JPH059742A - Plasma treating device and constituting method - Google Patents

Abstract

PURPOSE:To form an insulating film without causing the damage arising from the charge up on a sample surface by an electron cyclotron resonance method and a bias, ECR plasma CVD deposition method which impresses an RF bias to a substrate holder. CONSTITUTION:Oxygen is introduced from a 1st gas introducing port 7 to form plasma and SiH4 is introduced from a 2nd gas introducing port 8 to form an SiO2 film on a wafer 11. The RF bias is impressed to the substrate holder 5 from an RF power source 6 to generate sputter etching, by which the formation and flattening of the SiO2 film are attained. A magnet coil 1 is moved in parallel with its axial central direction at this time to decrease the damage by the charge up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a method for constructing a plasma processing apparatus for generating plasma by using an electron cyclotron resonance method to reduce damage caused when a thin film is formed on a semiconductor element. Is.

[0002]

2. Description of the Related Art When a semiconductor integrated circuit is manufactured, it is indispensable to use a plasma processing apparatus due to miniaturization of the semiconductor integrated circuit. However, when a plasma processing apparatus is used, damage from the plasma is a problem.
In particular, as damage, destruction of the gate insulating film due to charge-up of charged particles is an important problem. In particular, the bias ECR plasma CVD deposition method, which is an insulating film flattening technique for generating plasma by an electron cyclotron resonance method and applying a radio frequency (RF) bias to a substrate, is characterized by low-temperature thin film formation and excellent filling characteristics. There was a problem of gate insulating film destruction.

FIG. 5 (a) is a sectional view of the target semiconductor device, and FIG. 5 (b) is a bias ECR plasma CV.
The time dependency of the damage characteristic to the gate oxide film by the D deposition method is shown. In FIG. 5A, reference numeral 15 is a bias EC.
A SiO2 film formed by R plasma CVD deposition, a 16-polysilicon gate electrode, 17 an Al electrode, and 18 a gate oxide film. In FIG. 5B, the vertical axis represents the yield of the gate oxide film, and the horizontal axis represents the deposition time. The gate oxide film 18 is 11
The thickness is 0 angstrom, and the SiO2 film 15 is formed directly on the polysilicon gate electrode 16 of the MOS diode by the bias ECR plasma CVD deposition method. The antenna pattern in which the electrode area is changed is used as a parameter for the gate area of 100 μm square in FIG. Further, comparison is made regarding whether or not the RF bias is applied.

[0004]

In the above, when the RF bias is not applied, the yield of the gate oxide film 18 is increased even if the antenna ratio (the value AR obtained by dividing the area of the antenna electrode area by the area of the gate area) is large. There is no deterioration. But R
When the F bias is applied, the yield deteriorates as the antenna ratio increases and the deposition time increases. This is considered to be because the deterioration in yield is charge-up when an RF bias is applied. In the current device configuration, there is no means for avoiding charge-up when applying the RF bias. In addition, the RF frequency applied to the substrate holder in the system applying RF bias is 13.56.
A means for avoiding damage by setting a low frequency from MHz to 400 kHz has been considered. The purpose of this method is mainly to use the low frequency to allow the ion to follow the electron rather than the electron, and to reduce the self-bias voltage to avoid the damage due to the ion bombardment. , It's not enough to avoid charge-up.

An object of the present invention is to provide an electron cyclotron resonance method and a bias EC for applying an RF bias to a substrate holder.
It is an object of the present invention to provide a plasma processing apparatus which can solve the damage caused by the charge-up phenomenon on the surface of a sample by the R plasma CVD deposition method and can form an insulating film without damaging the device and a method of using the plasma processing apparatus.

[0006]

A plasma processing apparatus according to the present invention includes a sample chamber having a cylindrical plasma generating chamber having a magnet coil on its outer periphery and a substrate holder facing the plasma generating chamber and capable of applying high frequency. In a plasma processing apparatus that generates plasma by using an electron cyclotron resonance method, in order to adjust the distance between the magnet coil position and the substrate holder, the magnet coil is movable and fixed in a direction parallel to its axis. It was done. Further, the moving range of the magnet coil is set so that the electron cyclotron resonance point is at least set within a range of 2 cm to 6 cm from the microwave introduction port. Furthermore, the apparatus configuration method of the plasma processing apparatus of the present invention is to adjust the position of the magnet coil and the position of the substrate holder so as not to damage the semiconductor element.

[0007]

The plasma processing apparatus and apparatus configuration method according to the present invention are based on charge-up by electrons trapped in the magnetic field by adjusting the position of the magnet coil to suppress the influence of the magnetic field strength from the magnet coil on the substrate. Avoid damage to the element.

[0008]

1 is a schematic sectional view showing an embodiment of the present invention. Reference numeral 1 denotes a magnet coil, which is movable in a direction parallel to the axis of the magnet coil, and is provided with a fixing means (not shown) so that the magnet coil can be fixed at an arbitrary position. Reference numeral 2 is a microwave inlet, and 3 is a plasma chamber, which has a cylindrical shape with a width of 20 cm and a radius of 10 cm. 4 is the sample chamber, 5 is R
A substrate holder for applying an F bias, 6 is an RF power source, 7 is a first gas inlet, 8 is a second gas inlet, 9 and 10 are cooling water, and 11 is a wafer. In the present invention, oxygen is introduced through the first gas inlet 7 to generate plasma, SiH4 is introduced through the second gas inlet 8, and SiO2 is formed on the wafer 11. In addition, the RF power from the RF power source 6 to the substrate holder 5
A bias is applied to cause sputter etching to form an insulating film and achieve planarization.

FIG. 2 shows the yield of the gate oxide film 18 when the magnet coil position of the magnet coil 1 of the present invention is moved. The vertical axis represents the yield of the gate oxide film 18, and the horizontal axis represents the distance between the left end of the magnet coil 1 and the wafer 11, that is, the magnet coil position. The deposition time is constant for 200 seconds. Gas pressure is 1.0 mTorr,
Microwave power 800W, RF power density 1.1
The magnet current value is 7 W / cm @ 2 and the magnet current value is 17 A. The gate oxide film thickness was 110 Å, the area of the gate oxide film was 100 μm square, and the electrode area was 1.0 mm square. The yield is worse than 40% when the magnet coil position X is 150 mm from the wafer 11. However, the magnet coil position is 180-21
The yield is improved between 0 mm. As is clear from this result, it is understood that the damage is reduced by moving the position of the magnet coil.

FIG. 3 shows the magnetic field strength and ion current density in the radial direction Br and the vertical direction Bz on the surface of the wafer 11 when the magnet coil 1 is moved. When the position of the magnet coil is 180 mm or more, the magnetic field strength in the radial direction Br is reduced to about ⅓, and the vertical direction Bz is reduced to about ½. The ion current density is almost constant. That is, it is considered that the magnetic field intensity on the sample surface influences the charge-up. Originally, when an RF bias is applied on the surface of the wafer 11, the effect of the RF bias is to generate plasma and accelerate ions from ECR plasma. Electron neutralization is sufficient if only ECR plasma is used. However, it is considered that when the RF bias is applied on the sample surface in the presence of the magnetic field, the plasma density increases as compared with the case without the magnetic field. There are three types of electrons on the sample surface: 1) diffused into plasma, 2) neutralized with ions in the sheath, and 3) moved to the sample surface by thermal motion. It is considered that when the magnetic field strength is strong, the amount of electrons trapped in the magnetic field increases, causing charge-up. That is, the feature of the present invention is that the magnetic field strength is reduced by moving the position of the magnet coil away from the sample surface, and the charge-up phenomenon due to electrons is reduced. Here, a method may be considered in which the substrate holder 5 and the plasma chamber 3 are separated from each other in order to reduce the magnetic field strength on the sample surface. However, in this method, ECR plasma cannot be efficiently supplied to the film formation and the deposition rate is increased. It has the drawback of becoming smaller.

FIG. 4 shows an electron cyclotron resonance point (875 gauss) when the position of the magnet coil is moved.
From the comparison between FIG. 2 and FIG. 4, it is understood that when the magnet current value is 17 A, the damage is reduced when the resonance point exists between 2 and 6 cm from the microwave introduction port 2.
On the other hand, when the magnet current value is 15 A, the magnetic field strength on the sample surface becomes small. At this time, the resonance point is located 15 mm from the microwave introduction port 2. Also,
Damage is also occurring. That is, even if the magnetic field on the surface of the wafer 11 is weakened, the resonance point is 2 to 6 cm.
It is shown that the object of the present invention cannot be achieved unless it is set in the area of. The existence of this peculiar region is physically unknown, but is expected to change depending on the size of the cylindrical plasma chamber 3 and the like. Therefore, it is considered that this damage reduction region exists corresponding to the arbitrarily defined plasma chamber 3. The feature of the present invention is that the position of the magnet coil is adjusted to reduce the magnetic field strength and the resonance point is set in the damage reduction region to reduce the damage.

Although the above-mentioned embodiment is carried out for thin film formation, by using an etching gas in place of the gas for deposition in the apparatus structure of the present invention, it is possible to reduce the charge-up that occurs during etching. Needless to say, is also effective.

[0013]

As described above, according to the present invention, in the plasma processing apparatus and apparatus configuration method capable of generating plasma by the electron cyclotron resonance method and applying the RF bias to the substrate, the magnet coil is parallel to the axis thereof. Since it is movable in the direction, the electron cyclotron resonance point is shifted without changing the magnet current value by adjusting the magnet coil position, and the magnetic field strength on the wafer surface is reduced,
The charge-up phenomenon due to electrons can be suppressed.
Therefore, the insulating film can be formed without damaging the MOS device.

Furthermore, since the electron cyclotron resonance point is set at least within the range of 2 to 6 cm from the microwave introduction port, damage to the MOS device can be minimized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between magnet coil position and yield according to the present invention.

FIG. 3 is a diagram showing the relationship between the position of a magnet coil according to the present invention and the magnetic field strength and the ion current density in the radial and vertical directions on the wafer surface.

FIG. 4 is a diagram showing a relationship between a magnet coil position and an electron cyclotron resonance point according to the present invention.

FIG. 5 is a cross-sectional view of a semiconductor device to be processed and a diagram showing time dependence of damage characteristics to a gate oxide film by a bias ECR plasma CVD deposition method.

[Explanation of symbols]

1 magnet coil 2 Microwave inlet 3 Plasma chamber 4 Sample chamber 5 substrate holder 6 RF power supply 7 First gas inlet 8 Second gas inlet 9 cooling water 10 cooling water 11 wafers

Claims (3)

[Claims] 1. A cylindrical plasma generation chamber having a magnet coil on the outer periphery and a microwave introduction port, and a sample chamber having a substrate holder facing the plasma generation chamber and capable of applying a high frequency bias, In a plasma processing apparatus for generating plasma by using an electron cyclotron resonance method, in order to adjust the distance between the magnet coil position and the substrate holder, the magnet coil can be moved and fixed in a direction parallel to its axis. A plasma processing apparatus characterized by the above. 2. The plasma processing apparatus according to claim 1, wherein the magnet coil has an electron cyclotron resonance point set at least within a range of 2 cm to 6 cm from the microwave introduction port. 3. The plasma processing apparatus according to claim 1, wherein the distance between the magnet coil position and the substrate holder is adjusted to move the magnet coil to a position that does not damage the semiconductor element. How to configure.