JPS58110673A - Reactive sputtering device - Google Patents

Abstract

PURPOSE:To provide a titled device which can control reactive gaseous pressure near the substrate in a wide range, by providing a partition wall having many small holes between a target and the substrate disposed to face the target and separately forming an electric discharge chamber on the target side and a thin film forming chamber on the substrate side. CONSTITUTION:A target 2 supported with a support 3 and a substrate which is supported with a support 5 mounted with a rotating device 13 and is to be formed with thin films thereon are disposed in a vacuum vessel 1 of a titled reactive sputtering device. The vessel 1 is divided to two chambers; an electric discharge chamber on the target 2 side and a thin film forming chamber on the substrate 4 side by means of a partition wall 11 having length 1-2 times the hole diameter and many small holes. An introducing device 6 for an inert gas such as Ar is mounted in the discharge chamber and an introducing device 7 for a reactive gas such as O2N2 in the thin film forming chamber. Evacuating devices 8, 9 are mounted respectively to the above-mentioned chambers. With such constitution, a >=10 times difference can be given in the concn. of the reactive gas between the discharge chamber and the thin film forming chamber, and since the plasma generated in the discharge chamber is shut off by the wall 11, there are virtually no increase in the substrate temp. and the damage of the formed films and the distributions of the film thickness are made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for forming a reactant film using a reactive sputtering method.

Sputtering is performed by mixing a reactive gas such as oxygen, nitrogen, methane, or hydrogen sulfide into an inert gas that causes a discharge using a single substance as a target, and sputtering the oxide or nitride of the target substance onto a substrate facing the target. matter, carbide,
In reactive sputtering technology that forms reaction products such as sulfides, the target is treated in an atmosphere with a low concentration of reactive gas, the concentration of reactive gas is increased near the substrate, and the reactive gas and inert gas are separated. A reactive sputtering device has been proposed. This is because in the conventional parallel plate bipolar sputtering method, the reactive gas comes into contact with the target, so it reacts on the target first, and the reaction product is sputtered, so the film formation rate is generally slow. On the other hand, when trying to form reactants of the target material on the substrate by applying high sputtering power to avoid reactions on the target, it is difficult to control the degree of reaction of the film and it is difficult to form intermediate reactants. was there.

In order to overcome these shortcomings, the proposed device separates the target into a shield chamber by surrounding it with a shield plate in a vacuum chamber, introduces an inert gas into the shield chamber, and introduces a reactive gas near the substrate. The configuration is such that

However, the shield plate naturally has a window that allows the particles sputtered on the target to pass through, and because the conductance of this window is large and the shield chamber does not have an exhaust system, the inert gas and reactive gas separation is almost impossible.

Furthermore, the sputtered particles widely adhere to the wall surface of the vacuum chamber, and the resulting getter action effectively reduces the reactive gas partial pressure to a very low level, which is a problem in controlling the reactivity.

Furthermore, since the substrate is directly exposed to plasma, the substrate temperature increases, making it difficult to control the substrate temperature, and causing damage to the formed film due to ion collisions.

SUMMARY OF THE INVENTION An object of the present invention is to provide a reactive sputtering apparatus that eliminates the above-mentioned drawbacks of the prior art, can control reactive gas pressure in the vicinity of a substrate over a wide range, and can suppress a rise in substrate temperature.

A feature of the present invention is that a partition wall having a large number of small holes of appropriate length is provided between a target and a substrate provided opposite to the target, and a vacuum chamber is connected to a discharge chamber on the target side and a substrate provided with the substrate. *Divided into two chambers, the film formation chamber and the discharge chamber, an inert gas introduction device is connected to the thin film formation chamber, a reactive gas introduction device is connected to the thin film formation chamber, and an exhaust device is connected to each chamber. By 2i! In this method, it is easy to separate the inert gas and the reactive gas, and reactions on the target can be prevented.

Another feature of the present invention is that since discharge occurs only between the target and the above-mentioned barrier ribs, the substrate is not directly exposed to plasma and the substrate temperature is less likely to rise.

Another feature of the present invention is that the influence of the getter action on the reactive gas partial pressure is reduced.

Another feature of the present invention is that the partition wall has a large number of small holes;
The advantage is that it is easy to make the film thickness distribution uniform.

The present invention will be explained below with reference to Examples.

Example 1 The configuration of this example is shown in FIGS. 1 and 2. FIG. 1 is an overall configuration diagram of the device, and FIG. 2 shows an example of the arrangement of small holes formed in the partition wall. In FIG. 1, 1 is a vacuum chamber, 2 is a target, and 3 is a target support, and the vacuum chamber 1 and the target support 3 are electrically insulated. 4 is a substrate on which a thin film is to be formed; 5 is a substrate support to which a substrate rotation device 13 is attached in order to make the film thickness uniform; The vacuum chamber 1 has a partition wall 1 having a large number of small holes of appropriate length.
1, it is divided into two chambers: a discharge chamber on the target 2 side and a thin film forming chamber on the substrate 4@. The discharge chamber is equipped with an inert gas introduction device 6 such as argon, the thin film forming chamber is equipped with a reactive gas introduction device 7 such as oxygen and nitrogen, and each chamber is equipped with exhaust devices 8 and 9. 10 is a DC or high frequency power supply for discharging, and 12 is a target 2 by discharging.
The flight path of the particles sputtered from the partition wall 11 and passing through the small holes in the partition wall 11 is shown.

FIG. 2 shows the substrate rotation 15 of the small hole 111 made in the partition wall 11.
This conceptually shows an example of an arrangement for making the film thickness uniform in combination with the above, and the small holes 111 are opened at equal intervals on the solid line portion of the cotton wire 112 as shown in the figure. The origin of the cotton wire is aligned with the center of substrate rotation.

Next, the operation of each part will be explained. First, it will be shown that in this example, the concentrations of the inert gas and the reactive gas can be significantly different between the discharge chamber and the thin film formation chamber. The conductance of the opening of the partition wall 11 is C (L/5ee), the inert gas flow rate from the inert gas introducing device 6 is Qa (Torr @ AΔ), and the reactive gas flow rate from the reactive gas introducing device 7 is QB ( To
rr*L/see), and the exhaust speeds of the exhaust devices 8 and 9 are Stj, s, (t/sc), respectively, the inert gas partial pressure P-(Torr
), reactive gas partial pressure P', (Torr), and inert gas partial pressure p in the thin film forming chamber: (Torr
) and reactive gas partial pressure PF (Terr) are respectively expressed by the formula (
It is given by 1) to (4).

"""'d Gokusabi 6 ・・・・・・・・・・・・・・・
(1) pF ==Σ-Ji-Dinga ・ (2"Qa ""y; πT and lower F ・・・・・・・・・・・・・・・
(5) PF=s *'+"("'t+'t"
(4' Ft, b) formula, PF /pt = (St
10') QA/CQJ *Pr/p:=<s, +c
)Qx/cqtttyb. In order to separate the inert gas and the reactive gas in one and both chambers, as we will see, we must either increase the pumping speed S, S, of both chambers, or decrease the conductance C° of the diaphragm opening. There is a need to. However, when the pumping speed "IIS!" is increased, the gas pressure 1Q - " (Torr
), the gas flow rates QA and Qn must be made very large. Therefore, it is more appropriate to reduce the conductance C'' of the partition wall opening.

If the diameter and length of the small hole made in the partition wall 11 as in this example are t, the conductance will be 1/()4+1) compared to the case of a small hole with no length, and for example, L/D= When set to 1o, the conductance falls to '/a,s. In order to effectively utilize the reduction in conductance due to the small holes having such a length and to minimize the decrease in the film formation rate, it is preferable that 1≦l/D≦20.

In this example, t=20 (w), D=2 (wa)
Approximately 2,000 holes are drilled (total opening area = 65
al), its conductance x t゛=ss (t/
5ac). Using such a partition, the pumping speed is 51
=s, =so.

(t/5IIe) t QA=4.7 (Torr −
j/sc) (=converted to standard state "0"/"
) * Qj ” 2.35 (Torr e Z/s
se ) (= 190 cc 7 m ), and when argon gas is used as the inert gas and oxygen gas is used as the reactive gas, there is a large difference in the concentration of argon gas and oxygen gas between the two chambers, as shown in the table below. .

If the apparatus of this example is used, the reactive gas partial pressure and the inert gas partial pressure in both chambers can be controlled almost independently, and the degree of reaction can be easily controlled.

Further, in the apparatus of this example, when the supply of reactive gas is stopped and the apparatus is used as a normal sputtering apparatus, the residual impurity gas in the thin film forming chamber can be suppressed to a low level, and a high-quality film can be obtained.

Sputtering of target 2 is performed at a distance of 1 from target 2.
111 or the vacuum chamber 1 which is electrically connected thereto, and the high frequency power source 10 for discharge connected therebetween. If the target 2 is a good conductor, the power source 10 may be a DC power source. At this time, discharge occurs between the target 2 and the partition wall 11, and particles sputtered from the target pass through the small holes of the partition wall 1111 as indicated by arrow 12 and reach the substrate. Sputtered particles react with reactive gases while in flight or on the substrate.

At this time, the substrate is not directly exposed to plasma (
The increase in substrate temperature can be suppressed to a low level, and the formed film is less likely to be damaged by the ion balance device.

Further, as can be seen from the arrow 12, since the small holes 111 formed in the partition wall 11 have a certain length, the sputtered particles have unidirectionality. This material is advantageous in controlling the orientation of films such as magnetic thin films.

Furthermore, in this example, most of the sputtered particles adhere directly to the walls of the discharge chamber, so even if the sputtered particles have a strong getter effect on the reactive gas, the amount of reactive gas in the thin film forming chamber is The effect on pressure is extremely small. If this is shown in accordance with the example in which the numerical value is increased in this example, it will be as follows. If aluminum, iron, or the like, which has a strong getter effect on oxygen, adheres to the inside of the vacuum chamber, the pumping speed for oxygen will reach about 10' (17W). Therefore, in equation (4), if S = 104 (t/111e) and other values remain as in the previous example, the oxygen partial pressure in the thin film forming chamber is 4. It can be seen that OX 10-s (7'ayy) and there is no change at all. Thus, it can be seen that the device of this example consumes very little reactive gas due to the getter action, and that the reactive gas is effectively used for the reaction of the film deposited on the substrate.

Next, a description will be given of how to make the film thickness distribution uniform when using a partition wall having the arrangement of small holes shown in FIG. The sputtered particles that have passed through one small hole form a band-shaped film on the substrate due to the rotation of the substrate, with the maximum film thickness near the center radius. In order to make the distribution uniform near the radius of this band, it is necessary to make the distribution uniform by a fraction of the radius of rotation of the substrate! It is sufficient to overlap the contributions from the small holes. Furthermore, in order to make the film thickness distribution in the direction of the rotation radius of the substrate uniform, it is sufficient to superimpose the contributions of the /h holes in proportion to the rotation radius of the substrate. An example of such arrangement of small holes is to arrange them at equal intervals on a spiral edge represented by r=Aθ in polar coordinates as shown in FIG.

In the case of this example, Δ=2 (g/rad) #!
Small holes 111 (diameter 2 m) were placed on the solid line portion of 1112 at equal intervals of 4 cm between centers, and the distribution in the radial direction of the substrate support at this time was W, as shown by the solid line in Figure 5. Very uniform. The dotted line in FIG. 6 shows the film thickness distribution when the small holes 111 are opened at the same intervals on the inside and outside of the 14IIIi 112. As can be seen from this dotted line, the film thickness distribution cannot be made uniform at the center of substrate rotation. Therefore, this example is suitable for cases where it is not necessary to form a film at the center of rotation of the substrate, such as in magnetic disks.

Using the partition wall of this example, iron was the target, argon gas was used as the inert gas, and oxygen was used as the reactive gas.
When a or -FgtUs is formed, the film formation rate is approximately o
, o s :47-, which is very small.

If a magnetron-made target is used and the hole size and arrangement are adjusted accordingly, the film formation rate can be improved by more than one order of magnitude.

Example 2 The schematic structure of this example is shown in FIGS. 4 and 5. FIG. 4 is a schematic diagram of a sputtering apparatus equipped with an eccentric substrate rotating device, and FIG. 5 is a conceptual diagram of a one-hole apparatus with a partition wall. The feature of this example is that the rotation center of the substrate rotation device 150 is eccentric, and can be applied to larger substrates than the first embodiment. The other configurations and their operations are the same as in the first embodiment.

As explained above, the apparatus configuration according to the present invention can increase the difference in reactive gas concentration between the discharge chamber and the thin film forming chamber by more than 10 times.

Furthermore, since the plasma generated in the discharge chamber is blocked by the partition wall, there is almost no rise in substrate temperature caused by the ion balancer and no damage to the formed film.

In addition, since the sputtered particles hardly adhere to the wall surface of the thin film forming chamber due to the presence of the partition wall, the decrease in reactive gas due to the getter action is extremely small, and the reactive gas is effectively used for the reaction of the sputtered particles.

Further, since the partition wall has a large number of small holes, the film thickness distribution can be easily made uniform by a combination of the arrangement thereof and the rotation of the substrate.

Furthermore, since the small holes in the partition wall are long and narrow, the flight direction of the sputtered particles can be set to an opening angle of 1 degree or less.

[Brief explanation of drawings]

FIG. 1 is a side view of the configuration of an embodiment of a sputtering apparatus according to the present invention, FIG. 2 is a conceptual diagram showing the arrangement of small holes in the partition wall, and FIG. 3 is a diagram showing the arrangement of the small holes and the rotation of the substrate. FIG. 4 is a diagram showing the film thickness distribution, FIG. 4 is a side view showing the construction of an embodiment of the sputtering apparatus according to the present invention for Oya's substrate, and FIG. 5 is a diagram showing the arrangement of small holes made in the partition wall at that time. 1... Vacuum chamber 2... Target 5... Target support 4... Substrate 5... Substrate support 6... Inert gas introduction device - 7... Reactive gas introduction device 8 9...Exhaust device 10...Discharge power source 11...Partition wall 12 with small holes...Flight direction of sputtered particles 13...Substrate rotation device 111...Small hole 112...Small Cotton wire showing hole arrangement A-1 closed hole 3

Claims (1)

[Claims] t A target and a substrate facing the target are provided in a vacuum chamber, and the chamber is made into a mixed gas atmosphere of an inert gas and a reactive gas, and a discharge is caused to occur between the target material and the reactive gas. In a reactive sputtering device that forms a reactant on a substrate, there is a gap between the target and the substrate of 1 to 2
A reactive sputtering apparatus characterized in that a partition wall having a small hole having a length of 0 times is provided, and exhaust mechanisms are provided on each of the target side and the substrate side. 2. A target and a substrate facing it are placed in a vacuum chamber, and a mixed gas atmosphere of an inert gas and a reactive gas is generated in the chamber, and a discharge is caused to cause a reaction material between the target material and the reactive gas to be transferred onto the substrate. In a reactive sputtering apparatus for forming a sputtering device, a substrate rotation mechanism is provided, a partition wall having a small hole having a length of 1 to 20 times the hole diameter is provided between the target and the substrate, and the target side and the substrate are separated from each other. A reactive sputtering device characterized by having an exhaust mechanism provided on each side.