JPS6353260A - Reactive sputtering device - Google Patents

Abstract

PURPOSE:To uniformize the compsn. of a film by providing a means for joining and mixing a reactive gas and sputtering gas to the front stage of a gas introducing port of a sputtering vacuum vessel so that the atmospheric gas at the time of sputtering has a uniform gas ratio. CONSTITUTION:An introducing pipe 11A for the sputtering gas and an introducing pipe 11B for the reactive gas are coupled to each other just before the gas introducing port 13 to the sputtering vacuum vessel 12 to form the confluent part 111 of both gases. The diameter and average pressures of the respective pipes 11A, 11B are adjusted to provide an approximately viscous flow region from valves 15A, 15B up to the gas introducing port 13. The sputtering gas and reactive gas joined to each other in the confluent part 111, therefore, generate turbulent flow and are satisfactorily mixed with each other. The gaseous mixture fills the inside of the vacuum vessel 12 while maintaining the specified mixing ratio. The sputtered film uniformly contg. the reactive gaseous component is formed by the above-mentioned mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a reactive sputtering apparatus used in semiconductor processes and the like.

[Conventional technology]

Reactive sputtering generally uses Ns, On as a reactive gas.
Ar, Xe, Ne, K, etc. are used as the sputtering gas.
This is carried out using an inert gas such as r.

FIG. 5 shows a conventionally used reactive sputtering apparatus. The sputtering gas container and the reactive gas ◎ are supplied to the gas inlets 3A and 3BK of the sputtering vacuum chamber 2 through separate introduction pipes IA and IB, respectively. 4A and 4B are mass flow controllers, 5A and 5B are stop pulps, 6 is a target, 7 is a substrate placed facing this, 8 is a power source, 9 is a conductance pulp, and 10 is an exhaust device O sputter vacuum chamber 2 The pressure inside is maintained at about jPa. The introduced gas has a short mean free path of gas molecules inside the introduction tube 1B and maintains a viscous flow state, but inside the sputtering vacuum chamber 2, the mean free path of gas molecules increases, This results in an intermediate flow state between molecular flow and viscous flow.

Here, each state of viscous flow, molecular flow, and intermediate flow is defined as follows in relation to the diameter d of the circular tube and the pressures Pi and Pl at both ends thereof. For air at a temperature of 20°C, when the product of the average pressure inside the circular pipe P==(Px+Ps/2) and the pipe diameter d is greater than 0.8 (unit: Pa-m), it is called viscous flow. When the flow is less than .02, it is called molecular flow, and when it is in between, it is called intermediate flow. In the viscous flow region, viscosity is maintained and a laminar flow is formed. On the other hand, in the molecular flow region, the mean free path of gas molecules is extremely large, and no laminar flow is formed.

In the intermediate flow region, properties are intermediate between the two, and laminar flow is incompletely formed.

[Problem that the invention seeks to solve]

In the conventional reactive sputtering apparatus described above, when a reactive gas is introduced into the sputtering vacuum chamber 2, the reactive gas maintains a viscous flow property, so that the sputtering vacuum chamber 2 is not uniformly filled. First, mixing with the sputtering gas becomes insufficient, and the concentration of the reactive gas becomes non-uniform within the sputtering vacuum chamber 2. For example, AJN, TiN, TaN, WN films formed by reactive sputtering using Ns gas.
, MoN.

Regarding 8iN, etc., the nitrogen concentration distribution in the film surface and in the thickness direction is non-uniform), which significantly impairs the reliability of the film quality.

[Means for solving problems]

The reactive sputtering apparatus of the present invention is a merging mixture in which a reactive gas and a sputtering gas, which are supplied through separate introduction pipes, are brought together in a viscous flow state to form a turbulent flow upstream of a gas inlet of a sputtering vacuum chamber. It has a section.

[Effect]

After the reactive gas and the sputtering gas are thoroughly mixed with each other in the confluence mixing section, they are introduced into the sputtering vacuum chamber.

〔Example〕

FIG. 1 is a distribution system diagram showing one embodiment of the present invention. In the figure, 11A is an introduction pipe for sputtering gas such as Ar, Ne, Kr, Xe, etc., 11B is an introduction pipe for reactive gas such as Ns, (h, etc.), and similarly to FIG. 5, the mass flow controller 14A, 14B and stop pulps 15A and 15B are inserted.The point that is markedly different from FIG. Merging part 11 of sputtering gas (e) and reactive gas 0
1. 1B is a sputtering target; 17 is a substrate to be adhered to which is placed facing the frame; 1
8 is a power source, 19 is a fundacance valve, and 20 is an exhaust device such as an oil diffusion pump or a cryopump, which are the same as those shown in FIG.

Here, the sputtering gas is usually 10 to 11008 CC.

The reactive gas flows through the mass flow controllers 14A, 14B and the stop pulp 1 at a flow rate of about 1 to 50 SCCM.
It flows through 5A and 15B. At this time, introduction pipe 1
If the pipe diameter of 1A and 11B is about 5 to 20 nm' and the average pressure inside the pipe is about 100 Pa, pulp 15A and 15
The region from B to the gas inlet 13 is almost in a viscous flow region. Therefore, the sputtering gas and the reactive gas that have joined together in a viscous flow state at the joining part 111 generate turbulent flow and are sufficiently mixed with each other.

The inside of the sputtering vacuum chamber 12 is normally maintained at about 0.3 to 3 Pa and is in the intermediate flow region. At this time, the sputtering gas and the reactive gas fill the interior of the sputtering vacuum chamber 12 while maintaining a constant mixing ratio, so that a sputtered film uniformly containing the reactive gas components can be obtained.

FIG. 2 shows the results of measuring the N3 concentration in the sputtered film when Ar was used as the sputtering gas, Ns was used as the reactive gas, and Mo was used as Targetera F. As shown in FIG. 5, in the case of sputtering using the conventional apparatus, the Ns content in the film was unevenly distributed as shown by the broken line I in the figure, whereas in the case of sputtering using the apparatus of this embodiment, In the film, it is uniformly distributed as shown by the solid line ■. Although the figure shows the distribution within the coating surface, according to this example, uniform distribution can be obtained in the thickness direction as well.

If the length of the mixing part 112 from the confluence part 111 of the reactive gas and sputtering gas to the gas inlet 13 to the sputtering vacuum chamber 2 is 1OcIn8 degrees or more, the mixing effect can be obtained, but in addition, If the piping is fitted with, for example, linear piping as shown in Figure 3, or a reservoir type mixer as shown in Figure 4, more turbulence will occur, further promoting gas mixing, and - A sputtered coating with a uniform layer can be obtained. Note that the arrows in the figure indicate the flow of gas.

The reactive gas and the sputtering gas are not limited to one type each, and the present invention is similarly applicable to the case where three or more types of gases are used. In that case, for example, if three types of gas are used, each gas may be combined at once, or two gases may be combined and then another gas may be combined with the inlet pipe for each gas. may be combined.

〔Effect of the invention〕

As explained above, according to the present invention, by merging reactive gas and sputtering gas in a viscous flow state, turbulent flow is generated, uniform mixing is promoted, and atmospheric gas during sputtering is becomes a uniform gas ratio. Therefore, the obtained sputtered film contains the reactive gas uniformly in the film surface and in the thickness direction, making the film composition uniform and improving its reliability.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram showing one embodiment of the present invention, FIG. 2 is a diagram showing the distribution of N3 content within the sputtered coating surface,
FIGS. 3 and 4 are a perspective view and a sectional view showing other configuration examples of the mixing section, respectively, and FIG. 5 is a piping system diagram showing a conventional example. 11A, 11Bφ・War φGas inlet pipe, 12...e sputtering vacuum chamber, 13・@Tatami・Gas inlet, 111・FistφΦ
Merging section, 112...mixing section.

Claims (1)

[Claims] In a reactive sputtering apparatus equipped with a sputtering vacuum chamber and an introduction tube for supplying a reactive gas and a sputtering gas into the sputtering vacuum chamber, the reactive gas and the sputtering gas are supplied through separate introduction tubes, respectively. A reactive sputtering apparatus characterized in that a merging and mixing section for merging viscous flows to form a turbulent flow is provided upstream of a gas inlet of a sputtering vacuum chamber.