Photoetching process method

Abstract

The invention discloses a photoetching process method. The photoetching process method comprises the following steps: 1, an optimal focal length and a focusing depth of exposure in a photoetching process are calculated; 2, a first photoresist is applied to a first wafer, wherein the thickness of the first photoresist is greater than the focusing depth; 3, exposure for multiple times is carried outfrom the bottom of the first photoresist, wherein each time of exposure before the last-time exposure is to process a sub-layer with the thickness of DOF in the first photoresist, the sub-layers aresuperposed sequentially from the bottom to the top of the first photoresist, the superposition thickness of the sub-layers is smaller than the thickness of the first photoresist, the remaining topmostsub-layer is formed at the top of the first photoresist, the thickness of the topmost sub-layer is smaller than or equal to the DOF, and the topmost sub-layer is processed through the last-time exposure; and 4, the first photoresist is developed. The focusing depth of the thick photoresist process can be increased, and the resolution and the process window are improved.

Description

technical field [0001] The invention relates to a semiconductor integrated circuit manufacturing method, in particular to a photolithography process method. Background technique [0002] Photolithography is the process of transferring the pattern prepared in advance on the mask (Mask) to the substrate by using the principle of photochemical reaction. Depth-of-focus (DOF) is an important parameter to measure the lithography process window, which marks the relationship between the imaging quality of the exposure system and the position of the wafer surface. Within the range of depth of focus, the quality of exposure imaging can be guaranteed. [0003] Such as figure 1 As shown, it is a schematic diagram of the depth of focus exposed in the photolithography process; in the exposure process, after the light source 101 passes through the mask (Mask) 102, the pattern on the mask 102 will diffract the light and form a corresponding diffraction image (Diffracted Image) 103, after...

AI Technical Summary

Problems solved by technology

With the decrease of the line width and the increase of the thickness of the photoresist required by the process, the height of the photoresist is often greater than the depth of focus, so that the bottom or top of the photoresist is not within the range of the depth of focus, resulting in loss of graphics. focus, which affects the resolution and process window of the exposure

like figure 2 As shown, it is a schematic diagram of the photoresist defocus (defocus) when the photoresist height is greater than the depth of focus in the existing photolithography process; The sub-layer 2022 of 201 from the surface to the thickness within the range of DOF is exposed, and the sub-layer 2021 at the bottom of the sub-layer 2022 is an out-of-focus part. The sub-layer 2021 is also represented by Defocus, and the sub-layer 2021 cannot achieve good exposure, which will cause Graphics do not meet requirements

Images