JPH101400A - Manufacture of silicon vibrator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacture by which an Si vibrator having good adhesion to a base substrate and high vibrating element characteristics can be manufactured in a good yield. SOLUTION: In this manufacture, on one surface of an n-type Si substrate 1 shown in (a) of the figure, a p-type Si layer 2 is formed (as shown in (b)) and then, a glass substrate 6 joined to the p-type Si layer 2 by anodic joining (as shown in (c)) and thereafter, the ntype Si substrate 1 is worked into a vibrator shape by subjecting the Si substrate 1 to polishing and reactive ion etching (as shown in (d) to (f). Then, a part of the p-type Si layer 2, that is located in the region of a vibrating section 11 having a vibrating element shape, is etched and removed to support the vibrator 13 by the glass substrate 6 so that the vibrating section 11 is apart from the glass substrate 6 by the thickness of the p-type Si layer 2, and thus, the objective Si vibrator is manufactured (as shown in (g)).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a Si vibrator used for an acceleration sensor, a vibrating gyroscope and the like.

[0002]

2. Description of the Related Art Si vibrators are used in, for example, acceleration sensors and vibrating gyroscopes. As shown in FIG. 2, the vibrator 13 is formed by the substrate 3 having the vibrating portion 11,
A supporting portion 12 supporting the vibrating portion 11 is fixed to a base substrate (supporting substrate) 5 via a bonding layer 4. The vibrating part 11 is
It is spaced from the underlying substrate 5 by the thickness of the bonding layer 4,
For example, it vibrates as indicated by the arrow in FIG.

[0003] Among such vibrators, as a method of manufacturing a Si single crystal vibrator, "TECHNICAL DIGEST OF THE 13TH
SENSOR SYMPOSIUM, 1995.PP.161-164, A CAPACITIVE ACCE
LEROMETER USING SDB-SOI STRUCTURE "is known. The method of manufacturing the Si vibrator described in this document is as follows.

First, another Si single crystal substrate is bonded to the thermal oxide film of a Si single crystal substrate having a thermal oxide film of about 1 μm by a direct bonding method, and one side of the Si single crystal substrate is vibrated.
Polish to a height of 13. And S on the polished side
Using the i-single-crystal substrate as the substrate 3 and the unpolished Si single-crystal substrate as the base substrate 5, a photoresist pattern in the shape of the vibrator 13 is formed on the Si single crystal of the substrate 3, Si using ion etching (RIE)
The single crystal is processed vertically. Finally, the thermal oxide film in the vibrating portion region of the vibrator shape is removed using BHF (buffered hydrofluoric acid), washed with water, and dried, so that the vibrating portion 11 is removed from the Si single crystal substrate as the base substrate 5. Then, the thermal oxide film is processed to be floated by the thickness (about 1 μm).

[0005]

However, in the above method, the bonding layer (sacrifice layer) 4 is formed of a thermal oxide film (silicon oxide film) of a Si single crystal substrate, and its thickness is about 1 μm. The vibrating part 11 and the underlying substrate 5
In the drying stage after the RIE, sticking of the vibrating portion 11 (a phenomenon in which the vibrating portion 11 comes into contact with the base substrate 5) occurs, and the yield of the Si vibrator is reduced.

That is, in the method in which the bonding layer 4 is formed of a silicon oxide film as in the above method, since the thickness of the silicon oxide film formed by the thermal oxidation method is limited, the vibrating portion 11 and the underlying It is difficult to widen the distance from the substrate 5, and the above-described problem occurs. In order to increase the distance as much as possible, two Si single crystal substrates having a thermal oxide film are prepared, and the thermal oxide film side of these Si single crystal substrates is directly bonded. Although it is possible to manufacture a vibrator, even in this case, the distance between the vibrating portion 11 and the base substrate 5 can be at most doubled, and it is difficult to solve the above problem. . Further, when the thermal oxide films are directly bonded to each other, the substrate 3 on which the vibrator 13 is formed is peeled off from the base substrate 5 during RIE due to poor adhesion of the bonding surfaces. I will.

In these methods, since the substrate 3 and the base substrate 5 are both formed of a Si single crystal substrate, a parasitic capacitance is generated between the vibrator 13 and the base substrate 5, and There also arises a problem that the characteristics of 13 are deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to provide good adhesion between a substrate forming a vibrator and a substrate supporting the vibrator, and to have almost no parasitic capacitance. An object of the present invention is to provide a method of manufacturing a Si vibrator capable of manufacturing a Si vibrator with high yield.

[0009]

Means for Solving the Problems To achieve the above object, the present invention provides means for solving the problems by the following constitution. That is, in the present invention, a p-type Si layer is formed on one surface of an n-type Si substrate, and then the base substrate is joined to the p-type Si layer, and then the n-type Si substrate is processed into a vibrator shape. After that, the p-type Si layer in the vibrating part region of the vibrator shape is etched away.

[0010] Further, when the base substrate is a glass substrate, p
The feature of the present invention is that the mold Si layer and the glass substrate are bonded by anodic bonding.

In the present invention having the above structure, the n-type Si substrate is processed into a vibrator shape, and the p-type Si layer formed on one surface of the vibrating portion region of the vibrator shape is removed by etching. Is manufactured, the distance between the vibrating portion and the underlying substrate is substantially equal to the thickness of the p-type Si layer.
Since this p-type Si layer can be formed to have a desired thickness, increasing the thickness of the p-type Si layer increases the distance between the vibrator-shaped vibrating portion and the base substrate. Therefore, sticking between the vibrating portion and the underlying substrate is reduced, and the production yield of the Si vibrator is improved.

By using a glass substrate as the base substrate, unlike the case where both the vibrator and the base substrate are formed of a single crystal silicon substrate, the parasitic capacitance can be minimized. By bonding the Si layer and the glass substrate by anodic bonding, the adhesion between the p-type Si layer and the glass substrate is improved, whereby the adhesion between the vibrator and the base substrate is improved, and the above-mentioned problem is solved. You.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same reference numerals are given to the same parts as those in the conventional example, and the overlapping description will be omitted. FIG. 1 shows an embodiment of a method for manufacturing a Si vibrator according to the present invention. Hereinafter, a method for manufacturing a Si vibrator according to the present embodiment will be described with reference to FIG. First, as shown in FIG.
An n-type Si substrate 1 is prepared. This n-type Si substrate 1
In this embodiment, a phosphorus-doped n-type Si substrate is used, the resistivity is 1 to 10 Ωcm (ohm cm), and CM
The substrate is generally used for manufacturing an OS circuit.

Next, as shown in FIG.
On one surface of the i-substrate 1, a boron-doped p-type Si layer 2 is deposited and formed by an epitaxial growth method. Note that this p
The thickness of the mold Si layer 2 is formed to an appropriate thickness (thickness suitable for forming the bonding layer 4) between 1 and 10 μm. Next, as shown in FIG. 2C, a glass substrate 6 made of Pyrex glass (Pyrex is a trademark) serving as a base substrate 5 is bonded to the p-type Si layer 2 by an anodic bonding method (an n-type After the Si substrate 1 is heated to 300 to 500 ° C., a voltage of about +1000 V is applied and bonding is performed.

Next, as shown in FIG.
The i-substrate 1 is polished to the height of the vibrator 13, and then, as shown in FIG.
A pattern of the resist 7 is formed using a normal photolithography process. This pattern corresponds to the vibrator 13
Shape. Next, as shown in (f) of the figure, the n-type Si substrate 1 is processed into a vibrator shape by vertically processing the n-type Si substrate 1 by RIE using the resist 7 as a mask. 7 is removed.

Next, in this state, the Si vibrator forming member is put into an etching bath 14 using KOH as an etchant as shown in FIG. 3, and a positive potential is applied to the n-type Si substrate 1. In the figure, reference numeral 8 denotes a potentiostat as a power source, 9 denotes a reference electrode, and 10 denotes a counter electrode. By doing so, as shown in FIG. 1 (g), only the p-type Si layer 2 in the vibrator-shaped vibrating portion 11 region is removed by etching, and this member is etched when the etching is completed. The Si vibrator is completed by taking out from the layer 14, washing with pure water, and drying.

According to this embodiment, the bonding layer (sacrifice layer) 4 is formed of the p-type Si layer 2 as described above.
Since the p-type Si layer 2 can be formed to have a desired thickness, unlike the thermal oxide film used in the conventional Si resonator manufacturing method, the p-type Si layer 2 is formed between the resonator 13 and the underlying substrate 5. The intervals can be formed at appropriate intervals, whereby sticking between the oscillator 13 and the base substrate 5 can be reduced, and the yield of manufacturing Si oscillators can be improved.

According to the embodiment, the base substrate 5
Since the glass substrate 6 is used as the substrate, the substrate 3 on which the vibrator 13 is formed and the underlying substrate 5 are both S
Unlike a conventional Si resonator formed of an i-single-crystal substrate, the parasitic capacitance between the substrate 3 and the underlying substrate 5 can be minimized, and element characteristics can be improved.

Further, the glass substrate 6 and the p-type Si layer 2
Since the vibrator 13 and the base substrate 5 are bonded by anodic bonding, the adhesion between the vibrator 13 and the base substrate 5 can be improved. Peeling from the substrate 5 can be suppressed.

It should be noted that the present invention is not limited to the above-described embodiment, but can adopt various embodiments. For example,
In the above embodiment, the p-type Si layer 2 is deposited and formed by using the epitaxial growth method. However, the method of forming the p-type Si layer 2 is not particularly limited, and may be appropriately set. It can also be manufactured by ion implantation or deposition of boron-doped poly-Si by CVD (chemical vapor deposition).

In the above embodiment, when the n-type Si substrate 1 is processed into a vibrator shape, the n-type Si substrate 1 is processed by RIE using the photoresist 7 as an etching mask.
RIE processing can be performed using a metal mask or a thermal oxide film formed by a vacuum evaporation method or a sputtering method as a mask.

Further, in the above embodiment, the n-type Si substrate 1 is a phosphorus-doped n-type Si substrate, and the p-type Si layer 2 is a boron-doped p-type Si layer. Is not particularly limited, and is appropriately set.

Further, in the above embodiment, the base substrate 5
Is formed from Pyrex glass, but the glass substrate may be a substrate other than Pyrex glass. The base substrate 5 may be a substrate other than a glass substrate. When the base substrate 5 is formed of an insulating substrate such as the glass substrate 6, the parasitic capacitance with the vibrator 13 can be reduced. Therefore, the base substrate is formed of an insulator such as the glass substrate 6. desirable.

Further, in the above embodiment, the etching removal of the p-type Si layer 2 was performed using the apparatus shown in FIG. 3, but the apparatus used for etching removal was not necessarily the apparatus shown in FIG. However, the etching removal is performed by using an appropriate device.

Further, the shape of the vibrator of the Si vibrator manufactured by the method of manufacturing a Si vibrator of the present invention is not particularly limited, and may be a shape as shown in FIG.
Other shapes may be used.

[0026]

According to the present invention, a p-type Si layer is formed on one surface of an n-type Si substrate on which a Si vibrator is formed, and the p-type
The base substrate is bonded to the Si layer, and the p-type Si layer in the vibrator-shaped vibrating part region of the n-type Si substrate is removed by etching.
Since the vibrator is manufactured, the p-type Si layer is formed to a desired thickness, and the p-type Si layer in the vibrating portion region of the vibrator is removed by etching to make the distance between the vibrating portion and the base substrate a desired value. Can be intervals. Therefore, by setting the thickness of the p-type Si layer to an appropriate thickness, sticking between the vibrating portion of the vibrator and the base substrate can be suppressed, and the yield in manufacturing can be improved.

Further, when the base substrate is a glass substrate, p
According to the present invention in which the silicon substrate and the glass substrate are joined by anodic bonding, the parasitic capacitance between the vibrator of the n-type Si substrate and the substrate can be minimized by using the glass substrate as the insulating substrate. The element characteristics can be improved, and the adhesion between the vibrator and the underlying substrate can be improved by joining the p-type Si layer and the glass substrate by anodic bonding. Therefore, the exfoliation of the vibrator from the underlying substrate can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing one embodiment of a method for manufacturing a Si resonator according to the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a Si vibrator.

FIG. 3 is an explanatory view showing an example of an apparatus for etching and removing a p-type Si layer in the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 n-type Si substrate 2 p-type Si layer 3 substrate 4 bonding layer 5 base substrate 6 glass substrate 11 vibrating part 13 vibrator

Claims (2)

[Claims] 1. A p-type Si layer is formed on one surface of an n-type Si substrate, then a base substrate is joined to the p-type Si layer, and then the n-type Si substrate is processed into a vibrator shape. Thereafter, the p-type Si layer in the vibrating portion region of the vibrator shape is removed by etching. 2. The method according to claim 1, wherein the base substrate is a glass substrate, and the p-type Si layer and the glass substrate are joined by anodic bonding.