Preparation method of SiOCN film and semiconductor process equipment

Abstract

The invention relates to the technical field of SiOCN thin film preparation, in particular to a preparation method of a SiOCN thin film and semiconductor process equipment. The preparation method of the SiOCN thin film comprises the steps that the process temperature is adjusted to a target temperature value, and the process pressure is adjusted to a target pressure value; introducing a process gas into the process chamber, and carrying out deposition to obtain a SiOCN thin film; wherein the process gas comprises O2, and the volume ratio of O2 is 17%-29%. According to the preparation method of the SiOCN film provided by the invention, the oxygen content in the SiOCN film can be improved, so that the SiOCN film with a relatively low dielectric constant can be obtained; in addition, the uniformity of the obtained SiOCN film can be kept within 2%, and the step coverage rate can reach 98% or above.

Description

Technical Field

[0001] The present invention relates to the technical field of SiOCN film preparation, and in particular to a method for preparing a SiOCN film and semiconductor process equipment. Background Art

[0002] As chip feature sizes continue to shrink, the parasitic capacitance between the gate and drain electrodes is likely to increase. Excessive parasitic capacitance can negatively impact semiconductor devices and circuits in many ways, such as reducing circuit speed, increasing power consumption, affecting signal integrity, increasing interconnect latency, and impacting memory performance. To mitigate these negative impacts, low-k dielectric materials, such as SiOCN films, have been employed in related technologies to replace traditional SiN and SiO2 films to reduce the parasitic capacitance of semiconductor devices.

[0003] However, the K value (dielectric constant) of SiOCN films produced by related processes is generally greater than 4.7, which cannot meet the needs of further chip size reduction. Therefore, a solution to reduce the K value through process optimization is urgently needed. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing a SiOCN film and a semiconductor process equipment to alleviate the technical problem of a high dielectric constant of the SiOCN film prepared by the related art.

[0005] The present invention provides a method for preparing a SiOCN thin film, the method comprising:

[0006] Adjust the process temperature to the target temperature value, and adjust the process pressure to the target pressure value;

[0007] A process gas is introduced into the process chamber for deposition to obtain a SiOCN film; wherein the process gas includes O2, and the volume proportion of O2 is 17% to 29%.

[0008] Preferably, as an implementable embodiment, the target temperature value ranges from 620 to 650°C.

[0009] Preferably, as an implementable embodiment, the target pressure value ranges from 5000 to 6000 mTorr.

[0010] Preferably, as an implementation method, the introducing process gas into the process chamber includes: introducing Si2Cl6, C3H6, O2 and NH3 into the process chamber in sequence.

[0011] Preferably, as an implementation method, the process gas introduced into the process chamber has a flow rate of Si2Cl6 of 120-140 sccm, a flow rate of C3H6 of 4400-4600 sccm, a flow rate of O2 of 4000-6000 sccm, and a flow rate of NH3 of 4200-4400 sccm.

[0012] Preferably, as an implementation method, the process gas introduced into the process chamber has the following characteristics: the introduction time of Si2Cl6 is 9 to 11 seconds, the introduction time of C3H6 is 78 to 82 seconds, the introduction time of O2 is 10 to 15 seconds, and the introduction time of NH3 is 14 to 16 seconds.

[0013] Preferably, as an implementable method, the method further includes:

[0014] The deposited SiOCN film is post-processed.

[0015] Preferably, as an implementation method, the post-processing of the deposited SiOCN film includes:

[0016] The deposited SiOCN film is annealed in an inert gas environment.

[0017] Preferably, as an implementation method, the inert gas includes N2 or Ar.

[0018] The semiconductor process equipment provided by the present invention includes a process chamber, an air intake component, an exhaust component, a heating component and a controller, characterized in that the controller includes at least one processor and at least one memory, the memory storing a computer program, and when the computer program is executed by the processor, the method for preparing the SiOCN film as described above is implemented.

[0019] Compared with the related art, the present invention has the following beneficial effects:

[0020] The SiOCN film preparation method and semiconductor process equipment provided by the present invention increase the volume fraction of O2 in the process gas introduced into the process chamber, thereby increasing the oxygen incorporation amount, thereby changing the atomic ratio of Si, O, C, and N in the SiOCN film and improving the oxygen content in the SiOCN film, thereby obtaining a SiOCN film with a lower dielectric constant. Furthermore, when deposited in a chamber process environment with an appropriate target process temperature and target process pressure, the uniformity of the resulting SiOCN film can be maintained within 2%, and the step coverage can reach over 98%, thereby effectively meeting the requirements of advanced processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the following briefly introduces the drawings required for use in the embodiments or related technical descriptions. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0022] Figure 1 A schematic flow chart of a method for preparing a SiOCN thin film according to an embodiment of the present invention;

[0023] Figure 2 A graph showing the dielectric constant of a SiOCN film according to an embodiment of the present invention as a function of oxygen content;

[0024] Figure 3 A schematic diagram of a process flow of a method for preparing a SiOCN thin film according to an embodiment of the present invention;

[0025] Figure 4 A schematic structural diagram of semiconductor process equipment provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0026] In a related technique, SiOCN films are doped with elements such as fluorine (F) and boron (B) to reduce their polarizability, thereby lowering their K value. However, doping uniformity is difficult to control in a vertical furnace, resulting in uneven element distribution within the SiOCN film, affecting its performance consistency. Furthermore, the doping elements may volatilize or migrate at high temperatures, causing degradation of the SiOCN film's performance. Furthermore, the doping process can introduce new contamination sources, impacting other processes.

[0027] Another related technique involves introducing air gaps within the SiOCN film, leveraging the low dielectric constant of air to reduce the overall K value of the SiOCN film. However, creating air gaps requires additional etching and filling steps, resulting in a complex and costly process. Furthermore, air gaps can weaken the mechanical strength of the SiOCN film, impacting device reliability. Furthermore, the thermal conductivity of air is lower than that of the SiOCN film, potentially leading to localized overheating.

[0028] The process parameters (such as temperature, pressure, precursor ratio, etc.) of a vertical furnace atomic layer deposition (ALD) device have a significant impact on film performance, but the related art lacks a systematic adjustment strategy. Based on this, the present invention provides a method for adjusting the dielectric constant (K value) of SiOCN films through process optimization. By adjusting the process parameters (including temperature, pressure, precursor gas ratio and flow rate, etc.) of a vertical furnace atomic layer deposition (ALD) device, the atomic ratio of Si, C, N, and O in the SiOCN film can be precisely controlled, thereby obtaining a SiOCN film with a lower dielectric constant (K value).

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0030] The present invention will be further described in detail below through specific implementation examples in conjunction with the accompanying drawings.

[0031] Figure 1 FIG. 5 is a schematic flow chart of a method for preparing a SiOCN thin film in one embodiment of the present invention, the method comprising:

[0032] S102, adjusting the process temperature to the target temperature value, and adjusting the process pressure to the target pressure value;

[0033] S104 , introducing process gas into the process chamber for deposition to obtain a SiOCN thin film; wherein the process gas includes O 2 , and the volume proportion of O 2 is 17% to 29%.

[0034] Specifically, on the basis of keeping the flow rate and duration of other gases introduced into the process chamber unchanged, the volume proportion of O2 in the process gas can be adjusted by adjusting the introduction duration and flow rate of O2.

[0035] In the related art, the volume proportion of O2 in the process gas introduced into the process chamber is low. The present invention increases the volume proportion of O2 in the process gas introduced into the process chamber, and can increase the amount of oxygen doped to change the atomic ratio of Si, O, C, and N in the SiOCN film, thereby increasing the oxygen content in the SiOCN film. Figure 2 As shown in the figure, the horizontal axis represents the oxygen content in the SiOCN film, which is expressed in percentage; the vertical axis represents the K value of the SiOCN film. It can be seen from the curve in the figure that the K value of the SiOCN film gradually decreases with the increase of the oxygen content. Therefore, when the oxygen content in the SiOCN film is increased, a SiOCN film with a lower dielectric constant can be obtained.

[0036] In addition, by carrying out deposition in a chamber process environment with a suitable target process temperature and target process pressure, the uniformity of the resulting SiOCN film can be maintained within 2%, and the step coverage can reach more than 98%, thereby meeting the requirements of advanced processes as much as possible.

[0037] The method for preparing the SiOCN thin film provided in this embodiment has wide process compatibility, is applicable to vertical furnace ALD equipment, does not require hardware modification, and has significant cost-effectiveness.

[0038] In the above step S104 , the volume proportion of O 2 in the process gas is preferably 19% to 27%, more preferably 21% to 25%, and even more preferably 23%.

[0039] In related technologies, the process temperature (deposition temperature) is usually set at around 580°C. At this process temperature, the oxygen incorporation efficiency is low. The present invention sets the target temperature range to 620-650°C, which is equivalent to raising the process temperature. At this higher process temperature, the reactivity of the oxygen-containing gas is higher, which can help increase the oxygen incorporation amount, further improve the oxygen content in the SiOCN film, and obtain a SiOCN film with a lower dielectric constant. In addition, the increased process temperature can increase the precursor mobility and reaction rate, thereby improving the density of the SiOCN film, for example, reducing the porosity to less than 5%.

[0040] In related art, the process pressure (the pressure within the process chamber) is typically set at around 3500mTorr. At this process pressure, the oxygen incorporation level is relatively low. The present invention sets the target pressure range to 5000-6000mTorr, which is equivalent to raising the process pressure. At this higher process pressure, the partial pressure of the oxygen-containing gas is higher, thereby increasing the oxygen incorporation level, further improving the oxygen content in the SiOCN film and achieving a SiOCN film with a lower dielectric constant.

[0041] See also Figure 3 The above step S104 may specifically include: introducing Si2Cl6, C3H6, O2 and NH3 into the process chamber in sequence, and the deposition principle is as follows:

[0042] Si+NH3→Si-NH2(Pretreatment)

[0043] Si-NH2+Si2Cl6→Si-N-SiCl2

[0044] Si-N-SiCl2+C3H6→Si-N-Si-CH+HCl

[0045] Si-N-Si-CH+O2→SiNCX OH

[0046] SiNC X O Y +NH3→SiNC X O Y -N+byproduct

[0047] From the above reaction principle, it can be seen that SiOCN film can be obtained by sequentially introducing Si2Cl6, C3H6, O2 and NH3 into the process chamber.

[0048] In step S104, the flow rate of Si2Cl6 introduced into the process chamber is set to 120-140 sccm, preferably 125-135 sccm, and more preferably 130 sccm; the flow rate of C3H6 introduced into the process chamber is set to 4400-4600 sccm, preferably 4450-4550 sccm, and more preferably 4500 sccm; the flow rate of O2 introduced into the process chamber is set to 4000-6000 sccm, optionally 4500-5500 sccm, and more preferably 5000 sccm; and the flow rate of NH3 introduced into the process chamber is set to 4200-4400 sccm, preferably 4250-4350 sccm, and more preferably 4300 sccm. It should be noted that setting the flow rates of the process gases introduced into the process chamber within the above-mentioned corresponding ranges is conducive to ensuring the uniformity of the produced SiOCN film.

[0049] In the above step S104, the time length for introducing Si2Cl6 can be set to 9 to 11 s, preferably 9.5 to 10.5 s, and more preferably 9 s; the time length for introducing C3H6 can be set to 78 to 82 s, preferably 79 to 81 s, and more preferably 80 s; the time length for introducing O2 can be set to 10 to 15 s, preferably 12 to 14 s, and more preferably 13 s; the time length for introducing NH3 can be set to 14 to 16 s, preferably 14.5 to 15.5 s, and more preferably 15 s. In the related art, the time for introducing O2 is generally about 7 seconds. The present invention extends the time for introducing O2 to 10-15 seconds, thereby increasing the volume proportion of O2 in the process gas introduced into the process chamber, and increasing the amount of oxygen incorporated to obtain a SiOCN film with a lower dielectric constant; in addition, setting the time for introducing each process gas into the process chamber within the above-mentioned corresponding range is also beneficial to ensuring the uniformity of the obtained SiOCN film.

[0050] The method for preparing the SiOCN film provided in this embodiment further includes: performing post-processing on the deposited SiOCN film to further increase the oxygen content in the SiOCN film and reduce the K value of the SiOCN film.

[0051] Preferably, the deposited SiOCN film is annealed in an inert gas environment to reduce the K value of the SiOCN film.

[0052] Specifically, N2 or Ar can be selected as the above-mentioned inert gas, which can not only ensure annealing stability but also reduce costs.

[0053] In practical applications, the method for preparing the SiOCN thin film provided in this embodiment can be used to perform multi-layer cyclic deposition.

[0054] In order to further illustrate the technical solution of the present invention, the preparation method of the SiOCN thin film provided by the present invention is described in more detail below with reference to specific embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0055] Comparative Example

[0056] Adjust the process temperature to 580°C and the process pressure to 3500 mtorr;

[0057] Si2Cl6, C3H6, O2 and NH3 are introduced into the process chamber in sequence for deposition to obtain a SiOCN film; wherein, the flow rate of Si2Cl6 is 130sccm, the flow time is 14s, the flow rate of C3H6 is 4500sccm, the flow time is 80s, the flow rate of O2 is 4000sccm, the flow time is 7s, and the flow rate of NH3 is 4300sccm, and the flow time is 15s.

[0058] The SiOCN film prepared in the comparative example was measured, and the results showed that the K value of the SiOCN film was 5.2.

[0059] Example 1

[0060] Adjust the process temperature to 580°C and the process pressure to 3500 mtorr;

[0061] Si2Cl6, C3H6, O2 and NH3 are introduced into the process chamber in sequence for deposition to obtain a SiOCN film; wherein, the flow rate of Si2Cl6 is 130sccm, the flow time is 14s, the flow rate of C3H6 is 4500sccm, the flow time is 80s, the flow rate of O2 is 4000sccm, the flow time is 14s, and the flow rate of NH3 is 4300sccm, and the flow time is 15s.

[0062] Measurements of the SiOCN film produced in Example 1 showed that the oxygen content in the SiOCN film increased, and the K value decreased from 5.2 to 4.3. At the same time, the uniformity of the SiOCN film was maintained within 2%, and the step coverage reached over 98%, meeting the requirements of advanced processes.

[0063] Example 2

[0064] Adjust the process chamber temperature to 620°C and the process pressure to 3500 mtorr;

[0065] Si2Cl6, C3H6, O2 and NH3 are introduced into the process chamber in sequence for deposition to obtain a SiOCN film; wherein, the flow rate of Si2Cl6 is 130sccm, the flow time is 14s, the flow rate of C3H6 is 4500sccm, the flow time is 80s, the flow rate of O2 is 5000sccm, the flow time is 10s, and the flow rate of NH3 is 4300sccm, and the flow time is 15s.

[0066] Measurements of the SiOCN film produced in Example 2 show that the oxygen content in the SiOCN film increased, reducing the K value from 5.2 to 4.1. Simultaneously, the uniformity of the SiOCN film remained within 2%, and the step coverage reached over 98%, meeting the requirements of advanced processes. Furthermore, the increased process temperature increases the precursor mobility and reaction rate, reducing film defects and improving film density (porosity <5%).

[0067] Example 3

[0068] Adjust the process chamber temperature to 580°C and the process pressure to 5500 mtorr;

[0069] Si2Cl6, C3H6, O2 and NH3 are introduced into the process chamber in sequence for deposition to obtain a SiOCN film; wherein, the flow rate of Si2Cl6 is 130sccm, the flow time is 14s, the flow rate of C3H6 is 4500sccm, the flow time is 80s, the flow rate of O2 is 4000sccm, the flow time is 10s, and the flow rate of NH3 is 4300sccm, and the flow time is 15s.

[0070] Measurements of the SiOCN film produced in Example 3 showed that the oxygen content in the SiOCN film increased, and the K value decreased from 5.2 to 3.9. At the same time, the uniformity of the SiOCN film was maintained within 2%, and the step coverage reached over 98%, meeting the requirements of advanced processes.

[0071] The above embodiments show that by using the preparation method of the SiOCN film provided by the present invention for deposition, the oxygen content in the obtained SiOCN film will increase, and the K value of the SiOCN film will decrease to below 4.3 as the oxygen content increases; at the same time, the uniformity of the SiOCN film can still be maintained within 2%, and the step coverage reaches more than 98%, meeting the requirements of advanced processes.

[0072] In fact, by using the method for preparing a SiOCN film provided by the present invention to deposit the SiOCN film, the K value of the obtained SiOCN film can be as low as 3.5.

[0073] Figure 4 The present invention also provides a semiconductor process equipment, which includes a process chamber 210, an air inlet component 220, an exhaust component 230, a heating component 240 and a controller ( Figure 4 (not shown). The controller includes at least one processor and at least one memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method of any one of the above embodiments is implemented.

[0074] For example, the controller can be either a host computer or a slave computer. Specifically, the controller can control the opening of the valve of the gas inlet assembly 220 to introduce the corresponding process gas into the process chamber 210. The controller can also control the opening and closing of the valve of the gas inlet assembly 220 to control the flow rate of the process gas. The controller can also control the exhaust assembly 230 to exhaust the interior of the process chamber 210 to control the process pressure within the process chamber 210 and discharge reaction byproducts. The controller can also control the heating assembly 240 to control the process temperature within the process chamber 210.

[0075] The semiconductor process equipment 200 of the embodiment of the present invention may be a vertical furnace atomic layer deposition (ALD) equipment. The embodiment of the present invention does not limit the type of the semiconductor process equipment 200.

[0076] The semiconductor process equipment provided in the embodiment of the present invention has the same technical features as the method for preparing the SiOCN thin film provided in the above embodiment, and therefore can also solve the same technical problems and achieve the same technical effects.

[0077] This embodiment further provides a machine-readable storage medium storing machine-executable instructions. When the machine-executable instructions are called and executed by a processor, the machine-executable instructions prompt the processor to implement the above-mentioned method for preparing the SiOCN thin film.

[0078] Those skilled in the art will clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described equipment and devices can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0079] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a non-volatile computer-readable storage medium that is executable by a processor. Based on this understanding, the technical solution of the present invention, or the part that contributes to the relevant technology, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0080] Finally, it should be noted that in this document, terms such as "comprise" or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a SiOCN thin film, characterized in that: The method comprises: Adjust the process temperature to the target temperature value, and adjust the process pressure to the target pressure value; A process gas is introduced into the process chamber for deposition to obtain a SiOCN film; wherein the process gas includes O2, and the volume proportion of O2 is 17% to 29%.

2. The method for preparing a SiOCN thin film according to claim 1, wherein: The target temperature ranges from 620 to 650°C.

3. The method for preparing a SiOCN thin film according to claim 1, wherein: The target pressure value ranges from 5000 to 6000 mTorr.

4. The method for preparing a SiOCN thin film according to any one of claims 1 to 3, characterized in that: The introducing of process gas into the process chamber comprises: introducing Si2Cl6, C3H6, O2 and NH3 into the process chamber in sequence.

5. The method for preparing a SiOCN thin film according to claim 4, wherein: The process gases introduced into the process chamber have a flow rate of Si2Cl6 of 120-140 sccm, a flow rate of C3H6 of 4400-4600 sccm, a flow rate of O2 of 4000-6000 sccm, and a flow rate of NH3 of 4200-4400 sccm.

6. The method for preparing a SiOCN thin film according to claim 5, wherein: Among the process gases introduced into the process chamber, the introduction time of Si2Cl6 is 9 to 11 seconds, the introduction time of C3H6 is 78 to 82 seconds, the introduction time of O2 is 10 to 15 seconds, and the introduction time of NH3 is 14 to 16 seconds.

7. The method for preparing a SiOCN thin film according to any one of claims 1 to 3, characterized in that: The method further comprises: The deposited SiOCN film is post-processed.

8. The method for preparing a SiOCN thin film according to claim 7, wherein: The post-processing of the deposited SiOCN film comprises: The deposited SiOCN film is annealed in an inert gas environment.

9. The method for preparing a SiOCN thin film according to claim 8, wherein: The inert gas includes N2 or Ar.

10. A semiconductor process equipment, comprising a process chamber, an air inlet assembly, an air extraction assembly, a heating assembly and a controller, characterized in that: The controller includes at least one processor and at least one memory, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method for preparing the SiOCN thin film according to any one of claims 1 to 9 is implemented.

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