US 5,963,783 A · In-line detection and assessment of net charge in PECVD silicon dioxide (oxide) layers

Abstract

The present method provides for the detection and assessment of the net charge in a PECVD oxide layer deposited on a surface of a semiconductor substrate. Electrical potential differences across PECVD oxide layers on as-produced semiconductor substrates are measured. Resultant PECVD oxide charge derivative values are plotted on an control chart and compared to calculated control parameters. All measurement techniques are non-contact and non-destructive, allowing them to be performed on as-processed semiconductor substrates at any time during or following a wafer fabrication process. In a first embodiment, a contact potential difference V.sub.CPD between a vibrating electrode and the semiconductor substrate is measured while the semiconductor substrate beneath the vibrating electrode is subjected to a constant beam of high intensity illumination. The resultant value of V.sub.CPD is equal to the electrical potential difference across the PECVD oxide layer V.sub.OX (plus a constant). In a second embodiment, the semiconductor substrate is not illuminated curing the measurement of V.sub.CPD. A conventional SPV apparatus is used to measure the surface barrier potential V.sub.SP of the semiconductor substrate. Subtracting the measured value of V.sub.SP from the measured value of V.sub.CPD yields the value of V.sub.OX (plus a constant).

Claims11

Dependent claims

A method of monitoring a PECVD oxide layer deposition process with respect to net charge contained within the PECVD oxide layers, comprising the steps of:

depositing upon a surface of a plurality of semiconductor substrates a respective plurality of PECVD oxide layers;
for each of the plurality of semiconductor substrates:
positioning a vibrating electrode above the PECVD oxide layer, said vibrating electrode being separated from the semiconductor substrate by the PECVD oxide layer and an air gap between the PECVD oxide layer and the vibrating electrode;
monitoring a sinusoidal electrical signal produced between the vibrating electrode and the semiconductor substrate in accordance with sinusoidally varying distance between the vibrating electrode and the semiconductor substrate;
establishing a direct current (DC) potential between the vibrating electrode and the semiconductor substrate;
subjecting the semiconductor substrate to a continuous beam of high intensity illumination;
adjusting the magnitude of the direct current (DC) potential until the amplitude of the sinusoidal electrical signal produced between the vibrating electrode and the semiconductor substrate becomes zero;
recording a PECVD oxide charge derivative value measured as the direct current (DC) potential during times when the amplitude of the sinusoidal electrical signal produced between the vibrating electrode and the semiconductor substrate becomes zero;
producing a control chart from recorded PECVD oxide charge derivative values in order to compare said PECVD oxide charge derivative values to a set of control parameters, thereby determining the relative net charges within the PECVD oxide layers.

6 more elements

A method of monitoring a PECVD oxide layer deposition process with respect to net charge contained within the PECVD oxide layer, comprising the steps of:

depositing upon a surface of a plurality of semiconductor substrates a respective plurality of PECVD oxide layers;
for each of the plurality of semiconductor substrates:
measuring and recording a contact potential difference between a vibrating electrode and the semiconductor substrate;
measuring and recording a surface barrier potential of the semiconductor substrate;
calculating a PECVD oxide charge derivative value by subtracting the recorded value of the surface photovoltage from the recorded value of contact potential difference;
producing a control chart from recorded PECVD oxide charge derivative values in order to compare said PECVD oxide charge derivative values to a set of control parameters, thereby determining the relative net charges within the PECVD oxide layers.

3 more elements

Dependencies are inferred from the claim text.

In-line detection and assessment of net charge in PECVD silicon dioxide (oxide) layers

Life of this patent

In-line detection and assessment of net charge in PECVD silicon dioxide (oxide) layers

Life of this patent

Abstract

Claims11