JP2016096266A - Manufacturing method of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a device enabling suppression of shape abnormality at the time of processing of a film.SOLUTION: A manufacturing method of a device forms a film at a second surface side of a substrate having a first surface and a second surface, partially forms grooves to the substrate such that the film remains from a first surface side, injects a substance from the first surface side and removes the film at the second surface side of portions where the grooves are formed.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a device manufacturing method.

  A plurality of semiconductor elements formed on a semiconductor substrate such as a wafer is divided into a plurality of semiconductor chips by dicing along a dicing region provided on the semiconductor substrate. When a metal film serving as an electrode of a semiconductor element or a resin film such as a die bonding film is formed on one surface of the semiconductor substrate, it is necessary to remove the metal film or resin film in the dicing region during dicing. .

  As a method of removing the metal film or the resin film, for example, there is a method of removing the semiconductor substrate and the metal film or the resin film simultaneously by blade dicing. In this case, shape abnormalities such as protrusions (burrs) are likely to occur in the metal film or the resin film. When the shape abnormality of the metal film or the resin film occurs, the semiconductor chip is determined to be defective in appearance inspection, or the bonding failure between the bed and the semiconductor chip is caused, resulting in a decrease in product yield.

JP 2008-141135 A

  The problem to be solved by the present invention is to provide a device manufacturing method that enables suppression of shape abnormality during film processing.

  In the device manufacturing method according to the embodiment, a film is formed on the second surface side of a substrate having a first surface and a second surface, and the film is left on the substrate so that the film remains from the first surface side. A groove is partially formed, a substance is sprayed from the first surface side, and the film on the second surface side where the groove is formed is removed.

FIG. 3 is a schematic process cross-sectional view illustrating a device manufacturing method according to the first embodiment. FIG. 9 is a schematic process cross-sectional view illustrating a device manufacturing method according to a second embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same members and the like are denoted by the same reference numerals, and the description of the members and the like once described is omitted as appropriate.

(First embodiment)
In the device manufacturing method of this embodiment, a film is formed on the second surface side of the substrate having the first surface and the second surface, and the film is partially left on the substrate so that the film remains from the first surface side. A groove is formed, a substance is sprayed from the first surface side, and the film on the second surface side where the groove is formed is removed.

  Hereinafter, the case where the device to be manufactured is a vertical power MOSFET (Metal Oxide Field Effect Transistor) using silicon (Si) having metal electrodes on both sides will be described as an example. In this case, the substrate is a semiconductor substrate. Further, the film becomes a metal film. Further, an example will be described in which the substance injected onto the metal film is particles containing carbon dioxide. Note that particles containing carbon dioxide (hereinafter also simply referred to as carbon dioxide particles) are particles containing carbon dioxide as a main component. In addition to carbon dioxide, for example, inevitable impurities may be contained.

  FIG. 1 is a schematic process cross-sectional view showing the device manufacturing method of this embodiment.

  First, a base region and a source of a vertical MOSFET (semiconductor element) on the surface side of a silicon substrate (substrate) 10 having a first surface (hereinafter also referred to as a front surface) and a second surface (hereinafter also referred to as a back surface). Patterns such as regions, gate insulating films, gate electrodes, and source electrodes are formed. Thereafter, a protective film is formed on the uppermost layer of the silicon substrate 10. The protective film is, for example, a resin film such as polyimide, or an inorganic insulating film such as a silicon nitride film or a silicon oxide film. It is desirable that the silicon substrate 10 is exposed on the surface of the dicing region provided on the surface side.

  Next, a support substrate (support body) 12 is bonded to the surface side of the silicon substrate 10 (FIG. 1A). The support substrate 12 is, for example, quartz glass.

  Next, the back side of the silicon substrate 10 is removed by grinding, and the silicon substrate 10 is thinned. Thereafter, a metal film 14 is formed on the back side of the silicon substrate 10 (FIG. 1B). The metal film 14 is provided on substantially the entire back surface.

  The metal film 14 is a drain electrode of the MOSFET. The metal film 14 is, for example, a laminated film of different metals. The metal film 14 is, for example, a laminated film of aluminum / titanium / nickel / gold from the back side of the silicon substrate 10. The metal film 14 is formed by, for example, a sputtering method. The film thickness of the metal film 14 is, for example, not less than 0.5 μm and not more than 1.0 μm.

  Next, the silicon substrate 10 is placed on the tray 16 with the back side facing down. Only the periphery of the silicon substrate 10 is supported by the tray 16. Except for the peripheral portion of the silicon substrate 10, there is a gap between the tray 16. The metal film 14 at the periphery of the silicon substrate 10 and the periphery of the tray 16 may be fixed using an adhesive layer. Thereafter, the support substrate 12 is peeled from the silicon substrate 10 (FIG. 1C).

  Next, grooves 20 are partially formed in the silicon substrate 10 along the dicing region provided on the front surface side of the silicon substrate 10 so that the metal film 14 on the back surface side is exposed from the front surface side (FIG. 1D )). Here, the dicing region is a planned region having a predetermined width for dividing a plurality of semiconductor elements into a plurality of semiconductor chips by dicing, and is provided on the surface side of the silicon substrate 10. A semiconductor element pattern is not formed in the dicing region. For example, the dicing region is provided in a lattice shape on the surface side of the silicon substrate 10 so as to divide the semiconductor elements.

The groove 20 is formed by plasma etching, for example. The plasma etching is, for example, a so-called Bosch process in which an isotropic etching step using F radicals, a protective film forming step using CF ₄ radicals, and anisotropic etching using F ions are repeated.

  The groove 20 is preferably formed by etching the entire surface using the protective film on the surface side of the silicon substrate 10 as a mask. According to this method, since lithography is not used, the manufacturing process can be simplified and the cost can be reduced.

  Next, carbon dioxide particles are jetted from the surface side of the silicon substrate 10 (FIG. 1E). By injecting carbon dioxide particles, the metal film 14 on the back side of the portion where the groove 20 is formed is removed. The metal film 14 is physically removed by carbon dioxide particles (FIG. 1 (f)).

  The carbon dioxide particles are carbon dioxide in a solid state. The carbon dioxide particles are so-called dry ice. The shape of the carbon dioxide particles is, for example, a pellet shape, a powder shape, a spherical shape, or an indefinite shape.

  The carbon dioxide particles are generated, for example, by adiabatic expansion of liquefied carbon dioxide gas. The generated carbon dioxide particles are sprayed from a nozzle together with, for example, nitrogen gas and sprayed onto the metal film 14. The average particle size of the carbon dioxide particles is desirably 10 μm or more and 200 μm or less. The average particle diameter of carbon dioxide particles can be obtained, for example, by capturing carbon dioxide particles ejected from a nozzle with a high-speed camera and measuring the particles in the captured image.

  Further, the spot diameter on the surface of the metal film 14 when the carbon dioxide particles are sprayed onto the metal film 14 is preferably, for example, φ3 mm or more and φ10 mm or less.

  The MOSFET divided by removing the metal film 14 on the back surface side of the groove 20 is dropped and held on the tray 16 (FIG. 1G).

  The operation and effect of the device manufacturing method of the present embodiment will be described below.

  When the metal film 14 is formed also on the back surface side of the silicon substrate 10 like a vertical MOSFET, it is necessary to remove the metal film 14 on the back surface side of the dicing region at the time of dicing. For example, when the semiconductor substrate 10 and the metal film 14 are simultaneously removed from the front surface side by blade dicing, the metal film 14 at the end of the groove 20 in the dicing region is rolled up on the back surface side, and so-called burrs are generated.

  If burrs occur in the metal film 14, for example, the semiconductor chip may be defective in appearance inspection and cannot be commercialized. In addition, for example, when the semiconductor chip and the metal bed are bonded with a bonding material such as solder, adhesion may be deteriorated at a burr portion, which may cause a bonding failure.

  In the present embodiment, after forming the groove 20 along the dicing region of the silicon substrate 10, carbon dioxide particles are sprayed from the surface side, and the metal film 14 in a portion straddling the groove 20 is removed. The removed metal film 14 is scraped off into the space on the tray 16 side, and the generation of burrs is suppressed. Only the metal film 14 in the groove 20 can be removed in a self-aligning manner.

  It is considered that the removal of the metal film 14 in the portion straddling the groove 20 is mainly caused by physical impact of carbon dioxide particles. In addition, the effect of removing the metal film 14 by physical impact is promoted by the fact that the metal film 14 is rapidly cooled by the low-temperature carbon dioxide particles and the force that vaporizes and expands the carbon dioxide that collides with the metal film 14 is applied. It is considered a thing.

  In addition, when the groove 20 of the silicon substrate 10 is formed by blade dicing, chipping (chipping) may occur in the silicon substrate 10 at the end portion on the back surface side of the groove 20. In the present embodiment, since the groove 20 is formed by plasma etching, it is possible to prevent chipping generated in the silicon substrate 10 at the end portion on the back surface side of the groove 20.

  Further, when the groove 20 of the silicon substrate 10 is formed by blade dicing, at least a width greater than the thickness of the blade is required in the dicing region. For this reason, for example, a dicing area width of 50 μm or more is required.

  In this embodiment, since the groove 20 is formed by plasma etching, the width of the dicing region can be reduced. For example, the width of the dicing region can be, for example, 10 μm or more and less than 50 μm, and further 20 μm or less.

  Moreover, in this embodiment, a metal film etc. are removed mainly by the physical impact by a carbon dioxide particle. Therefore, for example, unlike the case of dry etching, even if the metal film is a laminated film of different metals, it is possible to remove the metal film regardless of the difference in chemical properties of the respective films. Therefore, even a laminated film of different metals can be easily removed while suppressing shape abnormality.

  In particular, when the groove 20 is formed by plasma etching as in the present embodiment, the unevenness difference at the end of the metal film 14 on the groove 20 side is greater than the unevenness difference on the side surface of the groove 20 of the silicon substrate 10. Becomes smaller. In other words, the surface roughness of the end of the metal film 14 on the groove 20 side is smaller than the surface roughness of the side surface of the groove 20.

  As mentioned above, according to this embodiment, it becomes possible to provide the manufacturing method of the device which enables suppression of the shape abnormality at the time of processing a metal film.

(Second Embodiment)
The device manufacturing method of the present embodiment is different from the first embodiment in that a semiconductor device including a resin film instead of a metal film on the back side of the silicon substrate 10 is manufactured. Hereinafter, the description overlapping with the first embodiment is omitted.

  Hereinafter, a case where a device to be manufactured is a semiconductor memory using silicon (Si) having a resin film on the back side will be described as an example.

  FIG. 2 is a schematic process cross-sectional view showing the device manufacturing method of this embodiment.

  First, a memory transistor of a semiconductor memory (semiconductor element), a peripheral circuit, a surface of a silicon substrate (substrate) 10 including a first surface (hereinafter also referred to as a front surface) and a second surface (hereinafter also referred to as a back surface), Patterns such as a power supply electrode, a ground electrode, and an I / O electrode are formed. Thereafter, a protective film is formed on the uppermost layer of the silicon substrate 10. The protective film is, for example, a resin film such as polyimide, or an inorganic insulating film such as a silicon nitride film or a silicon oxide film.

  Next, a support substrate (support body) 12 is bonded to the surface side of the silicon substrate 10 (FIG. 2A). The support substrate 12 is, for example, quartz glass.

  Next, the back side of the silicon substrate 10 is removed by grinding, and the silicon substrate 10 is thinned. Thereafter, a resin film 30 is formed on the back surface side of the silicon substrate 10 (FIG. 2B). The resin film 30 is provided on substantially the entire back surface.

  The resin film 30 is, for example, DAF (Die Attach Film) for bonding the divided semiconductor chip to the substrate. The film thickness of the resin film 30 is, for example, not less than 10 μm and not more than 200 μm.

  Next, the silicon substrate 10 is placed on the tray 16 with the back side facing down. Only the periphery of the silicon substrate 10 is supported by the tray 16. Except for the peripheral portion of the silicon substrate 10, there is a gap between the tray 16. The resin film 30 at the periphery of the silicon substrate 10 and the periphery of the tray 16 may be fixed using an adhesive layer. Thereafter, the support substrate 12 is peeled from the silicon substrate 10 (FIG. 2C).

  Next, grooves 20 are partially formed in the silicon substrate 10 along the dicing region provided on the front surface side of the silicon substrate 10 so that the resin film 30 on the back surface side is exposed from the front surface side (FIG. 2D )). Here, the dicing area is a predetermined area having a predetermined width for dividing the semiconductor chip by dicing, and is provided on the surface side of the silicon substrate 10. A semiconductor element pattern is not formed in the dicing region. For example, the dicing region is provided in a lattice shape on the surface side of the silicon substrate 10.

  The groove 20 is formed by blade dicing, for example.

  Next, carbon dioxide particles are jetted from the surface side of the silicon substrate 10 (FIG. 2E). By injecting carbon dioxide particles, the resin film 30 on the back side of the portion where the groove 20 is formed is removed. The resin film 30 is physically removed by carbon dioxide particles (FIG. 2 (f)).

  The carbon dioxide particles are carbon dioxide in a solid state. The carbon dioxide particles are so-called dry ice. The shape of the carbon dioxide particles is, for example, a pellet shape, a powder shape, a spherical shape, or an indefinite shape.

  The carbon dioxide particles are sprayed from a nozzle together with, for example, nitrogen gas and sprayed on the resin film 30. The average particle size of the carbon dioxide particles is desirably 10 μm or more and 200 μm or less. The average particle diameter of carbon dioxide particles can be obtained, for example, by capturing carbon dioxide particles ejected from a nozzle with a high-speed camera and measuring the particles in the captured image.

The spot diameter on the surface of the resin film 30 when the carbon dioxide particles are sprayed onto the resin film 30 is preferably, for example, from φ3 mm to φ10 mm.

  By removing the resin film 30 on the back surface side of the groove 20, the divided semiconductor memory is dropped and held on the tray 16 (FIG. 1G).

  The operation and effect of the device manufacturing method of the present embodiment will be described below.

  For example, a semiconductor device used in a small electronic device typified by a mobile phone, such as a semiconductor memory, uses a small and thin semiconductor package such as a BGA (Ball Grid Array) or MCP (Multi Chip Package). In BGA and MCP, a film-like die bonding material such as DAF is used instead of the paste-like die bonding material.

  When the resin film 30 such as DAF is formed on the back surface side of the silicon substrate 10, it is necessary to remove the resin film 30 on the back surface side of the dicing region at the time of dicing. For example, when the semiconductor substrate 10 and the resin film 30 are simultaneously removed from the surface side by blade dicing, the resin film 30 is not peeled off from the end of the groove 20 in the dicing region, or the cut surface of the resin film 30 is not linear. There is a problem of irregular shapes.

  In this embodiment, after forming the groove 20 along the dicing region of the silicon substrate 10, carbon dioxide particles are sprayed from the surface side to the resin film 30, and the resin film 30 in a portion straddling the groove 20 is removed. The removed resin film 30 is scraped off into the space on the tray 16 side, and the generation of burrs is suppressed. Further, the cut surface of the resin film 30 is linear.

  It is considered that the removal of the resin film 30 in the portion straddling the groove 20 is mainly caused by physical impact of carbon dioxide particles. In addition, the resin film 30 is rapidly cooled by the low-temperature carbon dioxide particles, and the effect of vaporizing and expanding the carbon dioxide that has collided with the resin film 30 is applied, thereby promoting the effect of removing the resin film 30 by physical impact. It is considered a thing.

  As mentioned above, according to this embodiment, it becomes possible to provide the manufacturing method of the device which enables suppression of the shape abnormality at the time of processing a resin film.

(Third embodiment)
The device manufacturing method of this embodiment is the same as that of the first embodiment except that pressurized water (water jet) is used instead of carbon dioxide particles. Hereinafter, the description overlapping with the first embodiment is omitted.

  In the present embodiment, water pressurized on the metal film 14 is sprayed from the surface side of the silicon substrate 10. The metal film 14 on the back side of the groove 20 is removed by spraying pressurized water. The metal film 14 is physically removed with pressurized water. This processing is so-called water jet processing.

  As described above, according to this embodiment, it is possible to provide a device manufacturing method that enables suppression of shape abnormality when processing a metal film.

(Fourth embodiment)
The device manufacturing method of this embodiment is the same as that of the first embodiment except that pressurized water containing abrasive grains is used instead of carbon dioxide particles. Hereinafter, the description overlapping with the first embodiment is omitted.

  In the present embodiment, pressurized water containing abrasive grains is sprayed from the surface side of the silicon substrate 10 onto the metal film 14. The metal film 14 on the back surface side of the groove 20 is removed by spraying pressurized water containing abrasive grains. The metal film 14 is physically removed by pressurized water containing abrasive grains. This processing is so-called abrasive jet processing.

  The abrasive grains are, for example, alumina particles, silicon carbide particles, silica particles and the like.

  As described above, according to this embodiment, it is possible to provide a device manufacturing method that enables suppression of shape abnormality when processing a metal film.

  In the embodiment, the case where the semiconductor element is a vertical MOSFET or a semiconductor memory has been described as an example. However, the semiconductor element is not limited to a vertical MOSFET or a semiconductor memory.

  In the first embodiment, the case where the grooves are formed by plasma etching has been described as an example. However, the grooves can also be formed by blade dicing or laser dicing. In the second embodiment, the case where the groove is formed by blade dicing has been described as an example. However, the groove can also be formed by plasma etching or laser dicing.

  In the embodiment, the case where the groove is formed so as to expose the metal film or the resin film has been described as an example. However, the groove may be formed so as to leave a part of the substrate. In this case, the remaining substrate and the metal film or resin film are simultaneously removed by spraying the substance.

  Further, in the embodiment, the case of using the MOSFET and the semiconductor memory has been described as an example, but the present invention is applied to the manufacture of an IGBT (Insulated Gate Bipolar Transistor), a small signal device, and a MEMS (Micro Electro Mechanical Systems). It is also possible.

  In the embodiments, the semiconductor substrate is described as an example of the substrate. However, the present invention can be applied to other substrates such as a ceramic substrate, a glass substrate, and a sapphire substrate. .

  In the embodiment, the case of injecting carbon dioxide particles onto a metal film or a resin film has been described as an example. However, it is solid at the time of injection from a nozzle, and is vaporized in an atmosphere where a substrate such as room temperature is placed. It is also possible to apply particles. For example, nitrogen particles or argon particles can be applied.

  In the embodiment, the metal film and the resin film are described as examples of the film formed on the second surface side. However, other films such as an inorganic insulating film such as a nitride film and an oxide film are applied. It is also possible.

  Although several embodiments and examples of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. For example, a component in one embodiment may be replaced or changed with a component in another embodiment. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10 Silicon substrate (substrate)
14 Metal film (film)
20 Groove 30 Resin film (film)

Claims (13)

Forming a film on the second surface side of the substrate having the first surface and the second surface;
Forming a groove in the substrate partially so that the film remains from the first surface side;
A method for manufacturing a device, wherein a material is sprayed from the first surface side to remove the film on the second surface side where the groove is formed.   The device manufacturing method according to claim 1, wherein the film is a metal film or a resin film.   The device manufacturing method according to claim 1, wherein the substance is particles containing carbon dioxide.   The device manufacturing method according to claim 1, wherein the groove is formed so that the film is exposed when the groove is formed.   The device manufacturing method according to claim 1, wherein the substrate is a semiconductor substrate.   The device manufacturing method according to claim 1, wherein the groove is formed by plasma etching when the groove is formed.   The device manufacturing method according to claim 1, wherein when forming the groove, the groove is formed by blade dicing.   The device manufacturing method according to claim 1, wherein before forming the film, the second surface side of the substrate is removed to thin the substrate.   The device manufacturing method according to claim 2, wherein the metal film is a laminated film of different metals.   The device manufacturing method according to claim 1, wherein the device is a MOSFET, an IGBT, a small signal device, or a MEMS.   The device manufacturing method according to claim 1, wherein the groove is formed along a dicing region provided on the first surface side.   The device manufacturing method according to claim 3, wherein an average particle diameter of the particles is 10 μm or more and 200 μm or less. The device manufacturing method according to any one of claims 1 to 12, wherein a difference in unevenness at an end of the film on the groove side is smaller than a difference in unevenness on a side surface of the groove.

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