JP3105849B2 - Sputtering equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering apparatus used in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art A general sputtering apparatus will be described with reference to the configuration diagram of FIG.

A semiconductor wafer (hereinafter, simply referred to as a wafer) 11 held on an anode 1 and a target 20 facing the anode 1 are placed in the same chamber 16. Then, an environment in which a glow discharge is generated is created in the chamber, and a sputter gas (eg: Ar) flowing into the chamber is ionized by generating a weakly-electron plasma to form + ions (eg: Ar ⁺ ). The glow discharge is accelerated by a cathode descending layer generated on the cathode side and collided with the target 20 surface, and the kinetic energy causes the mass of the target material (for example: Al) to be bounced off and deposited on the anode-side wafer 11 on the opposite side. It is configured as follows.

[0004] In addition to the basic structure, the device disclosed in Japanese Patent Application Laid-Open No. Hei 4-26759 has a rotating flange and a ring-shaped rotary sealing mechanism for rotatably rotating the rotating flange at the peripheral edge and supporting the peripheral edge in an airtight state. The target itself is rotated by the rotating flange by interposing a sealing mechanism that expands and contracts in the axial direction between the moving flange in the shape of a cylinder or a short cylinder and the vacuum vessel. This is to improve the uniformity of the film thickness in the same manner as when it is used.

[0005]

The first problem is that in the conventional sputtering apparatus, the cover ridge at the step portion of the sputtered film to be uniformly deposited on the surface of the semiconductor wafer is poor with respect to the unevenness on the surface of the semiconductor wafer. .

The reason for this is that the target surface flying from above the target has a large flying angle because the target surface is sufficiently large with respect to the uneven pattern on the wafer.

The second problem is that the thickness of the semiconductor wafer is uneven due to the structure of the equipment (the center is thick and the periphery is thin).
Is to occur.

The reason is that the probability that the target material will fly to the center of the wafer is increased because the semiconductor wafer and the target are fixed at opposing positions as shown in FIG. At present, an attempt is made to reduce the influence by making the diameter of the semiconductor wafer smaller than the diameter of the target, but no significant effect is seen because the distance between the wafer and the target is sufficient.

As one of the improvement methods, Japanese Patent Laid-Open Publication No.
As described in Japanese Patent No. 759, there is a method of obtaining the same effect as using a large target with a small target. However, this method is to make a pseudo large target around a rotating flange. Although the uniformity of the film is somewhat improved, the tendency of the film thickness unevenness does not change. Moreover, the sputtering rate and the sputtering efficiency are reduced,
There is a problem that the coverage of the uneven surface of the wafer due to the rotation of the target is greatly deteriorated.

A third problem is that, since the distance between the semiconductor wafer and the target is sufficient, most of the target material dispersed by the sputtering gas on the target surface adheres to the side wall of the chamber other than the surface of the semiconductor wafer to become particles and become particles. Is to pollute.

A fourth problem is that when the target surface is sputtered, unevenness of the electric field appears as irregularities on the target surface as it is (erosion), so that the target needs to be replaced earlier than the original target life. Is the thing. In addition, there is a third problem with the target, and the maintenance period cannot be extended too much, so that a short-time specification with a thin sputtered material layer is used. And the equipment operation rate decreases.

The reason is that, since the target and the wafer are fixed, the collision frequency and intensity of the ionized sputter gas due to the unevenness of the electric field generated on the surface of the target create unevenness of the fixed unevenness on the target surface. is there.

Therefore, the target life is limited by the concave target film thickness. (If the target material is used in conformity with the convex structure due to the thin structure of the target material layer, the concave portion sputters the metal to which the target material is attached. On)
The transfer of unevenness to the semiconductor wafer surface due to the unevenness of the target surface is also a concern.

A first object of the present invention is to provide a sputtering apparatus capable of forming a sputtered film with good coverage even on an uneven surface of a wafer.

A second object of the present invention is to provide a sputtering apparatus capable of suppressing the generation of particles from the chamber wall.

A third object of the present invention is to provide a sputtering apparatus capable of reducing the frequency of maintenance due to a reduction in the life of a target.

[0017]

According to the present invention, there is provided a sputtering apparatus comprising: an anode for holding a semiconductor wafer; one or more targets provided to face the anode and having a smaller diameter than the wafer; And a target scanning means for scanning the target in a specific pattern while maintaining a constant narrow gap.

The sputtering apparatus of the present invention has a target diameter smaller than that of a semiconductor wafer and scans the surface of the wafer in a specific pattern, thereby solving the problem caused by the conventional equipment structure in which the central portion of the wafer is thin. it can.

As shown in FIG. 7, in the narrow gap state as in the sputtering apparatus of the present invention, when viewed from the pinpoint, a sputtered film is formed concentrically around the wafer portion near the target head. By setting the scanning pattern and the speed in consideration of the concentric film thickness distribution at this time, a sputtered film having a uniform growth film thickness can be formed on the wafer surface. For this purpose, a mechanism for monitoring the amount of pinpoint spatter by monitoring the gap between the target and the semiconductor wafer is provided as a monitoring factor of the operating state of the apparatus.

Further, in order to improve the flying angle of the sputtered material to the wafer and to prevent spattering other than the sputtered material, FIG.
As shown in (a), the target side surface has a barrier composed of an insulating shield and an electromagnetic shield.

The flying angle of the sputtered material relative to the wafer can be freely adjusted by the positional relationship between the frontage of the barrier and the target sputtering surface.

Basically, the flying angle is sufficiently smaller than that of the conventional target and the flying angle of the target material is limited to only the direction perpendicular to the wafer by lowering the sputtering surface of the target from the surrounding barrier surface. The electromagnetic shield has the effect of slightly converging in a direction close to the vertical.

Lastly, by performing sputtering while maintaining a narrow gap (several mm to several cm) between the sputtering surface of the target and the semiconductor wafer, the conventional sputtering material is wasted (mostly the side wall of the processing chamber other than on the semiconductor wafer). ), And the life of the target can be greatly extended by the columnar target and the rotary target surface adjustment mechanism. Therefore, it is possible to reduce the number of particles, reduce the maintenance frequency, and improve the equipment operation rate.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. FIGS. 1A and 1B are a configuration diagram of a sputtering apparatus (target rotating scan type) and a top view of a target portion for explaining a first embodiment of the present invention.

Referring to FIGS. 1A and 1B, the sputtering apparatus according to the first embodiment includes an anode 1 provided in a chamber 16 for holding a wafer (sample) 11, and
, Which is located below the anode 1 and is opposed to the anode 1,
It comprises a columnar target 3 having a smaller diameter, a rotation drive mechanism 7 composed of an inertia ring 2 and a motor, a target base 9 and a target 10, etc., and has a specific pattern shape while maintaining a constant narrow gap with respect to the surface of the wafer 11. 1. The scanner mainly comprises a target scanning means for scanning the columnar target 3, a gap monitor 8 for monitoring a gap by the capacitance between the surface of the wafer 11 and the surface of the target 3, and a target drive controller 18.

In FIG. 1, reference numeral 4 denotes a target shield, 5 denotes a sputter gas inlet, 6 denotes an exhaust port, and 19 denotes a dustproof sheet. As the gap monitor, a laser light gap measuring device using a Michelson-Mole interferometer, a micrometer, or the like can be used.

In the first embodiment configured as described above, as shown in FIG. 1B, the target rail 10 runs in the center of the inertia ring 2 of the target base, and the target base 9 moves along the center. It has a moving structure, the inertia ring 2 rotates, and the target base 9 moves on the target rail 10, so that concentric sputtering can be performed along the surface direction of the wafer 11.

The drive controller 18 has a function of detecting the position of the target base 9 in the X and Y directions and controlling the position of the target base 9, and a function of detecting the position of the moving target base 9 from the rotation axis on the wafer. It has a function to control the scan speed (linear velocity) to be constant. Therefore, the thickness unevenness of the sputtered film formed on the wafer 11 is determined by the moving speed and accuracy of the target base 9.

The pattern drawn by the target 3 under the control of the drive controller 18 is, for example, a scanning pattern as shown in FIG. At this time, it is necessary to grow a uniform sputtered film on the wafer.
The rotational speed of the inertia ring 2 of the target base is adjusted according to the distance from the center of the target, and the relative speed between the sputter surface of the wafer 11 and the columnar target 3 is always constant (constant linear velocity)
As shown in FIG. 7, a uniform concentric sputtered film can be grown by making the film thickness at the pinpoint constant as shown in FIG.

Further, in the case of this structure, the target base 9 moves in the direction of the diameter of the wafer while rotating, so that the rotation of the target base 9 is eccentric or vibrated due to its own weight, which adversely affects the operation accuracy and is therefore large. The installation of a target-based inertial ring 2 with an inertial mass eliminates these adverse effects.

The columnar target 3 is, as shown in FIG.
Columnar target 3 on target base 9 having drive unit
It has a structure that rides. This columnar target 3
In the lower part of the figure, a cathode-side gap monitor electrode 13 and a rotary target elevator 14 are attached, and as shown in FIG.
And an insulating shield 4A.

As shown in FIG. 4, the columnar target 3 has a target elevating groove 15, and the rotation and vertical movement of the rotary target elevator 14 and the fixing of the target ensure the accurate and accurate vertical movement of the target. Has a possible function.

Next, the flying angle at the time of target sputtering will be described with reference to FIG. As shown in FIG. 6A, an electromagnetic shield 4A made of quartz, Teflon, a resin film and the like and a coil and the like are provided around the columnar target 3.
A barrier composed of the sputter protection shield 4B is formed.

An electromagnetic wave is generated from the electromagnetic generation / sputter protection shield 4B to form an electromagnetic shield 4C to protect the side wall of the columnar target 3 from the sputter gas, and to concentrate the collision of the sputter gas on the target sputter surface. In the same way, by using the difference in the height of the target sputtering surface and the opening of the barrier to prevent the scattering direction of the particles of the sputtering material dispersed from the target sputtering surface from scattering in the lateral direction, the particles of the sputtering material It is possible to limit the direction to the wafer.

That is, the target sputtering surface 21A
Is high, the sputter angle becomes wide, and the particles 3A of the sputter material scatter at a wide angle. As indicated by the broken line, the sputtering surface 2
When 1B is lowered, the spread of the particles 3B of the sputter material becomes narrow. Therefore, as shown in FIGS. 9A and 9B, the flying angle on the surface of the semiconductor wafer 11 is reduced (θ ₁ > θ).
₂ ) As shown in FIG. 9B, the coverage of the sputtered film 22 can be improved with a fine uneven pattern.

Further, since the frequency of collision of the sputtering gas with the vicinity of the barrier is reduced by the electromagnetic shield 4C, assuming the actual operation state, the target sputtering surface 21A is formed as shown in FIG.
The shape as shown in (b) is obtained, and the scattering of the target material in the direction of the semiconductor wafer is increased.

Further, by making the gap between the target sputtering surface and the semiconductor wafer a narrow gap, waste of the target material can be eliminated and generation of particles due to the adhesion of the target material to the side wall of the chamber can be reduced. In addition, the use of the above-mentioned columnar target and the rotary target sputtering surface adjustment mechanism enable the long-term target to be used without being affected by erosion of the sputtering surface, thereby reducing maintenance frequency, improving equipment operation rate, and reducing particles. And the like.

FIGS. 2A and 2B show a sputtering apparatus (target XY) for explaining a second embodiment of the present invention.
It is a block diagram of a direction self-propelled type) and a top view of a target part.

In the second embodiment, the scanning by rotation is not performed as in the first embodiment.
By using the XY scanning mechanism constituted by the X-direction target rail 10B and the Y-direction target rail 10A as shown in FIG. 5B, a more uniform sputtering film can be obtained by a target scan pattern as shown in FIG. Is formed. Other configurations are almost the same as those of the first embodiment.

In the second embodiment, since the above-described configuration and operation are performed, a scanning pattern as shown in FIG. 5B is obtained. At this time, the difference from the first embodiment is that the semiconductor wafer is uniformly scanned on the semiconductor wafer by the XY scanning mechanism shown in FIG. Produces the same effect as In addition, although there is no rotating part, the structure becomes simple, but the operation becomes complicated, so accuracy is required.

FIGS. 3A to 3C show a sputtering apparatus (target XY) for explaining a third embodiment of the present invention.
FIG. 2 is a configuration diagram of a sample self-propelled rotation type), a top view of a target portion, and a bottom view of an anode-side gap monitor electrode.

In the third embodiment, the wafer 11 is held and rotated by the anode-side gap monitor
The second embodiment is designed to take advantage of the advantages of the second embodiment and the second embodiment.

The structure is such that the semiconductor wafer 11 itself is rotated by the anode rotation drive mechanism 7A controlled by the target drive controller 18, and the target base 9 is rotated by the XY scanning mechanism shown in FIG. 3B. The upper part can be scanned in an arbitrary pattern. In the first embodiment, FIG.
As shown in the figure, the centrifugal force due to the rotation greatly affects the operation of the target base 9 because the target base 9 is located on the inertia ring 2 of the target base. By doing so, the accuracy for in-plane uniformity can be further improved. Further, since the semiconductor wafer 11 itself is rotated and the target base 9 can be scanned in the X and Y directions, fine adjustments to the film thickness uniformity can be made.

In the above embodiments, one columnar target having a diameter smaller than the diameter of the wafer has been described. However, a plurality of columnar targets having a diameter smaller than the diameter of the wafer are fixed on the target base. May be used. When a plurality of targets having the same area of the sputter surface as one target are used, the coverage of the sputtered film is further improved.

[0045]

The first effect is that the cover ridge by the target material on the uneven portion of the semiconductor wafer is improved. The reason is that the flying angle of the target material flying from above the target can be reduced as described above.

The second effect is that unevenness in film thickness caused by a flat plate (magnetron) sputtering method can be improved. The reason is that, in principle, the semiconductor wafer and the target are not fixed at a position facing each other, so that the sputter rate and the uniformity of the gap fixed film thickness can be dealt with by the scanning accuracy of the target.

The third effect is that the generation of particles is small due to the small amount of extra sputtered material adhered to the inner wall of the chamber, the maintenance period is sufficiently long, and the operation time is improved. The reason is that since sputtering is performed with a narrow gap, there is almost no useless scattering of the target material wrapping around the side wall of the chamber.

The fourth effect is that the expiration date of the target itself is greatly extended, and the extension of the maintenance period and the improvement of the operation rate can be expected in addition to the third effect. The reason is,
By using a columnar target, a gap monitor between the semiconductor wafer and the target, and the use of a rotary gap adjustment mechanism,
This is because the problem of the film thickness of the target material and the problem of fixing the unevenness of the sputtering surface do not occur.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a sputtering apparatus and a top view of a target unit for explaining a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a sputtering apparatus and a top view of a target unit for explaining a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a sputtering apparatus for explaining a third embodiment of the present invention, a top view of a target section, and a bottom view of an anode-side gap monitor electrode.

FIG. 4 is a configuration diagram of a columnar target used in the embodiment.

FIG. 5 is a view showing a scanning pattern of a target.

FIG. 6 is a diagram showing a structure near a sputtering surface of a target.

FIG. 7 is a diagram showing a film growth model during scanning sputtering.

FIG. 8 is a basic configuration diagram of a conventional sputtering apparatus.

FIG. 9 is a diagram for explaining a cover ridge of a sputtered film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Anode 2 Inertial ring 3 Columnar target 4 Target shield 4A Insulation shield 4B Electromagnetic generation / sputter protection shield 4C Electromagnetic shield 5 Sputter gas introduction part 6 Exhaust port 7 Rotation drive mechanism 8 Gap monitor 9 Target base 10 Target rail 11 Wafer (sample) 12 Anode-side gap monitor electrode 13 Cathode-side gap monitor electrode 14 Target elevator 15 Target elevating groove 16 Chamber 18 Target drive controller 19 Dust-proof shield 20 Target 21A, 21B Target sputter surface 22 Sputtered film

Claims (7)

(57) [Claims] An anode for holding a semiconductor wafer, one or more targets provided opposite to the anode and having a smaller diameter than the wafer, and specified while maintaining a constant narrow gap with respect to the surface of the wafer. And a target scanning means for scanning the target in a pattern as described above. 2. The sputtering apparatus according to claim 1, wherein the target is provided below the anode. 3. The sputtering apparatus according to claim 1, further comprising a wafer rotating means for rotating the wafer. 4. The sputtering apparatus according to claim 1, further comprising a gap monitor for monitoring a gap between the wafer and the target. 5. The sputtering apparatus according to claim 1, wherein the target is formed in a column shape. 6. The sputtering apparatus according to claim 5, further comprising a rotary target extrusion supply unit. 7. A barrier comprising an insulating shield and an electromagnetic shield for preventing a sputtering gas from colliding with a target side wall and controlling a flying angle of a sputtered substance is provided on a side surface of the target. Item 7. The sputtering apparatus according to Item 6.