JPS5988618A - Manufacture of overhung beam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (a) Field of the Invention This invention relates to, for example, a thin film ultrasonic sensor, an accelerometer,
The present invention relates to a method for manufacturing a thin film cantilever beam (unimorph cantilever beam) used in electro-mechanical vibrators such as vibration sensors, piezoelectric relays, and optical modulators.

(b) Prior art and its problems Conventionally, one of the methods for manufacturing a thin film type unimorph cantilever is to form a silicon dioxide (SiO2) cantilever and then sputter a piezoelectric thin film onto 5i02. There is a way to form it. However, this type of manufacturing method has a problem in that the five cantilevers are bent due to distortion caused by sputtering during the process of forming the piezoelectric thin film. Such defects occur due to subtle changes in conditions during sputtering.

This is caused by a variety of factors, and it has been extremely difficult to eliminate or control it. Therefore, in order to solve this problem, a method is proposed in which a piezoelectric thin film is not formed by sputtering on a cantilever beam, but a piezoelectric thin film is formed by sputtering on a silicon dioxide beam, and then a cantilever beam is obtained. Conceivable.

By the way, the conventional method of obtaining a cantilever beam of silicon dioxide, for example, is to use a silicon (Si) crystal substrate 1-L with a plane orientation (100) as shown in FIG.

A silicon dioxide film 4 having a substantially U-shaped opening 2 and a convex long side 6 corresponding to the U-shaped recess of this opening 2 is formed, and anisotropic etching is performed from this opening 2. , a silicon dioxide cantilever beam 5 whose longitudinal direction is in the <110> direction.
I'm trying to get it.

In this case, since etching in the direction of the (i i Over-etching of silicon to the lower part of the silicon dioxide film 4 other than the long side portion 6 having a width does not occur. That is, the convex corner 3a
A cantilever beam 5 is formed by the shape of the silicon dioxide film 4 having the shape.

Here, in order to obtain the above-mentioned double-sided beam of silicon dioxide film, if we consider the case where the long sides are extended and bridged as shown by the dotted lines in Figure 1, the long sides as when creating the 5 cantilever beams are Since the convex corner groove a of part B is eliminated, even if etching is performed, the long side part 6, that is, the silicon dioxide that should become the double-supported beam, will not be etched downward, and it will not be possible to obtain the double-supported beam after all. When it became impossible to obtain a beam supported on both sides, a piezoelectric thin film was formed by sputtering using nine beams each supported on both sides.

[The method of obtaining a cantilever beam after 7 steps is also unfeasible.

In view of the above, the purpose of the present invention is to first realize the creation of a double-supported beam by anisotropic etching, and to change the state of this double-supported beam to -[-
In step 7), a piezoelectric thin film is formed and 4 beams are obtained. An object of the present invention is to provide a method for manufacturing a cantilever beam that does not cause distortion due to sputtering or the like.

B) Structure and Effects of the Invention In order to achieve the above object, the method for manufacturing a cantilever beam of the present invention is to fabricate a cantilever beam on a silicon substrate with a plane orientation of (100).

a long side portion for forming a cantilever in the axial direction (110>);
first and second openings provided on both sides of the long side; two supporting sides formed by separating one end of the long side; and four overlapping sides of the long side. forming a coating (for example, silicon dioxide) having a sixth opening having a width wider than the width of the side portion;

Further, a piezoelectric thin film is formed on each side of the coating,
Anisotropic etching is performed through each of the openings before or after the formation of the piezoelectric thin film.

After the formation of the piezoelectric thin film and the anisotropic etching are completed, the support portion including the silicon substrate and the piezoelectric thin film is cut in a direction including the width direction of the sixth opening to obtain a cantilever beam. That's what I do.

According to the method for manufacturing a cantilever beam of the present invention, the width of the sixth opening provided at the tip of the long side is made υ larger than the width of the long side, so that a convex shape is formed at the tip of the long side. Corners are formed, and etching progresses below the long sides and supporting sides to obtain a double-supported beam.

Then, before cutting the silicon substrate and supporting side along a plane including the width direction of the sixth opening 1'' to form a cantilever beam.

Since the piezoelectric thin film is formed on the long side portions and the branch portions, the possibility of distortion occurring due to sputtering or the like during formation of the piezoelectric thin film is eliminated. The bending of the tip of the cantilever beam can be reduced.

The sensor's common characteristics and directivity can be improved,
Furthermore, when the cantilever beam obtained by implementing the present invention is applied to a piezoelectric relay or an optical modulator, the amount of tip displacement can be easily controlled. The yield rate during manufacturing can be greatly improved.

0→Description of Embodiments The present invention will be described in detail below with reference to embodiments shown in nine drawings.

FIG. 2 is a perspective view of an element in which the invention is implemented. A method for manufacturing a cantilever beam will be described below with reference to the element shown in this figure. In the figure, reference numeral 11 denotes a silicon single crystal substrate with a (100) plane orientation, and silicon dioxide 12 is formed on this silicon substrate 11. Then, line up this silicon dioxide 12.

Patterning is performed by conventional photolithography and etching processes. Patterning results.

The silicon dioxide 12 has a long side portion 13 whose longitudinal direction is in the <110> direction. Openings 14, 15 arranged on both sides of this long side. 1] Supporting sides 16 and 17 provided separately at one end of the long side, and supporting sides 16 and 17 teL
! Lj, i, long side 13t7) width direction (7) 'lW*
2 characteristically has an opening 18 larger than the width W1 of the long side portion 13.

Next, the silicon substrate 11 is etched through the openings 14 and 15.degree. 18 using an anisotropic etching solution such as an aqueous solution of ethylenediamine and pyrocatechol. The etching progresses from the openings 14, 15, 18, respectively, and as it progresses, the convex corners 19, 20 of the supporting sides 16 and 17
Etching also progresses to the lower part of the support side 16, 17, and the lower part of the silicon dioxide 12 has a space 2 shown in FIG.
1 occurs. The etchings of the openings 14 and 15 and the etchings of the opening 18 are connected at the bottom to form a convex corner 22.
．． 23i is formed. As the etching progresses further from these corners 22 and 23, as shown in FIG.
is formed.

After this, the long side portion 131. An electrode and a piezoelectric thin film are formed on the support portion i6.17, and finally, cutting is performed using a laser beam or the like at A-A shown in FIG. 2 to obtain one entire cantilever beam.

FIG. 5 is a perspective view of the device manufactured as described above. In the figure, 26 is a lower electrode formed on the silicon dioxide 12, and 2'? is the piezoelectric 41 area sandwiched between the lower electrode 26 and the upper electrode 28.

These silicon dioxide12. Lower electrode 26. Long side portion 13 formed by piezoelectric thin film 2'i7 and upper electrode 28.
Cantilever beam 29. at supporting side 16.17. By applying a voltage to the lower electrode 26 and the upper electrode 28, the tip of the cantilever beam 29 vibrates.

In addition, in Example 21, the formation of a piezoelectric thin film was performed.

Although the case where the piezoelectric film is formed after the anisotropic etching is explained above, the piezoelectric thin film may be formed before the anisotropic etching.

Further, in the above embodiment, 21-doped silicon is used as the layer to be formed on the silicon substrate, but instead of this, high-concentration K (1019 pieces/cA) boron-doped silicon may be used, or V silicon doped with silicon. Molybdenum y(”)+ on the board
ri o −1, (cr), IZ tanta/l/(Ta
) may be vapor-deposited. When a metal vapor deposited corrugated film is used, the lower electrode 26 in FIG. 5 is unnecessary.

[Brief explanation of drawings]

FIG. 1 is a side view of a cantilever beam produced by a conventional manufacturing method. FIG. 2 is a perspective view of an element in which the invention is implemented. 5 and 4 are perspective views showing the progress of etching of the device, and FIG. 5 is a side view of the device manufactured by the manufacturing method of the present invention. 11: Silicon substrate, 12: Silicon dioxide. 1ro: long side, 14, 15, 18: opening. 16/17: Support part, 2q: Piezoelectric thin J model. 29: Cantilever beam. Patent Applicant Tateishi Electric Co., Ltd. Representative Patent Attorney Shigeru Nakamura M1 Figure M2 Figure 3 Figure 2I Bud 4 Figure 5

Claims (1)

[Claims] (1) On a silicon substrate with plane orientation (100), axial orientation <
A method for manufacturing a cantilever beam, comprising forming a cantilever beam made of a piezoelectric thin film and a coating whose longitudinal direction is arranged at i io>. A long side portion forming the cantilever, first and second openings provided on both sides of the long side portion, and one end of the long side portion separated from each other are formed on the silicon substrate. forming a coating having two supporting sides; and a sixth opening surrounded by the supporting sides and having a width wider than the width of the long side; A piezoelectric thin film is formed thereon, and before or after the formation of the piezoelectric thin film, anisotropic etching is performed through each of the openings, and after the formation of the piezoelectric thin film and the anisotropic etching are completed, the sixth A method for manufacturing a cantilever beam in which the intersection portion including the silicon substrate and the piezoelectric thin film is cut in a plane including the width direction of the opening.