JP2003229391A - Dressing method for polishing cloth for semiconductor substrate - Google Patents

Abstract

(57) Abstract: A dressing method capable of increasing the porosity of a porous layer on the surface of a polishing pad for a semiconductor substrate in a short time. A dressing of a polishing cloth used for polishing a semiconductor crystal substrate is performed using ultrapure water at 40 ° C or higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dressing method for a polishing cloth used for polishing a semiconductor crystal wafer.

[0002]

2. Description of the Related Art Compound semiconductors are used in the fabrication of devices such as Schottky gate field effect transistors (MESFET), high mobility transistors (HEMT), heterojunction bipolar transistors (HBT), and various light emitting and receiving devices. There is. The active layers of these devices are the molecular beam epitaxial growth (MBE) method and the
It is created by a metal organic vapor phase epitaxial growth (MOVPE) method or the like.

The mirror-finished wafer is prepared by the following procedure.

First, a crystal ingot is sliced and a wafer is cut out. This sliced wafer # 800- # 30
After rough polishing with alumina abrasive grains of No. 00 to improve the flatness, the wafer is attached to an attachment plate having a highly-finished surface flatness using wax or the like.

Next, as a polishing liquid, a hypochlorous acid-based aqueous solution,
A polishing cloth having a porous layer on its surface is used, and the wafer surface is mirror-finished by mechanochemical polishing.

After the polishing, the polishing liquid on the wafer and the attachment plate is quickly washed with water. Finally, the wafer is dried by spin drying or N ₂ blow.

Immediately after replacement of the polishing cloth and between polishing, dressing of the polishing cloth is performed. As a method of this dressing, clogging of the surface and the inside of the polishing cloth and foreign matters are removed by brushing while flowing ultrapure water at about 20 ° C. into the polishing cloth.

[0008]

However, the problem with the prior art is that the dressing after replacement of the polishing cloth is
Since it is performed with ultrapure water at about 0 ° C., the porosity of the porous layer on the surface of the polishing cloth is low and the retention of the polishing liquid is poor. Therefore, the polishing characteristics are poor at the beginning of using the polishing cloth, and the rate of occurrence of haze, that is, so-called clouding defect, on the mirror surface of the wafer increases.

Therefore, conventionally, in order to increase the porosity of the porous layer on the surface of the polishing cloth, it is necessary to use the plate to which the wafer is attached for one hour or more to perform the polishing cloth leveling operation. Therefore, in the conventional dressing method,
The polishing liquid cost and the number of man-hours required for the break-in operation are very low, resulting in very poor efficiency.

Therefore, an object of the present invention is to solve the above problems and to provide a dressing method capable of increasing the porosity of the porous layer on the surface of the polishing cloth for semiconductor substrates in a short time.

[0011]

In order to achieve the above object, the present invention is configured as follows.

A dressing method for a polishing cloth for a semiconductor substrate according to a first aspect of the present invention is characterized in that in the dressing method for a polishing cloth used for polishing a semiconductor crystal substrate, dressing is performed using ultrapure water at 40 ° C. or higher. To do.

A dressing method for a polishing cloth for a semiconductor substrate according to a second aspect of the present invention is a dressing method for removing clogging of a polishing cloth for mechanochemically polishing a semiconductor crystal wafer and removing foreign matter. While flowing
It is characterized by dressing with a brush.

According to a third aspect of the invention, in the dressing method for a polishing cloth for semiconductor substrates according to the first or second aspect, the polishing cloth to be dressed is a group IV semiconductor, a group III-V compound semiconductor or a group II-VI compound. It is a polishing cloth for semiconductors.

According to a fourth aspect of the present invention, in the dressing method for a semiconductor substrate polishing cloth according to the third aspect, the polishing cloth to be dressed is a polishing cloth for GaAs, semi-insulating GaAs or InP. To do.

<Points of the Invention> In order to increase the porosity of the porous layer on the surface of the polishing cloth in a short time, dressing is performed using ultrapure water at 40 ° C. or higher instead of ultrapure water at around 20 ° C. Is very effective. For example, by brushing for about 3 minutes while supplying ultrapure water at 40 ° C. to the polishing cloth,
The haze value of the polishing cloth at the beginning of use can be reduced, and the life of the polishing cloth can be extended.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on Examples.

<Example 1> Dressing immediately after replacement of the polishing cloth was carried out for 3 minutes using a brush while supplying ultrapure water at 20 ° C (conventional example) and 40 ° C (this embodiment) to the polishing cloth.
The polishing cloth used was a Fujimi polishing cloth (trade name: Sufine000). Then, polishing was performed for a certain period of time using a ceramic plate to which five wafers having a diameter of 150 mm were attached. Subsequent polishing and dressing performed between polishing are 2
While supplying ultrapure water of 0 ° C. and 40 ° C. to the polishing cloth, it was performed for 15 seconds using a brush. Haze against the number of polishing (HA
The relationship between ZE) values (haze level: number of haze defects (surface roughness)) is shown in FIG.

From these results, the polishing cloth dressed using the ultrapure water at 40 ° C. of this example has a lower HAZE value at the beginning of use of the polishing cloth than the conventional example, and the initial polishing cloth A significant improvement in properties was obtained. Also, with respect to the number of polishing times, streak defects called polish marks began to appear after about 150 times in the conventional dressing with ultra pure water at 20 ° C. However, dressing with ultra pure water at 40 ° C. according to the present example. No polishing mark was observed even after the number of polishing was 300 times or more, and the life of the polishing cloth was doubled or more.

<Example 2> The same experiment as in Example 1 was conducted using ultrapure water at 80 ° C. As a result, the same result as the dressing at 40 ° C. was obtained. That is, the HAZE value at the beginning of use of the polishing cloth was lower than that of the conventional example, and the life of the polishing cloth was more than doubled.

[0021]

As described above, according to the present invention, dressing is performed using ultrapure water at 40 ° C. or higher instead of ultrapure water at about 20 ° C., and therefore the following excellent effects are obtained. To be

(1) According to the present invention, the porosity of the porous layer on the surface of the polishing cloth can be increased in a short time. Therefore,
The dressing time immediately after the polishing cloth is replaced and the initial characteristics of the polishing cloth are significantly improved.

(2) Further, according to the present invention, the life of the polishing cloth is significantly extended.

(3) Then, the quality of the wafer polished by the polishing cloth using the dressing method of the present invention is improved. Therefore, by using a wafer polished with a polishing cloth using the dressing method of the present invention, good epitaxial crystals can be obtained and the device yield can be increased.

[Brief description of drawings]

FIG. 1 shows the relationship between the number of polishing times and HAZE when dressing is performed at the ultrapure water supply temperature according to the method of the present invention.
It is the figure shown in comparison with the prior art example.

Claims (4)

[Claims] 1. A dressing method for a polishing cloth used for polishing a semiconductor crystal substrate, which comprises dressing with ultrapure water at 40 ° C. or higher. 2. A dressing method for removing clogging of a polishing cloth and removing foreign matter for mechanochemically polishing a semiconductor crystal wafer, wherein dressing is performed using a brush while flowing ultrapure water at 40 ° C. or higher. Dressing method for polishing cloth for substrate. 3. The semiconductor substrate according to claim 1, wherein the polishing cloth to be dressed is a polishing cloth for a group IV semiconductor, a group III-V compound semiconductor or a group II-VI compound semiconductor. Dressing method for polishing cloth. 4. The polishing cloth for dressing is GaA.
4. A dressing method for a polishing cloth for a semiconductor substrate according to claim 3, which is a polishing cloth for s, semi-insulating GaAs or InP.