JPH06275560A - Method and device for sputtering - Google Patents

Abstract

PURPOSE:To provide a method by which the coverage of a film on a step of a substrate to be treated, especially, the coverage of a conductive material on the step of a contact hole in a highly integrated circuit device can be improved. CONSTITUTION:A film having good coverage is formed on the step of a substrate to be treated, such as a wafer 2, etc., set in a chamber 1 by performing sputtering on the substrate from a direction which is nearly perpendicular to the substrate and another direction which is nearly parallel to the substrate by using a target 3 for vertical sputtering arranged in nearly parallel to the substrate and target 5 for oblique sputtering obliquely arranged against the substrate. Since a plurality of targets for oblique sputtering or a target for oblique sputtering which can be changed in inclined angle or position can be used, any kinds of steps having different slopes and aspect ratios can be coped with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sputtering a film on a substrate having a step and an apparatus therefor, and more particularly, a sputtering method for improving the coverage of a conductive material in a fine contact hole and an apparatus therefor. Regarding In recent years, as semiconductor integrated circuit devices have been highly integrated and contact holes formed in an interlayer insulating film have been miniaturized, conductive materials such as metals are sputtered in the contact holes to form lower electrodes and wiring and upper layers. When electrically connecting the wiring, it is difficult to maintain a good coverage of the step of the contact hole.

[0002]

As a countermeasure against this, conventionally, at least a part of a sputtering target is effectively tilted with respect to a surface of a wafer to be sputtered so that a directivity of sputtering has a non-vertical component. By doing so, the conductive material is also sputtered on the side wall of the contact hole, and by mounting a collimator between the target and the wafer, the direction in which the conductive material is scattered from the target is controlled, and the conductive material is also formed on the side wall of the contact hole. There is proposed a method for sputtering the semiconductor layer, a method for ensuring electrical connection by filling a contact hole with a conductive material such as tungsten (W), tungsten silicide (WSi) and the like.

However, with the method of effectively inclining the target, it is not possible to form a coating film of a conductive material having a sufficient coverage on the step portion of the contact hole, and the contact hole is filled with tungsten (W). According to the method, there is a problem that the cost is high, the process requires a long time, and the method using the collimator causes dust to be generated by the collimator.

FIG. 5 is an explanatory view of a conventional sputtering apparatus for improving the coverage of a conductor in a contact hole.
(A) shows a schematic cross section of a sputtering apparatus, and (B) shows a target for oblique sputtering. In this figure, 51 is a chamber, 52 is a susceptor, 53 is a wafer, 54 is a target for vertical sputtering, 55 is a target for oblique sputtering, and 56 ₁ and 56 ₂ are electromagnets.

In the conventional sputtering method for improving the coverage of the conductor in the contact hole, the susceptor 52 for mounting the wafer 53 having the contact hole formed thereon is provided at the bottom of the chamber 51. In the ceiling of the chamber 51, a disk-shaped vertical sputtering target 54 is provided directly above the susceptor 52 on which the wafer 53 is placed, and a donut-shaped oblique sputtering target having a slope around the vertical sputtering target 54 is provided. A target 55 is provided, and electromagnets 56 ₁ and 56 ₂ are provided on the back surfaces of the target 54 for vertical sputtering and the target 55 for oblique sputtering outside the chamber 51.

When performing sputtering by this conventional sputtering apparatus, a voltage is applied between the target 54 for vertical sputtering, the target 55 for oblique sputtering, and the chamber insulated from these targets so that Ar and the like in the chamber Metal of the metal forming the target that reaches the wafer 53 by concentrating the plasma on the vertical sputtering target 54 by controlling the plasma region by the electromagnets 56 ₁ and 56 ₂ provided outside the chamber 51. The normal incidence component of the molecule can be increased.

Further, the plasma can be concentrated on the doughnut-shaped oblique sputtering target 55 provided around the vertical sputtering target 54 to increase the oblique incident components of the metal molecules reaching the wafer 53. Therefore, the coverage of the conductive material on the step of the contact hole can be improved by the two-step sputtering.

[0008]

Looking only at the cross-sectional shape of the target of this conventional sputtering apparatus, it can be seen that there is a remarkable effect of improving the coverage of the conductive material in the step of the contact hole as described above. Seem. However, if vertical sputtering and diagonal sputtering are performed alternately, conductive material is deposited near the upper edge of the contact hole step due to vertical sputtering, and the aspect ratio becomes severe, so shadowing of diagonal sputtering becomes stronger and electrical connection is made. There is a problem that the conductive material is not sufficiently deposited around the bottom of the contact hole that needs to be formed.

Further, since the oblique sputtering target 55 has a ring shape and is simultaneously sputtered from the entire surface thereof, metal molecules obliquely flying toward the wafer 53 collide at the central portion in the vicinity of the wafer 53 and are scattered to control. There is a problem that oblique sputtering is not possible. Therefore, it has been found that there is a problem that the wiring in the contact hole is cut off as the contact hole is further miniaturized. The present invention provides a coating rate of a film on a step of a substrate to be processed,
In particular, it is an object of the present invention to provide a sputtering method and an apparatus therefor capable of improving the coverage of the conductive material on the steps of contact holes in a highly integrated circuit device.

[0010]

In the sputtering method according to the present invention, in order to achieve the above object, a vertical sputtering target arranged substantially parallel to a substrate to be processed and a target to be processed are provided. By using the oblique sputtering target that is placed at an angle to perform sputtering from a direction substantially perpendicular to the substrate to be processed and sputtering from a direction close to the substrate to be processed, the step on the substrate to be processed is covered. The process of forming a film with good rate was adopted.

In this case, a plurality of targets for oblique sputtering can be used, and a target for oblique sputtering whose tilt angle or position can be changed can be used.

Further, in the sputtering apparatus according to the present invention, in order to achieve the above object, a vacuum chamber,
A susceptor for mounting a substrate to be processed provided in the vacuum chamber, a vertical sputtering target placed on the susceptor substantially parallel to the susceptor, and a periphery of the vertical sputtering target. A structure including an oblique sputtering target that is arranged to be inclined with respect to the susceptor is adopted.

In this case, it is also possible to provide a plurality of oblique sputtering targets so as to sequentially perform sputtering, and to provide a single or a plurality of oblique sputtering targets whose tilt angles or positions can be changed. It can also be configured to sputter at a desired angle and a desired position.

[0014]

As in the sputtering method of the present invention, when sputtering is performed using the target for vertical sputtering which is arranged substantially parallel to the substrate to be processed, the coating can be deposited on the flat surface of the substrate to be processed. Since the film can be deposited on the side wall of the step by sputtering using the oblique sputtering target that is arranged to be inclined with respect to, it is possible to form a film with a good coverage on the step of the substrate to be processed. Become.

In this case, when a plurality of oblique sputtering targets are used, or an oblique sputtering target whose tilt angle or position can be changed is used for sputtering, even if the steps have different inclinations or different aspect ratios, the steps will be different. It is possible to form a film having a good coverage on the surface.

Further, like the sputtering apparatus of the present invention, a vacuum chamber, a susceptor for mounting a substrate to be processed formed in the vacuum chamber, and a top surface of the susceptor substantially parallel to the susceptor. The above-mentioned sputtering method can be effectively carried out by using a device having a vertical sputtering target arranged in and a diagonal sputtering target arranged around this vertical sputtering target with an inclination with respect to this susceptor. You can
In this case, multiple targets for oblique sputtering, or
When the structure is provided with a target for oblique sputtering whose tilt angle or position can be changed, it is possible to handle processed substrates having steps with various aspect ratios.

[0017]

Embodiments of the sputtering method and apparatus of the present invention will be described below. (First Embodiment) FIG. 1 is an explanatory view of the structure of a sputtering apparatus of the first embodiment. In the figure, 1 is a chamber, 2 is a wafer, 3 is a target for vertical sputtering, 4 is a cathode for vertical sputtering, 5 is a target for oblique sputtering, and 6 is a cathode for oblique sputtering.

In the sputtering apparatus of this embodiment, a place for setting the wafer 2 is provided in the chamber 1, a vertical sputtering target 3 is provided immediately above it, and an oblique sputtering target 5 is provided in an inclined direction.
Outside the chamber 1, a vertical sputtering cathode 4 and an oblique sputtering cathode 6 are provided.

Then, the wafer 2 having the contact holes is set in the chamber 1, the chamber 1 is evacuated, then a gas such as Ar is introduced, and the oblique sputtering cathode 6 connected to the oblique sputtering target 5 and A voltage is applied between the oblique sputtering cathode 6 and the chamber 1 which is insulated so that the oblique sputtering cathode 6 becomes negative to generate plasma, and cations are caused to collide with the oblique sputtering cathode 6. The constituent material is sputtered and deposited on the wafer 2 having the contact holes.

Next, the vertical sputtering cathode 3 becomes negative between the vertical sputtering cathode 4 connected to the vertical sputtering target 3 and the chamber 1 insulated from the vertical sputtering cathode 3. Thus, a voltage is applied to generate plasma, and cations are made to collide with the cathode 3 for vertical sputtering to sputter its constituent materials, and deposited on the wafer 2 having a contact hole. By this two-step sputtering, the conductive material can be coated from the bottom of the contact hole to the step.

FIG. 2 is an explanatory view of the state of covering the contact hole with the conductive material by the sputtering method of the first embodiment.
(A) shows the first stage, and (B) shows the second stage. In this figure, 11 is a substrate, 12 is an insulating film, 13 is a contact hole, 14 is a conductive material by oblique sputtering, and 15 is a conductive material by vertical sputtering.

According to the sputtering method of this embodiment described with reference to FIG. 1, when the conductive material forming the target is deposited on the wafer 2 having the contact holes by sputtering the target 5 for oblique sputtering, the process shown in FIG.
As shown in (A), the conductive material 14 formed by oblique sputtering faces the upper surface of the insulating film 12 on the substrate 11 and the cathode 6 for oblique sputtering of the contact hole 13 formed in the insulating film 12. Is deposited on the side wall.

When the conductive material is deposited on the wafer 2 having the contact holes by the sputtering of the vertical sputtering target 3, as shown in FIG. 2B, the conductive material 15 is formed by the vertical sputtering. Is deposited on the upper surface of the conductive material 14 by oblique sputtering on the insulating film 12 and on the bottom of the contact hole 13.

As can be seen from this figure, the conductive material 14 formed by oblique sputtering and the conductive material 15 formed by vertical sputtering.
This makes it possible to form a good electrical connection with improved coverage from the substrate 11 to the outside of the contact hole 13. The purpose of this embodiment is not to uniformly coat the inner periphery of the side wall of the contact hole 13 with the conductive material, but to reliably form the connection by the conductive material formed on one side of the contact hole 13.

When the wiring is formed by the sputtering method of this embodiment, the wiring running parallel to the Y-axis shown in FIG. 1 is particularly effective and can be further miniaturized. However, with respect to the wiring running parallel to the X axis, it is necessary to allow a slight margin with respect to the contact hole diameter.

Needless to say, the same effect can be obtained by reversing the order of the deposition of the conductive material 14 by the oblique sputtering and the deposition of the conductive material 15 by the vertical sputtering.

(Second Embodiment) FIG. 3 is an explanatory view of the structure of a sputtering apparatus of the second embodiment, (A) showing a cross section, and (B) showing an appearance. In the figure, 21 is a chamber, 22 is a susceptor, 23 is a wafer, 24 is a vertical sputtering target, 25 is a vertical sputtering cathode, 26 is a first oblique sputtering target, 27 is a first oblique sputtering cathode, 28 Is the second target for oblique sputtering, 2
9 is a second oblique sputtering cathode, 30 is a third oblique sputtering target, 31 is a third oblique sputtering cathode, 32 is a fourth oblique sputtering target, 33
Is a fourth oblique sputtering cathode.

The structure of the sputtering apparatus of this embodiment is as shown in the figure. A wafer 23 having a contact hole is set in a susceptor 22 in a chamber 21, and after evacuating the chamber 21, a gas such as Ar is introduced to vertically Vertical sputtering cathode 25 connected to the sputtering target 24, and this vertical sputtering cathode 25
A voltage is applied so that the cathode 25 for vertical sputtering is negative between the chamber 21 and the chamber 21 which is insulated from each other to generate plasma, and cations are added to the cathode 2 for vertical sputtering.
4, the constituent material is sputtered and deposited on the wafer 23 having the contact holes.

Next, the first oblique sputtering cathode 2 connected to the first oblique sputtering target 26.
7 and a chamber 21 that is insulated from the first oblique sputtering cathode 27, a voltage is applied so that the first oblique sputtering cathode 27 becomes negative, plasma is generated, and Ions are made to collide with the first oblique sputtering cathode 26 to sputter the constituent materials thereof, and deposited on the wafer 23 having the contact holes.

Similarly to the above, the second oblique sputtering target 28 and the third oblique sputtering target 3 are sequentially arranged.
Sputtering is performed by using the No. 0 and fourth oblique sputtering targets 32, the material forming the target is deposited on the wafer 23 having the contact holes, and the conductive material is covered from the bottom of the contact holes to the step.

FIG. 4 is an explanatory view of a state in which a contact hole is covered with a conductive material by the sputtering method of the second embodiment. In this figure, 41 is a substrate, 42 is an insulating film, 43 is a contact hole, 44 is a vertical conductive material, 45 is a conductive material by the first oblique sputtering, and 47 is a conductive material by the third oblique sputtering. According to the sputtering method of this embodiment described with reference to FIG. 3, when the conductive material is deposited on the wafer 23 having the contact holes by the sputtering of the vertical sputtering target 24, as shown in FIG.
Conductive material 4 by vertical sputtering as shown in FIG.
4 is deposited on the upper surface of the insulating film 42 on the substrate 41 and on the bottom of the contact hole 43 formed in the insulating film 42.

The first oblique sputtering target 2
When the conductive material is deposited on the wafer 23 having the contact holes by the sputtering of No. 6, as shown in FIG. 4, the conductive material 45 by the first oblique sputtering contacts the upper surface of the insulating film 42. The hole 43 is deposited on the side wall of the hole 43 facing the first oblique sputtering cathode 26.

Further, the second target 2 for oblique sputtering is used.
In the case of depositing the conductive material on the wafer 23 having the contact holes by the sputtering of No. 8, although not shown in FIG. 4, the conductive material by the second oblique sputtering is the insulating film 42 on the substrate 41. And the side wall of the contact hole 43 facing the second oblique sputtering cathode 28.

The third oblique sputtering target 3
When the conductive material is deposited on the wafer 23 having the contact holes by the sputtering of 0, as shown in FIG. 4, the conductive material 37 by the third oblique sputtering is the insulating film on the substrate 41. It is deposited on the upper surface of 42 and the side wall of the contact hole 33 facing the third oblique sputtering cathode 30.

The fourth oblique sputtering target 3
When the conductive material is deposited on the wafer 23 having the contact holes by the second sputtering, although not shown in FIG. 4, the conductive material by the fourth oblique sputtering is the insulating film 42 on the substrate 41. And the side wall of the contact hole 43 facing the fourth oblique sputtering cathode 32.

As can be seen from this figure, in the sputtering method of this embodiment, the ring-shaped target in the conventional sputtering apparatus is divided into four and arranged around the target for vertical sputtering, and the sputtering is independently and sequentially performed. Therefore, the conductive material reaches every corner of the contact hole, and a good step coverage can be obtained.

When the wiring is formed by the sputtering method of this embodiment, the step coverage can be improved irrespective of the wiring direction, so that the degree of freedom in miniaturizing the wiring is increased.

Needless to say, the same effect can be obtained even if the order of the deposition of the conductive material by the oblique sputtering and the deposition of the conductive material by the vertical sputtering is reversed from the above description. In addition, the first oblique sputtering target, the second
If the inclinations of the target for oblique sputtering, the target for third oblique sputtering, and the target for fourth oblique sputtering can be set freely, contact holes of all aspect ratios can be dealt with. Further, by using one oblique sputtering target and making the inclination angle variable so as to be movable in the chamber, it is possible to deal with contact holes of all aspect ratios as in the above.

In the above embodiment, the case where the conductive material is deposited in the contact hole has been described. However, it is needless to say that the present invention can be applied to the case where the target substrate having a step is sputtered.

[0040]

As described above, according to the present invention,
Improve the coverage of the coating such as the conductive material deposited on the substrate to be processed having a step such as a contact hole while avoiding the problems such as the cost increase and the increase of dust that the conventional sputtering method has. Therefore, it is possible to deal with finer steps such as contact holes, which greatly contributes to the field of manufacturing technology of highly integrated circuit devices and the like.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a sputtering apparatus of a first embodiment.

FIG. 2 is an explanatory view of a state in which a contact hole is covered with a conductive material by the sputtering method of the first embodiment, (A) showing a first stage and (B) showing a second stage.

FIG. 3 is a configuration explanatory view of a sputtering apparatus of a second embodiment,
(A) shows a cross section and (B) shows an appearance.

FIG. 4 is an explanatory view of a state of covering a contact hole with a conductive material by a sputtering method according to a second embodiment.

5A and 5B are explanatory views of a conventional sputtering apparatus for improving the coverage of a conductor in a contact hole, FIG. 5A shows a schematic cross section of the sputtering apparatus, and FIG. 5B shows a target for oblique sputtering.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 chamber 2 wafer 3 target for vertical sputtering 4 cathode for vertical sputtering 5 target for oblique sputtering 6 cathode for oblique sputtering 11 substrate 12 insulating film 13 contact hole 14 conductive material by oblique sputtering 15 conductive material by vertical sputtering 21 chamber 22 susceptor 23 wafer 24 Vertical Sputtering Target 25 Vertical Sputtering Cathode 26 First Oblique Sputtering Target 27 First Oblique Sputtering Cathode 28 Second Oblique Sputtering Target 29 Second Oblique Sputtering Cathode 30 Third Oblique Sputtering Target 31 Third Oblique Sputtering Cathode 32 Fourth Oblique Sputtering Target 33 Fourth Oblique Sputtering Cathode 41 Substrate 42 Insulating Film 43 Contact Hole 44 Vertical Conductive Material 45 Conductive Material by First Oblique Sputtering 47 Conductive Material by Third Oblique Sputtering 51 Chamber 52 Susceptor 53 Wafer 54 Vertical Sputtering Target 55 Oblique Sputtering Target 56 ₁ , 56 ₂ Electromagnet

Claims (6)

[Claims] 1. A substrate to be processed is provided with a target for vertical sputtering, which is arranged substantially parallel to the substrate to be processed, and a target for oblique sputtering, which is arranged obliquely to the substrate to be processed. Sputter from the vertical direction,
A sputtering method, wherein a film having a good coverage is formed on a step of the substrate to be processed by performing sputtering from a direction substantially parallel to the substrate to be processed. 2. A substrate to be processed using a target for vertical sputtering arranged substantially parallel to the substrate to be processed and a plurality of targets for oblique sputtering arranged to be inclined with respect to the substrate to be processed. Is characterized in that a film having a good coverage is formed on a step of the substrate to be processed by performing sputtering from a direction substantially perpendicular to the substrate and sputtering from a plurality of directions close to the substrate to be processed. Sputtering method. 3. A vertical sputtering target arranged substantially parallel to a substrate to be processed, and an oblique sputtering target arranged to be inclined with respect to the substrate and capable of changing its inclination angle or position. By performing sputtering from a direction substantially perpendicular to the substrate to be processed and sputtering from an arbitrary direction near the substrate to be processed,
A sputtering method, which comprises forming a film having a good coverage on a step of the substrate to be processed. 4. A vacuum chamber, a susceptor for mounting a substrate to be processed provided in the vacuum chamber, and a vertical sputtering target disposed on the susceptor substantially parallel to the susceptor. A sputtering apparatus comprising an oblique sputtering target arranged around the vertical sputtering target with an inclination with respect to the susceptor. 5. A vacuum chamber, a susceptor for mounting a substrate to be processed provided in the vacuum chamber, a target for vertical sputtering disposed substantially parallel to the susceptor, and a target for vertical sputtering. A sputtering apparatus comprising: a plurality of oblique sputtering targets arranged around a target and inclined with respect to the susceptor. 6. A vacuum chamber, a susceptor for mounting a substrate to be processed, which is provided in the vacuum chamber, a target for vertical sputtering arranged substantially parallel to the susceptor, and a target for vertical sputtering. A sputtering apparatus including a target for oblique sputtering, which is arranged around the susceptor at an angle with respect to the susceptor and whose inclination angle or position can be changed.