CN110314896A - A kind of semiconductor substrate materials polishing method - Google Patents

Abstract

The invention relates to a semiconductor substrate material polishing method, which belongs to the technical field of semiconductor material polishing. The polishing method of the present invention includes: laser polishing the semiconductor substrate material after wire cutting; ultrasonic cleaning the semiconductor substrate material after laser polishing to complete the laser polishing treatment; using chemical mechanical polishing to process the semiconductor substrate completed in the previous steps Material. In the polishing method of the present invention, laser polishing can efficiently remove surface damage and form structures and components that are beneficial to chemical mechanical polishing. At the same time, since laser polishing is non-contact polishing, no new mechanical damage will be generated, and chemical mechanical polishing in the next step It takes only 0.1‑5 hours to obtain an ultra-precision polished surface. All the processing steps of the invention can be completed in commercial equipment, which is easy to implement and has good application prospects.

Description

A kind of semiconductor substrate material polishing method

technical field

The invention relates to a semiconductor substrate material polishing method, which belongs to the technical field of semiconductor substrate material polishing, in particular to the technical field of ultra-precision polishing for hard-to-process substrate materials such as superhard materials and brittle materials.

Background technique

Traditional semiconductor substrate material processing is divided into steps such as crystal growth, wire cutting, precision machining, and cleaning. The precision machining step is used to remove defects such as damaged layers and surface unevenness caused by the cutting process, and significantly reduce surface stress and roughness. Thus, atomic-scale surfaces are obtained. At present, precision machining includes grinding, mechanical polishing, chemical mechanical polishing and other steps, and the processing technology is cumbersome. Especially for difficult-to-process substrate materials such as superhard materials and brittle materials, new defects will be generated in grinding and mechanical polishing, which will not only cause low efficiency. For example, the removal rate of superhard material silicon carbide chemical mechanical polishing is only about 100nm/h ( JMater Sci: Mater Electron (2013) 24:5040–5047), brittle materials are prone to fragmentation during processing, which brings great challenges to chemical mechanical polishing.

In order to improve efficiency and reduce surface defects, patent CN 107346726 A first immerses and removes the original substrate, and then performs polishing treatment; patent CN 107993936 A performs an etching process on the sliced substrate to remove the damaged layer generated by the slice; Patent CN103624675 B solidifies the abrasive into the polishing pad to reduce the damage caused by grinding and simplifies the substrate processing steps. It can be seen that the efficiency can be improved or surface defects can be reduced by changing the processing method. However, the above-mentioned patents only improve one step in substrate processing, and do not increase the rate of chemical mechanical polishing.

Contents of the invention

The object of the present invention is to overcome the deficiencies in the prior art, and proposes a semiconductor substrate material polishing method, which can quickly remove the surface damage layer, undulations, etc. The surface structure and composition of mechanical polishing greatly improve the efficiency of chemical mechanical polishing. This method can change the processing steps of the traditional substrate material: the cut substrate material only needs two steps of laser polishing and chemical mechanical polishing to obtain an ultra-precision surface, with short processing time and high efficiency.

A kind of semiconductor substrate material polishing method of the present invention is characterized in that, the method comprises the following steps:

(a) laser polishing the semiconductor substrate material after wire cutting;

(b) Ultrasonic cleaning is performed on the semiconductor substrate material after laser polishing to complete the laser polishing process;

(c) The semiconductor substrate material completed in step (b) by chemical mechanical polishing.

The semiconductor substrate material includes sapphire, gallium arsenide, silicon carbide, gallium nitride, diamond, aluminum nitride, indium nitride, silicon, and zinc oxide.

The medium used for the ultrasonic cleaning is water or ethanol, and the cleaning time is 1-10 minutes.

The laser polishing method includes any one of excimer laser polishing, CO ₂ laser polishing, YAG laser polishing, nanosecond laser polishing, picosecond laser polishing, and femtosecond laser polishing.

The speed of the laser scanning is 1 mm/s˜500 mm/s.

The energy density of the laser scanning is 0.01J/cm ² -20J/cm ² .

The polishing fluid used in the chemical mechanical polishing is one or more of alumina polishing fluid, cerium oxide polishing fluid and silicon oxide polishing fluid.

The polishing pad is one or more of polyurethane polishing pads, non-woven polishing pads, and composite polishing pads.

The polishing liquid is one or more of acidic, neutral and alkaline.

The pressure used for chemical mechanical polishing is 50g/cm ² -400g/cm ² , and the polishing time is 0.1-5 hours.

Compared with the prior art, the present invention has the following advantages:

1. Reduce the processing steps of traditional sinking bottom materials, and the cut substrate materials only need two steps of laser polishing and chemical mechanical polishing to obtain ultra-precision surfaces;

2. The laser polishing time is short, and it only takes a few minutes to ten minutes to quickly remove the surface damage layer, fluctuations, etc. without generating new defects;

3. After laser polishing, the surface structure and composition that are easy to chemical mechanical polishing can be generated, which can greatly improve the efficiency of chemical mechanical polishing;

4. All the machines used are commercial machines, and the polishing process is within the settable range of commercial polishing machines, and the operation is simple and easy to implement;

5. The entire polishing process takes a short time, and it only takes 0.1 to 5 hours to complete the polishing for difficult-to-process materials;

Description of drawings

FIG. 1 is a microscopic view of the surface of a silicon carbide substrate after polishing in Example 4 of the present invention.

Fig. 2 is a microscope image of the polished silicon carbide substrate surface in Comparative Example 1.

Detailed ways

In order to further explain the technical problems solved by the present invention and the effects produced, the present invention will be described in detail below in conjunction with specific embodiments. The specific embodiments described here are only used to explain the content of the present invention, and are not intended to limit the present invention.

Embodiment one

The silicon carbide substrate surface after wire cutting is polished by IPG’s GYLPM nanosecond laser: the laser scanning speed is 1mm/s, and the laser energy density used is 1J/cm ² ; after the scanning is completed, put it in ethanol for ultrasonic cleaning for 5 minutes ; The cleaned silicon carbide substrate was polished for 3 hours with a 1000S polishing machine from Shenyang Kejing Company, an alkaline alumina polishing solution, and a polyurethane polishing pad at a polishing pressure of 400 g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Embodiment two

ULR50 type _CO2 laser from Universal Company was used to polish the silicon carbide substrate surface after wire cutting: the laser scanning speed was 250mm/s, and the laser energy density used was 0.01J/ ^cm2 ; after the scanning was completed, put it in ethanol for ultrasonic cleaning for 1 Minutes; the cleaned silicon carbide substrate was polished for 1 hour with a 1000S polishing machine from Shenyang Kejing Company, an alkaline cerium oxide polishing solution, and a composite polishing pad at a polishing pressure of 100 g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Embodiment three

Use the PH1 femtosecond laser of LIGHTCINVERSION company to polish the surface of the silicon carbide substrate after wire cutting: the laser scanning speed is 500mm/s, and the laser energy density used is 20J/ ^cm2 ; after the scanning is completed, put it in water for ultrasonic cleaning for 10 minutes; The cleaned silicon carbide substrate was polished for 5 hours with a 1000S polishing machine from Shenyang Kejing Company, an acidic silicon oxide polishing solution, and a polyurethane polishing pad at a polishing pressure of 300 g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Embodiment Four

Use LIGHTCINVERSION's PH1 femtosecond laser to polish the surface of the silicon carbide substrate after wire cutting: the laser scanning speed is 50mm/s, and the laser energy density used is 1J/ ^cm2 ; after the scanning is completed, put it in ethanol and ultrasonically clean it for 10 minutes ; The cleaned silicon carbide substrate was polished for 5 hours with a 1000S polishing machine from Shenyang Kejing Company, an alkaline silicon oxide polishing solution, and a non-woven polishing pad at a polishing pressure of 400 g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Embodiment five

Adopt the PH1 type femtosecond laser of LIGHTCINVERSION Company to polish the surface of the diamond substrate: the laser scanning speed is 200mm/s, and the laser energy density used is 10J/ ^cm2 ; after the scanning is completed, put it in ethanol for ultrasonic cleaning for 5 minutes; The silicon carbide substrate was polished for 3 hours using a 1000S polishing machine from Shenyang Kejing Company, an acidic silicon oxide polishing solution, and a polyurethane polishing pad, with a polishing pressure of 400g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Embodiment six

Use the PH1 femtosecond laser of LIGHTCINVERSION Company to polish the surface of the zinc oxide substrate: the laser scanning speed is 300mm/s, and the laser energy density used is 0.05J/ ^cm2 ; after the scanning is completed, put it in ethanol for ultrasonic cleaning for 1 minute; The final silicon carbide substrate was polished for 0.1 hour with a 1000S polishing machine from Shenyang Kejing Company, a neutral silicon oxide polishing solution, and a composite polishing pad, with a polishing pressure of 50 g/cm ² . After polishing, a Leica microscope was used to observe the surface of the polished silicon carbide material, and it was found that the surface damage had been completely removed.

Comparative example one

The wire-cut silicon carbide substrate is processed according to the traditional process: firstly, it is ground with diamond abrasive liquid to remove the knife marks on the surface of the substrate material. After grinding for 30 minutes, it is found under the microscope that the surface knife marks have been completely removed, but there are More deep scratches; the substrate material after grinding was polished for 3 hours according to the chemical mechanical polishing conditions in Example 1 using Shenyang Kejing Company 1000S polishing machine and alkaline alumina polishing solution, and it was observed under a microscope that the lining The scratches on the surface of the substrate material were significantly shallower and reduced; the substrate material polished with the alumina polishing solution was polished for 5 hours according to the chemical mechanical polishing conditions in Example 4, and it was observed under a microscope that scratches still existed on the surface of the substrate material.

Comparative example two

The wire-cut silicon carbide substrate was polished according to the chemical mechanical polishing conditions in Example 4, and the surface was observed under a microscope every 1 hour. After polishing for 10 hours, it was found that there were still defects such as line marks and pits on the surface.

Claims (10)

1. a kind of semiconductor substrate materials polishing method, which is characterized in that method includes the following steps:

(a) semiconductor substrate materials after cutting line carry out laser polishing；

(b) ultrasonic cleaning is carried out to the semiconductor substrate materials after laser polishing, completes laser polishing processing；

(c) semiconductor substrate materials completed using chemical mechanical polish process step (b).

2. semiconductor substrate materials polishing method according to claim 1, which is characterized in that the semiconductor substrate materials Including sapphire, GaAs, silicon carbide, gallium nitride, diamond, aluminium nitride, indium nitride, silicon, zinc oxide.

3. semiconductor substrate materials polishing method according to claim 1, which is characterized in that used in the ultrasonic cleaning Medium be water or ethyl alcohol, scavenging period be 1~10 minute.

4. semiconductor substrate materials polishing method according to claim 1 or 2, which is characterized in that the laser polishing Method includes excimer laser polishing, CO₂Laser polishing, YAG laser polishing, nanosecond laser polishing, picosecond laser polishing, femtosecond Any one of laser polishing.

5. semiconductor substrate materials polishing method according to claim 1 or 4, which is characterized in that the laser scanning Speed be 1mm/s~500mm/s.

6. semiconductor substrate materials polishing method according to claim 1 or 4, which is characterized in that the laser scanning Energy density be 0.01J/cm²~20J/cm²。

7. semiconductor substrate materials polishing method according to claim 1, which is characterized in that the chemically mechanical polishing makes Polishing fluid is one or more of alumina polishing solution, cerium oxide polishing slurry, silica polishing fluid.

8. semiconductor substrate materials polishing method according to claim 1, which is characterized in that the polishing pad is polyurethane One or more of polishing pad, non-woven fabrics polishing pad, compound polishing pad.

9. semiconductor substrate materials polishing method according to claim 8, which is characterized in that the polishing fluid be it is acid, One or more of neutral, alkalinity.

10. semiconductor substrate materials polishing method according to claim 8, which is characterized in that chemically mechanical polishing is made It is 50g/cm with pressure²~400g/cm², polishing time is 0.1~5 hour.