JP2007019439A - High frequency circuit board and high frequency module - Google Patents

High frequency circuit board and high frequency module Download PDF

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JP2007019439A
JP2007019439A JP2005202343A JP2005202343A JP2007019439A JP 2007019439 A JP2007019439 A JP 2007019439A JP 2005202343 A JP2005202343 A JP 2005202343A JP 2005202343 A JP2005202343 A JP 2005202343A JP 2007019439 A JP2007019439 A JP 2007019439A
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circuit board
frequency circuit
bonding pad
high frequency
signal wiring
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Kazuhiko Adachi
一彦 安達
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Ricoh Co Ltd
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Ricoh Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
    • H01L24/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L24/02—Bonding areas ; Manufacturing methods related thereto
    • H01L24/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L24/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/02—Bonding areas; Manufacturing methods related thereto
    • H01L2224/04—Structure, shape, material or disposition of the bonding areas prior to the connecting process
    • H01L2224/05—Structure, shape, material or disposition of the bonding areas prior to the connecting process of an individual bonding area
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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    • H—ELECTRICITY
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    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/01—Chemical elements
    • H01L2924/01033—Arsenic [As]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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    • H01L2924/01079—Gold [Au]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
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    • H01L2924/01087—Francium [Fr]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/013—Alloys
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/102—Material of the semiconductor or solid state bodies
    • H01L2924/1025—Semiconducting materials
    • H01L2924/1026—Compound semiconductors
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    • H01L2924/10329—Gallium arsenide [GaAs]
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    • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10—Details of semiconductor or other solid state devices to be connected
    • H01L2924/11—Device type
    • H01L2924/14—Integrated circuits

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
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Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact high frequency circuit board which can realize low return loss at a frequency band ranging in wideband, in such a way that a width of bonding pad is made to be wider than signal wiring width, and that a characteristic impedance of the bonding pad is made to be equal to that of the signal wiring. <P>SOLUTION: In a high frequency circuit board 1, a transmission line consisting of a signal wiring 3 and ground wiring 2 is formed, and a bonding pad 4 is formed in a portion of the above-mentioned signal wiring 3, the width of the above-mentioned bonding pad 4 is wider than that of the above-mentioned signal wiring 3, and the characteristic impedance of the above-mentioned bonding pad 4 is equal to that of the above-mentioned signal wiring 3. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

本発明は、高周波パッシブデバイス、高周波半導体デバイス及びモノリシックマイクロ波集積回路（ＭＭＩＣ）を実装する高周波回路基板及び高周波モジュールに関するものである。   The present invention relates to a high-frequency circuit board and a high-frequency module on which a high-frequency passive device, a high-frequency semiconductor device, and a monolithic microwave integrated circuit (MMIC) are mounted.

従来、ＧＨｚ帯の高周波モジュールは、ＦＲ−４、ポリイミド基板、テフロン（登録商標）基板、あるいは高抵抗シリコン、半絶縁ＧａＡｓ基板などの誘電体基板に、マイクロストリップ線路などの伝送線路からなる高周波平面回路パターンを形成し、この回路パターン上にインダクタやキャパシタなどのパッシブ部品及びＭＭＩＣを実装して構成されている（例えば、特許文献１参照）。
かかるデバイスの実装形態としては、モジュールの薄型化とワイヤボンディングの寄生インダクタンスによる周波数特性劣化を避けるためにフリップチップ実装法が採用されている。
しかし、数１０ＧＨｚ帯のようなより高周波の領域では、フリップチップ実装だけでは、十分な高周波特性が得にくいことが明らかになってきた。これは、実装部のインピーダンスの不整合に起因している。その原因の１つとしては、フリップチップ実装に使用するバンプに寄生するインダクタンスによるインピーダンス不整合がある。
高さ１０μｍ程度の極めて小型のバンプであっても、その寄生インダクタンスは数１０ｐＨ程度となる。例えば、バンプの寄生インダクタンスが５０ｐＨの場合、３０ＧＨｚ帯の領域の電子部品に適用した場合、そのインピーダンスは約１０Ωとなるから、反射損失が増大するなど周波数特性に大きな影響を及ぼすことになる。
そのため、バンプ高さは低いことが望ましいが、逆に低くなると実装基板とＭＭＩＣ間の距離が短くなるため、両者間のキャパシタンス成分が増加し、新たな周波数特性劣化を引き起こすので、その高さ低減にも限界がある。
もう１つの原因としては、ボンディングパッドの特性インピーダンスと信号配線の特性インピーダンスの不整合がある。
ＭＭＩＣを含めて半導体デバイスのボンディングパッドは１００μｍ角程度と比較的大きい。さらに、実装歩留まりを考慮し、実装基板側のボンディングパッドは、半導体デバイスのパッドよりも大きめ目に設定し、例えば、１５０μｍ角程度が選ばれる。
一方、実装基板側の信号配線の幅といえば、例えば、厚さ１１０μｍのＧａＡｓ基板では、基準となる５０Ωのマイクロストリップ線路で８０μｍ程度（厚さ２μｍ Ａｕ配線）になる。
したがって、実装基板上の５０Ωの信号配線に対して、ボンディングパッドは３５Ωと小さくなってしまい、信号配線とボンディングパッド間でインピーダンスの不整合が生じ、反射が起こる。 Conventionally, a high-frequency module in the GHz band is a high-frequency plane composed of a transmission line such as a microstrip line on a dielectric substrate such as FR-4, polyimide substrate, Teflon (registered trademark) substrate, high-resistance silicon, or semi-insulating GaAs substrate. A circuit pattern is formed, and passive components such as inductors and capacitors and MMIC are mounted on the circuit pattern (see, for example, Patent Document 1).
As a mounting form of such a device, a flip chip mounting method is employed in order to avoid a frequency characteristic deterioration due to a thin module and a parasitic inductance of wire bonding.
However, in a higher frequency region such as several tens of GHz band, it has become clear that it is difficult to obtain sufficient high frequency characteristics only by flip chip mounting. This is due to the impedance mismatch of the mounting part. One of the causes is impedance mismatch due to inductance parasitic to bumps used for flip chip mounting.
Even a very small bump having a height of about 10 μm has a parasitic inductance of about several tens of pH. For example, when the parasitic inductance of the bump is 50 pH, when applied to an electronic component in a 30 GHz band region, the impedance is about 10Ω, which greatly affects the frequency characteristics such as an increase in reflection loss.
Therefore, it is desirable that the bump height is low, but conversely, if the distance is low, the distance between the mounting substrate and the MMIC is shortened, increasing the capacitance component between the two and causing new frequency characteristic degradation. There are also limitations.
Another cause is mismatch between the characteristic impedance of the bonding pad and the characteristic impedance of the signal wiring.
Bonding pads of semiconductor devices including MMIC are relatively large at about 100 μm square. Further, considering the mounting yield, the bonding pad on the mounting substrate side is set to be larger than the pad of the semiconductor device, and for example, about 150 μm square is selected.
On the other hand, the width of the signal wiring on the mounting substrate side is, for example, about 80 μm (2 μm thick Au wiring) with a reference 50Ω microstrip line in a GaAs substrate with a thickness of 110 μm.
Therefore, the bonding pad becomes as small as 35Ω with respect to the 50Ω signal wiring on the mounting substrate, impedance mismatch occurs between the signal wiring and the bonding pad, and reflection occurs.

上記従来技術の欠点を解決するために、特許文献１では、ボンディングバッドに１／４λのショートスタブを付加した高周波回路基板を提案している。
図１３は第１の誘電体基板と第２の誘電体基板をフリップチップ実装した高周波回路基板の従来例を示す平面図である。図１４は図１３の高周波回路基板の断面図である。
図１３及び図１４において、高周波回路基板は第１の誘電体基板１ｃと第２の誘電体基板１ｅをバンプ１ｈを用いてフリップチップ実装している。この従来例では、バンプ接続による周波数特性の劣化を、導体パッド１ｆに１／４λショーツスタブ１ｉを付加し、その共振を利用することにより防止し、周波数特性を改善している。
特開２００４−１１２４２６公報 In order to solve the above-described drawbacks of the prior art, Patent Document 1 proposes a high-frequency circuit board in which a 1 / 4λ short stub is added to a bonding pad.
FIG. 13 is a plan view showing a conventional example of a high-frequency circuit board in which a first dielectric substrate and a second dielectric substrate are flip-chip mounted. 14 is a cross-sectional view of the high-frequency circuit board of FIG.
In FIG. 13 and FIG. 14, the high-frequency circuit board has a first dielectric substrate 1c and a second dielectric substrate 1e flip-chip mounted using bumps 1h. In this conventional example, deterioration of frequency characteristics due to bump connection is prevented by adding a 1 / 4λ shorts stub 1i to the conductor pad 1f and utilizing the resonance, thereby improving the frequency characteristics.
JP 2004-112426 A

しかし、従来例では、１／４λショートスタブを利用するため、基板面積が増大し、更に共振周波数付近でしか良好な特性が得られないため、広帯域で良好な高周波特性を実現することが困難であった。
以上説明したように、従来の高周波回路基板においては、信号配線とボンディングパッド間のインピーダンス不整合による反射損失を広帯域に亘り整合することができなかった。
高周波回路モジュールでは、薄型化・小型化の要求から配線の細線化が進むのに対して、高周波部品は検査や実装歩留まりを考慮して、ボンディングパッドは１００μｍ角程度と大きい。そのため、配線とボンディングパッドの特性インピーダンスの不整合は、より深刻な問題となっている。
そこで、本発明の目的は、ボンディングパッドの幅を信号配線幅より広く、ボンディングパッドの特性インピーダンスを信号配線の特性インピーダンスに等しくして、小型で広帯域な周波数帯で低反射損失を実現できる高周波回路基板を提供することにある。 However, since the conventional example uses a 1 / 4λ short stub, the substrate area increases, and good characteristics can be obtained only near the resonance frequency, so it is difficult to realize good high frequency characteristics in a wide band. there were.
As described above, in the conventional high-frequency circuit board, the reflection loss due to the impedance mismatch between the signal wiring and the bonding pad could not be matched over a wide band.
In a high-frequency circuit module, thinning of wiring has been advanced due to demands for thinning and miniaturization. On the other hand, a high-frequency component has a large bonding pad of about 100 μm square in consideration of inspection and mounting yield. Therefore, the mismatch of the characteristic impedance between the wiring and the bonding pad is a more serious problem.
Accordingly, an object of the present invention is to provide a high-frequency circuit capable of realizing a low reflection loss in a small and wide frequency band by making the bonding pad width wider than the signal wiring width and making the characteristic impedance of the bonding pad equal to the characteristic impedance of the signal wiring. It is to provide a substrate.

上記の課題を解決するために、請求項１に記載の発明は、信号配線及び接地配線からなる伝送線路が形成されており、前記信号配線の一部にはボンディングパッドが形成されている高周波回路基板において、前記ボンディングパッドの幅は前記信号配線の幅より広く、前記ボンディングパッドの特性インピーダンスは前記信号配線の特性インピーダンスに等しいことを特徴とする。
請求項２の発明は、請求項１において、前記ボンディングパッドは、接続される前記信号配線の幅よりも狭い幅で接触し、それ以外のボンディングパッド領域は前記高周波回路基板面から浮いていることを特徴とする。
請求項３の発明は、請求項１、又は２において、前記ボンディングパッド部の一部は、接続される前記信号配線の幅よりも狭い幅で接触し、それ以外のボンディングパッド領域は前記高周波回路基板面に配置した低誘電率材料表面に延伸されていることを特徴とする。
請求項４の発明は、請求項１、２、又は３において、前記低誘電率材料がポリイミドなどの有機系誘電体材料であることを特徴とする。
請求項５の発明は、請求項１、２、又は３において、前記低誘電率材料がシリコン酸化膜あるいはシリコン窒化膜などの無機系誘電体材料であることを特徴とする。
請求項６の発明は、請求項１において、前記伝送線路はマイクロストリップ線路であることを特徴とする。
請求項７の発明は、請求項１において、前記ボンディングパッド直下の高周波回路基板の厚さを他の部分よりも厚くしたことを特徴とする。
請求項８の発明は、請求項６、又は７において、前記伝送線路はコプレーナ線路であることを特徴とする記載の。
請求項９請求項１乃至８の何れか一項において、前記高周波回路基板に複数の半導体高周波部品をフリップチップ実装してなることを特徴とする。 In order to solve the above problems, the invention according to claim 1 is a high-frequency circuit in which a transmission line including a signal wiring and a ground wiring is formed, and a bonding pad is formed in a part of the signal wiring. In the substrate, the bonding pad is wider than the signal wiring, and the characteristic impedance of the bonding pad is equal to the characteristic impedance of the signal wiring.
According to a second aspect of the present invention, in the first aspect, the bonding pad is in contact with a width narrower than the width of the signal wiring to be connected, and the other bonding pad region is floating from the surface of the high-frequency circuit board. It is characterized by.
According to a third aspect of the present invention, in the first or second aspect, a part of the bonding pad portion contacts with a width narrower than a width of the signal wiring to be connected, and the other bonding pad region is the high-frequency circuit. It is characterized by being stretched on the surface of a low dielectric constant material disposed on the substrate surface.
According to a fourth aspect of the present invention, in the first, second, or third aspect, the low dielectric constant material is an organic dielectric material such as polyimide.
According to a fifth aspect of the present invention, in the first, second, or third aspect, the low dielectric constant material is an inorganic dielectric material such as a silicon oxide film or a silicon nitride film.
The invention of claim 6 is characterized in that, in claim 1, the transmission line is a microstrip line.
A seventh aspect of the invention is characterized in that, in the first aspect, the thickness of the high-frequency circuit board immediately below the bonding pad is made thicker than other portions.
According to an eighth aspect of the present invention, in the sixth or seventh aspect, the transmission line is a coplanar line.
9. The semiconductor device according to claim 1, wherein a plurality of semiconductor high-frequency components are flip-chip mounted on the high-frequency circuit board.

本発明によれば、特性インピーダンスの小さいボンディングパッド部を信号配線の特性インピーダンスに一致させることで、反射損失を低減させ、良好な高周波特性を実現できる効果がある。   According to the present invention, the bonding pad portion having a small characteristic impedance is matched with the characteristic impedance of the signal wiring, so that there is an effect that the reflection loss can be reduced and good high frequency characteristics can be realized.

以下、図面を参照して、本発明の実施の形態を詳細に説明する。本発明の高周波回路基板の特徴は、従来と同程度のボンディングパッド面積を確保しつつ、信号配線とボンディングパッドの特性インピーダンスを一致させることが可能なボンディングパッド構造を有することにある。
伝送線路では、その特性インピーダンスＺｏは式１で表わせる。

Figure 2007019439
・・・・ 式１
ここで、Ｌは単位長さ当たりのインダクタンス、Ｃは単位長さ当たりのキャパシタンスである。
式１によれば、幅が広いために特性インピーダンスの小さいボンディングパッド部を５０Ωに一致させるためには、キャパシタンス分を小さくすればよいことが分かる。以下に、本発明の実施の形態を使って、ボンディングパッド部のキャパシタンス成分を制御する制御手段を説明する。
図１は本発明による高周波回路基板のボンディングパッド構造の第１の実施の形態を示す平面図である。図２は図１の線Ａ−Ａ’でのボンディングパッド構造の断面図である。図１及び図２において、高周波回路基板１には厚さ１１０μｍの半絶縁ＧａＡｓ基板を使用する。
このボンディングパッド構造において、伝送線路にはマイクロストリップ線路を採用し、高周波回路基板１の裏面には接地配線２、表面には信号配線３が形成されている。厚さ１１０μｍのＧａＡｓ（εｒ＝１３）基板では、特性インピーダンス５０Ωの信号配線３の線幅は約８０μｍとなる。
信号配線３の一端あるいはその一部には、半導体高周波部品のチップインダクタ、チップキャパシタ、さらにはアクティブデバイスのダイオード、ＭＭＩＣなどのベアチップをダイボンディングするためのボンディングパッド４が形成されている。
実装部品のボンディングパッドの縦横サイズを１００μｍ×１００μｍ程度とした場合、高周波回路基板１のボンディングパッド４の形状としては、実装歩留まりを考えて、それよりも大きめの１５０μｍ×１５０μｍの縦横サイズに形成する。
そしてそのボンディングパッド４の一部は高周波回路基板１から浮いた構造とすることで、ボンディングパッド４のキャパシタンス成分を低減し、その特性インーダンスを５０Ωに調整している。
より具体的に説明すれば、図１及び図２のボンディングパッド４では、中央部４ａ（６０μｍ）はＧａＡｓ基板１と接触させ、中央部４ａの両サイドに延びるパッド領域４ｂはＧａＡｓ基板１から１０μｍ程度基板表面から浮かせることで、ボンディングパッド４のキャパシタンス成分を減少させ、ほぼ特性インピーダンスを５０Ωに調整することを可能にしている。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The high-frequency circuit board according to the present invention is characterized in that it has a bonding pad structure capable of matching the characteristic impedances of the signal wiring and the bonding pad while ensuring a bonding pad area comparable to that of the prior art.
In the transmission line, the characteristic impedance Zo can be expressed by Equation 1.
Figure 2007019439
.... Formula 1
Here, L is an inductance per unit length, and C is a capacitance per unit length.
According to Equation 1, since the width is wide, in order to match the bonding pad portion having a small characteristic impedance to 50Ω, it is necessary to reduce the capacitance. Hereinafter, control means for controlling the capacitance component of the bonding pad portion will be described using the embodiment of the present invention.
FIG. 1 is a plan view showing a first embodiment of a bonding pad structure of a high-frequency circuit board according to the present invention. FIG. 2 is a cross-sectional view of the bonding pad structure taken along line AA ′ of FIG. 1 and 2, the high-frequency circuit substrate 1 is a semi-insulating GaAs substrate having a thickness of 110 μm.
In this bonding pad structure, a microstrip line is employed for the transmission line, and a ground wiring 2 is formed on the back surface of the high-frequency circuit board 1 and a signal wiring 3 is formed on the front surface. In a GaAs (εr = 13) substrate having a thickness of 110 μm, the line width of the signal wiring 3 having a characteristic impedance of 50Ω is about 80 μm.
A bonding pad 4 for die-bonding a chip inductor, a chip capacitor of a semiconductor high-frequency component, a diode of an active device, or a bare chip such as an MMIC is formed at one end or a part of the signal wiring 3.
When the vertical and horizontal sizes of the bonding pads of the mounting component are about 100 μm × 100 μm, the shape of the bonding pads 4 of the high-frequency circuit board 1 is formed in a larger vertical and horizontal size of 150 μm × 150 μm, considering the mounting yield. .
A part of the bonding pad 4 is lifted from the high-frequency circuit board 1 to reduce the capacitance component of the bonding pad 4 and adjust the characteristic impedance to 50Ω.
More specifically, in the bonding pad 4 of FIGS. 1 and 2, the central portion 4a (60 μm) is brought into contact with the GaAs substrate 1, and the pad region 4b extending on both sides of the central portion 4a is 10 μm from the GaAs substrate 1. By floating from the substrate surface to some extent, the capacitance component of the bonding pad 4 can be reduced and the characteristic impedance can be adjusted to approximately 50Ω.

図３は高周波回路基板上に、ボンディングパッド部と半田バンプ、ＭＭＩＣを含む他の高周波回路基板などを搭載した状態を示す斜視図である。図４は図３の状態の断面図である。
高周波回路基板１のボンディングパッド４上に、半田バンプ５を介してＭＭＩＣを含む他の高周波回路基板６などをバンプ実装している。
本発明によれば、従来とほぼ同じ平面積を有するボンディングパッド４であっても、反射損失の少ない高周波回路基板を提供できる。図３及び図４には、図１及び図２と同様に、接地配線２、信号配線３、ボンディングパッド４の中央部４ａ、それ以外のパッド領域４ｂが示してある。
本発明のボンディングパッド構造の効果を確認するために、直径９０μｍ、高さ２０μｍのバンプで２つの基板を接続した場合の高周波特性（Ｓ１１）を測定した。 FIG. 3 is a perspective view showing a state where a bonding pad portion, a solder bump, another high frequency circuit board including an MMIC, and the like are mounted on the high frequency circuit board. 4 is a cross-sectional view of the state of FIG.
On the bonding pad 4 of the high-frequency circuit board 1, another high-frequency circuit board 6 including the MMIC is bump-mounted via a solder bump 5.
According to the present invention, it is possible to provide a high-frequency circuit board with little reflection loss even if the bonding pad 4 has almost the same plane area as the conventional one. 3 and 4, similarly to FIGS. 1 and 2, the ground wiring 2, the signal wiring 3, the central portion 4 a of the bonding pad 4, and the other pad region 4 b are shown.
In order to confirm the effect of the bonding pad structure of the present invention, the high frequency characteristics (S11) when two substrates were connected with bumps having a diameter of 90 μm and a height of 20 μm were measured.

図５はボンディングパッド構造による反射損失の測定結果を示す特性図である。図には、従来の構造の高周波特性も示している。図に示すように、本発明の高周波回路基板は従来よりも低反射損失であることが確認できた。
第１の実施の形態では、基板材料としてＧａＡｓ基板を用いた例を説明したが、本発明にて使用する回路基板は、ＧａＡｓ基板に限定されるものではない。他の誘電体材料、例えばシリコンあるいはテフロン（登録商標）など有機系誘電体材料を使っても、同様な効果を得られることは明らかである。 FIG. 5 is a characteristic diagram showing a measurement result of reflection loss by the bonding pad structure. The figure also shows the high-frequency characteristics of the conventional structure. As shown in the figure, it was confirmed that the high-frequency circuit board of the present invention had a lower reflection loss than before.
In the first embodiment, an example in which a GaAs substrate is used as the substrate material has been described. However, the circuit substrate used in the present invention is not limited to a GaAs substrate. It is clear that the same effect can be obtained by using another dielectric material, for example, an organic dielectric material such as silicon or Teflon (registered trademark).

図６は本発明による高周波回路基板のボンディングパッド構造の第２の実施の形態を示す平面図である。図７は図６の線Ａ−Ａ’でのボンディングパッド構造の断面図である。
本発明の第２の実施の形態では、ボンディングパッド４の機械的強度を高めるために、パッド両端の直下に高周波回路基板１よりも誘電率の低い低誘電体材料から成るポリイミド７を配置した構造としている。
ポリイミド（低誘電体材料）７は誘電率が３．５とＧａＡｓ基板１より小さいので、ボンディングパッド４をポリイミド７上まで延長形成したとしても、キャパシタンス成分は減少し、特性インピーダンスを制御することが可能である。図６及び図７には、図１及び図２と同様に、接地配線２、信号配線３、ボンディングパッド４の中央部４ａ、それ以外のパッド領域４ｂが示してある。
本実施の形態では、ボンディングパッド４の一部直下に高周波回路基板１の誘電率よりも小さい誘電率を有した他の低誘電体材料を配置すれば、同様な効果が得られることは言うまでもない。例えば、シリコン酸化膜またはシリコン窒化膜などの他の低誘電体材料が使用できる。
本実施形態では、低誘電率材料がポリイミドなどの有機系誘電体材料であるために、機械的強度に優れた信頼性の高い低反射の高周波回路基板を提供でき、また、シリコン酸化膜あるいはシリコン窒化膜などの無機系誘電体材料であるために、機械的強度に優れた信頼性の高い低反射の高周波回路基板を提供できる効果がある。
ボンディングパッド４は、その中央部において、接続される信号配線３の幅よりも狭い幅で高周波回路基板１と接触し、それ以外のボンディングパッド領域は基板１より低誘電率材料７の表面に延伸することで特性インピーダンスが制御できるため、反射損失の少ない高周波回路基板を提供できる効果がある。 FIG. 6 is a plan view showing a second embodiment of the bonding pad structure of the high-frequency circuit board according to the present invention. FIG. 7 is a cross-sectional view of the bonding pad structure taken along line AA ′ of FIG.
In the second embodiment of the present invention, in order to increase the mechanical strength of the bonding pad 4, a structure in which a polyimide 7 made of a low dielectric material having a dielectric constant lower than that of the high-frequency circuit board 1 is disposed immediately below both ends of the pad. It is said.
Since polyimide (low dielectric material) 7 has a dielectric constant of 3.5 and is smaller than GaAs substrate 1, even if bonding pad 4 is extended to polyimide 7, the capacitance component is reduced and the characteristic impedance can be controlled. Is possible. 6 and 7 show the ground wiring 2, the signal wiring 3, the central portion 4 a of the bonding pad 4, and the other pad region 4 b as in FIGS. 1 and 2.
In the present embodiment, it is needless to say that the same effect can be obtained if another low dielectric material having a dielectric constant smaller than that of the high frequency circuit board 1 is arranged immediately below a part of the bonding pad 4. . For example, other low dielectric materials such as a silicon oxide film or a silicon nitride film can be used.
In this embodiment, since the low dielectric constant material is an organic dielectric material such as polyimide, it is possible to provide a high-reliability, low-reflection high-frequency circuit board with excellent mechanical strength, and a silicon oxide film or silicon Since it is an inorganic dielectric material such as a nitride film, there is an effect that it is possible to provide a highly reliable low-reflection high-frequency circuit board having excellent mechanical strength.
The bonding pad 4 is in contact with the high-frequency circuit board 1 with a width narrower than the width of the signal wiring 3 to be connected at the center thereof, and the other bonding pad region extends to the surface of the low dielectric constant material 7 from the substrate 1. By doing so, since the characteristic impedance can be controlled, there is an effect that it is possible to provide a high-frequency circuit board with little reflection loss.

図８は本発明による高周波回路基板の第３の実施の形態を示す平面図である。図に示すように、高周波回路基板１の伝送線路にコプレーナ線路を採用しても、信号配線３とボンディングパッド４の特性インピーダンスを一致させることができる。
高周波実装基板１として、厚さ１１０μｍの半絶縁ＧａＡｓ基板を採用し、信号配線３の幅ｗ１を第１の実施の形態と同じ８０μｍとすれば、信号配線３と接地配線２間の距離ｇ１は５５μｍとなる。
ボンディングパッド４の幅ｗ２は１５０μｍであるから、５０Ωの特性インピーダンスを実現するためには、ボンディングパッド４と接地配線２とのギャップｇ２は８０μｍに設定すればよい。
コプレーナ線路を用いれば、ボンディングパッド４の端を浮かせることなく、信号配線３の線幅ｗ１と接地配線２間のギャップｇ１を調整するだけで、特性インピーダンスを制御することが可能で、ボンディングパッド形成が容易になる利点がある。
伝送線路はコプレーナ線路とし、配線幅と接地導体間ギャップを適切に設定することによって、任意にその特性インピーダンスを制御することが可能であり、設計自由度の高い低損失の高周波回路基板１を提供することができる。
本実施の形態では、伝送線路としてコプレーナ線路を使って説明したが、グランド付きコプレーナ線路を使用しても同様の効果が得られることは言うまでもない。 FIG. 8 is a plan view showing a third embodiment of the high-frequency circuit board according to the present invention. As shown in the figure, even when a coplanar line is adopted as the transmission line of the high-frequency circuit board 1, the characteristic impedance of the signal wiring 3 and the bonding pad 4 can be matched.
If a 110 μm thick semi-insulating GaAs substrate is used as the high frequency mounting substrate 1 and the width w1 of the signal wiring 3 is 80 μm, the same as in the first embodiment, the distance g1 between the signal wiring 3 and the ground wiring 2 is 55 μm.
Since the width w2 of the bonding pad 4 is 150 μm, the gap g2 between the bonding pad 4 and the ground wiring 2 may be set to 80 μm in order to realize a characteristic impedance of 50Ω.
If the coplanar line is used, the characteristic impedance can be controlled by adjusting the gap g1 between the line width w1 of the signal wiring 3 and the ground wiring 2 without lifting the end of the bonding pad 4, and the bonding pad formation There is an advantage that becomes easier.
The transmission line is a coplanar line, and by appropriately setting the wiring width and the gap between the ground conductors, the characteristic impedance can be arbitrarily controlled, and a low-loss high-frequency circuit board 1 with high design flexibility is provided. can do.
Although the present embodiment has been described using a coplanar line as a transmission line, it goes without saying that the same effect can be obtained even if a coplanar line with a ground is used.

図９は本発明による高周波回路基板のボンディングパッド構造の第４の実施の形態を示す平面図である。図１０は図９のボンディングパッド構造の断面図である。図９及び図１０に示す第４の実施の形態では、ボンディングパッド４の特性インピーダンスを制御する方法として、ボンディングパッド４直下に基板１よりも低誘電率の材料９を配置する構造を提案する。
厚さ１１０μｍの半絶縁ＧａＡｓ基板を使用し、伝送線路としてマイクロストリップ線路を採用した高周波回路基板１において、ボンディングパッド４の特性インピーダンスを５０Ωに調整するために、ボンディングパッド４直下の基板１を所定の深さ分除去した凹所１ａを形成する。
この凹所１ａ内に基板１よりも低誘電率のポリイミド層９を配置し、実効的な誘電率を下げている。その結果、ボンディングパッド部の特性インピーダンスは増加し、信号配線３の特性インピーダンスに一致させることができる。
高周波回路基板１は、伝送線路にマイクロストリップ線路を採用し、かつボンディングパッド４直下の基板１に設けた凹所内に低誘電率材料を配置することにより、特性インピーダンスを制御している。図１０において、符号２は接地配線を示している。
本構造では、ボンディングパッド４は基板１から浮かせること無く、その製造プロセスを簡略化でき、低コストで低反射損失の高周波回路基板を提供できる効果がある。 FIG. 9 is a plan view showing a fourth embodiment of the bonding pad structure of the high-frequency circuit board according to the present invention. 10 is a cross-sectional view of the bonding pad structure of FIG. In the fourth embodiment shown in FIGS. 9 and 10, as a method for controlling the characteristic impedance of the bonding pad 4, a structure is proposed in which a material 9 having a dielectric constant lower than that of the substrate 1 is disposed immediately below the bonding pad 4.
In a high-frequency circuit board 1 using a semi-insulating GaAs substrate having a thickness of 110 μm and adopting a microstrip line as a transmission line, the substrate 1 immediately below the bonding pad 4 is predetermined in order to adjust the characteristic impedance of the bonding pad 4 to 50Ω. A recess 1a is formed by removing the depth of.
A polyimide layer 9 having a lower dielectric constant than that of the substrate 1 is disposed in the recess 1a to lower the effective dielectric constant. As a result, the characteristic impedance of the bonding pad portion increases and can be matched with the characteristic impedance of the signal wiring 3.
The high frequency circuit board 1 employs a microstrip line as a transmission line, and controls the characteristic impedance by disposing a low dielectric constant material in a recess provided in the board 1 immediately below the bonding pad 4. In FIG. 10, reference numeral 2 denotes a ground wiring.
In this structure, the bonding pad 4 does not float from the substrate 1, the manufacturing process can be simplified, and a high-frequency circuit substrate with low reflection loss and low reflection loss can be provided.

図１１は本発明による高周波回路基板のボンディングパッド構造の第５の実施の形態を示す平面図である。図１２は図１１の高周波回路基板の断面図である。図１１及び図１２において、ボンディングパッド４の特性インピーダンスを制御する方法として、高周波回路基板１の厚さを変える方法を提案する。
高周波実装基板１には厚さ１１０μｍの半絶縁ＧａＡｓ基板を使用し、伝送線路としてマイクロストリップ線路を採用している。この高周波回路基板１において、ボンディングパッド４直下の基板１ａの厚さを２１０μｍと厚くすることで、特性インピーダンスを５０Ωに制御している。
高周波回路基板１は、伝送線路にマイクロストリップ線路を採用し、かつボンディングパッド４直下の基板１を信号配線３よりも厚くすることで、特性インピーダンスを制御している。図１０において、符号２は基板裏面に設けた接地配線を示している。
本発明によれば、高周波回路基板１に複数の半導体高周波部品をフリップチップ実装することができる。第１の実施の形態の高周波回路基板１に半導体高周波部品をフリップチップ実装するため、従来よりも低反射損失の高周波モジュールを提供することができる効果がある。
以上、本発明の効果を、ＭＭＩＣなどの高周波部品を実装する高周波回路基板のボンディングパッドを例に説明したが、本発明の効果は、ＭＭＩＣを含む半導体デバイスのボンディングパッド構造にも適用することができる。 FIG. 11 is a plan view showing a fifth embodiment of the bonding pad structure of the high-frequency circuit board according to the present invention. 12 is a cross-sectional view of the high-frequency circuit board of FIG. In FIGS. 11 and 12, a method of changing the thickness of the high-frequency circuit board 1 is proposed as a method of controlling the characteristic impedance of the bonding pad 4.
The high frequency mounting substrate 1 uses a semi-insulating GaAs substrate having a thickness of 110 μm and employs a microstrip line as a transmission line. In the high-frequency circuit board 1, the characteristic impedance is controlled to 50Ω by increasing the thickness of the substrate 1a immediately below the bonding pad 4 to 210 μm.
The high-frequency circuit board 1 employs a microstrip line as a transmission line, and the characteristic impedance is controlled by making the board 1 immediately below the bonding pad 4 thicker than the signal wiring 3. In FIG. 10, reference numeral 2 denotes a ground wiring provided on the back surface of the substrate.
According to the present invention, a plurality of semiconductor high-frequency components can be flip-chip mounted on the high-frequency circuit board 1. Since the semiconductor high-frequency component is flip-chip mounted on the high-frequency circuit board 1 of the first embodiment, there is an effect that it is possible to provide a high-frequency module having a lower reflection loss than the conventional one.
As described above, the effect of the present invention has been described using the bonding pad of the high frequency circuit board on which the high frequency component such as the MMIC is mounted as an example. However, the effect of the present invention can be applied to the bonding pad structure of the semiconductor device including the MMIC. it can.

本発明による高周波回路基板のボンディングパッド構造の第１の実施の形態を示す平面図である。It is a top view which shows 1st Embodiment of the bonding pad structure of the high frequency circuit board by this invention. 図１の線Ａ−Ａ’でのボンディングパッド構造の断面図である。It is sectional drawing of the bonding pad structure in line A-A 'of FIG. 高周波回路基板のボンディングパッド部と半田バンプ、ＭＭＩＣを含む他の高周波回路基板などをバンプ実装した状態を示す斜視図である。It is a perspective view which shows the state which carried out bump mounting of the bonding pad part of a high frequency circuit board, a solder bump, another high frequency circuit board containing MMIC, etc. 図３のバンプ実装した状態の断面図である。FIG. 4 is a cross-sectional view of the bump mounted state of FIG. 3. ボンディングパッド構造の効果の測定結果を示す特性図である。It is a characteristic view which shows the measurement result of the effect of a bonding pad structure. 本発明による高周波回路基板のボンディングパッド構造の第２の実施の形態を示す平面図である。It is a top view which shows 2nd Embodiment of the bonding pad structure of the high frequency circuit board by this invention. 図６の線Ａ−Ａ’でのボンディングパッド構造の断面図である。FIG. 7 is a cross-sectional view of the bonding pad structure taken along line A-A ′ of FIG. 6. 本発明による高周波回路基板の第３の実施の形態を示す平面図である。It is a top view which shows 3rd Embodiment of the high frequency circuit board by this invention. 本発明による高周波回路基板のボンディングパッド構造の第４の実施の形態を示す平面図である。It is a top view which shows 4th Embodiment of the bonding pad structure of the high frequency circuit board by this invention. 図９のボンディングパッド構造の断面図である。FIG. 10 is a cross-sectional view of the bonding pad structure of FIG. 9. 本発明による高周波回路基板のボンディングパッド構造の第５の実施の形態を示す平面図である。It is a top view which shows 5th Embodiment of the bonding pad structure of the high frequency circuit board by this invention. 図１１のボンディングパッド構造の断面図である。It is sectional drawing of the bonding pad structure of FIG. 第１の誘電体基板と第２の誘電体基板をフリップチップ実装した高周波回路基板の従来例を示す平面図である。It is a top view which shows the prior art example of the high frequency circuit board which carried out the flip chip mounting of the 1st dielectric substrate and the 2nd dielectric substrate. 図１３の高周波回路基板の断面図である。It is sectional drawing of the high frequency circuit board of FIG.

符号の説明Explanation of symbols

１ 高周波回路基板（基板）
１ａ ボンディングパッド４直下の基板（厚さ）
２ 伝送線路（接地配線）
３ 伝送線路（信号配線）
４ ボンディングパッド
４ａ ボンディングパッド中央部
４ｂ ボンディングパッド延伸部
５ バンプ
６ 他の高周波回路基板
７ 低誘電体材料（ポリイミド）
９ 低誘電体材料（ポリイミド） 1 High-frequency circuit board (substrate)
1a Substrate directly under bonding pad 4 (thickness)
2 Transmission line (ground wiring)
3 Transmission line (signal wiring)
4 Bonding pad 4a Bonding pad center 4b Bonding pad extension 5 Bump 6 Other high frequency circuit board 7 Low dielectric material (polyimide)
9 Low dielectric material (polyimide)

Claims (9)

信号配線及び接地配線からなる伝送線路が形成されており、前記信号配線の一部にはボンディングパッドが形成されている高周波回路基板において、前記ボンディングパッドの幅は前記信号配線の幅より広く、前記ボンディングパッドの特性インピーダンスは前記信号配線の特性インピーダンスに等しいことを特徴とする高周波回路基板。   In the high-frequency circuit board in which a transmission line including a signal wiring and a ground wiring is formed, and a bonding pad is formed on a part of the signal wiring, the bonding pad is wider than the signal wiring, The high frequency circuit board according to claim 1, wherein the characteristic impedance of the bonding pad is equal to the characteristic impedance of the signal wiring. 前記ボンディングパッドは、接続される前記信号配線の幅よりも狭い幅で接触し、それ以外のボンディングパッド領域は前記高周波回路基板面から浮いていることを特徴とする請求項１記載の高周波回路基板。   2. The high frequency circuit board according to claim 1, wherein the bonding pads are in contact with each other with a width narrower than a width of the signal wiring to be connected, and other bonding pad regions are floating from the surface of the high frequency circuit board. . 前記ボンディングパッド部の一部は、接続される前記信号配線の幅よりも狭い幅で接触し、それ以外のボンディングパッド領域は前記高周波回路基板面に配置した低誘電率材料表面に延伸されていることを特徴とする請求項１、又は２に記載の高周波回路基板。   A part of the bonding pad portion contacts with a width narrower than the width of the signal wiring to be connected, and the other bonding pad region is extended to the surface of the low dielectric constant material disposed on the surface of the high frequency circuit board. The high frequency circuit board according to claim 1, wherein the high frequency circuit board is provided. 前記低誘電率材料がポリイミドなどの有機系誘電体材料であることを特徴とする請求項１、２又は３に記載の高周波回路基板。   4. The high frequency circuit board according to claim 1, wherein the low dielectric constant material is an organic dielectric material such as polyimide. 前記低誘電率材料がシリコン酸化膜あるいはシリコン窒化膜などの無機系誘電体材料であることを特徴とする請求項１、２、又は３に記載の高周波回路基板。   4. The high frequency circuit board according to claim 1, wherein the low dielectric constant material is an inorganic dielectric material such as a silicon oxide film or a silicon nitride film. 前記伝送線路はマイクロストリップ線路であることを特徴とする請求項１に記載の高周波回路基板。   The high-frequency circuit board according to claim 1, wherein the transmission line is a microstrip line. 前記ボンディングパッド直下の高周波回路基板の厚さを他の部分よりも厚くしたことを特徴とする請求項１記載の高周波回路基板。   2. The high frequency circuit board according to claim 1, wherein a thickness of the high frequency circuit board immediately below the bonding pad is made thicker than other portions. 前記伝送線路はコプレーナ線路であることを特徴とする請求項６、又は７に記載の高周波回路基板。   The high-frequency circuit board according to claim 6, wherein the transmission line is a coplanar line. 請求項１乃至８の何れか一項に記載の高周波回路基板に複数の半導体高周波部品をフリップチップ実装してなることを特徴とする高周波モジュール。   A high-frequency module comprising a plurality of semiconductor high-frequency components flip-chip mounted on the high-frequency circuit board according to claim 1.
JP2005202343A 2005-07-11 2005-07-11 High frequency circuit board and high frequency module Pending JP2007019439A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010177364A (en) * 2009-01-28 2010-08-12 Nippon Telegr & Teleph Corp <Ntt> Semiconductor package and packaging method thereof
US10224146B2 (en) 2015-10-23 2019-03-05 Kabushiki Kaisha Toshiba Inductive coupling system and communication system

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010177364A (en) * 2009-01-28 2010-08-12 Nippon Telegr & Teleph Corp <Ntt> Semiconductor package and packaging method thereof
US10224146B2 (en) 2015-10-23 2019-03-05 Kabushiki Kaisha Toshiba Inductive coupling system and communication system
US11139111B2 (en) 2015-10-23 2021-10-05 Kabushiki Kaisha Toshiba Inductive coupling system and communication system

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