JP2681959B2 - Method for manufacturing semiconductor integrated circuit - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a semiconductor integrated circuit with crosstalk countermeasures.

[Conventional technology]

Conventionally, as a method for separating circuits of a semiconductor integrated circuit formed on one semiconductor substrate, a method of applying a reverse bias to a PN junction and a method of separating with a silicon oxide film or the like have been used. For example, FIGS. 4 (a) and 4 (b) are a plan view and a sectional view of an example thereof, in which different circuits 2 and 3 are formed on the main surface of one semiconductor substrate 1, respectively, and a thick circuit is formed between the two circuits. The oxide film 7 is formed to separate the circuits. The semiconductor integrated circuit is mounted on the package 8 at a predetermined position.

[Problems to be solved by the invention]

In the above-mentioned conventional semiconductor integrated circuit, when the frequency to be handled is up to several hundred MHz, no particular problem occurs in the circuit separation by means such as the oxide film separation described above.
However, in recent years, the operating frequency of semiconductor integrated circuits is several GHz.
Further, with the demand for several tens of GHz, crosstalk between circuits in a semiconductor integrated circuit chip has become a problem. That is, the above-mentioned PN junction separation and oxide film separation are separation methods on the circuit surface, and the underlying substrate (substrate) is common. For this reason, if the operating integrated circuit is in the GHz range or if the gain of the semiconductor integrated circuit is large, the amount of signal that wraps around the amplifier input through the substrate from the circuit with large operating amplitude cannot be ignored. This causes a disturbance in the signal waveform, and if it is remarkable, it causes oscillation.

As one means for solving this problem, the amplifier gain per semiconductor integrated circuit may be lowered. Further, a semiconductor integrated circuit having a large gain may be divided into two or more pieces to form an independent semiconductor integrated circuit, which is mounted on the same package and then connected by a bonding wire.

However, if the semiconductor integrated circuit is composed of two or more independent circuits, it is disadvantageous for mounting, and mounting two or more chips in the same package has problems in reliability and mass productivity. That is, when mounting the second chip, the brazing material of the already mounted chip may melt. Also, the mounting time is twice as long as one chip.

An object of the present invention is to provide a method for manufacturing a semiconductor integrated circuit, which can reduce the crosstalk in the semiconductor integrated circuit and improve the reliability and mass productivity of the semiconductor integrated circuit.

[Means for solving the problem]

A method of manufacturing a semiconductor integrated circuit according to the present invention includes a step of mounting a chip having a plurality of circuits formed on the front surface of the same semiconductor substrate on a package on the back surface thereof, and a surface of the semiconductor substrate between the circuits in the mounted state. The method includes a step of forming a groove having a required depth by irradiating a laser beam to separate both circuits, and a step of forming a wiring for electrically connecting both circuits.

[Action]

In this manufacturing method, the crosstalk between circuits is reduced by forming the groove, and the chip can be mounted on the package in one step.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining a first embodiment of the present invention, FIG. 1 (a) is a plan view, and FIG. 1 (b) is a sectional view taken along the line AA.

In this embodiment, first, a semiconductor integrated circuit chip having different circuits 2 and 3 formed on the main surface of one semiconductor substrate 1 is mounted on a package 8 using a brazing material.

Then, the semiconductor integrated circuit is selectively irradiated with a laser beam so that the depth between the circuits 2 and 3 is at least 5 μm.
The groove 4 described above is formed, and the two circuits 2 and 3 are separated by this groove 4. It is preferable to form the groove 4 at least deeper than the epitaxial layer or the like formed on the main surface of the semiconductor substrate 1.

Then, the bonding wire 5 is used for the circuit 2 and the circuit 3.
Are electrically connected.

In the semiconductor integrated circuit completed in this embodiment, the groove 4 formed between the circuit 2 and the circuit 3 reduces the crosstalk from the substrate 1 and increases the amount of crosstalk attenuation between the two circuits. . On the other hand, the semiconductor integrated circuit chip requires only one mounting step, and reliability and mass productivity can be improved.

FIG. 2 is a diagram for explaining the second embodiment of the present invention. FIG. 2A is a plan view, and FIGS. 2B and 2C are BB line and C in FIG. It is sectional drawing which follows the C line. In addition,
The same parts as those in FIG. 1 are denoted by the same reference numerals.

In this embodiment, after mounting the substrate 1 of the semiconductor integrated circuit chip on which the circuits 2 and 3 are formed in the package 8, the depth between the circuits 2 and 3 is 5 μm by the laser beam.
A groove 4A of m or more is formed to separate the two. At this time, the groove
A part of the portion where 4A is formed is left as a wiring 6 without forming a groove, and the wiring 6 electrically connects the circuits 2 and 3. Therefore, the bonding wire is unnecessary.

Also in this embodiment, if the width dimension of the wiring 6 is made as thin as possible, the crosstalk characteristics can be reduced to the same extent as in the first embodiment.

FIG. 3 is a diagram showing a third embodiment of the present invention, FIG. 3 (a) is a plan view, and FIG. 3 (b) is a sectional view taken along the line D-D.

In this embodiment, after mounting the semiconductor integrated circuit chip on the package 8, the circuit 2, 3 is utilized by using the laser beam.
Groove the groove 4B to be formed between the chips to the thickness of the chip,
It is completely divided into two at 3. After that, connecting the circuits 2 and 3 by the bonding wire 5 is the same as in the example of FIG.

In this embodiment, by dividing into two, the substrate 1 common to the circuits 2 and 3 becomes independent, and the crosstalk between the circuits 2 and 3 becomes almost zero. Further, in this case, mounting can be performed with higher reliability than mounting two independent chips, and the mounting process is not increased.

Further, in each of the first to third embodiments, when a groove is formed by a laser beam, dust such as silicon may adhere to the circuit surface, causing a problem such as a circuit short circuit. It is important to strengthen the protective film of the integrated circuit chip.

〔The invention's effect〕

As described above, the present invention includes the step of separating the two circuits by forming a groove having a required depth between the circuits formed on the chip, and thus the formation of the groove reduces crosstalk between the circuits. As a result, the crosstalk in the semiconductor integrated circuit chip can be reduced, and the coupling due to the input / output crosstalk can be reduced even in a high frequency operation such as several tens GHz, and a stable high gain can be obtained. Further, in the present invention, since the groove is formed in the chip by the laser beam in the state where the chip is mounted on the package, compared to a chip in which the circuit is separated by forming the groove in the chip before mounting, the external force applied during mounting causes The chip does not break in the groove. Further, in the present invention, when the chip is divided by the groove, one mounting step is required as compared with the case where a plurality of chips separated in advance are mounted. As a result, the reliability and mass productivity of the semiconductor integrated circuit can be improved, and further, the manufacturing yield can be increased.

[Brief description of the drawings]

1 shows a first embodiment of the present invention, FIG. 1 (a) is a plan view, FIG. 1 (b) is a sectional view taken along the line AA, and FIG. 2 shows a second embodiment of the present invention. The figure (a) is a plan view and the figure (b) is
Is a sectional view taken along the line BB, and FIG.
FIG. 3 shows a third embodiment of the present invention, FIG. 3 (a) is a plan view, FIG. 3 (b) is a sectional view taken along the line D-D, and FIG. Is a plan view, and FIG. 6B is a sectional view taken along the line EE. 1 ... Substrate, 2, 3 ... Circuit, 4, 4A, 4B ... Groove, 5 ... Bonding wire, 6 ... Wiring, 7 ... Thick oxide film, 8 ... Package.

Claims (1)

(57) [Claims] 1. A step of mounting a chip having a plurality of circuits formed on the surface of the same semiconductor substrate on a back surface of the chip in a package, and a groove having a required depth on the surface of the semiconductor substrate between the circuits in the mounted state. And a step of forming a wiring for electrically connecting the two circuits by irradiating a laser beam to separate the two circuits, and a method for manufacturing a semiconductor integrated circuit.