Semiconductor Energy Laboratory Co., Ltd.

Toru Mitsuki

Shunpei Yamazaki

Hisashi Ohtani

Akiharu Miyanaga

Tamae Takano

Taketomi Asami

Kenji Kasahara

Takeshi Shichi

Hideto Ohnuma

Mitsuhiro Ichijo

Chiho Kokubo

Koji Dairiki

Yasushi Ogata

Toru Takayama

Junichi Koezuka

Masayuki Kajiwara

Takeshi Fukunaga

Osamu Nakamura

Satoshi Toriumi

Takashi Ohtsuki

Yasuyuki Arai

Yoko Kanakubo

Kengo Akimoto

Shinji Maekawa

Hiroshi Shibata

Osama Nakamura

After an amorphous semiconductor thin film is crystallized by utilizing a catalyst element, the catalyst element is removed by performing a heat treatment in an atmosphere containing a halogen element. A resulting crystalline semiconductor thin film exhibits {110} orientation. Since individual crystal grains have approximately equal orientation, the crystalline semiconductor thin film has substantially no grain boundaries and has such crystallinity as to be considered a single crystal or considered so substantially.

Semiconductor thin film and semiconductor device

After an amorphous semiconductor thin film is crystallized by utilizing a catalyst element, the catalyst element is removed by performing a heat treatment in an atmosphere containing a halogen element. A resulting crystalline semiconductor thin film exhibits {} orientation. Since individual crystal grains have approximately equal orientation, the crystalline semiconductor thin film has substantially no grain boundaries and has such crystallinity as to be considered a single crystal or considered so substantially.

When a laser beam is irradiated onto a semiconductor film, a steep temperature gradient is produced between a substrate and the semiconductor film. For this reason, the semiconductor film contracts, so that a warp in the film occurs. Therefore, the quality of a resulting crystalline semiconductor film sometimes deteriorates. According to the present invention, it is characterized in that, after laser beam crystallization on the semiconductor film, heat treatment is carried out so as to reduce the warp in the film. Since the substrate contracts by the heat treatment, the warp in the semiconductor film is lessened, so that the physical properties of the semiconductor film can be improved.

Method of manufacturing a semiconductor device

Method of fabricating TFTs (thin-film transistors) having a crystallized silicon film and a gate-insulating film. First, an amorphous silicon film is formed on an insulating substrate. A first dielectric film is formed from silicon oxide on the amorphous silicon film. Holes are formed in the first dielectric film to selectively expose the surface of the amorphous silicon film. Nickel is introduced as the metal element into the amorphous silicon film. The film is heat-treated, thus forming crystallized silicon film. This crystalline silicon film is etched together with the silicon oxide film to form an active layer. The etched silicon oxide film acts as the aforementioned gate-insulating film. Even after the crystallization step, the silicon oxide film is left behind. As a result, the interface with the crystalline silicon film is kept in a good state.

Method of fabricating semiconductor devices

An object is to reduce the number of high temperature (equal to or greater than 600&#xb0; C.) heat treatment process steps and achieve lower temperature (equal to or less than 600&#xb0; C.) processes, and to simplify the process steps and increase throughput in a method of manufacturing a semiconductor device. With the present invention, a barrier layer, a second semiconductor film, and a third semiconductor film containing a noble (rare) gas element are formed on a first semiconductor film having a crystalline structure. Gettering is performed and a metallic element contained in the first semiconductor film passes through the barrier layer and the second semiconductor film by a heat treatment process, and moves to the third semiconductor film. The second semiconductor film and the third semiconductor film are then removed, with the barrier layer used as an etching stopper.

In a crystalline silicon film fabricated by a related art method, the orientation planes of its crystal randomly exist and the orientation rate relative to a particular crystal orientation is low. A semiconductor material which contains silicon as its main component and 0.1-10 atomic % of germanium is used as a first layer, and an amorphous silicon film is used as a second layer. Laser light is irradiated to crystallize the amorphous semiconductor films, whereby a good semiconductor film is obtained. In addition, TFTs are fabricated by using such a semiconductor film.

Semiconductor device and fabrication method therefor

A first amorphous semiconductor film is formed on an insulating surface. A catalyst element for promoting crystallization is added thereto. Thereafter, by a first heat treatment in an inert gas, a first crystalline semiconductor film is formed. A barrier layer and a second semiconductor layer are formed on the first crystalline semiconductor film. The second semiconductor layer contains a rare gas element at a concentration of 1&#xd7;10to 2&#xd7;10/cm, preferably 1&#xd7;10to 1&#xd7;10/cmand oxygen at a concentration of 5&#xd7;10to 1&#xd7;10/cm. Subsequently, by a second treatment in an inert gas, the catalyst element remaining in the first crystalline semiconductor film is moved to the second semiconductor film.

Process for manufacturing a semiconductor device

The crystallization method by laser light irradiation forms a multiplicity of convexes (ridges) in the surface of an obtained crystalline semiconductor film, deteriorating film quality. Therefore, it is a problem to provide a method for forming a ridge-reduced semiconductor film and a semiconductor device using such a semiconductor film. The present invention is characterized by heating a semiconductor film due to a heat processing method (RTA method: Rapid Thermal Anneal method) to irradiate light emitted from a lamp light source after crystallizing the semiconductor film by laser light, thereby reducing the ridge.

Method for manufacturing a semiconductor device including top gate thin film transistor and method for manufacturing an active matrix device including top gate thin film transistor

The orientation ratio of a crystalline semiconductor film obtained by crystallizing an amorphous semiconductor film through heat treatment and irradiation of intense light such as laser light, ultraviolet rays, or infrared rays is enhanced, and a semiconductor device whose active region is formed from the crystalline semiconductor film and a method of manufacturing the semiconductor device are provided. In a semiconductor film containing silicon and germanium as its ingredient and having a crystal structure, the {101} plane reaches 30% or more of all the lattice planes detected by Electron backscatter diffraction. This semiconductor film is obtained by forming an amorphous semiconductor film containing silicon and germanium as its ingredient through plasma CVD in which hydride, fluoride, or chloride gas of a silicon atom is used, the repetition frequency is set to 10 kHz or less, and the duty ratio is set to 50% or less for intermittent electric discharge or pulsed electric discharge, and introducing an element for promoting crystallization of the amorphous semiconductor film to the surface thereof to crystallize the amorphous semiconductor film while utilizing the introduced element.

Semiconductor device and method of manufacturing the same

In a semiconductor device using a crystalline semiconductor film on a substratehaving an insulating surface, impurities are locally implanted into an active regionto form a pinning region. The pinning regionsuppresses the spread of a depletion layer from the drain side to effectively prevent the short channel effect. Also, since a channel forming regionis intrinsic or substantially intrinsic, a high mobility is realized.

It is intended to achieve the reduction in number of heat treatments carried out at high temperature (at least&#xb0; C.) and the employment of lower temperature processes (&#xb0; C. or lower), and to achieve step simplification and throughput improvement. In the present invention, a barrier layer (), a second semiconductor film (), and a third semiconductor layer () containing an impurity element (phosphorus) that imparts one conductive type are formed on a first semiconductor film () having a crystalline structure. Gettering is carried out in which the metal element contained in the first semiconductor film () is allowed to pass through the barrier layer () and the second semiconductor film () by a heat treatment to move into the third semiconductor film (). Afterward, the second and third semiconductor films () and () are removed with the barrier layer () used as an etching stopper.

An insulating filmfor making an under insulating layeris formed on a quartz or semiconductor substrate. Recessestocorresponding to recessestoof the substrateare formed on the surface of the insulating film. The surface of this insulating filmis flattened to form the under insulating layer. By this flattening process, the distance L, L, . . . , Ln between the recessesof the under insulating layeris made 0.3 &#x3bc;m or more, and the depth of the respective recesses is made 10 nm or less. The root-mean-square surface roughness of the surface of the under insulating filmis made 0.3 nm or less. By this, in the recesses, it can be avoided to block crystal growth of the semiconductor thin film, and crystal grain boundaries can be substantially disappeared.

Semiconductor device

The TFT has a channel-forming region formed of a crystalline semiconductor film obtained by heat-treating and crystallizing an amorphous semiconductor film containing silicon as a main component and germanium in an amount of not smaller than 0.1 atomic % but not larger than 10 atomic % while adding a metal element thereto, wherein not smaller than 20% of the lattice plane {} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film, not larger than 3% of the lattice plane {} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film, and not larger than 5% of the lattice plane {} has an angle of not larger than 10 degrees with respect to the surface of the semiconductor film as detected by the electron backscatter diffraction pattern method.

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Kanagawa, Japan

Toru Mitsuki