JPH04336443A - Microscope - Google Patents

Abstract

PURPOSE:To provide a microscope which is capable of appropriately identifying a boundary between a semiconductor chip and gold pads, and which facilitates the setting of the brightness of the light source and levels used in binary decision by employing an infrared emission element as the light source. CONSTITUTION:A light receiving surface 21 of a television camera 2 is positioned at the image surface of the main body 1 of a microscope, and the bright-field or dark-field illumination of the object being captured is effected. Video signals of the television camera 2 are displayed on a monitor TV for visualization, or subjected to image processings. In such a microscope, an infrared emission element is used for the light source 3 which illuminates the object 5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microscope used to judge and inspect gold pad plating of semiconductor die bonds or semiconductor chips.

0002

2. Description of the Related Art FIGS. 4 and 5 are explanatory diagrams showing a conventional microscope. The microscope shown in FIG.
1 is arranged, and a light source 3 that emits light to the optical path of the microscope main body 1 is arranged. This microscope is a so-called bright field type microscope in which the light emitted from the light source 3 passes through the optical axis of the microscope optical system. Irradiate target) 5. The reflected light irradiated onto the semiconductor chip 5 is transmitted from the microscope optical system to the television camera 2 via the half mirror 11.
The video signal (
image signal). This image signal is image-processed and displayed on a monitor television, and an automatic machine performs inspection and determination of the semiconductor chip. On the other hand, the microscope shown in FIG. 5 has a light source 3 that irradiates the object 5 with light outside the microscope body 1, and the light from the light source 3 does not pass through the optical axis of the microscope optical system, but directly. It is a so-called dark field type that emits light onto the object 5.

0003

[Problems to be Solved by the Invention] The conventional microscopes shown in FIGS. 4 and 5 both use a visible light source (tungsten lamp) 3. As shown in FIG. 3, in the visible light tungsten lamp 3, the emission intensity exhibits a large value between 600 nm and 800 nm, and rapidly decreases when the wavelength exceeds 850 nm. Furthermore, if the object to be imaged is, for example, a semiconductor chip, the chip portion of the semiconductor chip 5 (
The reflectance of GaP) 51 is highest near 500 nm (reflectance is approximately 40%), and as the wavelength becomes longer, the reflectance gradually decreases, and from around 700 nm it shows a horizontal state with a reflectance of about 25%. . Furthermore, the reflectance of the gold pad portion 52 within the semiconductor chip surface is 50% at around 500 nm.
However, as the wavelength becomes longer, the reflectance gradually increases, and from around 800 nm, the reflectance increases to about 10
A value close to 0% indicates a horizontal state. Furthermore, the sensitivity of the CCD is also high at a small wavelength of around 500 to 700 nm. Therefore, when the semiconductor chip 5 is irradiated with visible light from the tungsten lamp 3 as shown in FIG.
The intensity of the reflected light from the gold pad portion 52 and the reflected light from the chip portion 51 are close to each other, there is almost no difference between the two, and the boundary between the gold pad portion 52 and the chip portion 51 is not clear. Therefore, the gold pad portion 5
The disadvantage is that the optimum range A for accurately recognizing the reflection pattern of No. 2 is narrow, and that it is difficult to set the brightness of the light source and the level (threshold level) B for binarization determination.

[0004] In the present invention, the above problems are solved, and by using an infrared light emitting element as a light source, the boundary between the semiconductor chip part and the gold pad part can be accurately recognized, and the brightness of the light source and the binarization can be improved. The purpose of the present invention is to provide a microscope in which the determination level can be easily set.

[0005]

Means and Effects for Solving the Problems In order to achieve this object, the microscope of the present invention has the following configuration. A microscope is a microscope in which the light-receiving surface of a television camera is arranged on the image plane of the microscope body, bright-field or dark-field illumination is applied to the object to be imaged, and the video signal of the television camera is visually viewed or image-processed on a monitor television. The illumination of the object to be imaged is characterized in that an infrared light emitting element is used as a light source.

[0006] A microscope having such a configuration uses an infrared light emitting diode as a light source. As shown in FIG. 3, the spectrum of the infrared light emitting diode ranges from 850 nm to 1000 nm, with a peak value at 950 nm. In other words, it is a light source that has a peak value in a long wavelength region. Moreover, at around 950 nm, the reflectance of the semiconductor chip portion is approximately 25%, and the reflectance of the gold pad portion is close to approximately 100%. Furthermore, the sensitivity of CCD is low at 950 nm, but it is about 50%. Therefore, as shown in Figure 2, when an infrared light emitting diode is used as a light source and infrared radiation is applied to a semiconductor chip, there is a large difference between the light reflected from the gold pad and the light reflected from the chip. Yes, the boundary between the two becomes clear. Therefore, the optimum range for accurately recognizing the reflection pattern of the gold pad portion is widened, and as a result, it becomes easy to set the brightness of the light source and the level for binarization determination.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view showing a specific embodiment of a microscope according to the present invention.

[0008] In the embodiment, a bright field type microscope is shown. As is well known, this microscope consists of a microscope main body (stereomicroscope or metallurgical microscope) 1 and a black and white television camera (CCD/image pickup tube) 2 arranged on the image plane side of the microscope main body 1. In other words, the light receiving surface 21 of the television camera 2
is arranged on the image plane of the microscope main body 1. Also, light source 3
is installed in the microscope body 1 so as to emit light to the optical system of the microscope body 1, and the light from the light source 3 passes through the optical axis through the half mirror 11 and onto the imaging target on the table 4 (
It is designed to irradiate the semiconductor chip (5). Also,
The reflected light irradiated onto the semiconductor chip 5 is reflected by a half mirror 11.
The light enters the light-receiving surface 21 of the television camera 2 from the microscope optical system via the microscope optical system, and is captured by the television camera 2 as a video signal (image signal). This image signal is subjected to image processing and displayed on a monitor television.

The feature of this invention is that the infrared light emitting element is used as a light source 3.
The point is that it was used as That is, an infrared light emitting diode 3 whose purpose is to emit infrared radiation with a long wavelength is used. As shown in FIG. 3, this infrared light emitting diode 3 has a long wavelength 8
It has a parabolic spectrum with a peak value of 950 nm in the range of 50 nm to 1000 nm. Also, Figure 3
As shown in , the reflectance of the gold pad portion 52 is extremely large (nearly 100%) in this 950 nm wavelength region.
, conversely, the reflectance of the semiconductor chip portion 51 is extremely small (
approximately 25%). Also, although the CCD is low, it has a high sensitivity (approximately 50
%). In other words, the infrared light emitting diode 3 has a gold pad portion 52.
This is a light source that emits light in a region where there is a large difference between the reflectance of the chip portion 51 and the reflectance of the chip portion 51, and the sensitivity of the CCD is low.

[0010] In the microscope having such a configuration, an infrared light emitting diode is used as the light source 3. As shown in Figure 3, the spectrum of an infrared light emitting diode is 850 nm.
It rises from around 950 nm and reaches a peak at 1000 nm.
nm and has the same lowest point as 850 nm. In other words, it is a light source that has a peak value in a large wavelength region. Moreover, 95
At around 0 nm, the reflectance of the semiconductor chip portion 51 is approximately 25
%, and the reflectance of the gold pad portion 52 shows a value close to about 100%. Furthermore, the sensitivity of the CCD is also low at 950 nm, but only about 50%. Therefore, as shown in FIG. 2, when an infrared light emitting diode is used as the light source 3 and infrared radiation is emitted to the target semiconductor chip 5, the reflected light from the gold pad portion 52 and the reflected light from the chip portion 51 are separated. There is a large difference between the two, and the boundary between the two is extremely clear. As a result, the optimal range A for accurately recognizing the reflection pattern of the gold pad portion 52 is widened, and the brightness of the light source and the level for binarization determination (threshold level B) can be easily set.

In the embodiment, the object to be imaged is the chip portion (GaP) 51 of the semiconductor chip 5 and the gold pad portion (Au).
) 52, but for example, A
Even in the case of an L electrode and a Si chip, the boundary between the two can be made clear by emitting infrared radiation.

0012

Effects of the Invention As described above, in this invention, since the light source that emits light to the object to be imaged by the microscope is an infrared light emitting element, the light reflected from the semiconductor chip portion and the gold pad portion are Since there is a large difference between the reflected light and the CCD sensitivity, which is low, the boundary between the two becomes clear and clear imaging can be obtained. Therefore, the optimum range for accurately recognizing the reflection pattern of the gold pad portion is widened, and the brightness of the light source and the level for binary determination can be easily set, and the present invention has excellent effects that achieve the purpose of the invention.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an example microscope.

FIG. 2 is an explanatory diagram showing a case where a semiconductor chip is imaged with an example microscope.

FIG. 3 is an explanatory diagram showing spectral characteristics of an LED illumination system.

FIG. 4 is an explanatory diagram showing a conventional microscope.

FIG. 5 is an explanatory diagram showing another conventional microscope.

FIG. 6 is an explanatory diagram showing a case where a semiconductor chip is imaged using a conventional microscope.

[Explanation of symbols]

1　Microscope body 2 TV camera 3. Light source 5 Semiconductor chip

Claims (1)

[Claims] Claim 1: A microscope in which the light-receiving surface of a television camera is arranged on the image plane of the microscope body, bright-field or dark-field illumination is applied to the object to be imaged, and the video signal of the television camera is visually viewed or image-processed on a monitor television. . A microscope characterized in that illumination of the object to be imaged uses an infrared light emitting element as a light source.