Ground sapphire substrate slice boron carbide cleaning method

A technology of sapphire substrate and boron carbide, applied in the direction of cleaning methods using liquids, cleaning methods and utensils, chemical instruments and methods, etc.

Inactive Publication Date: 2019-12-20

江苏吉星新材料有限公司

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AI-Extracted Technical Summary

Problems solved by technology

[0003] In view of the defects of the existing cleaning process after boron carbide grinding of sapphire substrates, the present invention provides a cleaning method for boron carbide grinding of sapphire substrates, and different cleaning processes and p...

Method used

By activator to the wrapping of wafer surface boron carbide, boron carbide particle is separated with wafer; Then by the physical grinding effect of damping cloth and wafer, the activator of wrapping boron carbide particle is peel...

Abstract

The invention discloses a ground sapphire substrate slice boron carbide cleaning method. The method specifically comprises the steps of (1) conducting pure water ultrasonic cleaning to remove big-particle-size boron carbide micro powder adhering to the surfaces of wafers; (2) conducting low-frequency ultrasonic cleaning through cleaning fluid to remove big-particle-size boron carbide micro powderadhering to the surfaces of the wafers; (3) conducting physical grinding in the cleaning fluid to remove medium-particle-size boron carbide micro powder adhering to the surfaces of wafers; (4) conducting high-frequency ultrasonic cleaning through the cleaning fluid to remove small-particle-size boron carbide micro powder inlaid on the surfaces of the wafers; and (5) conducting acid corrosion to roughen the surfaces to remove tiny boron carbide micro powder on the surfaces of the wafers. According to the ground sapphire substrate slice boron carbide cleaning method provided by the invention, different cleaning processes and procedures are designed for different particle sizes of boron carbide micro powder to achieve the purpose of completely removing the boron carbide micro powder on the surfaces of the wafers. The ground sapphire substrate slice boron carbide cleaning method has the advantages of short technological process and high one-time yield. The abnormal problems that the cleaning yield is low and the quality is poor through a traditional process are solved.

Application Domain

Polishing machinesLapping machines +2

Technology Topic

Acid corrosionSmall particle +4

Examples

Experimental program(1)

Example Embodiment

[0024] Example 1

[0025] A cleaning method for sapphire substrate after boron carbide grinding, the specific steps are as follows:

[0026] (1) Insert the 4-inch wafers (400 pieces) that have been ground by boron carbide into the cassette, soak them in 18M pure water, and wait for cleaning.

[0027] (2) Ultrasonic removal of boron carbide particles attached to the wafer surface with pure water: put the wafer box into a stainless steel tank with pure water at 60°C, and take it out after ultrasonic cleaning for 10 minutes (ultrasonic frequency is 28KHz, ultrasonic intensity is 0.3V).

[0028] (3) Removal of large particles of boron carbide (particle size: 40-70 μm) by low-frequency ultrasonic: prepare a cleaning agent solution with a concentration of 1% in a stainless steel tank, heat it to 65 ° C, place the wafer in the solution, ultrasonic (ultrasonic frequency is 28KHz) , ultrasonic intensity is 0.3V) cleaning for 10min, take out.

[0029] The main components of the cleaning agent solution are nonionic and anionic compound active agents and dispersants, specifically 1:1 ratio of fatty alcohol polyoxyethylene ether and sodium dodecylbenzenesulfonate and a trace amount of organic dispersants. same.

[0030] The active agent penetrates into the surface of the wafer, wraps the boron carbide particles, changes the contact angle of the wafer surface, reduces the adhesion between the boron carbide particles and the wafer surface, separates the boron carbide particles from the wafer surface, and uses 28KHz ultrasonic cleaning. It separates the larger particles of boron carbide micropowder on the surface of the wafer from the wafer to achieve the purpose of cleaning.

[0031] (4) Physical removal of boron carbide particles (particle size 10-40 μm): use a double-sided polishing machine with black damping cloth, insert the wafer into the star wheel, put it into a double polishing machine, and use 1% concentration of The cleaning agent solution is used as the circulating fluid, and the pressure is set to 30g/cm 2 , the speed is set to 30rpm, the wafer is taken out after grinding for 5min, and rinsed with pure water.

[0032] The boron carbide particles are separated from the wafer by the activating agent wrapping the boron carbide on the surface of the wafer; and then through the physical grinding action between the damping cloth and the wafer, the activating agent wrapping the boron carbide particles is peeled off from the wafer surface to achieve the purpose of removing boron carbide. . The damping cloth is mainly used because the damping cloth is a velvet-like material on the surface, and the texture is delicate and soft, and it is not easy to scratch the wafer.

[0033] (5) High-frequency ultrasonic removal of small boron carbide particles (particle size 0.3-10 μm): prepare a cleaning agent solution with a concentration of 1% in a stainless steel tank, heat it to 65 ° C, place the wafer in the solution, ultrasonic (ultrasonic frequency is 40KHz, ultrasonic intensity is 0.2V) cleaning for 10min, take out and rinse with pure water. Remove boron carbide fine powder with smaller particle size on the wafer surface.

[0034] (6) Removal of small particle size boron carbide (particle size <0.3μm) by acidizing corrosion: configure 1:1 phosphorus-sulfur mixed acid (85% analytically pure phosphoric acid and 98% analytically pure sulfuric acid), heat to 140°C, place in acid In the washing box, pour the wafer into the pickling box, soak it for 5 minutes, take it out, rinse it with pure water, and brush it dry.

[0035] The strong oxidizing and dehydrating properties of sulfuric acid can remove the cleaning liquid and organic residues on the surface of the wafer, and eliminate the protective oxide film on the surface of the wafer.

[0036] (7) Heat treatment of the wafer: The boron carbide particles on the surface of the wafer can be removed through the above steps, and the wafer can be subjected to high temperature heat treatment.

[0037] (8) Visual inspection and yield:

[0038] ①Appearance inspection before annealing: The surface of the wafer is white, without black oil and white spots.

[0039] ②Appearance inspection after annealing: the surface of the wafer is white, without black oil and white spots.

[0040] ③ Yield rate: 400 pieces were put in, 400 pieces were qualified, and the qualified rate was 100%.

PUM

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