JP2842908B2 - Plasma process equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] The present invention relates to a plasma CV in a semiconductor manufacturing process.
With respect to a plasma process apparatus suitable for D, etc., an object of the present invention is to provide a highly controllable and highly reliable plasma process apparatus. In a plasma processing apparatus in which a semiconductor plasma process is performed using the gas that has been converted into plasma, a voltage applied between the pair of electrodes is set to be slightly lower than a discharge sustaining voltage, and The discharge start of the source gas in the applied state is controlled by irradiation of a predetermined short-wavelength light beam.

[Industrial applications]

The present invention relates to a plasma CV in a semiconductor manufacturing process.
The present invention relates to a plasma processing apparatus suitable for D or the like.

2. Description of the Related Art Plasma process apparatuses are widely used for plasma CVD and the like in a semiconductor manufacturing process. However, with recent miniaturization of LSIs, controllability and reliability thereof have been demanded.

[Conventional technology]

A plasma processing apparatus generates a discharge between a pair of electrodes in a reaction chamber filled with a raw material gas to convert the raw material gas into plasma, and performs a semiconductor plasma process such as plasma CVD using the plasmaized gas. Things.

Conventionally, generation of plasma in a plasma processing apparatus has been controlled by applying a voltage equal to or higher than a plasma critical voltage between a pair of electrodes and causing a source gas to self-discharge.

For this reason, the discharge starting conditions and the discharge path greatly depend on the geometric structure of the apparatus, and the controllability and reliability of the process have been conventionally ensured by experience, trial and error.

However, with recent advances in LSI miniaturization, methods that rely on such experience and intuition are no longer able to follow the demands of the process side. Although attention has been paid to its development, it has not yet been put to practical use.

[Problems to be solved by the invention]

As described above, the generation of plasma in a conventional plasma process apparatus is controlled by increasing the voltage applied between a pair of electrodes to a level equal to or higher than the plasma critical voltage. The controllability and reliability of the process have been ensured through experience, trial and error, and it has become impossible to follow the recent demand for finer LSIs.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a plasma processing apparatus having high controllability and high reliability.

[Means for solving the problem]

According to the present invention, in order to achieve the above object, in a reaction chamber filled with a source gas, a discharge is caused between a pair of electrodes to convert the source gas into a plasma, and a semiconductor plasma is formed by using the plasma-converted gas. In the plasma processing apparatus configured to perform the process, the voltage applied between the pair of electrodes is set to be slightly lower than the discharge sustaining voltage, and the start of discharge of the source gas in the voltage applied state is determined by a predetermined short-wavelength light. Is controlled by the irradiation of light.

[Action]

According to such a configuration, the discharge occurs only during the period of light irradiation, and disappears with the interruption of the light, and the discharge occurs only between the electrodes around the optical path. Further, the discharge starting voltage / discharge sustaining voltage is reduced to a fraction of that of the conventional device.

〔Example〕

 FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

In this embodiment, the present invention is applied to an ordinary parallel plate type plasma processing apparatus in which a wafer is placed on an anode electrode.

As shown in FIG. 1, an anode electrode 1 and a cathode electrode 2, which are a pair of parallel flat electrodes, are provided in a reaction chamber filled with a raw material gas. Is placed on the wafer 3. In the drawing, reference numeral 4 denotes the lines of electric force.

A DC power supply 5 is applied between the pair of electrodes 1 and 2. The value of the applied voltage of the DC power supply 5 is set lower than the discharge starting voltage and the discharge sustaining voltage in a state where no short-wavelength light described later exists.

A light source 6 is provided on one side of the reaction chamber, and a light beam 7 from the light source 6 is set so as to pass through a space between the electrodes 1 and 2 in parallel with the electrodes.

Further, as the light beam 7, a short-wavelength light beam having a shorter wavelength than ultraviolet light is used so that the source gas can be ionized.

Further, as the light source 6, an appropriate light source such as a lamp, a laser, and a radiation light is used.

According to the above configuration, when the DC power supply 5 is applied between the pair of electrodes 1 and 2 and the light source 7 irradiates the light 7 in this state, the material The discharge of the gas generates a plasma 8 and this discharge state disappears with the interruption of the light beam 7.

For this reason, when performing the plasma CVD on the wafer 3 on the anode electrode 1, the generation and disappearance of the plasma 8 can be controlled with high precision, thereby making it possible to cope with, for example, a VLSI process.

The value of the DC power supply 5 applied between the electrodes 1 and 2 is several hundred volts DC or higher or a high frequency
This can be reduced to about several times lower than that of the conventional device which has to apply the microwave number kv or more.

Further, since the start and end of the process are controlled by turning on and off the light, the instability at the time of initial and end peculiar to the plasma process is eliminated.

Further, since the discharge power is external irradiation light, there is no change over time in the process conditions due to contamination of the electrodes.

Further, since the applied voltage does not cause discharge without light, there is no instability such as fluctuation of discharge to the reaction chamber wall.

Next, FIG. 2 is a diagram showing a configuration of a second embodiment of the present invention.

The same components as those in the embodiment of FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

The feature of the second embodiment is that the substrate 7 is simultaneously excited by light by irradiating the wafer 3 with a light beam 7 as a discharge power source vertically.

Next, FIG. 3 is a diagram showing a configuration of a third embodiment of the present invention.

In the figure, the same components as those in the embodiment shown in FIG. 1 are denoted by the same reference numerals, and redundant description is omitted.

The feature of the third embodiment is that when a plurality of source gases are alternately supplied by MOCVD or the like, a discharge is generated synchronously only when a specific source gas is supplied.

That is, a shutter is provided in front of the raw material gas inlets 9 and 10.
11 and 12 are provided, and a shutter 13 is also provided on the front surface of the light source 6.

The shutters 11 to 13 are controlled to be opened and closed as appropriate in accordance with the source gas inlets 9 and 10 by the control of the synchronization circuit 14.

According to such a configuration, even if a combination of raw materials cannot be sufficiently decomposed under the same process conditions, a desired process operation can be performed by appropriately irradiating and blocking the light beam 7.

Next, FIG. 4 is a diagram showing a configuration of a fourth embodiment of the present invention,
FIG. 5 is an operation explanatory view of the second embodiment.

In the figure, the same components as those in the embodiment of FIG. 1 are denoted by the same reference numerals, and the description is omitted.

The feature of the fourth embodiment is that a discharge is generated in synchronization with an applied alternating voltage in a high-frequency plasma process.

According to this embodiment, the generation and disappearance of the discharge up to several hundred Hz can be made to follow the alternating voltage by turning on and off the light. If the discharge is generated only when the cathode electrode 1 is at the negative voltage, the electron to the wafer 3 will The impact can be eliminated, and damage to the substrate (wafer 3) can be reduced as much as possible.

〔The invention's effect〕

As apparent from the above description, according to the present invention, the discharge power is determined from the external irradiation light, and the applied voltage is kept lower than the discharge start / discharge maintenance voltage in the absence of light. The region where the discharge occurs can be limited only between the optical path and the electrode, and contamination, damage, and instability due to discharge occurring in unnecessary places can be eliminated.

Also, the geometric arrangement such as the electrode spacing does not have to satisfy the discharge start / discharge maintenance conditions, and thus can be freely selected.

In addition, it is stable because the discharge power is externally controlled, has a low inter-electrode voltage, alleviates damage, and has excellent effects such as being able to turn on and off discharge quickly and stably. It is.

[Brief description of the drawings]

 1 is a block diagram of the first embodiment, FIG. 2 is a block diagram of the second embodiment, FIG. 3 is a block diagram of the third embodiment, FIG. 4 is a block diagram of the fourth embodiment, FIG. The figure is a diagram for explaining the operation of the fourth embodiment. DESCRIPTION OF SYMBOLS 1 ... Anode electrode 2 ... Cathode electrode 3 ... Wafer 4 ... Line of electric force 5 ... DC power supply 6 ... Light source 7 ... Light beam 8 ... Plasma 9 ... Source gas inlet 10 ... Source gas introduction Mouth 11 Shutter 13 Shutter 14 Synchronous circuit 15 High-frequency power supply 16 Synchronous circuit

──────────────────────────────────────────────────の Continuation of front page (51) Int.Cl. ⁶ identification code FI H01L 21/31 H01L 21/302 C (58) Field surveyed (Int.Cl. ⁶ , DB name) C23C 16/00-16 / 56 C23F 4/00-4/04 H01L 21 / 205,21 / 31,21 / 302 H05H 1/46

Claims (1)

(57) [Claims] In a reaction chamber filled with a raw material gas,
In the plasma processing apparatus, a discharge is generated between the pair of electrodes (1, 2) to convert the raw material gas into plasma, and a semiconductor plasma process is performed using the plasma-converted gas. A plasma processing apparatus characterized in that the applied voltage is set slightly lower than the discharge sustaining voltage, and the start of discharge of the source gas in the voltage applied state is controlled by irradiation of a predetermined short-wavelength light beam (7).