Patterned ZnS Thin-Film Growth using KrCl Excimer Lamp on the Zn Nuclei
- PDF / 1,642,947 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 34 Downloads / 144 Views
PRINCIPLES OF THIS EXPERIMENT
100O
In this experiment, we have used a
two step process to produce ZnS thin film formation. The first step is Zn nucleation on a silicon substrate using an ArF excimer laser. Zn(CH3 )2 is used as the material gas. The second step is ZnS thin film growth using a KrCI excimer lamp. H2S and
I DMZ: 0.5 Torr Vapor phase Adsorption layer zi7
Zn(CH 3) 2 are the material gases used in this step. The vapor pressure of Zn(CH 3) 2 is 1
1 H 2 S:5Torr
-" . -
'Vapor phase
|
!
atm at room temperature. Fig.1 shows UVspectrograms of the material gases. As shown in Fig.l, these gases have strong absorption bands at both 222 nm (KrCl
190 300 400 WAVELENGTH (nm) Fig. 1. Absorption of reaction gases. 147
Mat. Res. Soc. Symp. Proc. Vol. 585 © 2000 Materials Research Society
excimer lamp) and 193 am (ArF excimer laser). Zn Nucleation In this experiment, we positioned the substrate in the reaction chamber and filled the chamber with Zn(CH 3)2. We then exhausted the chamber to high vacuum. This process forms several molecular DMZ layers onto the substrate by vacuum adsorption (as shown in Fig.
P MU
ArF Excitat L&er ( 193 rim)
Eth"O'
Mask Patern
GW= OP.to VAMUM
BAM%%W
FJJ.ii,'t' 1KM RAHRM ý
ý
-OtimU ,M#ltaItf
In"NAM"L
Fig. 3. Zn nuclei formation.
Ua•forksDMZ Fig.2. Adsorbed DMZ onto substrate. KrC!Excimer Lamp (222nm)
KrC Excimer Lamp (222nm)
UII14III 00@
0
tCII
ghhh amw .j. kqtT" 7
Fig. 4. Photo-dissociated material gases.
Fig. 5. ZnS film growth.
148
2). We then expose the substrate to a single shot of the ArF Excimer laser through the photomask. This process produces, on the surface of the substrate, a photochemical reaction (which is shown as in Fig. 3) and forms patterned Zn nuclei on the surface of substrate. The photo-chemical equation of this process is shown in (eq. 1):
Zn(CH 3)2
Zn nuclei + 2CH 3
h,-
(1)
Selective growth of a ZnS film onto Zn nuclei In this experiment, we positioned the substrate onto which we had formed patterned Zn nuclei, as described above, into the chamber. We exhausted the chamber to high vacuum and then filled it with the material gases DMZ and H2S. We then irradiated the substrate for 10 minutes with 222 nm light from the KrCl excimer lamp (as shown as Fig. 4).A photochemical reaction (shown in Fig. 5) was produced in which a ZnS thin film was grown selectively onto only the patterned Zn nuclei as above. The photochemical equation of this process is as follows:
H 2S + Zn(CH 3) 2
h
ZnS + 2CH4
(2)
EXPERIMENTAL CONDITIONS AND RESULTS Zn nucleation Fig. 6 shows the equipment for this step of the experiment. The substrate is a Si wafer. The material gas (DMZ) was filled at 100 Torr, and then exhausted to high vacuum. This process forms several molecular Zn(CH 3)2 layers onto the substrate by vacuum adsorption. We then exposed the substrate to a single shot from an ArF excimer laser at 30 mJ/cm 2 through a patterned photo-mask positioned along the Z-axis above the substrate as shown in Fig. 6. Patterned Zn •
Mirror
Reticle Pattern L
Data Loading...
