KR20080061999A

KR20080061999A - Photo mask for improving wafer pattern cd uniformity and manufacturing method therefor

Info

Publication number: KR20080061999A
Application number: KR1020060137229A
Authority: KR
Inventors: 이전규
Original assignee: 주식회사 하이닉스반도체
Priority date: 2006-12-28
Filing date: 2006-12-28
Publication date: 2008-07-03

Abstract

A photo mask for improving uniformity of wafer pattern CD and a manufacturing method thereof are provided to implement uniform CD distribution by varying distribution of holes on a pellicle layer. A reticle has patterns to be transcribed to a wafer. A plurality of holes(401) are distributed on a first pellicle layer(400) on the basis of light transmittance distribution to compensate deviation of CD distribution within an exposure field region of the patterns transcribed by the reticle on the wafer. A second pellicle layer is attached to the first pellicle layer to prevent the pollution of the reticle.

Description

Photo mask for improving wafer pattern CD uniformity and manufacturing method therefor}

1 is a view showing a process flow for manufacturing a photomask according to an embodiment of the present invention.

2 to 6 are schematic views illustrating a photomask structure according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to semiconductor device fabrication, and more particularly, to a photomask structure and a manufacturing method for improving the uniformity of a critical dimension (CD) in a lithography process.

As the design rule of the semiconductor device is rapidly reduced and the degree of integration increases, the uniformity of the pattern transferred onto the wafer is rapidly reduced. When the pattern on the photomask is transferred onto the wafer in a photographic and exposure process, the intra shot critical dimension uniformity that is actually transferred onto the wafer within one exposure shot or exposure field is It is falling rapidly. Accordingly, various efforts have been made to improve the pattern line width uniformity.

Improvements in pattern line width uniformity in the exposure shot are mainly considered in the wafer processing step or the pattern layout design step. On the other hand, the structure of the photomask including the pattern layout to be transferred by the exposure process and the manufacturing stage of the photomask are considered relatively limited. Improvement of CD uniformity in photomask fabrication is made by applying a fogging method or modifying and changing the linewidth uniformity of the entire pattern of the mask itself.

Accordingly, such pattern linewidth uniformity improvement methods involve rework or remanufacturing of the photomask. In addition, a lot of costs are required for the remanufacturing of the mask, and an additional remanufacturing period is required, which delays device development and mass production, thus incurring additional costs.

An object of the present invention is to propose a photomask structure and a manufacturing method for improving the line width (CD) uniformity of the wafer pattern.

One aspect of the present invention for achieving the above technical problem is a reticle formed with patterns to be transferred onto a wafer, line width (CD) in the exposure field area of the patterns on the wafer transferred by the reticle A photo mask including a first pellicle film having holes distributed therein to provide a light transmittance distribution to compensate for the variation of the distribution, and a second pellicle film attached on the first pellicle film to prevent contamination of the reticle. present.

The first pellicle film may be formed to have a distribution of holes that are densely distributed in a second region where the line width is relatively larger than a first region where the line width is relatively small.

According to another aspect of the present invention, there is provided a method of forming a reticle having patterns on a substrate to be transferred onto a wafer, transferring patterns of the reticle onto a wafer, and an exposure field of patterns transferred onto the wafer. obtaining a line width (CD) distribution in an area of an exposure field, obtaining a light transmittance distribution to compensate for a deviation of the pattern line width distribution, and distributing holes on a first pellicle film based on the light transmittance distribution It provides a photomask manufacturing method comprising the step of forming, attaching the first pellicle film on the reticle, and attaching a second pellicle film to prevent contamination of the reticle on the first pellicle film.

The holes may be formed through the first pellicle film so as to be densely distributed in a second region having a relatively large line width compared to a first region having a relatively small line width.

According to the present invention, the pellicle is formed of a double structure of the first pellicle film to prevent contamination and the second pellicle film to control the light transmittance distribution, thereby improving the line width uniformity of the wafer pattern by adjusting the light transmittance distribution. The photomask structure can be presented.

In an embodiment of the present invention, the pattern uniformity is improved by introducing a double pellicle film into a reticle formed on a transparent substrate having a reticle pattern such as a light shielding pattern or a phase shift pattern for a pattern to be transferred onto a wafer. . The pellicle film may include a first pellicle film for preventing contamination of the reticle and a second pellicle film for adjusting the light transmittance distribution. The second pellicle film may include a plurality of transmittance adjusting holes penetrating the film to adjust the light transmittance distribution. According to the distribution of the holes, the second pellicle film has a light transmittance distribution, and the light transmittance distribution may be set to compensate for the pattern line width distribution on the wafer. For this purpose, a test step of first obtaining a pattern line width distribution on the wafer may be performed.

1 to 6 are diagrams schematically illustrating a photomask structure and a manufacturing method according to an embodiment of the present invention.

1 and 2, a photomask according to an embodiment of the present invention first forms a reticle for a pattern to be transferred onto a wafer (101 in FIG. 1). As shown in FIG. 2, the reticle is formed of a reticle pattern 201, for example, a shading layer pattern such as a chromium (Cr) layer or molybdenum, along a layout to be transferred onto a transparent substrate 200 such as a quartz substrate. The reticle pattern 201 including a phase inversion layer pattern such as a denium (Mo) layer or an Mo alloy layer may be formed. In the exposure process of transferring a pattern onto a wafer (not shown) by using the reticle thus formed, the reticle substrate 200 is applied to the surface of the reticle 200 in order to improve the depth of focus (DOF) or the like and to exclude the influence of particles. A photomask in which the test pellicle film 300 is bonded using a frame 301 is used.

A line pattern (CD) distribution of a pattern, for example, a photoresist pattern, is formed by transferring a target pattern designed on the wafer by performing an exposure process using such a photomask and transferring the actual pattern on the wafer. Measure In the photo process such as the actual exposure and development process, since the exposure conditions may be changed for each region, the line widths of the patterns implemented on the actual wafer may be somewhat uneven. At this time, the test pellicle film 300 is preferably understood to be a simple contamination prevention pellicle film having a uniform transmittance distribution over the entire area.

When the line width distribution of the patterns formed in the wafer area corresponding to one exposure shot area or the exposure field area is measured, a map of line width (CD) distributions varied for each area can be obtained as shown in FIG. 103 in FIG. 1). The line width distribution map of FIG. 3 divides the exposure field area into a plurality of spot size regions, measures the line width CD in each spot size region, and then measures the measured line widths in each region. A map created by granting to.

As such, based on the measured wafer line width distribution map of FIG. 3, the distribution of the exposure energy difference ΔE that can compensate for the variation of the pattern line width which is formed larger or smaller than the target line width is obtained. These exposure energy differences ΔE may eventually be understood as exposure energy differences that may compensate for differences in line width patterns in the corresponding area. When the exposure energy differences ΔE are calculated for each corresponding area with respect to the exposure energy in which the line widths measured in the wafer line width distribution map of FIG. 3 are implemented, the appropriate exposure energy for the area in which the target pattern may be implemented is included in the corresponding area. Can be given.

These exposure energy differences ΔE are added to the regions of the wafer line width distribution map of FIG. 3 to obtain a distribution of exposure energy differences ΔE to be used to correct the pattern line width. For example, line width deviations are obtained for each spot size region, and exposure energy differences corresponding to the line width deviations are calculated from the correlation between the line width and the exposure energy to obtain a distribution of exposure energy differences. The light transmittance distribution is then calculated to provide this exposure energy difference ΔE distribution. After obtaining the light transmittance distribution to compensate for the CD deviation, as shown in FIGS. 4 and 5, a first pellicle film (400 of FIGS. 4 and 5) for adjusting the light transmittance to provide such a light transmittance distribution was fabricated. On the substrate 200 (105 in FIG. 1).

As shown in FIG. 5, the first pellicle film 400 has a hole 401 to induce a change in light transmittance for each region by the hole 401. For example, in the first region 410 in which the CD is measured to be relatively small based on the CD distribution of FIG. 3, the distribution of the holes 401 is relatively evenly distributed with relatively low light transmittance. On the other hand, in the second region 420 where the CD is measured relatively large, the distribution of the holes 401 is distributed more densely because the light transmittance is relatively high. That is, as the density of the holes 401 increases, light transmittance is relatively increased. Therefore, the portions of the holes 401 to be relatively larger induce CDs are arranged more sparsely to lower the light transmittance. As such, the first pellicle film 400 is formed to have a light transmittance distribution to compensate for a deviation in the CD distribution of FIG. 3. Since the holes 401 are formed as through holes penetrating the first pellicle film 400, the holes 401 are formed in the entirety of the first pellicle film 400 by using the difference between the resin film forming the first pellicle film 400 and the light transmittance in the air. The light transmittance distribution over can be adjusted by the distribution of the holes 401.

Subsequently, as shown in FIGS. 4 and 5, the first pellicle film 400 is attached to the substrate 200 of the reticle using the frame 301, and the contamination is prevented on the first pellicle film 400. A second pellicle film 310 is attached (107 in Fig. 1). By the pellicle structure of the double layers of the first and second pellicle films 400 and 310, the distribution of exposure energy doses can be adjusted for each reticle or photomask region. As such, since the first pellicle film 400 provides a light transmittance distribution to compensate for the CD deviation, an appropriate exposure energy dose distribution may be provided for each region when the reticle pattern 201 is transferred onto the wafer. As such, the line width of the actual pattern formed on the wafer may exhibit a more uniform distribution as shown in the measured wafer distribution map shown in FIG. 6.

According to the present invention described above, after fabricating the reticle, the pellicle film itself is obtained by obtaining a wafer pattern linewidth distribution map according to the reticle, and attaching a pellicle film having through holes distributed to the reticle to compensate for the linewidth variation of each region according to the linewidth distribution The light transmittance distribution can be adjusted at. Accordingly, the exposure energy actually irradiated for each region may be changed and provided on the wafer in accordance with the appropriate exposure energy for realizing the actual target line width. Therefore, the line width distribution of the patterns formed on the wafer can be implemented to have a more uniform distribution.

In addition, by changing the distribution of the holes in the pellicle film, it is possible to implement various light transmittance distributions, thereby inducing a more uniform linewidth distribution changed by various variables. The process of forming the holes in the pellicle film is relatively easy compared to the process of forming various light transmittance control patterns on the actual quartz substrate. Therefore, in order to compensate for the line width nonuniformity of the wafer pattern, the process of remanufacturing the reticle itself can be preferably omitted. In addition, since the distribution of the holes can be adjusted quite freely, even when the line width distribution is made fairly random, a light transmittance distribution to compensate for this can be realized on the pellicle film. Therefore, the line width distribution of the patterns formed on the wafer can be implemented to have a more uniform distribution.

As mentioned above, although this invention was demonstrated in detail through the specific Example, this invention is not limited to this, It is clear that the deformation | transformation and improvement are possible by the person of ordinary skill in the art within the technical idea of this invention.

Claims

A reticle formed with patterns to be transferred onto a wafer;

A first pellicle film in which holes are distributed based on a light transmittance distribution to compensate for a deviation in a line width (CD) distribution in an exposure field area of patterns on the wafer transferred by the reticle; And

A photomask comprising a second pellicle film attached to the first pellicle film to prevent contamination of the reticle.

The method of claim 1,

The first pellicle film has a distribution of the holes that are relatively densely distributed in the second region where the line width is relatively larger than the first region where the line width is relatively small.

Forming a reticle having patterns on the substrate to be transferred onto the wafer;

Transferring patterns of the reticle onto a wafer;

Obtaining a line width (CD) distribution in an exposure field area of patterns transferred onto the wafer;

Obtaining a light transmittance distribution to compensate for the deviation of the pattern line width distribution;

Forming a distribution of holes on a first pellicle film based on the light transmittance distribution;

Attaching the first pellicle film on the reticle; And

And attaching a second pellicle film to prevent contamination of the reticle on the first pellicle film.

The method of claim 3,

And the holes are formed through the first pellicle film so as to be densely distributed in a second region where the line width is relatively larger than a first region where the line width is relatively small.