TW447077B - Method for improving the characteristics of dielectric layer with a low dielectric constant formed by chemical vapor deposition - Google Patents

Abstract

A method for improving the bonding characteristics between a dielectric layer formed by a chemical vapor deposition with a low dielectric constant and one of a silicon carbide layer or a silicon nitride layer or a silicon-oxy-nitride layer, particularly a carbon-doped dielectric layer with a low dielectric constant formed by a chemical vapor deposition. The method comprises performing a plasma treatment, forming one of a silicon carbide layer or a silicon nitride layer or a silicon-oxy-nitride layer on a substrate. The present invention uses one of N2, Ar and He to be mixed with oxygen molecules and N2O gas for a plasma gas treatment on the dielectric layer to improve the bonding characteristics. Furthermore, when a pure oxygen gas is used for the treatment, the plasma treatment temperature shall be reduced, e.g. 17 DEG C for thereby achieving the effect of increasing the bonding properties.

Description

447 077 V. Description of the invention α) Field of the invention: The present invention relates to a chemical vapor deposition (CVD) low-k dielectric layer (LOW K) treated with a diluted oxygen-containing plasma to improve its formation. The method of film adhesion (adhesi ο η) on it, such as one of the carbonized dream layer or silicon nitride layer, tantalum nitride layer or silicon nitride oxide layer and the above CVD LOW κ material adhesion "Background of the invention: /

In addition to the process of making the integrated circuit of the V chip small, in order to achieve high density and reduce unit costs, the final performance of the component is more critical. In addition to the design of the transistor component itself, the final The dielectric layer between the metal wires and even the interconnects is an important factor that affects the speed performance of the device. This is because the resistance value R of the wire, there will be a capacitor C between the upper and lower wires and adjacent wires, as Those familiar with related technologies know that a lower RC value represents a lower time delay. Therefore, the current copper interconnect process has gradually replaced the aluminum process. In addition, the dielectric layer between interconnects has been changed to a lower level. A dielectric layer with a dielectric constant to reduce parasitic capacitance to increase speed is also the current consensus in the semiconductor industry to handle RC delays. \ Organic spin-on glass (spin on glass; S0G) is known to have low-responsibility-often-fee-of-materials-materials_with-food-gap-fill-fill-energy-force-- . An ittr- Xibu --- such as LOW K material deposited by chemical vapor deposition, such as n-methyl silicon

447 077 V. Description of the Invention (2) (tetramethylsilane) is not widely used in SOG as it has the problem of water absorption, and its dielectric constant is less than 3, only 2.95, so it is widely used in the dual damascene process. Metal interconnect dielectric layer.

However, as shown in FIG. 1, in the dual damascene process, a film layer 20 of about 100 nm in thickness is usually formed in the metal interconnect dielectric layer 30 to stop the etching of the upper wire trench. Layer 2 0 »Among the widely used etch stop layers is a silicon nitride layer or a silicon carbide layer. Regardless of which type, the bonding properties are not good when formed on the above-mentioned CVD LOW K dielectric layer 30. Especially when a chemical / mechanical polishing process is required, it is more obvious that the bad bonding properties are serious. Sex. Based on the above-mentioned problems and the unsatisfactory of traditional solutions, the present invention will provide a new method. For this reason, the traditional method is usually treated with a 02 plasma to improve the bondability between the etch stop layer and the metal interconnect dielectric layer. However, although the conventional technology solves the above bondability problem, it will Impact on the dielectric constant of the metal interconnect dielectric layer. Normally, the dielectric constant will be increased from 2, 95 to 3.1-3.15. In other words, the traditional method sacrifices metal interconnects. The dielectric constant of the electrical layer. In addition, if it is treated at a higher temperature, such as 400C for about 120 seconds, it will often cause excessive oxidation and the bonding will deteriorate. Some problems need to be solved urgently.

Page 5 447077 V. Description of the invention (3) Purpose and summary of the invention: The purpose of the present invention is to provide a low-k dielectric layer with improved chemical vapor deposition and a silicon carbide layer or a silicon nitride layer formed thereon. Or the method of bonding characteristics of one of the nitrogen-silicon oxide layers, and more particularly, the method of the present invention does not increase the dielectric constant of the dielectric layer after processing. Therefore, whether it is a dual damascene process, a copper process, or both, it can effectively improve the resistance value and reduce the problems of peeling or sudden increase in resistance caused by poor bonding.

I The present invention discloses a method for improving the bonding characteristics of a low dielectric constant dielectric layer by chemical vapor deposition, in particular, bonding characteristics with one of a silicon carbide layer, a silicon nitride layer, a silicon nitride oxide layer, or a tantalum nitride. Its improvement. The method of the present invention has a significant improvement effect on a carbon-doped dielectric layer having a low dielectric constant dielectric layer having chemical vapor deposition. For example, one of dimethylsilane, trimethylsilane and tetramethylsilane. First, the dielectric layer is treated with a plasma before forming one of a silicon carbide layer, a silicon nitride layer, or a silicon nitride oxide layer on the substrate. In the present invention, the dielectric layer is treated by using a gas mixture of one of N2, Ar, and He to reduce the oxygen concentration or the N20 concentration as a plasma gas to improve the bonding characteristics. The above mixed gas can be used in a processing environment of 400 ° C. In addition, when treating with pure oxygen gas, it is necessary to lower the temperature of the plasma treatment, for example, around 17 ° C, and the effect of improving the bonding can also be achieved.

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V. Description of the invention (4) Detailed description of the invention: As described in the background of the invention, although the CVD LOW K material can be used to improve the problem of RC delay as a metal interconnector, the layer ^

There are hidden disadvantages to the manufacturing process, such as in the dual-damascene system: blind parts: when the dual-damascene process is carried out, a last name engraving termination layer must be formed in order to avoid over-etching when thinking about the formation of the wire trenches. However: = is a commonly used CVD LOW K metal interconnect dielectric layer, such as carbon-doped dielectric layers such as tetramethy lsi Une, but the second: Shi Xi layer or silicon nitride Layer or silicon nitride oxide layer and other commonly used etch stop layers have poor adhesion. α The inventors have found that, in order to solve the above-mentioned bonding problems, it is necessary to understand the reasons for the poor bonding properties' and the reason why the dielectric constant of the dielectric layer is increased when conventionally treated with a 02 plasma. The curve shown in Fig. 2 is analyzed by Fourier transform far infrared analysis (FT IR) frequency, and the n-methyl silane dielectric layer (such as the 02 plasma treatment or the When processing) Result 'At the wave numbers of 2 950 cm-1, 1 250 cm-1, and 80, there is a peak corresponding to the C-C bond, Si-CH bond, and Si-C bond respectively. After the same dielectric layer was treated with traditional 〇2 plasma treatment, a new hill waveform was added to the FT IR spectrum analysis curve 110, corresponding to the formation of the Si-〇Η bond and another appeared at 1 530 cnr corresponding to The position of 〇0 (carbon-oxygen double bond), meanwhile, the peaks corresponding to C-Η bond, Si-CH bond, and Si-C bond were significantly reduced.

Page 7 447077 Five 'invention description (5) Based on the above facts, the inventor believes that the carbon-oxygen double bond and si-〇 bond produced by the conventional plasmon treatment of CVD L 0 WK metal interconnect dielectric layer may be Causes of dielectric constant rise. The peaks of the bonds corresponding to the C-η bond, the Si-C S bond, and the Si-C bond may be the cause of the deterioration of the bondability—. In other words, the excessively high carbon content in the dielectric layer of the CVD LOW K metal interconnect is the main cause of the deterioration in bonding properties. In addition, the traditional method uses oxygen-containing plasma to generate excessively oxidized carbon-oxygen double bonds in a relatively warm environment. Therefore, in the present invention, the dielectric layer of the cyp LOW K metal interconnect is treated by reducing the oxygen inertia. Taking the first preferred embodiment as an example, Nz / 0 Luo gas is used as the plasma treatment gas. In which, the 〇2 / n crazy amount ratio is controlled to be less than 4 ′ at about 300-400 Ot :, and the RF power is controlled at 5000 to 1,000 watts for processing. In order to prevent excessive oxidation, about 2〇 _60 seconds. Plasma treatment of the dielectric layer according to the method of the present invention, followed by the formation of an etch stop layer material or a barrier layer material, can significantly improve the bondability between the above two layers of materials. The F T I R spectrum analysis curve 12 shown in the figure is the analysis result of the dielectric layer processed by the electric paddle according to the method of the present invention. The peak intensities corresponding to the c_H bond, Si-CH bond, and si-C bond were all significantly reduced. Secondly, the peak corresponding to the Si-0H bond and another peak at 1530 cm-corresponding to c = 0 (carbon-oxygen double bond) have disappeared. Layer or silicon nitride layer or silicon nitride oxide layer has significantly improved the bonding characteristics' more importantly because there is no peak of the si_〇H bond and the other — corresponding to the peak of C = 0 (carbon-oxygen double bond) , The dielectric constant will not increase.

Page 8 447077 V. Description of the invention (6) In addition, the method of the present invention is not only applicable to n-fluorenyl silane, but also other CVD LOW K dielectric layers with carbon doping, such as dimethylsilane Dielectric layers deposited by CVD, such as trimethylsilane, trimethylsilane, etc., are also suitable for β and can be expanded to be used in copper processes, for example. The barrier properties of the barrier layer TaN that is commonly used to isolate copper from CVD LOW κ dielectric layer contact Poor question. In addition to the above examples, N 2/0 mixed gas is used as the plasma processing gas. Other plasma gases can reduce the concentration of Ar / 0 mixed gas, heart / 0 full gas, 1 ^ /] ^ 20 Mixed gas, 41 '/ 1 ^ 0 mixed gas, etc. are all acceptable. The inventors have further found that when treating the gas with pure 02 plasma, it is necessary to avoid using an environment with a commercial temperature such as about 4 0 C. 'In a preferred embodiment, the temperature is below about 3 5 ° C' is between 17 and 3 Low temperature processing below 5 ° C is more ideal. When 〇2 is the main gas and Ar or He is the carrier gas, the concentration of 〇fishing should be reduced, for example, the ratio of 0 and the above-mentioned carrier gas flow rate should be reduced to less than 4 ^ In addition, N 2 0 is the main gas and He or A r is also a good choice when carrying gas. Where t Νβ is the main gas and “or ne is the carrier gas, the concentration of n20 and the ratio of the above-mentioned carrier gas flow rate should be reduced to less than 4. The above is only a preferred embodiment of the present invention and is not intended to Limit the scope of the patent application for the present invention; all other equivalent changes or modifications that do not depart from the ir-4 4 7 0 7 7 disclosed in the present invention (7) should be included in the following applications Within the scope of the patent.

liiB Page 10 447077 Brief description of the drawings The preferred embodiment of the present invention will be described in more detail in the following explanatory text with the following figures: Figure 1 is a schematic cross-sectional view of a semiconductor structure in a dual damascene process. Figure 2 shows the frequency spectrum of the three cases of n-methylsilane deposited by chemical vapor deposition using FT IR spectrum analysis, untreated, treated with pure oxygen plasma treatment at 400 ° C, and plasma treated with reduced oxygen concentration. Comparison of analysis results.

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Claims (1)

447077 6. Scope of patent application 1. A plasma treatment method for reducing oxygen concentration to improve the bonding characteristics of one of a low-k dielectric layer and one of a silicon carbide layer or a silicon nitride layer or a silicon nitride oxide layer or a tantalum nitride The method includes at least the following steps: providing a substrate of the low-dielectric-constant dielectric layer, the low-dielectric-constant dielectric layer having carbon doping; and processing the mixed plasma gas with a carrier gas to reduce the oxygen concentration The substrate; and forming a carbonized stone layer or a gasified stone layer or a nitrogen oxide layer, one of which is on the substrate. 2. The method according to item 1 of the scope of patent application, wherein the substrate of the above-mentioned low-k dielectric layer comprises at least a chemical vapor deposition method. 3. The method according to item 1 of the scope of patent application, wherein the substrate of the above-mentioned low-k dielectric layer comprises at least dimethylsilane, trimethylsilane, and n-methyllithium One kind of tetramethylsilane. 4. The method according to item 1 of the scope of patent application, wherein the above-mentioned carrier gas includes at least one of N 2, Ar and He. 5. The method as described in item 4 of the scope of the patent application, in which one of the above-mentioned N 2, Ar, and He is used as a carrier gas to reduce the concentration of 0, the flow ratio of the amount of 0 crazy and any of the above-mentioned carrier gas should be Controlled at less than 4. Page 12 447077 6. Application scope 6. The method as described in item 5 of the scope of patent application, in which the above-mentioned mixed gas plasma is plasma treated at 300 to 400 ° C, and the time is about 2 0 to 60 seconds 0 7. The method as described in item 1 of the scope of patent application, wherein the above-mentioned 0 ammonia body further includes N 20 instead. 8. The method according to item 5 or item 7 of the scope of patent application, wherein the flow rate ratio of the above-mentioned N 20 and the above-mentioned carrier gas is about 0.2 to 4. 9. The method described in item 1 of the scope of patent application, further comprising replacing the above-mentioned mixed plasma gas with high-purity oxygen, and performing plasma treatment at a temperature of 17 to 35 ° C or lower. 10. A method for improving a bonding characteristic method of a chemical vapor deposition low-k dielectric layer and one of a silicon carbide layer, a silicon nitride layer, or a silicon nitride oxide layer. The method includes at least the following steps: providing The dielectric layer is a substrate of an upper surface layer, and the dielectric layer has carbon doping; the substrate is treated with a mixed gas plasma with reduced oxygen concentration, wherein the mixed gas system is selected from the group consisting of N2 / 0 Niehe gas One or more of the group consisting of Ar, O / Nie gas, He / O couple gas, He / & 20 mixed gas, Ar / N20 mixed gas, and N 2 / N 20 mixed gas 0 0 447077 VI. Apply for patent Fanyuan _ to 40 (TC processing or pure oxygen electricity., Forming a silicon carbide or nitriding continuous layer $ < 3 5 C or less for processing; and on the substrate. Layer or nitrogen crushing One of the oxide layers is as described in Section 1. 10 of the scope of patent application. The substrate of the dielectric constant dielectric layer is a carbon doped method, in which the above-mentioned low dielectric W 雊 dielectric layer is used. 1 2. Such as The method of Gans described in the scope of the patent application No. 11 is to make the substrate of the above-mentioned low dielectric constant dielectric layer contain at least dimethylsilane, dimethyl sulfonate (chirime) Seven hy 1 si 1 ane) and tetramethylsilane. 13. The method as described in item 10 of the scope of patent application, wherein the above-mentioned n A r and He gas systems are used to reduce. Concentration or the concentration of N 20. 1 4. According to the method described in item 10 of the scope of patent application 'where the above time' 0, the flow ratio of any one of the paralysis volume and the above-mentioned gas with a reduced concentration of 0 should be controlled to less than 4 . 1 5. If the scope of patent application is the first! The method according to item 4, wherein the above-mentioned mixed gas plasma is electropolymerized at 300 to 400 ° C, and the time is about 20 to 60 seconds. 1 6. The method according to item 丨 0 of the patent application scope, wherein the above N 447077 VI. Scope of patent application The flow ratio of any one of the gas and the above-mentioned gas with a reduced N 20 concentration should be controlled to less than 4. 17. The method as described in item 10 of the scope of patent application, further comprising replacing the above-mentioned mixed plasma gas with high-purity oxygen, and performing plasma treatment at a temperature of 17 to 35 ° C or lower. Page 15