JP2003100671A - Semiconductor crystal wafer and method of polishing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of polishing semiconductor crystal wafer by which a semiconductor wafer having a low haze level can be obtained stably, and to provide a semiconductor crystal wafer. SOLUTION: When a surface active agent is added to a polishing solution used by a polishing device, the mechanical action of the polishing cloth of the polishing device can be reduced by the lubricating action of the agent. Consequently, the semiconductor crystal wafer having a low haze level can be obtained stably.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for polishing a semiconductor crystal wafer and a semiconductor crystal wafer.

[0002]

BACKGROUND OF THE INVENTION Compound semiconductors are used in the manufacture of various light emitting and receiving devices such as Schottky gate field effect transistors (MESFETs), high electron mobility transistors (HEMTs) and heterojunction bipolar transistors (HBTs). The active layers of these devices are manufactured on the surface of the mirror-finished wafer by the molecular beam epitaxial growth (MBE) method, the metal organic vapor phase epitaxial growth (MOVPE) method, or the like.

Here, the mirror-finished wafer is manufactured by the following method.

First, a semiconductor crystal ingot is sliced with a blade and the wafer is cut out to obtain a sliced wafer.

This sliced wafer is # 800- # 300
After rough polishing with a lapping machine using 0 alumina abrasive grains to improve flatness, a hypochlorous acid-based aqueous solution, bromine-
A methanol solution or colloidal silica is used, a polishing cloth having a porous layer on the surface is used, and the mirror surface is finished by mechanochemical polishing.

Next, degreasing cleaning, cleaning with a cleaning liquid having an extremely slight etching action, and ultrapure water cleaning are performed.

Finally, the wafer is dried by an isopropyl alcohol vapor drying method or a spin drying method to obtain a mirror-finished wafer.

[0008]

By the way, a wafer which is mirror-finished by the polishing method described in the above-mentioned prior art is
Haze (so-called cloudiness) occurs. The value indicating the degree of haze (haze level) is greatly affected by the state of the polishing cloth and increases as the polishing cloth is used, and is not stable. For wafers with haze,
When an epitaxial crystal is grown, there is a problem that the surface of the epitaxial crystal is roughened and the crystal quality is deteriorated.

Therefore, an object of the present invention is to solve the above problems and provide a semiconductor crystal wafer polishing method and a semiconductor crystal wafer for stably obtaining a wafer having a low haze level.

[0010]

In order to achieve the above object, a method for polishing a semiconductor crystal wafer according to the present invention uses a method in which a polishing liquid is mixed with a surfactant and an alkaline aqueous solution. The surface of the semiconductor wafer is polished.

In addition to the above structure, in the method for polishing a semiconductor crystal wafer of the present invention, the semiconductor wafer is preferably a III-V group compound semiconductor or a II-VI group compound semiconductor.

In addition to the above structure, in the method for polishing a semiconductor crystal wafer according to the present invention, it is preferable that the polishing liquid comprises at least one of a bromine-methanol solution, a solution containing hypochlorous acid and colloidal silica.

In addition to the above structure, in the method for polishing a semiconductor crystal wafer according to the present invention, the surfactant is preferably a nonionic surfactant.

In addition to the above structure, in the method for polishing a semiconductor crystal wafer of the present invention, the nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polystyryl phenyl ether, polyhydric alcohol fatty acid. It is preferably any one of partial ester, trialkylamine oxide, polyoxyethylene alkyl ether, fatty acid diethanolamide and polyglycerin fatty acid ester.

In addition to the above structure, in the method for polishing a semiconductor crystal wafer of the present invention, the alkaline aqueous solution is NaOH, KOH,
It is preferably a mixed solution of at least two kinds of NaHCO ₃ , KHCO ₃ and NH ₄ OH.

The semiconductor crystal wafer of the present invention is polished by using a mixture of a polishing liquid with a surfactant and an alkaline aqueous solution.

Here, the haze level increases as the number of times the polishing cloth is used increases. When the polishing cloth is used many times, the porous layer on the surface of the polishing cloth is crushed. This porous layer has a function of holding a polishing liquid. With this function, sufficient polishing liquid is supplied to the wafer surface.

However, if the porous layer is crushed,
The holding power of the polishing liquid deteriorates, and it becomes impossible to supply a sufficient polishing liquid to the wafer surface. Therefore, the chemical action on the surface of the wafer becomes small and the mechanical action becomes relatively large. As a result, the surface of the wafer is strongly rubbed with the polishing cloth of the polishing apparatus, so that the surface becomes rough, which causes haze. Therefore, in order to reduce the surface roughness, the mechanical action of rubbing with the polishing cloth may be reduced.

Therefore, when a surfactant is added to the polishing liquid, the mechanical action of the polishing cloth can be reduced by the anti-friction action of the surfactant. As a result, a wafer with a low haze level can be stably obtained.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.

The method of polishing a semiconductor crystal wafer of the present invention comprises:
The surface of a semiconductor wafer is polished by using a mixture of a polishing liquid with a surfactant and an alkaline aqueous solution.
The semiconductor crystal wafer of the present invention is a semiconductor crystal wafer polished by using a mixture of a polishing liquid with a surfactant and an alkaline aqueous solution.

The semiconductor wafer may be a III-V group compound semiconductor or a II-VI group compound semiconductor, and the polishing liquid may be at least one of a bromine-methanol solution, a solution containing hypochlorous acid and colloidal silica. A solution may be mentioned.

As the surfactant, a nonionic surfactant is preferable, and polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene polystyryl phenyl ether, polyhydric alcohol fatty acid partial ester, trialkylamine oxide, Mention may be made of polyoxyethylene alkyl ethers, fatty acid diethanolamides and polyglycerin fatty acid esters.

As the alkaline aqueous solution, NaOH, KO
A mixed solution of at least two kinds of H, NaHCO ₃ , KHCO ₃ and NH ₄ OH is preferable.

By polishing a semiconductor wafer with the above-mentioned polishing liquid, surfactant and alkaline aqueous solution,
A wafer with a low haze level can be stably obtained.

[0026]

The present invention will be described below with reference to specific numerical values, but the present invention is not limited thereto.

(Example 1) A GaAs wafer rough-polished with # 1500 alumina abrasive grains was mirror-finished by mechanochemical polishing. As the polishing liquid, a mixture of hypochlorous acid, polyoxyethylene alkyl ether, and an alkaline aqueous solution was used, and the type of the alkaline aqueous solution was changed to perform polishing. The haze level of the mirror-polished wafer is measured by a mirror surface inspection device (Surfscan 620 manufactured by Tencor Co.
0). In addition, the surface was visually observed using a concentrator of 200,000 lux.

For comparison, wafers polished only with hypochlorous acid and wafers polished with a mixed solution of hypochlorous acid and polyoxyethylene alkyl ether were subjected to the same treatment. The results are shown in Table 1.

[0029]

[Table 1]

No haze was observed in the light concentrator on the wafer polished with a solution of a mixture of hypochlorous acid, polyoxyethylene alkyl ether and an aqueous alkali solution, and the haze level was 0.1 to 0.5 ppm. And low.

However, a wafer polished only with hypochlorous acid or a wafer polished with a mixed solution of hypochlorous acid and polyoxyethylene alkyl ether causes fog and scratches and has a haze level of 1.0 to 3. It is as high as 0.0 ppm.

(Example 2) A GaAs wafer rough-polished with # 1500 alumina abrasive grains was mirror-finished by mechanochemical polishing. As the polishing liquid, a mixed liquid of hypochlorous acid, trialkylamine oxide and an alkaline aqueous solution was used, and polishing was performed by changing the kind of the alkaline aqueous solution.
The haze level of this mirror-polished wafer was examined by using the mirror surface inspection apparatus used in Example 1. In addition, the surface was visually observed using a concentrator of 200,000 lux.

For comparison, the same treatment was applied to a wafer polished only with hypochlorous acid or a wafer polished with a mixed solution of hypochlorous acid and trialkylamine oxide. The results are shown in Table 2.

[0034]

[Table 2]

For a wafer polished with a mixed solution of hypochlorous acid, trialkylamine oxide and an aqueous alkali solution,
No cloudiness was observed in the observation of the condenser, and the haze level was low at 0.1 to 0.5 ppm.

However, a wafer polished only with hypochlorous acid or a wafer polished with a mixed solution of hypochlorous acid and trialkylamine oxide causes cloudiness and scratches and has a haze level of 1.0 to 3. It is as high as 0.0 ppm.

(Example 3) A GaAs wafer roughly polished with # 1500 alumina abrasive grains was mirror-finished by mechanochemical polishing. The polishing liquid used was a mixture of a bromine-methanol solution, a trialkylamine oxide, and an alkaline aqueous solution, and the type of the alkaline aqueous solution was changed. The haze level of this mirror-polished wafer was examined by using the mirror surface inspection apparatus used in Example 1. Also, 20
The surface was visually observed using a 10,000 lux collector.

For comparison, a wafer polished only with a bromine-methanol solution and a wafer polished with a mixed solution of a bromine-methanol solution and trialkylamine oxide were subjected to the same treatment. The results are shown in Table 3.

[0039]

[Table 3]

No cloudiness was observed in the light concentrator on the wafer polished with a mixture of a bromine-methanol solution, a trialkylamine oxide and an alkaline aqueous solution.
The haze level is as low as 0.1 to 0.5 ppm.

However, the wafer polished with only hypochlorous acid or the wafer polished with the mixed solution of the bromine-methanol solution and the trialkylamine oxide has fog and scratches, and the haze level is 1.0 to 3. It is as high as 0 ppm.

Example 4 The same treatment as in Example 1 was carried out by using colloidal silica instead of hypochlorous acid, and the same result as in Example 1 was obtained.

Example 5 InP was used instead of GaAs, and the same treatment as in Example 3 was performed.
The exact same result was obtained.

As described above, according to the present invention, since only the composition of the polishing liquid is improved, it is not necessary to newly use a special device and it is not necessary to construct a new polishing process, which is economically advantageous. is there. By using the semiconductor crystal wafer that has been subjected to the polishing method of the present invention, a high quality epitaxial layer can be obtained and the device yield can be increased.

[0045]

In summary, according to the present invention, the following excellent effects are exhibited.

It is possible to realize a method for polishing a semiconductor crystal wafer and a semiconductor crystal wafer for stably obtaining a wafer having a low haze level.

Continued front page    (72) Inventor Ken Ikeda             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Wire Co., Ltd. Hidaka Factory (72) Inventor Hiroki Akiyama             Hitachi, 1-1 Hidaka-cho, Hitachi City, Ibaraki Prefecture             Electric Wire Co., Ltd. Hidaka Factory F-term (reference) 3C058 AA07 AC04 DA02 DA12 DA17

Claims (7)

[Claims] 1. A method for polishing a semiconductor wafer, which comprises polishing the surface of a semiconductor wafer using a mixture of a surfactant and an alkaline aqueous solution in a polishing liquid. 2. The method for polishing a semiconductor crystal wafer according to claim 1, wherein the semiconductor wafer is a III-V group compound semiconductor or a II-VI group compound semiconductor. 3. The method for polishing a semiconductor crystal wafer according to claim 1, wherein the polishing liquid comprises at least one of a bromine-methanol solution, a solution containing hypochlorous acid, and colloidal silica. 4. The method for polishing a semiconductor crystal wafer according to claim 1, wherein the surfactant is a nonionic surfactant. 5. The nonionic surfactant is polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene polystyryl phenyl ether, polyhydric alcohol fatty acid partial ester, trialkylamine oxide, polyoxyethylene alkyl. An ether, a fatty acid diethanolamide, or a polyglycerin fatty acid ester.
5. The method for polishing a semiconductor crystal wafer according to any one of 1 to 4. 6. The alkaline aqueous solution is NaOH or KO.
The method for polishing a semiconductor crystal wafer according to claim 1, wherein the method is a mixed solution of at least two kinds of H, NaHCO ₃ , KHCO ₃ and NH ₄ OH. 7. A semiconductor crystal wafer polished by using a mixture of a polishing liquid with a surfactant and an alkaline aqueous solution.