The wafer manufacturing process consists of seven independent processes: lithography, etching, film growth, diffusion, ion implantation, chemical-mechanical polishing, and metallization. As one of the key process processes of wafer manufacturing, chemical mechanical polishing (CMP) refers to the efficient removal of excess materials on the wafer surface and the global nano level flattening through the cooperative action of chemical corrosion and mechanical grinding.

In 2018, the global market size of CMP equipment was 1.842 billion US dollars, accounting for about 4% of the market share of wafer manufacturing equipment, of which the Chinese mainland CMP equipment market size was 459 million US dollars.

A must for wafer flattening

CMP, the full name of Chemical Mechanical Polishing, is one of the key techniques for semiconductor wafer surface polishing. Chemical mechanical polishing technology is used many times in the manufacturing process of monocrystalline silicon wafer and the first half process. Compared with the previously commonly used mechanical polishing, chemical mechanical polishing can make the surface of the silicon wafer flatter, and also has the advantages of low processing cost and simple processing method, so it has become the most common surface leveling technology for semiconductor materials.

Because the integrated circuit components generally use multi-layer three-dimensional wiring, the front process of integrated circuit manufacturing needs to carry out multi-layer cycle. In this process, the wafer surface needs to be flattened by the CMP process. Integrated circuit manufacturing is the most important application scenario of CMP equipment, which is reused after film deposition and before the lithography process.

CMP equipment is the only way to wafer flattening. Its working process is: the polishing head presses the wafer surface to be polished on the rough polishing pad, and realizes global flattening with the coupling of polishing liquid corrosion, particle friction and polishing pad friction. The polishing disc drives the polishing pad to rotate and achieves real-time thickness measurement with 3-10nm resolution to prevent overpolishing through the grinding of different materials and thicknesses by an advanced endpoint detection system.

The more critical technology is the globally zoned pressure polishing head, which can achieve ultra-precision controllable unidirectional pressure on multiple annular regions of the wafer in a limited space, so that the pressure can be adjusted in response to the film thickness data measured by the polishing disc to control the polishing morphology of the wafer, so that the polished surface of the wafer can reach ultra-high smoothness, and the surface roughness is less than 0.5nm. This is equivalent to one in 100,000 pieces of human hair.

Unlike semiconductor devices such as lithography and etching machines, CMP devices are less affected by Moore's Law, there is no technology iteration cycle in a longer period of time, and there is no significant difference in CMP devices applied to 28nm and 14nm, only the optimization of specific module technologies. However, as the CMP process continues to advance from 14nm to 7nm, 5nm, and 3nm advanced processes, CMP technology will continue to develop in the direction of polishing head zoning refinement, intelligent process control, and multi-energy combination of cleaning units.

Patents are a blessing to the first, and a curse to the next. After 2013, the number of CMP patent applications increased slowly, while the number of post-CMP washing patent applications declined. The overall number of global CMP patent applications has remained stable, reflecting that there is no major technological innovation in the current global CMP technology, and latecomers must face strong patent barriers if they want to catch up.

Chinese companies caught between the giants

In 2017, the global CMP equipment market size of $1.75 billion, of which Applied Materials (AMAT) $1.24 billion, Japan's EBARA (EBARA) $470 million, the calculation of applied Materials share of 71.3%, Japan's Ebara share of 26.7%, the two combined accounted for more than 90% of the global CMP market share.

Applied Materials (AMAT) is one of the world's largest suppliers of semiconductor equipment, covering semiconductor equipment, solar energy, displays, automation software, roll-to-roll vacuum coating and other fields. In the semiconductor equipment segment, the company developed a PPACt strategy aimed at driving innovation in chip energy efficiency, performance, area, cost and time to market through parallel rather than serial innovation.

The company's products cover deposition, etching, doping, CMP multi-process links. In 2020, the global market share of applied materials in etching, deposition, CMP, ion implantation, and process control will reach 17%, 43%, 64%, 55%, and 12%, respectively.

Founded in 1912, Ebara is a pioneer of dry-in/dry-out patents in the field of CMP, independently developed 200 mm and 300mm CMP polishing equipment with high reliability and high productivity. The F-REX series CMP system enables surface roughness control at 10-20nm nodes for oxide, ILD, STI, tungsten and copper surface treatments for IC manufacturing. With excellent reliability and performance over 250 hours of MTBF, the F-REX200 tool represents the latest CMP technology for 200mm wafers (150 mm is also available).

The high-end segment of the domestic CMP market is still mainly dependent on imports, and the CMP equipment used in large production lines with the most advanced process processes below 14nm is provided only by two international giants, Applied Materials in the United States and Ebara in Japan. Applied materials and Ebara Japan have respectively achieved 5nm process and some materials 5nm process applications; However, in the field of mature process, domestic enterprises represented by Huahai Qingke have broken the perennial monopoly situation of foreign giants, and have occupied an important share in the domestic CMP market.

Huahai Qingke was established in 2013, is a high-tech enterprise established by Tianjin Municipal Government and Tsinghua University to implement the national strategy of "Beijing-Tianjin-Hebei integration" and promote the industrialization of chemical mechanical polishing (CMP) technology and equipment in China. In January 2018, Huahai Qingke's Cu&Si CMP equipment entered Shanghai Huali, marking the first domestic 12-inch copper process CMP equipment officially entered the integrated circuit production line. From 2018 to 2020, the share of Huahai Qing in the domestic CMP market was 1.05%, 6.15% and 12.64%, respectively.

CMP includes three polishing processes, the main materials used include polishing pad, polishing fluid, wax, ceramic sheet, etc. Different processes require different polishing pressure, polishing liquid composition, pH value, polishing pad material, structure and hardness according to different purposes. CMP polishing fluid and CMP polishing pad are the core elements of CMP process, and their properties affect the surface polishing quality.

The main polishing liquid suppliers include Japan Fujimi, Japan HinomotoKenmazai, the United States Cabot, DuPont, Rodel, Eka, South Korea ACE and other companies, accounting for more than 90% of the global market share, the domestic market is mainly dependent on imports, only some domestic enterprises can produce, But it also reflects the gradual technological breakthrough in China and the huge import substitution market.

As one of the key process equipment in the semiconductor manufacturing process, CMP equipment will continue to benefit from downstream expansion and domestic replacement process, but we must also see the difficulties, but one thing is certain, as long as the company can break foreign monopolies, then orders and performance are guaranteed.