JPH07204876A - Device for drilling hole in protective film on ic surface and method for drilling hole by using the method - Google Patents

Abstract

PURPOSE:To provide a device and a method for safely and correctly drilling a hole in the protective film on the IC surface when a probe is brought into contact with the wiring pattern inside the IC and the test is carried out by an IC tester to realize the analysis of defects of the IC (integrated circuit of semi-conductor) in the wafer condition or in the chip condition. CONSTITUTION:A laser beam oscillator 11 of short pulse from 1ns to 5ns is provided, a film thickness measuring instrument 26 is provided in the optical path of the laser beam 12, and a control part to control emission intensity of the laser beam and the focal distance of an objective lens 15 according to the measured film thickness is provided. The film thickness on the IC surface is first measured, the emission intensity of the laser beam 12 and the focal distance of the objective lens 15 are set according to the film thickness, and the laser beam 12 is emitted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC (semiconductor integrated circuit) in a wafer state or a chip state, and in order to analyze a defect of the IC, it makes contact with a wiring pattern inside the IC with a needle and tests it with an IC tester. The present invention relates to an apparatus and method for making a hole in a protective film on an IC surface for applying a needle to a wiring pattern.

[0002]

2. Description of the Related Art In order to apply a needle to a wiring pattern inside an IC, it is necessary to peel off a minute portion of a protective film on the IC surface. there were. One means is a method of peeling the protective film by an etching technique performed in the process of manufacturing an IC. However, while it has been laborious to use etching techniques over large wafers, it has been difficult to do with one small chip.

As another means, there is a peeling method using a laser. There are a drilling device using a YAG laser and a photoablation processing method using an excimer laser. However, in the conventional device, the half width of the laser beam pulse is as large as about 50 ns, thermal damage is given to the periphery, the laser processing energy is not uniform, and the laser output is unstable. Since the pattern may be cut or the protective film may not be peeled on the contrary, there is no means for safely and surely peeling and punching the protective film.

[0004]

The present invention is based on the above-mentioned IC.
The purpose is to safely and surely open a protective film in a narrow area on the surface without cutting the wiring pattern.

[0005]

In order to achieve the above object, the present invention requires a short pulse laser beam having appropriate energy for the type and thickness of the protective film of each IC. It irradiates an area to explode on the surface of the metal thin film under the protective film of the IC, and peels off the protective film in a narrow area above it. The applicant previously filed Japanese Patent Application No. 4-2.
1159 (filed on August 7, 1992) discloses "laser processing device". The present invention is an application of the present invention.
C A device for punching a surface protective film.

FIG. 4 shows an example of the configuration. Reference numeral 11 in the figure denotes a laser oscillator. The half-width of the laser pulse of the conventional laser oscillator is often around 50 ns or more, and a laser beam with a narrow half-width has not been obtained, but recently, it has come to be obtained due to technological progress. In the present invention, a laser beam having a half width pulse of 1 ns to 5 ns is used.

A laser beam 12 emitted from a laser oscillator 11 is applied to an IC 17 through a mirror 13, a beam splitter 14 and an objective lens 15. IC17 is X
It is a structure that is mounted on the -Y moving table 16 and can irradiate the laser beam 12 to an arbitrary position of the IC 17 by moving the XY moving table 16.

The beam splitter 14 is a laser oscillator 11
A part of the incident laser beam 12 is branched, and a part of the branched laser beam 12 is received by the light receiving element 18 for measuring the incident light amount.
Give to. The photoelectric conversion output of the light receiving element 18 is given to the AD converter 21 through the buffer amplifier 19, AD-converted by the AD converter 21 and given to the control unit 22 to control the emitted light of the laser oscillator 11.

On the other hand, the beam splitter 14 splits the laser beam 12 reflected from the IC 17 through a beam splitter 29 into a light receiving element 23 for measuring the amount of reflected light, and gives an electric signal corresponding to the amount of reflected light to an AD converter 25, and the AD converter. The reflected light amount signal AD-converted by 25 is given to the control unit 22, and the emitted light amount of the laser oscillator 11 is also controlled by the reflected light.

The beam splitter 29 splits a part of the reflected light from the IC 17 and supplies it to the film thickness measuring device 26. As the film thickness measuring device 26, a device using a microscopic interference method or a device using extinction method ellipsometry has been put into practical use.
Further, a white light source 27 is provided above the mirror 13 to operate the film thickness measuring device 26. The white light source 27 is turned on before operating the film thickness measuring device 26. A half mirror is used as the mirror 13. Half mirror 13
The white light extracted by is given to the IC 17, and the reflected white light is split by the beam splitter 29 and given to the film thickness measuring device 26. The film thickness measurement value of the film thickness measuring device 26 is given to the control unit 22, and the intensity of the laser beam 12 emitted from the laser oscillator 11 is controlled according to the film thickness of the protective film H1 formed on the surface of the IC 17. .

【Example】

FIG. 1 shows a flow chart of an embodiment of the present invention, FIG. 2 shows an example of a pulse waveform of the laser beam 12, and FIG. 3 shows the laser beam 12 with which the IC 17 is irradiated. Figure 1
The embodiment will be described with a focus on the flowchart of FIG. First, the position where the IC17 surface protective film is to be drilled is determined. This is a natural step when performing laser processing, and is performed by fine adjustment of the XY moving table 16. Although not shown, the position may be determined by looking through the beam splitter with a microscope if necessary, or the precise XY moving table 16 may be used to control the CP.
It may be U-controlled.

After the positioning is completed, it is determined whether the emission intensity of the laser beam 12 has been set. In the case of the first emission, NO is set because the emission intensity is not set,
The film thickness of the protective film H1 on the surface of the IC 17 is measured. At this time, the white light source 27 is turned on, the white light is reflected by the IC 17, and the film thickness measuring device 26 measures the film thickness of the IC 17 surface protective film H1.

When the protective film thickness H1 is measured, the film thickness value is transmitted to the control unit 22, and the emission intensity of the laser beam 12 and the focal length of the objective lens 15 are set. As shown in FIG. 3, the focal length of the objective lens 15 is focused on the surface of the metal thin film wiring pattern L1 such as an aluminum thin film. Laser beam 12
This is because the energy of is concentrated on the surface of the metal thin film wiring pattern L1 and then explodes in a moment on the surface.

The emission intensity of the laser beam 12 is set by the type and thickness of the protective film H1. As described above, the half width of the laser beam 12 of the laser oscillator 11 is from 1 ns to 5
It is a short pulse with a half-value width up to ns, and there is no heat dispersion in the protective film H1 on the surface of the IC 17, and only a part of the surface of the irradiated metal thin film wiring pattern L1 and the protective film in a narrow range are concentrated in thermal energy It explodes and peels off. However, since the appropriate energy depends on the film thickness of the protective film H1 up to the surface of the metal thin film L1 and its type, the emission energy (pulse height) is controlled to emit the laser beam 12 having the appropriate energy. There must be.

When a suitable laser beam 12 is emitted, its energy concentrates on the surface of the metal thin film wiring pattern L1 in a short time, and an explosion phenomenon occurs instantly, and the protective film H in a narrow range is generated.
1 is peeled off. Since the metal thin film wiring pattern L1 has a high hardness, only a part of the surface is scraped.

When the emission of the first laser beam 12 is completed, it is determined whether or not there is a next hole. In general, it is necessary to provide a plurality of points in order to make a needle on the wiring inside the IC 17. Therefore, positioning is performed for the second drilling, and after the positioning is completed, the laser beam 12 is emitted in the same process to perform the second drilling. However,
In such a case, since the protective film H1 often has almost the same film thickness, the emission intensity is already set, and the measurement of the protective film thickness, the emission intensity of the laser beam, and the setting of the focal length of the objective lens are omitted. The laser beam may be emitted immediately. In this way, the drilling of a plurality of preset positions is completed and the work is completed.

[0017]

As described above, the present invention is an apparatus using a short-pulse laser beam, which has been difficult in the past.
Peeling in a narrow area of the protective film on the C surface enables safe and accurate drilling, and the effect is great.

[Brief description of drawings]

FIG. 1 is a flowchart of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a pulse waveform of a laser beam according to an example of the present invention.

FIG. 3 is an explanatory diagram of a laser beam with which an IC is irradiated.

FIG. 4 is a configuration diagram of an example previously disclosed by the applicant.

[Explanation of symbols]

 11 Laser Oscillator 12 Laser Beam 13 Mirror (Half Mirror) 14, 19 Beam Splitter 15 Objective Lens 16 XY Moving Stage 17 IC 18, 23 Light-Receiving Element 26 Film Thickness Meter H1 IC Surface Protection Film L1 Metal Thin Film Wiring Pattern

Claims (2)

[Claims] 1. A laser oscillator is provided, and a laser beam emitted from this laser oscillator is applied to the surface of the IC.
A hole piercing device for an IC surface protective film for peeling off a protective film on a C surface, wherein the laser oscillator has a pulse half width of 1 ns to 5 ns.
Is a laser oscillator (11) for oscillating a laser beam up to and including a film thickness measuring device (26) provided in the optical path of a beam reflected from the IC surface, and a film obtained by the measurement result of the film thickness measuring device (26). An IC surface protective film comprising: a control unit (22) for controlling the emission intensity of the laser beam (12) of the laser oscillator (11) and the focal length of the objective lens (15) according to the thickness. Drilling device. 2. An IC surface is provided with a laser oscillator, and a laser beam emitted from the laser oscillator is irradiated onto the IC surface.
In the method of drilling a protective film on the IC surface for peeling off the protective film on the C surface, the protective film thickness on the IC surface is measured, and a laser beam (12) with a half width of a pulse from 1 ns to 5 ns is emitted according to the film thickness. Intensity and objective lens (15)
A method of drilling a hole on the IC surface protective film in which the laser beam (12) is emitted after this setting and the protective film on the IC surface is peeled off.