Method for Manufacturing Thin Film Transistor
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorHidekazu MIYAIRI
Life of this patent
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Abstract
It is an object to provide a method for manufacturing a thin film transistor, in which the number of masks to be used is small. A thin film transistor is manufactured as follows: a first conductive film, an insulating film, a semiconductor film, an impurity semiconductor film, and a second conductive film are stacked; a resist mask having a recessed portion is formed thereover with the use of a multi-tone mask; a thin-film stack body is formed with first etching; a gate electrode layer is formed with second etching in which an etched first conductive film is side-etched; and then a source electrode and a drain electrode and the like are formed. A crystalline semiconductor film is used for the semiconductor film.
Claims19
A method for manufacturing a thin film transistor, comprising the steps of:
- stacking a first conductive film, an insulating film, and a first semiconductor film in this order;
- crystallizing the first semiconductor film to form a second semiconductor film;
- stacking an impurity semiconductor film and a second conductive film in this order over the second semiconductor film;
- forming a first resist mask having a recessed portion over the second conductive film;
- performing first etching on at least the second conductive film, the impurity semiconductor film, the second semiconductor film, and the insulating film with the use of the first resist mask;
- performing second etching in which the first conductive film is side-etched to form a first wiring layer;
- reducing the first resist mask to expose a part of the second conductive film which overlaps with the recessed portion of the first resist mask to form a second resist mask after performing the second etching;
- and
- performing third etching on the second conductive film, the impurity semiconductor film, and the second semiconductor film with the use of the second resist mask to form a second wiring layer, an impurity semiconductor layer, and the second semiconductor film whose upper part is etched.
A method for manufacturing a thin film transistor, comprising the steps of
- stacking a first conductive film, an insulating film, and a first semiconductor film in this order;
- crystallizing the first semiconductor film to form a second semiconductor film;
- stacking an impurity semiconductor film and a second conductive film in this order over the second semiconductor film;
- forming a first resist mask having a recessed portion over the second conductive film;
- performing first etching on at least the second conductive film, the impurity semiconductor film, the second semiconductor film, and the insulating film with the use of the first resist mask;
- reducing the first resist mask to expose a part of the second conductive film which overlaps with the recessed portion of the first resist mask to form a second resist mask;
- performing second etching in which the first conductive film is side-etched to form a first wiring layer after reducing the first resist mask;
- and
- performing third etching on parts of the second conductive film, the impurity semiconductor film, and the second semiconductor film with the use of the second resist mask to form a second wiring layer, an impurity semiconductor layer, and the second semiconductor film whose upper part is etched.
A method for manufacturing a thin film transistor, comprising the steps of:
- stacking a first conductive film, an insulating film, and a first semiconductor film in this order;
- crystallizing the first semiconductor film to form a second semiconductor film;
- forming a first resist mask over the second semiconductor film;
- adding an impurity element imparting one conductivity type to a region of the second semiconductor film which is not covered with the first resist mask;
- removing the first resist mask, and then activating the impurity element of the second semiconductor film;
- forming a second conductive film over the second semiconductor film;
- forming a second resist mask having a recessed portion over the second conductive film;
- performing first etching on at least the second conductive film, the second semiconductor film, and the insulating film with the use of the second resist mask;
- performing second etching in which the first conductive film is side-etched to form a first wiring layer;
- forming a third resist mask over the second conductive film;
- and
- performing third etching on the second conductive film and the second semiconductor film with the use of the third resist mask to form a second wiring layer and a semiconductor layer including a source region and a drain region.
Dependencies are inferred from the claim text.