Semiconductor Chemicals and Materials Market
Chemicals are used in a variety of processes in semiconductor manufacturing. All are used in IC manufacturing to varying degrees depending on the type of device architecture, cleaning-process chemistry and frequency of use, etching-process chemistry, method of thin film deposition, use of wet or dry etching, use of wet-etching machines (cassette-to-cassette, automatic processing) or wet etching systems (dip tanks), size of wafers, and number of wafer starts.
Suppliers of semiconductor chemicals and materials are focusing on reducing the impurity levels of their products. “Electronic” and “Semiconductor” grade gases are available with low concentrations of cations and anions that could degrade device performance. Transition metal impurities, for example, are fast diffusers and readily move into the silicon wafer lattice during high-temperature processing, replacing silicon ions at lattice sites and changing the bandgap of the silicon. These new sites act as a generation-recombination center and result in a decrease in the minority carrier lifetimes and leakage currents at p-n junctions.
A critical concern has emerged as the suppliers have improved the purity of the delivered product — consistency. The manufacturing of devices at adequate yields has become dependent on minimizing process variances. The current purity of gases has now reached a threshold where subsequent deterioration or improvement of purity, even in a single trace element, can upset the yield. The fact that improvement in purity can be viewed as a negative has been somewhat ironic to the suppliers.
Most users continue to ask suppliers for higher and higher chemical purity. At the present time the supplier specifications represent product purity that is satisfactory for most manufacturing processes and that is commercially available at prices that are acceptable to users.
Higher purity chemicals could be offered but would require additional processing such as distillation, chemical treatment or even drastic modifications in the basic manufacturing procedures. Many basic chemical producers have already made improvements in their manufacturing facilities to accommodate the semiconductor industry and its chemical suppliers. Individual company specifications make it necessary for suppliers to do lot selection or extra analytical work and this can escalate the selling price of the chemicals. Also, it causes shipping delays since the supplier usually cannot ship his regular product from existing inventory.
Obviously these basic changes would change the cost structure and ultimately increase the selling price to users. These price increases could be dramatic.
It is well known that the yields in Japanese IC manufacturing facilities are higher than in the United States. This is related to two major factors; the increased use of automation in Japan, and the decreased contamination levels due to the integrity of their Class 1 and 10 cleanrooms, their attitude to quality, and their processing chemicals. U.S. semiconductor manufacturers must adopt these practices in order to remain competitive with the Japanese. A major effort must be directed towards chemical manufacturers to supply chemicals with as high a purity and as low a particulate level as possible. This must also be achieved at as low a cost as possible.
IC manufacturers are installing chemical distribution systems in their new facilities. Chemicals are piped into wafer fab cleanrooms after delivery to the facility in bulk containers. This method totally eliminates the need for bottles. A continual pipeline of chemicals from the supplier to wafer has been developed, utilizing fluoropolymer piping, baths, and wafer carriers. Fluoropolymer tubing and piping, pumped by fluoropolymer pumps, and filtered in fluoropolymer filter housings with replaceable fluoropolymer filters make up the purest method of handling chemicals for tomorrow’s purity demands. All of these components are available in Teflon for the most critical applications.
The use of direct piping systems or any dispensing hardware will usually require extensive retrofitting of existing fabrication areas and can be costly. However, savings on product cost and handling can sometimes easily justify these changes. Needless to say, yield improvements which are often possible, would be an even stronger justification. A typical system price breakdown is:
- 40% – Equipment and components such as piping, tanks, pumps, filters, and valves
- 14% – Automated control system including interface to host computer over a LAN, hardware, and software
- 46% – Labor including installation, engineering, test, inspection, and project overhead costs
The quality of semiconductor chemicals and materials entering the fab area should be the most important concern of personnel in a semiconductor manufacturing facility. In order to undertake proper evaluation of chemicals and their suppliers, a total awareness program must be initiated in the facility. To achieve this goal, the primary requirement must be a commitment by management that personnel and monetary resources are dedicated to the purity issue regardless of cost.
The more extensive the quality control program within a facility, the more confidence that can be placed in the analytical results. These results can only be at the confidence level of the personnel, equipment, and testing methods. These methods should be subjected to rigorous quality control methods, including calibration on a biannual basis.
For more information, table of contents, and ordering details, please view the report: Chemicals And Materials For Sub-100nm IC Manufacturing.