JP2015142113A - Semiconductor device and manufacturing method of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device capable of reducing the thickness and a manufacturing method of semiconductor device.SOLUTION: A semiconductor device according to an embodiment of the invention has a through-hole and a metal part. The through-hole penetrates a base plate across the surface and the rear face thereof, and the dimension of one opening is smaller than the dimension of the other opening. The metal part is formed by means of conformal plating in the through-hole with the other opening of the through-hole closed, and the one opening of the through-hole is closed. The through-hole has a cross section perpendicular to a thickness direction of the base plate having a uniform dimension from the other opening up to a midway to the one opening, but the dimension of the cross section gets smaller from the midway to the one opening.

Description

  Embodiments described herein relate generally to a semiconductor device and a method for manufacturing the semiconductor device.

  2. Description of the Related Art Conventionally, there is a technique for reducing the area occupied by a semiconductor device by stacking chips each having a semiconductor element or an integrated circuit formed on a substrate in multiple stages. The stacked chips are electrically connected by a through electrode in which a metal is embedded in a cylindrical through hole that penetrates the substrate.

  The embedding of the metal into the through hole is generally performed by electrolytic plating. Such electrolytic plating includes, for example, bottom-up plating in which metal is gradually deposited from the closed bottom surface of the through hole toward the opening, and conformal plating in which metal is deposited from the entire inner peripheral surface of the through hole.

  Conformal plating has an advantage that metal can be embedded in the through hole in a shorter time than bottom-up plating. In conformal plating, as metal deposition proceeds, the voids in the through-holes gradually become smaller, and finally the open ends of the voids are blocked by the metal.

  In such conformal plating, metal is deposited on the inner peripheral surface of the gap toward the inside of the gap, but metal is deposited in all directions at the opening end of the gap, so that the opening end of the gap is blocked. When the metal is deposited until it is removed, the metal protrudes greatly from the substrate. Therefore, when chips having through holes in which metal is embedded by conformal plating are stacked in multiple stages, there arises a problem that the thickness of the semiconductor device increases.

Japanese Patent Laid-Open No. 2007-5402

  An object of one embodiment of the present invention is to provide a semiconductor device and a semiconductor device manufacturing method capable of reducing the thickness.

  A semiconductor device according to an embodiment of the present invention includes a through hole and a metal part. The through hole penetrates the front and back of the semiconductor substrate, and the size of one opening is smaller than the size of the other opening. The metal part is formed by conformal plating inside the through hole in which the other opening is closed, and includes a cavity in which the one opening in the through hole is closed.

FIG. 3 is a cross-sectional view schematically showing the configuration of the semiconductor device according to the first embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 1st Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 1st Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 1st Embodiment. Sectional drawing which shows typically the structure of the semiconductor device which concerns on 2nd Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 2nd Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 2nd Embodiment. Sectional drawing which shows the manufacturing process of the semiconductor device which concerns on 2nd Embodiment.

  Exemplary embodiments of a semiconductor device and a method for manufacturing the semiconductor device will be explained below in detail with reference to the accompanying drawings. Note that the present invention is not limited to these embodiments.

(First embodiment)
FIG. 1 is a cross-sectional view schematically showing the configuration of the semiconductor device 1 according to the first embodiment. In the following, for convenience, the upper surface of the substrate 2 shown in the figure is sometimes referred to as the front surface, and the lower surface is sometimes referred to as the back surface. As shown in FIG. 1, the semiconductor device 1 includes a through electrode that penetrates the front and back of a substrate 2 formed of a semiconductor such as Si (silicon). The surface of the substrate 2 is covered with an insulating film 6, and the back surface of the substrate 2 is covered with an insulating film 3.

  The through electrode includes a bump 10, an electrode pad 4, a seed film 7, and a metal part 8. The bumps 10 are formed by solder, for example, and are provided on the surface side of the substrate 2. The electrode pad 4 is formed of, for example, silicide and is provided at a position facing the bump 10 with the substrate 2 interposed therebetween.

  The seed film 7 is made of, for example, Cu (copper). The seed film 7 is formed around the opening of the through hole 5 on the surface of the insulating film 6, the surface of the electrode pad 4, and the surface of the substrate 2 that covers the inner peripheral surface of the through hole 5 penetrating the front and back of the substrate 2. It is provided on the surface of the insulating film 6 to be covered.

  The metal part 8 is made of, for example, Ni (nickel). The metal portion 8 is formed by, for example, conformal plating of Ni (nickel) on the surface of the seed film 7.

  Here, as shown in FIG. 1, the through-hole 5 penetrating the front and back of the substrate 2 has one dimension on the surface side of the substrate 2 larger than the dimension of the other opening blocked by the electrode pad 4 on the back surface side of the substrate 2. Is also small. Thereby, the shape of the insulating film 6 that covers the inner peripheral surface of the through hole 5 and the shape of the seed film 7 that covers the insulating film 6 follow the shape of the through hole 5.

  That is, at the stage where the seed film 7 is formed, a hole is formed inside the substrate 2 that is covered with the seed film 7 and has a smaller opening size on the surface side of the substrate 2 than on the bottom surface side of the substrate 2. It is in the state.

  Therefore, when Ni is deposited on the inner peripheral surface of the hole having such a shape by conformal plating to form the metal portion 8, for example, the hole shape has a cylindrical shape extending in a direction parallel to the thickness direction of the substrate 2. Compared to the case, the opening of the hole can be closed in a short time.

  As a result, the semiconductor device 1 has a substrate in which the through hole 5 formed in advance in the substrate 2 for forming the through electrode is, for example, a cylindrical through hole penetrating the substrate 2 in the thickness direction. The thickness of the metal part 8 formed on the upper layer side of the surface of 2 is reduced, and the thickness of the entire semiconductor device 1 can be reduced.

  Moreover, the through-hole 5 has the same cross-sectional dimension perpendicular to the thickness direction of the substrate 2 from the other opening on the back surface side of the substrate 2 to the one opening on the front surface side. It is formed so that the cross-sectional dimension becomes smaller toward one opening. That is, the through-hole 5 is tapered toward the surface of the substrate 2, and the cross section of the corner of the opening on the surface of the substrate 2 is sharper than 90 degrees.

  In conformal plating, the electric field concentrates at a pointed portion such as a corner rather than at a flat portion, so that the metal deposition by plating is faster. Therefore, in the manufacturing process of the semiconductor device 1, one opening on the surface side of the substrate 2 is blocked by the metal portion 8 by conformal plating in a shorter time.

  In addition, the semiconductor device 1 includes a cavity 9 closed at the center of the metal portion 8. Thereby, the semiconductor device 1 can suppress the breakage of the substrate 2 when, for example, heat treatment for processing the shape of the bump 10 into a hemisphere is performed.

  Specifically, in the process of performing heat treatment, the metal part 8 may cause thermal expansion. In such a case, the cavity 9 inside the metal part 8 absorbs the thermal expansion force exerted by the metal part 8 to the outside, and reduces the force applied from the metal part 8 to the substrate 2, thereby suppressing the breakage of the substrate 2. Can do.

  Further, in the process of manufacturing the semiconductor device 1, the opening on the surface of the substrate 2 in the through hole 5 is closed by the metal portion 8 in a relatively short time, so that the cavity 9 inside the metal portion 8 is more than the surface of the substrate 2. Is also formed at a deep position inside the substrate 2. That is, the upper end of the cavity 9 is located on the lower layer side than the surface of the substrate 2.

  Therefore, according to the semiconductor device 1, the thickness of the portion of the metal portion 8 that protrudes higher than the surface of the substrate 2 is made thinner than when the upper end of the cavity 9 is positioned above the surface of the substrate 2. And the control and management of the thickness of this part is facilitated.

  Further, the cavity 9 inside the semiconductor device 1 is formed inside the metal portion 8 formed of Ni, which has higher resistance to electromigration than Cu. Therefore, in the process of performing conformal plating, when the relatively high voltage is applied to the metal part 8, it is possible to suppress the displacement of the position of the cavity 9 inside the metal part 8, resulting in electromigration. Damage to the metal part 8 and the substrate 2 can be suppressed.

  Next, a method for manufacturing the semiconductor device 1 according to the first embodiment will be described with reference to FIGS. 2 to 4 are cross-sectional views illustrating the manufacturing process of the semiconductor device 1 according to the first embodiment. Here, a manufacturing process for forming through electrode portions penetrating the front and back of the substrate 2 included in the semiconductor device 1 will be described.

  When forming the through electrode portion of the semiconductor device 1, as shown in FIG. 2A, first, an insulating film 3 such as a Si oxide film is formed on the back surface of the substrate 2 by, for example, CVD (Chemical Vapor Deposition). To do. Then, electrode pads 4 are formed on the back surface side of the substrate 2 by patterning, for example, silicide at a predetermined position on the back surface side of the insulating film 3.

  Subsequently, as shown in FIG. 2B, a resist 21 such as a resin is formed on the surface of the substrate 2. Then, by patterning the resist 21, an opening 50 is formed at a position facing the electrode pad 4 in the resist 21. At this time, the opening 50 is formed such that the cross-sectional dimension orthogonal to the thickness direction of the substrate 2 is smaller than the corresponding cross-sectional dimension of the electrode pad 4.

  Thereafter, RIE (Reactive Ion Etching) is performed on the Si substrate using the resist 21 as a mask. In this step, RIE is performed by introducing a mixed gas of an etching gas and a protective film forming gas into the etching chamber.

  For example, CF4 (tetrafluoromethane) or CHF3 (trifluoromethane) is used as the etching gas. As the protective film forming gas, for example, C4F8 (octafluorocyclobutane) is used. Note that these gases are examples. At this time, the content of the protective film forming gas in the mixed gas is suppressed to be lower than that in the case of forming a cylindrical through hole penetrating the substrate 2 in the thickness direction.

  Thereby, as shown in FIG. 2B, erosion of the substrate 2 by RIE proceeds not only in the thickness direction (vertical direction) of the substrate 2 but also in the direction perpendicular to the thickness direction (lateral direction). . Therefore, the lateral dimension of the opening 50 formed in the substrate 2 gradually becomes larger than the lateral dimension of the opening 50 on the surface of the substrate 2 as the depth of the opening 50 increases.

  Thereafter, the content of the protective film forming gas in the mixed gas is increased. Specifically, the protective film forming gas is prevented so that erosion of the substrate 2 by RIE proceeds in the thickness direction (vertical direction) of the substrate 2 and does not proceed as much as possible in the direction perpendicular to the thickness direction (lateral direction). Adjust the content.

  That is, the content rate of the protective film forming gas is adjusted so that a cylindrical through-hole penetrating the substrate 2 in the thickness direction is formed. Under such processing conditions, the surface of the electrode pad 4 is exposed by continuing RIE.

  As a result, as shown in FIG. 2C, the substrate 2 has a through hole in which the dimension W1 of one opening formed on the front surface side is smaller than the dimension W2 of the other opening formed on the back surface side. 5 is formed. More specifically, the cross-sectional dimension perpendicular to the thickness direction of the substrate 2 is substantially equal from the other opening on the back surface side of the substrate 2 to the one opening on the front surface side. A through hole 5 having a smaller cross-sectional dimension is formed toward one opening.

  In other words, the size of the cross section perpendicular to the thickness direction of the substrate 2 extends from the other opening on the back side of the substrate 2 to the one opening on the front side, and the size of the cross section increases from the back side of the substrate 2 to the midway portion. Through holes 5 are formed in such a way that the size of the cross-section becomes smaller from the midway part toward one opening on the surface side of the substrate 2 than the degree of reduction.

  Subsequently, as shown in FIG. 3A, an insulating film 6 such as a Si oxide film is formed on the exposed surface of the electrode pad 4, the inner peripheral surface of the through hole 5, and the surface of the substrate 2 by, for example, CVD. Form. Then, as shown in FIG. 3B, the surface of the electrode pad 4 is exposed again by selectively removing the insulating film 6 formed on the surface of the electrode pad 4 by etching.

  After that, as shown in FIG. 3C, the exposed surface of the electrode pad 4, the surface of the insulating film 6 covering the inner peripheral surface of the through hole 5, and the surface of the insulating film 6 covering the surface of the substrate 2 For example, a seed film 7 for plating to be performed next is formed by forming a Cu film. The seed film 7 is formed by, for example, vacuum deposition or sputtering.

  Subsequently, as shown in FIG. 4A, a resist 22 such as a resin is formed on the surface of the seed film 7 covering the surface side of the substrate 2. Then, by patterning the resist 22, an opening is formed at a position facing the electrode pad 4 in the resist 22. At this time, the opening is formed so that the cross-sectional dimension orthogonal to the thickness direction of the substrate 2 is substantially equal to the corresponding cross-sectional dimension of the electrode pad 4.

  Subsequently, for example, Ni conformal plating is performed on the surface of the seed film 7 not covered with the resist 22. Thereby, the formation of the metal portion 8 is started by conformal plating inside the through hole 5 in which the other opening on the back surface side of the substrate 2 is closed by the seed film 7.

  At the beginning of the formation of the metal part 8, the inside of the through hole 5 covered with the metal part 8 is in a state where the surface of the substrate 2 is opened. If the opening on the surface side of the substrate 2 is not closed, the semiconductor device 1 may be damaged during the subsequent heat treatment. Therefore, thereafter, Ni conformal plating is continued, and one opening on the surface side of the substrate 2 in the through hole 5 is closed by the metal portion 8 as shown in FIG. As a result, a cavity 9 is formed in the center of the metal portion 8.

  Thereafter, as shown in FIG. 4C, bumps 10 are formed by laminating, for example, a solder layer on the surface of the metal part 8 surrounded by the resist 22. Finally, the seed film 7 immediately below the resist 22 is removed together with the resist 22, and heat treatment is performed to process the bumps 10 into a hemispherical shape, thereby completing the semiconductor device 1 shown in FIG.

  As described above, the semiconductor device 1 according to the first embodiment includes the through hole 5 that penetrates the front and back of the substrate 2 and that has one opening having a smaller dimension than the other opening. Furthermore, the semiconductor device 1 includes a metal portion 8 that is formed by conformal plating inside the through hole 5 in which the other opening is blocked, and closes one opening in the through hole 5.

  Therefore, according to the semiconductor device 1 according to the first embodiment, since the thickness of the metal part 8 protruding to the upper layer side from the surface of the substrate 2 is reduced, the thickness of the entire semiconductor device 1 is reduced. Can do.

(Second Embodiment)
FIG. 5 is a cross-sectional view schematically showing the configuration of the semiconductor device 1a according to the second embodiment. Hereinafter, the same components as those illustrated in FIG. 1 are denoted by the same reference numerals as those illustrated in FIG.

  As shown in FIG. 5, the semiconductor device 1a is different from the semiconductor device 1 shown in FIG. 1 in the shape of the hole penetrating the front and back of the substrate 2 and the shape of the insulating film 6a covering the inner peripheral surface of the hole. The configuration is the same as that of the semiconductor device 1 shown in FIG.

  Specifically, in the semiconductor device 1 shown in FIG. 1, the through hole 5 penetrating the front and back of the substrate 2 has a dimension of one opening on the surface side of the substrate 2 that is processed by the substrate 2 being processed. It is formed smaller than the dimension of the other opening on the side.

  On the other hand, in the semiconductor device 1 a shown in FIG. 5, the through-hole 5 a that penetrates the front and back of the substrate 2 is formed on the surface of the substrate 2 by the insulating film 6 a that covers the inner peripheral surface of the cylindrical cavity that penetrates the front and back of the substrate 2. The dimension of one opening on the side is formed smaller than the dimension of the other opening on the back side of the substrate 2.

  Also in the manufacturing process for manufacturing the semiconductor device 1a, the shape of the seed film 7 follows the shape of the through hole 5a. That is, at the stage where the seed film 7 is formed, a hole is formed inside the substrate 2 that is covered with the seed film 7 and has a smaller opening size on the surface side of the substrate 2 than on the bottom surface side of the substrate 2. It becomes a state.

  Thus, Ni is deposited on the inner peripheral surface of the hole having such a shape by conformal plating to form the metal portion 8, so that the metal portion 8 can open the hole in a short time as in the first embodiment. Can be occluded. Therefore, according to the semiconductor device 1a, the thickness of the entire semiconductor device 1a can be reduced as in the first embodiment.

  The semiconductor device 1a has the same configuration as that of the semiconductor device 1 shown in FIG. 1 except for the shape of the hole penetrating the front and back of the substrate 2 and the shape of the insulating film 6a covering the inner peripheral surface of the hole. The other effects produced from the embodiment are also produced in the same manner.

  Next, with reference to FIGS. 6-8, the manufacturing method of the semiconductor device 1a which concerns on 2nd Embodiment is demonstrated. 6 to 8 are cross-sectional views illustrating manufacturing steps of the semiconductor device 1a according to the second embodiment. Here, a manufacturing process for forming through electrode portions penetrating the front and back of the substrate 2 included in the semiconductor device 1a will be described.

  When forming the through electrode portion of the semiconductor device 1a, as shown in FIG. 6A, first, the insulating film 3 such as a Si oxide film is formed on the back surface of the substrate 2 by, for example, CVD. Then, electrode pads 4 are formed on the back surface side of the substrate 2 by patterning, for example, silicide at a predetermined position on the back surface side of the insulating film 3.

  Subsequently, as shown in FIG. 6B, a resist 23 such as a resin is formed on the surface of the substrate 2. Then, by patterning the resist 23, an opening is formed at a position facing the electrode pad 4 in the resist 23.

  Thereafter, RIE (Reactive Ion Etching) is performed on the Si substrate using the resist 23 as a mask. In this step, RIE is performed by introducing a mixed gas of an etching gas and a protective film forming gas into the etching chamber.

  For example, CF4 (tetrafluoromethane) or CHF3 (trifluoromethane) is used as the etching gas. As the protective film forming gas, for example, C4F8 (octafluorocyclobutane) is used. Note that these gases are examples.

  Here, the content of the protective film forming gas is such that the erosion of the substrate 2 by RIE proceeds in the thickness direction (vertical direction) of the substrate 2 and does not proceed as much as possible in the direction perpendicular to the thickness direction (lateral direction). Adjust. Thereby, a cylindrical cavity 51 penetrating the substrate 2 in the thickness direction is formed. Then, the surface of the electrode pad 4 is exposed by continuing RIE further.

  Subsequently, after removing the resist 23, as shown in FIG. 6C, the exposed surface of the electrode pad 4, the inner peripheral surface of the cylindrical cavity 51 formed in the substrate 2, and the surface of the substrate 2. For example, an insulating film 6a such as an Si oxide film is formed by CVD.

  At this time, the film thickness of the insulating film 6a in the portion covering the corner that is the opening end on the substrate 2 surface side of the cylindrical cavity 51 is larger than the film thickness of the insulating film 6a in the portion covering the inner peripheral surface of the cylindrical cavity 51. The film forming conditions of the insulating film 6a are adjusted so that the thickness of the insulating film 6a is increased.

  Thereafter, as shown in FIG. 7A, the surface of the electrode pad 4 is exposed again by selectively removing the insulating film 6a formed on the surface of the electrode pad 4 by etching. Thus, the insulating film 6a forms a through hole 5a in which the dimension W3 of one opening on the surface side of the substrate 2 is smaller than the dimension W4 of the other opening on the back surface side of the substrate 2.

  Subsequently, as shown in FIG. 7B, the exposed surface of the electrode pad 4, the surface of the insulating film 6a covering the inner peripheral surface of the through hole 5a, and the insulating film 6a covering the surface of the substrate 2 are formed. For example, a Cu film is formed on the surface, thereby forming a seed film 7 for the next plating. The seed film 7 is formed by, for example, vacuum deposition or sputtering.

  Subsequently, as shown in FIG. 7C, a resist 24 such as a resin is formed on the surface of the seed film 7 that covers the surface side of the substrate 2. Then, by patterning the resist 24, an opening is formed at a position facing the electrode pad 4 in the resist 24. At this time, the opening is formed so that the cross-sectional dimension orthogonal to the thickness direction of the substrate 2 is substantially equal to the corresponding cross-sectional dimension of the electrode pad 4.

  Subsequently, for example, Ni conformal plating is performed on the surface of the seed film 7 not covered with the resist 24. Thereby, the formation of the metal portion 8 is started by conformal plating inside the through hole 5a in which the other opening on the back side of the substrate 2 is closed by the seed film 7.

  Thereafter, Ni conformal plating is continued, and one opening on the surface side of the substrate 2 in the through hole 5a is closed by the metal portion 8 as shown in FIG. As a result, a cavity 9 is formed in the center of the metal portion 8.

  Thereafter, as shown in FIG. 8B, bumps 10 are formed by laminating, for example, a solder layer on the surface of the metal part 8 surrounded by the resist 24. Finally, the seed film 7 directly under the resist 24 is removed together with the resist 24, and heat treatment is performed to process the bump 10 into a hemispherical shape, thereby completing the semiconductor device 1a shown in FIG.

  As described above, in the second embodiment, the through hole 5a penetrating the front and back of the substrate 2 is formed on the surface side of the substrate 2 by the insulating film 6a covering the inner peripheral surface of the cylindrical cavity that penetrates the front and back of the substrate 2. The size of one of the openings is smaller than the size of the other opening on the back side of the substrate 2.

  Therefore, according to the semiconductor device 1a according to the second embodiment, since the thickness of the metal portion 8 protruding to the upper layer side from the surface of the substrate 2 is reduced, the thickness of the entire semiconductor device 1a is reduced. Can do. In the first embodiment and the second embodiment, the case where the metal part 8 is formed of Ni has been described. However, the material of the metal part 8 is not limited to Ni.

  For example, the metal part 8 is made of Au (gold), Ag (silver), Co (cobalt), Pd (palladium), W (tungsten), Ta (tantalum), platinum (Pt), rhodium (Rh), iridium (Ir ), Ruthenium (Ru), osmium (Os), rhenium (Re), molybdenum (Mo), niobium (Nb), boron (B), hafnium (Hf), and other metals having higher resistance to electromigration than Cu May be formed. Moreover, the metal part 8 may be formed with the alloy containing these metals.

  Moreover, the metal part 8 may be formed of Cu when the voltage used for conformal plating is relatively low. By using Cu as the material of the metal part 8, for example, Au, Ag, Co, Pd, W, Ta, Pt, Rh, Ir, Ru, Os, Re, Mo, Nb, B, Hf, etc. are used. However, the metal part 8 can be formed at low cost.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example 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. 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.

  1, 1a Semiconductor device, 2 substrate, 3, 6, 6a insulating film, 4 electrode pad, 5, 5a through-hole, 7 seed film, 8 metal part, 9 cavity, 10 bump

Claims (5)

A through-hole penetrating the front and back of the semiconductor substrate, the size of one opening being smaller than the size of the other opening;
A semiconductor device comprising: a metal portion formed by conformal plating inside the through hole in which the other opening is closed, and including a cavity in which the one opening in the through hole is closed. The through hole is
The cross-sectional dimension perpendicular to the thickness direction of the substrate is the same from the other opening to the middle part toward the one opening, and the cross-sectional dimension decreases from the middle part toward the one opening. The semiconductor device according to claim 1. The through hole is
The semiconductor device according to claim 1, wherein a dimension of the one opening is smaller than a dimension of the other opening by processing the substrate. The through hole is
The dimension of said one opening is formed smaller than the dimension of said other opening by an insulating film that covers the inner peripheral surface of a cylindrical cavity that penetrates the front and back of said substrate. Item 3. The semiconductor device according to Item 2. A process of forming a through-hole penetrating the front and back of the semiconductor substrate, the size of one opening being smaller than the size of the other opening;
Forming a metal part enclosing a cavity in which the one opening in the through hole is closed inside the through hole in which the other opening is closed, by conformal plating. Device manufacturing method.

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