Method for evaluating oxide semiconductor and method for manufacturing semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei Yamazaki, Akiharu Miyanaga, Tatsuya Honda
Life of this patent
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Abstract
Many of the principles of an oxide semiconductor are still unclear and therefore there is no established method for evaluating an oxide semiconductor. Thus, an object is to provide a novel method for evaluating an oxide semiconductor. Carrier density is evaluated, and hydrogen concentration is also evaluated. Specifically, a MOS capacitor (a diode or a triode) is manufactured, and the C-V characteristics of the MOS capacitor are obtained. Then, the carrier density is estimated from the C-V characteristics obtained.
Claims9
A method for manufacturing a semiconductor device, comprising steps of:
- forming a MOS capacitor having a transistor including an oxide semiconductor layer over a substrate;
- obtaining a C-V characteristic by plotting a relationship between a gate voltage Vg and a capacitance C of the MOS capacitor;
- obtaining a graph by plotting a relationship between the gate voltage Vg and (1/C)2 with the use of the C-V characteristic;
- calculating a carrier density Nd by obtaining a differential value of (1/C)2 in a weak inversion region in the graph and substituting the differential value into a mathematical formula:
- N
- d
- =
- -
- (
- 2
- e
-
-
- ɛ
- 0
-
- ɛ
- )
- /
- ⅆ
- (
- 1
- /
- C
- )
- 2
- ⅆ
- V
- where e is an electron charge ε0 is a vacuum permittivity, and ε is a relative permittivity of the oxide semiconductor layer;
- and
- performing heat treatment of the transistor when the carrier density is determined to be 1×1018 cm−3 or more.
A method for manufacturing a semiconductor device, comprising steps of:
- forming a MOS capacitor having a transistor including an oxide semiconductor layer over a substrate;
- obtaining a C-V characteristic by plotting a relationship between a gate voltage Vg and a capacitance C of the MOS capacitor;
- obtaining a graph by plotting a relationship between the gate voltage Vg and (1/C)2 with the use of the C-V characteristic;
- calculating a carrier density Nd by obtaining a differential value of (1/C)2 in a weak inversion region in the graph and substituting the differential value into a mathematical formula:
- N
- d
- =
- -
- (
- 2
- e
-
-
- ɛ
- 0
-
- ɛ
- )
- /
- ⅆ
- (
- 1
- /
- C
- )
- 2
- ⅆ
- V
- where e is an electron charge, ε0 is a vacuum permittivity, and ε is a relative permittivity of the oxide semiconductor layer;
- and
- performing heat treatment of the transistor when the carrier density is determined to be 1×1016 cm−3 or more.
A method for manufacturing a semiconductor device, comprising steps of:
- forming a MOS capacitor having a transistor including an oxide semiconductor layer over a substrate;
- obtaining a C-V characteristic by plotting a relationship between a gate voltage Vg and a capacitance C of the MOS capacitor;
- obtaining a graph by plotting a relationship between the gate voltage Vg and (1/C)2 with the use of the C-V characteristic;
- calculating a carrier density Nd by obtaining a differential value of (1/C)2 in a weak inversion region in the graph and substituting the differential value into a mathematical formula:
- N
- d
- =
- -
- (
- 2
- e
-
-
- ɛ
- 0
-
- ɛ
- )
- /
- ⅆ
- (
- 1
- /
- C
- )
- 2
- ⅆ
- V
- where e is an electron charge, ε0 is a vacuum permittivity, and ε is a relative permittivity of the oxide semiconductor layer;
- and
- performing heat treatment of the transistor when the carrier density is determined to be 1×1014 cm−3 or more.
Dependencies are inferred from the claim text.