JP2006196739A - Method for manufacturing electronic component using ferroelectric material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an electronic component using a ferroelectric material used for a tuning fork for sensor or the like at low cost through the improvement of production efficiency by solving the problems that the requirement for individual polarization process lowers productivity to cause an increase in cost. <P>SOLUTION: The method for manufacturing the electronic component using the ferroelectric material in obtaining the intended electronic component by machining the wafer with a lower electrode, a ferroelectric substance, and an upper electrode sequentially film-formed comprises the steps of polarizing the ferroelectric substance after machining the upper electrode and the ferroelectric substance on the wafer, and machining the lower electrode and silicon substrate afterwards. The work in large unit can downsize the facility to lower the cost, and suppress a variation in characteristics to improve a quality and reliability. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of manufacturing an electronic component using a ferroelectric material used for a tuning fork or an actuator for a sensor.

PbTiO ₃ —PbZrO ₃ piezoelectric material (hereinafter referred to as PZT piezoelectric material), which is one of the ferroelectric materials, exhibits excellent piezoelectric characteristics, and is widely used for tuning forks and actuators for sensors. Tuning forks, actuators and the like using PZT type piezoelectric tuning forks have been developed. A tuning fork using this PZT type piezoelectric tuning fork generally uses a manufacturing method in which a PZT type piezoelectric material is formed on a silicon substrate and then machined or polarized.

  FIG. 13 is a conceptual diagram showing a method of polarizing a ferroelectric when manufacturing this type of conventional tuning fork. In FIG. 13, 20a and 20b indicate tuning forks, and these tuning forks 20a and 20b are silicon substrates 21. A lower electrode 22, a ferroelectric material 23, and an upper electrode 24 are sequentially formed on the wafer 25 to produce a wafer 25. The wafer 25 is machined to be separated into individual pieces to obtain tuning forks 20a and 20b having a desired configuration. It is a thing.

  A voltage generator 26 has a voltage output terminal at one end of the voltage generator 26 connected to the upper electrode 24 of each tuning fork 20a, 20b and a GND terminal at the other end connected to the lower electrode 22 of each tuning fork 20a, 20b. In a connected state, each tuning fork 20a, 20b was heated to a high temperature of, for example, 150 ° C., and then a voltage was applied from the voltage generator 26 to perform polarization (polling) processing of the ferroelectric 23. .

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
JP-A-5-70245

  However, the above-described conventional method for manufacturing an electronic component using a ferroelectric material is a manufacturing method in which a tuning fork 20a, 20b having a desired configuration is manufactured by machining a wafer 25, and then a polarization process is performed. Therefore, as a matter of course, the tuning forks 20a and 20b manufactured as described above have already completed the processing of the upper electrode 24, the processing of the ferroelectric 23, and the processing of the lower electrode 22, and the tuning forks 20a and 20b. The electrode pattern is also complete.

  Therefore, when performing polarization processing on these tuning forks 20a, 20b, a voltage generator 26 for supplying a voltage to the upper electrode 24 and the lower electrode 22 of each tuning fork 20a, 20b, and this voltage generator 26 A voltage supply probe for connecting each tuning fork 20a, 20b is required individually, which not only increases the equipment cost but also increases the size of the equipment.

  Furthermore, in recent years, as tuning forks have become smaller, it has become possible to manufacture a large number of tuning forks on a wafer, and in order to individually apply voltages to a large number of tuning forks, a large number of voltage generators are required. As a result, there has been a problem in that it is expensive to apply a voltage to such a large number of tuning forks at once to perform the polarization treatment.

  Also, in the method of performing polarization processing by individually applying a voltage to each of many tuning forks from individual voltage generators, it is difficult to suppress variations in the characteristics of the tuning fork after polarization processing, and this causes problems in performance. Also had.

  An object of the present invention is to solve such a conventional problem and to provide a method for manufacturing an electronic component using a ferroelectric material, which can manufacture a highly reliable electronic component at a low cost. Is.

  In order to solve the above-mentioned problems, the present invention produces a wafer by sequentially forming a lower electrode, a ferroelectric and an upper electrode on a silicon substrate, and machining the wafer to obtain an electronic component having a desired configuration. In a method of manufacturing an electronic component using a ferroelectric material, after processing the upper electrode and the ferroelectric of the wafer, a polarization process is performed to polarize the ferroelectric, and thereafter processing of the lower electrode and the silicon substrate is performed. To obtain an electronic component having a desired configuration.

  As described above, since the manufacturing method according to the present invention can perform work in large units by performing polarization treatment before the electrode processing step, the equipment is reduced, the cost is reduced, the production efficiency is increased, and the characteristics are increased. It is possible to obtain an extraordinary effect that it is possible to improve quality and reliability by suppressing the variation of the above.

(Embodiment 1)
Hereinafter, the invention described in the first to fourth aspects of the present invention will be described using the first embodiment.

  FIG. 1 is a flowchart showing a manufacturing process of an electronic component manufacturing method using a ferroelectric material according to the first embodiment of the present invention. Hereinafter, the strong process according to the present embodiment will be described with reference to the flowchart of FIG. A method for manufacturing an electronic component using a dielectric material will be described.

  First, FIG. 2 is a cross-sectional view showing the structure of a wafer for explaining the first film formation step. In FIG. 1, reference numeral 1 denotes a silicon substrate, and a conductive material such as platinum is provided on the silicon substrate 1. A lower electrode 2 made of a member is formed by sputtering or the like. Subsequently, a PZT ferroelectric 3 having ferroelectric characteristics is formed on the lower electrode 2 by sputtering or the like. Further, an upper electrode 4 made of a conductive member such as gold is formed on the ferroelectric 3 by a sputtering method or the like. In this manner, the film forming process is completed by manufacturing the wafer 5 having the structure in which the ferroelectric 3 is sandwiched between the lower electrode 2 and the upper electrode 4 on the silicon substrate 1.

  Next, the upper electrode processing step (1), which is the next step, will be described with reference to FIG. 3. The upper electrode 4 formed on the wafer 5 is processed into a tuning fork electrode shape to expose the ferroelectric 3. . As a result, the upper electrode 4 where the tuning fork electrode is to be formed is divided into a plurality of rows (rows A to H) as shown in FIG. As shown in FIG. 9, the row A as an example divided into a plurality of parts as described above has a plurality of tuning forks 6 arranged in parallel at the center, and a voltage supply terminal 7 and a voltage measuring terminal at both ends. The terminal 8 is also produced at the same time. Further, the plurality of tuning forks 6, the voltage supply terminal 7, and the voltage measurement terminal 8 are connected by connecting portions 9 and 10. The B column to the H column are the same except that the number of the tuning fork 6 is different from that of the A column.

  Next, the ferroelectric processing step (1), which is the next step, will be described with reference to FIG. 4. The exposed portion of the ferroelectric 3 in FIG. The ferroelectric 3 is processed so that the lower electrode 2 is exposed.

  Next, the polarization process, which is the next process, will be described with reference to FIG. 5. First, a voltage generator 11A is prepared, and the voltage output terminal at one end of the voltage generator 11A is connected to the Hi side at one end of the current measuring instrument 12A. Further, the low side of the other end of the current measuring device 12A is connected to the voltage supply terminal 7 in the A column. The GND terminal at the other end of the voltage generator 11A is connected to + COM1 and grounded together. Further, in the B row to the H row, similarly, the voltage output terminals of the voltage generators 11B to 11H are connected to the Hi side of one end of the current measuring devices 12B to 12H, and the other end of the current measuring devices 12B to 12H is Low. The other side of the voltage generators 11B to 11H is connected to + COM1 and grounded together, and the wafer 5 is brought to a high temperature of 150 ° C. in this state. Heat.

  Next, a voltage (polarization voltage) is applied from the voltage generator 11A to the voltage supply terminal 7 in the A column. At this time, as shown in FIG. 10, when the polarization voltage is applied, the polarization voltage is increased until the polarization voltage becomes constant, for example, 20 V after a certain time, and after the polarization voltage becomes constant, the polarization voltage is kept constant for a sufficient time. Continue to apply.

  When the polarization voltage is applied, the ferroelectric 3 is polarized (polling), and a polarization current flows during the polarization of the ferroelectric 3. As shown in FIG. 11, this polarization current is composed of three types of leakage current, absorption current, and thermal stimulation current, and the leakage current continues to flow when a polarization voltage is applied. Also, an absorption current flows immediately after application of the polarization voltage, and the absorption current does not flow after a sufficient time has elapsed. Here, the time during which the absorption current flows (absorption time) is about several microseconds, and when a sufficient time elapses after the absorption current stops flowing, the thermal stimulation current starts to increase.

  Therefore, the polarization current is monitored during application of the polarization voltage, and the polarization voltage is lowered when the polarization current exceeds a predetermined current value after the absorption time has elapsed. At this time, the polarization voltage is lowered at a constant interval until the polarization voltage is sufficiently lower than the voltage at the time of polarization (cooling voltage), for example, 5 V, and such operations are performed individually in all the A to H columns.

  Next, after the polarization voltages of all the columns A to H become the cooling voltage, the temperature of the wafer 5 is cooled to room temperature with the cooling voltage applied, and when the cooling is finished, the output voltages of the voltage generators 11A to 11H That is, the polarization voltage is lowered to 0 V and the voltage application is finished.

  Next, the upper electrode processing step (2) as the next step will be described. By processing the connecting portions 9 and 10 of the upper electrode 4 of the wafer 5 and cutting the upper electrode 4 of the connecting portions 9 and 10. The upper electrode 4 portion of each tuning fork 6 is separated.

  Next, the ferroelectric processing step (2), which is the next step, will be described. The connecting portions 9 and 10 of the ferroelectric 3 of the wafer 5 are processed, and the ferroelectric 3 of the connecting portions 9 and 10 is cut. By doing so, the ferroelectric 3 portion between the tuning forks 6 is separated.

  Subsequently, the lower electrode processing step, which is the next step, will be described with reference to FIG. 6. By processing only a predetermined portion of the exposed portion of the lower electrode 2 of the wafer 5, the lower electrode of each tuning fork 6 is processed. Separate the two parts.

  Subsequently, the silicon substrate processing step as the next step will be described with reference to FIG. 7. By processing only a predetermined portion of the exposed portion of the silicon substrate 1 of the wafer 5, the silicon substrate of each tuning fork 6 is processed. By separating one part, a tuning fork 6 having a predetermined shape can be obtained.

  As described above, the method of manufacturing an electronic component using the ferroelectric material according to the present embodiment can be performed in a large unit by performing the polarization process in the middle of the processing process. It is possible to minimize the voltage supply probe and wiring to the upper electrode and the lower electrode, which can greatly reduce the cost of the polarization device, as well as the polarization current flowing during polarization By controlling the polarization voltage while monitoring the polarization, it becomes possible to perform stable polarization, and it is possible to improve quality and reliability by suppressing variation in characteristics It is.

(Embodiment 2)
Hereinafter, the invention according to claim 5 of the present invention will be described using the second embodiment.

  In the present embodiment, the steps after the polarization step of the electronic component manufacturing method using the ferroelectric material according to the first embodiment are partially different, and the other steps are the same as in the first embodiment. Therefore, the same reference numerals are given to the same parts, and detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 12 is a cross-sectional view showing a state in which the polarization process is completed in the method of manufacturing an electronic component using the ferroelectric material according to the second embodiment of the present invention. In FIG. The cut portion removed by electric discharge machining in step (1), 14 is a connection portion that electrically connects the upper electrode 4 and the lower electrode 2 separated by the cut portion 13, and this connection portion 14 deposits gold. In this way, each processing step after the polarization step is performed in a state where the upper electrode 4 and the lower electrode 2 are electrically connected is performed.

  As described above, in the method of manufacturing an electronic component using the ferroelectric material according to the present embodiment, the upper electrode 4 formed on the wafer 5 is subjected to each processing step after the polarization process for polarizing the ferroelectric 3 is performed. And the lower electrode 2 are electrically connected and set at the same potential, so that the polarization of the ferroelectric 3 subjected to the polarization treatment does not deteriorate or progress. Thus, the performance of the ferroelectric 3 can be sufficiently exhibited, and an electronic component using a ferroelectric material having further excellent performance can be stably manufactured.

  The method of manufacturing an electronic component using a ferroelectric material according to the present invention can reduce the equipment cost of a polarization device and the like when manufacturing a tuning fork on a wafer, and can reduce the manufacturing cost by improving the production efficiency, as well as the variation in characteristics. It is effective as a method for manufacturing electronic parts such as tuning forks and actuators using a ferroelectric material.

The flowchart which showed the manufacturing process of the manufacturing method of the electronic component using the ferroelectric material by Embodiment 1 of this invention Cross-sectional view of wafer explaining the film formation process Sectional drawing of the wafer explaining the upper electrode processing step (1) Sectional view of wafer explaining the same ferroelectric processing step (1) Wafer cross-sectional view explaining the polarization process Wafer sectional view explaining the lower electrode machining process Sectional view of the wafer explaining the silicon substrate processing process Plan view of wafer after finishing upper electrode processing step (1) and ferroelectric processing step (1) Plan view of row A after finishing upper electrode processing step (1) and ferroelectric processing step (1) Characteristic diagram showing the relationship between polarization voltage, time, and wafer temperature in the same polarization process Characteristic diagram showing polarization current in the same polarization process Sectional drawing which showed the state which finished the polarization process by Embodiment 2 of this invention Conceptual diagram explaining a conventional method of polarizing a tuning fork

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Lower electrode 3 Ferroelectric material 4 Upper electrode 5 Wafer 6 Tuning fork 7 Voltage supply terminal 8 Voltage measurement terminal 9,10 Connection part 11A-11H Voltage generator 12A-12H Current measurement device 13 Cutting part 14 Connection part

Claims (5)

Manufacture of electronic components using ferroelectric materials that produce a wafer by fabricating a wafer by sequentially depositing a lower electrode, a ferroelectric, and an upper electrode on a silicon substrate, and machining the wafer to obtain an electronic component of a desired configuration In the method, after processing the upper electrode and the ferroelectric of the wafer, a polarization process for polarizing the ferroelectric is performed, and then the lower electrode and the silicon substrate are processed to obtain an electronic component having a desired configuration. An electronic component manufacturing method using the ferroelectric material thus made. 2. The method of manufacturing an electronic component using a ferroelectric material according to claim 1, wherein the polarization process for polarizing the ferroelectric material divides the wafer into a plurality of rows and polarizes the divided rows. The electronic component using the ferroelectric material according to claim 1, wherein the polarization process for polarizing the ferroelectric material measures a polarization current flowing during the polarization, and controls the polarization voltage to control the polarization. Manufacturing method. 4. The method of manufacturing an electronic component using a ferroelectric material according to claim 3, wherein the polarization voltage is controlled such that the polarization voltage is lowered after the polarization current becomes a predetermined value or more. 2. The respective processing steps after the polarization processing for polarizing the ferroelectric are performed in a state where the upper electrode and the lower electrode formed on the wafer are electrically connected to have the same potential. Of manufacturing electronic parts using any ferroelectric material.

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