JP2005120440A - Method for producing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a structure where, from a structure formed on a substrate using a film deposition technique, the substrate can easily be peeled. <P>SOLUTION: The method for producing a structure comprises: a stage S1 where an intermediate layer is formed on the main face of a substrate by material removable by thermal oxidation; a stage S2 where at least a brittle material layer is formed on the upper layer of the intermediate layer using an aerosol deposition method of spraying the powder of the material toward the lower layer at a high speed so as to be deposited; and a stage S3 where the intermediate layer is thermally oxidized and removed, by which the substrate is peeled from the structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a structure using a film forming technique, and more particularly to a method for manufacturing a structure using a jet deposition method.

  Conventionally, as a technique for forming a thin film or a thick film, a sputtering method, a sol-gel method, a vapor deposition method, a thermal spraying method, a jet deposition method, or the like is known. The spray deposition method is a film forming method in which raw material powder is deposited by spraying at a high speed toward the lower layer. This spray deposition method is particularly attracting attention as a technique capable of forming a strong thick film using a hard and brittle material such as ceramics. The jet deposition method is also called a gas deposition method, an aerosol deposition (AD) method, or a fine particle beam deposition method. By using these film formation techniques, a multilayer structure including a plurality of material layers, such as a multilayer capacitor, a piezoelectric pump, a piezoelectric actuator, and an ultrasonic transducer, can be easily manufactured.

  In the AD method, the material is attached to the lower layer using the collision energy when the powder of the material collides with the lower layer. Therefore, silicon, glass, sapphire, SUS (for special applications) is generally used during film formation. A substrate having a certain degree of hardness is used. Further, in Patent Document 1, in order to form a brittle material structure on a resin base material without scraping the resin base material, a base layer made of a hard material is formed on the surface of the resin base material. A brittle material is collided by a fine particle beam deposition method, and a part of the material bites into the underlayer to form an anchor portion. There is no crystal orientation in the polycrystal and there is a grain interface consisting of a glass layer at the interface between crystals. It is disclosed to form a brittle structure that is substantially absent. According to the method disclosed in Patent Document 1, a structure can also be formed on a resin substrate using the AD method.

By the way, since the structure formed on the substrate using a film forming technique such as the AD method is firmly attached to the substrate, it is difficult to peel the substrate from the structure. Therefore, such a structure is often used with the substrate attached. However, due to the presence of the substrate, the function of the structure and the apparatus using the structure is often lowered. For example, in an ultrasonic transducer manufactured using a substrate as described above, the propagation efficiency of ultrasonic waves is reduced by the substrate. Therefore, it is conceivable to remove the substrate from the structure by polishing or the like. However, in this case, since the lower part of the structure is also polished, a new electrode layer or the like must be formed on the polished surface after removing the substrate, the manufacturing process becomes complicated, and the structure There is a possibility that the adhesion between the object and the electrode layer may be reduced. Furthermore, the structure may be damaged by the stress during polishing. Therefore, a method capable of easily peeling the substrate from the structure is desired.
JP 2003-34003 A

  Therefore, in view of the above points, an object of the present invention is to easily peel a substrate from a structure formed on the substrate using a film forming technique.

  In order to solve the above-described problems, a method of manufacturing a structure according to the present invention includes a step (a) of forming an intermediate layer on a main surface of a substrate with a material that can be removed by thermal oxidation, A step (b) of forming a brittle material layer using an injection deposition method in which at least a powder of material is sprayed and deposited on the upper layer at a high speed toward the lower layer, and the intermediate layer is removed by thermal oxidation, (C) which peels a board | substrate from a structure.

  According to the present invention, the intermediate layer that can be removed by thermal oxidation is previously formed on the substrate, and the intermediate layer is removed after the structure is formed on the substrate, so that the structure is damaged. And the substrate can be easily peeled off.

Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. The same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
FIG. 1 is a flowchart showing a structure manufacturing method according to an embodiment of the present invention. Moreover, FIG. 2 is a figure for demonstrating the manufacturing method of the structure based on this embodiment. In the present embodiment, a laminated structure including a plurality of layers including a brittle material layer is manufactured. For example, a laminated structure in which a dielectric material (ferroelectric material) is used as a brittle material and electrodes are formed on both ends thereof can be used for a capacitor or the like. In addition, a laminated structure using a piezoelectric material such as PZT (Pb (lead) zirconate titanate) as a brittle material is an ultrasonic transducer that transmits and receives ultrasonic waves in an ultrasonic imaging device, a piezoelectric actuator, and the like. Can be used.

In step S1 of FIG. 1, as shown in FIG. 2A, a substrate 10 is prepared, and an intermediate layer 11 is formed thereon. As the substrate 10, for example, silicon, glass, sapphire, alumina (Al ₂ O ₃ ), SUS (special purpose steel), or the like is used. A polyimide photoresist is applied onto the substrate 10 by using a spin coater while controlling the rotational speed so that the thickness becomes 0.5 microns. Furthermore, the intermediate layer 11 is formed by drying the applied polyimide photoresist by baking. In addition, as the material for the intermediate layer 11, it is possible to use a thermally decomposable polymer that is decomposed by thermal oxidation. For example, polyimide, PMMA (polymethyl methacrylate), novolac resin, ethyl Examples thereof include other resist materials including cellosolve acetate and naphthoquinodiamide.

  In step S <b> 2, as illustrated in FIG. 2B, the layers 12 to 16 are stacked on the intermediate layer 11 to form a stacked structure. That is, first, a two-layer electrode is formed by forming a titanium (Ti) layer 12 and a platinum (Pt) layer 13 by sputtering. The titanium layer 12 is disposed in order to bring platinum having a relatively low adhesion with other materials into close contact with the lower layer, and has a thickness of about 10 nm to 100 nm, more preferably 10 nm to 50 nm. The platinum layer 13 is a conductive layer used for applying a voltage to the upper layer 14 and has a thickness of about 50 nm to 150 nm.

Next, the PZT layer 14 is formed on the platinum layer 13 by using a jet deposition method (aerosol deposition method, hereinafter also referred to as “AD method”).
FIG. 3 is a schematic diagram showing a film forming apparatus using the AD method. This film forming apparatus has an aerosol generation container 22 in which raw material powder (for example, PZT single crystal powder having an average particle size of 0.3 μm) 21 is arranged. Here, the aerosol refers to solid or liquid fine particles suspended in a gas. The aerosol generation container 22 is provided with a carrier gas introduction part 23, an aerosol lead-out part 24, and a vibration part 25. By introducing a gas such as nitrogen gas (N ₂ ) from the carrier gas introduction part 23, the raw material powder disposed in the aerosol generation container 22 is blown up to generate an aerosol. At that time, vibration is applied to the aerosol generation container 22 by the vibration unit 25, whereby the raw material powder is stirred and the aerosol is efficiently generated. The generated aerosol is guided to the film forming chamber 26 through the aerosol deriving unit 24.

  The film forming chamber 26 is provided with an exhaust pipe 27, a nozzle 28, and a movable stage 29. The exhaust pipe 27 is connected to a vacuum pump and exhausts the film forming chamber 26. The aerosol generated in the aerosol generation container 22 and guided to the film forming chamber 26 through the aerosol deriving unit 24 is ejected from the nozzle 28 toward the substrate 10. As a result, the raw material powder collides and accumulates on the substrate 10. The substrate 10 is placed on a movable stage 29 that can move in three dimensions, and the relative position between the substrate 10 and the nozzle 28 is adjusted by controlling the movable stage 29.

  Further, as shown in FIG. 2B, a titanium layer 15 and a platinum layer 16 are formed on the PZT layer 14 by sputtering. Thereby, a structure of a vibrator in which electrodes are formed on both ends of the piezoelectric material is formed. Further, a stacked structure having a plurality of layers may be formed by sequentially stacking a PZT layer, a titanium layer, and a platinum layer a desired number of times on the platinum layer 16.

In addition, as the layers 12 and 15 for bringing the platinum layers 13 and 16 into close contact with each other, a titanium oxide (TiO ₂ ) layer may be used instead of titanium. By using a pre-oxidized material, it is possible to prevent deterioration of the material due to oxygen transmitted through the PZT layer, which is generated at the time of subsequent heat treatment or firing, and deterioration of the function as an adhesion layer resulting therefrom.

In step S3 of FIG. 1, the intermediate layer 11 is removed by thermally oxidizing and decomposing the polyimide photoresist film, for example, by performing heat treatment in air at 500 ° C. for about 2 hours. Thereby, the board | substrate 10 is peeled from the laminated structures 12-16. If necessary, the laminated structures 12 to 16 may be fired thereafter.
As described above, according to the present embodiment, the substrate can be easily peeled without applying a load to the formed laminated structure.

Next, the thickness of each layer formed in this embodiment will be described in detail.
FIG. 4 shows the relationship between the thickness t (μm) of the intermediate layer and the deposition rate of the PZT layer formed by the AD method. In FIG. 4, the film formation rate on the vertical axis indicates a value obtained by normalizing the film formation rate in a range where film formation is performed well as 1 and multiplying the standardized film formation rate by the possibility of peeling. ing. Therefore, the curve shown in FIG. 4 represents a range in which film formation by the AD method is possible and the formed structure can be peeled from the substrate. In general, the film formation rate is represented by the film thickness with respect to the unit consumption of the raw material.

  As shown in FIG. 4, by providing the intermediate layer, it is possible to remove the interaction between the lowermost layer of the structure (titanium layer 12 in FIG. 2) and the substrate and to remove them. In addition, in the range of 0 <t ≦ 0.7 μm, a good film formation rate is shown. Then, the film formation rate starts to gradually decrease from the vicinity where the thickness t becomes 0.7 μm, and the film formation rate becomes lower than 0.8 in the vicinity where the thickness t becomes 1.0 μm. Further, when the thickness t exceeds 1.0 μm, the film formation rate starts to rapidly decrease, and when the thickness t exceeds 2.4 μm, film formation by the AD method becomes impossible.

As described above, the reason why the film formation rate decreases as the thickness of the intermediate layer increases is as follows. That is, the AD method is a film forming method in which the raw material powder is adhered to the lower layer by using collision energy in which the raw material powder accelerated at high speed collides with the lower layer. Therefore, if the elasticity (cushioning property) of the lower layer is too large, the collision energy of the raw material powder is absorbed or repelled and cannot be deposited in the lower layer.
Therefore, in the present embodiment, the range of 0 <t ≦ 2.4 μm is set to a range in which film formation by the AD method is possible and the formed structure can be peeled from the substrate, and the film formation rate is set to 0. A range where t ≦ 1.0 μm indicating 8 or more (a region indicated by hatching in FIG. 4) is a range where film formation can be satisfactorily performed.

  Next, in the present embodiment, the reason why the thickness of the platinum layer 13 is 50 nm or more is as follows. That is, in the AD method, a phenomenon (called “anchoring”) occurs in which the raw material powder bites into the lower layer (the platinum layer 13 in FIG. 1). The thickness of the anchor layer (powder layer) generated by this anchoring varies depending on the material of the lower layer, the speed of the powder, etc., but is generally about 10 nm to 100 nm. Therefore, it is desirable that the thickness of the platinum layer is at least 50 nm or more in order to cause the anchoring sufficiently to bring the PZT layer and the platinum layer into close contact and to make the conductivity of the platinum layer function well. is there. The reason why the thickness of the platinum layer 13 is set to 150 nm or less is that, like the intermediate layer, if the cushioning property of the platinum layer is too large, the PZT layer is difficult to deposit.

As described above, according to this embodiment, the substrate can be easily peeled from the structure including the brittle material layer formed by using the AD method. Therefore, it is possible to move to the next step after completing a series of film forming steps including the formation of the electrode layer and the brittle material layer, and thus it is necessary to form a separate electrode layer on the lowermost layer of the structure. Disappears. Moreover, since the electrode layer in which the brittle material layer is formed on the upper layer by using the AD method can be used as it is after the substrate is peeled off, it is possible to maintain the strong adhesion between the two.
In this embodiment, the laminated structure in which the electrode layers are formed on both ends of the dielectric layer is manufactured. However, a single-layer structure having only the brittle material layer may be manufactured.

  The present invention can be used in a method for manufacturing a structure using a film formation technique.

It is a flowchart which shows the manufacturing method of the structure which concerns on one Embodiment of this invention. It is a figure for demonstrating the manufacturing method of the structure based on one Embodiment of this invention. It is a schematic diagram which shows the film-forming apparatus using the aerosol deposition method. It is a figure which shows the relationship between the thickness of an intermediate | middle layer, and the film-forming rate of the PZT layer formed by AD method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Substrate 11 Intermediate layer 12, 15 Titanium layer 13, 16 Platinum layer 14 PZT layer 21 Raw material powder 22 Aerosol generation container 23 Carrier gas introduction part 24 Aerosol derivation part 25 Vibrating part 26 Deposition chamber 27 Exhaust pipe 28 Nozzle 29 Movable stage

Claims (7)

Forming an intermediate layer on a main surface of the substrate with a material that can be removed by thermal oxidation;
A step (b) of forming a brittle material layer on the intermediate layer using at least a spray deposition method in which a powder of a material is sprayed and deposited at a high speed toward the lower layer;
Removing the intermediate layer from the structure by thermally oxidizing and removing the intermediate layer (c);
The manufacturing method of the structure which comprises this.   The method of manufacturing a structure according to claim 1, wherein the intermediate layer includes a polymer that is decomposed by thermal oxidation.   The method of manufacturing a structure according to claim 2, wherein the intermediate layer is formed of a photoresist material.   The method for manufacturing a structure according to claim 1, wherein the intermediate layer has a thickness of 2.4 μm or less.   The method for manufacturing a structure according to claim 1, wherein the intermediate layer has a thickness of 1.0 μm or less.   Step (b) includes forming a brittle material layer by forming a conductor layer on the upper layer of the substrate and spraying and depositing a powder of material toward the conductor layer at a high speed. The manufacturing method of the structure of any one of Claims 1-5.   The method for manufacturing a structure according to claim 1, wherein the brittle material layer includes a dielectric.

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