JPS60145715A - Production of substrate for forming piezoelecric resonator - Google Patents

Abstract

PURPOSE:To attain an UHF band resonator of good characteristics by polishing a resonator forming substrate, which is stuck to a supporting substrate, into a parallel thin plate and opening a window on the supporting substrate without influeneces upon this thin plate-shaped substrate. CONSTITUTION:A supporting substrate 10 and a piezoelectric substrate 11 for forming the resonator are stuck to each other by an adhesive layer 12. The outside face of the substrate 11 is polished until the substrate 11 becomes a parallel plane thin plate having a required thickness as the resonator. A resist film 13 is formed on the surface of the thin plate 11 by application, and a window 17 is opened in a part of a resist film 13 on the surface of the supporting substrare 10. The part exposed to the window 17 of the substrate 10 is removed to form a window 9. the exposed part due to the window of the adhesive layer 12 and resist films 13 are removed by the method having less influences upon the substrate 11. Next, electrodes 5 and 6 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a substrate for forming a piezoelectric resonator which is used for forming a substrate for a piezoelectric resonator operating in the frequency range V (1<tE). Piezoelectric resonators are small, have a low Q value, and provide safe air resonance characteristics, so they have been used as control elements for helmet vibration frequencies and as elements for air filters.

The operating frequency range of the piezoelectric resonator was traditionally limited to VHFHF, but in recent years UHF piezoelectric resonators have become increasingly popular and are being gradually developed1.The operating frequency of the piezoelectric resonator depends on the thickness of the substrate. Since it is inversely proportional, in order to realize a resonator in the Ul-iF band!'i < y, it is necessary to fabricate an extremely thin substrate with a thickness of about 10 μm or less. Several methods are known.

In other words, Figure 1 shows a conventionally known structure fr'i as a sliding-pressure eye resonator for UHF m with 7J combs, the upper surface of silicon substrate 1 and 1l-(';'and that i1 silicon oxide layer (
An electrode 1 (Si'021) 2 and 3 is formed on the silicon oxide layer 2, and a piezoelectric thin film 4 is formed on the electrode film 5. : is, piezoelectricity/i
9? , 40 through which the electrode lI is partially oriented with 5,
5 is formed. To produce this,
The silicon substrate 1 in the form of a parallel plate is thermally or chemically treated to form two Sl layers 2 and 3 on the surface of the substrate, and then a part of the SiO2 layer on one side is chemically etched. After removing the SiO2 layer, the unexposed 7917-layer substrate 1 exposed in the area where the SiO2 layer was removed was removed by etching to open a window 9, making use of the apparent difference in etching speed between Noricon and silicon oxide. So only 5102 layer 2 is window 9
This is used as a substrate for forming a composite resonator. Opposing portions of the thin electrode films 5 and 6 are located at a portion 9.

This structure is known as a Noricon diaphragm structure, in which impurities are diffused into the silicon substrate 1 instead of Si+21@2, and the etching speed of the non-diffused layer and the spreading layer is increased. A method of leaving only the impurity diffusion layer in the window portion using one layer is also used.

To make a resonator, a temporary resonator is formed by providing electrodes 5, 6 and a piezoelectric thin film 4 on the 5IO2 layer 2a or the impurity diffusion layer in the core 9 portion formed by the method described above.

The above-mentioned structure is S@ which forms a composite resonator, but there is also a known method in which a part of the piezoelectric substrate 7, such as crystal, is shaped into a thin plate, as shown in FIG. That is, in FIG. 2A, a resist film 8 is formed on one surface of a piezoelectric substrate such as crystal, and a substrate 7 is formed through the edges of the resist film 8.
is removed by a method such as etching or ion beam sputtering to make it thinner than the surrounding area, and as shown in Fig. 2B, electrodes 5 and 6 are provided on both sides of the plate-shaped portion 7a to generate resonance. form a child;

According to the method shown in FIG.
However, as mentioned above, the material used for the thin plate substrate 2a is limited to 5i02 or silicon with impurities diffused into a high gap.
has no piezoelectricity. Therefore, in order to construct a resonator, it is safe to use the piezoelectric thin film 4 as an N, 17-coupled resonator. The properties of the first resonator are determined by the substrate material, pressure thin film material, etc. In the method shown in Figure 1, the substrate 2
Since it is not possible to arbitrarily change the width of 4 of a, it is possible to obtain an F-band resonator with good temperature characteristics and good resonance characteristics such as high Q. ID: 11 button.

-')-7. In the method shown in Figure 2, the piezoelectric material is
Is it possible to do 711H machining on a? It takes a long machining time and is it an Iyl axis? One thing is that when processing, there are problems such as the fineness of the thickness and the poor quality of the finish, and the roughness of the surface. .

A of the Invention (Zet-Kyo) This invention enables the production of a substrate for forming a piezoelectric resonator that is precisely processed into a thin rod shape7 and has strong support. This makes it possible to realize a -UH) band resonator with good characteristics.

According to this invention, a piezoelectric resonator forming substrate having 911 pieces of piezoelectric resonator formed in a planar shape is attached to a flat surface of a support substrate, and the piezoelectric resonator forming phase νiI4σt IL is parallel to A piezoelectric resonator forming substrate is made into a thin plate, and a window is opened in the supporting substrate without affecting the thin plate shaped piezoelectric resonator forming substrate, and the piezoelectric resonator forming substrate is processed into a parallel thin plate shape by U = tt. Let it remain.

<Example> FIG. 3 shows the steps of Example 1 of the present invention.

Step A: A piezoelectric substrate for forming a resonator, consisting of a supporting nose plate 10 made of metal or glue, which is precisely finished to have one side flat, and a quartz crystal, which is precisely finished to be flat on one side. 11 are finished by pasting them together with an adhesive layer 12 with their edges facing each other. At this time, 1 of each board 10.11
1 is due to the stress added during the bonding work.
;I will prepare myself sufficiently so that I can stand up to you. Regarding the thickness of the multi-plate 10, the flexibility described in step B is added.

If the curve is on both sides of the bonded substrate obtained in Step B1@A or on the side of the piezoelectric substrate 11 for forming the ij resonator,
Then, process it so that the base 7.11 becomes a resonator with a thickness of n-mugi and a V-plate shape.

In addition, Ryōsōpaku + Jt rM ;! In the case of li6, the size of the supporting substrate 10 will be smaller, so the piezoelectric substrate 1 for forming a resonator will be
Set the thickness of base &10 so that it has a strong r of +5± for 1, leaving a considerable 117-strength 1-5.1, Step C1; Resist film 13 on the surface of 11
A solution 17 is opened in a part of the resist 11ii' and 13 on the support substrate 10iI++ side.

The window 9 is formed by removing the portion of the supporting base 10 that has been exposed on the edge 17 by a physical or chemical method such as chemical etching or sputter etching. The river gas used is one that has a small etching effect on the piezoelectric substrate 11 for forming a resonator.

Next is adhesion J! 12 and the resist film 13 exposed by the windows 9 are removed by a method that has a small effect on the piezoelectric substrate 11 for forming a resonator.

Through the above steps, the piezoelectric substrate 11 for forming a resonator formed in a rectangular shape is placed in the window 9, and the support laminate 10 around the window 9 can be used as a support. .

Process F2. 'The electrodes 5 and 6 are arranged on both sides of the piezoelectric substrate 11 for forming a resonator in the form of a thin plate, so that the resonance f is arranged in the pattern, and the substrate 11 is shifted by 1°.
74 crystal, tantalum 1-solithium or niobium lithium can be used as the material, and by steps A~1] Since it can be processed into an extremely thin substrate of about n size, it is possible to realize a UHF' band common emitter without using a composite resonator configuration as shown in step E. If a mechanical polishing method such as latching or poly/ink is used in the temporary processing step B, the thickness can be monitored during the polishing process, making it easy to adjust the thickness. Therefore, it is possible to obtain a very good processing direction, and a resonator with good characteristics can be realized. 3. FIG. 4 shows a second embodiment of the present invention, which is an example of forming a harmonic pendulum. In step A, a composite resonator forming base plate 14 made of an elastic material such as sapphire or fused crystal is attached to a supporting substrate 10. paste. Others are steps A to I) 4': l: Lower pestle A to D of Example 1
The process is similar to the above, and the thin plate-like substrate 14 is connected to the window 9 at the step of the process.
9. In step E, a small pole 5, a piezoelectric thin film 4, and an electrode 6 are sequentially provided on the thin plate substrate 14'' in the window 9 portion, thereby constructing a composite resonator. In this second embodiment, since any material can be used for the substrate 14, fQ j
You can breed J things that are C. For example, if a high Q is important, use the substrate 14. When performing step B in Examples 1 and 2 of AilσL, is it okay to grind only the substrate 11 or 14? The polishing method is more advantageous in terms of mass production and finish accuracy such as parallel length.1. At that time, the substrates 10 and 1
If the polishing speed of the substrate 1 is different, the thickness of the substrate 1 tends to vary.

In addition, d) It is desirable that materials with the same polishing characteristics exhibit Q on both sides. FIG. 5 is a diagram showing such a case, in which the support substrate 11 is used as a support substrate in step A. Similarly, a piezoelectric substrate 1 is attached to the opposite side of the dummy substrate 15 from the tummy substrate 15 of the substrate 10, except that a dummy substrate 15i having one-party property is attached with a
Paste 1. At the same time, the substrates 11 and 15 are attached to the substrate 10 (
It is also possible to paste them together. Next, in step B, both sides of the three-layered substrate are polished to form a substrate 11? After removing the thickness of the FyT layer by polishing or etching the substrate 15 and adhesive TtIi12'' in step C, the I rod 1)
If you are applying resist, open the window first, and then open the window 17 with
Remove dust from the substrate 10, adhesive layer 12,
The resist film 13 is removed, and then step FT44jB5.
6 is provided on the substrate 11 at the window 9 portion to form a resonator.

According to this method, the substrates 11 and 15 are polished at the same time and at the same speed in polishing process B, so the amount of polishing of the substrate 11 is 1/2 of the total amount of polishing, which allows for easy thickness control and high finishing accuracy. I get caught.

FIG. 6 shows a fourth embodiment of the invention. When the dummy substrate 16 is made of the same material as the composite resonator substrate 14 made of an elastic material such as sapphire or fused crystal, or has the same abrasiveness as the substrates 1 to 4, the manufacturing steps A to E are as shown in FIG. This corresponds to steps A-E in Example 3. In step F, a composite resonator is formed by sequentially providing the electrode 5, piezoelectric thin film 4, and electrode 6 on the composite resonator substrate 14 in the window 9 portion.

In Examples 3 and 4, the termi substrates are all removed in step C, but the dummy substrates 15.16 and the adhesive layer 12' are removed without removing the dummy substrates 15.16 in step C. Alternatively, a method may be used in which a window is opened in the first step and a core is opened in the supporting substrate 10 and the adhesive layer 12. In this case, the tummy substrates 15 and 16 remain around the window 9, but this does not pose any problem in forming the resonator.

Next, according to the third embodiment shown in FIG. 5, the fundamental resonance frequency is 500.
An example of manufacturing a crystal resonator of 1vII(zI(z) will be described.

A (1'OO) silicon plate with a thickness of 300 μηL was used as the substrate 10, and a BT cut crystal plate with a thickness of 60 μm was used as the substrates 11 and 15, respectively.
, 12' have a thickness of about 3 μm [attached with W]. As a result, a three-layer laminated board with a thickness of 426 μm was obtained. When this is processed to a thickness of 316 μm by simultaneous polishing of both sides, the thickness of both substrates 11 and 15 becomes 5 μm. An ammonium fluoride solution is used for etching the crystal substrate 15 for the tammy, and a PED solution known as an anisotropic etching solution is used for etching the silicon substrate, while the adhesive layers 12 and 12' are removed by plasma ashing. . As a result, a BT-cut crystal substrate with an area of about 1 mm and a thickness of 5 μm is formed in the window 9, and the fundamental frequency is 500 MHz.
It is possible to realize a resonator that is stable against the temperature of 15 Gt (z) due to the third overtone.Also, the resonance Q value can be close to the Q value of the crystal material. Since the part is supported by the silicon plate 10 having sufficient strength 1, it is of course easy to handle and resistant to vibrations, shocks, etc.

<Effects> As invented above, the method of manufacturing a substrate for forming a piezoelectric resonator according to the present invention allows any substrate to be formed into a thin plate shape with a finish of 14 degrees, regardless of the material, so temperature characteristics, resonances such as Q + 1 temperature, etc. can be improved. It is possible to realize a UHF band resonator with good characteristics.

[Brief explanation of the drawing]

ili Figure 1 is a cross-sectional structural diagram showing Kengo's Kaigoi pressure tome resonator, Figure 2 is a cross-sectional diagram showing a conventional method of forming a thin plate-like substrate, and Figure 3 is a piezoelectric resonator according to the present invention. Rikihaku IIi diagram showing the process of [Example of manufacturing method of forming substrate],
FIG. 4 and FIG. 6 are cross-sectional views showing the steps of implementation side 1 of (I+?) of the present invention. 1: Silicon base &, 2, 3: Silicon supply layer, 4: Compression property N Hakame film, 5, 6: electrode film, 7: piezoelectric, sexual group + a, 8 resist film, 9: window, 1o: supporting substrate, 11: piezoelectric 1 substrate for resonator formation, 12.12°: contact layer , 13 resist film, 14: substrate for piezoelectric resonator formation, 15, 16: termi substrate. Agent Takashi Higashino 74 Tsui 5 Figure A 75 Figure B O 6 Figure A 76 Figure B

Claims (2)

[Claims] (1) A bonding process in which a piezoelectric resonator forming substrate with one side processed into a flat shape and a supporting substrate with one side processed into a flat shape are bonded together with their flat surfaces facing each other. , a polishing process in which the piezoelectric resonator imaging number plate is polished in the bonded state to make the piezoelectric resonator forming substrate into a parallel frozen cedar shape; The support substrate is processed in a manner that does not affect the resonance/preformation substrate, and only the piezoelectric resonator formation substrate processed into the parallel thin plate shape is placed inside the opening. 1. A method for manufacturing a substrate for forming a piezoelectric resonator, comprising 10 steps in which remaining steps are required. (2) The supporting base plate described in H is the first plate whose both sides are flat.
A dummy substrate with one side processed into a flat surface is bonded to one surface of the substrate, and the bonding process is performed on the surface opposite to the surface to which the tummy staff is bonded. Pressure "P@@" is the process of assembling the resonator with the resonator board, which is the first step of the LP4f questionable mechanism.