EUV reticle thermal management

A reticle thermal management system for use in photolithography comprising:

• a cooling element placed adjacent a reticle and capable of cooling a selected portion of the reticle as the reticle is scanned across said cooling element;
• a heating element placed adjacent the reticle and said cooling element and capable of heating a selected portion of the reticle as the reticle is scanned across said heating element;
• an illumination aperture formed adjacent to said heating element;
• and
• a control coupled to said cooling and heating elements, said control causing said heating element to increase a thermal load on a portion of the reticle when not illuminated by electromagnetic radiation and to decrease the thermal load on the reticle when illuminated by electromagnetic radiation,
• whereby electromagnetic radiation passes through said illumination aperture illuminating a reticle and projecting an image of the reticle onto a photosensitive substrate.

A thermal management system for use in controlling the temperature of a reticle used in photolithography comprising:

• a substantially planar heating element placed adjacent the reticle;
• a substantially planar cooling element placed adjacent the reticle and surrounding said planar heating element;
• an illumination aperture formed in said planar cooling element having a side common with said planar heating element;
• a control coupled to said substantially planar heating element, said control causing said substantially planar heating element to provide heat when the reticle is not being illuminated by electromagnetic radiation from an illumination source and not to provide heat when the reticle is being illuminated by electromagnetic radiation from the illumination source,
• whereby thermal gradients in the reticle due to absorption of the electromagnetic radiation from an illumination source are reduced.

A photolithographic system with reticle thermal management comprising:

• an EUV illumination source providing an illumination field;
• a reticle stage having a reticle thereon positioned to receive the illumination field;
• a heating element placed adjacent the reticle providing heat to a portion of the reticle;
• a cooling element placed adjacent the reticle removing heat from the reticle;
• a temperature control coupled to said EUV illumination source, said illumination source, and said heating and cooling elements, whereby said temperature control selectively controls thermal energy provided to the reticle by said heating and cooling elements so that thermal gradients due to absorption of electromagnetic radiation by the reticle are reduced;
• a substrate stage having a photosensitive substrate thereon;
• projection optics placed between the reticle and the photosensitive substrate;
• and
• a stage control coupled to said reticle stage and said substrate stage,
• whereby the image of the reticle is projected onto the photosensitive substrate with reduced distortion due to thermal gradients in the reticle.

A method of controlling thermal distortion of a reticle used in photolithography comprising the steps of:

• scanning a reticle across a heating element
• providing heat sequentially to portions of the reticle as the reticle is scanned across the heating element when the reticle is not being illuminated by an illumination source;
• and
• removing heat sequentially from portions of the reticle as the reticle is scanned when an illuminated portion of the reticle is being illuminated by an illumination source,
• whereby temperature gradients in the reticle are reduced.

A reticle thermal management system for use with a scanning photolithographic system having an illumination source for projecting the image of a reticle onto a photosensitive substrate comprising:

• a cooling element placed adjacent a portion of the reticle so as to be capable of providing cooling to a portion of the reticle as the reticle is scanned across said cooling element;
• an illumination transmitting portion adjacent said cooling element and adapted to transmit electromagnetic radiation from the illumination source to an illuminated portion of the reticle;
• a heating element placed adjacent the illumination transmitting portion and a portion of the reticle so as to be capable of providing heat to a portion of the reticle as the reticle is scanned across said heating element;
• and
• a control coupled to said cooling element and said heating element, said control balancing cooling provided by said cooling element and heat provided by said heating element so as to result in no net temperature change due to absorption of electromagnetic radiation from illumination of the illuminated portion of the reticle by the illumination source,
• whereby thermal gradients in the reticle due to absorption of the electromagnetic radiation over portions of the reticle are reduced.

A reticle thermal management system used in scanning photolithography for creating an image of a reticle on a photosensitive substrate comprising:

• a thermal management device having an illumination aperture placed adjacent the reticle, the illumination aperture being smaller than a planar surface of the reticle, whereby a scanning exposure may be obtained and an entire image of the reticle may be produced onto the photosensitive substrate;
• a heating element placed adjacent the illumination aperture and providing heat to the reticle;
• and
• control means, coupled to said heating element, for reducing the energy provided by said heating element to compensate for thermal energy created by absorption of electromagnetic radiation in the reticle.

A reticle thermal management system for use in scanning photolithography comprising:

• a heating element placed adjacent a reticle;
• an illumination aperture formed adjacent to said heating element illuminating a portion of the reticle;
• a reticle stage holding the reticle and movable in a scan direction;
• a stage control coupled to said reticle stage;
• and
• a temperature control coupled to said heating element and said stage control, said temperature control controlling said heating element spatially, compensating for any differences in a rate of absorption of electromagnetic radiation when the portion of the reticle is being illuminated,
• whereby thermal gradients in the reticle are reduced.