JPH0445247Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) This invention relates to a monolithic microwave integrated circuit device used in equipment such as radar, communications, or broadcasting, and particularly relates to its hermetic sealing structure. This is an improved version.

(Prior Art) In recent years, various microwave integrated circuits such as amplifiers, oscillators, frequency converters, etc. are expected to be monolithic, which will allow the devices to be smaller and lighter, and will be cheaper to mass produce. However, when implementing a monolithic microwave integrated circuit, micropatterns such as semiconductor elements such as transistors and diodes, or interdigital capacitors, etc., and metal-insulator-metal structures (hereinafter referred to as MIM ) Capacitors etc. are environmentally resistant,
It must be hermetically sealed for long-term reliability.

Conventionally, therefore, a monolithic microwave integrated circuit has been assembled in a hermetically sealed envelope as shown in FIG. FIG. 4 shows a plan view, a side sectional view, and a longitudinal sectional view. 1 is a monolithic microwave integrated circuit chip, in which GaAs-
A MESFET (field effect transistor) 3 and a microstrip line 4 forming an input/output matching circuit are formed. Further, a ground conductor 5 is provided on the back surface of the GaAs substrate 2. A via hole 6 is used to connect this conductor 5 to the electrode 7 on the front side. 8 is an MIM capacitor, 9 is a high frequency input terminal, and 10 and 11 are bias supply terminals.
Furthermore, 12 is an envelope incorporating a monolithic microwave integrated circuit chip. This envelope 12 consists of a metal pedestal 13, a first layer insulator 14, a second layer insulator 15, and a metal lid 16.

The above monolithic microwave integrated circuit chip 1 is fixed inside an envelope 12 with AuSn solder or the like, and electrodes 17, 18, 19 provided on the upper surface of the first layer insulator 14, Terminal 9 on the top surface,
10, 11 means bonding wire, etc. 20, 2
1 and 22, respectively.

FIG. 5 shows an equivalent circuit of the above-mentioned high frequency circuit section. 1 is a monolithic microwave integrated circuit, in which a portion 26 surrounded by a broken line is a hermetically sealed portion, 231 and 232 are distributed constant lines of the input and output electrode portions of the envelope, and 24 and 25 are bonding wires, etc. It is inductance.

(Problem to be solved by the invention) When bonding the chip 1 in the above monolithic microwave integrated circuit, if there are no variations in its position or the length of the bonding wire, etc., the inductances 24, 25, etc. should be taken into consideration. All you have to do is design the circuit.

However, in reality, there are variations in the length and shape of bonding wires, and this effect is particularly large at high frequencies. Even if the return loss of a monolithic microwave integrated circuit chip is 20 dB, when it is incorporated into an envelope, the return loss is There were cases where the variation was ±10dB. In such a case, it may be necessary to make circuit adjustments to meet the required characteristics, and there is a problem in that the characteristic of monolithic microwave integrated circuits, which is low cost during mass production, is lost due to hermetic sealing.

Therefore, the present invention aims to provide a monolithic microwave integrated circuit device having a hermetically sealed structure that prevents electrical performance from deteriorating due to variations in dimensions and shapes between components that occur when hermetically sealing the circuit. purpose.

[Structure of the Invention] (Means for Solving the Problems) In this invention, a metal or insulator lid is directly fixed to the upper surface of a substrate on which field effect transistors, diodes, matching circuits, and bias circuits are integrally formed. This achieves the above objectives.

(Function) As mentioned above, this invention does not align and fix the chip in the envelope as in the past, but fixes the lid directly to the board, so the chip position and the envelope can be adjusted. There is no variation in electrical performance, and there is no deterioration in electrical performance.

(Example) An example of this invention will be described below with reference to the drawings.

Fig. 1 shows an embodiment of this invention, in which Fig. 1A is a plan view, Fig. 1B is an elevational view, and Fig. 1C is a side view. Further, FIG. D is a sectional view along AA, and E is a sectional view along BB. 1 is a monolithic microwave integrated circuit, and a field effect transistor 3, a microstrip line 4 forming an input/output matching circuit, etc. are provided on a GaAs insulating substrate 2 of this circuit. Further, a ground conductor 5 is provided on the back surface of the insulating substrate 2. When connecting the upper electrode 7 of the substrate 2 and the ground conductor 5, the via hole 6 is used. 8
is a metal-insulator-metal structure MIM capacitor,
9 is a high frequency input terminal, and 10 and 11 are bias supply terminals.

By the way, in the above-mentioned monolithic microwave integrated circuit, the parts to which high electric fields are input, such as the junctions of field effect transistors, fine pattern parts such as comb-shaped capacitors, and MIM capacitors for high frequency short circuits and DC blocking, are Dust may adhere to the
Since the characteristics change when the temperature is high, it is necessary to hermetically seal it to improve reliability and environmental resistance. However, the high frequency input/output terminals and bias supply terminals formed on the GaAs insulating substrate have large pattern dimensions and do not have a fine structure, so it is not necessarily necessary to completely hermetically seal them.

In this invention, attention has been paid to this fact, and a metal lid 16 is used to hermetically seal the semiconductor element or the fine pattern portion, and this is directly soldered to the metal pattern 27 on the top surface of the chip 1. In this way, the lid 16 itself can be treated as a component on the chip, and its position is accurate.

Regarding the high frequency input terminal 9 section, the first
As shown in FIG. E, an insulating film 28 is provided at the intersection of the high frequency input terminal 9 and the metal pattern 27 to prevent short circuits. Furthermore, in this structure, a transmission line is formed by the metal pattern 27 and the ground conductor 5,
This may cause resonance or feedback between input and output, which may make the monolithic microwave integrated circuit unstable. To prevent this, it is recommended to connect the metal pattern 27 to the ground conductor 5 through the via hole 29. It is valid.

Note that the metal pattern 27 is made larger than the soldering surface of the metal lid 16, and within this range, even if the soldering position varies, the electrical performance will not deteriorate.

FIG. 2 shows the high frequency equivalent circuit of FIG. 1. That is, 1 is a monolithic microwave integrated circuit, 30 and 31 are distributed number lines of input/output terminals on the top surface of the integrated circuit, and a portion 32 surrounded by a broken line is an airtightly sealed portion. In other words, the terminals on the top surface of the monolithic microwave integrated circuit chip directly serve as the input/output terminals of the hermetically sealed monolithic microwave integrated circuit. Therefore, compared to the conventional case where monolithic microwave integrated circuit chips are hermetically sealed in an envelope and interconnected using bonding wires, variations in size and shape are reduced, and the electrical performance associated with hermetically sealed packaging is reduced. The variation in can be made sufficiently small.

In the above embodiment, the hermetic sealing lid is made of metal, but as shown in FIG. 3, the lid 33 may be made of an insulator. That is, a lid 33 made of an insulating material such as ceramic is directly adhered to the top surface of the monolithic microwave integrated circuit with an insulating adhesive 34 to achieve an airtight seal. In this case, resonance and feedback due to the lid are less likely to occur, and the via hole 29 shown in the previous embodiment may be omitted.

[Effects of the invention] As explained above, according to this invention, the electrical performance does not deteriorate due to variations in size and shape caused by hermetically sealing, making it impossible to adjust the circuit, and reducing the cost during mass production. It is possible to obtain a device with an air-tight sealing mechanism that does not detract from the cost characteristic of monolithic microwave integrated circuits. Furthermore, since the number of parts is smaller than when using a hermetically sealed envelope, costs can also be reduced during mass production.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a configuration showing one embodiment of this invention, Fig. 2 is an equivalent circuit diagram of a monolithic microwave integrated circuit section of this invention, and Fig. 3 is an explanatory diagram of a configuration showing another embodiment of this invention. 4 are configuration explanatory diagrams showing the structure of a conventional monolithic microwave integrated circuit, and FIG. 5 is an equivalent circuit diagram of the monolithic microwave integrated circuit. 1... Monolithic microwave integrated circuit, 2...
...Insulating substrate, 3...Field effect transistor, 4...
...Microstrip line, 5...Ground conductor, 7
... Upper electrode, 6 ... Via hole, 8 ... Metal-insulator-metal structure (MIM) capacitor, 9 ...
... High frequency input terminal, 10, 11 ... Bias supply terminal, 16, 33 ... Lid, 27 ... Metal pattern, 28 ... Insulating film, 34 ... Adhesive.

Claims (1)

[Scope of utility model registration request] A monolithic microwave integrated circuit in which field effect transistors, diodes, matching circuits, and bias circuits are integrally formed on an insulating substrate such as GaAs, characterized in that a metal or insulating lid is directly fixed to the top surface of the substrate. Monolithic microwave integrated circuit device.