In recent years, a shift from the GMR (Giant Magnetic Resistance) technology to the TMR (Tunnel Magnetic Resistance) technology has been made to cope with capacity increase of hard disc drives, and density increase in the surface recording density has been promoted rapidly.
Along with this, fine processing is needed to manufacture a magnetic head used in the hard disc drive, and a fine plasma etching technology of the magnetic head is demanded. In manufacturing apparatuses of magnetic heads, therefore, adaptation to a plasma etching apparatus from ion milling apparatuses is being promoted.
The manufacturing method of the magnetic heads is nearly the same as the manufacturing method of the semiconductor devices; while a photoresist patterned by lithography is used as a mask, fine processing using plasma etching is conducted on non-volatile materials, such as Al2O3, NiFe, and Ru, together with materials frequently applied to semiconductor devices, such as SiO2, Ta and Cr, formed on a substrate.
Incidentally, in fine processing using plasma etching in recent years, a photoresist patterned by lithography is reduced by plasma etching before a material to be etched is etched so that dimensions of wirings of the material to be etched are reduced by conducting plasma etching on the material to be etched with a mask pattern of the reduced photoresist.
For example, as a method (trimming) for reducing dimensions, a method is disclosed in Patent Literature 1, with which a photoresist patterned by lithography is reduced by isotropic or partially isotropic etching to form a patterned photoresist of reduced dimensions having a buried antireflective coating that also functions as an etch stop or a dummy layer so that the pattern of reduced dimensions provides an etch mask for subsequent anisotropic etching of underlying material such as polysilicon, metal, an insulator, or a ferroelectric substance.
In addition, as a method for reducing processing dimensions of a material to be etched from patterned dimensions, disclosed in Patent Literature 2 is a plasma etching method of etching a silicon carbide film using plasma with a laminated film as a mask, the laminated film including a previously patterned photoresist and a film selected from a Cr film, a Mn film, a Fe film, a Co film, a Ni film, a Y film, a Zr film, a Nb film, a Mo film, a Ru film, a Hf film, an Ir film, a Pt film, and an Au film or a film of an oxide containing an element selected from Cr, Mn, Fe, Co, Ni, Y, Zr, Nb, Mo, Ru, Hf, Ir, Pt, and Au, the method including the steps of: forming a mask for etching the film using a mixed gas of a chlorine gas and an oxygen gas and using the photoresist as a mask; and reducing dimensions of the film obtained in the above mask forming step using a mixed gas of a chlorine gas, an oxygen gas, and a rare gas after the above mask forming step.
As a dry etching method capable of conducting fast etching on a magnetic film having a thickness in the range of 200 to 500 nm and conducting favorable fine processing, for example, disclosed in Patent Literature 3 is a plasma processing method of dry etching a magnetic film having a thickness in the range of 200 to 500 nm, wherein a sample is subjected to dry etching on which a laminated film including a resist film, a non-organic film underlying the resist film, a Cr film underlying the non-organic film, and an Al2O3 film underlying the Cr film is formed on the magnetic film.
In addition, as an etching method of a Ta film, disclosed in Patent Literature 4, for example, is a method of etching a Ta film, which is a film to be etched and a non-volatile material, with high precision using a photoresist film as a mask pattern and using a mixed gas of Cl2 and O2.
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