JP2009170730A - Inspecting apparatus for back irradiating type solid-state imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspecting apparatus for a back irradiating type solid-state imaging device capable of conducting the inspection in a wafer state. <P>SOLUTION: A vacuum chuck 40 composing a stage 14 for placing a semiconductor wafer 11 includes a chuck top 43 comprising a transparent member on which a suction hole 43a is disposed and a support container 42 comprising the transparent member formed so that the chuck top 43 is inserted to the open upper part, the vacuum chuck 40 holds by suction the reverse face 11b of the semiconductor wafer 11 on which a plurality of the back irradiating type solid-state imaging devices are formed, which receives light from the rear face that is the back side of the surface where an electrode pad is formed. An EL sheet 41 is fixed on the bottom face of the support container 42. The EL sheet 41 emits surface light and irradiates the rear face 11b (optical incident face of the back irradiating type solid-state imaging device) of the semiconductor wafer 11 passing through the vacuum chuck 40. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor wafer inspection apparatus, and more particularly to a semiconductor wafer inspection apparatus on which a back-illuminated solid-state imaging device is formed.

  CCD (Charge Coupled Device) type and CMOS (Complementary Metal Oxide Semiconductor) type solid-state imaging devices used in electronic cameras such as digital cameras are formed in a matrix on a semiconductor wafer. Inspection (wafer inspection) is performed in a wafer state before dividing the wafer.

  In this wafer inspection process, a wafer prober that holds a semiconductor wafer and applies a measurement probe to an electrode pad of a desired solid-state imaging device in the semiconductor wafer to achieve electrical conduction, and a solid-state imaging device via the wafer prober An inspection apparatus is used that includes a semiconductor tester that inputs and outputs electrical signals between them and inspects the electrical characteristics of the solid-state imaging device, and a light source device that causes inspection light to enter each solid-state imaging device. The contents of the inspection include DC (direct current) measurement for checking conduction / non-conduction between the electrode pads, and whether the light receiving surface is irradiated with light and a driving pulse is supplied to correctly output a signal from the solid-state imaging device. There are imaging measurements to examine.

In a solid-state imaging device, since the electrode pad and the light receiving surface are usually formed on the same surface, the back side of the semiconductor wafer on which the electrode pad and the light receiving surface are not formed is held by a vacuum chuck or the like. Inspection is performed by irradiating light to the light receiving surface from the opening of the probe card in a state in which the electrode pad is subjected to needle contact by an opened probe card (a card on which a measurement probe is arranged) (for example, Patent Document 1). reference).
JP 2002-164395 A Japanese Patent Laid-Open No. 9-82852 JP 2002-222936 A

  By the way, in recent years, as a solid-state imaging device, in order to improve the aperture ratio and increase the sensitivity, it is configured to receive light incident from the back side opposite to the front side where the electrode pad and the wiring layer are formed. A back-illuminated solid-state imaging device is known (see, for example, Patent Documents 2 and 3).

  However, since the semiconductor wafer on which this back-illuminated solid-state imaging device is formed has a light-receiving surface on the back side that is held by the above-described vacuum chuck or the like, in the inspection apparatus described above, light can be incident on the light-receiving surface. There is a problem that the inspection cannot be performed. For this reason, it is conceivable to inspect the backside illuminated solid-state imaging device after dividing the semiconductor wafer into chips for each device and packaging each chip, but with this inspection method, it is not possible in the wafer state. Since good products cannot be excluded in advance, defective products are packaged for inspection, which is wasteful and increases manufacturing costs.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a back-illuminated solid-state imaging device inspection apparatus that enables inspection in a wafer state.

  In order to achieve the above object, the backside illumination type solid-state imaging device inspection apparatus of the present invention has a plurality of backside illumination type solid-state imaging devices that receive light from the back surface opposite to the surface on which the electrode pads are formed. A holding unit formed of a transparent member that holds the back side of the semiconductor wafer; an inspection light irradiating unit that irradiates the back side of the semiconductor wafer with inspection light transmitted through the holding unit; and a front side of the semiconductor wafer And an inspection means for conducting electrical inspection with respect to the electrode pad.

  The inspection light irradiating means is preferably an EL sheet fixed to the bottom surface of the holding means.

  The holding means includes a chuck top on which the semiconductor wafer is placed and a suction hole disposed so as to be located outside the formation region of the backside illumination type solid-state imaging device, and the chuck top on an open upper portion. It is preferable that it is a vacuum chuck which consists of a support container formed so that can be fitted.

  The inspection means preferably includes a probe card including a measurement probe that is in contact with the electrode pad, and a semiconductor tester that applies an electrical signal to the electrode pad via the probe card.

  An inspection apparatus for a backside illumination type solid-state imaging device according to the present invention includes a holding unit formed of a transparent member that holds the backside of a semiconductor wafer, and an inspection light irradiation that passes through the holding unit and irradiates the backside of the semiconductor wafer. The back-illuminated solid-state imaging device can be inspected in the wafer state.

  In FIG. 1, an inspection apparatus 10 according to the present invention holds a semiconductor wafer 11 to be inspected and is electrically connected to an electrode pad 31 (see FIG. 2) of a back-illuminated solid-state imaging device 30 formed on the semiconductor wafer 11. A wafer prober 12 for electrical connection and a semiconductor tester 13 for inputting / outputting electrical signals to / from the semiconductor wafer 11 via the wafer prober 12 and inspecting the electrical characteristics of the back-illuminated solid-state imaging device 30. Has been.

  The semiconductor tester 13 has a built-in computer, generates electrical signals for DC characteristics and imaging characteristics inspection based on a test program, inputs them to the back-illuminated solid-state imaging device 30 to be inspected, and according to the input test signals This is a well-known semiconductor measurement apparatus that detects an electrical signal output from the back-illuminated solid-state imaging device 30 to be inspected and determines whether it is acceptable.

  The wafer prober 12 is provided with a stage 14 on which the semiconductor wafer 11 is placed. The stage 14 is configured to accurately move in the vertical and horizontal directions via the stage moving mechanism 16 and the position detection sensor 17 under the control of the controller 15. As will be described in detail later, the stage 14 is provided with a light source device for irradiating the back side of the semiconductor wafer 11 with inspection light.

  A probe card 18 is detachably provided immediately above the stage 14. The probe card 18 is provided with a plurality of measurement probes 19 so as to correspond to the electrode pads 31 of the back-illuminated solid-state imaging device 30 formed on the semiconductor wafer 11. The probe card 18 and the semiconductor tester 13 correspond to the inspection unit described in the claims.

  An image recognition mechanism 20 including a CCD camera or the like is disposed in the vicinity of the stage 14. The image recognition mechanism 20 recognizes images of the surface of the semiconductor wafer 11 and the tip of the measurement probe 19. This image recognition information is transmitted to the controller 15, and the controller 15 controls the stage moving mechanism 16 based on the position information of the stage 14 detected by the position detection sensor 17, and the backside irradiation type solid-state imaging on the semiconductor wafer 11. The electrode pad 31 of the element 30 is aligned with the corresponding measurement probe 19.

  In FIG. 2, a semiconductor wafer 11 is obtained by forming a plurality of back-illuminated solid-state imaging elements 30 in a two-dimensional matrix on a disk-shaped silicon single crystal substrate. On the front surface 11 a of the semiconductor wafer (semiconductor substrate) 11, a plurality of electrode pads 31 are formed as external terminals for inputting / outputting electrical signals to / from the internal circuit of the back-illuminated solid-state imaging device 30.

  FIG. 3 shows a cross-sectional structure of the light receiving portion of the backside illumination type solid-state imaging device 30. The light receiving element 32 is an embedded photodiode formed in the semiconductor wafer 11 and receives light incident from the back surface 11b side opposite to the front surface 11a. The light receiving elements 32 are two-dimensionally arranged in the semiconductor wafer 11 at a pitch of several μm. The semiconductor wafer 11 is thinned to a thickness of about 10 μm so that light can be incident from the back surface 11 b side. On the back surface 11 b side, a color filter 33 that splits incident light is provided on each light receiving element 32. It is provided to correspond.

  The light receiving element 32 is an element that receives incident light and generates and accumulates signal charges corresponding to the amount of light. The signal charges accumulated in the light receiving elements 32 are transferred to the surface 11a side of the semiconductor wafer 11 as charge transfer paths. A gate electrode 34 is provided for transferring to a (when the back-illuminated solid-state image sensor 30 is a CCD type) and an amplifier (when the back-illuminated solid-state image sensor 30 is a CMOS type). The gate electrode 34 is made of conductive silicon such as polysilicon, and its periphery is covered with an interlayer insulating layer 35 made of silicon oxide or the like.

  The surface of the interlayer insulating layer 35 is planarized. A wiring layer 36 made of aluminum or the like connected to the gate electrode 34 through a contact plug (not shown) is formed on the interlayer insulating layer 35. The wiring layer 36 is covered with a protective insulating layer 37 made of silicon oxide or the like. The wiring layer 36 is connected to the electrode pad 31 exposed on the surface 11a side.

  As described above, in the backside illumination type solid-state imaging device 30, structures such as the gate electrode 34 and the wiring layer 36 are not located on the light incident side of the light receiving device 32, and thus a high aperture ratio can be obtained. For this reason, sufficient light receiving sensitivity can be obtained without providing a microlens on the color filter.

  FIG. 4 shows the structure of the stage 14. The stage 14 includes a vacuum chuck 40 for attracting and holding the semiconductor wafer 11 and an EL (electroluminescence) sheet 41 for irradiating the semiconductor wafer 11 with inspection light. The vacuum chuck 40 is formed by bonding a support container 42 and a chuck top 43 formed of a transparent member such as glass by an adhesive material 44. The vacuum chuck 40 and the EL sheet 41 correspond to the holding unit and the inspection light irradiation unit described in the claims.

  The support container 42 is an open top cylindrical container with an open top, and a chuck top 43 is fitted into the uppermost part of the cylinder. The chuck top 43 has a disk shape, and a plurality of minute through holes (suction holes) 43a penetrating vertically are formed. The semiconductor wafer 11 is placed on the surface of the chuck top 43. As shown in FIG. 5, the through hole 43 a is disposed at a position corresponding to the outer edge portion of the semiconductor wafer 11 so as to be located outside the region where the backside irradiation type solid-state imaging device 30 of the semiconductor wafer 11 is formed. .

  By fitting the chuck top 43 on the upper portion of the support container 42, a sealed space is created in the container. A suction port 45 is formed in the side portion of the support container 42. By sucking air in the sealed space from the suction port 45 by the suction device 46, air is sucked from the through hole 43 a of the chuck top 43. As a result, the semiconductor wafer 11 is sucked and held on the surface of the chuck top 43. The semiconductor wafer 11 is placed so that the back surface 11 b side faces the surface of the chuck top 43.

  The EL sheet 41 is a surface-emitting light source device in which an EL element that emits light by applying voltage to a phosphor dispersed in a high dielectric constant binder is formed into a sheet shape, and is fixed to the bottom surface of the support container 42. ing. The EL sheet 41 has a disk shape that is slightly larger than the semiconductor wafer 11, and the emitted light passes through the vacuum chuck 40 made of a transparent member and enters the back surface 11 b (light incident surface) of the semiconductor wafer 11.

  As shown in FIG. 6, the EL sheet 41 protects the surface of the transparent bonding layer 50 having the function of bonding to the surface of the support container 42, the EL layer 51 including the EL elements, and the entire surface uniformly emitting light, and the surface of the EL layer 51. The protective layers 52 to be laminated are sequentially laminated. The EL layer 51 includes a transparent electrode layer 51a, a light emitting layer 51b, a dielectric layer 51c, a back electrode layer 51d, and an insulating layer 51e. By applying a voltage to the transparent electrode layer 51a and the back electrode layer 51d, The light emitting layer 51b emits light. Supply of voltage to the EL layer 51 is performed by the controller 15. Note that the emission color of the EL layer 51 is determined by the light emitting material in the light emitting layer 51b. When the light emitting layer 51b emits white light, the color of the inspection light may be adjusted by providing a color filter on the emission side.

  Next, the operation of the inspection apparatus 10 configured as described above will be described. When the inspection starts, first, the stage moving mechanism 16 moves horizontally under the control of the controller 15, and the back-illuminated solid-state imaging device 30 to be inspected in the semiconductor wafer 11 placed on the stage 14 becomes the probe card 18. Positioning is performed so as to be positioned under the measurement probe 19 (step S1). When the positioning is completed, the stage moving mechanism 16 moves upward under the control of the controller 15, and the electrode pad 31 formed on the surface 11 a of the back-illuminated solid-state imaging device 30 to be inspected is brought into contact with the measurement probe 19. (Step S2).

  When the electrode pad 31 is brought into contact with the measurement probe 19, a test signal for DC measurement is input to the back-illuminated solid-state imaging device 30 to be inspected by the semiconductor tester 13 via the probe card 18, and DC measurement is performed ( Step S3). When the DC measurement is completed, the EL sheet 41 is operated, and the inspection light transmitted through the vacuum chuck 40 is irradiated onto the back surface 11b (light incident surface) of the semiconductor wafer 11 (step S4). In this state, the electrical signal for imaging measurement is input to the back-illuminated solid-state imaging device 30 to be inspected by the semiconductor tester 13 via the probe card 18, and imaging measurement is performed (step S5).

  When the imaging measurement is completed, the stage moving mechanism 16 moves downward under the control of the controller 15, and the measurement probe 19 is separated from the electrode pad 31 (step S6). Thereafter, it is determined whether or not there is an unexamined back-illuminated solid-state imaging device 30 (step S7). If there is an unexamined back-illuminated solid-state image sensor 30, steps S1 to S6 are repeated. When all the back-illuminated solid-state image sensors 30 in the semiconductor wafer 11 are inspected, the inspection is completed.

  As described above, by using the inspection apparatus 10, the back-illuminated solid-state image sensor 30 can be inspected as it is formed on the semiconductor wafer 11, and the back-illuminated solid-state image sensor 30 is separated into chips. Defective products can be excluded in advance before packaging.

  In the above embodiment, the vacuum chuck is formed by the two transparent members of the support container and the chuck top. However, the present invention is not limited to this, and the vacuum chuck may be integrally formed by the transparent member. Further, the through hole (suction hole) for adsorbing the semiconductor wafer may be formed at an appropriate position as long as it is outside the element formation region.

  Moreover, in the said embodiment, although the light source device is comprised using an EL sheet, this invention is not limited to this, You may use the light source device comprised by the halogen lamp and LED (light emitting diode).

It is a schematic diagram which shows the structure of the inspection apparatus concerning this invention. It is a top view which shows the surface side of the semiconductor wafer to be examined. It is principal part sectional drawing which shows the structure of a back irradiation type solid-state image sensor. It is sectional drawing which shows the structure of a stage. It is a top view of a chuck top. It is sectional drawing which shows the structure of EL sheet. It is a flowchart explaining the effect | action of an inspection apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inspection apparatus 11 Semiconductor wafer 11a Front surface 11b Back surface 12 Wafer prober 13 Semiconductor tester (inspection means)
14 Stage 18 Probe card (inspection means)
19 Measurement probe 30 Back-illuminated solid-state imaging device 31 Electrode pad 32 Light receiving device 40 Vacuum chuck (holding means)
41 EL sheet (inspection light irradiation means)
42 Support container 43 Chuck top 43a Through hole (suction hole)
45 Suction port

Claims (4)

A holding means formed of a transparent member that holds the back side of the semiconductor wafer on which a plurality of backside illuminated solid-state imaging elements that receive light from the back side opposite to the surface on which the electrode pads are formed;
Inspection light irradiating means for irradiating the back side of the semiconductor wafer with inspection light transmitted through the holding means;
Conducting with the electrode pad from the surface side of the semiconductor wafer, inspection means for performing an electrical inspection,
A back-illuminated solid-state imaging device inspection apparatus comprising:   2. The inspection apparatus for a backside illumination type solid-state image pickup device according to claim 1, wherein the inspection light irradiation means is an EL sheet fixed to the bottom surface of the holding means.   The holding means includes a chuck top on which the semiconductor wafer is mounted and a suction hole disposed so as to be located outside a formation region of the backside illumination type solid-state imaging device, and the chuck top is fitted into an open upper portion. 3. A back-illuminated solid-state imaging device inspection apparatus according to claim 1, wherein the inspection device is a vacuum chuck comprising a support container formed as described above.   4. The inspection unit includes a probe card including a measurement probe that is in contact with the electrode pad, and a semiconductor tester that applies an electrical signal to the electrode pad via the probe card. The inspection apparatus for a backside illumination type solid-state imaging device according to any one of the above.

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