Variable transmission focal mask for lens heating compensation
First Claim
1. A semiconductor fabrication alignment and exposure equipment comprising:
- an exposure and alignment unit including a light source and a lens;
a variable transmission mask under the lens to at least indirectly measure focus and adjust the focus in real time in response to determining that the focus is out of specification; and
a stage on which a wafer is placed for exposure to the light source through one of a mask and a reticle.
1 Assignment
0 Petitions
Accused Products
Abstract
A variable transmission focal mask to compensate lens heating is disclosed. A semiconductor fabrication alignment and exposure equipment includes an exposure and alignment unit, a variable transmission mask, and a stage. The unit has a light source and a lens. The mask is under the lens, and at least indirectly measures focus. The mask further can adjust the focus in real time in response to determining that the focus is out of specification. A wafer is placed on the stage for exposure to the light source through a mask or a reticle. The variable transmission mask normally has a substantially high transmission of light rating that can be adjusted downward to adjust the focus. For example, the mask can be a liquid crystal display (LCD) that can be darkened to so reduce its transmission of light rating.
10 Citations
20 Claims
-
1. A semiconductor fabrication alignment and exposure equipment comprising:
-
an exposure and alignment unit including a light source and a lens;
a variable transmission mask under the lens to at least indirectly measure focus and adjust the focus in real time in response to determining that the focus is out of specification; and
a stage on which a wafer is placed for exposure to the light source through one of a mask and a reticle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A lens heating compensation mechanism for a semiconductor fabrication and exposure equipment comprising:
-
a sensor to at least indirectly measure focus;
a variable transmission mask under a lens of the equipment, normally having a substantially high but adjustable transmission of light rating; and
a mask adjuster to adjust the transmission of light rating downward to adjust the focus in response to the sensor determining that the focus is out of specification. - View Dependent Claims (12, 13, 14, 15)
-
-
16. A method comprising:
-
at least indirectly measuring focus of a semiconductor fabrication exposure and alignment equipment; and
in response to determining that the focus is out of specification, adjusting in real time a transmission of light rating of a variable transmission mask below a lens of the equipment, to adjust the focus. - View Dependent Claims (17, 18, 19, 20)
-
Specification