JP2012197463A - Film deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film deposition method which can increase the rate of film deposition over a substrate to thereby efficiently deposit a film on the bottom surface of a trench or via-hole.SOLUTION: The film deposition method is a film deposition method for depositing a film over a substrate having a trench or a via-hole having a level difference with an aperture width or an aperture diameter of 3 μm or less and an aspect ratio of 1 or more. There are provided, in an evacuatable treatment chamber, a first electrode for supporting the substrate, a second electrode disposed opposite to the substrate and supporting a target, and a plurality of magnets which are disposed outside the second electrode and generate a cusp magnetic field inside the second electrode. The method includes introducing an Ne-containing treatment gas into the treatment chamber, supplying a high-frequency electric power for plasma generation to at least either of the first electrode and the second electrode, forming a cusp magnetic field on the second electrode to generate a plasma, and thereby depositing a film of the target material over the substrate having the trench or the via-hole.

Description

  The present invention relates to a method for forming a thin film in a semiconductor integrated circuit device or the like, and in particular, a thin film on a substrate having a trench or via hole having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. The present invention relates to a method for forming a film.

There has been proposed a plasma sputter processing apparatus capable of obtaining high ion concentration, better target utilization efficiency, high film formation speed, and uniform film formation thickness.
FIG. 15 is a cross-sectional view showing an example of a conventional plasma sputtering apparatus. The plasma sputtering apparatus shown in FIG. 15 is fixed to the reaction vessel 100 and the upper electrode 101 including the upper electrode 101 and the lower electrode 123 facing each other in parallel via at least a part of the internal space of the reaction vessel 100. A substrate 127 that includes a target plate 107 and that needs to be processed by a sputtering process is mounted on the lower electrode 123. In the MF region, one first rf power source 118 that operates in the HF region or the VHF region. Another rf power source 1220 that operates is connected to the upper electrode 101. According to the plasma sputter processing apparatus of FIG. 15, a large area uniformly distributed in a plane over the entire surface of the substrate 127 with independent control of ion density and ion energy and uniform etching rate of the target material. A high-density plasma can be created, and a plasma source having a low aspect ratio can be realized (see Patent Document 1).

JP 2000-156374 A (FIG. 1)

However, due to the evolution of the market, higher film formation efficiency and higher coverage rate are required compared to the technique of Patent Document 1.

On the other hand, in the plasma sputtering apparatus shown in FIG. 15, if the power applied to the upper electrode 101 is increased, the voltage applied to the path from the power source to the electrode increases, so that the withstand voltage performance needs to be increased and the structure is complicated. Therefore, materials and structures with high pressure resistance performance are often more expensive, which increases costs, and if the design is not fully studied, the voltage applied to the electrodes is large and abnormal discharge is likely to occur. There is a problem, and it is not yet known what resolves this point as far as the inventors can know.
In addition, there is a recent energy-saving boom, and it is very useful to increase the deposition rate of the thin film and increase the bottom coverage rate while maintaining the applied power.
Therefore, in view of the above circumstances, the present invention is applied when a thin film is formed on a substrate having a trench or a via hole having an opening width or an opening diameter of 3 μm or less and an aspect ratio of 1 or more. In this case, the present invention provides a thin film deposition method capable of increasing the deposition rate of the thin film on the bottom surface of the trench or via hole even when the same power is applied to the upper electrode functioning as the cathode electrode. It is aimed.

  The configuration of the present invention made to achieve the above object is as follows.

That is, a film forming method for forming a thin film on a substrate having a trench or a via hole having an opening width or an opening diameter of 3 μm or less and an aspect ratio of 1 or more,
In a processing chamber capable of being evacuated, a first electrode that supports a substrate, a second electrode that is disposed so as to face the substrate and supports a target, and is disposed outside the second electrode. A plurality of magnets for forming a cusp magnetic field inside the two electrodes,
A processing gas containing Ne is introduced into the processing chamber, high frequency power for plasma formation is supplied to at least one of the first electrode and the second electrode, and a cusp magnetic field is generated on the second electrode. Then, plasma is generated and a target material is deposited on a substrate having a trench or a via hole.

  The thin film formation method according to the present invention is applied when forming a thin film on a substrate having a trench or a via hole having an opening width or an opening diameter of 3 μm or less and an aspect ratio of 1 or more. . Since Ne is lighter than Ar, even if the metal particles sputtered from the target collide with Ne, the traveling direction of the metal particles is hardly changed, and the probability of adhesion to the substrate is increased. Therefore, by adding Ne gas, the deposition rate of the thin film on the substrate increases even when the same power is applied to the second electrode functioning as the cathode electrode. As a result, the processing time of the apparatus is improved by reducing the time required for one substrate.

  Further, since Ne is lighter than Ar, metal particles sputtered from the target collide with Ne and are more ionized. Therefore, when a thin film is formed on a substrate having a trench or via hole having an opening width or diameter of 3 μm or less and an aspect ratio of 1 or more, a cathode electrode is formed by adding Ne gas. Even when the same power is applied to the upper electrode functioning as a thin film, the deposition rate of the thin film on the bottom surface of the trench or via hole increases. As a result, the processing time of the apparatus is improved by reducing the time required for one substrate.

It is a schematic diagram which illustrates the plasma processing apparatus which enforces the film-forming method of the thin film which concerns on this invention. It is the schematic which shows the structure in the upper wall (outside) of a plasma processing apparatus, and the structure of the inner side. It is the schematic which shows the cross-sectional shape of a board | substrate. It is a fragmentary sectional view of the top plate which shows the magnetic field of the magnet of a plasma treatment apparatus. It is a top view of the 1/4 area | region of the top plate which shows the arrangement | sequence (I) of a magnet. It is a top view of the 1/4 area | region of the top plate which shows arrangement | sequence (II) of a magnet. It is a conceptual diagram which shows the cusp magnetic field which generate | occur | produces with the magnet mechanism comprised from a magnet and a top plate. It is a schematic explanatory drawing which shows the film-forming condition in the film-forming method of the thin film concerning this invention. It is the top view which showed the relationship between the magnetic field by a magnet, and the electric field by a high frequency power supply. It is a figure which shows the Ne addition rate dependence of the film-forming speed | rate of titanium (Ti). It is a figure which shows the electric power dependence of the cathode electrode of the film-forming speed | rate of copper (Cu). It is a figure which shows the N2 addition rate dependence of the film-forming speed | rate of titanium (Ti). It is a figure which shows the anode electric power dependence of the bottom coverage rate of copper (Cu). It is a figure which shows the aspect-ratio dependence of the bottom coverage rate of titanium (Ti). It is sectional drawing which shows the conventional plasma sputter | spatter processing apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the embodiments.

  First, with reference to FIGS. 1 to 3, the configuration of a plasma processing apparatus for carrying out the thin film forming method according to the present invention will be described. FIG. 1 is a schematic view illustrating a plasma processing apparatus for performing a thin film forming method according to the present invention. FIG. 2 is a schematic view showing a structure on the upper wall (outer side) of the plasma processing apparatus and a structure on the inner side thereof. FIG. 3 is a schematic view showing a cross-sectional shape of the substrate.

  As shown in FIGS. 1 and 2, in the present embodiment, as a plasma processing apparatus for forming a thin film on a substrate 17, for example, a magnetron sputtering apparatus is illustrated. The sputtering apparatus of this embodiment includes a reaction vessel 10 that can be evacuated as a processing chamber, and an anode electrode 15 (first electrode 15) that supports a substrate 17 in the reaction vessel 10 and a substrate 17. And a cathode electrode 11 (second electrode 11) that supports a target (not shown). In this sputtering process, a processing gas is introduced into a processing chamber in the reaction vessel 10, different electric power is applied to the cathode electrode 11 and the anode electrode 15 from the high-frequency power source 19 and the high-frequency power source 8, and a cusp magnetic field is formed on the cathode electrode 11. To do. Thus, the sputtering apparatus generates plasma in the processing chamber and forms a thin film of the target material on the substrate 17.

  An exhaust device such as an exhaust pump is connected to the exhaust port 18 of the reaction vessel 10 via a conductance valve (not shown). The reaction vessel 10 is connected with a gas introduction system 25 having a flow rate controller, a valve, and the like, as means for introducing a processing gas (process gas), and the processing gas is introduced from the gas introduction system 25 at a predetermined flow rate. (See FIG. 4).

  As the processing gas of this embodiment, a mixed gas containing Ne can be used. When reactive sputtering is performed, a mixed gas of a mixed gas containing Ne and a reactive gas composed of oxygen and nitrogen can be used. The reactive gas is selected from at least one selected from a gas group consisting of oxygen and nitrogen.

  The reaction vessel 10 includes a top plate 11, a cylindrical side wall 12, and a bottom plate 13. The lower portion 12b and the bottom plate 13 of the cylindrical side wall 12 are made of, for example, a metal such as stainless steel or aluminum (Al). The upper portion 12a of the cylindrical side wall 12 is made of ceramic (dielectric material). The top plate 11 has a flat plate shape, and is made of a nonmagnetic metal such as Al.

  Since the top plate 11 is mounted on the upper portion 12 a of the cylindrical side wall 12, it is electrically insulated from other portions of the reaction vessel 10. The top plate 11 functions as a cathode electrode when generating plasma. The cathode electrode 11 is connected via a matching circuit 20 to a high frequency power source 19 that can apply a variable voltage. The cathode electrode 11 is supplied with necessary high frequency power from a high frequency power source 19. A magnet mechanism composed of a plurality of magnets 6 is disposed on the cathode electrode 11 (back surface). By providing this magnet mechanism, plasma can be formed at a high density. This magnet mechanism is typically a circuit having a structure in which magnets having different polarities are arranged at each vertex of a quadrangle, and generates a cusp magnetic field (Cusp Field). Details of the magnet mechanism will be described later.

  As a target material supported on the front surface (lower surface) of the cathode electrode 11, for example, a material having a single composition such as tantalum (Ta), copper (Cu), titanium (Ti) or the like can be used, and GeSbTe or NiFe can be used. A composite composition composed of two or more such compositions can also be used. Of the target materials, Ta and Cu are non-magnetic materials, while NiFe is a magnetic material.

  In addition, the diameter of the upper part 12a and the lower part 12b of the cylindrical side wall 12 is the same. The diameter value is not an important issue and can vary between 40 cm and 60 cm. The height of the ceramic portion 12a of the cylindrical side wall 12 is likewise not critical and is in the range of 1 cm to 5 cm. The lower portion 12 b of the cylindrical side wall 12 and the bottom plate 13 are electrically grounded via a ground wire 14. The diameter of the top plate 11 corresponds to the diameter of the cylindrical side wall 12.

  A substrate holder 15 that functions as an anode electrode 15 mounted on the bottom plate 13 is disposed in the internal space of the reaction vessel 10. The substrate holder 15 is connected to a high-frequency power source 8 capable of applying a variable voltage via, for example, a matching circuit 9. The high frequency power source 8 is disposed outside the reaction vessel 10.

  The substrate 17 to be processed in the reaction vessel 10 is held on the substrate holder 15 by a substrate holding mechanism (not shown) such as an electrostatic adsorption holding device. The substrate holder 15 is disposed in parallel to the bottom plate 13 and is electrically insulated from the reaction vessel 10 by the insulator 16. The substrate holder 15 is a disk-shaped holding table, for example, and includes a holding mechanism (not shown) such as an electrostatic chucking electrode. The substrate holder 15 mounts the substrate 17 on its upper surface (front surface), and the substrate 17 is held by the holding mechanism with its processing surface facing upward.

  The substrate holder 15 may be formed to be rotatable in the in-plane direction of the substrate 17 by a rotation mechanism (not shown) such as a motor. The substrate holder 15 preferably includes a heating mechanism (not shown) such as a heater. The substrate temperature of the present embodiment can be set in a temperature range of, for example, minus 90 ° C. to plus 900 ° C.

  An example of the substrate 17 is a semiconductor wafer, which is held by the substrate holder 15 in a state where only the substrate is mounted or a state where the substrate 17 is mounted on a tray. As shown in FIG. 3, the substrate 17 has a trench 31 and a via hole 32 which are concave steps having an opening width or opening diameter of 3 μm or less and an aspect ratio (depth / opening width or opening diameter) of 1 or more. is doing. Hereinafter, the trench 31 and the via hole 32 may be simply referred to as a step. The trench 31 and the via hole 32 have a bottom 33 and an inner wall 34. As the substrate 17, a single crystal semiconductor substrate such as a silicon wafer, a polycrystalline silicon film, a glass substrate having a non-single crystal silicon film such as a microcrystalline silicon film or an amorphous silicon film, or a compound semiconductor substrate such as GaAs may be used. it can. The substrate 17 may be provided with various elements such as a transistor, a capacitor, and a photoelectric conversion element.

  Next, the magnet mechanism disposed on the top plate 11 will be described in detail with reference to FIGS. FIG. 4 is a partial cross-sectional view of the top plate showing the magnetic field of the magnet of the plasma processing apparatus. FIG. 5 is a plan view of a ¼ region of the top plate showing the magnet arrangement (I). FIG. 6 is a plan view of a quarter region of the top plate showing the magnet arrangement (II). FIG. 7 is a conceptual diagram showing a cusp magnetic field generated by a magnet mechanism composed of the magnet and the top plate shown in FIG.

  As shown in FIGS. 4 to 7, a plurality of magnets 21 are disposed on the top plate 21 and further fixed to the outer surface of the top plate 11. Since the magnets 21 are arranged in a symmetrical positional relationship, only a quarter region of the top plate 11 is shown in a plan view in FIGS.

  The magnet 21 is disposed on the outer surface of the top plate 11 so as to generate a cusp magnetic field 23 inside the top plate 11. In this case, strictly speaking, the cusp magnetic field 23 is called a point-cusp magnetic field determined by the four magnets 21. Here, in this specification, the “point cusp magnetic field” means that a closed cusp magnetic field is formed by four adjacent magnets 6 as shown in FIG.

  The only requirement for creating a point cusp field is that each adjacent magnet must have the opposite polarity at the pole toward the top plate 11. This means that the polarity of the magnet going to the inside of the reaction vessel 10 changes alternately. For example, as shown in FIG. 5, each corner portion (corner) of a quadrangle 22 drawn by a dotted line on the top plate 11 is arranged. 5 and 6, N and S mean the magnetic polarity of the magnet 21. The spacing (distance) between any two adjacent magnets is not critical and can vary from 2 cm to 10 cm depending on the strength of the magnet and the diameter of the top plate 11.

  As shown in FIG. 4, the arrangement of the magnets 21 creates a point cusp magnetic field 23 together with a cusp 23 a created between two adjacent magnetic fields 23 on the lower side of the top plate 11. Reference numeral 23b indicates magnetic flux lines. The magnetic flux lines 23b emerging from the magnetic pole bend toward the nearest opposite magnetic pole. Thus, the point cusp magnetic field 23 is formed. The point cusp magnetic field 23 generated in the space near the inner surface of the top plate 11 forms a magnetic flux line 23b that is closed to form a loop. Many magnetic flux loops are formed in the vicinity of the inner surface of the top plate 11, and as a result, a magnetic field cusp 23a is formed. Depending on the arrangement structure formed by the magnets 21 on the top plate 11, the uniformity of the plasma below the top plate 11 changes.

  The shape of the magnet 21 is preferably a cube or a cylinder whose cross-sectional shape is a square and a circle, respectively. Each of the magnets 21 is disposed in a hole 11 a formed on the outer surface of the top plate 11. For example, the thickness of the top plate 11 is approximately 20 mm, and the depth of the hole 11a is approximately 17 mm. Therefore, the bottom surface of the magnet 21 is close to the internal space of the reaction vessel 10.

  The cross-sectional shape of the magnet 21 is circular or quadrangular. If the cross-sectional shape of the magnet 21 is circular, the diameter is included in the range of 10 mm to 40 mm. The diameter value is not important. If the cross-sectional shape of the magnet 21 is a square, dimensions corresponding to those of a magnet having a circular cross-sectional shape are selected. The height of the magnet 21 is likewise not critical and is in the range of 3 mm to 10 mm. The magnetic strength of the magnet 21 is selected to have a magnetic field strength of approximately 50 Gauss to 500 Gauss below the top plate 11.

  In addition, as shown in FIG. 4, a circular gas passage 24 is formed inside the top plate 11. The circular gas passage 24 is coupled to a gas supply source (not shown) through a gas introduction system 25 and has a plurality of gas introduction holes 26 on the inner surface of the top plate 11. A processing gas (process gas) supplied by the gas supply source is introduced into the internal space of the reaction vessel 10 through the circular gas passage 24 and the gas introduction hole 26. The processing gas is first supplied to the circular gas passage 24 and then introduced into the processing chamber of the reaction vessel 10 through several gas introduction holes 26.

  The internal pressure of the reaction vessel 10 is controlled by adjusting the gas flow rate and adjusting a well-known variable orifice (not shown) located at the gas exhaust port 18. The internal pressure (pressure in the processing chamber) of the reaction vessel 10 is changed in the range of 0.2 Pa to 27 Pa, for example. In the present embodiment, in the thin film deposition method according to the present invention, which will be described later, the pressure in the processing chamber in the second step is set lower than the pressure in the processing chamber in the first step. The specific set pressure in the processing chamber will be described in detail in the description of the thin film formation method according to the present invention.

  In the present embodiment, the frequency of the high frequency power supply 19 that supplies power to the cathode electrode 11 is in the range of approximately 10 MHz to 300 MHz. On the other hand, the frequency of the high-frequency power supply 8 that supplies power to the anode electrode 15 is in the range of approximately 1 MHz to 15 MHz.

  Furthermore, in this embodiment, in the thin film formation method according to the present invention described later, the ratio of the anode power to the cathode power in the second step is larger than the ratio of the anode power to the cathode power in the first step. Is set. The specific setting of the power ratio will be described in detail in the thin film forming method according to the present invention. The anode electrode 15 may be used in a grounded state.

  Next, the mechanism of plasma generation in the reaction vessel 10 equipped with the above-described plasma source will be described. In FIG. 4, when a high-frequency current 19a is fed from the high-frequency power source 19 to the cathode electrode 11, plasma is generated by a mechanism of electrostatic coupling of the high-frequency power. At that time, electrons in the plasma are subjected to cyclotron rotation based on the presence of a point cusp magnetic field 23 created by a magnet 21 disposed on the cathode electrode 11. This increases the length of the electron path, thereby resulting in a higher ionization rate of the process gas. In addition, the collision of electrons and ions with the cathode electrode 11 is partially suppressed by the point cusp magnetic field 23. Therefore, the presence of the magnetic field 23 results in an increase in plasma density.

  In general, in the absence of a magnetic field, the plasma generated by the mechanism of electrostatic coupling between two parallel plates has a higher radial uniformity. In the presence of a magnetic field, this plasma uniformity changes. The magnet 21 disposed on the cathode electrode 11 forms a point cusp magnetic field 23 below the cathode electrode 11. The plasma density is maximum at the place where the strength of the magnetic field 23 existing parallel to the cathode electrode 11 is maximum. Similarly, the plasma density is low at a place where the strength of the magnetic field 23 existing parallel to the top plate is minimum. Therefore, the plasma density becomes maximum and minimum in the vicinity of the cathode electrode 11. However, since these maximum and minimum of plasma density are close to each other, diffusion creates plasma uniformity at a shorter distance from the cathode electrode 11 on the downstream side. Further, since the magnets 21 are alternately arranged to have opposite polarities, the magnetic flux lines 23b of the point cusp magnetic field 23 bend at a close distance from the inner surface of the cathode electrode 11. Therefore, an environment in which there is no magnetic field at a closer distance from the cathode electrode 11 is obtained.

  For the purpose of obtaining a uniform plasma density, it is possible to find another arrangement of the magnets 21 different from the above-described configuration. For example, the interval between two adjacent magnets near the center of the cathode electrode 11 can be made larger than the interval between two adjacent magnets near the periphery, or the magnet at the center can be removed. it can. Here, the magnet 21 is arranged in a band shape (as a band) only at a position close to the peripheral portion of the cathode electrode 11. A radius r1 is a radius of the cathode electrode (top plate) 11, and a radius r2 is a radius of a circular region where no magnet is arranged. With these arrangements, the number of magnets 21 near the center portion of the top plate 11 is smaller than the number of portions near the peripheral portion. That is, the magnetic flux density at the center portion of the top plate 11 and the peripheral edge thereof is lower than the magnetic flux density at the portion close to the peripheral edge portion.

  Next, with reference to FIGS. 1 to 3 and 8 again, the operation of the plasma processing apparatus and the thin film deposition method according to the present invention will be described. FIG. 8 is a schematic explanatory view showing a film forming state in the thin film forming method according to the present invention. In addition, titanium (Ti) or copper (Cu) was used as a target supported by the cathode electrode 11, and a mixed gas of Ar (argon) and Ne (neon) was introduced into the reaction vessel 10 as a processing gas.

A feature of the thin film forming method according to the present invention is that a mixed gas of Ar (argon) and Ne (neon) is used as a processing gas. First, the reason why a mixed gas of Ar (argon) and Ne (neon) is used as the processing gas will be described.

FIG. 10 is a graph showing the Ne addition rate dependence of the deposition rate of titanium (Ti). Titanium (Ti) is used as a target to be supported by the cathode electrode 11, and the processing gas is only Ar on a substrate having a trench or via hole having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. The film formation rate was compared between the above and the case where Ne was added. From this figure, it can be seen that the deposition rate of the thin film increases as the addition of Ne gas increases. At this time, the pressure in the processing chamber is 14 Pa, and the power applied to the cathode electrode is 3200 W. Note that when a light noble gas, helium, is added, the sputtering rate is reduced because it is too light, and the deposition rate is reduced. In addition, when a heavy rare gas such as krypton or xenon is added, scattering when colliding with metal particles increases, and the film formation rate decreases.

FIG. 11 is a diagram showing the power dependency of the cathode electrode on the deposition rate of copper (Cu). Copper (Cu) is used as a target to be supported by the cathode electrode 11, and the processing gas is only Ar on a substrate having a trench or via hole having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. The film formation rate was compared between the above and the case where Ne was added. From this figure, it can be seen that the use of Ne gas increases the deposition rate of the thin film. At this time, the pressure in the processing chamber is 8 Pa, and the power applied to the cathode electrode is 4000 W. In the film forming method of the present invention, the voltage applied to the cathode voltage is 200 V or less, that is, the ion energy is 200 eV or less. In the range of 200 eV or less, there is no difference in the sputtering rate depending on the type of rare gas, and in this range, the sputtering rate and the deposition rate are irrelevant.

FIG. 12 is a diagram showing the N ₂ addition rate dependency of the deposition rate of titanium (Ti). Titanium (Ti) is used as a target to be supported by the cathode electrode 11, and the processing gas is Ar and a substrate having trenches or via holes having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. comparing the deposition rate of the thin film in the case where the Ne and N ₂ of N _2. From this figure, it can be seen that the use of Ne gas increases the deposition rate of the thin film. At this time, the pressure in the processing chamber is 7 Pa, and the power applied to the cathode electrode is 5000 W. In the film forming method of the present invention, the voltage applied to the cathode voltage is 200 V or less, that is, the ion energy is 200 eV or less. In the range of 200 eV or less, there is no difference in the sputtering rate depending on the type of rare gas, and in this range, the sputtering rate and the deposition rate are irrelevant.

  FIG. 13 is a diagram showing the anode power dependence of the bottom coverage ratio of copper (Cu). Copper (Cu) is used as a target to be supported by the cathode electrode 11, and the processing gas is only Ar on a substrate having a trench or via hole having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. The bottom coverage rate of trenches and via holes when Ne was added was compared. From this figure, it can be seen that the use of Ne gas increases the bottom coverage rate of trenches and via holes. At this time, the pressure in the processing chamber is 8 Pa, and the power applied to the cathode electrode is 4000 W. In the film forming method of the present invention, the voltage applied to the cathode voltage is 200 V or less, that is, the ion energy is 200 eV or less. In the range of 200 eV or less, there is no difference in the sputtering rate depending on the type of rare gas, and in this range, the sputtering rate and the deposition rate are irrelevant.

FIG. 14 is a diagram illustrating the aspect ratio dependency of the bottom coverage ratio of titanium (Ti). Titanium (Ti) is used as a target to be supported by the cathode electrode 11, and the processing gas is only Ar on a substrate having a trench or via hole having an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more. The bottom coverage rate of trenches and via holes when Ne was added was compared. From this figure, it can be seen that the use of Ne gas increases the bottom coverage rate of trenches and via holes. At this time, the pressure in the processing chamber is 14 Pa, and the power applied to the cathode electrode is 3200 W.

As described above, according to FIGS. 10 to 14, titanium (Ti) or copper (Cu) is used as a target supported by the cathode electrode 11, and Ar (argon) and Ne (neon) are used as processing gases in the reaction vessel 10. It was found that when the same gas was introduced, the deposition rate of the thin film on the bottom of the trench and via hole increased even when the same power was applied.

The reason why a mixed gas of Ar (argon) and Ne (neon) is introduced as the processing gas will be further described. It is considered that Ne is lighter than Ar, so that metal particles sputtered from the target collide with Ne and are more ionized. In particular, in the present invention, a plurality of magnets that form a point cusp magnetic field are arranged inside the cathode electrode that is the second electrode. For this reason, although it originally has a mechanism for generating high-density plasma, Ne is heavier than Ar by introducing a mixed gas of Ar (argon) and Ne (neon) into the processing chamber as a processing gas. It is considered that the metal particles sputtered from the target collide with Ne and are more ionized because of being light.

  Next, the thin film forming method of the present invention will be described. In the thin film forming method according to the present invention, first, the inside of the reaction vessel 10 is evacuated to a predetermined degree of vacuum by an exhaust system. Electric power is supplied to a heater (not shown) built in the substrate holder 15 to heat the substrate holder 15 to a set temperature.

  Next, a gate valve (not shown) disposed on the side wall of the reaction vessel 10 is opened to open the substrate transfer path. In this state, the substrate 17 is transferred to the upper surface of the substrate holder 15 using a transfer arm (not shown) such as a robot arm. Then, the substrate 8 is held on the substrate holder 15 by a holding mechanism (not shown). After the transfer arm is retracted, the gate valve is closed.

  After a heating time is allowed until the surface temperature of the substrate 17 reaches a predetermined temperature (for example, 900 ° C.), a processing gas having a predetermined flow rate is introduced from the gas introduction system 25. Further, the inside of the reaction vessel 1 is adjusted to an arbitrary pressure by an exhaust system conductance valve (not shown).

  Under the introduction of the processing gas, different electric power is applied to the second electrode 11 and the first electrode 15 from the high-frequency power source 19 and the high-frequency power source 8, and a cusp magnetic field is applied to the cathode electrode 11 (second electrode 11). Generate plasma to generate. By generating this plasma, a thin film of the target material is formed on the substrate 17 having the trench 31 or the via hole 32 having an opening width or an opening diameter of 3 μm or less and a step having an aspect ratio of 1 or more.

  As described above, in the thin film forming method according to the present invention, the thin film is formed on the substrate 17 having the trench 31 or the via hole 32 having a step having an opening width or an opening diameter of 3 μm or less and an aspect ratio of 1 or more. Applies when filming.

  Under the condition of the above power ratio, the power of the high frequency power supply 19 that supplies power to the cathode electrode 11 (second electrode 11) is selected and set in the range of 300 W to 10000 W, and the anode electrode 15 (first electrode 15). The power of the high frequency power supply 8 that supplies power is selected and set in the range of 0 W to 2000 W. Specifically, when the diameter (size) of the substrate 17 is 12 inches, it is desirable to set the cathode power in the range of 300 W to 10000 W and the anode power in the range of 0 W to 2000 W.

  As can be seen from the lower limit (0 W) of the anode power, the anode electrode 15 (first electrode) may be used in a grounded state.

  After depositing a predetermined film thickness, power supply from the high frequency power source 8 and the high frequency power source 19 is stopped. Further, the introduction of the processing gas from the gas introduction system 25 is stopped, the conductance valve of the exhaust system is opened, and the inside of the reaction vessel 10 is exhausted.

  Next, the gate valve is opened to open the substrate transfer path, the transfer arm is inserted to hold the substrate 17, the transfer arm is retracted, and the substrate 17 is unloaded from the reaction vessel 10. Finally, the gate valve is closed to complete the entire process. In addition, you may transfer to next processes, such as a reflow process, as it is.

  As described above, in the method for forming a thin film according to the present invention, a bias is applied to the anode electrode 15 on which the substrate 17 is placed while the target particles flying from the target are formed on the substrate 17. Thereby, ions of rare gas (mixed gas of argon and neon) in the plasma generated between the anode electrode 15 and the cathode electrode 11 are drawn into the anode electrode 15 and resputtered (etched) using the substrate 17 as a target. Therefore, there is no change in film quality that occurs in ECR plasma CVD.

  In this embodiment, since a mixed gas of argon and neon is used, the film quality can be maintained. Furthermore, the frequency of the high-frequency power source 19 of the cathode electrode 11 is in the range of 10 MHz to 300 MHz. Therefore, since the film can be formed at a high ionization rate in the first step, a large amount of film is attached to the bottom 33 of the trench 31 or the via hole 32 (step), and the inner wall 34 is hardly attached.

  As described above, according to the present invention, the bottom width 33 and the inner wall 34 of the trench 31 or the via hole 32 having a high aspect ratio with an opening width or opening diameter of 3 μm or less and an aspect ratio of 1 or more, particularly 1.5 or more. A barrier film can be formed on both sides with a sufficient film thickness. As a result, when the next step of Al reflow is performed, an extremely flat Al film can be formed without generating a void in the trench 31 or the via hole 32. Therefore, a planarization process such as a CMP (Chemical Mechanical Polishing) process can be omitted.

  The present invention can be applied not only to the magnetron sputtering apparatus illustrated but also to plasma processing apparatuses such as a dry etching apparatus, a plasma asher apparatus, a CVD apparatus, and a liquid crystal display manufacturing apparatus.

8, 19 High frequency power supply 10 Reaction vessel 11 Second electrode (top plate)
15 First electrode (basic holder)
17 Substrate 31 Trench 32 Via hole 33 Bottom 34 Inner side wall

Claims (8)

A film forming method for forming a thin film on a substrate having a trench or via hole having an opening width or an opening diameter of 3 μm or less and an aspect ratio of 1 or more,
In a processing chamber capable of being evacuated, a first electrode that supports a substrate, a second electrode that is disposed so as to face the substrate and supports a target, and is disposed outside the second electrode. A plurality of magnets for forming a cusp magnetic field inside the two electrodes,
A processing gas containing Ne is introduced into the processing chamber, high frequency power for plasma formation is supplied to at least one of the first electrode and the second electrode, and a cusp magnetic field is generated on the second electrode. Then, plasma is generated and a target material is formed on a substrate having a trench or a via hole.   2. The method of forming a thin film according to claim 1, wherein the pressure in the processing chamber is selected and set in a range of 2 Pa to 27 Pa.   The method of forming a thin film according to claim 1 or 2, wherein the frequency of the high-frequency power source of the second electrode is in the range of 10 MHz to 300 MHz.   The power of the high frequency power source of the second electrode is selected and set in a range of 300 W to 10000 W, and the power of the high frequency power source of the first electrode is selected and set in a range of 0 W to 2000 W. Item 4. The method for forming a thin film according to any one of Items 1 to 3.   5. The thin film forming method according to claim 1, wherein the second electrode is made of a material having a single composition or a composite composition having conductivity.   6. The process gas according to claim 5, wherein the processing gas is a mixed gas of a rare gas containing Ne and a reactive gas, and the reactive gas is at least one selected from a gas group consisting of oxygen and nitrogen. The thin film formation method described. The magnet is arranged at a position corresponding to each corner of a quadrangular quadrilateral in a grid pattern, and the magnets adjacent to each side of the quadrilateral have opposite polarities. The thin film forming method according to any one of claims 1 to 6. The method for forming a thin film according to any one of claims 1 to 7, wherein the first electrode is an anode electrode, and the second electrode is a cathode electrode.