JP2008182297A - Method for manufacturing piezoelectric wafer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a piezoelectric wafer by which the piezoelectric wafer can be processed thin to a uniform thickness. <P>SOLUTION: The method comprises: a sticking stage of sticking one main surface 11 of a crystal wafer 10 having main surfaces formed into mutually parallel planes on one plane portion 21 of a base member 20; a film forming stage of forming an anticorrosive film 30 on at least a flank 13 of the crystal wafer 10 stuck on the base member 20 and the other plane portion 22 and flank 23 of the base member 20; an etching stage of etching the other main surface 12 by dipping the crystal wafer 10 stuck on the base member 20 and having the anticorrosive film 30 formed in an etchant 40; an anticorrosive film peeling stage of peeling the anticorrosive film 30 at least off the crystal wafer 10 after the etching stage; and a wafer peeling stage of peeling the etched crystal wafer 10 off the base member 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a piezoelectric wafer, and more particularly to a method for manufacturing a piezoelectric wafer in which a piezoelectric wafer is thinly processed.

Conventionally, a method for thinly processing a piezoelectric wafer is manufactured by a photolithographic process in which a thick frame body portion is left at the outer peripheral edge portion of the piezoelectric wafer and a thin plate region integrated with the frame body portion is formed at the center portion. A method is known (see, for example, Patent Document 1).
As another method, a manufacturing method is known in which a silicon plate and a glass plate are bonded and polished to a parallel plane, and the quartz plate is bonded to the silicon plate, and the quartz plate is polished and thinned ( For example, see Patent Document 2).

JP 2006-262005 A JP-A-8-46475

According to the manufacturing method disclosed in Patent Document 1, the piezoelectric wafer is reinforced by supporting the thin plate region in the central portion of the piezoelectric wafer with the thick frame body portion in the outer peripheral edge portion. Is formed.
However, in the above manufacturing method, when the thin plate region of the piezoelectric wafer is successively thinned, there is a limit in supporting the thin plate region with the frame portion and performing necessary reinforcement on the thin plate region.
For this reason, in the manufacturing method described above, the thin plate region of the piezoelectric wafer may be damaged by an external force applied during processing.

In addition, the manufacturing method disclosed in Patent Document 2 includes a quartz plate (hereinafter referred to as a piezoelectric wafer) bonded to a plate (hereinafter referred to as a base member) in which a silicon plate and a glass plate are bonded together to a polishing apparatus. Attaching and polishing the piezoelectric wafer.
According to the above manufacturing method, for example, if the accuracy of the parallelism of the base member is poor, the piezoelectric wafer bonded to the base member is polished while being inclined with respect to the polishing surface of the polishing apparatus. The accuracy of the parallelism becomes worse.
In addition to the above, the above manufacturing method has various accuracy factors such as the flatness accuracy of the base member, the bonding accuracy between the piezoelectric wafer and the base member, and the mounting accuracy to the polishing apparatus. Affects the accuracy of wafer parallelism and flatness.

  The present invention pays attention to the above-mentioned problems, and the piezoelectric wafer is difficult to break during processing, and the accuracy of the parallelism and flatness of the piezoelectric wafer after processing is various other than the accuracy of the parallelism and flatness of the piezoelectric wafer itself. There is provided a method for manufacturing a piezoelectric wafer capable of thinly processing a piezoelectric wafer with a uniform thickness without being affected by various precision factors.

  In order to solve the above-mentioned problems, a method for manufacturing a piezoelectric wafer according to the present invention is a method for applying one main surface of a piezoelectric wafer having main surfaces formed in parallel and flat to one flat portion of a base member. A step of forming a corrosion-resistant film on the side surface of the piezoelectric wafer affixed to the base member, and the other flat surface and side surface of the base member; An etching step of immersing the piezoelectric wafer formed with the etching solution to etch the other main surface, and after the etching step, a corrosion-resistant film peeling step of peeling the corrosion-resistant film from at least the piezoelectric wafer; And a wafer peeling step for peeling the piezoelectric wafer from the base member.

According to the above, in the method for manufacturing a piezoelectric wafer, the piezoelectric wafer is etched in a state where the piezoelectric wafer is attached to one flat surface portion of the base member.
As a result, the piezoelectric wafer manufacturing method can process the piezoelectric wafer while being reinforced by the base member, thereby avoiding damage due to external force during the processing of the piezoelectric wafer.

Further, in the piezoelectric wafer manufacturing method, since the corrosion-resistant film is formed on the side surface of the piezoelectric wafer, the etching is performed from the other main surface without being etched from the side surface of the piezoelectric wafer.
As a result, the piezoelectric wafer is etched with a uniform thickness over the entire area of the other main surface while securing the outer shape.
For this reason, in the piezoelectric wafer in which the main surfaces are formed parallel to each other and flat, the main surfaces are parallel to each other and flat after etching.
As described above, in the method for manufacturing a piezoelectric wafer, the accuracy of the parallelism and flatness of the piezoelectric wafer after etching is the same as that of the conventional method. It is possible to avoid the influence of the alignment accuracy, the mounting accuracy to the polishing apparatus, and the like.

  Hereinafter, an embodiment of a method for manufacturing a piezoelectric wafer according to the present invention will be described with reference to the drawings, taking a crystal wafer as an example of the piezoelectric wafer.

FIG. 1 is a process explanatory view showing a processing step by the piezoelectric wafer manufacturing method of the present embodiment, FIG. 1 (a) is a perspective view for explaining a sticking process, and FIG. 1 (b) is a film forming process. FIG. 1A is a cross-sectional view taken along line AA in FIG. 1A, FIG. 1C is a cross-sectional view at the same position as FIG. 1B, illustrating the etching process, and FIG. These are perspective views explaining a wafer peeling process.
In addition, the dimension ratio of each component is expressed with a ratio different from the actual ratio for easy understanding of the drawings.

First, in the attaching step, as shown in FIG. 1 (a), either one of the main surfaces 11 of the quartz wafer 10 as a piezoelectric wafer is bonded to an unillustrated UV-curable adhesive or the like. Affixed to one flat surface portion 21 of the base member 20.
The quartz wafer 10 is previously formed in a predetermined shape, thickness, and surface state in the previous process. In the case of this embodiment, the quartz wafer 10 has a thickness of about 100 μm, the main surfaces 11 and 12 are parallel and flat to each other, and the main surfaces 11 and 12 are mirror-finished.
Note that the thickness of the quartz wafer 10 and the surface states of the main surfaces 11 and 12 are not limited to this, and are appropriately set according to the application.

The base member 20 is made of a plate material such as quartz, and is previously formed in a predetermined shape, thickness, and surface state in the previous process. In the case of the present embodiment, the base member 20 has a thickness of about 1 mm, and the one surface portion 21 to which the crystal wafer 10 is attached is mirror-finished.
Further, the planar shape of the base member 20 is formed in substantially the same shape as the quartz wafer 10.
Note that the shape, thickness, surface state, and the like of the base member 20 are not limited to this, and are appropriately set according to the shape, thickness, the state of the main surfaces 11, 12, the use, and the like of the crystal wafer 10. .

Next, in the film forming step, as shown in FIG. 1B, at least the entire circumference of the side surface 13 excluding the other main surface 12 of the crystal wafer 10, and the other flat portion 22 and the side surface of the base member 20. The corrosion resistant film 30 is formed on the entire circumference of the film 23 by a sputtering apparatus or the like.
The corrosion-resistant film 30 is made of a metal film in which a metal such as gold having corrosion resistance against an etching solution described later is laminated on a base layer made of chromium.
When the corrosion-resistant film 30 is formed, the other main surface 12 of the quartz wafer 10 is placed in close contact with the placement surface of the sputtering apparatus, whereby the other main surface 12 is masked. Thereby, the corrosion-resistant film 30 is not formed on the other main surface 12 of the quartz wafer 10.

Next, in the etching step, as shown in FIG. 1C, the quartz wafer 10 and the base member 20 which are attached to the base member 20 and formed with the corrosion-resistant film 30 are made of hydrofluoric acid or hydrofluoric acid and ammonium fluoride. It is immersed in an etching tank 41 in which an etching solution 40 such as a mixed solution is stored.
After the immersion, the quartz wafer 10 and the base member 20 are swung to etch the quartz wafer 10 with respect to the other main surface 12 until a predetermined thickness is reached.

Thus, the quartz wafer 10 is etched with a uniform thickness over the entire area of the other main surface 12 while securing the outer shape.
As a result, the quartz wafer 10 is thinned to a predetermined thickness while maintaining the main surfaces 11 and 12 in a parallel and flat state. In the case of this embodiment, the thickness of the crystal wafer 10 after etching is set in the range of several tens μm to several μm.
At this time, since the corrosion-resistant film 30 is formed on the side surface 13 of the crystal wafer 10, the crystal wafer 10 is not etched from the side surface 13.

  Next, in the corrosion-resistant film peeling step, the quartz wafer 10 and the base member 20 are immersed in a peeling solution, and the corrosion-resistant film 30 is peeled from the quartz wafer 10 and the base member 20.

Next, in the wafer peeling process, as shown in FIG. 1D, the etched quartz crystal wafer 10 is peeled from the base member 20 by dissolving the adhesive with a solvent or the like.
After peeling, the crystal wafer 10 is immersed in a pure water tank in which pure water is stored, washed and dried.
As described above, the quartz wafer 10 processed thinly with a uniform thickness is obtained.

Depending on the application, the base member 20 may be provided with a function other than reinforcement, and the crystal wafer 10 may be used without being peeled off from the base member 20.
Further, depending on the application, the crystal wafer 10 and the base member 20 may be separated after being divided into a plurality of pieces by a dicing apparatus or the like.

  The crystal wafer 10 processed by the above manufacturing method can be used as an optical component such as a wide viewing angle film of a liquid crystal projector, for example. Further, it can be used as a crystal vibrating piece constituting a crystal oscillator, a crystal resonator, or the like after a post-process such as excitation electrode formation.

As described above, in the method for manufacturing a piezoelectric wafer according to the present embodiment, the crystal wafer 10 is etched in a state where the crystal wafer 10 is attached to one flat surface portion 21 of the base member 20.
As a result, in the method for manufacturing a piezoelectric wafer, the crystal wafer 10 is processed in a state in which the crystal wafer 10 is reinforced by the base member 20, so that damage due to an external force during processing of the crystal wafer 10 can be avoided.

Further, in the piezoelectric wafer manufacturing method, since the corrosion-resistant film 30 is formed on at least the side surface 13 of the crystal wafer 10, the etching is performed from the other main surface 12 without being etched from the side surface 13 of the crystal wafer 10. .
Thus, the quartz wafer 10 is etched with a uniform thickness over the entire area of the other main surface 12 while securing the outer shape.
Therefore, in the quartz wafer 10 in which the main surfaces 11 and 12 are formed parallel to each other and flat, the main surfaces 11 and 12 become parallel and flat after etching.

  As described above, in the method for manufacturing a piezoelectric wafer, the accuracy of the parallelism and flatness of the crystal wafer 10 after etching is the same as the accuracy of the parallelism and flatness of the base member 20, and the crystal wafer 10 and the base member are conventional. It is possible to prevent the influence other than the accuracy of the parallelism and flatness of the quartz wafer 10 itself, such as the bonding accuracy with respect to 20.

Further, the piezoelectric wafer manufacturing method places the other main surface 12 of the crystal wafer 10 so as to be in close contact with the mounting surface of the sputtering apparatus when the corrosion-resistant film 30 is formed. Masked.
As a result, the method for manufacturing a piezoelectric wafer eliminates the need for forming a mask pattern for masking a portion of the quartz wafer 10 where the corrosion-resistant film 30 is not formed, and therefore, compared with a conventional manufacturing method using a photolithography process. Thus, the number of processing steps can be reduced.

In the piezoelectric wafer manufacturing method of the present embodiment, the piezoelectric wafer is the crystal wafer 10, but the present invention is not limited to this, and the piezoelectric wafer may be lithium tantalate, lithium niobate, or the like.
Further, when the crystal wafer and the base member are bonded, they may be directly bonded without using an adhesive or the like.
The base member may also be a glass other than quartz or a quartz wafer as the base member.

Process explanatory drawing explaining the processing process in the manufacturing method of the piezoelectric wafer of this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Crystal wafer as piezoelectric wafer, 11 ... One main surface of crystal wafer, 12 ... Other main surface of crystal wafer, 13 ... Side surface of crystal wafer, 20 ... Base member, 21 ... One plane part of base member , 22 ... the other flat surface of the base member, 23 ... a side surface of the base member, 30 ... a corrosion-resistant film, 40 ... an etching solution, 41 ... an etching tank.

Claims (1)

A pasting step of pasting one main surface of the piezoelectric wafer, the main surfaces of which are parallel and flat to each other, to one flat portion of the base member;
A film forming step of forming a corrosion-resistant film on the side surface of the piezoelectric wafer affixed to the base member and the other flat portion and side surface of the base member;
An etching process in which the piezoelectric wafer attached to the base member and having the corrosion-resistant film formed thereon is immersed in an etching solution to etch the other main surface;
After the etching step, a corrosion-resistant film peeling step for peeling the corrosion-resistant film from at least the piezoelectric wafer;
A method of manufacturing a piezoelectric wafer, comprising: a wafer peeling step of peeling the etched piezoelectric wafer from the base member.

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