TWI524411B - A group iii-v compound semiconductor wafer and method for cleaning the same - Google Patents

Description

III-V compound semiconductor wafer and cleaning method thereof

The invention relates to a III-V compound semiconductor wafer and a cleaning method thereof.

With the development of semiconductor lasers, optical communication components for optical communication, and high-speed and high-frequency semiconductor device manufacturing technologies, the cleanliness of III-V compound semiconductor materials (such as gallium arsenide, indium phosphide, etc.), especially The requirements for surface cleanliness are getting higher and higher.

For the main applications of semiconductor wafers, the main contaminants on the surface are particles and metal ions.

For another type of semiconductor wafer wafer, there is a common cleaning method, the RCA method proposed by Kern and Puotinen (RCA Review, vol. 31, pp. 187-206, June, 1970). In this method, the particles are washed with aqueous ammonia and aqueous hydrogen peroxide (SC-1), and the metal is removed with hydrochloric acid and aqueous hydrogen peroxide (SC-2).

However, III-V compound semiconductor materials, such as indium phosphide semiconductor materials, are binary compounds, so that the reaction characteristics of the wafer surface are different from those of the germanium wafer, so the cleaning method of the germanium wafer cannot be applied. In particular, the above RCA also has the disadvantage that although the SC-1 solution is capable of substantially removing particulate matter from the surface of the semiconductor wafer, it also brings additional sources of foreign metal contamination. Despite the latter step SC-2 Solution treatment has the potential to reduce the concentration of foreign metal impurities on the wafer surface, but the result of this treatment is to increase the amount of particulate matter adhering to the wafer (P.H. Singer, Semiconductor International, pp. 36-39, December, 1992). In addition, due to corrosion cleaning in some places, and some areas have not been corroded and cleaned, the surface of the wafer is not corroded unevenly. Such wafers are not ideal for subsequent epitaxial growth.

A method for cleaning a gallium arsenide (III-V compound) semiconductor wafer is described in Chinese patent CN101661869, which comprises treating with a cleaning agent under ultrasonic action, respectively using concentrated sulfuric acid and NH ₄ OH-H ₂ O ₂ solution. Clean the gallium arsenide wafer. This method does not effectively remove metal residues and the surface of the cleaned gallium arsenide wafer is severely corroded, so it is not easy to apply this method to clean other III-V compound semiconductor wafers, especially indium phosphide semiconductor wafers.

Therefore, the prior art method is difficult to remove particles and metal residues on the surface of the III-V compound semiconductor material (for example, indium phosphide semiconductor material), and at the same time, to ensure the uniformity of the surface of the wafer.

The invention provides a method for cleaning a III-V compound semiconductor wafer, the method comprising the steps of: (1) treating a wafer with a concentrated acid at not lower than 50 ° C; (2) using a concentrated acid at not higher than Processing wafers at 30 ° C; (3) washing wafers with high purity water; (4) treating wafers with an organic acid solution; (5) washing wafers with high purity water; (6) using a NH ₄ OH-H ₂ O ₂ solution Processing the wafer; (7) washing the wafer with high purity water; and (8) drying the resulting wafer.

The method of the invention can not only effectively reduce the particle and metal residue on the surface of the wafer, but also improve the corrosion uniformity of the surface of the wafer and reduce the haze value, thereby improving the spot defect on the surface of the wafer. Effect.

Therefore, the present invention also provides a III-V compound semiconductor wafer characterized in that, in a surface area of more than 0.11 μm ² per square centimeter of wafer surface area, 0.5 particles (by statistical division divided by wafer surface area), crystal The metal residue on the round surface was Cu ≦ 10 × 10 ¹⁰ atoms/cm ² and Zn ≦ 10 × 10 ¹⁰ atoms/cm ² , and the surface average white fog value was 1.0 ppm.

The invention provides a method for cleaning a III-V compound semiconductor wafer, comprising the steps of: (1) treating a wafer with a concentrated acid at not lower than 50 ° C; (2) treating with a concentrated acid at not higher than 30 ° C Wafer; (3) washing the wafer with high purity water; (4) treating the wafer with an organic acid solution; (5) washing the wafer with high purity water; (6) treating the wafer with a NH ₄ OH-H ₂ O ₂ solution (7) washing the wafer with high purity water; and (8) drying the resulting wafer.

Unexpectedly, the method of the present invention not only enables effective cleaning of the wafer surface, reduces wafer surface particles and significantly reduces the residual amount of metals, especially copper and zinc, but also ensures the uniformity of corrosion. Make the white fog value lower. Therefore, the wafer obtained by the method of the present invention can be suitably used as an epitaxial substrate.

In the method of the present invention, the wafer used as the original wafer (ie, the wafer used in the step (1)) is a wafer that has been subjected to mechanochemical polishing and chemical fine polishing (ie, a wafer that has been finished with fine mirror polishing), usually Is a single-sided polished wafer with a micro-roughness Ra of the polished surface 0.5 nm (tested by AFM (atomic force microscope)), preferably Ra 0.3 nm. If both sides are required to be polished, the above parameters are the average of the two sides.

In the step (1) of the method of the present invention (processing a wafer with a concentrated acid at not lower than 50 ° C), preferably, the concentrated acid is a mineral acid including, but not limited to, sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid. Etc., preferably nitric acid or sulfuric acid. Since the solubility of different acids is different at a certain temperature, when different acids are used, the concentrated acid at the treatment temperature is used, for example, when the concentration is 60% or more of the saturated concentration at the corresponding temperature, It is considered to be "concentrated acid". Preferably, when sulfuric acid is used, its concentration C ₁ is usually not less than 65% by weight. Usually, the concentration of sulfuric acid used is from 65 to 98% by weight, preferably from 70 to 97% by weight. The treatment temperature T ₁ is usually from 50 to 80 ° C, preferably from 55 to 75 ° C, more preferably from 60 to 70 ° C. The temperature in the treatment step may vary as long as the temperature is not lower than 50 °C. The treatment time P _{1 of} this step is usually from 1 to 20 seconds, preferably from 2 to 18 seconds, more preferably from 3 to 15 seconds. The treatment includes, but is not limited to, rinsing and immersion, etc., preferably immersion treatment. During processing, it is preferred to use mega-sonic or ultrasonic processing.

In step (2) of the method of the invention (processing the wafer with a concentrated acid at not higher than 30 ° C), preferably, the concentrated acid is a mineral acid including, but not limited to, sulfuric acid, hydrochloric acid, phosphoric acid and nitric acid Etc., preferably nitric acid or sulfuric acid. Since the solubility of different acids is different at a certain temperature, when different acids are used, the concentrated acid at the treatment temperature is used, for example, when the concentration is 60% or more of the saturated concentration at the corresponding temperature, It is considered to be "concentrated acid". Preferably, when sulfuric acid is used, its concentration C ₂ is usually not less than 65% by weight. Usually, the concentration of sulfuric acid used is from 65 to 98% by weight, preferably from 70 to 97% by weight. The treatment temperature T ₂ is usually not higher than 30 ° C, preferably not higher than 25 ° C. The temperature in the treatment step may vary as long as the temperature is not higher than 30 °C. Usually, the treatment temperature is 5 to 30 ° C, preferably 8 to 28 ° C, more preferably 10 to 25 ° C. The treatment time P _{2 of} this step is usually from 0.5 to 15 seconds, preferably from 1 to 12 seconds, more preferably from 2 to 10 seconds. The treatment includes, but is not limited to, rinsing and immersion, etc., preferably immersion treatment. In the course of processing, it is preferred to use a million frequency ultrasonic or ultrasonic processing.

Preferably, steps (1) and (2) are treated with the same acid. At this time, the same concentrated acid can be used, and the treatment is continuously performed according to different temperatures, that is, after the first step of treatment is completed, the temperature is rapidly cooled to the processing temperature of the second step to continue the treatment; in this embodiment, C ₂ is the step ( 2) The concentration at the beginning. If the acid used in the second step is different from the acid used in the first step, after the first acid treatment (1), preferably, the wafer is washed with high-purity water for 5-30 seconds before the second step of acid treatment ( 2).

In a particularly preferred embodiment of the invention, the acid concentration C _{1 of the} step (1), the treatment temperature T ₁ and the treatment time P ₁ and the acid concentration C _{2 of the} step (2), the treatment temperature T ₂ and the treatment The following relationship is satisfied between times P ₂ : C ₂ × P ₂ × (T ₂ + 273.15) ≦ C ₁ × P ₁ × (T ₁ + 273.15) ≦ 3 × C ₂ × P ₂ × (T ₂ + 273.15), In the above formulas, the concentration unit is a weight percentage concentration, the treatment temperature is Celsius, and the treatment time is seconds.

It is further preferred that the acid concentration C ₁ , the treatment temperature T ₁ and the treatment time P ₁ of the step (1) and the acid concentration C _{2 of the} step (2), the treatment temperature T ₂ and the treatment time P ₂ satisfy the following Relationship: 500 ≦C ₁ ×P ₁ ×(T ₁ +273.15)≦4,500; and 350≦C ₂ ×P ₂ ×(T ₂ +273.15)≦3,000; still more preferably: 650≦C ₁ ×P ₁ ×( T ₁ +273.15)≦3,800; and 450≦C ₂ ×P ₂ ×(T ₂ +273.15)≦2,500; still more preferably: 850≦C ₁ ×P ₁ ×(T ₁ +273.15)≦3,200; and 550≦ C ₂ × P ₂ × (T ₂ + 273.15) ≦ 2,200.

In the present invention, as the term "high-purity water" refers to the resistivity of preferably 25 deg.] C is not less than 15 million ohms × cm ^{(1.5 × 10 7 Ω × cm} ), more preferably not less than 17.5 million ohms × The water of centimeters.

In the steps (3), (5) and (7) of washing the wafer with high-purity water, the respective steps are preferably carried out at a lower temperature, for example, at a temperature not higher than 30 ° C (for example, 3 to 30 ° C), preferably at no A temperature higher than 25 ° C (for example, 5 to 25 ° C) is more preferably carried out at a temperature of 8 to 20 ° C. The washing time is usually from 10 to 100 seconds, preferably from 12 to 80 seconds, more preferably from 15 to 60 seconds.

In the step (4) of the method of the present invention (treatment of the wafer with an organic acid solution), the organic acid used may be a commonly used organic polybasic acid. The acid includes, but is not limited to, a polybasic acid of citric acid, tartaric acid, maleic acid, fumaric acid, malic acid, gluconic acid, glucoheptonic acid, C3-C12 (ie, 3-12 carbon atoms), preferably A dibasic acid or the like of C3-C10, for example, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, sebacic acid, sebacic acid or the like, preferably citric acid. The concentration C _{4 of} the organic acid is usually from 1 to 10% by weight, preferably from 2 to 8% by weight, more preferably from 3 to 6% by weight. The temperature T ₄ when treated with an organic acid is usually 10 to 30 ° C, preferably 15 to 25 ° C. The temperature in this processing step can vary. The treatment time P _{4 of} this step is usually from 15 to 35 seconds, preferably from 20 to 33 seconds. The treatment includes, but is not limited to, rinsing and immersion, etc., preferably immersion treatment.

In a particularly the present invention, preferred embodiments, step (1), Step (2) the concentration of the acid, the treatment temperature, the treatment time in step (4) the concentration of C in the acid _4, the treatment temperature T ₄ and the processing time P ₄ satisfies the following relationship: 1/10 [C ₂ × P ₂ × (T ₂ + 273.15) + C ₁ × P ₁ × (T ₁ + 273.15)] ≦ C ₄ × P ₄ × (T ₄ + 273.15) ≦ 1 /2[C ₂ ×P ₂ ×(T ₂ +273.15)+C ₁ ×P ₁ ×(T ₁ +273.15)], in the above formulas, the concentration unit is the weight percentage concentration, the treatment temperature is Celsius, and the treatment time is second.

Further preferably, the step (4) the concentration of acid in ₄ C, the treatment temperature and treatment time T ₄ P ₄ satisfy the following _{relation: 100 ≦ C 4 × P 4} × (T 4 +273.15) ≦ 1,200.

Still more preferably, 200 ≦ C ₄ × P ₄ × (T ₄ + 273.15) ≦ 900.

In the step (6) of the method of the invention (treatment of the wafer with a solution of NH ₄ OH-H ₂ O ₂ ), the NH ₄ OH-H ₂ O ₂ aqueous solution is used, and the NH ₄ OH-H is calculated by weight percentage. ₂ O ₂ aqueous solution, NH ₄ OH, H ₂ O ₂ concentrations are typically 5-25% NH ₄ OH, and 3-15% H ₂ O _2, preferably 10-22% NH ₄ OH and 5-12% H ₂ O ₂ . The treatment is advantageously carried out at 10-40 ° C, preferably at a temperature of 15-30 ° C. The temperature in this processing step can vary. The treatment time for this step is usually from 2 to 15 seconds, preferably from 3 to 12 seconds, more preferably from 4 to 10 seconds. The treatment includes, but is not limited to, rinsing or immersion, etc., preferably immersion treatment.

In a particularly preferred embodiment of the present invention, the concentration C ₆ of the aqueous ammonia, the treatment temperature T _{6 of the} step (6), and the treatment time P _{6 in the} step (6) satisfy the following relationship: 50 ≦ C ₆ × P ₆ × ( T ₆ +273.15) ≦ 1,000 is _{preferably, 80 ≦ C 6 × P 6} × (T 6 +273.15) ≦ 800 further _{preferably, 100 ≦ C 6 × P 6} × (T 6 +273.15) ≦ 500

In the above formulas, the concentration unit is the weight percentage concentration, and the treatment temperature In degrees Celsius, the processing time is seconds.

In the step (6) of the process of the invention, the ratio of NH ₄ OH to H ₂ O ₂ is preferably from 0.5 to 7.5:1, preferably from 1 to 5:1, by weight percent.

In the step (8) of the method of the present invention, the wafer may be selected to be dried in air or an inert atmosphere (nitrogen or the like), or vacuum drying may be selected, and the drying temperature is preferably 20-120 ° C, preferably 25-90 ° C; the drying time is preferably 1 -20 minutes.

The method of the present invention is preferably suitable for cleaning III-V compound semiconductor wafers, such as wafers having a diameter of 2.50-15.0 cm, such as III-V compounds having a diameter of 5.0 cm, 7.5 cm, 10.0 cm, 12.5 cm, and 15.0 cm. Semiconductor wafers, especially indium phosphide semiconductor wafers. The obtained III-V compound semiconductor wafer has 0.5 particles per square centimeter of wafer surface area greater than 0.11 μm ² (calculated by dividing the surface area of the wafer by statistic), preferably ≦ 0.3; metal residue on the surface of the wafer Cu ≦ 10 × 10 ¹⁰ atoms/cm ² and Zn ≦ 10 × 10 ¹⁰ atoms/cm ² , preferably metal residual Cu ≦ 7 × 10 ¹⁰ atoms/cm ² and Zn ≦ 8 × 10 ¹⁰ atoms/cm ² , more preferably metal Residual Cu ≦ 2 × 10 ¹⁰ atoms / cm ² and Zn ≦ 3 × 10 ¹⁰ atoms / cm ² ; surface average white fog value ≦ 1.0 ppm, preferably surface average white fog value ≦ 0.8 ppm, more preferably ≦ 0.7 ppm; Micro roughness Ra 0.5 nm (tested by AFM (atomic force microscope)), preferably Ra 0.3 nm. Typically, the wafer is polished on one side; if two sides are required to be polished, the above parameters are the average of the two sides.

Therefore, the present invention also provides a III-V compound semiconductor wafer, characterized in that: 0.5 particles per square centimeter of wafer surface area greater than 0.11 μm ² (calculated by dividing the surface area of the wafer), preferably ≦ 0.3 particles; metal residue on the surface of the wafer Cu ≦ 10 × 10 ¹⁰ atoms / cm ² and Zn ≦ 10 × 10 ¹⁰ atoms / cm ² , preferably metal residual Cu ≦ 7 × 10 ¹⁰ atoms / cm ² and Zn ≦ 8 × 10 ¹⁰ atoms/cm ² , more preferably metal residual Cu ≦ 2 × 10 ¹⁰ atoms/cm ² and Zn ≦ 3 × 10 ¹⁰ atoms/cm ² ; surface average white fog value ≦ 1.0 ppm, preferably surface average white fog value ≦ 0.8 ppm More preferably ≦0.7 ppm; its surface micro-roughness Ra 0.5 nm (tested by AFM (atomic force microscope)), preferably Ra 0.3 nm. Typically, the wafer is polished on one side; if two sides are required to be polished, the above parameters are the average of the two sides. The III-V compound semiconductor wafer, for example, a wafer having a diameter of 2.50-15.0 cm, such as a III-V compound semiconductor wafer having a diameter of 5.0 cm, 7.5 cm, 10.0 cm, 12.5 cm, and 15.0 cm, especially phosphorus Indium semiconductor wafers.

In the present invention, all percentages or parts are by weight unless otherwise stated. All concentrations are calculated based on the pure substance of the substance, unless otherwise stated.

EXAMPLES: Instruments and devices: wet cleaning stations (including tanks and washing tanks for soaking wafers); wafer rotary dryers (Semitool Model SRD, USA).

Wafer quality inspection equipment: Yamada glare (light is stronger than 100,000 Lux); wafer surface analyzer (KLA-TENCOR company 6220); atomic force microscope (AFM) (Digital Instrument, USA) NanoScope Type IIIa) (Vertical resolution 0.03 nm, analysis area 5 μm × 5 μm); Wafer surface elements were tested with TXRF (Reflective X-Ray Fluorescence Analyzer; TREX Model 610, OSAKA Japan Technos).

Experimental Wafer: Unless otherwise stated, an indium phosphide wafer with a diameter of 5.08 cm (2 inches), one of which was finely mirror polished, with a thickness of 350 μm, and a micro-roughness of the polished surface Ra = 0.3 nm . All tests are for polished surfaces (as for non-indium phosphide wafers).

Comparative example 1

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 93% by weight of concentrated sulfuric acid at 65 ° C for 3 seconds; (2) taking the above wafer and immersing it in 98% by weight of concentrated sulfuric acid Processing at 25 ° C for 3 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle was immersed in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O in a weight ratio of 1:2:7) at 25 ° C for 7 seconds; (5) then at 25 ° C The wafer is placed in a rinse tank, and the surface of the wafer is rinsed with high-purity water having a resistivity of more than 17.5 million ohms for 30 seconds; (6) The rinsed wafer is placed in a wafer rotary dryer with hot nitrogen (70 ° C) ) Dry for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR 6220, and atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles but white fog. For the inspection of KLA-TENCOR 6220 type in the United States, 18 particles (0.89 particles/cm ² ) having an area larger than 0.11 μm ^{2 and} a haze value (1.3 mg) were used. Metal content measured by TXRF, Cu = 20x10 ¹¹ atoms / cm ^2, Zn = 23x10 ¹¹ atoms / cm ^2.

Comparative example 2

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 90% by weight of concentrated sulfuric acid at 65 ° C for 3 seconds; (2) taking the above wafer and immersing it in 95% by weight of concentrated sulfuric acid 25 ° C for 2 seconds; (3) then at 25 ° C, the wafer is placed in the rinse tank, the surface of the wafer is rinsed with fast high purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) diluted with 4 wt% Sulfuric acid is treated at 25 ° C for 30 seconds; (5) at 25 ° C, the wafer is placed in the rinse tank, and the wafer surface is rinsed with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (6) will be rinsed The wafer is immersed in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O in a weight ratio of 1:2:7) at 25 ° C for 5 seconds; (7) then At 25 ° C, the wafer was placed in a rinse tank, and the surface of the wafer was rinsed with high-purity water having a resistivity of more than 17.5 million ohms for 30 seconds; (8) the rinsed wafer was placed in a wafer rotary dryer with hot nitrogen. (70 ° C) drying for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR 6220, and atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With the US KLA-TENCOR 6220 type, the particles with an area larger than 0.11 μm ² = 20 particles (= 0.99 particles/cm ² ), and the white fog value (Haze value) = 1.5 ppm. The metal content was measured by TXRF, Cu = 21 x ^{10 10} atoms/cm ² , and Zn = 23 x ^{10 10} atoms/cm ² .

Comparative example 3

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 95% by weight of concentrated sulfuric acid at 65 ° C for 4 seconds; (2) taking the above wafer and immersing it in 95% by weight of concentrated sulfuric acid Processing at 25 ° C for 10 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle was immersed in a 6 wt% nitric acid solution at 25 ° C for 30 seconds; (5) the wafer was then placed in a rinse tank, and the wafer surface was rinsed with high-purity water having a resistivity greater than 17.5 million ohms at 25 ° C for 20 seconds. (6) The immersed wafer is immersed in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O weight ratio 1:2:7) at 22 ° C for 6 seconds. (7) Then, at 25 ° C, the wafer is placed in a rinse tank, and the wafer surface is rinsed with high-purity water having a resistivity of more than 17.5 million ohms for 30 seconds; (8) the rinsed wafer is placed in the wafer rotation. Dry in a dryer with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With KLA-TENCOR 6220 type, particles with an area larger than 0.11 μm ² = 22 particles (1.09 particles/cm ² ), and a haze value (Haze value) = 1.2 ppm. The metal content was measured by TXRF, Cu = 22 x ^{10 10} atoms/cm ² and Zn = 21 x ^{10 10} atoms/cm ² .

Example 1

Use the following procedure to clean a 5.08 cm (2 in.) diameter finely mirrored GaAs wafer with a thickness of 350 μm and a surface micro-roughness Ra = 0.3 nm: (1) Immerse the wafer to be washed at 92% by weight. The concentrated sulfuric acid was treated at 65 ° C for 4 seconds; (2) the above wafer was taken out and then immersed in 98% by weight of concentrated sulfuric acid at 25 ° C for 2 seconds; (3) then the wafer was placed in the rinse tank at 20 ° C Rinse the wafer surface with fast high purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) immerse the rinsed wafer in an 8 wt% citric acid solution for 30 seconds at 25 ° C; (5) then crystallize The circle was placed in a rinse tank, and the surface of the wafer was rinsed with high-purity water having a resistivity of more than 17.5 million ohms at 20 ° C for 20 seconds; (6) the rinsed wafer was immersed in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O in a weight ratio of 1:2:7) at 25 ° C for 5 seconds; (7) then at 20 ° C, the wafer is placed in the rinse tank, with a resistivity greater than 17.5 Million ohms of high purity water was used to rinse the wafer surface for 30 seconds; (8) The rinsed wafer was placed in a wafer rotary dryer and dried with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With KLA-TENCOR 6220 type, 6 particles (0.30 particles/cm ² ) having an area larger than 0.11 μm ^{2 and} a haze value (0.7 mg) were used. Metal content measured by TXRF, Cu = 4x10 ¹⁰ atoms / cm ^2, Zn = 3x10 ¹⁰ atoms / cm ^2.

Example 2

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 68% by weight of concentrated nitric acid at 51 ° C for 7 seconds; (2) taking out the wafer and immersing it in 68% by weight of concentrated nitric acid Processing at 23 °C for 4 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle is immersed in a 3 wt% pimelic acid solution at 20 ° C for 30 seconds; (5) the wafer is then placed in a rinse tank, and the wafer surface is rinsed with high purity water having a resistivity greater than 17.5 million ohms at 25 ° C. 20 seconds; (6) immersing the rinsed wafer in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O weight ratio of 1:1:8) at 20 ° C 6 seconds; (7) then at 25 ° C, the wafer is placed in the rinse tank, the surface of the wafer is rinsed with high purity water with a resistivity greater than 17.5 million ohms for 30 seconds; (8) the rinsed wafer is placed in the crystal Dry in a rotary spin dryer with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With KLA-TENCOR 6220 type, 8 particles (0.39 cells/cm ² ) having an area larger than 0.11 μm ^{2 and} a haze value (Haze value) = 0.75 ppm were examined. The metal content was measured by TXRF, Cu = 4 x ^{10 10} atoms/cm ² and Zn = 4 x ^{10 10} atoms/cm ² .

Example 3

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 90% by weight of concentrated sulfuric acid at 70 ° C for 7 seconds; (2) taking the above wafer and immersing it in 93% by weight of concentrated sulfuric acid Processing at 22 ° C for 6 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle was immersed in a 3% by weight citric acid solution at 22 ° C for 30 seconds; (5) the wafer was then placed in a rinse tank, and the wafer surface was rinsed with high purity water having a resistivity greater than 17.5 million ohms at 25 ° C. (6) The immersed wafer is immersed in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O weight ratio of 0.7:1.8:7.5) at 30 ° C. Seconds; (7) then at 25 ° C, the wafer is placed in the rinse tank, the surface of the wafer is rinsed with high-purity water with a resistivity greater than 17.5 million ohms for 30 seconds; (8) the rinsed wafer is placed in the wafer Dry in a rotary drier with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With KLA-TENCOR 6220 type, 10 particles (0.49 particles/cm ² ) having an area larger than 0.11 μm ^{2 and} a haze value (Haze value) = 0.85 ppm were examined. The metal content was measured by TXRF, Cu = 7 x ^{10 10} atoms/cm ² and Zn = 8 x ^{10 10} atoms/cm ² .

Example 4

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 92% by weight of concentrated sulfuric acid at 65 ° C for 4 seconds; (2) taking the above wafer and immersing it in 95% by weight of concentrated sulfuric acid Processing at 15 ° C for 4 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle is immersed in a 3% by weight solution of glutaric acid at 25 ° C for 30 seconds; (5) the wafer is then placed in a rinse tank, and the wafer surface is rinsed with high-purity water having a resistivity greater than 17.5 million ohms at 25 ° C. 20 seconds; (6) immersing the rinsed wafer in an NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ :NH ₄ OH:H ₂ O weight ratio 1:1:8) at 18 ° C 5 seconds; (7) then at 25 ° C, the wafer is placed in the rinse tank, the surface of the wafer is rinsed with high-purity water with a resistivity greater than 17.5 million ohms for 30 seconds; (8) the rinsed wafer is placed in the crystal Dry in a rotary spin dryer with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. With KLA-TENCOR 6220 type, 6 particles (0.30 particles/cm ² ) having an area larger than 0.11 μm ^{2 and} a haze value (Haze value) = 0.70 ppm were examined. The metal content was measured by TXRF, Cu = 2 x ^{10 10} atoms/cm ² , and Zn = 3 x ^{10 10} atoms/cm ² .

Example 5

The indium phosphide wafer is cleaned by the following steps: (1) immersing the wafer to be washed in 70% by weight of concentrated sulfuric acid at 62 ° C for 13 seconds; (2) taking the above wafer and immersing it in 70% by weight of concentrated sulfuric acid Processing at 30 ° C for 10 seconds; (3) then placing the wafer into the rinse tank at 25 ° C, rinsing the wafer surface with fast high-purity water with a resistivity greater than 17.5 million ohms for 55 seconds; (4) rinsing the crystal The circle is immersed in a 5% by weight solution of adipic acid at 25 ° C for 20 seconds; (5) the wafer is then placed in a rinse tank, and the wafer surface is rinsed with high-purity water having a resistivity greater than 17.5 million ohms at 25 ° C. 20 seconds; (6) immersing the rinsed wafer in a NH ₄ OH-H ₂ O ₂ solution (H ₂ O ₂ : NH ₄ OH: H ₂ O weight ratio 1:1.5:7.5) at 15 ° C 15 seconds; (7) then at 25 ° C, the wafer is placed in the rinse tank, the surface of the wafer is rinsed with high purity water with a resistivity greater than 17.5 million ohms for 30 seconds; (8) the rinsed wafer is placed in the crystal Dry in a rotary spin dryer with hot nitrogen (70 ° C) for 15 minutes.

The dried wafer was inspected with a strong light, KLA-TENCOR Model 6220, and an atomic force microscope lamp.

The surface of the wafer was inspected with a strong light, with no visible particles or white fog. 6220 inspection KLA-TENCOR, an area greater than 0.11 μm ² is 10 particles (0.49 / cm ^2), the fog value (a Haze value) = 0.97 ppm. The metal content was measured by TXRF, Cu = 7 x ^{10 10} atoms/cm ² , and Zn = 9 x ^{10 10} atoms/cm ² .

The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments, and any other changes, substitutions, combinations, and simplifications made without departing from the spirit and principles of the present invention. Equivalent replacement means are included in the scope of protection of the present invention.

Claims (25)

A method for cleaning a III-V compound semiconductor wafer, comprising the steps of: (1) treating a wafer with a concentrated acid at not lower than 50 ° C; and (2) treating the wafer with a concentrated acid at not higher than 30 ° C (3) washing the wafer with high purity water; (4) treating the wafer with an organic acid solution; (5) washing the wafer with high purity water; (6) treating the wafer with a NH ₄ OH-H ₂ O ₂ solution; 7) washing the wafer with high purity water; and (8) drying the resulting wafer. The method according to claim 1, characterized in that the wafer used in the step (1) is a wafer which has been subjected to mechanical chemical polishing and chemical fine polishing, and has a surface micro-roughness Ra 0.5 nm. The method according to claim 1, characterized in that the concentrated acid used in the steps (1) to (2) is a mineral acid whose concentration is 60% or more of the saturated concentration at the corresponding temperature. The method according to claim 3, characterized in that the inorganic acid is nitric acid or sulfuric acid. The method according to claim 1, characterized in that the steps (1) and (2) are carried out using the same acid. The method according to claim 1, characterized in that the acid concentration C _{1 of the} step (1), the treatment temperature T ₁ and the treatment time P ₁ and the acid concentration C _{2 of the} step (2), the treatment temperature T ₂ and the treatment time The following relationship is satisfied between P ₂ : C ₂ × P ₂ × (T ₂ + 273.15) ≦ C ₁ × P ₁ × (T ₁ + 273.15) ≦ 3 × C ₂ × P ₂ × (T ₂ + 273.15), or more In each formula, the concentration unit is a weight percentage concentration, the treatment temperature is Celsius, and the treatment time is seconds. The method according to claim 1 or 6, characterized by the acid concentration C _{1 of the} step (1), the treatment temperature T ₁ and the treatment time P ₁ , the acid concentration C _{2 of the} step (2), the treatment temperature T ₂ and The following relationship is satisfied between the processing times P ₂ : 500 ≦ C ₁ × P ₁ × (T ₁ + 273.15) ≦ 4,500; and 350 ≦ C ₂ × P ₂ × (T ₂ + 273.15) ≦ 3,000. The method according to claim 1, characterized in that, in the step (4), the organic acid used is citric acid, tartaric acid, maleic acid, fumaric acid, malic acid, gluconic acid, glucoheptonic acid or C3-C12. Polyacid. The method according to claim 8, characterized in that the organic acid is a C3-C10 diacid or citric acid. The method according to claim 1, 8, or 9, characterized in that the organic acid concentration is from 1 to 10% by weight. The method according to claim 1, characterized in that the concentration of the acid in the step (1), the step (2), the treatment temperature, the treatment time, the concentration of the acid C ₄ in the step (4), the treatment temperature T ₄ and the treatment time P ₄ satisfies the following relationship: 1/10 [C ₂ × P ₂ × (T ₂ + 273.15) + C ₁ × P ₁ × (T ₁ + 273.15)] ≦ C ₄ × P ₄ × (T ₄ + 273.15) ≦ 1 /2[C ₂ ×P ₂ ×(T ₂ +273.15)+C ₁ ×P ₁ ×(T ₁ +273.15)], in the above formulas, the concentration unit is the weight percentage concentration, the treatment temperature is Celsius, and the treatment time is second. The method according to claim 1 or 11, characterized in that the acid concentration C ₄ , the treatment temperature T ₄ and the treatment time P ₄ in the step (4) satisfy the following relationship: 100 ≦ C ₄ × P ₄ × (T ₄ + 273.15) ) ≦ 1,200. The method according to claim 1, characterized in that in the step (6), the NH ₄ OH-H ₂ O ₂ aqueous solution is used, the ammonia concentration C ₆ , the treatment temperature T _{6 of the} step (6), and the treatment time P _{6 are} satisfied. The following relationship: 50 ≦C ₆ ×P ₆ ×(T ₆ +273.15) ≦1,000, in the above formulas, the concentration unit is a weight percentage concentration, the treatment temperature is Celsius, and the treatment time is seconds. The method according to claim 13, characterized in that, in the step (6), the ratio of NH ₄ OH to H ₂ O ₂ is preferably from 0.5 to 7.5:1 in terms of percentage by weight. The method of claim 1, wherein the III-V compound semiconductor wafer is an indium phosphide semiconductor wafer. A III-V compound semiconductor wafer prepared according to the method of claim 1, characterized in that: 0.5 particles per square centimeter of wafer surface area greater than 0.11 μm ² , and metal residual Cu ≦ 10×10 on the wafer surface ¹⁰ atoms / cm ² and Zn ≦ ¹⁰ × 10 10 atoms / cm ^2, the average surface value of the fog ≦ 1.0ppm, the surface micro-roughness Ra 0.5 nm. The III-V compound semiconductor wafer according to claim 16, characterized in that the number of particles per square centimeter of the wafer surface area is greater than 0.11 μm ² . The III-V compound semiconductor wafer according to claim 16, characterized in that the metal on the surface of the wafer has a residual Cu ≦ 7 × 10 ¹⁰ atoms/cm ² . The III-V compound semiconductor wafer according to claim 16, characterized in that the metal on the surface of the wafer has a residual Cu ≦ 2 × 10 ¹⁰ atoms/cm ² . The III-V compound semiconductor wafer according to claim 16, characterized in that the metal residue on the surface of the wafer is Zn ≦ 8 × 10 ¹⁰ atoms/cm ² . The III-V compound semiconductor wafer according to claim 16, characterized in that the metal residue on the surface of the wafer is Zn ≦ 3 × 10 ¹⁰ atoms/cm ² . The III-V compound semiconductor wafer according to claim 16, characterized in that the surface average white fog value is ppm0.8 ppm. The III-V compound semiconductor wafer according to claim 16, characterized in that the surface average white fog value is ppm0.7 ppm. The III-V compound semiconductor wafer according to claim 16, characterized in that the surface micro-roughness Ra 0.3 nm. The III-V compound semiconductor wafer according to claim 16, wherein the III-V compound semiconductor wafer is an indium phosphide semiconductor wafer.