JPH02156082A - Sputtering device - Google Patents

Abstract

PURPOSE:To prevent the generation of an arc discharge on a grounded electrode by providing a magnetic field forming means between respective targets, and forming a high-frequency power source or a transmission line so that the voltages to be impressed on respective targets have a phase difference. CONSTITUTION:The high-frequency voltages having a phase difference from each other are impressed on plural targets T. A potential difference is produced between the targets by the phase difference. A glow discharge is generated between the targets by the potential difference and plasma is produced. A magnetic field is formed so that a line of magnetic force leaves one target T and enters the other target. A highly densified region P of plasma is formed in the vicinity of the surface of the target T by the magnetic field. A discharge current flows between the targets through the region P. Meanwhile, the discharge current between the target T and the grounded electrodes 10 and 21 is greatly reduced. Accordingly, the current flowing through the grounded electrodes 10 and 21 is reduced, and the arc discharge from the grounded electrodes 10 and 21 is diminished.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a high frequency sputtering apparatus.

(Prior Art) In a high-frequency sputtering apparatus, generally, a vacuum chamber and a substrate supported therein, which is an object to be processed, constitute one electrode, and a target supported within the vacuum chamber constitutes the other electrode. The former is brought to zero potential, and the latter is applied with a high-voltage radio-frequency voltage (RF lightning voltage. The former is called the ground electrode, and the latter is called the RF main electrode. The radio-frequency voltage is applied to the transmission line including the matching circuit and blocking capacitor. RF is applied to the target via the main electrode.Then,
Glow discharge occurs between the earth electrode and the RF electrode, turning the atmosphere between the two electrodes into plasma.

According to the switching of the polarity of the high frequency voltage, the earth electrode and
F main electrode alternately serves as a cathode and an anode. A discharge current flows from the anode to the cathode in the plasma atmosphere. The magnitude of the discharge current is proportional to the amount of light irradiated from the plasma to the cathode and the applied voltage.

Since the ground electrode has a larger area than the RF main electrode and irradiates a larger amount of light, a larger discharge current flows when the ground electrode is a cathode when the applied voltage is the same. On the other hand, due to the direct current blocking effect of the blocking capacitor, the discharge current when the earth electrode is the cathode is the same as the discharge current when the RF main electrode is the cathode. Therefore, the peak value of the high frequency voltage is biased towards the negative side, being high when the RF main electrode is the cathode and low when the earth electrode is the cathode. Therefore,
Discharge power consumption is large when the RF main electrode is the cathode, and conversely, power consumption is small when the earth electrode is the cathode.

During such glow discharge, arc discharge may occur for some reason. Arc discharge is thermionic emission from the cathode, which is visually observed as a spark emanating from the cathode. In order to minimize the occurrence of this arc discharge, arc cut circuits are conventionally known. The arc cut circuit detects the occurrence of arc discharge from a change in power consumption during glow discharge, and momentarily cuts off the supply of high frequency voltage. As mentioned above, the power consumption of glow discharge when the RF [pole is a cathode] is relatively large, so the occurrence of arc discharge at this time causes a noticeable change in power consumption. Therefore, the arc discharge generated by the RF main electrode is easily detected and cut by the arc cut circuit. However, the occurrence of arc discharge when the ground electrode is a cathode does not cause a significant change in power consumption. Therefore, arc discharge generated at the ground electrode is difficult to be detected by the arc cut circuit and difficult to cut.

(Problems to be Solved by the Invention) As described above, it is difficult to cut arc discharge generated at the ground electrode using an arc cut circuit. If arc discharge occurs in the substrate of the ground electrode, the substrate will be destroyed at the location of the arc discharge. Additionally, if an arc discharge occurs in a part of the ground electrode located near the board, such as a jig for fixing the board, ejected material from the arc discharge location will adhere to the coating on the board surface and ruin it. I end up making it.

Further, even when sputtering is performed normally without arc discharge, conventional high-frequency sputtering has several problems as described below. As mentioned above, the glow discharge current is R
F flows in both directions between the main electrode and the ground electrode. When the Group 7JS current flows toward the ground electrode, sputter evaporation of the target does not occur, so the power consumed at this time is wasted power.

Further, the discharge current directed toward the earth electrode causes sputter evaporation of the earth electrode, and the evaporated earth electrode material contaminates the film on the surface of the substrate.

Further, when a current flows through the ground electrode, especially the substrate, heat is generated in the substrate, which makes it difficult to control the temperature of the substrate.

Therefore, a first object of the present invention is to effectively prevent arc discharge occurring at the earth electrode.

A second purpose is to improve the sputter rate by minimizing wasted power that does not contribute to sputter evaporation of the target.

The third purpose is to eliminate sputter evaporation of the ground electrode as much as possible to prevent contamination of the substrate surface film.

Furthermore, the fourth purpose is to prevent heat generation in the substrate, making it easier to control the temperature of the substrate, and to make it possible to apply high-frequency sputtering to substrates made of materials such as plastic, which are not suitable for high-temperature processing. It is to make it.

[Structure of the invention]

(Means for Solving the Problems) The present invention applies a high frequency voltage from a high frequency power source to a target placed in a vacuum container via a transmission path including a matching box, thereby generating a target inside the vacuum container. In a device that performs sputter deposition processing on a workpiece, a plurality of targets are arranged in the vacuum container, and a magnetic field having lines of magnetic force that exits from one target and enters the other target is provided between each target and the other targets. The present invention provides a sputtering apparatus in which the high frequency power source or the transmission line is configured such that the voltages applied to the targets have a phase difference with each other.

(Function) According to the above configuration, high frequency voltages having mutually different phases are applied to each of the plurality of targets. The difference in phase creates a potential difference between the targets. This potential difference causes a glow discharge between the targets to form plasma. A magnetic field is created such that magnetic field lines exit one target and enter the other target. Due to the action of this magnetic field, a region of highly concentrated plasma is formed near the surface of the target. This region is formed from the surface of one target to the surface of the other target. A discharge current flows well between the targets through such a plasma concentration region. The discharge current flows alternately between the targets, and sputter evaporation always occurs in one of the targets. On the other hand, the discharge current between the target and the ground electrode becomes very small. Therefore, the current flowing through the ground electrode decreases. the result,
Arc discharge from the ground electrode is reduced, spatter evaporation from the ground electrode is suppressed, heat generation from the substrate is reduced, and wasted power consumption is reduced.

(Example) Examples will be explained below.

FIG. 1 shows the configuration of an embodiment of a sputtering apparatus according to the present invention.

In the figure, 10 is a vacuum container, and this container 10 is provided with a gas inlet 11 and an exhaust port 12.
A predetermined gas is contained inside the container 10 in a nearly vacuum state. This container 10 is provided with a rotary holder 21 that holds the object to be processed, and this rotary holder 21 is driven by a motor 22.

Four sputter gun targets T1 to T4 are arranged in parallel so as to face the circumferential surface of the rotary holder 21. These four targets T1 to T4 are divided into bare T1 and T2 and bare T3 and T4. The bare targets are placed close to each other so that glow discharge can occur favorably between them. A necessary distance is provided between the targets of different bears so that the plasma formed by the discharge of each bear does not interfere with each other.

On the back side of the target bears Tl and T2, an electromagnet M1 is arranged, with an N pole located for each target bear and an S pole located for each target bear. This magnet M1 forms a magnetic field having lines of magnetic force Φ1 that exit from the surface of the target T1 and enter the surface of the target T2. On the back side of the other target bear T3゜T4, there is an electromagnet M with an N pole located on each target bear and a S pole located on the side of target T3.
2 is placed. This magnet M2 is connected to the target T3
The magnetic field line Φ2 that comes out from the surface of and enters the surface of target T4
form a magnetic field with .

High frequency voltage generator 0801.0S for each target bear
C2 is provided. High frequency voltage generator 0SCI, 0
5C2 independently generates a high frequency voltage and outputs it to two transmission lines provided for each target bear. Viewed from the voltage generators 03CI and 03C2, each transmission line is connected to voltage amplifiers FAI, PA2, and matching box M.
H.I.

It has MB2 and high frequency transformers Trl and Tr2 as elements. Drive cables CC11-CCl4 have a characteristic impedance equal to the input impedance of voltage amplifiers PAI-PA4. The voltage amplifier PA amplifies the high frequency voltage from the voltage generator O8C to a desired level of high voltage, and since the gain can be adjusted, the voltage level applied to each sputter gun can be made different or the same. . The matching box MB has a matching circuit for matching impedance so that the high frequency voltage sent through the transmission line is applied to the sputtering gun with maximum efficiency, and the matching circuit includes a blocking capacitor that blocks direct current. . Trans Tri
, Tr2 distributes each high frequency voltage output from the high frequency voltage generators 09CI and 03C2 to each bare target. Since the transformers Trl and Tr2 are configured to function as a balun, a balanced two-phase high frequency voltage having a phase difference of 180 degrees is applied to the bare target. Further, the ground electrodes consisting of the vacuum container 10, the substrate holder 21, the shield of the matching box, etc. are brought to zero potential.

Next, the effect will be explained.

The high frequency voltage output from the high frequency voltage generator 0SCI is amplified by the high frequency amplifier PAL, and then 1
The high frequency voltages are converted into two high frequency voltages with a phase difference of 80 degrees, and these high frequency voltages are respectively applied to the targets T1. Applied to T2. The potential difference between the targets TI and T1 caused by the phase difference between these two high frequency voltages causes the targets Tl and T2 to
A glow discharge occurs between the two, forming plasma. Similarly, glow discharge occurs between targets 73 and 74, forming plasma.

Target TI due to the action of magnetic field lines Φ1.

A region P1 where plasma is concentrated at high density is formed on the surface of T2. Similarly, the magnetic field line Φ2 causes the target T
3. The plasma is concentrated on the surface of T4 to form a region P2. As shown in the figure, these plasma concentration regions PL,
P2 is formed from the surface of one target to the surface of the other target of each target bear. Therefore, a discharge current flows satisfactorily between the targets TI and T2 via the plasma concentration region P1, and between the targets 73 and 74 via the plasma concentration region P2. Due to this discharge, sputter evaporation is performed alternately on the surfaces of targets TI and T2, and
3. Sputter evaporation is also performed alternately on each surface of T4.

The magnetic lines of force Φ1 and Φ2 are in repulsive directions, and the target pair T3.74 of tartbear TI and T2 is
By having a sufficient distance between them, the plasma concentration area P
There is no mutual interference between the plasma concentration region P1 and the plasma concentration region P2. Therefore, sputter evaporation for each target bear is performed independently of each other.

On the other hand, almost no discharge current flows between the targets T1 to T4 and the earth electrode 10°21. Therefore, almost no current flows through the earth electrode, and arc discharge from the earth electrode is effectively prevented. Furthermore, since almost no current flows through the substrate, the heat generation of the substrate is reduced, making it easier to control the temperature of the substrate. The low heat generation of the substrate also gives rise to the possibility of applying high frequency sputtering to materials unsuitable for high temperature processing. Furthermore, since almost no sputter evaporation of the ground electrode occurs, there is little contamination of the substrate coating. In addition, in this embodiment, since discharge is performed independently for each bear of the target and there is no interference between bears, the high frequency voltage generator 0SCI,
05C2 has the advantage that there is no practical problem even if the frequencies are slightly different or the phases are different.

FIG. 2 shows an embodiment in which the present invention is applied to a magnetron type sputtering apparatus. The figure shows only the portion around the target of this embodiment. The same configuration as in FIG. 1 can be adopted for other parts not shown.

Four targets T5 to T8 are arranged in parallel, and they form a target pair T5. T6 and target pair T7
．． It is grouped into T8.

The same bare targets are placed close to each other to improve glow discharge between them, and different targets are placed apart from each other to avoid mutual interference of plasma.

A balanced two-phase high frequency voltage is applied to two targets for each target bear. Vacuum vessel 10 is brought to zero potential.

Electromagnets M5 to M are provided on the back side of each target T5 to T8.
8 is placed. Each of the magnets T5 to T8 has a shape in which one magnetic pole is surrounded by the other magnetic pole.

They form a magnetic field on the surface of each target T5-T8 with magnetic field lines Φ5-Φ8 coming out of the center (or periphery) and entering the periphery (or center) of the target.

Magnets M5 and M8 have an S pole at the center and an N pole around the periphery. Magnets M6 and Ml have a north pole at the center and a south pole around the periphery. In other words, the magnets on the back surface of the bare target have opposite magnetic poles. Therefore, between the bare targets, a line of magnetic force Φ9 exits from the surface of one target and enters the surface of the other target.
．． Magnetic fields each having Φ10 are formed.

Next, the action will be explained.

By applying a reverse phase high frequency voltage to the bare targets, a glow discharge is generated between the bare targets and plasma is formed near the surfaces of each of the targets T5 to T8. The plasma is confined by magnetic lines of force Φ5 to Φ8, forming annular plasma concentration regions P5 to P8 on each target surface. Also 1. Line of magnetic force Φ9 between paired targets. Φ10
Due to the plasma confined in the bare target, a plasma concentration region P9. P10 is formed. Plasma concentration region P9 between the bare targets. Via the PIO, the plasma concentration regions on the surface of the bare target are coupled together. In this way, a discharge current flows satisfactorily between the bare targets via the plasma concentration region coupled between the bare targets. On the other hand, the discharge current flowing between the targets T5 to T8 and the ground electrode decreases.

The preferred embodiments have been described above. In these embodiments, two targets were driven with two-phase high-frequency voltages, but the scope of the present invention also includes driving a larger number of targets with multi-phase high-frequency voltages. For example, if you set 3 targets to 12
A modification is also possible in which it is driven by balanced three-phase high frequency voltages whose phases differ by 0 degrees. This modification can be realized by using a transmission line in which a high frequency voltage from a single high frequency power source is converted into a balanced three-phase high frequency voltage by a high frequency transformer.

〔Effect of the invention〕

As explained above, according to the present invention, the configuration is such that the high-frequency current mainly flows between the targets and almost no high-frequency current flows through the ground electrode. This reduces substrate contamination, substrate heat generation, and wasted power consumption, improves product quality, increases sputtering rate, facilitates substrate temperature control, and makes it possible to apply high-frequency sputtering to materials unsuitable for high-temperature processing. The effect of generation can be obtained.

FIG. 2 is a circuit diagram showing an example.

10... Vacuum container, 21... Substrate holder, T1-T
8...Target, Ml, M2. M5-M8...Electromagnet, Φ1. Φ2. Φ5~Φ10...Magnetic field lines, PI,
P2. P5~PIO...Plasma concentration area, 0SC1
,0SC2...High frequency voltage generator, CCl1. CCl
2...Drive cable, PAI.

PA2...Voltage amplifier, C, C21, CC22...
Output cable, MBI, MB2...Matching box, Tri, Tr2...High frequency transformer.

Claims (1)

[Claims] 1. Applying a high-frequency voltage from a high-frequency power source to a target placed in a vacuum container via a transmission path including a matching box, and sputtering deposition onto a workpiece in the vacuum container. In the processing apparatus, a plurality of targets are arranged in the vacuum vessel, and means for forming a magnetic field between each target and the other targets, the magnetic field having lines of magnetic force exiting from one target and entering the other target. A sputtering apparatus characterized in that the high frequency power source or the transmission path is configured such that the voltages applied to the targets have a phase difference with each other. 2. The apparatus according to claim 1, wherein the plurality of targets are divided into groups of a predetermined number of targets, and a magnetic field having lines of magnetic force exiting from one target and entering the other target is provided between each target belonging to the same group. The magnetic field forming means is provided so as to form a
A sputtering apparatus characterized in that the high frequency power supply or the transmission path is configured such that voltages applied to targets belonging to the same group have a phase difference with each other. 3. The apparatus according to claim 1, wherein the magnetic field forming means is a magnet having a north pole placed on the one target side and a south pole placed on the other target side. sputtering equipment. 4. The apparatus according to claim 1, which is a magnetron type sputtering apparatus in which a magnet is arranged corresponding to each of the targets, wherein the magnet corresponding to the one target and the magnet corresponding to the other target are A sputtering apparatus characterized by having a mutually opposite magnetic pole arrangement structure.