Semiconductor Energy Laboratory Co., Ltd.

Other

Ritsuko Kawasaki

Kenji Kasahara

Shunpei Yamazaki

Hisashi Ohtani

Hidehito Kitakado

Koichiro Tanaka

Setsuo Nakajima

Hiroki Adachi

Toru Takayama

Yasuyuki Arai

Masahiko Hayakawa

Hiroshi Shibata

Taketomi Asami

Naoya Sakamoto

Hiroyuki Ogawa

Kazuhide Tomiyasu

Hideto Kitakado

The present invention provides a semiconductor device in which a bottom-gate TFT or an inverted stagger TFT arranged in each circuit is suitably constructed in conformity with the functionality of the respective circuits, thereby attaining an improvement in the operating efficiency and reliability of the semiconductor device. In the structure, LDD regions in a pixel TFT are arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in an N-channel TFT of a drive circuit is arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in a P-channel TFT of the drive circuit is arranged so as to overlap with a channel protection insulating film and to overlap with the gate electrode.

Semiconductor device and manufacturing method thereof

A laser annealing method for obtaining a crystalline semiconductor film having a large grain size, and a method of manufacturing a semiconductor device using the crystalline semiconductor film, are provided. Using a shape change (convex portion or concave portion) of an amorphous semiconductor film when crystallizing the amorphous semiconductor film using irradiation of laser light, it is possible to intentionally regulate the origin of crystal growth, and to make the grain size large. By then designing the arrangement of an active layer (island shape semiconductor film) so as to contain at least a channel forming region within one grain, it becomes possible to improve the electrical characteristics of a TFT.

Semiconductor device, manufacturing method thereof, and electronic device

The present invention provides a semiconductor device in which a bottom-gate TFT or an inverted, stagger TFT arranged in each circuit is suitably constructed in conformity with the functionality of the respective circuits, thereby attaining an improvement in the operating efficiency and reliability of the semiconductor device. In the structure, LDD regions in a pixel TFT are arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in an N-channel TFT of a drive circuit is arranged so as not to overlap with a channel protection insulating film and to overlap with a gate electrode by at least a portion thereof. LDD regions in a P-channel TFT of the drive circuit is arranged so as to overlap with a channel protection insulating film and to overlap with the gate electrode.

Protrusions called ridges are formed on the surface of a crystalline semiconductor film formed by a laser crystallization method or the like. A heat absorbing layer are formed below a semiconductor film. When the semiconductor film is crystallized by laser, a temperature difference is produced between a semiconductor filmpositioned above a heat absorbing layerand a semiconductor filmof the other region to produce a difference in thermal expansion at the boundary of the outside endof the heat absorbing layer. This difference produces a strain to form a surface wave. The surface wave starting at the outer periphery of the heat absorbing layer is formed in the vicinity of the heat absorbing layer. When the semiconductor layer is solidified after it is melted, the protrusions of the surface wave remain as protrusions after the semiconductor film is solidified.

Semiconductor device and its manufacturing method

To realize TFT enabling high-speed operation by fabricating a crystalline semiconductor film in which positions and sizes of crystal grains are controlled and using the crystalline semiconductor film in a channel forming region of TFT, a film thickness is stepped by providing a stepped difference in at least one layer of a matrix insulating film among a plurality of matrix insulating films having refractive indices different from each other. By irradiating laser beam from a rear face side of a substrate (or both sides of a surface side and the rear face side of the substrate), there is formed an effective intensity distribution of laser beam with regard to a semiconductor film and there is produced a temperature gradient in correspondence with a shape of the stepped difference and a distribution of the film thickness of the matrix insulating film in the semiconductor film. By utilizing thereof, a location of producing lateral growth and a direction thereof can be controlled to thereby enable to provide crystal grains having large particle sizes.

Semiconductor device and method of fabricating thereof

In a semiconductor device including a laminate of a first insulating layer, a crystalline semiconductor layer, and a second insulating layer, characteristics of the device are improved by determining its structure in view of stress balance. In the semiconductor device including an active layer of the crystalline semiconductor layer having tensile stress on a substrate, tensile stress is given to the first insulating layer formed to be in close contact with a surface of the semiconductor layer at a substrate side, and compressive stress is given to the second insulating layer formed to be in close contact with a surface of the semiconductor layer at a side opposite to the substrate side.

Semiconductor device and method of fabricating the same

A crystalline semiconductor film in which the position and size of a crystal grain is controlled is fabricated, and the crystalline semiconductor film is used for a channel formation region of a TFT, so that a high performance TFT is realized. An island-like semiconductor layer is made to have a temperature distribution, and a region where temperature change is gentle is provided to control the nucleus generation speed and nucleus generation density, so that the crystal grain is enlarged. In a region where an island-like semiconductor layeroverlaps with a base film, a thick portion is formed in the base film. The volume of this portion increases and heat capacity becomes large, so that a cycle of temperature change by irradiation of a pulse laser beam to the island-like semiconductor layer becomes gentle (as compared with other thin portion). Like this, a laser beam is irradiated from the front side and reverse side of the substrate to directly heat the semiconductor layer, and heat conduction from the semiconductor layer to the side of the substrate and heat conduction of the semiconductor layer in the horizontal direction to the substrate are used, so that the increase in the size of the crystal grain is realized.

To provide a laser apparatus and a laser annealing method with which a crystalline semiconductor film with a larger crystal grain size is obtained and which are low in their running cost. A solid state laser easy to maintenance and high in durability is used as a laser, and laser light emitted therefrom is linearized to increase the throughput and to reduce the production cost as a whole. Further, both the front side and the back side of an amorphous semiconductor film is irradiated with such laser light to obtain the crystalline semiconductor film with a larger crystal grain size.

Laser annealing method and manufacturing method of a semiconductor device

The present invention provides a laser apparatus including a transmission-variable mirror and a method for forming a semiconductor device using the apparatus. For crystallizing an amorphous semiconductor film by irradiation of laser beams, a top surface and a back surface of the amorphous semiconductor film are irradiated with the laser beams. In this case, the transmission-variable mirror is used for dividing a laser light emitted from a laser source.

Laser apparatus and laser annealing method

To form a polycrystalline silicon film having a grain size of 1 &#x3bc;m or greater by means of laser annealing. A beam emitted from a laser apparatus () is split in two by a half mirror. The split beams are processed into linear shapes by cylindrical lenses () to (), and (), then simultaneously irradiate an irradiation surface (). If an amorphous silicon film formed on a glass substrate is disposed on the irradiation surface (), an area will be irradiated by both a linear shape beam entering from a front surface and a linear shape beam that has transmitted through the glass surface. Both linear shape beams irradiate the same area to thereby crystallize the amorphous silicon film.

Laser irradiation apparatus, laser irradiation method, semiconductor device, and method of manufacturing a semiconductor device

To provide a technique required for purifying the interface between an active layer and an insulating film. On a substrate (), a gate wiring () is formed and the surface thereof is covered with a gate oxide film (). Then, a first insulating film (), a second insulating film (), a semiconductor film () and a protective film () are sequentially formed and layered without exposing them to the air. Further, the semiconductor film () is irradiated with laser light through the protective film (). In this way, a TFT may be given good characteristics by completely purifying the interface of the semiconductor film.

Semiconductor device and a method of manufacturing the same

A laser annealing method for obtaining a crystalline semiconductor film having a large grain size is provided. Laser light is irradiated to the top surface and the bottom surface of an amorphous semiconductor film when crystallizing the amorphous semiconductor film by laser light irradiation. Furthermore, a relationship of 0&#x3c;(I'/I)&#x3c;1, or 1&#x3c;(I&#x2032;/I) is achieved for the ratio (I/I&#x2032;) between the effective energy strength of the laser light when irradiated to the top surface (I) and the effective energy strength of the laser light when irradiated to the bottom surface (I&#x2032;).

This invention improves TFT characteristics by making an interface between an active layer, especially a region forming a channel formation region and an insulating film excellent, and provides a semiconductor device provided with a semiconductor circuit made of a semiconductor element having uniform characteristics and a method of fabricating the same. In order to achieve the object, a gate wiring line is formed on a substrate or an under film, a gate insulating film, an initial semiconductor film, and an insulating film are formed into a laminate without exposing them to the atmosphere, and after the initial semiconductor film is crystallized by irradiation of infrared light or ultraviolet light (laser light) through the insulating film, patterning is carried out to obtain an active layer and a protection film each having a desired shape, and then, a resist mask is used to fabricate the semiconductor device provided with an LDD structure.

Semiconductor device provided with semiconductor circuit made of semiconductor element and method of fabricating the same

A crystalline semiconductor film having crystal grains of large grain size or crystal grains in which the position and the size are controlled is formed to manufacture a TFT, whereby a semiconductor device that enables a high-speed operation is realized. First, a reflecting member is provided on a rear surface side of a substrate on which a semiconductor film is formed (semiconductor film substrate). When a front surface side of the semiconductor film substrate is irradiated with a laser beam that penetrates the semiconductor film substrate, the laser beam is reflected by the reflecting member to irradiate the semiconductor film from the rear surface side. With this method, an effective energy density is raised in the semiconductor film, and an output time is made long. Thus, the cooling rate of the semiconductor film is made gentle and crystal grains of large grain size are formed. Further, the front surface side of the semiconductor film substrate is irradiated with the laser beam by using a substrate on which a reflecting layer is partially formed as the reflecting member, whereby the semiconductor film is partially irradiated with the laser beam from the rear surface side. Thus, a temperature distribution is generated in the semiconductor film, and the location where a lateral growth is generated and the lateral direction can be controlled. Therefore, the crystal grains of large grain size can be obtained.

Growing community of inventors

Kanagawa, Japan

Ritsuko Kawasaki