JP2010245347A - Method of manufacturing functional device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a functional device, which is superior in mass production without damage of the functional device upon manufacturing, and in which performance can be improved. <P>SOLUTION: The method of manufacturing the functional device 10 includes: a functional thin film 2 formed on one surface side of a silicon substrate (substrate) 1; and a cavity 5 formed on the other surface side of the silicon substrate 1. The method of manufacturing the functional device 10 includes: forming the functional thin film 2 on the one surface side of a silicon wafer (wafer) 3 as a base; forming a separation groove 7 on the one surface side of the silicon wafer 3 along a planned separation region 6 for separating the silicon wafer 3 into a plurality of functional devices 10; forming a metal layer 9 on the other surface side of the silicon wafer 3 except the planned separation region 6 and a cavity formation region 8; and etching the planned separation region 6 and the cavity formation region 8 from the other surface side of the silicon wafer 3 using the metal layer 9 as a mask to form the cavity 5 and to separate the functional devices 10. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  In the present invention, when a functional device is manufactured by separating a functional thin film from a wafer on which a functional thin film is formed, the functional device is free of damage and the like, and is excellent in mass productivity and can improve performance. The present invention relates to a method for manufacturing a conductive device.

  Conventionally, a functional device comprising a functional thin film formed on one surface side of a substrate and having a cavity formed in the substrate for spatially separating a part of the functional thin film from the substrate is a thermal device. Infrared sensors and various MEMS (Micro Electro Mechanical Systems) devices (for example, acceleration sensors, gyro sensors, ultrasonic sensors, micro valves, etc.) are known. In manufacturing such a functional device, using a micromachining technology or the like, after forming a large number of functional devices having a functional thin film on one surface side of the wafer serving as the base of the substrate, A plurality of functional devices are separated from the wafer.

  Here, when separating from a wafer into a plurality of functional devices, it is common to perform dicing using a dicer that cuts the wafer into a lattice while rotating a blade holding diamond abrasive grains with a binder at high speed. In order to remove wafer chips and to cool the blade, pure water is sprayed.

  However, functional devices with cavities that spatially separate a part of the functional thin film from the substrate are structurally fragile compared to other electronic devices such as ICs and LSIs and are purely used during dicing. Damage may occur due to water pressure. Therefore, in the method for manufacturing the functional device shown in FIG. 8, a large number of functional devices having a functional thin film are formed on one surface side of the wafer 3 ′ serving as the base of the substrate, and the wafer 3 ′ is increased in order to increase the strength of the wafer 3 ′. A separate wafer 80 is bonded to each functional thin film via a gap on the one surface side of 'and sealed to protect. Then, the wafer 80 is diced at each dicing portion 6'a for each functional thin film to form a protective cap for protecting the functional thin film, and then the wafer 3 serving as the basis of the substrate for each functional device. It has been proposed to manufacture a functional device by dicing 'in the planned separation region 6' (see, for example, Patent Document 1).

  In FIG. 8, the wafer 80 serving as the base of the protective cap is provided with leg portions 83 protruding from the one surface side of the wafer 3 ′ so as to surround the functional thin films in plan view in order to form the gap. It has been. A bonding layer 81 is provided on the leg portion 83 of the wafer 80, and the bonding layer 81 of the wafer 80 and the bonding frame 82 provided on the one surface side of the wafer 3 'are bonded by a eutectic reaction.

  By the way, in the manufacturing method of the functional device described in the above-mentioned patent document 1, the wafer 80 that is the basis of the protective cap that protects the functional thin film at the time of dicing is bonded to one surface side of the wafer 3 ′ that is the basis of the substrate. There is a problem that a process is required and the manufacturing cost increases. Further, in the formed functional device, the functional thin film is hermetically sealed with a protective cap, so that unnecessary organic substances may remain inside the hermetically sealed functional device.

  In this case, the function of the functional device may deteriorate due to degassing released from unnecessary organic substances. Furthermore, when an infrared sensor is formed as a functional device, it may be difficult to improve the characteristics of the infrared sensor because the protective cap absorbs infrared rays.

  In addition, instead of separating a plurality of functional devices from a wafer by dicing using a dicer, it has been proposed to separate a plurality of functional devices from a wafer by etching. Specifically, as shown in FIG. 9, a functional thin film 2 ′ is formed on one surface side of the wafer serving as the basis of the substrate 1, and separation is performed for separating into a plurality of functional devices on the other surface side of the wafer. A mask 9 ′ is formed except for the predetermined region 6 and a cavity forming region 8 ′ for forming a cavity 5 ′ for reducing the thickness of the substrate below the functional thin film 2 ′, and the other surface side of the wafer is formed. A technique has been proposed in which a functional device having a cavity 5 ′ on the other surface side of the substrate 1 is separated from the wafer by etching the planned separation region 6 and the cavity forming region 8 ′ from the wafer ( For example, see Patent Document 2).

  In FIG. 9, prior to etching the wafer from the other surface side of the wafer serving as the base of the substrate 1, the functional device is previously placed on the one surface side of the wafer serving as the base of the substrate 1. And a resist layer 11 ′ for protecting the functional thin film 2 ′ are formed.

JP-A-8-316497 JP-A-9-27465

  However, in separating the mask 9 ′ used for etching from the substrate 1, it may not always be easy to remove the mask 9 ′. In this case, if the peeling of the mask 9 ′ used for separating the plurality of functional devices from the wafer by etching is not sufficient, the components of the mask 9 ′ may remain on the other surface of the functional device. . The remaining material of the mask 9 'impairs the smoothness of the other surface side of the substrate 1 of the functional device. Further, if the mask 9 ′ is sufficiently peeled from the other surface side of the substrate 1 of the functional device, the other surface side of the functional device may be damaged and the smoothness of the other surface side may be impaired. is there.

  When the smoothness on the other surface side of the substrate 1 of such a functional device is impaired, when the functional device is mounted on the mounting substrate side later, the functional device is increased in a direction perpendicular to the mounting surface of the mounting substrate. It is difficult to mount with accuracy. For this reason, the characteristics of the functional device may deteriorate.

  In particular, when a functional device having a cavity that spatially separates a part of the functional thin film from the substrate is formed on the other surface side of the substrate, the depth of etching the wafer serving as the base of the substrate is deep and the mask is thick and strong. Need to be formed. Therefore, it tends to be difficult to form a smooth surface without damage on the other surface side of the substrate.

  Therefore, in such a functional device, it is difficult to mount it on a mounting substrate with high accuracy, and the function of the functional device may not be sufficiently exhibited.

  The present invention has been made in view of the above-mentioned reasons, and the purpose thereof is a functional device that can be a functional device that is excellent in mass productivity and can improve performance without breakage of the functional device during manufacturing. It is in providing the manufacturing method of.

  According to the first aspect of the present invention, a substrate, a functional thin film formed on one surface side of the substrate, and a part of the functional thin film formed on the other surface side of the substrate are spatially separated from the substrate. A method of manufacturing a functional device comprising: a thin film forming step of forming the functional thin film on one surface side of a wafer serving as a base of the substrate; and a plurality of functional devices from the wafer. A separation groove forming step for forming a separation groove on the one surface side of the wafer along a predetermined separation region for separation, and a cavity formation for forming at least the separation region and the cavity on the other surface side of the wafer A metal layer forming step of forming a metal layer for bonding the separated functional device to a mounting substrate except for the region, and the region to be separated from the other surface side of the wafer using the metal layer as a mask. Yo And having a separation step of separating the functional device from the wafer to form the said cavity by etching the cavity forming region.

  According to the present invention, the metal layer capable of bonding the functional device to the mounting substrate when the functional device is mounted on the mounting substrate is formed by forming the cavity in the functional device and the functionality from the wafer. Since it is used as a mask at the time of etching for separating the device, it is possible to provide a method for manufacturing a functional device that is excellent in mass productivity and can improve performance without breakage of the functional device during manufacturing.

  The invention of claim 2 has a sheet sticking step of sticking a temporary fixing sheet to the one surface side of the wafer after the separation groove forming step and before the metal layer forming step in the invention of claim 1. It is characterized by that.

  According to the present invention, the plurality of functional devices separated from the wafer by the separation step are temporarily fixed to the temporary fixing sheet, and therefore do not fall apart.

  The invention of claim 3 has a sheet sticking step of sticking a temporary fixing sheet to the one surface side of the wafer after the metal layer forming step and before the separating step in the invention of claim 1. Features.

  According to the present invention, the plurality of functional devices separated from the wafer by the separation step are temporarily fixed to the temporary fixing sheet, and therefore do not fall apart.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, in the separation step, the outer peripheral portion of the wafer in a plan view is left in a ring shape, and a plurality of functionalities are provided. It is characterized by separating the devices.

  According to the present invention, unnecessary peripheral portions of the wafer can be collectively separated from a plurality of functional devices, and the functional devices can be manufactured with high mass productivity. In addition, separation can be performed without using a jig such as a flat ring that is usually used when dicing with a dicer or the like.

  In the invention of claim 1, a functional thin film formed on one surface side of the substrate, and a cavity formed on the other surface side of the substrate and spatially separating a part of the functional thin film from the substrate, When the functional device is provided, the separated functional device is bonded to the mounting substrate except for at least a predetermined separation region and a cavity forming region that forms a cavity on the other surface side of the wafer serving as a base of the substrate. Forming a metal layer for etching and etching the planned separation region and the cavity forming region from the other surface side of the wafer using the metal layer as a mask to form the cavity and the functional device to the wafer Is separated from Thereby, there is a remarkable effect that it is possible to provide a method for manufacturing a functional device that is excellent in mass productivity and capable of improving performance without being damaged in the functional device.

It is a schematic process sectional drawing of the manufacturing method of the functional device of embodiment. The infrared array sensor as a functional device shown above is shown, (a) is a schematic plan view, (b) is an equivalent circuit diagram. The thermal infrared detection part which comprises a part of infrared array sensor shown above is shown, (a) is the schematic plan view, (b) is the A-A 'schematic sectional drawing. It is a typical top view of the wafer in which the infrared array sensor same as the above was formed. It is a typical top view of a semiconductor device carrying an infrared array sensor same as the above. It is function explanatory drawing of a semiconductor device same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of the semiconductor device carrying an infrared array sensor same as the above. It is a schematic sectional drawing for demonstrating the manufacturing method of the conventional functional device. It is a schematic sectional drawing for demonstrating the manufacturing method of the conventional functional device.

(Embodiment 1)
In the present embodiment, an infrared array sensor will be described as a functional device with reference to FIG. 2, and a thermal infrared detector constituting the infrared array sensor will be described with reference to FIG. Moreover, the manufacturing method of the functional device used as an infrared array sensor is demonstrated based on FIG.

  The infrared array sensor 32 of FIG. 2 is used for an infrared image sensor or the like. FIG. 2A shows m × n (2 × 2 in the illustrated example) thermal infrared detectors 30. They are arranged in a two-dimensional array. In FIG. 2 (b), an equivalent circuit is shown as a voltage source corresponding to the thermoelectromotive force of the thermocouple type sensing element (temperature sensing unit) 20 in the thermal infrared detector 30.

  When the thermal infrared detector 30 constituting the infrared array sensor 32 is enlarged, the configuration shown in FIG. 3A is obtained, and a cross-sectional view taken along the line A-A 'of FIG. 3A is shown in FIG. In FIG. 3B, a silicon oxide film 11 formed on one surface side of the silicon substrate 1 which is a substrate, a silicon nitride film 12 formed on the silicon oxide film 11, and a silicon nitride film 12 are formed. The laminated structure of the sensing element 20 formed, the interlayer insulating film 17 formed so as to cover the sensing element 20 on the surface side of the silicon nitride film 12, and the passivation film 19 formed on the interlayer insulating film 17 is patterned. Thus, the functional thin film 2 is formed.

  Here, a part of the functional thin film 2 is spatially separated from the silicon substrate 1 by a cavity 5 formed from the other surface side of the silicon substrate 1, and a slit 4 communicating with the cavity 5 is formed in the functional thin film 2. It penetrates in the thickness direction. In addition, a metal layer 9 is provided on the other surface of the silicon substrate 1 so that the infrared array sensor 32 can be bonded to a package side serving as a mounting substrate described later. A portion of the functional thin film 2 that is spatially separated from the silicon substrate 1 by the cavity 5 constitutes an infrared absorbing portion 21 that absorbs infrared rays.

  The thermal infrared detecting unit 30 includes the interlayer insulating film 17 made of a BPSG (Boro-PhosphoSilicate Glass) film, and the passivation film 19 as a PSG (Phospho Silicate Glass) film and an NSG (Non-doped Silicate Glass) on the PSG film. The laminated film of the interlayer insulating film 17 and the passivation film 19 also serves as the infrared absorption film 22.

  Here, when the refractive index of the infrared absorption film 22 is n and the center wavelength of the infrared ray to be detected is λ, and the thickness t of the infrared absorption film 22 is set to λ / 4n, the wavelength of the detection target (for example, 8 The absorption efficiency of infrared rays (˜12 μm) can be increased, and high sensitivity can be achieved. For example, when n = 1.4 and λ = 10 μm, t≈1.8 μm may be set, the interlayer insulating film 17 has a thickness of 0.8 μm, the PSG film has a thickness of 0.5 μm, and the NSG film The film thickness is 0.5 μm. Note that the passivation film 19 is not limited to the stacked film of the PSG film and the NSG film, and may be formed of, for example, a silicon nitride film.

  As shown in FIG. 3A, the sensing element 20 includes the p-type polysilicon layer 15, the n-type polysilicon layer 13, and the infrared incident portion 21, which are formed across the infrared absorbing portion 21 and the silicon substrate 1. A thermopile composed of a connecting portion 23 made of a metal material (for example, Al—Si) in which one end portion of the p-type polysilicon layer 15 and one end portion of the n-type polysilicon layer 13 are electrically joined on the surface side. I have.

  Here, the thermopile constituting the sensing element 20 has the other end of the p-type polysilicon layer 15 and the other end of the n-type polysilicon layer 13 of the thermocouple adjacent to each other on one surface side of the silicon substrate 1. Four pieces are connected in series by being joined by a wiring 18 made of a metal material (for example, Al—Si). In the thermopile, one end portion of the n-type polysilicon layer 13, one end portion of the p-type polysilicon layer 15, and the connection portion 23 constitute a hot junction on the infrared absorption portion 21 side, and the other end of the p-type polysilicon layer 15. This part, the other end of the n-type polysilicon layer 13 and the wiring 18 form a cold junction on the silicon substrate 1 side.

  The connection portion 23 formed of a metal material is electrically connected to the n-type polysilicon layer 13 and the p-type polysilicon layer 15 through contact holes 25 formed in the interlayer insulating film 17. .

  In addition, the infrared array sensor 32 of the present embodiment has a plurality (four in the illustrated example) in which one end of the sensing element 20 in each thermal infrared detector 30 is individually connected as shown in FIG. The output pad 24 (Vout-1, Vout-2, Vout-3, Vout-4) and one reference bias pad 26 (the other end of the sensing element 20 in the thermal infrared detector 30 are commonly connected) Vref) so that the outputs of all the thermal infrared detectors 30 can be read in time series.

  The sensing element 20 has one end electrically connected to the output pad 24 through the vertical readout line 27 and the other end connected to the reference bias line 29 connected to the reference bias pad 26. It is electrically connected via. Here, for example, if the potential of the reference bias pad 26 (Vref) is set to 1.65 V, the output pad 24 (Vout-1, Vout-2, Vout-3, Vout-4) is connected to the pixel A. The output voltage (1.65 V + the output voltage of the sensing element 20) of the thermal infrared detector 30 can be read out.

  Slits 4 penetrating in the thickness direction of the functional thin film 2 are formed by etching from the one surface side of the silicon substrate 1 at the four corners of the rectangular region serving as the infrared absorbing portion 21. The slit 4 can thermally separate the thermocouples and improve the sensor sensitivity of the thermal infrared detector 30. Note that the shape of the slit 4 is not limited to a rectangle, but can be variously selected as desired, such as a triangle, an ellipse, and a circle.

  Further, the cavity 5 formed on the other surface side of the silicon substrate 1 can thermally separate the functional thin film 2 from the silicon substrate 1 side to improve the sensitivity of the thermal infrared detector 30. . For example, the cavity 5 is formed by forming a slit 4 on the one surface side of the functional thin film 2 and then performing deep reactive ion etching (hereinafter referred to as deep reactive ion etching) using the metal layer 9 as an etching mask from the other surface side of the silicon substrate 1. , DRIE) and anisotropic etching using a method.

  The shape of the cavity 5 viewed from the other surface side of the silicon substrate 1 can be formed by selecting variously as desired, such as a triangle, an ellipse, and a circle in addition to a rectangle. Furthermore, in this embodiment, the n-type compensating polysilicon layer 14 and the p-type that are not electrically connected to the infrared incident surface side of the infrared absorbing portion 21 when the n-type polysilicon layer 13 and the p-type polysilicon layer 15 are patterned. The compensation polysilicon layer 16 is left. Such n-type compensation polysilicon layer 14 and p-type compensation polysilicon layer 16 can enhance the uniformity of stress balance in the functional thin film 2. In addition, the n-type compensation polysilicon layer 14 and the p-type compensation polysilicon layer 16 can prevent warpage while reducing the thickness of the functional thin film 2 and can improve the sensor sensitivity of the thermal infrared detector 30. . The thickness of the functional thin film 2 laminated in this way is sufficiently thinner than the thickness of the silicon substrate 1. The thickness of the functional thin film 2 is not limited to the thickness of the functional thin film 2 constituted by the infrared absorption film 22 or the like described above, and may be, for example, about 0.1 μm to 10 μm.

  Hereinafter, the manufacturing method of the functional device used as the above-mentioned infrared array sensor 32 is demonstrated based on FIG. 1 and FIG.

  First, the silicon wafer 3 which is the wafer serving as the base of the silicon substrate 1 which is the substrate is cleaned, and each thin film which becomes the above-described functional thin film 2 on one surface side of the silicon wafer 3 is formed by a CVD method, a photolithography technique, It forms sequentially using an etching technique. Subsequently, separation is performed in the thickness direction of the functional thin film 2 from the one surface side of the silicon wafer 3 along the planned separation region 6 for separating the plurality of functional devices 10 from the silicon wafer 3 by photolithography technology and etching technology. A separation groove forming step for forming the grooves 7 is performed.

  Here, the above-described slit 4 can be formed. That is, the slit 4 may be formed simultaneously by etching the one surface side of the silicon wafer 3 simultaneously with the separation groove 7 in order to improve mass productivity, or the slit 4 in order to improve the shape controllability by etching. 4 and the separation groove 7 may be formed in separate steps. The separation groove 7 formed on the one surface side of the silicon wafer 3 is formed leaving the outer peripheral portion of the silicon wafer 3 in a ring shape in plan view.

  Next, using Cr as a target material, a Cr film is formed by sputtering on the entire surface of the silicon wafer 3 on the other surface side opposite to the one surface side on which the functional thin film 2 is formed. Subsequently, the target material is changed from the metal Cr to the metal Au, and an Au film is formed on the entire surface of the Cr film formed on the other surface side of the silicon wafer 3 by a sputtering method. As a result, a metal laminate composed of the Cr film and the Au film on the Cr film is formed on the entire surface on the other surface side opposite to the one surface side on which the functional thin film 2 is formed in the silicon wafer 3. A film is formed.

  Subsequently, on the other surface side of the silicon wafer 3, at least a planned separation region 6 for separating the plurality of functional devices 10 from the silicon wafer 3 and a part of the functional thin film 2 are spaced from the silicon substrate 1. The metal laminated film corresponding to the cavity forming region 8 for forming the cavity 5 for the purpose of separation is removed by a photolithography technique and an etching technique. Thereby, the separated functional device 10 is bonded to the package side which is a mounting substrate described later, except for the cavity forming region 8 which forms at least the planned separation region 6 and the cavity 5 on the other surface side of the silicon wafer 3. A metal layer forming step for forming the metal layer 9 can be performed. In this way, the metal layer 9 is formed on the entire surface of the silicon wafer 3 on the other surface side so that the metal layer 9 is formed with a substantially uniform thickness on the other surface of the silicon substrate 1 in the functional device 10. can do.

  In addition, prior to forming the metal laminated film, when a through-wiring that can be connected to the functional thin film 2 side from the other surface side of the silicon wafer 3 is provided in advance, the metal layer 9 is a silicon substrate. It can function as an electrode for taking out the output from the functional thin film 2 to the outside through the through wiring penetrating in 1 (not shown).

  Next, a resist film 11 is applied and formed on the one surface side of the silicon wafer 3 on which the functional thin film 2 is formed. The resist film 11 is suitably provided in order to increase the mechanical strength of the functional thin film 2 and protect the functional thin film 2 when the functional device 10 is manufactured, and is not necessarily required.

  Subsequently, a sheet sticking process is performed in which the temporary fixing sheet 12 is attached to the one surface side of the silicon wafer 3 via the resist film 11 (FIG. 1A).

  Here, the temporarily fixing sheet 12 prevents a plurality of functional devices 10 separated from the silicon wafer 3 from falling apart, and the plurality of separated functional devices 10 are temporarily fixed sheets. 12, the functional device 10 can be easily peeled without being damaged. Specifically, as the temporary fixing sheet 12, a sheet in which a pressure-sensitive adhesive is coated on a base material such as plastic or polyester having a thickness of about 1 to 500 μm can be suitably used. As the temporary fixing sheet 12, an ultraviolet peelable pressure-sensitive adhesive sheet whose adhesive strength is reduced by irradiating with ultraviolet light, a water-soluble peelable pressure sensitive adhesive sheet whose adhesive strength is reduced by being immersed in an aqueous solution, or heat release whose adhesive strength is reduced by heating A mold pressure-sensitive adhesive sheet can be suitably used.

  In the case where a plurality of separated functional devices 10 are peeled from the temporarily fixed sheet 12 in a short time, in order to reduce the adhesive force of the temporarily fixed sheet 12 in view of mass productivity, it is more than the water-soluble peelable adhesive sheet. The heat peelable pressure sensitive adhesive sheet or the ultraviolet light peelable pressure sensitive adhesive sheet is more preferable. Further, the heat-peelable pressure-sensitive adhesive sheet is more preferable than the UV-peelable pressure-sensitive adhesive sheet from the viewpoint of having less residual adhesive force and being easily peelable without damaging the functional thin film 2.

  Such a heat-peelable pressure-sensitive adhesive sheet includes the pressure-sensitive adhesive containing thermally expandable fine particles (for example, rubber-based pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, vinyl alkyl ether-based pressure-sensitive adhesive, silicone-based pressure-sensitive adhesive, polyester-based pressure-sensitive adhesive). , Polyamide-based adhesive, urethane-based adhesive, fluorine-based adhesive, etc.) can be applied to a substrate such as polyester and used as a sheet having an adhesive layer. Examples of the thermally expandable fine particles include microcapsules in which a substance that easily expands by gasification by heating, such as isobutane, propane, or pentane, is encapsulated in an elastic shell.

  Next, using the metal layer 9 formed excluding the scheduled separation region 6 and the cavity forming region 8 on the other surface side of the silicon wafer 3 as a mask, the silicon wafer 3 is scheduled to be separated from the other surface side using the DRIE method. The region 6 and the cavity forming region 8 are anisotropically etched. By this anisotropic etching, a cavity 5 for spatially separating a part of the functional thin film 2 in the functional device 10 from the silicon substrate 1 is formed, and a separation process for separating the functional device 10 from the silicon wafer 3 is performed. (FIG. 1 (b)).

  In the present embodiment, even after the separation step, the one surface side of the plurality of functional devices 10 is individually fixed to the temporarily fixing sheet 12 via the resist film 11. The functional device 10 can be manufactured without the individual functional devices 10 falling apart.

  Further, as shown in FIG. 4, the outer peripheral portion 41 of the silicon wafer 3 in a plan view is left in a ring shape by the separation process of separating the plurality of functional devices 10 from the silicon wafer 3. As a result, the outer peripheral portion 41 of the unnecessary wafer can be separated at once from the plurality of manufactured functional devices 10, and the functional device 10 can be manufactured with high mass productivity. In addition, a plurality of functional devices 10 can be separated from the silicon wafer 3 without using a jig such as a flat ring that is usually used when dicing with a dicer or the like. Note that the ring shape of the outer peripheral portion 41 is not limited to a complete ring but may be a partially opened shape if there is no problem such as a large reduction in mass productivity in the production of the functional device 10.

  Next, the plurality of functional devices 10 separated from the silicon wafer 3 are peeled from the temporary fixing sheet 12. In this peeling step, in order to remove each of the plurality of functional devices 10 from the temporary fixing sheet 12 side, an ultraviolet irradiation process, an injection process into an aqueous solution, a heating process, or the like may be performed according to the characteristics of the temporary fixing sheet 12. For example, when a heat-peelable pressure-sensitive adhesive sheet is used as the temporary fixing sheet 12, the temporary fixing sheet 12 may be heated by a hot air dryer, a hot plate, a near infrared lamp, or the like.

  By heating, the heat-expandable fine particles contained in the pressure-sensitive adhesive of the heat-peelable pressure-sensitive adhesive sheet swell greatly, thereby producing minute irregularities on the surface of the pressure-sensitive adhesive layer, and the temporary fixing sheet 12 and each functional device 10 face each other. It changes from a relatively strong bond bonded at point to a point bond. As a result, the adhesion area of the temporary fixing sheet 12 is reduced and the adhesive force is greatly reduced. The temporary fixing sheet 12 can be peeled relatively easily from the one surface side of the functional device 10 without destroying the functional device 10.

  Subsequently, the functional device 10 can be formed by removing the resist film 11 formed on the one surface side of the functional device 10 by an ashing process (FIG. 1C).

  As a method for removing the resist film 11 by ashing, the resist film 11 can be removed by exposing the resist film 11 to ozone generated by irradiating oxygen gas with ultraviolet rays or high-frequency microwaves. As a result, not only the resist film 11 but also unnecessary organic substances attached to the side walls of the separation grooves 7 and the cavities 5 in the slits 4 on the surface of the functional device 10 can be removed by decomposition surface desorption. . Further, after mounting the functional device 10 on a package which is a mounting substrate described later, the resist film 11 may be removed by an ashing process.

  The functional device 10 manufactured by such a method has little damage to the functional device 10, and the functional device 10 having the metal layer 9 capable of bonding the functional device 10 to the package side has high productivity. Can be manufactured.

  Instead of attaching the temporary fixing sheet 12 to the one surface side of the silicon wafer 3 after the separation groove forming step and before the metal layer forming step, the separation step is performed after the metal layer forming step. Before that, a sheet sticking step of sticking the temporary fixing sheet 12 to the one surface side of the silicon wafer 3 may be performed. Even in this case, since the plurality of functional devices 10 separated from the silicon wafer 3 by the separation step are temporarily fixed to the temporary fixing sheet 12, they do not fall apart.

  Next, an example in which a semiconductor device is configured using the functional device 10 formed in the above process will be described with reference to FIG. 5, and the function of the semiconductor device will be described with reference to FIG.

  As shown in the plan view of FIG. 5, the semiconductor device 50 includes an infrared array sensor 32 having the four thermal infrared detectors 30 described above, and an infrared array sensor 32 formed separately from the infrared array sensor 32. The cooperating signal processing IC chip 33 is fixedly arranged on the inner bottom surface side of the recess of the package 36.

  The output pad 24 and the reference bias pad 26 of the infrared array sensor 32 and the input pad 31 of the signal processing IC chip 33 are wire-bonded with a wire (for example, a gold wire or an aluminum wire). In order to efficiently connect the wires 35 by the wire bonding apparatus, the output pads 24 and the reference bias pads 26 are arranged on one side of the infrared array sensor 32 having a rectangular shape in plan view, and similarly infrared rays are used. Each input pad 31 is arranged on one side of the signal processing IC chip 33 facing the side where the output pads 24 and the like of the array sensor 32 are arranged. Thus, when the input pad 31 of the signal processing IC chip 33 is disposed adjacent to the output pad 24 of the infrared array sensor 32, the wiring length of the wire 35 can be shortened, and the influence of noise is reduced. The semiconductor device 50 which is not easily received and has high sensor sensitivity can be obtained.

  In the signal processing IC chip 33, as shown in FIG. 6, each output pad 24 (Vout-1, Vout-2, Vout-3, Vout-4) of the infrared array sensor 32 and a reference bias pad 26 (Vref). Is received by each input pad 31 (Vin-1, Vin-2, Vin-3, Vin-4) on the signal processing IC chip 33 side. The signal processing IC chip 33 selectively outputs each output power in each thermal infrared detection unit 30 of the infrared array sensor 32 as one signal sequentially by a multiplexer (hereinafter referred to as MUX), and an amplifier circuit ( The signal can be amplified by an amplifier (hereinafter referred to as AMP).

  Next, a manufacturing process for manufacturing the semiconductor device 50 of the present embodiment will be described with reference to FIG.

  As shown in FIG. 7B, the semiconductor device 50 has a recess and a package 36 in which the infrared array sensor 32 and the signal processing IC 33 are mounted on the inner bottom surface 36a side of the recess, and infrared rays are incident on the infrared array sensor 32. A lid 51 that includes a lens-shaped cap 52 and hermetically seals the concave portion of the package 36.

  More specifically, the package 36 used in the semiconductor device 50 can be formed of a ceramic material or the like, in which the infrared array sensor 32 and the signal processing IC 33 can be disposed on the inner bottom surface 36a of the recess. A metal film 37 (for example, an Au film) functioning as an electromagnetic shield is formed on the inner wall of the recess of the package 36 so that unnecessary infrared light incident from the outside of the package 36 does not become noise of the infrared array sensor 32. Yes.

  Further, a part of the metal film 37 is notched on the inner bottom surface 36 a side of the recess of the package 36, and a part of the metal film 37 is a metal pattern for joining with the metal layer 9 of the infrared array sensor 32. It is formed to function as (not shown). Further, another part of the metal pattern formed by cutting out the metal film 37 can also function as an electrode for electrical connection with the signal processing IC 33. And the signal processing IC 33 are electrically connected by a wire 35.

  The infrared array sensor 32 and the signal processing IC 33 are electrically connected via a wire 35. The metal pattern is electrically connected to external electrodes 38, 38 provided outside the package 36 through through electrodes (not shown) provided in the package 36.

  In order to manufacture such a semiconductor device 50, the metal layer 9 of the infrared array sensor 32 is aligned and placed on the metal pattern previously formed on the inner bottom surface 36a of the recess of the package 36 in a vacuum chamber. And heat while pressing. Thus, the infrared array sensor 32 can be mounted on the package 36 by diffusion bonding the metal layer 9 of the infrared array sensor 32 and the metal pattern formed on the inner bottom surface 36 a of the recess of the package 36. .

  More specifically, in the infrared array sensor 32, the metal layer 9 provided on the infrared array sensor 32 with the Au film as the outermost surface is provided in advance on the package 36 in a vacuum chamber filled with an argon atmosphere as an inert gas. The provided at least surface is aligned and arranged on the metal pattern made of Au. The arranged infrared array sensor 32 is heated at a temperature of 300 ° C. to 400 ° C. while being pressed against the inner bottom surface 36 a side of the recess of the package 36. Thus, the metal layer 9 of the infrared array sensor 32 and the metal pattern provided on the inner bottom surface 36a of the recess of the package 36 are directly bonded and fixed by AuAu diffusion bonding (FIG. 7A). ).

  Here, diffusion bonding is a method in which the base material is brought into close contact with the base material at a temperature equal to or lower than the melting point of the base material and pressed to the extent that plastic deformation does not occur as much as possible, and is joined using diffusion of atoms generated between the joint surfaces. is there. Therefore, unlike mounting using an adhesive such as solder or resin, it can be bonded as it is, so that it can be bonded with good controllability. When diffusion bonding is used for mounting the semiconductor device 50, the infrared array sensor 32 is perpendicular to the inner bottom surface 36 a of the recess of the package 36 on the metal pattern provided on the inner bottom surface 36 a of the recess of the package 36. It is possible to mount without substantially changing the positional relationship between directions before and after joining.

  In diffusion bonding, bonding may be performed at normal temperature (for example, 25 ° C.) according to the material to be bonded, or may be bonded while heating. When diffusion bonding is performed at room temperature, for example, the bonding surfaces may be activated by irradiating the bonding surfaces with argon plasma, an ion beam or an atomic beam in vacuum to activate the bonding surfaces, and then bonding the bonding surfaces to each other. . Such diffusion bonding at room temperature is more preferable in that stress is relaxed when the infrared array sensor 32 and the package 36 are directly bonded. It is more preferable to provide an activation process for cleaning the surface of the inner side of the recess of the package 36 prior to diffusion bonding in order to improve the bonding strength between the infrared array sensor 32 and the package 36.

In order to join the metal layer 9 of the infrared array sensor 32 to the package 36 side, anodic bonding can be used instead of diffusion bonding. In this case, for example, the outermost surface of the metal layer 9 of the infrared array sensor 32 is formed of a Cr film as an active metal highly reactive with oxygen, and the metal layer 9 is formed on the inner bottom surface 36 a of the recess of the package 36. instead of joining the metal pattern, the metal layer 9 aluminosilicate inner bottom 36a side of the concave portion of the package 36 made of the glass composition of _{(Na 2 O-Al 2 O} 3 -Ba 2 O 3 -SiO 2 system) It is sufficient to join directly.

  Next, the signal processing IC chip 33 is provided with an adhesive layer 39 (for example, glass, AuSi, or solder. An epoxy resin can be suitably used as long as it is an organic material, but an inorganic material is more preferable). The package 36 is adhered to the inner bottom surface 36a side of the recess. Specifically, the package 36 and the back surface of the signal processing IC chip 33 are bonded by solder. The signal processing IC chip 33 is diffusion bonded to the inner bottom surface 36a side of the recess of the package 36 in the same manner as the infrared array sensor 32, instead of being mounted on the inner bottom surface 36a side of the recess of the package 36 by the adhesive layer 39. Alternatively, it may be mounted by anodic bonding.

  Subsequently, each output pad 24 and reference bias pad 26 of the infrared array sensor 32 and each input pad 31 of the signal processing IC chip 33 are individually wire-bonded by wires 35 to be electrically connected. .

  In the semiconductor device 50 according to the present embodiment, the package 36 diffuses and bonds the metal layer 9 of the infrared array sensor 32 to the metal pattern provided on the inner bottom surface 36 a of the recess of the package 36, and then the infrared array sensor 32. In order not to lower the sensor sensitivity, ashing is performed to remove unnecessary organic substances generated in the manufacturing process. The signal processing IC chip 33 may remove unnecessary organic substances simultaneously with the infrared array sensor 32 and the package 36, or may separately remove unnecessary organic substances.

  Such an ashing process for removing unnecessary organic substances can be applied as needed depending on the size, number, and materials used of the infrared array sensor 32 and the signal processing IC chip 33 disposed in the package 36. For example, an ozone ashing device or a plasma ashing device can be used as photoexcited ashing.

  Next, a lid made of a metal (for example, Kovar metal) having an opening in advance is used as the lid 51, and a cap 52 having a lens shape made of silicon is hermetically bonded to the opening of the lid 51 using low melting point glass or the like. The prepared one is prepared for hermetic sealing of the package 36. A bonding metal film for bonding to the lid 51 is formed in advance on the upper end portion of the recess of the package 36, and the bonding metal film and the lid 51 are subjected to seam welding in a vacuum chamber. Thereby, the semiconductor device 50 in which the inside of the concave portion of the package 36 is hermetically sealed with the lid 51 having the lens-shaped cap 52 can be formed (FIG. 7B).

  When driving the semiconductor device 50 thus formed, for example, when 1.65 V is applied as the reference voltage, the voltage generated in each thermal infrared detector 30 is added to the reference voltage on the output pad 24 side. Each is output. The output of the infrared array sensor 32 is obtained by sequentially switching the output signal for each thermal infrared detector 30 using the MUX of the signal processing IC chip 33 and amplifying it by the AMP of the signal processing IC chip 33. Can do.

  In the present embodiment, the infrared array sensor 32 is exemplified as the functional device 10, but in addition to this, a one-axis acceleration sensor, a two-axis acceleration sensor, a three-axis acceleration sensor, a gyro sensor, a pressure sensor, a microactuator, a microphone, a super It can also be used for sonic sensors.

1 Silicon substrate (substrate)
2 Functional thin film 3 Silicon wafer (wafer)
5 Cavity 6 Separation Planned Area 7 Separation Groove 8 Cavity Formation Area 9 Metal Layer 10 Functional Device

Claims (4)

A function comprising: a substrate; a functional thin film formed on one surface side of the substrate; and a cavity formed on the other surface side of the substrate to spatially separate a part of the functional thin film from the substrate. A method for manufacturing a functional device, comprising:
A thin film forming step of forming the functional thin film on one surface side of the wafer serving as a base of the substrate;
A separation groove forming step of forming a separation groove on the one surface side of the wafer along a separation planned region for separating a plurality of functional devices from the wafer;
A metal layer forming step for forming a metal layer for bonding the separated functional device to a mounting substrate, excluding at least the planned separation region and the cavity forming region for forming the cavity on the other surface side of the wafer; ,
And separating the functional device from the wafer while forming the cavity by etching the separation region and the cavity formation region from the other surface side of the wafer using the metal layer as a mask. The manufacturing method of the functional device characterized by the above-mentioned.   2. The functional device according to claim 1, further comprising a sheet attaching step of attaching a temporary fixing sheet to the one surface side of the wafer after the separation groove forming step and before the metal layer forming step. Manufacturing method.   The functional device manufacturing according to claim 1, further comprising a sheet attaching step of attaching a temporary fixing sheet to the one surface side of the wafer after the metal layer forming step and before the separating step. Method.   4. The function according to claim 1, wherein in the separation step, a plurality of functional devices are separated while leaving an outer peripheral portion of the wafer in a plan view in a ring shape. 5. Manufacturing method of a conductive device.

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