JP2005150131A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form an insulating film having good insulation in the interior of a through hole by an electrodeposition technology as a method of forming the insulating film since the formation of the insulating film inside a conductive film is necessary but is difficult from the problem of a heat resistant temperature of a MOS, when a thermal oxidation film is formed in prior art if an electric connection is performed on the front and rear surfaces of a silicon semiconductor substrate through the interior of very fine through holes provided in the substrate, a CVD or a PVD method has a limit in an aspect ratio and it is difficult to uniformly adhere in the interior. <P>SOLUTION: In a semiconductor device, before the through hole is provided in the silicon semiconductor substrate, the surface functional film of the position is removed where the through hole is provided in advance. When the electrodeposition is performed thereafter, its edge is raised largely and an electrodeposition film is deposited from the difference of the current densities of the edge and the interior, and the electrodeposition film having the good insulation can be formed without exposing the ground of the edge part even if curing is performed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor device in which an insulating film is formed by electrodeposition coating in a through hole provided in a silicon semiconductor substrate.

  Currently, a thermal oxide film, CVD, PVD, or the like is generally used as a method for forming an insulating film of a semiconductor device. A specific example of such an apparatus is the invention of JP-A-2001-250912. In order to ensure electrical insulation in the through-hole in providing a through-hole in the semiconductor chip and forming a conductive film that electrically connects the front and back surfaces of the semiconductor chip through the through-hole, the through-hole and the conductive film An insulating film is provided between the two. The insulating film is formed of a silicon oxide film formed by heat treatment in a high temperature atmosphere, a silicon nitride film formed by a CVD method, an organic insulating film such as polyimide.

Further, as an example of using an electrodeposition technique as a method for forming an insulating film, there is an invention disclosed in JP-A-2002-319011. Similarly to the above, the insulating film in the through hole of the semiconductor chip is formed by the electrodeposition technique.
JP 2001-250912 A JP 2002-319011 A

  In recent years, semiconductor devices have become fine and complicated, and it is required to form an insulating film in a very fine pattern. In particular, in a semiconductor device that uses a through-hole formed in a semiconductor substrate to conduct on the front and back surfaces, a very fine through-hole of 50 to 150 μm is required as the conductive pattern becomes denser. An insulating film is always required on the inner surface of the film. Therefore, it is required to form an insulating film with a uniform film thickness on the inner surface of the fine through hole.

  Therefore, it has been proposed to apply the insulating film forming method described in JP-A-2001-250912 described above. However, since a semiconductor device on which a MOS circuit is mounted is restricted by a heat-resistant temperature of 350 ° C., it is impossible to form a silicon oxide film that is subjected to heat treatment near 1000 ° C. In addition, since the inner diameter of the through hole tends to be fine, the CVD and PVD methods have limitations due to the aspect ratio problem, and it becomes impossible to form a uniform film thickness on the inner surface of the through hole. End up.

  Accordingly, the present invention provides a semiconductor device in which an insulating film is formed on the inner surface of a through hole provided in a silicon semiconductor substrate, a step of removing a surface functional film at a position where the through hole is to be formed, and the surface functional film is removed. Forming a through hole in a portion, forming an insulating film by electrodeposition on the inner surface of the through hole, and forming a patterned conductive film on the inner surface of the insulating film and on the front and back surfaces of the silicon semiconductor substrate A semiconductor device characterized by the above is proposed.

  Unlike electroplating, electrodeposition coating causes the resin film at the edge to flow when the resin film is cured, resulting in a thin film. Therefore, it is essential to remove the surface functional film and swell the resin film at the edge portion before curing. Electrodeposition coating is generally known as a means of uniformly forming the film thickness regardless of the edge or flat part. However, when this method is used for through holes, there is a large difference in current distribution between the edge part and the through hole. By using, the effect of the swell of the edge portion can be further extracted.

  As described above, according to the present invention, an insulating film with good insulation can be formed by using an electrodeposition technique even on the inner surface of a very fine through hole provided in a silicon semiconductor substrate. it can. In addition, in the opening of the through hole, the base is not exposed due to heat flow at the time of curing, and an unpainted state does not occur, and an electrodeposited film can be reliably formed even after curing. Therefore, even if a conductive film is formed on the inner surface of the electrodeposition film and electrical connection is made on the front and back surfaces of the substrate, electrical insulation can be reliably achieved.

(First embodiment)
FIG. 1 is a view showing a state of a through hole 12 formed in a substrate 10 according to the first embodiment of the present invention. 1A is a top view and FIG. 1B is a cross-sectional view.

  In the figure, 10 is a silicon semiconductor substrate, and 11 is a surface functional film such as a silicon oxide film or silicon nitride film formed in advance on the front and back surfaces of the substrate 10. Reference numeral 12 denotes a through hole penetrating the substrate 10. Reference numeral 13 denotes an insulating electrodeposition film formed on the inner surface of the through hole 12. Reference numeral 14 denotes a conductive film formed on the inner surface of the electrodeposition film and around the opening of the through hole 12. The conductive film 14 is connected to an electrode (not shown) formed in advance on the surface of the substrate 10. The electrodeposition film 13 is a highly reliable insulating film, and is formed so that the conductive film 14 and the substrate 10 are completely insulated and do not leak.

  FIG. 2 is a sectional view showing a substrate manufacturing process in which an insulating film is formed by electrodeposition coating in a through hole provided in the silicon semiconductor substrate in the embodiment of the present invention. First, in FIG. 2A, a silicon semiconductor substrate 20 is prepared. Next, in FIG. 2B, the surface functional film in the portion where the through hole of the substrate 20 is formed is removed by □ 50 × 50 to 150 × 150 μm. As the removal method, laser processing, etching, or the like can be used.

  Next, in FIG. 2C, a through hole 22 having a diameter of 50 to 150 μm is formed in the substrate 20. The manufacturing method includes laser processing, drilling, etching, and the like, and can be appropriately selected in consideration of the material of the substrate 20, the shape of the through hole, the aspect ratio, productivity, and the like.

  Next, in FIG. 2D, an electrodeposition film 23 is formed on the substrate 20. As the electrodeposition paint, polyimide, maleimide, or the like can be used.

  Here, a schematic view of an apparatus for performing electrodeposition is shown in FIG. In the figure, reference numeral 36 denotes an electrodeposition paint for forming an electrodeposition film on the substrate 20. The substrate 20 is set in the electrodeposition paint 36 so as to be sandwiched between two electrodes 37. Electrodeposition is performed by applying a positive electrode to the electrode 37 and a negative electrode to the substrate 20. Further, the voltage and the size of the electrode are adjusted in a range where the electrodeposition film does not contact the opposing edge portion. By performing electrodeposition in this way, a highly reliable insulating film can be formed.

  Next, in FIG. 2E, a conductive layer 24 is formed on the inner surface of the electrodeposition film 23 and the front and back surfaces of the substrate 20. As the material for the conductive layer, copper, nickel, palladium, gold, or silver can be used. Moreover, the manufacturing method can use dry plating, wet plating, and a jet printing method, and these are suitably selected according to the shape and aspect ratio of the through-hole 22.

  Next, in FIG. 2 (f), the hole surrounded by the conductive layer 24 on the inner surface of the through hole 22 is buried with a filling material 25. As this embedding material, for example, a conductive metal material such as copper or silver, or an insulating resin material such as polyimide, silicon, amide, or epoxy can be used. As the embedding method, dipping, dispensing, printing, electrodeposition and the like can be used. Note that the embedding material 25 is not always necessary, and the inside of the through hole 22 may not be embedded.

  Next, in FIG. 2G, the conductive layer 24 on the front and back surfaces of the substrate 20 is patterned. Thereby, an electrical connection is selectively made with an electrode (not shown) provided on the substrate 20 in advance. Note that this step may be performed before the embedding step shown in FIG.

  Through the above steps, a semiconductor device capable of high-density mounting having the structure of the electrodeposition film 23 for bonding the front and back surfaces of the substrate 20, the conductive layer 24, and the through hole 22 made of the embedding material 25 is easily realized. Can do.

  Next, specific examples in the present embodiment will be described in order. First, as a process corresponding to FIG. 2A, a substrate 20 made of silicon and having a thickness of 625 μm is prepared. Electrodes, semiconductor elements, and wirings are provided in advance on the surface of the substrate 20, and the portions other than the electrode portions are covered with a silicon oxide film that is an insulating film and a surface functional film of a silicon nitride film.

Next, as a process corresponding to FIGS. 2B and 2C, the surface functional film 21 is removed and the through hole 22 is formed using a laser. The laser uses Nd: YAG laser second harmonic (wavelength 532 nm), Q-switch pulse oscillation, pulse width 30 nsec, oscillation frequency 3 kHz, □ 80 × 80 μm surface functional film is removed, and then a hole with a processed hole diameter of 80 μm Was processed. At that time, the fluence was 65 J / cm ^{2 on} the processed surface, and the number of shots was ²⁰ shots (surface functional film) and 100 shots (through holes). After the laser beam is emitted from the laser transmitter, it is expanded to a beam diameter of φ500 μm by a combination of optical lenses, and then passes through a mask having a diameter of φ400 μm to remove the peripheral portion of the beam to obtain a circular beam shape. . Next, the laser beam intensity is increased to a fluence of 65 J / cm ² by focusing with an optical system with a reduction ratio such that the beam diameter is 1/5 (φ80 μm) on the substrate. With the above function, processing was started immediately after the substrate was irradiated with the laser beam, the surface functional film was removed by the laser beam with the oscillation pulse 20shot, and a through hole was formed in the substrate 20 with the oscillation pulse 100shot.

  Next, as a step corresponding to FIG. 2D, an electrodeposition film 23 is formed on the inner surface of the through hole 22 and in the vicinity of the opening of the through hole 22 by electrodeposition.

  As the electrodeposition paint, a cation type polyimide electrodeposition paint (Elecoat, manufactured by Shimizu) is used, and the substrate is sandwiched between two electrodes as shown in FIG. Energized. An electrodeposition film was deposited under an electric field condition of 150 V, 120 sec, 25 ° C., and then cured at 250 ° C. for 60 minutes.

  By performing electrodeposition in this way, an electrodeposited film having a raised edge portion due to the through-hole and good coverability and excellent smoothness inside the through-hole could be formed.

  Next, as a step corresponding to FIG. 2E, the conductive layer 24 is formed by electroless plating on the inner surface of the insulating layer 23 and the front and back surfaces of the substrate. Plating conditions are potassium hydroxide 75 ° C., 5 minutes, pretreatment liquid (Melplate ITO conditioner 480, Melplate conditioner 1101, Enplate activator 440, manufactured by Meltex), Ni plating liquid (Melplate NI-867, A 0.5 μm film was formed by Meltex Co.) and then annealed for 30 minutes.

  Next, as a step corresponding to FIG. 2F, the hole surrounded by the conductive layer 24 on the inner peripheral surface of the through hole 22 is filled with the embedding material 25 by a printing method. The printing method uses a metal mask to embed polyimide ink (FS-510T40S, manufactured by Ube Industries) with a squeegee attack angle of 25 °, a squeegee speed of 30 mm / sec, a clearance of 1.5 mm, and a printing pressure of 0.25 Mpa. After printing, drying at 110 ° C. for 5 minutes was repeated 3 times and cured at 250 ° C. for 60 minutes.

  Next, as a process corresponding to FIG. 2G, the conductive layer 24 on the front and back surfaces of the substrate 20 is patterned. In the patterning method, first, a positive photosensitive resist (OFPR800, manufactured by Tokyo Ohka Kogyo Co., Ltd.) was uniformly applied by 2 μm using a spin coater, and then dried at 110 ° C. for 90 minutes. Next, using the mask corresponding to patterning, after exposing with an aligner, it developed with the developing solution (NMD-W, Tokyo Ohka Co., Ltd.). Next, etching was performed by immersing in an etching solution of 10% phosphoric acid, 40% nitric acid, and 40% acetic acid for 15 minutes. Finally, by immersing in a resist stripping solution (stripping solution 104, manufactured by Tokyo Ohka Kogyo Co., Ltd.) for 2 minutes, the remaining resist is stripped, and predetermined patterning is completed. As a result, the electrode provided on the substrate and the conductive layer 24 were selectively electrically connected.

It is a conceptual diagram which shows 1st Embodiment. It is sectional drawing which shows the example of the manufacturing process of 1st Embodiment. It is the schematic which shows the electrodeposition apparatus in 1st Embodiment.

Explanation of symbols

10, 20, 30 Substrate 11, 21 Surface functional film 12, 22 Through hole 13, 23 Electrodeposition film 14, 24 Conductive layer 15, 25 Filling material 36 Electrodeposition paint 37 Electrode

Claims (4)

  A silicon semiconductor substrate, wherein a surface functional film at an edge portion of a through hole is removed, and an electrodeposition film is formed on an inner surface of the through hole including the edge portion.   The silicon semiconductor substrate according to claim 1, wherein the electrodeposition film is an insulating film formed in the through hole.   The silicon semiconductor substrate according to claim 1, wherein a conductive film is formed on an inner surface of the electrodeposition film formed in the through hole. The silicon semiconductor substrate according to claim 1, wherein an inner diameter of the through hole is 50 μm to 150 μm.

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