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US 7,064,087 B1Granted
Phosphorous-doped silicon dioxide process to customize contact etch profiles
AssigneeNovellus Systems, Inc.
InventorsMichael Turner, Waikit Fung, Oliver Graudejus, Doug Winandy
Life of this patent
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Abstract
A method for depositing a doped silicon dioxide layer is provided that allows the dopant concentration in the silicon dioxide layer to be controlled throughout the layer. By controlling the dopant concentration throughout the layer the etch profile of contact holes etched into the layer can be controlled and footing can be prevented or eliminated. During the deposition of the silicon dioxide, the amount of dopant is increased as the temperature of the wafer is increased and held constant while the temperature of the wafer is constant.
Claims23
A method for depositing a doped silicon dioxide layer onto a wafer comprising:
- introducing a dopant precursor gas having a dopant precursor gas flow rate and a silicon-containing gas having a silicon-containing gas flow rate into a plasma within a deposition chamber, wherein a ratio of the dopant precursor gas flow rate to the silicon-containing gas flow rate has an initial value;
- increasing the ratio within the deposition chamber from the initial value to a final value during an initial deposition period;
- and
- maintaining the ratio within the deposition chamber at the final value during a final deposition period,
- wherein during the initial deposition period and the final deposition period the dopant precursor gas and the silicon-containing precursor gas react in the plasma to form the doped silicon dioxide layer on the wafer, and wherein the initial value of the ratio is determined by:
- measuring a concentration of dopant incorporated into a portion of a silicon dioxide layer as a function of the ratio for a first series of test depositions performed at a constant temperature;
- repeating the measurement of dopant concentration for a second series of test depositions performed at a different constant temperature;
- and
- measuring a temperature profile of the wafer during a third test deposition wherein the temperature is not held constant.
6 more elements
A method for depositing a doped silicon dioxide layer comprising:
- introducing a dopant precursor gas and a silicon-containing gas into a plasma at a dopant precursor gas flow rate and a silicon-containing gas flow rate for a deposition period;
- and
- during the deposition period, adjusting a ratio of the dopant precursor gas flow rate and the silicon-containing gas flow rate as a function of wafer temperature, whereby the dopant precursor gas and silicon-containing gas react in the plasma to form the doped silicon dioxide layer having a defined dopant concentration, wherein a set of values of the ratio to be used during the deposition are determined by
- measuring a concentration of dopant incorporated into a portion of a silicon dioxide layer as a function of the ratio for a first series of test depositions performed at a constant temperature;
- repeating the measurement of dopant concentration for a second series of test depositions performed at a different constant temperature;
- and
- measuring a temperature profile of the wafer during a third test deposition wherein the temperature is not held constant.
4 more elements
A method for depositing a doped silicon dioxide layer onto a wafer, the method comprising:
- introducing a dopant precursor gas having a dopant precursor gas flow rate and a silicon-containing gas having a silicon-containing gas flow rate into a plasma, wherein a ratio of the dopant precursor gas flow rate to the silicon-containing gas flow rate has an initial value;
- increasing the ratio from the initial value to a final value during an initial period;
- determining a duration of the initial period by measuring a temperature of the wafer during a test deposition of a doped silicon dioxide layer, wherein the duration is the time required for the temperature to reach an essentially constant value;
- and
- maintaining the ratio at the final value during a final period,
- wherein during the initial period and the final period the dopant precursor gas and the silicon-containing precursor gas react in the plasma to form the doped silicon dioxide layer on the wafer, and wherein the initial value of the ratio is determined by:
- measuring a concentration of dopant incorporated into a portion of a silicon dioxide layer as a function of the ratio for a first series of test depositions performed at a constant temperature;
- repeating the measurement of dopant concentration for a second series of test depositions performed at a different constant temperature;
- and
- measuring a temperature profile of the wafer during a third test deposition wherein the temperature is not held constant.
7 more elements
A method for depositing a doped silicon dioxide layer onto a wafer, the method comprising:
- introducing a dopant precursor gas having a dopant precursor gas flow rate and a silicon-containing gas having a silicon-containing gas flow rate into a plasma, wherein a ratio of the dopant precursor gas flow rate to the silicon-containing gas flow rate has an initial value;
- increasing the ratio from the initial value to a final value during an initial period;
- maintaining the ratio at the final value during a final period, wherein during the initial period and the final period the dopant precursor gas and the silicon-containing precursor gas react in the plasma to form the doped silicon dioxide layer on the wafer;
- and
- measuring a concentration of dopant incorporated into a portion of a silicon dioxide layer as a function of the ratio for a first series of test depositions performed at a constant temperature;
- repeating the measurement of dopant concentration for a second series of test depositions performed at a different constant temperature;
- and
- measuring a temperature profile of the wafer during a third test deposition wherein the temperature is not held constant, whereby the initial value of the ratio is determined.
5 more elements
A method for depositing a doped silicon dioxide layer, the method comprising:
- introducing a dopant precursor gas and a silicon-containing gas into a plasma at a dopant precursor gas flow rate and a silicon-containing gas flow rate for a deposition period;
- adjusting, during the deposition period, a ratio of the dopant precursor gas flow rate and the silicon-containing gas flow rate as a function of wafer temperature, whereby the dopant precursor gas and the silicon-containing gas react in the plasma to form the doped silicon dioxide layer having a defined dopant concentration;
- measuring a concentration of dopant incorporated into a portion of a silicon dioxide layer as a function of the ratio for a first series of test depositions performed at a constant temperature;
- repeating the measurement of dopant concentration for a second series of test deposition performed at a different constant temperature;
- and
- measuring a temperature profile of the wafer during a third test deposition wherein the temperature is not held constant,
- whereby a set of values of the ratio to be used during the deposition are determined.
4 more elements
Dependencies are inferred from the claim text.