1. A traffic sign comprising:
a post;
a base plate mounted on the post;
at least one panel formed on the base plate, each of the at least one panel being red, yellow, green, or blue; and
at least one letter each formed on the panel, each of the at least one letter being \u201cE\u201d indicating east, \u201cW\u201d indicating west, \u201cS\u201d indicating south, or \u201cN\u201d indicating north.
2. The traffic sign of claim 1, wherein each of the at least one panel is a stylized cross having four equal triangular arms at right angles, each arm with a sharp outer end.
3. The traffic sign of claim 1, wherein each of the at least one panel is formed of a plurality of red, yellow, green, or blue LEDs (light-emitting diodes).
4. The traffic sign of claim 1, wherein each of the at least one panel is a red, yellow, green, or blue light reflective coating.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A method for forming a contact of a semiconductor device, comprising the steps of:
forming a first interlayer dielectric (ILD) layer on a semiconductor substrate having a cell transistor and a lower poly silicon plug thereon;
forming a stacked structure of a barrier layer, a conductive layer and a hard mask nitride film on the first ILD layer, and selectively etching the stacked structure to form a bit line;
forming an oxide film spacer at a sidewall of the bit line;
forming a second ILD layer on the semiconductor substrate including the bit line;
polishing the second ILD layer using CMP slurry having high selectivity for oxide film to expose the hard mask nitride film;
forming a third ILD layer on the semiconductor substrate; and
performing an etching process to form an opening for storage node contact exposing the lower poly silicon plug.
2. The method according to claim 1, wherein the CMP slurry has a pH ranging from 4 to 10.
3. The method according to claim 1, wherein the CMP slurry has a pH ranging from 6 to 8.
4. The method according to claim 1, wherein the CMP slurry comprises distilled water or ultra-pure water as a solvent.
5. The method according to claim 1, wherein the CMP slurry comprises Ceria (CeO2) as an abrasive.
6. The method according to claim 5, wherein an amount of the abrasive ranges from 0.5 to 10 wt % of the CMP slurry.
7. The method according to claim 1, wherein the CMP slurry comprises an organic polymer as an additive.
8. The method according to claim 7, wherein the organic polymer is a polyacrylic acid salt.
9. The method according to claim 7, wherein an amount of the additive ranges from 0.5 to 10 wt % of the CMP slurry.
10. The method according to claim 1, wherein the selectivity ratio of the CMP slurry for nitride film to oxide film ranges of 1:10\u02dc200.
11. The method according to claim 1, wherein the selectivity ratio of the CMP slurry for nitride film to oxide film ranges of 1:30\u02dc200.
12. The method according to claim 1, wherein the barrier layer comprises TiTiN.
13. The method according to claim 1, wherein the conductive layer comprises tungsten.
14. The method according to claim 1, wherein the third ILD layer is formed from a source selected from a group consisting of HDP PSG (high density plasma phosphosilicate glass), BPSG (borophosphosilicate glass), PSG (phosphosilicate glass), HDP USG (high density plasma undoped silicate glass), FSG (fluorosilicate glass), PE-SiH4 (plasma enhanced-silane), LP-TEOS (low pressure-tetraethoxysilicate glass) and PE-TEOS (plasma enhanced-tetraethoxysilicate glass).
15. The method according to claim 1, wherein a thickness of the third ILD layer ranges from 500 to 5000 \u212b.
16. The method according to claim 1, wherein a thickness of the third ILD layer ranges from 500 to 2000 \u212b.