JPH0610345B2 - Sputtering equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a sputtering apparatus.

(Prior Art) In semiconductor manufacturing, as an apparatus for forming a refractory metal or an alloy film of a silicide of this refractory metal on a semiconductor wafer, for example, argon in an atmosphere with a pressure of about 10 ^-3 to 10 ^-2 Torr is used. A sputtering apparatus is used in which a voltage is applied between two electrodes in gas to generate argon plasma, and a target is sputtered by the argon plasma to deposit an alloy film on a semiconductor wafer. The refractory metal referred to here is a metal that can take advantage of the characteristics of the sputtering method, and refers to a metal having a relatively higher melting point than, for example, aluminum.
For example, metals such as tungsten and molybdenum used for the wiring film of the semiconductor element can be cited.

As a target material used in this sputtering apparatus, from the viewpoint of accelerating the operation of semiconductor elements, for example, a refractory metal silicide having a low specific resistance of the deposited alloy film, for example, tungsten silicide (WS
i ₂ ) products are often used.

The target made of tungsten silicide is generally manufactured by molding tungsten (W) powder and silicon (Si) powder in a high temperature and high pressure atmosphere.

In addition to the above target, there is a target disclosed in Japanese Patent Application Laid-Open No. 58-193364, for example, in which a refractory metal is embedded with silicon.

(Problems to be Solved by the Invention) However, in the former target, it is difficult to control the distribution and particle size of tungsten and silicon particles to be uniform in the fabrication thereof. May remain with a relatively large particle size. If this large particle size silicon is present in the target, there are the following problems.

In FIG. 3 (a), when the magnetic field H (3) is applied in parallel to the sputtering surface (2) of the target (1) and the electric field E (4) is applied vertically, the target (1) is temporarily If it has a uniform resistivity, the electric field E (4) will be
Enter into (2) with a uniform distribution.

However, when large-grained silicon (5) is present on the sputtering surface (2) of the target (1), the larger-grained silicon (5) is larger than the resistivity of the tungsten silicide (6) in the target (1). Since the specific resistance of 5) is large, the electric field E (4) is hard to enter the above-mentioned large grain silicon (5), and as shown in FIGS. 3 (a) and 3 (b), this large grain silicon (5) It concentrates on the tungsten silicide (7) with a lower specific resistance in the vicinity.

Then, an abnormal discharge is generated in the portion of the tungsten silicide (7) where the electric field E (4) is concentrated, and a part of the target (1) is peeled off to float as foreign matter in the sputtering device (not shown). No) and adheres as foreign matter.

On the other hand, in the latter case, abnormal discharge does not occur, but since the target base material is filled with silicon, the manufacture becomes complicated.

The present invention has been made to solve the above problems, preventing abnormal discharge due to electric field concentration on the target,
In addition, it is an object of the present invention to provide a sputtering apparatus that prevents foreign matter from being generated from a target due to abnormal discharge and does not cause foreign matter to adhere to an alloy film formed on a substrate.

[Structure of Invention]

(Means for Solving Problems) A sputtering apparatus according to the present invention discharges plasma in the presence of a processing chamber that holds a depressurized state and a gas for plasma generation supplied into the processing chamber. 1st and 2nd
Sputtering is caused by collision between the electrodes and the first and second magnetic poles that form a magnetic field that acts on the electric field between these electrodes to confine the plasma by this magnetic field, and the active species in the plasma that are confined by the magnetic field between these magnetic poles. In a sputtering apparatus equipped with a sputtering target attached to any of the above electrodes so as to generate particles, and a holder for holding a substrate on which a thin film is formed by the sputtered particles from this sputtering target, The target for use is formed as a sintered body containing a powder of refractory metal and at least a powder of silicon, and the silicon is pre-doped with an atom belonging to group III or group V of the periodic table as an impurity atom to obtain a specific resistance. It is characterized by being adjusted to 1 Ω-cm or less.

(Function) According to the present invention, when a gas for plasma generation is supplied into the processing chamber in a depressurized state and then a voltage is applied between the first and second electrodes, the gas is turned into plasma due to the discharge between the two electrodes. The active species are generated, and the first,
The magnetic field between the second magnetic poles acts to confine the plasma, and the active species in the plasma thus confined are the first and second active species.
In combination with the action of the electric field between the electrodes, they collide with the sputtering target to generate high melting point metal atoms and silicon atoms as sputtered particles, and these sputtered particles diffuse in the processing chamber and adhere to the substrate. A refractory metal silicide film is formed by pre-doping the silicon contained in the sputtering target with an atom belonging to Group III or V of the periodic table as an impurity atom, and the specific resistance of silicon is 1 Ω-cm. Since the difference with the surrounding specific resistance is small in the following, an even electric field is formed near the surface of the sputtering target and the electric field concentration on the surface of the sputtering target is eliminated, preventing abnormal discharge on that surface. be able to.

(Example) Hereinafter, one example of the sputtering apparatus of the present invention will be described with reference to the drawings.

A sputter gun portion ( 12 ) formed in a cylindrical shape, for example, is hermetically attached to the bottom of the processing chamber (11) by welding or other means.

The lower part of this sputter gun section ( 12 )
Excitation coil wound in an annular shape around the center of ( 12 )
(13) is built in, and this exciting coil (13) is connected to the exciting coil power supply (14).

Next, in the upper part of the sputter gun part ( 12 ), an annular groove (15) is formed.
The outer magnetic pole (16) and the inner magnetic pole (17) serve as the first magnetic pole and the second magnetic pole, respectively, in the outer portion inner portion of the groove (15) due to the magnetic field generated by the exciting coil (13). A first electrode for generating and generating plasma
It is made of a magnetic material so as to function as (18).

Further, in the groove (15), a target (19) formed in a ring shape.
The second electrode (20) for plasma generation provided with is disposed in an insulated state from the first electrode (18).

Here, the target (19) will be described.

As a material for the target (19), for example, tungsten (W)
And silicon (Si) are used. First, silicon pulverized into powder is treated with a processing means such as thermal diffusion to obtain I of the periodic table.
Boron (B) or phosphorus (P), which is an atom belonging to Group II or Group V, is doped as an impurity atom, and the resistivity of the silicon after doping is reduced to about 1 Ω-cm or less. deep.

Next, tungsten, which is a refractory metal, is pulverized into powder, and the powdered silicon after doping is mixed and sintered in an atmosphere under high temperature and high pressure to obtain a predetermined shape, for example, a flat plate. Annular tungsten silicide (WS
It is made by molding a target (19) consisting of i ₂ ).

Next, the first electrode (18) and the second electrode (20) are treated in the processing chamber (1
1) It is connected to the sputter power supply (21) provided outside.

On the other hand, a heating mechanism (not shown) is provided in the upper portion of the processing chamber (11), and a circular shape is provided as a holding body for holding the semiconductor wafer (22) as a substrate while facing the sputter gun section ( 12 ). A plate-shaped susceptor (23) is suspended.

Further, a vacuum pump (24) for reducing the pressure in the processing chamber (11) to a predetermined pressure via the side wall of the processing chamber (11), the processing chamber (11).
A vacuum gauge (25) that indicates the degree of vacuum inside, a main gas introduction source (26) for introducing a gas for plasma generation such as argon (Ar) gas into the processing chamber (11) is connected to the sputtering apparatus. It is configured.

Next, the operation will be described.

First, the semiconductor wafer (22) is transferred by a transfer mechanism (not shown) or the like.
Is carried into the processing chamber (11), and the semiconductor wafer (22) is held by the susceptor (23). Next, the vacuum pump (24) is operated to evacuate, and the semiconductor wafer (22) is heated to a predetermined temperature. Next, argon gas is introduced from the main gas introduction source (26), and the inside of the processing chamber (11) is kept in a depressurized state so that the display of the vacuum gauge (25) is about 10 ⁻³ to 10 ⁻² Torr.

Then, a current is supplied to the exciting coil (13) by the exciting coil power source (14) to magnetize the sputter gun portion ( 12 ) so that the inner magnetic pole (17) becomes the N pole and the outer magnetic pole (16) becomes the S pole. Magnetize to.

Further, the sputtering power source (21) is used to, for example, the first electrode (18).
Is used as an anode and the second electrode (20) provided with the target (19) is used as a cathode, and a DC voltage of about 0.5 to 1 KV is applied to generate a plasma discharge, whereby an argon plasma ( (Not shown) is generated.

At this time, argon ions (not shown) of argon plasma (not shown) which is an active species trapped on the upper surface of the target (19) by the magnetic field (27) formed by the outer magnetic pole (16) and the inner magnetic pole (17). ) Collides with the target (19), and a refractory metal or a silicide of this refractory metal, for example, tungsten atoms (not shown) and silicon atoms (not shown) are ejected as sputtered particles. And propagates in the processing chamber (11) to adhere to the semiconductor wafer (22) to form a tungsten-silicide thin film as a refractory metal silicide.

And, as shown in FIGS. 2 (a) and 2 (b), the spatter is
The magnetic field H (2) is almost parallel to the sputtering surface (28) of the target (19).
9) with the electric field E (30) applied vertically, the target (1
9) is sputtered, but even if large-grained silicon (32) remains in the tungsten silicide (31) that is the material of the target (11), it is possible to use the conventional method for the following reasons. Such abnormal discharge does not occur.

Generally, the resistivity of the tungsten silicide (31) formed as described above is about several tens to several hundreds μΩ-cm,
Further, the resistivity of the large particle diameter silicon (32) doped with boron (B) or phosphorus (P) as impurity atoms and having a low resistance is about 1 Ω-cm or less.

Therefore, if a target material in which the specific resistance of silicon (32) is 1 Ω-cm or less is used, it is a resistance region in which a sufficiently stable plasma can be generated by DC magnetron sputtering. At the nearby tungsten or tungsten-silicide interface (33), there is no electric field concentration to the extent that plasma becomes unstable, and abnormal discharge does not occur. Therefore, the target (19) comes off and the semiconductor wafer (2
It does not adhere to 2) as foreign matter, and a clean film without adherence can be formed.

The effect of the present invention is greatest when the specific resistance of the tungsten silicide (31) and the silicon (32) doped with boron (B) or phosphorus (P) as impurity atoms are the same, but the effect of the present invention is 1 Ω. Within the range of −cm or less, an effect that does not hinder practical use can be obtained.

The material of the target (19) is not limited to the two materials of the above embodiment, tungsten and silicon, but other materials and impurities may be used as long as the specific resistance is uniform at about 1 Ω-cm or less. It is needless to say that the target (19) may be molded using three or more materials.

Further, the target (19) is made by molding, so that the price is low.

EFFECT OF THE INVENTION As described above, according to the present invention, a processing chamber that holds a decompressed state and a plasma generating gas that discharges in the presence of a gas for plasma generation supplied to the processing chamber ,
The second electrode and the first and second magnetic poles that form a magnetic field that acts on the electric field between the two electrodes to densify the plasma by this magnetic field, and the magnetic field between the two magnetic poles A sputtering target attached to any of the above electrodes so as to generate sputtered particles by collision of active species, and a holder for holding a substrate on which a thin film is formed by the sputtered particles from the sputtering target. In the sputtering apparatus, the sputtering target is formed as a sintered body containing a powder of refractory metal and at least a powder of silicon, and the silicon is previously doped with an atom belonging to Group III or V of the periodic table as an impurity atom. However, since the specific resistance was adjusted to 1 Ω-cm or less, abnormal emission due to electric field concentration on the sputtering target was observed. Was prevented, by extension may provide a possibility that no sputtering apparatus occurrence of foreign matter is prevented from adhering foreign substances to alloy film formed on the substrate from the target based on abnormal discharge.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the sputtering apparatus of the present invention, FIG. 2 is an operation explanatory view of the main part of FIG. 1, and FIG. 11 ... Processing chamber, 12 ... Sputter gun part, 19 ... Target, 31 ... Tungsten silicide, 32 ... Large grain silicon.

Claims (4)

[Claims] 1. A processing chamber for maintaining a reduced pressure state, first and second electrodes for generating plasma by discharging in the presence of a gas for plasma generation supplied into the processing chamber, and between these two electrodes. A magnetic field acting on the electric field is formed, and the first and second magnetic poles for confining the plasma by the magnetic field and the sputtered particles are generated by collision of active species in the plasma confined by the magnetic field between these magnetic poles. In a sputtering apparatus equipped with a sputtering target attached to another electrode and a holder for holding a substrate on which a thin film is formed by sputtered particles from the sputtering target, the sputtering target is a powder of refractory metal. And an atom belonging to group III or group V of the periodic table in the silicon while being formed as a sintered body containing at least silicon powder. Previously doped as an impurity atom, a sputtering apparatus, characterized in that to adjust the specific resistance below 1 [Omega-cm. 2. The sputtering apparatus according to claim 1, wherein the atom belonging to Group V of the periodic table is phosphorus. 3. An atom belonging to Group III of the periodic table is
The sputtering apparatus according to claim 1, wherein the sputtering apparatus is boron. 4. The sputtering apparatus according to any one of claims 1 to 3, wherein the refractory metal is tungsten.