TWI749809B - Method for generating swing curve - Google Patents

Abstract

A method for generating a swing curve includes the following steps. A spin coating process is performed on a first wafer to form a photoresist layer on the first wafer, wherein in the spin coating process, a nozzle of a photoresist coater moves from the center of the first wafer toward the edge of the first wafer. A thickness measurement process is performed to measure the thicknesses of the photoresist layer at positions and obtain thickness measurement values. An exposure process is performed on the photoresist layer. A development process is performed on the photoresist layer to form a patterned photoresist layer including feature patterns. A critical dimension measurement process is performed to measure the critical dimension of the feature pattern corresponding to each position of the positions and to obtain critical dimension measurement values. A swing curve is obtained by a corresponding relationship between the critical dimension measurement values and the thickness measurement values.

Description

How to generate the swing curve

The present invention relates to a method for generating a curve, and particularly relates to a method for generating a swing curve.

In the semiconductor manufacturing process, the lithography process is one of the most important steps. In the photolithography process, after the photoresist layer is exposed and developed, a patterned photoresist layer with a characteristic pattern can be obtained. In addition, in the lithography process, the critical dimension (CD) of the feature pattern on the patterned photoresist layer versus the thickness of the photoresist layer is used to determine the photoresist layer used in the process. An important factor in thickness. The swing curve shows that the key dimensions of the characteristic pattern formed by the photoresist layer after exposure and development show an oscillating waveform with the thickness of the photoresist layer. Therefore, the optimal thickness of the photoresist layer corresponding to the critical dimensions required by the subsequent process can be determined by the swing curve, so as to facilitate the subsequent process.

At present, the method of generating the swing curve is to form photoresist layers of different thicknesses on multiple wafers, and then expose and develop these photoresist layers respectively to obtain the characteristic patterns corresponding to the photoresist layers of different thicknesses. The key size of, and the swing curve is obtained by the corresponding relationship between the thickness of the photoresist layer and the key size of the feature pattern. However, the current method for generating the swing curve requires the use of multiple wafers and a long time, which will increase the process time and manufacturing cost.

The invention provides a method for generating a swing curve, which can reduce the process time and manufacturing cost required to obtain the swing curve.

The present invention provides a method for generating a swing curve, which includes the following steps. A photoresist coater is used to perform a spin coating process on the first wafer, and a photoresist layer is formed on the first wafer. In the spin coating process, the nozzle of the photoresist coater is replaced by the first wafer The center moves toward the edge of the first wafer. A thickness measurement process is performed to measure the thickness of the photoresist layer at multiple positions and obtain multiple thickness measurement values. An exposure process is performed on the photoresist layer. A development process is performed on the photoresist layer to form a patterned photoresist layer including a plurality of feature patterns. A key dimension measurement process is performed to measure the key dimension of the feature pattern corresponding to each of the multiple positions, and obtain multiple key dimension measurement values. The oscillation curve of the key dimension of the feature pattern versus the thickness of the photoresist layer is obtained by the correspondence between the multiple key dimension measurement values and the multiple thickness measurement values.

According to an embodiment of the present invention, in the above-mentioned oscillation curve generation method, the nozzle movement method is, for example, a continuous movement method or a stepwise movement method.

According to an embodiment of the present invention, in the above-mentioned oscillation curve generation method, the spin coating process can be repeated, so that the nozzle repeatedly moves from the center of the first wafer to the edge of the first wafer to enlarge The thickness difference between the photoresist layer located at the center of the first wafer and the photoresist layer located at the edge of the first wafer.

According to an embodiment of the present invention, in the above-mentioned oscillation curve generation method, the rotation speed of the spin coating process can be gradually reduced when the nozzle moves from the center of the first wafer to the edge of the first wafer , To enlarge the thickness difference between the photoresist layer located at the center of the first wafer and the photoresist layer located at the edge of the first wafer.

According to an embodiment of the present invention, in the above-mentioned method for generating a swing curve, the thickness measuring device of the photoresist layer is, for example, an optical thickness measuring device.

According to an embodiment of the present invention, in the above-mentioned oscillation curve generation method, the optical thickness measurement device is, for example, a reflectometer or an ellipsometer.

According to an embodiment of the present invention, the above-mentioned method for generating a swing curve may further include the following steps. After the spin coating process, the photoresist layer is subjected to a soft bake process. The thickness measurement process can be performed after the soft baking process.

According to an embodiment of the present invention, the above-mentioned method for generating a swing curve may further include the following steps. After the development process, the patterned photoresist layer is subjected to a hard bake process. The critical dimension measurement process can be performed after the hard baking process.

According to an embodiment of the present invention, the above-mentioned method for generating a swing curve may further include the following steps. The spin coating process, the thickness measurement process, the exposure process, the development process, and the critical dimension measurement process are performed on the second wafer. The rotation speed of the spin coating process performed on the first wafer may be greater than the rotation speed of the spin coating process performed on the second wafer. The oscillation curve of the key dimension of the feature pattern versus the thickness of the photoresist layer is obtained by the correspondence between the multiple key dimension measurement values and the multiple thickness measurement values on the first wafer and the second wafer.

According to an embodiment of the present invention, in the above-mentioned method for generating a swing curve, at the same position, the thickness of the photoresist layer on the first wafer may be smaller than the thickness of the photoresist layer on the second wafer.

Based on the above, in the method for generating the swing curve proposed by the present invention, in the spin coating process, because the stage of the photoresist coating machine rotates, centrifugal force is generated, so the nozzle of the photoresist coating machine spray The photoresist will only flow towards the edge of the first wafer. In this way, in the spin coating process, by moving the nozzle of the photoresist coater from the center of the first wafer to the edge of the first wafer, the thickness of the photoresist layer can be changed from that of the first wafer. The center gradually increases toward the edge of the first wafer. In this way, the key dimensions of the feature patterns corresponding to the different thicknesses of the photoresist layer can be collected at multiple positions on the same wafer, so that the process time and manufacturing cost required to obtain the swing curve can be reduced.

In order to make the above-mentioned features and advantages of the present invention more comprehensible, the following specific embodiments are described in detail in conjunction with the accompanying drawings.

FIG. 1 is a flowchart of a method for generating a swing curve according to an embodiment of the present invention. 2 is a schematic diagram of a spin coating process using a photoresist coater according to an embodiment of the present invention. Fig. 3 is a swing curve diagram according to an embodiment of the present invention. 4 is a schematic diagram of a spin coating process using a photoresist coater according to other embodiments of the present invention. Fig. 5 is a graph of swing curves according to other embodiments of the present invention.

Please refer to FIGS. 1 and 2 to proceed to step S100. Use the photoresist coater 100 to perform a spin coating process on the wafer W1 and form a photoresist layer 200 on the wafer W1. In the spin coating process, The nozzle 102 of the photoresist coater 100 moves from the center of the wafer W1 to the edge of the wafer W1 (as shown by the arrow in FIG. 2). The movement method of the nozzle 102 is, for example, a continuous movement method or a stepwise movement method. The step-by-step movement method means that the nozzle 102 will stop in stages during the movement. Since the stage 104 of the photoresist coater 100 generates centrifugal force when rotating, the photoresist 202 ejected from the nozzle 102 of the photoresist coater 100 only flows toward the edge of the wafer W1. In this way, in the spin coating process, by moving the nozzle 102 of the photoresist coater 100 from the center of the wafer W1 to the edge of the wafer W1, the thickness of the photoresist layer 200 can be changed from the center of the wafer W1. Gradually increase toward the edge of wafer W1. For example, the thickness T1 of the photoresist layer 200 at the center of the wafer W1 is smaller than the thickness T2 of the photoresist layer 200 at the edge of the wafer W1.

In this embodiment, although one spin coating process is taken as an example, the present invention is not limited to this. In some embodiments, the spin coating process can be repeated, and the nozzle 102 is repeatedly moved from the center of the wafer W1 to the edge of the wafer W1 to enlarge the photoresist layer 200 and the position in the center of the wafer W1. The thickness difference between the photoresist layers 200 at the edge of the wafer W1.

In this embodiment, the rotation speed of the spin coating process is a fixed rotation speed as an example, but the invention is not limited to this. In other embodiments, when the nozzle 102 moves from the center of the wafer W1 to the edge of the wafer W1, the rotation speed of the spin coating process can be gradually reduced to amplify the photoresist in the center of the wafer W1. The thickness difference between the layer 200 and the photoresist layer 200 located at the edge of the wafer W1.

Then, step S102 can be performed to perform a soft baking process on the photoresist layer 200. The temperature of the soft baking process is, for example, 70°C to 150°C.

Then, step S104 is performed to perform a thickness measurement process to measure the thickness of the photoresist layer 200 (eg, thickness T1, thickness T2, etc.) at multiple positions, and obtain multiple thickness measurement values. For example, multiple positions can be selected at different distances from the center of the wafer W1 to the edge of the wafer W1 for thickness measurement. The thickness measuring device of the photoresist layer 200 is, for example, an optical thickness measuring device. The optical thickness measuring device is, for example, a reflectometer or an ellipsometer, but the invention is not limited to this.

Next, step S106 is performed to perform an exposure process on the photoresist layer 200. For example, a photomask can be used as a mask to perform an exposure process on the photoresist layer 200. The light source used in the exposure process is, for example, mercury lamp G-line (wavelength 436 nm), mercury lamp I-line (wavelength 365 nm), krypton fluoride (KrF) excimer laser (wavelength 248 nm) or fluorinated Argon (ArF) excimer laser (wavelength 193 nm).

Subsequently, step S108 is performed to perform a development process on the photoresist layer 200 to form a patterned photoresist layer including a plurality of feature patterns. The feature pattern can be a line or a space.

Then, step S110 may be performed to perform a hard baking process on the patterned photoresist layer. The temperature of the hard baking process is, for example, 80°C to 180°C.

Furthermore, step S112 is performed to perform a key dimension measurement process to measure the key dimension of the feature pattern corresponding to each of the multiple positions, and obtain multiple key dimension measurement values. The measuring device for the critical dimension of the feature pattern is, for example, a scanning electron microscope (Scanning Electron Microscope, SEM).

Then, step S114 is performed to obtain the swing curve S1 of the key dimension of the feature pattern versus the thickness of the photoresist layer 200 by the correspondence between the key dimension measurement values and the thickness measurement values (FIG. 3 ). That is, the swing curve S1 can be drawn by the correspondence between the multiple key dimension measurement values and the multiple thickness measurement values.

In other embodiments, the method for generating the swing curve may include the following steps in addition to obtaining the swing curve S1 through the above steps.

First, the spin coating process, the thickness measurement process, the exposure process, the development process, and the critical dimension measurement process as described in FIG. 1 are performed on the wafer W2, and the soft baking process and the critical dimension measurement process as described in FIG. 1 can be performed. Hard baking process. The rotation speed R1 of the spin coating process performed on the wafer W1 may be greater than the rotation speed R2 of the spin coating process performed on the wafer W2. In this way, at the same position, the thickness of the photoresist layer 200 on the wafer W1 can be smaller than the thickness of the photoresist layer 300 on the wafer W2. For example, the thickness T1 (FIG. 2) of the photoresist layer 200 located in the center of the wafer W1 is smaller than the thickness T3 (FIG. 4) of the photoresist layer 300 located in the center of the wafer W2, and it is located in the wafer W1 The thickness T2 of the photoresist layer 200 at the edge of the wafer W2 (FIG. 2) is smaller than the thickness T4 of the photoresist layer 300 at the edge of the wafer W2 (FIG. 4 ). In addition, the spin coating process performed on the wafer W1 and the spin coating process performed on the wafer W2 use the same photoresist material. In this embodiment, the wafer W1 and the wafer W2 may be different wafers, but the invention is not limited to this. In other embodiments, the wafer W1 and the wafer W2 may be the same wafer, that is, the wafer W2 may be a wafer W1 that is recycled after removing the patterned photoresist layer on the wafer W1.

Then, the oscillation curve S of the critical dimension of the feature pattern versus the thickness of the photoresist layer is obtained by the correspondence between the multiple key dimension measurement values and the multiple thickness measurement values on the wafer W1 and the wafer W2 (Figure 5). For example, as shown in FIG. 5, the key dimension of the feature pattern versus the photoresist layer can be obtained by the correspondence between multiple key dimension measurement values and multiple thickness measurement values measured on the wafer W2. The swing curve S2 with a thickness of 300 is combined with the swing curve S1 and the swing curve S2 to obtain the swing curve S. In addition, the oscillation curve S1 obtained by the rotation speed R1 and the oscillation curve S2 obtained by the rotation speed R2 may have overlapping parts. In other embodiments, after obtaining the swing curve S (ie, the swing curve S1 and the swing curve S2), steps S100 to S114 in FIG. 1 can be repeated, and the rotation speed of the spin coating process in step S100 can be adjusted , In order to obtain a wider range of swing curves.

Based on the foregoing embodiment, it can be seen that in the method for generating the swing curve, in the spin coating process, the stage 104 of the photoresist coater 100 generates centrifugal force when rotating, so the nozzle 102 of the photoresist coater 100 The ejected photoresist will only flow to the edge of the wafer W1. In this way, in the spin coating process, by moving the nozzle 102 of the photoresist coater 100 from the center of the wafer W1 to the edge of the wafer W1, the thickness of the photoresist layer 200 can be changed from that of the wafer W1. The center gradually increases toward the edge of wafer W1. In this way, the key dimensions of the feature patterns corresponding to the different thicknesses of the photoresist layer 200 can be collected at multiple positions on the same wafer W1, so that the process time and manufacturing cost required to obtain the swing curve S1 can be reduced.

In summary, in the oscillation curve generation method of the above embodiment, by moving the nozzle of the photoresist coater from the center of the wafer to the edge of the wafer, the light obtained by the spin coating process can be made The thickness of the barrier layer changes. In this way, the key dimensions of the feature patterns corresponding to the different thicknesses of the photoresist layer can be collected on the same wafer, so the process time and manufacturing cost required to obtain the swing curve can be reduced.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to those defined by the attached patent scope.

100: Photoresist coating machine 102: Nozzle 104: Stage 200, 300: photoresist layer 202: photoresist R1, R2: Rotation speed S, S1, S2: swing curve S100, S102, S104, S106, S108, S110, S112, S114: steps T1, T2, T3, T4: thickness W1, W2: Wafer

FIG. 1 is a flowchart of a method for generating a swing curve according to an embodiment of the present invention. 2 is a schematic diagram of a spin coating process using a photoresist coater according to an embodiment of the present invention. Fig. 3 is a swing curve diagram according to an embodiment of the present invention. 4 is a schematic diagram of a spin coating process using a photoresist coater according to other embodiments of the present invention. Fig. 5 is a graph of swing curves according to other embodiments of the present invention.

S100, S102, S104, S106, S108, S110, S112, S114: steps

Claims (9)

A method for generating a swing curve includes: using a photoresist coater to perform a spin coating process on a first wafer, and forming a photoresist layer on the first wafer, wherein during the spin coating process , The nozzle of the photoresist coater moves from the center of the first wafer to the edge of the first wafer, and the nozzle moves from the center of the first wafer to the first wafer During the movement of the edge of the first wafer, the rotation speed of the spin coating process is gradually reduced to amplify the photoresist layer located in the center of the first wafer and all the edges located on the edge of the first wafer. The thickness difference between the photoresist layers; perform a thickness measurement process to measure the thickness of the photoresist layer at multiple positions and obtain multiple thickness measurement values; perform an exposure process on the photoresist layer; The photoresist layer undergoes a development process to form a patterned photoresist layer including a plurality of characteristic patterns; a critical dimension measurement process is performed to measure the characteristic pattern corresponding to each of the plurality of positions And obtain a plurality of key dimension measurement values; and obtain the key dimension of the characteristic pattern by the correspondence between the plurality of key dimension measurement values and the plurality of thickness measurement values Oscillation curve to the thickness of the photoresist layer. The method for generating a swing curve according to claim 1, wherein the movement method of the nozzle includes a continuous movement method or a stepwise movement method. The method for generating a swing curve according to claim 1, wherein the spin coating process is repeated, and the nozzle is repeatedly moved from the center of the first wafer to the edge of the first wafer, The thickness difference between the photoresist layer located at the center of the first wafer and the photoresist layer located at the edge of the first wafer is enlarged. The method for generating a swing curve according to claim 1, wherein the measuring device for the thickness of the photoresist layer includes an optical thickness measuring device. The method for generating a swing curve according to claim 4, wherein the optical thickness measurement device includes a reflectometer or an ellipsometer. The method for generating a swing curve according to claim 1, further comprising: performing a soft baking process on the photoresist layer after the spin coating process, wherein the thickness measurement process is performed in the soft baking process Afterwards. The method for generating a swing curve according to claim 1, further comprising: performing a hard baking process on the patterned photoresist layer after the development process, wherein the critical dimension measurement process is performed in the hard baking process. After the manufacturing process. The method for generating a swing curve according to claim 1, further comprising: performing the spin coating process, the thickness measurement process, the exposure process, the development process, and the key on a second wafer The size measurement process, wherein the rotation speed of the spin coating process performed on the first wafer is greater than the rotation speed of the spin coating process performed on the second wafer; and by the second wafer Correspondence between the plurality of key dimension measurement values and the plurality of thickness measurement values on a wafer and the second wafer to obtain the characteristic pattern The swing curve of the critical dimension to the thickness of the photoresist layer. The method for generating a swing curve according to claim 8, wherein at the same position, the thickness of the photoresist layer on the first wafer is smaller than the thickness of the photoresist layer on the second wafer The thickness of the photoresist layer.

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