JPH07211769A - Method and apparatus for plasma processing - Google Patents

Abstract

PURPOSE:To simplify the procedure for releasing electrostatic attraction and improve the throughput of plasma processing, by stopping the generation of plasma with DC voltage kept applied to a stage, and releasing a workpiece electrostatic-attracted to the stage. CONSTITUTION:When negative DC voltage is applied to a stage 6, a wafer 5 is attracted to the negative stage 6 by Coulomb force, and they are brought into tight contact with each other throughout the entire surface. The wafer 5 is held and processed for a specified time. After the completion of processing, a control unit 9 maintains the application of DC voltage to the stage 6 through a power supply 8 for electrostatic attraction, and further stops the application of high-frequency power to an electrode 2 for generating plasma through a high-frequency power supply 1 to stop the generation of plasma 4. Thus the wafer 5 is put in the same potential with the stage 6. As a result, electrostatic attractive force exerted on the wafer 5 is eliminated, and the wafer 5 is instantaneously released from the stage 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing technique, and more particularly to a technique effective when applied to a plasma processing technique in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art For example, in a semiconductor device manufacturing process,
Plasma processing is commonly used to form a thin film of a desired substance on a semiconductor substrate (wafer) and to etch the thin film. By the way, in such plasma processing of a wafer, it is important to uniformly control the temperature of the wafer during processing, and it is necessary to uniformly adhere and fix the entire surface of the wafer to a temperature-controlled stage. .

As a technique for fixing the entire wafer in close contact with the stage in this manner, for example, Japanese Patent Laid-Open No. 1-2274.
An electrostatic chuck as described in Japanese Patent No. 54, etc. is known. That is, a dielectric layer is provided on the sample table, a voltage is applied between the sample table and the wafer, and the wafer is attracted and fixed by the Coulomb force generated between the two. Further, as a method for desorbing a wafer electrostatically attracted to an electrostatic chuck, in the related art, it is described in the claims and the detailed description of the invention on pages 10 and 11 and the like. As described above, there is disclosed a method of stopping the plasma and applying a reverse DC voltage for wafer desorption (reverse voltage of the voltage used at the time of adsorption) to the electrostatic chuck for desorption.

[0004]

SUMMARY OF THE INVENTION In the above prior art,
As a method for removing the wafer electrostatically attracted to the electrostatic chuck, a static elimination step (for removing the wafer from the electrostatic chuck, which is complicated such as applying a reverse voltage and takes several tens of seconds or more) is performed. Since such a static elimination step usually requires several minutes, the processing sequence of the apparatus becomes complicated, and the throughput (the number of wafers processed per unit time) decreases. was there.

Therefore, the object of the present invention is to instantly release the electrostatic adsorption of the object to be treated with respect to the stage, so that the electrostatic adsorption releasing procedure can be simplified and the throughput in the plasma processing can be improved. To provide a simple plasma processing technology.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[0007]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, according to the first aspect of the invention, an object to be processed is placed on a stage to which a direct current voltage can be applied, the direct current voltage is applied to the stage, and plasma is formed in the vicinity of the object to be processed. In the plasma processing method, the object to be processed is attracted and fixed on the stage by electrostatic attraction, and the desired processing is performed on the object to be processed by the plasma in that state, in which the DC voltage is applied to the stage. By stopping the formation of the plasma while the voltage is applied, the electrostatic adsorption of the object to be treated with respect to the stage is released.

According to a second aspect of the invention, in the plasma processing method according to the first aspect, the DC voltage applied to the stage is reduced after the electrostatic attraction is released.
After that, the object to be processed is removed from the stage and carried out.

The invention according to claim 3 is the plasma processing method according to claim 1 or 2, wherein the object to be processed is a semiconductor wafer, and a thin film forming process or an etching process is performed on the semiconductor wafer by the plasma. It is a thing.

According to a fourth aspect of the present invention, a plasma processing chamber, a plasma forming means for forming plasma inside the plasma processing chamber, and a plasma processing chamber are provided inside the plasma processing chamber, and an object to be processed is placed on the plasma processing chamber. And a DC power supply unit that applies a DC voltage to the stage, and a control unit that controls at least the plasma forming unit and the DC power supply unit. By applying the DC voltage and forming the plasma in the vicinity of the object to be processed, a first control operation of adsorbing and fixing the object to be processed on the stage by electrostatic adsorption, and to the stage While applying the DC voltage from the DC power supply unit, by stopping the formation of the plasma,
It is provided with a control logic for performing a second control operation for releasing the electrostatic adsorption of the processing target on the stage.

According to a fifth aspect of the present invention, in the plasma processing apparatus according to the fourth aspect, the stage has a dielectric layer formed on a mounting surface of the object to be processed.

The invention according to claim 6 is the plasma processing apparatus according to claim 4 or 5, wherein the temperature control for controlling the temperature of the processing object placed on the stage is provided inside the stage. Means are provided.

The invention according to claim 7 is the same as in claim 4,
In the plasma processing apparatus of 5 or 6, the plasma forming means includes a parallel plate electrode and a high frequency power source for applying high frequency power between the parallel plate electrodes, and the stage also serves as one of the parallel plate electrodes. It is configured.

[0015]

According to the above-mentioned means, the stage becomes positive or negative potential during processing, and the object to be processed becomes the ground (GND) level through the plasma, and the dielectric layer between the object to be processed and the stage is formed. A potential difference is generated and the object to be processed is electrostatically adsorbed on the stage. After the processing is completed, the plasma is stopped while the DC voltage is applied to the stage, so that the potential of the processing target becomes the same potential as the stage, and the processing target on the stage is instantly electrostatically adsorbed. Will be released.

As a result, it is possible to omit a complicated static elimination step such as applying a DC voltage of opposite polarity to the stage, for example, in order to release the electrostatic attraction of the object to be treated, as in the conventional case, and simplify the processing sequence. Throughput can be improved by shortening the required time.

[0017]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a conceptual diagram showing an example of the configuration of a plasma processing apparatus for carrying out a plasma processing method according to an embodiment of the present invention, and FIG. 2 is a flow chart showing an example of its operation.

In the plasma processing chamber 3, a desired processing gas g
A gas supply mechanism 3a for supplying the gas and an exhaust mechanism 3b for exhausting the inside of the plasma processing chamber 3 to a desired degree of vacuum are provided. Inside the plasma processing chamber 3, there is a stage 6
Is horizontally provided, and the wafer 5 to be put in and taken out through an entrance (not shown) provided in a part of the plasma processing chamber 3 is placed thereon. A fluid passage 6a for temperature control is formed inside the stage 6, and the temperature of the wafer 5 placed on the stage 6 is reduced by, for example, a minus number by circulating a heat medium 6b having a desired temperature. It is possible to control in a temperature range of about 10 ° C to plus one hundred and several tens ° C.

A plasma generating electrode 2 connected to a high frequency power source 1 is arranged at a position facing the stage 6, and by applying high frequency power between the plasma generating electrode 2 and the stage 6,
Between the stage 6 and the plasma generating electrode 2, the processing gas g
The operation of forming plasma 4 is performed.

In this case, the stage 6 has a D for electrostatic attraction.
A C power source 8 is connected, for example, a negative DC voltage can be applied, and a dielectric layer 7 is provided on the mounting surface of the wafer 5 on the stage 6.
The wafer 5 is placed in a state of being electrically insulated from the stage 6. The dielectric layer 7 is made of a dielectric material such as ceramics.

DC power source 8 for electrostatic attraction and high frequency power source 1
Is connected to the control unit 9, and the control operation in cooperation with the both is possible. In addition, the control unit 9 is provided with control logic for performing a series of control operations as illustrated in the flowchart of FIG.

An example of the operation of the plasma processing method and apparatus of this embodiment will be described below with reference to the flow chart of FIG.

First, the wafer 5 is loaded into the plasma processing chamber 3 and placed on the stage 6 (step 21).

Thereafter, the inside of the plasma processing chamber 3 is evacuated to a predetermined degree of vacuum and the processing gas g is supplied (step 22).

Further, by applying a relatively low high frequency power from the high frequency power source 1 between the plasma generating electrode 2 and the stage 6, the plasma 4 is formed (step 2).
3). At this time, the wafer 5 on the stage 6 is brought to the ground potential via the plasma 4, for example.

In this state, when a negative DC voltage of, for example, about 300 to 500 V is applied to the stage 6 from the electrostatic attraction DC power source 8, the stage 6 and the wafer 5 are
A potential difference is generated in the dielectric layer 7 interposed between the wafer 5 and
Are adsorbed by the Coulomb force to the negative stage 6 and are in close contact with the entire surface (step 24) (first control operation).

In this way, the whole of the wafer 5 adhered to the stage 6 is the heat medium 6b which flows through the inside of the stage 6.
Uniform and accurate control of temperature.

In such a state, the high frequency power applied from the high frequency power source 1 to the plasma generating electrode 2 is increased to the level of the normal processing mode, and the excited state of the plasma 4 is further increased to, for example, the wafer 5. Etching and thin film formation processing is executed (step 25).

When the processing on the wafer 5 is completed while maintaining the state of step 25 for a predetermined time (step 2
6) In the present embodiment, the control unit 9 controls the high frequency power from the high frequency power source 1 to the plasma generating electrode 2 while maintaining the application state of the DC voltage from the electrostatic attraction DC power source 8 to the stage 6. The application is stopped and the formation of plasma 4 is stopped (step 27). As a result, the wafer 5 has the same potential as the stage 6, the electrostatic attraction force acting on the wafer 5 disappears, and the attraction state of the wafer 5 to the stage 6 is instantly released (second control operation).

Thereafter, the supply of the processing gas g to the plasma processing chamber 3 is stopped (step 28), and the DC voltage applied to the stage 6 from the electrostatic attraction DC power source 8 is changed to, for example, 50. The voltage is reduced to about 100 V (step 29), the wafer 5 is unloaded from the stage 6 (step 30), and the electrostatic attraction DC power supply 8 is turned off (step 31).

As described above, according to the plasma processing method and apparatus of the present embodiment, the formation of the plasma 4 is stopped while the DC voltage from the electrostatic attraction DC power supply 8 is still applied to the stage 6. Since the electrostatic attraction state of the wafer 5 to the stage 6 is instantly released by a simple operation, for example, as in the conventional case, a reverse polarity DC voltage for releasing the electrostatic attraction is applied to the stage 6 or the like. A complicated static elimination step can be omitted, and the throughput can be improved by simplifying the processing sequence and shortening the required time.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. Needless to say.

For example, the plasma forming means is not limited to the parallel plate electrode system exemplified in the above-mentioned embodiment, and for example, a microwave generating means for sending a microwave into the plasma processing chamber and a magnetic field inside the plasma processing chamber. The plasma forming means may be configured by the magnetic field forming means to be formed, and the plasma may be formed by the interaction between the microwave and the magnetic field.

[0035]

The outline of typical ones of the inventions disclosed in the present application will be briefly described as follows.

That is, according to the plasma processing method of the present invention, the complicated static elimination step for desorbing the processing object electrostatically adsorbed on the stage can be omitted, so that the throughput can be improved. Further, the processing sequence of the entire plasma processing process can be simplified.

Further, according to the plasma processing apparatus of the present invention, the complicated static elimination step for desorbing the processing object electrostatically adsorbed on the stage can be omitted, so that the throughput can be improved. Further, the processing sequence of the entire plasma processing process can be simplified.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a plasma processing apparatus in which a plasma processing method according to an embodiment of the present invention is implemented.

FIG. 2 is a flowchart showing an example of the operation.

[Explanation of symbols]

1 High Frequency Power Supply (Plasma Forming Means) 2 Plasma Generation Electrode (Parallel Plate Electrode: Plasma Forming Means) 3 Plasma Processing Chamber 3a Gas Supply Mechanism 3b Exhaust Mechanism 4 Plasma 5 Wafer (Processing Object) 6 Stage (Parallel Plate Electrode) 6a Fluid passage (temperature control means) 6b Heat medium (temperature control means) 7 Dielectric layer 8 DC power supply for electrostatic adsorption (DC power supply part) 9 Control part g Processing gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuru Ogasawara, 3-3 Fujibashi, Ome, Tokyo 2-3 Hitachi Tokyo Electronics Co., Ltd. (72) Hiroshi Marumoshi 3-3, Fujibashi, Ome, Tokyo 2 Hitachi-Higashi Inside Kyo Electronics Co., Ltd.

Claims (7)

[Claims] 1. A process target is placed on a stage to which a DC voltage can be applied, the DC voltage is applied to the stage, and plasma is formed in the vicinity of the process target by electrostatic adsorption. A plasma processing method for adsorbing and fixing the object to be processed on the stage, and performing a desired process on the object to be processed by the plasma in that state, while applying the DC voltage to the stage, By stopping the formation of plasma,
A plasma processing method, wherein electrostatic attraction of the processing object to the stage is released. 2. After the electrostatic attraction is released, the DC voltage applied to the stage is lowered, and then the object to be processed is removed from the stage and carried out. The plasma processing method described. 3. The processing object is a semiconductor wafer,
The plasma processing method according to claim 1, wherein a thin film forming process or an etching process is performed on the semiconductor wafer by the plasma. 4. A plasma processing chamber, a plasma forming means for forming a plasma inside the plasma processing chamber, a stage provided inside the plasma processing chamber, on which an object to be processed is placed, and a stage on which the processing target is placed. A plasma processing apparatus comprising: a DC power supply unit for applying a DC voltage; and a control unit for controlling at least the plasma forming unit and the DC power supply unit, wherein the control unit applies the DC voltage to the stage. At the same time, by forming the plasma in the vicinity of the object to be processed, the object to be processed is attracted and fixed on the stage by electrostatic attraction.
A second control operation, and the electrostatic attraction of the object to be treated to the stage is released by stopping the formation of the plasma while applying the DC voltage from the DC power supply unit to the stage. A plasma processing apparatus having a control logic for performing the control operation of 1. 5. The plasma processing apparatus according to claim 4, wherein the stage has a dielectric layer formed on a mounting surface of the object to be processed. 6. The plasma processing according to claim 4, wherein temperature control means for controlling the temperature of the object to be processed placed on the stage is provided inside the stage. apparatus. 7. The plasma forming means includes a parallel plate electrode and a high frequency power source for applying high frequency power between the parallel plate electrodes, and the stage also serves as one of the parallel plate electrodes. Claims 4 and 5 characterized
Alternatively, the plasma processing apparatus of item 6.