JP2926940B2 - Manufacturing method of micromechanical structure - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing a micromechanical structure formed on a semiconductor substrate and including a fixed part and a movable part.

B. Conventional technology FIG. 14 shows, for example, IEICE Transactions C, Vol.
FIG. 1C is a plan view of a micro check valve as an example of a conventional micromechanical structure known in, for example, No. 12, p. 1705-1711 (December 1988).

In the figure, 1 is a silicon substrate, 2 is a silicon substrate 1
A through-hole 3 is formed in an inverted V-shaped cross-section, and a valve 3 is formed above one opening of the through-hole 2. Reference numeral 4 denotes a fixing ring formed on the surface of the silicon substrate 1, 5 denotes four supporting arms provided in a form extending inward from the fixing ring 4, and the valve 3 denotes these four supporting arms. It is fixed to the fixing ring 4 in a state of being floated by a predetermined distance from one opening of the through-hole 2 via 5. The valve 3, the fixing ring 4, and the support arm 5 are each made of polysilicon (poly-Si).
It is integrally molded.

Such a check valve is used as a micro check valve constituting a diaphragm type micro pump (micro pump) used for integrating an analytical chemical system such as a liquid chromatograph.

Next, a method for manufacturing a micro check valve having the above structure will be described.
This will be described with reference to FIG.

First, as shown in FIG. 15 (a), the silicon substrate 1 is thermally oxidized in a high-temperature oxidizing gas to form an oxide film (SiO ₂ ) 6 on the front surface and the back surface thereof. The portion of the oxide film 6 corresponding to the portion to be formed is removed by etching.

Next, as shown in FIG. 15 (b), the surface of the silicon substrate 1 and the oxide film 6 are formed on the surface of the oxide film 6 by CVD (chemical vapor deposition).
After the SG film 7 is deposited, the portion of the PSG film 7 corresponding to the portion where the fixing ring 4 is to be formed is removed by photopatterning and etching (photoetching).

Next, as shown in FIG. 15 (c), after forming a polysilicon film 8 by LPCVD (low pressure chemical vapor deposition) on the surface of the substrate 1 and the oxide film 6, a valve 3 and a fixed ring 4 are formed. The polysilicon film 8 other than the portion corresponding to the portion to be removed is removed by photopatterning and dry etching.

Further, as shown in FIG. 15 (d), after forming the polysilicon film 9 again by LPCVD, the polysilicon film 9 other than the portion corresponding to the portion where the valve 3, the support arm 5 and the fixing ring 4 are formed is removed. It is removed by dry etching.

Further, as shown in FIG. 15 (e), after an oxide film and a CVD nitride film 10 are formed on both surfaces of the substrate 1, the oxide film and the nitride film 10 are photo-etched to form a through hole on the back surface of the substrate 1. Patterning of the portion corresponding to 2 is performed. Then, 35
An inverted V-shaped through hole 2 is formed on the back surface of the silicon substrate 1 by anisotropic etching using a wt% KOH solution. Finally, the PSG film 7 is etched with hot phosphoric acid or hydrofluoric acid based etchant.
By removing the oxide film and the nitride film 10, the micro check valve shown in FIG. 15 (f) can be obtained.

In addition to the micro check valve having the above structure, a micro gear, a micro turbine, a micro scissors, and the like having a fixed shaft fixed on a silicon substrate and a movable portion rotatable around the fixed shaft. Micromechanical structures are conventionally known (for example, IEEE Transaction on Electron
Devices, Vol. 35, No. 6, June (1988), p. (719-723).

In addition, micromechanical structures for semiconductor sensors have also been manufactured. For example, cantilever and doubly-supported beam structures used for vibration sensors and the like (for example, J. Electrochem.
Soc., Vol. 130, No. 6, p. 1420-1423, June, 1983) and a diaphragm structure used for a pressure sensor (for example, Proc.o
f the 6th Sensor Symposium, p.23-28 (1986)).

As an example of the micro-mechanical structure for a semiconductor sensor as described above, a method of manufacturing a diaphragm structure for a pressure sensor will be described with reference to FIG.

First, as shown in FIG. 16A, an intermediate layer 12 and a silicon nitride film 13 are deposited on a (100) plane of a silicon substrate 11, and then the intermediate layer 12 and the silicon nitride
Etching 13 is performed to form an etching hole 14 on the silicon substrate 11.

Next, as shown in FIG. 16 (b), the silicon substrate 11 is etched together with the intermediate layer 12 with an alkaline aqueous solution to form a cavity region 15 on the surface of the silicon substrate 1. Then, by etching until the cavity region 15 has a desired size, as shown in FIG. 16 (c),
A diaphragm section 16 made of the silicon nitride film 13 is formed.
Finally, if necessary, add a polysilicon film to the diaphragm
A diaphragm is formed by depositing on the top 16 and closing the etching hole 14.

C. Problems to be Solved by the Invention However, in the conventional micromechanical structure as described above, since the fixed part and the movable part are formed of a polycrystalline film, the existence of grain boundaries between crystals is inevitable. However, since these grain boundaries are aggregates of defects and are structurally weak, there has been a problem that the strength of the micromechanical structure cannot be sufficiently secured and reliability is poor. In addition, each fixing portion composed of a polycrystalline film,
The movable part has poor surface flatness. For example, a polysilicon film obtained by reacting under standard conditions (using monosilane as a raw material at around 0.8 Torr and around 600 ° C.) by LPCVD, which is most often used for mass production, has a thickness of several hundreds of thousands due to the presence of many grain boundaries. Thousands of irregularities are present on the surface. Therefore, there is also a problem that abrasion in the contact portion progresses quickly. Furthermore, it is difficult to obtain a uniform film with good reproducibility with a polycrystalline film,
There is also a problem that the characteristics cannot be uniformized between manufacturing lots or on the same film, resulting in variations in performance, and low physical property sensitivity such as piezoresistance due to stress in the crystal.

A technical object of the present invention is to form at least one of a fixed part and a movable part of a micromechanical structure from a single crystal film.

D. Means for Solving the Problems To explain the present invention with reference to FIGS. 1 to 3 showing one embodiment, a method for manufacturing a micromechanical structure according to the present invention is formed on a single crystal semiconductor substrate 20, The present invention is applied to a method for manufacturing a micromechanical structure including a fixed part 22 and movable parts 21 and 23 integrated with the substrate 20. Then, a step of selectively implanting ions into the single crystal semiconductor substrate 20, a step of dividing into a first single crystal part and a second single crystal part with the ion implantation layer 31 as a boundary, and a step of etching the ion implantation layer 31 And a step of forming a micromechanical structure in the second single crystal portion to achieve the above technical object.

E. Function Ions are selectively implanted into the single crystal semiconductor substrate 20, an epitaxial layer is grown thereon, and a single crystal layer of the substrate 20 and the epitaxial layer 35 is formed. After that, the ion implantation layer 31 is heat-treated, for example. The single crystal layer is divided into a first crystal part and a second crystal part with the ion implantation layer 31 as a boundary. Further, a cavity is formed in the substrate 20 by etching the ion implantation layer 31, and the movable portion 2 of the micro mechanical structure made of a single crystal is formed in the second crystal portion by using the cavity.
1 and 23 are described. In the above sections D and E for describing the configuration of the present invention, the drawings of the embodiments are used in order to make the present invention easy to understand, but the present invention is not limited to the embodiments. Not something.

F. Examples Hereinafter, examples of the present invention will be described in detail with reference to the drawings.

2 and 3 are a plan view and a sectional view showing a check valve (micromechanical structure) manufactured by one embodiment of the method for manufacturing a micromechanical structure according to the present invention.

The check valve of the present embodiment has the same structure as the check valve of the conventional example, and the valve 2 formed on the silicon substrate 20
1. It comprises a fixing ring 22, a support arm 23, and a through hole 24 formed in the silicon substrate 20. However, in this embodiment, a disc-shaped groove 25 is formed in a range surrounded by the fixing ring 22 on the surface of the silicon substrate 20, and this groove 25 is
The projection 26 is formed on the bottom surface in the vicinity of the through hole 24, so that the depth is slightly reduced. And these valves 2
1. The fixing ring 22 and the support arm 23 are all formed of an epitaxial silicon layer.

Next, an embodiment of a method for manufacturing a check valve according to the present invention will be described with reference to FIG.

First, as shown in FIG. 1A, an oxide film (SiO ₂ ) 30 is formed on a surface of a silicon single crystal substrate 20 having a plane orientation (100) by CVD.
Is deposited. The thickness of the oxide film 30 is, for example, 1 μm.
m. Thereafter, the surface of the oxide film 30 is photo-etched to pattern a portion corresponding to the inside of the fixing ring 22 excluding the protrusions 26. It should be noted that a CVD nitride film (Si ₃ N ₄ ) can be used instead of the oxide film 30. The film thickness in this case may be several thousand mm or more.

Next, as shown in FIG. 1B, oxygen ions are implanted into the surface of the silicon substrate 20 using the oxide film 30 as a mask. The conditions for the ion implantation are, for example, a concentration of about 1.8 × 10 ¹⁸ cm ⁻² at an implantation energy of 200 keV. Thereafter, high-temperature annealing is performed in an inert gas such as N ₂ to form a stable ion-implanted layer 31 inside the silicon substrate 20. Annealing conditions are 2 hours at 1250 ° C. or 30 minutes at 1405 ° C. in N ₂ gas (Solid State Techno)
logy, p.93-98, March (1987)). This ion implantation layer 31 is substantially an SiO ₂ layer. Also, ion implantation layer
The crystallinity of the substrate on the upper part of 31 is sufficiently recovered by this annealing, and is in a single crystal state.

Next, as shown in FIG. 1 (c), after removing the oxide film 30 by etching, an epitaxial silicon layer 32 is deposited on the surface of the silicon substrate 20, and the surface of the epitaxial layer 32 and the surface of the silicon substrate 20 are further removed. Then, an oxide film 33 is deposited by CVD, and portions inside the fixed ring 22 and portions corresponding to the portions where the through holes 24 are formed are removed by photoetching. This epitaxial layer 32 is substantially single crystal. Note that the thickness of the epitaxial layer 32 may be, for example, about 2500 °. Further, instead of the oxide film 33, a CVD nitride film can be used.

Furthermore, as shown in FIG. 1 (d), after re-implanting oxygen ions toward the silicon substrate 20 from the epitaxial layer 32 surface, for example, performs high-temperature annealing in an inert gas such as N _2, epitaxial layer Ion implantation layer directly below 32
Form 34. As an example of ion implantation conditions,
The concentration is about 1.8 × 10 ¹⁸ cm ^-2 at 200 keV. This ion implantation layer 34 is almost a SiO ₂ layer. Thereafter, an epitaxial silicon layer 35 is further deposited on the surface of the epitaxial layer 32. This epitaxial layer 35 is substantially single crystal. The thickness of the epitaxial layer 35 is, for example, 2 μm
It should be about the degree.

Further, as shown in FIG. 1 (e), a photoresist is selectively formed on a portion where the valve 21, the fixing ring 22 and the support arm 23 are formed, and the other portion is used as a mask to perform RIE (reactive ion The dry etching is selectively performed by, for example, etching to expose the ion-implanted layer 34, and the valve 21, the fixed ring 22, and the support arm 23 are formed. After this, silicon substrate
An oxide film 36 is deposited on the surface 20 and the surface of the epitaxial layer 35 by CVD. Of course, it is also possible to substitute a CVD nitride film as described above.

Further, as shown in FIG. 3, a through hole 24 having an inverted V-shaped cross section is formed on the back surface of the silicon substrate 20 by anisotropic etching using, for example, a 35 wt% KOH solution or the like. This through hole 24
The presence of the ion-implanted layers 31 and 34
It is not formed above 1,34. As the other etchant, an alkaline solution-based etchant such as a hydrazine hydrate solution or an amine-based solution can be used. Then, using a hydrofluoric acid solution that selectively dissolves SiO ₂ ,
The grooves 25 are formed by selectively etching the ion-implanted layers 31 and 34. Although the oxide films 33 and 36 are also removed by this etching at the same time, when a nitride film is used instead of the oxide film, the etching may be performed with hot phosphoric acid. Through the above steps, a check valve as shown in FIGS. 2 and 3 is obtained.

In the method of manufacturing the check valve according to the present embodiment by the above-described steps, ions are implanted into the silicon single crystal substrate 20 to form ion implantation layers 31 and 34 in the substrate 20, and the ion implantation layer 31 is formed. , 34, and epitaxial silicon layers 32, 35 on the surface of the silicon substrate 20.
Is deposited and the epitaxial layers 32 and 35 constitute a check valve, so that a single crystal check valve integrated with the silicon single crystal substrate 20 can be obtained. Therefore, as compared with the conventional polycrystalline check valve, sufficient strength can be secured and reliability is improved, and since the surface flatness of parts is also good, reliability is also improved from this aspect. Can contribute. Furthermore, if a single crystal film is used, a uniform material with good reproducibility can be obtained, and variations in performance can be reduced.

FIG. 4 is a view showing another embodiment of the method of manufacturing the micromechanical structure (check valve) according to the present invention. Hereinafter, this embodiment will be described with reference to FIG. 4, but the same reference numerals are given to the same components as those in the above-described embodiment, and the description thereof will be omitted.

First, as shown in FIG. 4 (a), an oxide film 41 is deposited on both surfaces of a silicon single crystal substrate 40 having a plane orientation of (100) by CVD, and a portion corresponding to the inside of the fixed ring 22 and the through hole 24 is formed. The oxide film 41 is removed by photo etching. In addition,
Instead of the oxide film 41, a CVD nitride film may be used.

Next, as shown in FIG. 4 (b), oxygen ions are implanted into the surface of the silicon substrate 40 using the oxide film 40 as a mask, and annealing is performed at a high temperature in an inert gas to form an ion-implanted layer in the silicon substrate 40. Form 42.

Next, as shown in FIG. 4C, after removing the oxide film 41 by etching, an epitaxial silicon layer 43 is deposited on the surface of the silicon substrate 40.

Further, as shown in FIG. 4D, the valve 21 and the fixing ring of the epitaxial layer 43 are formed by photoetching.
A portion where the 22 and the support arm 23 are to be formed is selectively patterned, and an oxide film or a nitride film 44 is deposited thereon by CVD.

Further, as shown in FIG. 4 (e), after forming a through hole 24 on the back surface of the silicon substrate 40 by anisotropic etching with an alkaline solution, a groove 25 selectively etched with SiO ₂ is formed.
To form Then, a check valve can be obtained by removing the oxide film or the nitride films 41 and 44 by etching.

In this embodiment, the same operation and effect as those of the previous embodiment can be obtained. The check valve manufactured according to the present embodiment has a configuration in which the protrusion 26 formed on the bottom surface of the groove 25 is omitted as compared with the check valve according to the previous embodiment. Therefore, if the groove 25 is not formed accurately, for example, if a protrusion remains on the bottom surface of the groove 25 below the support arm 23, the lowering of the valve 21 is prevented, and the opening and closing operation of the entire check valve can be smoothly performed. It may not be done. However, compared to the previous example,
The manufacturing method of this embodiment has the advantage that the steps are simplified, and the configuration is inexpensive and has a high throughput.

Next, FIG. 6 is a cross-sectional view showing a diaphragm structure manufactured by another embodiment of the method for manufacturing a micromechanical structure according to the present invention.

The diaphragm structure of the present embodiment has substantially the same structure as that of the above-described conventional diaphragm structure, and has a cross-sectionally equilateral trapezoidal cavity region on the surface of the silicon substrate 50 in which the width decreases as the depth increases. 51 is formed, the upper portion of the cavity region 51 is covered with a diaphragm portion 53 leaving an etching hole 52, and the etching hole 52 is covered with a polysilicon 54. The diaphragm 53 is made of single crystal silicon.

In the diaphragm structure having the above configuration,
The pressure sensor is formed by forming, for example, a piezoresistor of silicon in the diaphragm portion 53 with the cavity region 51 as a pressure reference chamber, and taking out a change due to the distortion of the diaphragm portion 53 as a change in the piezoresistance value according to a change in the outside air pressure. Can be configured.

A method for manufacturing the diaphragm structure will be described with reference to FIG.

First, as shown in FIG. 5A, a CVD oxide film or a nitride film 60 is formed on a silicon single crystal substrate 50 having a plane orientation (100).
Is deposited, and an oxide film 60 corresponding to the diaphragm 52 is formed.
Is removed by photoetching.

Next, as shown in FIG. 5B, using the oxide film 60 as a mask, oxygen ions are ion-implanted into the surface of the silicon substrate 50, followed by high-temperature annealing in an inert gas to form an ion-implanted layer 61. I do. The conditions for ion implantation are, for example, a concentration of about 1.8 × 10 ¹⁸ cm ^{−2 at} 200 keV. This ion implantation layer 61 is almost SiO ₂ .

Further, as shown in FIG.
After an epitaxial silicon layer 62 is deposited on the surface of the substrate, an etching hole 52 is formed by photoetching. This epitaxial silicon layer 62 is substantially single crystal.

Further, as shown in FIG. 5 (d), after the ion implantation layer 61 is selectively dissolved by a hydrofluoric acid type etching solution to form a disk-shaped cavity 63, the entire surface of the silicon substrate 50 is subjected to CVD.
Then, an oxide film or a nitride film 64 is deposited, and the oxide film on the bottom surface of the etching hole 52 is removed by photoetching.

Further, as shown in FIG. 5 (e), the silicon substrate 50 immediately below the cavity 63 is anisotropically etched with an alkali-based etching solution to form a trapezoidal cavity region 51 having an isosceles cross section.
Form within 50. After that, the oxide film or the nitride film 64 is removed by etching.

Then, for example, during low pressure CVD, a polysilicon 54 is deposited on the surface of the epitaxial layer 62 so as to cover the etching hole 52, and the polysilicon 54 other than the portion of the etching hole 52 is removed by photoetching, as shown in FIG. A diaphragm structure as shown can be manufactured.

In the method of manufacturing a tire diaphragm structure having such a configuration, since the diaphragm portion 53 can be formed of the epitaxial layer 62, that is, a single crystal, the characteristics of the entire diaphragm portion 53 can be made uniform. As a result, the change in the piezo resistance increases, the sensitivity of the pressure sensor can be increased, and a highly accurate pressure sensor can be realized. The number of etching holes 52 formed,
Needless to say, the position can be set to a desired position other than in this example, and the way of closing the holes is not limited to this example.

Next, FIGS. 8 and 9 are a bottom view and a cross-sectional view showing a one-time beam structure manufactured by another embodiment of the method for manufacturing a micromechanical structure according to the present invention. In the figure, reference numeral 71 denotes a truncated pyramid-shaped weight that narrows downward, and is formed by hollowing out the inside of a rectangular support base 72.
71 is supported by a cantilever 73 in a cantilever state.
For example, a piezo resistor (not shown) is formed in 73. Here, 74 is a hollow through hole.

In the cantilever structure having such a configuration, the weight 71 is displaced when acceleration is applied to the entire structure, and the cantilever 73 supporting the weight is distorted to change the piezoresistance value. If a change in the value is detected, it can be used as an acceleration detection sensor.

A method for manufacturing the cantilever structure will be described with reference to FIG.

First, as shown in FIG. 7A, an oxide film or a nitride film 81 is formed on the surface of a silicon single crystal substrate 80 having a plane orientation (100).
Is deposited by CVD, and the oxide film 81 corresponding to the bottom of the cantilever 73 is removed by photoetching. afterwards,
Oxygen ions are ion-implanted into the surface of the silicon substrate 80 using the oxide film 81 as a mask, and high-temperature annealing is performed in an inert gas to form an ion-implanted layer 82 in the silicon substrate 80. Conditions for ion implantation are, for example, 1.8 × 1 at 200 keV.
The concentration is about 0 ¹⁸ cm ^-2 . This ion implantation layer 82 is almost S
is an iO _2.

Next, as shown in FIG. 7B, after removing the oxide film 81 by etching, an epitaxial silicon layer 83 is deposited on the surface of the silicon substrate 80. This epitaxial layer 83 is substantially single crystal.

Further, as shown in FIG. 7C, an oxide film or a nitride film 84 is formed on the surface of the epitaxial layer 83 and the silicon substrate.
After depositing on the back surface of 80, the oxidized surface of the back surface of the silicon substrate 80
Of the 84, the oxide film 84 other than the weight 71 and the support base 72 is removed by photoetching. Further, anisotropic etching is performed using an alkaline etching solution to form the through hole 74 and the cantilever 73. At this time, the alkaline etching solution hardly etches the SiO ₂ , and therefore, the etching of the bottom of the cantilever 73 is completed at the stage when the ion-implanted layer 82 is exposed. It is possible to form. Note that the film formed on the front surface of the epitaxial layer 83 and the back surface of the silicon substrate 80 may be a two-layer film of an oxide film and a nitride film.

Then, by selectively etching the ion implantation layer 82 and the oxide film 84, a cantilever structure as shown in FIGS. 8 and 9 can be manufactured.

In the method of manufacturing such a cantilever structure, the weight 7
1. Since all of the support base 72 and the cantilever 73 can be formed of a single crystal, a high-quality, high-accuracy, and inexpensive acceleration sensor can be obtained as compared with the conventional example. That is, the conventional cantilever structure employs a method in which epitaxial layers having different impurity types are formed on a silicon substrate, and the substrate is removed by (electrolytic) etching with an alkaline etchant under a bias. (For example, TRANSDUCER '87, p.112
~ 115). However, in the case of electrolytic etching, the operation of the apparatus is complicated, the controllability is poor, it is difficult to obtain a stable operation, and the electrochemical reaction in the silicon substrate has a large variation, so that the diameter of the substrate is increased. However, there is a problem that it is difficult to obtain an acceleration sensor with high throughput and good reproducibility. On the other hand, in the present embodiment, it is easy to obtain a uniform film with good reproducibility within a wafer and between lots, and it is possible to increase the diameter of a silicon substrate and obtain a high-throughput acceleration sensor. Can be obtained at a low cost.

Next, FIG. 11 is a cross-sectional view showing a micro gear structure manufactured by another embodiment of the method for manufacturing a micro mechanical structure according to the present invention. In this figure, 90 is a silicon substrate, 91 is a micro gear provided separately on the silicon substrate 90, 92 is a through hole formed at the center of the micro gear 91, 93 is integrated with the silicon substrate 90. And a shaft loosely fitted in the through hole 92 of the micro gear 91. The shaft 93 has a bottomed cylindrical base 94 disposed in the through hole 92.
And a wing 95 extending horizontally outward from the upper end of the base 94, whereby the micro gear 91 is rotatably supported without protruding from the shaft 93. In this embodiment, the micro gear 91 is formed of a single crystal,
93 is formed of polysilicon.

A method of manufacturing the micro gear structure will be described with reference to FIG.

First, as shown in FIG. 10A, an oxide film or a nitride film 100 is deposited on a silicon single crystal substrate 90 having a plane orientation (100).
The oxide film 100 deposited by VD and forming the micro gear 91 is removed by photoetching. After that, using the oxide film 100 as a mask, oxygen ions are ion-implanted into the surface of the silicon substrate 90, and annealing is performed at a high temperature in an inert gas to form the ion-implanted layer 101 in the silicon substrate 90.

Next, as shown in FIG. 10 (b), after removing the oxide film 100 by etching, an epitaxial silicon layer 102 is deposited on the surface of the silicon substrate 90.

Next, as shown in FIG. 10 (c), the part to be the micro gear 91 is formed by etching the epitaxial silicon layer 102. Further, this etching is continued, and the silicon substrate 90 is also etched until the surface of the silicon substrate 90 reaches directly below the ion implantation layer 101. However, the ion implantation layer 10
Needless to say, 1 may be formed over the entire surface of the substrate (FIGS. 10 (a) 'and (b)').

Next, as shown in FIG. 10 (d), an oxide film 103 is deposited on the surface of the silicon substrate 90, and the oxide film 103 on the bottom of the through hole 92 is formed.
Only those are removed by photoetching. Thereafter, a polysilicon film is deposited on the surface of the silicon substrate 90 by LPCVD, and the polysilicon film other than the portion of the axis 93 is removed by photoetching.

Then, by selectively etching the ion-implanted layer 101 and the oxide film 103, a micro gear structure as shown in FIG. 11 can be manufactured.

In the manufacturing method of the micro gear structure having such a configuration, the micro gear 91 can be formed of a single crystal,
It is possible to provide a mechanical component having higher surface flatness, higher precision and higher resistance to abrasion than a conventional micro gear made of polysilicon. Moreover, micro gears
The advantage is that the strength of the 91 itself can be sufficiently ensured, and there is little variation in quality.

In the method of manufacturing a micro gear, after the etching of the epitaxial layer 102 shown in FIG.
It is also possible to adopt a process as shown in FIG.

That is, as shown in FIG.
An oxide film 110 is deposited on the surface of the epitaxial layer 102 and the epitaxial layer 102 by CVD, and the oxide film 110 on the surface of the epitaxial layer 102 is removed by photoetching. Thereafter, using the oxide film 110 as a mask, oxygen ions are ion-implanted into the surface of the epitaxial layer 102, and annealing is performed at a high temperature in an inert gas to form an ion-implanted layer 111 in the epitaxial layer 102.

Further, as shown in FIG. 12 (b), the oxide film 110 is dry-etched by RIE to remove the oxide film 110 other than the portion on the side wall of the epitaxial layer 102. Thereafter, the epitaxial silicon layer 112 is formed by an epitaxial growth method.
And a shaft 93 is formed by photoetching.

Then, as shown in FIG. 12 (c), the ion implantation layers 101 and 111 and the oxide film 110 are also selectively etched by a hydrofluoric acid-based etchant, thereby forming the micro gear 91 and the shaft.
A micro gear structure can be manufactured in which both 93 are formed of a single crystal.

In the step shown in FIG. 12C, a selective epitaxial method (for example, Solid State Technol. Vol. 29, No. 1, p. 107 (198
6), Vol.31, No.5, p.159 (1988), Abs.259, Ext.Abs.V
ol. 87-1, Electrochem. Soc., 1987, etc.), it is possible to obtain a single crystal axis 93 having few defects in a bent portion or the like.
The ultra-thin crystal layer 113 remaining like the ion implantation layer 111 shown in the drawing like a burr can be formed by lightly performing gas etching such as RIE as necessary.
All you have to do is remove the parts other than the bottom.

FIG. 13 is a block diagram showing a method for manufacturing the micromechanical structure described above.

That is, in the embodiment shown in FIG. 1, (I) → (II) → (III) → (IV) → (II) → (III) →
(IV) → (V) → (VI) In the embodiment shown in FIG. 4, (I) → (II) → (III) → (IV) → (V) → (VI) The embodiment shown in FIG. Then, (I) → (II) → (III) → (IV) → (V) → (VI) →
(VII) In the embodiment shown in FIG. 7, (I) → (II) → (III) → (IV) → (V) → (VI) In the embodiment shown in FIG. 10, (I) → (II) ) → (III) → (IV) → (V) → (VI) In the embodiment shown in FIG. 12, (I) → (II) → (III) → (IV) → (V) → (II) →
(III) → (IV) → (V) → (VI) As is clear from the above, the steps (II) and (VI) are essential, but the micromechanical structure to be manufactured for the other steps What is necessary is just to combine suitably according to a body. It goes without saying that combinations other than the above-described steps including the steps (II) and (VI) exist. Also,
By repeating the step (II), the ion-implanted layer can be formed thick.

In the above embodiment, oxygen ions were ion-implanted. Instead, nitrogen ions were ion-implanted to form an ion-implanted layer made of SiN, and this ion-implanted layer was selected with an etching solution such as hot phosphoric acid. Etching may be performed.
Alternatively, a high-concentration impurity layer may be formed by high-concentration ion implantation of ions of boron, phosphorus, arsenic, antimony, antimony, germanium, aluminum, or the like, and the high-concentration impurity layer may be selectively etched. For example, these high concentration impurity layer, 1: 3: 8 (49.23 % HF: 69.51% HNO 3: 99% CH 3 COOH) can be selectively etched with an etching solution (e.g. Elec
trochem. Soc. Extent. Abstr., 72-1, p. 74 (1972)). Further, other ion species such as phosphorus may be ion-implanted while oxygen ions are implanted to form an ion-implanted layer close to PSG.

G. Effects of the Invention As described above, according to the present invention, ions are selectively implanted into a single crystal semiconductor substrate to form an ion-implanted layer,
The first single crystal portion and the second single crystal portion are divided by the ion implantation layer, and the ion implantation layer is etched to form a micromechanical structure, so that the conventional polycrystalline micromechanical structure is compared. As a result, a sufficient strength can be ensured and the reliability can be improved, and the surface flatness of the component is also good, which can contribute to the improvement of the reliability from this aspect as well. Furthermore, if a single crystal film is used, a uniform material with good reproducibility can be obtained, and variations in performance can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory sectional view showing one embodiment of a method for manufacturing a micromechanical structure according to the present invention. FIG. 2 is a plan view showing a check valve manufactured according to the embodiment. FIG. 3 is a sectional view of the same. FIG. 4 is an explanatory sectional view showing another embodiment of the method for manufacturing a micromechanical structure according to the present invention. FIG. 5 is an explanatory sectional view showing another embodiment of the method for manufacturing a micromechanical structure according to the present invention. FIG. 6 is a plan view showing a diaphragm structure manufactured according to the embodiment. FIG. 7 is an explanatory sectional view showing another embodiment of the method for manufacturing a micromechanical structure according to the present invention. FIG. 8 is a bottom view showing the cantilever structure manufactured according to the embodiment. FIG. 9 is a sectional view of the same. FIG. 10 is an explanatory sectional view showing another embodiment of the method for manufacturing a micromechanical structure according to the present invention. FIG. 11 is a sectional view showing a micro gear structure manufactured according to the example. FIG. 12 is an explanatory cross-sectional view showing another embodiment of the method for manufacturing a micromechanical structure according to the present invention. FIG. 13 is a diagram illustrating a method for manufacturing a micromechanical structure. 14 (a) and 14 (b) are a plan view and a cross-sectional view of a micro check valve as an example of a conventional micromechanical structure. FIG. 15 is a sectional view for explaining the manufacturing method. FIG. 16 is a sectional view for explaining a conventional method for manufacturing a diaphragm structure. 20,40,50,80,90: Single-crystal semiconductor substrate 22,51,72,93: Fixed part 21,23,53,71,91: Movable part

Claims (1)

(57) [Claims] 1. A method of manufacturing a micromechanical structure formed on a single crystal semiconductor substrate and comprising a fixed portion and a movable portion integrated with the substrate, wherein the single crystal semiconductor substrate is selectively ionized. Implanting; a step of dividing the ion implantation layer into a first single crystal part and a second single crystal part; a step of etching the ion implantation layer; and a micromechanical structure in the second single crystal part. And a step of forming a body.