TWI763223B - Etching apparatus and etching method thereof - Google Patents

Abstract

An etching apparatus and etching method thereof are provided. An endpoint detector detects a light intensity at a specific wavelength of a light generated when a material to be processed is etched, and generates an endpoint detection signal. The material to be processed includes a material layer and at least one mask layer formed on the material layer. A control device determines an etching completion time of the mask layer according to the endpoint detection signal, calculates a thickness of the mask layer according to the etching completion time, and adjusts an etching time of the material layer according to the thickness of the mask layer.

Description

Etching system and etching method thereof

The present invention relates to a semiconductor device, and more particularly, to an etching system and an etching method thereof.

In recent years, with the development of semiconductor manufacturing process, the requirements for the integration and performance of components are getting higher and higher, and plasma technology (Plasma Technology) is playing a pivotal role in the field of semiconductor manufacturing. Plasma technology is used in many semiconductor processes, such as deposition processes (eg, chemical vapor deposition), etching processes (eg, dry etching), and the like. As the size of semiconductor devices shrinks and the complexity of circuits increases, the complexity of the mask film and the aspect ratio of the etched features also increase accordingly, and the precision requirements for the plasma processing process also become more stringent.

In the prior art, a light source is often provided in the etching chamber to provide light to the substrate to be etched, and the information of the etching depth is obtained by analyzing the spectrum of the reflected light emitted from the material to be etched, so as to determine whether to achieve Target etch end point. However, when the aspect ratio of the features on the substrate to be etched is higher, the reflected light is less likely to form complete interference fringes, which will easily lead to errors in the determination of the etching end point, thereby affecting the accuracy of the semiconductor process.

The invention provides an etching system and an etching method thereof, which can effectively improve the precision of the semiconductor manufacturing process.

The etching system of the present invention includes an etching device and a control device. The etching device performs etching processing on the material to be processed to form a characteristic structure. The etching device includes an end-point detector, which detects the light intensity at a specific wavelength of light generated when the material to be processed is etched, and generates an end-point detection signal. The material to be processed includes a material layer and at least one mask layer formed on the material layer. . The control device is coupled to the etching device, determines the etching completion time of the mask layer according to the end point detection signal, calculates the thickness of the mask layer according to the etching completion time, and adjusts the etching time of the material layer according to the thickness of the mask layer.

The present invention also provides an etching method for an etching system, which is used for etching the processed material to form a feature structure. The etching method of the etching system includes the following steps. The end point detection signal is generated by detecting the light intensity at a specific wavelength of the light generated when the processed material is etched, wherein the processed material includes a material layer and at least one mask layer formed on the material layer. The etching completion time of the mask layer is determined according to the end point detection signal. The thickness of the mask layer is calculated according to the etching completion time. The etching time of the material layer is adjusted according to the thickness of the mask layer.

Based on the above, the embodiment of the present invention determines the etching completion time of the mask layer according to the end point detection signal, calculates the thickness of the mask layer according to the etching completion time, and adjusts the etching time of the material layer according to the thickness of the mask layer. The thickness of the mask layer can be calculated from the etching completion time of the layer, so that the thickness of the mask layer can be accurately known, and then the progress of the etching process of the material layer can be accurately grasped, and the accuracy of the semiconductor process can be effectively improved.

FIG. 1 is a schematic diagram of an etching system according to an embodiment of the present invention, please refer to FIG. 1 . The etching system 100 includes an etching device 102 and a control device 104 , and the etching device 102 is coupled to the control device 104 . The etching device 102 is used for etching the processed material 108 to form a feature structure on the processed material 108 . As shown in FIG. 2 , the processed material 108 may include a photoresist layer 202 , a mask layer 204 and a material layer 206 , wherein the mask layer 204 is formed on the material layer 206 , and the photoresist layer 202 is formed on the mask layer 204 . In some embodiments, the photoresist layer 202 can be patterned by, for example, a lithography process, so that the photoresist layer 202 has a characteristic pattern, and the photoresist layer 202 with the characteristic pattern is used as a mask to cover the mask. Layer 204 and material layer 206 are etched to form features. In some embodiments, the material layer 206 may be an elemental semiconductor substrate (eg, a silicon substrate or a germanium-based substrate) or a compound semiconductor substrate (eg, a silicon carbide substrate or a gallium arsenide substrate). In some embodiments, the mask layer 204 may be formed of a dielectric material such as silicon oxide (SiO), silicon nitride (SiN), and silicon oxynitride (SiON).

In this embodiment, the etching device 102 can be, for example, a plasma etching device, but is not limited thereto. Further, the etching apparatus 102 may include an etching chamber R1 , an etching gas generator N1 and an endpoint detector 106 . The etching chamber R1 can accommodate the processed material 108. As shown in FIG. 1, the processed material 108 can be placed on the base B1 in the etching chamber R1. The etching gas generator N1 can generate etching gas to the etching chamber R1 to generate plasma to perform the etching process on the material to be processed 108 . The endpoint detector 106 can detect the endpoint detection signal generated by the light intensity at a specific wavelength of the light generated when the material 108 is etched. For example, in this embodiment, the endpoint detector 106 can detect the spectrum emitted by the plasma during the plasma etching process. Since the spectrum will change significantly when etching to different material layers, the endpoint generated by the endpoint detector 106 The detection signal also changes in signal intensity correspondingly, which can indicate whether the etching end point is reached.

The control device 104 can be, for example, a computer or other electronic device with computing capability, but not limited to this, the control device 104 can determine the etching completion time of the mask layer 204 according to the end point detection signal, that is, as shown on the right side of FIG. 2 . , the mask layer 204 is etched to the time required to reach the end point (material layer 206 ). The control device 104 can calculate the thickness of the mask layer 204 according to the etching completion time of the mask layer 204 . For example, the etching completion time of the mask layer 204 can be multiplied by the etching speed of the mask layer 204 to calculate the thickness of the mask layer 204 , wherein the etching rate of the mask layer 204 can be obtained, for example, by collecting data through conventional experiments. Since a change in the thickness of the mask layer 204 will concomitantly change the aspect ratio of the features formed on the processed material 108, and different aspect ratios require different etch times to etch the same depth in the material layer 206, the mask The thickness variation of the curtain layer 204 may correspond to the etching time of different material layers 206 . After obtaining the thickness of the mask layer 204 , the control device 104 can adjust the etching time of the material layer 206 according to the thickness of the mask layer 204 , so as to avoid the thickness variation of the mask layer 204 caused by the manufacturing process or other factors, thereby causing the material layer 206 to change. Insufficient etching depth or excessive etching occurs. In addition, since the etching system of this embodiment does not need to install a light source in the etching chamber as in the prior art, the information of the etching depth can be obtained by analyzing the reflected light, which can directly The light emitted by the slurry is detected, and the thickness of the mask layer 204 is calculated according to the etching time. Therefore, the mask layer 204 can be accurately obtained without increasing the measurement cost and without interrupting the etching process to measure the etching depth. The thickness (etching depth) information is obtained, so as to achieve the effect of precise etching of the material layer 206 .

Further, the control device 104 can calculate the thickness difference according to the thickness of the mask layer 204 , for example, subtract the preset thickness (eg, standard thickness) of the mask layer 204 from the calculated thickness of the mask layer 204 to obtain the thickness difference (that is, the thickness change value of the mask layer 204), and adjust the etching time of the material layer 206 according to the thickness difference, such as increasing or decreasing the etching time by a compensation time, to ensure that the material layer 206 can be etched to the expected depth. The relationship between the thickness difference and the compensation time of the etching material layer 206 can be obtained, for example, by collecting data through conventional experiments.

In some embodiments, the processed material 108 may also include multiple mask layers, but is not limited to only one mask layer in the embodiment shown in FIG. 2 . As shown in FIG. 3 , the processed material 108 may include a photoresist layer 302 , three mask layers 304 , 306 , 308 and a material layer 310 . In some embodiments, the material layer 310 may be an elemental semiconductor substrate (eg, a silicon substrate or germanium-based) or a compound semiconductor substrate (eg, a silicon carbide substrate or a gallium arsenide substrate). In some embodiments, the mask layers 304 , 306 , and 308 may be formed of dielectric materials such as silicon oxide (SiO), silicon nitride (SiN), and silicon oxynitride (SiON). Similarly, the endpoint detector 106 can detect the spectrum emitted by the plasma during the plasma etching process to generate an endpoint detection signal. For example, the endpoint detector 106 can detect light intensities of different specific wavelengths corresponding to different mask layers to generate corresponding endpoint detection signals. The control device 104 can determine the etching completion time of the mask layers 304, 306 and 308 according to the end point detection signals corresponding to the mask layers 304, 306 and 308, and respectively according to the etching completion time of the mask layers 304, 306 and 308 and the mask layer. The etch rate of the curtain layers 304 , 306 and 308 calculates the sum of the thicknesses of the mask layers 304 , 306 and 308 . The sum H of the thicknesses of the mask layers 304, 306 and 308 can be represented, for example, by the following formula: H=RA×TA＋RB×TB＋RC×TC (1)

RA, RB, and RB are the etching rates of the mask layers 304, 306, and 308, respectively, and TA, TB, and TC are the etching completion times of the mask layers 304, 306, and 308, respectively. In some embodiments, the relationship between the etching time of the mask layers 304, 306 and 308 and the corresponding etching thickness can also be stored in the storage circuit of the control device 104, and the control device 104 obtains the mask layer according to the end point detection signal After the etching completion times of 304 , 306 and 308 , the control device 104 can obtain the thicknesses of the mask layers 304 , 306 and 308 corresponding to the etching completion times of the mask layers 304 , 306 and 308 by means of a table look-up. For example, FIGS. 4A to 4C are schematic diagrams illustrating the relationship between the etching time of the mask layers 304 , 306 and 308 and the corresponding etching thickness. As shown in FIGS. 4A to 4C , the curves corresponding to different mask layers are different The slope (etching speed) of , the etching completion times TA, TB and TC may correspond to the thicknesses HA, HB and HC of the mask layers 304, 306 and 308, respectively. The control device 104 may add the thicknesses HA, HB, and HC to obtain the sum H of the thicknesses of the mask layers 304 , 306 , and 308 .

Similarly, the control device 104 may subtract the sum H of the thicknesses of the mask layers 304, 306, and 308 from the sum of the preset thicknesses of the mask layers 304, 306, and 308 to obtain the thickness difference HD (ie, the mask layer 304 , 306 and 308 ), and adjust the etching time of the material layer 310 according to the thickness difference. For example, the storage circuit of the control device 104 can store the etching compensation time of the material layer 310 corresponding to the thickness difference, so the control device 104 can obtain the etching compensation time of the material layer 310 corresponding to the thickness difference by looking up a table. For example, FIG. 5 is a schematic diagram illustrating the relationship between the compensation time of the etching material layer 310 and the thickness difference according to an embodiment of the present invention. As shown in FIG. 5 , each thickness difference can correspond to a compensation time. For example, the thickness difference HD in the embodiment of FIGS. 4A to 4C can correspond to the compensation time TD, and the control device 104 can add the etching time of the material layer 310 to The compensation time TD ensures that the material layer 310 can be precisely etched to the desired depth. It should be noted that the thickness difference HD can be positive or negative, and the corresponding compensation time TD can also be positive or negative, that is, the control device 104 can increase or decrease the etching time of the material layer 310, In order to achieve precise etching of the material layer 310 .

6 is a flowchart of an etching method of an etching system according to an embodiment of the present invention. It can be known from the above embodiments that the etching method of the etching system may include the following steps. First, detecting the light intensity at a specific wavelength of the light generated when the material to be processed is etched to generate an endpoint detection signal (step S602 ), wherein the material to be processed includes a material layer and at least one mask layer formed on the material layer. The etching process can be, for example, a plasma etching process, but not limited thereto, the etching system can include an etching chamber for accommodating the material to be processed, and generates plasma to etch the material to be processed by generating an etching gas into the etching chamber deal with. Next, the etching completion time of the mask layer is determined according to the end point detection signal (step S604). Then, the thickness of the mask layer is calculated according to the etching completion time (step S606). Finally, the etching time of the material layer is adjusted according to the thickness of the mask layer (step S608 ). For example, the thickness difference of the mask layer can be calculated according to the thickness of the mask layer, and the etching time of the material layer can be adjusted according to the thickness difference, wherein the thickness The difference value may be the difference value of the thickness of the mask layer minus a preset thickness (eg, the standard thickness of the mask layer).

In the embodiment with multiple mask layers, the etching completion time of each mask layer can be determined according to the end point detection signal corresponding to each mask layer, and the thickness of each mask layer can be calculated according to the etching completion time of each mask layer . Then, the etching time of the material layer can be adjusted according to the sum of the thicknesses of the multiple mask layers. For example, the sum of the thicknesses of the multiple mask layers can be subtracted from the sum of the preset thicknesses of the multiple mask layers to obtain the thickness difference, and according to The thickness difference adjusts the etching time of the material layer.

To sum up, the present embodiment determines the etching completion time of the mask layer according to the end point detection signal, calculates the thickness of the mask layer according to the etching completion time, and adjusts the etching time of the material layer according to the thickness of the mask layer. In this way, the thickness of the mask layer can be calculated based on the etching completion time of the mask layer, so that the thickness of the mask layer can be accurately known, and the progress of the etching process of the material layer can be accurately grasped, thereby effectively improving the precision of the semiconductor process. In addition, since the etching system of this embodiment does not need to install a light source in the etching chamber as in the prior art, and obtain the information of the etching depth by analyzing the reflected light, it does not need to increase the measurement cost, nor does it need to By interrupting the etching process to measure the etching depth, the thickness (etching depth) information of the mask layer can be accurately obtained, so as to achieve the effect of precise etching of the material layer.

100: Etching System 102: Etching device 104: Controls 106: Endpoint Detector 108: Processed material 202: photoresist layer 204: Curtain layer 206: Material Layer 302: photoresist layer 304, 306, 308: Curtain layer 310: Material Layer R1: Etching chamber N1: Etching Gas Generator B1: Base TA, TB, TC: etching completion time HA, HB, HC: Thickness HD: Thickness difference TD: Compensation time S602~S608: the etching method steps of the etching system

FIG. 1 is a schematic diagram of an etching system according to an embodiment of the present invention. FIG. 2 is a schematic diagram of a processed material according to an embodiment of the present invention. FIG. 3 is a schematic diagram of a processed material according to another embodiment of the present invention. 4A to 4C are schematic diagrams illustrating the relationship between the etching time of the mask layer and the corresponding etching thickness. FIG. 5 is a schematic diagram of a relationship between compensation time and thickness difference of an etching material layer according to an embodiment of the present invention. 6 is a flowchart of an etching method of an etching system according to an embodiment of the present invention.

100: Etching System

102: Etching device

104: Controls

106: Endpoint Detector

108: Processed material

R1: Etching chamber

N1: Etching Gas Generator

B1: Base

Claims (10)

An etching system, comprising: an etching device for etching a processed material to form a feature structure, the etching device comprising: an end-point detector for detecting the etching of at least one mask layer of the processed material The light generated during processing generates a light intensity of a specific wavelength to generate an end point detection signal, the material to be processed includes a material layer and the at least one mask layer formed on the material layer; and a control device, coupled to the The etching device determines an etching completion time of the mask layer according to the end point detection signal, calculates the thickness of the mask layer according to the etching completion time, and adjusts the etching time of the material layer according to the thickness of the mask layer. The etching system of claim 1, wherein the control device calculates a thickness difference according to the thickness of the mask layer, and adjusts the etching time of the material layer according to the thickness difference, wherein the thickness difference is equal to the mask The thickness of the layer minus a preset thickness. The etching system according to claim 1, wherein the material to be processed comprises a plurality of mask layers, the control device judges the etching completion time of each mask layer according to the end point detection signal, and calculates according to the etching completion time of each mask layer The thickness of each mask layer, and the etching time of the material layer is adjusted according to the sum of the thicknesses of the mask layers. The etching system according to claim 1, wherein the control device multiplies the etching completion time of each mask layer by the corresponding etching speed to obtain the thickness of each mask layer. The etching system of claim 1, wherein the etching device further comprises: an etching chamber for containing the material to be processed; and an etching gas generator for generating an etching gas into the etching chamber to generate a plasma pair The material to be treated is subjected to the etching treatment. An etching method of an etching system is used for etching a processed material to form a feature structure. The etching method of the etching system includes: detecting that at least one mask layer of the processed material is subjected to the etching process. The light intensity of a specific wavelength generates an end point detection signal, wherein the processed material includes a material layer and the at least one mask layer formed on the material layer; according to the end point detection signal to determine the mask layer an etching completion time; calculating the thickness of the mask layer according to the etching completion time; and adjusting the etching time of the material layer according to the thickness of the mask layer. The etching method of an etching system according to claim 6, comprising: calculating a thickness difference of the mask layer according to the thickness of the mask layer; and adjusting the etching time of the material layer according to the thickness difference, wherein the thickness The difference is equal to the thickness of the mask layer minus a predetermined thickness. The etching method of an etching system according to claim 6, wherein the material to be processed comprises a plurality of mask layers, and the etching method of the etching system comprises: judging the etching completion time of each mask layer according to the end point detection signal; The etching completion time of the mask layers calculates the thickness of each mask layer; and adjusts the etching time of the material layer according to the sum of the thicknesses of the mask layers. The etching method of the etching system as claimed in claim 6, comprising: Multiply the etching completion time of each mask layer by the corresponding etching speed to obtain the thickness of each mask layer. The etching method of an etching system as claimed in claim 6, wherein the material layer is an elemental semiconductor substrate or a compound semiconductor substrate.

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