JPH01165768A - Formation of film by reactive sputtering - Google Patents

Abstract

PURPOSE:To improve the adhesion of a film and to form the film having the desired characteristics with the film thickness or time by fixing the gas pumping speed, and changing the supply flow rates of an inert gas and/or an active gas with the film thickness or time. CONSTITUTION:A target 13 (metal) and a substrate 3 are arranged in a sputtering chamber 11 in opposition to each other, the inside of the chamber 11 is evacuated to a high vacuum, and the inert gas and active gas are introduced into the chamber 11 from respective inlets 14 and 16 through mass-flow controllers 15 and 17. When an electric discharge is started, a reactive insulating film 2 (oxide film and nitride film) incorporating a gaseous reactant molecule 4 is deposited on the substrate 3. The active gas flow rate is gradually decreased from the thickness or time 6, and finally diminished to zero at the thickness or time 5. In the region 7 between the times 6 and 5, the amt. of the molecule 4 to be incorporated into the film is gradually decreased in the thickness direction of the film, the interface 5 with the metal film 1 is not clear and forms a buffer layer, and the internal stress generated between the films 2 and 1 is relieved.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a film forming method using reactive sputtering.

[Conventional technology]

The conventional reactive sputtering film forming method is as shown in Figure 3(b) (the sputtering pressure is controlled without changing the gas exhaust speed and the flow rates of active gas and inert gas, regardless of film thickness or time). A common method is to keep the value constant.

[Problem that the invention seeks to solve]

However, in the prior art described above, when the reactive insulating film 2 and the metal film 1 are layered on the substrate 3 and deposited by sputtering as shown in FIG. However, there is a problem in that adhesion strength is reduced due to internal stress, etc. Note that 4 is a reactive gas molecule in the film.Therefore, the present invention is intended to solve these problems, and its purpose is to In reactive insulating film formation, the film quality is focused on obtaining good adhesion near the metal film interface by controlling the gas during sputtering, and obtaining an insulating film with desired characteristics depending on the film thickness or sputtering time. The purpose of the present invention is to provide a reactive sputtering method that can perform the following steps.

Means for Solving Problem c] The reactive sputtering film forming method of the present invention introduces an inert gas as a sputtering gas and an active gas such as oxygen or nitrogen into a vacuum chamber to form an oxide film or a nitride film. In the reactive sputtering method for forming films, the gas exhaust speed is assumed to be constant.
The method is characterized in that the film is formed while changing the flow rate of an inert gas, an active gas, or both introduced gases along with the film thickness or the large batter time.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. FIG. 1 is a configuration diagram of a sputtering apparatus. The target 13 and the substrate 12 are placed in opposing positions in the sputtering chamber 11, and the inert gas and active gas (reactive gas) are supplied through the inlet ports 14, 16 and 15, 17 (also possible with a barrier pull valve), respectively. and is led to the spanter chamber.

In this example, 7059 glass manufactured by Corning Corporation was used for the substrate 3, tantalum was used for the target 13, argon was used as the inert gas, and oxygen was used as the active gas (reactive gas).

First, the inside of the sputtering chamber 11 is made into a high vacuum, and then 80 SCCM of argon and oxygen are supplied to start discharge.

Then, a reactive insulating film (tantalum oxide) 2 containing reactive gas molecules 4 is deposited on the substrate 3, as shown in FIG. 2A.

Then, as shown in Figure 2, the flow rate of oxygen, which is a reactive gas, is gradually reduced from a certain film thickness or time 6, and finally the oxygen flow rate is brought to 0 at a certain film thickness or time 5. Between times 6 and 5, 7 becomes a layer in which the amount of reactive gas molecules (oxygen gas molecules) 4 taken into the film gradually decreases in the film thickness direction, and the interface 5 with the metal film 1 is not clear, so to speak. It becomes a buffer layer with the reactive insulating film (tantalum oxide) 2. This layer is a reactive insulator! Between (tantalum oxide) 2 and metal film 1,
Alleviates the force of peeling caused by internal stress.

Therefore, the adhesion is improved.

In this embodiment, tantalum was used for the metal film 1, but in the conventional method, peeling occurred between the reactive insulating film (tantalum oxide) 2 and the metal film (tankle) 1 just by leaving it after film formation. In comparison, the film formed by this method did not peel off even in a peel test using 3M Scotch tape, and good adhesion was obtained.

It should be noted that the present invention can be used not only for the purpose of improving adhesion, but also for making the change in energy level in the film a gentle slope.

〔Effect of the invention〕

As described above, according to the invention, by performing reactive sputtering by changing the introduced gas flow rate of inert gas, active gas, or both with sputtering time or film thickness while keeping the gas exhaust speed constant, It is possible to change the amount of reactive gas molecules taken into the film, and this has the effect of making it possible to perform laminated sputtering of an insulating film and a metal, which has conventionally been considered to have poor adhesion. It is also effective for softening the Schittky barrier at the film interface.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a sputtering apparatus according to the present invention. FIG. 2 1al is a model diagram of the film structure deposited on a substrate according to the present invention. Figure 2 (mountain) is a diagram showing changes in oxygen flow rate (oxygen partial pressure) with respect to film thickness in the present invention. FIG. 3 [a] is a model diagram of the film structure deposited on a substrate by a conventional method. Figure 3 (bl is a diagram showing the oxygen flow rate with respect to film thickness in the conventional method. 1...Metal film 2...Reactive insulating film 3...
Substrate 4...Reactive gas molecules 5...Interface between metal film and reactive insulating film 6...Arbitrary film thickness or time 7...Buffer layer 11 between metal film and reactive insulating film
...Spanter chamber 13...Target 14...Inert gas inlet 15...Inert gas mass flow controller 16...
・Active gas inlet 17...Active gas mass flow controller Fig. 1 Fig. 2 (IL) Fig. 2 Cb] Fig. 3 (a,) Fig. 3 (b)

Claims (1)

[Claims] (1) In the reactive sputtering method in which an oxide film or a nitride film is formed by introducing an inert gas as a sputtering gas and an active gas such as oxygen or nitrogen into a vacuum chamber, the gas exhaust speed is assumed to be constant. A reactive sputtering film forming method characterized by forming a film while changing the flow rate of an inert gas, an active gas, or both introduced gases with the film thickness or sputtering time.