JP2003298070A - Method of manufacturing semiconductor device and semiconductor device manufactured thereby - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method by which a semiconductor device having a structure that has a possibility of becoming mechanically fragile such as a thin wall section can be formed without breaking the device. <P>SOLUTION: The semiconductor device manufactured by this method has thin wall sections 21 and thick wall sections 11 and 11 provided around the thin wall sections 21, both of which are formed by engraving a semiconductor substrate 1. The semiconductor substrate 1 is divided into individual elements by etching the prescribed positions of the thick wall sections 11 and 11 from both surfaces of the substrate 1. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of manufacturing a semiconductor device such as a semiconductor pressure sensor having a thin portion.

[0002]

2. Description of the Related Art As a conventional method for manufacturing a semiconductor device, FIG. 4 shows an example of a method for manufacturing a semiconductor pressure sensor. This is a semiconductor substrate 101 made of silicon (Si),
A plurality of sensor chips 100, 100, ... Forming a diaphragm 104 having a substantially square frame portion (thick portion) 102 and a substantially square thin portion 103 inside are formed. Further, the thin portion 103 is adapted to move in the thickness direction of the semiconductor substrate 101 due to the acting pressure.

When manufacturing this semiconductor pressure sensor, first, an adhesive sheet 106 for dicing is attached to the semiconductor substrate 101 before dicing. At this time, the semiconductor substrate 101 is attached so that the surface of the semiconductor substrate 101 on which the diaphragm 104 is formed overlaps the attachment surface of the adhesive sheet 106.

Next, the semiconductor substrate 101 is set in a dicing device (not shown), and the dicing blade 107 is set.
The sensor chips 100, 100, ... Can be individually divided by dicing so as to cut the frame portion 102.

FIG. 5 shows a method of manufacturing a semiconductor device disclosed in Japanese Patent Laid-Open No. 9-320996.

This is also a substantially square annular frame portion (thick portion) 202 and a substantially square thin portion 203 inside thereof.
A semiconductor substrate 201 made of silicon and provided with a plurality of sensor chips 200 each having a diaphragm 204 having
In FIG. 3, anisotropic etching is performed along a predetermined position of the frame portion 202 on the side where the diaphragm 204 is formed, and a groove 205 in which a predetermined part of the side wall is inclined with respect to the thickness direction of the semiconductor substrate 201 in a sectional view is formed. Is forming.

Then, one surface of the semiconductor substrate 201 in which the groove 205 is formed and the dicing sheet 206 are attached, and the semiconductor substrate 20 is cut so that the side surfaces of the dicing blade 207 cut the oblique surfaces 205a and 205a of the groove 205.
1 is diced to divide the sensor chip 200 individually.

[0008]

The above-mentioned conventional technique is a dividing method because the element can be divided relatively easily when the thin portion 103 has a relatively large thickness, for example, a thickness of about 10 μm or more. Although very effective, the mechanical strength of the thin portion 103 becomes extremely small as the thickness of the thin portion 103 becomes thin due to high sensitivity, downsizing, and the like. Therefore, cleaning cooling water during dicing and dicing blade 107 There is a possibility that the thin portion 103 may be damaged due to vibration or the like.

In the conventional method disclosed in Japanese Patent Laid-Open No. 9-320996, cracks and chips at the dicing end can be reduced, but the thin portion 203 is damaged by cleaning cooling water during dicing or vibration of the dicing blade 207. There is still the risk of problems.

The present invention has been made in view of the above points, and it is an object of the present invention to form a semiconductor device having a structure such as a thin portion which is likely to be fragile so as not to be easily damaged. A semiconductor device manufacturing method and a semiconductor device are provided.

[0011]

In order to achieve the above object, a semiconductor device of the present invention has a thin portion and a thick portion provided around the thin portion by performing a digging process on a semiconductor substrate. In the method of manufacturing a semiconductor device having the above, a predetermined position of the thick portion is etched from both sides of the semiconductor substrate to divide into individual elements.

According to a second aspect of the semiconductor device of the present invention, in the manufacturing method according to the first aspect, the semiconductor substrate is an SOI substrate having a buried oxide film layer immediately below a thin portion, and the buried oxide film layer. It is supposed to be etched.

A semiconductor device according to a third aspect of the present invention is a semiconductor device having a thin portion and a thick portion provided around the thin portion by subjecting a semiconductor substrate to a digging process. It is characterized in that a predetermined portion of the meat portion is formed by etching from both sides of the semiconductor substrate and dividing into individual elements.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on illustrated examples. Further, the semiconductor device is embodied as a semiconductor pressure sensor.

[First Embodiment] FIG. 1 is a perspective view showing a semiconductor pressure sensor according to this embodiment, and FIG. 2 is a process drawing showing a method for manufacturing a semiconductor pressure sensor according to this embodiment. .

The semiconductor pressure sensor converts the pressure applied to this into an electric signal and outputs it, and is formed of, for example, an n-type semiconductor substrate 1 made of single crystal silicon. The configuration includes frame portions (thick portions) 11 having a substantially rectangular ring shape in plan view, and a diaphragm 2 having a thin portion 21 inside thereof.

The outer side walls of the frame portions 11, 11 are formed by slanted surfaces 15, 15 so that the substantially central portion of the n-type semiconductor substrate 1 projects in a sectional view.

Further, the upper surface of the thin portion 21 (upper side in FIG. 1) and the boundary position between the frame portions 11 and 11 and the thin portion 21 are resisted by the strain of the thin portion 21 caused by the pressure acting on the semiconductor pressure sensor. Piezoresistive elements 12, 12, whose values change
... is near the center of the thin portion 21, the thin portion 21, the frame portion 11,
Two pieces each are formed on the boundary with 11, and are interconnected by diffusion wirings 13, 13, so that a total of four piezoresistive elements 12, 12, ... Form a bridge circuit. Then, the detected pressure signal is applied to the electrodes 14 and 1.
4 is output.

Next, a manufacturing process of the semiconductor pressure sensor thus constructed will be described. First, a boron ion (B) is formed in a predetermined area at a boundary position between the thin portion 21 and the frame portions 11 and 11 on the surface of the n-type semiconductor substrate 1 (upper side in FIG. 1).
+) Is diffused to form piezoresistive elements 12, 12, ... And diffusion wirings 13, 13 ,.

Next, aluminum (Al) is sputtered and a predetermined portion is removed by etching to remove the electrodes 14,
After forming 14, a protective film (not shown) is formed by the CVD method.

Then, on the back surface of the n-type semiconductor substrate 1 (lower side in FIG. 1), a nitride film (Si3N) as an etching mask is formed.
4) 3 is formed, and the nitride film 3 is removed by etching at the position where the diaphragm 2 is to be formed and the dividing positions in the frame portions 11, 11 on the front and back surfaces of the semiconductor substrate 1 (FIG. 2A).

Then, for example, TMA heated to 90 ° C.
Using a 11% aqueous solution of H (tetramethylammonium hydroxide), the position where the diaphragm 2 of the n-type semiconductor substrate 1 is formed and the position where the frame parts 11 and 11 are divided are formed until a thin part 21 having a predetermined thickness is formed. Thin part 2 by anisotropic etching
1 is formed and elements are divided. The etching rate at this time is about 0.8 μm / min (FIG. 2B).

At this time, since the etching depth of the dividing positions of the frame portions 11, 11 is shallower than the etching depth of the diaphragm 2, the frame portions 11, 11 are formed before the thin portion 21 is formed.
Etching is completed, and the device is divided into individual pieces.

According to the semiconductor pressure sensor of the embodiment described above, since the predetermined positions of the frame portions 11, 11 are etched from both sides of the n-type semiconductor substrate 1 to divide the element into individual elements, a physical means, For example, compared with the case of using a dicing blade or the like for division, vibrations or the like given to the semiconductor pressure sensor can be significantly reduced, damage to a structure such as the thin portion 21 that may become fragile can be reduced, and yield can be improved. Can be improved.

[Second Embodiment] FIG. 3 is a process diagram showing a method for manufacturing a semiconductor pressure sensor according to the present embodiment.
In this semiconductor pressure sensor, the semiconductor substrate forming the semiconductor pressure sensor is different from that of the first embodiment, and the steps before the formation of the other components and the diaphragm 2 are substantially the same as those of the first embodiment. Is omitted. Further, the same members are given the same numbers as in the first embodiment.

The semiconductor substrate is an SOI substrate 4 made of silicon having a buried oxide film layer 41 immediately below the thin portion 21.
Is.

In the manufacturing method, first, the nitride film 3 as an etching mask is formed on the front and back surfaces (upper and lower sides in FIG. 1) of the SOI substrate 4, and the position where the diaphragm 2 is formed and the SOI.
The nitride film 3 at the divided positions in the frame portions 11, 11 on the front and back surfaces of the substrate 4 is removed by etching (FIG. 3A).

Then, for example, TMA heated to 90 ° C.
An 11% aqueous solution of H (tetramethylammonium hydroxide) is used to anisotropically etch the position where the diaphragm 2 of the SOI substrate 4 is formed and the dividing positions of the frame portions 11 and 11 up to the buried oxide film layer 41. The etching rate at this time is about 0.8 μm / min. Moreover, the anisotropic etching is automatically stopped by the buried oxide film layer 41 (FIG. 3B).

Next, inside the diaphragm 2 and the frame portion 11,
The buried oxide film layer 41 exposed at the divided positions of 11 is C
The semiconductor pressure sensor is individually divided and completed by removing it by plasma etching using HF3 gas (FIG. 3C).

According to the semiconductor pressure sensor of the above-described embodiment, the SOI substrate 4 is used as the semiconductor substrate, and the predetermined positions of the frame portions 11, 11 are formed on both sides of the SOI substrate 4 immediately below the thin portion 21. Buried oxide film layer 4
Since the elements are individually divided by performing anisotropic etching up to 1, vibrations or the like given to the semiconductor pressure sensor can be significantly reduced as compared with the case where the elements are separated by a physical means such as a dicing blade. It is possible to reduce the damage of the structure such as the thin portion 21 that may become fragile and improve the yield. Further, the buried oxide film layer 41
As a result, the etching is automatically stopped, so that a semiconductor pressure sensor with high processing accuracy can be formed.

Although the semiconductor device has been described as the semiconductor pressure sensor in the two embodiments, the semiconductor device is not limited to the semiconductor pressure sensor, but may have a thin portion, such as a semiconductor acceleration sensor or a semiconductor acceleration sensor. It is also applied to a semiconductor actuator.

[0032]

In the method for manufacturing a semiconductor device according to the first aspect of the present invention, the predetermined position of the thick portion is etched from both sides of the semiconductor substrate to separate the elements, so that the vibration or the like applied to the semiconductor device is significantly reduced. It is possible to reduce damage to the fragile structure.

In addition to the effect of the first aspect, the method for manufacturing a semiconductor device according to the second aspect of the present invention uses the SOI substrate having the buried oxide film layer immediately below the thin portion, and therefore, in the case of element isolation. The etching can be automatically stopped at the buried oxide film layer, and a semiconductor device with high processing accuracy can be formed.

In the semiconductor device according to the third aspect of the present invention, since the predetermined position of the thick portion is formed by dividing it into individual elements by etching from both sides of the semiconductor substrate, there is a risk of becoming fragile. A semiconductor device with reduced body damage and improved yield can be provided.

[Brief description of drawings]

FIG. 1 is a sectional perspective view showing a semiconductor pressure sensor according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor according to the first embodiment of the invention.

FIG. 3 is a cross-sectional view showing the manufacturing process of the semiconductor pressure sensor according to the second embodiment of the invention.

FIG. 4 is a cross-sectional view showing a method for manufacturing a conventional semiconductor pressure sensor.

FIG. 5 is a cross-sectional view showing another conventional semiconductor pressure sensor.

[Explanation of symbols]

1 Semiconductor substrate 11 Frame part (thick part) 21 Thin part 4 SOI substrate 41 buried oxide film layer

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Atsushi Ogihara             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Takashi Okudo             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Shigenari Takami             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company (72) Inventor Mitsuhiro Kani             1048, Kadoma, Kadoma-shi, Osaka Matsushita Electric Works Co., Ltd.             Inside the company F term (reference) 2F055 AA40 BB20 CC02 DD05 EE13                       FF43 FF49 GG01                 4M112 AA01 BA01 CA01 CA03 CA07                       DA03 DA04 DA06 DA09 DA12                       EA03 EA07 EA10 EA11 FA20

Claims (3)

[Claims] 1. A method of manufacturing a semiconductor device having a thin portion and a thick portion provided around the thin portion by performing a digging process on a semiconductor substrate, wherein a predetermined position of the thick portion is a semiconductor. A method for manufacturing a semiconductor device, characterized in that the substrate is etched from both sides and divided into individual elements. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor substrate is an SOI substrate having a buried oxide film layer immediately below a thin portion, and the buried oxide film layer is also etched. 3. A semiconductor device having a thin portion and a thick portion provided around the thin portion by performing a digging process on the semiconductor substrate, wherein a predetermined position of the thick portion is a semiconductor substrate. A semiconductor device formed by etching from both sides and dividing into individual elements.