Etching a substrate: processes – Masking of a substrate using material resistant to an etchant – Adhesively bonding resist to substrate
Reexamination Certificate
2000-05-19
2002-10-29
Crispino, Richard (Department: 1734)
Etching a substrate: processes
Masking of a substrate using material resistant to an etchant
Adhesively bonding resist to substrate
C156S084000, C156S085000, C156S247000, C156S275500, C156S345420, C216S042000
Reexamination Certificate
active
06471882
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a process for producing a head slider, and more particularly to a process for producing a head slider by simply and surely removing a resist material present on a floating surface which is formed on a slider substrate.
BACKGROUND OF THE INVENTION
A floating head slider used in HDD (hard disc drive) has been required to maintain a low, constant floating height as the density of HDD has increased. Therefore, complicated uneven portions are formed on its floating surface by etching by using a resist material as a mask. As a difference in level in the uneven portions has increased in recent years, a dry film resist having a thickness of several tens &mgr;m is being used as a resist material.
In order to form a shape of a predetermined pattern on a floating surface, a dry film resist is first stuck onto a slider substrate and shaped into the predetermined pattern by the conventional photolithography. Next, the substrate in the area where no resist material is present is removed by etching by applying Ar ions or the like using the resist pattern as a mask, thereby forming the predetermined pattern on the floating surface of the slider substrate.
A resist mask which has already become unnecessary is present on the thus formed floating surface and it is removed prior to the next step. Heretofore, swelling treatment using an organic solvent such as acetone has been adopted as a method for removing such a resist mask.
However, the swelling treatment using the organic solvent has a problem that the resist material which has been peeled off from the substrate drifts in the solvent and redeposits onto the substrate. There is also another problem of the risk of fire, deterioration of a working environment, or the like.
SUMMARY OF THE INVENTION
The object of the present invention is, in the light of these circumstances, to provide a process for producing a head slider, the process being able to simply and surely remove, during the production of the head slider by photolithography, a resist material present on a floating surface which has already become unnecessary.
The present inventors have intensively studied in order to attain the above object. As a result, they have found that in the formation of a floating surface on a slider substrate by photolithography, sticking an adhesive sheet onto the upper surface of a resist material present on the floating surface, followed by peeling off the adhesive sheet together with the resist material from the floating surface allows the resist material to be simply and surely removed from the floating surface and the aforementioned problems such as the deterioration of the environment can be solved at one stroke, and have accomplished the present invention.
That is, the present invention includes:
1. A process for producing a head slider, the process comprising:
a step of forming, on a slider substrate by photolithography, a patterned floating surface having a resist material on its upper surface;
a step of sticking an adhesive sheet on the upper surface of the resist material present on the floating surface; and
a step of peeling off the adhesive sheet together with the resist material from the floating surface;
2. The process for producing a head slider according to the item 1, wherein the slider substrate and the resist material are heated to make a condition where a modulus of elasticity of the resist material is lowered at least during the step of peeling off the adhesive sheet;
3. The process for producing a head slider according to the item 2, wherein the step of sticking the adhesive sheet is conducted under a condition where the slider substrate and the resist material have been heated in advance and the step of peeling off the adhesive sheet is conducted while the heated condition is maintained;
4. The process for producing a head slider according to the item 2, wherein the slider substrate and the resist material are heated after the step of sticking the adhesive sheet and the step of peeling off the adhesive sheet is conducted while the heated condition is maintained;
5. The process for producing a head slider according to items 2, 3 or 4, wherein a temperature under the heated condition is in the range of from 40 to 150° C.;
6. The process for producing a head slider according to the item 1, wherein the adhesive used for the adhesive sheet is a curable pressure-sensitive adhesive; and
7. The process for producing a head slider according to the item 6, wherein the curable pressure-sensitive adhesive is an ultraviolet-curable adhesive and an ultraviolet irradiation step is conducted after the step of sticking the adhesive sheet and before the step of peeling off the adhesive sheet.
DETAILED DESCRIPTION OF THE INVENTION
In the process for producing a head slider according to the present invention, a typical example of the step of forming, on a slider substrate by photolithography, a patterned floating surface having a resist material on its upper surface is a method in which, as previously mentioned, a dry film resist material is stuck onto the slider substrate, a predetermined resist pattern is formed by the conventional photolithography, and the substrate in the area where no resist material is present is removed by etching by applying Ar ions or the like using the resist pattern as a mask.
The resist material on the floating surface, as mentioned above, was shaped into a predetermined pattern on the substrate and remains on the substrate as a resist mask after etching.
The thickness of the remaining resist material is generally set to be approximately from 1 to 20 &mgr;m, for example, in the case of the irradiation with Ar ions, but is not limited to this.
In the process for producing a head slider according to the present invention, an adhesive sheet is stuck onto the upper surface of such a resist material present on such a floating surface of the slider substrate. The adhesive sheet used here is an item prepared by providing a pressure-sensitive adhesive layer generally having a thickness of from 20 to 150 &mgr;m on a film substrate and forming them into a sheet or a tape. The film substrate is exemplified by films of plastic such as polyester, polycarbonate, polyethylene, polypropylene, polyamide and acetylcellulose. Preferred thickness of the film substrate is generally from 10 to 1000 &mgr;m.
The pressure-sensitive adhesive layer may be one using conventional non-curable pressure-sensitive adhesives of the acrylic type, the rubber type and the like, preferred is one using curable pressure-sensitive adhesive in order to remove the resist material more cleanly and to prevent adhesive deposit and the like.
Such a curable pressure-sensitive adhesive is not particularly limited in its material and the like as long as it has the property of being cured by an activation energy source so that its molecular structure is transformed into three-dimensional cross linkage. Preferred examples thereof those of a polymerization-curable type comprising a pressure-sensitive adhesive polymer, a curable compound having at least one unsaturated double bond in the molecule and a polymerization catalyst.
Examples of such a pressure-sensitive adhesive polymer include acrylic polymers containing, as a main monomer, (meth)acrylic acid and/or (meth)acrylic ester selected from acrylic acid, acrylic ester, methacrylic acid and methacrylic ester. In the synthesis of the acrylic polymers, it is also possible to make the acrylic polymer itself participate in the polymerizing and curing reaction by an activation energy by means of introducing an unsaturated double bond into the molecule of the acrylic polymer, for example, by using, as a copolymerizing monomer, a compound having two or more unsaturated double bonds in the molecule or by making a chemical bond, by a reaction between functional groups, a compound having an unsaturated double bond in the molecule and the acrylic polymer synthesized.
Preferred examples of the curable compound having at least one unsaturated double bond in the molecule include those
Ioka Haruo
Namikawa Makoto
Crispino Richard
Hawkins Cheryl N.
Knobbe Martens Olson & Bear LLP
Nitto Denko Corporation
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