JPH0831976A - Silicon double-sided packaging substrate and its manufacturing method - Google Patents

Abstract

PURPOSE:To improve packaging density of an electronic part mounting substrate with silicon as a substrate. CONSTITUTION:A through hole 2 is punched to a silicon substrate 1 using the wet etching process, powder beam process, or dry etching process, a conductor is formed inside the through hole 2, and the wirings on both surfaces of the silicon substrate are electrically connected. Further, a plurality of layers are wired on both surfaces of the silicon substrate 1 to create an electronic parts mounting substrate. Therefore, since electronic parts can be mounted on both surfaces of the silicon substrate and are electrically connected via through holes, the packaging density can be drastically improved and at the same time a circuit with improved high-frequency characteristics can be created.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a board for mounting electronic parts, and more particularly to a silicon double-sided board for electrically connecting wirings formed on both sides by through holes.

[0002]

2. Description of the Related Art A conventional mounting substrate using a silicon substrate will be described with reference to the sectional side view of FIG. 5 in which electronic components are mounted.

The mounting board 110 is one in which at least one wiring layer is provided on one surface of a silicon substrate 1 made of silicon single crystal, and electronic components are fixed to the uppermost wiring layer by soldering. The construction is a silicon substrate. 1. A passivation film 12 is formed on top of which a Cu wiring 4A is formed.
, And wirings 4B and 4C are provided with an insulator 5 such as polyimide or SiO2 sandwiched therebetween to form a wiring layer 4, and the wirings of each layer are connected vertically at arbitrary positions. Although the wiring 4B in the middle is shown as a single layer, it is common that the wiring 4B is made up of a plurality of layers. Wiring 4 which is the uppermost layer of wiring layer 4
The electronic component 7 is fixed to the conductor C by solder 8 and the other conductors and the surface of the insulator 5 are coated with an insulating material to form the surface insulating layer 6.

Although not shown in the figure, as a mounting substrate for electronic parts, there are a composite material substrate with an epoxy resin, a ceramics substrate and the like in addition to the above-mentioned silicon substrate. The density, ie the packaging density, is far below. In particular, a composite material substrate with an epoxy resin has a large shape change due to temperature and humidity, and a small mounted IC or the like has a large stress due to the shape change.
There is a possibility that C may be destroyed. In addition, although the ceramic substrate has excellent weather resistance, it is difficult to secure the highly accurate dimensions necessary for high-density mounting because the shape changes greatly when firing the ceramic.

[0005]

As described above,
In conventional electronic component mounting boards that use silicon as the substrate, it is not possible to make electrical connections between the both sides of the board by through holes, and the surface on which electronic components such as semiconductor components and chip components are mounted is practically one side. Limited, it is difficult to respond to further improvements in packaging density, downsizing, weight reduction, etc.
Therefore, the present invention seeks to solve this problem.

[0006]

Therefore, a wet etching, which is a semiconductor manufacturing technique, is provided on both surfaces of a silicon substrate on which electronic components are mounted, and through holes for making electrical connection between fine multilayer electric wiring and both surfaces of the substrate. The above problems were solved by using a process, a powder beam process and a dry etching process.

[0007]

By using the structure of the silicon double-sided mounting board having the through holes described above and the method of manufacturing the silicon double-sided mounting board to which the semiconductor manufacturing technology is applied, fine multi-layer electric wiring is formed on both sides of the silicon substrate. In addition, since both sides can be electrically connected, electronic components can be mounted at an extremely high density.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional side view of a double-sided mounting board using a silicon substrate in which electronic components are mounted.
(A) thru (h) are sectional side views showing a manufacturing process of a double-sided mounting substrate using a wet etching process,
3A to 3D are cross-sectional side views showing a manufacturing process of a double-sided mounting board using a powder beam process,
4 (a) and 4 (b) are cross-sectional side views showing a manufacturing process of a double-sided mounting substrate using a dry etching process.

In the structure of the double-sided mounting substrate 100 using the silicon substrate according to the present invention shown in FIG. 1, the through holes 2 are formed at the positions where the wirings 4A on both sides of the silicon substrate 1 need to be electrically connected. The through hole 2
A through-hole conductor 3 filled with a conductor is formed inside the. The other configurations are the same as those of the conventional example, and the same reference numerals are given to omit the description.

Wiring layers 4 are formed on both surfaces of the silicon substrate 1, and an electronic component 7 is fixed to the wiring 4C which is the uppermost layer of the wiring layer 4 on each surface. Are connected by the through-hole conductors 3 provided in the above to form an integrated circuit.

Next, a method of using the wet etching process, a method of using the powder beam process, and a method of using the dry etching process, which are methods of manufacturing the double-sided mounting substrate 100 according to the present invention, will be described.

First, a method of manufacturing a double-sided mounting board in which a through hole is formed by using a wet etching process according to the first embodiment will be described with reference to FIGS. 2 (a) to 2 (h).

A passivation film 12 such as a thermal oxide film or a nitride film is formed on both surfaces of the silicon substrate 1 by a CVD method or the like. After that, apply resist 13 on both sides,
The resist 13 is exposed and developed to form the opening 14 [FIG. 2 (a)].

Next, the opening 15 is formed in the passivation film 12 by dry etching using the opening 14.
Is formed [FIG. 2 (b)], the silicon substrate 1 is immersed in a silicon etching solution (for example, HF + HNO ₃ ) to form the through holes 2 in the silicon substrate 1 [FIG.
(C)].

In order to form the passivation film 17 on the side wall of the through hole 2, a thermal oxide film or a nitride film is formed again on the silicon substrate 1 (FIG. 2 (d)). Here, the silicon substrate 1 has a thickness of, for example, 400 μm, the passivation films 12 and 17 have a thickness of several nm, and the resist 13 has a thickness of several nm.
Has a thickness of 1 μm, and the resist opening 14 has a diameter of, for example, about 1 mm on the upper surface of the substrate opening.

Next, the through hole 2 is formed by a method such as printing.
The conductive paste 18 is embedded in the conductive paste 18 and then baked to solidify the conductive paste 18, and an electric conductor is formed in the through hole 2 to obtain an electrical connection between the wirings 4C on both sides [FIG. 2 (e)]. ].

As another method for obtaining electrical connection,
2D, Cu electroless plating 19 is applied to the entire silicon substrate 1, and then Cu electroplating 20 is performed.
Is performed [FIG. 2 (f)]. Next, when unnecessary portions of Cu are etched using a resist 22, a plated layer 21 which is a conductor is formed in the through hole 2 as shown in FIG.
Electrical connection between the wirings 4C on both sides can be obtained.
The resist 22 is peeled off, and the liquid resist 23 is embedded and sealed in the through hole 2 to flatten the substrate so that no obstacle will occur in a subsequent process.

After the through-hole conductor 3 is formed as described above to electrically connect both surfaces of the silicon substrate 1,
A wiring layer 4 made of Cu and polyimide or Cu and SiO ₂ is formed on both sides of the silicon substrate 1 by a conventional method to obtain a silicon double-sided mounting substrate.

Next, a method of manufacturing a double-sided mounting board for forming a through hole by using the powder beam process according to the second embodiment will be described with reference to FIGS. 3 (a) to 3 (d).

A resist 24 is applied to the surface of the silicon substrate 1 and then exposed and developed to remove the resist 24 at the locations where through holes are to be formed [FIG. 3 (a)]. next,
By anisotropically etching the silicon substrate 1 using a powder beam processing machine, it is possible to form the through holes 2 at the places where the resist 24 has been removed [FIG.
(B)].

The resist 24 is peeled off, and a passivation film 1 such as a thermal oxide film or a nitride film is formed on both surfaces of the silicon substrate 1.
After forming 2, the conductive paste 18 is embedded in the through hole 2 by a method such as printing. Next, firing is performed to solidify the conductive paste 18 to form the through-hole conductors 3 to obtain electrical connection between the wirings 4C on both surfaces of the silicon substrate 1 [FIG. )].

Alternatively, as described in the wet etching process, a passivation film 12 such as a thermal oxide film or a nitride film is formed on both surfaces of the silicon substrate 1 from the state shown in FIG. Plating 19
And then electrolytic plating 20 of Cu, and then C
By etching an unnecessary portion of u using a resist, a conductor is formed in the through hole 2 and electrical connection between the wirings on both sides is obtained. Liquid resist 2
3 is embedded in the through hole 2 and sealed to flatten the substrate so that no obstacle will occur in the subsequent process.

After the through-hole conductors 3 are formed to electrically connect both sides of the silicon substrate 1 as described above, the wiring layer 4 made of Cu and polyimide or Cu and SiO ₂ is provided on both sides of the silicon substrate 1. Forming is the same as in the first embodiment.

Further, a method of manufacturing a double-sided mounting board in which a through hole is formed by using the dry etching process according to the third embodiment will be described with reference to FIGS. 4 (a) and 4 (b).

A resist 25 is applied to the surface of the silicon substrate 1 and then exposed and developed to remove the resist 25 at the places where the through holes 2 are to be formed [FIG. 4 (a)]. By using this anisotropic etching method such as etching with SF ₆ gas in a reactive sputter etching apparatus, a through hole 2 having a linear side wall as shown in FIG. 4B is formed. The silicon substrate 1 can be perforated. Here, the thickness of the silicon substrate 1 is, for example, 30
0 μm, thickness of resist 24 is several μm, through hole 2
Has a diameter of several tens of μm.

When the resist 24 is peeled off, the state shown in FIG. 3 (b) described in the second embodiment is obtained,
The subsequent wiring process is the same as that of the second embodiment, and the description thereof is omitted.

The through holes formed by the powder beam process of the second embodiment and the dry etching process of the third embodiment are formed by the wet etching process of the first embodiment as shown in FIG. It is possible to form a through hole having a linear side wall instead of the shape in which the central portion is projected as shown in FIG. Therefore, by using the second and third processes, finer through holes can be formed than in the first process, and the wiring density can be further increased.

[0028]

As described above, according to the present invention,
Since electrical conduction can be established on both sides of the silicon mounting board, it is possible to realize mounting of electronic components with higher density. Further, since the wiring length can be shortened, a circuit having excellent high frequency characteristics can be formed.

Since the substrate is made of silicon, the characteristics of the IC such as temperature and humidity are the same as those of the bare chip of the IC, and the affinity with the substrate after mounting the bare chip is good. Further, a semiconductor manufacturing technique can be used for silicon processing, and a highly accurate and fine mounting substrate can be created.

[Brief description of drawings]

FIG. 1 is a cross-sectional side view of a double-sided mounting substrate using a silicon substrate according to the present invention in which electronic components are mounted.

FIG. 2 is a sectional side view showing a manufacturing process of a double-sided mounting substrate using a wet etching process.

FIG. 3 is a sectional side view showing a manufacturing process of a double-sided mounting substrate using a powder beam process.

FIG. 4 is a sectional side view showing a manufacturing process of a double-sided mounting substrate using a dry etching process.

FIG. 5 is a cross-sectional side view of a mounting board using a conventional silicon substrate in a state where electronic components are mounted.

[Explanation of symbols]

 1 Silicon Substrate 2 Through Hole 3 Through Hole Conductor 4 Wiring Layer 5 Insulator 6 Surface Insulating Layer 7 Electronic Component 8 Solder 12 Passivation Film 13 Resist 14 Opening 17 Passivation Film 18 Conductive Paste 19 Electroless Plating 20 Electroplating 21 Plating Layer 23 Liquid resist

Claims (4)

[Claims] 1. An electronic component mounting board using silicon as a substrate, wherein a wiring layer consisting of at least one layer for mounting and wiring electronic components is provided on both surfaces of a silicon wafer, and the wiring layers on both surfaces are electrically conductive. A silicon double-sided mounting board characterized by being electrically connected through a hole. 2. A through hole of the mounting board is formed by using a wet etching process,
A method for manufacturing the silicon double-sided mounting substrate according to claim 1. 3. The method for manufacturing a silicon double-sided mounting substrate according to claim 1, wherein the through-holes of the mounting substrate are created by using a powder beam process. 4. The method of manufacturing a silicon double-sided mounting substrate according to claim 1, wherein the through hole of the mounting substrate is formed by using a dry etching process.