JPH10303434A - Manufacture of semiconductor working parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor working parts manufacturing method in which an electronic circuit forming processing requiring high-temperature heat treatment and a sensing section forming process requiring no high- temperature heat treatment are separated from each other and silicon substrates can be polished and worked easily at the time of forming the sensing section. SOLUTION: An electronic circuit 4, such as the FET, etc., is formed on the surface of a silicon substrate and a ultraviolet-ray transmissive substrate 14 is stuck to the surface of the silicon substrate with an adhesive sheet 13 in between. Then a silicon thin plate 12a is obtained by polishing the rear surface of the silicon substrate and the recessed section 1a side of a supporting substrate 1 having the recessed section 1a is stuck to the polished rear surface of the thin plate 12a. Thereafter, the adhesive sheet 13 is stripped off from the thin plate 12a together with the ultraviolet-ray transmissive substrate 14 by reducing the adhesion of the sheet 13 by irradiating the sheet 13 with ultraviolet rays from the substrate 14 side. Finally, a sensing section is formed on the surface of the thin plate 12a by the photoetching technology.

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 processed part such as an acceleration sensor and an angular velocity sensor.

[0002]

2. Description of the Related Art In recent years, semiconductor processed parts composed of small capacitive sensors such as acceleration sensors and angular velocity sensors or piezoelectric sensors have been used in navigation systems such as automobiles, posture control devices for robots, and camera shake prevention devices. Demand is coming out. Among such small semiconductor processed parts, the capacitance type sensor has a sensing part having a movable electrode part for detecting acceleration or angular velocity, an electronic circuit part for converting the detection capacitance of the sensing part into a voltage, and the like. ing. Further, the piezoelectric sensor has a sensing unit, an electronic circuit unit for converting a detection voltage detected by the sensing unit into acceleration or angular velocity, and the like.

[0003] A bonded substrate formed by bonding a silicon substrate and a glass substrate by anodic bonding is used for the manufacture of the semiconductor processing component. After the anodic bonding, the bonded substrate is polished and processed into a silicon thin plate, and the polished surface is mirror-finished. Then, an electronic circuit portion and a sensing portion of the detection circuit are formed on the mirror surface of the silicon thin plate.

[0004]

However, the conventional method of manufacturing a semiconductor processed part is to form an electronic circuit portion such as a capacitance-voltage converter on a silicon thin plate of a bonding substrate.
For example, in activation of implanted ions, thermal oxidation, etc., 60
A high temperature heat treatment of 0 to 1200 ° C. is required, and the bonded substrate warps due to the difference in thermal expansion between silicon and glass, and mobile ions (Na ⁺ ions) from the glass substrate are FE
Adhering to the gate electrode of T (field effect transistor) has a bad influence such as causing a change in threshold voltage.

Further, in the conventional method of manufacturing a semiconductor processed part, a silicon substrate is polished into a silicon thin plate, and then the polished surface of the silicon thin plate is mirror-finished to form an electronic circuit portion on the polished surface of the silicon thin plate. Needed to be processed.

Therefore, the present invention separates a process for forming an electron circuit that requires a high-temperature heat treatment process from a process for forming a sensing portion that does not require a high-temperature heat treatment, and provides a silicon substrate for forming a sensing portion. It is an object of the present invention to provide a method of manufacturing a semiconductor processed component which facilitates polishing and processing of a semiconductor.

[0007]

According to a first aspect of the present invention, there is provided a process for forming at least an electronic circuit portion by processing a region of one main surface of a silicon substrate, and forming the electronic circuit portion on the silicon substrate. A step of bonding the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet having pressure-sensitive adhesive strength to at least one surface, and a step of bonding an ultraviolet-transparent substrate to another surface of the pressure-sensitive adhesive sheet, Polishing the other main surface of the silicon substrate into a silicon thin plate, and bonding the polishing surface of the silicon thin plate to the concave portion forming surface of the support substrate having a concave portion on one main surface side with an adhesive. Irradiating the pressure-sensitive adhesive sheet with ultraviolet rays from the ultraviolet-transparent substrate side to reduce the adhesive force thereof, and peeling the pressure-sensitive adhesive sheet together with the ultraviolet-transparent substrate from the silicon thin plate; Using a photoresist forms a mask to form the sensing portion by etching the silicon thin, in which more made.

According to the present invention, an electronic circuit portion requiring high-temperature heat treatment is formed on a silicon substrate in a pre-stage process.
In a later step, a silicon substrate is bonded to an ultraviolet-transmissive substrate such as glass or plastic to form a bonding substrate, and then the silicon substrate is polished to form a silicon thin plate, which does not require high-temperature heat treatment. Form a sensing part. Therefore, among the bonded substrates having different thermal expansion coefficients between the silicon substrate and the ultraviolet light transmitting substrate, the ultraviolet light transmitting substrate is not exposed to the high temperature heat treatment.

As described above, by processing the electronic circuit section and the sensing section having different thermal processing conditions in the first step and the second step, the electronic circuit section and the sensing section can be easily and easily formed on the same silicon thin plate. It can be manufactured efficiently.

Further, by manufacturing the electronic circuit section and the sensing section on one silicon thin plate adhered to a supporting substrate such as an ultraviolet transmitting substrate, the chip area is reduced, and the influence of parasitic capacitance and noise is reduced.

[0011] Further, the silicon substrate and the ultraviolet-transmissive substrate are bonded together via an adhesive sheet whose adhesive force is reduced by irradiation with ultraviolet rays. The ultraviolet transmitting substrate serves as a holding structure when mechanically polishing the silicon substrate, and also serves as a mask when performing chemical polishing.

After polishing the silicon substrate, the pressure-sensitive adhesive sheet is irradiated with ultraviolet rays to reduce the adhesive force thereof to 1/10 to 1/10.
The pressure is reduced to about 0, and the pressure-sensitive adhesive sheet is peeled off from the silicon thin plate together with the ultraviolet-transmitting substrate.

Further, a support substrate having a concave portion is bonded to the polished surface of the silicon thin plate. This recess provides a vibrating space for the movable electrode portion of the sensing section.

According to a second aspect of the present invention, there is provided a process for forming at least an electronic circuit portion by processing a region of one main surface of a silicon substrate, and forming a region of one main surface of the silicon substrate including the electronic circuit portion. A step of adhering the adhesive surface of an adhesive sheet having an adhesive force to at least one surface over the entire surface, a step of adhering an ultraviolet-transparent substrate to the other surface of the adhesive sheet, and Polishing a surface to a silicon thin plate, bonding the insulating film of a support substrate having an insulating film formed on one principal surface to the polished surface of the silicon thin plate with an adhesive, and transmitting the ultraviolet light to the ultraviolet light. Irradiating the adhesive sheet from the non-conductive substrate side to reduce its adhesive strength,
Removing the adhesive sheet from the silicon thin plate together with the ultraviolet-transparent substrate, and using a photoresist formed on the surface of the silicon thin plate as a mask, etching the silicon thin plate to provide a sensing unit having a movable part and a fixed part. And the step of etching and removing the insulating film below the movable part of the sensing part.

The present invention is the same as the first aspect in utilizing the function of the pressure-sensitive adhesive sheet. According to the present invention, in particular, an insulating film such as silicon oxide is provided on a support substrate, and this insulating film is partially used as a sacrificial layer, which is etched to form a space in which the movable electrode portion of the sensing unit freely vibrates.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an acceleration sensor according to an embodiment of the present invention will be described below with reference to FIGS. Reference numeral 1 denotes a support substrate made of glass or the like, which has a rectangular concave portion 1a at the center of one main surface. The concave portion 1a provides a free vibration space to a movable electrode portion of a sensing unit described later. Reference numeral 2 denotes a fixed electrode portion formed by processing a silicon substrate bonded on the support substrate 1 with an adhesive 3. The fixed electrode portion 2 has a convex flat surface as shown by a point set portion in FIG. 1, and three fixed electrode fingers 2 a extending parallel to each other and extending in the longitudinal direction of the substrate 1 on the protrusion portion. have. Then, a pair of fixed electrode portions 2, 2 are arranged in plane symmetry at intervals at the tips of the fixed electrode fingers 2 a, 2 a, and are arranged on both sides in the longitudinal direction of the substrate 1. In this case, the fixed electrode finger 2 a is
a.

In the area of the convex planar portion of the fixed electrode portion 2, an electronic circuit portion 4 composed of a capacitance / voltage conversion circuit as shown in FIG. It is formed insulated by. Reference numerals of the elements and terminals of the electronic circuit unit 4 shown in FIG. 2 are described in the corresponding parts of the electronic circuit unit 4 shown in FIG. 1, and the operation will be described later.

On the other hand, a sensing part 5 composed of four anchor parts 5a, two support beams 5b, a support handle 5c, and a movable electrode finger 5d is formed by the same silicon substrate on which the fixed electrode part 2 is formed. The four anchor portions 5a are respectively formed near the shoulders of the convex flat surface of the fixed electrode portion 2. The two support beams 5b are supported between anchor portions 5a, 5a arranged opposite to the longitudinal direction of the support substrate 1, respectively. The support handle 5c includes two support beams 5b,
Both ends are supported by an intermediate portion of 5b, and the left and right fixed electrode portions 2, 2 are located at the position of the plane of symmetry where they are arranged in plane symmetry. On both sides of the support pattern 5c, a plurality of movable electrode fingers 5d extend in the longitudinal direction of the substrate 1 and face the fixed electrode fingers 2a with a gap therebetween to form a capacitor. Next, the operation of the acceleration sensor 10 shown in FIGS. 1 and 10 will be described. The acceleration sensor 10 is mounted on a moving body such as an automobile such that the longitudinal direction of the support handle 5c is in the traveling direction of the moving body. Then, when the moving body accelerates, the movable electrode portions (5b to 5d) of the sensing unit 5 cannot follow the acceleration due to its inertia depending on the mounting direction of the acceleration sensor 10, and the support beam 5b is bent to fix the fixed electrode finger. 2a and the movable electrode finger 5d approach or separate from each other, and the capacitance formed between them increases or decreases. The amount of change in the capacitance can be converted into a voltage to determine the acceleration. In relation to the electronic circuit section 2, the fixed electrode finger 2a shown in FIG. 1 is directly connected to the gate G of the FET, and the capacitance change amount ΔC detected by the fixed electrode finger 2a is connected to the gate G. Upon input, the FET converts the capacitance change ΔC into a voltage, and outputs the converted voltage from an output terminal Vout connected to the source S. Next, a method of manufacturing the acceleration sensor 10 shown in FIG. 1 will be described. In FIG. 3, the thickness is 200 to 300 μm.
On both sides of the surface of the silicon substrate 12 in the longitudinal direction.
The electronic circuit units 4 and 4 including a voltage conversion circuit and the like are formed by using a well-known semiconductor circuit forming technique. At the same time, impurities such as boron are implanted into regions where the four anchor portions 5a of the sensing portion 5 of the silicon substrate 12 are to be formed, thereby forming the ohmic contact anchor portions 5a.

As shown in FIG. 2, the electronic circuit units 4 and 4
FET, diode Dg for determining the potential between source S and gate G of this FET, source resistance Rs, power supply terminal Vdd, source output terminal Vout, ground terminal GND
And wiring patterns for connecting terminals.

In FIG. 4, the adhesive surface of an adhesive sheet 13 having an adhesive force on one side is adhered to the entire surface of the silicon substrate 12 on which the electronic circuit section 4 and the like are formed. This adhesive sheet 13 has a width substantially equal to that of the silicon substrate 12,
The length is formed slightly longer than the silicon substrate 12.
The adhesive sheet 13 is, for example, conventionally used for dicing silicon wafers, and has about 1
A UV-curable surface protection tape (product name SP-594M-1) manufactured by Furukawa Electric Co., Ltd. having an adhesive strength of about 3 g / m2.
30) can also be used. According to this, the adhesive strength is reduced to about 1/70 by ultraviolet irradiation.

In the present invention, as the pressure-sensitive adhesive sheet, not only one surface but also a surface having a pressure-sensitive adhesive force on both surfaces can be used.

In FIG. 5, an ultraviolet-transparent substrate 14 such as glass or plastic having substantially the same area as the silicon substrate 12 is bonded to the silicon substrate 12 so as to correspond to the ultraviolet-transparent adhesive 3a such as epoxy or phenol.
To adhere to the other surface of the adhesive sheet 13.

In FIG. 6, an ultraviolet-transparent substrate 14 is used as a polishing or etching
2 is mechanically polished or etched to form a silicon thin plate 12a having a thickness of about 10 to 50 μm. The surface to be polished or etched does not need to be mirror-polished. On the contrary, since it becomes an adhesive surface, it is desirable to have an appropriate roughness to increase the adhesive strength.

In FIG. 7, the polished surface of the silicon thin plate 12a has substantially the same area as the silicon thin plate 12a.
The concave portion forming surface side of the support substrate 1 having the concave portion 1a on one main surface side is adhered with an adhesive 3 such as an epoxy type. The support substrate 1 is made of Pyrex glass, silicon, ceramic, resin, or the like. The concave portion 1a of the support substrate 1 is provided with a movable electrode portion (5b to 5d) of the sensing unit 5 shown in FIG.
To provide a free vibration space.

Referring to FIG. 8, the adhesive sheet 13 is irradiated with ultraviolet rays from the side of the ultraviolet ray transmitting substrate 14 as shown by arrows.

In FIG. 9, the irradiation of the ultraviolet rays
The pressure-sensitive adhesive sheet 13 is cured to reduce its adhesive force, and the pressure-sensitive adhesive sheet 13 is peeled off from the silicon thin plate 12a together with the ultraviolet-transparent substrate 14.

In FIG. 10, the electronic circuit section 4 shown in FIG.
The photoresist is patterned on the surface of the silicon thin plate 12a in the planar shape of the fixed electrode unit 2 and the sensing unit 5 including. Using this photoresist as a mask, 6
The silicon thin plate 12a is processed into a plane shape shown in FIG. 1 and a cross-sectional shape shown in FIG. 10 by reactive ion etching (RIE) using sulfur fluoride (SF ₆ ), so that the fixed electrode portion 2 and the sensing portion 5 are formed. Form.

Here, since the movable electrode portion of the sensing portion 5 including the support beam 5b, the support handle 5c and the movable electrode finger 5d is formed on the concave portion 1a of the support substrate 1, it can freely vibrate.

Next, a description will be given of a second embodiment of the method for manufacturing a semiconductor processed part according to the present invention with reference to the accompanying drawings. In the second embodiment, among the manufacturing steps, the steps in FIGS. 3 to 6 are the same as those in the first embodiment, and thus the description is referred to, and FIGS. 11 to 14 will be described.

In FIG. 11, the insulating surface of the support substrate 11 having the same area as the silicon thin plate 12a on the polished or etched surface of the silicon thin plate 12a and having one main surface on which an insulating film 11a such as silicon oxide is formed. The film 11a is adhered by the adhesive 3b.

In FIG. 12, an ultraviolet ray is applied to the adhesive sheet 13 from the side of the ultraviolet ray transmitting substrate 14 as shown by an arrow.

In FIG. 13, the adhesive sheet 13 is cured by the irradiation of the ultraviolet light, and the adhesive force is reduced to about 1/70 as compared with that before the ultraviolet light irradiation.
The adhesive sheet 13 is peeled off from the substrate 2a together with the ultraviolet-transparent substrate 14.

In FIG. 14, the electronic circuit section 4 shown in FIG.
The photoresist is patterned on the surface of the silicon thin plate 12a in the planar shape of the fixed electrode unit 2 and the sensing unit 5 including. Using this photoresist as a mask, 6
The silicon thin plate 12a is processed into a planar shape shown in FIG. 1 by reactive ion etching (RIE) using sulfur fluoride (SF ₆ ), and the fixed electrode portion 2 and the sensing portion 5 are processed.
To form

Then, using the photoresist as a mask, the adhesive 3b is removed by isotropic dry etching such as O ₂ (oxygen) ashing. Next, similarly,
Using the photoresist as a mask, hydrofluoric acid (HF) is used as an etchant, and an insulating film 11a under and near the movable electrode portions (5b to 5d) of the sensing unit 5 is provided.
(It is called a sacrificial layer) and the exposed insulating film 11a around the fixed electrode portion 2 is removed by wet etching.

Thus, the movable electrode portion of the sensing section 5, ie, the support beam 5b, the support handle 5c and the movable electrode finger 5
Air gaps 11b are formed in the lower part of d and in the vicinity thereof, and these can freely vibrate.

[0036]

According to the first aspect of the present invention, an electronic circuit portion requiring a high-temperature heat treatment is manufactured in a previous step, and a sensing portion not requiring a high-temperature heat treatment is formed by a silicon substrate and an ultraviolet-transparent substrate. After the bonding, is produced in a subsequent step. Therefore, among the bonded substrates having different thermal expansion coefficients between the silicon substrate and the ultraviolet-transmitting substrate, the ultraviolet-transmitting substrate is not exposed to a high-temperature heat treatment, so that the bonding substrate does not warp, and The scattering of impurities does not adversely affect the electronic circuit section, and the electronic circuit section and the sensing section can be easily and efficiently manufactured on one silicon substrate.

As described above, since the electronic circuit portion and the sensing portion are formed on one silicon substrate adhered to the support substrate, a semiconductor processed component having a small chip area and little influence of parasitic capacitance and noise can be realized. .

In addition, the silicon substrate is bonded to the ultraviolet-transmissive substrate via an adhesive sheet whose adhesive force is reduced by irradiation with ultraviolet rays, and the silicon substrate is polished into a thin plate, so that the silicon substrate can be easily polished. .

One main surface of the silicon substrate is mirror-finished in advance, and an electronic component circuit is formed on the mirror surface, and the other surface of the silicon substrate is polished to a thin plate.
Since the supporting substrate is adhered to the polished surface without forming the element, it is not necessary to mirror-finish the polished surface as compared with the case where the element is formed on the polished surface as in the related art. Conversely,
Since the adhesive surface has an appropriate roughness, an effect of increasing the adhesive force is obtained.

Further, a support substrate having a concave portion is bonded to the polished surface of the silicon thin plate. This recess provides a vibrating space to the movable electrode portion of the sensing unit, and does not require a separate so-called sacrifice layer etching step.

According to a second aspect of the present invention, as described above,
The effect derived from the function of the pressure-sensitive adhesive sheet is the same as that of the first aspect. However, the present invention is characterized in that the support substrate according to the first aspect of the present invention has a concave portion on one main surface side, whereas the support substrate has an insulating layer on one main surface side. However, this is different from the first aspect. Although the concave portion provides a space for free vibration in the movable electrode portion of the sensing portion, in the present invention, a part of the insulating layer is used as a sacrificial layer, and the sacrificial layer is etched to form the same as the concave portion. Can be formed. Further, according to the present invention, since the protection gap for the free vibration can be formed according to the shape of the movable part after the processing of the sensing part, the precision in positioning when bonding the support substrate to the polished surface of the silicon thin plate is improved. Not required.

[Brief description of the drawings]

FIG. 1 is a plan view of an acceleration sensor in a method of manufacturing an acceleration sensor as an embodiment of the method of manufacturing a semiconductor processed part according to the present invention.

FIG. 2 is a circuit diagram of an electronic circuit unit of the acceleration sensor shown in FIG.

FIG. 3 shows a method for manufacturing an acceleration sensor as a first embodiment of the method for manufacturing a semiconductor processed part according to the present invention, and is a process chart for forming an electronic circuit portion on a silicon substrate.

[FIG. 4] Similarly, a process diagram of attaching an adhesive sheet to a silicon substrate.

FIG. 5 is also a process chart for bonding an ultraviolet-transparent substrate to an adhesive sheet.

FIG. 6 is also a process diagram of polishing a silicon substrate into a thin film.

FIG. 7 is a process chart for bonding a supporting substrate to a silicon thin plate.

FIG. 8 is a process chart of irradiating the adhesive sheet with ultraviolet rays.

FIG. 9 is also a process diagram of peeling off the adhesive sheet whose adhesive force has been reduced by ultraviolet irradiation together with the ultraviolet-transparent substrate from the silicon thin plate.

FIG. 10 is also a process chart of forming a sensing portion on a silicon thin plate by photoetching.

FIG. 11 shows a second example of the method of manufacturing a semiconductor processed part according to the present invention.
FIG. 4 illustrates a method of manufacturing an acceleration sensor as an example,
Process diagram of bonding support substrate to silicon thin plate

FIG. 12 is a process chart of irradiating the adhesive sheet with ultraviolet rays.

FIG. 13 is a process chart of peeling off the adhesive sheet whose adhesive strength has been reduced by ultraviolet irradiation together with the ultraviolet-transparent substrate from the silicon thin plate.

FIG. 14 is a process chart of forming a sensing portion on a silicon thin plate by photo-etching, and etching the silicon oxide under the movable electrode portion of the sensing portion and exposed silicon oxide.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 11 Support board 1a Depression 2 Fixed electrode part 2a Fixed electrode finger 3, 3a, 3b Adhesive 4 Electronic circuit part 5 Sensing part 5a Anchor part 5b Support beam 5c Support pattern 5d Movable electrode finger 10, 20 Acceleration sensor 11a Silicon oxide 11b Void 12 Silicon substrate 12a Silicon thin plate 13 Adhesive sheet 14 UV transparent substrate

Claims (2)

[Claims] A step of forming at least an electronic circuit portion by processing a region of one main surface of a silicon substrate; and forming at least one surface on an entire surface of one main surface of the silicon substrate including the electronic circuit portion. Bonding the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet to a pressure-sensitive adhesive sheet; bonding a UV-transparent substrate to the other surface of the pressure-sensitive adhesive sheet; polishing another main surface of the silicon substrate to form a silicon thin plate And a step of bonding, with an adhesive, the concave portion forming surface of the support substrate having a concave portion on one main surface side to the polished surface of the silicon thin plate, and the adhesive sheet from the ultraviolet ray transmitting substrate side with ultraviolet rays. Irradiating the adhesive sheet with the ultraviolet light-transmitting substrate and peeling the adhesive sheet from the silicon thin plate; and using a photoresist formed on the surface of the silicon thin plate as a mask. Forming a sensing part by etching the silicon thin plate using the method. 2. a step of forming at least an electronic circuit portion by processing a region of one main surface of the silicon substrate; and forming at least one surface over the entire main surface of the silicon substrate including the electronic circuit portion. Bonding the pressure-sensitive adhesive surface of the pressure-sensitive adhesive sheet to a pressure-sensitive adhesive sheet; bonding a UV-transparent substrate to the other surface of the pressure-sensitive adhesive sheet; polishing another main surface of the silicon substrate to form a silicon thin plate And bonding the insulating film side of a support substrate having an insulating film formed on one principal surface thereof to the polished surface of the silicon thin plate with an adhesive; Irradiating the sheet to reduce its adhesive strength, peeling the adhesive sheet from the silicon thin plate together with the ultraviolet transparent substrate, and using a photoresist formed on the surface of the silicon thin plate as a mask Forming a sensing part having a movable part and a fixed part by etching the silicon thin plate; and etching and removing an insulating film below the movable part of the sensing part. Manufacturing method.