JP2013253288A - Thin film deposition apparatus and thin film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To deposit a film with accurately controlled composition on a substrate with a sufficient adhesion strength.SOLUTION: A thin film deposition apparatus includes: a target 8 having a hollow part; a substrate holder 13 holding a substrate 14; a vapor deposition source 1 that is disposed to be opposite to the substrate holder through the hollow part and on which vapor deposition material 2 is placed; and a vacuum chamber 17 having the target, the substrate holder, and the vapor deposition source internally.

Description

  The present invention relates to a thin film forming apparatus and a forming method.

A conventional thin film forming apparatus and a thin film forming method using the same will be described with reference to FIG.
FIG. 4 is a schematic view showing the configuration of a conventional thin film forming apparatus.
As shown in FIG. 4, the conventional thin film forming apparatus has an electron beam evaporation source 71 used for forming a thin film using a main material and a molecular beam cell evaporation source 77 used for forming a thin film using a secondary material. Have.

  More specifically, first, in the state where Cu (copper) as a secondary material is placed on the molecular beam cell deposition source 77, the pressure inside the apparatus is observed with a nude ion vacuum gauge 74, and the film formation rate of Cu is measured. The temperature of the molecular beam cell deposition source 77 is adjusted so as to be 1 nm / min. At the time of adjustment, the molecular beam cell deposition source shutter 722 and the nude ion gauge shutter 724 are opened, and these are temporarily closed after the adjustment is completed.

Simultaneously with the adjustment of the molecular beam cell deposition source 77, the input power to the electron beam deposition source 71 on which Al (aluminum) as the main material is placed is adjusted.
When the adjustment of the molecular beam cell deposition source 77 and the electron beam deposition source 71 is completed, the electron beam deposition source shutter 721, the molecular beam cell deposition source shutter 722, and the substrate shutter 723 are simultaneously opened. Then, by controlling the electric power applied to the electron beam evaporation source 71 so that the film forming rate in the quartz oscillator film thickness meter 75 is constant, the auxiliary material Cu is added to the main material Al. An Al—Cu alloy film 715 is formed on the substrate 714 (for example, Patent Document 1).

JP 2004-18903 A

  However, in the conventional configuration shown in FIG. 4, since the molecular beam cell deposition method is used for the addition of the submaterial to the main material, accuracy cannot be obtained, and for example, it is difficult to control the composition on the order of less than 1000 ppm. have. Moreover, since it is a thin film formation method combining the electron beam vapor deposition method and the molecular beam cell vapor deposition method, there is a problem that the adhesion strength of the formed thin film is insufficient.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to form a film with a highly precise composition on a substrate with high adhesion strength.

  In order to achieve the above object, a thin film forming apparatus of the present invention includes a target having a hollow portion, a substrate holder that holds a substrate, and a vapor deposition material that is disposed to face the substrate holder through the hollow portion. And a vacuum chamber having therein the target, the substrate holder, and the vapor deposition source.

  Furthermore, the thin film forming method of the present invention is characterized in that a target having a hollow portion is sputtered and attached to a substrate, and at the same time, a vapor deposition material that has passed through the hollow portion is vapor-deposited on the substrate.

  As described above, by forming a film on a substrate by using a sputtering method and an evaporation method, a film with a highly accurate composition can be formed on the substrate with high adhesion strength.

Schematic which shows the structure of the thin film formation apparatus which concerns on embodiment of this invention Schematic plan view showing the configuration of a thin film forming unit in a thin film forming apparatus according to an embodiment of the present invention Schematic sectional view showing the configuration of a thin film forming unit in the thin film forming apparatus according to the embodiment of the present invention Schematic showing the configuration of a conventional thin film forming apparatus

  In the thin film forming apparatus and the thin film forming method according to the embodiment of the present invention, for example, intrinsic silicon as a main material is added to p-type impurities (B: boron, etc.) or n-type impurities (P : Phosphorus, etc.) can be used to form a silicon thin film or the like.

Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic diagram showing a configuration of a thin film forming apparatus according to the present embodiment, and FIG. 2 is a schematic plan view showing a configuration of a thin film forming unit in the thin film forming apparatus according to the present embodiment. FIG. 3 is a schematic cross-sectional view showing the configuration of the thin film forming unit in the thin film forming apparatus according to the present embodiment, and is a schematic cross-sectional view taken along the line AA of FIG. The sputtering cathode 7 is surrounded by the earth shield 100 as shown in FIGS. 2 and 3, but the earth shield 100 is omitted in FIG.

  As shown in FIGS. 1 to 3, the thin film forming apparatus according to the present embodiment has an inner portion larger than the outer periphery of the vapor deposition source 1 above the vapor deposition source 1 on which the vapor deposition material 2 as the main material of the thin film to be formed is placed. An annular sputtering cathode 7 having a peripheral hollow portion 7a is disposed. On the sputtering cathode 7, an annular target 8 made of a sub-material containing a component as an additive material is placed. The annular target 8 has a hollow portion 8a having the same shape and size as the hollow portion 7a, and the sputtering cathode 7 and the annular target 8 are arranged so that the centers of the hollow portion 7a and the hollow portion 8a are aligned. The sputtering cathode 7 and the annular target 8 are installed between the vapor deposition source 1 on which the vapor deposition material 2 is placed and the substrate holder 13 that holds the substrate 14. At this time, the vapor deposition material 2 is placed on the vapor deposition source 1 so as to face the substrate holder 13 through the hollow portion 7 a of the sputtering cathode 7 and the hollow portion 8 a of the annular target 8. The electron gun 3 is installed around the vapor deposition source 1 and irradiates the vapor deposition material 2 with an electron beam 5 to evaporate the vapor deposition material 2 to generate vapor deposition particles 6. The vacuum chamber 17 contains the substrate holder 13, the sputtering cathode 7 and the vapor deposition source 1.

  In such a thin film forming apparatus, the deposition amount of the deposition material 2 on the substrate 14 is adjusted by controlling the applied voltage and applied current of the EB power source 4 for generating an electron beam connected to the electron gun 3. Independently of this, the amount of sputtering of the secondary material constituting the annular target 8 is adjusted by controlling the applied power of the sputtering RF power source 10 connected to the sputtering cathode 7. In this way, by adding the secondary material by sputtering, the addition amount of the secondary material can be adjusted with high accuracy. In addition, since the vapor deposition particles 6 pass through the plasma 11 generated at the time of sputtering, the vapor deposition particles 6 adhere to the substrate 14 with higher strength than when the vapor deposition particles 6 do not pass through the plasma 11.

  The annular sputtering cathode 7 on which the annular target 8 is placed is installed in the vacuum chamber 17 via an insulating material 18 as shown in FIG. At this time, the power introduction terminal 19 of the sputtering cathode 7 is connected to the RF power source 10 through the matching unit 9.

  When thin film formation is performed, first, the electron beam 5 is generated from the electron gun 3 by supplying electric power from the EB power source 4. The generated electron beam 5 is bent by an electron beam deflecting magnet (not shown), and is irradiated onto the vapor deposition material 2 placed on the vapor deposition source 1. The vapor deposition material 2 irradiated with the electron beam 5 evaporates after melting, and vapor deposition particles 6 are generated as a vapor flow. The generated vapor deposition particles 6 convect while diffusing toward the substrate 14. In FIG. 1, the case where the vapor deposition particles 6 diffuse linearly is illustrated, but the degree of diffusion is not constant, for example, when the vapor deposition particles 6 diffuse so as to spread more widely as they move away from the vapor deposition source 1. The degree of diffusion can be adjusted by setting the environment.

At this time, the pressure adjusting valve 15 is adjusted to keep the inside of the vacuum chamber 17 at a pressure of about 10 ⁻² to 10 ⁻⁴ Pa by a vacuum exhaust system such as a vacuum pump 15a. In addition, an inert gas such as Ar (argon) or He (helium) is introduced into the vacuum chamber 17 through the gas flow rate regulator 16.

  Next, a negative voltage is applied (power supply) from the sputtering RF power source 10 to the annular sputtering cathode 7 on which the annular target 8 is placed, and the matching unit 9 is adjusted to achieve matching, thereby obtaining a vacuum chamber. 17, an inert gas plasma 11 is generated. The annular target 8 is sputtered by the plasma ions in the plasma 11 and the sputtered particles 12 are emitted. At this time, the RF power supply 10 is controlled independently of the EB power supply 4.

  Here, by opening a shutter plate (not shown) between the thin film forming unit composed of the vapor deposition source 1 and the sputtering cathode 7 and the substrate holder 13 installed at a position opposite to the thin film formation unit, the vapor deposition particles 6 are formed. While passing through the plasma 11 and reaching the substrate 14, the sputtered particles 12 also reach the substrate 14.

  Thus, the electron beam vapor deposition method and the sputtering method are performed simultaneously. The electron beam evaporation method is capable of high-speed film formation (deposition rate: 10 to 100 μm / min) and is therefore used when the main material (deposition material 2) is formed on the substrate 14. On the other hand, the sputtering method has a relatively slow film formation rate (particularly, in the conventional sputtering method in which no magnet is used, the film formation rate is 10 nm / min), but it is easy to control the film to be formed. Adopted for the application of (annular target 8). Thereby, for example, the main material in which the addition amount of the secondary material is controlled with high accuracy such as 1% or less (ppm order) can be formed on the substrate 14.

  Further, since the vapor deposition material 2 is held by the vapor deposition source 1 at a position facing the substrate holder 13 through the hollow portion 7a and the hollow portion 8a, the vaporized vapor deposition particles 6 pass through the hollow portion 8a and pass through the substrate. Vapor deposition is performed on the substrate 14 held by the holder 13. At this time, when the sputtering method is performed, the plasma 11 is generated in the space between the hollow portion 8 a and the substrate 14, and the vapor deposition particles 6 pass through the plasma 11. Since the vapor deposition particles 6 that have passed through the plasma 11 are activated and ionized, they are deposited on the substrate 14 in a more dense and high adhesion strength state. Furthermore, when the substrate 14 is directly exposed to the plasma 11, the surface is cleaned and the adhesion of the vapor deposition particles 6 is further increased.

  Basically, the positions of the substrate 14, the vapor deposition source 1, the annular target 8, and the sputtering cathode 7 and the distance from each other may be adjusted so that the vapor deposition particles 6 and the sputter particles 12 can sufficiently reach the substrate 14. For example, as shown in FIG. 1, the substrate 14 and the evaporation source are arranged so that a straight line connecting the outer periphery of the substrate 14 and the evaporation source 1 passes through the hollow portion 8 a of the annular target 8 and the hollow portion 7 a of the sputtering cathode 7. 1. An annular target 8 and a sputtering cathode 7 are disposed. At this time, as shown in FIGS. 1 and 2, the inner circumference size r of the annular target 8 and the sputtering cathode 7 can be adjusted so that the vapor deposition particles 6 are not blocked by the annular target 8 and the sputtering cathode 7. More desirable. This is because the deposition of the vapor deposition particles 6 is not reduced, and the deposition of the deposit 11 is achieved with higher adhesion strength under the action of the plasma 11. Specifically, since the vapor deposition particles 6 are convected toward the substrate 14 while diffusing, the diameter r of the hollow portion 8a of the annular target 8 and the hollow portion 7a of the sputtering cathode 7 arranged in the middle of the convection of the vapor deposition particles 6 is. The annular target 8 and the sputtering cathode 7 are configured to be larger than the width w of the region where the vapor deposition particles 6 diffuse at that position. Thereby, since the vapor deposition particles 6 reach the substrate 14 without being blocked by the annular target 8 and the sputtering cathode 7, the film can be efficiently formed.

  Note that the distance l which is the shortest distance from the surface of the vapor deposition material 2 placed on the vapor deposition source 1 to the surface of the annular target 8 on the side facing the substrate 14 is the surface of the annular target 8 on the side facing the substrate 14. The inventors have found that it is more preferable to make the distance smaller than the distance L, which is the shortest distance from the surface to the surface of the substrate 14. Since the width w of the diffusion region of the vapor deposition particles 6 increases as the distance from the surface of the vapor deposition material 2 increases, it is necessary to increase the diameter r of the hollow portion 8a and the hollow portion 7a as the distance l increases. However, if the diameter r of the hollow portion 8a is too large, the surface area of the annular target 8 facing the substrate 14 may decrease, and the sputtered particles 12 may not adhere to the substrate 14 uniformly. Specifically, the sputtered particles 12 are less likely to adhere to the region immediately above the hollow portion 8a in the substrate 14 (concave distribution). On the other hand, since the region where the sputtered particles 12 diffuse becomes wider as the distance L increases, the sputtered particles 12 reach the region directly above the hollow portion 8a in the substrate 14 even when the diameter r of the hollow portion 8a is large. There is a case. From these, as described above, when the distance l is made smaller than the distance L, even if the diameter r of the hollow portion 8a is made larger than the width w of the region where the vapor deposition particles 6 diffuse, the annular target 8 to the substrate 14 A sufficient distance L can be secured, and the sputtered particles 12 can be diffused into the surface body of the substrate 14. Thereby, the in-plane uniformity of the secondary material contained in the film formed on the substrate 14 is improved.

  Furthermore, when the substrate 14 has a disk shape and the annular target 8 has a donut shape, it is preferable that the distance L be 0.5 times or more and 2 times or less the outer diameter R of the annular target 8. Since the sputtered particles 12 tend to reach the substrate 14 from the outer peripheral direction of the substrate 14, the distance between the substrate 14 and the annular target 8 is too short at less than 0.5 times, and the concentration of the secondary material on the outer periphery of the substrate 14 is low. This is because the concentration is deep (concave distribution), and when it is larger than twice, it is too far, and the concentration of the sub-material near the center of the substrate 14 may be high (convex distribution).

  Further, as shown in FIGS. 1 and 2, it is more preferable that the diameter r of the hollow portion 8 a is smaller than the diameter W of the substrate 14 and the outer diameter R of the annular target 8 is larger than the diameter W of the substrate 14. In this case, the center of the hollow portion 8 a of the annular target 8 is arranged on a perpendicular line passing through the center of the substrate 14. Then, since the sputtered particles 12 reach the entire substrate 14 evenly, the in-plane uniformity of the secondary material in the film formed on the substrate 14 is further improved.

  Furthermore, when the surfaces of the annular target 8 and the substrate 14 facing each other are arranged in parallel, and the area of the surface of the annular target 8 facing the substrate 14 is ½ or more and twice or less than the area of the substrate 14, it is formed on the substrate 14. The inventors have found that the distribution of the secondary material in the film is uniform. The facing area here refers to the area of the orthogonal projection of the annular target 8 on the substrate 14.

  Based on these, in the present embodiment, as an example, the diameter W of the substrate 14 is 300 mm, the outer diameter R of the annular target 8 is 400 mm, the diameter r of the hollow portion 8a is 200 mm, and the inner diameter ra of the vapor deposition source 1 is 100 mm. The distance L is 300 mm and the distance l is 125 mm.

  As the secondary material, for example, a p-type semiconductor material such as boron or an alloy of boron and silicon can be employed. Further, when forming an n-type silicon thin film (n-Si), an n-type semiconductor material such as phosphorus or an alloy of phosphorus and silicon can be employed as a secondary material.

  In the present embodiment, the circular target 8 is illustrated as a circle, but may be a rectangle or other shapes. Also in that case, it is necessary to provide the hollow part 8a in the center part so that the vapor deposition particle 6 can be supplied to the board | substrate 14. FIG.

  Further, as long as the plasma 11 can be generated between the hollow portion 8 a and the substrate holder 13, a part of the annular portion of the sputtering cathode 7 and the annular target 8 may be interrupted.

The main material is a material that is contained most in a film to be formed.
In the above description, the vapor deposition material 2 as the main material is vapor deposited on the substrate 14 by the electron beam vapor deposition method, but the vapor deposition material 2 can be vaporized by various other methods.

  The present invention is useful when forming a film such as an n-type semiconductor or a p-type semiconductor employed in a solar cell or the like.

DESCRIPTION OF SYMBOLS 1 Deposition source 2 Deposition material 3 Electron gun 4 EB power source 5 Electron beam 6 Deposition particle 7 Sputtering cathode 8 Annular target 9 Matching device 10 RF power source 11 Plasma 12 Sputtered particle 13 Substrate holder 14 Substrate 15 Pressure adjustment valve 15a Vacuum pump 16 Gas flow rate Adjuster 17 Vacuum chamber 18 Insulating material 71 Electron beam deposition source 74 Nude ion vacuum gauge 75 Quartz crystal thickness meter 77 Molecular beam cell deposition source 100 Earth shield 714 Substrate 715 Al-Cu alloy film 721 Shutter for electron beam deposition source 722 Shutter for molecular beam cell deposition source 723 Shutter for substrate 724 Shutter for nude ion gauge

Claims (7)

A target having a hollow portion;
A substrate holder for holding the substrate;
A vapor deposition source disposed opposite to the substrate holder through the hollow portion and placing a vapor deposition material;
A vacuum chamber having the target, the substrate holder, and the vapor deposition source therein;
A thin film forming apparatus comprising:   The thin film forming apparatus according to claim 1, wherein the vapor deposition material is a material that is contained most in a thin film to be formed.   3. The thin film forming apparatus according to claim 1, wherein a diameter of the hollow portion is larger than a diameter of a region where the evaporated deposition material diffuses when passing through the hollow portion.   The thin film forming apparatus according to claim 1, wherein a shortest distance between a surface of the target facing the substrate and the vapor deposition material is shorter than a shortest distance from the target to the substrate.   The thin film forming apparatus according to claim 1, wherein a shortest distance from the substrate to the target is 0.5 times or more and 2 times or less of an outer diameter of the target.   The thin film forming apparatus according to claim 1, wherein a diameter of the hollow portion is smaller than a diameter of the substrate, and an outer diameter of the target is larger than a diameter of the substrate. At the same time as sputtering the target having a hollow part and attaching it to the substrate,
A thin film forming method for depositing a deposition material that has passed through the hollow portion on the substrate.