Patent Application
20060060559
The present invention is related to a method and system of forming a thin film layer, a protective layer, and a friction-free layer, and more particularly to a method and system for forming a protective layer over a magnetic device thereon.
At present, magnetic devices, such as magnetic read/write heads, magnetic disks, are being widely used in data storage industry. Referring to
In addition, surface recording density (areal density) of hard disk drivers (HDDs) has been continuously increased since last few years. The increase of areal density demands for higher signal intensity and lower flying height. Accordingly, it is also required for a thinner overcoat, for example, an ultra thin overcoat (i.e. equal or less than 3 nm) will be required for the magnetic read/write head to achieve a higher areal density (i.e. greater than 120 Gb/inch2) in the near future. Correspondingly, lower flying height with a higher rotating speed requires excellent properties of the overcoat, such as hardness, conductivity and tribology properties.
To form an overcoat for satisfying the above-mentioned requirements, a lot of forming methods have been used. Currently, the most popular methods for forming overcoats on magnetic heads are electron cyclotron resonance chemical vapor deposition (ECR CVD) and direct or secondary ion beam deposition (IBD). However, these methods have arrived at a stage where their limitation to scale down a thickness of overcoat is clearly visible, for the following reasons. One reason is that some important elements of magnetic device, such as the read/write element material, yoke and shields, become more and more sensitive to corrosion, which are aimed to have a gradually increased magnetic flux density. Another reason is that these methods use hydrocarbon as precursor, so the formed overcoat has some extent of hydrogen content (5%˜50%, atm %) and many defects (such as vacancies, or even pin hole) are formed thereon when the overcoat becomes thinner. These defects show up in the course of manufacturing, application or reliability tests for magnetic devices.
Another problem associated with these methods is that the high deposition rate results in a very short time to form an ultra thin overcoat (i.e. equal or less than 3 nm), and this makes the overcoats formed on the magnetic devices in one batch non-uniform. Additionally, the current coating machines usually utilize a shutter for blocking ion beam. The shutter normally takes about two seconds to open or close. During the course of opening or closing the shutter, there are still some ion beams bombarding the magnetic devices, which also contributes to the non-uniformity of the overcoats formed on one batch magnetic devices.
Hence it is desired to provide a method and system for forming thin film over magnetic devices which can overcome the foregoing drawbacks of the prior art.
A main feature of the present invention is to provide a method and system of forming thin film to achieve well-uniformity.
To achieve the above-mentioned feature, a thin film forming method of the present invention, comprises the steps of: (1) holding at least one object in a chamber; (2) depositing a forming material on the object; and (3) etching the forming material while depositing is conducted. In the present invention, the depositing and etching are controlled to be conducted simultaneously. The depositing is that placing a target for forming a film and irradiating ion beam to bombard the target. The etching comprises the steps of: (1) making an atmosphere of inert or reactive gas at a predetermined pressure in a chamber; (2) ionizing the atmosphere to generate etching beam to bombard the object.
A system of the present invention comprises a chamber to form thin film, a positioning tool to hold an object in the chamber, a disposing conductor to conduct deposition on the object, an etching conductor to conduct etching the object; and a controller to control irradiation timing of the both conductors. In the present invention, the controller is a shutter which is placed in front of the object to open when both of irradiations are stable.
As an embodiment of the present invention, a thin film forming method comprises the steps of: (1) holding at least one object in a chamber; (2) the chamber is pumped to a predetermined pressure and then an inert or reactive gas is introduced into an etching source; (3) the inert or reactive gas is ionized and extracted by a grid of the etching source to generate an etching beam; (4) a first deposition source is turned on to generate a first deposition beam; (5) the deposition and etching beams are blocked by a substrate shutter mounted in front of the object(s); (6) the substrate shutter is opened when the deposition and etching beams are both stable, and the deposition and etching beams are bombarding the object(s) simultaneously to form a first film thereon. In the present invention, a second film can also be formed on the first film by a second deposition source bombarding the object.
In the present invention, the first deposition source can be ion beam deposition (IBD) source, ion beam sputter deposition (IBSD) source, ion cluster beam (ICB) deposition source, or ion beam assisted deposition (IBAD) source.
By depositing a forming material on an object while etching the forming material, the method and system not only improves the adhesion and coverage properties of the film formed on the object, but also decrease the deposition rate significantly and accordingly extend the deposition time, then the uniformity of the protective film formed on one-batch objects can be improved significantly. A lower deposition rate also minimize the influence of opening and closing the shutter on the uniformity of the protective films. In addition, the method also overcome the current thickness limitation (i.e. equal or more than 3 nm) of the protective film with superior reliability of the conventional film forming method.
For the purpose of making the invention easier to understand, one particular embodiment thereof will now be described with reference to the appended drawings in which:
A thin film forming method of the present invention comprises the steps of: (1) holding at least one object in a chamber; (2) depositing a film-forming material on the object; and (3) etching the film-forming material while depositing is conducted. In the present invention, the depositing and etching are conducted simultaneously. The depositing step comprises placing a target for forming a film and irradiating ion beam to bombard the target. The etching step comprises the steps of: (1) providing an atmosphere of inert or reactive gas at a predetermined pressure in a chamber; and (2) ionizing the atmosphere to generate etching beam to bombard the object.
Referring now to the drawings in detail,
In the present invention, a second film can be formed on the first film by a second deposition source bombarding the object(s). The second deposition source is an ion beam source using a hydrocarbon as precursor with the aid of another ion beam source, or an microwave ion source using hydrocarbon as precursor with the aid of another ion beam source, and accordingly the second film is a diamond like carbon film. In step (103), the first deposition beam is created by using an ion beam source to bombard a silicon (or other material, such as graphite) target, and the first film is a silicon (or other material, such as carbon) film. In step (101), the etching source can be radio frequency inductive plasma source, or a Kaufman ion source, and the grid can be two-platter structure or three-platter structure, preferably three-platter structure, with concave, convex or flat surface. A grid with three-platter structure comprises a beam grid, a suppressor grid and a ground grid.
In step (101), the inert or reactive gas is introduced into the etching source by a mass flow controller (MFC), and the chamber is generally pumped to a pressure less than 1×106 Torr, before the inert or reactive gas is introduced. After the inert or reactive gas is introduced, the etching source is ignited and after a while the plasma is stabilized. Then the first deposition source starts accordingly. In the present invention, each source has a shutter mounted in front thereof, and when the etching source and the first deposition source both attain a stable state of plasma, the shutters for both the sources are opened to etch and coat the objects simultaneously.
In the present invention, both the etching source and the deposition sources are adjusted to an optimized power. The ion energy of the etching source is normally ranged from 60 ev to 200 ev, to avoid any damage to the elements of the object (such as the MR element 35 when the object is a magnetic head, see
The following paragraphs illustrates an embodiment of the present invention and describes the present invention in more detail.
Referring to
The coating process in the chamber 9 can be carried as follows:
First, the etching source 1 is turned on to generate argon ion beam under the following condition: the flow rate of argon gas is 15 SCCM, the RF ignite power is 350 watts (W), the beam voltage is 120 volts and the beam current is 100 milliamperes, the suppressor voltage is 200 volts, the incidence angle of the argon ion beam to the objects 4 is 60° C.
After 30 seconds, the shutter 6 and the substrate shutter 5 are opened when the ion beam is stable. Then the objects 4 on the pallet 11 are etched for 30˜60 seconds by the argon ion beam until the surfaces of the objects 4 are clean. After that time, the substrate shutter 5 is closed, and the etching source 1 is kept on without any change of the above-mentioned condition.
Here silicon film is selected as the first film and the secondary ion beam deposition system 2 used for amorphous silicon deposition. The secondary ion beam deposition system 2 comprises an ion beam source 22 and a silicon target 21. The working condition of the ion beam source 22 used for bombing deposition target (silicon target) is set as follows: the flow rate of argon gas is 10 SCCM, the RF ignite power is 400 watts, the beam voltage is 500 volts, the beam current is 300 milliamperes, the suppressor voltage is 300 volts, the incidence angle of argon ion beam from the ion beam source 22 to the silicon target 21 is 35° C.
After 30 seconds, the shutter 3 and the substrate shutter 5 are opened when the ion beam is stable. Simultaneously, the shutter 6 is also opened and then the argon ion beam from the etching source 1 in step 1 is bombarding the surfaces of the objects 4 to densify the silicon film. The coating process is continued for about 30 seconds to 50 seconds until the silicon film reaches a thickness of about 1 nm. After that time the shutters 6, 3 and the substrate shutter 5 are closed and the secondary ion beam deposition system and the etching source 1 are turned off.
In this step, for example, ethene gas is used to form a second film, such as a diamond like carbon film (DLC film). The DLC film coating uses the same source as the etching source 1 in step 1 and the conditions in step 1 remain unchanged, except that the gas line is changed from argon to ethene with a flow rate of 80 SCCM. After the modified etching source is turned on for 30 seconds, the shutter 6 and the substrate shutter 5 are opened when the ion beam is stable. Then, the ionized ethene segment is deposited on the silicon film of the objects 4 to form the DLC film. After that, the shutter 6 and the substrate shutter 5 are closed and the source is turned off. Then, the coated objects are formed. When the object 4 is a magnetic head or magnetic disk, a protective film 36 or 40 formed thereon as shown in
In all of the above-mentioned steps, a neutralizer may be used to avoid accumulating charges on the objects 4. In addition, in the present invention, the pallet 11 is rotating at a speed of 15 rpm.
Referring to
In the present invention, the argon gas can be replaced by other inert gases or reactive gases, the first deposition source 2 also can be directly an ion beam deposition (IBD) source, ion beam sputter deposition (IBSD) source, ion cluster beam (ICB) deposition source, or ion beam assisted deposition (IBAD) source. Because the above-mentioned deposition sources are well known to persons skilled in the art, a detailed description of such deposition sources is omitted herefrom.
It is understood that the invention may be embodied in other forms without departing from the spirit thereof. Thus, the present example and embodiment are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein.
