JPH02181472A - Manufacturing method of semiconductor pressure sensor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for 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 known, strain gauges using silicon semiconductors have extremely high gauge factors due to the piezoelectric effect of silicon, and single crystal silicon is also an ideal highly elastic material. By using this method to form a pressure-sensitive diaphragm in a silicon semiconductor chip and fabricating a strain gauge on its surface by diffusion, it is possible to create a small and highly sensitive semiconductor pressure sensor.This semiconductor device sensor They are usually several square pieces, and can be manufactured in large numbers from a single silicon wafer using essentially the same process as normal semiconductor devices.In this case, strain gauges and the like are first created on the surface of the wafer by diffusion. Then, a recess is dug from the back side by etching to form a strain gauge part on the pressure-sensitive diaphragm, and then it is cut into each chip.

Such semiconductor pressure sensors are suitable for mass production, but in practical terms it is necessary to make their sensitivity as uniform as possible.
The key to this is how to control the amount of digging into the recess to minimize variations in the dimensions of the pressure-sensitive diaphragm, especially the thickness. Various efforts have been made for this purpose, but the fourth The figure shows the outline of the method currently in use for digging this recess.

Figure 4 shows a cross section of one semiconductor pressure sensor in a wafer, with (a) showing the state in the middle of digging a recess, and (b) showing the state when completed. It is shown. The base 10 made of silicon semiconductor for pressure sensor is
In this example, an n-type semiconductor region 11 and a p-type semiconductor region 1
It has a three-layer structure of 2 and an n-type semiconductor 'yRhli 13, and the semiconductor region 11 is usually a 2↓ temporary with only several hundred pm of PI, and the semiconductor zI'I regions 12 and 13 are on top of it. There are only 17 epitaxial layers of a total of several tens of pl that were grown sequentially.

6. Before starting to dig a recess from the back side of this base 10. In this example on the front side, the n-type “11 conductor S! i area 1
A semiconductor resistance layer serving as a strain gauge 20 is diffused from the surface of 3 in a P type. Is this distortion 5'-ji20 normal? One or more, for example four, diffuse, break, and oxidize 1t covering the surface of the w body 10.
, 171 ] 2 Connecting film 72 is connected, for example, by a bridge, by means of connections IILA 72 made of aluminum or the like which are in conductive contact with both ends of gauge 20, respectively.
The upper part is covered with a protective film 73 made of silicon nitride or the like, and the connection film 72 in the open window portion is used as a connection pad 80 for connection with the outside.

FIG. 4(a) shows the state after the first etching for digging a recess. 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 region corresponding to the area where the strain gauge 20 is formed, and a prepared hole 31a is formed in the semiconductor region 11 near the interface with the semiconductor region 12 as shown in the figure by chemical etching using this oxidized 1119G as a mask. As the etching solution for digging deeply, for example, a mixed solution of hydrofluoric acid and nitric acid, which has a relatively high etching rate, is used.

Figures 4 and 4) show the completed state after the second or final etching. For this finishing, an n-type semiconductor region 1
By electrolytically etching 1, the etching is automatically stopped at the interface with the p-type semiconductor region 12. As a result, the prepared hole 31a shown in FIG. 2A is finished into a recess 31 whose depth is regulated by the interface between the semiconductor regions 11 and 12, as shown in FIG. After completing the digging of the recess 31, the oxide film 90 used as an etching mask is removed, and the wafer is separated into chips by scribing to form the state shown in the figure.

In the semiconductor pressure sensor manufactured in this way, the semiconductor regions 12 and 13 within the range where the strain gauge 20 is formed above the recess 31 in the figure become the pressure sensitive diaphragm 60. Therefore, the thickness of the pressure-sensitive diaphragm 60 can be made constant by carefully controlling the thickness of the amphibic conductor regions 12 and 13 in advance, and the area thereof can be made constant by controlling the etching conditions.
Since the flatness of the lower surface determined by the interface between the semiconductor region 12 and the semiconductor region 12 can also be improved, the sensitivity of the semiconductor pressure sensor can be uniformly adjusted within small variations.

The semiconductor pressure sensor shown in FIG. 4(c) has a base body 1.
In Figure 1, the bottom surface 10 is the side where the recess 31 is provided.
After bonding or gluing a to a silicon pedestal or the like by means of soldering or other methods, the diaphragm 60 is usually housed in a special container by attaching it via this pedestal, and hangs from above and below against the pressure-sensitive diaphragm 60. It is used to measure or detect the differential pressure between two types of pressure. In practice, one of the upper and lower pressures is set as a reference pressure, and the other pressure 1, for example, is often used to measure or detect the pressure introduced toward the recess 31.

[Problem to be solved by the invention]

As mentioned above, a highly accurate semiconductor pressure sensor can be manufactured by the conventional method, but etching to dig the recess takes a relatively long time, and the area of the semiconductor chip used for it cannot be reduced much. Problems remain.

As for the etching time, the time required for the first etching to dig the pilot hole 31a in FIG. 4 is long, and when the thickness of the semiconductor region 11 is about 500 nm, it usually takes about 2 hours or more. Of course, the etching time can be shortened by reducing the thickness of the semiconductor region 11, but as mentioned above, when the semiconductor pressure sensor is attached to a container etc., temperature errors will occur unless this part absorbs the difference in thermal expansion coefficient between the semiconductor pressure sensor and the container. In addition, if the wafer becomes too thin, handling becomes very inconvenient and problems occur, so it is undesirable to make the semiconductor region 11 thinner than the current thickness.Also, if the first etching time is too long, the mask Oxide film 9
0 is likely to be affected and cause defects.

The main reason why the chip area cannot be reduced is that a considerable area is required on the lower surface 10a of the base 10 of FIG.

As mentioned above, semiconductor pressure sensors are often used under the condition that one of the upper and lower pressures applied to the pressure-sensitive diaphragm is the reference pressure. This is because a minimum area is required to ensure leak-free bonding at the lower surface 10a.

Also, regarding the area of the recess 31, the pressure sensitive diaphragm 60
The minimum required diameter is usually about 1.5 to 2 amu, but in the conventional method, even if the etching conditions are anisotropic, as shown in the same figure Since it is unavoidable that the sides of the recess 31 are slightly sloped, there is a problem in that an extra chip area is required for the slope. Particularly recently, semiconductor pressure sensors have been used for various types of tactile sensors, and in this case, it is necessary to fabricate a large number of pressure-sensitive diaphragms in a matrix in one chip. A large area will be eaten up by the slope alone.

SUMMARY OF THE INVENTION An object of the present invention is to solve these problems, to shorten the etching time required to form a pressure-sensitive diaphragm of a semiconductor pressure sensor, and to reduce the chip area thereof.

(Means for Solving the Problems) According to the present invention, this object 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 past. A semiconductor region of one conductivity type is provided in contact with a semiconductor region of the other conductivity type on the side, and a strain gauge is formed on the other surface of this substrate by diffusion, and a strain gauge is formed in the semiconductor region of one conductivity type. A groove is dug in the corresponding range using a physical processing method so as to limit the periphery of this range, and a semiconductor region of one conductivity type within this range is etched using an electrolytic etching method to connect the semiconductor region of the other conductivity type. This is achieved by the first manufacturing method of forming a recess by digging down to the interface.

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

Furthermore, the above-mentioned object is to provide a structure in which the pressure-sensitive diaphragm of the semiconductor pressure sensor is formed by providing a cavity under the above-mentioned recess instead of forming the pressure-sensitive diaphragm by the above-mentioned recess. A high impurity concentration layer is created in the area, an epitaxial layer is grown on top of it, and a strain gauge is created by diffusion in the area corresponding to the high impurity concentration layer on the surface of the epitaxial layer, and then the strain gauge is grown from the other side of the substrate. This can also be achieved by a second method in which an etching path is dug to reach the high impurity concentration layer by a physical processing method, and a cavity is bored in the high impurity concentration layer through the etching path by a chemical etching method.

Note that the laser processing method is similarly suitable for the above-mentioned physical processing method, and it is desirable to use this method to dig a long and narrow hole as an etching path. In addition to serving as a passage for the etching solution during etching, it can also be used as a passage when introducing the pressure to be measured into the cavity or sealing off the cavity as a reference pressure chamber. Further, the high impurity concentration layer in the above structure can be formed on a buried diffusion layer or a buried epitaxial layer.

[Effect]

In the first method described above, the pressure-sensitive diaphragm is formed in the same way as before (by digging a recess), but instead of digging the bottom by etching as in the conventional method, the groove is formed by a physical processing method such as laser processing. This method shortens the time required for pre-etching before final etching, rather than digging in. Although electrolytic etching is used for final etching as in the past, the time required for digging in recesses is halved compared to conventional etching. It can be shortened to 1 or less.

Furthermore, in this method, the groove is dug so as to limit the periphery of the recess as described above, so even after finishing etching, the shape of the recess is regulated by the groove, eliminating the slope of the side surface, which was conventional. The chip area can usually be reduced by about 20% by the inclination of , and as is easily understood, this is particularly advantageous for tactile sensors and the like in which a large number of pressure-sensitive diaphragms are built into one chip.

The second method described above is different from the conventional method in that a pressure-sensitive diaphragm is formed by drilling a cavity underneath it, but the chemical etching rate for a high impurity concentration layer is much higher than that for a low impurity concentration layer. As a specific means for embedding this high impurity concentration layer in the substrate for a semiconductor pressure sensor in advance, focusing on obtaining A high impurity concentration layer is formed in a predetermined area by means of diffusion or the like, an epitaxial layer is grown thereon, and this epitaxial layer is used as a pressure-sensitive diaphragm after a cavity is provided.

To create a cavity, first, an etching path is dug from the other side of the substrate using a physical processing method such as laser processing to reach the high impurity concentration layer, and then the high impurity concentration layer is etched through this etching path. Selective chemical etching of only the layers. This method requires only a short time to dig the etching path, and the chemical etching time is the same as that of conventional finishing etching, so the time required to form the pressure-sensitive diaphragm can be reduced to about one-fifth of the conventional method. In addition, since there is only a very thin etching path of less than l+am on the bottom surface of the base of the semiconductor pressure sensor or the other surface of the substrate, the entire surface of the etching path can be used for joining or adhering to a pedestal, etc., so the chip area can be reduced. It becomes possible to reduce the size to less than half of the conventional size.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. In FIG. 0, the same parts as in FIG. FIG. 1 shows an embodiment in which the pressure sensitive diaphragm is formed by digging a recess.

As shown in FIG. 1(a), the semiconductor substrate lO used in this embodiment has a three-layer structure including semiconductor regions 11-13, as in the case of FIG. is used as a substrate, and a p-type semiconductor region 12 and an n-type semiconductor region 13 are grown as an epitaxial layer sequentially thereon. For example, the p-type semiconductor region 12 is formed by diffusion from the surface of the substrate. It's okay,
Furthermore, the essence of the present invention is that 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, are of opposite conductivity type. Therefore, it is sufficient that the substrate IO has 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 nm, and the thickness of the semiconductor region 13 which is also an epitaxial layer is about ton. Ru. The strain gauge 20 is connected to the semiconductor region 13, which is n-type in this example.
A p-type resistance layer is formed from the surface of the resistor layer in the same manner as in the case of FIG.

FIG. 1(b) shows a step of digging a trench, in which a trench is formed in the semiconductor region 11 by, for example, a laser processing method.
It is dug to a depth that reaches close to the interface with 2. As a laser device used for this purpose, a high-output excimer laser is preferable, and a rondo-type or slab-type solid-state laser can also be used, although the wavelength is longer. For cutting grooves, the laser beam is narrowed down so that grooves with a width of 0.3 to 0.5 m can be dug.

The pattern of groove cutting is that the recess is usually circular, so the l
an outer circular pattern of grooves 3 defining an edge or circumference;
0a and usually a plurality of grooves 30b in the linear pattern inside the grooves 30b are appropriately combined. The speed of this laser grooving is sufficiently fast, 500 to 1000 per wafer.
When fabricating several semiconductor pressure sensors, it can be completed in 30 minutes to one hour. Incidentally, it is preferable that an oxide film 90 as a mask for etching in the next step be deposited in advance before this groove cutting.

FIG. 1C shows the finishing process of the recess 30 by electrolytic etching, in which the n-type semiconductor region 11 is electrolytically etched under low voltage using a hydrofluoric acid solution of about 5% as in the conventional method. The pressure sensitive diaphragm 60 is formed by digging the recess 30 to a depth regulated by the interface with the shaped semiconductor region 12. The peripheral surface of the recess 30 after this final etching has already been roughly defined in shape by the aforementioned circular pattern grooves 30a, so it is formed into a right cylindrical surface with no inclination as shown. In addition, the time required for this electrolytic etching can be shortened (usually 20 to 30 minutes) by devising the digging pattern of the grooves 30.
After completing this final etching, which takes about a minute, the oxide film 90 is removed and the semiconductor pressure sensor is isolated from the wafer to form the state shown in the figure.

In this embodiment, the time required to dig the recess 30 is half or less than that of the conventional method, and since there is no slope on the circumferential surface of the recess 30, the semiconductor pressure sensor The chip area can be reduced by about 20%.

2 and 3 each show an embodiment in which the pressure sensitive diaphragm is formed by a cavity. First, the embodiment of FIG. 2 will be explained.

The substrate 15 shown in FIG. 2(a) is of n-type in this example, and has a resistivity of about several C1, a low impurity concentration, and a thickness of several hundred nanometers. In the zero-order process shown in FIG. 9(c), in which an oxide film 91 is attached to the surface and a window is punched out in a predetermined range as shown in the figure, the high impurity concentration layer 16 is removed from the surface of the base @15 to the oxide film 91. In this example, this high impurity concentration layer 16 is made with a resistivity of about 0.0IQC11 by a solid-state diffusion method using a mask as a p-type, but its resistivity is 0.07Ω1. As long as the layer has a high impurity concentration of less than 100 nm, it can be an n-type layer.Since the size of the cavity is determined by this high impurity concentration layer 16, its diffusion is deep, for example, 20 to 30 nm.

In the step shown in FIG. 2C, the oxide layer 1191 is first removed, and then the epitaxial layer 18 is grown on the substrate 15 at a low impurity concentration with a resistivity of about several C1, and in this example is n-type. Since a pressure-sensitive diaphragm will be formed from this epitaxial layer 18 in a later step, the thickness of the epitaxial layer 18 is set to a suitable thickness, for example, 30 to 40 nm. In this embodiment, the epitaxial layer 18 is preferably grown at a relatively low temperature of 0 or higher so that impurities from the high impurity concentration layer 16 below do not rise into the epitaxial layer 18. A substrate 10 or wafer for fabricating the sensor is completed.

In FIG. 2(d), first, the strain gauge 20 is formed from the surface of the epitaxial layer 18 in the same manner as described above, and then one etched path 40 is formed from the surface of the substrate 15 on the back side of the base 10. When the etching path 40 is laser-processed by digging an elongated hole to a depth that reaches a high impurity concentration of 3116 by a physical processing method such as a laser processing method, the diameter is 0.3 to 0.5 mm. If the hole is to be opened by electrical discharge machining or machining, the diameter may be set to about 1 mm.

FIG. 2(e) shows the etching process of the cavity, and the etching solution is, for example, i3:3 of acetic acid, nitric acid, and hydrofluoric acid.
The high impurity concentration layer 16 is selectively etched from the etching path 40 with the wafer immersed in the etching solution using a mixed solution having a ratio of :1. As a result, cavity 5
0 is drilled as shown and the epitaxial layer 1 thereon is
8 is formed on the pressure sensitive diaphragm 60. In this limit, although it varies depending on the conditions, the etching rate for the high impurity concentration layer 16 is 1 to 3 nm per minute, and the substrate 15 and epitaxial layer 18 with low impurity concentration are hardly etched.The time required for etching the cavity 50 is obtained. teeth,
The etching time is usually 10 to 20 minutes, but does not exceed 30 minutes at most. Since the group [15] is hardly etched, it is 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. There isn't.

The embodiment shown in FIG. 3 uses an epitaxial layer as the high impurity concentration layer. In the process shown in FIG. 2(a), the upper surface of the substrate 15 is etched with an etching solution of, for example, caustic potash using oxidized 11192 as a mask to form a recess 15a with a depth of, for example, 30 mm.
Make it to a maximum depth of about a. In this example, the caustic potash solution is an anisotropic etching solution, so the recess 15a has an open ■-shaped shape as shown in the figure. good.

In the process shown in FIG. 2B, the substrate 15 from which the oxide film 92 has been removed
In this example, a p-type epitaxial layer 17a with a high impurity concentration is grown on the upper surface of the substrate to a thickness of over 30 a. The impurity concentration of this epitaxial layer 17a is the same as before < O, OV
It can be sufficiently increased to have a specific resistance of about Ω1 or less. Furthermore, after this growth, the epitaxial jl17a becomes L in the figure.
The surface indicated by P is removed by lapping or the like.

In the next step (C) in the same figure, an epitaxial film is formed on top of it.
J18 is grown to a thickness of, for example, 30 to 40p@ with an n-type impurity with a low I11 concentration as in the previous embodiment, and the above-mentioned epitaxial layer 17a is buried thereunder as a high impurity concentration layer 17. The base body 10 for this example is now completed, 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. 3(a) shows the step of fabricating the strain gauge 20 in the epitaxial layer 18 and providing the etching path 40 from the back side of the base 10, and FIG. 3(e) shows the process of drilling the cavity 51 to form the pressure sensitive diaphragm 60 Since the steps are the same as those in the embodiment shown in FIG. 2, explanations of these steps will be omitted.

In both the embodiments of FIGS. 2 and 3, the time required to form pressure sensitive diaphragm 60 with cavities 50-51 is reduced to a conventional 5 minute process. In addition, since only a small-diameter etching path 40 is opened on the lower surface 10a of the base 10 of the semiconductor pressure sensor, the lower surface 10
Almost all of 0a can be used for joining or adhering to a pedestal, etc., and thereby the chip area of the semiconductor pressure sensor can be halved.

In these embodiments, the diameter of the pressure-sensitive diaphragm 60 can be set in advance by the width of the high impurity concentration layers 16 and 17, so that the precision of the diameter of the pressure-sensitive diaphragm can be improved compared to conventional methods, and variations in sensitivity can be reduced. It is possible to manufacture a semiconductor pressure sensor with less Furthermore, by selecting the depth of the cavities 50-51 to be much smaller than in the embodiments described above, when the pressure sensitive diaphragm 60 thereon is deflected due to excessive pressure from above, the bottom surface of the cavity is It can also act as a stopper to prevent damage to the surface.

As can be seen from the embodiments described above, the present invention is not limited to these examples, and can be implemented in various embodiments to achieve its unique effects.

〔Effect of the invention〕

As described above, in the first method according to the present invention in which a pressure sensitive diaphragm is formed by a recess, a semiconductor $R region of one conductivity type is in contact with the semiconductor $R region of one conductivity type on one surface side of the silicon semiconductor substrate, and the other i A semiconductor region of one conductivity type was provided, and a strain gauge was created on the other surface of this substrate by diffusion.''Then, a groove was physically machined within the range corresponding to the strain gauge in the semiconductor region of one conductivity type. By digging to limit the periphery of this area using the method, most of the amount of digging for the recess can be efficiently dug through physical processing, and then the area limited by the physical processing method is By etching the semiconductor region of one conductivity type to the interface with the semiconductor region of the other conductivity type to finish forming the recess, the time required to dig the recess is less than half of the conventional etching time. can be reduced to

Furthermore, according to this first method, the depth of the recess, and therefore the formation It is possible to precisely control the thickness of the pressure-sensitive diaphragm to make the sensitivity of the semiconductor pressure sensor uniform, and by defining the circumference of the recess in advance using physical processing, Since it is possible to dig a recess with no slope in the surface, the chip area of the semiconductor pressure sensor can be reduced by about 20% compared to the conventional one.

In a second method according to the present invention in which a pressure-sensitive diaphragm is formed 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 on the layer. After forming a strain gauge by diffusion in a range corresponding to the high impurity concentration layer on the surface of the substrate, an etching path is efficiently dug using a physical processing method to reach the high impurity concentration layer from the other side of the substrate. By using this etching path and selectively etching only the high impurity concentration layer using chemical etching to create a cavity, a pressure-sensitive diaphragm can be formed in about one-fifth of the time required by conventional methods. .

In addition, in this second method, by controlling the size of the pattern of the high impurity concentration layer in advance, it is possible to control the diameter of the pressure-sensitive diaphragm with high precision (controlling it) to make the sensitivity of the semiconductor pressure sensor uniform. Furthermore, since there is only a thin etched path on the bottom surface of the base of the semiconductor pressure sensor, almost the entire surface can be used as an area for bonding or adhesion to a pedestal etc., so the chip area of the semiconductor pressure sensor can be reduced. It can be reduced to less than half of the conventional size.

In addition, the present invention has the following effects.

(a) When a large number of pressure-sensitive diaphragms need to be built into one semiconductor chip, such as in a tactile sensor, the chip area can be reduced to one tenth or less of the conventional size.

(b) When etching the bottom hole as in the past, the oxide film used as a mask will not be eroded and unexpected defects will occur. The cost can be further reduced.

As described above, the present invention can be significantly effective in making the sensitivity of a semiconductor pressure sensor more uniform than before, reducing the time required for manufacturing it, and reducing the chip area, thereby improving its economic efficiency. Therefore, the present invention can contribute to further advancement, spread, and development of semiconductor pressure sensors.

[Brief explanation of the drawing]

1 to 3 relate to the present invention, and FIG. 1 is a cross-sectional view of a semiconductor pressure sensor showing the state of each main process of an embodiment of the present invention in which a pressure-sensitive diaphragm is formed by a recess, and FIG.
3 and 3 are cross-sectional views of a semiconductor pressure sensor showing each main process of different embodiments of the present invention in which a pressure-sensitive diaphragm is formed by a cavity. FIG. 4 is a cross-sectional view of a semiconductor pressure sensor showing the state of each main process in a conventional manufacturing method. In FIG. 12: Semiconductor region or epitaxial layer of the other conductivity type, 13: Semiconductor region or epitaxial layer, 15: Semiconductor substrate, 15a: Recess in substrate, 16: High impurity concentration layer formed by diffusion layer. , 17: High impurity concentration layer formed by epitaxial layer, 17a, 18: Epitaxial layer, 20: Strain gauge, 30: Recess, 30a,
30b: full, 31: recess, 31a: pilot hole, 40: etching path, 50.51: cavity, 60: pressure sensitive diaphragm, 71: oxide film, 72: connection film, 73: protective film, 80
: Connection pad, 90-92: Oxide film, LF: Miniature Figure 1

Claims (1)

[Claims] 1) A semiconductor region of one conductivity type is provided in a silicon semiconductor substrate in contact with a semiconductor region of one conductivity type on one side of the substrate, and a semiconductor region of the other conductivity type is provided on the other surface of the substrate by diffusion. A strain gauge is fabricated, and a groove is dug in a range corresponding to the strain gauge in the semiconductor region of one conductivity type using a physical processing method so as to limit the periphery of this range. A recess is formed by etching the semiconductor region to the interface with the semiconductor region of the other conductivity type by electrolytic etching, and the base between the recess and the other surface is formed into a pressure-sensitive diaphragm. A method for manufacturing a semiconductor pressure sensor. 2) Create a high impurity concentration layer in a predetermined range on one side of the silicon semiconductor substrate, grow an epitaxial layer on it, and create a strain gauge by diffusion in a range corresponding to the high impurity concentration layer on the surface of the epitaxial layer. An etching path is dug from the other side of the substrate using a physical processing method to reach the high impurity concentration layer, and a cavity is formed in the high impurity concentration layer through this etching path using a chemical etching method. A method for manufacturing a semiconductor pressure sensor, comprising forming an epitaxial layer portion of the pressure sensitive diaphragm.