JPH0824196B2 - Method for manufacturing semiconductor pressure sensor - Google Patents

Description

The present invention relates to a method of manufacturing a semiconductor pressure sensor in which a strain gauge is formed on a pressure-sensitive diaphragm of a single crystal silicon semiconductor by diffusion.

[Prior Art] As is well known, a strain gauge using a silicon semiconductor has a very high gauge factor due to the piezo effect of silicon, and single crystal silicon is also an ideal highly elastic body. By utilizing this, a pressure sensitive diaphragm is formed in a silicon semiconductor chip, and a strain gauge is formed on the surface of the pressure sensitive diaphragm by diffusion, whereby a small and highly sensitive semiconductor pressure sensor can be manufactured. This semiconductor pressure sensor is usually a few mm square, and many can be manufactured from one silicon wafer using essentially the same process as a normal semiconductor device. A strain gauge is made, and a recess is dug from the back by etching to form a strain gauge portion on a pressure-sensitive diaphragm and then cut into chips.

Although such a semiconductor pressure sensor is suitable for mass production, it is of course necessary to make its sensitivity as uniform as possible in practical use. The point for this is how well the depth of the recess is controlled and the size of the pressure-sensitive diaphragm, especially the thickness. It can be managed with less variation. Various measures have been taken for this purpose, and FIG. 4 shows the outline of the method currently put into practical use for digging this recess.

FIG. 4 is a cross-sectional view showing one semiconductor pressure sensor in the wafer. FIG. 4 (a) shows a state in the middle of excavation of a recess, and FIG. 4 (b) shows a completed state. It is shown. The base 10 made of a silicon semiconductor for a pressure sensor,
In this example, a three-layer structure of an n-type semiconductor region 11, a p-type semiconductor region 12, and an n-type semiconductor region 13 is formed. Usually, the semiconductor region 11 is a substrate having a thickness of several hundreds of μm. Regions 12 and 13 are epitaxial layers having a total thickness of several tens of μm, which are successively grown thereon.

Before digging the recess from the back side of the substrate 10, the semiconductor resistance layer as the strain gauge 20 is diffused as p-type from the surface of the n-type semiconductor region 13 in this example on the front side. A plurality of, for example, four strain gauges 20 are usually diffused, and bridges are formed, for example, by connecting films 72 made of aluminum or the like which are in conductive contact with both ends of the strain gauge 20 through the windows opened in the oxide film 71 covering the surface of the substrate 10. Connected. As usual, the connection film 72 is covered with a protective film 73 made of silicon nitride or the like, and the connection film 72 in the open window is used as a connection pad 80 for external connection.

FIG. 4 (a) shows a state in which the first etching for engraving the recess has been performed. First, an oxide film 90 is deposited on the surface of the semiconductor region 10 on the back side of the substrate 10, a window is opened in a portion corresponding to the range where the strain gauge 20 is formed, and chemical etching is performed using the oxide film 90 as a mask. By the method, the prepared hole 31a is dug deep into the semiconductor region 11 up to near the interface with the semiconductor region 12 as shown in the figure. As the etching liquid at this time, for example, a mixed liquid of hydrofluoric acid and nitric acid having a relatively high etching rate is used.

FIG. 4 (b) shows a completed state after the second or final etching. For this finishing, for example, about 5% hydrofluoric acid is used as an electrolytic solution to electrolytically etch the n-type semiconductor region 11 under a low voltage to automatically stop the etching at the interface with the p-type semiconductor region 12. . As a result, the pilot hole 31a in FIG. 11A has a recess whose depth is regulated at the interface between the semiconductor regions 11 and 12 as shown in FIG.
Finished to 31. After the digging of the recess 31 is completed, the oxide film 90 for the etching mask is removed, and then the wafer is separated into chips by scribing to obtain the state shown in the drawing.

In the semiconductor pressure sensor manufactured in this manner, the semiconductor regions 12 and 13 within the region where the strain gauge 20 on the upper side of the recess 31 in the drawing is formed become the pressure sensitive diaphragm 60. Therefore, the thickness dimension of this pressure-sensitive diaphragm 60 is
The thickness of 12 and 13 can be made constant by preliminarily controlling and placing them, and the area can be made constant by controlling the etching conditions, and the flatness of the lower surface determined by the interface between the semiconductor regions 11 and 12 is also good. Because you can
The sensitivity of the semiconductor pressure sensor can be made uniform within a small variation.

The semiconductor pressure sensor shown in FIG.
The surface of the 10 where the recess 31 is provided, in the figure, the lower surface 10a is joined or adhered to a silicon pedestal or the like by a method such as soldering, and then attached through this pedestal, which is usually used in a dedicated container. Stored in a pressure sensitive diaphragm 60
It is used to measure or detect the differential pressure between two types of pressure applied from above and below. In practice, one of the vertical pressures is set as the reference pressure, and the other pressure, for example, the recess
It is often used to measure or detect the pressure introduced towards 31.

[Problems to be Solved by the Invention]

As described above, it is possible to manufacture a highly accurate semiconductor pressure sensor by the conventional method, but it takes a relatively long time to etch the recess, and the area of the semiconductor chip for that is reduced too much. There is a problem that cannot be solved.

As the etching time, the time required for the first etching for digging the prepared hole 31a in FIG. 4 is long, and usually about 2 hours or more when the thickness of the semiconductor region 11 is about 500 μm. Of course, if the thickness of the semiconductor region 11 is reduced, the etching time can be shortened.However, when the semiconductor pressure sensor is attached to the container, etc. as described above, a temperature error will occur unless the difference in the coefficient of thermal expansion from it is absorbed in this part. In addition, if the wafer becomes too thin, it will be very inconvenient to handle and trouble will occur. Therefore, it is not desirable to make the thickness of the semiconductor region 11 thinner than the current one. Further, if the etching time of the first etching is too long, the oxide film 90 for the mask is also attacked, which is likely to cause a defect.

The main reason why the chip area cannot be reduced is that a considerable area is required for the lower surface 10a of the base body 10 of FIG. 4 (b) in order to bond or bond the semiconductor pressure sensor to the pedestal.
As described above, the semiconductor pressure sensor is often used under the condition that one of the vertical pressures applied to the pressure-sensitive diaphragm is used as the reference pressure, so that even if there is a slight leak in the soldering part of the lower surface 10a, it can be used. This is because it becomes unbearable and the minimum area is required in order to guarantee the leak-free joining on the lower surface 10a.

Also, regarding the area of the recess 31, the minimum necessary normal for the pressure-sensitive diaphragm 60 is usually made to have a diameter of about 1.5 to 2 mm, but in the conventional method, even if the etching conditions are anisotropic, As can be seen from FIG. 7B, since it is inevitable that the side surface of the recess 31 is slightly inclined, there is a problem that an extra chip area is required for this inclination. In particular, recently, there is an application in which a semiconductor pressure sensor is used as a so-called tactile sensor. In this case, since it is necessary to form a large number of pressure-sensitive diaphragms in a matrix in one chip, the recess 31 is formed as a whole. A large area will be eaten only by the inclination.

An object of the present invention is to solve such a problem, to shorten the etching time required for forming the pressure-sensitive diaphragm of the semiconductor pressure sensor, and to reduce the chip area thereof.

[Means for solving the problem]

According to the present invention, an object of the present invention is to provide a semiconductor pressure sensor in which a pressure-sensitive diaphragm is formed by digging a recess in the same manner as in the conventional art. A semiconductor region of the other conductivity type is placed in contact with the substrate, a strain gauge is formed on the other surface of this substrate by diffusion, and a groove is physically formed within the range corresponding to the strain gauge of the semiconductor region of the one conductivity type. A processing method is used to engrave so as to limit the periphery of this range, and a semiconductor region of one conductivity type within this range is engraved to the interface with the semiconductor region of the other conductivity type by electrolytic etching to form a recess. This is achieved by the first manufacturing method.

As the above-mentioned physical processing method, it is preferable to use a laser processing method.

Further, the above-mentioned object is a structure in which the pressure-sensitive diaphragm of the semiconductor pressure sensor is formed by providing a cavity below the pressure-sensitive diaphragm instead of the above-mentioned recess. Therefore, one of the silicon semiconductor substrates of one conductivity type is formed. A high-impurity-concentration semiconductor layer of the other conductivity type is formed in a predetermined range on the surface side, and an epitaxial semiconductor layer of one conductivity type is grown in contact with the surface of the semiconductor layer. A strain gauge is formed in the corresponding area by diffusion, and an etching path is dug from the other surface side of the substrate to reach the high impurity concentration semiconductor layer by a physical processing method. It is also achieved by the second method, in which the concentration semiconductor layer is formed in the cavity by the chemical etching method.

A laser processing method is also suitable for the above-described physical processing method, and it is desirable to dig a long and narrow hole as an etching path by this method. This etching path not only serves as a passage for the etching solution when the high impurity concentration layer is formed in the cavity by the chemical etching method, but also as a passage when introducing the measured pressure into the cavity or closing the cavity as a reference pressure chamber. can do. Further, the high impurity concentration layer in the above structure can be formed as a buried diffusion layer or a buried epitaxial layer.

[Action]

In the first method described above, the pressure-sensitive diaphragm is formed by digging the recess as in the conventional method, but instead of digging the prepared hole by etching as in the conventional method, the groove is dug by a physical processing method such as laser processing. By doing so, the time required for so-called pre-etching before finish etching is shortened, and electrolytic etching is used for finish etching as in the conventional method, but the time required for digging a recess is half that of the conventional method. It can be shortened to

Further, in this method, since the groove is dug so as to limit the peripheral edge of the recess as in the above-mentioned configuration, the shape of the recess is restricted by the groove even after the finish etching, and the side surface has no inclination. It is possible to reduce the chip area by about 20% by the amount of inclination, which is particularly advantageous for a tactile sensor in which a large number of pressure-sensitive diaphragms are built in one chip.

The second method described above is different from the conventional method in that the pressure-sensitive diaphragm is formed by forming a cavity in the lower side of the pressure-sensitive diaphragm, but the chemical etching rate for the high impurity concentration layer is much higher than that for the low impurity concentration layer. Paying attention to the obtainment, the high impurity concentration layer is embedded in advance in the substrate for the semiconductor pressure sensor. As a specific means for this, as described in the above configuration, a high impurity concentration layer is formed in a predetermined range on one surface of the silicon semiconductor substrate by a method such as diffusion, and an epitaxial layer is grown on the layer. The epitaxial layer is used as a pressure-sensitive diaphragm after forming the cavity.

To make a cavity, first, an etching path is dug from the other surface side of the substrate by a physical processing method such as a laser processing method so as to reach a high impurity concentration layer, and then a high impurity concentration is passed through this etching path. Only the layers are selectively chemically etched. In this method, the digging of the etching path is very short, and the time for chemical etching may be the same as that for the conventional finish etching. Therefore, the time required for forming the pressure-sensitive diaphragm can be shortened to about one fifth of the conventional time. .
In addition, since the bottom surface of the base of the semiconductor pressure sensor or the other surface of the substrate has a very small etching path of 1 mm or less, almost the entire surface can be used for joining or bonding with a pedestal, etc. It can be reduced to less than half.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The same parts as those in FIG. 4 described before in the drawing are designated by the same reference numerals, and the description of the overlapping parts will be omitted. FIG. 1 shows an embodiment in which a pressure-sensitive diaphragm is formed by digging a recess.

As shown in FIG. 1A, the semiconductor substrate 10 used in this embodiment has the same semiconductor region as in FIG.
It has a three-layer structure including 11 to 13, for example, an n-type semiconductor region 11 is used as a substrate, and a p-type semiconductor region 12 and an n-type semiconductor region 13 are epitaxial layers sequentially grown thereon. However, for example, the p-type semiconductor region 12 may be formed by diffusion from the surface of the substrate. Further, in the essence of the present invention, the semiconductor region 11 of one conductivity type which is n-type in this example and the semiconductor region 12 of the other conductivity type which is p-type in this example may be of opposite conductivity types, Therefore, the substrate 10 need only have a two-layer structure. In this embodiment, the thickness of the semiconductor region 11 which is a substrate is, for example, 400 to 500 μm, the thickness of the semiconductor region 12 which is an epitaxial layer is about 20 to 30 μm, and the thickness of the semiconductor region 13 which is also an epitaxial layer is about 10 μm. It The strain gauge 20 is formed as a p-type resistance layer from the surface of the semiconductor region 13, which is n-type in this example, in the same manner as in FIG.

FIG. 1 (b) shows a trench digging process in which the trench is formed in the semiconductor region 11 by, for example, a laser processing method.
It is dug to the depth near the interface with. As a laser device used for this purpose, a high-power excimer laser is preferable, and a rod-type or slab-type solid-state laser having a long wavelength can be used. For grooving, the laser beam is focused so that the groove can be dug with a width of 0.3 to 0.5 mm. Since the groove pattern is generally circular in the recesses, the outer circular groove 30 that limits the periphery or peripheral surface of the groove is used.
a and the inner straight pattern is usually multiple grooves 30b
And are appropriately combined. The laser grooving speed is sufficiently high, and when 500 to 1000 semiconductor pressure sensors are built per wafer, this can be completed in 30 minutes to 1 hour. The oxide film 90 used as a mask for etching in the next step is preferably deposited in advance before this groove cutting.

FIG. 1 (c) shows a finishing process of the recess 30 by electrolytic etching. By electrolytically etching the n-type semiconductor region 11 at a low voltage using a hydrofluoric acid solution of about 5% as in the conventional case, The recess 30 is dug to a depth regulated at the interface with the p-type semiconductor region 12 to form the pressure-sensitive diaphragm 60. The peripheral surface of the recess 30 after this finish etching is formed in the shape of a right circular cylinder without inclination, as shown in the figure, because its approximate shape is already limited by the circular pattern of grooves 30a. Further, the time required for this electrolytic etching can be shortened as compared with the conventional case by devising the engraving pattern of the groove 30, and it is usually about 20 to 30 minutes. After completion of this finishing etching, the oxide film 90 is removed, and then the semiconductor pressure sensor is isolated from the wafer to obtain the state shown in the drawing.

In this embodiment, the time required for digging the recess 30 is half or less than that of the conventional one, and since the peripheral surface of the recess 30 is not inclined, the semiconductor pressure sensor of the conventional pressure sensor shown in FIG. The chip area can be reduced by about 20%.

2 and 3 both show an embodiment in which a pressure-sensitive diaphragm is formed by a cavity. First, the embodiment shown in FIG. 2 will be described.

The substrate 15 shown in FIG. 2 (a) is an n type in this example, and a low impurity concentration having a specific resistance of about several Ωcm and a thickness of several hundred μm is used for this. An oxide film 91 is attached to the surface, and a window is punched out in the predetermined area as shown. In the next step (b) of the same figure, the high impurity concentration layer 16 is formed from the surface of the substrate 15 by a solid diffusion method using the oxide film 91 as a mask with a specific resistance of about 0.01 Ωcm in this example. Although the high impurity concentration layer 16 is p-type in this embodiment, it may be n-type as long as it has a specific resistance of about 0.07 Ωcm or less. Since the size of the cavity is determined by the high impurity concentration layer 16, the diffusion is deeper, for example, 20 to 30 μm.

In the step of FIG. 7C, first, the oxide film 91 is removed, and then the epitaxial layer 18 is grown on the substrate 15 at a low impurity concentration that provides a specific resistance of about several Ωcm, and in this example, n-type. . Since the pressure-sensitive diaphragm is formed by this epitaxial layer 18 in a later step, the thickness of the epitaxial layer 18 is set to, for example, 30 to 40 μm suitable for it. It should be noted that this epitaxial layer 18 is preferably grown at a relatively low temperature so that impurities from the high impurity concentration layer 16 therebelow do not rise into it. As described above, the base body 10 or the wafer for forming the semiconductor pressure sensor in this embodiment is completed.

In FIG. 2 (d), first, a strain gauge 20 is formed on the surface of the epitaxial layer 18 in the same manner as described above, and then the substrate is formed.
In this example, one elongated hole is dug from the surface of the substrate 15 on the back side of the substrate 10 as an etching path 40 to a depth reaching the high impurity concentration layer 16 by a physically appropriate processing method such as a laser processing method. The diameter when the etching path 40 is laser processed is 0.3 to 0.5 mm, and the diameter is 1 m when it can be opened by electrical discharge machining or machining.
It does not matter if it is about m.

FIG. 2 (e) shows a cavity etching process, and the etching liquid is, for example, 8: 3: 1 of acetic acid, nitric acid and hydrofluoric acid.
The high impurity concentration layer 16 is selectively etched from the etching path 40 in a state in which the wafer is immersed in the etching liquid using a mixed liquid of the ratio. This causes the cavity 50 to be drilled as shown and the epitaxial layer 18 thereon to be formed on the pressure sensitive diaphragm 60. Although depending on the conditions at this time, the etching rate for the high impurity concentration layer 16 is 1 to 3 μm / min, and the low impurity concentration substrate 15 and the epitaxial layer 18 are hardly etched. Cavity 50
The time required for etching is usually 10 to 20 minutes and does not exceed 30 minutes at the longest. Since the substrate 15 is hardly etched, it is not necessary to protect the surface of the substrate 15 with an oxide film or the like as an etching mask as in the previous embodiment.

The embodiment of FIG. 3 utilizes an epitaxial layer as the high impurity concentration layer. In the step of FIG. 3A, the upper surface of the substrate 15 is dug with an etching solution of caustic potash to form the recess 15a with a maximum depth of about 30 .mu.m using the oxide film 92 as a mask. In this example, since the caustic potash solution is an anisotropic etching solution, the recess 15a has an open V-shape as shown in the figure. However, the recess 15a has a smooth shape that is recessed upward in the figure. Good.

In the step of FIG. 7B, a p-type epitaxial layer 17a having a high impurity concentration in this example is grown to a thickness of 30 μm or more on the upper surface of the substrate 15 from which the oxide film 92 has been removed. The impurity concentration of the epitaxial layer 17a is sufficiently increased so that it has a specific resistance of about 0.07 Ωcm or less as before. Further, after this growth, the epitaxial layer 17a is removed by lapping or the like up to the surface indicated by LF in the figure.

In the next step (c) of the same figure, an epitaxial layer 18 is formed thereon with the same low n-type impurity concentration as in the previous embodiment.
The above-mentioned epitaxial layer grown to a thickness of 30-40 μm
17a is buried under the high impurity concentration layer 17.
This completes the substrate 10 for this embodiment, in which the high impurity concentration layer 17 corresponds to the cavity and the upper portion of the epitaxial layer 18 corresponds to the pressure-sensitive diaphragm.

FIG. 3D shows a step of forming a strain gauge 20 in the epitaxial layer 18 and providing an etching path 40 from the back side of the substrate 10, and FIG. 3E shows a step of forming a pressure sensitive diaphragm 60 by punching a cavity 51. The steps are the same as those in the embodiment of FIG. 2, but the description of these steps will be omitted.

2 and 3, the time required to form the pressure sensitive diaphragm 60 by the cavities 50 to 51 is reduced to about one fifth of the conventional time. Also,
Since only the small-diameter etching path 40 is opened on the lower surface 10a of the base 10 of the semiconductor pressure sensor, almost all of the lower surface 10a can be used for joining or bonding with a pedestal or the like.
This can reduce the chip area of the semiconductor pressure sensor by half.

In these examples, since the diameter dimension of the pressure-sensitive diaphragm 60 can be preset by the width of the high impurity concentration layers 16 to 17, the diameter dimension accuracy of the pressure-sensitive diaphragm is improved as compared with the conventional one, and the variation in sensitivity is increased. It is possible to manufacture a semiconductor pressure sensor having a small number of components. Furthermore, by choosing the depth of the cavities 50-51 to be much smaller than in the previous embodiment, when the pressure-sensitive diaphragm 60 above it flexes under excessive pressure from above, the bottom surface of the cavity will be offset by it. It can also serve as a stopper and prevent the damage of the feeling.

As can be seen from the above-described embodiments, the present invention is not limited to such an example, and can be implemented in various modes to bring out its unique effects.

〔The invention's effect〕

As described above, according to the first method of the present invention for forming the pressure-sensitive diaphragm by the recess, the silicon semiconductor substrate is in contact with the semiconductor region of one conductivity type on one surface side thereof and of the other conductivity type. A semiconductor region is provided and placed, and a strain gauge is created on the other surface of this substrate by diffusion,
By digging a groove in a range corresponding to the strain gauge of one conductivity type semiconductor region so as to limit the peripheral edge of this range by a physical processing method, most of the digging amount for the recess is physically Efficiently by excavating the semiconductor region of one conductivity type within the range limited by the physical processing method to the interface with the semiconductor region of the other conductivity type by the electrolytic etching method. By finishing forming the place, the time required for digging the recess can be reduced to less than half that in the conventional case.

Furthermore, according to this first method, the finish digging of the recess into one semiconductor region by electrolytic etching is automatically stopped at the interface with the other semiconductor region, so that the depth of the recess, and thus the formation thereof, is formed. The thickness of the pressure-sensitive diaphragm can be accurately controlled to make the sensitivity of the semiconductor pressure sensor uniform, and the peripheral surface of the recess can be limited by the physical processing method in advance to make it inclined. Since it is possible to dig a recess that does not have a chip, the chip area of the semiconductor pressure sensor can be reduced by about 20% compared to the conventional case.

According to the second method of the present invention for forming a pressure-sensitive diaphragm by a cavity, a high impurity concentration layer is formed in a predetermined area on one surface of a silicon semiconductor substrate, and an epitaxial layer is grown and placed on the high impurity concentration layer. After forming a strain gauge by diffusion in the range corresponding to the high impurity concentration layer on the surface of, the etching path is efficiently dug by a physical processing method so as to reach the high impurity concentration layer from the other surface side of the substrate. By using this etching path, only the high impurity concentration layer is selectively etched by the chemical etching method to form the cavity, so that the pressure-sensitive diaphragm can be formed in a short time of about 1/5 of the conventional time. .

Further, in the second method, the size of the pattern of the high impurity concentration layer is controlled and set in advance, so that the diameter dimension of the pressure sensitive diaphragm can be accurately controlled and the sensitivity of the semiconductor pressure sensor can be made uniform. . Further, since there is only a thin etching path on the lower surface of the base of the semiconductor pressure sensor, almost the entire surface of the base can be used for bonding or adhering area with the pedestal or the like. It can be reduced to less than half.

 In addition to this, the present invention has the following effects.

(A) When it is necessary to form a large number of pressure-sensitive diaphragms in one semiconductor chip like a tactile sensor, the chip area can be reduced to one-tenth or less of the conventional one.

(B) When digging a prepared hole by etching as in the conventional case, an oxide film or the like as a mask for the same is not corroded to cause an unexpected defect, so that the damage is reduced and the semiconductor pressure sensor is reduced. The cost can be further reduced.

As described above, the present invention can make the sensitivity of the semiconductor pressure sensor more uniform than the conventional one, and can be remarkably effective in improving the economical efficiency by shortening the time required for its production and reducing the chip area. The present invention can contribute to further sophistication, spread, and development of semiconductor pressure sensors.

[Brief description of drawings]

1 to 3 relate to the present invention, and FIG. 1 is a sectional view of a semiconductor pressure sensor showing an embodiment of the present invention in which a pressure-sensitive diaphragm is formed by a recess, in a state of each main process,
FIG. 3 and FIG. 3 are cross-sectional views of a semiconductor pressure sensor showing different embodiments of the present invention in which a pressure-sensitive diaphragm is formed by a cavity in a state of each main process. FIG. 4 is a sectional view of a semiconductor pressure sensor showing a conventional manufacturing method in a state of each main step. In the drawing, 10: silicon semiconductor substrate or wafer for semiconductor pressure sensor, 10a: lower surface of substrate, 11: semiconductor region or substrate of one conductivity type, 12: semiconductor region or epitaxial layer of other conductivity type, 13: semiconductor region Or epitaxial layer, 15: semiconductor substrate, 15a: substrate recess, 16: high impurity concentration layer by diffusion layer, 17: high impurity concentration layer by epitaxial layer, 17a, 18: epitaxial layer, 20: strain gauge, 30:
Recess, 30a, 30b: Groove, 31: Recess, 31a: Prepared hole, 40: Etching path, 50, 51: Cavity, 60: Pressure sensitive diaphragm, 71: Oxide film, 7
2: connection film, 73: protective film, 80: connection pad, 90 to 92: oxide film, LF: lapping surface.

Claims (2)

[Claims] 1. A silicon semiconductor substrate is provided with a semiconductor region of one conductivity type on one surface side thereof in contact with a semiconductor region of the other conductivity type, and a strain gauge is provided on the other surface of the substrate by diffusion. A groove is formed in a range corresponding to the strain gauge of one conductivity type semiconductor region so as to limit the peripheral edge of this range by a physical processing method, and one conductivity type semiconductor region in this range is formed. The semiconductor pressure is characterized in that a recess is formed by digging up to the interface with the other conductivity type semiconductor region by the electrolytic etching method, and the substrate between this recess and the other surface is formed as a pressure-sensitive diaphragm. Sensor manufacturing method. 2. A high-impurity concentration semiconductor layer of the other conductivity type is formed in a predetermined area on one surface side of a silicon semiconductor substrate of one conductivity type, and an epitaxial semiconductor layer of one conductivity type is formed in contact with the surface thereof. A strain gauge is grown by diffusion in a range corresponding to the predetermined range on the surface side of the epitaxial semiconductor layer, and an etching path is formed in the high impurity concentration semiconductor layer from the other surface side of the substrate by a physical processing method. A semiconductor pressure sensor characterized in that it is dug to reach it, the high-impurity-concentration semiconductor layer is bored through this etching path into a cavity by a chemical etching method, and an epitaxial semiconductor layer portion on the cavity is formed into a pressure-sensitive diaphragm. Manufacturing method.