JPS6319822A - Method and apparatus for dry etching - Google Patents

Abstract

PURPOSE:To facilitate etching with high speed, precision and low damage by a method wherein a resistant element is provided in parallel with a DC source and the impedance of a whole DC circuit is reduced and a self-bias voltage created by the application of a radio frequency power is controlled by selecting the proper resistance value of the resistance element. CONSTITUTION:High density plasma is generated by a microwave and a negative bias voltage to a substrate 5 is induced by a radio frequency power regardless of whether the substrate 5 is made of insulating material or of non- insulating material. A DC power is applied to a sample table 6 with the radio frequency power and, by connecting a resistance element 17 in parallel with a DC source 8, the applied value of the DC power can be controlled so that the negative bias voltage can be controlled while the applied value of the radio frequency power is kept constant. When the substrate 5 is etched, the applied value of the DC source is so predetermined as to make the negative bias voltage applied to the substrate 5 high. With this constitution, increased ion energy and orientation to the substrate 5 can be given to gas ions and etching with high speed and improved precision can be realized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a dry etching treatment method and! ! ! ! In particular, the present invention relates to a dry etching processing method and apparatus suitable for etching at high speed, with precision, and with little damage by controlling the bias voltage applied to a sample. [Prior Art] As a conventional dry etching treatment technique, for example, as described in Japanese Patent Publication No. 60-30098,
A negative voltage is applied together with high frequency power to fli, and the negative voltage is reduced to -1.
A technique has been proposed in which selective etching is performed with an etching rate ratio of 5 between Si02 and Si by applying 00QV. However, such conventional techniques do not take into consideration the possibility of damage to the element due to the application of a negative voltage.

[Problem that the invention seeks to solve]

The above-mentioned conventional technology has not been overlooked in terms of damage to the element due to ion spattering energy caused by negative voltage, and in recent years, with the increase in integration, the electrical characteristics of polished elements are severely restricted. However, there is a problem in that applying a negative high voltage may adversely affect the electrical characteristics of the device.

An object of the present invention is to provide a dry etching processing method and apparatus that can perform high-speed, precise etching with little damage by controlling the bias voltage that acts on the sample.

[Means for solving problems]

The above purpose is to perform a dry etching process by applying microwaves and a magnetic field to a discharge gas introduced into a vacuum chamber to generate plasma, and etching the surface of the sample to be processed using active particles in the plasma. and a step of applying high frequency power and direct a power to the sample table on which the sample is placed during the etching process of the surface to be processed of the sample, and the dry etching processing apparatus is equipped with a vacuum a chamber, means for depressurizing and evacuating the vacuum chamber, means for introducing discharge gas into the vacuum chamber, means for generating microwaves, means for generating a magnetic field, and the action of the microwaves and the magnetic field. a sample stage on which a sample to be etched with active particles in plasma generated by is placed;
This is achieved by providing a high frequency power source electrically connected to the sample stage and a power source independent of the high frequency power source.

[For production]

The above-mentioned conventional technology does not include a resistance element, and the negative bias voltage is controlled in such a way that the negative bias voltage is further increased from the self-bias voltage. In such conventional technology, increasing the negative bias voltage is achieved by making the negative DC voltage higher than the self-bias voltage by applying high-frequency power. In order to lower the bias voltage, it is difficult to lower the negative bias voltage of the wafer mounting electrode because it is necessary to flow a current in the opposite direction to the current flowing in order to generate negative pressure from the DC power supply.

In the present invention, the impedance of the entire DC circuit is reduced by providing a resistance element in parallel with the DC power source. Therefore, the self-bias voltage generated by applying high frequency power can be reduced by appropriately selecting the resistance value of the resistance element. As a result, the negative bias voltage can range from approximately 0 to the self-bias voltage generated by applying high-frequency power (when the resistance value of the resistance element is 0).In reality, the stability of the plasma during processing Negative bias voltage is limited to a range where the plasma condition is stable, as it may adversely affect uniform processing of the sample.The resistance value of the resistance element should be set to a negative value within a range where plasma stability can be ensured depending on the processing conditions. By applying DC power in this state, the negative bias voltage that affects the sample can be controlled from a lower negative bias voltage to a higher negative bias voltage than before. This makes it possible to widen the control range of the bias voltage compared to the conventional method.

As described above, when etching a sample, the applied value of DC power is set so that the negative bias voltage acting on the sample becomes high, and by increasing the negative bias voltage, the ion energy for gas ions and the substrate is increased. It is possible to provide enlargement and directionality, and increase the speed and precision of etching.

In addition, the applied value of DC power is suppressed at an appropriate point after the etching end point is detected, and a negative bias voltage is applied to an extent that does not impair etching precision (a shape that does not affect the electrical characteristics of the element). Perform etching while suppressing. By lowering the negative bias voltage, the energy of ions can be lowered, and element damage caused by ion energy can be reduced.

By combining the DC power supply circuit and the resistance element in this way, the control range of the negative bias voltage that acts on the specimen is expanded, and etching conditions (bias voltage) can be set according to the state of the specimen, resulting in faster and more precise etching.

Etching with low damage is possible.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1st
In the figure, a discharge gas 12 is introduced from a discharge gas introducing means (not shown) into the white part of the vacuum chamber, and a magnetron 2 is introduced into the discharge gas.
Plasma 4 is generated by interacting the microwaves generated by the magnetic field coil 3 with the magnetic field generated by the magnetic field coil 3, and active particles in the plasma 4 are used to attach a sample, such as a semiconductor element substrate (hereinafter abbreviated as substrate).
Etch the surface of 5. Note that the pressure in the vacuum chamber 1 is evacuated from the exhaust port 13 by a depressurizing exhaust means (not shown) and maintained at a predetermined value.

In addition, the sample stage 6I also includes a resistance element 17 and a high frequency power source 7.
and a DC power supply 8 are electrically connected to each other, and the coil 9
and the capacitor 10 constitute a low-pass filter 11 for preventing the high-frequency power supply 7 from affecting the DC power supply 8 .

Here, the high frequency power supply 7 biases the insulating substrate 5 negatively with respect to the plasma, and the resistance element 17 has a direct current of 1! The negative bias voltage can be controlled by combining the resistance element 17 and the DC power source 8, which are connected in parallel with the power source 8.

According to this embodiment, high-density plasma is generated by microwaves, and the substrate 5 is made of an insulating material by receiving high-frequency power.

A negative bias is generated for the substrate 5 regardless of the non-insulating material. DC power is applied to this along with high frequency power to the sample stage 6.
By connecting the resistance element 17 in parallel with the DC power source 8, it is possible to control the negative bias voltage by controlling the applied value of DC power while keeping the applied value of high-frequency power constant. Become.

When etching the substrate 5 (for example, M film), the substrate 5
The applied value of the DC power supply 8 is set so that the negative bias voltage acting on the substrate 51 is high. By increasing the negative bias voltage, it is possible to give gas ions an increase in ion energy and directionality toward the substrate 51. It is possible to increase the speed and precision of etching.

Then, at an appropriate point after the etching end point is detected, the applied DC power is suppressed, and a negative bias voltage is applied to an extent that does not impair etching precision (a shape that does not affect the electrical characteristics of the element). By lowering the etching temperature, it is possible to lower the ion energy to the base of the M film (for example, 5tO-z film, Si, etc.) and reduce element damage caused by the ion energy. It has the effect of being precise and causing low damage.

FIG. 2 is for explaining another embodiment of the present invention. FIG. The configuration is as follows. Note that in FIG. 2, other parts that are the same as those in FIG.

In this embodiment, the resistance value of the resistor element 17' can be adjusted to the optimum value according to the processing conditions, so that it is suitable for various processing conditions compared to the case of using a fixed resistor. This method has the advantage that it becomes easy to select the resistance value (resistance value that allows stable plasma to be obtained under various processing conditions), and there is no need to replace the resistance element with a suitable one.

〔Effect of the invention〕

According to the present invention, since the bias voltage applied to the sample can be controlled, the sample can be etched at high speed and with precision and with little damage.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a vacuum chamber of a dry etching processing apparatus according to an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of a vacuum chamber of a dry etching processing apparatus according to another embodiment of the present invention. It is a front view. 1...Vacuum chamber, 2...Magnetron,
3. Curved hot water coil, 4. Curved plasma, 5...
・Substrate, 6 ・Block/sample stage, 7...Block high frequency power supply, 8...
・DC power supply, 11...Low pass filter, Open heavy gas, 13...Exhaust port, 14...
・Waveguide, 15... Discharge tube, 16... Curved 41
figure

Claims (1)

[Claims] 1. A step of generating plasma by applying microwaves and a magnetic field to a discharge gas introduced into a vacuum chamber, and a step of etching the surface of the sample to be processed with active particles in the plasma. A dry etching processing method, comprising: applying high frequency power and DC power to a sample stage on which the sample is placed during the etching process of the surface to be processed of the sample. 2. A patent in which the step of applying high frequency power and DC power to the sample stage includes a step of simultaneously applying high frequency power and DC power to the sample stage, and a step of applying only high frequency power to the sample stage. A dry etching treatment method according to claim 1. 3. The dry etching processing method according to claim 1, wherein the applied value of the high-frequency power applied to the sample stage is kept constant, the applied value of the DC power is controlled, and the bias voltage applied to the sample is controlled. 4. The dry etching processing method according to claim 1, wherein after the etching end point of the sample is detected, the applied value of the DC power applied to the sample stage is controlled, and the bias voltage applied to the sample is controlled. 5. a vacuum chamber, a means for depressurizing and evacuating the vacuum chamber, a means for introducing discharge gas into the vacuum chamber, a means for generating microwaves, a means for generating a magnetic field, and the microwave and the a sample stage on which a sample to be etched with active particles in plasma generated by interaction with a magnetic field is placed; a high-frequency power source electrically connected to the sample stage;
A dry etching processing apparatus comprising: a DC power supply electrically connected to the sample stage so as to be controllable independently of the high frequency power supply; and a resistance element electrically connected to the sample stage.