Method of deposition

Abstract

According to the present invention, a method for depositing a silicon carbonitride (SiCN:H) film on a substrate by plasma-enhanced chemical vapor deposition (PECVD) is provided, comprising the steps of: providing the substrate into a chamber; introducing a silane (SiH4), a carbon donor precursor, and a nitrogen gas (N2) into the chamber; and maintaining a plasma in the chamber to deposit SiCN:H on the substrate by PECVD, wherein the substrate is maintained at a temperature of about 250°C or less.

Description

Technology Field

[0001] The present invention relates to a method for depositing a silicon carbonitride film by plasma-enhanced chemical vapor deposition (PECVD). In particular, the present invention relates to a method for depositing a silicon carbonitride (SiCN:H) film by PECVD. The present invention also relates to a substrate having an associated SiCN:H film. The present invention also relates to methods for bonding two substrates and an associated device comprising two bonded substrates. Background Technology

[0002] Two-dimensional (2D) scaling of electronic devices based on Moore's Law will continue in the near future. However, three-dimensional (3D) integration of devices, whether homogeneous or heterogeneous, offers great potential for the development of advanced systems. It is believed that stacking devices in 3D will enable greater integration, which will consequently provide improved device performance, enhanced functionality, and ultimate cost reduction compared to the 2D scaling approach.

[0003] To achieve efficient 3D integration of devices, it is desirable to bond two substrates, such as device wafers, together so that a large number of dies can be stacked simultaneously. Surface activated bonding techniques are promising candidates for achieving proper 3D stacking of devices. Typically, a surface activated bonding process involves treating the surfaces of two substrates with a dielectric bonding / adhesion layer, such as a silicon carbon nitride (SiCN) layer (containing a silicon carbon nitride (SiCN:H) layer). The two treated surfaces can then be smoothed by chemical mechanical planarization (CMP), precisely aligned, compressed together at an elevated temperature, and annealed to bond these substrates together.

[0004] Known surface-activated bonding techniques utilize dielectric bonding layers and adhesive layers, such as SiCN and SiCN:H, deposited at high temperatures (approx. 340–370 °C), and may require additional densification steps at approximately 420 °C prior to bonding. Because high temperatures are required, these known processes are not suitable for bonding substrates with low thermal budget constraints (i.e., temperature-sensitive substrates). For example, for substrates containing device layers and / or interconnects that may include copper layers embedded in the dielectric, it is important to maintain a low thermal budget to prevent damage to the devices.

[0005] However, simply lowering the deposition temperature of bonding and adhesive layers results in poor bonding strength of the adhesive layers, poor properties of the copper barrier layer, and increased sensitivity to moisture. Therefore, simply lowering the temperature of known deposition processes leads to unacceptable results.

[0006] Therefore, there is a need for a method that can deposit dielectric barrier and adhesive layers for wafer-to-wafer bonding at significantly low temperatures while maintaining excellent device performance. This is desirable to enable bonding of a wider variety of substrates (especially those with low thermal budget constraints) using surface-activated bonding techniques. By providing such a method, enhanced 3D integration of devices can be achieved, which is expected to improve device performance. The problem to be solved

[0007] The present invention aims to address at least some of the problems, desires, and requirements described above in at least some embodiments. In particular, embodiments of the present invention aim to provide a method for depositing a silicon hydride carbonitride (SiCN:H) film capable of maintaining a low thermal budget for a substrate. SiCN:H films deposited by the methods of the present invention are suitable for use as adhesive layers in surface-activated bonding techniques while being maintained within low thermal budget constraints. These films also exhibit excellent copper barrier layer properties and remain stable in the presence of moisture. means of solving the problem

[0008] According to a first aspect of the present invention, a method for depositing a silicon hydride carbonitride (SiCN:H) film on a substrate by plasma-enhanced chemical vapor deposition (PECVD) is provided, wherein

[0009] A step of providing a substrate into a chamber;

[0010] A step of introducing silane (SiH4), a carbon-donating precursor, and nitrogen gas (N2) into a chamber; and

[0011] The method includes the step of maintaining a plasma in a chamber to deposit SiCN:H on a substrate by PECVD, wherein the substrate is maintained at a temperature of less than about 250°C.

[0012] It has been found that using a deposition recipe comprising a combination of silane (SiH4), a separate carbon donor precursor, and nitrogen gas (N2) as a reactive precursor can produce a stable SiCN:H film with excellent barrier and adhesion layer properties while maintained within low thermal budget constraints. The SiCN:H film is suitable for use as an adhesion layer in surface-activated bonding processes. Therefore, this method is suitable for 3D integration of various substrates, including device wafers, temperature-sensitive device layers and their interconnects that can be embedded within the substrate. The reactive precursors used can essentially consist of a combination of silane (SiH4), a separate carbon donor precursor, and nitrogen gas (N2). Preferably, the reactive precursors used can essentially consist of a combination of silane (SiH4), a separate carbon donor precursor, and nitrogen gas (N2). Optionally, one or more non-reactive carrier gases may also be introduced into the chamber.

[0013] The carbon donor precursor may be an organic silane, a gaseous hydrocarbon, or a combination thereof. Preferably, the carbon donor precursor is an organic silane. The organic silane may be an alkyl silane. The organic silane may be selected from methyl silane, dimethyl silane, trimethyl silane, tetramethyl silane, or a combination thereof. Preferably, the organic silane is trimethyl silane or tetramethyl silane. Most preferably, the organic silane is trimethyl silane. It has been found that using a deposition recipe comprising a combination of silane (SiH4), an organic silane, and nitrogen gas (N2) can produce SiCN:H films having particularly desirable properties, for example, as an excellent copper barrier layer. Optionally, the carbon donor precursor may be a gaseous hydrocarbon. The gaseous hydrocarbon may be methane (CH4) or acetylene (C2H2).

[0014] Silane (SiH4) is a silicon donor precursor. Silane (SiH4) can be introduced into the chamber at a flow rate in the range of 100-500 sccm, optionally in the range of 200-400 sccm, optionally in the range of 250-300 sccm, or optionally about 275 sccm.

[0015] The carbon donor precursor can be introduced into the chamber at a flow rate in the range of 10-90 sccm, optionally in the range of 20-70 sccm, or optionally in the range of 25-55 sccm.

[0016] The carbon donor precursor can be introduced into the chamber at a flow rate lower than that of the silane (SiH4). The carbon donor precursor may have a flow rate of about 2-50% of the silane (SiH4) flow rate, optionally about 5-25%, optionally about 7-20%, optionally about 8-15%, or optionally about 10-11%.

[0017] Carbon donor precursors such as silane (SiH4) and trimethylsilane can be introduced into the chamber at flow rates (in sccm units) in a range of 3:1 to 30:1, optionally 4:1 to 25:1, optionally 5:1 to 20:1, optionally about 7:1 to 15:1, optionally about 10:1 to 12:1, or optionally about 11:1. Introducing silane (SiH4) and carbon donor precursors into the chamber at these ratios can maintain high resistance to moisture absorption while improving the adhesion properties of the deposited SiCN:H film. Without being bound by any theory or speculation, the improved adhesion properties are thought to be a result of the increased carbon content in the deposited SiCN:H film. Just as an example, when the carbon-donating precursor is trimethylsilane, the ratio of silane (SiH4) to trimethylsilane is preferably about 10:1 to 12:1, or most preferably 11:1.

[0018] Nitrogen gas (N2) is a nitrogen donor precursor. Nitrogen gas (N2) can be introduced into the chamber at a flow rate in the range of 1,000–10,000 sccm, optionally in the range of 2,500–9,000 sccm, optionally in the range of 4,000–8,000 sccm, or optionally in the range of 6,000–7,000 sccm. Optionally, ammonia (NH3) is not present as a nitrogen donor precursor. Advantageously, N2 is the only nitrogen donor precursor used.

[0019] During the PECVD step, the substrate may be maintained at a temperature below 225 °C, optionally below 200 °C, or optionally about 175 °C or lower. The substrate may be maintained at a temperature above 100 °C, optionally above 125 °C, or optionally above 150 °C. Maintaining the substrate at these temperatures allows the substrate to be maintained within low thermal budget constraints, thereby enabling the present method to properly deposit SiCN:H films on temperature-sensitive substrates. For example, the method may be used to deposit SiCN:H (adhesive) layers on temperature-sensitive substrates comprising device layers and / or interconnects that may include copper layers embedded in the dielectric.

[0020] While the plasma is maintained within the chamber, the chamber may have a pressure in the range of 1,000-5,000 mTorr, optionally in the range of 1,400-3,000 mTorr, and optionally about 1,600 mTorr.

[0021] Plasma can be maintained using high-frequency RF power. Alternatively, plasma can be maintained using high-frequency RF power and low-frequency RF power.

[0022] The high-frequency RF power may have a frequency in the range of 10-15 MHz, preferably 13.56 MHz. The high-frequency RF power may have a power in the range of 250-1,250 W, optionally in the range of 500-1,000 W, optionally in the range of 700-900 W, or optionally about 800 W.

[0023] The low-frequency RF power may have a frequency in the range of 100-500 kHz, optionally in the range of about 200-450 kHz, optionally in the range of about 300-400 kHz, or optionally in the range of about 380 kHz. The low-frequency RF power may have a power in the range of 0-400 W, optionally in the range of 50-300 W, or optionally in the range of 100-200 W.

[0024] The method may further include a subsequent step of performing hydrogen plasma treatment, which involves exposing the SiCN:H film to hydrogen plasma. Hydrogen plasma treatment can further enhance the stability of the SiCN:H film. Without being bound by any theory or speculation, it is believed that hydrogen plasma treatment serves to passivate the surface of the SiCN:H film, thereby preventing surface absorption of moisture and the formation of SiO. Hydrogen plasma treatment can be performed continuously under vacuum conditions. Hydrogen plasma treatment can be performed without exposing the SiCN:H film to water vapor.

[0025] During hydrogen plasma treatment, the substrate may be maintained at a temperature of about 200°C or less, optionally about 175°C or less, optionally about 150°C or less, or optionally about 125°C.

[0026] The silicon carbonitride (SiCN:H) film can be an amorphous film (e.g., a-SiCN:H).

[0027] The substrate can be a semiconductor substrate.

[0028] According to a second aspect of the present invention, a substrate on which a SiCN:H film is deposited using the method according to a first aspect is provided.

[0029] The substrate may be a semiconductor substrate. The substrate may be a silicon substrate or a silicon wafer. The substrate may include a plurality of dies. The substrate may include features such as one or more device layers and / or interconnects. The features may be temperature-sensitive. The features may include copper layers, for example, copper layers embedded in a dielectric material.

[0030] SiCN:H films can have a refractive index in the range of about 2.0. SiCN:H films can have a refractive index of about 1.85-2.2, optionally 1.95-2.10, optionally 1.97-2.03, or optionally 1.99-2.00.

[0031] The SiCN:H film can have a SiC:SiN ratio (based on FTIR peak area) of about 0.01, optionally about 0.005, or optionally about 0.004.

[0032] The SiCN:H film has a SiCH of less than about 0.01, optionally about 0.008 (based on FTIR peak area). x It can have a :SiN ratio.

[0033] The SiCN:H film can have an NH:SiN ratio of about 0.02, optionally about 0.018 (based on FTIR peak area).

[0034] SiCN:H films deposited using the methods of the present invention typically have a lower SiC:SiN ratio (based on FTIR peak area) and a lower SiCH compared to known deposition recipes performed at low temperatures (e.g., less than about 250 °C). x :SiN ratio and a lower NH:SiN ratio. This indicates a high-density SiCN (or SiCN:H) film.

[0035] The SiCN:H film may have a SiH:SiN ratio (based on FTIR peak area) greater than about 0.8, optionally greater than about 0.10, and optionally greater than about 0.12. SiCN:H films deposited using the methods according to the present invention typically exhibit a high SiH:SiN ratio (based on FTIR peak area) by characteristic. The SiCN:H film may have a hydrogen content greater than about 2 at%, optionally greater than about 5 at%, or optionally greater than about 10 at%.

[0036] According to a third aspect of the present invention, a method for bonding two substrates is provided, the method comprising:

[0037] A step of providing a first substrate having a SiCN:H film according to a second embodiment;

[0038] Step of providing a second substrate having a SiCN:H film according to a second embodiment; and

[0039] The method includes the step of contacting the SiCN:H film of the first substrate with the SiCN:H film of the second substrate at a temperature of less than about 250°C in order to bond the SiCN:H film of the first substrate with the SiCN:H film of the second substrate.

[0040] The SiCN:H film of the first substrate may be in contact with the SiCN:H film of the second substrate at a temperature in the range of 100-250 ℃, optionally in the range of 125-225 ℃, optionally in the range of 150-200 ℃, or optionally at about 175 ℃.

[0041] A method for bonding two substrates may further include a smoothing step, such as a chemical mechanical planarization (CMP) step, for smoothing the SiCN:H films of the first and / or second substrates. A method for bonding two substrates may further include a step of aligning the first and second substrates before bringing the SiCN:H films of the first and second substrates into contact.

[0042] According to a fourth aspect of the present invention, a device comprising a stack of two or more substrates generated using the method of a third aspect is provided.

[0043] Although the present invention has been described above, it is extended to any original combination of features in the foregoing or following description, drawings, and claims. For example, any feature disclosed in connection with one aspect of the present invention may be combined with any feature disclosed in connection with any of the other aspects of the present invention. Brief explanation of the drawing

[0044] Embodiments of the present invention will now be described only by way of example with reference to the attached drawings. Figure 1 is a schematic side view of two substrates ready to undergo a surface-activated substrate-substrate bonding process. Figure 2 shows the FTIR spectra of SiCN:H films deposited using comparative examples. Figure 3 shows the FTIR spectra of SiCN:H films deposited using comparative examples. Figure 4 shows the FTIR spectra of SiCN:H films deposited using the method of the present invention and a comparative example. Figure 5 is a plot showing the carbon content in the deposited SiCN:H layer as a function of the ratio of carbon donor precursor to silane. Figure 6 is a plot showing the change in refractive index (RI) after a period of 6 days as a function of the ratio of carbon donor precursor to silane. Figure 7 shows the FTIR spectra of the SiCN:H film before and after a 6-day exposure period to air. Figure 8 is a plot showing the change in refractive index (RI) for a SiCN:H film deposited using an exemplary method of the present invention. FIG. 9 shows FTIR spectra of SiCN:H deposited using exemplary methods of the present invention. FIG. 10 is a plot showing the change in refractive index of SiCN:H films deposited using exemplary methods of the present invention. Specific details for implementing the invention

[0045] FIG. 1 illustrates a schematic diagram of a surface-activated bonding process used to bond two substrates together. The substrates (10a, 10b) may include temperature-sensitive features such as device layers (12a, 12b). An adhesive layer (14a, 14b), such as a silicon carbon nitride (SiCN:H) layer or a silicon carbon nitride (SiCN) layer, is deposited on the surface of each substrate (10a, 10b). The two adhesive layers (14a, 14b) can be smoothed, precisely aligned, pressed together at an elevated temperature, and annealed, for example, by chemical mechanical planarization (CMP), to bond the two substrates together through this adhesive layer.

[0046] An apparatus suitable for depositing silicon carbonitride (SiCN) films, such as SiCN:H films, according to the exemplary methods (and comparative examples) of the present invention includes the SPTS Delta™ parallel plate PECVD apparatus commercially available from SPTS Technologies Limited, located in Newport, South Wales, UK. All exemplary embodiments and comparative examples described below were performed using this apparatus.

[0047] Comparison Examples 1 and 2

[0048] SiCN:H adhesive layers are known to be deposited using plasma-enhanced chemical vapor deposition (PECVD) at high temperatures (e.g., about 340–370 °C) using organic silanes and ammonia (NH3) as reactive precursors. Organic silanes act as silicon and carbon donor precursors, while ammonia acts as a nitrogen donor precursor.

[0049] As comparative examples (and with reference to FIG. 2), SiCN:H films were deposited on a 300 mm silicon wafer by PECVD at 350 °C using organic silane and ammonia (NH3) as reactive precursors. The chamber pressure was maintained in the range of 1-5 Torr. In Comparative Example 1 (line (21) in FIG. 2), trimethylsilane (3MS) was used as the organic silane precursor. In Comparative Example 2 (line (22) in FIG. 2), tetramethylsilane (4MS) was used as the organic silane precursor.

[0050] The characteristic Si-CH3 stretching peak is approximately 1257 cm⁻¹ in both Comparative Examples 1 and 2. -1 As can be seen in [the image], this is more pronounced when 3MS (i.e., Comparative Example 1, line (21)) is used as an organosilane precursor. Both spectra (21 and 22) show Si-H n (n=1-3) and CH m (m=1-3) Approximately 2133 cm, each corresponding to the stretching peaks -1 and about 2900 cm -1 It exhibits similar intensity peaks.

[0051] Comparison Examples 3 and 4

[0052] As additional comparative examples (and with reference to FIG. 3), SiCN:H films were deposited on a 300 mm silicon wafer by PECVD using organic silane (3MS) and ammonia (NH3) as reactive precursors. The plasma was maintained using mixed frequency RF power; that is, the plasma was maintained using high frequency (HF) RF (operating at 13.56 Hz) and low frequency (LF) RF (operating at 380 kHz). Comparative Example 3 (line (33) in FIG. 3) and Comparative Example 4 (line (34) in FIG. 3) use the same deposition parameters, except that Comparative Example 3 uses a high deposition temperature of 370 °C, while Comparative Example 4 uses a low deposition temperature of 175 °C.

[0053] The SiCN:H film deposited in Comparative Example 3 (line (33)) exhibited acceptable properties as an adhesion layer and / or copper barrier layer. However, the high temperature required to deposit this film cannot be used for temperature-sensitive substrates (i.e., substrates with low thermal budget constraints).

[0054] The SiCN:H film deposited in Comparative Example 4 (i.e., at a low temperature of 175 °C, line (34)) has a Si-CH3 stretching peak (~1257 cm⁻¹) compared to the film deposited at 370 °C (Comparative Example 3, line (30)). -1 ), Si-H n (n=1-3) Stretching peak (~2133 cm) -1 ), and CH m (m=1-3) Stretching peak (~2900 cm) -1 It shows a significant increase of ). Additionally, 600-1200 cm -1 The peaks at are more pronounced in SiCN:H films deposited at 175 °C. These FTIR spectra indicate that SiCN:H films deposited at 175 °C contain more CH compared to SiCN:H films deposited at 370 °C. n , Si-CH n , Si-Hn (n=1-3) indicates that it includes terminated groups.

[0055] The SiCN:H films deposited in Comparative Example 4 (i.e., at 175 °C, using 3MS and NH3 as reactive precursors) have a lower density and a lower refractive index of ~1.57. Due to the low density and porosity of the film, the SiCN:H films deposited in Comparative Example 4 absorb moisture. The film in Comparative Example 4 cannot be used as an adhesive layer. Additionally, due to the low density, the film may become a poor copper barrier layer and may release gas during the bonding process, which could adversely affect the substrate-substrate bonding strength. The unacceptable film formed in Comparative Example 4 demonstrates that depositing acceptable SiCN:H films at low temperatures (e.g., <250 °C) is not a trivial variation.

[0056] Exemplary embodiments

[0057] The present invention provides a method for depositing silicon carbonitride (SiCN:H) films suitable for use as adhesive layers in a surface-activated bonding process. In particular, acceptable SiCN:H films may be deposited on substrates at temperatures below about 250 °C, optionally below 200 °C, and optionally about 175 °C. The substrate may be a semiconductor substrate, such as a silicon substrate or a silicon wafer. The substrate may include a plurality of dies. The substrate may include temperature-sensitive features, such as device layers and interconnects, which may include copper layers embedded in a dielectric.

[0058] Exemplary embodiments of the present invention include introducing a silicon donor precursor, a carbon donor precursor, and a nitrogen donor precursor into a PECVD chamber. Optionally, one or more non-reactive carrier gases may also be introduced into the chamber. Since a plasma is maintained within the chamber, a PECVD process may occur, thereby allowing SiCN:H to be deposited on a substrate. The silicon donor precursor is a silane (SiH4). The nitrogen donor precursor is nitrogen gas (N2). The carbon donor precursor may be an organic silane, methane (CH4), acetylene (C2H2), or a combination thereof. The organic silane may be a methyl silane, a dimethyl silane, a trimethyl silane (3MS), a tetramethyl silane (4MS), or a combination thereof.

[0059] Table 1 shows exemplary PECVD process parameters suitable for achieving stable SiCN:H films at deposition temperatures in the range of 100-250 ℃.

[0060] Process parameters range Preferred range Chamber pressure mT 1000-5000 1400-3000 N2 flow velocity Sccm 1000-10,000 2500-8000 Carbon donor precursor (e.g., 3MS) flow rate Sccm 10-90 10-55 SiH4 flow rate Sccm 100-500 200-300 HF RF power W 250-1250 500-1000 LF RF power W 0-400 0-200 temperature ℃ 100-250 100-200 ℃

[0061] Example 5

[0062] In one exemplary example (Example 5), a SiCN:H film was deposited on a 300 mm silicon wafer at 175 °C by PECVD. The reactive precursors were silane (SiH4), trimethylsilane (3MS) as a carbon donor precursor, and nitrogen gas (N2).

[0063] Using a combination of (non-carbon-containing) silanes and separate carbon-containing precursors allows for the carbon content of SiCN:H films to be finely tuned and changed in a controlled manner. This can also be more cost-effective than using a single organic silane precursor. The chamber pressure ranged from 1 to 5 Torr. The plasma was maintained using mixed-frequency RF power. The mixed-frequency RF power consisted of high-frequency RF (operating at 13.56 Hz) and low-frequency RF (operating at 380 kHz).

[0064] FIG. 4 shows the FTIR spectrum (line (45)) of a SiCN:H film deposited using the method of Example 5. Line (43) (Fig. 4) corresponds to a SiCN:H film deposited at 370 °C using the same conditions as those used in Comparative Example 3. Here, Comparative Example 3 is used as an exemplary spectrum of a SiCN:H film suitable for use as an adhesive layer.

[0065] Table 2 shows the FTIR peak regions using the SiN peak to normalize the results.

[0066] FTIR peak ratios SiC / SiN SiH / SiN Itself x / SiN NH / SiN RI HT NH3-based SiCN:H (Comparison Example 3) 0.0042 0.0466 0.0042 0.0097 1.9762 LT NH3-based SiCN:H (Comparison Example 4) 0.0956 0.0512 0.0281 0.0757 1.5691 LT N2-based SiCN:H (Example 5) 0.0036 0.1230 0.0080 0.0179 1.9972

[0067] The FTIR spectrum (line (45)) of the SiCN:H film deposited using the low temperature (LT) method of Example 5 was similar to the FTIR spectrum (lines (33, 43)) of the film deposited in Comparative Example 3. However, the SiCN:H film of Example 5 had a stronger Si-H peak (~2120 cm⁻¹) than the high temperature (HT) Comparative Example 3. -1 This represents ). This is a characteristic trait of SiCN:H films deposited using the methods of the present invention.

[0068] In addition, based on Table 2, the SiC / SiN, SiCH of Example 5 xIt is evident that the / SiN and NH / SiN ratios match Comparative Example 3 more closely than the results of Comparative Example 4. Additionally, the refractive indices of Comparative Example 3 and Example 5 match closely. The low refractive index of Comparative Example 4 suggests that this film has a very low density and is not suitable for use as an adhesive layer. Example 5 achieves a much superior film compared to Comparative Example 4 (which is also deposited at a low temperature but uses a known deposition recipe). Using a mixture of reactive precursors including a combination of silane (SiH4), a carbon donor precursor, and nitrogen gas (N2) provides suitable conditions for depositing SiCN:H films of improved quality while maintaining a low thermal budget. SiCN:H films deposited using these methods are acceptable for use as an adhesive layer in surface-activated bonding processes and can provide acceptable copper barrier layer characteristics.

[0069] Example 5 uses a 3MS carbon donor precursor, but acceptable results are expected to occur even if the 3MS precursor is replaced with other carbon donor precursors, such as alternative organosilane precursors, e.g., tetramethylsilane (4MS).

[0070] The ratio of the carbon donor precursor to the silane can be changed by altering the flow rates of the reactive precursors. Figure 5 shows the ratio (as a percentage) of the carbon donor precursor (i.e., 3 MS in this example) to the silane (SiH4) as SiC / SiN (~1250 cm⁻¹). -1 ) and SiCH x / SiN(~2900 cm -1 ) shows how it affects the ratios of FTIR peak areas (each line (50 and 52)). Peak areas (~840 cm²) -1The results for changes in film thickness were normalized by dividing by the major SiN peak area. By controlling the ratio of carbon donor precursor to silane (SiH4), the carbon content of the film can be changed in a controllable manner.

[0071] Figure 6 shows how the ratio of carbon donor precursor (i.e., 3MS in this example) to silane (SiH4) (as a percentage) affects the stability of the refractive index measured over a period of 6 days. Lower 3MS / SiH4 flow rates provided a smaller change (decrease) in RI over time, indicating a more stable membrane with lower sensitivity to moisture. A 3MS / SiH4 membrane ratio of ~20% provided an acceptable change in RI of less than 0.14. However, a 3MS / SiH4 flow rate ratio of ~10% provided a significant improvement in the stability of the measured RI. Changing the flow rate ratio of the carbon donor precursor to silane allows for fine-tuning the carbon content of SiCN:H membranes. Without being bound by any theory or speculation, it is believed that a higher carbon content in the membranes can provide improved bonding strength. However, SiCN:H membranes with high carbon content are also more sensitive to moisture absorption, resulting in reduced stability.

[0072] Figure 7 shows that the FTIR spectra of SiCN:H films deposited using these methods show no significant change over a period of 6 days, indicating that the film is stable. In particular, after exposure to the atmosphere for 6 days, the Si-O peak (~1050 cm⁻¹) -1 There was no observable increase at ), and the -OH peak (~3350 cm⁻¹) -1 In ), only a minimal increase existed. This indicates that the film is stable and that only minimal water vapor absorption occurs after exposure to the atmosphere at room temperature.

[0073] Figure 8 shows how the refractive index changes over a period of 6 days when exposed to the atmosphere. An initial decrease in RI is observed within the first 24 hours. However, thereafter, the RI remains stable at about 2.00.

[0074] Post-deposition treatment

[0075] Selective post-deposition treatment may be performed on SiCN:H films deposited using the methods of the present invention. Post-deposition treatment can improve the stability of the film and further improve (reduce) the sensitivity of the film to moisture. The post-deposition treatment may be thermal annealing, plasma treatment (e.g., hydrogen plasma treatment), e-beam treatment, UV curing techniques, or a combination thereof. Preferably, the post-deposition treatment is hydrogen plasma treatment.

[0076] Hydrogen plasma treatment may involve exposing the deposited SiCN:H film to hydrogen plasma, preferably without interrupting the vacuum and / or without exposure to water vapor / moisture. Hydrogen plasma treatment may involve introducing a hydrogen gas precursor into a chamber and maintaining the plasma. The pressure inside the chamber may be about 2 Torr. To maintain the plasma, high-frequency RF power of about 1 kW (e.g., operating at 13.56 MHz) may be used. Hydrogen plasma treatment may be performed for about 30 to 300 seconds, optionally about 60 seconds. During hydrogen plasma treatment, the substrate may be maintained at a temperature lower than the temperature used in the SiCN:H deposition step. For example, during hydrogen plasma treatment, the substrate may be maintained at a temperature of about 200 °C or lower, optionally about 175 °C or lower, optionally about 150 °C or lower, or optionally about 125 °C. Performing hydrogen plasma treatment at a low temperature (e.g., lower than the SiCN:H deposition step) allows the substrate to be kept within low thermal budget constraints. This prevents damage to any temperature-sensitive features of the substrate.

[0077] Figure 9 shows how the FTIR spectra change over a period of 6 days (each line (90 and 92)) with and without hydrogen plasma treatment after deposition.

[0078] Figure 10 shows how post-deposition hydrogen plasma treatment affects the RI stability of SiCN:H films deposited over a period of 6 days. In the absence of post-deposition hydrogen plasma treatment (line (100)), an initial decrease in RI is observed within the first 24 hours. However, thereafter, RI remains stable at approximately 2.00. However, with post-deposition hydrogen plasma treatment, the stability of RI is further improved (line 102)). When RI maintains a value of approximately 2.02–2.03, a negligible change in RI was observed over a period of 6 days. Without being bound by any theory or speculation, it is believed that hydrogen plasma treatment prevents moisture absorption by passivating the SiCN:H surface. Post-deposition hydrogen plasma treatment can be used to improve the stability of SiCN:H films.

Claims

Claim 1 A method for depositing a silicon carbonitride (SiCN:H) film on a substrate by plasma enhanced chemical vapor deposition (PECVD), comprising the steps of: providing the substrate into a chamber; introducing a silane (SiH4), a carbon-donating precursor, and a nitrogen gas (N2) into the chamber; and maintaining a plasma in the chamber to deposit SiCN:H on the substrate by PECVD, wherein the substrate is maintained at a temperature of less than 225°C, less than 200°C, or about 175°C or lower. Claim 2 A method according to claim 1, wherein the carbon donor precursor is an organic silane. Claim 3 The method according to paragraph 2, wherein the organic silane is selected from methyl silane, dimethyl silane, trimethyl silane, tetramethyl silane, or combinations thereof. Claim 4 A method according to claim 1, wherein the carbon donor precursor is a gaseous hydrocarbon such as methane (CH4) or acetylene (C2H2), or a combination thereof. Claim 5 A method according to any one of claims 1 to 4, wherein silane (SiH4) is introduced into the chamber at a flow rate of 100 to 500 sccm, or 200 to 400 sccm, or 250 to 300 sccm, or about 275 sccm. Claim 6 A method according to any one of claims 1 to 4, wherein the carbon donating precursor is introduced into the chamber at a flow rate in the range of 10 to 90 sccm, or in the range of 20 to 70 sccm, or in the range of 25 to 55 sccm. Claim 7 A method according to any one of claims 1 to 4, wherein the silane (SiH4) and the carbon donor precursor are introduced into the chamber at a flow rate (in sccm units) in a ratio of 3:1 to 30:1, or 4:1 to 25:1, or 5:1 to 20:1, or about 7:1 to 15:1, or about 10:1 to 12:1, or about 11:

1. Claim 8 A method according to any one of claims 1 to 4, wherein nitrogen gas (N2) is introduced into the chamber at a flow rate in the range of 1,000 to 10,000 sccm, or in the range of 2,500 to 9,000 sccm, or in the range of 4,000 to 8,000 sccm, or in the range of 6,000 to 7,000 sccm. Claim 9 A method according to any one of claims 1 to 4, wherein while the plasma is maintained within the chamber, the chamber has a pressure in the range of 1 to 5 Torr, or in the range of 1.4 to 3 Torr, or about 1.6 Torr. Claim 10 A method according to any one of claims 1 to 4, further comprising a subsequent step of performing a hydrogen plasma treatment including exposing the SiCN:H film to a hydrogen plasma. Claim 11 A method according to claim 10, wherein during the hydrogen plasma treatment, the substrate is maintained at a temperature of less than about 200°C, or less than about 175°C, or less than about 150°C, or about 125°C. Claim 12 A method according to any one of claims 1 to 4, wherein the silicon hydride carbon nitride film is an amorphous silicon hydride carbon nitride film (a-SiCN:H). Claim 13 A method according to any one of claims 1 to 4, wherein the substrate is a semiconductor substrate. Claim 14 A substrate on which a SiCN:H film is deposited using a method according to any one of claims 1 to 4. Claim 15 A substrate according to claim 14, wherein the SiCN:H film has a hydrogen content of more than about 2 at%, or more than about 5 at%, or more than about 10 at%. Claim 16 A method for bonding two substrates, comprising: providing a first substrate having a SiCN:H film according to claim 14; providing a second substrate having a SiCN:H film according to claim 14; and bonding the SiCN:H film of the first substrate to the SiCN:H film of the second substrate at a temperature of about 250°C or less. Claim 17 A device comprising a stack of two or more substrates created using the method according to claim 16. Claim 18 delete

Images