JPH0375629B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to reactive sputtering equipment.

(Prior art) Among the physical vapor deposition methods (PVD), the sputtering method is used to form various thin films.In particular, if the reactive sputtering method is used, TiN,
Ceramic thin films such as TiO ₂ can be formed.

As a reactive sputtering device, there is one shown in FIGS. 6 and 7, and in this device, a container 26
Inside, a cathode 27 and an anode 28 are disposed facing each other, and a target 29 and a base 30 are provided on the cathode 27 and anode 28, respectively. 31 is a shutter.

An exhaust pipe 32 is connected to the container 26 for discharging the gas inside the container 26, and in the case shown in FIG. 6, an inert gas such as Ar and a reactive gas such as N ₂ are mixed. Gas is introduced from the side wall of the container 26 via a mixed gas supply pipe 33.

In the system shown in FIG. 7, an inert gas is supplied to the vicinity of the target 29 and a reactive gas is supplied to the vicinity of the substrate 30 by an inert gas supply pipe 34 and a reactive gas introduction pipe 35, respectively.

In the above device, the material of the target 29, for example, pure Ti, is evaporated by sputtering with inert gas ions such as Ar, and a small amount of N ₂ gas is introduced as a reaction gas, so that Ti and N ₂ react. As a result, a thin film of TiN is formed on the substrate 30.

What is important in this reactive sputtering apparatus is to uniformly distribute the reactive gas in order to form a thin film with a uniform composition.

(Problems to be Solved by the Invention) In the above device, there is no problem if the base body 30 is a flat plate, but if the base body 30 is a cylinder and a thin film is to be formed on the inner surface of the base body 30,
Since the reactive gas is supplied from the outside into the interior of the base 30, the reactive gas is not uniformly supplied inside the base 30 in the axial direction, and the concentration of the reactive gas is inevitably much higher at both ends of the base 30 than at the center. Therefore, there was a problem that a thin film having a uniform composition could not be formed on the inner circumferential surface of the substrate 30.

For example, when a TiN thin film is formed on the inner circumferential surface of the base 30, the TiN thin film is formed in a range of 30 to 50 mm at both ends of the base 30, but on the part of the base 30 other than the above-mentioned ends. A thin film consisting almost only of Ti is formed.

This is because the N ₂ gas reacts and is consumed at both end regions inside the base 30, and the N ₂ gas does not sufficiently reach the center inside the base 30.

An object of the present invention is to provide a reactive sputtering device that can solve the above problems.

(Means for Solving the Problems) In order to solve the above problems, the present invention employs a method in which a cylindrical base 8 is fitted concentrically around the target 2, and in an inert gas atmosphere, A glow discharge is generated between the target 2 and the substrate 8, causing the material of the target 2 to sputter and evaporate;
In a case where a compound of the vaporized material of the target 2 and the reaction gas inside the substrate 8 is formed as a thin film on the inner circumferential surface of the substrate 8, a reaction gas introduction pipe 12 is provided inside the substrate 8 over the entire length in the axial direction of the substrate 8. is arranged parallel to the axis of the base body 8, and an outflow hole 13 is formed in a portion of the introduction tube 12 inside the base body 8 to allow the reaction gas to flow out almost uniformly from the entire length in the axial direction of the inlet tube 12. At the point.

(Function) When a thin film is formed on the inner peripheral surface of the substrate 8, glow discharge is generated between the target 2 and the substrate 8 in an inert gas atmosphere, and the material of the target 2 is sputtered and evaporated.

Then, a reactive gas is supplied into the base 8 from the reactive gas inlet pipe 12, and this reactive gas reacts with the evaporated material of the target 2 to form a compound as a thin film on the inner circumferential surface of the base 8. Ru.

In this case, the introduction tube 12 is inserted into the base body 8 and extends over the entire length of the base body 8 in the axial direction,
An outflow hole 13 is formed in a portion of the introduction tube 12 in the base body 8 to allow the reaction gas to flow out almost uniformly over the entire length of the portion in the axial direction. The reactant gas can be supplied substantially uniformly over the entire surface of the substrate 8, and a thin film having a substantially uniform composition can be formed over the entire surface of the substrate 8.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described based on the drawings of FIGS. 1 to 3. In FIG. 1, numeral 1 denotes a container, which also serves as an anode.

2 is a cylindrical target made of pure Ti, etc.
It is inserted into the bottom of the container 2 and stands upright.
The target 2 is also used as a cathode, and a power source 3 is connected to the target 2 and the container 1.

A turntable 4 is fitted concentrically to the lower part of the target 2 and supported by the container 1 via a bearing 5.

A toothed portion is formed on the outer circumference of the turntable 4, and an electric motor 7 is connected to this toothed portion via a gear 6.
are interlocked and connected, and the turntable 4 is rotationally driven by the drive of the electric motor 7.

Reference numeral 8 denotes a cylindrical base body, which is removably mounted on the turntable 4 and is fitted around the target 2 concentrically.

Reference numeral 9 denotes an exhaust pipe, which is connected to the container 1 and is used to exhaust gas inside the container 1 .

Reference numeral 11 denotes an inert gas supply pipe, which is connected to the side wall of the container 1 and supplies an inert gas such as Ar gas into the interior of the container 1.

Reference numeral 12 denotes a reaction gas introduction tube, which supplies a reaction gas such as N ₂ gas or O ₂ gas into the inside of the base 8. It is inserted through the side wall of the container 1, and its tip end is bent. As shown in Figure 2, the base 8
It is inserted into the interior parallel to the axis of the base body 8 and extends over the entire length of the base body 8 in the axial direction.

Then, the introduction pipe 12 has an outer diameter of 5 to 10 mm, for example.
It is a hollow pipe with a wall thickness of 0.5 to 1 mm, and the tip is sealed. Further, the distance l between the axis of the introduction tube 12 and the outer circumferential surface of the target 2 is approximately 1/3 to 2/5 of the distance L between the outer circumferential surface of the target 2 and the inner circumferential surface of the base 8.
For example, L is 20mm and L is 6.2 to 8.2mm.
It is said that

As shown in FIG. 3, the portion of the introduction tube 12 inside the base body 8 has a large number of outflow holes 13 extending in the axial direction to allow the reaction gas to flow out almost uniformly over the entire length of the portion in the axial direction. They are arranged at equal pitches.

The diameter of the outflow hole 13 is, for example, 0.5 to 1.0 mm, and the pitch thereof is 10 to 40 mm.

As shown in FIG. 2, when viewed from the axial direction of the target 2, the axial center of the introducing tube 12 is located on a circumference 15 that passes through the axial center of the introducing tube 12 and is centered on the axial center of the target 2. When a tangent line 16 is drawn, the outflow hole 13 is directed toward a region 18 on the opposite side of the target 2 from the tangent line 16.

According to the embodiment configured as described above, the base 8
When forming a thin film of TiN on the inner circumferential surface, the target 2 is made of pure Ti, and the base 8 is rotated by the electric motor 7 by rotating the turntable 4 in the state shown in FIG. While rotating, Ar gas is supplied to the inside of the container 1 from the inert gas supply pipe 11 to create an Ar gas atmosphere inside the container 1, and _N2 gas is supplied to the inside of the substrate 8 from the reaction gas introduction pipe 12. , from the outflow hole 13 toward the inner circumferential surface of the base body 8.

In this state, when a glow discharge is generated between the target 2 and the substrate 8, pure Ti, which is the material of the target 2, is sputtered and evaporated by Ar gas ions, which reacts with the N ₂ gas to form Ti and N ₂ A thin film of TiN, which is a compound, is formed on the inner peripheral surface of the base 8.

In this case, the tip of the introduction tube 12 is inserted into the base 8 and extends over the entire axial length of the base 8, and the portion of the introduction tube 12 inside the base 8 has a approximately uniformly over
Since a large number of outflow holes 13 are formed to allow N ₂ gas to flow out, N ₂ gas can be supplied almost uniformly over the entire length of the base 8 in the axial direction, and the N 2 gas can be supplied to the inner peripheral surface of the base 8 over the entire surface. A thin film of TiN with a substantially uniform composition can be formed.

Although the substrate 8 was rotated when forming the thin film, this was done in order to form a thin film with a more uniform composition, and there is no need to rotate the substrate 8 separately.

By the way, the reason why the distance l between the axis of the introduction tube 12 and the outer peripheral surface of the target 2 is set to 1/3 to 2/5 of the distance L between the outer peripheral surface of the target 2 and the inner peripheral surface of the base 8 is as follows. by.

That is, if the introduction tube 12 is brought too close to the target 2, the glow discharge becomes unstable, and if the introduction tube 12 is brought too close to the inner peripheral surface of the base 8, the introduction tube 12 blocks the sputtering particles, causing the inner peripheral surface of the base 8 to become unstable. A shadow is formed.

Therefore, considering these circumstances, the introduction pipe 12
The position of is set as above.

Further, the diameter of the outflow hole 13 of the introduction pipe 12 is determined as follows.

That is, in order to obtain a substantially uniform flow of the reactant gas such as N ₂ gas from each outlet hole 13, () the flow of the reactant gas within the introduction pipe 12 is made to be a viscous flow;

() The flow of reaction gas from each particle hole 13 is brought into a critical state.

There is a need for this.

The reason for the above () is that if there is a molecular flow,
This is because most of the reaction gas comes out from the outflow hole 13 near the gas source, and almost no reaction gas flows out from the outflow hole 13 at the tip end of the introduction tube 12.

Moreover, the reason for the above () is that if the introduction pipe 12 becomes longer if the introduction pipe 12 is not in a critical state, the introduction pipe 12 becomes longer.
Due to the pressure loss within the inlet tube 12, the back pressure at each outlet hole 13 location will be different, resulting in a greater flow of reactant gas from each outlet hole 13 closer to the gas source. In order to avoid this, the flow of the reaction gas from each outflow hole 13 is set to a critical state, so that the flow rate of the reaction gas can basically be determined only by the cross-sectional area of the outflow hole 13.

By the way, if you consider the points () and () above,
The inner diameter of the introduction tube 12 is 5 mm, and the flow rate of the reaction gas is
In the case of 10SCCM, the diameter of the outflow hole 13 is 0.5mm.
However, in reality, the diameter of the outflow hole 13 should be adjusted so that the outflow hole 13 can be easily machined with good precision, taking into consideration the diameter and wall thickness of the introduction pipe 12.
It is set at 0.5 to 1.0 mm.

In addition, the pitch of the outflow hole 13 was determined to be 10 to 10 by experiment.
It is set as 40mm.

Also, the reason why the outflow hole 13 is directed toward the region 18 on the opposite side of the target 2 from the tangent line 16 shown in FIG.
Due to the following reasons.

That is, when forming a thin film of nitride or oxide on the inner peripheral surface of the base 8 by the reactive sputtering method,
The following three cases are generally assumed for these reactions (for example, when forming a thin film of TiN, a reaction of 2Ti+N ₂ →2TiN occurs).

(a) The compound reacts on the surface of target 2 and evaporates by sputtering. (For example, TiN
In the case of the thin film, TiN is formed on the target 2 and is sputtered and evaporated. ) (b) Reacts in the space between the target 2 and the substrate 8 to generate a compound.

(c) Reacts on the inner circumferential surface of the substrate 8 to generate a compound. (For example, in the case of a thin film of TiN, sputtered particles of Ti adhere to the inner circumferential surface of the base 8 and react with N ₂ gas to become TiN.) In the above three cases, the above As the reaction progresses according to (a), the target 2 is covered with a nitride (e.g., TiN), which has a lower sputtering rate than pure metal (e.g., Ti), and is sputtered, resulting in the formation of a thin film. 10~ for other membrane speeds
It will drop to 50%.

This is a phenomenon called target poisoning, and should be avoided in order to increase the film formation rate.

In the present invention, the outflow hole 13 is
Area 1 closer to the target 2 than the tangent line 16 shown in the figure
9 to direct the reaction gas from the outflow hole 13 toward the target 2, a target poisoning phenomenon was observed, and the outflow hole 13 was
When the reactive gas was directed toward the region 18 on the opposite side of the target 2 from the tangent line 16 shown in the figure and flowed out from the outflow hole 13 toward the inner peripheral surface of the base 8, almost no target poisoning phenomenon was observed. Therefore, the direction of the outflow hole 13 is determined as described above.

Note that the direction of the outflow holes 13 only affects the film formation rate, and has little or no effect on forming a thin film with a substantially uniform composition over the entire inner circumferential surface of the substrate 8, so the film formation rate If it is acceptable for the flow rate to be slow, the outflow hole 13 may be directed toward a region 19 closer to the target 2 than the tangent line 16 shown in FIG.

By the way, if O ₂ gas is used as the reaction gas,
Since the activity of O ₂ is very high, uneven film formation tends to occur on the inner circumferential surface of the substrate 8.

To solve this problem, a second embodiment of the present invention shown in FIG. The O ₂ gas is made to flow out almost uniformly.

FIG. 5 shows a third embodiment in which the present invention is applied to a magnetron sputtering device, in which the target 2 is cylindrical, and inside the target 2, magnets 21 having a length of 40 mm are arranged at 2 mm intervals. It is arranged in the direction.

In the case of this magnetron sputtering device, it is thought that reactions occur in regions corresponding to each magnet 21 in the axial direction.
One or more outflow holes 13 are formed in a portion corresponding to each magnet 21 of No. 2 .

In the example, an introduction pipe with a large number of outflow holes arranged at equal pitches was used, but instead of the introduction pipe as described above, a sintered stainless steel tube having an extremely large number of pores (outflow holes) was used. A textile pipe may also be used as the introduction tube.

When the introduction tube as described above is used, it is preferable to seal the target side of the introduction tube in order to effectively prevent the target poisoning phenomenon.

Further, the base body may be a square tube or a hexagonal tube other than a cylinder, and in short, any cylindrical body is sufficient.

(Effects of the Invention) As described in detail above, according to the present invention, it is possible to form a thin film having a substantially uniform composition over the entire inner peripheral surface of the substrate, which is of great practical benefit.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a front sectional view of the whole, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG. B-B in Figure 2
4 is a plan sectional view of the main part showing the second embodiment of the present invention; FIG. 5 is a vertical sectional view of the main part showing the third embodiment of the invention; FIG. 6 and FIG. 7 are overall simplified front views showing one conventional example. 1... Container, 2... Target, 8... Substrate,
11... Inert gas supply pipe, 12... Reaction gas introduction pipe, 13... Outflow hole, 15... Circumference, 16...
Tangent line, 18...Area on the opposite side of the target.

Claims (1)

[Scope of Claims] 1. A cylindrical base 8 is fitted concentrically around the target 2, and a glow discharge is generated between the target 2 and the base 8 in an inert gas atmosphere, thereby discharging the target 2.
The material of the target 2 is sputtered and evaporated, and a compound of the evaporated material of the target 2 and the reaction gas inside the base 8 is formed as a thin film on the inner peripheral surface of the base 8. A reaction gas introduction pipe 12 extending over the entire length in the direction is arranged parallel to the axial center of the base body 8, and the reaction gas flows out almost uniformly from the part extending over the entire length in the axial direction to the part of the introduction pipe 12 inside the base body 8. 1. A reactive sputtering device characterized in that an outflow hole 13 is formed. 2. The reactive sputtering apparatus according to claim 1, wherein the base body 8 is cylindrical and is provided with means for rotating the base body 8 about its axis. 3. The reactive sputtering apparatus according to claim 1, wherein a plurality of introducing pipes 12 are arranged around the target 2 at equal pitches in the circumferential direction. 4. It should be noted that the distance l between the axis of the introduction tube 12 and the outer circumferential surface of the target 2 is approximately 1/3 to 2/5 of the distance L between the outer circumferential surface of the target 2 and the inner circumferential surface of the base 8. A reactive sputtering apparatus according to claim 1, characterized in: 5 Outflow hole 13 with a diameter of 0.5 to 1.0 mm in the introduction pipe 12
2. The reactive sputtering device according to claim 1, wherein the sputtering devices are arranged at a pitch of 10 to 40 mm in the axial direction. 6. A tangent line 16 passing through the axis of the introduction tube 12 on the circumference 15 passing through the axis of the introduction tube 12 centered on the axis of the target 2 when viewed from the direction of the axis of the target 2.
2. The reactive sputtering apparatus according to claim 1, wherein the outflow hole 13 is oriented toward a region 18 on the opposite side of the target 2 from the tangent line 16 when .