Patent Application
20220246410
The disclosure relates to a semiconductor device, and particularly relates to an etching apparatus and an etching method thereof.
Through the development of semiconductor manufacturing processes in recent years, the demands for integration level and performance of devices have become much higher, and plasma technologies play an essential role in the field of semiconductor manufacture. The plasma technology, which forms plasma by exciting a processing gas, is applied in various semiconductor manufacturing processes, such as the deposition process (e.g., chemical vapor deposition), the etching process (e.g., dry etching), etc. As semiconductor devices are being scaled down and circuit complexity thereof is increasing, a mask film has become more and more complicated, and the aspect ratio of a feature structure formed through etching correspondingly increases. Thus, the requirement for the precision of a plasma process has become much stricter.
In the conventional art, it is common to dispose a light source in an etching chamber to emit a light beam onto an etched substrate. By analyzing the spectrum of reflected light from the etched material, the information about etching depth is obtained, so as to determine whether a target etching end point is reached. Nevertheless, as the aspect ratio of the feature structure on the etched substrate increases, it becomes more difficult for the reflected light to form a complete interference fringe. As a result, an error may easily occur in determining the etching end point, which as a consequence influences the precision of the semiconductor manufacturing process.
Embodiments of the disclosure provide an etching apparatus and an etching method thereof capable of increasing the precision of a semiconductor manufacturing process.
An etching apparatus according to an embodiment of the disclosure includes an etching device and a control device. The etching device performs an etching process on a material to be processed to form a feature structure. The etching device includes an end point detector, detecting a light intensity at a specific wavelength for light generated when the etching process is performed on the material to be processed and generating 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 etching device also includes a control device, coupled to the etching device and determining an etching completion time of the mask layer according to the end point detection signal, calculating a thickness of the mask layer according to the etching completion time, and adjusting an etching time of the material layer according to the thickness of the mask layer.
Another embodiment of the disclosure provides an etching method of an etching apparatus for performing an etching process on a material to be processed to form a feature structure. The etching method includes steps as follows. A light intensity at a specific wavelength is detected for light generated when the etching process is performed on the material to be processed, and an end point detection signal is generated. The material to be processed includes a material layer and at least one mask layer formed on the material layer; An etching completion time of the mask layer is determined according to the end point detection signal. A thickness of the mask layer is calculated according to the etching completion time. An etching time of the material layer is adjusted according to the thickness of the mask layer.
Based on the above, in the embodiments of the disclosure, 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, and the etching time of the material layer is adjusted according to the thickness of the mask layer. By calculating the thickness of the mask layer according to the etching completion time of the mask layer, the thickness of the mask layer can be precisely determined. Consequently, the progress of the etching process on the material layer can be precisely determined. Thus, the precision of the semiconductor manufacturing process can be effectively facilitated.
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.
Reference will now be made in detail to the present preferred embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
In the embodiment, the etching device 102 may be, for example, a plasma etching device. However, the disclosure is not limited thereto. More specifically, the etching device 102 may include an etching chamber R1, an etching gas generator N1, and an end detector 106.
The etching chamber R1 may accommodate the material 108 to be processed. As shown in
The control device 104 may be a computer or other electronic devices with computing capabilities. However, the disclosure is not limited thereto. The control device 104 may determine the etching completion time of the mask layer 204, i.e., the time required for the mask layer 204 to be etched to the end point (material layer 206), as shown on the right side of
More specifically, the control device 104 may calculate a thickness difference according to the thickness of the mask layer 204, such as subtracting the default thickness (e.g., 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, such as adding or reducing a compensation time to or from the etching time, according to the thickness difference, so as to ensure the material layer 206 to be etched to a predetermined depth. The relationship between the thickness difference and the compensation time for etching the material layer 206 may be obtained by, for example, collecting data through regular experimentation.
In some embodiments, the material 108 to be processed may include a plurality of mask layers, instead of including only one mask layer like the embodiment shown in
Examples of the dielectric material include SiO, SiN, SiON, etc. Similarly, the end point detector 106 may detect the spectrum of light emitted by the plasma during the plasma etching process to generate the end point detection signal. For example, the end point detector 106 may detect the light intensities at different specific wavelengths respectively corresponding to different mask layers, so as to generate corresponding end point detection signals. The control device 104 may determine the etching completion times 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 calculate the sum of the thicknesses of the mask layers 304, 306, and 308 according to the etching completion times of the mask layers 304, 306, and 308 and the etching rates of the mask layers 304, 306, and 308, respectively. A thickness sum H of the mask layers 304, 306, and 308 may be calculated according to the following equation:
H=RA×TA+RBxTB+RC×TC ... (1),
wherein RA, RB, and RC respectively represent the etching rates of the mask layers 304, 306, and 308, and TA, TB, and TC respectively represent the etching completion times of the mask layers 304, 306, and 308. In some embodiments, the relationships between the etching times of the mask layers 304, 306, and 308 and the corresponding etched thicknesses may also be stored in a storage circuit of the control device 104. After obtaining the etching completion times of the mask layers 304, 306, and 308 according to the end point detection signals, the control device 104 may 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 looking up a table.
Similarly, the control device 104 may subtract a sum of default thicknesses of the mask layers 304, 306, and 308 from the thickness sum H of the mask layers 304, 306, and 308 to obtain a thickness difference HD (i.e., a total thickness change value 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. Accordingly, 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,
In an embodiment having multiple mask layers, the etching completion time of each mask layer may be determined according to the end point detection signal corresponding to each mask layer, and the thickness of each mask layer may 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 mask layers. For example, the thickness difference may be obtained by subtracting the sum of the default thicknesses of the mask layers from the sum of the thicknesses of the mask layers, and the etching time of the material layer may be adjusted according to the thickness difference.
In view of the foregoing, in the embodiments of the disclosure, 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, and the etching time of the material layer is adjusted according to the thickness of the mask layer. By calculating the thickness of the mask layer according to the etching completion time of the mask layer, the thickness of the mask layer can be precisely determined. Consequently, the progress of the etching process on the material layer can be precisely determined. Thus, the precision of the semiconductor manufacturing process can be effectively facilitated. Besides, unlike the conventional art which requires an additional light source in the etching chamber so as to obtain the information of the etching depth by analyzing reflected light, the etching apparatus according to the embodiments of the disclosure is capable of accurately obtaining the thickness (etching depth) information of the mask layer, thereby precisely etching the material layer, without increasing the measurement cost or interrupting the etching process to measure the etching depth.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
