Determining layer thickness using photoelectron spectroscopy

A method for determining a thickness of a layer in a multi-layer structure comprising:

• determining a first predictive intensity function for a first characteristic electron species of the layer dependent on the thickness of the layer;
• determining a second predictive intensity function for a second characteristic electron species of the multi-layer structure;
• measuring a first intensity of the first characteristic electron species and a second intensity of the second characteristic electron species using x-ray photoelectron spectroscopy (XPS) or other electron spectroscopy;
• determining a ratio of the first and second predictive intensity functions;
• and
• iterating the ratio to determine the thickness of the layer, wherein the first intensity of the first characteristic electron species and the second intensity of the second characteristic electron species are also used to determine the thickness of the layer, wherein if the layer is beneath a second layer of the multi-layer structure, determining the first predictive intensity function including an attenuation factor dependent on a thickness of the second layer, wherein the second layer comprises an oxide of silicon, wherein the thickness of the second layer is given by:
• tSiO2=sin(α) ln[(I(Si0)/I(Si4+)*k+1].

A method for determining a thickness of a layer in a multi-layer structure comprising:

• bombarding the structure with radiation;
• analyzing electrons ejected by the structure including a first electron species ejected by the layer and a second electron species ejected by the structure, wherein the multi-layer structure includes the layer over a second layer comprising a silicon oxide;
• determining a first predictive intensity function for the first electron species dependent on a thickness of the layer and a second predictive intensity function for the second electron species;
• formulating a ratio of the first and second predictive intensity functions;
• iterating the ratio to determine the thickness of the layer;
• determining a thickness of the second layer using tSiO2=sin(α) ln[(I(Si0) /I(Si4+)* k+1];
• and
• determining a thickness of the layer using the ratio,
• wherein the first electron species is emitted by the layer and the first predictive intensity function is given by
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• wherein the second predictive intensity function is given by:
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A method for determining a thickness of a layer in a multi-layer structure comprising:

• bombarding the structure with radiation;
• analyzing electrons ejected by the structure including a first electron species and a second electron species, wherein the first electron species and the second electron species are both emitted by the layer;
• determining a first predictive intensity function for the first electron species dependent on a thickness of the layer and a second predictive intensity function for the second electron species dependent on the thickness of the layer;
• formulating a ratio of the first and second predictive intensity functions;
• and
• iterating the ratio to determine the thickness of the layer.

A machine readable medium having stored thereon executable program code which, when executed, causes a machine to perform a method for determining a thickness of a layer using electron spectroscopy, the method comprising:

• determining a first predictive intensity function for a first electron species of the layer dependent on the thickness of the layer;
• determining a second predictive intensity function for a second electron species of the layer dependent on the thickness of the layer;
• determining a ratio of the first and second predictive intensity functions;
• and
• iterating the ratio to determine the thickness of the layer, wherein a first measured intensity of the first electron species and a second measured intensity of the second electron species are also used to determine the thickness of the layer.