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]] | ||
There is one [[Specific Process Knowledge/Thin film deposition/B3 Furnace LPCVD TEOS|LPCVD furnace]] for deposition of TEOS at Danchip. The furnace was installed in 1995 and can handle 4" wafers. | |||
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. | ||
There one standard process for deposition on the LPCVD TEOS furnace called TEOS. Anyway there are two standby recipe, which used for load and unload the wafers : one called "Standby" for standard process and other one called "Stb-slw" which is for unloading thicker oxides. And on this recipe the furnace will be opened significantly slower than normal standby recipe. Thick TEOS layers have a tendency to form cracks when they are moved to fast out from 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. | 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. | ||