JP2005353229A - Method for manufacturing thin film magnetic head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin film magnetic head, with which patterning accuracy, a sputtering film deposition distribution and/or an etching distribution can be improved, a wafer suction defect in a vacuum chuck or electrostatic chuck can be prevented, and a yield can be improved. <P>SOLUTION: Rear face polishing for cleaning the rear face of the wafer is performed at least once in the middle of a wafer process. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a thin film magnetic head from a wafer for a thin film magnetic head.

  Although it is a technical field different from the manufacturing technology of thin film magnetic heads, two silicon wafers are bonded together with a dielectric layer interposed, and one silicon wafer is thinned to a prescribed thickness to form a semiconductor single crystal film In this case, there is a technique for preventing the peripheral edge from becoming high due to the polycrystalline silicon adhering to the back surface of the silicon wafer and preventing uniform grinding (for example, Patent Document 1).

  In the known technique disclosed in Patent Document 1, an oxide film is deposited in advance on the back surface of a silicon wafer, and a part of the oxide film is removed prior to polishing or grinding, so that the oxide film wraps around and adheres to the back surface. The removed polycrystalline silicon is removed to flatten the back surface.

  As another known technique for processing the back surface of a semiconductor wafer, the back surface of the semiconductor wafer is mirror-finished so that the back surface is not damaged, and therefore generation of fine particles due to cutting is prevented (Patent Document 2). When manufacturing a semiconductor device, there is a method of reducing dust adhering to or generated on the back surface of the wafer by holding the back surface of the wafer with a wafer holding portion having a waviness formed on the front surface (Patent Document 3).

JP-A-5-326685 JP 7-057980 A JP-A-7-307375

  In recent years, with the miniaturization and high accuracy of magnetic disk drive devices, it is required to perform fine patterning with high accuracy in the wafer process of a thin film magnetic head.

  In order to perform such fine high-accuracy patterning and uniform film formation and etching within the wafer surface, the inventor of the present application is required to perform backside of the wafer during patterning, sputtering, etching and / or plating processes. It has been found that it is very important that the wafer is not tilted due to redeposits and dirt.

  However, the conventional techniques described in Patent Documents 1 to 3 all relate to a semiconductor wafer, and further, there is no suggestion about processing the wafer back surface in the wafer process.

  In a photo process that requires high-precision processing during a wafer process, a resist material or a developing solution wraps around and adheres to the back of the wafer during development, thereby inducing an unnecessary tilt of the wafer on the stage. . If the wafer is tilted on the stage, the alignment accuracy, defocus during exposure, and distribution in the shot will deteriorate, the final patterning accuracy will deteriorate, and wafer adsorption failure or gas by the vacuum chuck or electrostatic chuck will deteriorate. Yield decreases due to leakage.

  Also, in the dry process during the wafer process, if the sputtered film and etching components move to the backside of the wafer and adhere to it, the wafer tilts on the stage, and the sputter deposition distribution and etching distribution only deteriorate. First, a wafer adsorption failure or gas leakage caused by a vacuum chuck or an electrostatic chuck is induced, which causes a deterioration in yield.

  In addition, during the plating process, measurement process, and transfer during the wafer process, contamination during plating, dust during handling, metal due to contact with other substances during wafer transfer during transfer inside the device, etc. are on the back side of the wafer. Adhering causes similar inconveniences and decreases the yield.

  Accordingly, it is an object of the present invention to provide a method of manufacturing a thin film magnetic head that improves patterning accuracy, sputter deposition distribution and / or etching distribution and enables yield improvement.

  Another object of the present invention is to provide a method of manufacturing a thin film magnetic head which can prevent wafer adsorption failure in a vacuum chuck or electrostatic chuck and can improve yield.

  According to the present invention, there is provided a method for manufacturing a thin film magnetic head in which backside polishing for cleaning the backside of a wafer is performed at least once during the wafer process.

  The backside polishing is performed in the middle of the wafer process, not before or after the wafer process, and the backside of the wafer is cleaned. Therefore, the patterning accuracy is improved in the photo process, and the sputter deposition distribution and etching distribution are improved in the dry process. Further, it is possible to reduce the wafer adsorption failure in the vacuum chuck or the electrostatic chuck. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  It is preferable that the back surface polishing is performed immediately before a process that requires the planar accuracy of the back surface of the wafer.

  It is preferable that the process requiring the plane accuracy of the back surface of the wafer includes an exposure process when forming the resist pattern. More preferably, the exposure process includes an exposure process when forming a resist pattern in a lead conductor forming process of a magnetoresistive effect (MR) element and an exposure process when forming a resist pattern in a magnetic pole forming process of an inductive element. preferable.

  It is also preferable that the process requiring the planar accuracy of the back surface of the wafer includes a dry etching process. More preferably, the dry etching step includes a dry etching step in the lead conductor forming step of the MR element and a dry etching step in the magnetic pole forming step of the inductive element.

  It is also preferable that the process requiring the planar accuracy of the back surface of the wafer includes a sputtering process, a plating process, and / or a measurement process.

  It is also preferable that the back surface polishing is performed using a rotating grindstone with high plane accuracy. It is more preferable that the rotary grindstone is an alkanes grindstone having high plane accuracy and having a large number of edges.

  It is also preferable that the back surface polishing is performed using a polishing sheet with high planar accuracy.

  The back surface polishing is preferably performed after adsorbing and fixing only the outer peripheral portion of the wafer surface to the polishing stage.

  The wafer is preferably fixed by positioning the wafer on the polishing stage using guide pins or an annular guide frame lower than the wafer height.

  According to the present invention, it is possible to improve the patterning accuracy in the photo process, improve the sputter deposition distribution, and improve the etching distribution in the dry process, and further reduce the wafer adsorption failure in the vacuum chuck or electrostatic chuck. Can be reduced. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  FIG. 1 is a flowchart schematically showing a flow of a photo process during a wafer process of a thin film magnetic head as one embodiment of the present invention.

  In this photo process, first, the back surface of the wafer is polished (step S1), and contamination, dirt, adhered matter, and the like attached to the back surface of the wafer during the previous process and transfer are removed and cleaned.

  FIG. 2 is a side view showing a schematic configuration of a polishing apparatus used for this polishing process on the back surface of the wafer, and FIG. 3A is a plan view showing a configuration of a wafer fixing portion of the polishing apparatus, and FIG. It is.

  In these drawings, reference numeral 20 denotes a stage that rotates axially at, for example, 20 rpm during the polishing process, 21 denotes a wafer that is coaxially fixed on the stage 20 with its back surface 21b facing upward, and 22 denotes an outer periphery of the front surface 21a of the wafer 21. An outer peripheral chuck for adsorbing and fixing the portion, 22a is a vacuum hole provided in the outer peripheral chuck 22, 23 is an annular guide frame having a height lower than the wafer height for preventing the wafer 21 from being displaced, and 25 is A first rotary polishing head having a polishing sheet 25a attached to the tip, 26 a second rotary polishing head having an alkanes grindstone 26a attached to the tip, and 27 a solution dispenser. Instead of the annular guide frame 23, a plurality of guide pins 24 having a height lower than the wafer height may be used.

  The outer peripheral chuck 22 is configured to suck and fix only the outer peripheral portion of the surface 21 a of the wafer 21, for example, the peripheral portion of 5 mm or less from the outer edge, and the stage 20 contains counterbore. For this reason, there is no inconvenience that the front surface 21a of the wafer 21 contacts other members and is damaged during the back surface polishing.

  The first rotary polishing head 25 and the second rotary polishing head 26 can rotate clockwise and counterclockwise, and can rotate along with the rotation of the stage 20. The polishing sheet 25a of the first rotary polishing head 25 is, for example, a polishing cloth made of polyurethane and polyester fibers. As for the alkanesus grindstone 26a of the second rotary polishing head 26, grooves in the orthogonal direction or other arbitrary directions are provided on the surface of the alkanesus grindstone with good plane accuracy, or a plurality of small groove-free alkanesus grindstones are provided on the plane. A large number of edges are formed by fixing or the like. For example, a groove having a width of 2.5 mm and a depth of 2.0 mm is provided on the surface of a high-accuracy alkanesus grindstone so as to cross at a pitch of 5 mm. The surface shape of the alkanesus grindstone may be rectangular, circular, triangular or other polygonal. The direction of the groove, and hence the direction of the edge, is also arbitrary.

  As a polishing method, the stage 20 is rotated, and, for example, the first rotary polishing head 25 and the second rotary polishing head 26 that are swung with a swing stroke of 20 mm are sequentially pressed against the back surface of the wafer 21. Grind. First, the polishing sheet 25a of the first rotary polishing head 25 is pressed and polished while applying a load, and then the alkanesus grindstone 26a of the second rotary polishing head 26 is also pressed and applied to finish polishing. The removal efficiency is improved by rotating not only the stage but also the polishing head. In addition, since a high-accuracy alkanesus grindstone is used to polish at the edge, the rear surface of the wafer is not damaged and efficient cleaning and polishing can be performed. As a result, the polishing time is shortened and the production efficiency is improved.

  When a stubborn deposit is present on the back surface of the wafer, polishing is performed after an appropriate amount of pure water or a solution soluble in the deposit is introduced from the solution dispenser 27 so as not to enter the wafer surface 21a. However, after polishing, the solution and the like are wiped away.

  Instead of the high-planar accuracy alkanesus grindstone, other high-planar accuracy grindstones, polishing sheets or abrasive grains may be used for wiping and drying.

  In the photo process of FIG. 1, next, the wafer 21 subjected to back surface polishing and cleaning is attached to a resist coating apparatus, and a resist is applied to the wafer surface 21a (step S2), and a baking process and a cool process are performed.

  In this case, since the wafer back surface 21b is cleaned, the wafer is fixed to the resist coating apparatus in the correct posture and in the correct position without being tilted, so that the resist can be applied uniformly, and in that case, the vacuum is applied. Wafer adsorption failure at the chuck can be reduced. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  After this resist coating is completed, the wafer backside polishing is performed in the same manner as the wafer backside polishing process described above (step S3). As a result, the resist that wraps around the back surface 21b of the wafer in the resist coating process and the deposits such as dirt during transportation are removed.

  Next, the wafer 21 is attached to a stepper, that is, an exposure apparatus, and the resist layer is exposed (step S4), and further developed in the developing apparatus (step S5).

  Since the wafer back surface is cleaned immediately before the exposure process, the wafer is fixed to the exposure apparatus in the correct posture and in the correct position without being inclined. For this reason, it is possible to correctly maintain alignment accuracy, focus accuracy, and intra-shot distribution accuracy, thereby preventing a decrease in patterning accuracy, and further reducing a wafer suction failure in the vacuum chuck. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  After this development is completed, the wafer backside polishing is performed in the same manner as the wafer backside polishing process described above (step S6), so that the dissolved resist and developer stains that have come around the backside of the wafer in the development process, Remove deposits and clean.

  Next, the process proceeds to another process such as a dry process, a plating process, or a measurement process (step S7).

  FIG. 4 is a flowchart schematically showing a flow of a dry process during a wafer process of a thin film magnetic head as another embodiment of the present invention.

  In this dry process, first, the back surface of the wafer is polished (step S11), and contamination, dirt, deposits, and the like attached to the back surface of the wafer during the previous process and transfer are removed and cleaned.

  The content of this polishing process is the same as that of the wafer back surface polishing process described above.

  Next, the wafer 21 is attached to the sputtering apparatus for sputtering, or attached to the dry etching apparatus for dry etching (step S12). The dry etching process includes processes such as plasma etching, reactive ion etching (RIE), and ion milling.

  Since the back surface of the wafer is cleaned immediately before the sputtering or dry etching process, the wafer is fixed to these apparatuses in the correct posture and in the correct position without being inclined. For this reason, it is possible to prevent the sputter film formation distribution or the dry etching distribution from being deteriorated, and further, it is possible to reduce the wafer adsorption failure in the electrostatic chuck. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  After this sputtering or dry etching is completed, the wafer backside polishing is performed in the same manner as the wafer backside polishing process described above (step S13), so that the sputtered film or etching reattached around the wafer backside in these steps is performed. Remove and clean dirt such as kimono.

  Next, the process proceeds to another process such as a photo process, a plating process, or a measurement process (step S14).

  FIG. 5 is a flowchart schematically showing the flow of a plating process during a wafer process of a thin film magnetic head, as still another embodiment of the present invention.

  In this plating process, first, the back surface of the wafer is polished (step S21), and contamination, dirt, deposits, etc. adhering to the back surface of the wafer during the previous process or transfer are removed and cleaned.

  The content of this polishing process is the same as that of the wafer back surface polishing process described above.

  Next, the wafer 21 is attached to a plating apparatus to perform plating (step S22).

  Since the back surface of the wafer is cleaned immediately before the plating process, the wafer is fixed to the plating apparatus in the correct posture and in the correct position without being inclined. In the plating process, since the wafer itself acts as an electrode, it is possible to prevent the plating film distribution from deteriorating by removing the tilt of the wafer. Further, at that time, it is possible to reduce the wafer adsorption failure in the vacuum chuck. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  After the plating process is completed, the wafer backside polishing is performed in the same manner as the wafer backside polishing process described above (step S23), thereby removing dirt and deposits such as a plating solution that has entered the backside of the wafer in this step. Remove and clean.

  Next, the process proceeds to another process such as a dry process, a photo process, or a measurement process (step S24).

  FIG. 6 is a flowchart schematically showing a flow of a measurement process during a wafer process of a thin film magnetic head as still another embodiment of the present invention.

  In this measurement process, first, the back surface of the wafer is polished (step S31), and the contaminants, dirt, deposits, and the like adhering to the back surface of the wafer during the previous process and transfer are removed and cleaned.

  The content of this polishing process is the same as that of the wafer back surface polishing process described above.

  Next, the wafer 21 is attached to the measuring apparatus and measurement is performed (step S32).

  Since the back surface of the wafer is cleaned immediately before the measurement process, the wafer is fixed to the measuring apparatus in the correct posture and in the correct position without being tilted. For this reason, it is possible to perform highly accurate measurement, and further, it is possible to reduce wafer suction failure in the vacuum chuck. Therefore, the yield of manufacturing the thin film magnetic head is improved, and stable mass production can be expected.

  Next, the process proceeds to another process such as a dry process, a photo process, a plating process, etc. (step S33).

  FIG. 7 is a flowchart for explaining a part of a wafer process of a thin film magnetic head as an example to which the present invention is specifically applied, and FIG. 8 is a schematic diagram showing a layer structure in the first lead conductor forming step of FIG. FIG. 9 is a cross-sectional view schematically showing the layer structure in the write pole forming step of FIG.

First, Al ₂ O ₃ or the like is formed by sputtering on the wafer substrate 80 made of Al—TiC or the like to form the insulating layer 81, and the lower shield layer 82 is formed thereon (step S71). Al ₂ O ₃ or the like is formed on the lower shield layer 82 by sputtering and planarized to form the lower shield gap layer 83 (step S72).

Next, a spin valve MR multilayer film 84 is formed thereon (step S73), a hard mag layer is further formed (step S74), and an insulating layer such as Al ₂ O ₃ is refilled (step S75).

  Thereafter, a first lead conductor is formed thereon (step S76). Hereinafter, the step of forming the first lead conductor will be described in detail.

  First, the first lead conductor film 85 is formed by sputtering Cu and Au on the spin valve MR multilayer film 84, the hard mug layer, and the insulating layer (step S761). FIG. 8A shows the layer structure in this state.

  Next, a photo process for determining the lead width is performed (step S762). First, after polishing the back surface of the wafer and cleaning the back surface, a resist film 86 is applied on the first lead conductor film 85 as shown in FIG. Next, as shown in FIG. 8C, after the back surface of the wafer is polished and the back surface is cleaned, the wafer is attached to an exposure device for exposure, and further developed by a developing device. A resist pattern 86 'as shown in (D) is obtained.

  Next, as shown in FIG. 8E, Ta is sputtered from above to form a Ta layer 87 (step S763).

  Next, as shown in FIG. 8F, the resist pattern 86 'is removed by lift-off to form a Ta mask 87' (step S764).

  After this lift-off process, the back surface of the wafer is polished to clean the back surface.

  Thereafter, RIE is performed to pattern the first lead conductor film 85, and the lead width is formed to determine the MR track width (MRT) (step S765).

Next, a second lead conductor is formed (step S77), Al ₂ O ₃ or the like is formed by sputtering to form an upper shield gap layer 88 (step S78), and an upper shield layer 89 is formed thereon. (Step S79).

Next, Al ₂ O ₃ or the like is formed thereon by sputtering to form the insulating layer 90 (step S80), and a magnetic layer to be the lower yoke layer 91 is formed thereon (step S81).

Next, a magnetic layer 92 having a high saturation magnetic flux density (Bs) is formed thereon (step S82), and a write gap layer 93 is formed thereon by sputtering Al ₂ O ₃ or the like (step S83).

  Next, a first coil conductor layer is formed thereon (step S84), and a coil insulating layer is formed from a resist material or the like (step S85).

  Thereafter, a write magnetic pole is formed thereon (step S86). Hereinafter, the process of forming the write magnetic pole will be described in detail.

  First, a frame photo process for the write magnetic pole is performed (step S861). First, after polishing the back surface of the wafer and cleaning the back surface, a resist film 94 is applied over the write gap layer 93 as shown in FIG. Next, as shown in FIG. 9B, after the back surface of the wafer is polished and the back surface is cleaned, the wafer is attached to an exposure apparatus for exposure, and further developed by a developing apparatus. A resist pattern 94 'as shown in FIG.

  Next, as shown in FIG. 9D, after the upper magnetic pole 95 is formed by plating using the resist pattern 94 'as a frame mask, the resist pattern 94' is peeled off (step S862).

  After this plating step, the back surface of the wafer is polished to clean the back surface.

  Thereafter, as shown in FIG. 9E, RIE is performed using the upper magnetic pole 95 as a mask to form a write gap 93 '(step S863).

  Next, as shown in FIG. 9F, the high saturation magnetic flux density magnetic layer 92 and the lower yoke layer 91 are trimmed to form the lower magnetic pole 92 'and the lower yoke 91' (step S864).

  Next, a second coil conductor layer is formed (step S88), and a coil insulating layer is formed using a resist material or the like (step S89).

  Thereafter, formation of the upper yoke layer (step S90), formation of bumps (step S91), formation of the overcoat layer (step S92), bump removal from the overcoat layer (step S93), and the like are sequentially performed to perform the wafer process. Exit.

  As described above, in this specific example of the wafer process of the thin film magnetic head, the exposure process in the photo process of the write magnetic pole is performed immediately before the exposure process and immediately before the RIE for determining the lead width whose dimensional accuracy is severe. Since the wafer back surface polishing cleaning is performed immediately before and RIE, the wafer can be mounted on each apparatus with high accuracy. Therefore, it is possible to improve the patterning accuracy and the etching distribution, and further reduce the wafer adsorption failure in the electrostatic chuck, so that the yield of the thin film magnetic head manufacturing is improved and stable mass production can be expected. it can.

  It is desirable to perform wafer back surface polishing cleaning immediately before the exposure step in other photo processes.

  All the embodiments described above are illustrative of the present invention and are not intended to be limiting, and the present invention can be implemented in other various modifications and changes. Therefore, the scope of the present invention is defined only by the claims and their equivalents.

FIG. 5 is a flowchart schematically showing a flow of a photo process during a wafer process of a thin film magnetic head as one embodiment of the present invention. It is a side view which shows schematic structure of the grinding | polishing apparatus used for the grinding | polishing process of a wafer back surface. It is the top view and side view which show the structure of the wafer fixing | fixed part of the grinding | polishing apparatus of FIG. FIG. 10 is a flowchart schematically showing a flow of a dry process during a wafer process of a thin film magnetic head as another embodiment of the present invention. FIG. 16 is a flowchart schematically showing a flow of a plating process during a wafer process of a thin film magnetic head as still another embodiment of the present invention. FIG. 16 is a flowchart schematically showing a flow of a measurement process during a wafer process of a thin film magnetic head as still another embodiment of the present invention. It is a flowchart explaining a part of wafer process of a thin film magnetic head as an example which applied this invention concretely. FIG. 8 is a cross-sectional view schematically showing a layer structure in a step of forming a first lead conductor in FIG. 7. FIG. 8 is a cross-sectional view schematically showing a layer structure in a step of forming a write magnetic pole in FIG. 7.

Explanation of symbols

20 Stage 21 Wafer 21a Wafer surface 21b Wafer back surface 22 Peripheral chuck 22a Vacuum hole 23 Annular guide frame 24 Guide pin 25 First rotating head 25a Polishing sheet 26 Second rotating head 26a Alcanthus whetstone 27 Solution dispenser 80 Wafer substrate 81, 90 Insulating layer 82 Lower shield layer 83 Lower shield gap layer 84 Spin valve MR multilayer 84
85 First lead conductor film 86, 94 Resist film 86 ', 94' Resist pattern 87 Ta layer 87 'Ta mask 88 Upper shield gap layer 89 Upper shield layer 91 Lower yoke layer 91' Lower yoke 92 High saturation magnetic flux density magnetic layer 92 'lower magnetic pole 93 write gap layer 93' write gap 95 upper magnetic pole

Claims (16)

  A method of manufacturing a thin film magnetic head, comprising performing at least one backside polishing for cleaning the backside of a wafer during a wafer process.   The manufacturing method according to claim 1, wherein the back surface polishing is performed immediately before a process that requires planar accuracy of the back surface of the wafer.   The manufacturing method according to claim 2, wherein the step that requires planar accuracy of the back surface of the wafer includes an exposure step in forming a resist pattern.   The manufacturing method according to claim 3, wherein the exposure step includes an exposure step in forming a resist pattern in the lead conductor forming step of the magnetoresistive effect element.   5. The manufacturing method according to claim 3, wherein the exposure step includes an exposure step for forming a resist pattern in the magnetic pole forming step of the inductive element.   6. The manufacturing method according to claim 2, wherein the step that requires the planar accuracy of the back surface of the wafer includes a dry etching step.   The manufacturing method according to claim 6, wherein the dry etching step includes a dry etching step in a lead conductor forming step of the magnetoresistive effect element.   The manufacturing method according to claim 6, wherein the dry etching step includes a dry etching step in a magnetic pole forming step of the inductive element.   9. The manufacturing method according to claim 2, wherein the step that requires planar accuracy of the back surface of the wafer includes a sputtering step.   The manufacturing method according to claim 2, wherein the step that requires planar accuracy of the back surface of the wafer includes a plating step.   11. The manufacturing method according to claim 2, wherein the step that requires the planar accuracy of the back surface of the wafer includes a measurement step.   The manufacturing method according to any one of claims 1 to 11, wherein the back surface polishing is performed using a rotating grindstone with high plane accuracy.   The manufacturing method according to claim 12, wherein the rotating grindstone is an alkanes grindstone having high planar accuracy and having a large number of edges.   The manufacturing method according to any one of claims 1 to 13, wherein the back surface polishing is performed using a polishing sheet with high planar accuracy.   The manufacturing method according to claim 1, wherein the back surface polishing is performed after adsorbing and fixing only the outer peripheral portion of the wafer surface to the polishing stage. The manufacturing method according to claim 15, wherein the wafer is fixed by positioning the wafer on a polishing stage using guide pins or an annular guide frame lower than the wafer height.

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