the thermal flow capability of the positive photoresist and may also make the negative photoresist insoluble to many developing agents this means that the negative photoresist may have an improved mef compared to positive photoresist but does not provide an improved dof that may be gained by using a flowable resist in addition it may be difficult to etch the negative photoresist after cross linking occurs while negative photoresist may be used with a chromium less cr less mask the negative photoresist used generally exhibits cross linking when exposed and therefore does not flow the use of a cr less mask with a flowable positive photoresist is generally not satisfactory because a cr less mask is transparent and works on the principle of destructive interference making it difficult to form holes when used with positive photoresist accordingly in step 12 of fig1 and with additional reference to fig2 a polymer layer 106 is formed over an underlying layer 104 and a substrate 102 it is understood that the underlying layer 104 was formed on the substrate 102 prior to the beginning of the method 10 the substrate 102 may comprise an elementary semiconductor such as crystal silicon polycrystalline silicon amorphous silicon and germanium a compound semiconductor such as silicon carbide and gallium arsenic an alloy semiconductor such as silicon germanium gallium arsenide phosphide aluminum indium arsenide aluminum gallium arsenide and gallium.