JP2008049443A - Sticking method of semiconductor wafer on polishing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a hand sticking method of a wafer devised to prevent trapping of air and particles since the hand sticking method in which a worker rubs solid wax against a heated polishing plate by hand to form a wax film to stick the wafer on the wax film may generate a recessed part and waviness after polishing due to entrapment of air and particles. <P>SOLUTION: The back surface side of the wafer 6 is stuck to the polishing plate 2 previously coated with the solid wax by atomizing liquid wax 9 by an atomizer 8 and thinly spraying it on a back surface of the wafer 6. The solid wax 4 and the liquid wax 9 are laminated between the polishing plate 2 and the wafer 6. The liquid wax 9 can prevent trapping of air and foreign matter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement in a method of attaching one surface of a GaAs wafer to a polishing plate with wax in a step of mirror polishing. In order to clarify the mounting direction of the wafer surface, the wafer surface to be polished is hereinafter referred to as “front surface”, and the surface attached to the polishing plate is referred to as “back surface”. There are roughly two methods for attaching a wafer to a polishing plate.

  One is a method in which a polishing plate is heated, a solid wax is held in hand and rubbed against a wide polishing plate to form a wax film, and the wafer back surface is pressed onto the wax film of the polishing plate to fix the wafer. This is called a manual pasting method.

  The manual pasting method will be described with reference to FIGS. In FIG. 1 (1), the operator holds the solid wax 3 by hand and rubs it against the surface of the polishing plate 2. A rod-shaped solid wax 3 is rotated in the circumferential direction several times to apply the wax and a thin wax film 4 is applied. As shown in FIGS. 1 (2) and 1 (3), the operator holds the spatula-shaped jig 5 in his / her hand and gently rubs the wax surface to form a wax film 4 having a uniform thickness.

  An operator attaches the back surface of the wafer to the wax film 4. In many cases, a plurality of sheets are attached at symmetrical positions on the circumference. As shown in FIG. 1 (5), the wafer surface is pressed with cotton cloth, paper, etc., and the wafer 6 is attached to the polishing plate. Remove excess wax adhering to other parts of the polishing plate. As shown in FIG. In this state, the polishing plate is mounted on a polishing apparatus for polishing.

  The manual pasting method is the most economical because there is no waste of wax and no time is spent because the solid wax is spread on the polishing plate with a coating jig by the required amount. If there are skilled workers, this is a suitable method for producing a low-cost GaAs wafer. However, since the worker manually applies the solid wax and thins it with a jig, the wax film thickness becomes non-uniform depending on the skill of the operator. The biggest problem is that air remains at the wafer wax boundary when the wafer is pressed.

  FIG. 2 shows a view from the back of the polishing plate when the wafer is attached to the transparent glass polishing plate 2 by a manual bonding method. Since it is transparent, the wax application state and the wafer 6 can be seen from the back side. When the bubble 7 is bitten, it looks whitish from the back side. FIG. 4 is a cross-sectional view showing a state where the bubbles 7 are sandwiched between the wax film 4 and the wafer 6. The wafer is lifted due to bubbles. Even in the presence of particles, the wafer is lifted in this way. If such a thing is grind | polished and removed from a grinding | polishing plate, the part in which the bubble existed will be shaved excessively and will become the recessed part D. FIG. FIG. 3 shows a plan view of a wafer in which bubbles 7 are bitten, and FIG. 10 shows a plan view in which a concave portion on the wafer surface when the wafer is polished on one side is measured with a laser interference type flatness measuring device. 11 is a perspective view thereof. FIG. 5 shows a longitudinal sectional view of the recess D. As shown in FIG. Due to the presence of the bubbles, it is excessively polished to form the recesses D.

  When bubbles are included (referred to as air entrapment), even if the wafer is pressed, the bubbles do not move and cannot be pushed out. If there is air entrainment or particle entrainment, the surface of that portion will be excessively shaved to form a recess. Air entrapment, particle entrapment, etc. are the biggest disadvantages of the manual pasting method.

  The other is to drop liquid wax onto a wafer fixed to a spinner, rotate the spinner to spread the wax by centrifugal force, create a film, and apply it to the polishing plate. This is called a spin coat method. This spreads the liquid wax by a spinner, so that the film thickness uniformity is further improved. However, a lot of wax is wasted, and a spinner facility is required, which increases the processing time for each sheet and increases the cost.

  The target is a GaAs wafer, but the GaAs wafer is used as a substrate of a light emitting device (LED), a substrate of a high-speed logic device, or the like. GaAs wafers as LED substrates are strongly required to be low cost. This is unavoidable because GaAs-LEDs are inexpensive. It is necessary to reduce the substrate cost, and for this reason, GaAs wafers tend to have a large area and become thin. The diameter of the wafer has been increased from 2 inches to 3 inches and further to 4 inches. By mirror-finishing the front and back surfaces by double-sided polishing, the problem of concavities due to bonding is eliminated, but the cost increases. In addition, in epitaxial growth in which the device operating layer is grown on a GaAs wafer, the roughness of the back surface is a heater. In many cases, the back surface of a GaAs wafer for LED applications remains rough.

  Currently, the wafer thickness is often 450 μm. In order to further reduce the cost, a product having a thickness of 350 μm has been prototyped and mass production is being started. Trials with a thickness of 300 μm are beginning to be manufactured. In this way, inexpensive GaAs wafers for LEDs are becoming larger and thinner. Since it is wide and thin, air biting and particles at the time of pasting are more easily reflected on the mirror surface after polishing, and single-side polishing becomes more difficult.

  The wafer is affixed to the polishing plate with wax and polished by a polishing device. If foreign matter is sandwiched between the wax and the plate or if bubbles are included, the surface of that part will be scraped off more than other parts, so polishing When it is removed from the plate, a recess is formed. A dot-like recess is called a “dent”. In the case of a continuous curved recess, it may be referred to as “swell”. The depression is sometimes called “dimple”.

  If dents and undulations occur on a single-side polished wafer, an accurate pattern cannot be drawn on the wafer by photolithography. The device made in that part becomes defective. Defects in swells and dents are increasing rapidly as the wafer diameter increases and the layer thickness decreases. For example, when a GaAs wafer with the same diameter is affixed to a polishing plate by the same technique and polished, the wafer with a thickness of 350 μm is three times as defective as the wafer with a thickness of 350 μm, and the wafer with a thickness of 300 μm. Then, the defect rate increases rapidly as the thickness is reduced, such as 15 times the defect rate. This means that a method suitable for a thick wafer cannot be applied to a thin wafer as it is.

  Cost competition cannot be won without increasing the diameter and thinning of the wafer. Therefore, it is necessary to develop a sticking or single-side polishing method that does not generate waviness depressions even with a large-diameter thin layer wafer.

  In Patent Document 1, when a photoresist or liquid wax is spin-coated on a Si wafer, the photoresist or wax is not uniform because there are steps, particles, or crystal defects on the wafer, and a dead spot is generated in the film. Make a problem.

  If there is a dead spot in the resist, the portion is not exposed, so that the pattern formed by photolithography is disturbed and becomes a defective product. If there is a dead spot in the wax, bubbles are generated and a step is formed on the surface after polishing. In order to prevent such a situation, Patent Document 1 discloses that when a solvent is applied and a spinner is rotated to form a solvent film, a resist or liquid wax is dropped on the wafer and the spinner is rotated to form a resist or a wax film. It ’s good.

  Patent Document 2 says that there are two methods for attaching a semiconductor wafer to a polishing jig with wax, but each has its drawbacks. Solid wax is heated and softened and rubbed against a polishing jig, and the wax is stretched uniformly with a jig such as a spatula, the wafer is placed on top of it and pressed to remove the wax on the part without the wafer. is there. This method works well for skilled workers. However, since the process is performed manually, the thickness of the solid wax is not uniform.

  There is also a method in which liquid wax is dropped onto a semiconductor wafer placed on a spinner, and the wafer is rotated at a high speed to form a wax film and affixed to a polishing jig. This is called a spin coating method. This has the advantage that the liquid wax is spread by centrifugal force, so that the thickness of the wax can be easily adjusted.

  However, since the liquid wax is spread with a spinner, most of the wax is scattered. Only a portion remains on the wafer. He states that less than 30% of the dropped liquid wax remains on the wafer. It points out that more than 70% is thrown away and wasteful. Patent Document 2 proposes a method in which liquid wax is sprayed on a polishing jig instead of a wafer by spraying, and the wafer is placed on the sprayed portion and pressed. Since the liquid wax is sprayed on the polishing jig instead of the heated solid wax, the uneven thickness is reduced. He states that the cost can be reduced compared to the spin coating method because wax is not wasted.

  Patent Document 3 has a problem that when a wafer is affixed to a carrier plate that fixes a single wafer with a wax and is polished, the outer peripheral portion is excessively polished due to the depression of the polishing cloth, resulting in a run-off. Therefore, the central portion of the carrier plate for one wafer is flat, and the peripheral portion is a region where many pins are formed. When wax is attached to the back surface of the wafer and attached to the carrier plate, the peripheral portion of the wafer bends upward because the wax enters between the pins on the outer peripheral portion. For that reason, it says that nobody is reduced.

  Patent Document 4 determines that the reason why the photoresist and wax cannot be uniformly applied to the wafer is that moisture and particles remain on the wafer. If residual moisture and residual particles are removed, liquid wax can be applied uniformly. Therefore, it has been proposed to clean the wafer in ethanol in advance to remove all moisture and particles. Dry and evaporate the ethanol. After that, when liquid wax is dropped and spin-coated, a uniform wax film is formed.

  According to Patent Document 5, when a liquid wax is spin-coated on a wafer, a wax layer having a uniform thickness is formed and attached to a polishing jig. When the polishing jig is pressed against a polishing surface plate and the wafer is polished, the polishing cloth bends. Therefore, the problem is that the circumferential portion of the wafer is excessively shaved and surface sag occurs. The part of the face is wasted because it cannot be used as a device. He says that he wants to reduce the surface droop as much as possible, so the wafer wax thickness is not made uniform, but is thicker at the center and thinner at the periphery. Since the wafer is thin because the wax is thin at the periphery, the wafer will bend upward and escape, so that the peripheral part will not be scraped off and the surface will be reduced.

JP-A-5-259052 JP 2004-165360 A JP2005-033139 JP-A-6-275503 Japanese Patent No. 3410719 (Japanese Patent Laid-Open No. 2002-110601)

  The inventor of the present invention has devised an improvement in which the wafer after polishing does not generate a waviness dent in the hand-pasting method in which a solid wax is rubbed against a heated polishing plate and the wafer is placed on the polishing plate and pressed with paper or cotton. In other words, it is not an improvement of the spin coating method. Spin coating wastes wax, takes time, and increases costs. If lower-cost wafers are required, we would like to solve them by hand-paste if possible.

  Patent Documents 1, 3, 4, and 5 listed above are proposals for the spin coating method and do not fall within the category of the present invention. Patent Document 2 sprays liquid wax onto the polishing plate by spraying, and is common with the present inventor in that wax is applied to the polishing plate. However, even if liquid wax is sprayed onto the polishing plate by spraying and a wafer is placed thereon, bubbles and particles may be bitten in the same manner as in the conventional method. In other words, none of the above-mentioned conventional examples is helpful.

  An operator who heats and applies the polishing plate holds the solid wax in his hand and rubs the solid wax against the polishing plate. Workers tried to speed up or slow down, or changed the angle of application, but it was not possible to eliminate air entrainment.

  We increased the number of times the solid wax was rubbed and increased the thickness of the wax film formed on the plate. Still, bubbles cannot be prevented. In addition, if the wax is thickened, the wafer flatness TTV (Total Thickness Variation) deteriorates.

  The heating temperature of the polishing plate is about 80 ° C. higher than the softening point of the solid wax. Although an experiment was conducted in which the heating temperature was raised or lowered from 80 ° C. to rub the solid wax and the wafer was attached and polished, it seemed that there was little effect on eliminating air entrapment. After the wax is rubbed, the wax is extended by rubbing with a jig such as a spatula. However, even if this process is increased or decreased, air entrapment does not decrease.

  Place the GaAs wafer on the wax extended with the jig and tap it with cotton or paper. I experimented by increasing the number of times I hit, but the air was still stuck. Bubbles once inside the wax do not seem to disappear no matter how much they are struck with cotton or paper from the top of the wafer. Therefore, polishing was performed after strongly pressing the wafer with a roller, but air entrainment was not reduced. It was found that once air (bubbles) entered, it was not pushed out even if the wafer was struck or rubbed.

  I also tried to hold the wafer attached with rubber balls. However, the air could not be eliminated. In other words, it was concluded that once the air was caught in the wax between the wafer and the polishing plate, the bubbles could not be extinguished in any way.

  The inventor made various attempts. It is difficult to prevent dimples (dents) from being generated by air entrapment and particle entrapment. Therefore, we tried putting the liquid in the beaker, sandwiching the GaAs wafer with tweezers, putting it in the beaker, dipping it into the liquid, taking it out, placing it on a polishing plate coated with solid wax and pressing it. FIG. 6 shows an outline of the beaker dipping method. The liquid 23 is put in the beaker 22. The GaAs wafer 6 is immersed in the liquid 23. The polishing plate 2 is heated and coated with solid wax manually. The immersed wafer 6 is taken out and placed wet on the liquid 23 on the solid wax 4 of the polishing plate 2.

  When the liquid 23 put in the beaker 22 is pure water, the liquid 23 adheres to the surface of the polishing plate 2 temporarily if there is no gap. Bubbles do not enter because the liquid 23 fills the space. Even if it enters, it will come off because the liquid 23 flows. However, after placing the wafer 6 on the polishing plate 2, there is a drawback that water does not evaporate and remains for a long time. Water impairs the adhesion of the wax 4 and the wafer 6 is easily peeled off from the polishing plate 2. Therefore, the wafer is detached during the polishing.

  When the liquid 23 is alcohol, the entire wafer 6 gets wet with the alcohol, so that the wafer 23 adheres to the polishing plate 2 without any gaps and bubbles do not enter. However, the alcohol has a function of partially dissolving the solid wax 4 previously applied to the polishing plate, so that the wafer 6 is peeled off from the polishing plate 4.

  When the liquid 23 put in the beaker 22 is a liquid wax, the operation is as follows. Since the polishing plate 2 has a solid wax 4 and the wafer 6 has a liquid wax, the wafer is bonded to the polishing plate and there is no entrapment of bubbles. Toluene and isopropyl alcohol contained in the liquid wax quickly evaporate as soon as they are attached to the polishing plate. The wafer does not come off the polishing plate. The combination of the solid wax and the liquid wax had no problem in terms of adhesion and bubble entrapment as described above, but it was found that there was another problem.

  That is, the total thickness of the wax becomes too large. Since there is a double wax layer of the solid wax 4 applied to the polishing plate 2 and the liquid wax attached to the wafer, the overall wax thickness becomes 15 μm to 25 μm.

  The wax thickness in the case of the conventional hand pasting was 1 to 5 μm. Compared to this, the thickness is increased by 10 μm to 20 μm. When the wax is thick, the non-uniformity of the wax thickness is large. Therefore, there is a drawback that TTV after polishing is deteriorated. TTV has a flat surface on the back side of the wafer, and evenly and vertically spaced points (for example, 0.1 mm or 0.01 mm) are measured on the front surface. Is subtracted. TTV is an index of flatness. A large TTV means poor flatness. If the wax is too thick, the non-uniformity is large and there is a disadvantage that the TTV of the polished wafer becomes large.

  The polishing plate was heated as before, solid wax was spread with a coating jig, and a method of manually attaching a wafer attached to the liquid to the polishing plate was tried. In the case of pure water or alcohol, there is a drawback that the wafer is detached. This is because it is unfamiliar with solid wax.

  It seems promising to attach a wafer soaked in liquid wax with the same wax to a polishing plate coated with solid wax. It is an advantage that the wafer does not come off and air bubbles (air) can be prevented from being caught. However, it has the disadvantage that the total wax thickness is too large.

  Liquid wax has a very high viscosity, and if a wafer is immersed in a liquid wax placed in a beaker, the wax is excessively attached. This increases the total wax thickness. It is necessary to prevent the entrapment of air entrained particles and reduce the total wax thickness.

  The present inventor also tried to apply liquid wax to the back surface of the wafer by a spin coating method and attach it to a polishing plate on which a wax film was formed. However, the air biting did not disappear. Since the wax film on the back surface of the wafer formed by spin coating is completely dried by high-speed rotation of 2000 to 5000 rpm, the solvent in the liquid wax is dried during coating. Therefore, it is presumed that the surfaces having high viscosity are bonded to each other, and air and foreign matters cannot flow and stick to each other, and the air bite is not lost. It turns out that wetness is the most important factor.

In the present invention, the liquid wax is thinly sprayed on the back surface of the wafer, and is attached to the back surface of the polishing plate previously coated with the solid wax. The method of the present invention will be described with reference to FIG. The liquid wax 9 is accommodated in the spray device 8. The back surface of the wafer 6 is directed to the atomizing device 8, and the liquid wax is atomized by the atomizing device 8 and sprayed onto the wafer 6. The back surface of the wafer is slightly wetted with mist of wax. It is affixed from the back surface to the polishing plate 2 in which the solid wax 4 is uniformly extended in advance with a coating jig. Bubbles do not remain between the waxes due to the action of fog.

  The spray device 8 may be a simple household one. A dedicated sprayer with a compressor may also be used. Although it depends on the size of the wafer, the distance between the wafer and the spray is about 10 cm to 100 cm. The back surface of the wafer is adjusted so that it is slightly moistened by the mist of the liquid wax 9 to be moistened. The film thickness of the liquid wax 9 that can be instantaneously formed is about 1 μm to 3 μm. I will call it mist pasting.

  Since the liquid wax is sprayed on the wafer surface, the liquid wax layer is sufficiently thin. When it is affixed to a polishing plate coated with solid wax, the liquid wax having fluidity spreads well and covers the concave protrusions of the solid wax. FIG. 8 is a sectional view showing a state in which a wafer coated with liquid wax is attached to a polishing plate. There is a film of solid wax 4 on the polishing plate 2 and a film of liquid wax 9 thereon. There is a wafer 6 thereon. The liquid wax 9 has a low viscosity and spreads so as to fill the concave portion. A flat surface is formed. In this state, the back surface of the wafer is attached to the polishing plate, so that almost no air or particles are caught. Therefore, no dimples or undulations occur on the wafer surface after polishing.

  Since the liquid wax 9 is obtained by thinning a solid wax with a solvent, the liquid wax 9 is originally compatible with the solid wax 4. The wafer 6 does not peel off from the polishing plate 2 because of the close contact. Since the mist (mist) is attached to the wafer, the thickness of the liquid wax layer 9 is as thin as about 1 μm to 3 μm. Even if the solid wax 4 layer has a thickness of 1 μm to 5 μm, and the thickness increases by about 1 μm to 3 μm by attaching mist, the total thickness is about 2 μm to 8 μm. As the solvent evaporates, the thickness is somewhat reduced. Ultimately, it becomes about 2 μm to 7 μm. Since no bubbles or particles remain, the flatness TTV of the polished wafer is good.

  FIG. 9 shows a cross-sectional view of the wafer after polishing. Dimple D is not generated. The wax thickness is suppressed to about 2 to 7 μm. The wax thickness is not too much to increase the TTV. Therefore, the flatness of the polished wafer is not impaired. FIG. 12 shows a plan view of the polished wafer surface measured by a laser interference type flatness measuring apparatus, and FIG. 13 shows a perspective view thereof. Compared to FIGS. 10 (plan view) and FIG. 11 (perspective view), which are measurement views of a wafer polished after manual pasting, dimples D are not generated, and a marked improvement in flatness can be clearly seen.

  In the present invention, liquid wax is sprayed on the back surface of the wafer, and is adhered to the back surface of the polishing plate that has been previously coated with solid wax. Since the spreading property of the fluid liquid wax is good, air entrapment can be effectively prevented. Since there is no air bite, no dimples or undulations occur after wafer polishing.

Since it is a combination of liquid wax and solid wax, compatibility is good and the wafer does not come off the polishing plate during polishing. Since no depressions or undulations occur, a pattern can be accurately drawn on the wafer by photolithography. The defect rate can be reduced and the yield of device fabrication can be increased. Instead of using a large amount of liquid wax, make it a mist and spray only a small amount. The overall thickness of the wax does not increase too much. The wax thickness of the conventional manual pasting method is about 1 μm to 5 μm, but the final thickness is about 2 μm to 7 μm even when the mist is pasted. In the conventional manual pasting method, even if the wax thickness is thin, air and foreign matter are involved, and the variation in flatness is large. However, in the mist pasting, the variation is eliminated, and even if the wax thickness is 1 to 2 μm thick. The flatness obtained better than that of the manual pasting method.
The only new requirement is a sprayer, which is an inexpensive device. It is much cheaper and easier to handle than spinner devices. Does not take up space and application time is short.

[Example 1]
130 sheets of 3 inch (76 mmφ) GaAs wafers (N = 130) having a thickness of 350 μm were attached to a polishing plate by the method of the present invention and polished on one side. Pasting was carried out by inexperienced workers because there was a large difference in skill. Four sheets were attached to one polishing plate. After peeling, the wax thickness was measured, and the wax thickness was 2 to 7 μm. The number of wafers in which dimples were generated by polishing was zero. This is a wonderful result. This means that air entrapment could be prevented by attaching mist.

[Comparative Example 1]
263 sheets of 3 inch (76 mmφ) GaAs wafers (N = 263) having a thickness of 350 μm were bonded to a polishing plate by a conventional manual bonding method and polished on one side. It is the same worker as the embodiment. Four sheets were attached to one polishing plate. After peeling, the wax thickness was measured, but the wax thickness was 1 μm to 6 μm. The number of wafers in which dimples were generated by polishing was 27. The ratio of the occurrence of dents is 10.2%. Air entrainment occurs with a considerable probability.

  Comparing the present invention with a comparative example, the mist bonding method of the present invention has an excellent advantage that it can almost completely prevent the formation of a dent after polishing and can also eliminate variations in flatness TTV.

Explanatory drawing which shows the process of apply | coating solid wax to a grinding | polishing plate and sticking a wafer. (1) shows a state in which a solid wax is applied in hand while rotating the polishing plate. (2) shows a state where the wax is thinly extended with a jig. (3) is a state after the wax is uniformly extended with a jig. (4) shows a state in which a plurality of wafers are placed on a solid wax film. (5) shows a state where the wafer is hit with a cotton cloth or the like. (6) shows a state in which the excess wax film is removed.

The bottom view of the grinding | polishing plate of the state which apply | coated solid wax to the transparent grinding | polishing plate and affixed the wafer. It can be seen that when bubbles enter between the wafer and the polishing plate, there is a portion that appears white when viewed from the back, and bubbles are present.

The top view for demonstrating that the bubble is biting when the wafer before grinding | polishing is seen from the surface.

Sectional drawing which shows that a wafer is lifted up, when air is stuck between a wax and a wafer, when a wafer is affixed on a polishing plate using solid wax.

FIG. 6 is a longitudinal sectional view for explaining that a recess D is generated because the wafer is lifted by air and the surface of the wafer is excessively scraped when air is caught.

The perspective view for demonstrating a mode that a wafer is immersed in the liquid put into the beaker, it lifts with a liquid attached, and it affixes on the grinding | polishing plate which applied solid wax.

The perspective view which shows the method of this invention which sprays liquid wax on a wafer using a sprayer, forms the film | membrane of thin liquid wax, and affixes it on the grinding | polishing plate which apply | coated solid wax beforehand.

The longitudinal cross-sectional view of the laminated body of a polishing plate / solid wax / liquid wax / wafer just after a wafer was affixed on the polishing plate by the method of the present invention. The back surface of the wafer is wet, and bubbles and particles can be eliminated. Air bubbles do not remain between the wax and the wafer.

Sectional drawing of the wafer after grinding | polishing which shows that a flat wafer without a recessed part (dimple) will be obtained if it removes from the grinding | polishing plate after grind | polishing the wafer hand-pasted by the method of this invention.

When polishing a wafer attached to a polishing plate by a conventional manual attachment method, the bubble portion is excessively scraped and a dimple is generated, so that the flatness is significantly impaired. Plan view.

When polishing a wafer attached to a polishing plate by a conventional manual attachment method, the bubble portion is excessively scraped and a dimple is generated, so that the flatness is significantly impaired. Perspective view.

The top view of a wafer which shows that it becomes a flat wafer without a dimple (dimple) when the wafer affixed on the grinding | polishing plate by grinding | polishing method of this invention is grind | polished.

1 is a perspective view of a wafer showing that when a wafer attached to a polishing plate is polished by the mist attaching method of the present invention, a flat wafer having no dimples is obtained.

Explanation of symbols

2 polishing plate
3 solid wax
4 solid wax membrane
5 jigs
6 wafers
7 bubbles
8 nebulizer
9 liquid wax
20 cotton cloth
22 beakers
23 liquids
D dimple

Claims (2)

A method for adhering a semiconductor wafer to a polishing plate, characterized by spraying liquid wax in the form of a mist with a sprayer and spraying it onto the back surface of the wafer and pressing the back surface of the wafer against a polishing plate previously coated with solid wax. 2. The method for adhering a semiconductor wafer to a polishing plate according to claim 1, wherein the total thickness of the solid wax and the liquid wax applied to the polishing plate is 2 to 8 [mu] m.

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