JP2006093270A - Apparatus and method for evaluating solid state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a matter that the characteristics cannot be evaluated in respective directions due to oblique light of large angle which cannot impinge on a solid state image sensor or oblique light from a plurality of directions in a probe card structure having such an optical system as receiving parallel light emitted from a light source and increasing the quantity of light in the direction oblique to the light receiving surface as compared with the quantity of light in the direction perpendicular to the light receiving surface from the central part toward the peripheral part on the light receiving surface of the solid state imaging device. <P>SOLUTION: Light emitting sources 11a-11h for irradiating the light receiving surface of an evaluation object, i.e. the solid state image sensor, with light from specified oblique directions are arranged on a probe card. At first, the light receiving surface of the solid state image sensor is irradiated with parallel light from a light source 23 and the characteristics are evaluated by measuring the output signal. Subsequently, the light source 23 is unlighted and light is emitted sequentially from the light emitting sources 11a-11h and the characteristics are evaluated by measuring the output signal every time when the light emitting source 11 for emitting light is switched. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a solid-state image sensor evaluation apparatus and evaluation method.

  Solid-state image pickup devices have made remarkable progress in multimedia applications, and the demand for downsizing, high pixel count, and multi-functionality has been increasing especially for solid-state image pickup devices for digital still cameras.

  Conventionally, when evaluating the electrical characteristics of a solid-state imaging device, it is common to perform automatic evaluation by a tester in a wafer state, and to evaluate by sensory inspection using a tester or a mounting evaluation device after assembly. In the solid-state imaging device, provisions for image quality are provided in the electrical characteristics, and it is necessary to accurately and promptly evaluate products that satisfy the provisions.

  In recent years, the distance between the optical lens and the solid-state image sensor has been reduced along with the reduction in the optical size of the solid-state image sensor and the downsizing of the image pickup apparatus incorporating the solid-state image sensor. For this reason, in an actual solid-state image sensor, the central portion of the light receiving surface has a large amount of parallel light components, and the peripheral portion has a large amount of oblique light components.

  In a conventional solid-state image sensor evaluation apparatus, as described in Patent Document 1, for example, an actual solid-state image sensor on a probe card with respect to a measurement light source of a standard solid-state image sensor that emits parallel light An optical system having the same or similar optical characteristics as that of a lens system incorporated in an imaging apparatus using a lens has been proposed. An evaluation apparatus for a solid-state image sensor in Patent Document 1 will be described with reference to the drawings.

As shown in FIG. 7, the light source 23 is provided with a light emitting source 23a and a lens 23b for converting light emitted from the light emitting source 23a into parallel light. Further, a probe needle 21a is attached to the probe card 21, and the probe needle 21a is brought into contact with an electrode pad (not shown) of a solid-state imaging device formed on the wafer 10 to be measured, thereby inputting and outputting signals. I do. 7 receives the parallel light emitted from the light source 23, and the amount of light in the direction perpendicular to the light receiving surface as it goes from the central portion to the peripheral portion of the light receiving surface of the solid-state imaging device formed on the wafer 10. The optical system 21b increases the amount of light in an oblique direction, and the measurement substrate 22 includes a circuit that performs a predetermined characteristic measurement based on an electrical signal obtained from the probe card 21.
Japanese Patent Laid-Open No. 11-26521

  However, in the above prior art, the light parallel to the light source 23 is received, and the light amount in the direction perpendicular to the light receiving surface is inclined in the direction from the central portion to the peripheral portion of the light receiving surface of the solid-state imaging device formed on the wafer 10. Characteristic evaluation cannot be performed individually (by direction) by oblique light with a large angle that cannot enter from an optical system (mainly a lens) that increases the amount of light, or oblique light from a plurality of directions.

  An object of the present invention is to solve such problems and to provide an evaluation device and an evaluation method for a solid-state imaging device that can individually evaluate electrical characteristics when oblique light is incident.

  In order to achieve the above object, the present invention provides a plurality of light emitting sources connected to controllable electrodes on a probe card so that light can be incident on a light receiving portion of a solid-state imaging device at a plurality of angles, Alternatively, the light emission source emits light one by one with a control signal based on a voltage signal, and an image signal obtained from the solid-state imaging device is individually processed.

  According to the present invention, it is possible to individually evaluate the electrical characteristics when oblique light is incident.

  Embodiments of an evaluation apparatus for a solid-state image sensor according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of a main part of a probe card and a first embodiment of the present invention including the probe card.

  A probe needle 21a is attached to the probe card 21, and a signal is input / output by bringing the probe needle 21a into contact with an electrode pad of a solid-state imaging device formed on the wafer 10 to be measured. An image signal is taken in, subjected to arithmetic processing, and the characteristics are evaluated based on the arithmetic result. In the present embodiment, the light emitting surface connected to the terminal on the probe card 21 in order to control the light receiving surface of the solid-state imaging device formed on the wafer 10 with a constant voltage or a voltage signal so that light can be irradiated from an oblique direction. A source 11 is arranged. In the present embodiment, the light source 11 is arranged on the probe card 21. However, the light source 11 may be arranged on the measurement substrate or other places, and the same effect can be obtained. Evaluation can be made. Further, since the probe card usually corresponds to the type of the solid-state image sensor, by arranging the light emitting source 11 on the probe card 21, different arrangements are possible for each type of the solid-state image sensor. The light source 11 is applicable as long as it can obtain parallel light so that the incident angle of oblique light is uniform, and a light emitting diode, a laser light source, and the like are preferable.

  FIG. 2 is a plan view of the probe card according to the second embodiment of the present invention as viewed from above. In the second embodiment, a plurality of light emitting sources 11 (eight in this embodiment) and electrodes 12 that electrically connect these light emitting sources 11 are arranged on a probe card 21 in a circular shape. The eight light emitting sources 11a to 11h can be individually controlled. Similar to the first embodiment shown in FIG. 1, the probe card 21 is combined with a measurement substrate and brought into contact with an electrode pad of a solid-state imaging device formed on the wafer 10 to input / output signals and obtain it. An image signal is taken into a measuring instrument, and an arithmetic process is performed, and a characteristic evaluation is performed based on the calculation result. And according to the control signal from a measuring device, the light emission sources 11a-11h of each direction are individually lighted with respect to the solid-state imaging device, and the characteristics are individually evaluated.

  FIG. 3 is a cross-sectional view of the main part of the third embodiment of the present invention, in which a plurality of light emitting sources 11 are arranged in a plurality of stages at different heights from the probe card 21 plane. In the cross-sectional view of FIG. 3, there are six light emitting sources 11, but it goes without saying that a plurality of light emitting sources 11 are arranged in the plane direction. Similar to the first embodiment shown in FIG. 1, the probe card 21 is combined with a measurement substrate and brought into contact with an electrode pad of a solid-state imaging device formed on the wafer 10 to input / output signals and obtain it. An image signal is taken into a measuring instrument, and an arithmetic process is performed, and a characteristic evaluation is performed based on the calculation result. The light source is individually turned on by the control signal from the measuring device, and the characteristics are individually evaluated. As a result, it is possible to individually perform characteristic evaluation with oblique light having different plane directions and different incident angles.

  FIG. 4 is a cross-sectional view showing the configuration of the fourth embodiment of the present invention, which has a configuration in which a light source 23 and a probe card 21 are combined to irradiate light vertically. FIG. 4A is a combination with the probe card 21 in the first embodiment shown in FIG. 1 or the second embodiment shown in FIG. 2, and FIG. 4B is the third embodiment shown in FIG. FIG. 6 is a cross-sectional view of the configuration in combination with the probe card 21. For convenience, the description will be made including FIG.

  FIG. 5 is a schematic diagram of the entire evaluation apparatus. The evaluation apparatus 1 has a configuration in which a prober 2 and a measuring instrument 3 are combined. Among these, the prober 2 includes a probe card 21 disposed on the wafer 10 on which the solid-state image sensor is formed, a measurement substrate 22 to which the probe card 21 is attached, and a light source 23 that irradiates light to the solid-state image sensor. The measuring instrument 3 has a configuration including a control system for controlling the prober 2, the measurement substrate 22 and the light source 23.

  As shown in FIG. 4, the light source 23 is provided with a light emitting source 23a and a lens 23b for converting light emitted from the light emitting source 23a into parallel light. In order to evaluate the characteristics of the solid-state image sensor with the evaluation apparatus 1 in the present embodiment, first, the wafer 10 on which the solid-state image sensor to be evaluated is formed is set on the prober 2 shown in FIG. The measurement substrate 22 and the probe card 21 are arranged on the substrate.

  It is assumed that the probe card 21 is attached with a light emission source as described above. Here, it is a condition that the light emitting source 11 is arranged so as not to interrupt the optical path from the light source 23 to the solid-state imaging device.

  Next, the probe card 21 and the wafer 10 are aligned, the probe needle 21a is brought into contact with the electrode pad of the solid-state image sensor to be evaluated, and the light receiving unit of the solid-state image sensor on the wafer 10 is irradiated with light. Thus, an electric signal (a signal obtained by photoelectric conversion) output from the electrode pad of the solid-state imaging device is taken in via the probe needle 21a previously brought into contact with the electrode pad, and is transferred from the probe card 21 to the measurement substrate 22. send. The taken electric signal is sent as a measurement value from the measurement substrate 22 to the measuring instrument 3 shown in FIG. 5, where a predetermined calculation process is performed to evaluate the characteristics.

  Next, the process of measuring the output signal from the fixed image sensor in the fourth embodiment will be described with reference to FIG. First, the light from the light source 23a of the light source 23 shown in FIG. 4 is converted into parallel light through the lens 23b and emitted, and the characteristics are evaluated (steps 1 and 2). The characteristic evaluation value obtained here is equivalent to the characteristic evaluation value of a probe card not disposed in a conventional light source. Next, the light source 23 is turned off or blocked by the control signal, and one of the light source groups 11, for example, the light source 11 a is first turned on by another control signal, and the light receiving surface of the solid-state image sensor is specified. In a state in which oblique light from the direction is intensively irradiated (step 3), it is sent to the measuring device 3 as in the case of the parallel light, and the characteristics are evaluated by a predetermined calculation (step 4). Further, by switching on and turning on the light emitting sources in the light emitting source group according to the control signal and evaluating the same characteristics, it is possible to individually evaluate the electric characteristics in the state where the oblique light is irradiated from a plurality of directions. Similarly, the light emitting sources 11a to 11h are turned on one by one, and the characteristic evaluation is performed individually (steps 3 to 18).

  As described above, the present invention is useful for measuring and evaluating optical characteristics of a solid-state imaging device when oblique light is incident.

Cross-sectional view of the main part of the first embodiment of the present invention Probe card plan view of the second embodiment of the present invention Cross-sectional view of the main part of the third embodiment of the present invention Sectional drawing of the principal part of the fourth embodiment of the present invention Schematic diagram of the entire evaluation device Measurement flow diagram according to the fourth embodiment of the present invention Cross-sectional view of a conventional method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Evaluation apparatus 2 Prober 3 Measuring device 10 Wafer 11, 11a, 11b, 11c, 11d, 11e, 11f, 11g, 11h (in this invention) Light emission source 21 Probe card 21a Probe needle 21b (in the conventional method) Optical system 22 Measurement board 23 Light source

Claims (8)

  An apparatus for evaluating a solid-state imaging device, comprising: a light-emitting source for irradiating light from a specific oblique direction to a light-receiving surface of a solid-state imaging device to be evaluated.   2. The evaluation device for a solid-state image pickup device according to claim 1, further comprising a probe card having a probe needle that contacts an electrode pad of the solid-state image pickup device, wherein the light emitting source is disposed on the probe card.   3. The solid-state image sensor evaluation apparatus according to claim 2, wherein a plurality of the light emission sources are arranged in a circle centering on the imaging center of the solid-state image sensor on the probe card plane.   The solid-state imaging device evaluation apparatus according to claim 2, wherein a plurality of the light emitting sources are arranged at different positions from the probe card plane.   It further comprises a light source for irradiating light substantially perpendicularly to the light receiving surface of the solid-state image sensor, and the light-emitting source is disposed at a position that does not impede light irradiation from the light source to the solid-state image sensor. The solid-state image sensor evaluation apparatus according to any one of claims 1 to 4.   The solid-state imaging device evaluation apparatus according to claim 1, wherein light emission control is enabled by controlling a voltage applied to the light emission source.   The solid-state image sensor evaluation apparatus according to claim 1, wherein the light emitted from the light-emitting source to the solid-state image sensor is parallel light. A light source for irradiating light substantially perpendicularly to the light receiving surface of the solid-state image sensor to be evaluated, and a position that does not obstruct light irradiation from the light source to the solid-state image sensor, An evaluation method for a solid-state imaging device using an evaluation apparatus provided with a light emitting source for irradiating light from an oblique direction,
An evaluation method for a solid-state imaging device, wherein evaluation is performed using image information obtained by irradiating light from the light source and image information obtained by irradiating light from the light emitting source.

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