Secondary pre-alignment device and pre-alignment method

Abstract

The invention relates to a secondary pre-alignment device. The secondary pre-alignment device is arranged between a movement station and a main substrate, is used for carrying out secondary pre-alignment on a wafer placed on the movement station and comprises three area array CCDs (Charge Coupled Device), three groups of optical path systems and an image processor. The three groups of optical path systems are used for respectively projecting three edge images of the wafer to the corresponding area array CCDs; a light source required by the three groups of optical path systems is arranged outside the movement station; the three area array CCDs are connected with the image processor; and the image processor is used for processing wafer edge image information from the three area array CCDs and then calculating the residual eccentric deviation of the wafer. A direct irradiation principle is adopted and the light source and the area array CCDs are respectively arranged at both sides of the wafer, so that not only is the accuracy higher, but also the secondary pre-alignment device is difficult to influence by the installing angle; and moreover, the design optical path is simple and the light energy dissipation is low. Moreover, the light source is arranged far away from key parts sensitive to a heat source, such as a projection objective, an objective, the main substrate, the movement station and the like, so that the performance stability of the secondary pre-alignment device is improved and the alignment accuracy is further improved.

Description

technical field [0001] The invention relates to the field of semiconductor photolithography, in particular to a wafer secondary alignment device and an alignment method thereof. Background technique [0002] At present, with the continuous shrinking of the critical size of the lithography machine, the requirements for the internal world of the lithography machine are also continuously increasing. The secondary pre-alignment measurement device measures the residual eccentricity of the wafer reaching the internal world, making the way of moving the stage to compensate becomes a development trend. During the transfer of the wafer from the cassette to the motion table, after pre-alignment, the eccentricity is about 10 μm and the deviation is about 150 μrad. The edge of the wafer is composed of most of the arc and the notch or flat edge that plays an orientation role. After centering and orientation, it is then transferred to the handover position above the motion table. The han...

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Problems solved by technology

Therefore, if the heat source is arranged on the main substrate, close to the projection objective lens and sensors of other subsystems, it will have a great impact on the surrounding temperature field

Similarly, if the heat source is arranged on the exercise platform, it will have a great impact on the temperature field of the exercise platform

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