JP2003347157A - Thin film electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film electronic component exhibiting excellent moisture resistance in which a protective layer is not stripped and cracks are not generated. <P>SOLUTION: The thin film electronic component comprises a supporting substrate 1, a thin film element A being provided on the supporting substrate 1 and having electrode layers 5 and 7 and a dielectric layer 3, a terminal electrode 18 electrically connected with the electrode layers 5 and 7, a first protective layer 13 covering the thin film element A, and a second protective layer 14 covering the first protective layer 13 wherein the thermal expansion coefficient of the first protective layer 13 is set smaller than that of the second protective layer. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-film electronic component, and more particularly to a thin-film electronic component suitably used for high-frequency applications, such as a thin-film capacitor and a thin-film filter.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller and more sophisticated, there has been a growing demand for electronic components installed in electronic devices to be smaller, thinner, and compatible with high frequencies.

For example, in a computer for processing a large amount of information at a high speed, a clock frequency for driving a CPU chip exceeds 1 GHz, and a clock frequency of a bus between chips is further increased from 133 MHz.

In addition, as the degree of integration of LSIs increases, there is a tendency that the power supply voltage is lowered in order to suppress heat generation from the chip, thereby reducing power consumption. As the speed, density, and voltage of these integrated circuits have increased, passive components such as capacitors have also been required to exhibit excellent characteristics with respect to high-frequency or high-speed pulses, in addition to increasing the size and capacitance. .

[0005] As the operating frequency increases, the resistance and inductance of the elements cause an instantaneous drop of the power supply voltage on the logic circuit side and new voltage noise, and this noise causes errors in the logic circuit. in addition,
In recent LSIs, since the power supply voltage is reduced in order to reduce power consumption due to an increase in the total number of elements and to suppress heat generation, the allowable fluctuation range of the power supply voltage is also reduced. from now on,
Further, in order to increase the number of elements and increase the operating frequency, it is necessary to take measures to reduce the influence of the resistance and inductance components of the mounting part.

[0006] In addition to the above-described electrical characteristics of the passive element itself, such as improvement in mounting accuracy due to an increase in the number of elements and improvement in reflow resistance due to component mounting, characteristics relating to mounting (mounting accuracy, mounting reliability). ) And moisture resistance reliability.

In response to such demands, US Pat.
9, 813, a lower electrode, a dielectric layer,
An upper electrode and a protective layer are sequentially provided, and a through hole is provided in the dielectric layer, the upper electrode, and the protective layer in order to obtain an electric signal from the lower electrode made of Ti / W, Ta, Al, or Cu at the shortest distance. BL made of Cr / Cu / Au on the inner wall of the hole
A thin film decoupling capacitor is disclosed in which an M layer is formed and then a solder bump is formed on the BLM layer.

This thin-film decoupling capacitor is mounted by aligning solder bumps of the thin-film decoupling capacitor with predetermined wiring formed on the surface of the mounting substrate and performing a reflow (heating) process.

Further, the thin-film decoupling capacitor has a low inductance structure. The thin-film decoupling capacitor can be arranged in the vicinity of the LSI chip. is there.

[0010]

However, in the above-mentioned thin film capacitor of the prior art, since the solder bump is formed in the through hole provided in the protective layer, heat is not generated when forming the solder bump or mounting on the mounting board. Is applied, the solder bump shrinks, and a load is applied to the protective layer having a through hole in which the solder bump is formed. Therefore, there has been a problem that the interface (upper electrode layer) between the protective layer and the layer of the thin film capacitor in contact with the protective layer is peeled off, or the protective layer itself is cracked, thereby deteriorating the moisture resistance. The present invention has been made in view of the above problems, and an object of the present invention is to provide a thin-film electronic component that can sufficiently exhibit the moisture resistance of a protective film.

[0011]

According to the present invention, there is provided a thin film electronic component in which a lower electrode layer, a dielectric layer, and an upper electrode layer are sequentially laminated on a supporting substrate, and the thin film electronic component is electrically connected to the electrode layer. A thin-film electronic component comprising: a terminal electrode; a first protective layer that covers the thin-film element so as to expose the terminal electrode; and a second protective layer that covers the first protective layer. expansion coefficient of 1.0 × 10 ^-7 ° C. ^{- 1} or 1.0 × 10
^-5 ° C ^{- 1} and the thermal expansion coefficient of the second protective layer is 1.0 ×
10 ^-5 ° C. ^{- 1} or 1.0 × 10 ^-3 ℃ ^- is obtained by setting to less than ^1.

By adopting such a configuration, when external terminals such as solder bumps are formed on the terminal electrodes, or when the thin-film electronic components are mounted on a mounting substrate, the terminal electrodes are connected to the terminal electrodes. When heat is applied, even if the external terminal electrode undergoes thermal shrinkage, the second protective layer is
Since the thermal expansion coefficient is larger than that of the protective layer, the influence of the thermal shrinkage of the external terminal or the terminal electrode remains in the second protective layer, and the first protective layer is hardly affected by the thermal shrinkage of the external terminal. The interface between the thin film element in contact with the first protective layer does not peel off, and the first protective layer does not crack.
The first protective layer can fulfill its original function, that is, the function of improving moisture resistance, and thus can improve the moisture resistance of the thin-film electronic component.

Further, a first protective layer is formed around the terminal electrode with a gap of 10 μm or more. Thereby, the influence of the heat shrinkage of the external terminals on the first protective layer can be reduced, and the original function of the first protective layer can be achieved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A thin film electronic component according to the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a thin film capacitor which is an example of a thin film electronic component. The thin film capacitor shown in FIG. 1 has a lower electrode layer 5 a and an extension 5 on a support substrate 1.
b, a lower electrode layer 5 formed on the lower electrode layer 5a, an upper electrode layer 7a formed on the dielectric layer 3 and an upper electrode The layers 7 are sequentially formed. The lower electrode layer 5a,
The thin film element A in which a predetermined capacitance is generated by the dielectric layer 3 and the upper electrode layer 7a is formed. Further, a plurality of thin film elements A may be provided on the support substrate 1 as needed.

The lower electrode layer 5 is circularly etched in accordance with the region where the extension 7b of the upper electrode layer 7a is formed. The lower electrode layer 5 is divided into a lower electrode layer 5a forming a capacitor and an extension 5b (a region where a terminal electrode is formed) not forming a capacitor.

The upper electrode layer 7 is etched so as to expose the lower electrode layer 5a, and is divided into an upper electrode layer 7a forming a capacitor and an extension 7b not forming a capacitor.

Also, at least the extension 7 of the upper electrode layer 7a
b and the extension 5b of the lower electrode layer 5a, a solder diffusion preventing layer 17 is formed. On the solder diffusion preventing layer 17, a solder adhesion layer 18 serving as a terminal electrode is formed. External terminals 11 a and 11 b such as solder balls are provided via the solder adhesion layer 18.

The support substrate 1 is selected from alumina, sapphire, aluminum nitride, magnesium oxide single crystal, strontium titanate single crystal, surface silicon oxide, glass, quartz, etc., and is not particularly limited. Electrode layer 5,
The material of 7 is limited depending on the use of the thin film electronic component and the purpose of use of each part. For example, when used for a high-speed signal circuit, a material having a low electric resistance is preferable, and Cu, Au, A
g, Pt, etc. can be illustrated.

As the material of the dielectric layer 3, beryllium titanate, strontium titanate, strontium beryllium titanate, etc. are used. The dielectric constant is high to some extent, and a large amount of electric charges can be accumulated. Rate 7
It is composed of zero or more materials.

The solder diffusion preventing layer 17 is made of Ti, Cr, N
It may be made of any one of i, Cu, Pd, Pt, or an alloy of two or more kinds selected from these metals, as long as it can be formed by sputtering, vapor deposition, plating, or the like. The thickness of the solder diffusion preventing layer 17 may be 0.3 μm or more in order to exhibit a function as a solder barrier.

The solder adhesion layer 18 is preferably made of a material having good solder wettability.
There are Cr, Au and the like, and Au is particularly desirable. Further, in order to improve the adhesion between the solder diffusion preventing layer 17 and the electrode layers 5 and 7 made of, for example, a known adhesion material such as Ti or Cr may be interposed between them.

The thin-film capacitor of the present invention has a first
At least the thin film element A is covered with the protective layer 13, through holes 23 a and 23 b are formed in the first protective layer 13 in the dielectric layer non-formed area B, and a solder adhesion layer 18 is provided on the bottom surface of the through holes 23 a and 23 b. It is exposed. Also, a second protective layer 14 is formed so as to cover the first protective layer 13 and the inner walls of the through holes 23a and 23b. That is, the second protective layer 14 in the dielectric layer non-formation region B is provided with the first protective layer 13
Hole 2 smaller than through holes 23a and 23b formed in
5a and 25b are formed, and the solder adhesion layer 18 is exposed on the bottom surfaces of the through holes 25a and 25b to serve as terminal electrodes. That is,
The second protective layer 14 is formed wider than the region where the first protective layer 13 is formed.

FIG. 2 shows the region where the first protective layer 13 is formed and the second protective layer 13.
FIG. 3 is a plan view showing a relationship between formation regions of a protection layer. A solid line indicates a region where the first protective layer 13 is formed, and a dotted line indicates a region where the second protective layer 14 is formed. Through hole 23, 2
5, the through holes 23a, 23b of the first protective layer 13
By making the through holes 25 a and 25 b of the second protective layer 14 smaller than that, the formation region of the second protection layer 14 is made wider than the formation region of the first protection layer 13. More specifically, a non-formation region (gap d) of the first protection layer of 10 μm or more is formed around the through holes 25a and 25b, and the gap d is covered with the second protection layer. Note that, as shown in FIG. 2, the second protective layer 14 may be formed wider than the first protective layer 13 also in the outer peripheral portion.

The first protective layer 13 is desirably made of a material having high moisture resistance. For example, an inorganic material such as silicon nitride or silica is particularly desirable. Further, a laminated structure using two or more of these materials may be used. The first protective layer 13 made of these inorganic materials has a thermal expansion coefficient of 1.0 × 1.
0 ^-7 ° C ^{- 1} or more and less than 1.0 × 10 ^-5 ° C ^{- 1}

The material of the second protective layer 14 is not particularly limited, and may be the inorganic material described above, or may be polyimide or benzocyclobutene (BC).
Organic materials such as B) may be used. Further, a laminated structure using two or more of these materials may be used. These materials have a thermal expansion coefficient larger than that of the first protective layer, for example, 1.0 × 10 ⁻⁵ ° C. ^{- 1} or more.
^-3 ° C. ^- is less than ^1.

Accordingly, when viewed as a whole of the protective layer, the thermal expansion coefficients of the second and first protective layers 14 and 13 from the outside of the protective layer are set so as to gradually decrease toward the thin film element.

Then, the through-hole 25a of the second protective layer 14,
External terminals 11a and 11b are formed in 25b.

The external terminals 11a, 11b are
There are a ball shape, a bump shape, a foil shape, a plate shape, a line shape, a paste shape and the like, and there is no particular limitation, and a plurality of shapes may be combined. The material is Pb, Sn, Au,
Pt, Pd, Al, Ni, Ag, In, Cu, Bi, S
b and Zn, etc., as long as they are conductive,
A plurality of materials may be combined.

The thin film capacitor 43 as described above is similar to that shown in FIG.
As shown in (2), after the external terminals 11a and 11b are positioned on the predetermined wirings 41a and 41b formed on the surface of the mounting board 40, the external terminals 11a and 11b are bonded and mounted by reflow processing.

In the case of the thin-film electronic component shown in FIG. 1, for example, when the external terminals 11a and 11b are formed of solder balls, the external terminals 11a and 11b are formed on the solder adhesion layer 18 by using a screen printing or a ball mounter, which is a known technique. External terminals 11a, 1
After the 1b is provided, it is bonded to the predetermined wirings 41a and 41b of the mounting board 40 by performing a reflow process and mounted.

In the thin-film capacitor configured as described above, the second protective layer 14 is formed more than the region where the first protective layer 13 is formed.
Since the formation region of the external terminals 11a and 11b is larger in the through holes 25a and 25b of the second protective layer 14 and when the thin film capacitor is mounted on the mounting substrate 40, the heat generated by the external terminals 11a and 11b is larger. Even if the influence of shrinkage, specifically, whether the external electrodes 11a and 11b are directly or indirectly affected by the thermal stress on the terminal electrode serving as the solder adhesion layer 18, the thermal expansion coefficient of the second protective layer 14 is Since the thermal expansion coefficient of the first protective layer 13 is larger than that of the second protective layer 1,
4 makes it easier to absorb. Thereby, the interface between the first protective layer 13 and the layer in contact with the first protective layer 13 or the interface between the first protective layer 13 and the upper electrode layer 7a does not peel off, and the first protective layer 13 is not cracked. Thus, the primary function of the first protective layer 13 can be achieved. Therefore, the moisture resistance of the thin film capacitor can be improved.

Although a thin film capacitor has been described as an example of the thin film electronic component of the present invention, the present invention is not limited to the above example. For example, a thin film composite component such as a thin film LC filter or a thin film RC component may be used. Of course, the present invention may be applied.

[0034]

EXAMPLE The lower electrode layer 5, upper electrode layer 7, solder diffusion preventing layer 17 and solder adhesion layer 18 were formed by DC sputtering, and the dielectric layer 3 (dielectric thin film) was formed by RF sputtering. .

First, a 30 nm adhesion layer made of TiO ₂ is formed on a support substrate 1 made of sapphire, a 30 nm Au layer is formed on the upper surface of this adhesion layer, and a lower electrode layer 5 is formed.
And

The lower electrode layer 5 was patterned by photolithography. Processed lower electrode layer 5
Then, a 0.5 μm-thick Ba (Sr
_1/3 Ti _2/3) to form a O ₃ dielectric layer 3 made of. After that, the dielectric layer 3 was patterned using a photolithography technique.

Next, on the dielectric layer 3 and on the lower electrode layer 5 exposed from the dielectric layer 3, an upper electrode layer made of Au having a thickness of 30 nm and a solder diffusion prevention made of Ni having a thickness of 1.0 μm are formed. A layer 17 and a solder adhesion layer 18 made of Au having a thickness of 0.1 μm were sequentially formed. Thereafter, first, the solder adhesion layer 18 is processed into a shape having a diameter of 100 μm by using a photolithography technique.
Then, the upper electrode 7 was patterned.

Thereafter, a thickness of 5.0 μm was formed by CVD.
m of SiO ₂ was formed, and a first protective layer having through holes 23 a and 23 b having a diameter of 120 μm and a depth of 5.0 μm was formed so that the solder adhesion layer 18 made of Au was exposed. At this time, the formation region of the first protective layer made of SiO ₂ is 2.0 mm in length and 1.8 mm in width, and its thermal expansion coefficient is 1.
It was 0 × 10 ⁻⁶ ° C. ^{- 1} .

Thereafter, a photosensitive BCB is applied, exposed,
The through-holes 25a, 25m having a diameter of 80 μm and a depth of 1 μm are developed so that the solder adhesion layer 18 made of Au is exposed.
The second protective layer 14 having b was formed. BC at this time
The formation area of the second protective layer 14 made of B is 2.04 m long.
m 2.02 mm. At this time, the resin component was adjusted so that the coefficient of thermal expansion of the second protective layer 14 was lower than 1.0 × 10 ⁻⁶ ° C. ^{- 1} to 1.0 × 10 ⁻⁴ ° C. ^{- 1} .

The difference between the through hole of the first protective layer and the through hole of the second protective layer, that is, the gap (hereinafter referred to as the difference D between the through holes).
Was set to 20 μm.

Finally, a eutectic solder paste consisting of 63% by weight of Pb and 37% by weight of Sn is transferred onto the solder adhesive layers 18 in the through holes 25a and 25b by screen printing, and reflowed. Then, solder bumps were formed to obtain a thin film capacitor as shown in FIG.

The effective electrode area of the obtained thin film capacitor is 1.8 mm ² , and the capacitance at a frequency of 1 MHz is about 30 nF.
Peeling of the protective layer 13 and cracking of the first protective layer 13 were completely absent.

Also, by changing only the formation region of the first protective layer 13, only the difference D between the through holes described above was changed, and several other thin film capacitors manufactured in the same manner as above were obtained. And these thin-film capacitors were heated at 85 ° C
Relative humidity 85% R. H. Of the insulation resistance value when a voltage of 2.0 V was continuously applied in the test tank was observed. FIG. 4 shows the result. Referring to FIG. 4, when the difference D between the through holes is 10 μm or more, the insulation resistance does not change from the initial value even after 500 hours or more.
On the other hand, when the difference D between the through holes is less than 10 μm, the insulation resistance value is deteriorated with respect to the initial value with the passage of time, and it can be seen that the smaller the difference D is, the faster the deterioration is.

The inventor of the present invention changed the material of the first protective layer 13 in various ways, and set the thermal expansion coefficient of the first protective layer 13 to 1.0 × 10 ⁻⁷ ° C. ^{- 1} or more and less than 1.0 × 10 ⁻⁵ ° C. ^{- 1.} And the material of the second protective layer is variously changed, and its thermal expansion coefficient is set to 1.0 × 10 ⁻⁵ ° C. ^{- 1} or more so as to be lower than the first thermal expansion coefficient.
× 10 ^-3 ° C. ^- be set to less than ¹ range, was confirmed similar effects. Conversely, when the coefficient of thermal expansion is reversed between the first protective layer and the second protective layer, stress due to the heat treatment concentrates on the interface between the first protective layer and the second protective layer, and the isolation at the interface and the first protective layer In addition, cracks occur in the second protective layer, so that the original function of the protective layer cannot be exhibited, and the moisture resistance of the thin film capacitor is greatly deteriorated.

[0045]

As described above in detail, according to the present invention, the influence of the thermal shrinkage of the external terminals and the stress generated when mounting the thin-film electronic component or forming the external terminal of the thin-film electronic component are reduced. Since the first protective layer itself does not remain in the second protective layer and is not cracked or the interface between the first protective layer and the layer of the thin-film electronic component in contact with the first protective layer does not peel off, the first protective layer has It can fully fulfill its original function,
The moisture resistance of the thin film electronic component is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a thin-film capacitor as an example of a thin-film electronic component of the present invention.

FIG. 2 is a plan view illustrating a relationship between formation regions of a first protective layer and a second protective layer.

FIG. 3 is a cross-sectional view showing a mounted state of a thin film capacitor which is an example of the thin film electronic component of the present invention.

FIG. 4 shows a test tank temperature of 85 ° C. and a relative humidity of 85% R.R.
H. Under a continuous load of 2.0 V in the test environment of
FIG. 4 is a characteristic diagram illustrating a temporal change of an insulation resistance value with respect to an initial value.

[Explanation of symbols]

1 ... Support substrate 3 ... Insulator layer 5 ... lower electrode layer 5a: Lower electrode layer 7 ... upper electrode layer 7a: Upper electrode layer 11a, 11b ... external terminals 18 ... Solder adhesion layer (terminal electrode) 13 First protective layer 14 second protective layer 23a, 23b ... through holes formed in the first protective layer 25a, 25b ... through holes formed in the second protective layer A: Thin film element

Claims (2)

[Claims] 1. A thin-film device comprising a support substrate, on which a lower electrode layer, a dielectric layer and an upper electrode layer are sequentially laminated, a terminal electrode electrically connected to the electrode layer, and a terminal electrode which is exposed. A thin-film electronic component comprising a first protective layer covering a thin-film element and a second protective layer covering the first protective layer, wherein the first protective layer has a coefficient of thermal expansion of 1.0 × 10 ^-7 ° C. ^{- one} or more,
1.0 × 10 ^-5 ℃ ^- less than ^1, the thermal expansion coefficient of the second protective layer is 1.0 × 10 ^-5 ℃ ^{- 1} or more, 1.0 × 10 ^-3 ℃ ^- and characterized in that less than ¹ Thin-film electronic components. 2. The method according to claim 1, wherein the first protective layer is formed around the terminal electrode with a gap of 10 μm or more.
The thin-film electronic component according to claim 1, wherein the gap is covered with a second protective layer.