Etching System and Its Etching Method

Abstract

The present invention provides an etching system and an etching method thereof. An endpoint detector detects the light intensity at a specific wavelength of the light generated during the etching process of the material to be processed, 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. The control device determines the etching completion time of the mask layer according to the endpoint 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.

Description

Technical Field

[0001] The present invention relates to a semiconductor device, and in particular to an etching system and an etching method thereof. Background Art

[0002] In recent years, with the development of semiconductor technology, the requirements for the integration and performance of components are getting higher and higher. Plasma technology is playing a vital role in the field of semiconductor manufacturing. Plasma technology is used in many semiconductor processes by exciting process gases to form plasma, such as deposition processes (such as chemical vapor deposition) and etching processes (such as dry etching). As the size of semiconductor components decreases and the complexity of circuits increases, the complexity of the mask film and the aspect ratio of the etched feature structure also increase accordingly, and the accuracy requirements for plasma processing processes become more stringent.

[0003] In the prior art, a light source is often set in the etching chamber to provide light to the etched substrate, and the spectrum of the reflected light emitted from the etched material is analyzed to obtain information on the etching depth, thereby determining whether the target etching endpoint has been reached. However, when the aspect ratio of the feature structure on the etched substrate is higher, it is more difficult for the reflected light to form complete interference fringes, which will easily lead to errors in the judgment of the etching endpoint, thereby affecting the accuracy of the semiconductor process. Summary of the invention

[0004] The invention provides an etching system and an etching method thereof, which can effectively improve the accuracy of semiconductor technology.

[0005] The etching system of the present invention includes an etching device and a control device. The etching device etches the processed material to form a characteristic structure. The etching device includes an endpoint detector, which detects the light intensity of the light at a specific wavelength generated when the processed material is etched to generate an endpoint detection signal, and the processed material 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 endpoint 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.

[0006] The present invention also provides an etching method of an etching system, which is used to perform etching on a processed material to form a characteristic structure. The etching method of the etching system includes the following steps. Detecting the light intensity of light at a specific wavelength generated when the processed material is etched to generate an endpoint detection signal, wherein the processed material includes a material layer and at least one mask layer formed on the material layer. Determining the etching completion time of the mask layer based on the endpoint detection signal. Calculating the thickness of the mask layer based on the etching completion time. Adjusting the etching time of the material layer based on the thickness of the mask layer.

[0007] Based on the above, the embodiment of the present invention determines the etching completion time of the mask layer according to the endpoint 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 accurately known by calculating the etching completion time of the mask layer, and then the progress of the material layer etching process can be accurately grasped, effectively improving the accuracy of the semiconductor process.

[0008] In order to make the above features and advantages of the present invention more clearly understood, embodiments are given below with reference to the accompanying drawings for detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a schematic diagram of an etching system according to an embodiment of the present invention;

[0010] Figure 2 is a schematic diagram of a processed material according to an embodiment of the present invention;

[0011] Figure 3 is a schematic diagram of a processed material according to another embodiment of the present invention;

[0012] Figure 4A to Figure 4C is a schematic diagram of a curve showing the relationship between the etching time and the corresponding etching thickness of the mask layer;

[0013] Figure 5 is a schematic diagram of a curve showing the relationship between compensation time and thickness difference of an etching material layer according to an embodiment of the present invention;

[0014] Figure 6 is a flow chart of an etching method of an etching system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0015] The term "coupled" used in this specification (including claims) may refer to any direct or indirect connection method. For example, "a first device is coupled to a second device" may be interpreted as "the first device is directly connected to the second device" or "the first device is indirectly connected to the second device through other devices or connection methods". In addition, in any appropriate place in the drawings and embodiments, elements / devices / steps with the same reference numerals represent the same or similar parts. Elements / devices / steps with the same reference numerals or names in different embodiments may be cross-referenced.

[0016] The following provides a plurality of embodiments to describe the present disclosure in detail, but the present disclosure is not limited to the provided embodiments, and the provided embodiments can be appropriately combined. In the following embodiments, the same or similar element symbols represent the same or similar components or signals.

[0017] Figure 1 is a schematic diagram of an etching system according to an embodiment of the present invention, please refer to Figure 1 The etching system 100 includes an etching device 102 and a control device 104, wherein the etching device 102 is coupled to the control device 104. The etching device 102 is used to perform etching on a material to be processed 108 to form a feature structure on the material to be processed 108. Figure 2 As shown, 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 may be patterned, for example, by 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 etch the mask layer 204 and the material layer 206 to form a characteristic structure. In some embodiments, the material layer 206 may be an element semiconductor substrate (such as a silicon substrate or a germanium substrate) or a compound semiconductor substrate (such as a silicon carbide substrate or a gallium arsenide substrate). In some embodiments, the mask layer 204 may be formed of a dielectric material, and the dielectric material includes silicon oxide (SiO), silicon nitride (SiN), and silicon oxynitride (SiON).

[0018] In this embodiment, the etching device 102 may be, for example, a plasma etching device, but is not limited thereto. Specifically, the etching device 102 may include an etching chamber R1, an etching gas generator N1, and an endpoint detector 106. The etching chamber R1 may contain a material to be processed 108, such as Figure 1As shown, the material to be processed 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 light intensity of the light generated at a specific wavelength when the material to be processed 108 is etched and generate an endpoint detection signal. For example, in the present 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 different material layers, the endpoint detection signal generated by the endpoint detector 106 will also have a corresponding change in signal intensity, which can indicate whether the etching endpoint has been reached.

[0019] The control device 104 may be, for example, a computer or other electronic device with computing capabilities, but is not limited thereto. The control device 104 may determine the etching completion time of the mask layer 204 according to the endpoint detection signal. Figure 2 As shown on the right side of , the time required for the mask layer 204 to be etched to reach the end point (material layer 206) is shown. 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 infer the thickness of the mask layer 204, wherein the etching speed of the mask layer 204 can be obtained by collecting data through conventional experiments, for example. Since the change in the thickness of the mask layer 204 will also change the aspect ratio of the feature structure formed on the processed material 108, and different aspect ratios require different etching times to etch the same depth in the material layer 206, the thickness change of the mask layer 204 can correspond to different etching times of the material layer 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 change of the mask layer 204 due to the process or other factors, thereby causing insufficient or excessive etching depth of the material layer 206. 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 to obtain the information of the etching depth by analyzing the reflected light, but can directly detect the light emitted by the plasma during the plasma etching process and calculate the thickness of the mask layer 204 according to the etching time, it is possible to accurately obtain the thickness (etching depth) information of the mask layer 204 without increasing the measurement cost or interrupting the etching process to measure the etching depth, thereby achieving the effect of accurate etching of the material layer 206.

[0020] Furthermore, the control device 104 may calculate the thickness difference according to the thickness of the mask layer 204, for example, by subtracting the preset thickness (for example, the standard thickness) of the mask layer 204 from the calculated thickness of the mask layer 204 to obtain the thickness difference (i.e., the thickness change value of the mask layer 204), and adjust the etching time of the material layer 206 according to the thickness difference, for example, by 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 for etching the material layer 206 can be obtained, for example, by collecting data through conventional experiments.

[0021] In some embodiments, the processed material 108 may also include multiple mask layers, not limited to Figure 2 The embodiment includes only one mask layer. Figure 3 As shown, 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 (e.g., a silicon substrate or a germanium substrate) or a compound semiconductor substrate (e.g., a silicon carbide substrate or a gallium arsenide substrate). In some embodiments, the mask layers 304, 306, 308 may be formed of a dielectric material, and the dielectric material includes silicon oxide (SiO), silicon nitride (SiN), and silicon oxynitride (SiON). Similarly, the endpoint detector 106 may detect the spectrum emitted by the plasma during the plasma etching process to generate an endpoint detection signal. For example, the endpoint detector 106 may detect the light intensity 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 endpoint detection signals corresponding to the mask layers 304, 306, and 308, and calculate the total thickness of the mask layers 304, 306, and 308 according to the etching completion time of the mask layers 304, 306, and 308 and the etching speed of the mask layers 304, 306, and 308. The total thickness H of the mask layers 304, 306, and 308 can be expressed as follows, for example:

[0022] H=RA×TA+RB×TB+RC×TC (1)

[0023] RA, RB, RB are the etching speeds of the mask layers 304, 306, and 308, respectively, and TA, TB, 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 may also be stored in the storage circuit of the control device 104. After the control device 104 obtains the etching completion time of the mask layers 304, 306, and 308 according to the endpoint detection signal, the control device 104 may obtain the thickness of the mask layers 304, 306, and 308 corresponding to the etching completion time of the mask layers 304, 306, and 308 by looking up a table. For example, Figure 4A to Figure 4C is a schematic diagram of a curve showing the relationship between the etching time and the corresponding etching thickness of the mask layers 304, 306 and 308. Figure 4A to Figure 4C As shown, the curves corresponding to different mask layers have different slopes (etching speeds), and 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 total thickness H of the mask layers 304, 306, and 308.

[0024] Similarly, the control device 104 may subtract the sum of the preset thicknesses of the mask layers 304, 306, and 308 from the sum of the thicknesses H of the mask layers 304, 306, and 308 to obtain a thickness difference HD (i.e., a total thickness change of the mask layers 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 may store the etching compensation time of the material layer 310 corresponding to the thickness difference, so that the control device 104 may obtain the etching compensation time of the material layer 310 corresponding to the thickness difference by looking up a table. For example, Figure 5 FIG. 2 is a schematic diagram of a curve showing the relationship between the compensation time and the thickness difference of the etching material layer 310 according to an embodiment of the present invention. Figure 5 As shown, each thickness difference can be corresponded to a compensation time, for example Figure 4A to Figure 4C The thickness difference HD of the embodiment may correspond to the compensation time TD, and the control device 104 may add the compensation time TD to the etching time of the material layer 310 to ensure that the material layer 310 can be accurately etched to the expected depth. It is worth noting that the thickness difference HD may be a positive value or a negative value, and the corresponding compensation time TD may also be a positive value or a negative value, that is, the control device 104 may increase or decrease the etching time of the material layer 310 to achieve accurate etching of the material layer 310.

[0025] Figure 6is a flow chart of an etching method of an etching system according to an embodiment of the present invention. It can be seen from the above embodiments that the etching method of the etching system may include the following steps. First, the light intensity of the light generated at a specific wavelength when the processed material is etched is detected to generate an endpoint detection signal (step S602), wherein the processed material includes a material layer and at least one mask layer formed on the material layer. The etching process may be, for example, a plasma etching process, but is not limited thereto. The etching system may include an etching chamber for accommodating the processed material, and plasma is generated by generating an etching gas to the etching chamber to perform an etching process on the processed material. Next, the etching completion time of the mask layer is determined according to the endpoint 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 may be calculated according to the thickness of the mask layer, and the etching time of the material layer is adjusted according to the thickness difference, wherein the thickness difference may be the difference between the thickness of the mask layer and the preset thickness (e.g., the standard thickness of the mask layer).

[0026] In an embodiment with multiple mask layers, the etching completion time of each mask layer can be determined according to the endpoint 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 is adjusted according to the sum of the thicknesses of the multiple mask layers. For example, the sum of the preset thicknesses of the multiple mask layers can be subtracted from the sum of the thicknesses of the multiple mask layers to obtain the thickness difference, and the etching time of the material layer is adjusted according to the thickness difference.

[0027] In summary, the present embodiment determines the completion time of etching of the mask layer based on the endpoint detection signal, calculates the thickness of the mask layer based on the etching completion time, and adjusts the etching time of the material layer based on the thickness of the mask layer. In this way, the thickness of the mask layer can be accurately known by calculating the completion time of etching of the mask layer, and the progress of the etching process of the material layer can be accurately grasped, thereby effectively improving the accuracy of the semiconductor process. In addition, since the etching system of the present embodiment does not need to install a light source in the etching chamber as in the prior art, and obtains the information of the etching depth by analyzing the reflected light, it is not necessary to increase the measurement cost, nor to interrupt the etching process to measure the etching depth, and the thickness (etching depth) information of the mask layer can be accurately obtained, thereby achieving the effect of accurate etching of the material layer.

[0028] Although the present invention has been disclosed as above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the claims.

Claims

1. An etching system, characterized in that, it includes: an etching device for etching a material to be processed to form a characteristic structure, and the etching device includes: an endpoint detector for detecting the light intensity at a specific wavelength of the light generated during the etching of the material to be processed to generate an endpoint detection signal, and the material to be processed includes a material layer and at least one mask layer formed on the material layer; and a control device coupled to the etching device, determining the etching completion time of the mask layer according to the endpoint detection signal, 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.

2. The etching system according to claim 1, characterized in that, 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, where the thickness difference is equal to the thickness of the mask layer minus a preset thickness.

3. The etching system according to claim 1, characterized in that, the material to be processed includes multiple mask layers, and the control device determines the etching completion time of each mask layer according to the endpoint detection signal, calculates the thickness of each mask layer according to the etching completion time of each mask layer, and adjusts the etching time of the material layer according to the total thickness of the multiple mask layers.

4. The etching system according to claim 1, characterized in that, the control device multiplies the etching completion time of each mask layer by the corresponding etching rate to obtain the thickness of each mask layer.

5. The etching system according to claim 1, characterized in that, the etching device further includes: an etching chamber for accommodating the material to be processed; and an etching gas generator for generating etching gas to the etching chamber to generate plasma for etching the material to be processed.

6. An etching method of an etching system, characterized in that, the etching method of the etching system is used to etch a material to be processed to form a characteristic structure, and the etching method of the etching system includes: detecting the light intensity at a specific wavelength of the light generated during the etching of the material to be processed to generate an endpoint detection signal, where the material to be processed includes a material layer and at least one mask layer formed on the material layer; determining the etching completion time of the mask layer according to the endpoint detection signal; 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.

7. The etching method of the etching system according to claim 6, characterized in that, it includes: calculating the 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, where the thickness difference is equal to the thickness of the mask layer minus a preset thickness.

8. The etching method of the etching system according to claim 6, characterized in that, the material to be processed includes multiple mask layers, and the etching method of the etching system includes: determining the etching completion time of each mask layer according to the endpoint detection signal; Calculating the thickness of each mask layer based on the etching completion time of each mask layer; and Adjusting the etching time of the material layer according to the total thickness of the plurality of mask layers.

9. The etching method of the etching system according to claim 6, characterized in that it includes multiplying the etching completion time of each mask layer by the corresponding etching rate to obtain the thickness of each mask layer.

10. The etching method of the etching system according to claim 6, characterized in that the material layer is an elemental semiconductor substrate or a compound semiconductor substrate.

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