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US 6,289,291 B1Granted
Statistical method of monitoring gate oxide layer yield
AssigneeUnited Microelectronics Corp.
InventorsMu-Chun Wang, Kuan-Yu Fu
Life of this patent
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Abstract
A statistical method of monitoring the yield of a gate oxide layer. A voltage is applied to first test keys and second test keys to build curves showing relationship between failure distribution and charge density, wherein each of the first test keys has a first oxide area and each of the second test keys has a second oxide area. A yield of the first test keys and a yield of the second test keys up to a charge density can be obtained. The yields of the first test keys and the second test keys have a relationship as an equation of area. To obtain a yield of small test keys, a yield and area of large test keys are imported into an equation. According to operating the equation, the yield of a small gate oxide is obtained.
Claims4
A method of monitoring the yield of a gate oxide layer, comprising the steps of:
- providing a plurality of first test keys and a plurality of second test keys, wherein each of the first test keys has a first area Ab and each of the second test keys has a second area As;
- testing the first test keys to obtain a curve of failure distribution F as a fuction of charge density a;
- calculating a yield Yb(a) of the first test keys from data of the failure distribution F;
- and
- substituting the yield Yb(a) of the first test keys into a equation Yb(a)=[Ys(a)](Ab/As) to obtain a yield of the second test keys Ys(a);
- wherein the yield Yb(a) is modified by a factor Ypb(a), wherein:
- Ypb(a)=[Yps(a)](Pb/Ps), so that the modified yield Yb′(a) is:
- Yb′(a)=Yb(a)×Ypb(a)=[Ys(a)]Ab/As×[Yps(a)]Pb/Ps
- wherein
- Yb(a) represents the yield of the first test keys up to the charge density a;
- Yb(a) represents the probability for the first test keys that the structure remains robust up to a;
- Ypb(a) represents the probability at the perimeter for the first test keys that the structure remains robust up to a;
- Ab and Pb represent respectively the area and the total perimeter of the first test keys;
- As and Ps represent respectively the area and the total perimeter of the second test keys;
- Ys(a) represents the probability for the second test keys that the structure remains robust up to a;
- and
- Yps(a) represents the probability at the perimeter for the second test keys that the structure remains robust up to a.
14 more elements
A method of monitoring the yield of a gate oxide layer, comprising the steps of:
- providing a plurality of first test keys and a plurality of second test keys, wherein each of the first test keys has a first area Ab and each of the second test keys has a second area As;
- testing the first test keys to obtain a curve of failure distribution F as a function of charge density a:
- calculating a yield Yb(a) of the first test keys from data of the failure distribution F;
- and
- substituting the yield Yb(a) of the first test keys into a equation Yb(a)=[Ys(a)](Ab/As) to obtain a yield of the second test keys Ys(a);
- wherein the gate oxide layer comprises more than one structure, and the modified yield Y(a)is:
- Y(a)=[Yau(a)]A×[Ypu(a)]P
- wherein
- Y(a) is the yield probability that a gate oxide layer with an arbitrary shape remains robust up to a;
- A represents an area of the gate oxide;
- P represents a perimeter of the gate oxide;
- Yau(a) represents the yield probability of unit area;
- and
- Ypu(a) represents the yield probability of unit perimeter.
11 more elements
A method of monitoring the yield of a gate oxide layer, comprising the steps of:
- providing a plurality of first test keys and a plurality of second test keys, wherein each of the first test keys has a first oxide area Ab and each of the second test keys has a second oxide area As;
- continually applying a voltage to the first test keys for testing;
- recording each data of failure distribution against charge density while each of the first test keys fails until all the first test keys fail;
- drawing a curve of each of the recorded data of failure distribution against charge density;
- converting the failure distribution into a yield Yb(a) of the first test keys;
- and
- substituting the yield Yb(a) of the first test keys into a equation Yb(a)=[Ys(a)](Ab/As) to obtain a yield of the second test keys;
- wherein the yield Yb(a) is modified by a factor Ypb(a), wherein:
- Ypb(a)=[Yps(a)](Pb/Ps), so that the modified yield Yb′(a) is:
- Yb′(a)=Yb(a)×Ypb(a)=[Ys(a)]Ab/As×[Yps(a)]Pb/Ps
- wherein
- Yb(a) represents the yield of the first test keys up to the charge density a;
- Yb(a) represents the probability for the first test keys that the structure remains robust up to a;
- Ypb(a) represents the probability at the perimeter for the first test keys that the structure remains robust up to a;
- Ab and Pb represent respectively the area and the total perimeter of the first test keys;
- As and Ps represent respectively the area and the total perimeter of the second test keys;
- Ys(a) represents the probability for the second test keys that the structure remains robust up to a;
- and
- Yps(a) represents the probability at the perimeter for the second test keys that the structure remains robust up to a.
16 more elements
A method of monitoring the yield of a gate oxide layer, comprising the steps of:
- providing a plurality of first test keys and a plurality of second test keys, wherein each of the first test keys has a first oxide area Ab and each of the second test keys has a second oxide area As;
- continually applying a voltage to the first test keys for testing;
- recording each data of failure distribution against charge density while each of the first test keys fails until all the first test keys fail;
- drawing a curve of each of the recorded data of failure distribution against charge density;
- converting the failure distribution into a yield Yb(a) of the first test keys;
- and
- substituting the yield Yb(a) of the first test keys into a equation Yb(a)=[Ys(a)](Ab/As) to obtain a yield of the second test keys;
- wherein the gate oxide layer comprises more than one structure, and the modified yield Y(a) is:
- Y(a)=[Yau(a)]A×[Ypu(a)]P
- wherein
- Y(a) is the yield probability that a gate oxide layer with an arbitrary shape remains robust up to a;
- A represents an area of the gate oxide;
- P represents a perimeter of the gate oxide;
- Yau(a) represents the yield probability of unit area;
- and
- Ypu(a) represents the yield probability of unit perimeter.
13 more elements
Dependencies are inferred from the claim text.