KR20020089595A - Method for amending image in process for manufacturing semiconductor device - Google Patents

Abstract

PURPOSE: A method for correcting an image in a semiconductor fabrication process is provided to improve critical dimension uniformity and prevent a lowering phenomenon of a yield in the semiconductor fabrication process. CONSTITUTION: A critical dimension of the remaining photoresist layer pattern of a wafer is measured after a developing process is performed(100). A lower material layer such as an insulating layer or a conductive layer is etched by using the photoresist layer pattern as an etch mask(110). The critical dimension of the lower material layer is measured by a worker or automatic equipment(120). The measured data are analyzed(130). An exposure apparatus controls automatically an exposure time or a focus according to an image map if a corrected image map is transferred to the exposure apparatus by using the analyzed result of the measured critical dimension data of an image correction system(140).

Description

Method for amending image in process for manufacturing semiconductor device

The present invention relates to an image correction method, and more particularly, to an image correction method in which an operator reduces an error by automating each step by using an image correction system provided between an exposure apparatus and a line width (CD) measurement apparatus.

High integration of semiconductor devices can lead to complexity of the process and lower the yield. In order to achieve high integration of semiconductor devices and to prevent a decrease in yield, the line width management of patterns formed on a wafer must be more strictly performed. Moreover, due to the characteristics of the photographic / etching equipment, line width differences may appear even when the wafers are aligned under the same conditions with respect to the edges or specific areas of the wafer.

For example, in the photographic equipment, the Tpr of the edge of the wafer is uneven and the reproducibility of the focusing and leveling of the edge is insufficient. In the etching equipment of the same alignment condition, the etching rate of a specific area varies according to the equipment structure, so that the line width of the bar pattern is On the other hand, the line width of the hole pattern becomes high.

In order to compensate for such a difference, the exposure time and the focus condition are different for each region in the photolithography process.

In the image correction method according to the prior art, first, the full shot line width of the photoresist pattern is measured in post-development inspection by the operator. Thereafter, etching is performed using the photoresist pattern. The photosensitive film pattern is removed, and after cleaning inspection is performed. At this time, the full shot line width is measured by the operator. In other words, the line width of the material film pattern formed on the wafer patterned in the etching process is measured. Subsequently, shot-by-shot skew verification is performed by an operator. Based on the verification, an image correction is performed for each region of the wafer by the operator. The operator then changes the image of the exposure apparatus, such as a stepper, based on the image correction.

Since the image correction method according to the related art is involved in all processes, the operator's labor is severely related to the measurement of the line width, and when the image adjustment for each wafer area is performed, rough eye adjustment is performed using a skew-proven wafer. Erra may be included in the image adjustment by mistake of the operator in charge. In addition, results may vary slightly depending on the operator. In addition, since there are characteristics of each of the exposure apparatuses and etching apparatuses used, it may be difficult to apply the result to other apparatuses even when image adjustment is performed on any one of the apparatuses. This is especially true for etching equipment.

Accordingly, the technical problem to be achieved by the present invention is to improve the above-described problems of the prior art, and provides an image correction method capable of improving the line width uniformity and preventing the yield of the semiconductor manufacturing process from being lowered due to high integration. Is in.

1 and 2 are block diagrams showing step by step an image correction method according to the first and second embodiments of the present invention, respectively.

3 is a schematic configuration diagram of a manufacturing apparatus of a semiconductor device including an image correction system used in the image correction method according to the first and second embodiments of the present invention.

Figure 4 shows the distribution of full shot CD (full shot CD) measured after development.

FIG. 5 is a line width distribution reflecting an etching characteristic of an etching apparatus in FIG. 4.

FIG. 6 illustrates an image map in which image regions are grouped according to the line width of FIG. 5.

* Description of symbols on the main parts of the drawings *

300: exposure apparatus 350: image correction system

400: measurement equipment

In order to achieve the above technical problem, the present invention after the development of the exposed wafer, the first step of measuring the line width of the photosensitive film pattern formed on the wafer and transmitting the result to the image correction system; A second step of etching the lower material layer formed below the photosensitive layer pattern; Removing the photoresist pattern, measuring a line width after cleaning the etched lower material layer, and transmitting the measured line width to the image correction system; And a fourth step of changing an exposure condition according to the photosensitive film pattern line width measurement data after the development of the image correction system and the analysis result of the line width measurement data after cleaning. In this case, the first, third and fourth steps are performed manually or automatically.

In another aspect, the present invention, after developing the exposed wafer, measuring the line width of the photoresist pattern formed on the wafer and transmits the result to the image correction system stored the characteristic data for the etching equipment And a second step of changing exposure conditions according to the photosensitive film pattern line width measurement data after the development of the image correction system and the analysis result of the line width measurement data after the cleaning of the image correction system.

As described above, the present invention automatically performs image correction by performing the etching from the measurement of the full shot line width after development, and then comparing the two shot results after the full shot line width measurement after cleaning and automating the change of exposure conditions accordingly. You can run Therefore, the line width change according to the operator can be prevented, and the line width distribution of the pattern formed on the wafer can be improved. In other words, a uniform line width distribution can be obtained. In addition, by storing the characteristic data of the etching facility in the image correction system, the line width distribution can be actively improved since the stored characteristic data can be used when using the etching equipment.

Hereinafter, an image correction method according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. At this time, the drawings are exaggerated for convenience of description.

<First Embodiment>

The characteristics of the equipment used for etching are not verified.

Specifically, referring to FIG. 1, the first step 100 of the image correction method according to the first embodiment is a step of measuring a full shot line width in a post-development inspection, and a line width of a photoresist pattern remaining on a wafer after development. Measure In this case, the full shot CD may be measured by an operator as in the prior art, but is preferably measured using an automated line width measuring apparatus such as an automated scanning electron microscope (SEM).

The second step 110 is an etching step.

Specifically, the lower material layer, for example, an insulating film or a conductive film, formed under the photosensitive film pattern is etched using the photosensitive film pattern as an etching mask. Thereafter, the photoresist pattern is removed, and the resultant is washed.

The third step 120 is measuring the full shot linewidth in a post-clean inspection (ACI). In this step, it can be seen whether the lower material layer is patterned with the same dimensions as the photoresist pattern. The full shot line width in the post-cleaning inspection may be measured by an operator as in the full shot line width measurement in the first step 100, but is preferably measured using the automated equipment.

The fourth step 130 is a step of inputting and analyzing the measurement data.

Specifically, as shown in FIG. 3, the full shot line width data of the measured photosensitive film pattern and the data of the full shot line width measured in the post-cleaning inspection are all exposed to the exposure apparatus 300 and the automated measurement equipment ( And input to an image correction system (ICS) 350 provided between 400. A database for the full shot linewidths is built up in the image correction system 350, and the image correction system 350 performs an analysis on the measured data based thereon.

The fifth step 140 is a step of changing an exposure condition for image correction.

Specifically, when the image map corrected based on the analysis result of the line width measurement data of the image correction system 350 is transmitted to the exposure apparatus, the exposure apparatus may be configured to have an exposure time or the like suitable for the image map. The focus etc. are adjusted automatically.

In this way, the measurement of the line width, the analysis thereof, and the image correction and the exposure conditions are automatically made through the analysis of the line width, thereby reducing the operator's labor and reducing the occurrence of error at each step by the operator.

Second Embodiment

An image correction method when the etching characteristics of each of the etching equipments are verified. That is, since the etching characteristics of each of the etching equipment are already stored in the image correction system 350 (FIG. 3), the measurement process for the full shot line width in the post-cleaning inspection according to the etching may be omitted.

Accordingly, the image correction method according to the second embodiment can be reduced to the first to third steps 200, 210, and 220 as shown in FIG. 2. Since the first step 200 according to the second embodiment is the same as the first step (100 in FIG. 1) of the first embodiment, description thereof will be omitted. The third step 220 of changing the exposure condition is also the same as the fifth step 140 of the first embodiment, and thus description thereof is omitted.

Meanwhile, in the second step 210 of the second embodiment, the line width measurement data is input to the image correction system 350 and analyzed using the image correction system 350, similar to the fourth step 130 of the first embodiment. In the step or the second embodiment, since the etching characteristics for the etching equipment are already stored in the image correction system 350, in the second step 210 of the second embodiment, the line width of the photoresist pattern measured in the post-development inspection is measured. Only data is input to the image correction system 350. Analysis of the input data is performed in the same manner as in the first embodiment.

FIG. 3 is a schematic view illustrating a manufacturing facility configuration of a semiconductor device used in an image correction method, and includes an exposure apparatus 300 such as a stepper and an automated measurement facility 400 such as an SEM and an image correction system 350. It can be seen.

The image correction system 350 is formed on the wafer in the data measured from the automated metrology facility 400, for example, the data of the line width of the photoresist pattern in the post-development inspection or in the post-cleaning inspection performed after etching. The data of measuring the line width of the pattern is received and analyzed to transmit the optimal image map for image correction to the exposure apparatus 300. The exposure apparatus 300 sets exposure conditions for each shot based on this, and performs exposure accordingly.

Next, a data analysis process of the image correction system 350 will be described.

The image condition is set to have the same image by separating the shots in the same range by separating the full shot linewidth data measured in the post-development inspection transmitted from the measurement facility 400 for each range.

For example, when the measured line width is a shot within ± 5 nm of the target, the main shot is a shot within +5 nm to +10 nm, and the first image shot is +10 nm to +15 nm. In the case of the shot within the range, the second image shot is set as the third image shot when the shot is within the range of -5 nm to -10 nm, and as the fourth image shot when the shot is within the range -10 nm to -15 nm.

In addition, the information on the image change by the etching characteristics of the etching equipment is reflected. For example, when the line width of the pattern formed at the edge of the selected etching equipment is about 10 nm smaller than the wafer center region, the image shot in exposure is set in consideration of this. Through this information, a shot after the fifth image is set. Subsequently, an exposure condition for each of the images, for example, an exposure time or an intensity of exposure, is set based on the reference information about the etching equipment.

Next, a process of determining an image through the image correction system 350 will be described with reference to FIGS. 4 to 6.

4 shows the linewidth distribution measured in the post-development inspection for each shot region transmitted from the metrology facility 400 to the image correction system 350. Reflecting the etching characteristics of the etching equipment, such as the fact that the line width at the wafer edge is about 10 nm smaller than other areas, a line width distribution is obtained by increasing the line width of the wafer edge by about 10 nm as shown in FIG. 5.

Subsequently, an image map as shown in Fig. 6 is determined by setting image shots for each linewidth group. In other words, the region having a line width of 245 nm to 255 nm is the main shot region, the region of 256 nm to 265 nm is the first image shot region, the region of 266 nm to 275 nm is the second image shot region, and the region of 235 nm to 244 nm is the third image As the shot region, the region of 225 nm to 234 nm is set as the fourth image shot region.

Thereafter, the image correction system 350 sets a progress condition for each shot region according to the image map of FIG. 6, and then transmits the image map and the progress condition to the exposure apparatus 300.

As described above, the image correction system 350 is a basic function, and is capable of distinguishing the full shot line width measured after the input development into an appropriate level, and the full shot line width measured after the development and the full shot line width measured after the cleaning. It has a function of verifying the skew and directly giving the analyzed image map a command to the exposure apparatus.

In addition, the image correction system 350 includes, as basic information, a database of information on linewidth variation according to exposure time for each exposure apparatus and information on characteristics of linewidth distribution for each etching apparatus, and each exposure apparatus. Contains information about the basic linewidth distribution characteristics for.

While many details are set forth in the foregoing description, they should be construed as illustrative of preferred embodiments, rather than to limit the scope of the invention. For example, a person skilled in the art may use a scanner in addition to a stepper as an exposure apparatus, or may use other line width measurement equipment other than SEM. In addition, the data on the line width measured in the post-development inspection and the data on the line width measured in the post-cleaning inspection may be transmitted simultaneously with the measurement at each step without transmitting to the image correction system at the same time. Therefore, the scope of the present invention should not be defined by the described embodiments, but should be determined by the technical spirit described in the claims.

As described above, the present invention performs image correction by performing etching from the measurement of the full shot line width after development, and then comparing the two shot results with the full shot line width measurement after cleaning and automating the change of exposure conditions accordingly. It can run automatically. Therefore, the line width change according to the operator can be prevented, and the line width distribution of the pattern formed on the wafer can be improved. In other words, a uniform line width distribution can be obtained. In addition, by storing the characteristic data of the etching facility in the image correction system, the line width distribution can be actively improved since the stored characteristic data can be used when using the etching equipment.

Claims (4)

A first step of measuring the line width of the photosensitive film pattern formed on the wafer in the post-development inspection; A second step of etching the lower material layer formed below the photosensitive layer pattern; Removing the photoresist pattern, and then measuring a line width of the etched lower material layer in a post-cleaning inspection; A fourth step of inputting and analyzing data on the line width measured after development and the line width measured after cleaning to an image correction system provided between an exposure apparatus and the line width measurement equipment; And And a fifth step of changing an exposure condition according to an analysis result of the input data of the image correction system. The method of claim 1, wherein the obtaining of the data about the line width, transmitting the same to the image correction system, and changing the exposure condition according to the analysis result are performed automatically. A first step of measuring the line width of the photosensitive film pattern formed on the wafer in the post-development inspection; A second step of transmitting the line width measurement result to an image correction system in which etching characteristic data of an etching apparatus to be used for subsequent etching is stored; And And a third step of changing an exposure condition according to the analysis result. 4. The method of claim 3, wherein said first to third steps are automated to prevent operator error.