OPTICAL ELEMENT MODULE
An optical element module comprising a plurality of module components is provided. The module components comprise an optical element, an optical element holder and a contact element. The optical element has a first coefficient of thermal expansion. The optical element holder holds the optical element via the first contact element and has a second coefficient of thermal expansion, the second coefficient of thermal expansion being different from the first coefficient of thermal expansion. At least one of the module components is adapted to provide at least a reduction of forces introduced into the optical element upon a thermally induced position change in the relative position between the optical element and the optical element holder, the position change resulting from a temperature situation variation in a temperature situation of the plurality of module components.
1 . An optical element module comprising:
an optical element,
an optical element holder and
a first contact element;
the optical element having a first coefficient of thermal expansion;
the optical element holder holding the optical element via the first contact element and having a second coefficient of thermal expansion, the second coefficient of thermal expansion being different from the first coefficient of thermal expansion;
a first contact point being formed on a first module component, the first module component being one of the optical element and the optical element holder;
the first contact element having a second contact point and a third coefficient of thermal expansion;
the first contact point, at a first temperature situation, contacting the second contact point at a first location;
the first contact element contacting a second module component at a second location, the second location, at the first temperature situation, being located at a first contact location distance from the first location;
the second module component being different from the first module component and being one of the optical element and the optical element holder;
at least one of the third coefficient of thermal expansion and the contact location distance being selected such that, at a given second temperature situation different from the first temperature situation, a thermally induced modification in the size of the first contact element with respect to the first temperature situation compensates for the difference between the first coefficient of thermal expansion and the second coefficient of thermal expansion such that, at the second temperature situation, there is substantially no shift between the first contact point and the second contact point.
2 . The optical element module according to claim 1 , wherein the optical element forms the first module component and the optical element holder forms the second module component.
3 . The optical element module according to claim 1 , wherein
the optical element holder comprises a first material and
the first contact element comprises a second material different from the first material.
4 . The optical element module according to claim 1 , wherein
the optical element comprises quartz (SiO 2 ),
the optical element holder comprises Invar, and
the first contact element comprises steel.
5 . The optical element module according to claim 1 , wherein the third coefficient of thermal expansion is considerably higher than the second coefficient of thermal expansion.
6 . The optical element module according to claim 1 , wherein
the optical element mainly extends in a first plane and has a centrally located optical element axis perpendicular to the first plane, and
the first contact point is located at a first contact surface of the optical element, the first contact surface being perpendicular to the optical element axis.
7 . The optical element module according to claim 1 , wherein
the optical element has an outer circumference and
a plurality of first contact elements contacting the optical element and the optical element holder are distributed at the outer circumference.
8 . The optical element module according to claim 7 , wherein
the optical element holder comprises a ring shaped holder unit;
the holder unit extending along the outer circumference of the optical element and contacting the first contact element.
9 . The optical element module according to claim 8 , wherein
a ring shaped frame unit is provided;
the frame unit extending along an outer circumference of the optical element holder and holding the optical element holder via a plurality of deformation uncoupling elements.
10 . The optical element module according to claim 9 , wherein the frame unit comprises a material being, at least with respect to its coefficient of thermal expansion, different from a material the optical element holder comprises.
11 . The optical element module according to claim 1 , wherein
a second contact element is provided;
the second contact element contacting the optical element and the optical element holder and having a fourth coefficient of thermal expansion.
12 . The optical element module according to claim 11 , wherein the second contact element comprises a material being, at least with respect to its coefficient of thermal expansion, different from a material the optical element holder comprises.
13 . The optical element module according to claim 11 , wherein
the optical element comprises quartz (SiO 2 ),
the optical element holder comprises Invar, and
the second contact element comprises steel.
14 . The optical element module according to claim 11 , wherein the fourth coefficient of thermal expansion is considerably higher than the second coefficient of thermal expansion.
15 . The optical element module according to claim 11 , wherein
the optical element has an outer circumference and
a plurality of second contact elements contacting the optical element and the optical element holder are distributed at the outer circumference.
16 . An optical element module comprising:
a plurality of module components;
the module components comprising an optical element, an optical element holder and a contact element;
the optical element having a first coefficient of thermal expansion;
the optical element holder holding the optical element via the first contact element and having a second coefficient of thermal expansion, the second coefficient of thermal expansion being different from the first coefficient of thermal expansion;
at least one of the module components being adapted to provide at least a reduction of forces introduced into the optical element upon a thermally induced position change in the relative position between the optical element and the optical element holder;
the position change resulting from a temperature situation variation in a temperature situation of the plurality of module components.
17 . The optical element module according to claim 16 , wherein at least one of the first contact surface and the second contact surface is formed by a low friction coefficient coating.
18 . The optical element module according to claim 16 , wherein
the contact element has a third coefficient of thermal expansion;
the third coefficient of thermal expansion being selected such that, at the temperature situation variation, a thermally induced modification in the size of the contact element compensates for the position change.
19 . The optical element module according to claim 16 , wherein
one of the optical element and the optical element holder forms a first module component;
a first contact surface being formed on the first module component;
the contact element having a curved second contact surface contacting the first contact surface;
the first contact element being adapted such that the second contact surface executes a rolling motion with respect to the first contact surface upon the position change.
20 . An optical element unit comprising:
a plurality of optical element modules connected to each other and supporting a plurality of optical elements,
the plurality of optical element modules comprising a first optical element module being an optical element module according to claim 1 .
21 . An optical exposure apparatus for transferring an image of a pattern formed on a mask onto a substrate comprising:
a light path;
a mask location located within the light path and receiving the mask;
a substrate location located at an end of the light path and receiving the substrate;
an optical element unit within the light path between the mask location and the substrate location, the optical element unit comprising:
a plurality of optical element modules connected to each other and supporting a plurality of optical elements,
wherein the plurality of optical element modules comprising a first optical element module being an optical element module according to claim 1 .
22 . A method of holding an optical element comprising:
in a first step, providing a plurality of module components, the module components comprising an optical element, an optical element holder and a contact element, and,
in a second step, holding the optical element using the optical element holder, the optical element holder holding the optical element via the contact element;
the optical element having a first coefficient of thermal expansion;
the optical element holder having a second coefficient of thermal expansion, the second coefficient of thermal expansion being different from the first coefficient of thermal expansion;
at least one of the module components being adapted to provide at least a reduction of forces introduced into the optical element upon a thermally induced position change in the relative position between the optical element and the optical element holder;
the position change resulting from a temperature situation variation in a temperature situation of the plurality of module components.
23 . The method according to claim 22 , wherein
in the first step, a contact element is provided, the contact element having a third coefficient of thermal expansion;
the third coefficient of thermal expansion being selected such that, at the temperature situation variation, a thermally induced modification in the size of the contact element compensates for the position change.