JP2009105277A - Semiconductor device, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device which has such a MEMS structure that a semiconductor integrated circuit and a movable portion having a movable part are formed into a semiconductor chip, and can reduce the size of the chip, and further, can detect the operation and operational direction of the chip, and to provide a manufacturing method of the semiconductor device. <P>SOLUTION: In the semiconductor device, a movable part 10 of a MEMS portion is formed on a beam 28 present on a semiconductor layer 13. The beam 28 comprises an insulating film 26 and a polysilicon film 27, and a resistance, etc., can be utilized therefor. The movable part 10 is disposed in a recessed portion 6 formed on each inter-layer insulating film 8, 14, and its lower end is joined to the polysilicon film 27 of the beam 28, and further, its upper end is free. A cavity 7 is formed in a portion having the formed beam 28, and moreover, the beam comprises a hollow structure. The movable part 10 receives stress by the acceleration of a chip so that its end moves. By the movement of the chip, a spatial distance interposed between the movable part 10 and each of electrodes 91-98 is so varied as to be able to detect the variation of capacitance interposed between each electrode and the movable part 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device, and more particularly to a micro electro mechanical systems (MEMS) device in which a system including an electrical element and a mechanical element is formed on one chip.

  2. Description of the Related Art Conventionally, a MEMS device in which a system including an electrical element and a mechanical element is packaged is one in which a MEMS chip is mounted on a wiring board in each chip such as a logic or an analog circuit constituting a semiconductor integrated circuit. . A semiconductor integrated circuit is mainly composed of, for example, a CMOS and includes a resistor and a capacitor. In addition, the conventional MEMS chip forms a recess and a movable part by etching the surface of the silicon semiconductor substrate, and the movable part made of silicon fixes one end in the recess and the space in the recess, the movable part, and the semiconductor. A capacitor is composed of the substrate. In the capacitor, the space is a dielectric, and the movable part and the semiconductor substrate are electrodes. The semiconductor substrate includes a silicon single crystal substrate, a silicon oxide film formed thereon, and a silicon active layer formed on the silicon oxide film. The movable part is formed in this active layer. A wiring is formed on the surface of the semiconductor substrate via an insulating film so as to cover the recess. One end of the movable portion is fixed to the wiring, and the other end protrudes in a free state without being connected to the other inside the recess. The movement of the MEMS chip can be sensed by causing the tip of the movable part to contact the semiconductor substrate by an acceleration force and short-circuiting the capacitor.

As for the MEMS device, the conventional process adopts a structure based on a thick film SOI substrate. The thick film SOI substrate uses a thick film having an active layer portion thickness of 8 to 10 μm. However, this device has the following problems.
(1) At the time of device shrinkage, particularly when a semiconductor integrated circuit such as a CMOS circuit is formed, since a capacitance around a well is not reduced in a thick film SOI substrate, device shrinkage becomes difficult.
(2) Since the MEMS structure is built on a silicon wafer, correction from 1S is required when performing device correction.
(3) In a device that senses the operation direction, it is necessary to make all of the devices in the direction that senses the operation direction, resulting in an increase in device size.

Patent Document 1 discloses an angle detection sensor with good assembling workability. It consists of a plurality of switching elements that are turned ON / OFF according to the posture (inclination) of the object, and the posture of the object can be detected by the ON / OFF state of these switching elements. It has four conductive pins arranged at equiangular intervals from the center, and a conductive rotating body arranged so as to be rotatable in contact with the pins in a region surrounded by the four pins.
JP-A-9-138119

  The present invention has been made to solve the above problems, and has a MEMS structure in which a semiconductor integrated circuit portion and a movable portion having a movable portion are formed in one semiconductor chip, and the reduction of the chip. A semiconductor device and a method of manufacturing the same are provided.

  One embodiment of a semiconductor device of the present invention includes a single crystal substrate, a semiconductor substrate including a semiconductor layer formed over the single crystal substrate with an insulating oxide film interposed therebetween, and a semiconductor integrated circuit formed over the semiconductor substrate; A movable part having a movable part formed on the semiconductor substrate and spaced apart from the semiconductor integrated circuit, and a multilayer wiring layer formed on the semiconductor substrate, the movable part comprising the semiconductor layer Formed in a concave portion of the multi-layer wiring, and is formed from a connection wiring for connecting the wirings of the multilayer wiring up and down, the lower end of the movable portion is connected to a predetermined wiring of the multilayer wiring, and the upper end does not contact with the other in the concave portion It is characterized by protruding.

  One aspect of a method for manufacturing a semiconductor device according to the present invention includes a step of forming a semiconductor integrated circuit on a semiconductor substrate including a single crystal substrate and a semiconductor layer formed on the single crystal substrate with an insulating oxide film interposed therebetween; Forming a multilayer wiring layer on the semiconductor substrate; forming a concave portion in a movable portion formed on the semiconductor substrate apart from the semiconductor integrated circuit; and forming a movable portion in the concave portion. The movable part is formed of a connection wiring that connects the multilayer wirings up and down, the lower end of the movable part is connected to a predetermined wiring of the multilayer wiring, and the upper end is not in contact with the other in the recess. It is characterized by protruding.

  According to the present invention, the movable portion is shortened to the same length as the connection wiring by the above configuration, and the semiconductor integrated circuit can be made into one chip, and the metal wiring for connecting the semiconductor integrated circuit and the MEMS portion is unnecessary. Therefore, it is possible to reduce the size of the semiconductor chip and to detect the operation and the operation direction.

  Hereinafter, embodiments of the invention will be described with reference to examples.

First, Embodiment 1 will be described with reference to FIGS.
FIG. 1 is a schematic plan view of a semiconductor chip described in this embodiment, and FIG. 2 is a CMOS portion in which a transistor of a semiconductor integrated circuit portion of the semiconductor chip in FIG. 1 is formed and a resistance portion in which a resistor is formed. 3 is a partial cross-sectional view showing a capacitor portion in which a capacitor of the semiconductor integrated circuit portion of the semiconductor chip of FIG. 1 is formed, and FIG. 4 is a MEMS structure of the semiconductor chip of FIG. FIG. 5 is a plan layout view of an electrode structure for explaining the function of the MEMS structure shown in FIG. 4, and FIG. 6 is a process sectional view for forming the MEMS structure.
As shown in FIG. 1, in a semiconductor chip 1 made of a semiconductor substrate such as silicon, a movable part (hereinafter referred to as a MEMS part) 2 having a movable part and a semiconductor integrated circuit part 3 are formed at an interval. The semiconductor integrated circuit includes a logic circuit 4, an analog circuit 5, and the like, and is composed of a CMOS transistor, a resistor, a capacitor, and the like.

  As shown in FIG. 2, the semiconductor substrate constituting the semiconductor chip 1 is a semiconductor single crystal substrate 11 such as silicon, and an insulating oxide film (Box layer) 12 formed on the semiconductor single crystal substrate 11 and epitaxially grown silicon. It is comprised from the semiconductor layer 13 which consists of. In the semiconductor layer 13, an active layer 17 which is an element region in which a transistor such as a CMOS or a passive element is formed and an element isolation region 18 having an STI (Shallow Trench Isolation) structure are formed. On the semiconductor layer 13, an interlayer insulating film 14 such as a silicon oxide film or a silicon nitride film on which a multilayer wiring is formed is formed. In FIG. 2A, a plurality of transistors constituting a semiconductor integrated circuit are formed. The gate 15 of the transistor is formed on the active layer 17. The transistor and the wiring (not shown) of the multilayer wiring layer are electrically connected via the connection wiring 16. The resistor 20 constituting the semiconductor integrated circuit is formed on the element isolation region 18 via an insulating film 19 such as a silicon nitride film, and connected to a wiring (not shown) of a multilayer wiring layer by a connection wiring 21.

  The connection wiring 21 constitutes a pair of lead electrodes of the resistor 20. The resistor 20 is made of polysilicon (FIG. 2B). The capacitor 25 constituting the semiconductor integrated circuit is formed on the element isolation region 18 and connected to the wiring (not shown) of the multilayer wiring layer by the connection wiring 24. The capacitor 25 uses the active layer of the semiconductor substrate as one electrode (lower electrode), the insulating film 22 on the semiconductor layer 13 as a dielectric, and the polysilicon film 23 on the insulating film 22 as the other electrode (upper electrode). Yes. The connection wiring 24 constitutes an extraction electrode for the upper electrode and the lower electrode (FIG. 3).

  The MEMS portion of the semiconductor chip and its function will be described with reference to FIGS. The movable part 10 is formed on the beam 28. The movable part 10 is also called a pillar. The beam 28 is formed on the semiconductor layer 13 and includes an insulating film 26 made of a silicon nitride film formed on the semiconductor layer 13 and a polysilicon film 27 formed on the insulating film 26. As the beam 28, a resistor or a capacitor of a semiconductor integrated circuit portion can be used. The beam 28 is covered with an interlayer insulating film 14 and an interlayer insulating film 8 formed from a silicon oxide film or a silicon nitride film formed on the interlayer insulating film 14, and the movable portion (pillar) 10 is attached to the interlayer insulating films 8 and 14. It is arranged in the formed recess 6, the lower end is joined to the polysilicon film 27 of the beam 28, and the upper end is in a free state. A cavity 7 is formed in a portion of the semiconductor substrate where the beam 28 is formed, and the beam portion has a hollow structure. The movable portion 10 is housed in the recess 6 of the two-layer interlayer insulating films 8 and 14, and the height of the movable portion 10 is 2 × 0.4 μm at most because the interlayer insulating films 8 and 14 are each 0.4 μm or less. Or less.

On the semiconductor layer 13, an interlayer insulating film 14 and an interlayer insulating film 8 are formed on the interlayer insulating film 14. A first layer wiring 30 constituting a multilayer wiring layer is formed on the surface of the interlayer insulating film 14. In order to electrically connect the wiring 30 to the transistor and the passive element, a connection wiring 29 embedded in the interlayer insulating film 14 is used. Similarly, a second layer wiring (not shown) is formed on the interlayer insulating film 8. The first layer wiring 30 and the second layer wiring are electrically connected by a connection wiring 31.
The movable part 10 which is a feature of this embodiment uses connection wiring. That is, the movable portion 10 is composed of connection wirings 29 and 31 stacked with the first-layer wiring 30 interposed therebetween. Further, as shown in FIG. 5, a plurality of electrodes 91 to 98 (eight in this embodiment, for example) are formed on the interlayer insulating film 8 at intervals along the outer periphery of the recess 6. . Thus, the movable part 10 is opposed to the electrodes 91 to 98 which are the other electrodes as one electrode, and constitutes a capacitor using the space of the recess 6 as a dielectric. The movable part 10, which is one electrode of the capacitor, is connected to the polysilicon film 27 constituting the beam 28, and is connected to the outside via the connection wiring 29, the first layer wiring 30 and the connection wiring 31 connected to the polysilicon film. It is connected to a terminal (not shown).

The semiconductor device of this embodiment, that is, a MEMS device has the above-described configuration.
Next, with reference to FIG. 5, the effect of the MEMS part of a MEMS device is demonstrated. The movable portion 10 receives stress due to the acceleration of the semiconductor chip and the tip portion moves. In the figure, when an acceleration force is applied in the direction of arrow A, the movable unit 10 moves in the direction of arrow B. Then, it is known that the semiconductor chip has moved when the tip of the movable portion contacts the electrodes 91 and 92. Moreover, the distance of the space between the movable part 10 (it becomes movable part 10 ') and the electrodes 91-98 changes with the movement of a semiconductor chip. Therefore, the direction of movement can be known by detecting the change in capacitance between each electrode and the movable portion 10. That is, in this embodiment, it is possible to detect the movement and know the operation direction.

Next, a manufacturing method of the MEMS device will be described with reference to FIG.
A transistor such as a CMOS, a resistor, a capacitor, etc. constituting a semiconductor integrated circuit are formed on the semiconductor layer 13 constituting the semiconductor substrate, and the beam 28 is formed in the same process as that for forming the resistor or the capacitor in the movable part (MEMS part). To do. On the active layer 17, the gate 15 of one transistor is displayed.
Next, the manufacturing process of the multilayer wiring part will be described. An interlayer insulating film 14 such as a silicon oxide film is formed on the semiconductor layer 13 and the surface thereof is planarized. A resist is applied to the planarized surface, this is patterned, and the interlayer insulating film 14 is etched using this as a mask to form contact holes. Next, a metal such as aluminum or copper is deposited on the contact hole and the surface of the interlayer insulating film 14, the metal on the surface of the interlayer insulating film 14 is removed by CMP or the like, and the metal is embedded in the contact hole. To do. Next, a metal layer is formed on the surface of the interlayer insulating film 14, and this is etched into a predetermined shape to form the first layer wiring 30.

Next, a second interlayer insulating film 8 is formed on the interlayer insulating film 14 and planarized. Then, a resist is applied to the planarized surface, this is patterned, and using this as a mask, the interlayer insulating film 8 is etched to form a contact hole. Next, a metal such as aluminum or copper is deposited on the contact hole and the surface of the interlayer insulating film 8, the metal on the surface of the interlayer insulating film 8 is removed by CMP or the like, and the metal is embedded in the contact hole. To do. Next, a metal layer is formed on the surface, and this is etched into a predetermined shape to form a second layer wiring, and electrodes 91 to 98 of the movable part are formed in the region B of the movable part.
Next, in the region A of the movable part, the interlayer insulating films 8 and 14 in the inner part of the electrodes 91 to 98 are etched by anisotropic etching to form the recess 6 whose bottom reaches the beam 28 (see FIG. 4). The movable part (pillar) 10 in the recess 6 is separated from the interlayer insulating films 8 and 14 and is fixed to the beam 28. Next, the cavity 7 is formed in the region C (see FIG. 4) under the movable part 10 and the beam 28 of the semiconductor substrate. That is, a cavity is formed from the back surface of the semiconductor substrate using silicon etching and wet etching.

  In this embodiment, the movable portion (pillar) of the MEMS portion is shortened to the same length as the connection wiring by the above, so that it can be made into one chip with the semiconductor integrated circuit, and the logic of the semiconductor integrated circuit and the analog circuit Since the metal wiring between them and the metal wiring between the semiconductor integrated circuit and the MEMS portion are not required, the semiconductor chip can be miniaturized, and further the operation detection and the operation direction detection can be performed.

The schematic plan view of the semiconductor chip demonstrated in an Example. FIG. 2 is a partial cross-sectional view in which a CMOS portion in which a transistor and a resistance portion in which a resistor is formed are formed in a semiconductor integrated circuit portion of the semiconductor chip in FIG. 1. FIG. 2 is a partial cross-sectional view illustrating a capacitor portion in which a capacitor of a semiconductor integrated circuit portion of the semiconductor chip of FIG. 1 is formed. 2 is a partial cross-sectional view in which a MEMS structure of the semiconductor chip of FIG. 1 is formed. FIG. 5 is a plan layout view of an electrode structure for explaining the function of the MEMS structure shown in FIG. Sectional drawing which forms the MEMS structure of the semiconductor device which concerns on an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor chip 2 ... Movable part (MEMS part)
DESCRIPTION OF SYMBOLS 3 ... Semiconductor integrated circuit part 4 ... Logic circuit 5 ... Analog circuit 6 ... Recess 7 ... Cavity 8, 14 ... Interlayer insulation film 10, 10 '... Movable part (pillar) )
11 ... Semiconductor single crystal substrate 12 ... Insulating oxide film (Box)
DESCRIPTION OF SYMBOLS 13 ... Semiconductor layer 15 ... Gate 16, 21, 24, 29, 31 ... Connection wiring 17 ... Active layer 18 ... Element isolation area | region 19, 22, 26 ... Insulating film 20 ... Resistance 23, 27 ... Polysilicon film 25 ... Capacitor 28 ... Beam 30 ... Wiring

Claims (4)

A semiconductor substrate comprising a single crystal substrate and a semiconductor layer formed on the single crystal substrate via an insulating oxide film;
A semiconductor integrated circuit formed on the semiconductor substrate;
A movable part formed on the semiconductor substrate and having a movable part formed apart from the semiconductor integrated circuit;
A multilayer wiring layer formed on the semiconductor substrate,
The movable part is formed in a concave portion of the semiconductor layer, and is formed of a connection wiring that connects the wirings of the multilayer wiring up and down. A lower end of the movable part is connected to a predetermined wiring of the multilayer wiring, and an upper end Is a semiconductor device that protrudes without contacting other parts in the recess. The semiconductor device according to claim 1, wherein a plurality of electrodes arranged at intervals around the recess are formed on a surface of the semiconductor layer. 3. The semiconductor device according to claim 1, wherein a semiconductor integrated circuit including a resistor or a capacitor or a resistor and a capacitor is formed in the semiconductor integrated circuit portion. Forming a semiconductor integrated circuit on a semiconductor substrate composed of a single crystal substrate and a semiconductor layer formed on the single crystal substrate via an insulating oxide film;
Forming a multilayer wiring layer on the semiconductor substrate;
Forming a recess in a movable part formed separately from the semiconductor integrated circuit in the semiconductor substrate, and forming a movable part in the recess,
The movable part is formed of a connection wiring that connects the wirings of the multilayer wiring up and down, the lower end of the movable part is connected to a predetermined wiring of the multilayer wiring, and the upper end protrudes without contacting other parts in the recess. A method for manufacturing a semiconductor device.

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