阅读说明：本技术 沉积的方法 (Method of deposition ) 是由 T·哈珀 K·克鲁克 于 2021-05-19 设计创作，主要内容包括：本申请的实施例涉及一种沉积方法。根据本发明,提供了一种通过等离子体增强的化学气相沉积PECVD在衬底上沉积氢化的氮化硅碳(SiCN:H)膜的方法,其包括：在腔室中提供所述衬底；将硅烷(SiH-(4))、供碳前体和氮气(N-(2))引入到所述腔室中；以及在所述腔室中维持等离子体,以便通过PECVD在所述衬底上沉积SiCN:H,其中所述衬底维持在低于约250℃的温度。(Embodiments of the present application relate to a deposition method. According to the present invention, there is provided a method of depositing a hydrogenated carbon silicon nitride (SiCN: H) film on a substrate by plasma enhanced chemical vapor deposition PECVD, comprising: providing the substrate in a chamber; silane (SiH) 4 ) Carbon precursor and nitrogen (N) 2 ) 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 about 250 ℃.)

1. A method of depositing a hydrogenated silicon carbon nitride (SiCN: H) film on a substrate by plasma enhanced chemical vapor deposition PECVD, comprising:

providing the substrate in a chamber;

silane (SiH)₄) Carbon precursor and nitrogen (N)₂) 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 about 250 ℃.

2. The method of claim 1, wherein the carbon donating precursor is an organosilane.

3. The method of claim 2, wherein the organosilane is selected from methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, or a combination thereof.

4. The method of claim 1, wherein the carbon donating precursor is a gaseous hydrocarbon, such as methane (CH)₄) Or acetylene (C)₂H₂) Or a combination thereof.

5. The method of any preceding claim, wherein Silane (SiH)₄) Is introduced into the chamber at a flow rate in the range of 100-500sccm, optionally 200-400sccm, optionally 250-300sccm, or optionally about 275 sccm.

6. The method of any preceding claim, wherein the carbon-donating precursor is introduced into the chamber at a flow rate in the range of 10-90 seem, optionally 20-70 seem, or optionally 25-55 seem.

7. The method of any preceding claim, wherein Silane (SiH)₄) And the carbon donating precursor is selected from the group consisting of 3:1 to 30:1, optionally 4:1 to 25:1, optionally 5:1 to 20:1, optionally aboutA flow rate (in sccm) in the range of 7:1 to 15:1, optionally about 10:1 to 12:1, or optionally about 11:1, is introduced into the chamber.

8. The method according to any preceding claim, wherein nitrogen (N) is introduced₂) Is introduced into the chamber at a flow rate in the range of 1000-.

9. The method of any preceding claim, wherein the substrate is maintained at a temperature of less than 225 ℃, optionally less than 200 ℃, or optionally about 175 ℃ or less.

10. The method of any preceding claim, wherein the chamber has a pressure in the range of 1-5 torr, optionally 1.4-3 torr, optionally about 1.6 torr, when the plasma is maintained in the chamber.

11. The method of any preceding claim, further comprising a subsequent step of performing a hydrogen plasma treatment comprising exposing the SiCN: H film to a hydrogen plasma.

12. The method of claim 11, wherein the substrate is maintained at a temperature of less than about 200 ℃, optionally less than about 175 ℃, optionally less than about 150 ℃, or optionally about 125 ℃ during the hydrogen plasma treatment.

13. A method according to any preceding claim, wherein the hydrogenated silicon carbon nitride film is an amorphous hydrogenated silicon carbon nitride film (a-SiCN: H).

14. The method of any preceding claim, wherein the substrate is a semiconductor substrate.

15. A substrate having a SiCN: H film deposited thereon using the method of any preceding claim.

16. The substrate of claim 15, wherein the SiCN: H film has a hydrogen content greater than about 2 at%, optionally greater than about 5 at%, and optionally greater than about 10 at%.

17. A method of bonding two substrates, comprising the steps of:

providing a first substrate having a SiCN H film according to claim 15;

providing a second substrate having a SiCN H film according to claim 15; and

bonding the SiCN: H film of the first substrate to the SiCN: H film of the second substrate at a temperature of less than about 250 ℃.

18. An apparatus comprising a stack of two or more substrates produced using the method of claim 17.

Technical Field

The present invention relates to a method of depositing a silicon nitride carbon film by Plasma Enhanced Chemical Vapor Deposition (PECVD). In particular, the present invention relates to a method of depositing a hydrogenated silicon carbon nitride (SiCN: H) film by PECVD. The invention also relates to a substrate having an associated SiCN: H film. The invention also relates to a method of bonding two substrates, and to an associated device comprising two bonded substrates.

Background

Two-dimensional (2D) scaling of electronic devices based on moore's law will continue in the foreseeable future. However, three-dimensional (3D) integration of devices, whether homogeneous or heterogeneous, offers tremendous potential for advanced system development. It is believed that "stacked" devices in 3D may enable greater integration compared to 2D scaling methods, which in turn will provide improved device performance, improved functionality, and ultimately reduced cost.

To achieve efficient 3D integration of devices, it is desirable to bond two substrates (e.g., device wafers) together so that a large number of dies can be stacked simultaneously. Surface-activated bonding techniques are promising candidates for enabling 3D stacking of suitable devices. Typically, the surface activated bonding process involves treating the surfaces of two substrates, for example with a dielectric bonding/adhesion layer, such as a silicon carbon nitride (SiCN) layer (including a hydrogenated silicon carbon nitride (SiCN: H) layer). The two treated surfaces may then be smoothed, precisely aligned, pressed together at elevated temperature, and annealed by Chemical Mechanical Planarization (CMP) to bond the substrates together.

Known surface-activated bonding techniques use dielectric bond and adhesion layers, such as SiCN and SiCN: H, which are deposited at high temperatures (about 340-. These known processes are not suitable for bonding substrates with low thermal budget constraints (i.e., temperature sensitive substrates) due to the high temperatures required. For example, it is critical that the substrate including the device layers and/or interconnects (which may comprise copper layers embedded in a dielectric) maintain a low thermal budget to avoid damaging the devices.

However, simply lowering the deposition temperature of the bonding layer and the adhesion layer results in an adhesion layer with poor bonding strength, poor copper barrier properties, and high sensitivity to moisture. Thus, simply lowering the temperature of known deposition processes provides unacceptable results.

Therefore, there is a need for a method in which dielectric barrier and adhesion layers for wafer-to-wafer bonding can be deposited at significantly lower temperatures while maintaining excellent device performance. This is desirable so that a greater variety of substrates (particularly substrates with low thermal budget constraints) can be bonded using surface-activated bonding techniques. By providing such a method, an improved 3D integration of the device may be achieved, which is expected to improve the device performance.

Disclosure of Invention

The present invention, in at least some embodiments thereof, seeks to address at least some of the above mentioned problems, desires and needs. In particular, embodiments of the present invention seek to provide a method of depositing a hydrogenated silicon carbon nitride (SiCN: H) film that is capable of maintaining a low thermal budget for the substrate. The SiCN: H films deposited by the method of the present invention are suitable for use as adhesion layers in surface activated bonding techniques while remaining within low thermal budget limits. The film also exhibits good copper barrier properties and is stable in the presence of moisture.

According to a first aspect of the present invention, there is provided a method of depositing a hydrogenated silicon carbon nitride (SiCN: H) film on a substrate by Plasma Enhanced Chemical Vapor Deposition (PECVD), comprising:

providing the substrate in a chamber;

silane (SiH)₄) Carbon precursor and nitrogen (N)₂) 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 about 250 ℃.

It has been found that the use of a Silane (SiH) -containing compound₄) Carbon-supplying precursor and nitrogen (N) gas separately₂) As a reactive precursor to produce stable SiCN: H films with good barrier and bonding layer properties while remaining within low thermal budget limits. The SiCN: H film is suitable for use as an adhesion layer in a surface activated bonding process. Thus, the method is suitable for 3D integration of a variety of substrates, including device wafers, which contain temperature sensitive device layers and their interconnects that can be embedded in the substrate. The reactive precursor used may consist essentially of Silane (SiH)₄) Carbon-supplying precursor and nitrogen (N) gas separately₂) The composition of (a). Preferably, the reactive precursor used is made of Silane (SiH)₄) Carbon-supplying precursor and nitrogen (N) gas separately₂) The composition of (a). Optionally, one or more non-reactive carrier gases may also be introduced into the chamber.

The carbon-donating precursor can be an organosilaneA gaseous hydrocarbon, or a combination thereof. Preferably, the carbon-donating precursor is an organosilane. The organosilane may be an alkylsilane. The organosilane may be selected from methylsilane, dimethylsilane, trimethylsilane, tetramethylsilane or combinations thereof. Preferably, the organosilane is trimethylsilane or tetramethylsilane. Most preferably, the organosilane is trimethylsilane. It has been found that the use of a composition comprising Silane (SiH)₄) Organosilane and nitrogen (N)₂) To produce SiCN: H films with particularly desirable characteristics, for example as good copper barrier layers. Optionally, the carbon donating precursor can be a gaseous hydrocarbon. The gaseous hydrocarbon may be methane (CH)₄) Or acetylene (C)₂H₂)。

Silane (SiH)₄) Is a silicon precursor. Silane (SiH)₄) Can be introduced into the chamber at a flow rate in the range of 100-500sccm, optionally 200-400sccm, optionally 250-300sccm, or optionally about 275 sccm.

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

The carbon-donating precursor can be less than Silane (SiH)₄) Is introduced into the chamber. The flow rate of the carbon-supplying precursor may be Silane (SiH)₄) About 2-50%, optionally about 5-25%, optionally about 7-20%, optionally about 8-15% or optionally about 10-11% of the flow rate of (a).

Silane (SiH)₄) And a carbon-donating precursor, such as trimethylsilane, can be introduced into the chamber at a ratio (in sccm) in the 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. Silane (SiH) is added in these ratios₄) And the introduction of a carbon precursor into the chamber can improve the adhesion characteristics of the deposited SiCN: H film while maintaining a high resistance to moisture absorption. Without wishing to be bound by any theory or speculation, it is believed that the improved adhesion characteristics are a result of the increased carbon content of the deposited SiCN: H film. By way of example only, where the carbon donating precursor is trimethylsilane, Silane (SiH) is preferred₄) The ratio to trimethylsilane is from about 10:1 to12:1, or most preferably 11: 1.

Nitrogen (N)₂) Is a nitrogen donor precursor. Nitrogen (N)₂) May be introduced into the chamber at a flow rate in the range of 1000-. Optionally, ammonia (NH) is absent as nitrogen donor precursor₃). Advantageously, N₂Is the only nitrogen donor precursor used.

During the PECVD step, the substrate may be maintained at a temperature of less than 225 ℃, optionally less than 200 ℃, or optionally about 175 ℃ or less. The substrate may be maintained at a temperature above 100 ℃, optionally above 125 ℃, optionally above 150 ℃. Maintaining the substrate at these temperatures can keep the substrate within low thermal budget limits, which makes the present method suitable for depositing SiCN: H films on temperature sensitive substrates. For example, the method may be used to deposit a SiCN: H (adhesion) layer on a temperature sensitive substrate including device layers and/or interconnects, which may comprise a copper layer embedded in a dielectric.

The chamber may have a pressure in the range of 1,000-5,000 mtorr, optionally 1,400-3,000 mtorr, optionally about 1,600 mtorr, when the plasma is sustained in the chamber.

High frequency RF power may be used to sustain the plasma. Alternatively, the plasma may be sustained using both high frequency RF power and low frequency RF power.

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

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

The method may further include performing a subsequent step of hydrogen plasma treatment including exposing the SiCN: H film to a hydrogen plasma. The hydrogen plasma treatment can further improve the stability of the SiCN: H film. Without wishing to be bound by any theory or speculation, it is believed that the hydrogen plasma treatment acts to passivate the surface of the SiCN: H film, thereby preventing the surface from absorbing moisture and forming SiO. The hydrogen plasma treatment may be performed without vacuum interruption. The hydrogen plasma treatment may be performed without exposing the SiCN: H film to water vapor.

During the hydrogen plasma treatment, the substrate may be maintained at a temperature of less than about 200 ℃, optionally less than about 175 ℃, optionally less than about 150 ℃, or optionally about 125 ℃.

The hydrogenated silicon carbon nitride (SiCN: H) film may be an amorphous film (e.g., a-SiCN: H).

The substrate may be a semiconductor substrate.

According to a second aspect of the present invention there is provided a substrate having a film of SiCN: H deposited thereon using a method according to the first aspect.

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 feature may be temperature sensitive. The feature may comprise a copper layer, for example a copper layer embedded in a dielectric material.

The SiCN: H film may have a refractive index in the range of about 2.0. The SiCN: H film 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.

The SiCN: H film can have a SiC to SiN ratio (based on FTIR peak area) of less than about 0.01, optionally less than about 0.005, optionally about 0.004.

The SiCN H film can have less than about 0.01, optionally about 0.008 SiCH_xSiN ratio (based on FTIR peak area).

The SiCN: H film can have a NH to SiN ratio (based on FTIR peak area) of less than about 0.02, optionally about 0.018.

SiCN to H films deposited using the method of the invention generally exhibit lower SiC to SiN ratios, lower SiCH than known deposition recipes conducted at low temperatures (e.g., less than about 250℃.)_xSiN ratio andlower NH to SiN ratio (based on FTIR peak area). This indicates a high density SiCN (or SiCN: H) film.

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

According to a third aspect of the present invention, there is provided a method of bonding two substrates, comprising the steps of:

providing a first substrate having a SiCN H film according to the second aspect;

providing a second substrate having a SiCN H film according to the second aspect; and

the SiCN: H film of the first substrate is brought into contact with the SiCN: H film of the second substrate at a temperature of less than about 250 ℃ to bond the SiCN: H film of the first substrate with the SiCN: H film of the second substrate.

The SiCN: H film of the first substrate can be contacted with the SiCN: H film of the second substrate at a temperature in the range of 100-.

The method of bonding two substrates may further include a smoothing step, such as a Chemical Mechanical Planarization (CMP) step, to smooth the SiCN: H film of the first substrate and/or the second substrate. The method of bonding two substrates may further include the step of aligning the first substrate and the second substrate before contacting the SiCN: H films of the first substrate and the second substrate.

According to a fourth aspect of the present invention there is provided an apparatus comprising a stack of two or more substrates produced using the method of the third aspect.

Although the invention has been described above, it extends to any inventive combination of the features set out above or in the following description, drawings or claims. For example, any feature disclosed in relation to one aspect of the invention may be combined with any feature disclosed in relation to any other aspect of the invention.

Drawings

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic side view of two substrates ready for a surface activated substrate-substrate bonding process;

FIG. 2 shows FTIR spectra of a SiCN: H film deposited using a comparative example;

FIG. 3 shows FTIR spectra of a SiCN: H film deposited using a comparative example;

FIG. 4 shows FTIR spectra of SiCN: H films deposited using the method of the present invention and comparative examples;

FIG. 5 is a graph showing carbon content in a deposited SiCN: H layer as a function of the ratio of carbon donating precursor to silane;

FIG. 6 is a graph showing the change in Refractive Index (RI) as a function of carbon donor precursor to silane ratio after a six day period;

FIG. 7 shows FTIR spectra of a SiCN: H film before and after six days of exposure to air;

FIG. 8 is a graph illustrating the change in Refractive Index (RI) of a H film deposited using an exemplary method of the present invention;

FIG. 9 shows FTIR spectra of SiCN: H deposited using an exemplary method of the invention; and is

Fig. 10 is a graph illustrating the change in refractive index of a SiCN: H film deposited using an exemplary method of the present invention.

Detailed Description

Fig. 1 shows a schematic view of a surface activated bonding process for bonding two substrates together. The substrates 10a, 10b may include temperature sensitive features, such as device layers 12a, 12 b. An adhesion layer 14a, 14b, such as a silicon carbon nitride (SiCN) layer, such as a hydrogenated silicon carbon nitride (SiCN: H) layer, is deposited on the surface of each substrate 10a, 10 b. The two adhesion layers 14a, 14b may be smoothed, precisely aligned, for example by Chemical Mechanical Planarization (CMP), pressed together at elevated temperature, and annealed to bond the two substrates together via the adhesion layers 14a, 14 b.

Exemplary methods according to the invention (and comparative examples)) An apparatus suitable for depositing silicon carbon nitride (SiCN) films (e.g., SiCN: H films) includes SPTS Delta^TMParallel plate PECVD equipment, available from SPTS Technologies Limited, located in New Port of South Wales, UK. All of the exemplary embodiments and comparative examples described below were carried out using this apparatus.

Comparative examples 1 and 2

It is known to use organosilanes and ammonia (NH)₃) As a reactive precursor, a high temperature (e.g., about 340-. The organosilane serves as a silicon and carbon donor precursor and the ammonia serves as a nitrogen donor precursor.

As a comparative example (and with reference to fig. 2), organosilane and ammonia (NH) were used₃) As a reactive precursor, a SiCN: H film was deposited by PECVD onto a 300mm silicon wafer at 350 ℃. The chamber pressure is maintained in the range of 1-5 torr. In comparative example 1 (line 21 of fig. 2), trimethylsilane (3MS) was used as an organosilane precursor. In comparative example 2 (line 22 of fig. 2), tetramethylsilane (4MS) was used as an organosilane precursor.

In comparative examples 1 and 2, at about 1257cm^-1Can see characteristic Si-CH₃The peak was stretched, but more pronounced when 3MS was used as the organosilane precursor (i.e., comparative example 1, line 21). Spectra 21 and 22 correspond to Si-H, respectively_n(n-1-3) and CH_m(m-1-3) about 2133cm of stretching peak^-1And about 2900cm^-1All show similar intensity peaks.

Comparative examples 3 and 4

As a further comparative example (and with reference to FIG. 3), trimethylsilane (3MS) and ammonia (NH) were used₃) As a reactive precursor, a SiCN: H film was deposited by PECVD onto a 300mm silicon wafer. Plasma is sustained using mixed frequency RF power. That is, a High Frequency (HF) RF (operating at 13.56 Hz) and a Low Frequency (LF) RF (operating at 380 kHz) are used to sustain the plasma. Comparative example 3 (line 33 of fig. 3) and comparative example 4 (line 34 of fig. 3) used the same deposition parameters except that comparative example 3 used a high deposition temperature of 370 ℃Whereas comparative example 4 used a low deposition temperature of 175 ℃.

The SiCN: H film deposited in comparative example 3 (line 33) exhibited acceptable performance as an adhesion layer and/or copper barrier layer. However, the high temperatures required to deposit such films cannot be used with temperature sensitive substrates (i.e., substrates with low thermal budget constraints).

The SiCN: H film deposited in comparative example 4 (i.e., line 34 at a lower temperature of 175 ℃) shows Si-CH as compared to the film deposited at 370 ℃ (comparative example 3, line 30)₃Stretching Peak (about 1257 cm)^-1)、Si-H_n(n-1-3) stretching peak (about 2133 cm)^-1) And CH_m(m-1-3) stretching peak (about 2900 cm)^-1) Is significantly increased. In addition, at 600-1200cm^-1The peaks are more prominent for the SiCN: H film deposited at 175 c. These FTIR spectra show that the SiCN: H film deposited at 175 deg.C contains more CH than the SiCN: H film deposited at 370 deg.C_n、Si-CH_n、Si-H_n(n-1-3) terminal group.

H film of SiCN deposited in comparative example 4 (i.e., at 175 ℃ C., using 3MS and NH)₃As a reactive precursor) has a lower density and a lower refractive index of about 1.57. The SiCN: H film deposited in comparative example 4 absorbs moisture due to the low density and porosity of the film. The film of comparative example 4 was not feasible as an adhesion layer. Furthermore, due to the low density, the film will be a poor copper barrier and may outgas during the bonding process, which will adversely affect the substrate-substrate bond strength. Unacceptable films formed in comparative example 4 indicate that at low temperatures (e.g., as indicated by<H films deposited at 250 ℃ with acceptable SiCN are not insignificant changes.

Exemplary embodiments

The present invention provides a method of depositing a hydrogenated silicon carbon nitride (SiCN: H) film that can be used as an adhesion layer in a surface activated bonding process. In particular, acceptable SiCN: H films can be deposited onto a substrate at temperatures below about 250 ℃, optionally below 200 ℃, optionally about 175 ℃. 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 comprise a copper layer embedded in a dielectric.

Exemplary embodiments of the present invention include introducing a silicon-donating precursor, a carbon-donating precursor, and a nitrogen-donating precursor into a PECVD chamber. Optionally, one or more non-reactive carrier gases may also be introduced into the chamber. A plasma is maintained within the chamber so that a PECVD process can be performed, which deposits SiCN: H onto the substrate. The silicon-donating precursor being Silane (SiH)₄). The nitrogen donor precursor is nitrogen (N)₂). The carbon donor precursor may be organosilane, methane (CH)₄) Acetylene (C)₂H₂) Or a combination thereof. The organosilane may be methylsilane, dimethylsilane, trimethylsilane (3MS), tetramethylsilane (4MS), or a combination thereof.

Table 1 shows exemplary PECVD process parameters suitable for obtaining stable SiCN: H films at deposition temperatures in the range of 100-.

TABLE 1

Example 5

In one exemplary embodiment (example 5), a SiCN: H film was deposited by PECVD onto a 300mm silicon wafer at 175 ℃. The reactive precursor being Silane (SiH)₄) Trimethylsilane (3MS) as a carbon donor precursor and nitrogen (N)₂)。

The use of a combination of (non-carbon containing) silane and discrete carbon containing precursors allows the carbon content of the SiCN: H film to be fine tuned and varied in a controlled manner. This is also more cost effective than using a single organosilane precursor. The chamber pressure is in the range of 1-5 torr. Plasma is sustained using mixed frequency RF power. The mixed frequency RF power includes high frequency RF (operating at 13.56 Hz) and low frequency RF (operating at 380 kHz).

Figure 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 ℃ using the same conditions as used in comparative example 3. Comparative example 3 is used herein as an exemplary spectrum of a SiCN: H film that may be suitable for use as an adhesion layer.

Table 2 shows FTIR peak areas normalized to the results using SiN peaks.

TABLE 2

The FTIR spectra (lines 45) of the SiCN: H films deposited using the Low Temperature (LT) method of example 5 are similar to those of the films deposited in comparative example 3 (lines 33, 43). However, the SiCN: H film of example 5 exhibited a stronger Si-H peak (about 2120 cm) than that of High Temperature (HT) comparative example 3^-1). This is a characteristic feature of the SiCN: H films deposited using the method of the present invention.

Further, based on Table 2, it is apparent that SiC/SiN, SiCH of example 5_xthe/SiN and NH/SiN ratios are more matched than the results of comparative example 4 with comparative example 3. In addition, the refractive indices of comparative example 3 and example 5 were closely matched. The low refractive index of comparative example 4 indicates that the film has a very low density and is not suitable for use as an adhesive layer. Example 5 gave a very superior film compared to comparative example 4, which was also deposited at low temperature, but using a known deposition recipe. Using gases containing Silane (SiH)₄) Carbon precursor and nitrogen (N)₂) The combined reactive precursor mixture of (a) provides suitable conditions for deposition of SiCN: H films with improved quality while maintaining a low thermal budget. The SiCN: H films deposited using the present method can be used as adhesion layers in surface activated bonding processes and can provide acceptable copper barrier properties.

Although example 5 uses a 3MS carbon donating precursor, acceptable results are expected to occur if the 3MS precursor is substituted with other carbon donating precursors, such as alternative organosilane precursors, e.g., tetramethylsilane (4 MS).

The ratio of carbon-donating precursor to silane can be varied by varying the flow rate of the reactive precursor. FIG. 5 shows a carbon donor precursor (i.e., 3MS in this example) with Silane (SiH)₄) How the ratio of (in%) affects the SiC/SiN(about 1250 cm)^-1) And SiCH_x/SiN (about 2900 cm)^-1) FTIR peak area ratios (lines 50 and 52, respectively). Peak area to major SiN peak area (about 840 cm)^-1) To normalize the results to changes in film thickness. Controlling carbon donor precursor and Silane (SiH)₄) The ratio of (a) allows the carbon content of the film to be varied in a controlled manner.

FIG. 6 shows a carbon donor precursor (i.e., 3MS in this example) with Silane (SiH)₄) How the ratio of (in percent) affects the stability of the refractive index measured over a six day period. Lower 3MS/SiH₄The flux ratio gave less RI change (decrease) over time, indicating a more stable membrane that was less sensitive to moisture. 3MS/SiH₄A film ratio of about 20% provides an acceptable variation in RI of less than 0.14. However, about 10% 3MS/SiH₄The flow ratio provides a significant improvement in the stability of the measured RI. Varying the flow ratio of the carbon donor precursor to silane allows for fine tuning of the carbon content in the SiCN: H film. Without wishing to be bound by any theory or conjecture, it is believed that the high carbon content in the film may provide improved bond strength. However, SiCN: H films with higher carbon content are also more hygroscopic and therefore less stable.

Figure 7 shows that the FTIR spectra of SiCN: H films deposited using these methods did not show significant FTIR spectral changes over a six day period, indicating that the films were stable. In particular, no Si-O peak (about 1050 cm) was observed after six days of atmospheric exposure^-1) And only-OH peak (about 3350 cm) was observed^-1) A minimum increase in. This indicates that the film is stable and that only minimal water vapor absorption occurs after exposure to the atmosphere at room temperature.

Fig. 8 shows how the refractive index changes over a six day period when exposed to the atmosphere. A preliminary decrease in RI was observed over the first 24 hours. However, thereafter, the RI remained stable at about 2.00.

Post-deposition treatment

The SiCN: H films deposited using the method of the present invention can be subjected to optional post-deposition treatments. 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 a thermal anneal, a plasma treatment (such as a hydrogen plasma treatment), an electron beam treatment, an ultraviolet curing technique, or a combination thereof. Preferably, the post-deposition treatment is a hydrogen plasma treatment.

The hydrogen plasma treatment may include exposing the deposited SiCN: H film to a hydrogen plasma, preferably without interruption in a vacuum and/or without exposure to water vapor/moisture. Hydrogen plasma processing may include introducing a hydrogen gas precursor into the chamber and maintaining a plasma. The pressure in the chamber may be about 2 torr. A high frequency RF power of about 1kW (e.g., operating at 13.56 MHz) may be used to sustain the plasma. The hydrogen plasma treatment may be performed for a duration of about 30-300 seconds, optionally about 60 seconds. During the hydrogen plasma treatment, the substrate may be maintained at a temperature lower than the temperature used for the SiCN: H deposition step. For example, during hydrogen plasma processing, the substrate may be maintained at a temperature of about 200 ℃ or less, optionally about 175 ℃ or less, optionally about 150 ℃ or less, or optionally about 125 ℃. Performing the hydrogen plasma treatment at low temperatures (e.g., below the SiCN: H deposition step) can keep the substrate within low thermal budget limits. This helps to avoid damaging any temperature sensitive properties of the substrate.

Fig. 9 shows how the FTIR spectra change during six days with and without post-deposition hydrogen plasma treatment (lines 90 and 92, respectively).

Figure 10 shows how post-deposition hydrogen plasma treatment affects the RI stability of the deposited SiCN: H film over a six day period. Without post-deposition hydrogen plasma treatment (line 100), an initial decrease in RI was observed over the first 24 hours. However, thereafter, the RI remained stable at about 2.00. However, the use of post-deposition hydrogen plasma treatment further improved the stability of the RI (line 102). Negligible changes in RI were observed over a six day period, with RI maintaining a value of about 2.02-2.03. Without wishing to be bound by any theory or speculation, it is believed that the hydrogen plasma treatment passivates the SiCN: H surface so that moisture absorption is prevented. Post-deposition hydrogen plasma treatment can be used to improve the stability of the SiCN: H film.