Specific Process Knowledge/Thin film deposition/Deposition of Silicon Oxide/Deposition of Silicon Oxide using LPCVD TEOS: Difference between revisions
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[[Image:teos1.jpg|300x300px|thumb|Figure 1: TEOS structure]] | [[Image:teos1.jpg|300x300px|thumb|Figure 1: TEOS structure]] | ||
[[Image:teos2.JPG|300x300px|thumb|Figure 2: TEOS deposited in a trench etched in Silicon]] | [[Image:teos2.JPG|300x300px|thumb|Figure 2: TEOS deposited in a trench etched in Silicon]] | ||
Danchip have one [[Specific Process Knowledge/Thin film deposition/B3 Furnace LPCVD TEOS|LPCVD furnace]] for deposition of TEOS: The furnace was installed in 1995 and can handle 4" wafers. It is furthermore possible to dope the TEOS with | Danchip have one [[Specific Process Knowledge/Thin film deposition/B3 Furnace LPCVD TEOS|LPCVD furnace]] for deposition of TEOS: The furnace was installed in 1995 and can handle 4" wafers. It is furthermore possible to dope the TEOS with Boron. | ||
TEOS is Tetra-Ethyl-Ortho-Silicate, it is also sometimes referred to as Tetra-Ethoxy-Silane. The difference between TEOS and Silane is essentially that is TEOS the silicon atom is already oxidised. Therefore the conversion of TEOS to Silicon dioxide is a rearrangement rather than an oxidation. As can be seen from figure 1 what is basically required to deposit Silicon dioxide is a removal of two oxygen atoms for that a relative high temperature of 725 <sup>o</sup>C. | TEOS is Tetra-Ethyl-Ortho-Silicate, it is also sometimes referred to as Tetra-Ethoxy-Silane. The difference between TEOS and Silane is essentially that is TEOS the silicon atom is already oxidised. Therefore the conversion of TEOS to Silicon dioxide is a rearrangement rather than an oxidation. As can be seen from figure 1 what is basically required to deposit Silicon dioxide is a removal of two oxygen atoms for that a relative high temperature of 725 <sup>o</sup>C. | ||
On the | On the LPCVD TEOS furnace there are two standard processes for deposition, one for thin oxides called TEOSPNE and one for thicker oxides called TEOSSLOW. The only difference is that in the case of the TEOSSLOW recipe the furnace opens significantly slower. Thick TEOS layers have a tendency to form cracks if they are moved to fast out of the furnace. | ||
TEOS can be used as an alternative to thermally grown or PECVD oxide, it has a dielectric constant of 3.56 (For thermal oxide it is 3.46). Furthermore TEOS has a very high surface mobility enabling it to fill holes that has a large aspect ratio and leaving the surface quite smooth see figure 2, hence it also covers corners and side walls very well. | |||
==Process parameters for the two standard deposition recipes on the TEOS furnace:== | ==Process parameters for the two standard deposition recipes on the TEOS furnace:== | ||