JPH10200128A - Manufacture of semiconductor sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To joint only a specified points surely without jointing a rocking part, in a manufacturing method for a semiconductor sensor which comprises a process where a semiconductor substrate having a rocking part is jointed to a glass substrate by anode jointing. SOLUTION: On a hot plate 18, a glass substrate 12 and a silicon substrate 13 are provided. A DC power source 19 is connected through a switch 23 which is opened/closed by a control circuit 22. Such pulse voltage as formed by switching is applied between both substrates 12 and 13. Here, each apply time period of pulse voltage is set to less than one fourth of resonance cycle of a weight part 15, while an application cycle of pulse voltage set to the resonance cycle of the weight part 15 or above.

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 semiconductor sensor including a step of joining a semiconductor substrate having a swinging portion to a glass substrate by anodic bonding.

[0002]

2. Description of the Related Art Conventionally, various semiconductor sensors have been proposed, and similarly, various methods for manufacturing semiconductor sensors have been proposed. Particularly, as a mechanical quantity sensor such as an acceleration sensor having a beam structure, a mechanical quantity sensor having a structure shown in FIG. 15 is generally known. FIG. 15 is a perspective view showing a structure of a general acceleration sensor, and FIG. 16 is a sectional view taken along line 16-16 of FIG.

[0003] As shown in FIG.
1 basically includes a glass substrate 12 and a silicon substrate 13. The silicon substrate 13 includes four beams 14 having a thin film shape and having flexibility, and a weight portion 15 supported by the beams 14.

[0004] Further, on the upper part of the glass substrate 12, FIG.
As shown in FIG. 1, a dug portion 16 is formed, and a predetermined clearance, for example, 4 to 8 μm is provided between the weight portion 15 of the silicon substrate 13 and the glass substrate 12. Through such a clearance, a predetermined capacitance is formed between the weight portion 15 and the glass substrate 12.

In the acceleration sensor 11 having such a structure, each beam 14 is bent by receiving acceleration in the vertical direction in the drawing, and the weight portion 15 swings up and down according to the magnitude of the acceleration. As a result, in the case of a capacitance type sensor, the distance between the weight portion 15 and the glass substrate 12 changes, and the capacitance between the weights 12 and 13 changes. The acceleration is detected based on the amount of change in the capacitance.

Generally, the swingable weight portion 15
Is formed as follows by anodic bonding. As shown in FIG.
In order to join the silicon substrate 13 only at the joint 17 by anodic bonding, the glass substrate 12 and the silicon substrate 13 are arranged on the hot plate 18 in order, and a DC power supply 19 is connected to the hot plate 18 and the silicon substrate 13. . The polarity of the connected power supply 19 is a negative electrode for the glass substrate 12 and a positive electrode for the silicon substrate 13.

As shown in FIG. 17, the voltage applied to both substrates 12 and 13 is 1000 V, and the voltage is applied for 30 minutes. Meanwhile, the glass substrate 12
And the silicon substrate 13 is about 4
It is kept heated to 50 ° C. The process of bonding the silicon substrate 13 and the glass substrate 12 in such a state is generally considered as follows.

The glass substrate 12 contains Na.sup. ⁺ Ions, and the Na.sup. ⁺ Ions move near the negative electrode, ie, move downward in the drawing. Joule heat is generated with the movement of the ions, and the temperature of the bonding surface of the glass substrate 12 rises to near the melting point.

Then, as shown in FIG. 18A, a space charge layer 20 is formed between the electrodes 12 and 13, and an electrostatic attraction is generated in the space charge layer 20. The glass substrate 12 and the silicon substrate 13 are attracted to each other by the electrostatic attraction, and the OH groups on the surfaces of both the substrates 12 and 13 are bonded. Subsequently, by removing H ₂ O between the two substrates 12 and 13, the two substrates 12 and 13 become covalently bonded between silicon and oxygen (Si—O) as shown in FIG.
Joined by.

[0010]

The silicon substrate 13 and the glass substrate 12 are bonded by anodic bonding as described above.
However, a relatively large attractive force is generated due to the high voltage applied at the time of the anodic bonding, and the swingable weight portion 15 is attracted toward the glass substrate 12 by the attractive force, and the weight portion 15 is attached to the glass substrate. 12 may be joined. In such a case, the weight portion 15 cannot swing and cannot function as the acceleration sensor 11.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a method of manufacturing a semiconductor sensor including a step of joining a semiconductor substrate having a swing portion to a glass substrate by anodic bonding. Without joining the parts
It is an object of the present invention to provide a method of manufacturing a semiconductor sensor that can accurately join only predetermined portions.

[0012]

According to a first aspect of the present invention, a semiconductor substrate having a swingable swing portion is bonded to a glass substrate by anodic bonding. A method for manufacturing a semiconductor sensor in which a predetermined clearance is formed between an oscillating portion and a glass substrate, wherein a voltage accompanied by a change in a voltage value is applied between both substrates so that oscillation of the oscillating portion is maintained. The purpose is to do.

According to the above configuration, although the value of the voltage applied between the semiconductor substrate and the glass substrate changes, the bonding proceeds on the bonding surface of the two substrates by applying a voltage equal to or higher than a predetermined value. I do. On the other hand, the oscillating portion receives an attractive force corresponding to the voltage value. That is, when the voltage value is large, the attractive force is large, and when the voltage value is zero, the attractive force is not generated. The swinging part receives such a force,
It swings in a direction approaching the glass substrate or in a direction away from the glass substrate. Therefore, the oscillating portion does not always receive the force toward the glass substrate, and the oscillating state is maintained. That is, the swinging part is not joined to the glass substrate.

[0014] The invention according to claim 2 is characterized in that the application time width of the anodic bonding voltage is set to less than a quarter of the resonance period of the oscillating portion. According to the above configuration, the swing unit swings toward the glass substrate or away from the glass substrate according to the time width during which the voltage is applied or the time width during which the voltage is not applied. Since the application time width is less than a quarter of the resonance period, the application of the voltage is stopped before the swinging portion reaches the position closest to the glass substrate from the initial position.

The invention described in claim 3 is characterized in that the application cycle of the anode junction voltage is set to be equal to or longer than the resonance cycle of the oscillating section. According to the above configuration, the oscillation of the oscillating portion does not resonate, and the increase in the displacement of the oscillating portion due to the applied voltage is suppressed to a small extent. In addition, if the application cycle is sufficiently long, the oscillating portion is reliably returned to the initial position during that period.

According to a fourth aspect of the present invention, a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding to form a predetermined clearance between the swing portion and the glass substrate. In a method for manufacturing a semiconductor sensor, a semiconductor substrate and a glass substrate are anodic-bonded in a state where the swinging portion is connected to a bonding portion of the semiconductor substrate via an insulating layer.

According to the above configuration, while a voltage is applied between the semiconductor substrate and the glass substrate, anodic bonding is performed at the bonding portion. (Voltage applying portion), the voltage applied between the oscillating portion and the glass substrate becomes extremely small. Therefore, the swing portion is prevented from being affected by the voltage applied between the semiconductor substrate and the glass substrate.

According to a fifth aspect of the present invention, a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A semiconductor sensor manufacturing method according to claim 1, wherein the semiconductor substrate and the glass substrate are anodically bonded after selectively reducing the Na ⁺ ion concentration in a portion corresponding to the oscillating portion of the glass substrate.

According to the above configuration, in the glass substrate, the concentration of Na ⁺ ions is set relatively low at the portion corresponding to the oscillating portion and set relatively high at the joint. Since the semiconductor substrate and the bonding of the glass substrate is carried out based on the movement of Na ⁺ ions, high joint concentration of Na ⁺ ions tends to be bonded to the semiconductor substrate. On the other hand, Na ⁺
A portion having a low ion concentration is hardly bonded to the semiconductor substrate.

According to a sixth aspect of the present invention, a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A method for manufacturing a semiconductor sensor, comprising: sequentially forming an insulator layer and a conductive glass layer on a bonding portion of the glass substrate with the semiconductor substrate; The purpose is to apply anodic bonding by applying a potential voltage.

According to the above configuration, since a potential difference is generated between the semiconductor substrate and the conductive glass layer, the two are joined by anodic bonding. However, the semiconductor substrate and the glass substrate have substantially the same potential, and the semiconductor substrate and the glass substrate have the same potential. The moving part also has the same potential as both substrates. Therefore, no electric action, for example, an attractive force is generated between the swinging portion and the glass substrate.

According to a seventh aspect of the present invention, a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. In the method of manufacturing a semiconductor sensor described above, it is intended that anodic bonding is performed after forming minute projections on at least one of the opposing surfaces of the oscillating portion and the glass substrate.

According to the above arrangement, a voltage is applied between the semiconductor substrate and the glass substrate, and an attractive force acts between the two substrates, whereby the rocking portion is pulled toward the glass substrate, and the rocking portion is made of glass. Approaching the substrate side. Here, when the displacement of the oscillating portion is large, the oscillating portion and the projection, or the projection and the glass substrate may be in contact with each other. At this time, even if the minute projections are joined, the contact area of the projections is small because the contact area of the projections is small. Therefore, by stopping the application of the voltage to the semiconductor substrate and the glass substrate, the bonding with the projection is released, and the swinging portion can return to the initial position.

According to an eighth aspect of the present invention, a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A method of manufacturing a semiconductor sensor, comprising: forming a soluble thin film on at least one of the opposing surfaces of the oscillating portion and the glass substrate; anodically bonding the semiconductor substrate and the glass substrate; and removing the thin film. And

According to the above configuration, when a voltage is applied between the semiconductor substrate and the glass substrate, an electric action, for example, an attractive force is generated between the swinging portion and the glass substrate. The oscillating portion is pulled toward the glass substrate and comes closer to the glass substrate. Here, even if the displacement of the oscillating portion is large, since the thin film is interposed between the oscillating portion and the glass substrate, they do not come into direct contact with each other. Even if the oscillating portion and the thin film or the thin film and the glass substrate are bonded to each other, the oscillating portion and the glass substrate can be separated from each other by melting the thin film, and the oscillating portion can return to the initial position. It becomes possible.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a method for manufacturing a semiconductor sensor according to the present invention will be described below with reference to the drawings.

(First Embodiment) An acceleration sensor manufactured according to this embodiment is of a capacitance type, and has the same shape as the conventional acceleration sensor 11 shown in FIG. The operation and the like are the same as those of the conventional acceleration sensor 11. Therefore, the conventional acceleration sensor 11
The same members as those described above are denoted by the same reference numerals, description thereof will be omitted, and only a method of manufacturing the same sensor will be described.

FIG. 1 shows an outline of an apparatus configuration for anodic bonding between a silicon substrate 13 and a glass substrate 12 by the manufacturing method of the present embodiment. At the time of anodic bonding, the glass substrate 12 is placed on a hot plate 18 as shown in FIG.
And a silicon substrate 13 are provided. Here, the weight 15
A predetermined clearance, for example, 4 to 8 μm, is provided between the substrate and the glass substrate 12. The weight 15 can swing up and down in the drawing by the clearance. Further, a DC power supply 19 is connected to the silicon substrate 13 and the hot plate 18. The polarity of the power supply 19 is a negative electrode with respect to the glass substrate 12 and a positive electrode with respect to the silicon substrate 13. Power supply 19 and silicon substrate 1
A switch 23 controlled to be opened and closed by the control circuit 22 is interposed between the control circuit 22 and the control circuit 3.

When the control circuit 22 controls the opening and closing of the switches, a voltage is intermittently applied to the silicon substrate 13 and the glass substrate 12. Normally, as described above, the bonding portion 1 between the silicon substrate 13 and the glass substrate 12 is used.
By applying a voltage to the substrate 7 continuously for a predetermined period, for example, 30 minutes, the two substrates 12 and 13 are anodically bonded to each other.

FIG. 2 shows both substrates 12 and 12 in this embodiment.
13 shows a waveform of a voltage applied to the sample No. 13. As shown in FIG. 2, the voltage waveform has a rectangular pulse shape, and its amplitude is 1
000 V, the pulse width (application time width) is t1, and the cycle time is t2. Here, weight part 15 for reference
The waveform having the resonance frequency is indicated by a two-dot chain line. Weight part 1
Assuming that the resonance frequency of No. 5 is f1, the application time width t1 of the voltage is set to be less than one quarter of the resonance period T1 with respect to the resonance period T1 (= 1 / f1) which is the reciprocal thereof. The period t2 of the same voltage corresponds to the weight 1
5 is set to be equal to or longer than the resonance period T1.

An anodic bonding voltage is intermittently applied between the silicon substrate 13 and the glass substrate 12 in this manner. The anodic bonding is an irreversible bonding, and even if the anodic bonding voltage is not continuous but thus intermittently applied,
The anodic bonding proceeds at the bonding portion 17 between the two substrates 12 and 13. At this time, the anodic bonding is completed when the cumulative time of the application time t1 of the voltage applied between the substrates 12 and 13 reaches the above-mentioned predetermined period (for example, 30 minutes).

Incidentally, the anodic bonding applied voltage is 1000 V
And a high voltage, even if a clearance is provided between the glass substrate 12 and the weight portion 15,
A large electrostatic attraction occurs between them. However, in the present embodiment, although the weight portion 15 receives the attraction toward the glass substrate 12 during the same voltage application time width t1, the attraction is also released during the subsequent voltage release period t3, and the dashed line in FIG. In the mode indicated by the arrow F, the original clearance returns to the position where the predetermined clearance is held. Moreover, in the present embodiment, since the application period t2 of the same voltage is equal to or longer than the resonance period T1 of the weight portion 15, the weight portion 15 reliably returns to the original position after the attraction is released. Will be done.

Therefore, a voltage as shown in FIG.
The weight portion 15 vibrates in a direction approaching the glass substrate 12 or in a direction away from the glass substrate 12 according to the voltage application time width t1 and the open period t3 by being applied to the glass substrates 12 and 13.

The weight portion 15 continually vibrates, but the cycle time t2 of the applied voltage is longer than the resonance cycle time T1 of the weight portion 15.
, The weight portion 15 does not resonate due to the applied voltage, and an increase in the displacement of the weight portion 15 is suppressed to be smaller than the resonance state. As a result, contact of the weight portion 15 with the glass substrate 12 is suppressed as much as possible.

As described above, according to the present embodiment, by applying the anodic bonding voltage in the above-described manner, it is possible to suitably prevent the weight portion 15 from being bonded to the glass substrate, Only the 13 joints 17 can be joined accurately.

In the present embodiment, the waveform of the anode junction voltage is not limited to the above-mentioned rectangular wave, but may be a triangular wave as shown in FIG. 3 or another waveform. Even with such a waveform, it is possible to join only the joint 17 while preventing the weight 15 from being joined to the glass substrate 12.

In this embodiment, the cycle time t 2 (t 2 ′) of the anode junction voltage is set to the resonance cycle T 1 of the weight 15.
Although it is ensured that the joining of the weight portions 15 is prevented by the above setting, the displacement amount of the weight portions 15 can be further suppressed by sufficiently shortening the application time width t1 (t1 '). Can be. Further, by making the voltage release time t3 (t3 ′) sufficiently long, the displacement amount of the weight portion 15 can converge to almost zero during that period. However, the amount of displacement of the weight portion 15 depends on the magnitude of the clearance, the rigidity of the beam 14, and the like in addition to the applied voltage. Therefore, when the clearance is large, and when the rigidity of the beam 14 is relatively high, even if the voltage application time width t1 (t1 ′) is set to half or more of the resonance cycle in practice, the cycle time t2 May be set to be less than the resonance period T1.

In addition to the above intermittent waveform, a voltage (a voltage other than DC) at which the voltage value changes in order to suppress the joining between the weight portion 15 and the glass substrate 12 in a manner similar to the above.
May be applied as the anodic bonding voltage.

(Second Embodiment) The acceleration sensor manufactured by the manufacturing method of this embodiment is a strain gauge type. However, the same members as those of the acceleration sensor 11 manufactured according to the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 4 shows the structure of the strain gauge type acceleration sensor 24, and FIG. 5 shows a cross section taken along line 5-5 of FIG. As shown in FIG. 4, in the acceleration sensor 24, the silicon substrate 13 including the weight 15 and the glass substrate 12 are joined to each other. Each beam 14 is provided with a strain gauge 25 having a predetermined resistance value on its upper surface. Further, in the present embodiment, an insulating layer 26 made of silicon oxide (SiO ₂ ) is interposed between the weight portion 15 and each of the beams 14, and the weight portion 15 and the silicon substrate 13 are particularly provided.
Is electrically insulated from the bonding portion 17.

Incidentally, in the case of the strain gauge type acceleration sensor, the beam 1
The acceleration is detected based on the amount of change in the resistance value of the strain gauge 25 provided on each beam 14 when the weight 4 is bent and the weight 15 swings.

Next, the anodic bonding of the silicon substrate 13 and the glass substrate 12 will be described with reference to FIG. As shown in FIG. 5, a glass substrate 12 is placed on a hot plate 18, and a silicon substrate 13 on which a strain gauge 25 and an insulating layer 26 are formed in advance is placed on the glass substrate 12 as shown. Then, in this state, the DC power supply 19 is connected to the silicon substrate 13 and the hot plate 18.

In this state, the anodic bonding voltage is applied to the silicon substrate 13 and the glass substrate 12 in the manner shown in FIG.
By applying the voltage between them, the two substrates 12 and 13 are connected to the joint 1.
At 7 anodically bonded.

At this time, a capacitor C1 is formed between the beam 14 and the weight portion 15 via the insulating layer 26, and a capacitor C2 is formed in a gap between the weight portion 15 and the glass substrate 12. Is done. As a result, the positive electrode of the DC power supply 19, the beam 19, the capacitor C1, the weight 1
5, an electric circuit is formed in the order of the capacitor C2, the glass substrate 12, and the negative electrode of the power supply 19. The voltage applied to the circuit comprises two capacitors C1, C2
Is divided by Here, the area of the capacitor C2 is much larger than the area of the capacitor C1 (the area of C1≪C
2), the capacity of the capacitor C2 is
1 capacity. Therefore, based on this capacitance ratio, the voltage divided into the capacitor C2, that is, the voltage applied between the weight portion 15 and the glass substrate 12 becomes extremely small. As a result, the weight 15 does not come into contact with the glass substrate 12 during the anodic bonding, so that the inconvenience of the weight 15 being bonded to the glass substrate 12 can be prevented, and the bonding between the silicon substrate 13 and the glass substrate 12 can be prevented. Only the portion 17 can be accurately joined.

In the present embodiment, if the weight 15 is electrically insulated from the joint 17, the insulating layer 26 may be formed at a position different from the above position. For example, as shown in FIG. 6, the insulating layer 27 may be formed over the entire surface of the silicon substrate 13. Even in such a configuration, the weight 15 is not affected by the voltage applied to the substrates 12 and 13, so that the weight 15 can be prevented from being bonded to the glass substrate 12.

(Third Embodiment) The acceleration sensor manufactured by the manufacturing method of this embodiment is a capacitance type like the acceleration sensor 11 of the first embodiment and has the same shape. Only the manufacturing method will be described.

FIG. 7 is a sectional view showing a manufacturing process of the acceleration sensor according to this embodiment. As shown in FIG.
Glass substrate 12 and the number of Na ⁺ ions (represented in the figure "+"), the Na ⁺ ions as many O ₂ ^- ion - includes (in the figure "" represented by), Na ⁺ ions and O ₂ ^- The ions are uniformly distributed in the glass substrate 12.

As shown in FIG. 7B, the glass substrate 12
Electrode 2 made of, for example, chromium (Cr)
9 is formed. The electrode 29 is located at a position corresponding to the weight 15, and the area of the electrode 29 is larger than the area of the lower surface of the weight 15. Then, the DC power supply 19 is connected to the upper surface of the glass substrate 12 and the electrode 29. The polarity of the connected power supply 19 is a negative electrode with respect to the upper surface of the glass substrate 12 and a positive electrode with respect to the lower surface.

Then, 1000 to the glass substrate 12
A voltage of ２０００2000 V is applied for a predetermined period, for example, 30 minutes. This voltage is applied when the glass substrate 12 is moved from normal temperature to 45 degrees.
This is performed while maintaining the temperature at 0 ° C. The above voltage application causes the electrode 29
A strong electric field is generated in the vicinity, and the Na ⁺ ions in the glass substrate 12 move to the same electrode 29 side by the electric field. Therefore, compared to the joint 17 of the glass substrate 12, the electrode 2
At the dug portion 16 corresponding to 9, Na ⁺ ions are significantly reduced.

Next, in order to remove the electrode 29 and perform anodic bonding, as shown in FIG. 7C, a hot plate 18, a glass substrate 12, and a silicon substrate 13 are sequentially arranged, and a DC power supply 19 is provided. Is connected to the silicon substrate 13 and the hot plate 18.

While the glass substrate 12 is heated to about 450 ° C., the distance between the silicon substrate 13 and the glass substrate 12 is
When a voltage of about 00 V is applied, both substrates 1
The anodic bonding is performed at the bonding portions 17 of the 2 and 13. Here, the bonding portion 17 of the glass substrate 12 has a sufficient number of Na
Due to the presence of ⁺ ions, heat is generated by the movement of Na ⁺ ions in the same portion, and anodic bonding proceeds.

On the other hand, despite the voltage being applied to both substrates 12 and 13, N
Since there is almost no a ⁺ ion,
In No. 6, Na ⁺ ions do not move and do not generate heat.
Therefore, since anodic bonding cannot occur in the dug portion 16, even when the weight portion 15 is in contact with the glass substrate 12, it is possible to prevent the weight portion 15 from being bonded to the glass substrate 12. it can.

In this embodiment, the glass substrate 12
Even if the electrode 29 formed on the lower surface is formed at a position other than the position shown in FIG. 7B, it is possible to move Na ⁺ ions in advance. For example, as shown in FIG. 8A, the electrode 30 may be formed only in the dug portion 16 of the glass substrate 12. Further, as shown in FIG.
The electrodes 29 and 30 may be formed on both surfaces of the dug portion 16 and the lower surface of the glass substrate 12.

(Fourth Embodiment) The acceleration sensor manufactured by the manufacturing method of this embodiment is of the capacitance type and has the same shape as the acceleration sensor 11 of the first embodiment. The structure near the part is different from that of the acceleration sensor 11 of the first embodiment.

In the present embodiment, as shown in FIG. 9, a first glass film 32 made of a high melting point glass (for example, quartz glass) is formed on a glass substrate 12 made of a low melting point glass (for example, PYREX # 7740). And a second glass film 33 made of a low-melting glass (for example, PYREX # 7740). The bonding between the glass substrate 12 and the first glass film 32 and the bonding between the first glass film 32 and the second glass film 33 are performed by a high pressure welding method or by sputtering high melting point glass onto the glass substrate 12. It is done by doing. A glass substrate 12 and both glass films 32,
The patterning 3 is performed by etching with a hydrofluoric acid solution or an ammonium fluoride solution, or by sandblasting.

The glass substrate 12 and the two glass films 32 and 3 contain Na ⁺ ions, but have different characteristics due to a difference in melting point. That is, the temperature at which anodic bonding is performed (about 450
(° C.), Na ⁺ ions can move in the low-melting glass, so that the low-melting glass has good conductivity and is a material suitable for anodic bonding. On the other hand, at the temperature at which anodic bonding is performed (about 450 ° C.), Na ⁺
Since ions are hard to move, high melting point glass is a material having high insulating properties and being hard to be anodically bonded.

When anodic bonding the glass substrate 12 and the silicon substrate 13, as shown in FIG. 10, the glass substrate 12 and the silicon substrate 13 are provided on a hot plate 18 and a DC power supply 19 is connected. The polarity of the connected voltage is a positive electrode with respect to the silicon substrate 13 and the glass substrate 12, and a negative electrode with respect to the second glass film 33. With the above connection, the glass substrate 12 and the silicon substrate 13 have the same potential, and a potential difference occurs between the silicon substrate 13 and the second glass film 33.

By applying the anodic bonding voltage shown in FIG. 17 by such a voltage applying structure, anodic bonding is performed between the silicon substrate 13 and the second glass substrate 12 having a potential difference. At this time, a high voltage is applied to each of the substrates 12 and 13, but the weight 15 is also applied to the glass substrate 1.
2, the weight 15 and the glass substrate 12
No electrical force acts between them.

Accordingly, it is possible to prevent the weight portion 15 from being bonded to the glass substrate 12, and
The silicon substrate 13 and the second glass film 33 can be securely anodically bonded.

In the present embodiment, the first glass film 32 is formed only on both ends of the glass substrate 12, but in the embodiment shown in FIGS. 11 (a), (b) and (c),
The first glass film 32 may be formed.

In particular, as shown in FIG. 11A, after a first glass film 32 having a uniform thickness is formed on the glass substrate 12, the glass film 32 is cut.
The thickness of the glass film 32 at a position facing the weight portion 15 can be easily changed. By such a change, the size of the clearance formed between the weight portion 15 and the weight portion 15 can be adjusted.

As shown in FIGS. 11 (a) and 11 (b), when the first glass film 32 is formed at a position facing the weight portion 15, the weight portion 15 becomes the first glass film at the time of anodic bonding. Even if the first glass film 32 is kept in contact with the film 32, the first glass film 32 has a high insulating property, so that the first glass film 32 and the first glass film 32 are not joined.

Further, instead of the first glass film 32, an insulating film made of another material which maintains the insulating property even at the temperature at which the anodic bonding is performed may be formed. For example, alumina (Al ₂ O ₃ ), silicon nitride (S
Ceramics such as i ₃ N ₄ ) are also applicable. In this case as well, by connecting the power supply 19 as shown in FIG. 10 and setting the weight 15 and the glass substrate 12 to the same potential,
The weight portion 15 can be prevented from being bonded to the glass substrate 12.

(Fifth Embodiment) The acceleration sensor manufactured by the manufacturing method of this embodiment is of the capacitance type and has almost the same shape as the acceleration sensor 11 of the first embodiment.

As shown in FIG. 12, the acceleration sensor 3
In No. 4, a projection 35 having a sharp tip is formed on the lower surface of the weight portion 15. The pyramid-shaped projections 35 are formed one at each of the four corners of the weight 15. FIG. 13 shows the projection 35 in an enlarged manner.

The method of forming the projections 35 is such that after applying a minute mask to a predetermined position on the silicon substrate 13, the silicon substrate 13 is alkali-etched to form the projections 35 at the masked position. As a method of forming the protrusion 35 at an arbitrary position, the protrusion 35 can also be formed by etching the silicon substrate 13 with a low-concentration alkaline etching solution without using a mask.

When the silicon substrate 13 and the glass substrate 12 are bonded by anodic bonding, the glass substrate 12 and the silicon substrate 13 are provided on the hot plate 18 and a DC power supply 19 is connected. Then, the glass substrate 12 is heated at 450 ° C.
By applying the voltage shown in FIG. 17 to the glass substrate 12 and the silicon substrate 13 in a state where the substrates 12 and 13 are heated to a certain degree, the anodic bonding is performed at the bonding portion 17 between the substrates 12 and 13.

At this time, the weight portion 15 receives an attractive force by the voltage applied to both substrates 12 and 13,
Pulled to the side. When the displacement of the weight portion 15 is large, the projection 35 may come into contact with the glass substrate 12. When this contact state continues for a predetermined period, the projection 35 is anodically bonded to the glass substrate 12. However, since the tip of the projection 35 is sharp, the bonding area between the projection 35 and the glass substrate 12 is very small.
The bonding strength of 5, 12 is also small.

That is, after the substrates 12 and 13 are securely anodically bonded, the application of the voltage is stopped, so that the rigidity (spring constant) of the beam 14 causes the weight portion 15 to have a restoring force in the direction of returning to the initial position. Works. Projection 35 and glass substrate 1
Since the bonding force between the two is very small, the lower surface of the projection 35 is separated from the glass substrate 12 by this restoring force, and the weight 1
5 can return to the initial position. Accordingly, the formation of the protrusion 35 on the weight portion 15 can also prevent the weight portion 15 from being joined.

At this time, the following equation (1) must be satisfied in order for the four projections 35 to peel off. Equation (1) indicates that the joining force of the four protrusions 35 is smaller than the restoring force of the weight.

4σs <kd (1) Here, in the equation (1), σ is the bonding strength (bonding force per unit area) of the projection 35, s is the area of the tip end surface of the projection 35, and k is the beam 14 Represents the distance between the lower surface of the weight portion 15 and the upper surface of the glass substrate 12. As shown in FIG. 13, when the tip surface of the protrusion 35 is a square with one side a, the side a is expressed by the following equation (2) based on the above equation (1).

A <(kd / 4σ) ^1/2 (2) A normal acceleration sensor has a spring constant and a distance of k, respectively.
= 200 (N / m) and the distance d = 5 (μm). At this time, the joining strength is set to σ = 1000 (kgf / c
Assuming that m ² ) = 100 (MPa), it suffices that one side a of the front end surface be 1 (μm) or less. The protrusion 35 having the tip surface having such a size can be easily formed by the above-described alkali etching technique.

In the present embodiment, the projection 35 may be formed on the glass substrate 12 side. (Sixth Embodiment) The acceleration sensor manufactured by the manufacturing method of this embodiment is the acceleration sensor 1 of the first embodiment.
Since it is of the capacitance type and has basically the same shape as in the case of No. 1, only the manufacturing method thereof will be described.

FIG. 14 shows an acceleration sensor 3 according to this embodiment.
It is sectional drawing which shows the manufacturing process of No. 6. As shown in FIG. 14A, a sacrificial layer 37 that can be removed by etching is formed in the dug portion 16 of the glass substrate 12. This sacrificial layer 3
7, titanium (Ti), aluminum (Al),
Chrome (Cr) or the like can be used.

Next, as shown in FIG. 14B, a glass substrate 12 and a silicon substrate 13 are placed on a hot plate 18.
And a DC power supply 19 is connected. And
The anodic bonding voltage shown in FIG. 17 is applied to the glass substrate 12 and the silicon substrate 13 in a state where the glass substrate 12 is heated to about 450 ° C.
The anodic bonding is performed at the bonding portions 17 of the 2 and 13. At this time, the weight 15 is pulled toward the glass substrate 12 by the attraction caused by the voltage.

As shown in FIG. 14C, when the displacement of the weight 15 is large, the weight 15 may come into contact with the sacrifice layer 37 and be joined to the sacrifice layer 37. In this state, only the sacrificial layer 37 is selectively removed by etching with an etching solution. At this time, when the sacrifice layer 37 is made of titanium, hydrogen chloride (HCl) is used as an etching solution. When the sacrifice layer 37 is made of aluminum or chromium, concentrated sulfuric acid (H ₂ SO ₄ ) is used as an etching solution.
Alternatively, concentrated nitric acid (HNO ₃ ) is used.

As described above, by removing the sacrificial layer 37 by etching, as shown in FIG.
5 returns to the initial position by the restoring force of the beam 14, and a predetermined clearance is secured between the weight portion 15 and the glass substrate 12.

Therefore, by forming the sacrificial layer 37 and performing anodic bonding as described above and removing the sacrificial layer 37, the weight 15 can be prevented from being bonded.

In this embodiment, the sacrificial layer 37
Are not limited to those described above, and may be any combination that allows only the sacrificial layer 37 to be removed without etching the silicon substrate 13 and the glass substrate 12.

The sacrifice layer 37 may be formed on the weight portion 15 side, or may be formed on both the glass substrate 12 and the weight portion 15. As mentioned above, although six embodiments were illustrated, it is not limited to them and may be changed as follows. In the following another embodiment, the same operation and effect as the above embodiment can be obtained.

(1) The capacitance type acceleration sensor may be provided with a strain gauge to be changed to a strain gauge type acceleration sensor. Alternatively, the strain gauge type acceleration sensor may be replaced with a capacitance type acceleration sensor by omitting the strain gauge.

(2) In each of the above embodiments, the glass substrate 12 and the silicon substrate 13 are disposed on the hot plate 18 in order, and the anodic bonding of the substrates 12 and 13 is performed. On the other hand, the anodic bonding may be performed by changing the arrangement of the substrates 12 and 13. That is, the silicon substrate 13 and the glass substrate 12 are sequentially arranged on the hot plate 18. Both substrates 1
By arranging the components 2 and 13 in this manner, the weight 15
In the direction away from the glass substrate 12, ie, the glass substrate 1
Gravity acts in a direction that hinders contact with 2.
Therefore, joining of the weight portions 15 can be more easily prevented.

(3) In the second to sixth embodiments, FIG.
Is applied, the magnitude of the voltage and the application period may be arbitrarily changed within a range in which the anodic bonding is performed. It should be noted that the technical ideas that are not described in the claims and can be grasped from the above embodiment are described below together with their effects.

The method of manufacturing a semiconductor sensor according to claim 1, wherein the application time width of the anodic bonding voltage is less than half the resonance period of the oscillating portion. .

Also in the above manufacturing method, it is possible to prevent bonding between the swinging part and the glass substrate.

[0086]

According to the first aspect of the present invention, anodic bonding proceeds on the bonding surface of the substrate. On the other hand, the swing unit swings in a direction approaching the glass substrate or in a direction away from the glass substrate based on an attractive force corresponding to the voltage value. Therefore, the oscillating portion does not always receive the force toward the glass substrate, and the oscillating state is maintained. As a result,
The swinging portion can be prevented from being bonded to the glass substrate.

According to the second aspect of the present invention, the swing portion swings in a direction approaching the glass substrate or in a direction away from the glass substrate according to a time width during which a voltage is applied or a time width during which no voltage is applied. The application time width is one quarter of the resonance period
Therefore, the application of the voltage is stopped before the swing portion reaches the position closest to the glass substrate from the initial position. Therefore, contact between the swinging part and the glass substrate can be suppressed.

According to the third aspect of the invention, the vibration of the swinging portion does not resonate, and the increase in the displacement of the swinging portion due to the applied voltage is suppressed to a small extent. In addition, if the application cycle is sufficiently long, the oscillating portion is reliably returned to the initial position during that period.
Therefore, it is possible to further prevent bonding between the swinging portion and the glass substrate.

According to the fourth aspect of the present invention, while a voltage is applied between the semiconductor substrate and the glass substrate, anodic bonding is performed at the bonding portion, whereas the oscillating portion is bonded via the insulating layer. Since it is connected to the portion (voltage applying portion), the voltage applied between the swinging portion and the glass substrate becomes extremely small. Therefore, the swing portion can be joined only at a predetermined position without being affected by the voltage applied between the semiconductor substrate and the glass substrate. According to the fifth aspect of the invention, in the glass substrate, the portion corresponding to the swinging portion is set in a state where it is difficult to perform anodic bonding, so that the joining between the swinging portion and the glass substrate can be reliably prevented.

According to the sixth aspect of the present invention, since the oscillating portion and the glass substrate have the same potential, there is no electric action, for example, no attractive force between them. Therefore, it is possible to prevent the swinging portion from contacting the glass substrate.

According to the seventh aspect of the present invention, even when the minute projection is bonded to the semiconductor substrate or the glass substrate, the contact area of the projection is small, so that the bonding force acting on the contact surface is small. Therefore, by stopping the application of the voltage to the semiconductor substrate and the glass substrate, the bonding with the projection is released, and the swinging portion can return to the initial position.

According to the eighth aspect of the present invention, even if the oscillating portion and the thin film or the thin film and the glass substrate are bonded to each other,
By melting the thin film, the oscillating portion and the glass substrate can be separated from each other, and the oscillating portion can return to the initial position.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing method according to a first embodiment.

FIG. 2 is a time chart showing a waveform of an applied voltage.

FIG. 3 is a time chart showing another waveform of an applied voltage.

FIG. 4 is a perspective view showing an acceleration sensor based on a manufacturing method according to a second embodiment.

FIG. 5 is a sectional view showing the manufacturing method according to the second embodiment;

FIG. 6 is a sectional view showing another manufacturing method of the second embodiment.

FIG. 7 is a sectional view showing the manufacturing method according to the third embodiment;

FIG. 8 is a sectional view showing another example of the arrangement of electrodes.

FIG. 9 is a sectional view showing a glass substrate according to a manufacturing method of a fourth embodiment.

FIG. 10 is a sectional view showing the manufacturing method according to the fourth embodiment;

FIG. 11 is a cross-sectional view illustrating another example of the structure of the glass substrate.

FIG. 12 is a sectional view showing the manufacturing method according to the fifth embodiment;

FIG. 13 is an enlarged perspective view showing the shape of a projection.

FIG. 14 is a sectional view showing the manufacturing method according to the sixth embodiment;

FIG. 15 is a perspective view showing a configuration of a general acceleration sensor.

FIG. 16 is a sectional view showing the method of manufacturing the acceleration sensor.

FIG. 17 is a time chart showing a waveform of an applied voltage during anodic bonding.

FIG. 18 is a schematic view showing a bonding principle of anodic bonding.

[Explanation of symbols]

11, 24, 31, 34: acceleration sensor, 12: glass substrate, 13: silicon substrate, 18: hot plate, 1
9 power supply, 22 control circuit, 23 switch, 32 first glass film, 33 second glass film, 35 protrusion, 3
7 ... Sacrificial layer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hideki Sasaki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Masato Hashimoto 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (8)

[Claims] 1. A method of manufacturing a semiconductor sensor, comprising: bonding a semiconductor substrate having a swingable swing portion to a glass substrate by anodic bonding to form a predetermined clearance between the swing portion and the glass substrate. A method of manufacturing a semiconductor sensor, comprising applying a voltage with a change in a voltage value between the two substrates so as to maintain the oscillation of the oscillating portion. 2. The method of manufacturing a semiconductor sensor according to claim 1, wherein an application time width of the anodic bonding voltage is set to be less than a quarter of a resonance period of the oscillating portion. Production method. 3. The method of manufacturing a semiconductor sensor according to claim 2, wherein an application cycle of the anode junction voltage is equal to or longer than a resonance cycle of the oscillating portion. 4. Production of a semiconductor sensor in which a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A method of manufacturing a semiconductor sensor, comprising: anodically bonding the semiconductor substrate and the glass substrate in a state where the oscillating portion is connected to a bonding portion of the semiconductor substrate via an insulating layer. . 5. A method of manufacturing a semiconductor sensor in which a semiconductor substrate having a swingable swinging part is joined to a glass substrate by anodic bonding to form a predetermined clearance between the swinging part and the glass substrate. A semiconductor sensor, comprising: after selectively reducing the Na ⁺ ion concentration in a portion of the glass substrate corresponding to the oscillating portion, anodically bonding the semiconductor substrate and the glass substrate. Manufacturing method. 6. Manufacturing of a semiconductor sensor in which a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A method, wherein an insulating layer and a conductive glass layer are sequentially formed at a joint portion of the glass substrate with the semiconductor substrate, and the semiconductor substrate and the glass substrate are substantially the same with respect to the conductive glass layer. A method for manufacturing a semiconductor sensor, comprising applying anodic bonding by applying a potential voltage. 7. Production of a semiconductor sensor in which a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding to form a predetermined clearance between the swing portion and the glass substrate. A method of manufacturing a semiconductor sensor, comprising: forming fine projections on at least one of the opposing surfaces of the oscillating portion and the glass substrate, and then performing anodic bonding. 8. Manufacturing of a semiconductor sensor in which a semiconductor substrate having a swingable swing portion is joined to a glass substrate by anodic bonding, and a predetermined clearance is formed between the swing portion and the glass substrate. A method, comprising: forming a soluble thin film on at least one of the opposing surfaces of the oscillating portion and the glass substrate; removing the thin film after anodically bonding the semiconductor substrate and the glass substrate. Manufacturing method of a semiconductor sensor.