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Specific Process Knowledge/Thin film deposition/Deposition of Silicon Oxide/Deposition of Silicon Oxide using LPCVD TEOS: Difference between revisions

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On the furnace there are also two standby recipes, which are used for wafer loading and unloading. One standby recipe is called "STANDBY". The other standby recipe is called "STB-SLOW", and this is being used, if a thicker TEOS oxide layer (> 1 µm) is deposited, because the furnace then has to open slower to avoid stress and thus cracks in the deposited film.
On the furnace there are also two standby recipes, which are used for wafer loading and unloading. One standby recipe is called "STANDBY". The other standby recipe is called "STB-SLOW", and this is being used, if a thicker TEOS oxide layer (> 1 µm) is deposited, because the furnace then has to open slower to avoid stress and thus cracks in the deposited film.


==Process parameters for the two standard deposition recipes on the TEOS furnace:==
==Process parameters standard deposition recipes and the standby recipes on the TEOS furnace:==


{| border="1" cellspacing="0" cellpadding="4"  
{| border="1" cellspacing="0" cellpadding="4"  
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|-  
|-  
| "STANDBY" and "STB-SLOW"  
| "STANDBY" and "STB-SLOW"  
(standby recipe)
(standby recipes)
| 4" wafers
| 4" wafers
1-17 wafers
1-15 wafers
| 560  
| 560 <sup>o</sup>C
(wafer loading temperature)
(wafer loading temperature)
| Atmospheric pressure
| Atmospheric pressure
| 0
(wafer loading pressure)
| 0
| 0 sccm
| 0 sccm
| For wafer loading and unloading
| For wafer loading and unloading
|-
|-
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(deposition recipe)
(deposition recipe)
| 4" wafers
| 4" wafers
1-17 wafers
1-15 wafers
| 715, 712, 720  
| 715, 712, 720 <sup>o</sup>C
(temperature zone 1, 2, 3)
(temperature zone 1, 2, 3)
| 175
| 175 mTorr
| 50
| 50 sccm. <i>The exact flow is not know - the setpoint is much lower than 50 sccm, but the MFC is not calibrated for TEOS</i>
| 0
| 0 sccm
| Process recipe
| Process recipe
|}
|}


==Deposition rate and refractive index:==
==Deposition rate and refractive index:==


The deposition rate is normally a little below 10 nm/min. But especially for short depositions, the deposition rate is higher and depends on the deposition time. The mean reason for this is that there is some TEOS (about 20-30 nm) will be deposited during the pre- and post-deposition steps, and this does not count as deposition time. The pre-deposition step is when the TEOS is introduced into the furnace tube before the deposition, and the pre-deposition step is when the TEOS gas line and mass flow controller are emptied through the furnace tube after the deposition.  
The deposition rate is normally a little below 10 nm/min - See process log in LabManager. But especially for short depositions, the deposition rate is higher and depends on the deposition time. The main reason for this is that there is some TEOS (about 20-30 nm) being deposited during the pre- and post-deposition steps in the recipe, and this does not count as deposition time. The post-deposition step is when the TEOS is introduced into the furnace tube before the deposition, and the pre-deposition step is when the TEOS gas line and MFC are emptied through the furnace tube after the deposition.  


Before you use the furnace, it is recommended to look at process log to find the latest deposition rates.
Before you use the furnace, it is recommended to look at process log to find the latest deposition rates.
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TEOS has compressive stress (around 100-300 MPa).
TEOS has compressive stress (around 100-300 MPa).


==Using LPCVD TEOS oxide as a masking material for KOH etching==


==Using LPCVD TEOS as a masking material for KOH etching==
It is possible to use LPCVD TEOS oxide as a masking layer for KOH etching. However, it is not as suitable as LPCVD silicon nitride for deep KOH etching, as the etch rate for TEOS oxide is higher than the etch rate for silicon nitride.
 
It is possible to use LPCVD TEOS pxide as a masking layer for KOH etching. However, it is not as suitable as LPCVD silicon nitride for deep KOH etching, as the the etch rate for TEOS oxide is higher than the etch rate for silicon nitride.
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