JP4251713B2 - Sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sputtering apparatus, and more particularly to a magnetron sputtering apparatus used for forming a thin film in the manufacture of a semiconductor device, a liquid crystal display device or the like.
[0002]
[Prior art]
Thin films are conventionally used in various fields such as semiconductor devices and liquid crystal display devices, and various thin films such as metal thin films and magnetic thin films are formed by thin film forming apparatuses such as sputtering apparatuses and vapor deposition apparatuses. Yes.
Among them, the magnetron sputtering apparatus is widely used because it can form a thin film at a low temperature and at a high speed.
[0003]
An example of a conventional magnetron sputtering apparatus is indicated by reference numeral 101 in FIG. The magnetron sputtering apparatus 101 includes a vacuum chamber 102, a substrate holder 103, a target 104, an anode electrode 105, a mass flow controller 106, a vacuum exhaust device 107, a backing plate 108, an insulator 109, and a magnet 110. And an adhesion preventing plate 114.
[0004]
A substrate holder 103 is disposed on the inner bottom surface of the vacuum chamber 102. A deposition preventing plate 114 is disposed around the substrate holder 103.
A target 104 is disposed above the substrate holder 103, and the surface of the target 104 is opposed to the upper surface of the substrate holder 103.
[0005]
The back surface of the target 104 is fixed to the surface of a backing plate 108 made of a conductor, and the backing plate 108 is attached to the upper portion of the vacuum chamber 102 via an insulator 109.
[0006]
A magnet 110 is disposed on the back surface of the backing plate 108. FIG. 5B shows an enlarged cross-sectional view of the magnet, the backing plate, the target, and the anode electrode 105.
[0007]
The magnet 110 includes a columnar magnet 110a and a cylindrical magnet 110b, and the cylindrical magnet 110b is disposed so as to surround the columnar magnet 110a.
The surface 125 of the ring-shaped anode electrode 105 protrudes closer to the substrate holder 103 than the surface 124 of the target 104.
[0008]
A power source 111, a cooling water introduction device 112, a cooling water discharge device 113, and an exhaust device 107 are provided outside the vacuum chamber 102. Among them, the cooling water introduction device 112 and the cooling water discharge device 113 are connected to the backing plate 108 through water pipes, respectively, so that the cooling water can be passed through the backing plate 108 to cool the backing plate 108. Has been.
[0009]
Since one end of the power source 111 is connected to the backing plate 108 and the other end is grounded, and the anode electrode 105 and the deposition preventing plate 114 are grounded, when the power source 111 is activated, the backing plate 108, the anode electrode 105 and the anti-proofing plate A DC voltage can be applied between the platen 114 and the platen 114.
[0010]
The exhaust device 107 includes a turbo molecular pump 107a and a rotary pump 107b. The turbo molecular pump 107a is connected to the vacuum chamber 102, and the rotary pump 107b is connected to the turbo molecular pump 107a. When the rotary pump 107b is started, the inside of the vacuum chamber 102 can be evacuated.
[0011]
In order to form a thin film on the substrate surface with the above-described magnetron sputtering apparatus 101, first, the inside of the vacuum chamber 102 is evacuated to the ultimate vacuum degree by the exhaust apparatus 107, and then the sputtering gas is introduced through the mass flow controller 106. A substrate (not shown) is carried into the vacuum chamber 102 while maintaining the state at a pressure of about 0.1 Pa, and is held by the substrate holder 103, arranged so that the surface of the substrate faces the target 104, and the backing plate 108. Cooling water is passed through to prevent the backing plate 108 from being overheated.
[0012]
Next, the power supply 111 is activated to apply a DC voltage between the anode electrode 105 and the backing plate 108. Since the backing plate 108 is made of a conductor, a voltage is applied between the target 104 and the anode electrode 105, a glow discharge is generated therebetween, high density plasma is generated, and the target 104 is sputtered. The sputtered target material reaches the substrate surface, and a thin film made of the target material is formed on the substrate surface.
[0013]
In the magnetron sputtering apparatus 101 described above, the ionization efficiency of the plasma is improved by causing the electrons generated by the discharge to rotate while the electrons are accelerated near the surface of the target 104 by the magnetic field generated by the magnet 110. The film formation rate increases.
[0014]
However, in the above-described magnetron sputtering apparatus 101, when a DC voltage is applied between the anode electrode 105 and the backing plate 108 when the pressure in the vacuum chamber 102 is low, the potential of the target 104 rises above a predetermined value. As a result, the glow discharge is not stable and arc discharge is likely to occur. When arc discharge occurs, abnormal sputtering is performed, so that the film quality of the thin film formed on the substrate surface is deteriorated.
[0015]
Due to the circumstances as described above, the conventional apparatus can generate a stable discharge only at a pressure of 10 ⁻¹ Pa or less, but there is a strong demand to perform magnetron sputtering under a lower pressure condition. .
[0016]
[Problems to be solved by the invention]
The present invention was created to solve the above-described disadvantages of the prior art, and an object thereof is to provide a magnetron sputtering apparatus capable of generating a stable discharge even at a low pressure.
[0017]
[Means for Solving the Problems]
In order to solve the above problems, the invention described in claim 1 is a substrate holder disposed in the vacuum chamber, a target disposed such that a surface thereof faces the surface of the substrate holder, the target and a predetermined And a cylindrical anode electrode arranged around the target so as to surround the target, with the substrate held by the substrate holder, and between the target and the anode electrode A sputtering apparatus configured such that when a voltage is applied, the target material is sputtered to process the substrate, and the anode electrode protrudes from the surface position of the target toward the substrate holder. and the projection has, and a side portion located from the surface position of the target in the direction opposite to the substrate holder, the projections, the target table According terms vicinity toward the distal end direction of said projection, have a configured connection portions so the inner diameter is gradually increased, the radius of curvature of the cross section of the connecting portion is 1/30 or more of the diameter of the target It was made to become .
A second aspect of the present invention is the sputtering apparatus according to the first aspect, wherein the predetermined interval is in a range of 1.5 mm to 2.5 mm.
A third aspect of the present invention is the sputtering apparatus according to the first aspect of the present invention, further comprising a columnar magnet disposed on the back surface of the target and a cylindrical magnet. The cylindrical magnet is arranged around the columnar magnet so that a center axis thereof coincides with a center axis of the columnar magnet, and the columnar magnet and the cylindrical magnet are , And is configured to be rotatable around an axis different from the central axis.
[0018]
In a general magnetron sputtering apparatus, when a high voltage is applied between a target and an anode electrode to generate a magnetron discharge, high-density plasma is formed in the vicinity of the target surface. In the conventional magnetron sputtering apparatus, the surface of the cylindrical anode electrode protrudes from the surface of the target, the inner wall of the anode electrode approaches the high-density plasma, electrons flow easily to the anode electrode, and the plasma density decreases. Therefore, it was impossible to maintain the magnetron discharge at a low pressure (−10 ⁻² Pa).
[0019]
According to the sputtering apparatus of the present invention, the anode electrode has a ring-shaped side portion and a cylindrical protrusion, and the protrusion protrudes from the surface of the target, but its inner diameter is from the vicinity of the surface of the target. Within a predetermined distance range, it is gradually increased so that electrons hardly flow from the high-density plasma generated on the target surface to the anode electrode. Thereby, even at a low pressure, high-density plasma is generated on the target surface, and stable discharge is possible.
[0020]
In the present invention, the anode electrode may have a ring shape, and the surface of the target may be disposed between the surface of the substrate holder and the surface of the anode electrode. With this configuration, since the surface of the anode electrode does not protrude from the surface of the target, electrons do not flow easily from the high-density plasma to the anode. Can be generated.
[0021]
Furthermore, the magnet has a columnar magnet and a cylindrical magnet, and the cylindrical magnet is arranged around the columnar magnet so that the center axis thereof coincides with the center axis of the columnar magnet. The cylindrical magnet and the cylindrical magnet that are arranged may be configured to be rotatable around an axis different from the central axis thereof.
[0022]
With this configuration, since the magnetic field generated by the magnet rotates in a horizontal plane, the sputtered material can be sputtered from any part of the target surface, and the erosion can be made uniform compared to the conventional case. it can.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings. The vapor deposition apparatus of the present invention is indicated by reference numeral 1 in FIG. The vapor deposition apparatus 1 includes a vacuum chamber 2, a substrate holder 3, a target 4, an anode electrode 5, a mass flow controller 6, a vacuum exhaust device 7, a backing plate 8, an insulator 9, a magnet 10, And an adhesion preventing plate 14.
[0024]
A substrate holder 3 is disposed on the inner bottom surface of the vacuum chamber 2. An adhesion preventing plate 14 is disposed around the substrate holder 3 so as to surround the substrate holder 3.
A plate-like target 4 is disposed above the substrate holder 3, and the surface of the target 4 is opposed to the upper surface of the substrate holder 3. Around the target 4, an anode electrode 5 whose sectional view is shown in FIG. 1B is arranged at a predetermined distance from the target 4. Here, the diameter of the target 4 is 50 mm, and the distance between the anode electrode 5 and the target 4 is 1.5 mm.
[0025]
The back surface of the target 4 is fixed to the front surface of the backing plate 8, and the backing plate 8 is attached to the upper portion of the vacuum chamber 2 through an insulator 9. A magnet 10 is disposed on the back surface of the backing plate 8.
[0026]
As shown in the enlarged sectional view of FIG. 2A, the magnet 10 has a columnar magnet 10a and a cylindrical magnet 10b. The cylindrical magnet 10b is arranged around the columnar magnet 10a. Is arranged so as to surround.
[0027]
The anode electrode 5 has a ring-shaped side portion 5a and a cylindrical projection 5b, and the side portion 5a is formed in a ring shape. The outer wall surface of the protrusion 5 b is formed in a cylindrical shape, and the interface 25 between the protrusion 5 b and the side part 5 a is substantially flush with the surface 24 of the target 4.
[0028]
The protrusion 5b has a connection part 51 and a tip part 52 as shown in cross section in FIG. The cross section of the inner wall surface of the connecting portion 51 is a curve that makes the curvature radius ΔR constant as shown in FIG. 2B, and the inner diameter of the connecting portion 51 increases toward the substrate holder 3 side. It has been gradually increased. Here, the curvature radius ΔR of the cross section of the connecting portion 51 is 2 mm. On the other hand, the front end portion 52 is provided from the connection portion 51 toward the substrate holder 3 side, and the cross section of the inner wall is substantially linear.
[0029]
A power source 11, a cooling water introduction device 12, a cooling water discharge device 13 and an exhaust device 7 are arranged outside the vacuum chamber 2. Among them, the cooling water introduction device 12 and the cooling water discharge device 13 are connected to the backing plate 8 through water pipes, and cool the backing plate 8 by passing cooling water into the backing plate 8. It has been made possible.
[0030]
Since one end of the power supply 11 is connected to the backing plate 8 and the other end is grounded, and the anode electrode 5 and the adhesion preventing plate 14 are grounded, when the power supply 11 is activated, the backing plate 8, the anode electrode 5 and the anti-proofing plate are connected. A DC voltage can be applied between the platen 14 and the platen 14.
[0031]
The exhaust device 7 includes a turbo molecular pump 7a and a rotary pump 7b. The turbo molecular pump 7a is connected to the vacuum chamber 2, and the rotary pump 7b is connected to the turbo molecular pump 7a. When the rotary pump 7b is activated, the vacuum chamber 2 can be evacuated.
[0032]
In order to form a thin film on the substrate surface with the magnetron sputtering apparatus 1 described above, first, the vacuum chamber 2 is first evacuated to about 10 ⁻⁶ Pa by the exhaust device 7 and the vacuum chamber is maintained in a vacuum state. The substrate is loaded into the substrate 2 and held by the substrate holder 3, arranged so that the surface of the substrate faces the target 4, and cooling water is passed through the backing plate 8 so that the backing plate 8 is not overheated. deep.
[0033]
Next, a process gas is introduced, the pressure in the vacuum chamber 2 is controlled at about 10 ⁻² Pa, the power source 11 is activated, and a DC voltage is applied between the anode electrode 5 and the backing plate 8. . Then, a voltage is applied between the anode electrode 5 and the target 4 to cause glow discharge, and high-density plasma is generated to sputter the target 4. The sputtered target material receives a force perpendicular to the direction of motion by the magnetic field formed by the magnet 10 disposed on the back surface of the target 4, reaches the substrate surface while performing a spiral motion, and a thin film is formed on the substrate surface. Be filmed. Electrons generated by the discharge are rotated in the vicinity of the surface of the target 4 while the electrons are accelerated by the magnetic field generated by the magnet 10, thereby improving the ionization efficiency of the plasma.
[0034]
According to the magnetron sputtering apparatus 1 of the present embodiment, although the protrusion 5b protrudes from the surface of the target, the protrusion 5b is provided with the connecting portion 51, and the cross section of the inner wall surface of the connecting portion 51 is In the vicinity of the portion 5a, as shown in FIG. 2 (b), a curve with a constant curvature radius ΔR is drawn to make it difficult for electrons to flow from the high-density plasma generated on the target surface to the anode electrode. High-density plasma can be generated even under pressure, and stable discharge can be maintained.
[0035]
As described above, in the magnetron sputtering apparatus 1 of the present embodiment, since the high-density plasma is stabilized even under a low pressure condition as compared with the conventional case, a stable magnetron discharge can be maintained.
[0036]
In order to confirm the effect of the present invention, the inventors of the present invention use the conventional magnetron sputtering apparatus 101 and the magnetron sputtering apparatus 1 having the above-described configuration in a state where the pressure in the vacuum chamber is lowered. The voltage applied between the anode electrode and the backing plate (hereinafter referred to as the discharge voltage) was varied, and the discharge state was examined.
[0037]
The results are shown in curves (A) and (B) in FIG. A curve (A) shows an experimental result by the conventional magnetron sputtering apparatus 101, and a curve (B) shows an experimental result by the magnetron sputtering apparatus 1 described above.
[0038]
From the curve (A), it can be seen that the conventional magnetron sputtering apparatus 101 could generate a stable discharge only up to about 0.1 Pa when the pressure was lowered. On the other hand, in the magnetron sputtering apparatus 1 of the present embodiment, as shown by the curve (B), it can be seen that stable discharge can be generated even if the pressure is reduced to 0.05 Pa.
[0039]
Curves (C) and (D) in FIG. 3B show the relationship between the current flowing through the target during discharge (hereinafter referred to as the cathode current) and the discharge voltage. Curve (C) shows the experimental results of the conventional magnetron sputtering apparatus 101, and curve (D) shows the experimental results of the magnetron sputtering apparatus 1 of the present embodiment.
Comparing curve (C) and curve (D), it can be seen that curve (D) has a larger cathode current and a stable discharge can be obtained at the same discharge voltage.
[0040]
As described above, it has been confirmed that the magnetron sputtering apparatus 1 of the present embodiment can obtain a stable discharge up to about 10 ⁻² Pa, which is a lower pressure than the conventional one.
[0041]
The present invention is not limited to the magnetron sputtering apparatus 1 as shown in FIG. 1 (a), and has an anode electrode 15 formed in a ring shape as shown in FIG. You may make it the structure that 35 does not protrude from the surface 24 of the target 4. FIG.
[0042]
With this configuration, since the surface 35 of the anode electrode 15 does not protrude from the surface of the target 4, electrons do not flow easily on the inner wall of the anode electrode, and high-density plasma formed on the surface of the target 4 can be stabilized. The stable magnetron discharge can be maintained even under a low pressure.
[0043]
4B, the central axis 40 of the magnet 20 is arranged so as to be different from the central axis 30 of the target 4, and the magnet 20 is placed in a horizontal plane around the central axis 30 of the target 4. You may make it the structure which rotates. By comprising in this way, the magnetic field which the magnet 20 produces | generates rotates in a horizontal surface, a sputter | spatter material can be sputtered uniformly from the target surface, and erosion can be made uniform.
[0044]
Furthermore, in the above-described embodiment, the curvature radius ΔR of the inner wall cross section of the connection portion 51 is set to 2 mm, but the inventors of the present invention set the curvature radius ΔR to 1/30 or more of the diameter of the target, As in the above embodiment, it was confirmed that stable discharge was obtained under low pressure conditions.
[0045]
In the above embodiment, the distance d ₁₁ between the anode electrode and the target shown in FIG. 2 (b), was a 1.5 mm, the inventors of the present invention, 1.5 mm or more 2.5mm or less It was confirmed that it was in the range of.
[0046]
【The invention's effect】
A stable magnetron discharge can be obtained under low pressure conditions.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view illustrating a magnetron sputtering apparatus according to an embodiment of the present invention.
(b): Cross-sectional view illustrating an anode electrode according to an embodiment of the present invention. [FIG. 2] (a): Cross-sectional view illustrating an essential part of an embodiment of the present invention.
(b): Cross-sectional view for explaining a connecting portion of an embodiment of the present invention. FIG. 3 (a): A vacuum chamber for each of a magnetron sputtering apparatus according to an embodiment of the present invention and a conventional magnetron sputtering apparatus. Graph showing the relationship between internal pressure and discharge voltage
(b): A graph showing the relationship between the cathode current and the discharge voltage for each of the magnetron sputtering apparatus of one embodiment of the present invention and the conventional magnetron sputtering apparatus. FIG. 4 (a): Others of the present invention. Sectional drawing explaining the magnetron sputtering apparatus of embodiment of this
(b): Cross-sectional view illustrating a magnetron sputtering apparatus according to another embodiment of the present invention. FIG. 5 (a): Cross-sectional view illustrating a conventional magnetron sputtering apparatus.
(b): Cross-sectional view explaining the main part of a conventional magnetron sputtering apparatus
DESCRIPTION OF SYMBOLS 1 ... Magnetron sputtering device 2 ... Vacuum chamber 3 ... Substrate holder 5 ... Anode electrode 5a ... Side part 5b ... Projection 10 ... Magnet (magnet) 51 ... Connection part

Claims (3)

A vacuum chamber;
A substrate holder disposed in the vacuum chamber;
A target arranged such that the surface faces the surface of the substrate holder;
A cylindrical anode electrode disposed around the target so as to surround the target at a predetermined interval from the target;
A sputtering apparatus configured to process the substrate by sputtering the target material when a voltage is applied between the target and the anode electrode while the substrate is held by the substrate holder. And
The anode electrode has a protrusion protruding in the direction of the substrate holder from the surface position of the target, and a side portion positioned in the direction opposite to the substrate holder from the surface position of the target,
The protrusion, in accordance with direction from the target surface position near the distal direction of the projection, have a configured connection portions so the inner diameter is gradually increased,
The sputtering apparatus according to claim 1, wherein a radius of curvature of a cross section of the connection portion is set to 1/30 or more of a diameter of the target . The sputtering apparatus according to claim 1 , wherein the predetermined interval is in a range of 1.5 mm to 2.5 mm. A columnar magnet disposed on the back surface of the target, and a cylindrical magnet;
The cylindrical magnet is disposed around the columnar magnet so that a center axis thereof coincides with a center axis of the columnar magnet,
The sputtering apparatus according to claim 1, wherein the columnar magnet and the cylindrical magnet are configured to be rotatable about an axis different from a central axis thereof.

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