JPH07180047A - Production of ferroelectric substance thin film element and apparatus for producing the same - Google Patents

Abstract

PURPOSE:To produce a ferroelectric substance thin film which has high orientability to a polarization axis and is uniform in the directions of spontaneous polarization by forming films in the state of insulating substrates from the wall surfaces of a vapor deposition chamber for vapor deposition by sputtering. CONSTITUTION:MgO single crystal substrates which are cloven at (100) and are ground are used as the substrates 1 to be formed with the thin films. The substrates 1 are held on an anode 3 by an insulating substrate holder 2 consisting of ceramics. The anode 3 and the substrates 1 are insulated. The wall surfaces 4 of the vapor deposition chamber and the anode 3 are insulated by an anode holder 6 of an insulator. A voltage is applied to a target 5 and gaseous Ar and gaseous O2 are introduced into the vapor deposition chamber to execute vapor deposition by sputtering, by which the ferroelectric substance thin film of a perovskite type is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pyroelectric infrared detecting element,
The present invention relates to a method and an apparatus for manufacturing a ferroelectric thin film element used for a piezoelectric element and an electro-optical element.

[0002]

2. Description of the Related Art Lead titanate PbTiO which is a composite oxide
₃ , PbZr _x Ti _{1 -x} O ₃ (PZT), (Pb
_{1 - x La x) (Zr} y Ti 1 - y) 1 - x / 4 O
Ferroelectrics having a perovskite structure such as ₃ (PLZT) are interesting materials with excellent ferroelectric properties, piezoelectric properties, pyroelectric properties, and electro-optical properties, and various functional devices utilizing these properties have been investigated. Has been done. Therefore, thinning of these functional devices is very important for high performance and miniaturization.

Ferroelectric materials that have been used in infrared detection elements and piezoelectric elements so far are ceramics, and the direction of crystal axes is random. For this reason, the spontaneous polarization is also randomly arranged, and if it is left as it is, it cannot be used as the above-mentioned element for taking out the change of the spontaneous polarization as an output. Therefore, a high electric field was applied to the material to perform a polarization treatment to align the directions of spontaneous polarization. However, even if the polarization process is performed, the directions of the crystal axes do not align, and the directions remain random and the spontaneous polarization as an average appears in a certain direction. Therefore, the absolute value of spontaneous polarization and the magnitude of change are It was a small one.

[0004]

Under the above background, development of epitaxial ferroelectric thin films oriented along the polarization axis has been promoted. However, the crystallinity is good,
Until now, it has been difficult to stably form a ferroelectric thin film having a high orientation on the polarization axis. Further, just by orienting on the polarization axis does not necessarily align with the direction of spontaneous polarization, and generally 180 ° domains are formed and arranged alternately. Therefore, in this case as well, polarization treatment is required, but the polarization treatment on the thin film due to the high electric field has a problem in productivity due to dielectric breakdown and nonuniformity of polarization.

The present invention solves the above-mentioned conventional problems, and stably forms a perovskite type ferroelectric thin film having good crystallinity, high orientation with respect to the polarization axis, and moreover uniform spontaneous polarization directions. The present invention provides a method and an apparatus therefor.

[0006]

When forming a ferroelectric thin film, the substrate is insulated from the wall surface of the vapor deposition chamber. In addition, the anode is insulated from the wall surface of the vapor deposition chamber.

[0007]

In the film forming method and the film forming apparatus of the present invention, since the substrate or the anode is insulated from the wall surface of the vapor deposition chamber having the ground potential, the substrate potential never drops to the ground potential. Therefore, a ferroelectric thin film that is strongly aligned with the polarization axis and in which the direction of spontaneous polarization is already aligned is obtained, and a high-performance ferroelectric thin film element can be realized.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an apparatus for manufacturing a PLT ferroelectric thin film by the magnetron sputtering method in this embodiment.

As a substrate 1 on which a thin film is grown, (10
A MgO single crystal substrate cleaved and polished in 0) was used. By holding this on the anode 3 with a ceramic insulating substrate holder 2, the anode 3 and the substrate 1 are insulated. Further, the deposition chamber wall surface 4 and the anode 3 are insulated from each other by the anode holder 6 using an insulator. This substrate is heated to about 600 to 700 ° C. by a heater (not shown).

[0011] 0.8Pb ₀ as the target _{5. 9 La 0. 1 Ti} 0. 975 5O 3 +0.
A 2PbO 2 sintered body was used. The reason why PbO is added in excess is to prevent the composition ratio of Pb having a low vapor pressure from becoming small because the substrate temperature during film formation is high as described above.

[0012] The deposition chamber 20: 1 to 10: 1 of Ar gas and O ₂ gas at a rate introduced so that the internal gas pressure of about 0.4 P _a, of 0.2 to 0.3 [mu] m / h A ferroelectric thin film having a thickness of about 2.7 μm was formed at a film forming rate.

The obtained PLT thin film had a perovskite structure, and the diffraction peak (10
It was found that (001) was much higher than the height of (0) and was strongly oriented in the c-axis direction, which is the polarization axis.
Actually, the c-axis orientation rate α = I (001) / {I (001)
+ I (100)} (I (001) and I (100) are the diffraction intensities of (001) and (100), respectively), and a PLT thin film having 95% or more was stably obtained.

The MgO substrate of the PLT thin film thus obtained was
Remove and attach electrodes on both sides of the PLT thin film,
The r and the pyroelectric coefficient γ were measured. Unit temperature change hit here
R spontaneous polarization P_sIs defined as the pyroelectric coefficient,
The amount of change in temperature and the amount of change in spontaneous polarization are ΔT and ΔP, respectively.
_sThen ΔP_s= Γ · ΔT The higher the orientation ratio of the material to the polarization axis,
Spontaneous polarization P as the polarization directions are aligned_sThe absolute value of
And shows a higher pyroelectric coefficient and sensitivity as a sensor
Will also be higher. Ε as the measurement result_r~ 180, γ ~ 4.5
× 10^-8C / cm ²K is obtained, and the temperature using the pyroelectric effect is used.
A highly sensitive sensor can be realized.

Also, a similar ferroelectric thin film can be obtained by holding the substrate 1 on the anode 3 by the ceramic insulating substrate holder 2 to insulate the substrate from the anode and performing sputtering deposition. .

A similar ferroelectric thin film can be obtained by insulating the deposition chamber wall 4 and the anode 3 with an anode holder 6 using an insulator, holding the substrate on this with a substrate holder, and performing sputtering deposition. It is possible to obtain

The insulation method of this embodiment is an example.
The method is not limited to the above method.

[0018]

As is apparent from the above description, the present invention has the following advantages.
By performing the sputtering while electrically insulating the anode from the wall surface of the vapor deposition chamber, it is possible to obtain a ferroelectric thin film having a very high orientation with respect to the polarization axis and uniform spontaneous polarization directions.

By insulating the substrate from the anode having the same potential as the wall surface of the vapor deposition chamber, a ferroelectric thin film similar to the above can be easily obtained without making a large change in the apparatus.

If this ferroelectric thin film is used, it is possible to realize an infrared detecting element, a piezoelectric element and the like which do not require polarization treatment and which are much more sensitive and smaller than ceramics.

[Brief description of drawings]

FIG. 1 is a sectional view of a basic configuration of a sputtering apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 MgO single crystal substrate 2 Ceramic insulating substrate holder 3 Anode 4 Vapor deposition chamber wall surface 5 Target 6 Anode holder

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location H01L 21/314 A 7352-4M 21/316 Y 7352-4M (72) Inventor Ken Kamata Osaka Prefecture Kadoma City 1006 Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. When a ferroelectric thin film having a perovskite structure is formed by sputtering deposition on a (100) -oriented MgO single crystal substrate or a substrate having a platinum electrode formed thereon, the substrate is placed against the wall surface of the deposition chamber. A method of manufacturing a ferroelectric thin film element, characterized in that the film is formed in an insulated state. 2. When a ferroelectric thin film having a perovskite structure is formed by sputtering deposition on a (100) -oriented MgO single crystal substrate or a substrate having a platinum electrode formed thereon, an anode is provided on the wall surface of the deposition chamber. A method of manufacturing a ferroelectric thin film element, which comprises forming a film in an insulated state. 3. When a ferroelectric thin film having a perovskite structure is formed by sputtering deposition on a (100) -oriented MgO single crystal substrate or a substrate having a platinum electrode formed thereon, an anode is provided on the wall surface of the deposition chamber. A method of manufacturing a ferroelectric thin film element, which comprises forming a film while insulating and simultaneously insulating the substrate from the anode. 4. An apparatus for producing a perovskite type ferroelectric thin film by sputtering deposition, comprising: (100)
An oriented MgO single crystal substrate or a substrate on which a platinum electrode is formed, and a jig for holding this substrate on an anode are provided, and the substrate is insulated from the anode by the jig. Equipment for manufacturing dielectric thin film elements. 5. An apparatus for producing a perovskite type ferroelectric thin film by sputtering deposition, comprising:
0) An oriented MgO single crystal substrate or a substrate on which a platinum electrode is formed, and a jig for holding the substrate on the anode, and have a structure for insulating the wall surface of the vapor deposition chamber from the anode An apparatus for manufacturing a ferroelectric thin film element. 6. An apparatus for producing a perovskite type ferroelectric thin film by sputtering deposition, comprising:
0) An oriented MgO single crystal substrate or a substrate on which a platinum electrode is formed, and a jig for holding the substrate on an anode are provided, the substrate and the anode are insulated by the jig, and a vapor deposition chamber is further provided. An apparatus for manufacturing a ferroelectric thin film element, which has a structure for insulating the wall surface of the anode from the anode.