Measurement of the interface trap charge in an oxide semiconductor layer interface
First Claim
1. A method of determining charge associated with traps present in a semiconductor oxide interface between a semiconductor wafer and an oxide layer disposed on the wafer, the method comprising the steps of:
- depositing a dose of charge over a portion of a surface of the oxide layer;
measuring a resultant value of surface potential barrier at the portion of the surface of the oxide layer; and
determining a value of charge associated with interface trap from the surface potential barrier and the deposited charge dose.
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Abstract
A method of determining charge associated with traps present in a semiconductor oxide interface is described. The method includes the steps of depositing a dose of charge over a surface of the oxide and measuring a resultant value of surface potential barrier at the portion of the surface. From the measured value of surface charge and deposited charge dose a value of charge associated with the interface trap is determined. The method also includes determining space charge corresponding to the measured surface potential barrier of the portion of the substrate. With the determined space charge and known deposited charge the interface trapped charge is determined by noting that the change in interface trapped charge is related to the negative of the changes in space charge and deposited charge.
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Citations
20 Claims
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1. A method of determining charge associated with traps present in a semiconductor oxide interface between a semiconductor wafer and an oxide layer disposed on the wafer, the method comprising the steps of:
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depositing a dose of charge over a portion of a surface of the oxide layer; measuring a resultant value of surface potential barrier at the portion of the surface of the oxide layer; and determining a value of charge associated with interface trap from the surface potential barrier and the deposited charge dose. - View Dependent Claims (2)
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3. A method of determining charge associated with traps in a semiconductor oxide interface between a semiconductor wafer and an oxide layer disposed on the wafer, the method comprising the steps of:
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determining an initial surface potential barrier of the oxide layer; if the initial surface potential barrier is not in an accumulation condition, applying corona discharge to cause a charge accumulation condition; depositing a charge dose over the wafer; measuring the surface potential barrier over a plurality of locations of said wafer; and
for each of said measured differences,determining whether the surface potential barrier is within a threshold value approaching an inversion condition; continuing to deposit, charge and measure surface potential barrier over a plurality of regions of the wafer, until the surface potential barrier approaches a constant deep inversion level as a function of deposited charge; and calculating parameters associated with the interface trap charge from the measured values of surface potential barrier at inversion and deposited charge dosage levels.
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4. An apparatus for determining charge associated with traps present in a semiconductor oxide interface between a semiconductor wafer and an oxide laver disposed on the wafer, the method comprising:
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a corona discharge station for depositing a dose of charge over a surface of a oxide; a measuring station for measuring a resultant value of surface potential barrier; a computer for determining from the surface potential barrier and the deposited charge dose a value of charge associated with interface traps. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. A method of determining dopant concentration of a semiconductor comprises the steps of:
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depositing doses of charge over a surface of the oxide in measured doses of small precise increments changing the surface barrier from an accumulation to an inversion condition; measuring a resultant value of surface potential barrier, Vs at the surface defining (Q, Vs) range corresponding to a surface depletion layer where Q is defined as Q=Qc (Vs)-(Vs =0); and determining from the surface potential barrier and the deposited charge dose a value of dopant concentration in accordance with the equation,
space="preserve" listing-type="equation">Q.sup.2 =2qε
.sub.s N.sub.A (V.sub.s -kT/q) for V.sub.s >
kT/q.
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12. A method of determining charge associated with traps present in a P-type semiconductor/oxide interface comprises:
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depositing a dose of charge over a surface of the oxide; measuring a resultant value of surface potential barrier at the portion of the surface; determining from the surface potential barrier the space charge for surface depletion layer; and determining a value of charge associated with the interface trap from the space charge and the deposited charge dose. - View Dependent Claims (13, 14, 15, 16)
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17. A method of determining charge associated with traps in a p-type semiconductor/oxide interface comprises:
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determining an initial surface potential barrier of the oxide; if the initial surface potential barrier is not in an accumulation condition potential, applying corona discharge to cause a charge accumulation condition; depositing a charge dose over the wafer; measuring the surface potential barrier over a plurality of locations of said wafer; and
for each of said measured barriers,determining whether the surface potential barrier is within a threshold value approaching the inversion condition; continuing to deposit charge and to measure surface potential barrier over a plurality of regions of the wafer, until the surface potential barrier approaches a constant deep inversion level as a function of deposited charge; calculating from the surface potential barrier the space charge for surface depletion layer; and determining from the space charge and the deposited charge dose, a value of charge associated with the interface trap. - View Dependent Claims (18, 19)
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20. A method of determining charge associated with traps in an N-type semiconductor/oxide interface comprises:
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determining an initial surface potential barrier of the oxide; if the initial surface potential barrier is in a charge accumulation condition potential, applying corona discharge to establish a charge inversion condition; depositing a charge dose over the wafer; measuring the surface potential barrier over a plurality of locations of said wafer; and
for each of said measured barriers,determining whether the surface potential barrier is within the accumulation condition; continuing to deposit charge and to measure surface potential barrier over a plurality of regions of the wafer, until the surface potential barrier approaches a constant deep inversion level as a function of deposited charge; and calculating from the surface potential barrier the space charge for surface depletion layer and from the space charge and the deposited charge dose, a value of charge associated with the interface trap.
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Specification