JPS62117203A - Formation of dielectric thin film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention Field of Application to Industry The present invention relates to a method for forming a thin film by a sputtering method using a dielectric material as a target. -1L particle beam vacuum evaporation method, ion beam sputtering method, etc. are used. 1. In particular, the sputtering method has excellent electrical properties of the dielectric film formed, and furthermore, it is easy to form a thin film using a dielectric target using the RF magnetron sputtering method. It is used to form dielectric films for electroluminescent displays.

Problems to be Solved by the Invention However, when a dielectric thin film is formed from a dielectric target using a sputtering method, there are the following problems.

When sputtering particles are generated from a dielectric target to form a thin film on a substrate using the sputtering method, the dielectric film is deposited on the inner wall of the vacuum chamber and the target shield plate other than the substrate.
Eventually, it peels off and re-attaches to the substrate surface. At this time, the attached deposit becomes a foreign substance on the substrate and induces defects in the formed dielectric thin film. Such foreign substances increase the leakage current of the formed dielectric film, lower the dielectric strength voltage, and furthermore cause the formation of conductors, fireflies, etc.
When configured as a N moss L device, it may cause defects such as dielectric breakdown.

As a means of preventing the generation of foreign matter, there has been an attempt to cover the thin film deposition area in the vacuum chamber with the same material as the dielectric target except for the object to be deposited, but this is not practical.

As described above, the present invention reduces dielectric film deposition or adhesion of the dielectric film to a substrate, which has been a problem in the method of forming a dielectric thin film by sputtering using a dielectric target, An object of the present invention is to provide a method for forming a dielectric thin film with good electrical characteristics.

Means for solving the problem When forming a thin film by high frequency sputtering using a dielectric target, an auxiliary electrode having a negative bias potential with respect to the anode electrode is provided between the target and the substrate for sputter deposition. do.

When forming a thin film by sputtering using a working dielectric target, if an auxiliary electrode with a negative bias potential applied to the anode electrode is placed between the target and the substrate, the dielectric film that has adhered around the dielectric target will be removed. Since the deposit is electrically negatively charged, it is repelled by the auxiliary electrode with the same potential, and the neutral atoms and the desired dielectric material, which are extracted from the target surface by the sputtering gas, are deposited on the substrate. It becomes possible to form a uniform dielectric film to which particles are mainly attached and free of foreign matter.

Embodiment FIG. 1 schematically shows a sputtering apparatus in an embodiment of the dielectric thin film forming method according to the present invention. The auxiliary electrode 1 is supplied with voltage from -300V to +300V with respect to the anode electrode which is at the same potential as the ground by an external DC power supply 2.
A voltage of up to 1 is applied. A strontium titanate ceramic target is used as the target 3, and the substrate holder 8 on which the glass substrate 6 is installed is moved from targets 3 to 5.
The auxiliary electrode 1 is placed at a distance of 3.5 cm from the target. The substrate is heated by a heater 9 and maintained at 400'C. Next, a mixed gas of argon and oxygen is introduced into the vacuum chamber as a sputtering gas through the gas inlet 6, the gas pressure is set to 6 mTorr, and a high frequency voltage is applied to the ceramic target 3 using the RF power source 10 to perform sputtering. Form a strontium oxide thin film. At this time, the voltage V applied to the auxiliary electrode 1,
FIG. 2 shows the results of measuring the number N of electrically conductive foreign particles with a diameter of 2 μm or more adhering to the substrate using as a parameter (the scale of the vertical axis N is arbitrary). When the peak value of the high-frequency applied voltage of 1.5 KV as shown in Fig. 3 is applied to the target 3, the voltage V applied to the auxiliary electrode is equal to the potential of the anode (in this case, the same potential as the ground). If VC is positive, the number N of foreign particles increases as VC increases, but the auxiliary electrode voltage V
If r, is negative with respect to the anode potential, N decreases as VC, increases. Here, A in FIG. 2 is a case where the auxiliary electrodes are formed in a stripe shape, and B in FIG. 2 is a case in which the auxiliary electrodes are formed in a lattice shape. Note that the conducting wire used for the electrode configuration was a 0.5 mm tantalum wire. When the conductive wires are arranged in a stripe shape, the pitch is about smm, and the same is true for the lattice shape, so that they intersect at right angles at a pitch of 6 mm. As shown in FIG. 2, even when the auxiliary electrode voltage vG of the present invention is a negative voltage of about a factor of 10, which is a value smaller than the peak value of the target potential, the number of foreign particles is extremely small. was confirmed.

When the strontium titanate thin film formed by the method described above is used in combination with a manganese-activated zinc sulfide thin film as a thin-film electroluminescent device, it has been found that foreign particles of 2 μm or larger are generated when the dielectric thin film is attached. There was no dielectric breakdown and the light emitted stably.

As described above, according to the present invention, when forming a dielectric thin film by sputtering, by using an auxiliary electrode that is negatively biased with respect to the anode electrode (at the end and end positions), , a thin film with good properties can be easily formed.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a sputtering apparatus used in the method of forming a dielectric thin film according to the present invention, FIG. 2 is a performance diagram for explaining the present invention in detail, and FIG. FIG. 3 is a signal waveform diagram showing a target potential of a sputtering apparatus used in an example. 1... Auxiliary electrode, 2... DC power supply, 3...
Target, 4...Magnet, 5...
Board, 6... Scrap inlet, 7... Exhaust system, 8
・・・・・・Substrate holder, 9... ・Heater, 10
・・・・・・Name of RF main power supply agent Patent attorney Toshio Nakao and one other person Figure 1

Claims (1)

[Claims] In forming a thin film by a high frequency sputtering method using a dielectric as a target, an anode with a peak value of 0.1 times or more of the high frequency applied voltage applied to the cathode electrode on which the target is placed between the target and the substrate. A method for forming a dielectric thin film, characterized in that sputter deposition is performed by providing a ring-shaped, grid-shaped or striped auxiliary electrode having a negative potential with respect to the electrode.