Abstract: Numerous studies suggest that the current popular designs of coronary stents are functionally equivalent and suffer a 16 to 22 percent rate of restenosis. Although the use of coronary stents is growing, the benefits of their use remain controversial in certain clinical situations or indications due to their potential complications. The application of gas cluster ion beam (GCIB) surface modification such as smoothing or cleaning appears to reduce these complications and lead to genuine cost savings and an improvement in patient quality of life. The present invention is directed to the use of GCIB surface modification to overcome prior problems of thrombosis and restenosis. The atomic level surface smoothing of stents utilizing GCIB substantially reduces undesirable surface micro-roughness in medical coronary stents.
Type:
Grant
Filed:
July 9, 2001
Date of Patent:
January 13, 2004
Assignee:
Epion Corporation
Inventors:
Allen R. Kirkpatrick, Robert K. Becker, Avrum Freytsis
Abstract: Physical vapor deposition processes provide optical materials with controlled and uniform refractive index that meet the requirements for active and passive planar optical devices. All processes use radio frequency (RF) sputtering with a wide area target, larger in area than the substrate on which material is deposited, and uniform plasma conditions which provide uniform target erosion. In addition, a second RF frequency can be applied to the sputtering target and RF power can be applied to the substrate producing substrate bias. Multiple approaches for controlling refractive index are provided. The present RF sputtering methods for material deposition and refractive index control are combined with processes commonly used in semiconductor fabrication to produce planar optical devices such surface ridge devices, buried ridge devices and buried trench devices. A method for forming composite wide area targets from multiple tiles is also provided.
Type:
Grant
Filed:
July 10, 2001
Date of Patent:
January 14, 2003
Assignee:
Symmorphix, Inc.
Inventors:
Richard E. Demaray, Kai-An Wang, Ravi B. Mullapudi, Douglas P. Stadtler, Hongmei Zhang, Rajiv Pethe
Abstract: The present invention is related to methods and apparatus for processing weak ferroelectric films on semiconductor substrates, including relatively large substrates, e.g., with 300 millimeter diameter. A ferroelectric film of zinc oxide (ZnO) doped with lithium (Li) and/or magnesium (Mg) is deposited on a substrate in a plasma assisted chemical vapor deposition process such as an electron cyclotron resonance chemical vapor deposition (ECR CVD) process. Zinc is introduced to a chamber through a zinc precursor in a vaporizer. Microwave energy ionizes zinc and oxygen in the chamber to a plasma, which is directed to the substrate with a relatively strong field. Electrically biased control grids control a rate of deposition of the plasma. The control grids also provide Li and/or Mg dopants for the ZnO to create the ferroelectric film. A desired ferroelectric property of the ferroelectric film can be tailored by selecting an appropriate composition of the control grids.