KR100607199B1 - Apparatus for grinding back of wafer - Google Patents

Abstract

The present invention relates to a wafer backside polishing apparatus, comprising: a chamber in which wafer backside polishing is performed; A spin chuck installed inside the chamber to hold a wafer and rotate the wafer; A water jet injector installed at an upper portion of the spin chuck and spraying a water jet at a high speed and high pressure on a rear surface of the wafer rotated while being held by the spin chuck for polishing the back of the wafer; And a high pressure pump for supplying high pressure water to the water jet injector.

According to the present invention, the wafer back surface is prevented from being scratched and thermally deformed at the time of polishing the wafer, thereby minimizing wafer breakage and maximizing semiconductor manufacturing yield and productivity by minimizing the overall process time required for polishing. There is an advantage to this.

Wafers, Grinding and Water Jets

Description

Wafer back surface polishing apparatus {APPARATUS FOR GRINDING BACK OF WAFER}

1 is a schematic configuration diagram of a wafer back surface polishing apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged perspective view of portion A of FIG. 1.

3 is an operation diagram for explaining the operation of the wafer back surface polishing apparatus of FIG.

4 is a schematic plan view illustrating a state in which a wafer back surface is polished through the wafer back surface polishing apparatus of FIG. 1.

** Description of the symbols for the main parts of the drawings **

100 chamber 110 spin chuck

120: cover 122: outlet

130: water jet injector 132: nozzle

134: spindle 150: high pressure pump

152: water supply pipe

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer backside polishing apparatus, and more particularly, to a wafer backside polishing apparatus for thinning a wafer for miniaturization and high integration of a semiconductor package prior to the assembly process, which is a final process for manufacturing a semiconductor package. It is about.

In general, semiconductor packages are completed through a multi-step process. That is, the photo, etching, diffusion, thin film processes, etc. are repeatedly performed several times, and after the FAB (fabrication) process of forming an electric circuit pattern on the wafer, the electrical characteristics and operating states of each chip constituting the wafer are examined. It goes through an EDS (Electric Die Sorting) process that tests and sorts good and bad parts. In addition, the chip, which is determined to be good through the EDS process, is cut into chips and then assembled into a completed semiconductor package.

On the other hand, wafers in the FAB process and the EDS process need to maintain some strength to withstand the impact and external force applied during the handling process, and must have a sufficient thickness for this. On the other hand, a thinner wafer is advantageous for miniaturization and high integration of the completed semiconductor package after cutting in chip units as described above.

Therefore, during FAB process and EDS process, the thickness of the wafer is generally maintained at about 750 μm, and then the back side of the wafer, that is, the surface opposite to the surface on which the electric circuit pattern is formed, is polished before the wafer is cut into chips for the assembly process. Is reduced to approximately 280 μm.

Conventional mechanical polishing apparatus for mechanically polishing the back surface of a wafer includes a rotatable wafer chuck on which a wafer is placed so that the back side is faced up with a protective film coated on the front surface of the wafer, and is located above the wafer chuck and rotated. It is largely composed of diamond wheels mounted on the underside of the spindle. The polishing process through the polishing apparatus is as follows. First, when the spindle is lowered and the diamond wheel mounted below it rotates while pressing the back surface of the wafer, the wafer chuck is rotated in the opposite direction and the diamond wheel and the back surface of the wafer are polished by friction.

On the other hand, more specifically, the diamond wheel is usually composed of two types, the first is the first diamond wheel of about 350 mesh having a rather rough surface used to polish the amount less than about 20㎛ the polishing target, the second is the rest A second diamond wheel on the order of about 2000 mesh with a finer surface used to polish 20 μm.

Polishing on the back surface of the wafer through the conventional mechanical polishing apparatus having these two types of diamond wheels is performed by first polishing the amount less than about 20 μm from the polishing target value using the first diamond wheel, and then the second diamond. And grinding the remaining 20 μm using a wheel.

However, the above-described conventional mechanical polishing apparatus has the following problems.

Firstly, the first diamond wheel described above not only generates a large amount of particles as the surface particles fall off during the polishing process, but also the deeply scratched particles of the newly exposed portions are often called sawmarks on the backside of the wafer. It leaves a (scratch), there is a problem that the saw marks are relatively sharp to form the surface curvature to form a texture causing damage to the external impact.

Secondly, further polishing by the second diamond wheel can alleviate the above-mentioned problem of the saw marks to some extent, but the finest scratches are still caused by the second diamond wheel itself, so the final flat mirror finish ( For a flat mirror finish, a separate subsequent process, the polishing process, is required. However, the polishing process requires not only separate equipment but also transfers wafers to such separate equipment, thereby preventing the polishing process from being continuously performed. Therefore, additional time and cost problems arise.

Third, high heat is generated by the friction between the diamond wheel and the wafer during the mechanical polishing, and the high heat acts on the wafer in a state where the thickness is thin, causing thermal deformation, so-called bow- warp) phenomenon occurs. In addition, due to this bow phenomenon, there is a problem that breakage occurs in the process of being loaded into the cassette for moving to the separate polishing equipment described above.

The present invention has been made to overcome the disadvantages of the prior art as described above, to prevent scratches and thermal deformation of the wafer back surface when polishing the back surface of the wafer to minimize the breakage of the wafer, as well as necessary for polishing It is a technical problem to provide a backside polishing apparatus that can minimize the overall process time.

Wafer back surface polishing apparatus according to the present invention for achieving the above technical problem, the wafer back surface polishing is performed; A spin chuck installed inside the chamber to hold a wafer and rotate the wafer; A water jet injector installed at an upper portion of the spin chuck to spray a water jet at a high pressure and a high speed on a rear surface of the wafer rotated while being held by the spin chuck for polishing the back of the wafer; And a high pressure pump for supplying high pressure water to the water jet injector.

That is, the wafer back surface polishing apparatus according to the present invention minimizes damage to the wafer by preventing scratches and thermal deformation from occurring on the back surface of the wafer by performing back surface polishing through a water jet sprayed at high pressure and high speed. In addition, by minimizing the overall process time required for polishing, the ultimate semiconductor manufacturing yield and productivity can be maximized.

Preferably, the water jet injector includes a cylindrical spraying unit having a plurality of nozzles, a spindle positioned above the spraying unit to rotate the spraying unit, and a head positioned above the spindle to support the spindle. And, it can be installed to enable horizontal movement from the top of the spin chuck.

In addition, the plurality of nozzles may be installed to have a predetermined interval along the lower edge of the injection portion, it may be installed inclined downward so that the water jet injected during the rotation of the injection portion has a funnel shape.

In addition, a cup-shaped cover is installed around the spin chuck to prevent scattering of the water jet used for polishing the back surface of the wafer, and a discharge port for collecting and discharging the used water jet to the outside of the chamber. Can be.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the wafer back surface polishing apparatus according to the present invention.

1 is a schematic configuration diagram of a wafer back surface polishing apparatus according to an embodiment of the present invention, and FIG. 2 is an enlarged perspective view of portion A of FIG. 1.

Referring to FIG. 1, a chamber 100 for performing backside polishing of a wafer W is shown. The chamber 100 is provided with a spin chuck 110 for holding the wafer W and rotating the wafer W. The upper surface of the spin chuck 110 sucks and fixes the wafer W. Vacuum holes (not shown) are formed.

In addition, a lower portion of the spin chuck 110 supports the spin chuck 110, and a rotation shaft 112 for transmitting rotational force is connected, and a lowering force for rotating the wafer W is provided below the rotation shaft 112. Providing a first driver 114 is connected. Here, reference numeral T denotes a protective tape for protecting the electric circuit pattern formed on the front surface of the wafer W while the backside polishing of the wafer W is performed.

On the other hand, around the spin chuck 110 to prevent the scattering of the water jet used for polishing the back surface of the wafer (W) to be described later, the discharge port 122 for collecting the used water jet to discharge to the outside of the chamber 100 ) Is provided with a cup-shaped cover 120. The drive shaft 124 for vertically moving the cover 120 is connected to the lower portion of the cover 120, the second drive unit for providing a driving force for the vertical movement of the cover 120 in the lower portion of the drive shaft 124 126 is connected.

Meanwhile, water for spraying water jet at high pressure and high speed on the back surface of the wafer W which is rotated while being held by the spin chuck 110 for polishing the back surface of the wafer W on the upper portion of the spin chuck 110. Jet injector 130 is installed.

The water jet injector 130 has a cylindrical spraying unit 136 having a plurality of nozzles 138 and a spindle 134 positioned above the spraying unit 136 to rotate the spraying unit 136. And a head 132 positioned above the spindle 134 and supporting the spindle 134. In addition, the water jet injector 130 supplies high pressure water required to generate a wet jet which is injected at high pressure and high speed from the high pressure pump 150 to the back surface of the wafer W through the flowable water supply pipe 152. Receive.

On the other hand, one side of the head 132 of the water jet injector 130, the operating rod 142 is linearly connected by the third driving unit 140 is connected. Through this, the water jet injector 130 may horizontally move on the wafer W held by the spin chuck 110.

On the other hand, with reference to Figure 2 will be described in more detail with respect to the cylindrical injection portion 136 is provided with a plurality of nozzles (138). The injection unit 136 is configured to be rotatable by the spindle 134 provided thereon. In addition, the plurality of nozzles 138 formed in the injection unit 136 are installed to have a predetermined interval along the lower edge of the injection unit 136, the injection from the plurality of nozzles 138 in accordance with the rotation of the injection unit The water jet to be installed is inclined downward to have a funnel shape.

3 is an operation view for explaining the operation of the wafer back surface polishing apparatus of FIG. 1, the operation of the wafer back surface polishing apparatus according to the present invention with reference to FIGS. 1 and 3 as follows.

First, as shown in FIG. 1, the wafer chuck is transported with the upper end of the cover 120 positioned to form the same height as the spin chuck 110 so that the rear surface thereof faces upward. ) And is vacuum-adsorbed and fixed by the spin chuck 110. Next, as shown in FIG. 3, the water jet injector 130 is horizontally moved by the third driver 140 so as to be positioned above the wafer (W).

Next, the second driving unit 126 is operated to move the cover 120 to the height of the plurality of nozzles 138 provided in the water jet injector 130. Then, the first driving unit is operated to rotate the spin chuck 110. Next, the high pressure pump 150 operates to supply high pressure water to the water jet injector 130, and the spindle 134 rotates in a direction opposite to the rotation direction of the spin chuck 110 to be connected to the lower part. The water jet is sprayed toward the back surface of the wafer W at high pressure and high speed through the plurality of nozzles 138 provided below the spray unit 136 while rotating 136.

FIG. 4 is a schematic plan view showing the wafer back surface being polished by the wafer back surface polishing apparatus of FIG. 1. As described above, the spin chuck 110 rotates the jet 136 provided in the water jet injector 130. The water jet 139 sprayed at high pressure and high speed through a plurality of nozzles 138 installed under the jetting unit 136 while rotating in the opposite direction to the back surface is, as shown, the back surface 10 of the wafer W 10. ) To form an arc shape.

In this case, since the wafer W is being rotated at a high speed, the entire surface of the back surface 10 of the wafer W may be uniformly polished. In addition, since no heat is generated during the polishing process, so-called bow-warp due to thermal deformation does not occur.

In addition, since a scratch called a so-called sawmark, which is easy to occur when using a conventional mechanical polishing apparatus, is not formed, breakage of the wafer can be prevented and a separate subsequent step for removing the saw mark The polishing process, which is a process, is unnecessary. Therefore, the cost and time required for such a polishing process can be saved, thereby maximizing semiconductor manufacturing yield and productivity.

Meanwhile, referring back to FIG. 3, the water jet used for polishing the back surface of the wafer W is blocked by the cover 120 and prevented from being scattered to the surroundings. 100) It is discharged to the outside.

As described above, in the detailed description of the present invention has been described with respect to preferred embodiments of the present invention, those skilled in the art to which the present invention pertains various modifications without departing from the scope of the present invention Of course it is possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the claims below, but also by the equivalents of the claims.

According to the present invention having the above-described configuration, a uniform polishing of the entire back surface of the wafer is possible, and heat is hardly generated during the polishing process, so-called bow-warp phenomenon due to thermal deformation. There is an advantage that does not occur.

In addition, since a scratch called a so-called sawmark, which is easy to occur when using a conventional mechanical polishing apparatus, is not formed, breakage of the wafer can be prevented and a separate subsequent step for removing the saw mark The polishing process, which is a process, is unnecessary. Therefore, the cost and time required for such a polishing process can be saved, thereby maximizing semiconductor manufacturing yield and productivity.

Claims (5)

A chamber on which wafer backside polishing is performed; A spin chuck installed inside the chamber to hold a wafer and rotate the wafer; A water jet injector installed at an upper portion of the spin chuck and spraying a water jet at a high speed and high pressure on a rear surface of the wafer rotated while being held by the spin chuck for polishing the back of the wafer; And And a high pressure pump for supplying high pressure water to the water jet injector. The method of claim 1, The water jet injector includes a cylindrical spraying unit having a plurality of nozzles, a spindle positioned above the spraying unit to rotate the spraying unit, and a head positioned above the spindle to support the spindle. Wafer back surface grinding | polishing apparatus made into it. The method of claim 2, The plurality of nozzles are installed to have a predetermined interval along the lower edge of the jetting portion, the back surface polishing apparatus, characterized in that the water jet is injected inclined downward so as to have a funnel shape when rotating the injection portion. The method of claim 1, And the water jet injector is installed to be horizontally movable above the spin chuck. The method of claim 1, The cup-shaped cover is installed around the spin chuck to prevent scattering of the water jet used for polishing the back surface of the wafer, and a discharge port for collecting and discharging the used water jet to the outside of the chamber. Wafer back surface polishing apparatus characterized by the above-mentioned.

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