High purity buffered HF etchants for thermally grown or deposited silicon dioxide films. Transene silicon dioxide etchants are ideal for semiconductor applications requiring minimal undercutting and broad compatibility.
BUFFER-HF-IMPROVED
Highest etch rate for thermally grown silicon dioxide films. Also suitable for deposited SiO2.
BD ETCHANT
Buffered dip etchant for polysilica glass (PSG) and borosilica glass (BSG) systems. The etch rate is variable depending upon PSG or BSG composition.
SILOXIDE ETCH
Selective, controlled etching for SiO2 films deposited from silanes or ethylorthosilicate.
TIMETCH
Optimum control for etching of deposited silicon dioxide films.
SILOX VAPOX III
Etches deposited oxides on silicon. Saturated with aluminum to minimize attack on metallic substrates.
Room Temperature
Crystallization occurs below 10 °C.
Principal Ion
HF2 ligand
Heavy Metals
0.5 ppm
* Etch rate may vary depending upon silica film structure
USE OF BUFFER HF IMPROVED
BUFFER HF IMPROVED dissolves silica films (both thermally grown and silane SiO2) produced on the surfaces of silicon and exposed by photolithography. It also is capable of dissolving doped silica films such as phosphosilica and borosilica glasses as formed in semiconductor processing. The overall chemical reaction is: 4HF + SiO2 -> SiF4 + 2H2O
For trouble-free operation BUFFER HF IMPROVED is recommended in the new technologies for manufacture of semiconductor planar and mesa devices. it is compatible with both negative and positive photoresists. Excellent results with good reproducibility are simple to achieve without undercutting marked oxides, surface staining or device degradation by metallic impurities.
INSTRUCTIONS
Most practical oxide passivation layers range from 2000 Å to 5000 Å in thickness, and good results are obtained by exposure in BUFFER HF IMPROVED for 2 to 5 minutes at room temperature. Exposure time may be decreased or increased if necessary. BUFFER HF IMPROVED should be rinsed off with deionized water. 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.
Note: etch rate is dependent upon composition of PSG and BSG.
APPLICATION:
Employed as a dip etch to remove SiO2 films from contacts without the disturbance of the PSG film. BD Etchant is used prior to metallization of the contact holes of the silicon transistor wafers followed by water and alcohol rinses.
Siloxide Etchant is used in the photolithographic process for the manufacture of semiconductor devices and integrated circuits. Deposited SiO2 functions in these applications as a passivating dielectric or as an etch mask in conjunction with silicon nitride passivation. Typical SiO2 deposits are on the order of 2000 Å thick.
Conventional buffered HF solutions used to etch thermally grown SiO2 should not be used for deposited SiO2 films. Deposited SiO2 films are produced from the oxidation of silane or by the pyrolytic hydrolysis of ethyl orthosilicate. These deposited silica films etch much faster as compared to thermally grown SiO2. Siloxide Etchant gives the necessary etch control for these deposited SiO2 films.
ETCH CONTROL OF DEPOSITED SiO2 FILM WITH SILOXIDE ETCHANT
