JP2001334457A - Wrap plate and machining device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wrap plate facilitating the cleaning by preventing abrasives and polishing chips stuck to grooves in the wrap plate used for a wrapping device and to provide a machining device using it. SOLUTION: This wrap plate and this machining device using it are characterized in that a protection film for preventing the abrasives from being stuck to the grooves in the wrap plate used for the device for facing up a workpiece and the wrap plate via the abrasives by dispersing free abrasive grains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for simultaneously processing both surfaces of a parallel flat plate such as a semiconductor wafer, a magnetic disk and a glass substrate.

[0002]

2. Description of the Related Art High flatness and high smoothness have been demanded for parallel flat plates such as semiconductor wafers, magnetic disks, and glass substrates. For example, in a semiconductor device and the like, it is required to flatten a surface of a semiconductor wafer (hereinafter, sometimes referred to as a work) made of silicon or the like with high precision in accordance with ultra-miniaturization.

[0003] The manufacturing process of silicon and other compound semiconductor wafers is generally performed by the Czochralski method (CZ method).
Process of slicing a single crystal ingot grown by the method or the floating zone method (FZ method) into a disk shape to form a wafer prototype, lapping process for flattening the wafer, and etching for removing processing strain A wafer processing process in which at least one side (principal surface) is processed into a mirror-finished wafer through a step of a polishing step for mirror finishing, and then a fine electric circuit is formed on the mirror surface of the wafer. It is divided into device manufacturing processes to write. These manufacturing processes are accompanied by various other processes such as a heat treatment process for controlling the characteristics of the wafer, a washing and drying process for improving the cleanliness of the wafer surface, and an inspection process for evaluating the quality.

In the process from the above-mentioned single crystal ingot to the production of a semiconductor device, there is a lapping process as one of processing means for improving the flatness of a wafer. The lapping process is performed by using an abrasive (dispersing a lapping agent, a lapping slurry, or simply a slurry) in which free abrasive grains are dispersed and a platen (a lapping plate, a lapping plate, or simply a plate). (Sometimes referred to as rubbing), usually located in the pre-processing of etching and mirror finishing polishing (dimensions)
It has the role of adjusting the surface roughness.

[0005] In a processing device used in lapping processing, a work is arranged by arranging a work in a correction ring and pressurizing a head, or by pressing or adhering to a disk called a mount plate and pressing on a surface plate. A single-sided lapping machine or a work-holding bracket (generally called a carrier) that holds a work, the carrier is planetary-moved, and the work can be processed between the upper and lower lapping surfaces. There is a lapping machine (see Fig. 3). Currently,
A double-sided lapping machine is generally used to increase the parallelism of a wafer.

The lapping machine uses a liquid (abrasive) containing free abrasive grains, and the liquid containing the abrasive grains utilizes grooves (lap grooves as shown in FIGS. 7 and 8) of a lap plate. Then, it is supplied between the plate and the wafer surface, and the plate, loose abrasive grains and the work are rubbed together to process the work surface.

[0007] After the processing is finished, since polishing dust and abrasives remain on the lap plate, usually at the end of processing (every batch).
And easily cleaned with pure water spray. In addition, the residue stuck to the groove is periodically cleaned with a scraper or a brush.

[0008]

The wrap plate currently used is made of, for example, cast iron. Since the groove is used with the groove processed, rust is easily generated. In addition, the liquid containing abrasive grains may solidify in the back of the groove (the recessed portion) and stick to the surface of the groove.

For this reason, after the machining process is repeatedly performed to some extent, the groove portion is cleaned to remove the solidified abrasive and polishing debris, so that the operation rate of the apparatus is reduced. Also, if the solidified material comes off during processing, the surface of the processed material will be damaged and the quality will be impaired. Further, the size of the lap plate becomes larger year by year, and the plate diameter becomes larger, the handling difficulty increases, and the time spent for cleaning the groove and the like becomes longer, which causes a decrease in productivity. Therefore, it is desired that the groove of the lap plate can be easily cleaned in a short time.

The present invention has been made in view of such a technical background, and an object of the present invention is to provide a plate capable of easily cleaning a groove portion of a lap plate.

[0011]

In order to solve the above-mentioned problems, the surface of the groove portion of the lap plate is modified so that a liquid containing abrasive grains is difficult to adhere and solidify. Provide a plate capable of peeling.

That is, in a lap plate used in an apparatus for rubbing a lap plate with a workpiece (work) via an abrasive in which free abrasive grains are dispersed, a groove is formed in the lap plate. A wrap plate comprising a protective film formed on the surface of the portion to prevent the abrasive from adhering.

Various types of protective films (protective materials) can be considered. The protective film is made of a material which has chemical resistance to abrasives and which is difficult to adhere to abrasives and workpieces such as silicon chips. Are preferred. In that respect, synthetic resins such as fluororesins, for example, fluororesins such as polytetrafluoroethylene, have heat resistance, weather resistance, chemical resistance, release properties, slip properties, non-adhesion, mechanical strength, etc. Are better. Also,
Silicone resins are also excellent in chemical resistance and the like.

It is preferable to change the characteristics (material) of the film to be protected by the platen or the abrasive. For example,
When processing with less water or less processing allowance in the abrasive, or on the lower platen of simultaneous double-sided processing equipment (double-sided lapping machine), select a material that makes the protective film water-repellent and coat it. Is preferably performed. This is because water repellency improves drainage, makes it easier to discharge grinding dust and abrasives outside the machine during processing, and makes it easier to clean afterwards without leaving polishing dust and abrasives in the groove part. It is. Examples of such a protective film include protective materials such as a water-repellent paint, the above-mentioned fluorine-based resin, and silicone-based resin.

On the other hand, it is preferable to select a material such that the protective film becomes hydrophilic and coat the upper surface plate when the processing allowance is large and a large amount of polishing dust is generated, or when the upper surface plate of the simultaneous double-side processing device is used. This is because the hydrophilicity improves the dispersibility of the abrasive and prevents the abrasive from skewing in the surface of the surface plate, and the moisture is maintained in the groove portion so that the polishing debris and the like can be prevented from drying and fixing. . Such protective films include protective materials such as hydrophilic paint and titanium oxide.

As described above, by forming the protective film so that the abrasive and the polishing debris do not adhere to or adhere to the groove of the plate, the cleaning can be performed in a short time.

The method of forming the protective film in the groove portion is not particularly limited, but a protective material may be chemically deposited on the groove portion of the plate, or a resin is applied to the groove portion of the plate and then cured and coated. You may. Alternatively, a method of simply painting or attaching a thin resin film to the groove may be used.

[0018]

An embodiment of the present invention will be described below. Although the lapping device (lapping machine) is not particularly limited, for example, processing was performed by a double-sided simultaneous lapping device 10 as shown in FIG. FIG. 3 is a schematic explanatory view of the wrapping device. FIG. 4 is a schematic explanatory view of the lapping device as viewed from a side (cross section), and FIG. 5 is a schematic top view of the lapping device with the upper lap platen removed. FIG. 6 is a plan view showing a surface plate (lap plate) surface of the lower lap surface plate, and FIG. 7 is a perspective view of an end surface portion of the lower lap surface plate in FIG.

3 to 5, the wrapping device 10
Has a lower lap surface plate 11 and an upper lap surface plate 12 provided to face each other in the up-down direction. The lower lap surface plate 11
The upper lap platen 12 is rotated in opposite directions by a driving means (not shown).

The lower lap surface plate 11 has a sun gear 14 on the upper surface of a central portion thereof, and an annular internal gear 15 is provided adjacent to a peripheral portion thereof.

Reference numeral 16 denotes a disk-shaped workpiece holding bracket.
A gear portion meshing with the sun gear 14 and the internal gear 15 is formed on the outer peripheral surface thereof, and has a gear structure as a whole. A plurality of receiving holes (carrier holes) 17 are formed in the workpiece holding bracket 16. A workpiece W such as a wafer to be wrapped is arranged in the receiving hole 17. Usually, a plurality of the receiving holes (carrier holes) 17 are formed, but one may be formed.

A workpiece holding bracket 16 is provided between the upper and lower lap plates 12, 11, and between a sun gear 14 located at the center of the lower lap plate 11 and an internal gear 15 outside the lower lap plate 11. The gears on the outer side of the workpiece holding bracket 16 are engaged with each other, and the upper lapping board 12 is lowered, and the workpiece holding bracket 16 performs a planetary gear motion between the upper and lower lapping boards 12 and 11 rotating while facing each other. The workpiece W fits into a receiving hole 17 opened in the workpiece holding bracket 16, and the workpiece holding bracket 16 is given a rotation and a revolving motion.

To perform the lapping operation, a polishing agent called a lap slurry, for example, aluminum oxide (Al ₂
A liquid turbid liquid A such as O ₃ ), silicon carbide (SiC), or the like, and a liquid such as water containing a surfactant is vertically wrapped from a nozzle 18 through a through hole 19 provided in the upper lap plate 12. Abrasive grains are fed between the workpieces W and the upper and lower lapping plates 12 and 11 by flowing through the gaps between the boards 12 and 11 to process the workpieces W.

Here, in order to obtain the flatness, it is necessary to faithfully transfer the shapes of the upper and lower lap plates 12 and 11 to the workpiece W, and the upper and lower laps 12 and 11 are relatively moved. The movement of the lap slurry A between the platens 12 and 11 cannot be ignored.

This is because the abrasive grains in the lap slurry A are constantly worn and the grain size and sharpness change. Here, if the movement of the lap slurry A is biased, a portion to be processed with poorly sharpened abrasive grains having a small particle diameter compared to other portions is immediately thickened in a place where the flow of the lap slurry A is poor.

[0026] For this reason, grooves 20 called grids are dug at intervals of 20 mm to 50 mm on the platen surfaces 13 of the upper and lower lap plates 12 and 11 to supply slurry and discharge unnecessary slurry A and chips therefrom. (FIGS. 6 and 7).

The upper and lower stools 12, 11 are made of a hard material such as cast iron. Cast iron is generally used because it has a structure in which ferrite, cementite, and graphite are finely mixed, so that fine irregularities are formed and slurry (abrasive grains) is well retained. Glass or ceramics may be used in favor of metal contamination.

In the present invention, the protective film 1 for preventing the abrasive or the like from adhering to the surfaces of the grooves of the plates 11 and 12 in which the grooves 20 are formed is formed.

Since the portion 13 that comes into contact with the wafer is shaved during processing, the protective film 1 (the portion to be protected) is sufficient only in the recess of the groove. For example, as shown in FIGS. FIG. 1 shows a protective material covering the entire concave portion of the groove. FIG. 2 shows an example in which a protective material is attached only to the bottom of the groove. Although the effect is great if the entire groove is covered, the effect of preventing the adhesion of the abrasive or the like can be obtained only by attaching a water-repellent (in some cases, hydrophilic) protective material only to the bottom of the groove.

[0030]

The lapping method using the lap plate and the processing apparatus of the present invention will be described in more detail with reference to the following examples.

As a workpiece (sample wafer), a p-type manufactured by the CZ method, crystal orientation <100>, diameter 200 mm
Was used. Abrasive is aluminum oxide (Al ₂ O ₃ # 1200), slurry supply: 800 cc
/ Min, lap load: 100 g / cm ² , lap time: 15 minutes. Each batch was processed in 12 sheets.

(Comparative Example 1) Under the above lapping conditions,
The processing was performed using a conventional cast iron lap plate in which the partition grooves 20 of the upper and lower lap plates (lap plates) 12 and 11 of the processing apparatus shown in FIG. 3 were not coated with any resin.

As a result, silicon rinsing remains after each washing with a simple pure water spray (washing for about one minute), and the silicon scum sticks to the groove portion only after about 10 batches. In some cases. In such a state, it is necessary to perform full-scale cleaning using a scraper such as a spatula, a brush, or the like to scrape off the adhered matter in the groove portion. For this reason, it is necessary to stop the apparatus periodically, and the operating time (productivity) of the apparatus has been reduced. In addition, if processing was performed continuously for 10 batches or more without cleaning, the adhered material was peeled off during processing, and the quality was affected, such as scratches on the work surface.

(Embodiment 1) Using the same lapping conditions and processing apparatus as in Comparative Example 1, the protective material 1 was coated on the notches 20 of the upper and lower lap plates (lap plates) 12 and 11 (forming a protective film). Lap plate.
As the lap plate, plates 11 and 12 made of cast iron are used.
As shown in FIG. 1, the inside of the groove was coated with a fluororesin. The thickness for coating is not particularly limited, but about several μm is sufficient.

As a result, by applying such a coating, it was possible to efficiently remove silicon dust and abrasives by washing with a simple pure water spray after processing. In other words, when such a coating is applied, it is possible to easily remove silicon dust and the like only by performing a simple cleaning each time, and even if processing is continuously performed, the silicon dust and the abrasive are hardly fixed. I was able to. Accordingly, full-scale cleaning for forcibly removing the adhered matter using a scraper, a brush, or the like in the groove portion of the lap plate is almost unnecessary, and the working efficiency is remarkably improved.

The present invention is not limited to the above embodiment. The above-described embodiment is merely an example, and any element having substantially the same configuration as the technical idea described in the claims of the present invention and having the same function and effect will be described. It is included in the technical scope of the invention.

For example, the present invention can be applied not only to the double-sided simultaneous lapping apparatus but also to a plate used in an apparatus for lapping only one side. Further, in the above example, the upper and lower platens were implemented using a water-repellent fluororesin, but the material of the protective film in the groove portions of the upper and lower platens was different, for example, the groove portions of the upper platen were protected with a hydrophilic material. May be. For this, a material to which polishing dust and an abrasive are hardly adhered is selected depending on characteristics of a workpiece to be polished and polishing conditions such as an abrasive to be used.

As is apparent from the above description, when processing is performed using the plate of the present invention, the cleaning time is reduced and the operation rate of the apparatus is improved as compared with the conventional product. In addition, the generation of scratches on the processed surface has been suppressed to be lower than that of the conventional product.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a groove configuration of a lap plate according to the present invention.

FIG. 2 is a sectional view showing another example of the groove configuration of the lap plate according to the present invention.

FIG. 3 is a schematic explanatory view of a wrapping device.

FIG. 4 is a schematic explanatory view of the lapping device as viewed from the side (cross section).

FIG. 5 is a schematic top view showing a state where an upper surface plate of the lapping device is removed.

FIG. 6 is a plan view showing an example of a processing surface of a lap surface plate (lap plate) used in the lapping device.

FIG. 7 is a perspective view of an end face of the lap plate shown in FIG. 6;

FIG. 8 is a sectional view showing a groove portion of a conventional lap plate.

[Explanation of symbols]

 1: Protective material (membrane) 10: Lapping device 11: Lapping plate (lower surface plate) 12: Lapping plate (upper surface plate) 13: Lapping plate surface (surface plate surface) 14: Sun gear 15: Internal gear 16: Workpiece holding Metal fittings (carrier) 17: Receiving hole 18: Nozzle 19: Through hole 20: Partition groove A: Slurry W: Workpiece

Claims (4)

[Claims] 1. A lap plate used in an apparatus for rubbing a workpiece and a lap plate through an abrasive in which free abrasive grains are dispersed, wherein a groove is formed in the lap plate, and the groove portion is polished. A wrap plate formed with a protective film for preventing the agent from adhering. 2. The wrap plate according to claim 1, wherein said groove portion is protected by a water-repellent material. 3. The wrap plate according to claim 1, wherein said groove portion is protected by a hydrophilic material. 4. An upper and lower lap surface plate and a disk-shaped workpiece holding bracket rotatably held between the upper and lower lap surface plates and having one or a plurality of receiving holes formed therein. A lapping device for arranging a plate-shaped workpiece in the receiving hole and lapping the workpiece together with the workpiece holding metal with respect to the upper and lower lap platens; A processing apparatus using the lap plate according to claim 1 for a surface plate.