Source: http://www.google.com/patents/US6897166?dq=%22Meaning-based+information+organization+and+retrieval%22
Timestamp: 2017-10-20 12:53:07
Document Index: 142645003

Matched Legal Cases: ['art 19', 'art 19', 'art 19', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 2', 'art 4', 'art 2']

Patent US6897166 - Method of fabricating semiconductor device and system of fabricating ... - Google Patents
A method of fabricating a semiconductor device capable of obtaining a high-density laser beam necessary for crystallizing a semiconductor layer or activating an impurity while miniaturizing a lens group provided on the outlet of an optical fiber member is provided. This method of fabricating a semiconductor...http://www.google.com/patents/US6897166?utm_source=gb-gplus-sharePatent US6897166 - Method of fabricating semiconductor device and system of fabricating semiconductor device
Publication number US6897166 B2
Application number US 10/660,609
Also published as CN1487568A, CN100339958C, US20040053476
Publication number 10660609, 660609, US 6897166 B2, US 6897166B2, US-B2-6897166, US6897166 B2, US6897166B2
Inventors Naoya Sotani, Isao Hasegawa
Patent Citations (8), Referenced by (13), Classifications (29), Legal Events (4)
Method of fabricating semiconductor device and system of fabricating semiconductor device
US 6897166 B2
connecting a laser oscillator oscillating a near infrared laser beam and an irradiation optical system with each other through an optical fiber member having a single core part; and
heating a semiconductor layer by irradiating said near infrared laser beam from said irradiation optical system.
said step of heating said semiconductor layer includes a step of crystallizing said semiconductor layer by heating said semiconductor layer with said near infrared laser beam.
said step of heating said semiconductor layer includes a step of activating an impurity introduced into said semiconductor layer by heating said semiconductor layer with said near infrared laser beam.
said step of connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member includes a step of connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member having a length capable of reducing dispersion in intensity of said laser beam resulting from oscillation of a higher mode.
said step of connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member includes a step of connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member having a length of at least about 10 m.
said laser oscillator includes a first laser oscillator and a second laser oscillator,
said optical fiber member includes a first optical fiber member having a single core part connected to said first laser oscillator and a second optical fiber member having a single core part connected to said second laser oscillator, and
said irradiation optical system includes a single irradiation optical system connected with said first optical fiber member and said second optical fiber member for irradiating a single laser beam.
said irradiation optical system includes a first cylindrical lens receiving light from said first optical fiber member, a second cylindrical lens receiving light from said second optical fiber member, a single kaleidoscopic lens receiving said light from said first cylindrical lens and said light from said second cylindrical lens and a third cylindrical lens receiving light from said single kaleidoscopic lens while irradiating a single laser beam.
8. The method of fabricating a semiconductor device according to claim 6, wherein
an outlet of said first optical fiber member and an outlet of said second optical fiber member are arranged along the longitudinal direction of a linear laser beam at a prescribed interval.
said step of connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member includes a step of installing said laser oscillator in a first room while installing said irradiation optical system in a second room and connecting said laser oscillator and said irradiation optical system with each other through said optical fiber member having said single core part.
said step of heating said semiconductor layer includes steps of:
forming an absorption film either above or under said semiconductor layer, and
irradiating said absorption film with continuous-wave said near infrared laser beam thereby making said absorption film generate heat and crystallizing said semiconductor layer through said heat.
11. The method of fabricating a semiconductor device according to claim 10, wherein
said absorption film consists of a material containing a high melting point metal.
said optical fiber member includes a step index optical fiber member.
said irradiation optical system includes either an array lens optical system or a kaleidoscopic optical system.
14. The method of fabricating a semiconductor device according to claim 1, wherein
said near infrared laser beam is either a linear laser beam or a rectangular laser beam.
said core part of said optical fiber member has a diameter of not more than about 0.6 mm.
16. The method of fabricating a semiconductor device according to claim 1, wherein
said near infrared laser beam is a continuous-wave YAG laser beam.
17. The method of fabricating a semiconductor device according to claim 1, wherein
said step of heating said semiconductor layer by irradiating said near infrared laser beam from said irradiation optical system includes a step of feedback-controlling the output of said near infrared laser beam in said laser oscillator.
18. The method of fabricating a semiconductor device according to claim 1, wherein
said laser oscillator includes a single laser oscillator,
said optical fiber member includes a first optical fiber member and a second optical fiber member having single core parts connected to said single laser oscillator, and
said laser oscillator includes a first mirror transmitting about half of said oscillated laser beam while reflecting about the remaining half of said oscillated laser beam and a second mirror reflecting said laser beam reflected by said first mirror,
said laser beam transmitted through said first mirror is incident upon said first optical fiber member, and
said laser beam reflected by said second mirror is incident upon said second optical fiber member.
20. The method of fabricating a semiconductor device according to claim 1, wherein
said optical fiber member includes a first optical fiber member and a second optical fiber member having single core parts connected to said laser oscillator,
said laser oscillator includes a single laser oscillator for a dual head structure temporally switching said first optical fiber member and said second optical fiber member,
said irradiation optical system includes a first irradiation optical system connected with said first optical fiber member and a second irradiation optical system connected with said second optical fiber member, and
said step of heating said semiconductor layer by irradiating said near infrared laser beam from said irradiation optical system includes a step of irradiating different semiconductor layers with said near infrared laser beams through said first irradiation optical system and said second irradiation optical system.
A method of fabricating a semiconductor device according to a first aspect of the present invention comprises steps of connecting a laser oscillator oscillating a near infrared laser beam and an irradiation optical system with each other through an optical fiber member having a single core part and heating a semiconductor layer by irradiating the near infrared laser beam from the irradiation optical system. In the present invention, the term “near infrared laser beam” denotes a laser beam having a wavelength of at least 0.75 μm and not more than 2.0 μm.
In the aforementioned method of fabricating a semiconductor device according to the first aspect, the step of heating the semiconductor layer preferably includes a step of crystallizing the semiconductor layer by heating the semiconductor layer with the near infrared laser beam. In the present invention, the term “crystallization” denotes a wide concept also including recrystallization of temporarily melting an already crystallized substance and thereafter re-crystallizing the same. According to this structure, the semiconductor layer can be easily crystallized with the near infrared laser beam whose optical density is improved due to incidence upon the optical fiber member having the single core part.
An output of the light intensity sensor 18 is connected to a control part 19 including a power source. Outputs of the excitation semiconductor laser diodes (LDs) 12 a and 12 b are also connected to the control part 19. The control part 19 performs feedback control on the basis of a result of detection of the light intensity sensor 18 and the output of the excitation semiconductor laser diode (LD) 12 b.
According to this embodiment, the optical fiber member 2 connecting the laser oscillator 1 and the irradiation optical system 3 with each other is constituted of the single core part 2 a and a cladding part 2 b formed on the periphery thereof, as shown in FIG. 3. The optical fiber member 2 having the core part 2 a is formed as a step index type optical fiber member having the core part 2 a exhibiting a uniform refractive index with a length (40 m in this embodiment) of at least about 10 m.
The flatness of a glass substrate is about 100 μm, and hence the focal depth of the laser beam 100 must be at least about ±100 μm. If the optical fiber member 2 has a core diameter of 0.3 mm for condensing a laser beam having a short side of 0.1 mm, the beam quality is 50 mm·mrad. The beam quality, expressed by the product of the width of a thin portion of the beam and the beam divergence angle, is improved as the value thereof is reduced. This beam quality cannot be improved through an optical system. The relation between the beam quality and the diameter of the optical fiber member is approximately decided such that the former is 50 mm·mrad when the latter is 0.3 mm as described above and the former is 100 mm·mrad when the latter is 0.6 mm.
Assuming that allowable accuracy for the short side of the laser beam emitted from the optical fiber member having the core diameter of 0.3 mm is 0.1 mm+0.02 mm, the beam focal depth is ±240 μm at the maximum. When the core diameter of the core part 2 a of the optical fiber member 2 is 0.6 mm, the focal depth is ±120 μm at the maximum.
In order to obtain a focal depth of at least ±100 μm, therefore, the core part 2 a of the optical fiber member 2 preferably has a core diameter of not more than 0.6 mm. According to this embodiment, the core diameter of the core part 2 a of the optical fiber member 2 is set to 0.3 mm in consideration of this point. In this embodiment, the focal depth of the optical fiber member 2 having the core part 2 a exhibiting the core diameter of 0.3 mm and the irradiation optical system 3 is ±150 μm in practice.
As shown in FIG. 8, a buffer layer 22 consisting of an SiO2 film having a thickness of about 600 nm and an SiNx film having a thickness of about 20 nm in ascending order is formed on a glass substrate 21 by plasma CVD. An islanded semiconductor layer 23 of amorphous silicon or polycrystalline silicon for serving as an active layer is formed on the buffer layer 22 with a thickness of about 50 nm. An SiO2 film 24 is formed by plasma CVD to cover the semiconductor layer 23 with a thickness of about 100 nm. An absorption film 25 of Mo having a thickness of about 50 nm is formed on the SiO2 film 24. Preheating is performed at a temperature of about 200° C., for thereafter scanning the upper surface of the absorption film 25 with the continuous-wave YAG laser beam 100 condensed to a rectangular shape of about 0.1 mm by about 4 mm with the laser irradiator shown in FIG. 1 under conditions of a laser output of about 385 W, a scanning rate of about 1000 mm/s. and atmosphere gas of Ar.
A resist mask (not shown) is formed on a prescribed region for implanting P+ (phosphorus) ions and B+ (boron) ions into an n-channel TFT forming portion and a p-channel TFT forming portion under conditions of about 80 keV and about 7×1014 cm−2 and conditions of about 35 keV and about 1.5×1015 cm−2 respectively. Thereafter the implanted impurities are activated by RTA (rapid thermal annealing). Thus, source/drain regions 23 b are formed as shown in FIG. 9. An n-channel TFT and a p-channel TFT are formed in the aforementioned manner.
In FIG. 10, one long and slender cylindrical lens may be used by connecting two cylindrical lenses 33 a and 33 b.
While the substrate 50 is scanned with the laser beam 100 through the single irradiation optical system 3 in the aforementioned embodiment as shown in FIG. 1, the present invention is not restricted to this but a laser irradiator of a dual head structure may alternatively be employed for irradiating two substrates with laser beams through two irradiation optical systems, for example.
More specifically, different substrates may be irradiated with laser beams through a laser oscillator 61 for a dual head structure temporally switching optical fiber members 42 a and 42 b and two irradiation optical systems 53 a and 53 b, as shown in FIG. 12. Referring to FIG. 12, mirrors 44 and 45 for resonance are set on both sides of a YAG lot 41. A switching mirror 56 a switches the optical path of light passing through the mirror 44 every prescribed time. Light transmitted through the mirror 56 a is condensed by a lens 47 a and introduced into the optical fiber member 42 a. Light reflected by the mirror 56 a is reflected by another mirror 46 b, thereafter condensed by another lens 47 b and introduced into the optical fiber member 42 b.
While the irradiation optical system 3 and the laser oscillator 1 are installed in the clean room and the room outside the clean room provided on the same floor respectively in the aforementioned embodiment as shown in FIG. 1, the present invention is not restricted to this but the irradiation optical system 3 and the laser oscillator 1 may alternatively be installed in a clean room and a machinery room (outside the clean room) provided on different floors respectively.
Also according to the structure of the laser irradiator shown in FIG. 14, effects such as saving of the space of the clean room can be attained similarly to the aforementioned embodiment. According to the structure of the laser irradiator shown in FIG. 14, most part of the laser irradiator is installed in the service area while only the opening 72 c of the substitution room 72 and the cassette 73 are provided in the clean room, whereby the space of the clean room can be further saved. In this case, the laser irradiator can be maintained in the service area, whereby the clean room can be inhibited from reduction of cleanliness caused by dust or the like resulting from maintenance. The service area storing the irradiation optical system 3, the irradiation optical system moving part 4, the base 5 and the heater plate 6, the machine room storing the laser oscillator 1 and the clean room may be provided in a factory fabricating semiconductor devices while connecting the irradiation optical system 3 and the laser oscillator 1 with each other through the optical fiber member 2 having the single core part 2 a.
JP2001291666A Title not available
JP2002050576A Title not available
JPH06345415A Title not available
International Classification H01L21/20, H01L21/265, H01L21/00, H01L21/78, H01L21/268, H01L21/324, H01L21/301, H01L29/786, B23K26/12, B23K26/00, H01L21/26, H01L21/336
Cooperative Classification B23K26/064, B23K26/127, B23K26/123, H01L21/2026, B23K26/0665, B23K26/0648, B23K26/12, B23K26/0643
European Classification B23K26/12D, B23K26/06C1, B23K26/06C3, B23K26/06C, B23K26/06H, B23K26/12, H01L21/20D2
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:SOTANI, NAOYA;HASEGAWA, ISAO;REEL/FRAME:014501/0487