JP2008198779A - Method for manufacturing a plurality of semiconductor devices - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing semiconductor devices wherein dicing lines can be determined from the rear face side. <P>SOLUTION: After surface-side electrodes (3a, 3b, 3c, ...) are formed on the surface 1b of a wafer 1, the rear face 1a thereof is polished by a polishing grindstone 5. In this case, a pressure is applied to the polishing grindstone 5 downward from above, so that the wafer is elastically deformed and convex strips 9 are produced in the spacings 7 between the surface-side electrodes. After the polishing is completed, when the pressure is released, the wafer returns to the natural shape, and convex strips 13 are produced on the rear face 1a of the wafer 1. The positions of the produced convex strips 13 correspond to the spacings 7 between the surface-side electrodes. Thus, the dicing lines can be determined from the rear face side by measuring the convex strips 13 from the rear face side with a spectroscopic measuring device 19. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a plurality of semiconductor devices through a process of dicing a wafer.

A method of manufacturing a plurality of semiconductor devices from a single wafer by passing through a wafer dicing process has become widespread.
When manufacturing a plurality of semiconductor devices from a single wafer, (1) a plurality of semiconductor structures as units constituting a semiconductor device as a unit are arranged in a lattice shape when the wafer is viewed in plan view. In the positional relationship, a step of forming in one wafer, and (2) a plurality of surface side electrodes as a unit corresponding to a semiconductor structure as a unit are arranged in a lattice shape when the wafer is viewed in plan view. The process of forming on the surface of one wafer is carried out according to the positional relationship.

When dicing a wafer having surface-side electrodes arranged in a lattice shape from the surface side, a dicing line can be determined based on the position of the surface-side electrodes arranged in a lattice shape.
However, when the wafer is diced from the back side, it is difficult to determine the dicing line because the front side electrode cannot be visually recognized.

  Techniques for observing a wafer from the back side and determining a dicing line are disclosed in Patent Document 1 and Patent Document 2. In the techniques disclosed in these publications, a fluoroscopic measuring device including an infrared light emitting element and a light receiving element is used. By irradiating the wafer with infrared rays from the back side of the wafer, the wafer itself is transparent to infrared rays, whereas the surface side electrode reflects infrared rays, so by receiving infrared rays returning from the wafer on the back side of the wafer, The position where the surface side electrode is arranged can be measured through the wafer. A dicing line can be determined if the position of the surface-side electrodes arranged in a lattice shape can be seen through.

Japanese Patent Laid-Open No. 2004-22936 Japanese Patent Laid-Open No. 11-330013

If the fluoroscopic techniques disclosed in Patent Document 1 and Patent Document 2 are used, it seems that the wafer can be diced from the back side without any problem.
However, it may be difficult to measure the arrangement position of the front surface side electrode through the back surface side. For example, if the back surface of the wafer that has been thinned by polishing the back surface is rough, the infrared rays used for fluoroscopy will be scattered on the back surface, so that it is possible to measure the arrangement position of the surface side electrode through the back surface side. There are things that cannot be done. In addition, when manufacturing a vertical semiconductor device in which electrodes are also formed on the back surface, the back surface side electrodes prevent the passage of infrared rays, so that the arrangement position of the front surface side electrodes can be measured through the back surface side. There are things that cannot be done.
There is a need for a method that can determine the dicing line by observing from the back side of the wafer without using the fluoroscopic technique. The requirement that the wafer is diced from the back side occurs in various cases. Dicing from the back side requires less stress on the semiconductor structure, and a high-quality semiconductor device may be manufactured with a high yield. Since large irregularities are formed on the back surface side of the wafer, the back surface of the wafer cannot be fixed with a dicing tape.
The present invention provides a method of determining a dicing line by observing from the back surface side of the wafer without using a fluoroscopic technique when dicing the wafer from the back surface side for various reasons.

The present invention relates to a method of manufacturing a plurality of semiconductor devices through a process of dicing a wafer from the back side.
The manufacturing method of the present invention includes the following steps.
(1) A positional relationship in which a plurality of surface-side electrodes serving as units corresponding to a semiconductor structure serving as a unit constituting a semiconductor device serving as a unit are arranged in a lattice pattern on the wafer surface when the wafer is viewed in plan view. The process of forming in,
(2) A step of polishing the back surface of the wafer in a state in which the pressure on the back surface of the wafer is applied to the front surface and a portion located at the interval between the front surface side electrodes of the wafer is elastically deformed to the front surface side,
(3) A step of dicing the wafer from the back surface side of the wafer with reference to a protrusion generated on the back surface of the wafer when the pressure is released.

In the above method, the back surface is polished in a state in which pressure toward the front surface is applied to the back surface of the wafer. When a pressure toward the front surface is applied to the back surface of the wafer, the wafer at the portion where the surface-side electrode is formed is not deformed, whereas the wafer is elastically deformed toward the front surface at a portion located in the space between the front-side electrodes. When the pressure is released after the back surface is polished and flattened in this state, the wafer that has been elastically deformed to the front surface side returns to the natural shape at the portion located in the space between the front surface side electrodes, and the ridges are formed on the back surface of the wafer. Occurs. The positions of the ridges on the back surface correspond to the distance between the surface side electrodes. As a result, the dicing line can be determined by observing from the back side of the wafer. The method of the present invention does not rely on fluoroscopic techniques.
The above method does not rely on fluoroscopy technology, so for example, when the back side is rough and cannot be seen through, or when the back side electrode is formed and cannot be seen through, the surface side is observed from the back side. The arrangement position of the electrode can be measured.
According to the above method, for example, when dicing from the back side in order to reduce the stress applied to the semiconductor structure, or when dicing is possible only from the back side because large irregularities are formed on the back side, etc. Can be measured, and dicing can be performed along a correct dicing line.

  According to the method of the present invention, when dicing a wafer from the back side for various reasons, it becomes possible to determine a dicing line without using a fluoroscopic technique.

The main features of the embodiments described below are first organized.
(Characteristic 1) The polishing step is performed with a protective tape attached to the surface of the wafer.
(Feature 2) A polishing process is performed in a state where a dicing tape is attached to the surface of the wafer and the dicing tape is fixed to a dicing frame.

  FIG. 1A shows a perspective view of the wafer 1 from the back surface 1a side, and FIG. 1B shows a cross-sectional view of the wafer 1. FIG. The wafer 1 is (1) a plurality of semiconductor structures (not shown) as units constituting a semiconductor device (not shown) as a unit in the wafer, in a lattice shape when the wafer is viewed in plan view. (2) A plurality of surface side electrodes (3a, 3b, 3c,...) Serving as units corresponding to the semiconductor structure serving as a unit, and the wafer being planarized. Manufactured through a process of forming in a positional relationship arranged in a lattice when viewed. The front surface side electrodes 3a, 3b, 3c,... Are arranged in a lattice shape with a distance 7 between the surface 1b of the wafer 1, and a corresponding semiconductor structure is formed in the wafer 1. The surface side electrodes 3b, 3c,... Have the same pattern as the surface side electrode 3a.

In the step of polishing the back surface 1a of the wafer 1, in order to protect the front side electrodes 3a, 3b, 3c... Of the wafer 1 or to reinforce the wafer 1, the protective tape 10 is attached to the front surface 1b of the wafer 1. Processing proceeds.
2A shows a process of polishing the back surface 1a of the wafer 1 in order to make the wafer 1 thinner, and FIG. 2B shows a cross-sectional view of the wafer 1 during the process. In the polishing step, force is applied to the polishing grindstone 5 from below to below. Since the surface-side electrodes 3a, 3b, 3c,... Have a predetermined thickness, the surface 1b of the wafer 1 is supported from below at a portion located at a distance 7 between the surface-side electrodes 3a, 3b, 3c,. It is not done. When the polishing grindstone 5 applies a pressure toward the front surface 1b to the back surface 1a of the wafer 1, the front surface 1b of the wafer 1 is not supported from below because it is located at a distance 7 between the front surface side electrodes 3a, 3b, 3c. At the site, the wafer 1 is elastically deformed toward the surface 1b. In the polishing step, the back surface 1a is polished flat in a state where the wafer 1 located at the interval 7 between the front surface side electrodes 3a, 3b, 3c,... Is elastically deformed toward the front surface 1b.

  When the polishing step is completed and the polishing grindstone 5 is separated from the back surface 1a, the pressure that has elastically deformed the wafer 1 is released, and the surface side is located at a position 7 located between the surface side electrodes 3a, 3b, 3c,. The wafer 1 that has been elastically deformed is restored to its natural shape, and the ridge 13 is generated on the back surface 1 a of the wafer 1. The position of the ridge 13 generated on the back surface 1a corresponds to the interval 7 between the surface side electrodes 3a, 3b, 3c,. As a result, the dicing line can be determined by observing from the back surface 1a of the wafer 1.

  FIG. 3A shows a perspective view of the wafer 1 after completion of the polishing process from the back surface 1a side, and FIG. 1B shows a cross-sectional view of the wafer 1. FIG. On the back surface 1a of the wafer 1, protrusions 13 are generated at positions corresponding to the distance 7 between the front surface side electrodes 3a, 3b, 3c. The protrusions 13 correspond to the intervals 7 extending in a lattice shape and appear in a lattice shape on the back surface 1b.

  Next, as shown in FIG. 4, the wafer 1 on which the protrusions 13 on the lattice appear on the back surface 1a is diced. After the protective tape 10 affixed to the surface of the wafer 1 is peeled off, it is affixed to the dicing tape 15 on the surface 1 a of the wafer 1, and the dicing tape 15 is fixed to the dicing frame 17. In this state, the position of the ridge 13 is measured by the spectrometer 19 and the wafer 1 is diced by moving the dicing blade 23 along the measured ridge 13. The wafer 1 is diced along lattice lines dividing the semiconductor structure as a unit and the surface-side electrode.

  The measuring method of the ridge 13 is not limited to a specific method. The height distribution of the back surface 1 a of the wafer 1 may be measured to measure the position of the ridge 13. Alternatively, the position of the ridge 13 may be measured by measuring the thickness distribution of the wafer 1. In addition to an optical measurement method including interference measurement, a mechanical measurement method or a measurement method using a magic mirror can be used. If the detection accuracy in the horizontal and vertical directions when measuring the height distribution or thickness distribution of the back surface 1a of the wafer 1 is about 1 μm, the position of the ridge 13 is measured to determine the correct dicing line position. Can do.

As shown in FIG. 5, at the stage of thinning the back surface 21 a of the wafer 21, only the central portion of the back surface 21 a of the wafer 21 may be polished and the ribs 11 may be left in the peripheral portion of the back surface 21 a of the wafer 21. In this case, the rib 11 formed in the peripheral portion is thick, and even if the inner cut portion 12 is very thin, there is an advantage that the wafer 21 is not broken.
In the case of such a wafer 21, there is a large unevenness on the back surface 21a, and the back surface 21a cannot be fixed with a dicing tape. It is necessary to fix the front surface 21b and dice from the back surface 21a side. The technique of the present invention is particularly effective for dicing the wafer 21 having the mid-cut portion 12 on the back surface 21a.

  As shown in FIG. 6, the back surface side electrode 33 may be formed on the back surface 31 a of the wafer 31 after the protrusions 13 indicating the dicing lines appear on the back surface 31 a of the wafer 31. Even after the back surface side electrode 33 is formed, the protrusion 35 remains at the position of the protrusion 13 indicating the dicing line. Therefore, the dicing along the protrusion 35 may be performed after the back surface side electrode 33 is formed. By using the spectrometer 19 as well, the position of the ridge 35 appearing on the exposed surface of the back-side electrode 33 can be measured.

  As shown in FIG. 7, the wafer may be diced using a laser beam 37 instead of the dicing blade.

(A) is the figure which looked at the wafer 1 from the back surface 1a side, (b) is sectional drawing of the wafer. (A) is a figure which shows the process of grind | polishing the wafer 1, (b) is sectional drawing of the wafer in the process. (A) is the figure which looked at the wafer 1 after grinding | polishing from the back surface 1a side, (b) is sectional drawing of the wafer. FIG. 4 is a diagram showing a process of measuring the protrusion 13 using the spectroscopic measuring device 19 and dicing the wafer 1 based on the measurement result. FIG. 5 is a view corresponding to FIG. 2 of another embodiment, and shows a state in which the rib 21 and the mid-cut portion 12 are formed and the wafer 21 is polished. FIG. 6 is a view corresponding to FIG. 3 of another embodiment, and shows the state of the wafer in which the back surface side electrode 31 is formed on the back surface 31 a of the wafer 31. FIG. 7 is a view corresponding to FIG. 4 of another embodiment, and shows a process of dicing a wafer using a laser beam 37.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wafer 3a, 3b, 3c ... Surface side electrode 5 ... Polishing whetstone 7 ... Space | interval 9 of a surface side electrode ... Ridge 10 on the surface side ... Protective tape 11 ... Rib 13 ... Back side protrusion 15 ... Dicing tape 17 ... Dicing frame 19 ... Spectrometer 21 ... Sharpened wafer 23 ... Dicing blade 31 ... Back side electrode Formed wafer 33 ... back side electrode 35 ... ridge 37 on back side electrode ... laser beam

Claims (2)

A method of manufacturing a plurality of semiconductor devices through a process of dicing a wafer,
On the surface of the wafer, a plurality of surface-side electrodes that are units corresponding to a semiconductor structure that is a unit constituting a unit semiconductor device are formed in a positional relationship that is arranged in a lattice when the wafer is viewed in plan view. And a process of
Polishing the back surface of the wafer in a state in which the pressure is applied to the back surface of the wafer and the portion of the wafer located at the interval between the front side electrodes is elastically deformed to the front surface side;
Dicing the wafer from the back side of the wafer on the basis of the protrusion generated on the back side of the wafer when the pressure is released; and
A method for manufacturing a semiconductor device, comprising:   2. The method according to claim 1, wherein a step of forming a back side electrode on the back side of the wafer is performed between the step of polishing the back side of the wafer and the step of dicing from the back side of the wafer.

Images