Lithographic alignment mark structure and manufacturing method thereof

Abstract

The present invention provides a photolithographic alignment mark structure and its manufacturing method, which is a multi-level mutual alignment precision pattern structure design and its manufacturing method. When projecting, they are all center-symmetric figures relative to the same center, and the projections of all lithography alignment figures are nested and expanded from inside to outside according to the formation sequence of lithography alignment figures, which can be applied to various lithography processes. According to different needs, it can be matched at will to meet the alignment requirements that are constant and changeable, and can meet the mutual alignment requirements of lithography alignment marks between different layers. At the same time, it can take into account the traditional alignment measurement and 3 exposures, 4 exposures The alignment measurement required for the second exposure, and it saves the space of the cutting line and reduces the cost.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a photolithographic alignment mark structure and a manufacturing method thereof. Background technique [0002] With the continuous improvement of integrated circuit manufacturing technology and the continuous shrinking of line width, the area of ​​semiconductor devices is becoming smaller and smaller, and the layout of semiconductors has evolved from ordinary single-function separation devices to integrated high-density and multi-functional integrated circuits; From the initial IC (integrated circuit) to LSI (large-scale integrated circuit), VLSI (very large-scale integrated circuit), until today's ULSI (ultra-large-scale integrated circuit), the area of ​​the device is further reduced, and the functions are more comprehensive and powerful. Considering the complexity of process research and development, long-term and high cost and other unfavorable factors, how to furth...

AI Technical Summary

Problems solved by technology

[0005] 1. The placement of traditional alignment measurement patterns occupies more layout design space. On 2-in-1, 4-in-1, and N-in-1 masks, the space for cutting lines will become smaller and smaller, but the required test patterns However, it cannot be reduced. The space occupied by traditional alignment patterns will force the reticle to discard some test patterns before publication, and small layout design and publication will also be limited by this;

[0006] 2. The traditional alignment measurement graphics cannot measure the alignment accuracy across layers without increasing the number of additional front-layer alignment graphics, for example, when the second layer has a deviation from the first layer alignment , then it is no longer possible to use the third level to directly calibrate the method of the first level, but can only continue to align with the second level that already has deviations;

[0007] 3. When the traditional alignment measurement pattern is applied to the double exposure double patterning of the advanced process, it is difficult to improve the alignment error and residual problems. The reason is that it is limited by the single-level alignment of the traditional alignment measurement pattern. When performing the second In the exposure type, different front-layer marks need to be selected for alignment measurement, and it is obviously impossible to fix the same front-layer mark for measurement;

[0008] 4. When the traditional alignment measurement pattern adds a new pattern layer, it is necessary to add an additional front-layer alignment mark. In this way, it is necessary to re-publish the 2-layer mask including the front-layer mask, which increases additional costs;

Although this structure can perform three-layer alignment at the same time, the design cannot cover the deviation collection in the X and Y directions at the same time, and the vector fitting degree is questionable. This is also true for the development of chip structures below 28 nanometers. There is a risk of misalignment

And the current lithography technology no longer stays in the way of 2 exposures (double exposure), but has risen to 3 exposures, or even 4 exposures. This structure also cannot be used for subsequent multi-layer mark alignment through fixed front-layer marks. Measure

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