JP2006095607A - Manufacturing method of mems element and mems element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an MEMS element and an MEMS element, reducing the size and cost. <P>SOLUTION: This manufacturing method of the MEMS element 10 includes: a step of injecting the impurity into the surface of a semiconductor substrate 30 to form a well 32 insulated and separated from the periphery; a step of selectively forming a sacrifice layer (an insulating layer) 40 including a part of the surface of the well 32; a step of forming a beam 50 in which an anchor part 52 in an opening part opened in the sacrifice layer 40 is connected to the surface of the semiconductor substrate 30 and a movable part 51 is connected to the surface of the sacrifice layer 40; and a step of removing the sacrifice layer 40 formed in the peripheral edge including the lower part of the movable part 51 of the beam 50. In the MEMS element manufactured by the above manufacturing method, the semiconductor substrate 30 (a semiconductor device including an integrated semiconductor circuit element) is integrated with the beam 50. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a MEMS element and a MEMS element.

With the progress of microfabrication technology, so-called micro-machines (MEMS) devices are attracting attention.
Conventionally, a step of forming a substrate-side electrode that is insulatively isolated from other portions by injecting impurities into the surface of a semiconductor substrate, and a support portion made of an insulating layer for supporting a beam and the substrate-side electrode are selectively included. Forming a sacrificial layer, forming a beam having a drive-side electrode on the sacrificial layer, removing the sacrificial layer, and manufacturing the MEMS element manufactured by the manufacturing method It has been known.

JP 2003-200394 A (pages 8 and 9, FIG. 6, FIG. 7)

  In Patent Document 1, the beam is formed over the support portion and the sacrificial layer, and then a resist mask is formed, and the beam is formed into a predetermined planar shape by etching. It is formed. In this manner, a gap is formed between the movable part and the surface of the semiconductor substrate by the support part, so that the MEMS element is obtained. Therefore, it is necessary to form a support part for supporting the beam, and an etching process for forming the beam into a predetermined shape is also required, resulting in a long manufacturing process, which makes it difficult to reduce the manufacturing cost. Was the way.

  Further, according to the manufacturing method or structure as described above, since it is a configuration of the MEMS element alone, it is necessary to separately provide a drive control circuit or a detection circuit for driving control of the MEMS element, and as a whole system There is a problem that there is a limit to downsizing and cost reduction.

  An object of the present invention is to provide a method for manufacturing a MEMS device and a MEMS device that can be reduced in size and cost.

The method for manufacturing a MEMS device according to the present invention includes a step of injecting impurities into the surface of a semiconductor substrate to form a well that is insulated and isolated from the surroundings, and a sacrificial layer is selectively formed including a part of the surface of the well. A step in which an anchor portion is connected to the semiconductor surface in an opening formed in the sacrificial layer, and a movable portion forms a continuous beam on the surface of the sacrificial layer; and a lower portion of the movable portion of the beam And a step of removing the sacrificial layer formed on the peripheral edge.
Here, a well is a region having a different conductivity type in a semiconductor substrate (silicon substrate), and is a region where a MOS transistor of a type opposite to the surrounding is formed. In an embodiment described later, a p-type well is used. (P-well) will be described as an example.

  According to this invention, since the anchor portion for supporting the beam is connected to the surface of the semiconductor substrate, it is not necessary to separately form a support portion for supporting the beam. Since the anchor portion is laminated on the surface of the semiconductor substrate, the manufacturing process can be shortened and simplified, so that the manufacturing cost can be reduced.

  The movable part of the beam can be easily formed even if it has a complicated shape because a gap necessary for driving can be obtained by removing the sacrificial layer.

  In the method for manufacturing a MEMS element of the present invention, a step of forming a semiconductor integrated circuit element on the semiconductor substrate, and a step of integrally forming the sacrificial layer and an insulating layer for isolating the semiconductor integrated circuit element, Preferably, the method includes a step of removing the sacrificial layer formed on the periphery including the lower portion of the movable portion of the beam while leaving the insulating layer for isolating the semiconductor circuit element.

Here, as the semiconductor integrated circuit element, for example, a drive control circuit for driving and controlling the MEMS element is shown.
The insulating layer for separating the semiconductor integrated circuit element is, for example, silicon oxide (SiO ₂₎ for separating the source region and the drain region when the semiconductor integrated circuit element is a MOSFET (Metal Oxide Field Effect Transistor). ) And the like.

  According to the present invention, the sacrificial layer is formed integrally with the insulating layer for isolating the semiconductor integrated circuit element, that is, as a common layer. Therefore, it is not necessary to separately configure the sacrificial layer and the insulating layer, and the manufacturing is further performed. The process can be shortened and simplified.

  Further, since the insulating layer for isolating the semiconductor integrated circuit element is left in the step of removing the sacrificial layer below the movable portion of the beam, the insulating layer of the semiconductor integrated circuit element needs to be formed in a separate process. The manufacturing process can be shortened and simplified.

  Furthermore, in the manufacturing method of the present invention, since the beam is manufactured in a process that is continuous with the manufacturing process of the semiconductor integrated circuit element, it can be manufactured with equipment of the semiconductor manufacturing process, and there is no need to newly prepare equipment. Cost reduction and factory space can be reduced.

  According to another aspect of the present invention, there is provided a MEMS device comprising: a semiconductor substrate having a semiconductor integrated circuit device; and a beam having a movable portion connected to an anchor portion on the surface of the semiconductor substrate and continuously formed on the anchor portion. It is manufactured by the method according to claim 1 or claim 2.

  According to the present invention, since the semiconductor substrate having the semiconductor integrated circuit element and the beam are integrally formed, the conventional configuration in which the MEMS device (beam) and the semiconductor device for driving the MEMS element are separately provided. Compared with the MEMS element of this type, there is an effect that downsizing and low cost are possible.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration of a MEMS element according to an embodiment of the present invention, and FIGS. 2.1 and 2.2 are cross-sectional views showing a method for manufacturing the MEMS element.
(Embodiment)

  FIG. 1 is a partial cross-sectional view showing a typical configuration of a MEMS element according to the present invention. In the present embodiment, a MOSFET will be described as an example of a semiconductor integrated circuit element. In FIG. 1, in the MEMS element 10 of this embodiment, a MOSFET 36 and a beam 50 are integrally formed on a semiconductor substrate 30.

The MOSFET 36 is a p-well in which a predetermined impurity is implanted into a predetermined region of the silicon layer (Si layer) 31 and a conductive semiconductor region 32 (this region is referred to as a well, and in this embodiment, a p-type impurity is ion-implanted. In the following, it will be referred to as well), and the source region 33, drain region 34, gate electrode 35, and source layer 33 and drain region 34 formed on the upper surface side thereof are isolated from the periphery. SiO ₂ ) 40.

The insulating layer 40 includes a selective oxidation layer (so-called LOCOS: Local oxidation of) as an element isolation layer formed on the surface of the silicon layer 31 of the semiconductor substrate 30 including part of the well 32 and inside and outside the silicon layer 31 in the thickness direction. silcon).
The insulating layer 40 is a sacrificial layer when a beam 50 described later is formed.

  The source region 33, drain region 34, and gate electrode 35 are connected to other semiconductor integrated circuit elements (not shown) (for example, other MOSFETs, capacitors, resistors, etc.) by via holes or wiring patterns, and a plurality of insulating layers are further provided. They are stacked. These semiconductor circuit element groups are drive control circuits that drive and control the MEMS elements. A beam 50 is formed integrally with the semiconductor substrate 30 including such a drive control circuit.

The beam 50 is formed by laminating the anchor portion 52 on the surface of the beam support portion 37 formed on the silicon layer 31 and is continuous with the beam-shaped movable portion 51. The movable portion 51 has a gap with respect to the silicon layer 31 and is configured such that driving such as vibration is not hindered.
In this way, the MEMS element 10 is configured.

Then, the manufacturing method of this MEMS element is demonstrated with reference to drawings.
FIG. 2.1 and FIG. 2.2 are cross-sectional views schematically showing the manufacturing method of the MEMS element according to this embodiment along the manufacturing process. In addition, this manufacturing process has described only the part which concerns on this invention, and has abbreviate | omitted about the well-known semiconductor manufacturing process of the description.

  First, in this embodiment, as the semiconductor substrate 30, as shown in FIG. 2.1A, a well 32 as an insulating region of the n-type silicon layer 31 is formed at a predetermined position. The well 32 is formed by ion implantation of p-type impurities and annealing. The ion implantation concentration is set so as to obtain various characteristics such as a predetermined transistor threshold voltage.

Subsequently, the insulating layer 40 is formed by a CMOS process using LOCOS element isolation (insulation isolation). The insulating layer 40 is formed of silicon oxide (SiO ₂ ), and a source region and a drain region, which will be described later, and a beam support portion 37 to which the beam is connected are opened. A beam 50 is laminated on the beam support portion 37.

  Next, the beam 50 is formed. In FIG. 2.1 (b), in this embodiment, the beam 50 is formed of a laminated film of polysilicon whose physical characteristics such as structural strength and elastic constant are suitable for the mechanical drive characteristics of the beam 50. In the beam 50, the anchor portion 52 is formed in close contact with the surface of the beam support portion 37 of the silicon layer 31, and the other portion (movable portion 51) is formed on the surface of the insulating layer 40. The beam 50 is formed with a concave portion 53 so as to be laminated with a constant thickness, but does not affect the mechanical drive of the movable portion 51 because it is within the plane position range of the anchor portion 52. After the beam 50 is formed on the semiconductor substrate 30, the MOSFET 36 is formed.

Since the formation process of the MOSFET 36 is performed by a known semiconductor process, it will be briefly described. In FIG. 2.1 (c), first, a gate oxide film 60 is formed. Although not shown, after the LOCOS process is completed, after removal of silicon nitride (Si ₃ N ₄ ) and silicon oxide (SiO ₂ ) in the active region, a gate oxide film 60 is formed. A gate electrode 35 is formed at a predetermined position of the gate oxide film.

  The gate electrode 35 is formed of polysilicon (polycrystalline silicon) by a CVD method (Chemical Vapor Deposition). At this time, a predetermined resistance value can be controlled by doping impurities. After forming the gate electrode, a source region 33 and a drain region 34 are formed.

  As shown in FIG. 2.2D, the source region 33 and the drain region 34 are formed on the surface of the well 32 where the insulating layer 40 is opened by ion implantation and annealing treatment with the gate electrode 35 interposed therebetween. Since these forming processes are also well-known as semiconductor manufacturing processes, detailed description thereof is omitted.

Subsequently, a mask resist 70 is formed on the upper surface of the MOSFET 36 as shown in FIG. The mask resist 70 secures an area that ensures a sufficient element isolation capability of the insulating layer 40 of the MOSFET 36. Therefore, the distance from the beam 50 to the anchor portion of the movable portion 51 and the distance from the end portion of the mask resist 70 to the end portion of the insulating layer 40 for element isolation are set to substantially the same distance (FIG. 2). 2 (f), see).
Then, the insulating layer 40 in a predetermined range is removed by etching with hydrofluoric acid or the like.

  The state where the sacrificial layer 40 is removed is shown in FIG. 2.2 (f). By removing the sacrificial layer in this way, the beam 50 is released from the sacrificial layer, the anchor portion 52 is in close contact with the beam support portion 37 of the silicon layer 31, and the movable portion 51 is driven. The Further, in the MOSFET 36, the area of the insulating layer 40 necessary for element isolation is secured.

  When the distance between the beam 50 and the MOSFET 36 is close, the insulating layer 40 in the gap (see FIG. 2.2 (e)) formed between the beam 50 and the mask resist 70 is removed. After that, after forming a mask resist again on the mask resist end face on the MOSFET side, the insulating layer under the beam 50 can be removed.

  Here, the insulating layer 40 is a layer necessary for beam formation, and is a sacrificial layer for the beam 50 because it is removed thereafter.

  Therefore, according to the above-described embodiment, the beam 50 is supported to support the beam 50 because the anchor portion 52 that supports the beam 50 is stacked on the beam support portion 37 on the surface of the semiconductor substrate 30. There is no need to form a separate portion, and the anchor portion 52 is formed when the beam 50 is formed. Therefore, the manufacturing process can be shortened and simplified, and the manufacturing cost can be reduced.

  Further, the movable portion 51 of the beam 50 is laminated on the sacrificial layer, and a gap necessary for driving can be obtained by removing the sacrificial layer 40, so even if it has a complicated shape, it can be easily obtained. Can be formed.

  Further, since the sacrificial layer is formed in common with the insulating layer 40 as an insulating separation which is one of the components forming the MOSFET 36, it is not necessary to separately configure the sacrificial layer and the insulating layer, and the manufacturing process is further improved. Can be shortened and simplified.

  Further, in the step of removing the sacrificial layer below the movable portion 51 of the beam 50, the insulating layer for isolating the semiconductor integrated circuit element remains, so that it is not necessary to form the insulating layer of the MOSFET 36 in a separate step. The manufacturing process can be shortened and simplified.

  Furthermore, in the manufacturing method of the present invention, since the beam 50 is manufactured in a process that is continuous with the manufacturing process of the semiconductor integrated circuit element such as the MOSFET 36, the beam 50 can be manufactured with the equipment of the semiconductor manufacturing process. There is no need to prepare, cost reduction and factory space can be reduced.

  Furthermore, since the semiconductor substrate 30 having the semiconductor integrated circuit element and the beam 50 are integrally configured, the conventional configuration in which the MEMS device (beam) and the semiconductor device are separately provided for MEMS element drive control. Compared to the above, there is an effect that downsizing and low cost are possible.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in the above-described embodiment, the shape of the beam 50 (see FIG. 1) and the shape of the movable portion 51 are represented by a simple beam shape, but the movable portion 51 includes a comb-shaped vibrator, a resonator, Alternatively, it is possible to form a resonator or the like in which a pair of comb-shaped vibrating pieces is formed by a similar manufacturing method and the comb-tooth portions are opposed to each other.

  In this way, various forms of beams can be easily formed on the semiconductor substrate (semiconductor device).

  Therefore, according to the above-described embodiment, it is possible to provide a method for manufacturing a MEMS element and a MEMS element that can be reduced in size and cost.

  The MEMS element manufacturing method and MEMS element according to the present invention can be employed in electrostatic drive type MEMS elements (vibrators, resonators, etc.), optical MEMS elements, light modulation elements, and the like.

Sectional drawing which shows the structure of the MEMS element of embodiment which concerns on this invention. Sectional drawing which shows the manufacturing method of the MEMS element of embodiment which concerns on this invention. Sectional drawing which shows the manufacturing method of the MEMS element of embodiment which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... MEMS element, 30 ... Semiconductor substrate, 31 ... Silicon layer, 32 ... Well, 33 ... Drain region, 34 ... Source region, 35 ... Gate electrode, 36 ... MOSFET, 37 ... Beam support part, 40 ... Insulating layer (sacrificial) Layer), 50 ... beam, 51 ... movable part, 52 ... anchor part, 60 ... gate oxide film, 70 ... resist film.

Claims (3)

A step of injecting impurities into the surface of the semiconductor substrate to form a well that is insulated from the surroundings;
Selectively forming a sacrificial layer including part of the surface of the well;
An anchor portion connected to the semiconductor surface in an opening formed in the sacrificial layer, and a movable portion forming a continuous beam on the surface of the sacrificial layer;
Removing the sacrificial layer formed on the periphery including the lower portion of the movable part of the beam;
A method for manufacturing a MEMS device, comprising: In the manufacturing method of the MEMS element according to claim 1,
Forming a semiconductor integrated circuit element on the semiconductor substrate;
A step of integrally forming the sacrificial layer and an insulating layer for isolating the semiconductor integrated circuit element;
Removing the sacrificial layer formed on the periphery including the lower portion of the movable portion of the beam, leaving an insulating layer for element isolation of the semiconductor circuit element;
A method for manufacturing a MEMS device, comprising: A semiconductor substrate having a semiconductor integrated circuit element;
A beam having a movable part connected to an anchor part on the surface of the semiconductor substrate and continuously formed on the anchor part;
And a MEMS device manufactured by the method according to claim 1.

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