JP5140917B2 - Charge amount evaluation element - Google Patents

Description

  The present invention relates to a structure of a charge amount evaluation element for detecting the occurrence of charging that is a cause of damage to a magnetic head element, which occurs in the process of manufacturing a magnetic head element of a magnetic disk.

  As magnetic heads become smaller and higher in density, damage due to static electricity and electrical stress frequently occurs. In the manufacturing process of the magnetic disk head, the magnetic head element itself is damaged by static electricity or electrical stress. This is one of the main causes of yield reduction with the downsizing of the magnetic head. In order to prevent this, in the assembly process, evaluation by a charged plate monitor or a surface potential meter is performed as an antistatic measure.

  A magnetic head element of a magnetic disk has a cross-sectional structure in which a conductive film, an insulating film, a magnetic film such as an MR film, etc. are laminated on a substrate.

  In the manufacturing process of the magnetic head element, various insulating films, shield films, magnetic films, etc. are formed by sputtering, patterning process by photolithography, etching process by ion milling or dry etching many times. repeat.

  In these processes, for example, an etching process by ion milling, excessive static electricity is generated, so that ions and electrons flow into the conductive electrode portion, causing damage to the element.

In the semiconductor field where the influence of static electricity is also a problem, a fuse portion made of a conductive material is provided close to the bonding pad of a semiconductor integrated circuit, and the charge induced when static electricity is applied to the bonding pad There has been proposed a method of recording an application history of static electricity by causing a fuse to break through the flow.
For the problem of damage in the manufacturing process (ion etching process) of the magnetic head element before the assembly process, there is a method of evaluating the charge amount in the process apparatus using a probe.

FIG. 10 is an explanatory diagram of this method, and is a method of measuring a current value in a process apparatus using a general Langmuir probe. A probe 201 having potential energy applied to the plasma in the chamber 200 is directly inserted, and information on the density and temperature of electrons and ions in the plasma is obtained from the current value due to the collision of the electrons 202 and ions 203. Therefore, this method does not detect the generation of excess static electricity due to direct ions. Since it was not possible to detect and judge the actual degree of damage, it was not an effective measure.
Langmuir probe http://www.kobelco.co.jp/p109/cvd/l2p.htm

  The generation of static electricity does not occur only in a specific process. With the above measures, charging and damage cannot be evaluated over the entire process of the magnetic head element manufacturing process (including the cleaning process). There was a problem that evaluation was impossible.

  The magnetic head element failure mode can be broadly divided into a mode in which an excessive current flows through the element and burns out (current mode), and a mode in which a potential difference occurs between the upper and lower shields and the element and the element is damaged due to dielectric breakdown (voltage mode). However, the conventional evaluation element for semiconductor manufacturing equipment has insufficient sensitivity (for potential difference of 5V or more) and detects a defective mode peculiar to the magnetic head element. There was a problem that could not be done. In particular, defects that cause problems with magnetic head elements are caused by a very small potential difference of 5 V or less, and it is difficult to detect them.

  The conventional method used in the semiconductor field has a detection sensitivity of at least a potential difference of 10 V or more due to its structure, and is used to detect defects occurring at 5 V or less, particularly about 1 to 3 V, which is a problem in the magnetic disk head manufacturing process. Is known to be inapplicable.

  In this way, it is possible to directly detect the amount of charge generated in the process apparatus with high sensitivity capable of detecting an electrical stress of 5 V or less, or directly detect damage to the wafer on which the magnetic head element is formed. There is a need for a charge amount evaluation technique that can be used.

  An object of the present invention is to detect static electricity or electrical stress that damages a magnetic head element in a manufacturing process.

1 Conductor having an insulating film on the surface or semiconductor insulating substrate film, two electrode pads made of a conductor, a structure for electrically connecting one of the electrode pads and the substrate, and a fuse wiring connecting the electrode pads are formed. Thus, a charge amount evaluation element is obtained. (See Figure 1)
2 In the above-described configuration, an electrical wiring different from the fuse wiring is formed between the two electrode pads (that is, two sets of similar wiring are configured) and a protective resist covering only one wiring (fuse wiring) is provided. Form. (See Figure 3)
3 On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
A plurality of unit elements each including two electrode pads made of a conductor, a structure for electrically connecting one of the electrode pads and the substrate, a fuse wiring connecting the electrode pads, and a protective resist covering the fuse wiring are provided. Furthermore, a connection pad that is a connection electrode to the outside by a conductor, a conductive pattern that connects the connection pad between the electrode pads that are electrically connected to the substrate of the unit element, and a connection pad that is connected between the other electrode pads of the unit element By providing a conductive pattern to be configured, it is configured as a charge amount evaluation element. (See Figure 4)
The above configuration is a configuration (current type) for detecting damage due to the current mode. Due to ions and electrons flowing into the electrode pads at both ends of the fuse, a potential difference is generated between the electrode pads, and a current flows through the fuse. By measuring the resistance change of the fuse caused by the heat generated at this time, the possibility of occurrence of the ESD phenomenon in the pin reversal failure mode of the MR head is detected.
The configuration 1 is the basic configuration. The configurations 2 and 3 detect a change in resistance of the fuse due to an unstable current flowing through the fuse wiring when the wiring without the protective resist is cut during the etching process.
4 On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface, two electrode pads made of a conductor are provided. One electrode pad is electrically connected to the substrate, and a gap structure is provided between the electrode pads.
5. Further, a high resistance film made of a material having a lower surface resistance than the insulating film of the underlying substrate is disposed under the gap structure of both electrode pads. As a material, a semiconductor or the like can be considered. (See Figure 2)
As described above, the configurations 4 and 5 are configurations (voltage type) for detecting damage due to the voltage mode.
The aim is to detect the ESD phenomenon in the dielectric breakdown mode of the magnetic head element due to the accumulation of electric charges in the electrically floating electrode and the breakdown of the gap. In the configuration 5, a film having a low surface resistance is arranged in the gap between the two electrode pads so that the sensitivity can be increased even when the potential difference is low.
6 claim 1 or claim 2, wherein the charge quantity evaluation device (the current type), both detect the failure mode both be provided on a substrate and a quantity of charge evaluation device according to claim 3 (voltage type) it can.
If a plurality of charge quantity evaluation elements having a size of 7 or more are formed on the substrate (see FIG. 5), the charge quantity (degree of damage) can be quantitatively determined.
8 If these charge amount evaluation elements are formed on a wafer having the same size as the magnetic disk head wafer (see FIG. 6), they can be used for adjusting the ion concentration distribution and intensity in the process apparatus. Further, by appropriately mixing the wafers for the magnetic disk head, it is possible to detect where the abnormality occurs in the magnetic head element manufacturing process and temporal variations of the process apparatus or the like.
9 At the initial stage of the process of forming the magnetic head element, in parallel with (or before) the formation of the magnetic head element, a charge amount evaluation element is formed on a part of the magnetic disk head wafer (see FIG. 7). ), It is possible to directly detect the charge amount in the manufacturing process of the magnetic head element, and hence the degree of damage.

  The present invention captures phenomena that occur during the manufacture of actual magnetic head elements, quantitatively evaluates element damage caused by static electricity and electrical stress in the wafer process, and produces magnetic head elements at a high yield. You can get guidelines to do that. That is, in the magnetic head element manufacturing process, two breakdown modes (current mode and voltage mode) unique to the magnetic head element can be accurately captured. Therefore, the process conditions can be fed back in a short period of time. As a result, the yield can be increased and the cost can be significantly reduced.

  Since it can be configured as a planar element, it is easy to manufacture. In addition, since it is compatible with the magnetic head element manufacturing process, it is possible to build a charge evaluation element in the wafer of the magnetic head element. That is, it is possible to directly evaluate electrostatic damage at the time of manufacturing the magnetic head element.

  Further, since the charge amount evaluation element is exposed on the surface, if the damage is large, the change of the element due to electrostatic damage can be observed with an optical microscope, and the number of evaluation steps can be reduced or shortened.

Structure example 1 of charge quantity evaluation element
A structural example of a fuse type (current type) will be described with reference to FIG.

  As shown in FIG. 1, two electrode pads 31 and 32 are formed on the left and right, and a fuse-shaped electric wiring 41 is formed so as to connect them. One of the electrode pads 32 is electrically connected to the silicon substrate 1 through a contact hole 5 opened in the SiO 2 insulating film 2, and the other electrode pad 31 is electrically insulated from the silicon substrate 1 by the SiO 2 insulating film 2. Has been. For example, Al is used as the fuse wiring material, the two electrode pads 31 and 32 are about 200-300 μm and 300-800 μm, and the material is Au. These are materials commonly used in the process of forming a magnetic head element. Similarly, the substrate 1 may use a conductor for a magnetic head element. Cu or Al may be used for the electrode pad.

  The operation of the current type charge amount evaluation element will be described below.

  When this charge amount evaluation element is introduced into a process chamber such as a plasma apparatus, electrons and ions flow into the two electrode pads 31 and 32. Electrons and ions that have flowed into the electrode pad 32 on the left side in the figure, which is electrically connected to the substrate 1, flow into the substrate 1 through the contact holes 5. Electrons and ions that have flowed into the right electrode pad 31 that is electrically insulated from the substrate 1 flow into the left electrode pad 32 through the fuse-like electric wiring 41, and further through the contact hole 5. Flow into. The resistance of the fuse-like electrical wiring 41 changes according to the amount of current at this time. This is because the shape and film quality change due to heat generation. Further, when an excessive current flows, the fuse-like electrical wiring 41 is cut.

  By measuring the resistance value (change) of the fuse-like electric wiring 41 through the electrode pads 31 and 32 with the probe, the amount of electrons and ions that flowed in can be observed and determined.

  It is possible to set the desired sensitivity by adjusting the length, width, thickness, material, and the like of the fuse-like electric wiring 41. Further, the sensitivity can be similarly adjusted by adjusting the shape, size, and area ratio of the left and right electrode pads.

  A procedure for manufacturing this structure will be described below.

1) Prepare a silicon substrate with SiO2 insulation film
2) Form a contact hole pattern and form an opening with hydrofluoric acid
3) About 300mm thick Al film is deposited as a fuse material by vapor deposition or sputtering.
4) A fuse pattern is formed using a resist, and a fuse shape is formed by dry etching using a chlorine-based gas.
5) Form a resist pattern for electrode pad lift-off
6) About 3000mm of Au film as electrode pad material, about 100mm of Ti film as the underlying material, deposited by vapor deposition method, sputtering method, etc.
7) The lift-off resist is removed to complete the device.
8) Conduct backside continuity treatment and protective resist formation on the fuse or one side electrode pad as necessary.

  In this way, the charge amount evaluation element having the structure shown in FIG. 1 is completed.

Structure example 2 of charge quantity evaluation element
A structural example of a gap type (voltage type) will be described with reference to FIG.

  As shown in FIG. 2, two electrode pads 31 and 32 are formed on the left and right, and an Al gap structure 33 is formed so that the distance between the pads is several μm. A high resistance Si film 6 is formed under the gap structure 33. The two electrode pads 31 and 32 are made of Au / Ti, one of the electrode pads 32 is electrically connected to the silicon substrate 1 through the contact hole 5, and the other electrode pad 31 is interposed through the SiO 2 insulating film 2. The silicon substrate 1 is electrically insulated.

  Next, the operation of the gap type charge amount evaluation element will be described.

  When this charge amount evaluation element is introduced into the process chamber, electrons and ions flow into the two electrode pads 31 and 32. Electrons and ions that have flowed into the left electrode pad 32 that is electrically connected to the substrate 1 flow into the substrate through the contact hole 5, and further flow into the ground potential through the ground, so that the potential is approximately 0V. It becomes. Further, electrons and ions that have flowed into the right electrode pad 31 that is electrically insulated from the substrate 1 are gradually accumulated and have a certain potential. Therefore, a potential difference is generated between the left electrode pad 32 and the right electrode pad 31. At this time, a current flows through the surface resistance between the minute gaps 33 formed on the high-resistance Si film 6, and the resistance between the gaps, that is, the resistance between both electrode pads changes. If the amount of electrons and ions that flowed in is large, the conductive state is finally reached. If this resistance change is measured, the potential generated in the process chamber can be observed. The desired sensitivity can be set by adjusting the gap structure portion interval, shape, material of the high-resistance Si region, resistivity, and the like. Further, the sensitivity can be similarly adjusted by adjusting the ratio of the shape, size, and size of the left and right electrode pads 31 and 32.

  A manufacturing procedure of this structure will be described.

1) Prepare a silicon substrate with SiO2.
2) A high-resistance Si layer is formed to about 2000 mm by CVD method.

  3) A high resistance Si pattern is formed using a resist, and a high resistance Si pattern shape is formed by wet etching using a nitric acid-based etchant.

  4) A contact hole pattern is formed, and an opening is formed with hydrofluoric acid.

  5) An Au film as an electrode pad material is about 3000 mm, and a Ti film as a base material is about 100 mm, formed by vapor deposition, sputtering, or the like.

  6) An electrode pad pattern is formed using a resist, and an electrode pad pattern shape is formed by wet etching using aqua regia and hydrofluoric acid.

  7) A film of about 300 mm thick is formed by vapor deposition or sputtering using Al as a material for the gap structure.

  8) A gap pattern shape is formed using a resist, and a gap structure shape is formed by dry etching using a chlorine-based gas.

9) Conducting the back surface as necessary, and forming a protective resist on the gap or one-side electrode pad In this way, the charge amount evaluation element having the structure shown in FIG. 2 is completed.

Example 3 of structure of charge amount evaluation element
In the fuse type charge amount evaluation element, a structural example in the case where a conductive wiring is provided between the left and right electrode pads in addition to the fuse-like wiring will be described.

  As shown in FIG. 3, two electrode pads are formed on the left and right, and up to the point where an Al fuse-like electrical wiring 41 is formed so as to connect them, the same as in the first embodiment (FIG. 1). Structure. In addition to this, a conductive pattern (electric wiring 2) 42 for connecting the left and right electrodes is formed, and this conductive pattern may also be Al. A protective film 7 made of resist is formed on the fuse-like wiring pattern (electric wiring 1) portion for detecting a resistance change, and the other conductive pattern (electric wiring 2) 42 is left exposed.

  The charge amount evaluation element having this shape is introduced into a process chamber of an etching process apparatus. As the etching of each material proceeds, the electrical wiring 2 is cut. It is known from experience that unstable charge transfer occurs at this moment, and this evaluation element can detect the behavior at this time.

Structure example 4 of charge quantity evaluation element
In the fuse type charge amount evaluation element, a structure example in which a plurality of electrode pads are connected to each other and have a wiring pattern shape that is electrically connected to the outside of the wafer will be described.

  As shown in FIG. 4, the structure is the same as that of the first embodiment (FIG. 1) until two electrode pads are formed on the left and right and an Al fuse is formed so as to connect them. There are a plurality of such structures, and in addition to this, conductive patterns 91 and 92 for connecting the left and right electrode pads are formed, and the conductive patterns are connected to the external connection pads 8 for electrical connection with the outside. This conductive pattern is also made of Al.

  When the charge amount evaluation element having this shape is introduced into the process chamber, the external connection pad 8 comes into contact with the earth potential restraining jig in the process apparatus and falls to the ground potential. In the etching process apparatus, the conductive pattern is cut as the etching of each material proceeds. At this moment, unstable charge transfer occurs. In this evaluation element, the behavior at this time can be detected.

Structure example 5 of charge amount evaluation element
FIG. 5 shows that the fuse-type (current-type) evaluation element and the gap-type (voltage-type) evaluation element shown in Example 1 and Example 2 are formed on the same substrate and have two defects, current mode and voltage mode. This is an example of a layout in which modes can be captured on the same substrate. (a) to (e) are fuse type elements, and (f) to (j) are gap type elements.

  Here, (a) to (c) of the fuse-type elements change the sensitivity by changing the ratio of the size of the left and right electrode pads (antenna ratio) to 1: 4, 1: 2, and 1: 1, respectively. ing. Similarly, (f) to (h) of the gap type elements are examples in which the sensitivity is changed by changing the antenna ratio. Among the fuse type elements (c) to (e), the fuse width is changed to 0.8 μm, 1.0 μm, and 0.6 μm, respectively, and the sensitivity is changed. In (j), the gap interval is changed to 1.5 μm, 2.0 μm, and 1.0 μm, respectively, and the sensitivity is changed.

  In this manner, sensitivity can be adjusted by changing the element size, shape, and material, and the magnitude of damage to the substrate can be measured.

Structural example 7 of charge quantity evaluation element
By disposing one set shown in the structural example 5 on the wafer W as shown in FIG. 6, it is possible to observe the defect occurrence distribution in the wafer plane. By appropriately mixing such an evaluation wafer with a wafer for forming a magnetic head element, it is possible to examine temporal changes in the entire manufacturing process of the magnetic head element.

  The above example has shown the element structure for investigating the process condition in wafer units. Therefore, although the example which uses a silicon | silicone was shown, the board | substrate is not restricted to this. It may be a magnetic head wafer, that is, a conductor substrate.

Structural example 7 of charge quantity evaluation element
FIG. 7 shows an example in which the one set of elements shown in the fifth embodiment is formed on the magnetic head element forming wafer W. FIG.

  The magnetic head elements are grouped into a certain number and are called row bars R. The charge amount evaluation element of the present invention is incorporated in a row bar R in which magnetic head elements are arranged, and a large number of row bars R are formed on the wafer. This makes it possible to evaluate the damage to the magnetic head element during the process in units of rover.

Needless to say, in the case of the evaluation element of any of the above embodiments, the production procedure, material, shape, dimensions, and the like are not limited to the examples shown here.
-Resistance change data An example of the fuse type detection sensitivity measurement result is shown in FIG. Destruction has been confirmed when a 1V, 50ns pulse is applied between the electrode pads, and it has been confirmed that it has sufficient sensitivity for ESD detection.

FIG. 9 shows an example of a change in resistance value when a fuse-type charge amount evaluation element is inserted into the apparatus. In all the graphs, the horizontal axis represents the resistance value before the apparatus is turned on, and the vertical axis represents the resistance value after the apparatus is turned on. (a) is an example in which no abnormal charging was observed in the process apparatus and no change was observed in the resistance of the element. Since there is no difference in resistance value before and after the introduction of the device, the graph shows a straight line. On the other hand, (b) shows an example in which a change in the resistance of the element was observed because abnormal charging was observed in the process apparatus. The resistance value is larger after the introduction than before the introduction of the device, and the resistance value showing the maximum value indicates an example in which the fuse is completely cut. In this way, various phenomena can be captured depending on the element design dimensions, such as when the resistance value changes depending on the current, and finally fusing.
“The following additional notes are disclosed with respect to the embodiments including the above Examples 1 to 7”.
[Appendix 1]
On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
Two electrode pads with conductors;
A structure for conducting the one substrate and one of the electrode pads,
And fuses wiring connecting between the electrode pads,
A protective film covering the fuse wiring;
A charge amount evaluation element having a wiring pattern different from the fuse wiring for connecting the electrode pads .
[Appendix 2]
On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
Two electrode pads with conductors;
A structure for conducting the one substrate and one of the electrode pads,
And fuses wiring connecting between the electrode pads,
A protective layer covering the fuses wires,
And a different wiring pattern and the fuses wiring connecting between the electrode pads
A plurality of unit elements;
A connection pad to be an external connection electrode by a conductor;
A conductor pattern connecting the connection pads and the electrode pads that are electrically connected to the substrate of the unit element;
A conductor pattern connecting between the other electrode pads of the unit element and the connection pads;
Charge evaluation device characterized Rukoto is composed of.
[Appendix 3]
On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
Two electrode pads with conductors;
A structure for conducting the one substrate and one of the electrode pads,
A gap structure between the electrode pads;
Under the gap structure, a film made of a material having a lower surface resistance than the insulating film is formed on the substrate.
Charge evaluation device characterized by having.
[Appendix 4]
Both the charge amount evaluation element described in appendix 1 or 2 and the charge amount evaluation element described in appendix 3 are provided on the substrate.
Charge amount evaluation element characterized by the above.
[Appendix 5]
A charge amount evaluation element according to any one of appendices 1 to 3, wherein a plurality of charge amount evaluation elements are formed on the substrate with different dimensions and shapes.
[Appendix 6]
A wafer on which the charge amount evaluation element according to appendix 1 to appendix 5 is formed.
[Appendix 7]
The charge amount evaluation element according to appendix 1 to appendix 5 is formed on the magnetic disk head wafer in parallel with the process of forming the magnetic head element.
The manufacturing method characterized by the above-mentioned.

Example of structure of current-type charging evaluation element (Example 1) Example of structure of voltage-type charging evaluation element (Example 2) Example of structure of current-type charging evaluation element (Example 3) Example of structure of current-type charging evaluation element (Example 4) Example in which a large number of charging evaluation elements are formed (Example 5) Example in which a large number of charge evaluation elements are formed on a wafer (Example 6) Example (Example 7) in which the charge evaluation element was formed on the magnetic head wafer Example of detection sensitivity data of current-type charging evaluation element Example of resistance change data of current-type charging evaluation element Example of current monitoring with Langmuir probe

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Insulating film 31, 32 Electrode pad 33 Electrode pad gap structure 4, 41 Fuse wiring 42 Electrical wiring 5 Contact hole 6 High resistance film 7 Protective resist 8 External connection pad 91, 92 Conduction pattern R Rover
W wafer

Claims (3)

On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
Two electrode pads with conductors;
A structure for electrically connecting one of the electrode pads and the substrate;
Fuse wiring connecting the electrode pads;
A protective film covering the fuse wiring;
A charge amount evaluation element having a wiring pattern different from the fuse wiring for connecting the electrode pads. On the insulating film of the substrate made of a conductor or semiconductor having an insulating film on the surface,
Two electrode pads with conductors;
A structure for electrically connecting one of the electrode pads and the substrate;
Fuse wiring connecting the electrode pads;
A protective film covering the fuse wiring;
A plurality of unit elements having a wiring pattern different from the fuse wiring connecting the electrode pads;
A connection pad to be an external connection electrode by a conductor;
A conductor pattern connecting the connection pads and the electrode pads that are electrically connected to the substrate of the unit element;
A charge amount evaluation element comprising a conductive pattern for connecting between the other electrode pads of the unit element and the connection pad. Both the charge amount evaluation element according to claim 1 and the charge amount evaluation element according to claim 2
On the substrate
Charge amount evaluation element characterized by the above.

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