JP4023455B2 - Wafer etching method and thin film magnetic head manufacturing method - Google Patents

Description

  The present invention relates to a wafer etching method and a thin film magnetic head manufacturing method.

  In general, in the wafer process of a thin film magnetic head, a film thicker than other thin films is formed by frame plating. For example, Patent Document 1 describes that the upper magnetic core is formed by frame plating.

  In the frame plating method, an unnecessary plating film is inevitably formed around the plating film to be originally formed. Therefore, this unnecessary plating film must be removed.

  Conventionally, such an unnecessary plating film is removed by etching after covering all the plating film portions that should not be removed on the wafer with a photoresist layer.

Japanese Patent Laid-Open No. 10-091919

  However, in the prior art, unnecessary plating films on the wafer are removed by etching all at once. Therefore, when the stress of the plating film is strong, the stress change on the wafer becomes very large, and the photoresist layer is not deformed. As a result, there arises a disadvantage that the necessary plating film is partially etched.

  Accordingly, an object of the present invention is to provide a method for etching a wafer and a method for manufacturing a thin film magnetic head that can reduce a change in stress during etching.

According to the present invention, in order to remove unnecessary portions by etching so that only necessary portions of the predetermined film formed on the wafer remain, the wafer is at least in the first region and a region different from the first region. divided into a plurality of regions including a certain second region, the first to form a photoresist layer covering the necessary portion and a region other than the first area having a predetermined film in the first region, the first etching After removing unnecessary portions of the predetermined film in the region, the first photoresist layer is removed, and a second photoresist layer covering at least the necessary portions of the predetermined film in the first region and the second region is formed. Etching a wafer by removing an unnecessary portion of the predetermined film in the second region by etching, and then removing the second photoresist layer. Method of manufacturing a thin film magnetic head unnecessary portions so that only the necessary portion of the formed predetermined film remains removed by etching is provided.

  According to the present invention, the wafer further includes at least a first region and a plurality of second regions in order to remove unnecessary portions by etching so that only necessary portions of the predetermined film formed on the wafer remain. A first photoresist layer is formed which is divided into regions and covers a necessary portion of the predetermined film in the first region and a region other than the first region, and an unnecessary portion of the predetermined film in the first region is etched. After the removal, the first photoresist layer is removed, a second photoresist layer is formed to cover a necessary portion of the predetermined film in the second region and a region other than the second region, and the second photoresist layer is formed by etching. Wafer etching method for removing second photoresist layer after removing unnecessary portion of predetermined film in region, and necessary portion of predetermined film formed on wafer by this etching method Method of manufacturing a thin film magnetic head for removing unnecessary portions so that only the left by etching is provided.

  The first photoresist layer covers the necessary portion of the predetermined film in the first region and the region other than the first region, and unnecessary portions of the predetermined film in the first region are removed by etching. The photoresist layer is removed. Next, at least a necessary portion of the predetermined film in the plurality of regions is covered with the second photoresist layer, or a necessary portion of the predetermined film in the second region and the region other than the second region are covered, and the second region After the unnecessary portion of the predetermined film is removed by etching, the second photoresist layer is removed. In this way, the unnecessary portion of the predetermined film is not etched and removed all at once over the entire wafer, but the wafer is divided into a plurality of regions and unnecessary portions of the predetermined film are separately etched and removed for each region. Therefore, the etching area at each time is reduced accordingly, the change in the generated stress is reduced, and the deformation of the photoresist layer due to the stress is reduced. Moreover, since the photoresist layer is remade each time and unnecessary portions are removed by etching, for example, even if the photoresist layer is slightly deformed by the first etching, it is peeled off and new etching is performed in the second and subsequent etchings. Since the photoresist layer is formed, it is possible to reliably prevent the occurrence of an inconvenience that a necessary portion is etched due to the deformation of the photoresist layer.

  It is preferable that the plurality of regions include only the first region and the second region, or include the first region and the second region and at least one other region. If the wafer is divided into more regions and etched, the generated stress is reduced accordingly.

  It is preferable that each of the plurality of regions is distributed substantially symmetrically with respect to the center point of the wafer. In many cases, the etching solution is dropped on the center of the rotating wafer and spreads to the periphery. Therefore, if the point is symmetrical with respect to the center point, the etching of each region is performed equally, and the generated stress is applied to the wafer. It is balanced and minimized as a whole.

  It is also preferable to remove the second photoresist layer, form a third photoresist layer that covers a necessary portion of the predetermined film in the plurality of regions, perform etching, and then remove the third photoresist layer. . As a result, the altered film remaining on the surface can be completely removed.

  The predetermined film is preferably a plating film formed by a frame plating method.

  It is also preferable that the wafer is a wafer for forming a thin film magnetic head, and the predetermined film is an upper magnetic pole layer or a lower magnetic pole layer of the thin film magnetic head.

  It is also preferable that the etching is wet etching.

  It is preferable that the wet etching is performed by repeatedly applying an etching solution to the wafer and cleaning the wafer with pure water a plurality of times. Each etching process itself is also performed in this manner, so that the etching progresses slowly and the generated stress becomes smaller.

  When the predetermined film is a film made of a material having a strong stress, such as a CoFe film or a NiFeCo film, the effect of the present invention becomes more remarkable.

  According to the present invention, since the wafer is divided into a plurality of regions and unnecessary portions of the predetermined film are separately etched away for each region, the etching area of each time is reduced accordingly, and the change in the generated stress is reduced. As it becomes smaller, the deformation of the photoresist layer due to the stress becomes smaller. In addition, since the photoresist layer is remade each time and unnecessary portions are removed by etching, it is possible to reliably prevent the occurrence of inconvenience that the required portions are etched due to the deformation of the photoresist layer.

  1 and 2 are a cross-sectional view and a plan view for schematically explaining each step of the frame plating method and an etching removal step of an unnecessary portion of the plating film.

  First, as shown in FIG. 1A, an electrode film 11 which is a base film for plating is laminated on an insulating layer 10 on which a plating film is to be formed by a sputtering method or the like.

  Next, as shown in FIG. 1B, a photoresist layer 12 for frame plating is formed. The photoresist layer 12 is formed by applying a photoresist material on the electrode film 11 to form a photoresist film, exposing the photoresist film through a photomask, and developing it to form a frame. A general method for obtaining a pattern is applicable.

  Next, as shown in FIG. 1C, a predetermined film, that is, a plating film 13 is deposited by electrolytic plating. Here, 13a is a necessary part of the plating film 13, and 13b is an unnecessary part to be removed by etching.

  Next, as shown in FIG. 1 (D), the photoresist layer 12 is peeled off and removed, and as shown in FIG. 2 (A), the portion of the electrode film 11 where the photoresist layer 12 was present by milling is removed. Remove.

  Thereafter, as shown in FIG. 2B, a photoresist layer 14 is formed so as to cover only the necessary portion 13a of the plating film 13. The photoresist layer 14 is formed by applying a photoresist material on the plating film 13 to form a photoresist film, exposing the photoresist film through a photomask, and developing the desired pattern. A general method of obtaining can be applied.

  Next, as shown in FIG. 2C, the unnecessary portion 13b of the plating film 13 that is not covered with the photoresist layer 14 is dissolved and removed by wet etching.

  Thereafter, as shown in FIG. 2D, the photoresist layer 14 is peeled and removed to obtain the plating film 13 in which only the necessary portion 13a remains.

  In the present invention, the unnecessary portion 13b of the plating film 13 is not etched and removed all at once over the entire wafer, but the wafer is divided into a plurality of regions and the unnecessary portion 13b is removed by etching for each region. Moreover, the photoresist layer is recreated every time the etching is performed. Hereinafter, this etching method of the present invention will be described in detail.

  FIG. 3 is a plan view of a wafer for explaining steps in an embodiment of a conventional etching method and a wafer etching method of the present invention, and FIG. 4 is a flowchart showing the flow of each step.

  As shown in FIG. 3A, in the conventional etching method, only the necessary portion 31a of the predetermined film 31 is covered with the photoresist layer 32 over the entire wafer 30, and the unnecessary portion 31b of the predetermined film 31 is etched at once. It was removed.

  On the other hand, in this embodiment of the present invention, as shown in FIG. 3B, the wafer 30 is divided into a plurality of regions, in this case, the first region 30a and the second region 30b, The first photoresist layer 32 is formed so as to cover only the necessary portion 31a of the predetermined film in the first region 30a and to cover the entire region including unnecessary portions in the second region 30b (FIG. 4). Step S1).

  Next, wet etching is performed by dropping the etchant (etchant) onto the center of the wafer 30 while rotating the wafer 30 or immersing the wafer 30 in the etchant (step S2 in FIG. 4). As a result, as shown in FIG. 3C, in the first region 30a, the unnecessary portion 31b of the predetermined film is removed, and only the necessary portion 31a remains. Of course, all of the predetermined film remains in the second region 30b.

  The wet etching process is performed by applying an etching solution to the wafer 30 by the above-described method to perform etching, and then cleaning the wafer with pure water. Etching may be performed by applying an etching solution and cleaning with pure one cycle. However, if etching is performed repeatedly for a plurality of cycles, the etching proceeds slowly, so that stress generated on the wafer is reduced. More desirable.

  Note that each of the first region 30 a and the second region 30 b is desirably set so as to be distributed approximately in point symmetry with respect to the center of the wafer 30. When etching is performed by dropping the etching solution onto the center of the rotating wafer, the etching solution spreads from the center to the periphery. Therefore, if the point is symmetrical with respect to the center point, etching of each region is performed uniformly. . Furthermore, since etching is performed for each point-symmetric region with respect to the center point, the generated stress is balanced and minimized over the entire wafer.

  Next, the first photoresist layer 32 is peeled and removed (step S3 in FIG. 4).

  Next, as shown in FIG. 3D, the second photoresist layer 33 is formed so as to cover only the necessary portion 31a of the predetermined film in both the first region 30a and the second region 30b (see FIG. 3D). Step S4 in FIG.

  Next, wet etching is performed by dropping the etching solution onto the central portion of the wafer 30 while rotating the wafer 30 or by immersing the wafer 30 in the etching solution (step S5 in FIG. 4). Thereby, as shown in FIG. 3E, the unnecessary portion 31b of the predetermined film is removed also in the second region 30b, and only the necessary portion 31a remains. Of course, only the necessary portion 31a of the predetermined film remains as it is in the first region 30a.

  Next, the second photoresist layer 33 is peeled and removed (step S6 in FIG. 4). Thereby, a predetermined film in which only the necessary portion 31a remains over the entire wafer 30 is obtained.

  Although the etching process may be terminated in this state, it is preferable to perform the etching again in order to completely remove the deteriorated layer and contaminants adhering to the wafer surface. In this etching, a third photoresist layer is formed so as to cover only the necessary portion 31a of the predetermined film over the entire wafer (step S7 in FIG. 4), and then wet etching is performed (step S8 in FIG. 4). Thereafter, the third photoresist layer is peeled and removed (step S9 in FIG. 4).

  According to the embodiment described above, the wafer 30 is divided into the first region 30a and the second region 30b, and each of these regions is etched separately, so that the area of each etching is reduced accordingly. The change in the generated stress is reduced and the deformation of the photoresist layer due to the stress is reduced. Moreover, since the photoresist layer is remade each time and unnecessary portions are removed by etching, for example, even if the first photoresist layer 32 is slightly deformed by the first etching, this is removed and the second etching is performed. Since a new second photoresist layer 33 is formed, there is no inconvenience that the first photoresist layer 32 is deformed to etch a necessary portion.

  FIG. 5 is a plan view of a wafer for explaining steps in another embodiment of the wafer etching method of the present invention, and FIG. 6 is a flowchart showing the flow of each step.

  As shown in FIG. 5A, the wafer 50 is divided into a plurality of regions, in this case, a first region 50a and a second region 50b. In the first region 50a, a necessary portion 51a of a predetermined film is provided. The first photoresist layer 52 is formed so as to cover only all of the second region 50b including unnecessary portions (step S11 in FIG. 6).

  Next, wet etching is performed by dropping the etching solution onto the central portion of the wafer 50 while rotating the wafer 50 or immersing the wafer 50 in the etching solution (step S12 in FIG. 6). As a result, as shown in FIG. 5B, in the first region 50a, the unnecessary portion 51b of the predetermined film is removed, and only the necessary portion 51a remains. Of course, all of the predetermined film remains in the second region 50b.

  The wet etching process is performed by applying an etching solution to the wafer 50 by the above-described method to perform etching, and then cleaning the wafer with pure water. Etching may be performed by applying an etching solution and cleaning with pure one cycle. However, if etching is performed repeatedly for a plurality of cycles, the etching proceeds slowly, so that stress generated on the wafer is reduced. More desirable.

  Note that each of the first region 50 a and the second region 50 b is desirably set so as to be distributed substantially symmetrically with respect to the center of the wafer 50. When etching is performed by dropping the etching solution onto the center of the rotating wafer, the etching solution spreads from the center to the periphery. Therefore, if the point is symmetrical with respect to the center point, etching of each region is performed uniformly. . Furthermore, since etching is performed for each point-symmetric region with respect to the center point, the generated stress is balanced and minimized over the entire wafer.

  Next, the first photoresist layer 52 is peeled and removed (step S13 in FIG. 6).

  Next, as shown in FIG. 5C, the second region 50b covers only the necessary portion 51a of the predetermined film, and the first region 50a covers the entire portion including unnecessary portions. The photoresist layer 53 is formed (step S14 in FIG. 6).

  Next, wet etching is performed by dropping the etching solution onto the center of the wafer 50 while rotating the wafer 50 or immersing the wafer 50 in the etching solution (step S15 in FIG. 6). As a result, as shown in FIG. 5D, also in the second region 50b, the unnecessary portion 51b of the predetermined film is removed, and only the necessary portion 51a remains. Of course, only the necessary portion 51a of the predetermined film remains as it is in the first region 50a.

  Next, the second photoresist layer 53 is peeled and removed (step S16 in FIG. 6). Thereby, a predetermined film in which only the necessary portion 51a remains over the entire wafer 50 is obtained.

  Although the etching process may be terminated in this state, it is preferable to perform the etching again in order to completely remove the deteriorated layer and contaminants adhering to the wafer surface. In this etching, a third photoresist layer is formed so as to cover only the necessary portion 51a of the predetermined film over the entire wafer (step S17 in FIG. 6), and then wet etching is performed (step S18 in FIG. 6). Thereafter, the third photoresist layer is peeled and removed (step S19 in FIG. 6).

  According to the embodiment described above, the wafer 50 is divided into the first region 50a and the second region 50b, and each of these regions is etched separately, so that the area of each etching is reduced accordingly. The change in the generated stress is reduced and the deformation of the photoresist layer due to the stress is reduced. Moreover, since the photoresist layer is recreated each time and unnecessary portions are removed by etching, even if the first photoresist layer 52 is slightly deformed by the first etching, for example, this is peeled off and the second etching is performed. Since a new second photoresist layer 53 is formed, there is no inconvenience that the first photoresist layer 52 is etched to the necessary portion due to the deformation of the first photoresist layer 52.

  Next, a method for manufacturing a thin film magnetic head, which is used when the upper magnetic pole layer of the thin film magnetic head is formed by the etching method described above, will be described.

  7 and 8 are cross-sectional views showing each step in the method of manufacturing a thin film magnetic head using the etching method of FIG. 3 or FIG. 5 when forming the upper magnetic pole layer of the thin film magnetic head from the air bearing surface (ABS) direction. FIG. 9 is a cross-sectional view of the thin film magnetic head in a stage perpendicular to the ABS at the stage where the top pole layer is formed.

  First, an MR read head element portion is formed by sequentially laminating a lower shield layer 71, an upper and lower shield gap layer 72, a magnetoresistive effect (MR) layer 73, and an upper shield layer 74 on a wafer covered with an insulating layer 70. Then, an inductive write head element portion is formed thereon via an insulating layer 75. A known process can be applied as this manufacturing process.

  The inductive write head element portion is manufactured as follows. First, the lower magnetic pole layer 76 is formed through the insulating layer 75, and the insulating layer 78 is laminated thereon and on the insulating layer 77 around the element. Next, although not shown in FIGS. 7 and 8, the coil conductor 83 (FIG. 9) and the insulating layer 84 (FIG. 9) surrounding the coil conductor 83 are formed on the insulating layer 78. This state is shown in FIG.

  Next, as illustrated in FIG. 7B, an electrode film 79 which is a base film for plating is stacked over the insulating layer 78 by a sputtering method or the like. In this example, a two-layer electrode film is used.

  Next, as shown in FIG. 7C, a frame plating photoresist layer 80 is formed on the electrode film 79. As a method for forming the photoresist layer 80, a photoresist material such as a novolak positive resist material is applied on the electrode film 79 to form a photoresist film, and the photoresist film is exposed through a photomask. A known method for obtaining a frame-like pattern by developing can be applied.

  Next, as shown in FIG. 7D, a magnetic film such as a NiFe film, a CoFe film, or a NiFeCo film for the upper magnetic pole layer is deposited by electrolytic plating. Since the frame plating method is used, as the magnetic film, a portion 81a necessary as the upper magnetic pole layer and an unnecessary portion 81b to be removed by etching are formed.

  Next, as shown in FIG. 7E, the photoresist layer 80 is peeled and removed, and as shown in FIG. 8A, the electrode film 79 in the frame portion where the photoresist layer 80 was present by milling. Remove.

  Next, as shown in FIG. 8B, a photoresist layer 82 is formed so as to cover only the necessary portion 81a of the magnetic film. As for the method of forming this photoresist layer 82, for example, a photoresist film such as a novolak positive resist material is applied to form a photoresist film, and this photoresist film is exposed through a photomask and developed. A known method for obtaining a desired pattern can be applied.

  Next, as shown in FIG. 8C, the unnecessary portion 81b of the magnetic film not covered with the photoresist layer 82 is dissolved and removed by wet etching.

  Next, as shown in FIG. 8D, the photoresist layer 82 is peeled and removed.

  In the case where the formation of the photoresist layer 82 (FIG. 8B), wet etching (FIG. 8C), and removal of the photoresist layer 82 (FIG. 8D) are performed, in the present invention, As in the embodiment of FIG. 3 or FIG. 5, the wafer is divided into a plurality of regions, and a photoresist layer is formed in each region, and etching is performed separately. Since the etching is performed for each region, the area of each etching is correspondingly reduced, the change in the generated stress is reduced, and the deformation of the photoresist layer due to the stress is reduced. In addition, since the photoresist layer is remade each time and unnecessary portions are removed by etching, there is no inconvenience that the required portions are etched due to the deformation of the photoresist layer. Among the magnetic films, especially the CoFe film and the NiFeCo film have a strong stress, so that it is very effective to perform the etching in a divided manner.

  Thereafter, as shown in FIG. 8E, the remaining portion of the electrode film 79 is removed by milling.

  FIG. 9 shows the thin film magnetic head in this state. In the figure, reference numeral 85 denotes a lead conductor layer that is electrically connected to the MR layer 73.

  The above description relates to the formation of the upper magnetic pole layer of the thin film magnetic head, but the same etching method is used when forming the lower magnetic pole layer and other magnetic layers or when forming a metal layer other than the magnetic layer. It is clear that it may be applied.

  In the embodiment described above, the wafer is divided into two regions, the first region and the second region, and etched separately. However, the wafer is divided into three or more regions and etched separately. Obviously it is okay. As the number of divided areas increases, the stress generated accordingly decreases.

  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.

It is sectional drawing and a top view for demonstrating roughly each process of a frame plating method, and the etching removal process of the unnecessary part of a plating film. It is sectional drawing and a top view for demonstrating roughly each process of a frame plating method, and the etching removal process of the unnecessary part of a plating film. It is a top view of the wafer for demonstrating the process in one Embodiment of the conventional etching method and the etching method of the wafer of this invention. It is a flowchart which shows the flow of each process in embodiment of FIG. It is a top view of the wafer for demonstrating the process in other embodiment of the etching method of the wafer of this invention. It is a flowchart which shows the flow of each process in embodiment of FIG. FIG. 6 is a cross-sectional view of each step in the method of manufacturing a thin film magnetic head used when forming the upper magnetic pole layer of the thin film magnetic head by the etching method of FIG. 3 or FIG. 5 when viewed from the ABS direction. FIG. 6 is a cross-sectional view of each step in the method of manufacturing a thin film magnetic head used when forming the upper magnetic pole layer of the thin film magnetic head by the etching method of FIG. 3 or FIG. 5 when viewed from the ABS direction. 2 is a cross-sectional view of a thin film magnetic head at a stage where an upper magnetic pole layer is formed, taken along a plane perpendicular to ABS. FIG.

Explanation of symbols

10, 70, 75, 77, 78, 84 Insulating layer 11, 79 Electrode film 12, 14, 80, 82 Photoresist layer 13 Plating film 13a, 31a, 81a Necessary part 13b, 31b, 81b Unnecessary part 30, 50 Wafer 30a, 50a First region 30b, 40b Second region 31, 51 Predetermined film 32, 52 First photoresist layer 33, 53 Second photoresist layer 71 Lower shield layer 72 Upper and lower shield gap layer 73 MR Layer 74 Upper shield layer 76 Lower pole layer 83 Coil conductor 85 Lead conductor layer

Claims (15)

An etching method for removing unnecessary portions by etching so that only a necessary portion of a predetermined film formed on a wafer remains, wherein the wafer is at least a first region and a region different from the first region . A first photoresist layer is formed which covers a necessary portion of the predetermined film in the first region and a region other than the first region, and is etched to form the first photoresist layer. After removing unnecessary portions of the predetermined film in one region, the first photoresist layer is removed, and a second portion covering at least the necessary portions of the predetermined film in the first region and the second region is removed. A wafer comprising: forming a photoresist layer; removing unnecessary portions of the predetermined film in the second region by etching; and removing the second photoresist layer. Etching method.   An etching method for removing an unnecessary portion by etching so that only a necessary portion of a predetermined film formed on a wafer remains, wherein the wafer is divided into a plurality of regions including at least a first region and a second region. Forming a first photoresist layer covering a necessary portion of the predetermined film in the first region and a region other than the first region, and unnecessary portions of the predetermined film in the first region by etching. And removing the first photoresist layer to form a second photoresist layer covering a necessary portion of the predetermined film in the second region and a region other than the second region, A method for etching a wafer, comprising removing an unnecessary portion of the predetermined film in the second region by etching and then removing the second photoresist layer.   The method according to claim 1, wherein the plurality of regions include only the first region and the second region.   The method according to claim 1, wherein the plurality of regions include the first region, the second region, and at least one other region.   5. The method according to claim 1, wherein each of the plurality of regions is distributed substantially in a point symmetry with respect to a center point of the wafer.   After removing the second photoresist layer, a third photoresist layer is formed to cover a necessary portion of the predetermined film in the plurality of regions, and after etching, the third photoresist layer is removed. The method according to any one of claims 1 to 5, characterized in that:   The method according to claim 1, wherein the predetermined film is a plating film formed by a frame plating method.   8. The method according to claim 1, wherein the wafer is a wafer for forming a thin film magnetic head, and the predetermined film is an upper magnetic pole layer of the thin film magnetic head.   9. The method according to claim 1, wherein the wafer is a wafer for forming a thin film magnetic head, and the predetermined film is a lower magnetic pole layer of the thin film magnetic head.   The method according to claim 1, wherein the etching is wet etching.   The method according to claim 10, wherein the wet etching is performed by repeatedly applying an etching solution to the wafer and cleaning the wafer with pure water a plurality of times.   The method according to any one of claims 1 to 11, wherein the predetermined film is made of a film made of a material having a high stress.   The method according to claim 12, wherein the film made of a material having a high stress is a CoFe film.   The method according to claim 12, wherein the film made of a material having a high stress is a NiFeCo film. 15. A method of manufacturing a thin film magnetic head, wherein an unnecessary portion is removed by etching so that only a necessary portion of a predetermined film formed on a wafer remains by the etching method according to claim 1. Method.

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