Specific Process Knowledge/Etch/Etching of Bulk Glass: Difference between revisions
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At | == Comparing methods for etching bulk glass at DTU Nanolab == | ||
The set-up consists of a 5L | |||
Etching of glass can be done either wet or dry. Wet etching is done with HF. Dry etching can be done either with [[Specific Process Knowledge/Etch/AOE (Advanced Oxide Etch)|AOE]], ASE or Pegasus 4 using fluorine chemistry (only fused silica) or with [[Specific Process Knowledge/Etch/IBE⁄IBSD Ionfab 300|IBE]] by sputtering with Ar ions and/or using fluorine chemistry. | |||
At DTU Nanolab, we have two types of bulk glass substrates: Borosilicate glass (Borofloat 33 (like pyrex)) and fused silica glass which in cleanliness is similar to quartz. Both types are etched wet in a special set-up placed in a fumehood using a concentrated HF-solution (isotropic etch). | |||
The set-up consists of a 5L plastic beaker placed on a stirring plate (magnetic stirring) and a special horizontal wafer holder. Normally a 40% pre-mixed HF solution is used. | |||
Masking materials and pre-treatment of the glass surface prior to the deposition of the masking material is a special concern in particular for deep etching (> 10µm). | Masking materials and pre-treatment of the glass surface prior to the deposition of the masking material is a special concern in particular for deep etching (> 10µm). | ||
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Due to the high cleanliness fused silica is allowed access to basically all machines meaning that e.g. LPCVD silicon can be deposited as masking material. This is an excellent mask even for quite deep etches. | Due to the high cleanliness fused silica is allowed access to basically all machines meaning that e.g. LPCVD silicon can be deposited as masking material. This is an excellent mask even for quite deep etches. | ||
Regarding borosilicate glass masking is more tricky. Sputtered Si, Cr or Cr/Au can be used. It is a | Regarding borosilicate glass masking is more tricky. Sputtered Si, Cr or Cr/Au can be used. It is a challenge to avoid delamination, pinholes and cracks in the masking material. | ||
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*~75 nm/min (Thermal oxide) in BHF | *~75 nm/min (Thermal oxide) in BHF | ||
*~ | *~80 nm/min (Thermal oxide) in BOE 7:1 Etchant VLSI with Surfactant | ||
*~25 nm/min (Thermal oxide) in 5%HF | *~25 nm/min (Thermal oxide) in 5%HF | ||
*~3-4µm/min in 40%HF | *~3-4µm/min in 40%HF | ||
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*Process dependent | *Process dependent | ||
*Expected range: ~ less than | *Expected range: ~ less than 20 nm/min - ~200 nm/min | ||
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*Process dependent | *Process dependent | ||
*Expected range: ~ less than | *Expected range: ~ less than 230 nm/min - ~550 nm/min | ||
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*Process dependent | *Process dependent | ||
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!Substrate size | !Substrate size | ||
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*<nowiki>#</nowiki>1-25 | *<nowiki>#</nowiki>1-25 100 mm wafers in our 100mm bath | ||
*What can be fitted in a plastic beaker | *What can be fitted in a plastic beaker | ||
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*DUV resist | *DUV resist | ||
*E-beam resist | *E-beam resist | ||
*Other metals if they cover less than 5% of the wafer area | *Other metals if they cover less than 5% of the wafer area | ||
*Quartz/fused silica | *Quartz/fused silica | ||
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