Substrate laser marking
A method for forming a feature in a substrate, where residue within the feature can be easily removed. An upper sidewall portion of the feature is formed, where the upper sidewall portion forms a void in the substrate. The upper sidewall portion has an upper sidewall angle. A lower sidewall portion of the feature is formed, where the lower sidewall portion forms a void in the substrate. The lower sidewall portion has a lower sidewall angle. The upper sidewall angle of the upper sidewall portion is shallower than the lower sidewall angle of the lower sidewall portion. By forming the feature with a shallower sidewall angle at the top of the feature, any debris within the feature is more susceptible to rinsing, etching, or other cleaning procedures, and thus the feature is more easily cleaned than standard features having relatively steeper sidewalls.
1. A method for forming a feature in a substrate, where residue within the feature can be easily removed, the method comprising the steps of:
forming an upper sidewall portion of the feature by laser ablation, the upper sidewall portion forming a void in the substrate, where the upper sidewall portion has an upper sidewall angle, and
forming a lower sidewall portion of the feature by laser ablation, the lower sidewall portion forming a void in the substrate, where the lower sidewall portion has a lower sidewall angle,
where the upper sidewall angle of the upper sidewall portion is shallower than the lower sidewall angle of the lower sidewall portion.
2. The method of claim 1 , wherein the upper sidewall angle of the upper sidewall portion is from about thirty degrees to about sixty degrees.
3. The method of claim 1 , wherein the lower sidewall angle of the lower sidewall portion is from about sixty degrees to about ninety degrees.
4. The method of claim 1 , wherein the lower sidewall portion is formed before the upper sidewall portion is formed.
5. The method of claim 1 , wherein the feature comprises a blind bore formed in the substrate.
6. The method of claim 1 , wherein the upper sidewall portion has a depth of between about four microns and about eight microns.
7. The method of claim 1 , wherein the lower sidewall portion has a depth of between about four microns and about eight microns.
8. The method of claim 1 , wherein the feature has a depth of no more than about twelve microns.
9. The method of claim 1 , wherein the substrate comprises silicon.
10. A method for forming indicia elements on a substrate, where the indicia elements have a shape that aids in removal of foreign material from the indicia elements on the substrate, the method comprising the steps of:
forming an upper sidewall portion of the indicia elements by laser ablation, the upper sidewall portion forming a void in the substrate, where the upper sidewall portion has an upper sidewall angle,
forming a lower sidewall portion of the indicia elements by laser ablation, the lower sidewall portion forming a void in the substrate, where the lower sidewall portion has a lower sidewall angle,
where the upper sidewall angle of the upper sidewall portion is shallower than the lower sidewall angle of the lower sidewall portion, and
forming the indicia elements in a pattern to form identifying indicia on the substrate.
11. The method of claim 10 , wherein all of the upper sidewall portions of all of the indicia elements are formed prior to forming any of the lower sidewall portions of any of the indicia elements.
12. The method of claim 10 , wherein all of the lower sidewall portions of all of the indicia elements are formed prior to forming any of the upper sidewall portions of any of the indicia elements.
13. The method of claim 10 , wherein a preceding one of the indicia elements is completely formed prior to forming a seceding one of the indicia elements.
14. The method of claim 10 , wherein:
the upper sidewall angle of the upper sidewall portion is from about thirty degrees to about sixty degrees,
the lower sidewall angle of the lower sidewall portion is from about sixty degrees to about ninety degrees,
the upper sidewall portion has a depth of between about four microns and about eight microns,
the lower sidewall portion has a depth of between about four microns and about eight microns, and
the indicia element is a blind bore formed in the substrate and has a depth of no more than about twelve microns.