Plasma mediated ashing processes
A plasma and ashing technology, which is applied in the photoplate making process of patterned surface, photosensitive material processing, semiconductor/solid-state device manufacturing, etc.
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Embodiment 1
[0083] In this example, photoresist coated onto a silicon substrate was exposed to nitrous oxide stripping chemistry in a commercially available RapidStrip 320 plasma ashing tool from Axcelis Technologies. The photoresist was i-line photoresist and was deposited on a silicon substrate with a thickness of 1.9 microns. The plasma chemistry was formed by flowing nitrous oxide gas into the plasma ashing tool at 7 standard liters per minute (slm) at a pressure of 1 Torr, a temperature of 240° C., and a power setting of 3500 watts.
[0084] Ash rate, uniformity across wafer, and oxide growth of nitrous oxide plasma lift-off process compared to oxygen-free reducing plasma (forming gas) and oxygen-based plasma. A gas mixture of forming gas (nitrogen with 3% hydrogen) was flowed into the plasma ashing tool at a flow rate of 7 slm to form a reducing plasma at a pressure of 1 Torr, a temperature of 240° C., and a power setting of 3500 W. Using 90% oxygen (O 2 ) and 10% forming gas (nit...
Embodiment 2
[0088] In this example, adding a small amount of CF 4 to different plasma gas mixtures,
[0089] And processed in RapidStrip320 plasma ashing tool. Silicon substrates were exposed to different plasma chemistries and the oxide growth was measured. The results are shown in Table 1 below. In each example, the gas mixture was flowed to the plasma ashing tool using a flow rate of 7 slm at a pressure of 1 Torr and a power setting of 3500 Watts to form various plasmas.
[0090] Table 1
[0091]
[0092] As shown in the table, a small amount of CF was added during plasma formation as evidenced by oxide growth 4 This results in minimized substrate losses and, advantageously, the generation of more energetic species can be expected, which can effectively increase the ashing rate relative to the results observed in Example 1 . CF 4 / N 2 The plasma of O has the highest ratio of reactive nitrogen to reactive oxygen species, which also shows the least amount of oxidation.
Embodiment 3
[0094] In this example, for plasmas formed from nitrous oxide (i.e., labeled as a new technology), compared with the prior art from O with and without a small amount of carbon tetrafluoride 2 Substrate damage was measured in terms of silicon loss, oxide growth, and oxide loss using a RapidStrip320 plasma ashing tool compared to plasma formed from a / forming gas mixture. The forming gas component was nitrogen with 3% hydrogen. The results are shown in Figure 5A . In each example, the gas mixture was flowed to the plasma ashing tool using a flow rate of 7 slm at a pressure of 1 Torr, a temperature of 240° C., and a power setting of 3500 watts to form various plasmas. Substrate damage included (i) silicon loss from silicon-on-insulator (SOI) test structures, (ii) silicon-oxide growth on bare silicon test wafers and silicon-oxide loss from silicon thermal oxidation test wafers. Boxes (b) and (c) compare scanning electron microscope images of p-MOS after high-dose ion implantat...
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