JPH07180049A - Method for cleaning target surface - Google Patents

Abstract

PURPOSE:To eliminates defects in films and to lower a defective rate in a thin film forming stage by a sputtering method. CONSTITUTION:The magnitude and directions of the currents flowing in an inside coil 5, a middle coil 6 and an outside coil 7 are changed at specified periods, by which the magnitude of the plasma 17 generated on a target 3 is changed and the regions exclusive of target erosion are sputtered. The regions where the sputtered. particles deposit on the target 3 are, therefore, decreased and the generation of defects in the films is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to producing a defect-free film in a thin film forming process such as a sputter disk or a semiconductor.

[0002]

2. Description of the Related Art A conventional technique for preventing the occurrence of defects in a formed film is to move a part of a yoke as in JP-A-62-33765 to change the magnetic field on the target. The plasma was moved so that the sputtered particles emitted from the target were not allowed to adhere, remain, deposit, or scatter on the target again, so that no defect was generated in the film.

[0003]

However, in the above-mentioned conventional technique, a drive mechanism and a control unit for moving a part of the yoke are newly required, and the apparatus becomes complicated. In addition, since there is a drive part such as a shutter that protects the substrate from the scattered deposits in the airtight container, not only abrasion powder is generated and scattered from itself, but defects occur in the film, and the degree of vacuum is reduced and the vacuum is reduced. There was a problem of deterioration in quality. Therefore, it is necessary to regularly inspect the device and replace parts, which is an obstacle to production.

Therefore, an object of the present invention is to use a multi-electromagnet electrode in which coils are arranged concentrically, to eliminate the drive section and to simplify the entire apparatus, and to obtain the same effect.

[0005]

FIG. 1 shows the structure of a triple electromagnet as one means for achieving the above object.
Since the magnetic field can be changed when the number of layers is two or more, any number of layers can be used as long as it is two or more. The plasma 17 generated on the target 4 is moved to a position other than the target erosion at a constant cycle by changing the value and direction of the current flowing through the inner coil 5, the middle coil 6, and the outer coil 7 arranged on the back surface of the backing plate 4. It is what makes me.
This prevents the sputtered target particles from reattaching to a region that is not normally sputtered and prevents them from being deposited or scattered. Further, since the target particles can be constantly operated to prevent re-adhesion, a drive unit such as a shutter for protecting the substrate from contamination by deposits is unnecessary.

[0006]

According to the present invention, the particles adhering to the non-erosion area of the target can be prevented from accumulating, so that the accumulated particles scatter to cause defects in the film, resulting in deterioration of sliding resistance and bit error. Can be prevented.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a case where thin films are formed on both surfaces of a substrate by sputtering. The vacuum exhaust system is omitted.

A substrate 2 is arranged in the vacuum chamber 1.
There is a target 3 facing the substrate 2. Target 3
Is attached to the backing plate 4, and the inner coil 5, the middle coil 6, the outer coil 7, the center yoke 8, the middle yoke 9, and the outer yoke 10 are concentrically placed on the back side of the backing plate 4. A constant current power supply 11 for middle coil is connected to the middle coil 6. The middle coil constant current power supply 11 has a function of reversing its output. The inner coil 5 and the outer coil 7 are connected in series so that the mutual magnetic flux directions are opposite to each other, and are connected to the constant current power supply 12. The left and right targets 3 are connected to the sputtering power source 13. Further, the outputs of the constant current power supply 11 for the middle coil, the constant current power supply 12 and the sputtering power supply 13 can be controlled from the outside, and an external control device 14 is connected. The external control device 14 is capable of controlling the plasma generated on both sides of the substrate 2 at the same time, and the parameters of the external control device 14 are shown in Table 1.

[0009]

[Table 1]

The relationship between the parameters shown in Table 1 and the position of the plasma depends on the diameters of the coils and yokes, the current values flowing through the inner coil and the outer coil 7, and is generally expressed by the following equation.

[0011]

[Equation 1]

[0012]

[Equation 2]

[0013]

[Equation 3]

As an example, FIG. 2 shows the position of plasma on the non-magnetic target.

Next, the state of film formation in this embodiment will be described. In general, the size and position of the components forming the electrodes are determined so that the thickness of the film to be formed on the substrate 2 is uniform over the entire surface of the substrate 2. In this case, plasma 17 is generated in the middle circumference of the target 3, the inner circumference of the target 3 becomes a non-erosion portion, and particles flying from the opposing target pass through the hole of the substrate 2 and reach this non-erosion portion in the case of a magnetic disk. Reach and attach. This part is plasma 1
Since No. 7 does not occur, particles once attached remain. By further repeating the film formation, particles are deposited and eventually scattered, and some of them are attached to the substrate 2 and cause defects.

Next, the operation of cleaning the surface of the target 3 will be described. In order to move the plasma 17 to the inner circumference of the target, the direction of the current flowing through the middle coil 6 is reversed based on the equation 2, and the current value is gradually increased. The diameter of the plasma 17 becomes smaller as the current changes, and the target particles that have reattached to the non-eroded portion of the target are sputtered and cleaned. As an example, Table 2 shows the difference in the non-erosion region when the present invention is used and when it is not used.

[0017]

[Table 2]

The target 3 can be always kept clean by storing this series of operations in the external control device 14 in advance and performing them periodically. The operating time and frequency can be set during production and for each substrate as long as the film thickness, film thickness distribution and film quality of the product are not affected. FIG. 3 shows an example in which the present invention is used for each substrate.

The time from 13.9 seconds to 16 seconds after the start of the process is the time for cleaning the target surface according to the present invention. By lowering the sputtering power during this time than usual, the influence on the film thickness distribution in the substrate surface and the film quality is eliminated.

As a second embodiment, the present invention can be used even in the case where a single sputtering apparatus is used to form substrates of different diameters, which case will be described.

Generally, the diameter of the target 3 is determined by the diameter of the substrate 2 and the distance between the target 3 and the substrate 2. However, if the diameter of the substrate 2 is smaller than the predetermined one,
The plasma diameter is reduced to form a film. In this case, since the outer peripheral portion of the target 3 becomes a non-erosion portion, extra target particles adhere to this portion. Therefore, the direction of the current flowing through the middle coil 6 is set to be positive based on Equation 3, and the current value is gradually increased. Along with this change in current, the plasma moves toward the outer circumference of the target and the target particles adhering to the non-eroded portion are sputtered and cleaned.

In the first and second embodiments, the cleaning is achieved by changing only the magnitude and direction of the current flowing through the middle coil 6, but the current values of the inner coil 5 and the outer coil 7 are different. The thickness of the plasma 17 can be increased by reducing the value of .alpha., And thereby the non-erosion portion can be sputtered and cleaned. Further, as shown in FIG. 4, the inner coil 5 and the outer coil 7 may be controlled independently.

In the case where single-sided sputtering is performed as the third embodiment, the present invention can be applied to, for example, a thin film forming step in a semiconductor, which case will be described. In the case of only one side, as shown in FIG. 5, the configuration may be the one side configuration in the first and second embodiments. Although there is no opposing magnetic field, even in this case, the position of the plasma changes based on Equations 1, 2 and 3 to prevent reattachment of the target particles or to sputter the reattached sputtered particles to clean the target surface. Can be converted.

[0024]

According to the present invention, since the target surface can be cleaned, the defect rate can be reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is a diagram showing an example of changes in the position of plasma in a nonmagnetic target.

FIG. 3 is an example of usage frequency of the present invention.

FIG. 4 is a configuration diagram when an outer coil and an inner coil are separated to change a plasma ring.

FIG. 5 is an example of the configuration when the present invention is used in an apparatus for performing single-sided film formation.

[Explanation of symbols]

 1 ... Vacuum chamber, 2 ... Substrate, 3 ... Target, 4 ... Backing plate, 5 ... Inner coil, 6 ... Middle coil, 7 ... Outer coil, 8 ... Center yoke, 9 ... Middle yoke 10 ... Outer yoke, 11 ... Middle Coil constant current power supply, 12 ... Constant current power supply, 13 ... Sputtering power supply, 14 ... External control device 15 ... Inner coil constant current power supply, 16 ... Outer coil constant current power supply, 17 ... Plasma.

Front Page Continuation (72) Inventor Kazuhiro Ura 2880 Kozu, Odawara City, Kanagawa Stock Company Hitachi Storage Systems Division

Claims (1)

[Claims] 1. Sputtered particles redeposit on the target surface,
A device that cleans the target surface by controlling the current flowing through the electromagnet so that it does not remain and moving the plasma.