Electro-optical fine alignment process

Claim 2

In a process for aligning two objects by electro-optical means in which each of said objects have corresponding alignment patterns with the patterns on one of said objects being in the form of a relief image which is coated with a layer of photoresist; the alignment being accomplished by illuminating said patterns with coherent monochromatic light which is reflected from said relief image to produce images of said corresponding patterns; using said images to produce electrical signals which are indicative of the location of said patterns; and moving the objects relative to one another until the signals agree, the improvement which comprises coating on said resist layer a layer of material prior to illuminating said patterns which material absorbs and reflects said light such that only light reflected from said layer is used to generate said signals.

Claim 3

The process of claim 1 wherein said material is an organic dye.

Claim 4

The process of claim 2 wherein said dye is Rhodamine B.

Claim 5

In a process for aligning a resist coated semiconductor wafer during integrated circuit device manufacture with an exposure mask for resist exposure through said mask by electro-optical means in which the mask and wafer have corresponding alignment patterns with the patterns on the wafer being in the form of relief images, the alignment being accomplished by illuminating the patterns with coherent monochromatic light such that said light is reflected from the patterns on the wafer to produce images of the corresponding alignment patterns; using said images to produce electrical signals which are indicative of the location of said patterns; and then moving the mask and wafer relative to one another until the signals generated by the mask and wafer patterns agree, the improvement which comprises the step of coating a layer of material on top of the photoresist layer prior to illuminating said patterns which material reflects or absorbs the alignment light, such that only the reflected light is used in the alignment, and which material is transmissive of the exposure light so that photoresist exposure can occur through said layer.

Claim 6

In a process for aligning a resist coated semiconductor wafer during integrated circuit device manufacture with an exposure mask for resist exposure through said mask by electro-optical means in which the mask and wafer have corresponding alignment patterns with the patterns on the wafer being in the form of relief images, the alignment being accomplished by illuminating the patterns with coherent monochromatic light such that said light is reflected from the patterns on the wafer to produce images of the corresponding alignment patterns; using said images to produce electrical signals which are indicative of the location of said patterns; and then moving the mask and wafer relative to one another until the signals generated by the mask and wafer patterns agree, the improvement which comprises the step of coating a layer of material on top of the photoresist layer prior to illuminating said patterns which material reflects or absorbs the alignment light, such that only the reflected light is used in the alignment, and which material is transmissive of the exposure light so that photoresist exposure can occur through said layer.

Claim 7

The process of claim 4 in which said material is aluminum.

Claim 8

The process of claim 4 in which said material is Rhodamine B.

Claim 9

The process of claim 4 in which said material is erythrosin.

Claim 10

The process of claim 4 wherein said material is reflective at wavelengths above about 5,000A and transmissive of wavelength between about 3,500A and 4,500A.

Claim 11

The process of claim 2 wherein said material is coated in a thickness from about 500 to 2,000A.