Method for improving stability of alignment precision of high-transparency mask plate

Abstract

The invention discloses a method for improving the stability of an alignment precision of a high-transparency mask plate. The method comprises the steps of reversing a light-transmitting region of a high-transparency positive photoresist mask plate to obtain a low-transparency mask plate with a light-transmitting region opposite to the light-transmitting region of the positive photoresist mask plate; and taking the reversed low-transparency mask plate as an aeration mask plate, and utilizing negative photoresist to carry out aeration and developing on a silicon wafer. Therefore, the energy for heating a lens in an aeration process is effectively reduced and the degree of expanding of the lens by heating is reduced after the silicon water is continuously aerated; and the alignment precision is kept stable, and the yield and the process production efficiency of the silicon wafer are improved.

Description

technical field [0001] The invention relates to the technical field of semiconductor manufacturing, in particular to a method for improving the stability of the overlay precision of a mask plate with high light transmittance. Background technique [0002] With the improvement of the integration of semiconductor components, the line width requirements of semiconductor components are getting smaller and smaller, and the control of critical dimensions (CD, Critical Dimension) is becoming more and more important. The requirements are also getting higher and higher. In the photolithography process, a certain thickness of photoresist is usually coated on the surface of the wafer, and then a photolithography machine (scanner) is used to transfer the pattern exposure on the mask plate to the silicon wafer. There are two types of photoresist used in the photolithography process, positive photoresist and negative photoresist. Will not be removed by developer. The negative photoresi...

AI Technical Summary

Problems solved by technology

In the 55nm Dual gate process, a stepper is used for exposure, the key dimension is 0.45um, the photoresist is a positive photoresist, the pattern penetration rate of the mask is 88.3%, and the exposure energy is 200 In millijoules, the energy intensity is equal to the exposure energy multiplied by the light transmittance. During the continuous exposure process of 25 wafers, due to the excessive energy intensity of the light source passing through the mask, the lens will gradually expand due to heat, and the focal plane will gradually Offset, resulting in out-of-focus graphics, offset registration accuracy, low stability, lower wafer yield, and affect the production efficiency of lithography process

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