JPS5871372A - Method and device for film formation by sputtering - Google Patents

Abstract

PURPOSE:To reduce damages by the inflow of the charged particles of a substrate in a planar magnetron type sputtering device by combining respective magnetic pole terminals with magnetic field control means consisting of permanent magnets and soft magnetic materials. CONSTITUTION:The 3rd magnetic terminal 24 of a soft magnetic material is provided to magnetic pole terminals 22, 23 of magnetic materials and permanent further an energizing coil 24a is provided to intermediate space of the terminals 22, 24. The respective magnetic pole terminals are coupled magnetically by a yoke 26. An anode 30 of a central part is provided to the anode 29 around a disc-like flat plate 21 which is a target. A negative voltage is applied to a cathode 27, a voltage near the ground is applied to the anode 30 and the anode 29 and the vacuum vessel are grounded, then while the inflow of the charged partices to the substrate to be formed with film is held decreased, glow discharge is caused and sputtering is effected. If the energizing current to be supplied to the coil 24a is changed, the point where the magnetic lines of force parallel with the plate 21 is moved and the plasma region can be consequently moved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to allifing thin film materials by sputtering.
The present invention relates to a film forming method using sputtering and an apparatus therefor.

In the sputtering technology, a low-pressure atmospheric gas is ionized (plasma-like) by causing a glow discharge, and the plasma-like ions are accelerated by the fc'It pressure applied between the negative and anode electrodes and placed on the 1W# cathode. It is struck by a slab of target material.

This is a technique in which constituent molecules or particles of the target material ejected by the collided ions adhere and deposit on a substrate placed in close proximity to form a thin film of the target material.

In this case, the ions generated by the glow discharge are highly confined in the space and transported effectively onto the target material plate, which improves the deposition rate and reduces damage to the substrate caused by particles. It has become important.

Ninth, it is effective to confine the ions to a spatial region on the flat surface of the target material and increase the density. And Fi! The i-world configuration has been studied.

In particular, planar magnetron sputtering equipment
K has a deposition rate comparable to that of conventional resistance heating vacuum evaporation equipment, and in recent years has come to be widely used in the production film forming process as a thin film forming equipment for thin film integrated circuits and semiconductor devices. .

FIG. 1 is a conceptual sectional view showing the structure of a planar magnetron type sputtering apparatus in the vicinity of a flat plate of a target material according to well-known prior art. A ring-shaped magnetic inertia 2 magnetically coupled to the back surface of a target material flat plate (hereinafter referred to as target) 1 by a yoke 6, and its ring-shaped magnetic pole 2.
A cylindrical magnet 3 is placed in the center of the fB air circuit tsya, and the distribution of magnetic flux lines is distributed in the space on the surface side of the target 10 (lower side in Fig. 1).In other words, the height of the torus (Tonw) is A tunnel-like magnetic field distribution 11 is generated in which the target 10 is cut in half by a flat plane with the half-cut plane parallel to the surface of the target 10 . This tunnel-like magnetic field distribution 11 confines the plasma-like ions in a highly concentrated manner (not shown).

These plasma-like ions were further generated by high voltage applied to @&10 and l[7 installed on the back surface of the target. The surface of the target 10 is accelerated by an electric field of Y*, collides with the surface of the target 1, and as a result, the atoms or particles are sequentially ejected from the surface of the target 1, forming an eroded region 12.

As estimated from one or more of the above explanations, this erosion region 12 becomes more eroded as time passes during the sputtering process, and this erosion usually occurs in the target structure shown in FIG. To progress limited to a specific area of the target! j! It is said that only the volume of the eroded area can be used effectively.

Therefore, even if the desired uniform film thickness distribution is initially obtained, the formation of such erosion areas changes the direction and amount of the ejected atoms of the target material, causing the surface of the sample substrate to change. The thickness distribution of the thin film to be deposited is not uniform, resulting in a quadratic curve-like distribution convex downward or a quadratic curve-like distribution convex upward.

However, if you want to obtain a large film thickness or perform a long sputtering process, it is impossible to do so, and this is considered to be a limitation of conventional sputtering targets.

Subsequently, in order to eliminate this drawback, it was proposed to change the KtB field distribution 11t so that the erosion region 12 is generated over a wide area on the surface of the target 1.

In this conventional brainer magnetron type sputtering system, the maximum target erosion occurs in the area where the magnetic field lines are aligned with and underlying the above point or area where they are parallel to the target plate, thus generating an auxiliary variable magnetic field in a direction perpendicular to the source with respect to the magnetic field generating means, and continuously varying the auxiliary variable magnetic field until the resultant magnetic field lines are parallel to the source; Amano is to be moved.

In this way, in the conventional device, the glow discharge moves according to changes in the magnetic field distribution in the nuclear hollow space. A large amount of electrons, which are relatively distant and are part of charged particles as a discharge current, may also flow into the sample substrate side. If such an electron beam flows into the sample substrate, it may cause permanent damage to the semiconductor elements already formed on the sample substrate, resulting in a defective product.

The object of the present invention is to eliminate the above-mentioned conventional drawbacks.

In addition to being able to form a uniform film, it also greatly reduces the amount of negatively charged particles flowing into the sample substrate on which the film is being formed.
The present invention provides a method for forming a film by sputtering that reduces damage to a sample due to the inflow of charged particles, and a unit thereof.

That is, in the present invention, in view of the fact that when magnetic lines of force are generated from a negative magnetic force line source, they do not interlink as a matter of their nature, and an attractive force or direction of mutual I/cm x wall stress acts on the lines of magnetic force. Excitation that configures a - magnetic field line source with magnetic poles and controls the magnetic field lines generated at some of the magnetic poles to move the position of the magnetic field line distribution emitted from the remaining magnetic poles, that is, the position of the plasma region. Using a planar magnetron electrode equipped with a means (electromagnet), a dead weight current having a predetermined period is caused to flow through the excitation means, and an electric potential close to ground is applied to an anode provided around and at the center of the electrode. The bottom film reduces the inflow of charged particles into the target substrate.

The annular plasma generation region is moved at least once in a predetermined period of 70 cycles, and the thickness obtained in each annular plus one generation region is synthesized.

Embodiments of the present invention will be described in detail below with reference to the drawings.

Figure g2 is a sectional structural view of one embodiment of a target structure of a planar magnetron type sputtering apparatus according to the present invention.

In Figure 92, 21 is a target disc-shaped flat plate made of the material to be sputtered, At-2%Si (purity 99.999%).
Materials and shapes with a diameter of 8"ψ and a plate thickness of 2Drnrnt were used. 22 is the first ffi pole tip, made of a soft magnetic material (high permeability magnetic material), 23 is the second pole tip, made of a permanent magnetic material. 24 is the S-th a-end according to the present invention and is made of a soft a-based material. 24a is an excitation coil also according to the present invention, which is located between the first pole end 22 and the 30a-th end 24. A toroidal coil wound 300 times in space,
25 is a medium for cooling the target disc-shaped flat plate 21, in this case, a water inlet/outlet pipe; 26Fi 1. A yoke for magnetically coupling the second and third magnetic pole tips as a whole, made of a soft magnetic material, 27 a cathode, and 28 an insulating layer plate.

32#i erosion area. 29 and 30 are a first anode and a second anode to which a voltage close to ground is applied.

They are provided around the target material flat plate 21 and at the center of the target material flat plate 21 so as to be electrically insulated from the target material flat plate 21. The second anode 30 is constructed by purchasing the sputtered electrode structure shown in FIG.
It is cooled by a conduit with a coaxial structure and electrically led out to the back side of the structure.

Both FIG. 3 and FIG. 4 are explanatory diagrams of the operation of the sputter electric deflection structure of the planar magnetron type sputtering apparatus shown in FIG. 2, and show the magnetic flux distribution on the target material flat plate 21. Each of the figures in Figures 3 and 4! 501.
401 is the height W) above the target material flat plate 21, and! 02,402 indicates the radial distance from the center of the target material disk.

In both FIGS. 3 and 4, the excitation coil 24g has the polarity of the gi pole in the second magnetic pole tip 22.

A control current is passed in a direction opposite to the polarity of the flat plate of the target material caused by the permanent magnet.

FIG. 3 shows the case where this control excitation current is not passed as OA. Also, in Figure @4, this control excitation current is 7A.
This is the magnetic flux distribution at the time of tomo.

As is well known, in a planar magnetron sputtering electrode, a plasma region is formed around the point where the magnetic field lines on the target material flat plate are parallel to the target material flat plate. A flat plate 32 of target material at a close distance is eroded.

As shown in FIGS. 3 and 4, in the sputtering electrode according to the present invention, by changing the current flowing through the excitation coil, it is possible to move the point where the magnetic field lines are parallel to the target material flat plate, and therefore the erosion area I can see that 32wo should be moved as well.

By the way, when the permanent magnet 23 does not flow the control current through the excitation coil 24g attached to the third magnetic pole tip, 2
00~300 Gauss (αoyb, hawk) or more O magnetic field, 3rd. The line of magnetic force on the target flat plate in FIG. 4 was determined to be strong at a point where it is parallel to the target flat plate.

The following will briefly explain the sputtering process as it is incorporated into the sputtering process.

First, although the target structure according to the present invention is not shown in the drawings, it has a well-known Makabe exhaust system, a shutter, an Ar gas introduction system, two gate pallets 1, and a transport means capable of continuously transporting wafers. It is installed on a part of the wall of a vacuum chamber with a Next, place the target disk-like flat plate 21 at a distance of 70 degrees from the surface of the target disk-like flat plate 21 at the upper 9JHK (inverted arrangement in FIG. 5) where the magnetic flux lines of the target disk-like flat plate 21 are formed. The substrate on which the film is to be formed is mounted and held parallel to its surface by well-known holding means. Next, this vacuum tank t-1 to 5X10 = Torr is completely evacuated, and after exhausting, 4R gas is introduced from the 4R gas introduction system, and the Ar gas pressure is set to t-2 to 20 Torr.

Next, 0 to +
50V, -400V is applied to the cathode 27, and the first anode 2
9. When the vacuum chamber (not shown) is connected to ground, the Ar gas causes a glow discharge, but at this time, the excitation coil 24g
When the FiJ magnetic current applied to the target plate is changed by about 0 to 7 A, the point where the magnetic field lines shown in Figs. However, we were able to experimentally confirm that the confined plasma region was moving by visually observing it.

Figure 5 discloses the greatest technique made possible by this embodiment, which is to form an arbitrary film thickness distribution with respect to the center of the substrate from the film thickness distribution obtained by sputtering. was obtained.

This is a collection of five diagrams and some experimental results,
This figure shows the change in the film thickness distribution within the substrate with respect to the radial distance from the center of the substrate when the control current applied to the excitation coil 24a is changed. A solid line 501 (0 mark) indicates a downwardly convex film thickness distribution.

Solid line 5Q4 (○ mark) is almost uniform film thickness distribution, solid line 505
(○ mark) indicates an upwardly convex film thickness distribution.

Based on the above experimental results, the current flowing through the excitation coil 24G is set to a current waveform in which 12 seconds is the first phase, the excitation current #L is 7A for the first 4 seconds, and the excitation current is OA for the remaining 8 seconds. .

Next, the substrate to be film-formed was transported so as to directly face the first main plane of the target flat plate, the shutter for the target structure (not shown) was opened t-, the cathode voltage was 350V, and the cathode current was 15/I. Target material At-2%Si t-
The film was deposited on the substrate for 2 minutes.

By the way, the first substrate of the target plate and the target flat plate at this time
The distance from the main surface was 705 m.

After the scheduled deposition time has elapsed, the shutter is closed and At-2%
The same process was repeated for more than 1 time after the entire deposition process was carried out, and nine substrates (Si wafers) were taken out by opening the gate valve. Checked.

FIG. 6 shows a part of the experimental results, in which 601 shows the conventional film thickness distribution within a wafer, and 602 shows the change over time in the film thickness distribution within a wafer using the target structure according to the present invention. The effects of the present invention are obvious. Furthermore, the At-2% SL film thus formed showed good electrical properties as a film for semiconductor wiring.

It is clear from the inventors' research that such good EVA endometrial distribution and electrical properties are extremely dependent on the shape of the eroded region on the surface of the target disk-shaped plate facing the sea urchin. However, the erosion area 32 in FIG. 1 is extremely narrow as the erosion progresses locally, and as time passes, the center of the erosion area 320 is preferentially eroded, and finally the target disk The thickness of the target disc-shaped flat plate 21 is reached, and the target disc-shaped flat plate 21 becomes unusable.

On the other hand, in the erosion region 32 in FIG. 2, by selecting the current waveform that passes through the excitation coil 24a and periodically moving the plasma region, uniform and good film formation distribution characteristics can be maintained over a long period of time. It was possible to form an eroded region relatively uniformly over a wide area of the target material flat plate.

This has the effect of ensuring a long life of the expensive target material flat plate 21, and also greatly reducing the dead time mainly due to the replacement of the target material flat plate, which is a major gap in the production process. be.

FIG. 7 shows the effect of the anode according to the present invention. In the sputtering electrode of the present invention, when the current flowing through the excitation coil is increased, the plasma region can be contracted to the center on the target plane. However, in this case, a portion of the discharge current may flow into the substrate and damage the semiconductor elements on the substrate.

A curve 701 in FIG. 7 represents the defect rate of elements on one substrate when the anode according to the present invention is not provided. If the radius of the plasma ring is less than 50W, the defect rate increases. The defect rate of elements on one substrate when the anode according to the present invention is installed is shown by a curve 702 in the figure, and the effect of the anode according to the present invention is clear.

FIG. 8 is a sectional view of another embodiment of the target structure of the Glenner magnetron sputtering apparatus according to the present invention. The difference between the configuration in FIG. 8 and that in FIG. 2 is that instead of using a permanent magnet for the second magnetic pole tip 31, a second multi-turn, nine excitation coil 31g is attached to a soft magnetic material. Setup is the runner-up. The other symbols have exactly the same meanings as the symbols in Figures 2 to 5.

The technical idea of the present invention also includes the configuration of this embodiment, and the difference between the two operations in this embodiment and that shown in FIG. 2 is as described above, and W1
The magnetic flux generated by the second magnetic pole tip 31 and the third magnetic pole tip 24 can both be controlled. The process leading to the generation of other plasma regions is the same.

FIG. 9 shows a schematic configuration of the excitation electric power W of the electrode structure shown in FIGS. 2 and 8. FIG.

The main configuration of the excitation power supply section includes two current supply circuits for controlling the inner electromagnetic coil 31α and the outer electromagnetic coil 24a completely separately. The excitation power supply section #nuclear inner and outer electromagnetic coils 31α, 24
The current applied to α can be set completely arbitrarily, that is, to a constant voltage #L that does not change over time, or to a current waveform such as a rectangular waveform or triangular waveform with a constant period! It uses an microprocessor 41 and a memory 42,
A keyboard 43 or a suitable external storage device 40 (e.g. magnetic tape, magnetic disk) provides information regarding the predetermined current waveform, and the output of the microprocessor 41 is routed 44b (D-) to a digital-to-analog signal transformer 44. A converter) and a current amplifier 45a, 4
5b, it is amplified to a predetermined intensity sufficient to excite the inner and outer electromagnetic coils 24 and 25.

The excitation power supply unit in FIG. 9 handles 24α to the inner and outer electromagnetic coils 31 as a control target, so a power supply with constant current characteristics is required, and the output current detection unit 466, 466 outputs Current amplifiers 45G and 45b detect the current, that is, the current value of each electromagnet, and compare it with a predetermined current value outputted from Dμ converter 44 by 44b to perform correction.
has the means to return information to In other words, a constant current is applied to the electromagnetic coil 2425 so that a constant rectangular wave current is applied to the electromagnetic coil 2425.

As is well known, high-voltage power supplies for supplying the discharge force for sputtering, that is, sputter power supplies, have output voltages in the range of 0-a00V and 0 to 0.
A device with an output current of about 15 A was used. Also, as is well known, this high-voltage power supply has constant current output characteristics in order to control the power input to the glow discharge.

With the above configuration, the magnetic material is magnetically saturated,
Excessive magnetic flux lines can be used with greater ease of control (if the second magnetic pole tip 11 is a permanent magnet, it is limited to a thin plate, so it seems that it cannot be used practically) effect occurs. Therefore, conventionally, sputtered film deposition of magnetic materials was only possible with facing target type sputtering equipment, but with the present invention, it is now practically possible with planar magnetron type sputtering equipment. The thing is, the 1st VB
Regarding the special case of the extreme, g2 magnetic pole tip, and third ffl extreme, each magnetic pole tip can be controlled by any combination of a permanent magnet, a magnetic field control means consisting of a soft magnetic material (high-speed aSS material), and an excitation coil. It is clear that all the magnetic field control techniques to be realized are included in the technical idea of the present invention.

As mentioned above, according to the present invention, the life of the target disc-shaped flat plate can be extended, and an arbitrary deposited film thickness distribution can be obtained. This has the effect of significantly reducing the inflow of charged particles into the sample and reducing damage to the sample.

Figure 1 is a cross-sectional structural diagram showing the electrode structure of a conventional planar magnetron sputtering device, and Figure 2 is a sectional view of the electrode structure of a conventional planar magnetron sputtering device.
A cross-sectional structure diagram showing an example of an IM of an electrode structure of a planar magnetron sputtering apparatus by AK, FIGS. 5 and 4 are magnetic flux distribution measurement diagrams using the sputtering electrode structure of FIG. FIG. 6 is a diagram showing the time-dependent change characteristics of the thickness distribution of a film formed by the conventional sputter electrode and the embodiment of the present invention, and FIG. 8 is a sectional structural diagram showing another embodiment of the electrode structure of the planar magnetron sputtering apparatus of the present invention, and FIG. 9 is a diagram illustrating the effect of installing the second anode according to the present invention. 89 is a diagram showing a power source for excitation of the electrode structure of FIG. 89; FIG.

21... Target disc-shaped flat plate 24... Third magnetic pole tip 24g... First excitation coil 26... Yoke 27... Cathode 2
9...First anode 30...Second anode 31...Central magnetic pole tip 31 Country 12 Note 3 Mouthlessness 4 trouble 02 15 Target consumption time E hours] Figure r7' 50 100 Plasmalin')'Half Inventor: Hideki Tateishi, Hitachi, Ltd. Production Technology Laboratory, 292 Yoshida-cho, Totsuka-ku, Yokohama

Claims (1)

[Scope of Claims] (11) having at least three magnetic poles and at least two magnetic field generating means;
One uses a planar magnetron electrode equipped with an electromagnet.
A state in which a current with a predetermined circumference is passed through the electromagnet, and a potential close to ground is applied to the anode provided around and at the center of the electrode, thereby reducing the inflow of charged particles to the substrate to be film-formed. Then, the annular plasma generation area is moved at least once or more at a predetermined period, and the film thickness obtained in each annular plasma generation area is synthesized to form a film on the substrate to be formed. Characteristic film formation method using sputtering. (2) having at least three magnetic poles and at least two magnetic field generating means, at least one of which comprises a nine planar magnet C1/electrode f; A control means is provided for causing current to flow at a predetermined period through the electromagnet. A deposition apparatus using sputtering, characterized in that an anode to which a potential close to ground is applied is provided around the electrode and at the center thereof.