JP2006210487A - Electrical characteristics measuring device of wafer with ferroelectric material formed therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrical characteristics measuring device of a wafer where a ferroelectric material which precisely measures the electrical characteristics in a state of the wafer is formed, by solving the problem wherein the electrical characteristics as the state of the wafer cannot be measured precisely on the ferroelectric material used for tuning fork for sensor. <P>SOLUTION: The device is provided with a table 6 on which the wafer 5 where the ferroelectric material is formed on a silicon substrate is placed, a plurality of pins 7 disposed on the table 6 so that they energize and hold a ferroelectric material non-forming part at the surface peripheral edge of the wafer 5 and a measuring part for applying voltage to the wafer 5 and measuring the electrical characteristics. Since external force will not be added to the ferroelectric material formed on the surface of the wafer 5, the ferroelectric material can be expanded and contracted freely, and the electrical characteristics of the ferroelectric material can be measured accurately, without partially destroying the polarization state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrical property measuring apparatus for a wafer formed with a ferroelectric material, which is useful when measuring electrical properties of a ferroelectric material used in a tuning fork or an actuator for a sensor in a wafer state. is there.

  A piezoelectric body constructed by laminating thin films such as piezoelectric materials on a silicon substrate is slightly expanded or contracted by applying a voltage to the piezoelectric body, and conversely, a voltage is applied by applying stress to the piezoelectric body. It has a piezoelectric characteristic of producing. Therefore, in order to efficiently generate such piezoelectric characteristics, it is important to accurately grasp the electrical characteristics of the manufactured piezoelectric thin film at an earlier point in time. For this reason, the silicon substrate The electrical characteristics including the piezoelectric characteristics have been measured in the state of a wafer having a ferroelectric material formed thereon.

  FIG. 7 is a cross-sectional view and a top view of the main part showing the configuration of a conventional electrical characteristic measuring apparatus for a wafer on which this type of ferroelectric material is formed. In FIG. 7, reference numeral 20 denotes a wafer as an object to be measured. In this wafer 20, a lower electrode 22 made of a conductive member such as platinum is formed on a silicon substrate 21 by a sputtering method, and a ferroelectric material 23 having piezoelectric characteristics is formed on the lower electrode 22 by a sputtering method. The upper electrode 24 made of a conductive member such as platinum is formed on the ferroelectric material 23 by sputtering.

  Reference numeral 25 denotes an insulating table on which the wafer 20 is placed. Reference numeral 26 denotes a vacuum part provided on the insulating table 25. By vacuuming the vacuum part 26 by a vacuum pump 27 connected to the vacuum part 26, The back surface of the wafer 20 placed on the insulating table 25 is sucked and fixed on the insulating table 25.

  The conventional apparatus for measuring electrical characteristics of a wafer having a ferroelectric material formed as described above is an upper portion formed on the wafer 20 by a measurement unit (not shown) with the wafer 20 fixed on the insulating table 25. By applying a voltage to the electrode 24 and the lower electrode 22 and thereby compressing the ferroelectric material 23 formed on the wafer 20 by the piezoelectric characteristics, the electrical characteristics including the piezoelectric characteristics of the ferroelectric material 23 are measured. It was something like that.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 62-249447

  However, in the above-described conventional apparatus for measuring electrical characteristics of a wafer on which a ferroelectric material is formed, the back surface of the wafer 20 is fixed on the table 25 by vacuum suction. When a voltage is applied, the ferroelectric material 23 tends to expand and contract due to the piezoelectric characteristics, but the force is extremely small compared to the force that vacuum-adsorbs the wafer 20, so the wafer 20 cannot expand and contract. For this reason, there has been a problem that the polarization state is partially broken, or the electrical characteristics including the piezoelectric characteristics of the ferroelectric material 23 cannot be measured accurately.

  The present invention solves such a conventional problem, and by fixing the wafer in a state where the ferroelectric material can be expanded and contracted by piezoelectric characteristics, the ferroelectric material can be obtained without partially destroying the polarization state. It is an object of the present invention to provide an apparatus for measuring electrical characteristics of a wafer on which a ferroelectric material is formed, capable of accurately measuring electrical characteristics including the piezoelectric characteristics.

  In order to solve the above-mentioned problems, the present invention urges and holds a table on which a wafer having a ferroelectric material formed on a silicon substrate is placed, and a ferroelectric material-unformed portion on the peripheral edge of the wafer. And a plurality of pins provided on the table, and a measurement unit for measuring the electrical characteristics by applying a voltage to the wafer.

  As described above, according to the present invention, the wafer is fixed on the table by biasing and holding the ferroelectric material non-formed portion on the peripheral edge of the wafer surface with a plurality of pins. Since the formed ferroelectric material does not receive any external force such as pressurization or suction, the ferroelectric material can be freely expanded and contracted according to the piezoelectric characteristics, thereby partially destroying the polarization state. In this way, it is possible to obtain a special effect that the electrical characteristics including the piezoelectric characteristics of the ferroelectric material can be accurately measured.

(Embodiment 1)
Hereinafter, the first and second aspects of the present invention will be described with reference to the first embodiment.

  FIG. 1 is a cross-sectional view showing the configuration of a wafer, which is an object to be measured, using the electrical property measuring apparatus for a wafer on which a ferroelectric material is formed according to Embodiment 1 of the present invention. Reference numeral 1 denotes a silicon substrate, and reference numeral 2 denotes a lower electrode made of a conductive member such as platinum formed on the silicon substrate 1, which is formed by sputtering or the like. Reference numeral 3 denotes a ferroelectric material having piezoelectric characteristics formed on the lower electrode 2 and formed by sputtering or the like. An upper electrode 4 made of a conductive member such as platinum formed on the ferroelectric material 3 is formed by sputtering or the like. Thereby, a wafer 5 is formed in which a piezoelectric thin film having a structure in which a ferroelectric material 3 is sandwiched between a lower electrode 2 and an upper electrode 4 is formed on a silicon substrate 1.

  FIG. 2 is a top view and a cross-sectional view of the principal part showing the configuration of a wafer electrical property measuring apparatus on which a ferroelectric material is formed according to the present embodiment. In FIG. 2, reference numeral 6 denotes the wafer 5 placed thereon. For example, an insulating table, 7 is a plurality of insulating pins arranged on the table 6 so as to form a circle at a predetermined interval, 8 is a spring for biasing the pin 7, 9 Is a holder in which the spring 8 and the pin 7 are accommodated, and the pin 7 is not formed with the ferroelectric material 3 formed on the surface 6 of the wafer 5 on the peripheral edge of the wafer 5. 5a (the surface of the silicon substrate 1) is configured to be biased and held via a spring 8.

  Then, in a state where the wafer 5 is fixed on the table 6 in this manner, a ferroelectric is formed on the wafer 5 by applying a voltage to the upper electrode 4 and the lower electrode 2 formed on the wafer 5 by a measurement unit (not shown). The body material 3 is expanded and contracted by piezoelectric characteristics, and thereby the electrical characteristics including the piezoelectric characteristics of the ferroelectric material 3 are measured.

  In the wafer electrical characteristic measuring apparatus having the ferroelectric material according to the present embodiment configured as described above, a plurality of pins 7 bias and hold the ferroelectric material non-formed portion 5a on the surface periphery of the wafer 5. Thus, since the wafer 5 is fixed on the table 6, the ferroelectric material 3 formed on the surface of the wafer 5 is not subjected to any external force such as pressurization or suction, so that the ferroelectric material 3 Can be freely expanded and contracted by the piezoelectric characteristics. As a result, the wafer 5 is warped as shown in FIG. As a result, it is possible to obtain an extraordinary effect that the electrical characteristics including the piezoelectric characteristics of the ferroelectric material 3 can be accurately measured without partially destroying the polarization state. Is.

(Embodiment 2)
Hereinafter, the invention described in claim 3 of the present invention will be described with reference to the second embodiment.

  In the present embodiment, the configuration of the pins of the electrical property measuring device for the wafer on which the ferroelectric material described with reference to FIG. 2 is formed is partially different. Since the configuration is the same as that of the first embodiment, the same reference numerals are given to the same parts and the detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 4 is a cross-sectional view of the principal part showing the configuration of the electrical property measuring apparatus for a wafer formed with a ferroelectric material according to the second embodiment of the present invention. In FIG. 4, 10 is a pin, and 11 is the pin 10. A holder that is held via a spring 12 is shown. The pin 10 has a configuration in which the central axis of the pin 10 intersects the central axis of the wafer 5 on the back surface side of the wafer 5.

  With such a configuration, when a voltage is applied to the ferroelectric material 3 formed on the wafer 5, the ferroelectric material 3 expands and contracts and the wafer 5 expands and contracts due to piezoelectric characteristics. At this time, the wafer 5 is centered. Therefore, it is possible to prevent a large stress from being applied to the wafer 5 and perform measurement with high accuracy.

(Embodiment 3)
The third aspect of the present invention will be described below with reference to the third embodiment.

  In the present embodiment, the configuration of the table of the electrical property measuring apparatus for the wafer on which the ferroelectric material described with reference to FIG. 2 in Embodiment 1 is formed is partially different. Since the configuration is the same as that of the first embodiment, the same reference numerals are given to the same parts and the detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 5 is a cross-sectional view of the principal part showing the configuration of the electrical property measuring apparatus for a wafer formed with a ferroelectric material according to the third embodiment of the present invention. In FIG. 5, 13 is a table, and 14 is the table 13. The vacuum suction section 14 is configured to vacuum-suck the back surface periphery of the wafer 5 opposite to the front surface periphery of the wafer 5 biased and held by the plurality of pins 7 via the vacuum pump 15. Is provided.

  The electrical characteristic measuring apparatus for a wafer formed with the ferroelectric material according to the present embodiment configured as described above is configured to fix the wafer 5 by the vacuum suction unit 14 in addition to fixing the wafer 5 by the plurality of pins 7. As a result, the fixing force of the wafer 5 can be finely adjusted, so that the ferroelectric material 3 can be expanded and contracted more freely by the piezoelectric characteristics, and more accurate measurement can be performed. It will be possible.

(Embodiment 4)
In the following, the invention described in claims 5 and 6 of the present invention will be described using the fourth embodiment.

  In the present embodiment, the configuration of the table of the electrical property measuring apparatus for the wafer on which the ferroelectric material described with reference to FIG. 2 in Embodiment 1 is formed is partially different. Since the configuration is the same as that of the first embodiment, the same reference numerals are given to the same parts and the detailed description thereof is omitted, and only different parts will be described below with reference to the drawings.

  FIG. 6 is a cross-sectional view of the principal part showing the configuration of the electrical property measuring apparatus for a wafer formed with a ferroelectric material according to the fourth embodiment of the present invention. In FIG. 6, 16 is a table. The cavity 16a is provided so as not to contact the wafer 5 except for the portion where the wafer 5 is fixed.

  The electrical property measuring apparatus for a wafer formed with the ferroelectric material according to the present embodiment configured as described above can expand and contract the ferroelectric material 3 more freely according to the piezoelectric characteristics. It becomes possible to perform a high measurement.

  Further, the table 16 is made of a conductive material to form an insulating table, which is connected to the ground of the measuring device, so that more accurate measurement can be performed.

  The apparatus for measuring electrical characteristics of a wafer formed with a ferroelectric material according to the present invention does not apply any external force such as pressurization or suction to the ferroelectric material formed on the wafer. Can be freely expanded and contracted by this, so that the electrical characteristics including the piezoelectric characteristics of the ferroelectric material can be accurately measured without partially destroying the polarization state. This is effective when manufacturing a tuning fork for a sensor using a ferroelectric material.

Sectional drawing which showed the structure of the wafer which is a to-be-measured object measured using the electrical property measuring apparatus of the wafer in which the ferroelectric material by Embodiment 1 of this invention was formed A top view and a cross-sectional view of the main part showing the configuration of an electrical property measuring apparatus for a wafer formed with the same ferroelectric material Sectional view showing the state of the wafer when measuring the electrical characteristics Sectional drawing which shows the structure of the electrical property measuring apparatus of the wafer in which the ferroelectric material by Embodiment 2 of this invention was formed Sectional drawing which shows the principal part of the structure of the electrical property measuring apparatus of the wafer in which the ferroelectric material by Embodiment 3 of this invention was formed Sectional drawing which shows the principal part of the structure of the electrical property measuring apparatus of the wafer in which the ferroelectric material by Embodiment 4 of this invention was formed Sectional view and top view of relevant parts showing the configuration of a conventional electrical property measuring apparatus for wafers formed with a ferroelectric material

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Lower electrode 3 Ferroelectric material 4 Upper electrode 5 Wafer 5a Ferroelectric material non-formation part 6, 13, 16 Table (insulation table)
7, 10 pins (insulation pins)
8, 12 Spring 9, 11 Holder 14 Vacuum suction part 15 Vacuum pump 16a Cavity part

Claims (6)

A table on which a wafer on which a ferroelectric material is formed on a silicon substrate is placed; a plurality of pins provided on the table so as to bias and hold a ferroelectric material non-formed portion on the peripheral surface of the wafer; An apparatus for measuring electrical characteristics of a wafer on which a ferroelectric material comprising a measuring section for measuring electrical characteristics by applying a voltage to the wafer is formed. 2. The apparatus for measuring electrical characteristics of a wafer formed with a ferroelectric material according to claim 1, wherein the biasing means of the plurality of pins for biasing and holding the surface periphery of the wafer is a spring. 2. A measurement of electrical characteristics of a wafer on which a ferroelectric material according to claim 1 is formed, wherein a central axis of a plurality of pins for biasing and holding the front surface edge of the wafer intersects the central axis of the wafer on the back surface side of the wafer. apparatus. The apparatus for measuring electrical characteristics of a wafer on which a ferroelectric material is formed according to claim 1, further comprising a vacuum chucking unit that vacuum-sucks the back surface periphery of the wafer opposite to the front surface periphery of the wafer biased and held by a plurality of pins. . The apparatus for measuring electrical characteristics of a wafer on which a ferroelectric material is formed according to claim 1, wherein the table is provided with a cavity portion that prevents the wafer from abutting on the wafer except for a portion for fixing the wafer. 6. The wafer electrical property measuring apparatus according to claim 5, wherein a conductive material is used for the table on which the wafer is placed.

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