JP2016096265A - 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 partially forms grooves to a substrate from a first surface side of the substrate having a first surface and a second surface, removes a second surface side of the substrate such that the substrate of the second surface side of portions where the grooves are formed remains, forms a film at the second surface side, injects a substance onto the film from the second surface side and removes the film of the second surface side of the portions where the grooves are formed and the substrate of the second surface side of the portions where the grooves are formed so as to expose the grooves.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 groove is partially formed in the substrate from the first surface side of the substrate having the first surface and the second surface, and the second portion at the position where the groove is formed. The second surface side of the substrate is removed so that the substrate on the surface side of the substrate remains, a film is formed on the second surface side, and a substance is injected from the second surface side onto the film Then, the film on the second surface side where the groove is formed and the substrate on the second surface side where the groove is formed are removed so that the groove is exposed.

FIG. 3 is a schematic process cross-sectional view illustrating a device manufacturing method according to the first embodiment. The schematic cross section of the device manufactured with the manufacturing method of the device of a 1st 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 the present embodiment, a groove is partially formed in the substrate from the first surface side of the substrate having the first surface and the second surface, and the second surface at the position where the groove is formed. The second surface side of the substrate is removed so that the side substrate remains, a film is formed on the second surface side, a substance is sprayed onto the film from the second surface side, and a groove is formed The film on the second surface side and the substrate on the second surface side where the groove is formed are removed so that the groove is exposed.

  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, grooves 20 are partially formed in the silicon substrate 10 from the surface side along the dicing region provided on the surface side of the silicon substrate 10 (FIG. 1A). 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.

  The formation of the groove 20 is a so-called DBG (Dicing Before Grinding) process in which a groove is formed in the dicing region from the front surface side before the back surface grinding. The depth of the groove 20 is set so as to be shallower than a planned grinding position (a dotted line in FIGS. 1A and 1B) at the time of back surface grinding. In other words, the depth of the groove 20 is set so that the semiconductor substrate 10 remains on the back surface side of the groove 20 after the back surface grinding.

  Next, a support substrate (support) 12 is bonded to the surface side of the silicon substrate 10 using an adhesive layer (not shown) (FIG. 1B). The support substrate 12 is, for example, quartz glass.

  Next, the back surface side of the silicon substrate 10 is removed by grinding, and the silicon substrate 10 is thinned (FIG. 1C). At this time, the semiconductor substrate 10 on the back surface side where the groove 20 is formed is left. The semiconductor substrate on the back surface side of the groove 20 is left to be 20 μm or less, more desirably 10 μm or less.

  Thereafter, a metal film 14 is formed on the back side of the silicon substrate 10 (FIG. 1D). The metal film 14 is provided on substantially the entire back surface. At this time, since the silicon substrate 10 exists on the back side of the groove 20, the metal film 14 is not formed in the groove 20.

  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, carbon dioxide particles are sprayed onto the metal film 14 from the back surface side of the silicon substrate 10 (FIG. 1E). By injecting carbon dioxide particles, the metal film 14 on the back surface side of the groove 20 and the silicon substrate 10 on the back surface side where the groove 20 is formed are removed so that the groove 20 is exposed. The metal film 14 and the silicon substrate 10 are removed by being scraped off by the carbon dioxide particles into the grooves 20 which are physically hollow portions (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.

  Next, a resin sheet 16 is attached to the back side of the silicon substrate 10. The resin sheet 16 is a so-called dicing sheet. For example, the resin sheet 16 is fixed to a metal frame 18. The resin sheet 16 is bonded to the surface of the metal film 14. Thereafter, the support substrate 12 is peeled from the silicon substrate 10 (FIG. 1G).

  Thereafter, the resin sheet 16 on the surface side of the silicon substrate 10 is peeled to obtain a plurality of divided MOSFETs.

  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 back side to the metal film 14, and the portion of the metal film 14 straddling the groove 20 and the silicon substrate 10. Remove. Since the removed metal film 14 and the silicon substrate 10 are scraped off into the hollow groove 20, the generation of burrs is suppressed. Only the metal film 14 in the groove 20 and the silicon substrate 10 can be removed in a self-aligning manner.

  It is considered that the removal of the metal film 14 and the silicon substrate 10 over the groove 20 is mainly caused by physical impact of carbon dioxide particles. In addition, the metal film 14 and the silicon substrate 10 are rapidly cooled by the low-temperature carbon dioxide particles, and the force by which the carbon dioxide colliding with the metal film 14 and the silicon substrate 10 is vaporized and expanded is added. It is considered that the removal effect of the film 14 and the silicon substrate 10 is promoted.

  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.

  FIG. 2 is a schematic cross-sectional view of a device manufactured by the manufacturing method of this embodiment. The cross-sectional shape in the vicinity of the groove 20 is shown. As shown in FIG. 2, the inclination angle (θ1) with respect to the back surface (second surface) of the end of the metal film 14 on the groove 20 side is the inclination angle (θ2) with respect to the back surface (second surface) of the side surface of the groove 20. ).

  The end of the metal film 14 is located on the opposite side of the groove from the silicon end of the boundary between the silicon substrate 10 and the metal film 14. The end of the metal film 14 is inclined in a direction away from the groove from the boundary between the silicon substrate 10 and the metal film 14 toward the surface of the metal film 14. The inclination becomes gentle toward the surface of the metal film 14. Further, the corner on the upper surface side of the end portion of the metal film 14 is a curved surface. The end portion of the metal film 14 having the shape shown in FIG. 2 improves the junction characteristics when the MOSFET is joined to a bed or the like.

  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. 3 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, grooves 20 are partially formed in the silicon substrate 10 from the surface side along the dicing region provided on the surface side of the silicon substrate 10 (FIG. 3A). 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 blade dicing, for example.

  The formation of the groove 20 is a so-called DBG (Dicing Before Grinding) process in which a groove is formed in the dicing region from the front surface side before the back surface grinding. The depth of the groove 20 is set so as to be shallower than a planned grinding position (dotted line in FIGS. 3A and 3B) at the time of back surface grinding later. In other words, the depth of the groove 20 is set so that the semiconductor substrate 10 remains on the back surface side of the groove 20 after the back surface grinding.

  Next, a support substrate (support) 12 is bonded to the surface side of the silicon substrate 10 using an adhesive layer (not shown) (FIG. 3B). The support substrate 12 is, for example, quartz glass.

  Next, the back surface side of the silicon substrate 10 is removed by grinding, and the silicon substrate 10 is thinned (FIG. 3C). At this time, the semiconductor substrate 10 on the back surface side where the groove 20 is formed is left. The semiconductor substrate on the back surface side of the groove 20 is left to be 20 μm or less, more desirably 10 μm or less.

  Thereafter, a resin film 30 is formed on the back surface side of the silicon substrate 10 (FIG. 3D). 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, carbon dioxide particles are sprayed onto the resin film 30 from the back side of the silicon substrate 10 (FIG. 3E). By spraying carbon dioxide particles, the resin film 30 on the back surface side where the groove 20 is formed and the silicon substrate 10 on the back surface side where the groove 20 is formed are removed so that the groove 20 is exposed. . The resin film 30 and the silicon substrate 10 are removed by being scraped off by the carbon dioxide particles into the grooves 20 that are physically hollow portions (FIG. 3F).

  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.

  Next, a resin sheet 16 is attached to the back side of the silicon substrate 10. The resin sheet 16 is a so-called dicing sheet. For example, the resin sheet 16 is fixed to a metal frame 18. The resin sheet 16 is bonded to the surface of the resin film 30. Thereafter, the support substrate 12 is peeled from the silicon substrate 10 (FIG. 3G).

  Thereafter, the resin sheet 16 is peeled to obtain a plurality of divided semiconductor memories.

  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 the present embodiment, after forming the groove 20 along the dicing region of the silicon substrate 10, carbon dioxide particles are sprayed from the back surface side to the resin film 30, and the resin film 30 and the silicon substrate 10 in a portion straddling the groove 20. Remove. Since the removed resin film 30 and the silicon substrate 10 are scraped off into the hollow groove 20, peeling of the resin film 30 is suppressed. Further, the cut surface of the resin film 30 is linear.

  It is considered that the removal of the resin film 30 and the silicon substrate 10 in the portion straddling the groove 20 is mainly caused by physical impact of carbon dioxide particles. In addition, the resin film 30 and the silicon substrate 10 are rapidly cooled by low-temperature carbon dioxide particles, and the force by which the carbon dioxide that collides with the resin film 30 and the silicon substrate 10 is vaporized and expanded is added. It is considered that the removal effect of the film 30 and the silicon substrate 10 is promoted.

  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 back side of the silicon substrate 10. By spraying the pressurized water, the metal film 14 and the silicon substrate 10 on the back side of the groove 20 are removed. The metal film 14 is removed by being scraped off into the groove 20 which is a hollow part physically by 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 onto the metal film 14 from the back surface side of the silicon substrate 10. By spraying pressurized water containing abrasive grains, the metal film 14 and the silicon substrate 10 on the back side of the groove 20 are removed. The metal film 14 is removed by being scraped off into the groove 20 which is a hollow portion physically 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.

  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)
12 Support substrate (support)
14 Metal film (film)
16 Resin sheet 20 Groove 30 Resin film (film)

Claims (13)

Forming a groove in the substrate partially from the first surface side of the substrate having the first surface and the second surface;
Removing the second surface side of the substrate so that the substrate on the second surface side of the portion where the groove is formed remains,
Forming a film on the second surface side;
A substance is sprayed onto the film from the second surface side, and the film on the second surface side where the groove is formed and on the second surface side where the groove is formed A device manufacturing method, wherein the substrate is removed so that the groove is exposed.   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 substrate is a semiconductor substrate.   When removing the film on the second surface side where the groove is formed and the substrate on the second surface side where the groove is formed, an end of the film on the groove side The device manufacturing method according to claim 1, wherein an inclination angle of the portion with respect to the second surface is smaller than an inclination angle of the side surface of the groove with respect to the second surface.   6. The device manufacturing method according to claim 1, wherein a support is bonded to the first surface side after the groove is formed and before the second surface side of the substrate is removed. 7. Method.   The said board | substrate of the said 2nd surface side of the location in which the said groove | channel was formed leaves 20 micrometers or less when removing the said 2nd surface side of the said board | substrate. Device manufacturing method.   The method for manufacturing a device according to claim 6, wherein after removing the film, a resin sheet is attached to the second surface side and the support is peeled off.   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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