JPH07112056B2 - Wafer with solid-state image sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a solid-state imaging device-formed wafer capable of preventing contamination of the surface of the solid-state imaging device chip area in a wafer before dicing on which a plurality of solid-state imaging devices are formed. It is about.

[Conventional technology]

With the remarkable development of integrated circuit technology in recent years, solid-state image pickup devices (mainly mainly image pickup devices used for television cameras, etc.
CCD image sensors, etc.) are becoming the mainstream. Here, the basic structure of the CCD image sensor will be briefly described. A plurality of pixels composed of a photosensitive element, a switching element, and a capacitor and a shift register are formed on a semiconductor substrate, and the amount of light of an input image received for each pixel. Is generated by the photosensitive element for each pixel and stored in the capacitor for each pixel as a signal of the pixel, and the switching element for each pixel is controlled to store the accumulated charge of each pixel for one line by the capacitance for one line. It is said that an image signal is obtained by transferring the image signal to a shift register having the above and serially sending out from this shift register.

FIG. 3 is a diagram showing a schematic configuration of a CCD image sensor. (A) is an analog transfer scanning, line address transfer type configuration, (b) is a frame transfer type configuration, (c) is an interline transfer type configuration. Are shown respectively. Of these, in the analog transfer scanning and line address transfer type configuration of (a), each pixel PC stores a signal charge by a charge storage operation for a certain period and then, among the two-dimensionally arranged pixel groups to be read out. By the command from the vertical scanning shift register VS that specifies the row position to be read, the pixel group at the commanded row position operates as an analog shift register, and the accumulated signal charges are sequentially moved to the right side of the figure, The signal at the right end is the analog shift register in the column direction
It is sent out in order by VR and leads to the output terminal OUT. Then, the second pixel row is selected by a command from the vertical scanning shift register VS, and the signal charge is similarly led to the output terminal OUT. In the frame transfer type configuration of (b), the upper half area is the image area IM and the lower half area is the signal charge storage area CH. The image area IM has both the photoelectric conversion and charge transfer functions. There is a pixel group of, and here, after a charge proportional to the incident light information is accumulated in each pixel for a certain period of time, the signal charge disappears by transferring the signal charges of all the pixels PC to the accumulation region CH. The pixel in the image area is caused to accumulate the next signal charge. The storage area CH has the same number of device groups as the number of pixels of the image area IM having a transfer / storage function, and after the signal charges of all the pixels of the image area IM are stored here, respectively, One pixel for each column of pixels is sent to the horizontal analog shift register HR. The horizontal analog shift register HR has a capacity corresponding to the number of columns of pixels and receives a signal charge for each pixel for each column of pixels to obtain an image signal for one line and serially send the image signal. An image signal for a line is obtained. By repeating such work for the number of rows, scanning equivalent to reading by XY scanning by the electron beam in the image pickup tube (this is called a frame transfer method) is performed.

In addition, the interline transfer type configuration of (c) is such that the locations where photoelectric conversion and signal transfer are performed are different, and the photoelectric conversion area portion serves as the field of view of the pixel PC, A light receiving portion is provided at a position, and the light receiving portion accumulates a signal charge proportional to incident light information for a certain period of time, and a capacitance corresponding to the number of pixels in the column direction provided adjacent to each column in the pixel group in the column direction is stored. The signal is sent to the vertical analog shift register VR for vertical transfer, and the signal charge of each pixel PC is transferred to the vertical analog shift register VR corresponding to each pixel PC by this. Charge accumulation is performed. The vertical analog shift register VR corresponding to each column sends a signal charge for each pixel to the position corresponding to each column of the horizontal analog shift register HR to obtain an image signal for one line, and serially sends this out for one line. Get minute image signal.
By repeating such an operation for the number of rows, scanning equivalent to reading by XY scanning by the electron beam in the image pickup tube is carried out.

In addition, there is an on-chip filter type in which a color filter is directly formed on the element in a solid-state image sensor for a single-plate color camera which has been widely used in recent years. In this case, a mosaic color filter is used. Interline transfer type CCD that can be combined (hereinafter referred to as IT-CCD) is often used. This IT-CCD has a structure as described in FIG. 3 (c), and uses, for example, a photodiode as a light receiving portion in each pixel, and a storage diode is used as a capacitor for storing the output of this photodiode. , Vertical transfer CCD is used as the vertical analog shift register HR. A shift gate is used to control the transmission of signal charges from the photodiode output accumulated in the storage diode to the vertical transfer CCD, and this shift gate also serves as the transfer electrode of the vertical transfer CCD. IT-CCD
Then, each of a plurality of two-dimensionally arranged independent pixels includes a light receiving portion, a storage capacitor, and a vertical transfer CCD which is a reading portion for reading and transferring the signal charges stored in the capacitor. And this vertical transfer C
Since the CD part is light shielded, it becomes a sensitivity ineffective area, and the field of view of each pixel is only the area occupied by the light receiving part,
The detection efficiency becomes poor. Therefore, in order to effectively use this sensitivity ineffective area, an amorphous silicon (a-Si) layer for photoelectric conversion is laminated on the entire pixel area including the sensitivity ineffective area, and generated by the light incident on this amorphous silicon layer. Amorphous silicon laminated structure CCD, etc., in which charge signals are stored in the storage portion of the corresponding pixel and taken out, have also appeared.

[Problems to be Solved by the Invention]

By the way, such CCD image sensors having various structures are processed and formed on a semiconductor wafer for a plurality of chips at a time according to a predetermined semiconductor process. And
After forming the on-chip color filter, the scribe groove, which is a dividing groove for separating each CCD image sensor chip, is placed on the outer periphery of each CCD image sensor chip on this semiconductor wafer, and processed. In the process, the semiconductor wafer is divided along the scribe groove (dicing), fixed on a supporting substrate and wire-bonded to complete an element.

By the way, in the case of forming an on-chip color filter, CCD image sensors for a plurality of chips are formed on a semiconductor wafer, and R of each CCD image sensor is further formed.
On the red (red), G (green), and B (blue) pixels, only the red pixel is formed on the red filter forming step, and the green filter forming step is formed on the green pixel only on the blue filter forming step. Then, a dyeable transparent filter base is formed only on each pixel for blue, and this is dyed with each corresponding color. Then, it is shipped as a semi-finished product with the scribe groove formed, and in the final step, the semiconductor wafer is diced along the scribe groove, fixed on a supporting substrate and wire-bonded to complete an element.

When forming an on-chip color filter in this way, it is necessary to form a dyeable transparent filter base and dye this, and this filter formation process is different from the normal semiconductor manufacturing process. In addition to dyeing, a dye-proof filter is provided with a dye-proof film so that the dyed filter will not be affected by the dyeing of other colors to be dyed. Since a step of performing a stain-proofing process such as a chemical process is also included, an on-chip color filter manufacturing process is necessary in addition to the usual semiconductor device manufacturing process, and these are completely separated in the process. Therefore, the wafer on which a plurality of CCD image sensors manufactured by the semiconductor manufacturing process is formed is carried to the factory of the on-chip color filter manufacturing process, the filter is formed, and the final process factory is carried and mounted. It is necessary to say that it is finished.

A problem in this transportation process is dirt on the pixel surface of the CCD. Particularly in recent years, in order to maintain high quality, in the technical fields of semiconductor manufacturing technology and dyeing technology, the miniaturization of pixels, the miniaturization of on-chip color filters accompanying it, and the strict requirements for the optical characteristics of filters have been considered. The use of the individual technology cultivated is inevitable, and the division of labor, which is responsible for the formation of on-chip color filters in the printing industry, which has won the manufacturing technology of on-chip color filters, is progressing more and more. ing. Therefore, it is necessary to transport the wafer of the CCD image sensor on which the on-chip color filter is formed as a semi-finished product, but since the CCD image sensor is an image sensor, the light receiving surface is exposed.
If dust or dirt adheres here, it may cause element failure. And when transporting wafers as semi-finished products,
Completely protecting the exposed light receiving surface from dust and dirt is a difficult technique.

Therefore, an object of the present invention is to make it possible to protect the light receiving surface of the CCD image sensor part from dust and dirt when the wafer on which the CCD image sensor is formed is transported as a semi-finished product, and further, the final step. Another object of the present invention is to provide a solid-state imaging device forming wafer that is easy to handle.

[Means for Solving the Problems]

In order to achieve the above object, the present invention is configured as follows. That is, a plurality of solid-state image pickup devices are formed which are composed of a plurality of pixels, convert light incident on the light-receiving surface of these pixels into signals, and sequentially take out the converted signals for each pixel to obtain output signals. In the above wafer, the effective chip area of each of the solid-state imaging devices formed on the wafer is covered with a peeling protective film.

[Action]

In such a configuration, the effective chip area of each of the solid-state image pickup devices on the wafer formed with a plurality of solid-state image pickup devices is covered with a peeling protective film, and the protective film directly removes dust and dirt. , To prevent adhesion to the surface of the solid-state image sensor formation region. And, since the protective film is of a peeling property, peeling is easy,
Since it does not stick to the surface of the solid-state image sensor formation area,
If the wafer is peeled and removed after the solid-state image pickup device is divided, it can be surely protected from dust and dirt during transportation, and it is possible to prevent element failure due to the attachment of dust and dirt.

Therefore, it cannot be covered with an oxide film or the like. Moreover, it has a special area called the light-receiving surface that must be kept clean.
When a wafer on which a solid-state image sensor such as a CCD image sensor is formed is transported as a semi-finished product, the light-receiving surface of the solid-state image sensor can be reliably protected from dust and dirt. It is possible to provide a wafer for forming a solid-state imaging device, which is easy to handle.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 (a) is a plan view showing a solid-state imaging device forming wafer, and FIG. 1 (b) is a plan view of one embodiment showing a state in which the present invention is applied to the solid-state imaging device forming wafer of (a). Is. In (a), 1 is a solid-state image pickup element forming wafer, and a plurality of solid-state image pickup elements 2 are formed orderly on this wafer 1 by a manufacturing process of a semiconductor device.
A scribe groove 3 that is a dividing groove for separating the plurality of solid-state image pickup devices 2 is formed so as to be cut vertically and horizontally by using a gap between the solid-state image pickup devices 2, and is formed in a later step. Wafer 1 along this scribe groove 3
Each solid-state image sensor 2 is separated by dividing. Incidentally, 2a
Is a light receiving surface of the solid-state image sensor 2. On the solid-state imaging device forming wafer 1 as shown in FIG.
After forming the filter as an on-chip filter,
As shown in (b), an effective chip area of each solid-state image pickup element 2 in the solid-state image pickup element forming wafer 1, that is, an area where a chip of the solid-state image pickup element 2 is formed, has a peeling coating material (having a good peeling property). Coating material) is coated to form the protective film 4. Since the area of the effective chip area of each solid-state image sensor 2 is relatively large, this coating can be applied only to a necessary area by using a screen printing technique or the like.

Here, it should be noted that the peeling coating material is not applied to the scribe groove 3 which is a dividing groove for separating the plurality of solid-state image pickup devices 2. This is because when the peeling coating material is applied to the scribe groove 3, a part of the protective film 4 of the solid-state image pickup device 2 is covered with the scribe groove 3.
This is to prevent the protective film 4 from peeling off when dicing.

In this way, the peeling coating material is coated on the effective chip area portion of each solid-state image sensor 2 on the solid-state image sensor forming wafer 1, and the peeling coating material is transferred to the factory in the subsequent step with the protective film 4 formed. At 1, the wafer 1 is diced and separated into individual solid-state image sensor chips. Then, after mounting the separated solid-state image pickup element chip on the support substrate, as shown in FIG.
The protective film 4 on the chip is peeled off and wiring is performed to complete the solid-state imaging device. The protective film 4 is formed in the effective chip area of the solid-state image sensor 2, and therefore, is formed in the area outside the light receiving surface 2a and in the area not covered by the scribe groove, so that it does not peel off during dicing. ,
Further, at the time of peeling, this can be peeled off without touching the light receiving surface 2a.

As described above, this device is composed of a plurality of pixels, converts the light incident on the light receiving surface of these pixels into a signal, and sequentially extracts the converted signals for each pixel to obtain an output signal. In a wafer on which a plurality of image pickup devices are formed, the effective chip area of each solid-state image pickup device formed on the wafer is covered with a peeling protective film. And
By covering the effective chip area of each solid-state image sensor on the wafer with a peeling protective film, the protective film prevents dust and dirt from directly adhering to the surface of the solid-state image sensor forming area. Since the protective film has peeling properties, peeling is easy, and the solid-state image sensor formation region surface does not stick to the surface. It can be surely protected from dust and dirt, and it becomes possible to prevent element failure due to adhesion of dust and dirt.

Therefore, it has a special area called a light-receiving surface that cannot be covered with an oxide film or the like and must avoid contamination.
When a wafer on which a solid-state image sensor such as a CCD image sensor is formed is transported as a semi-finished product, the light-receiving surface of the solid-state image sensor can be reliably protected from dust and dirt. Has the advantage that it can be handled easily.

The present invention is not limited to the embodiments described above and shown in the drawings, and can be appropriately modified and implemented within the scope of the invention.

〔The invention's effect〕

As described above in detail, according to the present invention, it becomes possible to prevent element failure due to adhesion of dust or dirt, and therefore,
When a wafer on which a solid-state image sensor with a special area called a light-receiving surface that cannot be covered with an oxide film or the like must be avoided should be transported as a semi-finished product, the light-receiving surface of the solid-state image sensor should be This makes it possible to provide a solid-state imaging device forming wafer that can be reliably protected from dust and dirt and that can be easily handled in a later step.

[Brief description of drawings]

FIG. 1 is a plan view for explaining an embodiment of the present invention, FIG. 2 is a view showing a step of peeling a protective film, and FIG. 3 is a schematic structure of a conventional general CCD image sensor. FIG. 1 ... Solid-state image sensor forming wafer, 2 ... Solid-state image sensor, 2a
... light receiving surface, 3 ... scribe groove, 4 ... protective film.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Katsuaki Shimizu 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd. (72) Inventor Shigetaka Nakazawa 1-1-5 Taito, Taito-ku, Tokyo Toppan Within Printing Co., Ltd. (56) Reference JP-A-57-42009 (JP, A) JP-A-63-21604 (JP, A) Actual development Sho-56-78270 (JP, U) Actual development Sho-63-197359 ( JP, U)

Claims (1)

[Claims] 1. A solid-state image pickup device comprising a plurality of pixels, which converts light incident on a light-receiving surface of these pixels into a signal and obtains an output signal by sequentially taking out the converted signal for each pixel. 2. A solid-state image pickup element forming wafer, comprising: a plurality of wafers each having a plurality of layers formed thereon, and an effective chip area of each of the solid-state image pickup elements formed on the wafer is covered with a peeling protective film.