JP2011154751A - Processing amount detection method, processing amount detection device and workpiece - Google Patents

Abstract

【Task】
Provided are a processing amount detection method, a processing amount detection device, and a workpiece that detect a polishing amount of a processing amount detection element (for example, a magnetic head) without increasing the detection circuit scale.
[Solution]
A step of inputting an input signal to one terminal of the bridge circuit of a workpiece including a bridge circuit having an element having a known impedance value and an element having an unknown impedance value; and a terminal at the position of the bridge circuit. Detecting the output signal from the other terminal at a position opposite to the terminal, the input signal, the output signal, and the impedance value of the known element, and the impedance value of the unknown element and the workpiece A processing amount detection method comprising: calculating a processing end point.
[Selection] Figure 1

Description

  The present invention relates to a processing amount detection method, a processing amount detection device, and a workpiece to detect a polishing amount without increasing a detection circuit scale.

  In recent years, along with the progress of an advanced information society, miniaturization of electronic devices and higher recording density of magnetic disk devices (HDDs) are progressing. In order to realize a processing technique that meets such demands for miniaturization and high recording density, higher precision processing is required in the manufacturing process.

  For example, regarding the HDD magnetic head, in order to realize a high recording density, it is necessary to reduce the area of 1 bit on the magnetic disk, and accordingly, it is necessary to reduce the reproducing and recording element size.

  In the air bearing surface polishing process, which is one of the manufacturing processes of the magnetic head, a polishing amount whose resistance value changes according to the polishing amount embedded in the magnetic head in order to control the height of the MR (Magneto Resistive) film of the reproducing element. The resistance value of the sensing element (electric wrapping guide: ELG) is detected to control the pressing force to the polishing surface plate. For this reason, the terminal of the substrate connected to the polishing controller and the terminal of the ELG are usually connected by a wire (wire bonding process). As a processing method for driving and controlling the polishing surface plate while detecting the resistance value of the ELG, “a method of processing a bar which is a long member including at least one magnetic head slider each formed with a thin film magnetic head element”. A first polishing step of pressing the bar against the first polishing plate without using an elastic member to polish a predetermined surface of the bar; and the bar or a single piece cut out from the bar. A second polishing step of pressing the magnetic head slide against the second polishing plate using an elastic member to further polish the surface polished by the first polishing step, and at least the second In the polishing step, it changes according to the polishing amount of the bar or the single magnetic head slider, and is based on the resistance value of the resistance film formed on the bar or the single magnetic head slider. Method for processing a magnetic head slider being characterized in that to perform the polishing control based on fed back information. "Is disclosed in Patent Document 1 (JP 2001-101634, JP-claim 1 and 2).

  Further, as a manufacturing method of the magnetic head, “at least a magnetic thin film, an electric insulating film, and an electric conductor film are deposited in a predetermined order in the thickness direction, and an intermediate having a magnetic short-circuit portion at the tip of a magnetic gap regulating film of a predetermined length In the thin film magnetic head, a thin film magnetic head having a specific shape is formed and then the tip of the thin film magnetic head is polished to finish to a predetermined gap depth. Detecting means for measuring the impedance exhibited by the winding while supplying a DC bias current having a predetermined value including a zero value, and a change width of the impedance when the DC bias current value is changed in a predetermined mode. And determining means for generating a control signal that detects that the ratio has been reduced to the ratio of the above-mentioned ratio, and the end of the polishing process is controlled by this control signal. Method of manufacturing a thin film magnetic head is characterized in that the. "Is disclosed in Patent Document 2 (JP-62-65221, JP-claim 1).

JP 2001-101634 A JP-A-62-65221

  However, in the magnetic head manufacturing method (polishing end point detection method) disclosed in Patent Document 2, the processing amount is detected by one bridge circuit using three known impedances for one detection element. . For this reason, one detection circuit is required for detecting the polishing end point of one magnetic head, and as described in Patent Document 1, in order to control polishing of a row bar composed of a large number of magnetic heads, a magnetic element that performs impedance detection is used. The number of detection circuits is the same as the number of heads, and an increase in the detection circuit scale is a problem.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

  (1) a step of inputting an input signal to one terminal of the bridge circuit of a workpiece including a bridge circuit having an element having a known impedance value and an element having an unknown impedance value; Detecting an output signal from another terminal at a position opposite to the terminal at the position, and based on the input signal, the output signal, and the impedance value of the known element, the impedance value of the unknown element and the And a step of calculating a processing end point of the workpiece.

  (2) The machining amount detection method according to (1), wherein in the step of calculating, Vout = ((Z3 / (Z1 + Z3)) − (Z4 / (Z2 + Z4))) Vin (where Vout is an output signal, Machining amount detection characterized in that Vin is an input signal, Z3 and Z4 are impedance values of elements whose impedance values are known, and Z1 and Z2 are impedance values of elements whose impedance values are unknown) Is the method.

  (3) The processing amount detection method according to (1) or (2), wherein in the calculation step, impedance values and processing end points of a plurality of unknown elements are calculated for one bridge circuit. Is a processing amount detection method characterized by

  According to the invention disclosed in the present application, it is possible to provide a processing amount detection method, a processing amount detection device, and a workpiece that detect the polishing amount of a processing amount detection element (for example, a magnetic head) without increasing the detection circuit scale. Can do.

It is a circuit block diagram of the processing amount detection apparatus which concerns on this invention. It is a figure which shows the impedance change by the process of two to-be-processed objects processed by the processing amount detection apparatus which concerns on this invention. It is a figure which shows the relationship between the output voltage detected by the bridge circuit of the workpiece processed by the processing amount detection apparatus based on this invention, and processing amount. It is a block diagram of the Example of the to-be-processed object which concerns on this invention. It is a block diagram of the modification of the to-be-processed object which concerns on this invention. It is a block diagram of the modification of the to-be-processed object which concerns on this invention. It is a block diagram of the modification of the to-be-processed object which concerns on this invention. It is a block diagram of the modification of the to-be-processed object which concerns on this invention. It is a block diagram of the modification of the to-be-processed object which concerns on this invention. It is a graph which shows the frequency characteristic of the real part and imaginary part of impedance Zi at the time of comprising one side of the workpiece bridge circuit based on this invention as shown in FIG. It is a block diagram of the to-be-processed object which concerns on this invention. It is a figure which shows the structural example of the processing amount detection element of the to-be-processed object which concerns on this invention. It is a figure which shows the structural example of the processing amount detection element of the to-be-processed object which concerns on this invention. It is a figure which shows the structural example of the processing amount detection element of the to-be-processed object which concerns on this invention. It is a block diagram of the Example of the processing amount detection apparatus which concerns on this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

  Hereinafter, as an example of a processing amount detection method of the present invention and a processing apparatus including a processing amount detector using the processing detection method, a polishing amount detection method and a polishing amount detection using the polishing amount detection method will be described. Although a vessel and a polishing apparatus will be described, the present invention is not limited to this.

  An example of an embodiment of a processing amount detection apparatus according to the present invention will be described with reference to FIG. FIG. 1 is a circuit configuration diagram of a machining amount detection apparatus according to the present invention.

  A workpiece 5 to be processed by the processing amount detection device shown in FIG. 1 includes a first processing amount detection element 1 and a second processing amount detection element 2. Here, the impedance of the first machining amount detection element 1 is Z1, and the impedance of the second machining amount detection element 2 is Z2. The values of the impedances Z1 and Z2 change with processing, and the amount of change in impedance due to processing is also different from each other.

  Further, a bridge circuit is used for detecting these impedances Z1 and Z2, and the impedances Z1 and Z2 are connected to at least two of the four sides of the bridge circuit. An impedance adjustment element 3 (impedance is Z3) and an impedance adjustment element 4 (impedance is Z4) whose impedance values are known are connected to the remaining sides. As shown in FIG. 1, the input signal source 6 is connected to the terminals a and b of the bridge circuit, and the detection circuit unit 8 detects the output voltage 7 generated between the terminals c and d determined by the impedance of the bridge circuit. Thus, the processing amount and the processing end point are calculated.

Here, when the input voltage by the input signal source 6 of the bridge circuit is Vin and the output voltage 7 is Vout, the relationship shown in the following equation is established.

  FIG. 2 is a diagram showing impedance changes due to processing of two workpieces to be processed by the processing amount detection device according to the present invention, and FIG. 3 is a diagram of the workpiece processed by the processing amount detection device according to the present invention. It is a figure which shows the relationship between the output voltage detected by a bridge circuit, and the amount of processing.

  2 and 3 indicate the machining start 10 and the machining end point 11 as machining amounts, the vertical axis in FIG. 2 represents the absolute value of the impedance, and the vertical axis in FIG. 3 represents the absolute value of the output voltage.

  For example, when the impedance values Z3 and Z4 of the two impedance adjustment elements 3 and 4 are known, the impedances Z1 and Z2 of the two machining amount detection elements 1 and 2 have different amounts of change due to machining as shown in FIG. When Ztarget having the same impedance at the processing end point 11 or Z1Z4 = Z2Z3, the output voltage | Vout | becomes smaller from the processing start 10 to the processing end point 11 as shown in FIG. The value Vtarget or zero. The amount of change in | Vout | is determined by the amount of change in impedances Z1 and Z2 due to processing. If this output voltage | Vout | is detected, the relationship between Z1 and Z2 can be obtained from (Equation 1).

  Since Z1 and Z2 at the processing end point 11 have the same impedance Ztarget, or Z1Z4 = Z2Z3, the values of Z1 and Z2 can be obtained from this relationship, and the processing amount and processing end point can be calculated.

  Examples of the configuration of unknown impedance Z1 or Z2 (hereinafter referred to as Zi, where i = 1, 2) connected to one side of the bridge circuit of the workpiece according to the present invention are shown in FIGS. According to the present invention, the impedance Zi can be constituted by various passive circuit elements.

(1) FIG. 4 is a configuration diagram in the case where the impedance Zi12 is configured by only the resistor Ri13 that changes due to processing. At this time, the impedance Zi12 can be expressed by the following equation.

(2) FIG. 5 is a configuration diagram in the case where the impedance Zi12 is configured by a capacitor Ci14 that changes by processing. At this time, the impedance Zi12 can be expressed by the following equation.

(3) FIG. 6 is a configuration diagram in the case where the impedance Zi12 is constituted by a resistor Ri13 whose capacitance is changed by processing and a capacitor C15. At this time, the impedance Zi12 can be expressed by the following equation.

  In this case, for example, by forming one electrode of the resistor Ri13 and the capacitor C15 in the workpiece and providing the other electrode of the capacitor C15 on the detection sensor, the change of the resistor Ri13 is caused by electric field coupling of the capacitor C15. It becomes possible to detect without contact.

(4) FIG. 7 is a configuration diagram in the case where the impedance Zi12 is configured by a capacitor Ci14 whose inductance Zi12 is changed by processing, and inductors L1 (17) and L2 (18). At this time, the impedance Zi12 can be expressed by the following equation.

  In this case, for example, when the primary-side inductor L1 (17) is formed on the detection sensor and the secondary-side inductor L2 (18) is formed in the workpiece, the capacitance Ci14 that changes due to machining via electromagnetic coupling of the inductor pair. Can be detected.

(5) FIG. 8 shows an example in which Zi12 is composed of a resistor Ri13 that changes due to processing and inductors L1 (17) and L2 (18). At this time, the impedance Zi12 can be expressed by the following equation.

  In this case, for example, when the primary-side inductor L1 (17) is formed on the detection sensor and the secondary-side inductor L2 (18) is formed in the workpiece, the resistance Ri13 that changes due to machining via electromagnetic coupling of the inductor pair. Can be detected in a non-contact manner.

  (6) FIG. 9 shows an example in which the capacitor C19 is connected to the circuit shown in FIG. 8 in parallel with the primary inductor L1 (17). In this case, the capacitor C19 and the primary side (detection sensor side) inductor L1 (17) constitute a resonator, and the influence of the imaginary part of (Equation 6) becomes small at the resonance frequency, and the real part is dominant. It becomes.

  FIG. 10 is a graph showing frequency characteristics of the real part 20 and the imaginary part 21 of the impedance Zi when one side of the workpiece bridge circuit according to the present invention is configured as shown in FIG. It can be seen that the imaginary part 21 is almost zero. Therefore, in the present embodiment, it is possible to increase the detection sensitivity of the resistor Ri13 that changes due to processing by inserting the capacitor C19.

  Note that the configuration of the impedance Zi of the machining amount detection element in the second embodiment of the present invention is not limited to the example described above, and the user can have an arbitrary circuit configuration according to the application.

  FIG. 11 is a configuration diagram of a workpiece according to the present invention, and FIGS. 12 to 14 are diagrams showing a structure example of a workpiece amount detecting element of the workpiece according to the present invention.

  In FIG. 11, the workpiece 5 is disposed on a polishing surface plate 53, and includes a first processing amount detection element and a second processing amount detection element. A structure 30 of the processing amount detection element 1 and a structure 31 of the processing amount detection element 2 are shown in the configuration diagrams in which the first processing amount detection element and the second processing amount detection element are enlarged.

  As described above, the impedances Z1 and Z2 of the two machining amount detection elements in the present invention are characterized in that the amount of change due to machining is different, and the first machining amount detection element disposed in the workpiece 5 shown in FIG. The structures of the 30 and the second machining amount detection element 31 are different as shown in FIGS.

  For example, FIG. 12 compares the height of the first processing amount detection element 30 and the second processing amount detection element 31 and processes the processing amount 38 from the processing start point 35 to the processing end point 34. Think about the case. At this time, the inside of the processing amount detection elements 30 and 31 is constituted by the conductive film 32 and the outside is constituted by the electrodes, respectively. The widths of the processing amount detection element 1 and the processing amount detection element 2 at the processing end point are 37 and 40, respectively. It is. Further, the lengths of the processing amount detection element 1 and the processing amount detection element 2 at the processing end point are 36 and 39, respectively.

  Here, the width 37 of the first processing amount detection element 30 is higher than the width 40 of the second processing amount detection element 31, and therefore, when processing from the processing start point 35 to the processing end point 34, the first processing amount. The amount of change in the impedance Z1 of the detection element becomes gentler than the amount of change in the impedance Z2 of the second machining amount detection element.

Ａ・・・導電性膜３２のシート抵抗値
Ｂ１・・・第一の加工量検知素子３０の長さ３６
Ｃ１・・・加工終点における第一の加工量検知素子３０の幅３７
Ｂ２・・・第二の加工量検知素子３１の長さ３９
Ｃ２・・・加工終点における第二の加工量検知素子３１の幅４０
ｈ・・・加工終点までの加工量３８
ここで、Ｂ１＝αＢ２、Ｃ１＝αＣ２、（ただし、αは任意の数）とすることで、Ｚ１、Ｚ２の値は図２に示すように加工によるインピーダンスの変化量が異なり、例えば、ｈ＝０となる加工終点において同値となるようにすることが可能となる。 Z1 and Z2 in the structural example shown in FIG. 12 can be expressed by the following equations, respectively.

A: Sheet resistance value of the conductive film 32 B1: Length 36 of the first processing amount detection element 30
C1... Width 37 of the first machining amount detection element 30 at the machining end point
B2: Length 39 of the second machining amount detection element 31
C2... Width 40 of the second machining amount detection element 31 at the machining end point.
h ・ ・ ・ Processing amount 38 until the processing end point
Here, by setting B1 = αB2 and C1 = αC2 (where α is an arbitrary number), the values of Z1 and Z2 differ in the amount of change in impedance as shown in FIG. 2, for example, h = It becomes possible to have the same value at the processing end point of 0.

  Further, the two processing amount detection elements in the present invention are not limited to the structural example shown in FIG. 12, and the same effect can be obtained by taking the structure shown in FIGS. 13 and 14, for example.

  As described above, the structures that can be taken by the two machining amount detection elements in the present invention are different in impedance change amount depending on machining, and have the same impedance at the machining end point, or the four circuits constituting the bridge circuit shown in FIG. Any structure may be used as long as the impedances Z1, Z2, Z3, and Z4 satisfy Z1Z4 = Z2Z3.

  FIG. 15 is a configuration diagram of an embodiment of a processing amount detection device (polishing device) according to the present invention.

  The workpiece 5 includes a first machining amount detection element 1 and a second machining amount detection element 2, and these machining amount detection elements 1 and 2 are connected to the impedance adjustment element 3 and the impedance adjustment element 4. The circuit is configured.

  The workpiece 5 is disposed on the surface plate 53, and the machining amount of the workpiece 5 is detected as an electrical signal by, for example, the detection circuit 8 shown in FIG. 1 connected to the bridge circuit. An input signal is input to one terminal of the bridge circuit from the input signal source shown in FIG. 1, and an output signal (output voltage) from the other terminal of the bridge circuit is detected by the detection circuit unit shown in FIG. The detected electrical signal is transmitted to the control unit 56, and the control unit 56 calculates the processing amount and processing end point of the processing amount detection element, for example. Thereafter, the control unit 56 sends a control signal to the pressing mechanism 55 and the polishing surface plate driving mechanism 54 to adjust the force for pressing the workpiece 5 against the surface plate 53, and rotates the surface plate 43 by the polishing surface plate driving mechanism 54. Polishing is performed.

  As mentioned above, the invention made by the present inventor has been specifically described based on the embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say.

  For example, in the fourth embodiment, the configuration example of the polishing apparatus has been described. However, the present invention is not limited to this, and the entire technique for detecting the processing amount and the processing end point in a processing apparatus such as a cutting apparatus or an etching apparatus. Widely applicable to.

1 Processing amount detection element 1, 2 Processing amount detection element 2, 3 Impedance adjustment element 1, 4 Impedance adjustment element 2, 5 Workpiece, 6 Input signal source, 7 Output voltage, 8 Detection circuit, 10 Processing start point, 11 Processing end point, 12 Impedance Zi constituting one side of bridge circuit, 13 Resistance Ri changed by processing, 14 Capacitance Ci changed by processing, 15 Capacitance for detection C, 16 Coupling coefficient k, 17 Inductor L1 on detection sensor side, 18 Inductor L2 on Workpiece Side, 19 External Capacitance C, 30 Structure of Work Quantity Detection Element 1, 31 Structure of Work Quantity Detection Element 2, 32 Conductive Film, 33 Electrode of Work Quantity Detection Element, 34 Work Quantity Processing end point at detection element, 35 Processing start point at processing amount detection element, 36 Length of processing amount detection element 1, 37 At processing end point Width of processing amount detection element 1, 38 Processing amount to processing end point, 39 Length of processing amount detection element 2, 40 Width of processing amount detection element 2 at processing end point, 50 Detection substrate, 51 Detection tool, 53 Polishing Surface plate, 54 Polishing surface plate drive mechanism, 55 Pressing mechanism, 56 Control unit

Claims (15)

Inputting an input signal to one terminal of the bridge circuit of a workpiece having a bridge circuit having an element having an impedance value known and an element having an unknown impedance value;
Detecting an output signal from another terminal at a position opposite to the terminal at the position of the bridge circuit;
Calculating an impedance value of the unknown element and a processing end point of the workpiece based on the input signal, the output signal, and the impedance value of the known element;
A processing amount detection method comprising: The processing amount detection method according to claim 1,
A processing amount detection method, wherein there are a plurality of the unknown elements. The processing amount detection method according to claim 1 or 2,
The machining amount detection method, wherein the plurality of unknown elements have different amounts of change in impedance value due to machining. It is the processing amount detection method in any one of Claims 1 thru | or 3, Comprising:
The plurality of unknown elements have different impedance values at a machining start point, and have matching impedance values at a machining end point. The processing amount detection method according to any one of claims 1 to 4,
In the calculation step, Vout = ((Z3 / (Z1 + Z3)) − (Z4 / (Z2 + Z4))) Vin (where Vout is an output signal, Vin is an input signal, Z3 and Z4 are elements having known impedance values) A machining amount detection method, wherein Z1 and Z2 are calculated based on impedance values, Z1 and Z2 being impedance values of elements whose impedance values are unknown. It is the processing amount detection method in any one of Claims 1 thru | or 5, Comprising:
In the calculating step, an impedance value and a processing end point of a plurality of unknown elements are calculated for one bridge circuit. It is the processing amount detection method in any one of Claims 1 thru | or 6, Comprising:
In the calculating step, the processing amount of the unknown element is further calculated. A surface plate on which a workpiece having a bridge circuit having an element having an impedance value known and an element having an unknown impedance value is placed;
Input means for inputting an input signal to one terminal of the bridge circuit of the workpiece;
Detecting means for detecting an output signal from another terminal at a position opposite to the terminal at the position of the bridge circuit;
Based on the input signal input by the input means, the output signal output by the output means, and the impedance value of the known element, the impedance value of the unknown element and the processing end point of the workpiece are calculated. A control unit that transmits a control signal to the surface plate;
A processing amount detection device having: The processing amount detection device according to claim 8,
A processing amount detection apparatus comprising a plurality of the unknown elements. The processing amount detection device according to claim 8 or 9,
The machining amount detection device, wherein the plurality of unknown elements have different amounts of change in impedance values due to machining. It is a processing amount detection apparatus in any one of Claims 8 thru | or 10, Comprising:
The plurality of unknown elements have different impedance values at a machining start point, and have matching impedance values at a machining end point. The processing amount detection device according to any one of claims 8 to 11,
In the control unit, Vout = ((Z3 / (Z1 + Z3)) − (Z4 / (Z2 + Z4))) Vin (where Vout is an output signal, Vin is an input signal, and Z3 and Z4 are impedances of elements whose impedance values are known. Z1 and Z2 are calculated on the basis of values Z1 and Z2 based on impedance values of elements whose impedance values are unknown. The processing amount detection device according to any one of claims 8 to 12,
The processing amount detection apparatus characterized in that the control unit calculates impedance values and processing end points of a plurality of unknown elements for one bridge circuit. The processing amount detection device according to any one of claims 8 to 13,
The control unit further calculates a processing amount of the unknown element. A workpiece processed by the processing amount detection method according to claim 1.

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