Method for evaluating oxide semiconductor and method for manufacturing semiconductor device
First Claim
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1. 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;
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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.
93 Citations
9 Claims
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1. A method for manufacturing a semiconductor device, comprising steps of:
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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; - View Dependent Claims (2, 3)
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4. A method for manufacturing a semiconductor device, comprising steps of:
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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; - View Dependent Claims (5, 6)
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7. A method for manufacturing a semiconductor device, comprising steps of:
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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; - View Dependent Claims (8, 9)
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