X-Ray photoelectron spectroscopy study of phosphorus silicate glasses

Abstract

Samples of phosphorus silicate glass (PSG) layers were deposited in a class 100 clean room in two kinds of industrial type reactors: by plasma enhanced chemical vapour deposition (PECVD) and micro pressure chemical vapour deposition (μPCVD) at working temperatures of 380 °C and 430 °C, respectively. After deposition the samples were subjected to rapid thermal annealing (RTA) in a vacuum at 5×10 −3 Pa and temperatures of 800 °C, 1000 °C, 1200 °C and 1400 °C for 15–180 s. X-Ray photoelectron spectroscopy (XPS) investigations show that phosphorous oxides pass through a phase transition and evaporate, while silicon oxides evaporate and decompose. The rate of etching in ‘p’ etcher of μPCVD-PSG layer before annealing is 1023 Å min −1, after RTA at 800 °C for 15 s it is 909 Å min −1, and after annealing for 3 min it is 690 Å min −1. In the case of RTA at 1000, 1200 and 1400 °C for 3 min the etching rates are 660, 469 and 351 Å min −1, respectively, i.e. RTA results in considerable decrease of rate of etching. The same behaviour shows curves related to PSG layers obtained by PECVD. IR spectra show that PO bond vibration at 1320 cm −1 appears at temperatures of annealing T≥1000 °C and time interval 60–180 s. A correlation between PSG layers characteristics and conditions of RTA is found.