JPH04217321A - Plasma processor - Google Patents

Abstract

PURPOSE:To ensure the reproducibility of film growth property without requiring frequent calibration by providing a means, which shifts a sub solenoid coil or a substrate susceptor in axial direction, and connecting the winding of a main solenoid coil and the winding of the sub solenoid coil in series. CONSTITUTION:The susceptor 22 is shifted by a shifter so that the board placing face of the susceptor 22 may be the optimum relative position in view of film property to the cusp face 17 of a cusp magnetic field. Next, a current is supplied in series to the main solenoid coil 1 and a sub solenoid coil 2 so as to form an electron cyclotron resonance magnetic field region in the vicinity of the waveguide junction inside a plasma generation chamber 4. Then, N2O gas introduced through a waveguide path 2 into the plasma generation chamber 4 is made into plasma efficiently by electron cyclotron resonance ionization effect. And N2O gas activates board surface reaction, and forms a good quality of SiO2 film on the surface of a board.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an apparatus for manufacturing semiconductor integrated circuits, particularly DRAMs by microfabrication of LSIs, etc. The main components thereof include microwave generating means;
Plasma generation in which the microwave transmission means and the gas that is coupled to the microwave transmission means and coaxially surrounded and introduced by the main solenoid coil are turned into plasma by the electron cyclotron resonance effect of the microwave and the magnetic field formed by the main solenoid coil. A reaction chamber that communicates with the plasma generation chamber through an opening on the side facing the microwave transmission means coupling portion of the plasma generation chamber and that accommodates a substrate stage on which a substrate is placed, and a main solenoid coil. An ECR (Electron Cyclotron Resonance) type plasma processing apparatus equipped with a sub-solenoid coil disposed coaxially with the main solenoid coil at a position far from the substrate mounting surface of the substrate stand and forming a cusp magnetic field in pair with the main solenoid coil. Regarding.

0002

2. Description of the Related Art As an example of a conventional plasma processing apparatus of this type, the one disclosed in Japanese Patent Application Laid-Open No. 63-43324 is known. As shown in FIG. 2, this type of device includes a waveguide 2 that transmits microwaves generated by a microwave generating means (not shown), and a main solenoid coil 1 that is coupled to the waveguide 2 and coaxially connected to the waveguide 2. An enclosed plasma generation chamber 4, a reaction chamber 5 communicating with the plasma generation chamber 4 through an opening 4a at the lower end of the plasma generation chamber 4, and a substrate placed on a substrate table 10 housed in the reaction chamber 5. The main component is a sub-solenoid coil 2 disposed on the back side of a substrate 11.

When forming, for example, a SiO2 film on the surface of the substrate 11 using the apparatus configured as described above, first, a current is applied from the power supply 12 to the main solenoid coil 1 to connect the waveguide in the plasma generation chamber 4. An electron cyclotron resonance magnetic field region with a microwave frequency, usually 2.45 GHz, is formed near the coupling part, and then microwaves are introduced into the plasma generation chamber 4, and N2O is introduced through the gas introduction pipe 6.
When the gas is introduced, the N2O gas is efficiently turned into plasma by the electron cyclotron resonance ionization effect, and this plasma is caused by the magnetic field 15 formed by the main solenoid coil 1.
The SiH4 gas introduced into the reaction chamber 5 through the gas introduction pipe 7 is activated and reaches the substrate 11 along the magnetic field 15, where SiO2 is deposited on the substrate 11.
A film is formed. Here, in the reaction chamber 5, a power source 13 is provided.
The sub solenoid coil 2 to which current is supplied from
A magnetic field 16 is formed in the opposite direction to the magnetic field 15 caused by the main solenoid coil 1, and the strong magnetic field at the center weakens the strong magnetic field at the center of the magnetic field 15, and the weak magnetic field at the periphery weakens the weak magnetic field at the periphery of the magnetic field 15. This weakens the axial magnetic field to form a uniform axial magnetic field on the front side of the substrate, equalizing the density of plasma directed toward the substrate, and contributing to the formation of a thin film with uniform thickness.

0004

[Problem to be Solved by the Invention] Conventionally, when forming a film using this type of apparatus, the characteristics of the formed film, such as the film thickness, depend on the position of the substrate in the reaction chamber and the The sub solenoid coil determines the position of the so-called cusp surface, where the axial magnetic field component becomes zero in the overall magnetic field configuration, that is, the cusp magnetic field obtained by forming a magnetic field in the opposite direction to the magnetic field formed by the main solenoid coil. Since it depends on the current, film formation was performed by setting film formation conditions using the position of the substrate in the reaction chamber and the sub-solenoid coil current as controlled parameters. However, in order to ensure reproducibility of membrane characteristics, it is necessary to ensure the stability of the device so that the current flowing through the sub-solenoid coil falls within a predetermined allowable fluctuation range.
For this purpose, in particular, the power supply circuits of the main solenoid coil and sub-solenoid coil are calibrated at frequent intervals, so that the current obtained by constant current value control using feedback control performed during film formation always maintains a predetermined allowable variation. I had to make sure it was within range. For this reason, there was a problem in that the operating rate of the device could not be sufficiently increased.

[0005] An object of the present invention is to provide a plasma processing apparatus that can ensure reproducibility of film-forming characteristics without requiring frequent calibration as in the prior art.

[0006]

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a microwave generation means, a microwave transmission means, which are coupled to the microwave transmission means and coaxially connected by a main solenoid coil. A plasma generation chamber that turns the surrounded and introduced gas into plasma by the electron cyclotron resonance effect caused by microwaves and the magnetic field formed by the main solenoid coil, and an opening on the side of the plasma generation chamber facing the microwave transmission means coupling part. a reaction chamber that accommodates a substrate stand on which a substrate is placed, which communicates with the plasma generation chamber; A plasma processing apparatus including a sub-solenoid coil that forms a pair with a solenoid coil to form a cusp magnetic field is an apparatus in which a winding of the main solenoid coil and a winding of the sub-solenoid coil are connected in series. do.

[0007] Furthermore, this device is further provided with a moving means for moving at least one of the substrate stand or the sub-solenoid in the axial direction of the sub-solenoid.

[0008]

[Operation] In this type of device, even if the position of the substrate varies within a range of ±10% of the distance from the reaction chamber side opening of the plasma generation chamber to the average substrate position, the plasma state within this range will be There is no significant change in film properties, such as film thickness distribution. However, even within this range, it is known that there is a correlation between the relative position of the cusp surface formed by the two coils and the substrate and the film formation characteristics. With conventional equipment,
The position of the cusp surface was controlled by controlling the current flowing through the sub-solenoid coil, and film formation was performed at the optimal relative position determined from the above correlation. However, for example, if the film thickness distribution is
The permissible variation range of the sub-solenoid coil current to keep it below 2% is only about 2%. Reproducibility of common power supply configurations,
In other words, if the deviation between the operating center value or reference value of the configured power supply and the desired center value or reference value is about 0.5%, when the main solenoid coil current and sub-solenoid coil current are independently controlled, both In the worst case, the variation range allowed for the coil is only about 1% in total. The present invention focuses on the fact that conventional frequent calibration is based on such a small allowable variation range from a quantitative perspective.

According to the present invention, since the winding of the main solenoid coil and the winding of the sub-solenoid coil are connected in series, when the positions of both coils are fixed, the cusp surface is fixed regardless of the magnitude of the current. The position is immovably fixed, and there is no need for constant control of the cusp surface position by feedback control of the sub-solenoid coil current as in the conventional case.

However, in this case as well, the movement of the cusp surface position does not greatly affect the current and position of the main solenoid coil because it is necessary to form an electron cyclotron resonance magnetic field region near the waveguide coupling part in the plasma generation chamber. Although it cannot be changed, the position of the sub-solenoid coil can be moved largely in the axial direction, so by moving the sub-solenoid coil in the axial direction, it is possible to perform a wide range of movement from the top surface to the bottom surface of the reaction chamber. Therefore, by providing a device with a moving means for moving at least one of the sub-solenoid coil or the board stand in the axial direction,
Film formation can be performed at the optimal relative position between the substrate and the cusp surface.

[0011]

[Embodiment] An embodiment of the present invention is shown in FIG. In this embodiment, the device is coupled to a microwave generating means (not shown), a waveguide 2 for transmitting microwaves oscillated by the microwave generating means, a main solenoid coil 1, and a waveguide 2. A plasma generation chamber 4 coaxially surrounded by the main solenoid coil 1, a reaction chamber 5 communicating with the plasma generation chamber 4 through an opening 4a at the lower end of the plasma generation chamber 4, and a reaction chamber 5 within the reaction chamber 5. placed in an insulated state,
A substrate stand 22 to which high-frequency power is supplied from a high-frequency power supply 21 located outside the reaction chamber 5, a bellows 23 that enables axial movement of the substrate stand 22 while maintaining airtightness inside the reaction chamber 5, and a substrate stand 22. The board placement surface is ±20 above and below the cusp surface.
The main components are a moving device 24 that moves forward and backward in the axial direction so as to move within a range of mm, and a sub-solenoid coil 2 that is placed on the back side of the board 11 placed on the board stand 22. has been done. Here, the winding of the main solenoid coil 1 and the winding of the sub-solenoid coil 2 are connected in series, and a DC power source 20 is connected to the plasma generation chamber 4.
A current is supplied to form an electron cyclotron resonant magnetic field region near the waveguide coupling portion within the cyclotron. The sub solenoid coil 2 is designed with the number of turns of the winding, the average diameter of the coil, etc. so that when this current flows, it can generate a magnetic field that forms a cusp surface at an appropriate position in the reaction chamber 5. Here, it is fixed at a fixed position on the back side of the substrate 11.

With this device, for example, SiO2 is deposited on the surface of the substrate.
When forming a film, first, the substrate table 22 is moved by the moving device 24 so that the substrate mounting surface of the substrate table 22 is positioned at the optimal relative position in terms of film characteristics with respect to the cusp surface 17 of the cusp magnetic field.
, and then supplying current from the DC power supply 20 to the main solenoid coil 1 and the sub-solenoid coil 2 in series to form an electron cyclotron resonance magnetic field region near the waveguide coupling part in the plasma generation chamber 4. Microwaves are introduced into the plasma generation chamber 4 through the waveguide 2, and N2O gas is introduced into the plasma generation chamber 4 through the gas introduction pipe 6, for example, at 30 SC.
CM is introduced at a flow rate of CM, and N2O gas is efficiently turned into plasma by the electron cyclotron resonance ionization effect. The plasma N2 O gas is transferred to the main solenoid coil 1.
The SiH4 gas moves into the reaction chamber 5 along the magnetic field 15 formed by the SiH4 gas and activates the SiH4 gas supplied into the reaction chamber 5 through the gas introduction pipe 7 at a flow rate of 15 SCCM. On the other hand, the substrate 11
A high frequency voltage is applied from the high frequency power supply 21 via the substrate table 22, creating a DC bias potential with a negative polarity to the ground on the substrate surface, so the O ions in the N2O gas plasma are accelerated by this potential. is injected into the substrate 11,
Activates the substrate surface reaction and forms a good Si film on the substrate surface.
Form an O2 film.

In this embodiment, the substrate stand 22 is moved to obtain the optimum relative position between the substrate 11 and the cusp surface 17.
The sub-solenoid coil 2 may be provided on the side, and the sub-solenoid coil 2 may be moved while the board stand 22 is fixed.

[0014]

Effects of the Invention In the present invention, since the plasma processing apparatus is constructed as described above, the following effects can be achieved.

In the device of claim 1, when the respective positions of the main solenoid coil and the sub-solenoid coil are fixed, the position of the cusp surface is fixed immovably regardless of the magnitude of the current supplied to both coils. The substrate is held at a fixed position within the reaction chamber, and its relative position does not change. Therefore, reproducibility of film formation can be ensured with high accuracy. For this reason, calibration, which was conventionally performed using a precision power supply once every few months, can now be done by checking only the positions of both coils without using a precision power supply. Inspection of the central operating value or reference value of the device itself can be performed at the same time as the calibration of the entire device, thereby improving the reliability of the reproducibility of device characteristics and the operating rate of the device.

In the device of the second aspect, since the optimum relative position between the substrate and the cusp surface is mechanically set, the relationship between the amount of movement of the sub-solenoid coil from the reference position and the position of the cusp surface is determined in advance. By this, the optimum relative position between the substrate and the cusp surface can be easily realized with high precision.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a plasma processing apparatus according to an embodiment of the present invention.

[Fig. 2] Longitudinal cross-sectional view of a conventional plasma processing apparatus

[Explanation of symbols]

1 Main solenoid coil 2 Sub solenoid coil 4 Plasma generation chamber 5 Reaction chamber 10　　　　PCB stand 11　　　　Substrate 17 Cusp surface 22　　　　PCB stand 24 Mobile device

Claims (2)

[Claims] Claim 1: A microwave generating means, a microwave transmitting means, and a gas connected to the microwave transmitting means and coaxially surrounded by a main solenoid coil and introduced into the microwave and a magnetic field formed by the main solenoid coil. a plasma generation chamber that turns into plasma due to the electron cyclotron resonance effect of and a sub-solenoid coil that is disposed coaxially with the main solenoid coil at a position farther from the main solenoid coil than the substrate mounting surface of the substrate stand and forms a cusp magnetic field in pair with the main solenoid coil. A plasma processing apparatus characterized in that a winding of the main solenoid coil and a winding of the sub-solenoid coil are connected in series. 2. The plasma processing apparatus according to claim 1, further comprising a moving means for moving at least one of the substrate stand and the sub-solenoid in the axial direction of the sub-solenoid.