Development of Anisotropic Dry Etching Process Using Laser Cooling Method

A new method of anisotoropic dry etching using a laser-collimated neutral F radical beam has been proposed.Using this method，no damage nor pattern distortion by the charged particles is expected in the miniaturized Si devices.(1)For generation of F radicals，we made13.56 MHz plasma source to decompose NF I D 23 e D2 gas。NF D 23 D D 2 is the best matching for the present purpose judged from the view points of radical generation efficiency，easy handling，and no decomposition products.(2)The wavelength for the closed laser cooling cycle was determined to be 685.793 nm by the precision emission spectrum analysis of NF I D 23 D D 2 plasma.(3)The lower state of laser cooling cycle(3 p I D 14 D 30()7/2 D d.(3)The lower state of laser cooling cycleTherefore，the metastable lifetimeτI D2F文件D2 of 3s文件D14文件D1P文件D25/2文件D2 state is the key factor to accomplish successful laser collimation of Fradical beam using spontaneous light force.So far，however，no reliable report onτI D2F文件D2 has been published。We have made a new approach to measureτi D2F文件D2 of 3s I D14文件D1P文件D25/2文件D2 state to getτ文件D2=3.7±0.5µs.(4)Based on the short lifetime of 3s文件D14文件D1P文件D25/2文件D2 state，it is not a practical way to collimate F radical beam using spontaneous light force.However，the powerful laser collimation method using stimulated light force can be used to collimate F radical beam.(5)We have developed a highly efficient ECR(Electron Cyclotron Resonance)microwave plasma source of Fradical beam。Compared to the RF radical source，20-fold increase of the Si etching rate and 80-fold increase of the 685.793 nm emission intensity of F radicals have been achieved by the developed ECR source.(6)We measured the Si etching rates with and without the ion retarding bias voltage applied to the Si wafer。It was concluded that a practical etching rate by neutral F radicals would be obtainable for semiconductor manufacturing process。

A new method of anisotoropic dry etching using a laser-collimated neutral F radical beam has been proposed. Using this method, no damage nor pattern distortion by the charged particles is expected in the miniaturized Si devices.(1) For generation of F radicals, we made 13.56 MHz plasma source to decompose NFィイD23ィエD2 gas. NFィイD23ィエD2 is the best matching for the present purpose judged from the view points of radical generation efficiency, easy handling, and no decomposition products.(2) The wavelength for the closed laser cooling cycle was determined to be 685.793nm by the precision emission spectrum analysis of NFィイD23ィエD2 plasma.(3) The lower state of laser cooling cycle (3pィイD14ィエD1DィイD30(/)7/2ィエD3【tautomer】3sィイD14ィエD1PィイD25/2ィエD2) is the metastable state. Therefore, the metastable lifetime τィイD2FィエD2 of 3sィイD14ィエD1PィイD25/2ィエD2 state is the key factor to accomplish successful laser collimation of F radical beam using spontaneous light force. So far, however, no reliable report on τィイD2FィエD2 has been published. We have made a new approach to measure τィイD2FィエD2 of 3sィイD14ィエD1PィイD25/2ィエD2 state to get τィイD2FィエD2=3.7±0.5μs.(4) Based on the short lifetime of 3sィイD14ィエD1PィイD25/2ィエD2 state, it is not a practical way to collimate F radical beam using spontaneous light force. However, the powerful laser collimation method using stimulated light force can be used to collimate F radical beam.(5) We have developed a highly efficient ECR (electron cyclotron resonance) microwave plasma source of F radical beam. Compared to the RF radical source, 20-fold increase of the Si etching rate and 80-fold increase of the 685.793nm emission intensity of F radicals have been achieved by the developed ECR source.(6) We measured the Si etching rates with and without the ion retarding bias voltage applied to the Si wafer. It was concluded that a practical etching rate by neutral F radicals would be obtainable for semiconductor manufacturing process.