Methods for polishing semiconductor materials, polishing fluid for polishing gallium antimonide substrates

The content of this paper is extracted from the invention patent application documents of Suzhou Kun Yuan Photoelectric Co., LTD.
(54) Name of the invention
Methods for polishing semiconductor materials, polishing fluid for polishing gallium antimonide substrates
(57) Abstract
The invention provides a polishing method for semiconductor materials and a polishing liquid for gallium antimonide substrate, aiming at the shortcomings that polishing abrines and metal ions contained in polishing liquid are easy to adhere to the surface of the polished material when polishing soft semiconductor materials such as gallium antimonide and other soft semiconductor materials by using the prior art CMP process, which may cause scratches on the surface of the polished material and low life of the polishing liquid. Method is the Mohs hardness of 1.5-6 semiconductor material polishing, the first step is rough polishing, using a hard abrasive polishing liquid on the semiconductor material substrate sheet for mechanical polishing, the second step is polishing, polishing liquid including soft polishing abrasives, weak acidic oxidants, organic acids, hydrophilic non-ionic surfactants, deionized water; The third step is fine polishing. The fine polishing liquid includes weak acidic oxidant, organic acid and deionized water. The polishing method of the invention is used to polish the semiconductor material, eliminate the pits and scratches, reduce the pits, and obtain the material with good surface roughness.
[0066] Example 1
[0067] Gnad41 lapping and polishing machine was used for polishing.
[0068] The technological process of gallium antimonide substrate sheet includes lapping, chamfering, polishing and cleaning, and the invention mainly describes the polishing process.
[0069] First remove the line marks on the surface of gallium antimonide wire cut sheet, grinding it to the thickness required by the process, grinding in general single-side removal thickness of 40 50um; Then the polished gallium antimonide wafer is cleaned with cleaning agent and ultrasonic wave to ensure that the surface is free of particles produced by gallium antimonide grinding; The φ50.8 ± 0.5mm gallium antimonide wafer is evenly pasted on the quartz carrier plate by heating 60-80℃ with solid paraffin wax to cool and compact, to ensure that TTV≤2-3um, to ensure that the total thickness deviation accuracy of subsequent polishing is within the controllable range. Wipe off the excess paraffin wax on the quartz tray, around the wafer and on the surface of the wafer with a dustless cloth and isopropyl alcohol (IPA) or anhydrous ethanol to prevent paraffin from contaminating the polishing pad during polishing, and then rinse off with deionized water. Then the polishing process begins.
[0070] Step 1 Rough polishing: Rough polishing adopts polyurethane polishing pad, polishing liquid contains alumina abrasive with particle size of 3um, pressure of 60g/cm2, speed of 40rpm, roller pump non-circulating drops (vacuum extrusion) to supply polishing liquid. Instruction Manual Page 7/19 10CN 112701037 A10 Flow 80ml/min. The polishing liquid used for rough polishing is composed of the following components in percentage by volume: 10% alumina abrasive with 3um particle size; Hydrophilic nonionic surfactant fatty alcohol polyoxyethylene ether 0.5 %; Deionized water 89.5%;
[0071] The second step of middle polishing: polyurethane polishing pad is adopted in the middle polishing. The polishing liquid contains silicon dioxide nano abrasive with particle size of 60nm and hypochlorous acid. The pressure is 100g/cm2 and the rotation speed is 80rpm. The polishing liquid used in Chinese polishing is composed of the following components according to the percentage of volume: 60nm particle size silica 20%; The organic acid was 0.1% citric acid. Hypochlorous acid 7% as oxidant; Hydrophilic nonionic surfactant fatty alcohol polyoxyethylene ether 0.5 %; Deionized water 72.4 percent; The ratio of polishing liquid PH is 4.5.
[0072] Step 3 Fine polishing: Fine polishing adopts the polishing cloth with fluff synthetic leather, the polishing liquid is non-abrasive polishing liquid, the pressure is 50g/cm2, the speed is 50rpm, the polishing liquid is supplied by roller pump non-circulating drop (vacuum extrusion), the flow rate is 10ml/min. The polishing liquid used in fine polishing is composed of the following components according to the percentage of volume: hypochlorous acid is used as the oxidant 1. 5%; The organic acid was 0.5% citric acid. Deionized water 98%; PH of the ratio of polishing liquid is 4.5;
[0073] After chemical-mechanical polishing, gallium antimonide wafers on the quartz discs are quickly sprayed with deionized water to prevent oxidation and further remove particulate contaminants, followed by appropriate waxing, cleaning, and drying processes.
[0074] Gallium antimonide wafers polished in this embodiment are tested as follows:
[0075] The polished gallium antimonide wafer is subjected to eye inspection under strong light, showing no surface scratches, polishing fog or edge breakage defects.
[0076] The polished gallium antimonide wafer was examined by metallographic microscope. When the dark field was 100 times, no bright spots or scratches were observed on the surface of the wafer. When the bright field was 100, 200, 500 times, no pits, no pits, no orange peel or scratches were observed on the surface of the wafer, and the surface matrix was very flat. See Figure 1 attached. Note that the bright spot in the visual field in this image is the particle pollutant, not the pit, which is caused by the particle pollutant not cleaned during cleaning or environmental factors during testing.
[0077] The polished gallium antimonide wafers were tested by surfscan6200 particle size detector, 52 particles /cm2 within the detection range of G6; Better than the usual 100 200 particles /cm2. See attached figure 3.
[0078] The roughness Ra of the polished gallium antimonide wafer is tested by AFM, the scanning range is 10um*10um, and the detection value is Ra = 0.19nm, RMS = 0.472nm. See Figure 5 attached.