JP2004124206A - Deposition film forming method and deposited film forming system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the ionization rate of raw material atoms (molecules) and the uniformity of the ion density distribution in the sectional direction of the raw material atoms (molecules) ion beams in ionization deposition. <P>SOLUTION: Deposited films are formed by making rare gas to a meta-stable excited state and acting the gas on the raw material particles, and by bringing the gas in proximity to a supply point (a supply port) of process gas in the flying space of the raw material particles, or while controlling members (electrodes, deposition preventing plates, etc.) arranged on a substrate side to the surface potential 0≥Vp-V. Vp denotes the maximum plasma potential in the flying space of the raw material atoms (molecules) and V denotes the surface potential of the members. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of forming a deposited film and an apparatus for forming a deposited film used for manufacturing various semiconductor devices and the like, and more particularly, to a method of forming a deposited film and a method of ionizing a deposited film on a substrate by ionizing deposited particles. The present invention relates to a film forming apparatus.
[0002]
[Prior art]
The conventional ionization film forming method hits a raw material atom (molecule) flying from an evaporation source toward a substrate on which a film is formed, as typified by ion plating. What is ionized by a high-frequency substrate bias method or the like and is deposited on a substrate on which a film is to be formed has been widely put into practical use.
[0003]
[Problems to be solved by the invention]
In the prior art, the material atoms (molecules) are directly electron-impacted for ionization. However, it is said that the actual ionization is 1% or less to several% due to a small collision cross-sectional area between the two.
[0004]
In recent years, however, the functions required for ionized film formation have not only been improved in the conventional film quality and the adhesion to the substrate. If the ionization rate of the source atoms (molecules) is sufficiently high and the ionization is not uniform, such as forming a film only on an arbitrary part of the substrate as an ion beam or controlling the beam to an arbitrary distribution, it can be realized. Needs are becoming more sophisticated to the point where they cannot.
[0005]
In view of such a point, the present invention provides a deposited film forming method and a deposited film forming apparatus aiming at realizing uniform ionization of a beam of source atoms (molecules) in a cross-sectional direction of the beam and consequently improving the ionization rate. The purpose is to:
[0006]
[Means for Solving the Problems]
A deposition film forming method of using a process gas containing at least a rare gas, evaporating source particles for deposition film formation from an evaporation source, and forming a deposition film on a substrate for deposition film formation,
The rare gas is caused to act on the raw material particles in a metastable excited state, and a member (electrode disposed near the process gas supply point (supply port) in the flight space of the raw material particles or on the substrate side) , A deposition-preventing plate, etc.) at the following surface potential to form a deposited film.
[0007]
0 ≧ Vp−V
Vp: maximum plasma potential in the flight space of source atoms (molecules) V: surface potential of the member At that time, the rare gas contains at least helium.
[0008]
Then, a deposition film forming apparatus having a deposition film forming substrate, an evaporation source, a deposition-preventing plate disposed so as to surround them, a process gas supply means and a process gas excitation means in a vacuum vessel provided with an exhaust means. At
A member (electrode, deposition plate, etc.) capable of controlling the surface potential is provided near the excitation gas supply port provided in the process gas excitation means or on the substrate side.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the operation of the claims will be described.
[0010]
In the method of the present invention, an evaporation source for a raw material of a deposited film is provided in a vacuum vessel provided with an exhaust unit, a process gas containing at least a rare gas is supplied, and the raw material is supplied onto a substrate in the vacuum vessel. Since the rare gas is put into a metastable excited state and caused to act on the source atoms (molecules) to cause Penning ionization, a deposited film is formed by a so-called ionization film forming method.
[0011]
The energy of the metastable excited state of the rare gas and the long life of He and Ar are described in "Basics of Plasma and Film Formation" by Mitsuharu Konuma, published by Nikkan Kogyo Shimbun (1986), and the recent life of He. Is reported to be about 9000 seconds at the 52nd Annual Meeting of the Physical Society of Japan (1997, March, Nagoya), etc., by "Single-triplet conversion of helium-excited atoms on the surface of an organic ultrathin film" by Chiyo University and Satoshi Ariyoshi.
[0012]
The metastable excited rare gas released from the supply port into the flight space of the source atoms penetizes the source atoms present in the emission path due to its long life and high excitation energy, and generates pairs of ions and electrons. . However, these ions and electrons only have emission energies during evaporation from the evaporation source to the substrate, but do not have sufficient kinetic energy in the cross-sectional direction of the flight space. Therefore, the distribution of the source atom ions in the cross section of the flight space from the supply port to the substrate becomes extremely poor in uniformity reflecting the discharge path of the rare gas from the supply port.
[0013]
Naturally, such a lack of diffusivity in the ionization process of the source atoms hinders an increase in the ionization rate of the source atoms. Therefore, it can be said that it is indispensable to improve the ionization rate of the beam as well as the uniformity of the ion distribution in the beam cross section.
[0014]
As a result of taking these facts into consideration, in the present invention, a member (electrode, deposition plate, or the like) that is close to the supply point (supply port) of the process gas in the flying space of the raw material particles or disposed on the substrate side Is controlled to the following surface potential to form an electron attraction electric field, and to create a constant electron flow, thereby inducing ambipolar diffusion in which ions are put on this flow.
[0015]
0 ≧ Vp−V
Vp: the maximum plasma potential in the flight space of the raw material atoms (molecules) V: the surface potential of the member As a result, the generated ions are in the direction in which the diffusion speed of the rare gas in the metastable excited state is lowest (the probability of the existence of ions is lowest) Direction), and uniform and highly efficient ionization is realized.
[0016]
Further, in the method of the present invention, by using helium, which has a much longer metastable excited state lifetime of several thousand seconds than other rare gases, a metastable excited state in a flight space is formed in a source atom (molecule). The partial pressure of helium can be significantly increased, and the ionization rate of the raw material atoms (molecules) can be significantly increased.
[0017]
Further, in the apparatus of the present invention, a substrate for forming a deposited film, an evaporation source, a deposition preventing plate disposed so as to surround these, a process gas supply unit, and a process gas excitation unit are provided in a vacuum vessel provided with an exhaust unit. In the deposited film forming apparatus having
The source atoms (ionized by ionization) due to the presence of a member (electrode, deposition plate, etc.) capable of controlling the surface potential near the excitation gas supply port provided in the process gas excitation means or on the substrate side Molecules) quickly become uniform in the cross-sectional direction of the flight space.
[0018]
【Example】
Examples of the method for forming a deposited film according to the present invention will be described below, but the present invention is not limited to these examples.
[0019]
(Example 1)
In this example, a sputtering film forming method was performed using the deposited film forming apparatus having the configuration shown in FIG. 1 while supplying a helium gas in a metastable excited state. A sputtering target 104 was used as a source of the raw material molecules. Helium in a metastable excited state was generated as follows. That is, power is supplied from the microwave rectangular waveguide to the circle-type slot array microwave waveguide 112, a standing wave is generated in the circle-type waveguide, and microwave radiation occurs from each slot. The tube 112 has a built-in aluminum nitride tapered gas discharge tube in each slot portion, and helium in a metastable excited state in the discharge tube is discharged from each slot. The source atoms traveling from the target 104 to the substrate 102 collided with metastable excited atoms of helium and metastable excited helium, also collided with metastable excited argon, and ionized by the Penning ionization mechanism.
[0020]
Hereinafter, description will be given according to the process procedure.
[0021]
(1) In the apparatus shown in FIG. 1, first, a silicon wafer 102 having a diameter of 4 inches is set on a substrate holder 103 (floating potential) made of stainless steel, and a portion A of an electrode pair (FIG. 5) formed on the wafer is set. 4 V, which is the maximum plasma potential, and -10 V as an ion drawing voltage to the electrode were applied to the electrode B at the ground potential, and the inside of the vacuum vessel 101 was evacuated once to 10 ^-4 Pa or less by the evacuation means 109. .
[0022]
(2) Helium gas is introduced at 100 sccm from the gas introduction pipe 107 and argon gas at 100 sccm is introduced from 115 while continuing evacuation, and the internal pressure of the vacuum vessel 101 is maintained at 4.0 Pa by adjusting the opening of the exhaust valve 108. did.
[0023]
(3) Next, the power supply 114 for setting the voltage of the electron attractive electrode was set to 5V.
[0024]
(4) Then, the power supply 111 for setting the voltage of the ionizing raw material accelerating electrode was set to 100V.
[0025]
(5) Next, in this state, 400 W of microwave power was supplied from a microwave power supply (not shown) to the circle-type slot array microwave waveguide 112, and the emission of helium in a metastable excited state was started from each slot.
[0026]
(6) In the state of (5), 500 W of DC power is supplied from a DC power supply (not shown) to the gold target 104 placed 150 mm immediately below the substrate 102, and after the evaporation rate is stabilized, the shutter 106 is opened. It was opened and a film was formed on the substrate 102.
[0027]
(7) When the film formation time has passed 2 minutes, the shutter 106 is closed, the substrate 102 is taken out of the apparatus, the film is removed from the reference surface of the wafer, and then set on the stylus-type film thickness measuring device. The thickness of the deposited film was measured at the portions A and B (FIG. 5) of the electrode pair.
[0028]
Similarly, the set voltage of the electron attraction electrode voltage setting power supply 114 was sequentially increased from -10 V to 15 V in increments of 5 V to form a film, and each time the film thickness of all the electrode pairs on the sample was measured.
[0029]
The measured values of the deposited film thickness are arranged as an average value of the deposition rate ratio Tb / (Ta + Tb) obtained for all the electrode pairs, where the film thickness of the portion A is Ta and the film thickness of the portion B is Tb. The index was used to indicate the degree of When the maximum value of the deposition rate ratio in the wafer is Rmax and the minimum value is Rmin, the distribution rate ratio (Rmax−Rmin) / (Rmax + Rmin) was used as an index representing the variation of ionization.
[0030]
FIG. 6 shows the dependence of each ratio on the electron withdrawing electrode voltage.
[0031]
FIG. 6 shows that the present invention makes it possible to achieve good ionization and ion distribution.
[0032]
(Example 2)
This embodiment differs from the first embodiment in that argon is used instead of helium. All other points were the same as in Example 1 except that 2 V, which was the maximum plasma potential in this system, was applied to the portion A of the electrode pair (FIG. 5) formed on the wafer.
[0033]
The measured value of the deposited film thickness is treated in the same manner as in Example 1, and the dependence on the electron withdrawing electrode voltage is shown in FIG.
[0034]
From FIG. 7, it can be seen that good ionization and ion distribution can also be achieved by replacing the rare gas in the metastable excited state with argon.
[0035]
(Example 3)
In this example, the deposited film forming apparatus having the configuration shown in FIG. 2 was used. The difference from the first embodiment is that the evaporation source of the raw material is changed from the sputtering target of the apparatus of FIG. 1 to a resistance heating type crucible (both the inner diameter and the opening diameter are 8 mm). All other points were the same as in Example 1.
[0036]
Hereinafter, description will be given according to the process procedure.
[0037]
(1) In the apparatus shown in FIG. 2, first, a 4-inch diameter silicon wafer 202 is set on a stainless steel substrate holder 203 (floating potential), and A of an electrode pair (FIG. 5) formed on the wafer is set. 5 V, which is the maximum plasma potential of the system, and -10 V as an ion pull-in voltage to the electrode are applied to the electrode B at the ground potential, and the inside of the vacuum vessel 201 is evacuated to 10 ^-4 Pa or less by the vacuum exhaust means 209. Once evacuated.
[0038]
(2) Helium gas was introduced at 100 sccm from the gas introduction pipe 207 while continuing evacuation, and the internal pressure of the vacuum vessel 201 was maintained at 4.0 Pa by adjusting the opening of the exhaust valve 208.
[0039]
(3) Next, the power supply 214 for setting the voltage of the electron attracting electrode was set to 5V.
[0040]
(4) Then, the power source 211 for setting the voltage of the ionizing material acceleration electrode was set to 100V.
[0041]
(5) Next, in this state, microwave power 400 W was applied from a microwave power supply (not shown) to the circle-type slot array microwave waveguide 212, and emission of helium in a metastable excited state was started from each slot.
[0042]
(6) In the state of (5) above, the crucible 304 placed 150 mm directly below the substrate 202 and containing 0.5 g of gold is heated to about 1460 ° C., and after the evaporation rate is stabilized, the shutter 206 is opened. It was opened and a film was formed on the substrate 202.
[0043]
(7) When the film formation time has passed 30 seconds, the shutter 206 is closed, the substrate 202 is taken out of the apparatus, the film is removed from the reference surface of the wafer, and then set on the stylus-type film thickness measuring device. The thickness of the deposited film was measured at the portions A and B (FIG. 5) of the electrode pair.
[0044]
Similarly, the set voltage of the electron attraction electrode voltage setting power supply 114 was sequentially increased from -10 V to 15 V in increments of 5 V to form a film, and each time the film thickness of all the electrode pairs on the sample was measured.
[0045]
The measured value of the deposited film thickness is treated in the same manner as in Example 1, and the dependence on the electron withdrawing electrode voltage is shown in FIG.
[0046]
From FIG. 8, it can be seen that good ionization and ion distribution can also be achieved by replacing the evaporation source of the raw material with a crucible.
[0047]
(Example 4)
In this example, the deposited film forming apparatus having the configuration shown in FIG. 3 was used. 1 is different from FIG. 1 in that the slots formed in the circle-type microwave waveguide 312 that emits a rare gas in a metastable excited state are changed from one stage of the apparatus of FIG. 1 to a two-stage configuration. All other points were the same as in Example 1.
[0048]
The measured value of the deposited film thickness is treated in the same manner as in Example 1, and the dependence on the electron withdrawing electrode voltage is shown in FIG.
[0049]
From FIG. 9, it is possible to realize better ionization and ion distribution by changing the slot formed in the circle-type microwave waveguide 312 from the first stage of the apparatus of FIG. 1 to a two-stage configuration. I understand.
[0050]
(Example 5)
This embodiment is different from the fourth embodiment in that argon is used instead of helium. The other points were the same as in Example 4 except that 2 V, which was the maximum plasma potential in this system, was applied to part A of the electrode pair (FIG. 5) formed on the wafer.
[0051]
The measured value of the deposited film thickness is treated in the same manner as in Example 1, and the dependence on the electron withdrawing electrode voltage is shown in FIG.
[0052]
From FIG. 10, it can be seen that good ionization and ion distribution can be realized by replacing argon with a rare gas that is in a metastable excited state.
[0053]
(Example 6)
In this example, the deposited film forming apparatus having the configuration shown in FIG. 4 was used. Embodiment 4 is different from Embodiment 4 in that the evaporation source of the raw material is changed from the sputtering target of the apparatus of FIG. 3 to a resistance heating type crucible (both the inner diameter and the opening diameter are 8 mm). The other points were the same as in Example 4 except that 5 V, which was the maximum plasma potential in this system, was applied to the portion A of the electrode pair (FIG. 5) formed on the wafer.
[0054]
All the steps are the same as in Example 3.
[0055]
The measured value of the deposited film thickness is treated in the same manner as in Example 1, and the dependence on the electron withdrawing electrode voltage is shown in FIG.
[0056]
From FIG. 11, it can be seen that good ionization and ion distribution can also be achieved by changing the evaporation source of the raw material to a crucible.
[0057]
【The invention's effect】
As described above, the present invention does not aim at improving the film quality or the adhesion to the substrate, which is realized by ionization of 1% or less to several% of the conventional ion beam. It responds to advanced needs that cannot be realized unless the ionization rate of the source atoms (molecules) is sufficiently high and ionization occurs uniformly, such as by forming a film only on the surface or controlling the beam to an arbitrary distribution. Yes,
According to the present invention, it is possible to realize the above-described advanced ionization film formation even on a large-area substrate.
[Brief description of the drawings]
FIG. 1A is a schematic diagram illustrating an example of a configuration of a deposited film forming apparatus capable of performing a deposited film forming method according to the present invention.
FIG. 1B is a schematic view showing a circular slot array microwave waveguide 112 with a built-in tapered gas release tube of FIG. 1A.
FIG. 1C is another schematic diagram showing the tapered gas discharge tube built-in circle slot array microwave waveguide 412 of FIG. 1A.
FIG. 2A is a schematic view showing another example of the configuration of a deposited film forming apparatus capable of performing the deposited film forming method according to the present invention.
2B is a schematic diagram showing the tapered gas discharge tube built-in circle slot array microwave waveguide 212 of FIG. 2A.
FIG. 3A is a schematic view showing another example of the configuration of a deposited film forming apparatus capable of performing the deposited film forming method according to the present invention.
FIG. 3B is a schematic view showing a circular slot array microwave waveguide 312 with a built-in tapered gas discharge tube of FIG. 3A.
FIG. 4A is a schematic view showing another example of the configuration of a deposited film forming apparatus capable of performing the deposited film forming method according to the present invention.
FIG. 4B is a schematic view showing a circular slot array microwave waveguide 412 with a built-in tapered gas release tube of FIG. 4A.
FIG. 5 is a schematic view showing the shape and arrangement of an electrode pair formed on a silicon wafer used in an example of the present invention.
FIG. 6 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 1 of the present invention.
FIG. 7 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 2 of the present invention.
FIG. 8 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 3 of the present invention.
FIG. 9 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 4 of the present invention.
FIG. 10 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 5 of the present invention.
FIG. 11 is a graph showing the dependence of the deposition rate ratio distribution on the electron withdrawing electrode voltage, showing the degree of ionization, and showing the variation in ionization, according to Example 6 of the present invention.
[Explanation of symbols]
101, 201, 301, 401 Vacuum container 102, 202, 302, 402 Substrate (silicon wafer)
103, 203, 303, 403 Substrate holder 104, 304 Sputtering target 204, 404 Crucible 205, 405 Crucible heater 106, 206, 306, 406 Shutter 107, 207, 307, 407 Rare gas introduction pipes 108, 208, 308, 408 Exhaust valves 109, 209, 309, 409 Vacuum exhaust means 110, 210, 310, 410 Ionized material accelerating electrodes 111, 211, 311, 411 Ionized material accelerating electrode voltage setting power supplies 112, 212, 312, 412 Tapered gas release Tube built-in circle type slot array microwave waveguides 113, 213, 313, 413 Electron attracting electrodes 114, 214, 314, 414 Power supply 115, 315 for electron attracting electrode voltage setting Argon gas for sputtering Pipes 116, 216, 316, 416

Claims (3)

A deposition film forming method of using a process gas containing at least a rare gas, evaporating source particles for deposition film formation from an evaporation source, and forming a deposition film on a substrate for deposition film formation,
The rare gas is caused to act on the raw material particles in a metastable excited state, and a member (electrode disposed near the process gas supply point (supply port) in the flight space of the raw material particles or on the substrate side) , Proof plate, etc.)
0 ≧ Vp−V
Vp: the maximum plasma potential in the flight space of the raw material atoms (molecules) V: a deposition film forming method characterized by forming a deposition film while controlling the surface potential of the member to the surface potential. The method according to claim 1, wherein the rare gas contains at least helium. In a vacuum vessel provided with an exhaust means, a substrate for forming a deposited film, an evaporation source, a deposition prevention plate disposed so as to surround them, a deposited film forming apparatus having a process gas supply means and a process gas excitation means,
A deposition film forming apparatus characterized in that a member (electrode, deposition plate, etc.) capable of controlling the surface potential is provided near the excitation gas supply port provided in the process gas excitation means or on the substrate side. .

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