JPH0845857A - Plasma cvd method and controller - Google Patents

Abstract

PURPOSE:To improve the adhesiveness of a film deposited on a substrate, by keeping high ion impact in plasma CVD from the start of the deposition step. CONSTITUTION:At first an electric gas discharge step starts with a non- deposition gas (steps 26, 27 and 28). After the discharge becomes stable (steps 29, 30, and 31), a raw gas is fed and the pressure is adjusted (step 32). When a film with a given thickness is deposited, the electric discharge is stopped (steps 33, 34, and 36).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma CVD method and a controller for automatically performing the method, and more particularly to a plasma C method.
When forming a compound thin film on a substrate from a source gas by the VD method,
The present invention relates to a plasma CVD method for controlling at least one of discharge energy, raw material gas pressure, and raw material gas mixing ratio, and a control apparatus therefor.

[0002]

2. Description of the Related Art Conventionally, this type of plasma CVD method is
For example, as disclosed in Japanese Patent Laid-Open No. 4-198484, it is used to improve the adhesion of the deposited thin film to the substrate. FIG. 3 is an apparatus configuration diagram showing an example of a conventional plasma CVD control apparatus. As shown in FIG. 3, the CVD control device 57 includes a power control means 54, a gas control means 55, and a pressure adjusting means 56.
The power control means 54 sets the scheduled power output value, and sends the scheduled power output value and the output start signal to the power source 37 by the output start signal from the outside. Also, the output stop signal is sent to the power supply 37 by the output stop signal from the outside. The gas control means 55 is set with a planned gas flow rate value, and sends a planned gas flow rate value and a gas flow start signal to the mass flow controller 58 in response to a gas flow start signal from the outside. The pressure adjusting means 56 outputs an opening / closing control signal to the orifice 49 so that the preset gas pressure value and the pressure value output by the pressure gauge 39 match. Plasma CVD except plasma CVD control device 57
The apparatus includes a cathode 43, an anode 44, a reaction chamber 42 and a heater 46.
And a power supply 37 and a matching unit 38. The distance between the cathode 43 and the anode 44 is 3 cm. The cathode 43 has holes having a diameter of 0.5 mm opened at intervals of 5 mm on the entire surface facing the anode 44, and serves as a shower head from which gas is ejected. The reaction chamber 42 and the anode 44 are grounded. The heater 46 heats the substrate 44 placed on the anode 44 by heating the anode 44. Matching device 38 is power source 37
In order to achieve impedance matching between the cathode 43 and the cathode 43, all the high frequency power of the power source 37 is applied to the cathode 43,
A plasma is generated between the anode 44 and the anode.

Next, a conventional plasma CVD method will be described with reference to FIGS. 3 and 4. The smaller the film formation rate, the greater the adhesion of the thin film to the substrate, but the lower the productivity. Therefore, the film formation is performed at a low speed only in the initial stage of film formation, and thereafter at a high speed. Therefore, first, the raw material gas mixing ratio, the raw material gas pressure, and the high frequency power are set using the gas control means 55, the pressure adjusting means 56, and the power control means 54, respectively, under the condition that the film forming rate is low (steps 60 and 61). And 62), an output start signal is input to the power control means 54 to cause the power supply 37 to output high frequency power (step 6).
3). The output high frequency power is applied to the cathode 43,
Discharge starts between the cathode 43 and the anode 44. After the discharge is started, a plasma potential (Vp) is generated between the plasma on the substrate 45 and the substrate 45. Vp is 0 in the absence of plasma before the start of discharge, and increases as plasma is generated and the plasma density rises, and stabilizes at a constant value Vp0 when the plasma density distribution in the reaction chamber 42 stabilizes. From the state of Vp = 0 immediately after the start of discharge to the state of Vp = Vp0, the film has a Vpe smaller than Vp0eV.
It is deposited while being bombarded by ions having V energy. After Vp = Vp0, deposition is performed while being bombarded by ions having an energy of Vp0eV. The greater the ion bombardment energy during deposition, the greater the density of the film. Where the density is high, the areal density of the bonds existing in the cross section is also high, and in general, the adhesion with other substrates is also high. After the start of discharge, a film having good adhesion is formed by depositing for a time T4 which is longer than the time required to reach Vp = Vp0 from Vp = 0. After the lapse of T4 (step 64), the mixture ratio and pressure of the raw material gas and the high frequency power are changed to the conditions of high film formation rate by using the gas control means 55, the pressure control means 56 and the power control means 54, respectively ( Step 65). When the required film thickness is deposited after the elapse of the fixed time T5 (step 66), an output stop signal is input to the power control means 54 to stop the deposition (step 67).

[0004]

As the ion bombardment energy during deposition increases, so does the density of the film. Where the density is high, the areal density of the bonds existing in the cross section is also high, and in general, the adhesion with other substrates is also high. However, in this conventional plasma CVD method, since the ion bombardment energy immediately after the start of discharge remains smaller than Vp0eV, the density of the film at the interface of the substrate formed by receiving this small ion bombardment energy does not improve, and the film There is a problem that the adhesion with the substrate is not improved.

[0005]

In order to solve the above-mentioned problems, a plasma CVD method according to the present invention is a plasma CVD method in which at least one of a gas flow rate, a gas pressure, and a discharge power is changed after a discharge is started. In the above, after introducing only gas that does not cause deposition into the reaction chamber, discharge is started,
After that, a gas causing deposition is introduced into the reaction chamber while maintaining the discharge. Here, as the gas that does not cause deposition, an inert gas, a nitrogen gas, an oxygen gas, a hydrogen gas, a gas having nitrogen, oxygen or a hydrogen atom in the molecule, a halogen gas or a gas having a halogen atom in the molecule is used. Can be mentioned. Further, the plasma CVD control apparatus according to the present invention is a plasma CVD control apparatus for controlling discharge power, gas flow rate and gas pressure of the plasma CVD apparatus, and discharge detection means for detecting discharge in the reaction chamber and outputting a discharge detection signal. When the discharge detection signal is received, time measurement is started, and after a preset first time elapses, a gas flow rate change signal and a pressure change signal are output, and then a preset second time After the lapse of time, a timer means for outputting the output change signal and then for outputting the output stop signal after the lapse of the preset third time, and first, for the preset first gas flow rate preset value. A gas control means for controlling the gas flow rate and, when receiving the gas flow rate change signal, controlling the gas flow rate to a preset second preset gas flow rate value; Pressure control means for controlling the pressure to a preset first preset pressure value and, when receiving the pressure change signal, controlling the pressure to a preset second preset pressure value; When the output of the discharging power supply is controlled to the first power supply output scheduled value and the output change signal is received, the pressure is controlled to the preset second pressure planned value, and the output stop signal is received, And a power control means for stopping the output of the discharging power supply.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. Since the plasma CVD control device of the present invention is a device for executing the plasma CVD method of the present invention, the description of the embodiment of the plasma CVD control device of the present invention will be used to explain the embodiment of the plasma CVD method of the present invention. And FIG. 1 is an apparatus configuration diagram showing an embodiment of a plasma CVD control apparatus according to the present invention. As shown in FIG. 1, the plasma CVD control device 24 includes a power control means 19
It is composed of a gas control means 20, a discharge detection means 22, a pressure adjusting means 23 and a timer means 21. The power control means 19 can set two power supply output scheduled values Pw1 and Pw2, and sends the power supply output scheduled value Pw1 and the output start signal to the power supply 2 by an output start command from the outside. Further, the power supply 2 receives the output change signal from the timer means 21.
Then, the scheduled power output value Pw2 is sent to. Further, in response to the output stop signal from the timer means 21, the output stop signal is sent to the power supply 2. The gas control means 20 can set two gas flow rate planned values F1 and F2, and sends the gas flow rate planned value F1 and the gas flow start signal to the mass flow controller 25 in response to an external gas flow start command. . Further, upon receiving the flow rate change signal from the timer means 21, the gas flow rate scheduled value F2 is sent to the mass flow controller 25. The discharge detection means 22 detects the generation of plasma in the reaction chamber 7 and sends a detection signal to the timer means 21. The pressure adjusting means 23 can set two planned gas pressure values Pr1 and Pr2, and the orifice 14 is set so that the planned gas pressure value Pr1 and the pressure value output by the pressure gauge 4 match by a pressure control command from the outside. An open / close control signal is output to. Further, in response to the pressure change signal from the timer means 21, the opening / closing control signal is output to the orifice 14 so that the expected gas pressure value Pr2 and the pressure value output by the pressure gauge 4 match. The timer means 21 can set three times T1, T2 and T3, and receives a detection signal from the discharge detection means 22 to start time counting. After a lapse of T1 from the start of timing, a flow rate changing signal and a pressure changing signal are sent to the gas control means 20 and the pressure adjusting means 23, respectively. After that, when T2 further elapses, an output change signal is sent to the power control means 19. Then T
After the lapse of 3, an output stop signal is sent to the power control means 19. Plasma C excluding plasma CVD controller 24
The VD device includes a cathode 8, an anode 9, a reaction chamber 7, a heater 11, a power supply 2 and a matching unit 3. The distance between the cathode 8 and the anode 9 is 3c
m. The cathode 8 has holes having a diameter of 0.5 mm opened at intervals of 5 mm on the entire surface facing the anode 9, and serves as a shower head from which gas is ejected. Reaction chamber 7
And the anode 9 is grounded. The heater 11 heats the anode 9 to heat the substrate 10 placed on the anode 9. Since the matching device 3 performs impedance matching between the power source 2 and the cathode 8, all the high frequency power of the power source 2 is applied to the cathode 8 and plasma is generated between the cathode 8 and the anode 9.

Next, the operation of this embodiment of the plasma CVD control apparatus will be described with reference to FIGS. 1 and 2.
First, a gas feed start command is given to the gas control means 20 from the outside, and the non-depositing gas set in F1 of the gas control means 20 is introduced into the reaction chamber 7 (step 26). Next, a pressure control command is given to the pressure adjusting means 23 from the outside to adjust the gas pressure to the pressure set in Pr1 of the pressure adjusting means 23 (step 27). Next, an output start command is given to the power control means 19 from the outside, and the power source 2 receives the power control means 19
The power set to w1 is output (step 28). When the discharge detection means 22 detects the start of discharge, it outputs a time measurement start signal to the timer means 21 (step 29), and the timer means 21 receives the time measurement start signal and starts time measurement (step 30). After the start of discharge, Vp increases from 0 and stabilizes at Vp0 after a certain time T10. T1 of the timer means 21 is
It is set to a value larger than T10 in advance, and after T1 has elapsed from the start of discharge, the gas control means 20 and the pressure adjusting means 23
Then, a flow rate change signal and a pressure change signal are sent to each of them (step 31). When the gas control means 20 receives the flow rate change signal, the gas control means 20 stops the flow of the gas set in F1,
The flow of the mixed gas (material gas) containing the gas that causes the deposition set at 1 is started (step 32). In parallel with this gas changing operation, the pressure control means 23 adjusts the gas pressure to the value set in Pr2 of the pressure control means (step 32). The gas flow rate and gas pressure are set to T
Stabilizes after 20. The discharge continues even in the process of changing the gas flow rate and the pressure. A value larger than T20 is preset in T2 of the timer means 21. When T2 elapses after the gas flow rate and gas pressure change signals are sent, the timer means 21 sends an output change signal to the power control means 19 (step 33). Receiving this signal, the power control means 19 raises the output of the power supply 2 to the value set in Pw2 of the power control means 19 (step 34). The time required to deposit the desired film thickness is preset in T3 of the timer means 21. The timer means 21 sends the output change signal to the power control means 19,
When T3 has elapsed, an output stop signal is sent to the power control means 19 (step 35). The power control means 19 that has received the output stop signal stops the output of power from the power supply 2 (step 36), and the deposition operation is completed.

Next, the present invention will be specifically described by taking as an example the case where silicon dioxide is actually deposited on the gallium arsenide substrate on which gold wiring is formed by using the plasma CVD method. First, as a preparation, the anode 9 is heated by the heater 11, and the gallium arsenide substrate with gold wiring placed on the anode 9 is kept at 300 ° C. Further, the orifice 14 is fully opened, and the gas in the reaction chamber 7 is exhausted from the exhaust port 13 until the pressure gauge 4 shows 1 × 10 ⁻³ Pa or less. Subsequently, the operation of the part according to the present invention will be described. Argon 100SCCM is set as the non-depositing gas in F1 of the gas control means 20, and the argon is introduced into the reaction chamber 7 by an external command. The pressure adjusting means 23 adjusts the gas pressure to the pressure 0.5 Pa set to Pr1. According to the output command from the power control means 19, the power supply 2 outputs the high frequency power having the frequency of 375 kHz by 10 W set to Pw1. The timer means 21 receives the time measurement start signal from the discharge detection means 22 and starts time measurement, and when 5 seconds elapse as T1, the flow rate change signal and the pressure change signal are sent to the gas control means 20 and the pressure adjustment means 23, respectively. To do. Gas control means 20
Switches the gas from 100 SCCM of argon set to F1 to 100 SCCM of silane and 100 SCCM of nitrogen dioxide set to F2. The pressure control means 23 adjusts the gas pressure to 1 Pa set to Pr2. When the gas flow rate and the gas pressure have stabilized after 5 seconds, a signal from the timer means 21 is received and the power control means 19 is received.
Raises the high frequency power to 100 W set to Pw2 and starts the deposition of the silicon dioxide film. When one minute elapses as T3, the discharge is stopped and the operation of the part according to the present invention ends. Then, the introduction of the material gas is stopped, the orifice 14 is fully opened, and the gas in the reaction chamber 7 is exhausted. When the pressure gauge 4 shows 1 × 10 ⁻³ Pa or less, the orifice 14
To be fully closed to stop exhaust. Nitrogen is introduced into the reaction chamber 7, and the substrate is taken out when the atmospheric pressure is reached.

The film thickness of the silicon dioxide deposited in this example was 0.5 μm. When compared with a silicon dioxide film of the same thickness deposited by using the conventional method, in the conventional method, when the area ratio of the gold wiring on the gallium arsenide substrate exceeds about 30%, the silicon dioxide film is peeled off after the film formation. Although observed, in the film according to the present invention, peeling was not observed up to about 50%, which confirmed that the adhesiveness was improved.

In this embodiment, argon is used as the non-depositing gas, but other inert gas such as helium, neon or xenon may be used. Further, by using nitrogen, oxygen, hydrogen, nitrogen dioxide containing them, water, or the like, surface modification such as nitriding, oxidation, or reduction of the substrate surface can be performed at the same time as the start of discharge. Furthermore, as non-depositing gas,
A gas for etching the substrate may be used to start the discharge, and the surface of the substrate may be cleaned when the discharge is started. Examples include combinations in which a halogen gas such as chlorine gas or fluorine gas is used for the silicon substrate, or a gas whose molecule contains a halogen element such as sulfur hexafluoride, silicon tetrachloride, or nitrogen trifluoride is used. A mixture of these non-depositing gases can be used as long as they do not cause deposition.

[0011]

As described above, in the plasma CVD method according to the present invention, the non-depositing gas is used at the start of discharge, and then the procedure is switched to the deposition material gas while maintaining the discharge. The existing film at the beginning of the deposition is also subjected to sufficient ion bombardment, and the adhesion of the deposited film to the substrate is improved. Further, since the plasma CVD control apparatus according to the present invention accurately executes the plasma CVD method according to the present invention in time, it is possible to control the gas flow rate, the pressure, and the electric power, which require control within a few seconds, with good controllability. The advantage is that the reproducibility of the plasma CVD method according to the present invention can be improved.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram for explaining a method according to the present invention.

FIG. 2 is a block diagram showing the operation of the present invention.

FIG. 3 is a device configuration diagram for explaining a method according to a conventional example.

FIG. 4 is a block diagram showing an operation of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grounding 2 Power supply 3 Matching device 4 Pressure gauge 5 Gas mixer 6 Insulator 7 Reaction chamber 8 Cathode 9 Anode 10 Substrate 11 Heater 12 Gas blowout port 13 Exhaust port 14 Orifice 15 Grounding 16, 17, 18 Gas 19 Power control means 20 Gas control Means 21 Timer means 22 Discharge detecting means 23 Pressure adjusting means 24 Plasma CVD control device 25 Mass flow controller 37 Power supply 38 Matching device 39 Pressure gauge 40 Gas mixer 41 Insulator 42 Reaction chamber 43 Cathode 44 Anode 45 Substrate 46 Heater 47 Gas outlet 48 Exhaust Mouth 49 Orifice 50 Grounding 51, 52, 53 Gas 54 Power control means 55 Gas control means 56 Pressure adjusting means 57 Plasma CVD control device 59 Grounding

Claims (5)

[Claims] 1. A plasma CVD method in which at least one of a gas flow rate, a gas pressure, and a discharge power is changed after a discharge is started, and after a gas that does not cause deposition is introduced into a reaction chamber, a discharge is started, Then, a plasma CVD method, characterized in that a gas causing deposition is introduced into the reaction chamber while maintaining the discharge. 2. The plasma CVD method according to claim 1, wherein the gas that does not cause deposition is an inert gas. 3. The plasma CV according to claim 1, wherein the gas that does not cause deposition is nitrogen gas, oxygen gas, hydrogen gas, or gas having nitrogen, oxygen or hydrogen atoms in its molecule.
Method D. 4. The gas which does not cause deposition is a halogen gas or a gas having a halogen atom in its molecule.
The plasma CVD method described. 5. A plasma CVD control device for controlling discharge power, gas flow rate and gas pressure of a plasma CVD device, discharge detection means for detecting discharge in a reaction chamber and outputting a discharge detection signal, and the discharge detection signal. In response to this, clocking is started, and after a preset first time has elapsed, a gas flow rate change signal and a pressure change signal are output, and thereafter,
An output change signal is output after a preset second time has elapsed, and then a preset third signal is output.
And a timer means for outputting an output stop signal after a lapse of time, and first, when the gas flow rate change signal is received by controlling the gas flow rate to a preset first gas flow rate scheduled value, the preset value is set. Gas control means for controlling the gas flow rate to a second gas flow rate scheduled value; and first, controlling the pressure to a preset first pressure scheduled value, and receiving the pressure change signal, the preset gas pressure control means The pressure adjusting means for controlling the pressure to the planned pressure value of 2 and the output of the discharging power supply to the first preset power supply output value which is set in advance are controlled when the output change signal is received. And a power control means for stopping the output of the discharge power supply when the pressure is controlled to a second predetermined pressure value and the output stop signal is received.