KR20080003618A - Method of aligning a wafer in an exposure apparatus and an exposure system using the same - Google Patents

Abstract

A method of aligning a wafer in an exposure apparatus and an exposure system using the same are provided to align the wafer more precisely and easily by calculating alignment data and an alignment compensation value, and feeding back the data and value to the exposure apparatus. A method of aligning a wafer in an exposure apparatus includes the steps of: transmitting first raw alignment data measured from the wafer positioned in the exposure apparatus(S30); calculating a first alignment compensation value from the first raw alignment data by using a logic(S40); feeding back the first alignment compensation value to the exposure apparatus(S50); transmitting second raw alignment data measured from the wafer transferred to an overlay measuring device(S90) after performing an exposing process(S60); calculating a second alignment compensation value from the second raw alignment data by the logic(S100); and feeding back the second alignment compensation value to the exposure apparatus(S110). Further, the first and the second raw alignment data are deduced by measuring alignment marks formed at the wafer.

Description

A wafer alignment method of an exposure apparatus and an exposure system using the same {{FIELD OF ALIGNING A WAFER IN AN EXPOSURE APPARATUS AND AN EXPOSURE SYSTEM USING THE SAME}

1 is a process flowchart showing a wafer alignment method of an exposure apparatus according to an embodiment of the present invention.

2 is a block diagram of an exposure system using a wafer alignment method of an exposure apparatus according to an embodiment of the present invention.

3 is a surface view of a wafer on which shots are formed.

4 is an exploded perspective view of a part of the exposure apparatus.

5 is a process flowchart showing a wafer alignment method of the exposure apparatus according to another embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

100 exposure system 110 exposure apparatus

112, 122: first and second measuring units 114, 124: first and second transmitting units

116: correction unit 120: overlay device

130: server 132: data calculation unit

134: correction value calculation unit 136: correction value transmission unit

W: Wafer R: Reticle

The present invention relates to a wafer alignment method of an exposure apparatus and an exposure system using the wafer alignment method. More specifically, the present invention relates to a wafer alignment method capable of effectively preventing mis-alignment of a photoresist pattern formed on a wafer and an exposure system using the wafer alignment method of the exposure apparatus. .

Generally, the photolithography process of a semiconductor device includes a coating process, a baking process, an exposure process, and a developing process.

In performing the exposure and development processes, the alignment of the wafer and the reticle is very important in order to accurately transfer the image pattern to a predetermined position on the wafer. This is because the design rule of the circuit pattern formed on the wafer is miniaturized, and a very strict precision of the pattern dimension precision to be controlled is required to be several nm.

Therefore, in order to prevent misalignment occurring in the photoresist pattern formed by exposure and development, an alignment step of adjusting the position of the wafer and the reticle is generally provided in the exposure process. The overlay measurement process for confirming the alignment degree of the formed photoresist pattern is separately set.

Referring to the conventional alignment step, the process conditions such as the size of the wafer, the number and size of the shots of the wafer are input to the exposure apparatus, and the exposure apparatus to which the process conditions are input first aligns the wafer stage and the reticle stage relatively. Let's do it. Thereafter, the alignment state of the wafer is checked in the exposure apparatus. That is, the overlapping position between the pattern layer formed on the wafer and the reference value of the pattern layer is measured. At this time, since the pattern layers formed in the cells of the wafer are too complex to measure the overlapping degree, the overlapping degree is measured using alignment marks formed on the scribe lane of the wafer.

Thereafter, the degree of overlapping measured in the alignment marks is analyzed retrospectively to calculate alignment data. In this case, the logic for the regression analysis may be different for each exposure apparatus. The alignment correction value is calculated using the logic in the alignment data calculated as described above, and the alignment correction value is fed back to the exposure apparatus so that a misalignment is not generated in a subsequent wafer. At this time, when the alignment state is out of the preset range, the exposure apparatus corrects itself.

 On the other hand, in the conventional overlay measurement process, in the case of the wafer, the degree of overlap between the alignment mark of the pattern layer formed by the exposure process and the alignment mark of the pattern layer already formed under the pattern layer is measured and aligned through separate logic. Calculate data and alignment corrections. In the case of the reticle, the degree of alignment data and the alignment correction value are derived using the degree of overlap measured on the wafer. Thus, the respective calculated alignment correction values of the wafer and the reticle are fed back to the exposure apparatus to prevent the misalignment of the wafer.

However, according to the wafer alignment method of the conventional exposure apparatus, when calculating the alignment data and the alignment correction value from the measured overlapping degree, the logic used by each of the exposure apparatus and the overlay measuring device is different, which is derived from the same overlapping degree. Differences in alignment data and alignment correction values result in difficult alignment of the wafer. In addition, since the overlay measuring device is separately arranged in addition to the exposure device, the overlapping measurement and the alignment correction value are generated, thereby making the process step complicated.

One object of the present invention is to provide a wafer alignment method of an accurate and simplified exposure apparatus.

Another object of the present invention is to provide an exposure system using the wafer alignment method.

In order to achieve the above object of the present invention, in the wafer alignment method of the exposure apparatus according to the preferred embodiment of the present invention, the first raw alignment data measured from the wafer located in the exposure apparatus is transmitted to the server. A first alignment correction value is calculated from the first raw alignment data using logic, and then the first alignment correction value is fed back to the exposure apparatus. After performing the exposure process, the second raw alignment data measured from the wafer transferred to the overlay measurement apparatus is transmitted to the server. After the second alignment correction value is calculated from the second raw alignment data using the logic, the second alignment correction value is fed back to the exposure apparatus.

Further, in order to achieve the above object of the present invention, in the wafer alignment method of the exposure apparatus according to another preferred embodiment of the present invention, the first raw alignment data measured from the wafer located in the exposure apparatus is transmitted to the server. . After a first alignment correction value is calculated from the first raw alignment data using a first logic, a second alignment correction value is calculated from the first alignment correction value using a second logic. The second alignment correction value is fed back to the exposure apparatus.

In order to achieve the above object of the present invention, an exposure system according to a preferred embodiment of the present invention includes an exposure apparatus, an overlay measuring apparatus, and a server. The exposure apparatus performs an exposure process of a wafer, and includes a first measuring unit measuring first raw alignment data from the wafer, a first transfer unit transmitting the first raw alignment data to a server, and first and second alignment units. And a correction unit configured to correct the alignment of the wafer by receiving feedback of correction values. The overlay measurement apparatus includes an overlay measurement process of the wafer, and includes a second measurement unit measuring second raw alignment data from the wafer, and a second transfer unit transmitting the second raw alignment data to the server. The server may include a calculator configured to calculate the first and second alignment correction values from the first and second raw alignment data, and a third transmitter to feed back the first and second alignment correction values to the exposure apparatus. Include.

According to the present invention, the wafer alignment method and the wafer alignment method of the exposure apparatus are precisely and simplified by calculating the alignment correction values by the same logic in the same server using the raw alignment data measured by the exposure apparatus and the overlay apparatus, respectively. An exposure system can be provided.

Hereinafter, a wafer alignment method of an exposure apparatus and an exposure apparatus using the same according to preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not limited to the following embodiments. Those skilled in the art may implement the present invention in various other forms without departing from the technical spirit of the present invention. In the accompanying drawings, the dimensions of the components are enlarged than actual for clarity of the invention. When components are referred to as "first," "second," "third," and / or "fourth," they are not intended to limit these components but merely to distinguish them. Thus, "first", "second", "third" and / or "fourth" may be used selectively or interchangeably with respect to the components, respectively. When the first component is referred to as being formed "on" of the second component, the first component may be formed between the first component and the second component as well as when the first component is directly formed on the second component. Three components may be interposed.

1 is a process flow chart illustrating a wafer alignment method of an exposure apparatus according to an embodiment of the present invention, FIG. 2 is a block diagram of an exposure system using a wafer alignment method of the exposure apparatus according to an embodiment of the present invention. 3 is a table of a wafer on which shots are formed, and FIG. 4 is an exploded perspective view of a part of the exposure apparatus.

1 to 4, a wafer alignment method of an exposure apparatus according to an exemplary embodiment and an exposure system using the same will be described.

An exposure system using a wafer alignment method of an exposure apparatus according to an embodiment of the present invention includes an exposure apparatus 110, an overlay measurement apparatus 120, and a server 130.

The exposure apparatus 110 includes a first measurement unit 112, a first transmission unit 114, and a correction unit 116.

First, the wafer W is transferred to the exposure apparatus 110 (step S10). At this time, the wafer W is disposed on the wafer stage S. FIG. On the other hand, a reticle R for forming a desired photoresist pattern (not shown) on the wafer W is disposed on a reticle stage (not shown) disposed above the wafer stage S.

Thereafter, the moisture of the surface of the wafer W is removed, a pre-baking process for increasing the adhesion between the photoresist to be applied and the surface of the wafer W, and scrubbing to remove impurities on the surface of the wafer W A scrubbing process, a spin coating process for uniform coating, a soft-baking process for volatilizing the solvent and curing the photoresist are performed.

On the other hand, the wafer stage S and the reticle stage are moved to align the position between the wafer W and the reticle R. In this case, the alignment is performed by using a first alignment mark (not shown) formed on the wafer W and a second alignment mark (not shown) formed on the reticle R.

Thereafter, the first measurement unit 112 measures the first raw alignment data indicating the alignment state of the wafer W (step S20). That is, a part of the pattern (not shown) already formed by the previous exposure process is selected, and the degree of position overlap with the reference value of the pattern is measured. Since the overlapping degree cannot be measured by comparing all patterns in the wafer W cell area, a first alignment mark is formed in the scribe lane area on the wafer W, and the overlapping degree in the first alignment mark is determined. By confirming, the first raw alignment data can be measured. At this time, since it takes too long to measure the degree of overlap for all of the plurality of first alignment marks formed on the wafer W, sampling only a portion of the first alignment marks formed on the wafer W. Measure the degree of overlap. That is, the first raw alignment data is measured by sampling shots A to be measured in the cell area and measuring overlapping degrees of the first alignment marks included in the sampled shots A, respectively. Detect.

The degree of overlap of the first alignment marks is x and y, which are distances from the designated position (eg, the center) of the wafer W to the center of the first alignment mark, and the first alignment marks formed on the pattern to be measured and their It may include a value obtained by measuring each of dx and dy between the reference values.

The detected first raw alignment data is transmitted to the server 130 through the first transmission unit 114 (step S30).

The server 130 includes a data calculator 132, a correction value calculator 134, and a correction value transmitter 136.

The data calculator 132 calculates first alignment data from the first raw alignment data transmitted to the server 130 using logic (step S40). In this case, the first alignment data may include an offset, scaling, rotation, and orthogonality of the wafer W. The offset represents the degree to which the pattern is shifted left and right, up and down, and the scaling represents the degree to which the pattern on the wafer W is enlarged to the left and right and up and down by the lens, and the rotation value indicates that the axis of the pattern is shifted with respect to the reference axis The orthogonal value represents the degree to which the axes of the wafers W are twisted with each other.

The data calculator 132 then calculates a first alignment correction value from the calculated first alignment data using the logic (step S40).

The correction value transmission unit 136 feeds the first alignment correction value back to the correction unit 116 of the exposure apparatus 110 (step S50). Thereby, the position of the wafer W arrange | positioned in the exposure apparatus 110 is aligned.

Then, the light provided from the light source (not shown) is irradiated onto the wafer W through the mask pattern (not shown) of the reticle R and the lens system L to reticle R on the wafer W. An exposure process and other development processes, a hard-baking process, and the like, which reduce and project the mask pattern of the mask are performed.

After the above processes are performed, the wafer W is transferred to the overlay measurement apparatus 120 (step S70).

Meanwhile, the overlay measuring device 120 includes a second measuring unit 122 and a second transmitting unit 124.

The second measuring unit 122 measures the degree of overlap between the upper pattern (not shown) formed on the wafer W and the lower pattern (not shown) formed under the upper pattern by the exposure process. The second raw alignment data is measured (step S80). That is, the second raw alignment data may be measured by checking the overlapping degree of the first alignment marks formed in the scribe lane regions of the upper and lower patterns. In this case, only a portion of the first alignment marks formed on the wafer W may be sampled to measure the overlapping degree. The degree of overlap of the first alignment marks is x and y, which are distances from the designated position of the wafer W to the center of the first alignment mark, and dx and dy of the first alignment marks formed on the upper and lower patterns, respectively. It can include the measured value. Meanwhile, the second raw alignment data may further include reticle R related data. In this case, the reticle R related data may be estimated and derived from the wafer W related data.

 The detected second raw alignment data is transmitted to the server 130 through the second transmission unit 124 (step S90).

The data calculator 132 included in the server 130 calculates second alignment data from the second raw alignment data using the logic (step S100). In this case, the second alignment data may include an offset, scaling, rotation, and orthogonality of the wafer W. In addition, the second alignment data may include a rotation value and a reduction value of the reticle R. The rotation value of the reticle indicates the degree to which the reticle R is incorrectly set so that the axis of the pattern is misaligned with respect to the reference axis. It shows the degree enlarged up and down.

The data calculator 132 then calculates a second alignment correction value from the calculated second alignment data using the logic (step S100).

The correction value transmission unit 136 feeds the second alignment correction value back to the correction unit 116 of the exposure apparatus 110 (step S110). Accordingly, the positions of the wafer W and the reticle R disposed in the exposure apparatus 110 may be rearranged.

5 is a process flowchart showing a wafer alignment method of the exposure apparatus according to another embodiment of the present invention.

2 to 5, the wafer W is transferred to the exposure apparatus 110 (step S210), the first raw alignment data is measured (step S220), and the first raw alignment data is transferred to the server 130. ) And calculating the first alignment data and the first alignment correction value using the first logic (step S240) are substantially the same as described above.

Thereafter, the second alignment correction value is calculated using the second logic (step S250). This is possible by repeatedly performing the experiment according to the above embodiment in advance.

That is, as described above, the same server 130 receives the first and second raw alignment data from the exposure apparatus 110 and the overlay measurement apparatus 120, and furthermore, the first and second alignment data. Since the first and second alignment correction values can be calculated, correlations between them can be derived through repeated experiments.

The first raw alignment data measured by the exposure apparatus 110 and thus the first alignment data and the first alignment correction value, the second raw alignment data measured by the overlay measurement device 120 and thus The server 130 may continuously accumulate the data of the second alignment data and the second alignment correction value. Therefore, after sufficient data has been accumulated, instead of skipping the overlay measurement process performed by the overlay measurement apparatus 120, the server 130 directly calculates the second alignment correction value through the second logic using the correlation. This may be fed back to the exposure apparatus 110 (step S260).

As a result, after the positions of the wafer W and the reticle R of the exposure apparatus 110 are aligned by the feedback, the exposure process may be performed (step S270).

According to the present invention, raw alignment data measured by the exposure apparatus and the overlay measurement apparatus are received from the same server, and the alignment data and the alignment correction value are calculated using the same logic and fed back to the exposure apparatus, thereby providing more precise and simpler operation. The wafer can be aligned.

In addition, by receiving and accumulating the raw alignment data measured by the exposure apparatus and the overlay measuring device continuously at the server, the raw alignment data of the exposure apparatus and the overlay apparatus and between the alignment data and alignment correction values calculated therefrom Correlation can be seen. Therefore, by using this, it is possible to omit the overlay measurement process in the overlay measurement device, it is possible to simplify the process.

Although described with reference to the preferred embodiment of the present invention as described above, those of ordinary skill in the art will be various within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims It will be understood that modifications and changes can be made.

Claims (8)

Transmitting the first raw alignment data measured from the wafer located in the exposure apparatus to the server; Calculating a first alignment correction value from the first raw alignment data using logic; Feeding back the first alignment correction value to the exposure apparatus; After performing the exposure process, transmitting second raw alignment data measured from the wafer transferred to an overlay measuring device to the server; Calculating a second alignment correction value from the second raw alignment data using the logic; And And feeding back the second alignment correction value to the exposure apparatus. The method of claim 1, wherein the first and second raw alignment data are derived by measuring an alignment mark formed on the wafer. The exposure apparatus of claim 1, wherein the first and second alignment correction values are correction values of each of the first and second alignment data derived by regression analysis of the first and second raw alignment data. Wafer sorting method. The method of claim 3, wherein the first and second alignment data include offset, scaling, and rotation values of the wafer and rotation and reduction values of the reticle. Transmitting the first raw alignment data measured from the wafer located in the exposure apparatus to the server; Calculating a first alignment correction value from the first raw alignment data using first logic; Calculating a second alignment correction value from the first alignment correction value using a second logic; And And feeding back the second alignment correction value to the exposure apparatus. The method of claim 5, wherein the second logic, A second computed by using the first logic by transmitting the first alignment correction value, second raw alignment data measured from the wafer transferred to an overlay measuring device after performing an exposure process, and the second raw alignment data to the server; 2 The correlation coefficient between the alignment correction values is derived in advance through an iterative experiment, and formed using the derived correlation coefficient. Performing the exposure process of the wafer, A first measurement unit which measures first raw alignment data from the wafer, and a first transfer unit which transmits the first raw alignment data to a server. An exposure apparatus including a correction unit configured to correct the alignment state of the wafer by receiving feedback of first and second alignment correction values; Performing an overlay measurement process of the wafer, An overlay measurement device including a second measurement unit measuring second raw alignment data from the wafer and a second transfer unit transmitting the second raw alignment data to the server; A calculator configured to calculate the first and second alignment correction values using the same logic from the first and second raw alignment data, respectively; And And a server including a correction value transmitter for feeding back the first and second alignment correction values to the exposure apparatus. The method of claim 7, wherein the calculation unit, A data calculator configured to calculate first and second alignment data from the first and second raw alignment data, respectively; And And a correction value calculator for calculating the first and second alignment correction values from the first and second alignment data, respectively.

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