The etch-rate of silica ranges from 150 to 700 nm/min on a 150 mm wafer with the usual etch load (10–15%). Various glass etching processes with various etch mask materials are listed in Table 21.4. Table 21.4. Etch parameters and Etch Rates for Oxide and Mask Materials (nm/min)
20:1 Buffered oxide etch | Stanford Nanofabrication Facility 38% ammonium fluoride (NH4F), 2% hydrofluoric acid (HF), 60% water (H2O) SNF Cleanroom Paul G Allen L107 : Manual wet etching of non-standard materials. Etching Mechanism of Vitreous Silicon Dioxide in HF-Based Apr 25, 2000 RIWKH'LVVROXWLRQRI6L2 LQ$FLGLF)OXRULGH6ROXWLRQV concentrated HF to solutions highly buffered with NH4F, are being used for SiO2 dissolution through photoresist masks. Recently, Dey, Lundgren, and Har- relI (1) reported on the temperature and agitation dependence of the rate of SiO2 dissolution in one of the buffered HF solutions whose composition they
Silicon nitride films have a reasonably fast etch rate (200-300 Å/min) in concentrated HF (48%), but it was found that the ordinary photoresist materials, as used for SiO 2, do not mask sufficiently against the concentrated HF. Even if a good etching mask for concentrated HF were available, the etching of a contact hole in Si 3N
Used for etching of SiO2. Due to the higher PH value in contrast to unbuffered HF it gives better results in combination with photo resists. The etch rate on SiO2 is (depending on temperature and SiO2 morphology) in the range of 70-90 nm per minute. Typical Fields of Application of Buffered Hydrofluoric Acid. BOE is mainly used for etching glasses, quartz and SiO 2 films. The high buffer index of BUFFER HF IMPROVED permits repeated use of the buffer at fixed exposure time. For faster etch rate (approx. 2X) use BUFFER HF IMPROVED at 35 °C. SILICON DIOXIDE THICKNESS VS. A common buffered oxide etch solution comprises a 6:1 volume ratio of 40% NH 4 F in water to 49% HF in water. This solution will etch thermally grown oxide at approximately 2 nanometres per second at 25 degrees Celsius. Temperature can be increased to raise the etching rate. 2.1.6 Let the sample etch for the required length of time. Etch rate will vary with oxide composition and depositions method. You should verify etch rate with your own experiments on your own samples. Etch rate can vary. Ultraetch NP 13:2 Material Etch Rate Source BK7 glass wafer 650 nm/min Measured at Tufts by C. Gray 2007
Wet Etching - National Tsing Hua University
Silicon nitride films have a reasonably fast etch rate (200-300 Å/min) in concentrated HF (48%), but it was found that the ordinary photoresist materials, as used for SiO 2, do not mask sufficiently against the concentrated HF. Even if a good etching mask for concentrated HF were available, the etching of a contact hole in Si 3N 20:1 Buffered oxide etch | Stanford Nanofabrication Facility 38% ammonium fluoride (NH4F), 2% hydrofluoric acid (HF), 60% water (H2O) SNF Cleanroom Paul G Allen L107 : Manual wet etching of non-standard materials. Etching Mechanism of Vitreous Silicon Dioxide in HF-Based Apr 25, 2000 RIWKH'LVVROXWLRQRI6L2 LQ$FLGLF)OXRULGH6ROXWLRQV concentrated HF to solutions highly buffered with NH4F, are being used for SiO2 dissolution through photoresist masks. Recently, Dey, Lundgren, and Har- relI (1) reported on the temperature and agitation dependence of the rate of SiO2 dissolution in one of the buffered HF solutions whose composition they