JP3498288B2 - Semiconductor wafer polishing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polishing a semiconductor wafer, and more particularly to a method for polishing a semiconductor wafer in which a polished wafer is subjected to hydrophilic treatment.

[0002]

2. Description of the Related Art Generally, a silicon wafer cut out from a silicon single crystal ingot is subjected to a lapping process and an etching process, and then a mirror polishing process using an abrasive for flattening the wafer surface. The cleanliness of the surface of the silicon wafer directly affects the semiconductor device characteristics, and if the cleanliness decreases, it may cause a defect in forming a device pattern and adversely affect the electrical characteristics of the semiconductor device. The decrease in cleanliness of the wafer substrate surface is caused by foreign matter such as particles (fine particles) attached to the wafer substrate surface in each step of wafer processing. Therefore, after the mirror-polishing step, a final cleaning process is performed to remove foreign matter such as particles remaining on the wafer surface.

In a conventional single-wafer-type wafer polishing apparatus in which a plurality of silicon wafers are polished one by one and conveyed to a final cleaning process, the wafer is subjected to a final polishing in a mirror polishing process using a polishing slurry. After that, in order to remove the slurry remaining on the polished surface of the wafer and prevent contaminants from being brought in during the cleaning process, the cleaning water is supplied to the polished surface of the wafer with low pressure or no pressure instead of the slurry. A rinsing (water polishing) treatment was performed. Then, after this water rinsing (water polishing) treatment, in order to keep the wafer in a wet state and prevent particles from adhering to the wafer surface, the wafer was conveyed underwater to a cleaning device for performing a final cleaning treatment.

[0004]

According to the conventional wafer polishing method in which such a water rinsing process (water polishing process) and an underwater transfer to the cleaning apparatus are performed, particles can be reduced to some extent, but high quality wafers can be obtained. Insufficient to purify. That is, when the wafer after mirror polishing is subjected to the water rinsing treatment, the wafer polishing surface, which is a hydrophobic surface, is exposed to the cleaning water, the polishing cloth, or the air used in the water rinsing treatment. Here, since the polishing surface of the wafer is made into a very active surface (hydrophobic surface) by the mirror polishing processing, such a polishing surface of the wafer is washed with water, polishing cloth, or air during the water rinsing process. On the contrary, when exposed to, the particles tend to adhere to each other. The particles attached during the water rinsing process are extremely strong and are difficult to remove even by the final cleaning process.

The present invention has been made in view of the above problems, and a semiconductor wafer polishing method and apparatus capable of further reducing particles by making the polished surface of the wafer after mirror polishing hydrophilic. The main purpose is to provide.

[0006]

In order to achieve the above object, the invention according to claim 1 provides a step of performing mirror-polishing of the surface of a semiconductor wafer using a polishing liquid containing an abrasive, and a step of performing mirror-polishing after the mirror-polishing. In a semiconductor wafer polishing method, which comprises transporting a semiconductor wafer in water to a single-wafer cleaning device using transport water , the semiconductor wafer is polished during the mirror polishing.
Do not press the rotating surface plate with the head with a predetermined pressure.
After the finishing polishing process performed from
The semiconductor wafer held on the
The platen with a pressure lower than the constant pressure or no pressure
Characterized by comprising a hydrophilic treatment step of applying a hydrophilic treatment without water rinsing process above.

According to the first aspect of the present invention, since the wafer-polished surface after mirror-polishing can be made hydrophilic by the hydrophilic treatment step, adhesion of particles can be reduced.

The hydrophilic treatment step in the present invention may be carried out so long as the polished surface of the wafer can be made hydrophilic, and the conventional water rinsing treatment (water polishing treatment) can be omitted and immediately after the mirror polishing step is completed. It is possible to finish the surface to be hydrophilic by forming an organic film on the polished surface of the wafer or forming an oxide film. The following inventions may be mentioned as specific embodiments of such a hydrophilic treatment step. The “water rinsing process” in the present invention means that after polishing the mirror surface, a low pressure is applied to the wafer polishing surface in order to remove the slurry remaining on the polishing surface of the wafer and prevent the carry-in of contaminants in the cleaning process. Alternatively, it refers to a treatment (water polishing treatment) of supplying cleaning water instead of slurry without applying pressure.

[0009] The invention according to claim 2, provided in the semiconductor wafer polishing method according to claim 1, wherein the hydrophilizing treatment step, the polishing liquid to the polishing surface of the wafer by the surface plate
Characterized in that it is intended to feed.

The term "water rinsing treatment" as used in claim 2 refers to a wafer polishing surface in order to prevent the introduction of contaminants in the cleaning treatment by removing the slurry remaining on the polishing surface of the wafer after mirror polishing. Treatment of supplying cleaning water instead of slurry under low or no pressure (water polishing treatment)
Say.

In the hydrophilic treatment step according to the second aspect of the present invention, after the mirror-polishing step is completed, the wafer after mirror-polishing is not subjected to water rinsing treatment (water-polishing treatment).
The polishing surface of the wafer is not exposed to cleaning water, polishing cloth, or the air. Further, since the polishing liquid is brought into contact with the polishing surface of the wafer even after the mirror polishing is completed, the organic coating is formed on the polishing surface by the surfactant contained in the polishing liquid. Therefore, by omitting the water rinsing process and forming an organic film on the polishing surface, it is possible to finish the polishing surface of the wafer to be a hydrophilic surface (that is, to prevent it from becoming a hydrophobic surface) and further prevent particles from adhering. .

[0012] The invention according to claim 3 is the semiconductor wafer polishing method according to claim 1, wherein the hydrophilizing treatment step, the ozone water or hydrogen peroxide or a surface on the polished surface of the wafer on a platen It is characterized by supplying water containing an activator.

Also in the third aspect of the invention, since the wafer after mirror polishing is not subjected to the water rinsing treatment (water polishing treatment) in the hydrophilic treatment step after the mirror polishing step is finished, the polished surface is washed with water or polished. Not exposed to cross or air. Further, since the ozone water or the hydrogen peroxide solution is brought into contact with the polished surface of the wafer in the hydrophilic treatment step, an oxide film is formed on the polished surface. Therefore, by omitting the water rinsing process and forming an oxide film on the polishing surface, the polishing surface of the wafer can be finished to be a hydrophilic surface (avoiding a hydrophobic surface) and particles can be further prevented from adhering. .

Further, an organic coating is formed on the polishing surface by bringing water containing a surfactant into contact with the polishing surface of the wafer in the hydrophilic treatment step. By omitting the water rinsing treatment and forming such an organic coating, It is possible to further prevent the particles from adhering by finishing the polished surface of the wafer to be a hydrophilic surface.

[0015]

[0016]

In the present invention, in order to further reduce the particles, after the mirror-polishing step, the water rinsing process is not performed and the transfer step is performed .

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] A wafer polishing apparatus according to the first embodiment has a configuration capable of continuously performing from a mirror polishing step to a wafer transfer to a final cleaning step. Shown in 1. As shown in FIG. 1, the polishing unit 1
And an underwater transfer path 3 for transferring the wafer mirror-polished by the polishing section to the single-wafer cleaning device 5.

The polishing unit 1 is provided with a rough polishing device 12 and a finish polishing device 13 each having a predetermined polishing cloth attached thereto and formed of a rotary platen.

The underwater transport path 3 transports the wafer substrate W after the final polishing to the cleaning device, and has, for example, a roller conveyor as a transport mechanism. The underwater carrier path 3 is filled with carrier water which is pure water.

The cleaning device 5 is a device for performing a final cleaning process on the wafer W after polishing, and includes a spin cleaning device 32 and a scrub cleaning device 31.

Further, the rough polishing device 12 and the finish polishing device 1
In 3, the polishing slurry according to each process is supplied onto the rotating platen. In the finish polishing device 13, the wafer W is held by the polishing head so that the surface of the wafer abuts the polishing cloth. Then, the polishing slurry containing a predetermined surfactant is supplied from the slurry supply nozzle 14 onto the polishing cloth on the surface plate. The slurry supply nozzle 14 constitutes the polishing liquid supply means of the present invention.

In the final polishing step of mirror polishing, while supplying the polishing slurry onto the polishing cloth from the slurry supplying means,
The polishing head presses the wafer W against the surface plate (polishing cloth) with a predetermined pressure, and the surface plate and the wafer W are rotated to perform the final polishing process.

The water rinsing process (water polishing process) for removing the slurry, which is usually performed, is not performed on the wafer W after the finish polishing process. Instead, with the polishing head holding the wafer W, the pressing force from the polishing head is set to low pressure or no pressure (0 pressure), and again (or continuously from the finish polishing step) the slurry supply nozzle. 1
From step 4, the hydrophilic treatment step of supplying the polishing slurry to the polishing surface of the wafer for a predetermined time is executed. By the action of the surfactant contained in the polishing slurry in the hydrophilic treatment step,
An organic film is formed on the polished surface of the wafer.

When the hydrophilic treatment step is completed, the wafer W is transferred to the cleaning device 5 by the underwater transfer path 3. In the underwater transport path 3, at least the polishing surface of the wafer is unloaded while it is in contact with pure water. In the apparatus according to the present embodiment, the underwater transport path 3 is configured to carry out tray transport by a single-wafer type, and the polishing surface side of the wafer is immersed in the transport water in the tray.

As described above, in the polishing method by the wafer polishing apparatus of this embodiment, the water rinsing process (water polishing process) is omitted and the organic film is formed on the polishing surface of the wafer W. The surface can be made hydrophilic and the final cleaning process can be performed. As a result, it is possible to further prevent particles from adhering to the wafer.

[Second Embodiment] Next, a wafer polishing apparatus according to a second embodiment will be described. The wafer polishing apparatus of the second embodiment also has a configuration capable of continuously carrying the wafer from the mirror polishing step to the final cleaning step, and its schematic configuration is shown in FIG. As shown in FIG. 2, the polishing unit 1
And an underwater transfer path 3 for transferring the wafer mirror-polished by the polishing section to the single-wafer cleaning device 5.

The wafer polishing apparatus of this embodiment differs from that of the first embodiment in that the finish polishing apparatus 13 is further provided with an ozone water supply nozzle 15. Since other configurations are the same as those in the first embodiment, the same reference numerals as those in FIG.

The ozone water supply nozzle 15 supplies ozone water onto the polishing cloth after the finishing polishing step, and constitutes the hydrophilic treatment means of the present invention. When the same finishing polishing process as in the first embodiment is completed, the water rinse process is not performed in this embodiment either. Instead, with the wafer W held on the polishing head, the pressing force from the polishing head is set to low pressure or no pressure (zero pressure), and ozone water is supplied from the ozone water supply nozzle 15 to the polishing surface of the wafer. The hydrophilic treatment step of supplying for a predetermined time is executed. By supplying ozone water in the hydrophilic treatment step, an oxide film is formed on the polished surface of the wafer. The ozone water supply nozzle 15 constitutes the hydrophilic treatment means of the present invention.

After the completion of the hydrophilic treatment step, the wafer W is transferred to the cleaning device 5 through the underwater transfer path 3 as in the first embodiment. As described above, in the polishing method using the wafer polishing apparatus according to the present embodiment, the water rinsing process (water polishing process) is omitted, and the oxide film is formed on the polishing surface of the wafer W. It is possible to finish on the water surface and shift to the final cleaning process, and as a result, it is possible to further prevent particles from adhering to the wafer.

In the wafer polishing apparatus of this embodiment, the ozone water supply nozzle 15 is provided, and ozone water is supplied from the nozzle to the polishing surface of the wafer to form an oxide film on the polishing surface. Instead of water, hydrogen peroxide solution may be supplied to the wafer polishing surface to form an oxide film. In this case, the ozone water supply nozzle 1
Instead of 5, a hydrogen peroxide solution supply nozzle may be provided.

Further, instead of ozone water, cleaning water containing a surfactant may be supplied to the wafer polishing surface to form an organic film on the polishing surface. In this case, a cleaning water supply nozzle may be provided instead of the ozone water supply nozzle 15.

[Third Embodiment] Next, a wafer polishing apparatus of a third embodiment will be described. The wafer polishing apparatus of the third embodiment also has a configuration capable of continuously carrying the wafer from the mirror polishing step to the final cleaning step, and its schematic configuration is the apparatus of the first embodiment (FIG. 1). Since it is the same as the above, illustration is omitted.

The wafer polishing apparatus of this embodiment is different from the apparatus of the first embodiment only in that the carrier water in the underwater carrier path 3 is ozone water.

The final polishing process of the wafer W by the final polishing apparatus 13 is performed in the same manner as in the first embodiment. And
Upon completion of the finish polishing, the wafer W is immediately transferred to the cleaning device 5 by the underwater transfer path 3. In the underwater transport path 3, at least the polishing surface of the wafer is unloaded in a state of being in contact with the ozone water that is the transport water, whereby an oxide film is formed on the polishing surface of the wafer W being transported.

In the apparatus of the present embodiment, the underwater transfer path 3 is of a single-wafer type and is used for tray transfer, and the polishing surface side of the wafer is immersed in the transfer water in the tray.

As described above, in the polishing method by the wafer polishing apparatus of this embodiment, since the oxide film is formed on the polishing surface of the wafer W being transported through the underwater transport path 3, the polishing surface of the wafer is finished to be a hydrophilic surface. In this state, it is possible to shift to the final cleaning process, and as a result, it is possible to further prevent the adhesion of particles.

Although ozone water is used as the carrier water in the underwater carrier path 3 of this embodiment, hydrogen peroxide solution is used as the carrier water instead of the ozone water so that an oxide film is formed on the polished surface of the wafer. It may be configured. Alternatively, water containing a surfactant may be used as the carrier water to form an organic film on the polishing surface of the wafer W being carried.

[0051]

[Fourth Embodiment] Next, a wafer polishing apparatus of a fourth embodiment will be described. The wafer polishing apparatus of the fourth embodiment is also equipped with a configuration capable of continuously carrying the wafer from the mirror polishing process to the final cleaning process, and its schematic configuration is shown in FIG. As shown in FIG. 3, the polishing unit 1
And an underwater transfer path 3 for transferring the wafer mirror-polished by the polishing section to the single-wafer cleaning device 5.

The wafer polishing apparatus of this embodiment is firstly provided with the surfactant supply nozzle 16 in the underwater transfer path 3.
Different from the embodiment. Since other configurations are the same as those in the first embodiment, the same reference numerals as those in FIG.

The surfactant supply nozzle 16 is used for the underwater transport path 3.
A predetermined surfactant is added to the carrier water (pure water) therein, which constitutes the surfactant supply means of the present invention.

The final polishing process of the wafer W by the final polishing apparatus 13 is performed in the same manner as in the first embodiment. And
Upon completion of the finish polishing, the wafer W is immediately transferred to the cleaning device 5 by the underwater transfer path 3. In the underwater transport path 3, at least the polishing surface of the wafer is carried out while being in contact with the transport water. At this time, the surfactant supply nozzle 1
From 6, the rotation activator is added to the carrier water. Therefore, the organic film is formed by the surfactant on the polished surface of the wafer being transported.

As described above, in the polishing method by the wafer polishing apparatus of this embodiment, since the organic coating is formed on the polishing surface of the wafer W being transported through the underwater transport path 3, the polishing surface of the wafer is finished to be a hydrophilic surface. In this state, the final cleaning process can be performed, and as a result, it is possible to further prevent particles from adhering to the wafer.

[0057]

[0058]

EXAMPLE The conditions of the following [Experiment 1], [Experiment 2], and [Experiment 3] were changed, and the steps of mirror polishing, underwater transfer, and cleaning of a silicon wafer were carried out and remained on the wafer surface. The number of particles was measured. The number of particles is 80
It is the remaining number of those having a size of nm or more. [Experiment 1] Polishing (without water rinsing (water polishing)) → pure water roll transfer → cleaning [Experiment 2] Polishing (with water rinsing (water polishing)) → pure water roll transfer with surfactant added → cleaning [Experiment 3 Polishing (no water rinsing (water polishing)) → conveying pure water roll with surfactant added → cleaning Further, the following steps were performed as a comparative example, and the number of particles having a size of 80 nm or more remaining on the wafer surface was measured.

[Comparative Example] Polishing (with water rinsing (water polishing)) → pure water roll transfer → cleaning

[Measurement Result] FIG. 4 shows the measurement result of the number of particles. As can be seen from FIG. 4, Experiment 1 and Experiment 3
As described above, the number of particles is smaller when the water rinsing (water polishing) treatment is omitted as compared with the case of the comparative example where the water rinsing treatment is performed. In addition, as in Experiment 2, in the case where the surfactant was added in the pure water roll transfer of the wafer, the pure water roll transfer was performed without adding the surfactant.
It can be seen that the number of particles is reduced as compared with [Comparative Example]. Further, as in Experiment 3, when the water rinsing treatment is omitted and the surfactant is added by the pure water roll conveyance, it can be seen that the particle reduction effect is most obtained.

[0061]

As described above, according to the present invention,
By the hydrophilic treatment, the polished surface of the wafer after mirror polishing can be made hydrophilic and the final cleaning treatment can be performed.
There is an effect that the adhesion of particles to the wafer can be further reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a wafer polishing apparatus according to first and third embodiments.

FIG. 2 is a schematic configuration diagram of a wafer polishing apparatus of a second embodiment.

FIG. 3 is a schematic configuration diagram of a wafer polishing apparatus of a fourth embodiment.

FIG. 4 is an explanatory diagram showing the number of particles remaining on the wafer surface according to the present embodiment.

[Explanation of symbols]

1: Polishing part 3: Submersible transport path 5: Cleaning device 12: Rough polishing device 13: Finishing polishing device 14: Slurry supply nozzle (polishing liquid supply means) 15: Ozone water supply nozzle (or hydrogen peroxide water supply nozzle or cleaning) Water supply nozzle) 16: Surfactant supply nozzle 31: Scrub cleaning device 32: Spin cleaning device W: Wafer substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenro Hayashi 1 555 Nakanoya, Annaka-shi, Gunma Inside the Super Silicon Research Institute (56) References JP 10-74716 (JP, A) JP JP 11-340184 (JP, A) JP 10-270396 (JP, A) JP 9-115869 (JP, A) JP 11-307485 (JP, A) JP 2001-313278 (JP, A) ) JP 2002-217152 (JP, A) JP 2002-119931 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304 B24B 37/04

Claims (3)

(57) [Claims] 1. A step of mirror-polishing a surface of a semiconductor wafer using a polishing liquid containing an abrasive, and a step of carrying the mirror-polished semiconductor wafer underwater to a single-wafer cleaning apparatus using carrier water. In the method of polishing a semiconductor wafer , the semiconductor wafer is rotated by a polishing head during the mirror polishing.
Finishing while pressing the rotating surface plate with a predetermined pressure
After holding the polishing process, keep the polishing head
The semiconductor wafer on the surface plate is lower than the predetermined pressure.
A method for polishing a semiconductor wafer, comprising a hydrophilic treatment step of performing a hydrophilic treatment on the surface plate without performing a water rinse treatment in a pressurized or non-pressurized state . Wherein said hydrophilic treatment step, the semiconductor wafer according to claim 1, wherein those supplying the polishing liquid to the polishing surface of the front <br/> Symbol wafer on a platen Polishing method. 3. The hydrophilic treatment step comprises supplying ozone water, hydrogen peroxide water, or water containing a surfactant to the polishing surface of the wafer on the surface plate. The method for polishing a semiconductor wafer according to claim 1, wherein the method is for polishing a semiconductor wafer.