JP2008049438A - Manufacturing method of semiconductor device, semiconductor device and pressure sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a semiconductor device furnished with a cantilever beam type oscillating part of a stereoscopic structure capable of drastically simplifying the manufacturing method, the semiconductor device and a pressure sensor furnished with the semiconductor device. <P>SOLUTION: A cantilever beam type cantilever 10 constituted of a silicon oxide film 4 having compressive stress and a monocrystal silicon film 3 is formed by removing a silicon substrate 1 in a recessed shape until the silicon oxide film 4 is exposed by etching it from the back surface side of an SOI substrate 7 and removing part of the silicon oxide film 4 facing a space 1a from which the silicon substrate 1 is removed and the monocrystal silicon film 3 on the silicon oxide film 4. Consequently, the cantilever 10 warped up on the SOI substrate 7 is formed. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device including a cantilever obliquely provided on a substrate, a semiconductor device, and a pressure-sensitive sensor including the semiconductor device.

  2. Description of the Related Art In recent years, MEMS (Micro Electro Mechanical Systems) has been actively developed, and semiconductor devices (systems) called micromachines that fuse micro mechanical elements and electronic circuit elements by using silicon process technology are automobiles. It has come to be used in various fields such as sensors, information / communication, medical care, manufacturing, and environment. In particular, with the progress of semiconductor processing technology, research and development of micromachines including minute movable structures has become active, and micromachines that integrate a large number of microdevices on a silicon substrate (silicon chip) with nano-scale accuracy It is being put into practical use.

  In order to form a minute movable structure (for example, a cantilever) on a silicon substrate, there are roughly two manufacturing methods: bulk micromachining (removal processing) and surface micromachining (additional processing). In the bulk micromachining, a desired movable structure is formed by deep-digging a silicon substrate by 10 to 100 μm by dry etching or wet etching. In bulk micromachining, it is important to accurately separate the movable structure from the silicon substrate.

On the other hand, surface micromachining is a method in which a film layer is stacked on the surface of a silicon substrate to additionally form a desired movable structure on the surface of the silicon substrate. A movable structure can be obtained by processing into a desired shape by photolithography, etching, etc., and then removing only the sacrificial layer by selective etching (see Patent Document 1).
JP 2004-306217 A

  However, when the movable structure is formed by surface micromachining as in the example of Patent Document 1, it is necessary to perform sacrificial layer etching to remove the sacrificial layer. When a minute movable structure is formed, the thickness of the sacrificial layer is as thin as, for example, about several μm, and the gap between the movable structure and the silicon substrate surface becomes narrow, so that the movable structure sticks to the silicon substrate surface. There was a problem.

  There are sticking that occurs during the sacrificial layer etching that separates the movable structure from the surface of the silicon substrate, and sticking that occurs due to impact or static electricity after the separation. In order to prevent such sticking, an extra process such as a cleaning / drying step after etching or a water-repellent coating step is required, or a low-energy film is formed or protrusions are formed on the surface of the silicon substrate. There is a problem that the manufacturing process becomes complicated because a special process such as providing surface roughness is required. For this reason, it has been desired to simplify the manufacturing process for forming the movable structure.

  Further, in a field where a so-called three-dimensional micromachine in which a movable structure (for example, a cantilever) is obliquely provided from the surface of a silicon substrate is used, in order to form a three-dimensional movable structure by surface micromachining, It is necessary to stack a plurality of film layers having different internal stress (residual stress) states or to form a film layer in which the internal stress distribution is changed in the film thickness direction. For example, by forming a metal film having a residual tensile stress on the upper side of the silicon crystal film that is the lower layer, it is possible to form a movable structure that is warped.

  However, in order to make the movable structure into a three-dimensional structure (for example, a warped structure), it is necessary to newly form a film layer having an internal stress (residual tensile stress) on the silicon substrate. In the case of forming a metal film having a metal film, it is necessary to form an insulating film between the metal film and an electrode for taking out the flexure of the movable structure as an electric signal, which increases the number of manufacturing steps. It has been desired to simplify the manufacturing method.

  Further, when the movable structure is covered with a flexible resin layer, the gap between the movable structure and the surface of the silicon substrate is very narrow, so that there is a problem that the resin is not sufficiently filled below the movable structure.

  The present invention has been made in view of such circumstances, and the silicon layer (silicon substrate) is etched from the back side to remove the silicon layer in a concave shape until the insulating film is exposed, thereby removing the silicon layer. The insulating film facing the substrate and a part of the surface film on the insulating film are removed by etching to form a cantilever-like swinging portion (movable structure) made of the insulating film having the residual stress and the surface film. This makes it possible to form a three-dimensional cantilever-shaped swinging part that warps on the substrate, and does not require a complicated and special process to prevent sticking, and internal stress (residual tensile stress). It is not necessary to newly form a film layer having a thickness, the manufacturing method can be greatly simplified, and the back surface of the silicon layer is opened in a concave shape, so that the cantilever-like rocking portion is covered. Of resin layer And to provide a method of manufacturing a semiconductor device capable of improving the Hama property.

  Another object of the present invention is to apply a resin film to the silicon layer and the insulating film facing the space removed in a concave shape after removing the silicon layer, and after the swinging portion is formed. An object of the present invention is to provide a method of manufacturing a semiconductor device that can improve the yield by removing the resin film to prevent the swinging portion from abruptly warping.

  Another object of the present invention is to form a film layer having internal stress (residual tensile stress) on the upper surface side of the oscillating portion by using a surface film as a single crystal silicon film and an insulating film as a silicon oxide film. It is an object of the present invention to provide a method of manufacturing a semiconductor device and a semiconductor device that can easily form a swinging part that forms a three-dimensional structure (warped structure) without the need to do so.

  Another object of the present invention is to provide a three-dimensional structure comprising an active layer (single crystal silicon film) and a buried oxide film layer (silicon oxide film) by removing the support layer by bulk micromachining by using an SOI substrate as the substrate. An object of the present invention is to provide a semiconductor device manufacturing method and a semiconductor device in which a rocking portion of a structure can be formed by a simplified manufacturing process.

  Another object of the present invention is that the rocking portion is configured to be inclined by approximately 45 degrees outward with respect to the substrate surface, so that when the pressure sensitive element is provided on the rocking portion, the substrate surface An object of the present invention is to provide a semiconductor device that can detect the deflection of a swinging part due to a force acting in two directions, ie, a parallel direction and a vertical direction.

  Another object of the present invention is to detect a force acting on the oscillating portion by including a pressure sensitive element formed on the surface of the oscillating portion and an electrode connected to the pressure sensitive element. The object is to provide a pressure-sensitive sensor capable of

  According to a first aspect of the present invention, there is provided a method for manufacturing a semiconductor device, comprising: a cantilever-shaped swinging portion provided obliquely on a substrate having an insulating film having a residual stress and a surface film formed in this order on a surface of a silicon layer; A step of etching the silicon layer from the back side to remove the silicon layer in a concave shape until the insulating film is exposed, an insulating film facing the space from which the silicon layer has been removed, and the method And a step of removing a part of the surface film on the insulating film by etching to form a cantilever-like swinging portion made of the insulating film and the surface film.

  According to a second aspect of the present invention, there is provided a method for manufacturing a semiconductor device comprising: a step of applying a resin film to a silicon layer and an insulating film facing a space removed in a concave shape after removing a silicon layer; And a step of removing the applied resin film.

  A semiconductor device manufacturing method according to a third aspect of the invention is characterized in that the surface film is a single crystal silicon film and the insulating film is a silicon oxide film.

  A method for manufacturing a semiconductor device according to a fourth aspect of the present invention is characterized in that the substrate is an SOI substrate.

  A semiconductor device according to a fifth aspect of the present invention is a semiconductor device comprising a cantilever-like swinging portion disposed on a substrate on which an insulating film and a surface film are formed in this order on the surface of a silicon layer, The insulating film has a residual stress, and includes a recess formed on the back surface of the silicon layer so that the insulating film is exposed, an exposed insulating film, and a surface film on the insulating film. And a cantilever-shaped swinging portion provided obliquely on the substrate.

  The semiconductor device according to a sixth aspect of the invention is characterized in that the oscillating portion is configured to incline approximately 45 degrees outward with respect to the substrate surface.

  The semiconductor device according to a seventh aspect is characterized in that the surface film is a single crystal silicon film and the insulating film is a silicon oxide film.

  The semiconductor device according to an eighth aspect is characterized in that the substrate is an SOI substrate.

  A pressure-sensitive sensor according to a ninth invention is a pressure-sensitive sensor comprising the semiconductor device according to any one of the fifth to eighth inventions, the pressure-sensitive element formed on the surface of the oscillating portion, and the sensitivity And an electrode connected to the pressure element.

  In the first invention and the fifth invention, the silicon layer of the substrate on which the insulating film having the residual stress (residual compressive stress) on the surface of the silicon layer and the surface film are formed in this order is etched from the back side. The silicon layer is removed in a concave shape until the insulating film is exposed. As a result, the insulating layer is exposed with a required dimension facing the open space after the silicon layer is removed, and a two-layer structure including the exposed insulating film and the surface film on the insulating film is formed. The exposed insulating film and a part of the surface film on the insulating film are removed by etching so as to penetrate the front and back surfaces, thereby forming a cantilever-shaped swinging portion made of the insulating film and the surface film. Since the insulating film has residual stress, the residual stress (residual compressive stress) acts along the longitudinal direction of the cantilever-like swinging portion, and the cantilever-like swinging portion is fixed to the cantilever. With the end as a fulcrum, the insulating film side warps so as to be convex. As a result, a three-dimensional cantilever-like swinging portion that is inclined with respect to the surface of the substrate is formed.

  In the second invention, after removing the silicon layer, a resin film (for example, a photoresist) is applied to the silicon layer and the insulating film facing the space removed in the concave shape. Thus, the silicon layer and the exposed insulating film are fixed to the resin film. When the cantilever-like swinging part is formed in this state, since the insulating film of the swinging part is fixed to the resin film, the swinging part is prevented from suddenly warping due to insulating residual stress. The As a result, it is possible to prevent the swinging portion from being abruptly warped and being damaged when the swinging portion is formed. The resin film applied after the oscillating part is formed is removed so that the oscillating part gently warps.

  In the third and seventh inventions, the surface film is a single crystal silicon film and the insulating film is a silicon oxide film. Since the single crystal silicon film has no residual stress, while the silicon oxide film has residual stress (residual compressive stress), when the cantilever-like rocking part is formed by etching, the fixed end of the cantilever is not As a fulcrum, the silicon oxide film on the lower surface of the swinging portion is warped so as to be convex outward, so that a three-dimensional swinging portion can be formed. Since the three-dimensional rocking part is formed, it is not necessary to newly form a film layer having internal stress on the upper surface side of the rocking part.

  In the fourth and eighth inventions, the substrate is an SOI substrate. By removing the support layer of the SOI substrate by bulk micromachining, a two-layer structure including an active layer (single crystal silicon film) and a buried oxide film layer (silicon oxide film) is formed. The active layer and the buried oxide layer are patterned from the surface side of the SOI substrate and etched to form a desired planar shape to form a cut, thereby oscillating the three-dimensional structure composed of the active layer and the buried oxide layer. The part can be formed.

  In the sixth invention, the oscillating portion is configured to incline approximately 45 degrees toward the outside with respect to the substrate surface. Thereby, for example, when a pressure sensitive element capable of taking out an electric signal by the deflection of the oscillating part is formed on the surface of the oscillating part, a force acting in two directions, a parallel direction and a vertical direction, with respect to the substrate surface. Is detected substantially evenly by the swinging portion. Further, it is possible to efficiently capture the force acting in both the parallel direction and the vertical direction with respect to the substrate surface with one swinging portion.

  In the ninth invention, a pressure sensitive element (for example, a piezoresistive element, a piezoelectric element, etc.) and an electrode connected to the pressure sensitive element are formed on the surface of the swinging portion. For example, by forming a piezoresistive element on the surface of the oscillating part, the force (pressure, ultrasonic wave, etc.) acting on the oscillating part from the outside is detected based on the change in resistance value according to the deflection of the oscillating part To do.

  In the first and fifth inventions, the silicon layer is etched from the back side to remove the silicon layer in a concave shape until the insulating film is exposed, and the insulating film facing the space from which the silicon layer has been removed and the insulation By removing a part of the surface film on the film by etching to form an insulating film having a residual stress (residual compressive stress) and a cantilever-like rocking portion (movable structure) made of the surface film, A film that can form a three-dimensional cantilever-like oscillating part that warps on a substrate, and does not require a complicated and special process for preventing sticking and has internal stress (residual tensile stress) There is no need to form a new layer, the manufacturing method can be greatly simplified, and the back surface of the silicon layer has a concave opening. Improve fillability Door can be.

  In the second invention, after the silicon layer is removed, the resin film is applied to the silicon layer and the insulating film facing the space removed in the concave shape, and after the swinging portion is formed, the applied resin film By removing, the swinging portion can be prevented from abruptly warping and the yield can be improved.

  In the third and seventh inventions, a film layer having an internal stress (residual tensile stress) on the upper surface side of the oscillating portion by making the surface film a single crystal silicon film and the insulating film a silicon oxide film. It is possible to easily form an oscillating portion having a three-dimensional structure (a warped structure) without forming.

  In the fourth and eighth inventions, the support layer is removed by bulk micromachining by using an SOI substrate as the substrate, and the active layer (single crystal silicon film) and the buried oxide film layer (silicon oxide film) are used. The oscillating portion having the three-dimensional structure can be formed by a simplified manufacturing process.

  In the sixth aspect of the invention, since the swinging part is configured to be inclined by about 45 degrees toward the outside with respect to the substrate surface, when a pressure sensitive element is provided on the swinging part, Therefore, it is possible to detect the deflection of the swinging portion due to the force acting in the two directions of the parallel direction and the vertical direction substantially evenly. Further, it is possible to efficiently capture the force acting in both the parallel direction and the vertical direction with respect to the substrate surface with one swinging portion.

  In the ninth invention, the force acting on the swinging portion can be detected by including the pressure sensitive element formed on the surface of the swinging portion and the electrode connected to the pressure sensitive element. .

Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments. FIG. 1 is a perspective view showing the structure of a semiconductor device according to the present invention, and FIG. 2 is a cross-sectional view showing the structure of a semiconductor device according to the present invention. A semiconductor device (for example, a micromachine) according to the present invention includes a cantilever 10 having a three-dimensional structure on the surface of an SOI substrate 7 described later. In the figure, reference numeral 1 denotes a silicon substrate (Si). A silicon oxide film (SiO ₂ ) 4 (buried oxide film) is formed on the surface of the silicon substrate (silicon layer) 1. A single crystal silicon film (Si) 3 (silicon active film) is formed on the surface of the silicon oxide film 4. Layer) is formed. A structure in which the single crystal silicon film 3 is formed on the surface of the silicon oxide film 4 on the silicon substrate 1 is referred to as SOI (Silicon on Insulator), and the SOI substrate 7 is formed by the silicon substrate 1, the silicon oxide film 4, and the single crystal silicon film 3. Configure. A silicon oxide film 5 as a protective film is formed on the back surface of the SOI substrate 7.

  The SOI substrate (SOI wafer) 7 is formed by, for example, a method of bonding a silicon substrate (device wafer) on which an oxide film is formed and a substrate (handle wafer) to be transferred, or high-concentration oxygen ions in the silicon substrate. It can be formed by a SIMOX (Separation by Implanted Oxygen) method for forming a buried oxide (BOX) layer by implantation. The SOI substrate 7 has, for example, a wafer diameter of 4 to 6 inches, a single crystal silicon film 3 having a thickness of about 10 nm to 100 μm, a silicon oxide film 4 having a thickness of about 0.2 μm to 4 μm, and a thickness of the silicon substrate 1. Each dimension is about several hundred μm.

  The silicon substrate 1 has a space 1a (recess) formed by removing the silicon substrate 1 in a concave shape by etching from the back surface at a required position. By removing the silicon substrate 1 with a required size, a film layer structure constituted by a two-layer structure of a silicon oxide film 4 exposed facing the space 1a and a single crystal silicon film 3 on the silicon oxide film 4 is formed. By etching from the surface side of the SOI substrate 7 and cutting out a required pattern, a space 1 b communicating with the space 1 a is formed, and an opening made of the spaces 1 a and 1 b is formed in the SOI substrate 7.

  By etching the two-layer structure of the silicon oxide film 4 and the single crystal silicon film 3, a cantilever 10 that is a cantilever swinging portion is formed on the upper surface of the SOI substrate 7. Since the upper surface of the cantilever 10 is formed of the single crystal silicon film 3 having no internal stress, and the lower surface of the cantilever 10 is formed of the silicon oxide film 4 in which compressive stress remains, the residual in the longitudinal direction inside the silicon oxide film 4 is obtained. Due to the compressive stress (arrow in FIG. 2), the cantilever 10 is warped upward with the fixed end 8 as a fulcrum to form a three-dimensional structure.

  The dimension in the longitudinal direction of the cantilever 10 is, for example, about 100 μm to several hundred μm, and the dimension in the width direction is about 10 μm to several tens μm, and the thicknesses of the silicon oxide film 4 and the single crystal silicon film 3 are appropriately set. Accordingly, the cantilever 10 can be obliquely inclined with respect to the surface of the SOI substrate 7 toward the outside of the SOI substrate 7 at an inclination angle of about 45 degrees. For example, the warp of the cantilever 10 is increased by increasing the thickness of the silicon oxide film 4, decreasing the thickness of the single crystal silicon film 3, increasing the longitudinal dimension of the cantilever 10, or decreasing the width dimension of the cantilever 10. The degree of rising (inclination angle) can be increased. Usually, the stress of the thermal oxide film of silicon is about 300 MPa, and the Young's modulus of silicon and the thermal oxide film is about 170 GPa and 72 GPa, respectively, so that the silicon oxide film 4 having a thickness of 0.5 μm (buried oxide film). When the cantilever 10 is manufactured by processing a wafer made of the single crystal silicon film 3 (silicon active layer) having a thickness of 0.5 μm, the radius of curvature becomes about 300 μm. When the cantilever 10 having a length of 500 μm is formed, it is possible to form the cantilever 10 in which the tip of the cantilever 10 rises in a circular arc shape facing directly upward and the height of the tip portion is about 300 μm.

  Thereby, for example, when a piezoresistive element is formed on the surface near the fixed end 8 of the cantilever 10, it is possible to detect a change in resistance value due to the bending of the cantilever 10 (the white arrow in FIG. 2). The cantilever 10 can detect the force acting in two directions, ie, the parallel direction and the vertical direction. Further, the force acting in both the parallel direction and the vertical direction with respect to the surface of the SOI substrate 7 with one cantilever 10 can be efficiently captured. Although not shown, the opening made of the spaces 1a and 1b covers and protects the cantilever 10 and is covered with a flexible resin film for transmitting external pressure. Since the resin can be filled from the back side of the SOI substrate 7, the resin filling property is improved as compared with the case of surface micromachining.

  Next, a method for manufacturing a semiconductor device according to the present invention will be described. 3 and 4 are explanatory views showing a method of manufacturing a semiconductor device according to the present invention. Silicon oxide films 2 and 5 as protective layers are formed in advance on the front and back surfaces of the SOI substrate 7 in which the silicon oxide film 4 and the single crystal silicon film 3 are formed in this order on the surface of the silicon substrate 1 (FIG. 3 (a)).

  A required region of the silicon oxide film 5 on the back surface of the SOI substrate 7 is removed by a photoresist process (FIG. 3B). The region from which the silicon oxide film 5 is removed can be appropriately set depending on the shape, arrangement, number, etc. of the cantilever 10 formed on the surface of the SOI substrate 7. The photoresist process may be either a negative type or a positive type.

Using the remaining silicon oxide film 5 without being removed as an etching mask, for example, reactive ion etching (RIE: Reactive Ion Etching) is used to perform deep digging until the silicon oxide film 4 is exposed from the back surface of the SOI substrate 7. The substrate 1 is removed in a concave shape (FIG. 3C). Accordingly, so-called bulk micromachining is performed on the SOI substrate 7 to form the space 1a. In reactive ion etching, a required gas (for example, SF ₆ ) can be used, and since a high etching rate selection ratio is obtained between silicon (Si) and silicon dioxide (SiO ₂ ), a required shape is obtained. Can be etched. In addition, it can replace with dry etching and can use wet etching, and can also use both together.

  Photoresist 6 is applied to the back surface of SOI substrate 7 from which silicon substrate 1 has been removed and concave space 1a has been formed (FIG. 3D). Thereby, the silicon oxide film 4 exposed by etching is fixed to the photoresist 6.

  By the photoresist process, the silicon oxide film 2 on the surface of the SOI substrate 7 is removed according to a required pattern (FIG. 4E). The pattern for removing the silicon oxide film 2 can be appropriately set depending on the shape, arrangement, number, etc. of the cantilever 10 formed on the surface of the SOI substrate 7. The photoresist process may be either a negative type or a positive type.

  Using the silicon oxide film 2 that remains without being removed as an etching mask, the single crystal silicon film 3 is removed from the surface of the SOI substrate 7 by, for example, reactive ion etching (FIG. 4F). For the etching, for example, a fluorine-based gas can be selectively used.

  The silicon oxide films 2 and 4 on the surface of the SOI substrate 7 are removed by etching to form a space 1b (FIG. 4G). Thereby, a cantilever 10 having a two-layer structure of the single crystal silicon film 3 and the silicon oxide film 4 is formed on the surface of the SOI substrate 7 in a required arrangement. In this state, since the silicon oxide film 4 is fixed to the photoresist 6, it is possible to prevent the cantilever 10 from rapidly warping due to the residual compressive stress of the silicon oxide film 4.

  The photoresist 6 applied to the back surface of the SOI substrate 7 is removed. Since the single crystal silicon film 3 on the upper surface of the cantilever 10 has no internal stress and the silicon oxide film 4 on the lower surface of the cantilever 10 has a compressive stress, the cantilever 10 is fixed by removing the photoresist 6. Warping upwards with the end 8 as a fulcrum (FIG. 4 (h)). In this case, since the photoresist 6 is gradually removed, it is possible to prevent the cantilever 10 from warping rapidly. Thereby, the three-dimensional cantilever 10 can be formed.

  When the cantilever 10 having the three-dimensional structure of the present invention is applied to, for example, a tactile sensor, in the manufacturing method described above, in the vicinity of the fixed end 8 of the cantilever 10 formed on the surface of the SOI substrate 7 (that is, the bending of the cantilever 10). Piezoresistive element is formed at a position where the piezoresistive element can be detected most strongly, for example, by a thermal diffusion process, and an electrode for detecting the resistance value of the piezoresistive element according to the bending of the cantilever 10 is provided. Can be formed in advance at the required position.

  In addition, by covering the SOI substrate 7 on which the cantilever 10 is formed with a flexible resin film, when an object comes into contact with the resin film from the outside, the force transmitted through the resin film from the place where the object contacts the cantilever 10 The contact of the object can be detected with the bending of the cantilever 10 acting as a change in the resistance value of the piezoresistive element.

  FIG. 5 is a schematic plan view showing the structure of an example of the pressure-sensitive sensor 100 according to the present invention. The SOI substrate 7 is formed with an opening 1c having a substantially rectangular planar shape at the center, and cantilevers 10 and 20 in a cross shape facing each other at the center of each edge of the opening 1c on the surface of the SOI substrate 7. 30 and 40 are formed. Each cantilever 10, 20, 30, 40 is inclined toward the outside of the SOI substrate 7 at an inclination angle of about 45 degrees with respect to the surface of the SOI substrate 7.

  Piezoresistive elements 11, 21, 31, 41 are formed on the surface near the fixed end of each cantilever 10, 20, 30, 40, and an electrode (not shown) such as aluminum or copper is formed on the surface of the SOI substrate 7. ) To form wiring patterns 12, 22, 32, 42, and signal processing for calculating the contact of the object and its direction based on the change in resistance value of each piezoresistive element 11, 21, 31, 41. Part 50 is formed. The surface of the SOI substrate 7 is covered with a flexible resin film (not shown).

  By calculating the sum and difference of the signals detected by the deflection of each of the cantilevers 10 and 20, it is possible to detect the force acting in the y direction in the figure and the direction perpendicular to the surface of the SOI substrate 7. By calculating the sum and difference of the signals detected by each of the 40 deflections, it is possible to detect the force acting in the x direction in the figure and the direction perpendicular to the surface of the SOI substrate 7. Thereby, a force in a three-dimensional direction can be detected.

  Further, the pressure-sensitive sensor 100 configured by combining the above-described cantilevers 10, 20, 30, and 40 can be arranged in an array on the surface of the SOI substrate 7 to configure a sensor array.

  As described above, in the present invention, the silicon substrate 1 is removed in a concave shape until the silicon oxide film 4 is exposed by etching from the back side of the SOI substrate 7, and the silicon substrate 1 is removed in the space 1a. The silicon oxide film 4 facing and a part of the single crystal silicon film 3 on the silicon oxide film 4 are removed by etching to form a cantilever-like shape composed of the silicon oxide film 4 and the single crystal silicon film 3 having compressive stress. By forming the cantilever 10, the cantilever 10 warped on the SOI substrate 7 can be formed, and a complicated and special process for preventing sticking is not required, and a film layer having internal stress is newly added. There is no need to form it, and the manufacturing method can be greatly simplified. Further, since the back surface of the SOI substrate 7 is opened in a concave shape, the filling property of the resin for covering the cantilever 10 can be improved.

  Further, after the silicon substrate 1 is removed, a photoresist 6 is applied to the silicon substrate 1 and the silicon oxide film 4 facing the space 1a removed in a concave shape, and after the cantilever 10 is formed, the applied photoresist 6 is applied. By removing the can, the cantilever 10 can be prevented from warping suddenly during formation, and the yield can be improved. Further, by forming the upper surface of the cantilever 10 as the single crystal silicon film 3 and the lower surface as the silicon oxide film 4, a three-dimensional structure (warping structure) can be formed without forming a film layer having internal stress on the upper surface side of the cantilever 10. The formed cantilever 10 can be easily formed.

  Further, by using the SOI substrate 7, the silicon substrate 1 is removed by bulk micromachining, and the three-dimensional cantilever 10 composed of the active layer (single crystal silicon film 3) and the buried oxide film layer (silicon oxide film 4) is simplified. It can be formed by an integrated manufacturing process. Further, the cantilever 10 having a three-dimensional structure is inclined toward the outside of the SOI substrate 7 at an inclination angle of about 45 degrees with respect to the surface of the SOI substrate 7, so that a pressure sensitive element such as the piezoresistive element 11 is provided on the cantilever 10. When formed, the force acting in two directions, ie, parallel and perpendicular to the surface of the SOI substrate 7 can be detected substantially evenly. Further, the force acting in both the parallel direction and the vertical direction with respect to the surface of the SOI substrate 7 with one cantilever 10 can be efficiently captured.

  In the above-described embodiment, the shape, arrangement, number, and the like of the cantilever 10 are examples and are not limited to this.

  In the above-described embodiment, the step of applying the photoresist 6 to fix the silicon oxide film 4 was included. For example, depending on the size and shape of the cantilever 10, the damage at the time of warping is broken. If the possibility is low, the photoresist coating step can be omitted.

  In the above-described embodiment, an example of a contact sensor has been described as the pressure sensor. However, the pressure sensor is not limited to this, and the cantilever 10 of the present invention can be applied to an ultrasonic sensor or the like. it can. The pressure sensitive element is not limited to a piezoresistive element, and a piezoelectric element or the like can also be used.

1 is a perspective view showing a structure of a semiconductor device according to the present invention. It is sectional drawing which shows the structure of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing method of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing method of the semiconductor device which concerns on this invention. It is a plane schematic diagram which shows the structure of an example of the pressure sensitive sensor which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Silicon substrate 1a, 1b Space 1c Opening 2, 5 Silicon oxide film 3 Single crystal silicon film 4 Silicon oxide film 6 Photoresist 7 SOI substrate 8 Fixed end 10, 20, 30, 40 Cantilever 11, 21, 31, 41 Piezo Resistance element

Claims (9)

A method for manufacturing a semiconductor device comprising a cantilever-like swinging portion obliquely provided on a substrate on which a surface layer of an insulating film having a residual stress and a surface film are formed in this order on the surface of a silicon layer,
Etching the silicon layer from the back side and removing the silicon layer in a concave shape until the insulating film is exposed; and
A step of removing a part of the surface film on the insulating film facing the space from which the silicon layer has been removed and the insulating film by etching to form a cantilever-like swinging portion made of the insulating film and the surface film. A method for manufacturing a semiconductor device, comprising: A step of applying a resin film to the silicon layer and the insulating film facing the space removed in a concave shape after removing the silicon layer;
The method for manufacturing a semiconductor device according to claim 1, further comprising: removing the applied resin film after the swinging portion is formed.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the surface film is a single crystal silicon film, and the insulating film is a silicon oxide film.   The method of manufacturing a semiconductor device according to claim 1, wherein the substrate is an SOI substrate. A semiconductor device comprising a cantilever-like rocking portion disposed on a substrate having an insulating film and a surface film formed in this order on the surface of a silicon layer,
The insulating film has a residual stress;
A recess formed on the back surface of the silicon layer so that the insulating film is exposed;
A semiconductor device comprising: an exposed insulating film and a surface film on the insulating film; and a cantilever-like swinging portion obliquely provided on the substrate by the residual stress.   6. The semiconductor device according to claim 5, wherein the oscillating portion is configured to incline approximately 45 degrees toward the outside with respect to the substrate surface.   The semiconductor device according to claim 5, wherein the surface film is a single crystal silicon film, and the insulating film is a silicon oxide film.   The semiconductor device according to claim 5, wherein the substrate is an SOI substrate. A pressure-sensitive sensor comprising the semiconductor device according to any one of claims 5 to 8,
A pressure sensitive element formed on the surface of the swinging portion;
An electrode connected to the pressure sensitive element.

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