Development of Anisotropic Dry Etching Process Using Laser Cooling Method

提出了一种新的方法，即使用激光准直的中性自由基光束进行人工干燥处理。如果使用此方法，则不会对电荷粒子造成任何损坏，即预期会在微小的硅器件中造成任何破坏。（1） For generation of F radicals， we made 13. 56 MHz plasma source to decompose NFイイD23イエD2 gas。NF-D23-D2 is the Best matching for the present purpose judged from the view point of radical generation efficiency， easy handling， and no decomposition products。（2）闭合激光冷却循环的波长被确定为685.793纳米，由NF D23 D2等离子体的精确发射光谱分析决定。（3） The lower state of laser cooling cycle （3 pイイD14イイD1DイイD30（±）7/2イD3 [tautomer] 3 sイD14イイD1PイD25/2イD2） is the metastable state。因此， the metastable？etime？D2F？D2 of 3 s？D14？D1P？D25/2？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？D2F？D2 has been published。We have made a new approach to measure？D2F？D2 of 3 s？D14？D1P？D25/2？D2 state to get？D2F？D2= 3. 7 ± 0. 5？s。（4） Based on the short lifetime of 3 sイイD14イイD1PイD25/2イD2 state， it is not a practical way to collimate F radical beam using spontaneous light force。However，一种强有力的激光碰撞方法，使用刺激的光力可以被用于碰撞自由基束。（5）我们开发了一个非常有效的ECR （电子cyclotron resonance）微波等离子体来源的自由基光束。与射频自由基源进行比较，硅蚀刻速率的20-折叠增加和685.793纳米发射强度的80-折叠增加已被开发的ECR源实现。（6）我们测量了硅蚀刻率，而不使用离子还原偏差电压应用于硅晶圆。它包含了一个实际的处理率，即中性基础设施将可用于半导体制造过程。

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.