JP4153768B2 - Sputtering equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the technical field of sputtering cathodes, and more particularly to a sputtering cathode in which arcing does not occur and a sputtering apparatus using the same.
[0002]
[Prior art]
The sputtering method is used in many fields such as LSI, FPD, hard disk, and resin coating as the most typical film forming method for forming a thin film having various characteristics.
[0003]
As shown in FIG. 7, the conventional sputter cathode 111 is configured by bonding a target material 114 on an electrically conductive backing plate 112 made of copper, aluminum or the like by an adhesive 113 such as indium. ing.
[0004]
However, as the target material _{114, SiN, SiO 2, TiN} , TiO x, AlN, Al 2 O 3, MgO, Pb (Zr, Ti) O 3 ( hereinafter abbreviated as _{PZT), SrBi 2 Ta 2 O} 9 ( hereinafter , SBT), (Ba, Sr) TiO ₂ (hereinafter abbreviated as BST), SrTiO ₃ (hereinafter abbreviated as STO), and oxygen and nitrogen are introduced together with the sputtering gas by introducing RF and nitrogen. When active sputtering or pulse DC reactive sputtering is performed, a thin film having a high resistance due to a constituent material of the target material 114 may be deposited on the surface of the target material 114, and the thin film may be charged up on the surface.
[0005]
When the charge-up occurred on the target surface as described above, the charge easily moves to the cathode side, causing arcing.
[0006]
Further, when the target material 114 is composed of a chalcogenite-based semiconductor composed of GeSe, GeTe, GeS, AsSe, AsTe, AgSe, AgTe, AgS, and a composite compound thereof, due to the difference in sputtering rate of each atom, etc. There is a problem in that arcs are generated as in the case where a high resistance material such as Se remains on the target surface and a high resistance thin film is deposited.
[0007]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problems and to provide a uniform thin film stably by reducing particles by preventing the occurrence of arcing.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes a vacuum chamber, a cathode electrode having electrical conductivity disposed in the vacuum chamber, and a target material attached to the cathode electrode. A sputtering gas and a reactive gas are introduced into the vacuum chamber, and when a thin film is formed on the surface of the substrate by reactive sputtering of the target material, a high-resistance thin film is formed on the surface of the target material, A sputtering apparatus in which a thin film is charged on the surface, and an electric insulation composed of diamond, sapphire, aluminum nitride, boron nitride, carbon nitride, or silicon carbide is provided between the cathode electrode and the target material. consisting 10μm following thin thickness 5μm or more with sexual insulating film of said target A sputtering apparatus in which a film is formed on one side and disposed, and the target material is insulated from the cathode electrode in terms of DC voltage.
The invention according to claim 2 is the sputtering apparatus according to claim 1 , wherein an RF voltage or a pulsed DC voltage is applied to the cathode electrode.
[0009]
The inventors of the present invention prevent the occurrence of arc discharge (arcing) by sandwiching a thin insulator between the target material and the cathode electrode, thereby suppressing the charge on the surface of the target material from moving to the cathode electrode side. Confirmed that it will be.
[0010]
The insulator used in the present invention is preferably a material having high resistivity and high thermal conductivity such as diamond, sapphire, aluminum nitride, boron nitride, carbon nitride, and silicon carbide.
[0011]
The insulator used in the present invention is desirably as thin as possible in order to improve the cooling efficiency of the target material. On the other hand, a thicker one is desirable from the standpoint of ensuring insulation. Therefore, it has been confirmed that a thickness of 5 μm or more is effective for the insulator of the present invention.
[0012]
The insulator of the present invention is manufactured by a sintering method or a pulling method, and is fixed by bonding with a low melting point and heat resistant material such as indium as an adhesive between the target material and the cathode electrode (backing plate). Can do.
[0013]
On the other hand, the insulator used in the present invention can be directly formed on the surface of the target material, the surface of the cathode electrode, or the surface of the adhesive by a film forming method such as coating, sputtering or CVD instead of bonding. is there.
[0014]
[Embodiments of the Invention]
Reference numeral 11 in FIG. 1 is a sputter cathode according to an example of the present invention, and reference numeral 21 indicates a sputtering apparatus having the sputter cathode 11.
[0015]
The sputter cathode 11 includes a cathode electrode 12, an insulator 13 disposed on one surface of the cathode electrode 12, and a target material 14 disposed on the insulator 13.
[0016]
The cathode electrode 12 is made of a metal material such as copper, and the insulator 13 is made of an aluminum nitride thin film having a constant thickness formed on one surface of the target material 14. Here, the thickness of the insulator 13 is 5 μm.
[0017]
An adhesive 15 made of indium is disposed between the insulator 13 and the cathode electrode 12, and the insulator 13 is bonded to the cathode electrode 12 by the adhesive 15, so that the target material 14 is attached to the cathode electrode 12. On the other hand, it is fixed.
[0018]
The sputtering apparatus 21 has a vacuum chamber 22. The sputter cathode 11 is disposed on the bottom surface side of the vacuum chamber 22 with the insulator 31 interposed therebetween with the surface on which the target material 14 is disposed facing upward.
[0019]
A substrate holder 33 is disposed on the ceiling side of the vacuum chamber 22 at a position facing the target material 14. An evacuation system 24 is connected to the vacuum chamber 22, a vacuum pump included in the evacuation system 24 is activated, the inside of the vacuum chamber 22 is evacuated to a predetermined pressure, and the substrate holder 33 is maintained while maintaining a vacuum atmosphere. A substrate 34 is attached to the substrate. This substrate 34 is here a silicon wafer.
[0020]
Next, sputtering gas and reactive gas are introduced into the vacuum chamber 22 from a gas cylinder connected to the gas introduction system 23.
[0021]
A power source 38 is connected to the cathode electrode 12 via a matching box 37. When the inside of the vacuum chamber 22 rises to a predetermined pressure, the power source 38 is activated and a pulse DC voltage or a high frequency voltage is applied to the cathode electrode 12. To do.
[0022]
Symbol L _{1 in} FIG. 2A indicates a voltage waveform of the pulse DC voltage, and a pulse voltage is superimposed on the negative voltage, and a positive voltage is generated only at the peak of the pulse.
[0023]
An insulator 13 is disposed between the cathode electrode 12 and the target material 14, and the cathode electrode 12 and the target material 14 are insulated in terms of DC voltage but connected in terms of AC voltage. Then, an AC component included in the output voltage (pulse DC voltage) of the power supply 38 is applied to the target material 14, and a mixed gas plasma of a sputtering gas and a reactive gas is generated near the surface of the target material 14.
[0024]
Here, argon gas is used as the sputtering gas, and oxygen gas is used as the reactive gas. The target material 14 is made of aluminum, and reactive sputtering is performed by plasma of a gas in which argon gas and oxygen gas are mixed, and an aluminum oxide thin film that is a product of the reaction grows on the surface of the substrate 34. . When the aluminum oxide thin film reaches a predetermined thickness, the sputtering operation ends.
[0025]
Next, a plurality of sputter cathodes having the same configuration as described above were prepared using insulators 13 (aluminum nitride) having different thicknesses of 1 μm to 10 μm. Then, reactive sputtering was performed using the sputter cathodes under the same conditions as described above, and aluminum oxide was grown on the substrate. The relationship between the number of arc discharges generated during the reactive sputtering and the film thickness of the insulator was investigated. The result is shown in the graph of FIG.
[0026]
When the film thickness of the insulator is increased, the number of arc discharges is reduced to zero at 5 μm. Therefore, it can be seen that the thickness of the insulator is desirably 5 μm or more. If the thickness is too large, the capacitance value of the capacitor composed of the target material, the insulator, and the cathode electrode becomes small, and the AC voltage component applied to the target material 14 becomes small.
[0027]
Next, as shown in FIG. 4, adhesives 55 a and 55 b made of indium are arranged on both surfaces of an insulator 53 made of SiC having a thickness of 1 mm, and a target material 54 made of BST is placed on the cathode electrode 52 at the most. A sputter cathode 51 was constructed by laminating the upper layer.
[0028]
The sputter cathode 51 was placed on the bottom surface of the vacuum chamber 22, argon gas and oxygen gas were introduced, a BST film was grown on the surface of the substrate 34 by reactive RF sputtering, and the number of arc discharges and the number of particles were measured. .
[0029]
The graph of the output voltage of the power supply 38 at this time is shown in the graph of FIG. The waveform of the output voltage of the curve L ₂ is the power supply 38, is sinusoidal. The average value of the output voltage is a negative voltage and is a positive voltage only for a short time.
[0030]
At this time, instead of the sputter cathode 51 of the present invention, a sputter cathode of the prior art that does not have an insulator and is in a state where the target material is electrically connected to the cathode electrode is similarly reactive. A BST film was grown by RF sputtering, and the number of arc discharges and the number of particles were measured.
[0031]
The measurement results are shown in FIGS. It can be seen that in the sputter cathode 51 of the present invention (when an insulator is present), arc discharge is suppressed and particles are reduced. Arc discharge is zero times for 300 times of the prior art, and 80 or less particles for 10,000 or more particles.
[0032]
As described above, in the sputter cathodes 11 and 51 of the present invention, since the charges of the target materials 14 and 54 do not move to the cathode electrodes 12 and 52, the number of arc discharges is small and particles are reduced.
[0033]
【The invention's effect】
The present invention can be used for the formation of wiring capacitors such as LSIs, FPDs, and micro devices, the production of magnetic films such as hard disks and CDs, protective films, and reflective films, and the coating of metals and resin films.
[Brief description of the drawings]
FIG. 1 shows an example of a sputtering cathode according to the present invention and an example of a sputtering apparatus using the same. FIG. 2 (a): a waveform of a pulse DC voltage (b): a waveform of an RF voltage. FIG. 4 is a graph showing the relationship between the number of arc discharges. FIG. 4 is another example of the sputter cathode of the present invention. FIG. 5 is a graph showing the relationship between the presence or absence of insulators and the number of arc discharges. A graph showing the relationship of the number of electrodes [FIG. 7] Sputter cathode of the prior art [Explanation of symbols]
11, 51... Sputter cathode 12, 52... Cathode electrode 13, 53... Insulator 14, 54.

Claims (2)

A vacuum chamber;
A cathode electrode having electrical conductivity disposed in the vacuum chamber;
A target material attached to the cathode electrode;
When a sputtering gas and a reactive gas are introduced into the vacuum chamber, and a thin film is formed on the substrate surface by reactive sputtering of the target material,
A sputtering apparatus in which a high-resistance thin film is formed on the surface of the target material, and the thin film is charged up on the surface,
Between the cathode electrode and the target material, a thin film having a thickness of 5 μm or more and 10 μm or less having an electrical insulating property made of diamond, sapphire, aluminum nitride, boron nitride, carbon nitride, or silicon carbide. A sputtering apparatus in which an insulating film is formed and disposed on one side of the target, and the target material is insulated from the cathode electrode in terms of DC voltage. The sputtering apparatus according to claim 1 , wherein an RF voltage or a pulsed DC voltage is applied to the cathode electrode.

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