JPS6342367A - Sputtering method - Google Patents

Abstract

PURPOSE:To deposit different metals at a desired ratio on a substrate to be treated by using the different metallic materials for paired targets which are opposed to each other and controlling the electric powers to be impressed to the respective targets respectively independently thereby sputtering the targets simultaneously. CONSTITUTION:Magnets 8, 9 are provided to the outside of a vacuum vessel 1 in such a manner that a magnetic field M passes between the paired targets 6, 7 which are opposed to each other in the vessel 1. The paired targets 6, 7 are constituted of the different metallic materials. The substrate 11 to be treated is rotated in parallel with the opposed axes of the targets 6, 7 and the electric powers to be consumed are respectively separately impressed from respective power sources E1, E2 to the targets 6, 7 by which the targets are sputtered. Plasma P is formed at a high density near the part where the cylindrical magnetic lines M of force pass between the targets 6, 7 to sputter the targets 6, 7. The deposited film 12 contg. the metals of the targets 6, 7 at the desired ratio is thereby satisfactorily and stably formed on the substrate 11 to be treated.

Description

[Detailed Description of the Invention] [Summary] A facing target sputtering device is used, a pair of opposing targets are made of different metal materials, and the power applied to each target is controlled independently to sputter each target metal at the same time. This is a method in which an intermetallic compound or alloy containing each target metal in a desired ratio is deposited on a substrate to be processed, and a deposited film of an intermetallic compound or alloy with a constant composition and high purity and good film quality is produced. It is stably obtained, and the coating composition can be easily changed within the alloy composition range between the two targets.

[Industrial application field]

The present invention relates to a sputtering method, and particularly to a method for sputtering intermetallic compound coatings and alloy coatings using a facing target sputtering apparatus.

In highly integrated semiconductor ICs such as LSIs, the wiring width is becoming extremely fine, so in order to prevent a decrease in operating speed due to an increase in wiring resistance, conventional polycrystalline silicon is being used as the lower layer wiring material. Silicides of high-melting point metals are often used because of their low resistivity.

Further, since the impurity doped region is also formed shallowly, a barrier metal made of a high melting point metal is used at the connection portion between the impurity doped region and the aluminum wiring to prevent junction breakdown.

Furthermore, aluminum wiring - silicon (Si) - copper (Cu) is used to prevent migration and increase reliability as the wiring width decreases.
Alloy wiring is often used.

And the above-mentioned high melting point metal silicide film, barrier metal film,
Although Al-5i-Cu alloy films and the like are formed by sputtering, conventionally it has been difficult to obtain a layer with a stable composition, high purity, and good film quality, and improvements are desired.

[Conventional technology]

Conventionally, metal silicide films such as tungsten silicide (WS i t ) and molybdenum silicide (MoSiz) are used for the lower layer electrode wiring, and titanium tungsten (TiW) is used as a barrier metal.
Al-
The 3i-Cu alloy film and the like have been formed using a magnetron sputtering device.

FIG. 2 is a diagram schematically showing a magnetron sputtering apparatus, in which 51 is a conductive vacuum vessel, 52 is a gas inlet,
53 is a vacuum exhaust port, 54 is a backing plate made of copper or the like, 55 is a target, 56 is a ring-shaped magnet, 57
58 is a rotating magnet support, 58 is an insulator packing, 59 is a substrate holder, 60 is a substrate to be processed, 61 is a deposited film, E is a DC power supply, GND is a ground, and N and S are magnetic poles.

As shown in the figure, since the conventional sputtering equipment used had a single target, the target had the same composition as the film to be deposited, such as WSi2, MoS
i2, Ti'W, Hel-5t-Cu alloy, etc.

However, with targets made of high-melting point metal silicides or alloys of high-melting point metals, the target composition changes over time due to differences in sputtering efficiency of each metal element, making it difficult to stably form a film with a constant composition. Particularly, since the target is formed by a powder metallurgy method, its purity is not sufficiently increased, and it is also brittle and easily breaks into powder during sputtering, resulting in a decrease in the purity and quality of the coating.

Furthermore, when using a single target, when trying to change the composition of the alloy coating in a trial production experiment, etc., it is necessary to manually select a target with a composition that matches the desired coating composition each time. There was also the problem of an increase in costs.

[Problem that the invention seeks to solve]

The present invention aims to solve compositional fluctuations, purity and improvement of sputtered films that occur when forming refractory metal silicide films, refractory metal alloy films, and aluminum alloy films using the conventional sputtering method described above. Problems include a decline in quality, an increase in the number of steps required to change the composition, and an increase in costs.

[Means for solving problems]

The above problem has a pair of opposing targets equipped with magnets (8) and (9) at the rear that form a magnetic field (M) that penetrates between the targets. Substrate to be processed (11) facing the opposing axis of the target
A counter target scattering device is used in which the target target scattering device reciprocates while rotating parallel to the opposing axis, and the pair of targets includes first and second targets (6) having different materials or material compositions.
(7), the first and second target rays l-(6)
Sputtering is performed while changing the power consumption of (7) independently, and a deposited film (12) having a required blending ratio of the first target material and the second target material is formed on the substrate to be processed (11). This problem is solved by the sputtering method according to the present invention.

[For production]

Using the same target sputtering apparatus, the opposing pair of targeters 1, that is, the first and second targets, are formed of different metals (or alloys), and electric power is simultaneously applied to each target to separate the first and second targets. of target metals (or alloys) are simultaneously deposited on the substrate to be processed.

At this time, the composition of the sputtered film deposited on the substrate to be processed is
, a second Kuget metal (or alloy), and the sputter rate is proportional to the product of the power applied to each target and the sputtering efficiency of each target metal (or alloy).

Therefore, in the method of the present invention, the electric power applied to the first and second targets is applied to the first and second target metals (
Sputtering is performed by independently controlling the sputtering efficiency of the intermetallic compound or alloy (or alloy) and the composition of the intermetallic compound or alloy to be deposited, and deposits an intermetallic compound or alloy film having a desired composition on the substrate to be processed. .

According to this method, when forming a silicide film or a high melting point metal compound film, pure silicon and a single high melting point metal, or two types of single high melting point metals are used as a cuget. This prevents a decrease in coating purity due to target purity, a decrease in modification due to target pulverization, and a change in coating composition due to changes in target composition over time.

In addition, when forming an alloy film, by using targets with different compositions and changing the power of each target independently, a film with an intermediate alloy composition can be easily formed. It is possible to shorten the number of steps required for prototyping and reduce prototyping costs.

〔Example〕

Hereinafter, the present invention will be specifically explained by examples with reference to the drawings.

FIG. 1 is a vertical cross-sectional view (a) and a side view (bl) schematically showing the structure of a facing target sputtering apparatus.

In the figure, 1 is a four-electrode vacuum vessel made of stainless steel or the like, 2 is a gas inlet, 3 is a vacuum exhaust port, 4.5 is a hasoking plate 1 made of copper or the like, and 6.7 is a first and second 8 is a ring-shaped first magnet that forms a penetrating magnetic field for plasma excitation, 9 is a second magnet, 10 is a rotating substrate stage, 11 is a substrate to be processed, 12 is a deposited film, and 13 is a Insulator packing, EI, Et are DC power supplies for the first and second targets, M is magnetic field line, P is plasma, S
indicates the S pole, N indicates the N pole, and GND indicates the ground.

In this device, the lines of magnetic force M are formed into a cylindrical shape passing through opposing targets as shown in the figure.

Then, the plasma P is formed at high density on the target surface near where the magnetic field lines M penetrate the target, and the plasma P
The metal of the target 6.7 is sputtered by the target 6.7, reciprocating parallel to the opposing axis of the target 6.7 outside the area facing the target 6.7, that is, the area sandwiched between the targets 6.7, and A deposited film 12 made of metal constituting the first and second targets 6.7 is deposited on the substrate bl to be processed fixed on the substrate stage 10 which rotates facing the opposing axes of the substrate stage 10.

By the method of the present invention, silicide, high melting point metal compound,
When forming a film such as Al-3i-Cu alloy,
For example, a facing target sputtering device having a structure as shown in FIG. 1 inside 5 x 10-
'In a state of maintaining an argon (Ar) gas (or other inert gas) atmosphere of about Torr, each target metal (or alloy) is applied to each target.
The metals (or alloys) constituting each target 6.7 are simultaneously sputtered by applying DC power such that each sputter rate corresponds to the composition ratio of the film to be deposited, taking into account sputtering efficiency. , are simultaneously deposited on the substrate to be processed.

The sputtering conditions and results of sputtering using the method of the present invention will be described below.

(Example of W Si 2 film deposition) First target material Second target material High purity W High purity Si voltage m
360 420 Current (A) 2
．． 2 4 Electricity (KW) 0.8
WS i with high purity and high film quality at a sputtering rate of 400 people/min under conditions of 1.7 or higher
A stable z film was obtained.

(Example of TiW film deposition) First target Second target material High purity Ti High purity W Voltage m
330 40011 style (8)
3 3 electric power (K匈) 1 1. High purity, with a spackle rate of 500 people/min under the conditions of 1.2 or more.
A TiW film with high film quality was stably obtained.

In addition, in the above examples of W Si 2 film and TiW film deposition, high purity films are obtained because a pure metal is used as a target, and a high purity target is obtained, and high film quality is also achieved. This is because the pure metal cougette has high rigidity so that no target powder is generated during sputtering. Furthermore, the reason why the film composition is stable is that since a metal of a single composition is used for the target, there is no change in the target composition over time.

(Example of Al-5i-Cu alloy film deposition) First target Second target material Al-1%Si Al-1%5i-
4%Cu voltage (V) 500 4
00 Current (A) 20 12.
Under the conditions of 5 electric power (KW) 10 5 or more, an Al-1%5i-1,6% Cu alloy film was stably obtained at a spackle rate of 4000 people/win.

In the above embodiments, the DC voltage generated at each target increases and decreases in proportion to the plasma impedance at each target.

Further, the ratio of power applied to each target is determined by the product of the composition ratio of the component metals in the film to be deposited and the sputtering efficiency of the corresponding target metal.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to form a silicide film of a high-melting point metal such as W Si 2 or a high-melting point metal compound film such as TiW, which has high purity and good film quality, without changing the composition. can.

In addition, alloy films with different compositions can be easily formed without changing targets by independently changing the sputtering power of each target, which shortens the number of prototypes required to change the film composition and reduces trial production costs. etc. can be achieved.

[Brief explanation of drawings]

Figure 2 is a schematic side sectional view of a conventionally used magnetron sputtering device. In the figure, I is a vacuum vessel, 2 is a gas inlet, 3 is a vacuum exhaust port, and 4. 5 is the first and second backing play I・, 6.7 is the first and second target, 8 is the first magnet, 9 is the second magnet, 10 is the substrate stage, Els Ez is the first, Power supply for the second target, M is magnetic field line, P is plasma, S is S pole, N is N pole, GND is ground

Claims (1)

[Claims] A magnet (8
) (9) at the rear and a pair of opposing targets, and outside the area where the targets face each other, the substrate to be processed (11) faces the opposing axis of the targets and is parallel to the opposing axis. Using a facing target sputtering device that reciprocates while rotating, the pair of targets is provided with a first material or a first material having a different material composition.
Sputtering is performed using the first and second targets (6) and (7) while independently changing the power consumption of the first and second targets (6) and (7), and the target substrate (11) is sputtered.
A sputtering method characterized in that a deposited film (12) having a required blending ratio of a first target material and a second target material is formed thereon.