JP2005079554A - Substrate with through electrode and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate with a through electrode and a manufacturing method of the same capable of realizing a low-cost and mechanically and electrically stable connection. <P>SOLUTION: The manufacturing method of the substrate 29 with the through electrode that the substrate 1 having a through hole 5 and a bonding substrate 6 having a non-through hole 11 are used to position the substrate 1 and the bonding substrate 6 so as to allow the through hole 5 and the non-through hole 11 to be communicated, wherein a process for bonding the substrate 1 and the bonding substrate 6, a process for filling a base material of conductivity from an opening section 28 of the through hole 5 in the substrate 1, a process for removing the bonding substrate 6 are at least provided. This method allows the substrate 29 with the through electrode having the through electrode 27 comprising a conductive section 8 penetrating the substrate 1 in the thickness direction and a protrusion section 10 which protrudes from one surface of the substrate 1 and is integrated with the conductive section 8 to be manufactured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate with a through electrode used for a high-density three-dimensional mounting type semiconductor device and the like, and a method for manufacturing the same.

In recent years, development has been advanced in which semiconductor devices such as IC chips are provided three-dimensionally via a substrate and wiring is performed at high density.
In this technique, in order to electrically connect the semiconductor devices provided on the front and back of the substrate, a conductive portion that penetrates the substrate in the thickness direction is used (for example, see Patent Document 1). In Patent Document 1, the conductive portion is called a through electrode.
JP 2003-86591 A

However, in the prior art as described above, a substrate with a through electrode formed by filling a conductive material into pores formed in a direction perpendicular to the main surface of the substrate to form a conductive portion functioning as a through electrode is provided. Used as a retrofit, a contact portion required to connect the through electrode to an external wiring, circuit, element or the like is formed.
In this case, in order to form the conductive portion and the contact portion, a plurality of steps are necessary, and the manufacturing process of the substrate with a through electrode becomes complicated and the cost is increased.
In addition, an interface may be formed between the conductive portion and the contact portion, or an oxide layer may be formed at the interface to be integrated, and there may be an electrical failure between the conductive portion and the contact portion. .

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object thereof is to provide a substrate with a through electrode and a method for manufacturing the same that can achieve a low-cost and mechanically and electrically stable connection. .

  In order to achieve the above object, the present invention includes a substrate, a conductive portion that penetrates the substrate in the thickness direction, and a protruding portion that protrudes from one surface of the substrate and is integrated with the conductive portion. A through electrode is formed by the conductive portion and the protruding portion, and the protruding portion has a larger area than the conductive portion when viewed from the direction in which the protruding portion overlaps the conductive portion. It is the board | substrate with a penetration electrode characterized.

  According to this configuration, since the protruding portion has a larger area than the conductive portion, the mechanical durability in the case where the protruding portion is connected to other members such as an external wiring, circuit, element, or the like can be improved. If the conductive portion and the protruding portion of the through electrode have an integrated structure with no interface, the risk of an electrical failure between the conductive portion and the contact portion can be avoided.

Further, according to the present invention, the width of the protruding portion may be larger than the width of the conductive portion at a portion where the protruding portion is in contact with the conductive portion as viewed from the cross-sectional direction of the substrate.
According to this configuration, it is possible to improve the mechanical durability when the protruding portion is connected to other members such as an external wiring, a circuit, and an element, for example.

Furthermore, according to the present invention, the cross section of the protruding portion may be any one of a substantially semicircular shape, a trapezoidal shape, and a rectangular shape.
According to this configuration, when the cross section of the protrusion is substantially semicircular, the protrusion and the other member can be connected from various directions. When the cross section of the protrusion is trapezoidal, since the protrusion has a flat surface, it can be easily connected to other members. When the cross section of the protrusion is rectangular, the protrusion has a flat surface, so that it can be easily connected to other members. In particular, in the case of a rectangular shape, it is possible to easily connect with other members by increasing the thickness of the protruding portion and to easily connect with a plurality of conductive portions.

  Further, in the present invention, the projecting portions that are in contact with a plurality of conductive portions may be integrated.

  Further, the present invention uses a substrate having a through hole and a bonding substrate having a non-through hole, and aligns the substrate and the bonding substrate so that the through hole and the non-through hole communicate with each other. And a step of bonding the substrate and the bonding substrate, a step of filling a conductive base material from an opening of the through hole of the substrate, and a step of removing the bonding substrate. A method for manufacturing a substrate with a through electrode.

According to this method, since the conductive portion and the protruding portion can be simultaneously formed, the manufacturing process can be simplified and the manufacturing cost can be reduced.
In addition, since the conductive portion and the protruding portion can be integrally formed at the same time, it is possible to avoid the possibility of an interface between the two. As a result, it is possible to avoid the conventional problem, that is, the possibility that an electrical failure occurs between the conductive portion and the protruding portion, because the oxide layer is formed at the interface between the two and is not integrated.

In the present invention, the alignment may be performed using an optical method.
In the present invention, a silicon substrate or a glass substrate may be used as the bonding substrate.

  In the present invention, when the bonding substrate is a silicon substrate, the optical method may use light having a wavelength in the infrared region.

  In the present invention, when the bonding substrate is a glass substrate, the optical technique may use light having a wavelength in the visible range.

  As described above, in the present invention, the through electrode is formed by the conductive portion and the protruding portion, and the protruding portion has a larger area than the conductive portion when viewed from the direction in which the protruding portion overlaps the conductive portion. Therefore, for example, if the projecting portion is connected to other members such as an external wiring, circuit, element, etc., the mechanical durability can be improved, and the conductive portion and the projecting portion in the through electrode have an integrated structure with no interface. The risk of an electrical failure occurring between the conductive portion and the contact portion can be avoided.

In the present invention, a substrate having a through hole and a bonding substrate having a non-through hole are used, and the substrate and the bonding substrate are aligned so that the through hole and the non-through hole communicate with each other. And a step of bonding the substrate and the bonding substrate, a step of filling a conductive base material from an opening of the through hole of the substrate, and a step of removing the bonding substrate. In the method of manufacturing a substrate with a through electrode, which is characterized in that the conductive portion and the protruding portion can be simultaneously formed, the manufacturing process can be simplified and the manufacturing cost can be reduced.
In addition, according to the present invention, since the conductive portion and the protruding portion can be formed at the same time, an interface is hardly generated between them, and an oxide layer is not formed between them. Therefore, it is possible to avoid the possibility of an electrical failure between the conductive portion and the protruding portion.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a method of manufacturing a substrate 29 with a through electrode according to an embodiment of the present invention, and includes steps 1 to 6.
FIG. 1 is a view showing a cross section of a substrate. In FIG. 1, reference numeral 1 is a substrate, reference numeral 1 a is a front surface of the substrate 1, and reference numeral 1 b is a back surface of the substrate 1. There is no distinction between the front and back surfaces of the substrate 1 before the surface processing, and in this specification, the surface that is first drilled to form the microholes is the surface 1a, and the opposite surface is the back surface 1b. Reference numeral 2 is a protective layer (surface insulating layer), reference numeral 5 is a through fine hole (through hole), reference numeral 6 is a bonding substrate, reference numeral 7 is a wall insulating layer, reference numeral 8 is a conductive portion, reference numeral 10 is a protruding portion, reference numeral 27. Is a through electrode.

(Process 1)
In the following description, the substrate 1 will be described using a silicon substrate as an example, but the material is not limited to silicon. In step 1, after forming the protective layer 2 on the surface 1a of the substrate 1, the electrode pattern is transferred onto the protective layer 2 by lithography. Next, the protective layer 2 at the electrode site is removed by wet etching or the like to partially expose the substrate surface 1a.

The thickness of the substrate 1 is, for example, about 300 to 600 μm. The protective layer 2 is made of an oxide film (SiO ₂ ) formed by a thermal oxidation method. The diameter of the through minute hole 5 is usually smaller than the substrate thickness, for example, about 5 to 200 μm. Moreover, the opening shape, arrangement | positioning, and number of through-microholes 5 can be arbitrarily designed by the electrode pattern to form.
In some cases, a protective layer (not shown) may be formed on the back surface 1b of the substrate.

(Process 2)
In step 2, the electrode portion of the substrate surface 1a is drilled by an etching technique to form the through-hole 5. ICP-RIE (Inductively Coupled) is used as a method of forming the through-hole 5 having a high aspect ratio (ratio of hole diameter to depth) having a hole diameter of several tens of μm and a depth of several hundred μm or more. Plasma-Reactive Ion Etching), PAECE, laser method, micro-drill method, etc., but micro-drill method is inefficient to drill many through-holes 5 in a short time, and laser drilling equipment is expensive. Therefore, ICP-RIE is often used for forming microholes for electrodes of the substrate 1 such as silicon.

  Further, in the substrate drilling, since the etching depth reaches several hundred μm, it is necessary to increase the selection ratio (etching ratio) between silicon and the etching mask and use a thick etching mask. Therefore, in order to pattern the protective layer 2 in the step 1, a resist (not shown) is provided as an upper layer of the protective layer 2, and the two layers of the resist and the protective layer 2 are formed to form the through micropores 5 in the step 2. It may be used as an etching mask.

Of course, as the structure of the etching mask used for forming the through-hole 5, either a resist such as a photoresist, or an oxide film, a nitride film, or the like can be used alone as an etching mask.
In the etching, when the protective layer 2 is made of SiO ₂ and the substrate 1 is made of silicon, the selection ratio (etching rate ratio) between silicon and SiO ₂ in ICP-RIE is about 1: 100 to 200.

In order to form the through micropores 5 in a silicon substrate having a thickness of several hundred μm or more, the thickness of the protective layer 2 may be appropriately determined from the thickness of the substrate 1 and the value of the selection ratio.
Further, since there is a difference in the etching rate between the central part and the peripheral part of the substrate 1, it is necessary to set the thickness of the etching mask corresponding to the etching time necessary for the central part having a slow etching rate to penetrate. It is.

Further, if in order to function oxide film such as Si0 ₂ as the protective layer 2, it is necessary thickness of about 0.5 to 3 [mu] m, the through micropores 5 creates at the end, which does not reach the thickness of the However, in the formation of the inner wall insulating layer 7 as the next step, if the substrate surface 1a is also exposed so as to be subjected to the film forming action at the same time, the insulating layer can be formed simultaneously on the fine hole wall surface 9 and the substrate surface 1a.
By forming the through-holes 5 in this way, it is possible to confirm that all the fine holes on the substrate 1 have been etched and penetrated.

  Further, when a protective layer is formed on the back side 1b of the silicon substrate, the protective layer has a slower etching rate than the silicon substrate 1 (when the protective layer is an oxide film, the selectivity is 1: 100 to When the protective layer is a resist of about 200, the selection ratio is about 1:50 to 100), and even after the outer peripheral hole has penetrated, the etching can be continued until the inner peripheral hole penetrates. . Therefore, it is possible to form the through-hole 5 having a uniform depth, and the depth of the through-hole 5 is defined by the thickness of the substrate 1.

(Process 3)
Next, in step 3, the bonding substrate 6 in which the non-through holes 11 are formed is bonded to the substrate 1 in which the through micro holes 5 have been formed.
As the bonding substrate 6, a silicon substrate or a glass substrate is used. The joining method of the joining substrate 6 and the removing method after joining and filling the electrode metal differ depending on the material of the joining substrate 6.

  First, the case where the bonding substrate 6 is a silicon substrate will be described. The silicon substrate preferably has a thickness of about 100 to 300 μm, for example. With the insulating film 12 such as an oxide film formed on the entire outer periphery of the bonding substrate 6, the non-through hole 11 is formed by the method described later. As a bonding method of the substrate 1, thermal bonding or bonding with a resin such as a photoresist is used. Below, these joining methods are demonstrated.

In the case where the bonding substrate 6 is a silicon substrate, when bonding the substrate 1 and the bonding substrate 6, both are aligned using an optical method, and the optical method is a light having a wavelength in the infrared region. Is used.
In thermal bonding, the substrate 1 having the through-holes 5 and the bonding substrate 6 having the non-through-holes 11 are washed with a mixed aqueous solution of ammonia and hydrogen peroxide, and then bonded together. . Thereafter, the bonding is completed by heat treatment in an oxygen atmosphere, a nitrogen atmosphere, or a mixed atmosphere of nitrogen and oxygen. The temperature in the heat treatment is desirably 800 to 1200 ° C., and the time is preferably 30 minutes to 12 hours. In this case, during the heat treatment, an oxide film is formed on the inner wall of the surface 1a of the silicon substrate 1 and the through-holes 5 and the non-through-holes 11 by a thermal oxidation reaction. Is no longer necessary.

Further, in the bonding with the resin, the photoresist is uniformly applied to one surface of the bonding substrate 6 with a thickness of, for example, about 0.5 to 50 μm and bonded to the substrate 1. Then, joining of both the substrates 1 and 6 is completed by heat-processing. The temperature is preferably 80 to 200 ° C. and the time is preferably 30 minutes to 2 hours.
Next, joining in the case where the joining substrate 6 is a glass substrate will be described. In this case, the thickness of the bonding substrate 6 is preferably 100 to 500 μm. As a bonding method, anodic bonding or resin bonding is performed. The joining method will be described below.

When the bonding substrate 6 is a glass substrate, when the substrate 1 and the bonding substrate 6 are bonded, the alignment between the two is performed using an optical method, and the optical method is a light having a wavelength in the visible range. Is used.
In the case of the anodic bonding method, the substrate 1 and the bonding substrate 6 made of glass are bonded together, the substrate 1 is connected to the anode side, the bonding substrate 6 is connected to the cathode side, and the heat treatment is performed while applying voltage. To do. The applied voltage is 600 V, the heating temperature is 400 to 500 ° C., and the heating time is preferably 1 to 2 hours. The bonding method using resin is the same when the bonding substrate 6 is silicon.

Next, a method for forming the non-through holes 11 in the bonding substrate 6 will be described with reference to the drawings.
When the bonding substrate 6 is a silicon substrate, as shown in FIG. 2A, in order to form a non-through hole 11 having a semicircular cross-sectional shape 13 (referred to as an isotropic non-through hole here), When forming by wet etching, a mixed solution of hydrofluoric acid, nitric acid, and acetic acid is used, and in dry etching, SF6 gas, CF4 gas, oxygen gas, or a mixed gas thereof is used. Further, as shown in FIG. 2B, a non-through-hole 11 (here, referred to as an anisotropic non-through-hole) having a trapezoidal shape having a plurality of planes 14, 15, 16 having different cross-sectional shapes is formed. Therefore, wet etching using KOH (potassium hydroxide) or TMAH (tetramethylammonium hydroxide) or dry etching is performed. Further, as shown in FIG. 2C, in order to form a non-through hole 11 having a rectangular cross section having a vertical side surface 17 (herein referred to as a vertical non-through hole), for example, the Deep-RIE method (This is a dry etching method that etches the silicon substrate vertically and deeply. As the etching gas, SF6 gas and C4F8 gas are generally used. SF6 plays the role of etching silicon, and C4F8 forms a polymer protective film on the sidewall of the etching hole. The silicon is etched vertically and deeply while alternately performing the etching and the protective film forming process.

When the non-through hole 11 is formed in the silicon substrate, the depth of the non-through hole 11 is, for example, 10 to 100 μm, and the width of the non-through hole 11 is, for example, 30 μm to 100 μm.
When the bonding substrate 6 is a glass substrate, when the isotropic non-through hole 11 is formed, a hydrofluoric acid, nitric acid, acetic acid mixed solution is used in wet etching, and SF6 gas, CF4 gas, oxygen gas is used in dry etching. Alternatively, a mixed gas of these is used. In glass, only the isotropic non-through hole 11 can be formed. The depth of the non-through hole 11 is, for example, 10 to 100 μm, and the width of the non-through hole 11 is, for example, 30 μm to 100 μm. To do.

(Process 4)
Referring back to FIG. 1, in step 4, the wall surface insulating layer 7 is formed on the inner wall of the through microhole 5 and the inner wall of the non-through hole formed in the bonding substrate 6. Since the substrate 1 is a silicon substrate and has conductivity, it is necessary to provide an insulating portion between the substrate 1 and the through electrode 27, and thus the wall surface insulating layer 7 is formed. The wall surface insulating layer 7 is an oxide film such as SiO ₂ , and the formation method is a thermal oxidation method, a PE-CVD method, an anodic oxidation method, or the like. This step is not necessary when thermal bonding is performed in the substrate bonding.

(Process 5)
In step 5, the through-holes 5 and the non-through-holes 11 in which the wall surface insulating layer 7 is formed are filled with the metal for the through-electrodes from the openings 28, and the conductive portions 8 and the protruding portions 10 that become bumps and wirings are formed. A through electrode 27 is formed. In the through electrode 27, the conductive portion 8 and the protruding portion 10 are formed at the same time, and an integrated structure without an interface between the conductive portion 8 and the protruding portion 10 is formed. Because of the integral structure, no oxide layer is detected between the conductive portion 8 and the protruding portion 10. In addition, the protrusion 10 has a larger area than the conductive portion 8 when viewed from the direction in which the protrusion 10 overlaps the conductive portion 8. In particular, the protrusion 10 is electrically conductive when viewed from the cross-sectional direction of the substrate 1. In the portion in contact with the portion 8, the width of the protruding portion 10 is larger than the width of the conductive portion 8. As a filling method, a molten metal suction method, a printing method, a CVD method, or the like is used.

  The molten metal suction method is a method used when a high-aspect-ratio fine hole is filled with a metal. First, a substrate in which a fine hole is formed is inserted into a heat-melted metal in a vacuum-tight airtight container. Then, by pressurizing the inside of the container, the inside of the microhole and the protruding portion are filled with the molten metal using the pressure difference between the inside of the microhole and the inside of the airtight container, and then the substrate is taken out from the molten metal and cooled. Fill holes and protrusions with metal.

(Step 6)
In step 6, the bonding substrate 6 is removed by polishing or etching. As the etching, either dry etching or wet etching can be applied. In the case of dry etching, SF6 gas, CF4 gas, oxygen gas, or a mixed gas thereof is used. In the case of wet etching, a mixed solution of hydrofluoric acid, nitric acid, and acetic acid, an aqueous potassium hydroxide solution, or the like is used.
The thickness of the bonding substrate 6 removed by etching or polishing varies depending on the material of the bonding substrate 6. When the bonding substrate 6 is silicon, the back insulating layer 4 has already been formed between the substrate 1 and the bonding substrate 6, so that the thickness equal to the thickness of the bonding substrate 6 is polished or etched. If it removes, it will be in the state which the back surface insulating layer 4 will be exposed, and the protrusion part 10 will be exposed in this state. Therefore, it is not necessary to form a contact hole as in the prior art. That is, since the insulating layer portion 7 is removed in the state where the protruding portion 10 is formed, there is no problem that a gap is generated between the conductive portion 8 and the insulating layer portion 7.

On the other hand, when the bonding substrate 6 is a glass substrate, there is no back surface insulating layer 4 between the substrate 1 and the bonding substrate 6, so that the bonding substrate 5 made of glass remains at a thickness of about several μm. The removal is stopped, and the remaining glass layer is used as the back insulating layer 4 for insulation and surface protection.
In any bonding substrate removing method, since the thickness of the substrate 1 does not change, the depth of the through microhole 5 is constant and equal to the thickness of the substrate 1. Therefore, the thickness of the substrate 1 after the through electrode 27 is formed is constant with high accuracy, and a substrate with a through electrode with high thickness reproducibility can be manufactured.

  In addition, the protrusion part 10 according to the shape of the non-through-hole 11 of the board | substrate 6 for joining in FIG. 2 (a), (b), (c) is formed. In particular, when the bonding substrate 6 in FIG. 2C is used, the protrusions 10 in contact with the plurality of conductive portions 8 are integrated, and the protrusions 10 are in electrical communication with the plurality of conductive portions 8. It will be a thing.

Next, examples of the present invention will be described. A silicon substrate having a diameter of 2 inches and a thickness of 400 μm is prepared. After forming a SiO ₂ film as a protective film on the surface of the silicon substrate by a thermal oxidation method, an electrode pattern is formed on the protective film by a photolithography technique. The protective film on the silicon substrate which becomes the electrode part was removed by transfer and wet etching.
The transferred electrode pattern is a pattern in which 2000 circular holes having a hole diameter of 60 μm are arranged. The SiO ₂ film thickness after wet etching was 1 μm, and this was used as a mask for the next etching for forming through-microholes.

The through micropores were formed by ICP-RIE. Next, substrate bonding was performed. The substrate to be joined is a silicon substrate having a diameter of 2 inches and a thickness of 200 μm, and is provided with a non-through hole having a predetermined shape. Both substrates were subjected to a hydrophilic treatment by washing with a mixed aqueous solution of ammonia and hydrogen peroxide, and then bonded together.
The bonded substrates were subjected to heat treatment at 1100 ° C. for 3 hours in an oxygen atmosphere. In this example, since a thermal bonding method was used, a wall surface insulating layer was formed in the bonding step, and it was not necessary to newly form a wall surface insulating layer.

Next, a metal serving as an electrode was injected into the fine holes and the non-through holes by a molten metal method, and the bonded substrate was removed by polishing. The polishing amount is 200 μm, which is equal to the thickness of the bonded substrates.
In this way, it was possible to obtain a substrate with a through electrode having a thickness substantially the same as the thickness of the starting substrate and having protrusions serving as bumps and wiring.

It is a manufacturing method of the board | substrate with a penetration electrode by embodiment of this invention. It is a figure which shows the board | substrate for joining by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Protective layer, 5 ... Through-micro hole (micro hole), 6 ... Bonding board, 7 ... Wall insulation layer, 8 ... Conductive part, 10 ... Projection part, 11 ... ······································ Non-through hole, 27 ·············

Claims (9)

A substrate, a conductive portion that penetrates the substrate in the thickness direction, and a protruding portion that protrudes from one surface of the substrate and is integrated with the conductive portion, and the conductive portion and the protruding portion A substrate with a through electrode, wherein a through electrode is formed, and the protrusion has a larger area than the conductive portion when viewed from a direction in which the protrusion overlaps the conductive portion. 2. The substrate with through electrodes according to claim 1, wherein a width of the protruding portion is larger than a width of the conductive portion at a portion where the protruding portion is in contact with the conductive portion when viewed from a cross-sectional direction of the substrate. 3. The substrate with a through electrode according to claim 1, wherein a cross section of the projecting portion has any one of a substantially semicircular shape, a trapezoidal shape, and a square shape. The board | substrate with a penetration electrode in any one of Claims 1-3 in which the said protrusion part formed in contact with several electroconductive part makes integral. Using a substrate having a through hole and a bonding substrate having a non-through hole, the substrate and the bonding substrate are aligned so that the through hole and the non-through hole communicate with each other. Bonding the substrate to the substrate,
Filling a conductive base material from the opening of the through hole of the substrate;
And a step of removing the bonding substrate. A method of manufacturing a substrate with a through electrode, comprising: a step of removing the bonding substrate. The method for manufacturing a substrate with a through electrode according to claim 5, wherein the alignment uses an optical method. The method for manufacturing a substrate with a through electrode according to claim 5 or 6, wherein a silicon substrate or a glass substrate is used as the bonding substrate. When the said board | substrate for joining is a silicon substrate, the said optical method uses the light which has a wavelength in an infrared region, The manufacturing method of the board | substrate with a penetration electrode of Claim 6 characterized by the above-mentioned. When the said board | substrate for joining is a glass substrate, the said optical method uses the light which has a wavelength in a visible region, The manufacturing method of the board | substrate with a penetration electrode of Claim 6 characterized by the above-mentioned.

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