1. Field of the Invention
The present invention relates to a photo resist correction method, and more particularly, to a trimming process to remove a photo resist assistant feature.
2. Description of the Prior Art
In semiconductor manufacturing processes, in order to transfer an integrated circuit layout onto a semiconductor wafer, the integrated circuit layout is first designed and formed as a photo mask pattern. The photo mask pattern is then proportionally transferred to a photo resist layer positioned on the semiconductor wafer.
As the design pattern of integrated circuit becomes smaller and due to the resolution limit of the optical exposure tool, optical proximity effect will easily occur during the photolithographic process for transferring the photo mask pattern with higher density. The optical proximity effect will cause defects when transferring the photo mask pattern, such as residue of the assistant feature next to the right angled main feature, right angled corner rounding, line end shortening, and line width increasing/decreasing.
To avoid the mention problems of the optical proximity effect. The photo mask pattern will apply to the optical proximity correction and add the dummy assistant feature to prevent the optical proximity effect. The optical proximity correction is used the computer aided design (CAD) to calculate the deviation firstly, put the correction date into the computer to estimate the photo mask pattern and assistant feature, then output the photo mask pattern and assistant feature which are considered with the optical proximity effect.
Please refer to
In U.S. Pat. No. 6,777,146 B1, the assistant feature 14 between the main features 12, the pitch between the photo masks and the main feature width have a regular relation. The assistant feature 14 will not expose on the photo resist layer 26, but only the photo resist main feature 22 will show. In general, when the main feature 12 width is 120 μm and the pitch of the photo masks is 320 μm, the assistant feature 14 is less than 50 μm. And the assistant feature 14 will not show on the photo resist layer 26.
However the prior art doesn't have good OPC and the feature after exposure still has residue of the assistant feature next to the right angled main feature, right-angled corner rounded, line end shortened and line width increase/decrease. How to use the assistant feature 14 to develop OPE is an important issue in the domain.
The present invention relates to a method of forming the photo resist feature to solve the above-mentioned problems.
The embodiment according to the present invention providing the method of forming the photo resist feature comprises forming a photo resist layer on the substrate, providing a photo mask comprises the main feature and the assistant feature, providing the exposure process to form the photo resist main feature and the photo resist assistant feature correspondingly and providing the trimming process to remove the photo resist assistant feature and trim the photo resist main feature.
The embodiment according to the present invention providing the method of forming the photo resist feature comprises forming a photo resist layer on the substrate, providing a photo mask comprises the main feature and the assistant feature, providing the exposure process to form the photo resist main feature and the photo resist assistant feature correspondingly and providing the etching process to remove the photo resist assistant feature and trim the photo resist main feature.
The present invention can capacitates bigger assistant feature to reduce OPE and large the process window.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings.
FIGS. 2 to 4 are flowcharts of forming the photo mask pattern according to the present invention.
Please refer to FIGS. 2 to
Nevertheless, the correction of the main feature 32 is consideration of the projection, the optical proximity effect correction, the assistant feature 34 and the trimming process correction. The optical proximity effect correction corrects the main feature 32 after OPE. The trimming process correction corrects the photo resist main feature 42 after etching process.
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The conception of
Compare with the prior art, the present invention providing a method of forming a photo resist feature on a substrate, the method comprises forming the photo resist feature on the substrate, providing a photo mask and the photo mask comprises at least a first main feature and at least a first assistant feature, providing a exposure process to transfer the first main feature and the first assistant feature on the photo mask to a second main feature and a second assistant feature on the photo resist correspondingly, and providing a trimming process to remove the second assistant feature on the substrate and reduce the second main feature width. The present invention can capacitates bigger assistant feature 34 to reduce OPE, modify the residue of the assistant feature next to the right angled main feature, and large the process window.
Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.