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In the semiconductor fabrication processes, ceramic is a vital material used in many types of components and products such as chucks and carriers, wafer polishing substrates, heaters, nozzles, plasma-resistant parts, and electrical feedthrough insulators.
Ceramic, which comes in many forms such as alumina/aluminum oxide and zirconia/zirconium oxide, is often used when resistance to chemicals or corrosion is required and dimensional stability over a range of high temperatures is needed. It is also a good insulator. Moreover, the strength, hardness, toughness, and wear resistance of ceramic can promote part longevity as well.
However, the fabrication of ceramic prototypes can typically have long lead times of 12 to 15 weeks. In the constantly evolving and innovating semiconductor industry, where manufacturers are competing with rivals for the next breakthrough, this kind of delay in prototyping can be a major challenge.
As a result, a growing number of semiconductor manufacturers are partnering with domestic suppliers of ceramic parts that have rapid prototyping capabilities and can turn around product in as little as a few weeks. This allows manufacturers to accommodate multiple design iterations to make improvements before committing to a final design, which helps to optimize the product while minimizing the risk of costly design flaws.
The Many Benefits of Ceramic
Ceramic parts play a vital role in many aspects of semiconductor manufacturing, particularly in vacuum plasma chambers used to clean, etch or activate a dielectric material surface, according to Walt Roloson, R&D Engineering Manager at PVA TePla America, a leading system engineering firm that designs plasma systems.
According to Roloson, while PTFE-coated parts are used in plasma chambers, during the process they can release fluorine, which is very difficult to remove from the chamber even with an oxygen cleaning plasma cycle. “You have to mechanically remove the surface layer because it essentially absorbs the fluorine,” he says.
“A benefit of using ceramic [parts in the chamber] is that it is basically inert, and if plasma breaks down the ceramic does not give off any chemicals, unlike the PTFE,” explains Roloson.
Roloson says that PVA TePla America outsources many of its machinable ceramic parts, and frequently requires prototyping. Due to its insulative properties, ceramic parts are used in PVA TePla’s RF vacuum chambers to ensure no accidental connection between the positive and negative nodes of the system. One example was a ceramic “door pusher” used to automatically close the chamber door. Recently, the company prototyped a ceramic part to isolate the cooling line electrically through the back of the chamber.
Faster Development, Better Product
When the race is on to design and bring to market next generation devices, rapid prototyping can provide a decisive development edge over the competition because it allows more design iterations and improvements in less time.
“Engineers might make changes to their processes, such as an etch pattern with a different configuration, so there might be a number of process efficiency upgrades,” says Jeff Epstein, President of Ceramic Technologies Corp., a Houston-based company that provides advanced ceramic material solutions to a variety of industries including semiconductor. “That is why it is important for prototypes to be delivered in a matter of weeks, rather than months.”
The size of the ceramic manufacturer, it turns out, often plays a significant role in the speed of responsiveness to prototype requests. Large ceramic manufacturers often fit in small prototype orders whenever it can be squeezed into the scheduling. This typically relegates small orders to the back of the line, and contributes to the time taken to deliver the product. In contrast, a smaller, more nimble, domestic ceramic manufacturer has the ability to prioritize prototypes.
As an example, Epstein’s company provides rapid prototyping and material expertise to the semiconductor industry for ceramic products such as vacuum chucks, wafer clamps, lift pins, insulation boards, and alumina end effectors.
These products can be manufactured using isostatic pressing and sintering techniques to produce high quality, fully dense parts often in 3 to 4-week timeframes without a tooling fee. Ceramic parts can also be machined out of plates, rods or tubes.
According to Epstein, knowing which ceramic material to use, and at what level of purity, is also a critical consideration. “High purity 99.8% alumina is designed to withstand the extreme plasma edge environment, including vapor phase etchants, high RF voltage, microwave plasma, and aggressive cleaning methods,” says Epstein. “It offers excellent heat resistance, wear resistance, plasma resistance, and low dust generation.”
Also known as aluminum oxide, the material is almost a given in the industry and far superior to a metal, which would typically corrode very quickly in an acid environment where etching is involved.
“Compared to other ceramics, alumina/aluminum oxide is the lowest cost with one of the highest hardness properties,” says Epstein. “Alumina is gas-tight with no open porosity. It is diamond ground to achieve polished surface finishes.” He notes that alumina/ aluminum oxide is also commonly used as an electrical insulator.
However, for strength and toughness to protect a product in a rough, external environment, Epstein recommends zirconia/zirconium oxide. “Zirconia is the toughest ceramic commercially available,” says Epstein. This high-strength material exhibits excellent wear and corrosion properties.”
No matter which ceramic material is selected, it is vital that the supplier can provide consulting and help when required. For example, Ceramic Technologies, which has over three decades of field experience, provides ceramic design assistance as needed. “The engineer will come up with a design, and we might suggest some modifications if they have internal threads, for instance,” says Epstein.
With the market demanding ever greater innovation in shorter timeframes, semiconductor manufacturers will find that partnering with a domestic supplier with rapid prototyping capability can provide them an advantage against industry rivals.