JP4035487B2 - Method for manufacturing thin film magnetic head substrate - Google Patents

Description

  The present invention relates to a thin film magnetic head substrate including a plurality of magnetoresistive elements and a QST evaluation test element having the same electromagnetic characteristics as the magnetoresistive elements and a method for manufacturing the same.

  Conventionally, in order to improve productivity, a thin film magnetic head structure is simultaneously formed for each of a plurality of element formation areas on a substrate, and then the substrate is cut in units of each element formation area. Manufacture.

  In such a thin film magnetic head, a characteristic quality inspection is performed in order to confirm whether or not a standard as a pre-defined product is satisfied before manufacturing or shipping. As characteristic quality inspection, a QST (Quasi Static Test) evaluation test is generally used. The QST evaluation test is a technique for evaluating the reproduction output characteristics and magnetic stability of a thin film magnetic head without using an actual magnetic recording medium. Specifically, an external magnetic field of about 3.98 to 39.8 kA / m is periodically changed in a state where a thin film magnetic head (magnetoresistance effect element) is energized, and the element voltage-external magnetic field characteristics of the thin film magnetic head. A curve (VH curve) is obtained. And based on the obtained VH curve, from the viewpoint of reproduction output characteristics, magnetic symmetry / polarity of reproduction output (Asym, Polarity), noise (Barkhausen noise), etc., it is within or outside of the standard. Determine whether.

At present, the substrate is cut into individual element formation area units to form individual thin film magnetic head substrates, and then electrode pad layers are formed, and then ground on the surface (ABS surface) of each thin film magnetic head substrate facing the recording medium. A QST evaluation test is conducted after processing.
JP 2000-113430 A JP 2000-182219 A JP 2000-187820 A JP 2000-195020 A JP 2000-322712 A JP 2003-46163 A JP 2003-60262 A

  Incidentally, the thin film magnetic head is also evaluated by an electromagnetic characteristic (DET) test using an actual magnetic recording medium at the final stage of the manufacturing process. It is known that the DET test and the QST evaluation test have a high correlation. Therefore, in order to discover a magnetoresistive effect element out of specification at an early stage, it is preferable to carry out a highly accurate QST evaluation test in the course of the manufacturing process. The QST evaluation test should be carried out above.

  However, immediately after the formation of the magnetoresistive effect element, the electrode electrically connected to the magnetoresistive effect element is not yet formed, and the magnetoresistive effect element is not exposed to the ABS surface. The QST measuring needle for energization could not be brought into contact with the magnetoresistive effect element, and the QST evaluation test could not be performed on the wafer substrate. Further, when an attempt is made to perform a QST evaluation test on a substrate in a wafer state, the shape (height dimension) of the magnetoresistive effect element immediately after formation is different from the shape of the magnetoresistive effect element when the head is completed. There arises a problem that the correlation of the DET test results is lowered. In this case, the reliability of the QST evaluation test result is low, and even if it is determined as a nonstandard product in the QST evaluation test, it may be determined as a standard product in the DET evaluation test.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain a method of manufacturing a thin film magnetic head substrate capable of performing a highly accurate QST evaluation test on a substrate in a wafer state that is not cut individually. To do.

  According to the present invention, if at least one of a plurality of magnetoresistive elements formed on a substrate is an inspection element having the same film configuration and shape as the magnetoresistive element when the head is completed, the inspection element Is used to perform a highly accurate electromagnetic characteristic evaluation test (QST evaluation test) even on a substrate in a wafer state that is not cut individually.

That is, the present invention virtually divides the substrate surface into a plurality of element formation areas arranged in at least one of the track width direction and the height direction of the magnetoresistive effect element to be formed. A step of further setting the formation area into an actual element formation area for forming a magnetoresistive effect element and at least one inspection element formation area for forming an inspection element; a lower magnetic shield on the substrate in order from the bottom Forming a layer, a first insulating layer, and a magnetoresistive film , wherein before forming the first insulating layer, another insulating layer is entirely formed on the substrate, and the other The actual element forming area of the insulating layer is removed by etching, the lower magnetic shield layer is formed by plating, and the partial insulating layer is formed by the other insulating layer remaining in the inspection element forming area. Subjected to CMP processing and the upper surface of the partial insulation layer on the upper surface of the lower magnetic shielding layer was smoothened, wherein forming the first insulating layer on the planarizing surface steps and; the actual device forming area and the test element forming The track width dimension of the magnetoresistive effect film in the area is defined to be the same as the track width dimension of the magnetoresistive effect element 4 when the head is completed. Forming a layer; defining the height dimension of the magnetoresistive film in the actual element forming area to be larger than the height dimension when the head is completed, and setting the height dimension of the magnetoresistive film in the inspection element forming area to the head Defining the same height dimension of the magnetoresistive effect element at the time of completion ; forming a second insulating layer on the magnetoresistive effect film and a part of the electrode layer; magnetism of the inspection element forming area Resistive effect film Electrically connected to the lead electrode layer and the electrode layers which is not covered with the second insulating layer and electrically connected to the step of forming the second insulating layer by; the lead electrode layer above the test element via the Applying an external magnetic field in a state where a sense current is passed through the magnetoresistive film in the formation area, and performing an electromagnetic property evaluation test for each inspection element formation area on the uncut substrate; Determining whether or not the result satisfies a predetermined criterion. If the criterion is satisfied, an upper magnetic shield layer is formed on the magnetoresistive film in the actual element formation area; and Forming an inductive head element on the upper magnetic shield layer in the element formation area.

By Ino lower magnetic shield layer is such present in the test element formation area, without being affected by the lower magnetic shield layer in an electric magnetic property test (QST evaluation test), it is possible to improve the evaluation accuracy.

  Furthermore, the manufacturing method of the thin film magnetic head substrate of the present invention is a slider manufacturing process which is a subsequent process only for a non-defective product which is manufactured by the manufacturing method and meets the predetermined standard by performing the electromagnetic characteristic evaluation test. A current is passed through the actual element to conduct a second electromagnetic characteristic evaluation test to make a pass / fail judgment. Only those that are judged to be non-defective in the slider manufacturing process are subjected to the actual head gimbal assembly process. It is preferable to use a recording medium for the element to make a pass / fail determination in a final electromagnetic property evaluation test.

In addition, in the above manufacturing method, the results of the electromagnetism test and the characteristic evaluation test of the thin film magnetic head substrate, the second electromagnetism evaluation of the slider manufacturing process, and the final electromagnetism evaluation test result of the head gimbal assembly It is preferable that a predetermined standard is determined by conducting the electro-magnetic characteristic evaluation test on the thin-film magnetic head substrate based on the correlation with the above.

  According to the present invention, the inspection element having the same film configuration and the same shape as the magnetoresistive effect element when the head is completed is provided, and the extraction electrode layer that is exposed on the substrate surface and supplies power to the inspection element. It has become possible to perform a highly accurate QST evaluation test on a substrate in a wafer state that has not been cut individually. If a high-precision QST evaluation test can be performed in the wafer state, non-standard products can be found and eliminated at an early stage of the manufacturing process, and the yield in the subsequent process can be improved, thereby contributing to cost reduction. In addition, it was possible to detect factors that caused non-standard products in the manufacturing process early, and to correct the manufacturing process quickly. Furthermore, it is possible to provide quick feedback when evaluating prototypes under development, which has the advantage of reducing development time and improving development efficiency.

Further, according to the present invention, since there is no magnetic shield layer in the area where the test element and the extraction electrode layer are formed, there is no influence of the magnetic shield layer when performing the QST evaluation test on the substrate, It is possible to maintain good correlation between the QST evaluation test result and the result of the electromagnetic property test performed in the final stage. Therefore, non-standard products can be selected with high accuracy based on the QST evaluation test results.

  The present invention will be described below with reference to the drawings. In the figure, the X direction is the track width direction of the magnetoresistive effect element, the Y direction is the height direction of the magnetoresistive effect element, and the Z direction is the stacking direction of the layers constituting the magnetoresistive effect element.

  1 and 2 are plan views showing a thin film magnetic head substrate H according to an embodiment of the present invention. The thin film magnetic head substrate H includes a plurality of magnetoresistive elements 4 formed on the substrate 1 made of AlTiC (AlTiC), for example, arranged in the X direction (track width direction) and the Y direction (height direction). And at least one inspection element 5 for QST evaluation incorporated in the array of the plurality of magnetoresistive elements 4.

  In the present embodiment, the substrate surface is virtually divided into the illustrated X direction and the illustrated Y direction to provide a plurality of element formation areas A (actual element formation area Am, inspection element formation area At), and one element formation area. One magnetoresistive element 4 or inspection element 5 is formed on A. Between each element formation area A, a horizontal dicing line Dh parallel to the track width direction and a vertical dicing line Dp orthogonal to the track width direction are provided. The substrate 1 is cut along the horizontal dicing line Dh and the vertical dicing line Dp after forming a plurality of magnetoresistive effect elements 4 and at least one inspection element 5 and further forming an electrode pad layer. When the individual substrates 1 after cutting are ground in the Y direction in the drawing, a thin film magnetic head in a completed state is obtained. In FIG. 1, for the sake of convenience, the magnetoresistive effect element 4 is indicated by a white circle and the test element 5 is indicated by a black circle so that the magnetoresistive effect element 4 and the inspection element 5 on the substrate 1 can be easily seen.

  As shown in FIGS. 3 and 4, the magnetoresistive effect element 4 is inserted between the lower magnetic shield layer 2 and the upper magnetic shield layer 9 via the first insulating layer 3 and the second insulating layer 8. As the magnetoresistive effect element 4, an AMR element utilizing an anisotropic magnetoresistive (AMR) effect, a GMR element utilizing a giant magnetoresistive (GMR) effect, or a tunnel MR (TMR) element can be used.

  In the present embodiment, the magnetoresistive element 4 is a GMR element. As shown in FIG. 3, on the first insulating layer 3 which is the lower gap layer, an antiferromagnetic layer 4A, a pinned magnetic layer 4B whose magnetization is fixed in the Y direction by the antiferromagnetic layer 4A, and a nonmagnetic material layer 4C, a free magnetic layer 4D, and a cap layer 4E are sequentially stacked. On both sides of the magnetoresistive element 2 in the X direction shown in the figure, a bias magnetic layer 6 and an electrode layer 7 for aligning the magnetization direction of the free magnetic layer 4D in the X direction shown in the figure are laminated. A second insulating layer 8 that is an upper gap layer is formed on the effect element 4.

The lower magnetic shield layer 2 and the upper magnetic shield layer 9 are formed of a soft magnetic material such as NiFe or CoFe, and the first insulating layer 3 and the second insulating layer 8 are formed of an insulating material such as alumina or SiO ₂ . The bias magnetic layer 6 is made of a ferromagnetic material such as CoPtCr, and the electrode layer 7 is made of a conductive material such as Au, Cr, or Cu. The antiferromagnetic layer 4A is made of a PtMn alloy, and the pinned magnetic layer 4B and the free magnetic layer 4D are made of a soft magnetic material such as NiFe or CoFe. The nonmagnetic material layer 4C is made of Cu, for example. The pinned magnetic layer 4B and the free magnetic layer 4D may be formed of a single layer film or a laminated film, or may be formed of a laminated ferrimagnetic structure in which a nonmagnetic metal layer is sandwiched between magnetic layers. The pinned magnetic layer 4B may be formed of a self-pinned pinned magnetic layer, and the antiferromagnetic layer 4A may not be provided.

  As shown in FIG. 4, the plurality of magnetoresistive elements 4 are formed so that the track width dimension is the same as the track width dimension Tw when the head is completed, and the height dimension is higher than the height dimension MRh when the head is completed. A large MRh ′ (MRh ′> MRh) is formed. Here, the reason why the height dimension MRh ′ of the magnetoresistive effect element 4 is larger than the height dimension MRh when the head is completed is that grinding is performed after the substrate is cut as described above. It is adjusted to the height dimension MRh when the head is completed. A broken line shown in FIG. 4 is a position that becomes an end surface in the Y direction of the substrate 1 when the head is completed.

  As shown in FIGS. 5 to 7, the inspection element 5 is a magnetoresistive effect film having the same film configuration as the magnetoresistive effect element 4 described above, and the track width dimension and the height dimension are the same as the magnetic characteristics at the completion of the head. The resistive element 4 is formed with the same dimensions as the track width dimension Tw and the height dimension MRh. That is, the test element 5 has the same film configuration and the same shape as the magnetoresistive effect element 4 when the head is completed. This inspection element 5 is assumed to have the same electromagnetic characteristics as the magnetoresistive effect element 4 in a completed state (after cutting and grinding of the thin film magnetic head substrate H), and is performed during the manufacturing process. In the second QST evaluation test, the electromagnetic characteristics are evaluated instead of the plurality of magnetoresistive elements 4.

  The lower magnetic shield layer 2 and the upper magnetic shield layer 9 do not exist above and below the test element 5, and a partial insulating layer 3 ′ is formed instead of the lower magnetic shield layer 2. The first insulating layer 3 includes the partial insulating layer 3 ′ covering the substrate 1 in the test element formation area At, and the entire insulating layer 3 ″ covering the partial insulating layer 3 ′ and the lower magnetic shield layer 2, The inspection element formation area At is thicker than the element formation area Am by the partial insulating layer 3 ′. This inspection element 5 is removed when the substrate 1 in a wafer state is cut, and does not become a product.

  An extraction electrode layer 10 electrically connected to the inspection element 5 is formed on the second insulating layer 8 in the element formation area At where the inspection element 5 is formed. The extraction electrode layer 10 is made of an electrode material such as Au, Ag, Cu, Cr, or W, for example. In the element formation area At, as shown in FIG. 2, the uppermost layer (cap layer) of the test element 5, the extraction electrode layer 10, and the second insulating layer 8 are exposed.

  In the thin-film magnetic head substrate H having the above-described configuration, the substrate 1 is individually cut by bringing the extraction electrode layer 10 and a QST measuring needle (not shown) of the QST evaluation apparatus into contact with each other and supplying current to the inspection element 5. The QST evaluation test can be performed on the test element 5 having substantially the same electromagnetic characteristics as the magnetoresistive effect element 4 while the wafer is not in a wafer state. The implementation method of the QST evaluation test will be described later.

  Next, an embodiment of a method for manufacturing the thin film magnetic head substrate H shown in FIG. 1 will be described with reference to FIGS.

  First, a plurality of element formation areas A are set by virtually dividing the substrate surface in the illustrated X direction and the illustrated Y direction, and the plurality of element formation areas A are further formed to form the magnetoresistive effect element 4. The actual element formation area Am and the inspection element formation area At for forming the inspection element 5 are set. The number and position of the inspection element formation areas At are preferably set as appropriate in accordance with the evaluation accuracy of a characteristic quality test to be performed later, the number of steps to be performed until the characteristic quality test is performed, and the like.

  Next, the lower magnetic shield layer 2 is entirely formed on the substrate 1. Sputtering is used for film formation. As the sputtering method, a DC magnetron sputtering method, an RF sputtering method, an ion beam sputtering method, a long throw sputtering method, a collimation sputtering method, or the like can be used.

  Subsequently, as shown in FIG. 8, a lift-off resist layer R1 is formed on the actual element formation area Am, and all the lower magnetic shield layer 2 not covered with the resist layer R1 is removed. As a result, the lower magnetic shield layer 2 remains only in the actual element formation area Am, and the substrate 1 is exposed without the lower magnetic shield layer 2 existing in the inspection element formation area At. Here, the reason why the lower magnetic shield layer 2 on the inspection element formation area At is removed is to prevent the lower magnetic shield layer 2 from being affected by the QST evaluation test.

  Subsequently, as shown in FIG. 9, a partial insulating layer 3 ′ to be a part of the first insulating layer 3 to be formed is formed on the exposed substrate 1 with the resist layer R1 remaining. To do. After the partial insulating layer 3 'is formed, the resist layer R1 is removed by lift-off. The partial insulating layer 3 ′ is formed with a thickness that allows the upper surface of the partial insulating layer 3 ′ and the upper surface of the lower magnetic shield layer 2 to be smoothly continuous.

  When the resist layer R1 is removed, as shown in FIG. 10, a full-surface insulating layer 3 ″ which is the remaining portion of the first insulating layer 3 to be formed is formed on the lower magnetic shield layer 2 and the partial insulating layer 3 ′. To do. The entire surface insulating layer 3 ″ is formed with a film thickness thinner than that of the partial insulating layer 3 ′. The first insulating layer 3 is formed by the entire insulating layer 3 ″ and the partial insulating layer 3 ′. The film thickness of the first insulating layer 3 is thicker than the actual element forming area Am by the partial insulating layer 3 ′ in the test element forming area At.

  The lower shield layer 2 and the partial insulating layer 3 'can be formed by the following process. That is, a partial insulating layer 3 ′ is formed on the entire surface of the substrate 1, and the partial insulating layer 3 ′ located in the actual element formation area Am is removed by etching or the like from the partial insulating layer 3 ′ to remove the lower shield layer. 2 is formed entirely by plating. Then, the surface is flattened by performing a CMP process or the like, and the film thickness height positions of the lower shield layer 2 and the partial insulating layer 3 ′ are matched. As a result, the lower shield layer 2 is formed in the actual element formation area Am, and the partial insulating layer 3 ′ is formed in the inspection element formation area At.

  When the first insulating layer 3 is formed, the magnetoresistive effect element 4 is formed on the first insulating layer 3 in the actual element forming area Am, and the test element 5 is formed on the first insulating layer 3 in the test element forming area At. To do. The magnetoresistive effect element 4 and the test element 5 are magnetoresistive effect films having the same film configuration, and can be formed by substantially the same manufacturing process.

  For example, when the magnetoresistive effect element 4 and the test element 5 are formed by the GMR elements shown in FIGS. 3 and 5, first, each layer (antiferromagnetic) constituting the magnetoresistive effect film is formed on the first insulating layer 3. A layer 4A, a pinned magnetic layer 4B, a nonmagnetic material layer 4C, a free magnetic layer 4D, and a cap layer 4E) are sequentially deposited over the entire surface. Next, on the cap layer 4E, a resist layer R2 that defines the track width dimension of the magnetoresistive effect element 4 and the inspection element 5 to be formed to be the same as the track width dimension Tw when the head is completed is formed. In the present embodiment, both sides of the resist layer R2 in the X direction shown in the figure are curved as shown in FIG. 11 so that the track width dimension can be defined with high accuracy, and both end faces of the resist layer R2 are parallel to each other. The track width dimension Tw is defined by the straight portion. After the resist layer R2 is formed, as shown in FIG. 12, the cap layer 4E not covered with the resist layer R2 to the antiferromagnetic layer 4A are removed, and the bias magnetic layer 6 and the electrode layer 7 are formed in the removed portion. Form a film. After the electrode layer 7 is formed, the resist layer R2 is removed.

  Subsequently, as shown in FIGS. 13A and 13B, the height of the magnetoresistive effect element 4 to be formed on the cap layer 4E and the electrode layer 7 in the actual element formation area Am is set to complete the head. A resist layer R3 having a dimension MRh ′ larger than the height dimension MRh is formed. At the same time, the height dimension of the inspection element 5 to be formed on the cap layer 4E and the electrode layer 7 in the inspection element formation area At is defined to be the same as the height dimension MRh of the magnetoresistive effect element 4 when the head is completed. A resist layer R4 is formed. Subsequently, the magnetoresistive film (each layer from the cap layer 4E to the antiferromagnetic layer 4A), the bias magnetic layer 6 and the electrode layer 7 not covered with the resist layer are removed, and the resist layers R3 and R4 are further removed. To do. Then, as shown in FIG. 14, the second insulating layer 8 is formed on the removed portion of the magnetoresistive film and on the cap layer 4E and the electrode layer 7 (except for the connecting portion 7a with the extraction electrode layer to be formed later). Form. Thereby, the magnetoresistive effect element 4 having the same track width dimension Tw as that at the time of completion of the head and the height dimension MRh ′ larger than that at the time of completion of the head is formed in the element formation area Am. The inspection element 5 having the same track width dimension Tw and height dimension MRh as the magnetoresistive effect element 4 when the head is completed is formed.

  When the magnetoresistive effect element 4 and the test element 5 are formed, as shown in FIG. 15, the connection of the electrode layer 7 exposed from the second insulation layer 8 is formed on the second insulation layer 8 in the test element formation area At. The extraction electrode layer 10 connected to the portion 7a is patterned. The extraction electrode layer 10 is electrically connected to the test element 5 through the electrode layer 7. FIG. 2 shows an example of the planar shape of the extraction electrode layer 10.

  Subsequently, the first QST evaluation test is performed. The QST evaluation test here is performed on the substrate 1 in a wafer state that is not cut by using the inspection element 5 instead of the plurality of magnetoresistance effect elements 4. The inspection element 5 is formed with the same film configuration and shape (track width dimension Tw and height dimension MRh) as the magnetoresistive effect element 4 when the head is completed by the above process, and the magnetoresistive effect element 4 when the head is completed. It is assumed that it has almost the same electromagnetic characteristics. Therefore, in this embodiment, based on the QST evaluation test result of the test element 5, it is determined whether or not the output characteristics, magnetic symmetry, and the like of the plurality of magnetoresistive effect elements 4 satisfy a predetermined standard.

  Specifically, in the first QST evaluation test, first, the substrate 1 on which the extraction electrode layer 10 is formed is placed on a mounting table of a QST measurement device (not shown). Next, the QST measurement needle of the QST measurement apparatus is brought into contact with the extraction electrode layer 10, and a sense current is passed from the QST measurement needle to the test element 5 through the extraction electrode layer 10 and the electrode layer 7. The magnitude of the sense current is about 0.5 to 10 mA. Subsequently, application of an external magnetic field to the substrate 1 is started, the magnitude of the external magnetic field is periodically changed in a range of about 3.98 to 39.8 kA / m, and the output of the test element 5 with respect to the external magnetic field H The voltage V is detected. That is, a characteristic curve (VH curve) between the output voltage V of the test element 5 and the external magnetic field H is obtained. An example of the VH curve obtained in this embodiment is shown in FIG. Then, based on the obtained VH curve, it is determined whether or not it is out of specification from the viewpoint of reproduction output characteristics of the test element 5, magnetic symmetry of reproduction output, noise (Barkhausen noise), and the like. In this determination, the substrate 1 determined to be a nonstandard product is discarded, and the subsequent steps are continued only for the substrate 1 determined to be a standard product.

  When the first QST evaluation test is performed, the upper magnetic shield layer 9 is entirely formed on the actual element formation area Am. At this time, nothing is formed on the inspection element formation area At. Through the above steps, the thin film magnetic head substrate H shown in FIG. 1 is completed.

  The completed thin film magnetic head substrate H is further formed on the substrate 1 along the horizontal dicing line Dh and the vertical dicing line Dp after an electrode pad layer electrically connected to the electrode layer 7 of the magnetoresistive element 5 is formed. Is divided into individual thin film magnetic head substrates by cutting each element forming area A. During this division, the thin film magnetic head substrate (inspection element formation area At) on which the inspection element 5 is formed is removed and does not become a product. On the other hand, the thin film magnetic head substrate (actual element formation area Am) on which the magnetoresistive effect element 5 is formed is ground on the end surface on the Y direction side in the figure to become a slider. By this process, the height dimension of the magnetoresistive effect element 5 is defined by the height dimension MRh when the head is completed, and the end surface on the Y direction side in the drawing becomes the ABS surface. Each layer of the magnetoresistive element 5 is exposed on the ABS surface.

  Each slider is subjected to a second QST evaluation test in a state where a sense current is passed through the magnetoresistive effect element 5 through the electrode pad layer. The sliders determined as non-standard products in the second QST evaluation test are removed, and only the sliders determined as standard products are bonded onto the flexure to form a head gimbal assembly (HGA). In the head gimbal assembly, a final characteristic test performed using an actual magnetic recording medium, that is, a DET test is performed. If the DET test determines that the product is good, the product is shipped as a product.

  16 and 17 are graphs showing examples of VH curves obtained in the first QST evaluation test. FIG. 16 shows a case where the lower magnetic shield layer exists under the inspection element 5, and FIG. 17 shows a case where the lower magnetic shield layer does not exist under the inspection element 5.

  In the case where the lower magnetic shield layer 2 is present in the range where the inspection element 5 is formed, as shown in FIG. 16, disturbance is caused particularly in a low magnetic field region of about −10 to +10 kA / m, It can be seen that the output of the test element 5 is disturbed. This is because the lower magnetic shield layer 2 and the upper magnetic shield layer 9 are not optimally shaped on the substrate 1 in the wafer state, and the inspection element 4 is not exposed (AMS surface is not formed). From this, it is considered that the lower magnetic shield layer 2 existing under the inspection element 4 becomes a disturbance factor of the external magnetic field. Thus, if the output of the test element 5 is unstable, the accuracy (reliability) of the QST evaluation test is low, and the correlation with the result of the DET test performed at the final stage (the stage where the head gimbal assembly is made). Will also decline. In this case, even if it is determined as a nonstandard product in the QST evaluation test, it may be determined as a standard product in the DET evaluation test.

  On the other hand, if the lower magnetic shield layer 2 is not present in the area where the test element 5 is formed, as shown in FIG. 17, no disturbance occurs and the output of the test element 5 is stable. I understand. If a clean VH curve is obtained in this way, the accuracy (reliability) of the QST evaluation test is improved, and the correlation with the DET test result is also kept good. Therefore, nonstandard products can be selected with high accuracy based on the QST evaluation test results. That is, if it is determined whether or not it is out of specification based on the QST evaluation test result, the same determination result as in the case of determining whether or not it is out of specification based on the DET test result can be obtained. Since the first QST evaluation test is performed before the upper magnetic shield layer 9 is formed, the upper magnetic shield layer 9 does not exist in the area where the test element 5 is formed.

  FIG. 18 shows the QST evaluation test and DET using the output voltage (mV) of the magnetoresistive element 4 measured in the DET test as the vertical axis and the output voltage (mV) of the test element 5 measured in the QST evaluation test as the horizontal axis. It is a graph which shows the relationship with a test. As shown in FIG. 18, since each sample value is distributed on a straight line having a predetermined slope, the output voltage of the magnetoresistive effect element 4 measured in the DET test and the output of the test element 5 measured in the QST evaluation test. It can be seen that a proportional relationship is established with the voltage.

  FIG. 19 shows the QST evaluation test using the magnetic symmetry (%) of the magnetoresistive effect element 4 measured in the DET test as the vertical axis and the magnetic symmetry (%) of the test element 5 measured in the QST evaluation test as the horizontal axis. It is a graph which shows the relationship between a DET test. When FIG. 19 is seen, since each sample value is distributed on a straight line like FIG. 18, the magnetic symmetry (%) of the magnetoresistive effect element 4 measured by the DET test and the test measured by the QST evaluation test It can be seen that a proportional relationship is also established with the magnetic symmetry (%) of the element 5.

  As shown in FIGS. 18 and 19, it is verified that a good correlation is established between the QST evaluation test result and the DET test result. Therefore, even if it is determined whether or not it is a non-standard product based on the QST evaluation test result, the same determination result as when it is determined whether or not it is a non-standard product based on the DET test result is obtained. Non-standard products can be eliminated at an early stage in the manufacturing process.

  According to the above-described embodiment, at least one inspection element 5 having the same film configuration and shape as the magnetoresistive effect element 4 at the time of completion of the head, and the power supply to the inspection element 5 exposed on the substrate surface are provided. Since the lead electrode layer 10 is provided, the QST evaluation test can be performed for each inspection element 5 on the wafer substrate 1 that is not cut individually. Thereby, non-standard products can be found and eliminated at an early stage of the manufacturing process, and the yield in the subsequent process can be improved. In addition, it was possible to detect factors that caused non-standard products in the manufacturing process early, and to correct the manufacturing process quickly. Furthermore, it is possible to provide quick feedback when evaluating prototypes under development, and there is an advantage that development time is shortened and development efficiency is improved.

  According to the present embodiment, since the lower magnetic shield layer 2 (and the upper magnetic shield layer 9) does not exist in the region where the test element 5 and the extraction electrode layer 10 are formed, the first QST evaluation test is performed. In this case, a stable output of the test element 5 can be obtained without causing disturbance due to the lower magnetic shield layer 2. As a result, the correlation between the first QST evaluation test result and the DET test result at the final stage is well maintained, and it is determined with high accuracy whether the product is non-standard based on the QST evaluation test result. be able to.

In the above, the embodiment in which the present invention is applied to the read-only thin film magnetic head substrate H has been described. However, the present invention is a composite thin film magnetic in which an inductive head element for recording is laminated on the upper magnetic shield layer 9. It can also be applied to a head substrate. In particular, the composite type thin film magnetic head substrate has a larger number of manufacturing steps than the read-only thin film magnetic head substrate. Therefore, if a non-standard product can be found at an early stage, it is effective in improving the yield.

It is a top view which shows one Embodiment of the thin film magnetic head substrate by this invention. It is a top view which expands and shows FIG. FIG. 2 is a cross-sectional view showing the structure of the magnetoresistive element in FIG. 1 as viewed from the side facing the recording medium. It is a top view explaining the track width dimension and height dimension of the magnetoresistive effect element. FIG. 2 is a cross-sectional view showing the structure of the inspection element of FIG. 1 as viewed from the side facing the recording medium. FIG. 2 is a cross-sectional view of the structure of the inspection element in FIG. 1 as viewed from a position on the far side in the height direction from a surface facing the recording medium. It is a top view explaining the track width dimension and height dimension of the inspection element. FIG. 2 is a cross-sectional view showing one step of the method of manufacturing the thin film magnetic head substrate shown in FIG. 1 as viewed from the side facing the recording medium. FIG. 9 is a cross-sectional view showing the next step of the step shown in FIG. 8 as viewed from the side facing the recording medium. FIG. 10 is a cross-sectional view showing the next step of the step shown in FIG. 9 as viewed from the side facing the recording medium. It is a top view which shows the resist layer formed at the next process of the process shown in FIG. FIG. 12 is a cross-sectional view showing the next step of the step shown in FIG. 11 when viewed from the side facing the recording medium. FIG. 13 is a cross-sectional view showing the next step of the step shown in FIG. 12 as viewed from the track width direction, in which (a) an actual element formation area and (b) an inspection element formation area are respectively shown. FIG. 13 is a cross-sectional view showing the next step of the step shown in FIG. 12 when viewed from a position deeper in the height direction than the surface facing the recording medium. FIG. 15 is a cross-sectional view showing the next step of the step shown in FIG. 14 when viewed from a position on the far side in the height direction from the surface facing the recording medium. It is a VH curve obtained in the first QST evaluation test, and shows a case where a lower magnetic shield layer exists under the test element. It is a VH curve obtained by the first QST evaluation test, and shows a case where the lower magnetic shield layer does not exist under the test element. It is a graph which shows the relationship between a QST evaluation test and a DET test by using output voltage as a parameter. It is a graph which shows the relationship between a QST evaluation test and a DET test by using magnetic symmetry as a parameter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Lower magnetic shield layer 3 1st insulating layer 3 'Partial insulating layer 3''Whole surface insulating layer 4 Magnetoresistive element 5 Inspection element 6 Bias magnetic layer 7 Electrode layer 7a Connection part 8 2nd insulating layer 9 Upper magnetic shield Layer 10 Lead electrode layer H Thin film magnetic head substrate A Element formation area Am Actual element formation area At Inspection element formation area Dh Horizontal dicing line Dp Vertical dicing line X Track width direction Y Height direction Z Stacking direction

Claims (3)

The substrate surface is virtually divided into a plurality of elements, and a plurality of element formation areas are set side by side in at least one of the track width direction and the height direction of the magnetoresistive effect element to be formed. Setting an actual element formation area for forming a resistance effect element and at least one inspection element formation area for forming an inspection element;
A step of laminating a lower magnetic shield layer, a first insulating layer, and a magnetoresistive film on the substrate in order from the bottom, and before forming the first insulating layer, another insulating layer is formed on the substrate. Is formed on the entire surface, the actual element forming area of the other insulating layer is removed by etching, the lower magnetic shield layer is formed by plating, and the other remaining elements in the inspection element forming area are formed. Forming a partial insulating layer by an insulating layer, performing a CMP process on the upper surface of the partial insulating layer and the upper surface of the lower magnetic shield layer to planarize, and forming a first insulating layer on the planarized surface; ;
The track width dimension of the magnetoresistive effect film in the actual element forming area and the inspection element forming area is defined to be the same as the track width dimension of the magnetoresistive effect element 4 when the head is completed. Forming a bias magnetic layer and an electrode layer on both sides in the width direction ;
The height dimension of the magnetoresistive film in the actual element formation area is defined to be larger than the height dimension at the time of completion of the head, and the height dimension of the magnetoresistive film in the inspection element formation area is set to the magnetoresistance at the time of completion of the head. Defining the same height as the effect element;
Forming a second insulating layer on the magnetoresistive film and part of the electrode layer;
Forming an extraction electrode layer electrically connected to the magnetoresistive film in the inspection element formation area on the second insulation layer by electrically connecting to the electrode layer not covered with the second insulation layer; ;
An external magnetic field is applied to the magnetoresistive film in the inspection element formation area through the lead electrode layer in a state where a sense current is applied, and an electromagnetic property evaluation test is performed for each inspection element formation area on the uncut substrate. Performing the steps;
It is determined whether or not the result of the electro-magnetic characteristic test satisfies a predetermined criterion. If the criterion is satisfied, an upper magnetic shield layer is formed on the magnetoresistive film in the actual element formation area. Process;
And a step of forming an inductive head element on the upper magnetic shield layer in the real element forming area. 2. A thin film magnetic head substrate manufactured by the method of manufacturing a thin film magnetic head substrate according to claim 1, wherein the slider is a subsequent process only for a non-defective product that satisfies the predetermined criteria by performing the electromagnetic characteristic evaluation test. A sense current is passed through the actual element in the manufacturing process to perform a second electromagnetic characteristic evaluation test to determine pass / fail, and only those that are determined to be non-defective in the slider manufacturing process are included in the head gimbal assembly process in the subsequent process. A method of manufacturing a thin film magnetic head, wherein a recording medium is used as the real element and a pass / fail judgment is made in a final electromagnetic characteristic evaluation test. The method of manufacturing a thin film magnetic head substrate according to claim 2 includes a result of an electromagnetic test and a characteristic evaluation test of the thin film magnetic head substrate in advance, a second electromagnetic characteristic evaluation of the slider manufacturing process, and a final head gimbal assembly. A method of manufacturing a thin film magnetic head in which a predetermined standard is determined by performing the electromagnetic characteristics evaluation test on a thin film magnetic head substrate based on a correlation with an electromagnetic characteristics evaluation test result

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