JP2008147440A - Manufacturing method of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device, which reduces time and effort required for design of a mask used for patterning an etching target layer. <P>SOLUTION: A silicon oxide film 22 having resistance against an etching liquid is formed on a silicon substrate 21 as an etching target layer. After that, a plurality of through holes 23 penetrating the silicon substrate 21 and the silicon oxide film 22 are formed thereon. Then, an etching liquid for etching the silicon substrate 21 is supplied into each of the through holes 23 from the silicon oxide film 22 side. In this way, etching of the silicon substrate 21 progresses in a direction parallel to the silicon oxide film 22 from the side surface of each of the through holes 23 and the through holes 23 communicate with each other, thereby patterning the silicon substrate 21 into a desired shape. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device.

Recently, since the mounting of sensors (MEMS sensors) using MEMS (Micro Electro Mechanical Systems) technology on mobile phones has been started, the attention of MEMS sensors is increasing. As a typical MEMS sensor, an acceleration sensor for detecting the acceleration of an object is known.
FIG. 3 is a cross-sectional view schematically showing a configuration of a conventional acceleration sensor.

The acceleration sensor includes a sensor main body 101, a weight 102 held by the sensor main body 101, and an annular pedestal 103 that supports the sensor main body 101.
The sensor body 101 includes a membrane 104, an annular support portion 105 connected to the peripheral portion of one surface (lower surface) of the membrane 104, and a weight fixing portion 106 connected to the center portion of one surface of the membrane 104. Is prepared. A piezoresistive element (not shown) is formed on the other surface (upper surface) of the membrane 104. The support portion 105 and the weight fixing portion 106 are separated from each other by an annular groove 107 having an isosceles trapezoidal cross section that narrows as the membrane 104 is approached.

The weight 102 is formed in a disk shape, for example. The weight 102 is disposed below the weight fixing portion 106, and the center portion of the upper surface thereof is fixed to the weight fixing portion 106.
The pedestal 103 is formed in an annular shape having substantially the same inner diameter and outer diameter as the lower surface of the support portion 105 of the sensor main body 101. By placing the support portion 105 on the pedestal 103, the sensor main body 101 is supported by the pedestal 103. The weight 102 is provided in a non-contact state with the pedestal 103 and the support portion 105 between the sensor main body 101 and the surface on which the pedestal 103 is installed.

When acceleration acts on the acceleration sensor and the weight 102 swings, the membrane 104 is deformed, and stress acts on the piezoresistive element provided on the membrane 104. The resistivity of the piezoresistive element changes in proportion to the stress acting on it. Therefore, the acceleration acting on the acceleration sensor can be obtained based on the resistivity change amount of the piezoresistive element.
JP-A-2005-351716

The sensor body 101 is formed by wet-etching a silicon chip from the back surface side opposite to the surface (the surface on which the device is formed).
However, in wet etching, etching in a direction parallel to the back surface of the silicon chip, so-called side etching, occurs. Therefore, in order to pattern the silicon chip into a desired shape, a mask (resist pattern) formed on the back surface of the silicon chip in consideration of both the etch rate in the direction perpendicular to the back surface of the silicon chip and the side etch rate. ) Must be determined. Therefore, it takes time to design the mask.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device that can reduce the time and effort required to design a mask for patterning a layer to be etched.

  The invention according to claim 1 for achieving the above object includes a mask layer forming step of forming a mask layer having resistance to an etching solution on the etching target layer, and the etching target layer and the mask layer. A through hole forming step of forming a plurality of through holes penetrating in the laminating direction, supplying the etchant into the through hole from the mask layer side, and etching in a direction intersecting the laminating direction from the through hole And an etching step of patterning the etching target layer by proceeding.

  In this method, a mask layer having resistance to the etching solution is formed on the etching target layer. Thereafter, a plurality of through holes penetrating these layers are formed in the etching target layer and the mask layer. Then, an etching solution for etching the etching target layer is supplied into the plurality of through holes from the mask layer side. Accordingly, the etching target layer is etched using the mask layer having a plurality of through holes as a mask. This etching proceeds from the side surface of each through hole in a direction that intersects the stacking direction of the etching target layer and the mask layer. Therefore, considering only the etch rate in the direction intersecting the stacking direction, and determining the pitch of the through holes (interval between the through holes) and the position, the plurality of through holes are communicated in the etching target layer, The etching target layer can be patterned into a desired shape. Therefore, compared with the conventional method, the effort concerning the design of the mask for patterning the etching target layer can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view schematically showing a configuration of a semiconductor device manufactured by a manufacturing method according to an embodiment of the present invention.
The semiconductor device 1 is used as an acceleration sensor for detecting the acceleration of an object. The semiconductor device 1 includes a membrane 11, a support portion 12 that is provided on the lower surface of the membrane 11 and supports the peripheral portion of the membrane 11, and a weight portion 13 that is provided on the lower surface of the membrane 11 and is held at the center of the membrane 11. And.

The membrane 11 is made of, for example, SiO ₂ (silicon oxide) and has a substantially rectangular shape in plan view with a thickness of 1 to 10 μm. Although not shown, a plurality of (for example, 16) piezoresistive elements are formed on the membrane 11. A large number of openings 14 are formed in a rectangular annular region between the peripheral edge portion and the central portion of the membrane 11.
The support portion 12 and the weight portion 13 are made of Si (silicon), and are formed to be separated from each other by a square-shaped groove portion 15 having a rectangular cross-sectional shape in plan view.

The support portion 12 is formed in a square ring shape in plan view having an outer surface and an inner surface orthogonal to the membrane 11.
The weight portion 13 is formed in a quadrangular prism shape having the same height as the support portion 12.
When acceleration acts on the semiconductor device 1 and the weight portion 13 swings, the membrane 11 is deformed, and stress acts on each piezoresistive element provided on the membrane 11. The resistivity of the piezoresistive element changes in proportion to the stress acting on it. Therefore, if the amount of change in resistivity of each piezoresistive element is extracted as a signal, the direction (three-axis direction) and the magnitude of acceleration acting on the weight portion 13 (semiconductor device 1) can be obtained based on the signal. .

2A to 2C are schematic cross-sectional views for explaining a manufacturing process of the semiconductor device 1.
A silicon substrate 21 is used for manufacturing the semiconductor device 1. First, as shown in FIG. 2A, a silicon oxide film 22 as a mask layer having resistance to an etching solution capable of etching the silicon substrate 21 is formed on the surface of the silicon substrate 21 by plasma treatment (see FIG. 2A). Mask layer forming step).

Next, as shown in FIG. 2 (b), a planar annular region (region corresponding to the groove 15 shown in FIG. 1) between the peripheral portion and the central portion of the silicon substrate 21 and the silicon oxide film 22 by dry etching. ), A large number of through holes 23 penetrating them in the stacking direction are formed (through hole forming step).
Subsequently, an etching solution capable of etching the silicon substrate 21 is supplied from the silicon oxide film 22 side into each through hole 23 (etching step). As such an etchant, for example, an aqueous solution of TMAH (Tetra methyl ammonium hydroxide) having a concentration of 50% heated to 80 ° C. can be used. Since each through hole 23 penetrates the silicon substrate 21, when the etching solution is supplied to each through hole 23, the silicon substrate 21 is etched in the silicon substrate 21 as shown in FIG. It proceeds in the direction parallel to the silicon oxide film 22 from the side surface of each through hole 23. Then, as this etching proceeds, the rectangular annular region between the peripheral edge portion and the central portion of the silicon substrate 21 is removed without remaining in the thickness direction, and the rectangular annular groove portion 15 shown in FIG. Is formed. As a result, the silicon oxide film 22 becomes the membrane 11, and the silicon substrate 21 is supported by the groove portion 15 on the support portion 12 that supports the peripheral portion of the membrane 11 and the weight portion 13 held at the center portion of the membrane 11. Divided. Thereby, the semiconductor device 1 shown in FIG. 1 is obtained.

  As described above, in this manufacturing method, the silicon oxide film 22 having resistance to the etching solution is formed on the silicon substrate 21 that is the etching target layer. Thereafter, a plurality of through holes 23 penetrating these are formed in the silicon substrate 21 and the silicon oxide film 22. Then, an etching solution for etching the silicon substrate 21 is supplied into each through hole 23 from the silicon oxide film 22 side. Thus, the silicon substrate 21 is etched using the silicon oxide film 22 having the plurality of through holes 23 as a mask. This etching proceeds from the side surface of each through hole 23 in a direction parallel to the silicon oxide film 22 (direction intersecting with the stacking direction of the silicon substrate 21 and the silicon oxide film 22). Therefore, if only the etch rate in the direction parallel to the silicon oxide film 22 is considered and the pitch (interval between the through holes 23) and the positions of the through holes 23 are determined, the plurality of through holes 23 in the silicon substrate 21 are determined. The silicon substrate 21 can be patterned into a desired shape (the shape of the groove 15. In this embodiment, a square ring in a plan view). Therefore, compared with the conventional method, the effort concerning the design of the mask for patterning the silicon substrate 21 can be reduced.

As mentioned above, although one Embodiment of this invention was described, this invention can also be implemented with another form. For example, although the silicon oxide film 22 is formed on the surface of the silicon substrate 21, a silicon nitride film may be formed by plasma processing instead of the silicon oxide film 22. In this case, the material of the membrane 11 is SiN (silicon nitride).
Moreover, the shape of the groove 15 is not limited to a quadrangular ring shape in plan view, and may be an annular shape in plan view, for example.

Furthermore, the manufacturing method according to the above-described embodiment is not limited to the acceleration sensor, but includes various semiconductor device manufacturing methods such as a manufacturing method of a piezoresistive semiconductor pressure sensor for detecting gas pressure or the like. Can be applied.
In addition, various design changes can be made within the scope of matters described in the claims.

It is sectional drawing which shows typically the structure of the semiconductor device manufactured by the manufacturing method which concerns on one Embodiment of this invention. FIG. 7 is a schematic cross-sectional view for illustrating a manufacturing step of the semiconductor device shown in FIG. 1. It is sectional drawing which shows the structure of the conventional acceleration sensor typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Semiconductor device 21 Silicon substrate 22 Silicon oxide film 23 Through-hole

Claims (1)

A mask layer forming step of forming a mask layer having resistance to an etching solution on the etching target layer;
A through hole forming step of forming a plurality of through holes penetrating the etching target layer and the mask layer in the stacking direction;
An etching step of patterning the etching target layer by supplying the etching solution into the through-hole from the mask layer side and causing the etching to proceed in a direction intersecting the stacking direction from the through-hole. Device manufacturing method.

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