A particle control method for PVD carbon film equipment

Abstract

The present invention provides a particle control method for a PVD carbon film device, comprising the following steps: step S1, sputtering a carbon film on a substrate; step S2, forming a silicon carbide passivation layer on the surface of a target material; step S3, reacting carbon film particles with oxygen and being removed; step S4, restoring the surface state of the target material to an initial state; step S5, repeating steps S1-S4. After the present invention forms a carbon film on a substrate by sputtering, a silicon carbide passivation layer is formed on the surface of the target material, so that when oxygen reacts with carbon particles in a plasma, the carbon target itself will not react and be consumed, which can effectively reduce the consumption of the target surface. If there is no passivation layer, the subsequent introduction of oxygen to react with carbon particles will also cause the target surface to be consumed. The particle control method of the present invention can significantly reduce the carbon particles gradually accumulated in the vacuum chamber during the sputtering of the carbon film.

Description

Technical Field

[0001] The present invention relates to a particle control method, in particular to a particle control method for PVD carbon film equipment. Background Art

[0002] In the SiC device process, due to the low diffusion coefficient of impurities, ion implantation technology is the key process for achieving doping. In order to activate the implanted doping and eliminate the damage defects caused by the implantation process, SiC needs to be activated and annealed at high temperature. For SiC lattices with high bonding energy, annealing at a high temperature of more than 1600°C is required to obtain a certain degree of electrical activation. However, at such a high activation annealing temperature, Si is easily sublimated from the SiC surface and redeposited on the surface of the wafer in the form of Si, Si2C, SiC2, etc., forming step clusters, resulting in increased surface roughness. In order to protect the surface during high-temperature annealing, the surface needs to be protected before annealing, such as by covering the surface with a layer of carbon film. Studies have found that carbon films can successfully suppress the degree of surface roughness.

[0003] Physical vapor deposition (PVD) is an important method for preparing carbon films, with magnetron sputtering being the most commonly used. While PVD offers advantages in rapid film formation and excellent adhesion, it also suffers from poor particle size. After multiple sputterings, carbon particles gradually accumulate within the vacuum sputtering atmosphere, significantly increasing the surface roughness of the SiC wafer during subsequent high-temperature annealing, severely impacting device performance.

[0004] In the prior art, in order to improve the stability of particles in the PVD equipment cavity, Chinese patent application number CN201910937932.1 discloses a device for improving the stability of particles in the reaction chamber of a PVD equipment. By installing a fan outside the PVD equipment reaction chamber and a fan control system, temperature data information from different parts of the bell-shaped cover body is transmitted to a controller. The controller analyzes and processes the temperature data information and then adjusts the fan speed in real time to adjust the fan's heat dissipation effect on the bell-shaped cover body. Although the performance of particles in the cavity environment can be improved by maintaining the temperature in the cavity at an ideal temperature, this method of controlling the cavity temperature can only prevent residual particles from adhering to the cover without being affected by temperature, resulting in poor adhesion, and cannot fundamentally reduce the number and size of particles. Summary of the Invention

[0005] The present invention aims to overcome the shortcomings of the prior art by providing a particle control method for PVD carbon film equipment. This method significantly reduces the accumulation of carbon particles within the vacuum chamber during carbon film sputtering. The preparation of a target surface passivation layer effectively reduces target surface consumption. Without the passivation layer, the introduction of oxygen in subsequent steps would also cause target surface consumption.

[0006] To achieve the above technical objectives, the technical solution adopted in the embodiment of the present invention is: a particle control method for a PVD carbon film device, comprising the following steps:

[0007] Step S1, sputtering carbon film: transferring the substrate to a carrier in a vacuum sputtering chamber, forming a carbon film on the substrate using a DC magnetron sputtering target, and then removing the substrate from the vacuum sputtering chamber;

[0008] Step S2, forming a silicon carbide passivation layer: transferring a non-doped pure silicon wafer to the carrier, applying radio frequency power P0 of a certain frequency to the carrier, gradually etching out silicon wafer atoms, and simultaneously inputting DC power P1 to the target material, so that silicon atoms combine with carbon atoms sputtered by DC. The sputtering time is recorded as t1. After the sputtering is completed, a silicon carbide passivation layer is formed on the surface of the target material;

[0009] Step S3: The carbon film particles react with oxygen and are removed: the radio frequency power and frequency applied to the carrier remain unchanged, oxygen is introduced to fully react with the carbon particles in the cavity to form carbon dioxide gas, which is then pumped away;

[0010] Step S4, restoring the target surface state: inputting an asymmetric bipolar pulse power P2 to the target, with P2 ≥ P1 and sputtering time t2 = t1, to remove the passivation layer on the target surface, and the target state is restored to the initial state;

[0011] Step S5: Repeat steps S1-S4.

[0012] Furthermore, in step S1, the target material is a carbon target with a diameter of 320-321 mm, and the distance between the target material and the carrier is 40-60 mm.

[0013] Furthermore, in step S1, the target material is pre-sputtered for 1-3 minutes, the substrate temperature is set to 25-200°C during the pre-sputtering, and the vacuum degree of the vacuum sputtering chamber is maintained at 1.0×10 -8 -5.0×10 -8 Torr, sputtering power is 500-1000W;

[0014] Then, argon gas with a flow rate of 15-30 sccm is introduced into the vacuum sputtering chamber until the pressure of the vacuum sputtering chamber is 1.0-2.1 mTorr, and the target material is sputtered for 6-10 minutes at a sputtering power of 1000-3000W.

[0015] Furthermore, in step S2, the undoped pure silicon wafer is transferred to the carrier, argon gas with a flow rate of 30-60 sccm is introduced, the cavity reaction pressure is 2.2-4.4 mTorr, RF power of 2-27.12 MHz is applied to the carrier, power P0=100-1000 W, and DC power P1=50-200 W is input to the target material at the same time, and time t1 is maintained for 10-30 s.

[0016] Furthermore, in step S3, a radio frequency power of 2-27.12 MHz is applied to the carrier, the power P0 = 100-1000 W, the input power of the target material is zero, and oxygen with a flow rate of 80-100 sccm is introduced into the vacuum chamber. The opening of the pump plug valve is adjusted to 50%-80%, the chamber pressure is 20-40 mTorr, and the reaction time is 5-10 min, so that the oxygen fully reacts with the carbon particles in the chamber to form carbon dioxide gas and is pumped away by the pump.

[0017] Furthermore, in step S4, argon gas is introduced at a flow rate of 30-60 sccm, the reaction pressure of the vacuum chamber is 2.2-4.4 mTorr, an asymmetric bipolar pulse with a power P2=50-200 W is input to the target material, the pulse frequency is 100-350 kHz, the duty cycle is 50-60%, and the pulse sputtering time t2 is 10-30 s.

[0018] The technical solution provided by the embodiment of the present invention has the following beneficial effects:

[0019] After sputtering a carbon film onto a substrate, the present invention forms a silicon carbide passivation layer on the target surface. This prevents the carbon target from reacting and being consumed when oxygen reacts with carbon particles in the plasma, effectively reducing target surface consumption. Without the passivation layer, subsequent oxygen flow and carbon particle reaction would also cause target surface consumption. The particle control method of the present invention can significantly reduce the accumulation of carbon particles within the vacuum chamber during sputtering of the carbon film. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] Example 1

[0022] A particle control method for a PVD carbon film device comprises the following steps:

[0023] Step S1, sputtering carbon film: Based on SJI-SEMI's Depomerits P188 Pro PVD equipment, a carbon target with a purity of 99.998% was selected, the target diameter was 320 mm, and the distance between the target and the wafer stage was 50 mm;

[0024] First, the wafer temperature was set to 25°C and the chamber background vacuum was maintained at 1.0×10 -8 Torr, using a sputtering power of 500 W and pre-sputtering the target for 3 min;

[0025] Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, argon gas was introduced at a flow rate of 15 sccm, the chamber reaction pressure was 1.1 mTorr, the target input power was 1500 W, the sputtering time was 8 minutes, and after the carbon film was obtained, the wafer was transferred out of the vacuum chamber.

[0026] Step S2, forming a silicon carbide passivation layer: transfer a non-doped pure silicon wafer to the carrier, introduce argon gas with a flow rate of 30 sccm, and the chamber reaction pressure is 2.2 mTorr. Apply RF power with a frequency of 13.56 MHz and a power of 500 W to the carrier. At the same time, a DC current of 100 W is input to the target material for 30 seconds. The silicon atoms combine with the carbon atoms on the target surface to form a silicon carbide passivation layer on the target surface.

[0027] Step S3, reaction of carbon film particles with oxygen: the RF power and frequency applied to the carrier remain the same as in step S2, the input power of the target material is zero, and oxygen at a flow rate of 90 sccm is introduced into the vacuum chamber. The opening of the pump plug valve is adjusted to 50%, the chamber pressure is 40 mTorr, and the reaction time is maintained at 10 minutes, so that the oxygen can fully react with the carbon particles in the chamber to form carbon dioxide gas, which is then pumped away.

[0028] Step S4, restore the surface state of the target material: introduce argon gas with a flow rate of 30 sccm, the chamber reaction pressure is 2.2 mTorr, the asymmetric bipolar pulse power input to the carbon target is 200 W, the pulse frequency is 250 kHz, the duty cycle is 50%, and the pulse sputtering time is 30 s. After sputtering is completed, the target material state is restored to the initial state.

[0029] Step S5: Repeat steps S1-S4.

[0030] After steps S1 to S4 were cycled 100 times, a KLA plus 501 rl particle analyzer was used to detect the number of particles on the wafer surface after the wafer was transferred out of the vacuum chamber in step S1. The number of particles of different sizes is shown in Table 1.

[0031] When the carbon target is fully utilized at 500kW·h, the maximum sputtering depth of the target surface is scanned using the Jiangfeng Electronics CMM three-dimensional coordinate measuring instrument, recorded as L1, and the measured L1 is 6.02mm.

[0032] Comparative Example 1

[0033] A particle control method for a PVD carbon film device comprises the following steps:

[0034] Step S1, sputtering carbon film: Based on SJI-SEMI's Depomerits P188 Pro PVD equipment, a carbon target with a purity of 99.998% was selected, the target diameter was 320 mm, and the distance between the target and the wafer stage was 50 mm;

[0035] First, the wafer temperature was set to 25°C and the chamber background vacuum was maintained at 1.0×10 -8 Torr, using a sputtering power of 500 W and pre-sputtering the target for 3 min;

[0036] Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, argon gas was introduced at a flow rate of 15 sccm, the chamber reaction pressure was 1.1 mTorr, the target input power was 1500 W, the sputtering time was 8 minutes, and after the carbon film was obtained, the wafer was transferred out of the vacuum chamber.

[0037] Step S2, reaction of carbon film particles with oxygen: apply RF power of 13.56 MHz and 500 W to the carrier, the input power of the target material is zero, and oxygen with a flow rate of 90 sccm is introduced into the vacuum chamber. The opening of the pump plug valve is adjusted to 50%, the chamber pressure is 40 mTorr, and the reaction time is maintained for 10 minutes, so that the oxygen can fully react with the carbon particles in the chamber to form carbon dioxide gas, which is then pumped away by the pump.

[0038] Step S3: repeat steps S1-S2.

[0039] After steps S1 and S2 were cycled 100 times, a KLA plus 501 rl particle analyzer was used to detect the number of particles on the wafer surface after it was transferred out of the vacuum chamber in step S1. The number of particles of different sizes is shown in Table 1.

[0040] When the carbon target is fully utilized at 500kW·h, the maximum sputtering depth of the target surface is scanned using the Jiangfeng Electronics CMM three-dimensional coordinate measuring instrument, recorded as L1, and the measured L1 is 5.09mm.

[0041] Comparative Example 2

[0042] A particle control method for a PVD carbon film device comprises the following steps:

[0043] Step S1, sputtering carbon film: Based on SJI-SEMI's Depomerits P188 Pro PVD equipment, a carbon target with a purity of 99.998% was selected, the target diameter was 320 mm, and the distance between the target and the wafer stage was 50 mm;

[0044] First, the substrate temperature was set to 25°C and the background vacuum of the chamber was maintained at 1.0×10 -8 Torr, using a sputtering power of 500 W and pre-sputtering the target for 3 minutes;

[0045] Next, the wafer was transferred to a DC magnetron sputtering vacuum chamber, the argon flow rate was 15 sccm, the chamber reaction pressure was 1.1 mTorr, the target input power was 1500 W, the sputtering time was 8 minutes, and after the carbon film was obtained, the wafer was transferred out of the vacuum chamber.

[0046] Step S2: Repeat step S1.

[0047] After step S1 was cycled 100 times, a KLA plus 501 rl particle analyzer was used to detect the number of particles on the surface after being transferred out of the vacuum chamber in step S1. The number of particles of different sizes is shown in Table 1.

[0048] Table 1 Number of surface particles on the 101st wafer after coating

[0049]

[0050] As shown in Table 1, the total number of particles with a size greater than 3 μm on the wafer surface after 100 coating cycles in Example 1 and Comparative Example 1 was 15 and 25, respectively, significantly lower than the 304 in Comparative Example 2. The total number of particles with a size ≤ 3 μm on the wafer surface after 100 coating cycles in Example 1 and Comparative Example 1 was 25 and 628, respectively, significantly lower than the 1799 in Comparative Example 2. This indicates that in step S2 of the embodiment, the carbon particles can be removed by reacting oxygen with oxygen in the plasma. That is, after a complete coating and particle removal process, the number of carbon particles of different sizes in the cavity is greatly reduced.

[0051] Table 2 Target surface conditions after carbon target sputtering at 500kW·h

[0052]

[0053] According to Table 2, the total thickness of the carbon target is 9 mm. After the same sputtering of 500 kW·h, the lowest thickness of the remaining target material in Example 1 is 6.02 mm, while the lowest thickness of the remaining target material in Comparative Example 1 is 5.09 mm. This indicates that in Example 1, by adding a passivation layer to protect the carbon target surface, when the carbon particles in the vacuum chamber are subsequently removed in step S3, the loss of the target material is greatly reduced, and the target material life is significantly extended.

[0054] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A particle control method for a PVD carbon film device, characterized in that: The following steps are involved: Step S1, sputtering carbon film: transferring the substrate to a carrier in a vacuum sputtering chamber, forming a carbon film on the substrate using a DC magnetron sputtering target, and then removing the substrate from the vacuum sputtering chamber; Step S2, forming a silicon carbide passivation layer: transferring a non-doped pure silicon wafer to the carrier, applying radio frequency power P0 of a certain frequency to the carrier, gradually etching out silicon wafer atoms, and simultaneously inputting DC power P1 to the target material, so that silicon atoms combine with carbon atoms sputtered by DC. The sputtering time is recorded as t1. After the sputtering is completed, a silicon carbide passivation layer is formed on the surface of the target material; Step S3: The carbon film particles react with oxygen and are removed: the radio frequency power and frequency applied to the carrier remain unchanged, oxygen is introduced to fully react with the carbon particles in the cavity to form carbon dioxide gas, which is then pumped away; Step S4, restoring the target surface state: inputting an asymmetric bipolar pulse power P2 to the target, with P2 ≥ P1 and sputtering time t2 = t1, to remove the passivation layer on the target surface, and the target state is restored to the initial state; Step S5: Repeat steps S1-S4.

2. The particle control method of the PVD carbon film equipment according to claim 1, characterized in that: In step S1, the target material is a carbon target with a diameter of 320-321 mm, and the distance between the target material and the carrier is 40-60 mm.

3. The particle control method of the PVD carbon film equipment according to claim 1, characterized in that: In step S1, the target material is pre-sputtered for 1-3 minutes. During the pre-sputtering, the substrate temperature is set to 25-200°C, and the vacuum degree of the vacuum sputtering chamber is maintained at 1.0×10 -8 -5.0×10 -8 Torr, sputtering power is 500-1000W; Then, argon gas with a flow rate of 15-30 sccm is introduced into the vacuum sputtering chamber until the pressure of the vacuum sputtering chamber is 1.0-2.1 mTorr, and the target material is sputtered for 6-10 minutes at a sputtering power of 1000-3000W.

4. The particle control method of the PVD carbon film equipment according to claim 1, characterized in that: In step S2, the undoped pure silicon wafer is transferred to the carrier, argon gas with a flow rate of 30-60 sccm is introduced, the cavity reaction pressure is 2.2-4.4 mTorr, RF power of 2-27.12 MHz is applied to the carrier, power P0 = 100-1000 W, and DC power P1 = 50-200 W is input to the target material at the same time, and time t1 is maintained for 10-30 s.

5. The particle control method of the PVD carbon film equipment according to claim 1, characterized in that: In step S3, a radio frequency power of 2-27.12 MHz is applied to the carrier, the power P0 = 100-1000 W, the input power of the target material is zero, and oxygen with a flow rate of 80-100 sccm is introduced into the vacuum chamber. The opening of the pump plug valve is adjusted to 50%-80%, the chamber pressure is 20-40 mTorr, and the reaction time is 5-10 min, so that the oxygen fully reacts with the carbon particles in the chamber to form carbon dioxide gas, which is pumped away by the pump.

6. The particle control method of the PVD carbon film equipment according to claim 1, characterized in that: In step S4, argon gas is introduced at a flow rate of 30-60 sccm, the reaction pressure of the vacuum chamber is 2.2-4.4 mTorr, an asymmetric bipolar pulse with a power P2=50-200 W is input to the target material, the pulse frequency is 100-350 kHz, the duty cycle is 50-60%, and the pulse sputtering time t2 is 10-30 s.

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