JP3106719B2 - ECR plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ECR plasma processing apparatus used in an ultra LSI film forming step which requires low temperature film forming, particularly in a semiconductor manufacturing apparatus represented by an LSI manufacturing apparatus.

[0002]

2. Description of the Related Art For the purpose of improving film quality in low-temperature film formation, CVD and etching apparatuses using ECR (Electron Cyclotron Resonance) plasma using a resonance effect of a microwave and a magnetic field have been studied. The apparatus shown in FIG. 5 is an example of the plasma generation chamber 1 formed as an axially symmetric cylindrical body having a microwave inlet 1A and an opening 1B facing the microwave inlet 1A, and an opening 1B. The processing chamber 2 communicating with the plasma generation chamber through
When a carrier gas (plasma raw material gas) such as N ₂ , O ₂ , or Ar flows into the plasma generation chamber 1 depending on the purpose, microwaves are transmitted from the microwave oscillator 3 through the waveguide 4 and the microwave introduction window 5 to the microwave. Send in. A solenoid 6 is disposed outside the plasma generation chamber 1, and E is provided inside the plasma generation chamber 1.
CR plasma is generated. This plasma is extruded into the processing chamber 2, and on the way to the wafer holding table 7 </ b> A of the wafer holding mechanism 7, silane gas, which is a source gas fed into the processing chamber 2 via the hollow donut-shaped gas introduction ring 14. Is activated to form a silicon-based thin film on the surface of the wafer 8. The gas after film formation is supplied from the exhaust port 19 to the processing chamber 2.
It is discharged outside.

In such an ECR plasma processing apparatus, loading and unloading of a wafer 8 into and from the processing chamber 2 is performed by a vacuum transfer robot 1 in a load lock chamber 10 adjacent to the processing chamber 2.
1 and the wafer holding mechanism 7 in the processing chamber 2
It is performed through the carry-out port 2A. The wafer holding mechanism 7 is configured by using an electrostatic chuck 12 that sucks and holds the wafer 8 in a vacuum using a Coulomb force with the processing surface vertically downward. In such a configuration, when the wafer 8 is loaded into the wafer holding mechanism 7 in the processing chamber 2, first, the vacuum transfer robot 11 in the load lock chamber 10 into which the wafer 8 is loaded from the outside is loaded by the vacuum transfer robot 11 in the wafer holding mechanism 7 in the processing chamber 2. The wafer 8 is loaded and positioned immediately below. Subsequently, the wafer holding mechanism 7 is lowered by the outdoor vertical drive mechanism 13 to receive the wafer 8. The wafer holding mechanism 7 that has received the wafer further descends, and stops at a position where the wafer surface has passed the position of the wafer loading / unloading port 2A to perform processing such as thin film formation or etching. The unloading after the processing is the reverse movement.

In a film forming process, a method of controlling a fine shape of a cross section of a thin film by controlling an ion energy by applying an RF bias to a wafer has been used.

[0005]

In the ECR plasma processing apparatus configured as described above, when forming a thin film on the wafer surface, when an RF bias is applied to the wafer, abnormal discharge occurs in the transfer space on the back side of the wafer. In some cases, the film formation process cannot be performed under optimal conditions, and a defective film that does not satisfy required specifications is formed, resulting in a problem that the yield is significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide an ECR plasma processing apparatus which prevents abnormal discharge in a transfer space and secures optimum film forming conditions for satisfying required specifications.

[0007]

In order to solve the above-mentioned problems, in the present invention, a microwave introduction window and an opening are provided coaxially on both end surfaces, respectively, and the introduced carrier gas is separated from the microwave and the magnetic field. A plasma generation chamber formed as an axially symmetric cylindrical body that generates plasma using an electron cyclotron resonance effect, a solenoid that coaxially surrounds the plasma generation chamber and forms the magnetic field in the plasma generation chamber, and a plasma through the opening. A process in which a wafer held by a wafer holding mechanism is moved in the axial direction so as to communicate with the generation chamber and to have an exhaust port and a wafer loading / unloading port on the peripheral wall, and the inside of the processing chamber faces the opening. And forming a thin film on the wafer by activating the source gas introduced into the processing chamber using the plasma generated in the plasma generation chamber. The process ECR plasma processing apparatus for performing such etching of a resulting film, the internal space of the processing chamber,
The partition plate having an opening through which the wafer passes allows the space to be divided into a space on the plasma generation chamber side from the wafer loading / unloading port and a space on the anti-plasma generation chamber side including the wafer loading / unloading port, and An exhaust port is provided on the plasma generation chamber side space side, and when the wafer held by the wafer holding mechanism reaches the processing position in the plasma generation chamber side space through the opening of the partition plate, An apparatus in which the wafer holding mechanism includes a communication blocking unit that forms a communication blocking unit that blocks communication between the two spaces through the opening around the opening.

Here, the partition plate having an opening through which the wafer passes is provided with a ring-shaped groove surrounding the opening and opening into the space on the side opposite to the plasma generation chamber of the processing chamber, and a wafer holding mechanism. It is preferable that the communication blocking means provided in is formed as a cylindrical body having a cylinder inserted into the ring-shaped groove and a bottom surface fixed to the wafer holding mechanism. In this case, the communication blocking means rides on the open end surface of the groove when inserting the cylinder into the ring-shaped groove of the partition plate inside the cylinder.
It is more preferable that the inner peripheral surface is provided with a tapered ring forming a frustoconical surface extending toward the end surface.

Further, a ring made of an elastic body is provided in a ring-shaped groove around the opening of the partition plate having an opening through which the wafer passes, and the cylindrical end face of the cylindrical body provided with the wafer holding mechanism as a communication blocking means. It is more preferable that the partition plate is inserted so as to be in contact with the periphery so that the space on both sides of the partition plate is air-tightly separated. Further, in the plasma processing apparatus having the overall configuration as described above, an annular exhaust body having a hollow donut shape having a rectangular cross section and having an exhaust port formed in the inner peripheral wall equally in the circumferential direction is provided on the inner surface of the peripheral wall of the processing chamber. And an exhaust port provided on the side of the plasma generation chamber side of the processing chamber coaxially surrounding the wafer at the processing position, and an exhaust port formed on the outer peripheral wall of the exhaust ring body. It is preferable that it is formed at a position on the peripheral wall of the processing chamber that connects to the processing chamber.

Further, it is more preferable that the exhaust annular body be a device which also serves as a support member for a partition plate that divides the internal space of the processing chamber into two.

[0011]

The present invention focuses on the fact that the abnormal discharge in the transfer space when the RF bias is applied is caused by the fact that the gas flowing into the transfer space becomes conductive due to the application of the RF bias to the wafer. It was done. The ions in the plasma and the activated source gas, along with the electrons, try to move along the magnetic field lines created by the solenoid, but the electrons are strongly constrained to follow their magnetic paths along the path of movement, whereas the ions are The electron travels along a path affected by the hydrodynamic flow path of most of the gas that has no charge while being restrained in its moving path by electrons. Therefore, in the conventional apparatus configuration in which the exhaust port (19) is located on the peripheral wall of the processing chamber on the back side of the wafer from the wafer processing position, the gas flow reaching the wafer position reaches the exhaust port along the wafer surface. And
The ions in the plasma and the activated source gas also move along a path close thereto. Therefore, RF
When a bias is applied, a DC potential of ground negative polarity appears on the wafer surface, and as a result, ions in the plasma or activated source gas are adsorbed on the wafer, so that the gas flowing into the transfer space becomes conductive, Discharge is likely to occur. In addition, at the position of the conventional exhaust stack, it is inevitable that the density of the gas flow passing through the wafer becomes uneven,
The density of ions present in the gas flow also becomes non-uniform, and discharge is likely to occur along the path where the ion density is high.

However, as in the present invention, the inner space of the processing chamber is separated from the space on the plasma generation chamber side from the loading / unloading port of the wafer by the partition plate having an opening through which the wafer passes, and the loading / unloading of the wafer. It is divided into two parts, the space on the side opposite to the plasma generation chamber including the outlet, the exhaust port is provided on the space side on the plasma generation chamber side, and the wafer held by the wafer holding mechanism passes through the opening of the partition plate. An apparatus in which a wafer holding mechanism is provided with a communication blocking unit that forms a communication blocking unit formed around the opening when a processing position in the plasma generating chamber side space is reached at the processing position in the partition plate. With this configuration, the movement of the charges into the transfer space is eliminated, the discharge in the transfer space is prevented, and the position of the exhaust path is near the wafer, so that the flow of gas along the wafer surface is less likely to occur. Ri, the wafer front surface side, except for the immediately preceding wafer, only electrically neutral gas is present, abnormal discharge at the wafer front side is less likely to occur as in the prior art.

In this case, the communication between the spaces on both sides of the partition plate through the opening of the partition plate at the wafer processing position is prevented by inserting the cylinder of the communication blocking means of the wafer holding mechanism into the groove formed in the partition plate. If this is done, the magnetic lines of force of the solenoid will always cross the partition plate or the communication blocking means, so that the ions whose movement is restricted by the electrons moving along the lines of magnetic force will enter the anti-plasma generation chamber side space of the processing chamber. And communication can be prevented with a simple structure.

Further, the communication blocking means is formed inside the cylinder with a truncated conical surface which rides on the open end surface of the groove when the cylinder is inserted into the ring-shaped groove of the partition plate, and whose inner peripheral surface extends toward the end surface. If the tapered ring is provided, the communication blocking portion is formed without making the groove of the partition plate deep, and the movement amount of the wafer holding mechanism can be reduced. Therefore, the height of the processing chamber can be reduced. Yes, and the device is slightly smaller.

Further, a ring made of an elastic body is provided in a ring-shaped groove around the opening of the partition plate provided with an opening through which the wafer passes, and the entire cylindrical end face of the cylindrical body provided with the wafer holding mechanism as communication blocking means. By inserting the partition plate so that the spaces on both sides of the partition plate are air-tightly separated by contact over the circumference, it is possible to more reliably prevent the flow of the gas ionized by the application of the RF bias to the wafer, and the RF bias It is possible to more reliably prevent abnormal discharge in the transport space due to the application.

Further, in the plasma processing apparatus having the above-described overall configuration, an annular exhaust body having a hollow donut shape having a rectangular cross section and having an exhaust port formed on an inner peripheral wall equally in the circumferential direction is provided. An exhaust port is disposed at an axial position surrounding the wafer at the processing position coaxially along the inner surface of the processing chamber, and an exhaust port provided on the plasma generation chamber side space side of the processing chamber is formed on the outer peripheral wall of the exhaust ring. If the gas is formed at a position on the peripheral wall of the processing chamber connected to the exhaust port, the gas flows in an axially symmetric direction near the wafer, so that there is no flow across the wafer surface, and the gas flow along the wafer surface is more improved. It is effectively reduced and abnormal discharge on the front side of the wafer can be more reliably prevented.

Further, if the exhaust ring is used also as a support member for a partition plate that divides the internal space of the processing chamber into two, there is an advantage that the configuration of the apparatus is simplified.

[0018]

FIG. 1 shows an embodiment of an ECR plasma processing apparatus according to the present invention. In the figure, the same members as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted. In FIG. 1, the wafer 8 is
By the vacuum transfer robot 11 in the load lock chamber 10,
First, the wafer is loaded into the load lock chamber 10 from a wafer stocker in the atmosphere (not shown) via the vacuum gate valve 9A. Next, the vacuum transfer robot 11 in the load lock chamber 10
Opens the vacuum gate valve 9B and passes the wafer 8 directly below the wafer holding mechanism 7 in the processing chamber 2 through the wafer loading / unloading port 2A.
Is positioned. Subsequently, the wafer holding mechanism 7 is lowered by the outdoor vertical drive mechanism 13, and the electrostatic chuck 12 attached to the wafer holding mechanism 7 sucks and holds the wafer 8 with the processing surface vertically downward. Then vacuum transfer robot 11
Retreats into the load lock chamber 10. The wafer holding mechanism 7 holding the wafer 8 is lowered to the film forming position by the vertical driving mechanism 13 outside the room. At this time, the cylindrical body 17 fixed to the wafer holding mechanism 7 enters the ring-shaped groove 16A of the partition plate 16 fixed to the upper part of the exhaust ring 15.
In such a state, a carrier gas is flowed into the plasma generation chamber 1, and microwaves are sent from the microwave generator 3 through the waveguide 4 and the microwave introduction window 5 to the flowed place, and the magnetic field of the solenoid 6 arranged outside is used. Generate ECR plasma. This plasma is drawn into the processing chamber 2 and activates the source gas supplied from the gas introducing ring 14 in the processing chamber 2 to form a thin film on the wafer surface. At this time, the cylindrical body 17 fixed to the wafer holding mechanism 7 and the partition plate 16 fixed to the upper surface of the exhaust ring 15 form a communication blocking portion for blocking communication between the spaces on both sides of the partition plate 16. This prevents the converted source gas from flowing to the back side of the holding table of the wafer holding mechanism 7.

The exhaust annular body 15 is formed in the shape of a hollow donut having a rectangular cross section. Although not specifically shown here, the internal ring-shaped space is divided into two upper and lower stages using a ring-shaped partition plate. An exhaust port is formed on the inner peripheral side wall at equal intervals in the circumferential direction, and gas flowing in from the exhaust port flows a fixed distance in the circumferential direction along the partition plate, passes through the hole of the partition plate, and After entering the space and flowing a certain distance, the exhaust port 21
Is discharged to the outside. At this time, the position and number of each exhaust port on the peripheral wall surface of the exhaust annular body are set so that the gas flowing from any exhaust port has the same travel distance to the exhaust port 21 (for details, refer to Japanese Patent Application No. (See JP-A-2-117195).

FIG. 2 shows another embodiment of the communication blocking structure, in which the activated gas is maintained without increasing the thickness B of the partition plate even when the film formation position is moved to the transfer space side within the range A. Is prevented from reaching the back surface of the wafer holder. That is, when the wafer holding mechanism 7 is moved to the film forming position, the free taper ring 18 disposed in the cylindrical body 17 fixed to the wafer holding mechanism 7 is placed on the end face of the partition plate 16, and the partition plate and the cylinder The overlap with the body 17 is compensated to prevent the conductive gas from flowing to the back side of the wafer holder.

FIG. 3 shows still another embodiment of the communication blocking structure, and FIG. 4 is an enlarged view of a portion A in FIG. The film-forming position was limited, and when the wafer holding mechanism 7 was moved to the film-forming position, it was arranged in the ring-shaped groove 16A of the partition plate 16,
While slightly pushing the ring 22 made of an elastic body on the end face of the cylindrical body 17 fixed to the wafer holding mechanism 7, the ring 22
By this, the communication between the plasma generation chamber side and the transfer space side is more reliably prevented, and the conductive gas due to the application of the RF bias is prevented from flowing to the back side of the wafer holding table 7A.

[0022]

As described above, according to the present invention, an ECR plasma processing apparatus is provided in which
The partition plate having an opening through which the wafer passes allows the space to be divided into a space on the plasma generation chamber side from the wafer loading / unloading port and a space on the anti-plasma generation chamber side including the wafer loading / unloading port, and An exhaust port is provided on the plasma generation chamber side space side, and when the wafer held by the wafer holding mechanism reaches the processing position in the plasma generation chamber side space through the opening of the partition plate, Since the communication blocking means for blocking the communication between the two spaces through the opening is formed around the opening and the communication holding means is provided with the wafer holding mechanism, the plasma generated in the plasma generation chamber and the After the ions in the activated source gas are adsorbed by the wafer to which the RF bias is applied, the gas wraps around to the back side of the wafer holding table of the wafer holding mechanism in a state of being electrically conductive. This prevents abnormal discharge in the transfer space on the back side of the wafer, and enables film formation under optimal conditions. In addition, the film does not adhere to the walls and members of the transfer space. The yield of non-defective wafers is improved.

Further, in this device configuration, the communication blocking portion is formed by the groove of the partition plate and the cylinder of the communication blocking means formed as a cylinder having a bottom surface, thereby complicating the structure of the device. Thus, a communication blocking portion can be formed. Further, the communication blocking means is provided inside the cylinder,
When the cylinder is inserted into the ring-shaped groove of the partition plate, a tapered ring that rides on the open end surface of the groove and forms a frustoconical surface whose inner peripheral surface extends toward the end surface side is provided, so that the height of the processing chamber is increased. The cost can be reduced slightly, but the cost of the device is reduced slightly.

Further, a ring made of an elastic body is provided in a ring-shaped groove around the opening of the partition plate having an opening through which the wafer passes, and the cylindrical end face of the cylindrical body provided with the wafer holding mechanism as a communication blocking means is provided with a front end. By inserting so that the space on both sides of the partition plate is airtightly separated by making contact over the circumference, it is possible to reliably prevent the flow of gas ionized by the application of RF bias to the wafer into the transfer space. Abnormal discharge in the transport space is reliably prevented,
The film formation process under the optimum conditions can be performed more reliably, and the adhesion of the film to the transfer space wall surface and the transfer space inner member is reliably prevented, and the particle contamination is reduced. The yield of non-defective products is further improved.

In the plasma processing apparatus having the overall configuration as described above, the exhaust ring having a hollow donut shape having a rectangular cross section and having an exhaust port formed in the inner peripheral wall equally in the circumferential direction is formed in the peripheral wall of the processing chamber. An exhaust port is disposed at an axial position surrounding the wafer at the processing position coaxially along the inner surface of the processing chamber, and an exhaust port provided on the plasma generation chamber side space side of the processing chamber is formed on the outer peripheral wall of the exhaust ring. By forming it at a position on the peripheral wall of the processing chamber connected to the exhaust port, abnormal discharge on the front surface side of the wafer is more reliably prevented, and the operation rate of the apparatus is further improved.

Further, the above-mentioned effect can be obtained without complicating the apparatus by adopting a device structure in which the exhaust annular body also serves as a support member for the partition plate that divides the internal space of the processing chamber into two.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of an ECR plasma processing apparatus according to the present invention.

FIG. 2 is a sectional view of an essential part showing an embodiment different from that of FIG. 1 of the communication blocking structure of the partition plate on both sides according to the present invention;

FIG. 3 is a cross-sectional view of a principal part showing an embodiment different from FIGS. 1 and 2 of the communication blocking structure of the partition plate on both sides according to the present invention;

FIG. 4 is an enlarged view of a portion A in FIG.

FIG. 5 is a longitudinal sectional view showing an example of a configuration of a conventional ECR plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 1 plasma generation chamber 1B opening 2 processing chamber 2A loading / unloading port 5 microwave introduction window 6 solenoid 7 wafer holding mechanism 8 wafer 15 exhaust ring 16 partitioning plate 16A groove 16B opening 17 cylinder 18 taper ring 19 exhaust port 21 exhaust Mouth 22 ring

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 H01L 21/302 C23C 16/00

Claims (6)

(57) [Claims] 1. A microwave introducing window and an opening are coaxially provided on both end surfaces, respectively, and are formed as axially symmetric cylinders which convert introduced carrier gas into plasma by utilizing electron cyclotron resonance effect of microwave and magnetic field. A plasma generation chamber, a solenoid that coaxially surrounds the plasma generation chamber and forms the magnetic field in the plasma generation chamber, communicates with the plasma generation chamber through the opening, and has an exhaust port and a wafer loading / unloading port on the peripheral wall. A processing chamber in which the wafer held by the wafer holding mechanism moves in the axial direction such that the surface to be processed faces the opening, using plasma generated in the plasma generation chamber. ECR plasma processing equipment that activates the source gas introduced into the processing chamber to form a thin film on the wafer or perform processing such as etching of the generated film The inner space of the processing chamber is separated by a partition plate provided with an opening through which the wafer passes, by a space on the plasma generation chamber side from the wafer loading / unloading port and on the side opposite to the plasma generation chamber including the wafer loading / unloading port. And an exhaust port is provided on the plasma generation chamber side space side, and the wafer held by the wafer holding mechanism passes through the opening of the partition plate and the processing position in the plasma generation chamber side space An ECR plasma processing apparatus, characterized in that the wafer holding mechanism has a communication blocking means for forming a communication blocking portion around the opening when blocking the communication between the two spaces through the opening of the partition plate when the wafer reaches the opening. . 2. The ECR plasma processing apparatus according to claim 1, wherein the partition plate having an opening through which the wafer passes is formed in a ring shape surrounding the opening and opening into a space opposite to the plasma generation chamber. An ECR comprising a groove, wherein the communication preventing means provided in the wafer holding mechanism is formed as a cylinder having a cylinder inserted into the ring-shaped groove and a bottom surface fixed to the wafer holding mechanism. Plasma processing equipment. 3. The ECR plasma processing apparatus according to claim 2, wherein the communication preventing means rides on the open end face of the groove inside the cylinder when inserting the cylinder into the ring-shaped groove of the partition plate. An ECR plasma processing apparatus comprising: a tapered ring having an inner peripheral surface forming a truncated conical surface extending toward the end surface. 4. The ECR plasma processing apparatus according to claim 2, wherein the partition plate having an opening through which the wafer passes is formed in a ring shape surrounding the opening and opening into the space opposite to the plasma generation chamber. A ring made of an elastic body is inserted into the groove in such a manner that the cylindrical end face of the cylindrical body provided as the communication blocking means in the wafer holding mechanism contacts over the front circumference and the space on both sides of the partition plate is airtightly separated. An ECR plasma processing apparatus, comprising: 5. An ECR plasma processing apparatus according to claim 1, wherein the exhaust chamber is formed in a hollow donut shape having a rectangular cross section and an exhaust port is formed in an inner peripheral wall at equal circumferential intervals. An exhaust port is provided along the inner surface of the peripheral wall and coaxially surrounds the wafer at the processing position, and an exhaust port provided on the plasma generation chamber side space side of the processing chamber is formed in the outer peripheral wall of the exhaust ring. An ECR plasma processing apparatus is formed at a position on a peripheral wall of a processing chamber connected to a selected exhaust port. 6. An ECR plasma processing apparatus according to claim 5, wherein the annular exhaust member also serves as a support member for a partition plate that divides the internal space of the processing chamber into two.
R plasma processing equipment.