 second, 3 seconds, and 5 seconds, respectively, and the oxygen plasma generated using the signal in the VHF band The TMA deposition rates according to the first to third embodiments were 1 second, 3 seconds, and 5 seconds, respectively, as shown in Table 1 below.

Exposure time (s) Thin film deposition rate (Å / cycle) RF VHF One 2.19 2.52 3 2.32 2.67 5 2.313 2.7

FIGS. 5 and 6 are XRR analysis graphs showing thin film densities of the comparative examples using RF signals and thin film densities of the examples using VHF signals, respectively.

As a result of the XRR analysis, the density of the aluminum oxide thin film deposited using the RF signal and the aluminum oxide thin film deposited using the VHF signal were 3.11 g / cm ³ and 3.26 g / cm ³ , respectively, It was confirmed that the embodiment can obtain a thin film having a density of about 5% as compared with the comparative example using RF signals.

In the above, an embodiment of the present invention for atomically depositing a metal oxide thin film on a substrate in a PE-ALD process using a VHF band signal has been described. According to the embodiment of the present invention, the thin film deposition rate and the thin film density can be improved and the productivity of the semiconductor process can be improved as compared with the prior art using the RF band signal.

While the present invention has been described with reference to the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. Those skilled in the art will appreciate that various modifications may be made to the embodiments described above. The scope of the present invention is defined only by the interpretation of the appended claims.

10: atomic layer deposition apparatus
110: chamber
120:
130: gas supply unit
140:
150: plasma generator
160: VHF power supply
170: Impedance matching portion
180: Shower head

Claims (20)

A chamber for providing a space in which the process is performed;
A substrate support for supporting a substrate within the chamber;
A gas supply unit for supplying a metal precursor gas, a plasma source gas, and a purge gas to the chamber;
An exhaust unit for exhausting the gas in the chamber;
A plasma generator installed in the chamber to generate plasma in the chamber; And
A VHF power supply for applying a VHF (Very High Frequency) signal to the plasma generator;
/ RTI >
The gas-
The metal precursor gas trimethylaluminum (Trimethylaluminum (TMA), Al ( CH 3) 3) by supplying 1 sccm for 3 seconds or longer than the time by,
Supplying oxygen to the plasma source gas by 200 sccm for 2 seconds or longer,
Argon was supplied as the purge gas for about 6 seconds or longer by 50 sccm,
Wherein the VHF power source applies a signal having a frequency of 60 MHz to the plasma generating unit. delete delete The method according to claim 1,
Wherein the plasma generator comprises:
An upper electrode and a lower electrode provided to face each other with the substrate interposed therebetween to form an electric field in the chamber; And
A coil installed on the upper side or the side of the chamber to form an electromagnetic field in the chamber;
≪ / RTI > delete The method according to claim 1,
And an impedance matching unit connected between the VHF power supply and the plasma generating unit to match an output impedance of the VHF power supply with an input impedance of the plasma generating unit. The method according to claim 1,
And a heating unit installed on the substrate supporting unit to heat the substrate. delete delete delete delete 8. The method of claim 7,
Wherein the heating unit heats the substrate to 150 to 200 ° C. Supplying a metal precursor gas to a chamber in which the substrate is disposed;
Purging the chamber by supplying purge gas to the chamber;
Applying a VHF band signal to a plasma generation unit installed in the chamber while supplying a plasma source gas to the chamber; And
Purging the chamber by supplying the purge gas to the chamber;
Lt; / RTI >
Wherein the step of supplying the metal precursor gas comprises:
And supplying trimethylaluminum to the chamber for 1 sccm for 3 seconds or longer,
The step of applying a signal in the VHF band while supplying the plasma source gas comprises:
Supplying oxygen to the chamber by 200 sccm for 2 seconds or longer; And
And applying a signal having a frequency of 60 MHz to the plasma generator,
Purging the chamber comprises:
And supplying argon into the chamber at a rate of 50 sccm for 6 seconds or longer. delete delete delete delete delete 14. The method of claim 13,
Further comprising heating the substrate to a predetermined temperature before supplying the metal precursor gas. 20. The method of claim 19,
The step of heating the substrate to a predetermined temperature comprises:
And heating the substrate to 180 < 0 > C.

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