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| HNO<sub>3</sub> : BHF : H<sub>2</sub>O 20 : 1 : 20 | | HNO<sub>3</sub> : BHF : H<sub>2</sub>O 20 : 1 : 20 |
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| bainitially 85 wt% H<sub>3</sub>PO<sub>4</sub> which is heated up to the boiling temperature - ca. 157 <sup>o</sup>C. Water is allowed to boil off thus raising the concentration and the boiling temperature of the solution until a boiling temperature of 180 <sup>o</sup>C is reached. Thereafter, the wafers are submerged into the bath and the water-cooled lid is closed to maintain the concentration and the boiling temperature. In some cases a lower boiling temperature is chosen - typically 160 <sup>o</sup>C - which lowers the etch rate and improves the selectivity R<sub>Si<sub>3</sub>N<sub>4</sub></sub> / R<sub>SiO<sub>2</sub></sub>.
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| | | ===Poly Etch data=== |
| '''NB: Great care has to be taken in this process due to risk of "shock-boiling" '''
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| ===Nitride etch - key facts=== | |
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| {| border="1" cellspacing="0" cellpadding="4" align="left" | | {| border="1" cellspacing="0" cellpadding="4" align="left" |
