JP2005203679A - Method of manufacturing solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a solid-state image pickup device capable of significantly eliminating defects in image in dicing processing without deteriorating optical characteristics of the solid-state image pickup device. <P>SOLUTION: The method of manufacturing the solid-state image pickup device comprises a preparation process for preparing a semiconductor wafer formed with a plurality of solid-state image pickup devices; a rear surface polishing process for polishing the rear surface of the semiconductor wafer; an attaching process for attaching the semiconductor wafer to a dicing ring via a dicing tape; a hydrophilic process for applying hydrophilic treatment to the semiconductor wafer which is attached to the dicing ring, and to the adhesive material of the dicing tape; and a dicing process for dicing the semiconductor wafer, which is subjected to the hydrophilic treatment by a dicing blade, and cleaning the solid-state image pickup devices causing little damage to the solid-state image pickup devices, to remove a foreign matter that may attach thereto during the dicing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for manufacturing a solid-state imaging device, and more particularly to a dicing method for a solid-state imaging device.

  In general, dicing of a solid-state imaging device is performed by attaching a dicing tape to a dicing ring and mounting a semiconductor wafer thereon, and then cutting the semiconductor wafer with a dicing blade of a dicing apparatus. Since cutting waste is generated at the time of cutting, a large amount of pure water is used to flow the cutting waste out of the semiconductor wafer to obtain cleaning properties.

  In addition, when pure water is allowed to flow and the cutting waste is caused to flow out of the semiconductor wafer, a dry region may be generated on the semiconductor wafer, and the cutting waste may adhere to the dry region. In order to eliminate such a dry region, it is known to hydrophilize the wafer surface by subjecting the surface of the semiconductor wafer to plasma treatment. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 05-335412

  In the conventional dicing method of a solid-state imaging device, cutting waste generated when cutting a semiconductor wafer often gets on the solid-state imaging device and adheres, and image defects may occur after the assembly of the solid-state imaging device.

  In addition, the adhesive of the dicing tape that is exposed when the semiconductor wafer is cut may be peeled off by a large amount of pure water and may get on and adhere to the solid-state imaging device. This adhesive may also contribute to image defects in the solid-state imaging device.

  In order to physically remove the deposits on these solid-state image sensors, it is necessary to perform high-pressure water cleaning using a large amount of pure water. Is big.

  An object of the present invention is to provide a method for manufacturing a solid-state imaging device capable of performing dicing without deteriorating the optical characteristics of the solid-state imaging device.

  According to one aspect of the present invention, a method for manufacturing a solid-state imaging device includes a preparation step of preparing a semiconductor wafer on which a plurality of solid-state imaging devices are formed, a backside polishing step of polishing the backside of the semiconductor wafer, and the backside A dicing step of dicing the solid-state imaging device with low-damage cleaning and removing deposits generated by the dicing.

  According to another aspect of the present invention, a method of manufacturing a solid-state imaging device includes a preparation step of preparing a semiconductor wafer on which a plurality of solid-state imaging devices are formed, and dicing the semiconductor wafer through a dicing tape. A mounting step for mounting, a hydrophilic step for performing a hydrophilic treatment on the adhesive of the semiconductor wafer and the dicing tape mounted on the dicing ring, and dicing the hydrophilic semiconductor wafer with a dicing blade, And a dicing step of cleaning the solid-state imaging device with low damage and removing deposits generated by the dicing.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the solid-state imaging device which can improve the image defect in a dicing process significantly without degrading the optical characteristic of a solid-state imaging device can be provided.

  FIG. 1 is a diagram for explaining a method of manufacturing a solid-state imaging device according to an embodiment of the present invention.

  FIG. 1A is a cross-sectional view of the semiconductor wafer 1 before performing the back grinding process according to the present embodiment.

    The semiconductor wafer 1 is, for example, a silicon wafer having a diameter of 6 inches and a thickness of 500 μm. A solid-state imaging device 12 is formed on the semiconductor wafer 1 over a plurality of columns and a plurality of rows.

  The solid-state imaging device 12 is, for example, a CCD type solid-state imaging device, and includes a large number of photoelectric conversion elements, a vertical charge transfer device (VCCD) that transfers signal charges generated by the photoelectric conversion elements in the vertical direction, and on each photoelectric conversion element. And a peripheral circuit including a light receiving region including the microlens 32 and the like, a horizontal charge transfer device for transferring the signal charge transferred by the VCCD in the horizontal direction, and an output amplifier. The solid-state imaging device 12 is not limited to the CCD type, and may be a MOS type or the like.

The microlens 32 is formed on the surface of the solid-state image sensor 12 corresponding to each of a large number of photoelectric conversion elements formed on the solid-state image sensor 12. The microlens 32 is formed, for example, by forming a transparent resin layer on a planarizing film, patterning the transparent resin layer into a predetermined shape by a photolithography method or the like, and then performing reflow.
In the present embodiment, prior to the dicing process, the semiconductor wafer 1 is set in the back surface polishing apparatus, and the back grind is, for example, 300 μm or less with respect to the back surface of the semiconductor wafer 1 (the surface opposite to the surface on which the solid-state imaging device 12 is formed). Apply. By this back grinding, the semiconductor wafer 1 is in the state shown in FIG. 1B, and the thickness thereof is, for example, 300 μm.

  Thus, by reducing the thickness of the semiconductor wafer 1 prior to the dicing process, the cutting grooves 6 (FIG. 4) in the dicing process can be made shallower, and cutting chips generated during the dicing process are reduced. I can do it. Therefore, the cutting waste adhering to the solid-state image sensor 12 can be reduced.

  Next, the semiconductor wafer 1 subjected to the back grind shown in FIG. 1B is mounted on the dicing ring 2 via the dicing tape 3 to obtain the state shown in FIG.

  FIG. 2 is a plan view of the semiconductor wafer 1 mounted on the dicing ring 2. In addition, the cutting groove between each solid-state image sensor 12 shown with the dotted line in the semiconductor wafer 1 is not yet formed at this stage. Between the dicing ring 2 and the semiconductor wafer 1, the adhesive 4 of the dicing tape 3 is exposed at a portion indicated by oblique lines in the drawing. When the dicing process is performed in this state, the exposed adhesive material 4 may be melted by the cleaning during the dicing process and get on the surface of the solid-state imaging device 12. Accordingly, in this embodiment, the hydrophilic treatment is performed on the semiconductor wafer 1 mounted on the dicing ring 2.

  FIG. 3 is a cross-sectional view for explaining the hydrophilic treatment for the semiconductor wafer 1.

First, the semiconductor wafer 1 mounted on the dicing ring 2 is set in a reduced pressure O ₂ plasma chamber and subjected to a hydrophilic treatment. The plasma processing conditions are, for example, a high frequency power output of 50 (W), a chamber vacuum of 20 (Torr), and a gas flow rate used for processing of 10 (ml / min). Under such plasma processing conditions, for example, the plasma irradiation time is set to 10 (sec).

  By performing plasma treatment under the above conditions, a part of the exposed adhesive 4 of the dicing tape 3 can be removed and the surface of the remaining adhesive 4 can be hydrophilized. In practice, it is preferable that all of the adhesive 4 is removed by the plasma treatment. However, in this embodiment, the optical characteristics of the microlens 32 formed on the surface of the solid-state imaging device 12 are set as described later. Since it is necessary to maintain, not all of the adhesive 4 is removed, but a part is removed, and the rest is hydrophilized. That is, as long as the optical characteristics of the microlens 32 are not deteriorated, the processing may be performed under plasma processing conditions in which all of the adhesive 4 is removed.

  By the plasma treatment described above, the microlens 32 formed on the surface of the solid-state imaging device 12 is simultaneously subjected to a hydrophilic treatment. For example, the microlens 32 has a height of 1 μm and a diameter of about 3 μm. Under the above conditions, the surface of the microlens 32 is etched by about 0.03 μm. However, since it is about 3% of the height of the microlens 32, the optical characteristics of the microlens 32 are hardly affected.

It should be noted that under processing conditions equal to or higher than the plasma conditions, the exposed portion of the adhesive 4 of the dicing tape 3 that is the object of the plasma processing is removed and hydrophilized, and the surface of the microlens 32 is subjected to a rapid reaction. There is a possibility that the influence other than the hydrophilization, specifically, the deterioration of the optical characteristics of the microlens 32 and the deterioration of the electrical characteristics of the solid-state imaging device 12 may occur. Therefore, the plasma treatment in this embodiment needs to be under the low damage plasma conditions as described above. Here, the low damage plasma condition is, for example, a plasma processing condition in which etching of an organic substance is suppressed to 300 mm or less. The gas used for the plasma treatment is not limited to the O ₂ gas described above, but may be an O ₂ + Ar mixed gas.

  The hydrophilic treatment is not limited to plasma treatment. For example, the surface of the adhesive 4 and the micro lens 32 may be hydrophilized by surface modification by a photo-ozone method using ultraviolet radiation (UV) and ozone (O 3).

  In a normal state, the surface of the adhesive 4 does not have a hydrophilic group and repels cleaning water in a dicing process performed later, and may adhere to the semiconductor wafer 1 when flowing out with physical pressure. However, by performing the above-described hydrophilization treatment, the surface of the adhesive 4 can be modified to be hydrophilized and the cleaning performance can be improved without repelling the cleaning water. Further, since the surface of the microlens 32 is also modified and becomes hydrophilic, the adhered contaminants can be washed away without requiring high physical pressure.

  FIG. 4 is a diagram for explaining the dicing process of the semiconductor wafer 1. In the figure, white circles indicate cutting waste or other contaminants.

  In this step, first, the semiconductor wafer 1 that has undergone the hydrophilic treatment shown in FIG. 3 is set in the dicing apparatus 5. The dicing apparatus 5 includes at least a dicing blade 51 and a megasonic cleaning nozzle 52 disposed in the vicinity of the dicing blade. The megasonic cleaning nozzle 52 includes an oscillator and injects the cleaning water onto the surface of the semiconductor wafer 1 after applying vibrations of megahertz (MHz) or more to the cleaning water such as pure water.

  The dicing processing device 5 forms the cutting grooves 6 in the thickness direction of the semiconductor wafer 1 with a dicing blade 51. The cutting groove 6 is formed between each row and each column of the plurality of photoelectric conversion elements 12 formed on the semiconductor wafer 1 (see the dotted line in the semiconductor wafer 1 in FIG. 2). Since cutting scraps are generated by this cutting, cleaning water given a vibration of megahertz (MHz) or more is sprayed from the megasonic cleaning nozzle 52 to the semiconductor wafer 1 to generate the generated cutting scraps and other Contaminants (for example, the adhesive 4 that has flowed out) are poured out of the semiconductor wafer 1.

  Note that the cleaning of the semiconductor wafer 1 in the dicing process is not limited to that performed by the megasonic cleaning nozzle 52, and any method that does not damage the solid-state imaging device 12 formed on the semiconductor wafer 1 with a low physical pressure. Something like that. For example, the semiconductor wafer 1 may be cleaned by a two-fluid cleaning nozzle using pure water and air.

  After performing the above-described back grinding (back surface polishing) processing, hydrophilic treatment, and dicing processing, chip division, packaging, and the like are performed. These processes are based on well-known techniques.

  As described above, according to the embodiment of the present invention, since the thickness of the semiconductor wafer 1 is reduced by the back grinding (back surface polishing) process prior to the dicing process, the depth of the cutting groove 6 necessary for dicing is reduced. be able to. Therefore, the cutting by the dicing blade 51 can be shallowed, and the cutting waste generated by the cutting can be reduced. Moreover, since the cutting groove 6 can be made shallow, the removal of the cutting waste in the cutting groove 6 becomes easy.

  Moreover, according to the Example of this invention, adhesion of the adhesive material 4 to the semiconductor wafer 1 can be reduced by hydrophilizing the exposed surface of the adhesive material 4. Moreover, the detergency with washing water can be increased by making it hydrophilic. In addition, since a part of adhesive material 4 is removed in the hydrophilization treatment, it is considered that the amount of the adhesive material 4 itself flowing out decreases.

  Furthermore, according to the embodiment of the present invention, since the surface of the microlens 32 is also made hydrophilic, adhesion of cutting waste, the adhesive material 4 and other contaminants can be reduced. Further, even when contaminants or the like are attached, they can be easily removed.

  In addition, according to the embodiment of the present invention, contaminants from other than the semiconductor wafer 1 can be extremely reduced by the back grinding process and the hydrophilization process, and the surface of the solid-state imaging device 12 (the surface of the microlens 32) can also be reduced. Since it is hydrophilized, high detergency in the dicing process is not required. Therefore, it is not necessary to perform conventional high-pressure water cleaning for increasing the cleanliness in the dicing process. Therefore, it is possible to perform cleaning by a cleaning method with less damage to the solid-state imaging device 12, for example, megasonic cleaning. That is, in this embodiment, since the back grinding process and the hydrophilization process are performed prior to the dicing process, it is possible to greatly reduce large deposits, and thus high damage for physically removing these deposits. Cleaning is unnecessary, and high cleanliness can be obtained by cleaning by megasonic cleaning or the like for small deposits with lower damage.

  Further, according to the embodiment of the present invention, the back grinding process and the hydrophilization process, and the subsequent dicing process are performed, so that the image defects due to the attachment of cutting waste and other contaminants on the solid-state imaging device 12 are greatly reduced. Can be reduced.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is a figure for demonstrating the manufacturing method of the solid-state image sensor by the Example of this invention. 2 is a plan view of a semiconductor wafer 1 mounted on a dicing ring 2. FIG. 3 is a cross-sectional view for explaining a hydrophilic treatment for the semiconductor wafer 1. FIG. It is a figure for demonstrating the dicing process of the semiconductor wafer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Semiconductor wafer, 2 ... Dicing ring, 3 ... Dicing tape, 4 ... Adhesive material, 5 ... Dicing processing apparatus, 6 ... Cutting groove, 12 ... Solid-state image sensor, 32 ... Micro lens, 51 ... Dicing blade, 52 ... Mega Sonic cleaning nozzle

Claims (6)

Preparing a semiconductor wafer on which a plurality of solid-state imaging devices are formed; and
A back surface polishing step for polishing the back surface of the semiconductor wafer;
A solid-state imaging device manufacturing method comprising: a dicing step of dicing the semiconductor wafer whose back surface is polished with a dicing blade, and cleaning the solid-state imaging device with low damage to remove deposits generated by the dicing. Preparing a semiconductor wafer on which a plurality of solid-state imaging devices are formed; and
A mounting step of mounting the semiconductor wafer on a dicing ring via a dicing tape;
A hydrophilization step of performing a hydrophilization treatment on the semiconductor wafer attached to the dicing ring and the adhesive of the dicing tape;
And a dicing step of dicing the hydrophilic semiconductor wafer with a dicing blade and performing low-damage cleaning on the solid-state image sensor to remove deposits generated by the dicing. Furthermore, the manufacturing method of the solid-state image sensor of Claim 2 which has a back surface grinding | polishing process which grind | polishes the back surface of the said semiconductor wafer before the said mounting process. The method for manufacturing a solid-state imaging device according to claim 2, wherein the hydrophilization treatment removes at least a part of the adhesive. 5. The method for manufacturing a solid-state imaging device according to claim 2, wherein the hydrophilization treatment is a plasma treatment under a low damage plasma treatment condition for reducing an influence on other than the adhesive. The method for manufacturing a solid-state imaging device according to claim 1, wherein the cleaning in the dicing step is megasonic cleaning.

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