JPH0290645A - Inspection of image sensor and inspecting device which is used for that - Google Patents

Abstract

PURPOSE:To bring closer an image sensor to a state after the sensor is sealed and moreover, to make possible the inspection of the image sensor having little variability by a method wherein light emitted from a light source is scattered and the scattered light is turned into a light close to a uniform light and is irradiated on the image sensor to inspect. CONSTITUTION:Light irradiated from an LED 7 reaches a frosted glass 10 and is made to pass through the glass 10. At this time, the light emitted from the LED strikes on the interior of a luminous part main body 6 as well, but an irregular reflection is not caused because a discharge machining is performed on the surface of the interior. The light made to pass through the glass 10 becomes an almost uniform light as being scattered sufficiently by the glass 10 and reaches a SELFOC lens 4. Even here, even if the light strikes on the interior of the lens 4, the light is absorbed by the surface, on which a discharge machining is performed, of the lens 4. The angle of the light made to pass through the lens 4 is spread by about 20 deg. and the light is released. As this light becomes an almost uniform light, the light becomes the optimum light for the inspection of an image sensor which is an object. This light is irradiated on the image sensor 1a formed on a wafer 1 and as the result, a current which is made to flow through the sensor 1a is detected by probes 2. Thereby, the inspection of the image sensor is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a technique that is effective when applied to the inspection of imaging devices manufactured by semiconductors, such as image sensors.

[Conventional technology]

When inspecting an image sensor, such as an image sensor manufactured using a semiconductor, there are roughly two inspection steps. The first step is to inspect the image pickup devices formed on the wafer in that state, and the second step is to separate the image pickup devices from the wafer and perform the inspection after sealing them appropriately.

Conventionally, in the first inspection step, as with other semiconductor devices, the image sensor is inspected by bringing a probe needle into contact with the electrode of the image sensor formed on the wafer and applying a current.

In the second inspection step, after the image sensor is appropriately sealed, it is normal to irradiate light and perform inspection in a state closer to that of mounting.

Incidentally, although this is not an inspection of an image sensor, there is Japanese Patent Application Laid-Open No. 100439/1983 which shows an inspection in which a probe needle is brought into contact with a semiconductor element formed on a wafer.

[Problem to be solved by the invention]

In the conventional technology as described above, in the first inspection step, which is the inspection of the wafer state, a probe needle is brought into contact with the wafer and a current is applied to conduct the inspection. However, this method has a problem in that it is not always possible to obtain good test results because the conditions are different from test results obtained by irradiating light similar to the state in which the image sensor is actually used. In addition, in the second inspection process, after the seal is properly sealed, the inspection is performed by irradiating light, so highly accurate inspection results can be obtained, but if a defect is found, the previous manufacturing process will be wasted. There was a problem that this resulted in a large amount of losses.

An object of the present invention is to provide a method and apparatus for inspecting an image sensor formed on a wafer in a state closer to the state when it is mounted.

Another object of the present invention is to provide a highly accurate testing method and testing apparatus for testing an image sensor formed on a wafer.

[Means for tackling the challenges]

An overview of typical aspects of the present invention is as follows.

In other words, when inspecting an image sensor formed on a wafer, a light source is used to irradiate the image sensor formed on the wafer, and the light emitted from the light source is scattered to produce near-uniform light. This means that the imaging device is irradiated with nearly uniform light for inspection.

[Effect]

According to the means, the image sensor formed on the wafer,
Since light can be irradiated and the light can be made uniform, it is possible to inspect the image sensor in a state similar to that after the image sensor is sealed and with less variation.

〔Example〕

Hereinafter, the present invention will be described in detail based on examples.

FIGS. 1 and 2 are a front view and a side view showing cross sections of essential parts of an embodiment of the present invention. 3 and 4 are a front view and a side view of the present invention shown in FIGS. 1 and 2, respectively. FIG. 5 is a diagram showing a SELFOC lens used in the present invention.

The device used in the present invention is broadly divided into a light emitting section and a probe card section.

The light emitting section is composed of a light emitting section main body 6 made of iron-based material, a frosted glass mounted inside the main body 6, and a light source.

The light emitting part main body 6 has a box-like shape, and the inside thereof is subjected to electrical discharge machining. This electric discharge machining is performed on the light emitting part body 6.
This is to prevent unnecessary diffused reflection of light emitted from a light emitting diode (hereinafter referred to as an LED) installed as a light source in the upper part of the light emitting section within the light emitting section, which would adversely affect the inspection. Below the light emitting part main body 6 is the LED.
A frosted glass 10 is attached to scatter the irradiated light almost uniformly. This frosted glass 10 is fixed so as to be sandwiched between a portion protruding into the interior of the light emitting section main body 6 and a presser foot 11. This presser foot 11
The 0 surface is also subjected to electrical discharge machining for the same reason as the inside of the light emitting section main body 6.

Further below the frosted glass 10, a SELFOC lens 4 is attached as a part that emits light from the issuing body 6 to the outside. The SELFOC lens 4 is constructed as shown in FIG. 5, and is made up of a large number of elongated lenses arranged and assembled, and has the effect of uniformly emitting light. The light emitting section is configured as described above.

The probe card part consists of a probe card 3 and a light emitting unit mounting frame 5.
It's also happening. Semiconductor wafer 1 on which an image sensor 1a is formed, which is placed below a probe card 3 from a predetermined position.
It has a probe needle 2 configured to come into contact with. This probe card 3 is similar to a probe card used for testing semiconductor devices, except that the light emitting section is attached to a frame 5 at a predetermined position on the top surface. Also, the installation is frame 5
By changing the thickness of the portion in contact with the glove card 3, the distance between the probe needle 2 and the SELFOC lens can be adjusted.

The device of the present invention is completed by attaching the light emitting section to the glove card section.

An inspection method using the above device will be explained.

The light emitted from the LED 7 reaches the frosted glass 10. At this time, the light emitted from the LED 7 also hits the inside of the light emitting unit main body 6, but the internal surface is subjected to electrical discharge machining, so diffuse reflection does not occur.The light that has passed through the frosted glass 10 Since it is sufficiently scattered by the lens, it becomes almost uniform and reaches the SELFOC lens 4. Here, even if light hits the inside, the light is absorbed by the surface that has been subjected to electrical discharge machining. The passing light spreads at an angle of about 20 degrees and is emitted.This light is almost uniform, so it is the best light for inspecting the image sensor, which is the subject of the present invention.This light is applied to the wafer IK. The image sensor 1a is inspected by irradiating the image sensor 1a and detecting the current flowing through the image sensor with the probe needle 2.

According to this embodiment, the following effects can be obtained.

(11) Since the internal surface of the light emitting unit main body 6 is subjected to electrical discharge machining, an effect is obtained in that unnecessary reflected light does not have an adverse effect.

(2) Since a normal probe card can be processed and used, there is no need to prepare a new probe card.

(Using No. 31 frosted glass, LEI) The light irradiated from the LEI can be scattered and made into almost uniform light, resulting in the effect that highly accurate calibration results can be obtained.

Although the invention made by the inventor of the present application has been specifically explained based on one embodiment, it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the gist thereof. stomach. For example, in this embodiment, frosted glass was used as a scattering means to obtain uniform light, but other materials may be used. The inventor of this application tried using thin paper (trace paper) sandwiched between transparent glass, and a sufficient scattering effect was obtained. Further, in this embodiment, a selfoc lens is used to make the light uniform by scattering it with a frosted glass, but it is not necessary to use a selfoc lens. Even without a SELFOC lens, sufficient uniform light can be obtained for inspection, and a sufficient effect can be obtained for inspection of an imaging device that is irradiated with light.

In the above explanation, the invention made by the inventor of the present application has mainly been explained with respect to the field of application which is the background thereof, which is the inspection technique of an image sensor manufactured by a cow body. However, it is not limited to that, and at least Needless to say, it can be used to inspect devices that receive light.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

Since the image pickup device formed on the wafer can be inspected by irradiating it with light, it is possible to obtain inspection results that are closer to a smiling state before sealing.

Furthermore, since the imaging element can be irradiated with a uniform beam, highly accurate inspection results can be obtained.

Furthermore, since the quality of the image sensor can be determined in the wafer state, the rate of defective products being sent to subsequent processes is reduced, and this can be of great use in reducing product costs.

[Brief explanation of drawings]

Fig. 1 is a front view of a cross section of a main part of an embodiment of an inspection device according to the present invention, Fig. 2 is a side view of a cross section of a main part of an embodiment of an inspection device according to the present invention, and Fig. 3 is an inspection by non-invention. FIG. 4 is a side view showing the outline of an embodiment of the inspection device according to the invention; FIG. 5 is a structure of a selfoc lens used in the embodiment of the invention. It is an A-AIrr surface and a diagram showing it. ]... Wafer, 1a... Imaging element formed on the wafer, 2... Probe needle, 3... Probe card,
4...Selfoc lens, 5...Mounting frame, 6
...Issuing unit main body, 7...Light emitting diode (LED)
, 8... LED board, 9... lid, 10... frosted glass, ] 1... fixing plate, 12... lens. Agent: Patent Attorney Katsuo Ogawa Figure zo

Claims (1)

[Claims] 1. Irradiating an image sensor formed on a wafer with uniform light,
A method for inspecting an image sensor, characterized in that the image sensor is tested by measuring the current flowing through the image sensor as a result. 2. In an inspection apparatus that places a wafer in a predetermined position and irradiates light onto an image sensor formed on the wafer to inspect the image sensor, a light source for irradiating the image sensor with light; An inspection device for an image sensor, comprising means for scattering the light emitted from the light source to make the light substantially uniform.