JPS58197271A - Sputtering method of tantalum or the like - Google Patents

Abstract

PURPOSE:To prohibit abnormal electric discharge owing to charging up of oxide of Ta, etc. formed by fixing a target of Ta, etc. onto a backing plate of a cathode by means of belleville screws, etc. of the same material as the material of the target, maintaining the surface of the target at a high temp. and performing sputtering. CONSTITUTION:A target 2 consisting of Ta is fixed by means of screws 3 consisting of Ta to a backing plate 1 to decrease cooling efficiency deliberately. The surface of the target 2 is thus maintained at a high temp. and the excessive deformation of the target 2 is prevented. The Ta constituting the target 2 in this case is lower in m.p. and b.p. if it is oxide; therefore, the surface thereof can be maintained at a high temp. when the cooling efficiency is decreased by the screwing of the target 2. The Ta oxide formed by the reaction of O2 and Ta on the surface of the target 2 in this state is evaporated away from the surface of the target. The induction of abnormal discharge by the charge-up of the oxide is thus obviated and the stable discharge state is obtained even if large electric power is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an example of a method for sputtering a material such as tantalum, which has a lower melting point and boiling point than an oxide.

Usually, in a sputtering apparatus, a target is bonded to a backing plate of a cand to enhance the cooling effect. For example, in the case of mental sputtering, oxygen in the residual gas components reacts with tantalum to form tantalum oxide on the target surface. In DC magnetron sputtering, this oxide charges up and causes a series of abnormal discharges, resulting in target splash, pinholes in the sputtered film on the substrate, and the equipment itself becoming inoperable. . In particular, this abnormal discharge phenomenon becomes more severe as the input power increases. Therefore, in order to prevent such abnormal discharge from occurring, the
= 60mm).

Therefore, an object of the present invention is to mechanically attach a countersunk screw or the like made of the same material as the target to the backing plate of the entire cand of the target when performing sputtering using a target Th made of a substance whose melting point and boiling point are lower than that of an oxide, such as tantalum. It is an object of the present invention to provide a sputtering method for tantalum, etc., in which the entire surface of the target is kept at a high temperature and sputtering is performed four times, thereby preventing abnormal discharge due to charge-up of the oxide formed.

In addition to tantalum (melting point: 2,850°C, boiling point: approximately 4,100°C or higher, the melting point of its oxide Ta205 is 1,469°C), Mo
(Melting point 2617℃, its oxide MoO3 melting point 1068℃
) and W (melting point 6680°C, its oxide WO, melting point 1
743°C).

An example of a method for attaching a target using the method according to the present invention will be described below with reference to the drawings.

The drawing shows an assembly of a target and a cathode in a sputtering apparatus. In other words, in the drawing, reference numeral 1 is a backing plate for the cathode, and a target 2 made of tantalum is fixed onto this backing plate by screws 6 made of tantalum. Also, 4 is an earth shield. By attaching the target 2 with the screws 6 in this manner, the cooling efficiency is intentionally lowered to keep the surface temperature of the target high, and at the same time, excessive deformation of the target 2 is prevented. In the method according to the present invention, mechanical attachment means made of the same material as the target is used in principle, but when attachment means made of a different material from the target is used, it is necessary to mount it while avoiding sputtering erosion deposits. be.

In the illustrated embodiment, screws are used as means for attaching the target 2 to the backing plate 1 of the cathode, but screws in the form of wood screws, bolts, or other fastening member types may be used instead.

With this configuration, since the oxide of tantalum constituting the target 2 has a lower melting point and boiling point, the surface temperature of the target 2 is maintained at a high temperature by lowering the cooling efficiency by screwing the target 2. The tantalum oxide formed on the surface of the target by the reaction between oxygen and tantalum evaporates from the target surface and disappears. Therefore, the oxide does not charge up and induce abnormal discharge, and as a result, a stable discharge state is obtained even when a large amount of power is applied, that is, it is stable even at 5,000^/min or more.

As explained above, the method according to the present invention is applicable only to substances whose melting points and boiling points are lower than that of oxides, and as a general rule, it can be used instead of the target rotation by bonding that has been conventionally performed in this type of sputtering method. By attaching the target using mechanical attachment means such as screws made of the same material as the target, the cooling efficiency is intentionally lowered to keep the surface temperature of the target high and facilitate the evaporation of oxides formed by the reaction. This has the effect of preventing abnormal discharge due to oxide charge-up and preventing excessive deformation of the target.

[Brief explanation of drawings]

The drawing is a schematic cross-sectional view of a cathode target assembly implementing the method according to the invention. In the figure, 1: cathode backing plate, 2: target, 3: countersunk screw.

Claims (1)

[Claims] A method of sputtering a substance such as tantalum, whose oxide has a lower melting point and boiling point, is performed by attaching a target made of the above substance to the backing plate of a cand using a mechanical attachment means such as a countersunk screw made of the same material as the target. A sputtering method such as mental sputtering, which is characterized by performing sputtering while keeping the target surface at a high temperature while it is fixed.