JPS5830389B2 - TADANTARI - Sputtering Souch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for sequentially depositing layers of different materials on a substrate by sputtering, with the texture of the interfaces of these layers being strictly controlled.

In sputter deposition, the deposition of material is the result of ion bombardment of a target.

The impact ions eject target atoms at high speed,
The atoms end up being deposited on a suitably exposed surface, usually the substrate.

Typically, the target is physically and electrically connected to the cathode, and the substrate is placed on top of the anode.

These ions are formed from an inert gas or mixed gas existing between the anode and cathode to which a DC or RF constant potential is applied.

For many sputtering applications, it is necessary to produce a multilayer structure of different material layers with precisely controlled thicknesses and completely contamination-free interfaces between the layers.

This is especially necessary when manufacturing electronic circuits or equipment used in outer space exploration.

In this case, what kind of influence does the contamination between the layers have on the performance of the device in the space environment or in terms of long-term operation?
Because it is unknown, this contamination cannot be tolerated.

Sputtering devices are known which are capable of depositing multiple layers of different materials on one substrate.

Generally, each target is supported by a separate cathode with a separate power supply circuit.

After a layer of the first target supported on one cathode has been deposited, the supply circuit of the other cathode is energized.

Then, after a target washing period, which can be on the order of several hours, the first layer is exposed to the washed target and a second layer is deposited from the second target.

Unfortunately, during the period between the deposition of the first layer and the beginning of the deposition of the second layer, the top surface of the first layer becomes contaminated.

Such contamination inhibits the formation of a complete deposited layer interface.

Manufacturers of multilayer units ignore the fact that each layer interface becomes contaminated.

This is because, when sputtering is applied to the manufacture of commercial products, the effects of this contamination are reduced by sintering, or annealing.

However, in applications where the presence of any contamination is not tolerated, annealing is of no value.

Conventional sputtering apparatuses that are capable of depositing materials from different targets onto a single substrate do not allow the deposition rate of the materials for each target to be controlled separately.

As is known, the materials used for sputter deposition each have a different deposition rate, and it is therefore important to be able to control these sputter rates individually.

The conventional sputtering apparatus also has a plurality of cathodes provided for each target, and each of these cathodes is configured to have a separate power supply circuit.

This increases the initial cost of the device and makes maintenance difficult.

The present invention solves the above-mentioned drawbacks of the conventional method by providing a sputtering apparatus equipped with a single cathode to which a plurality of targets made of different materials are physically and electrically connected. be.

The anode supports a substrate on which multiple layers of different materials are deposited.

The anode is spaced apart from the cathode.

Multiple perforated plates are spaced apart from each other and buttoned.
It is disposed near the cathode and facing the anode.

The plates allow the plasma to extend in a column from one plate toward the anode, and confine the plasma to prevent it from expanding and to prevent cross-contamination of sputtered material between targets. .

Additionally, a plurality of spaced apart perforated bias shields are positioned behind the plate and opposite the anode.

These bias shields are charged with a potential gradient increasing toward the anode potential and simultaneously control the cross-sectional area of each plasma column and, therefore, the plasma current.

A separate bias ring is located in the path of each plasma column between the anode and the bias shield.

The rings can be connected to different bias voltages.

The function of this bias ring is to control the current to each plasma and thus the rate of deposition from each target independently of the rate of deposition from other targets.

The plate, bias shield button, and bias ring are arranged to prevent cross-contamination between targets.

Additionally, the device of the invention includes a movable shutter.

The shutter is initially positioned so that although the target is being cleaned, no material from the target reaches the substrate.

Next, the shutter exposes the substrate on the anode to the first target.

After depositing the desired layer thickness, the shutter and the anode supporting the substrate are rotated together to expose the anode to a second target of material to be deposited next.

This target is such that as the substrate converts from one position to the next during its conversion period, material is initially deposited from the first target and then the substrate is transferred to the first and second two targets. It is deposited continuously on the substrate so that when the substrate is located in the middle, it is deposited from both targets, and finally when the substrate is aligned with the second target, it is deposited only from the second target. It is arranged like this.

Continuous deposition of material onto the substrate as described above eliminates the possibility of contamination of the interface between deposited layers and ensures interface integrity.

Embodiments of this invention will be explained with reference to the drawings.

In FIG. 1, 10 indicates a gas-tight container connected to a vacuum system 12 and a gas storage chamber 14, such as argon, for example.

As is well known, the vacuum vessel is initially
It is evacuated to a low pressure on the order of Torr, and then a small amount of gas at an appropriate pressure on the order of several microns is filled from the storage chamber 14.

One cathode 15 is supported in the container 10 .

It is shown depending from the top plate 16.

The cathode shall be cooled by cooling fluid from a suitable cooling fluid source (not shown) via an insulating material conduit 18.

The container 10 also supports an anode 20 .

This anode is rotated by a drive unit or motor 22 located outside the container 10 via a shaft 23.

A stationary plate 25 for liquid cooling, with which the rotatable anode 20 is in thermal contact, is fixed to the container 10 by means of brackets 26, for example.

It is assumed that the cooling liquid flows into and out of the grip 5 through the groove 27.

Plate 25 is for removing the heat from anode 20.

To the extent described above, the devices are similar to conventional sputter devices.

As shown in FIG. 1, a cathode plate 28 is attached to the cathode 15 by screws 29. As shown in FIG.

In this play) 28, a plurality of targets 30 are attached.

Since the potential of the plate 28 is a cathode potential, from now on,
We will proceed with the discussion assuming that the target is a cathode 15v7c connection and is supported.

FIG. 2 shows plate 28 and T1. T2. It is a top view of three disc-shaped targets 30 indicated by T3.

As shown, the targets are not symmetrically disposed about the center of plate 28.

Angle between T1 and T2, Angle between T2 and T3, T
The angle between 3 and T1 is 1100.110° respectively
, 140'.

The targets are made of different materials and the layers are deposited either directly on the anode 20 or on a substrate supported by the anode.

This substrate is indicated at 32 in FIG.

T1 and T2 mentioned above. Although the opening degrees of T2 and TJ and T3 and T1 are shown as 110', 110°, and 140', these are not absolute angles but can be arbitrarily selected within a range that satisfies the following conditions.

1. During the cleaning process, the position where the shutter blocks all plasma columns can be secured so that material from any target does not reach the substrate while the target is being cleaned (T3 and T3 are shown in the figure). T).

2. The targets can be arranged so that deposition continues even when converting from one target to another, eliminating the presence of contaminants between the deposited layers.

Similar to conventional sputtering equipment, the anode in a vacuum vessel,
A potential difference is applied between the cathodes.

Typically, the anode is at ground potential and the cathode is at negative several kV.

This large potential difference ionizes the gas within the vacuum container, resulting in glow discharge or plasma.

These ions hit the target and neutral atoms are separated from the target, which is generally called sputtering.Meanwhile, the electrons travel toward the positive anode.

At least a portion of the separated neutral atoms reach the substrate on the anode and are deposited there as a desired layer.

In accordance with the present invention, the anode is at ground potential and a negative potential is applied to the cathode 15 from the RE/DC network 33.

The target must be cleaned before deposition can occur.

For this purpose, a shutter 57 is integrally formed.

The shutter 57 is provided near the anode 20, and its potential is assumed to be the anode potential, that is, the ground potential for the button in this example.

The shutter 57 has an aperture, the location of which is in this example such that the substrate is not exposed to sputtered material from any of the targets when the target is being cleaned. do.

In order to sequentially deposit layers of different target materials and to ensure that each layer consists of only one type of target material, cross-contamination between the plasma and the sputtered material from the various targets must be prevented. It is the most important thing to do.

This restricts the plasma from each target to extend toward the substrate as separate columns separated from other plasma columns, and the fact that the sputtered material from any target This is achieved by ensuring that the substrate is only reached when exposed to.

As shown in FIG. 1, the sputtering apparatus of the present invention includes a plurality of plates 35. As shown in FIG.

Two plates 35 are shown in the figure.

Each plate 35 has three apertures 36 as shown in FIG.
have.

The diameter of each aperture is about 0.5 inches larger than the diameter of the target.

The plates are fixed such that the central axes of the apertures in the plates coincide with the central axis of the target.

Thus, in a horizontal plane, the periphery of each aperture 36 is about 0.64 cm (1/4 inch) from the protruding end of the target.
It's there.

These plates are spaced approximately 0.64 cm (1/4 inch) apart, and these plates 35
The one located closest to the target is coplanar with the front surface of the target.

One aperture 38 is formed in the twisted plate 37 as shown in FIG.

Plate 37 surrounds cathode plate 28.

The diameter of aperture 38 is approximately 0.5 inches larger than the diameter of plate 28.

Plate 37 is located approximately 0.64 cm (1/4 inch) from the periphery of plate 28 and approximately 0.64 cm (1/4 inch) from overlying plate 35. Ru.

play) 35.37 are connected to ground potential.

These plates serve two functions.

The first of these is to prevent cross-contamination of the plasma button and sputtered material.

The second of these is to facilitate the formation of plasma along each layer.

As is known, plasma has a tendency to flow along the longest path.

Since the plasma is formed in the vicinity of each target, it has a tendency to migrate outwardly towards the walls of the vessel 10.

The presence of the ground potential plate confines the plasma towards the anode and shapes the plasma into a column whose outer surface is corrugated as shown in FIG.

This plasma is indicated by 40.

Thus, the plate confines the plasma to the desired columnar shape,
This also prevents cross-contamination of sputtered material between the pillars.

In addition to the plates described above, the device of the invention further includes a plurality of bias shields 42.

In FIG. 1, three shields are shown as these shields.

These shields physically function in the same way as the plate 35.

The shields each have three apertures 36, as shown in FIG.

Shield 42 is also spaced approximately 1/4 inch from the anode.

However, unlike plate 35, which is held at ground potential, shield 42 is connected to a divider circuit 45, represented by a resistor 45a connected between ground and negative potential -■.

The potential of the shield 42 closest to the anode is higher than the potential of the shield 42 closest to the lowest plate 35.

All of the shields 42 will thus be lower in potential than the anode at ground potential.

Due to the potential of the shield, the cross-sectional area of the plasma penetrating through each set of apertures in the shield is limited and the plasma current is therefore reduced, which further means a reduction in the deposition rate.

The bias shield 42 is configured so that the three plasmas are connected to the same three
It should also be noted that the plasma from the three targets is controlled by being drawn into three pillars by flowing through three biased shields.

The shield 42, like the plate 35, also prevents cross-contamination between the three pillars and causes the plasma within each pillar to have a corrugated shape as shown in FIG.

The device of the invention includes separate bias rings 50 for each layer.

A top view of one of the rings 50 is as shown in FIG.

The size of the aperture 52 is the same as the size of the aperture in the shield 42.

Each of the three rings 50 are located on the same plane approximately 1/4 inch below the lowest one of the shields 42.

Each ring 50 is connected to a separate bias power supply 55 (FIG. 5) of negative voltage.

This voltage, like the voltage applied to shield 42, reduces the plasma current and therefore the deposition rate.

However, since each layer has a separate bias ring 50, the plasma directed to each layer is controlled independently of the plasma directed to the other columns.

As further illustrated by the button in FIG.
A pair of shutters 57, 5B are provided.

Each shutter is coupled to motor 22 via a different shaft.

Each shutter has an aperture 59 (see FIG. 6) with a diameter approximately equal to the diameter of the layer to be deposited.

Shutter 57 is used as a barrier when the targets are being cleaned, while shutter 58 functions as a target selector that is used to select the particular target that will deposit the required material.

Except when washing, both shutters are operated by motor 2.
2, it is rotated in all directions.

The use of the apparatus of the invention will be explained using the example of a unit or structure consisting of layers to be produced from targets T1t T2 h and T, 75).

However, T1 and T2 and T2 and T3 centering on the axis of the container.
The area defined by T3 and T1 will be referred to as the 110° area, and the area defined by T3 and T1 will be referred to as the 1400° area.

After the front region of placing the substrate 32 on the anode, and before creating the necessary gas pressure in the container 10, the shutter 57 is rotated so that its aperture is aligned with the column of T. The shutter 58 has an aperture located between T3 and T1.

It can be rotated to a 140° range (see Figure 2).

In the 140' region, the target T0. The passage of the plasma pillars from T2 and T3 is blocked by the shutter 57, so that they do not reach the substrate 32.

Next, a potential is applied between the cathode and anode.

As a result, sputtering of the targets occurs, thereby cleaning all three targets.

It is assumed that the potential is continuously applied during this step.

With the shutter 57 in the 1400 area position as described above, no sputtered material will reach the substrate 32 when the target is being cleaned.

After the target has been washed, the shutter 57 is rotated so that its apertures are aligned with the columns 'l'11/i.

Thus, the substrate 32 will be exposed to the target T1 and hence the deposition of the first layer will take place on the substrate.

The bias of ring 50 on this column is controlled to control the rate of deposition from T1.

After the layer from T1 reaches a predetermined thickness, the shutter 57.
58 and anode 20 are rotated together (clockwise in FIG. 2) to layer T2.

As the anode button and shutter rotate and the substrate 32 and the shutter aperture move from being aligned with column T1 to being aligned with column T2, the conversion of the deposited material is 11
This is done within the 0° region.

The column-to-column spacing buttons placed in the container and the movement of the anode and shutter are such that material is deposited on the substrate whenever the conversion is complete.

As the board button and shutter move away from the T1 pillar, T1
The amount of material deposited on the substrate gradually decreases until the substrate is completely shielded from the T1 pillar and the TJ
Arrived at lining up.

Only material from T2 then becomes deposited for the formation of the second layer.

Board and shutter 57 button and 58 hole car'r, pillar and T
The midpoint of the 1100 area with the two pillars, i.e. approximately 55° from both pillars.
(see Figure 2), each target is at T
The amount of material from button 1 and T2 will be deposited to form the substrate.

However, when the substrate is aligned with the T2 pillar, only material from T2 will be deposited on the substrate.

Material from T1 or T3 is shielded by the shutter and also by the plate bias ring between the target and the substrate.

Since precipitation continues during the conversion from T1 to T2, no contaminants are present between the deposited layers.

Also, the integrity of the interface between the two deposited layers is ensured by the material from T1 and T2.

After reaching the T2 pillar, the shutter remains in place until the desired thickness of the T2 material layer is reached.

The anode button and shutter are then driven together onto the T3 column to deposit T3 material.

Even when converting from T2 to T3 in the 110° region, material is continuously deposited on the substrate, removing contamination between the second and third layers, as described above, and removing the contamination between these layers. It is possible to provide a nearly perfect interface between the two.

The apparatus of this invention was used to deposit a complete bond of molybdenum and gold on nickel foil.

The apparatus of this invention was used to deposit successive layers of titanium, molybdenum, and gold on a twisted aluminum oxide substrate.

The above layer is 500~xooo! When etched and inspected over a thickness of (Angstroms), no defects were found.

That is, the interface between each layer was perfect and free of contaminants.

It should be appreciated that this invention should not be limited in its use to only the materials mentioned above.

Any sputterable material can be used in this device.

Furthermore, two or more substrates can be placed on the same column at the same time.

The embodiments of the present invention are enumerated as follows by Omiya.

1. The device according to the claims [1-, wherein the plurality of elements are plate means adjacent to the cathode and spaced apart towards the anode side and connected at an anode potential to a potential device; A sputtering apparatus characterized in that the plasma from each target is directed towards the anode through a different set of apertures in the plate means.

2. The device as claimed in the claims further comprises a shutter device having a rotatable opening disposed adjacent to the anode so as to eliminate neutral material particles from any target to a predetermined anode area. and a position that exposes the predetermined anode region to at least one neutral material particle of the target. Sputtering equipment.

3. In the device according to the claims, the plurality of elements are spaced apart from each other in the direction of the anode between the plate means and from the point furthest away from the cathode. 1. A sputtering apparatus, which is a bias shielding means for an element having a hole, and a potential device applies different potentials to each of the bias shielding means.

4. In the device as claimed in the above claims, the elements of the bias shielding means closest to the anode have an anode potential, and the elements of the bias shielding means are arranged sequentially toward the cathode. A sputtering apparatus characterized in that the potential of a passing element is a potential that is sequentially decreased from an anode potential.

5. The claimed apparatus further comprises separate bias rings disposed in each plasma path extending from each target to control the ionization current of the plasma thereby sputtering each target. A multi-stage target sputtering apparatus characterized by comprising a device for controlling the potential of the rings in order to control the speed independently of each other.

[Brief explanation of the drawing]

Figure 1 is a vertical sectional view of a basic embodiment of this invention, Figures 2 and 3 are
The figure is a top view of the parts shown in FIG. 1, and FIG. 4 is a partial side view used to explain the features of the invention.
5 and 6 are top views of other parts shown in FIG. 1. In the figure, symbols: 10...airtight container, 12...vacuum system 14...gas storage chamber, 15...cathode, 1
6...Top plate, 18...Insulating material conduit, 20...
Anode, 22... Drive unit motor, 23...
Shaft, 25... Stationary plate, 26... Bracket,
27...Groove, 28...Cathode plate, 29...
...screw, 30...target, 32...board, 3
3...RF/DC circuit network, 35...Plate top plate,
36... Opening, 37... Plate, 38... Opening, 40... Plasma, 42... Bias shield, 45... Division circuit, 45a... Resistor, 50...・
・Bias ring, 52... Opening hole, 55... Bias power supply, 57... Shutter, 58... Shutter,
59...Open hole.

Claims (1)

[Scope of Claims] 1. A container filled with an inert gas at a predetermined gas pressure, one stationary cathode disposed within the container, and a stationary cathode disposed within the container along the axis of the container. a rotatable anode spaced apart from the cathode; a plurality of different target materials connected to and supported by the cathode; and a plurality of different target materials adjacent to and spaced apart from the cathode. a rotatable shutter having an aperture adjacent to said anode and spaced apart from said cathode; comprising a plurality of elements including a bias shield means provided at a position separated from the shutter means, and a bias ring means provided between the shutter means and the bias shield means, The shutter means each having a plurality of apertures so that along an axis parallel to the axis of the container, each of the target materials passes through a different set of the apertures onto the anode. ionizing the inert gas by applying a potential difference between the anode and the cathode to form a plasma containing gas ions and electrons; a power supply device for bombarding the target with the ions to separate neutral particles from the target and causing at least a portion of the separated neutral particles to travel toward the anode; voltage application means for controlling the ionization current and adjusting the voltage application of the element so as to pass through different sets of apertures of the element towards the anode; being spaced apart from the anode such that when a selected region of the anode is aligned with the first of the targets, only neutral particles of the first target reach the region; As the selected region of the anode rotates and moves from the first one of the targets to the next, the selected region is moved from one or both of the first and/or second neutral particles. A multi-stage target sputtering apparatus characterized in that the target sputtering apparatus is configured such that the targets reach the target continuously and without interruption.