JP3662293B2 - Etching electrode - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an etching electrode used for etching a substance on a substrate such as a semiconductor device using plasma.
[0002]
[Prior art]
Conventionally, as an etching apparatus, a cathode capacitive coupling type (generally called RIE), a magnetic field RIE type, an inductive coupling type using a high frequency coil, a μ wave discharge type, a magnetic field μ wave discharge type (including ECR), The helicon wave type, etc. are known (Akihiro Horiike, Haruo Shindo: “Attempt to review the plasma source for etching from the beginning”, Nikkei Microdevices, October 1991, page 89). In either apparatus, a high frequency bias is applied to the etching electrode on which the substrate is mounted, a negative self-bias is generated on the substrate using a blocking capacitor, and the resulting voltage is applied as an acceleration voltage to ions generated in the plasma. As a result, the ions collide with the substrate and the substrate is etched. When the high frequency bias applied to the etching electrode is at a relatively low frequency, ions can move following the frequency, so that an acceleration voltage can be applied to the ions only by the high frequency voltage, and a blocking capacitor is not necessarily required. .
[0003]
The apparatus shown in FIG. 1 is a magnetic field RIE type etching apparatus, and a substrate d to be etched on a holding table c made of a dielectric material such as quartz or alumina on an etching electrode b provided in a vacuum processing chamber a. And a counter electrode f having a hole e for uniformly ejecting the process gas introduced from the gas introduction hole so as to face the etching electrode b is provided, and a high frequency power source g is connected to the electrode b to connect the high frequency plasma. Is generated. In the figure, h is a permanent magnet for rotating outside the vacuum processing chamber a to constrain the plasma to the front surface of the counter electrode f and perform magnetron etching, and j is a vacuum exhaust port.
[0004]
The apparatus shown in FIG. 2 is a high-frequency inductively coupled etching apparatus, and a plasma generating high-frequency electric field connected to a high-frequency power source m other than the high-frequency power source g of the etching electrode is used as a dielectric partition. The difference is that a high-frequency antenna k for introduction through i is provided on the outer periphery of the vacuum processing chamber a. The substrate d is carried into and out of the vacuum processing chamber a by a transfer means such as an automatic transfer arm (not shown). The details of the holding table c of these devices are as shown in FIG. 3, and the surface on which the substrate d is placed is formed flat. The frequency of the high frequency of the high frequency antenna k is arbitrary, and the plasma generation source may be a μ wave. Further, the frequency of the high frequency applied to the etching electrode b is not limited to 13.56 MHz, and may be a higher frequency, for example 27.12 MHz, or a frequency of several hundreds of kHz.
[0005]
[Problems to be solved by the invention]
The apparatus shown in FIGS. 1 and 2 evacuates the inside of the vacuum processing chamber a to an appropriate vacuum pressure and introduces a process gas to energize the etching electrode b and the high-frequency antenna k from the high-frequency power sources g and m. Plasma is generated in front of the counter electrode f. Ions generated by the decomposition of the process gas enter the substrate d on the etching electrode b which has become a negative voltage due to self-bias, and the substrate d is etched. If the gas is Ar gas, the substrate d is etched and cleaned, and if CF ₄ gas is used, the SiO ₂ substrate can be etched.
[0006]
When the etching process is performed with the conventional apparatus having such a configuration, an electrostatic force generated between the substrate d and the dielectric holding table c causes an electrostatic adsorption force even after the discharge is completed, and the substrate d is adsorbed to the holding table c. There has been a disadvantage that the substrate d is removed from the holding table c and cannot be transported. The cause of such a situation is that the substrate d and the holding table c have different potentials due to the inflow of charged particles from the plasma and the difference in the secondary electron generation rate, and this potential difference is large. This is because a strong electrostatic attraction force acts between the substrate d and the substrate d remains strongly adsorbed to the holding table c even if the plasma disappears. Attempts were made to transport the adsorbed substrate d, and the substrate d was damaged by the application of a force opposite to the adsorbing force, making it difficult to convey.
[0007]
In the conventional etching apparatus, since the RF bias power applied to the substrate d is low and the charge-up phenomenon does not occur in the substrate portion, the above situation has not occurred. Since the etching rate is required and a high substrate bias power is applied, it has surfaced as a problem.
[0008]
As a method of preventing potential difference between the substrate and its holding part, the substrate and the holding part are made of the same material and the specific resistance is made equal, or after the etching is finished, the bias power supply is turned off while the plasma generating power supply is in operation. However, the former method is not preferable because it causes metal contamination and impurity contamination on the substrate, and the latter method is not preferable in terms of throughput, and it is difficult to adopt either method as an etching apparatus. .
[0009]
It is an object of the present invention to provide an etching electrode that can avoid the influence of electrostatic attraction force that does not reduce the throughput and that does not cause contamination of the substrate.
[0010]
[Means for Solving the Problems]
In the present invention, a substrate is placed on a dielectric holding table on an etching electrode provided in a vacuum processing chamber to which a high frequency bias is applied from a high frequency power source, and plasma generated by μ waves or high frequencies is generated in the vacuum processing chamber. In the etching electrode of an apparatus for etching the substrate by applying a high frequency bias to the etching electrode, at least three protrusions having a height that does not allow plasma generated for etching to enter the surface are provided on the holding table surface, The substrate is supported on the protrusions formed at a height not affected by the electrostatic attraction force due to the potential difference generated between the substrate and the holding table, so that the above object is achieved. did.
[0011]
[Action]
When process gas is introduced into the vacuum processing chamber to adjust to an appropriate vacuum pressure, the substrate is placed on a holding table, and high frequency plasma is generated while the etching electrode is biased with high frequency, ions in the plasma enter the substrate and are high The substrate is etched at the etching rate. At this time , an electrostatic force is generated between the substrate and the holding table due to the potential difference, but at least three protrusions having such a height that plasma generated for etching does not enter are provided on the surface of the holding table. In addition, since the substrate is placed on the protrusion formed so as not to generate an electrostatic adsorption force between the substrate and the holding table, the substrate has an electrostatic adsorption force with the holding table. And can be removed from the holding table without deteriorating impurity contamination or throughput.
[0012]
【Example】
An embodiment of the present invention will be described with reference to FIG. 4. Reference numeral 1 denotes an etching electrode, to which a high frequency bias is applied by a high frequency power source (not shown). On the etching electrode 1, a holding table 3 made of a dielectric material such as quartz or alumina provided with a recess 2 is provided, and a substrate 4 to be processed is placed in the recess 2. Protrusions 5 for supporting the substrate 4 are provided at at least three locations on the surface 3a of the holding table 3 at such a height that plasma generated for etching does not enter. If the height from the surface 3a of each projection 5 and 0.1 to 1 mm, since there is no entering plasma between the substrate 4 placed on this, also sufficient self-bias voltage is generated in the substrate 4 And can be etched . In addition, the substrate 4 is not affected by the electrostatic adsorption force caused by the potential difference generated between the holding tables 3, and the substrate 4 can be removed from the holding table 3 with a slight force. The substrate 4 can be stably held by forming the projections 5 by dispersing them so as to form a square shape. Note that the shape of the protrusion 5 is arbitrary, such as a spherical shape, a cylindrical shape, or a sharp shape.
[0013]
The etching electrode 1 having the holding table 3 is provided, for example, in the inductive coupling type etching apparatus shown in FIG. 5, and can be subjected to the etching process similar to the conventional one on the substrate 4. In FIG. Indicates a vacuum processing chamber provided with a vacuum exhaust port 7, the etching electrode 1 is provided below the vacuum processing chamber 6, and a counter electrode 9 having a porosity connected to the process gas introduction port 8 is provided above the etching electrode 1. Reference numeral 10 denotes a high-frequency power source for the high-frequency antenna 11 for generating plasma, and 12 denotes a high-frequency power source for biasing the etching electrode 1 at a high frequency.
[0014]
Ar gas was introduced into the vacuum processing chamber 6 and sputter etching was performed by applying a high frequency of 13.56 MHz from each of the high frequency power supplies 10 and 12 in a pressure range from 50 mPa to 1000 mPa. The adsorption phenomenon did not occur. Further, even when the substrate 4 was etched through the reliability test of 1000 sheets, the adsorption phenomenon due to the charge-up never occurred, and the substrate transfer trouble did not occur.
[0015]
【The invention's effect】
As described above, according to the present invention, the height of the plasma generated for etching does not enter the surface of the dielectric substrate holder on the etching electrode that is subjected to high-frequency biasing and high-frequency plasma etching on the substrate. The projection is formed at a height that is not affected by the electrostatic attraction caused by the potential difference generated between the substrate and the holding table , and the substrate is supported on the projection. since then, the substrate is not contaminated, since the substrate is positioned outside the area of influence of the electrostatic adsorption force, can be removed taking the substrate from the holder without damage, productivity since throughput is not reduced Also has an effect of improving.
[Brief description of the drawings]
FIG. 1 is a cutaway side view of a conventional magnetic field RIE type etching apparatus. FIG. 2 is a cutaway side view of a conventional high frequency inductive coupling type etching apparatus. FIG. 3 is an enlarged view of an etching electrode portion having a conventional holding table. Sectional view [FIG. 4] Cut-off side view of the embodiment of the present invention [FIG. 5] Cut-off side view of the use state of the etching electrode of the present invention [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Etching electrode, 3 Holding stand, 4 Substrate, 5 Protrusion, 6 Vacuum processing chamber.

Claims (2)

A substrate is placed on a dielectric holder on an etching electrode that is provided in a vacuum processing chamber and to which a high-frequency bias is applied from a high-frequency power source, and plasma generated by μ waves or high-frequency waves is generated in the vacuum processing chamber, and the etching electrode is In an etching electrode of an apparatus for biasing and etching the substrate, at least three protrusions having a height that does not allow plasma generated for etching to enter the substrate are provided on the surface of the holding table. An etching electrode , wherein the substrate is supported on the protrusion formed to a height not affected by an electrostatic attraction force due to a potential difference generated between the first electrode and the second electrode.   The etching electrode according to claim 1, wherein the protrusion has a height of 0.1 to 1 mm.

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