CN102002666B - Preparation method of tantalum nitride diffusion impervious layer for copper interconnection - Google Patents

Abstract

The invention relates to a preparation method of a tantalum nitride diffusion impervious layer for copper interconnection, relating to a preparation method of the tantalum nitride diffusion impervious layer and solving the problems of poor impervious effect of tantalum nitride diffusion impervious layer, which is caused by large thickness and poor compactness of the tantalum nitride diffusion impervious layer prepared by the traditional tantalum nitride deposition technology. The preparation method comprises the following steps of: cleaning a substrate, and then placing the cleaned substrate on a sample platform inside a vacuum cavity of filtering cathode arc deposition equipment; then carrying out ion cleaning on the substrate; vacuumizing, heating the sample platform, introducing nitrogen, then importing scanning waveforms, and setting deposition parameters; and then starting the filtering cathode arc deposition equipment. The tantalum nitride diffusion impervious layer for the copper interconnection has the thickness of 10-20 nm, good compactness and uniform and smooth surface and can ensure the excellent quality of a subsequent electrodeposition copper layer; and in addition, the tantalum nitride diffusion impervious layer has high high-temperature diffusion imperviousness and does not generate copper-silicon compounds after being subjected to heat treatment at the temperature of 600 DEG C for 90 minutes.

Description

A preparation method of tantalum nitride diffusion barrier layer for copper interconnection

technical field

The invention relates to a preparation method of a tantalum nitride diffusion barrier layer.

Background technique

With the development of integrated circuit technology, Cu has replaced Al to become a new generation of interconnect materials. In order to prevent Cu from diffusing into Si devices and cause damage to device performance and to improve the adhesion of Cu to Si and SiO ₂ , a diffusion barrier layer must be wrapped around Cu interconnects. Tantalum nitride has very good barrier material properties, such as low resistivity, high melting point, high activation energy for lattice and grain boundary diffusion, and a series of excellent properties such as stable interface. It is the preferred material for the current diffusion barrier. When the characteristic size of the integrated circuit is less than 45nm, the performance requirements for the thickness of the barrier film and the barrier effect are further improved. The thickness of the barrier layer should be less than 3.3nm, and the aspect ratio of the circuit trench increases. Ensure that the prepared tantalum nitride barrier layer still has good diffusion barrier performance and step coverage. The existing deposition techniques are mainly magnetron sputtering, vacuum evaporation, etc., and the thickness of the prepared tantalum nitride barrier layer is too large (greater than 100nm), the barrier layer has poor density, resulting in poor barrier effect.

Contents of the invention

The purpose of the present invention is to solve the problem that the tantalum nitride barrier layer prepared by the existing tantalum nitride deposition technology has a large thickness and poor compactness, which leads to poor barrier effect of the tantalum nitride barrier layer, and provides a tantalum nitride barrier layer for copper interconnection. A method for preparing a tantalum diffusion barrier layer.

The preparation method of the tantalum nitride diffusion barrier layer for copper interconnection of the present invention is realized through the following steps: 1. The single crystal silicon substrate is cleaned with ultrasonic waves for 30-40 minutes, and then the single crystal silicon substrate is placed in the filter cathodic arc On the sample stage in the vacuum chamber of the deposition equipment; 2. After the vacuum chamber is evacuated to 1.0×10 ^-6 ~ 9.9×10 ^-6 Torr, argon gas is introduced, and the flow rate of the argon gas is controlled to be 50cm ³ /min. When the pressure reaches 8.0×10 ^-5 to 1.0×10 ^-4 Torr, turn the sample stage to the ion cleaning position, perform ion cleaning on the surface of the single crystal silicon substrate for 10 to 20 minutes, then turn off the argon gas, and then turn the sample stage to the Deposition position; 3. Continue to evacuate the vacuum chamber. When the vacuum degree reaches 1.0×10 ^-6 ~9.9×10 ^-6 Torr, then heat the sample stage to 200~600°C, and then pass in nitrogen, and the flow of nitrogen gas is controlled At 2.6-8.8cm ³ /min, then call in the scanning waveform, set the deposition parameters as follows: arc current 120-150A, scanning time 10min, arcing cycle 10-15s/time, substrate DC bias 20- 200V; 4. When the vacuum degree in the vacuum chamber is 4.0×10 ^-4 ~ 7.0×10 ^-4 Torr, turn on the filtered cathodic arc deposition equipment, start to apply pulse power to the tantalum target to start the arc, and then use the flat characteristic power to stabilize the arc. A coating is deposited on the surface of the single crystal silicon substrate, and a tantalum nitride diffusion barrier layer is obtained on the surface of the single crystal silicon substrate after the deposition, so as to realize the preparation of the tantalum nitride diffusion barrier layer for copper interconnection.

The preparation method of the tantalum nitride diffusion barrier layer for copper interconnection of the present invention uses the filtered cathode vacuum arc technology to obtain a tantalum nitride diffusion barrier layer with a thickness of only 10-20 nm on a single crystal silicon substrate, and the prepared tantalum nitride The diffusion barrier layer has good compactness and uniform surface, which can ensure the excellent quality of the subsequent electrodeposited copper layer; at the same time, the high-temperature diffusion barrier property is high, and the tantalum nitride diffusion barrier layer is heat-treated at 600°C for 90 minutes, and there is no copper-silicon compound produce.

The preparation method of the tantalum nitride diffusion barrier layer for copper interconnection of the present invention has simple process, short preparation period and is suitable for industrial application. The preparation method of the invention can realize the requirement that the aspect ratio is at least 9:1, and can meet the performance requirement of the current semiconductor industry.

Description of drawings

Fig. 1 is the grazing incidence X-ray diffraction (GIXRD) test spectrum of the sample after the heat treatment in the specific embodiment thirteen, in which "■" is the (111) crystal orientation cubic phase TaN, and "□" is the (200) crystal orientation Cubic phase TaN, "◆" is (111) crystal orientation cubic phase Cu, "◇" is (200) crystal orientation cubic phase Cu, "▲" is (220) crystal orientation cubic phase TaN, "△" is (220) Crystalline cubic phase Cu.

Detailed ways

The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

Specific Embodiment 1: This embodiment is a method for preparing a tantalum nitride diffusion barrier layer for copper interconnection, which is realized through the following steps: 1. Clean the single crystal silicon substrate with ultrasonic waves for 30 to 40 minutes, and then clean the single crystal silicon substrate The bottom is placed on the sample stage in the vacuum chamber of the filtered cathodic arc deposition equipment; 2. After the vacuum chamber is evacuated to 1.0×10 ^-6 ~ 9.9×10 ^-6 Torr, argon gas is introduced, and the flow rate of argon gas is controlled to 50cm ³ /min, when the pressure in the vacuum chamber reaches 8.0×10 ^-5 ~1.0×10 ^-4 Torr, turn the sample stage to the ion cleaning position, perform ion cleaning on the surface of the single crystal silicon substrate for 10 to 20 minutes, then turn off the argon gas, Then turn the sample stage to the deposition position; 3. Continue to evacuate the vacuum chamber. When the vacuum degree reaches 1.0×10 ^-6 ~9.9×10 ^-6 Torr, heat the sample stage to 200~600°C, and then turn on the Inject nitrogen, control the flow rate of nitrogen at 2.6-8.8cm ³ /min, then adjust the scanning waveform, set the deposition parameters as follows: arc current 120-150A, scanning time 10min, arcing frequency 10-15s/time, substrate The DC bias voltage is 20-200V; 4. When the vacuum degree in the vacuum chamber is 4.0×10 ^-4 ～7.0×10 ^-4 Torr, turn on the filtered cathodic arc deposition equipment, start to apply pulse power to the tantalum target to start the arc, and then use The flat characteristic power supply stabilizes the arc, deposits a coating film on the surface of the single crystal silicon substrate, and obtains a tantalum nitride diffusion barrier layer on the surface of the single crystal silicon substrate after the deposition, and realizes the preparation of a tantalum nitride diffusion barrier layer for copper interconnection.

The purpose of ultrasonic cleaning in Step 1 of this embodiment is to remove pollutants on the surface of the single crystal silicon substrate, such as oil stains and dust.

In this embodiment, a tantalum nitride diffusion barrier layer with a thickness of only 10-20nm is obtained on a single crystal silicon substrate, and the prepared tantalum nitride diffusion barrier layer has good compactness and a uniform and smooth surface, which can ensure the subsequent electrodeposited copper layer Excellent quality; at the same time, the high-temperature diffusion barrier is high, and the tantalum nitride diffusion barrier layer is heat-treated at a temperature of 600 ° C for 90 minutes, and no copper-silicon compound is produced.

The preparation method of the tantalum nitride diffusion barrier layer for copper interconnection in this embodiment has a simple process and a short preparation period, and is suitable for industrial application. The preparation method of the invention can realize the requirement that the aspect ratio is at least 9:1, and can meet the performance requirement of the current semiconductor industry.

Specific embodiment 2: The difference between this embodiment and specific embodiment 1 is that in step 2, the vacuum chamber is evacuated to 3.0×10 ^-6 ~ 8×10 ^-6 Torr, and then argon gas is introduced, and the flow rate of argon gas is controlled to 50 cm ³ /min, when the pressure in the vacuum chamber reaches 8.5×10 ^-5 to 9.5×10 ^-5 Torr, turn the sample stage to the ion cleaning position. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 3: The difference between this embodiment and Embodiment 1 is that in step 2, the vacuum chamber is evacuated to 6.0×10 ^-6 Torr, and then argon gas is introduced, and the flow rate of argon gas is controlled to be 50 cm ³ /min. When the vacuum chamber When the internal pressure reaches 9×10 ^-5 Torr, turn the sample stage to the ion cleaning position. Other steps and parameters are the same as those in Embodiment 1.

Embodiment 4: The difference between this embodiment and Embodiment 1, 2 or 3 is that in step 3, when the degree of vacuum reaches 3.0×10 ^-6 to 8×10 ^-6 Torr, the sample stage is heated to 300 to 500 ℃. Other steps and parameters are the same as those in Embodiment 1, 2 or 3.

Embodiment 5: This embodiment is different from Embodiment 1, 2 or 3 in that in step 3, when the degree of vacuum reaches 6×10 ^-6 Torr, the sample stage is heated to 400°C. Other steps and parameters are the same as those in Embodiment 1, 2 or 3.

Embodiment 6: This embodiment is different from Embodiment 1 to Embodiment 5 in that the nitrogen flow rate in step 3 is controlled at 3-8 cm ³ /min. Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Embodiment 7: The difference between this embodiment and one of Embodiments 1 to 5 is that the nitrogen flow rate in step 3 is controlled at 4-6 cm ³ /min. Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Embodiment 8: The difference between this embodiment and one of Embodiments 1 to 5 is that the nitrogen flow rate in step 3 is controlled at 5 cm ³ /min. Other steps and parameters are the same as one of the specific embodiments 1 to 5.

Embodiment 9: The difference between this embodiment and Embodiments 1 to 8 is that the deposition parameters are set in step 3: the arc current is 125-145A, the scanning time is 10min, the arcing frequency is 11-14s/time, and the lining The bottom DC bias voltage is 80-150V. Other steps and parameters are the same as those in Embodiments 1 to 8.

Embodiment 10: This embodiment differs from Embodiment 1 to Embodiment 8 in that the deposition parameters are set in step 3: the arc current is 135A, the scanning duration is 10min, the arcing frequency is 12s/time, and the substrate DC bias is 120V. Other steps and parameters are the same as those in Embodiments 1 to 8.

Embodiment 11: This embodiment differs from Embodiments 1 to 11 in that in step 4, when the vacuum degree in the vacuum chamber is 4.8×10 ^-4 to 62×10 ^-4 Torr, the filtered cathodic arc deposition equipment is turned on. Other steps and parameters are the same as those in Embodiments 1 to 11.

Embodiment 12: This embodiment differs from Embodiments 1 to 10 in that in Step 4, when the vacuum degree in the vacuum chamber is 5.6×10 ⁻⁴ Torr, the filtering cathodic arc deposition equipment is turned on. Other steps and parameters are the same as those in Embodiments 1 to 11.

Specific Embodiment Thirteen: This embodiment is a method for preparing a tantalum nitride diffusion barrier layer for copper interconnection, which is achieved through the following steps: 1. Clean the single crystal silicon substrate with ultrasonic waves for 30 minutes, and then clean the single crystal silicon substrate Place it on the sample stage in the vacuum chamber of the filtered cathodic arc deposition equipment; 2. After the vacuum chamber is evacuated to 6×10 ^-6 Torr, argon gas is introduced, and the flow rate of the argon gas is controlled to be 50cm ³ /min. When the pressure in the vacuum chamber is When it reaches 9.0×10 ^-5 Torr, turn the sample stage to the ion cleaning position, perform ion cleaning on the surface of the single crystal silicon substrate for 20 minutes, then turn off the argon gas, and then turn the sample stage to the deposition position; 3. Continue to clean the vacuum chamber Carry out vacuuming, and when the vacuum degree reaches 6×10 ^-6 Torr, heat the sample stage to 400°C, then pass in nitrogen gas, the flow rate of nitrogen gas is controlled at 5cm ³ /min, then adjust the scanning waveform, and set the deposition parameters as follows: The arc current is 135A, the scanning time is 10min, the arcing frequency is 12s/time, and the substrate DC bias voltage is 120V; 4. When the vacuum degree in the vacuum chamber is 5.6×10 ^-4 Torr, turn on the filtered cathodic arc deposition equipment and start Apply a pulse power supply characteristic to the tantalum target to start the arc, and then use a flat characteristic power supply to stabilize the arc, deposit a coating on the surface of the single crystal silicon substrate, and obtain a tantalum nitride diffusion barrier layer on the surface of the single crystal silicon substrate after the deposition is completed to realize copper interconnection Fabrication of Diffusion Barriers Using TaN.

In this embodiment, the thickness of the tantalum nitride diffusion barrier layer prepared by depositing on the surface of single crystal silicon is only 15nm, and the prepared tantalum nitride diffusion barrier layer has good compactness and uniform surface, which can ensure the excellent quality of the subsequent electrodeposited copper layer. Quality; at the same time, the high-temperature diffusion barrier is high, and the tantalum nitride diffusion barrier layer is heat-treated at a temperature of 600 ° C for 90 minutes, and no copper-silicon compound is produced.

In this embodiment, the single crystal silicon deposited with a tantalum nitride diffusion barrier layer is then plated with copper, so that a layer of copper film is formed on the tantalum nitride diffusion barrier layer to obtain a sample, and then the sample is heat-treated at 600°C After 90 minutes, then adopt the X'Pert-Pro type X-ray diffractometer produced by Netherlands Philips company to carry out grazing incidence X-ray diffraction (GIXRD) test to the sample after heat treatment, test result is as shown in Figure 1, among the figure " ■" "□" is (200) cubic phase TaN, "◆" is (111) cubic phase Cu, "◇" is (200) cubic phase Cu, " ▲" is (220) cubic phase TaN, and "△" is (220) cubic phase Cu. It can be seen from FIG. 1 that after the tantalum nitride diffusion barrier layer obtained on the surface of the single crystal silicon substrate in this embodiment is subjected to heat treatment at a temperature of 600° C. for 90 minutes, no copper-silicon compound is produced and the diffusion barrier performance is good.

Claims (10)

1. interconnected preparation method of copper with the tantalum-nitride diffusion barrier layer; It is characterized in that the interconnected preparation method with the tantalum-nitride diffusion barrier layer of copper realizes through following steps: one, with monocrystalline substrate with ultrasonic cleaning 30～40min, then monocrystalline substrate is placed on the sample table in the filtering cathode arc deposited equipment vacuum storehouse; Two, with being evacuated to 1.0 * 10 in the vacuum storehouse ^-6～9.9 * 10 ^-6Feed argon gas behind the Torr, the control argon flow amount is 50cm ³/ min, pressure reaches 8.0 * 10 in the hole capital after selling all securities of taking seriously ^-5～1.0 * 10 ^-4During Torr, sample table is gone to the ion cleaning positions, ion is carried out on the monocrystalline substrate surface clean 10～20min, close argon gas then, again sample table is gone to deposition position; Three, continue the vacuum storehouse is vacuumized, when vacuum tightness reaches 1.0 * 10 ^-6～9.9 * 10 ^-6During Torr, again sample table is heated to 200～600 ℃, feeds nitrogen then, nitrogen flow is controlled at 2.6～8.8cm ³/ min calls in sweep waveform then, deposition parameter is set be: flame current is 120～150A, and the scanning duration is 10min, and the starting the arc cycle is 10～15s/ time, and the substrate DC biasing is 20～200V; Four, the interior vacuum tightness of hole capital after selling all securities is 4.0 * 10 surely ^-4～7.0 * 10 ^-4During Torr; Open filtering cathode arc deposited equipment; Begin the tantalum target is applied the starting the arc of pulse power characteristic, adopt flat characteristic power supply stabilising arc then, to monocrystalline substrate surface deposition plated film; Deposition promptly obtains the tantalum-nitride diffusion barrier layer on the monocrystalline substrate surface after finishing, and realizes the interconnected preparation with the tantalum-nitride diffusion barrier layer of copper.

2. the interconnected preparation method with the tantalum-nitride diffusion barrier layer of a kind of copper according to claim 1 is characterized in that working as in the step 3 vacuum tightness and reaches 3.0 * 10 ^-6～8 * 10 ^-6During Torr, again sample table is heated to 300～500 ℃.

3. the interconnected preparation method with the tantalum-nitride diffusion barrier layer of a kind of copper according to claim 1 is characterized in that working as in the step 3 vacuum tightness and reaches 6 * 10 ^-6During Torr, again sample table is heated to 400 ℃.

4. according to claim 1, the interconnected preparation method of 2 or 3 described a kind of copper, it is characterized in that nitrogen flow is controlled at 3～8cm in the step 3 with the tantalum-nitride diffusion barrier layer ³/ min.

5. according to claim 1, the interconnected preparation method of 2 or 3 described a kind of copper, it is characterized in that nitrogen flow is controlled at 4～6cm in the step 3 with the tantalum-nitride diffusion barrier layer ³/ min.

6. according to claim 1, the interconnected preparation method of 2 or 3 described a kind of copper, it is characterized in that nitrogen flow is controlled at 5cm in the step 3 with the tantalum-nitride diffusion barrier layer ³/ min.

7. according to claim 1, the interconnected preparation method of 2 or 3 described a kind of copper with the tantalum-nitride diffusion barrier layer; It is characterized in that being provided with in the step 3 deposition parameter is: flame current is 125～145A; The scanning duration is 10min; The starting the arc cycle is 11～14s/ time, and the substrate DC biasing is 80～150V.

8. according to claim 1, the interconnected preparation method of 2 or 3 described a kind of copper with the tantalum-nitride diffusion barrier layer; It is characterized in that being provided with in the step 3 deposition parameter is: flame current is 135A; The scanning duration is 10min, and the starting the arc cycle is 12s/ time, and the substrate DC biasing is 120V.

9. according to claim 1, the interconnected preparation method with the tantalum-nitride diffusion barrier layer of 2 or 3 described a kind of copper, vacuum tightness is 4.8 * 10 in the hole capital after selling all securities that it is characterized in that taking seriously in the step 4 ^-4～6.2 * 10 ^-4During Torr, open filtering cathode arc deposited equipment.

10. according to claim 1, the interconnected preparation method with the tantalum-nitride diffusion barrier layer of 2 or 3 described a kind of copper, vacuum tightness is 5.6 * 10 in the hole capital after selling all securities that it is characterized in that taking seriously in the step 4 ^-4During Torr, open filtering cathode arc deposited equipment.

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