JP2607276B2 - Dry etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Constitution of the Invention] (Field of Industrial Application) The present invention relates to a dry etching method.

(Prior art) In recent years, the density of electronic elements has been rapidly increasing, and for example, DRAM
For example, 1MDRAM is currently mass-produced,
In the future, 4MDRAM, 16MDRAM and higher density will be indispensable.

Here, up to 1 MDRAM, for example, when obtaining a capacitor of a predetermined capacity, the etching opening area on the wafer can be made relatively large, and the etching depth is about 0.3 μm.
With a high-density element higher than MDRAM, it is impossible to occupy such an opening area, and it is necessary to maintain a small opening area and form a trench structure that is dug down by several μm in the depth direction of the wafer. There is an urgent need to improve the technology for mass production of trench etching.

(Problems to be Solved by the Invention) When the above-mentioned trench etching is put into practical use,
One important requirement must be met.

First, when performing trench etching first,
It is necessary to perform anisotropic etching, and it is necessary to minimize the side etch as shown in FIG. In other words, the side etching was not so problematic at the conventional etching depth of about 0.3 μm,
This is because the adverse effect of the side etch cannot be ignored when m is also etched.

Next, if the anisotropic etching rate for obtaining a trench having a depth of several μm is small, the throughput is poor, so it is necessary to secure the etching rate to a predetermined value or more.

However, conventionally, a dry etching method that satisfies both of the above two requirements has not been provided.
This has been a problem in mass-producing high-density elements such as.

Therefore, an object of the present invention is to solve the above-described conventional problems, and to form a trench having an aspect ratio of 1 or more, in which side etching is reduced and a predetermined etching rate is secured. It is to provide an optimal dry etching method for the above.

[Constitution of the Invention] (Means for Solving the Problems) According to the present invention, a material to be etched is arranged on one of the parallel plate electrodes, and a trench having an aspect ratio of depth / opening width of 1 or more is formed in the material to be etched. In performing anisotropic dry etching for forming, dry etching is performed by using any element gas other than He and Ne among elements belonging to Group 0 as an additive gas.

In particular, the invention of claim 1 is characterized in that SF6, O2, and Kr are supplied such that the partial pressure ratio of SF6: O2: Kr is about 1: 1: 2.

A second aspect of the present invention is characterized in that the dry etching is performed under the condition that the pressure in the reaction chamber is 0.3 Torr or more.

The invention according to claim 3 is that the partial pressure ratio of SF6, O2, Kr is changed by changing the flow rate of SF6 or O2 with respect to a reference partial pressure ratio in which the partial pressure ratio of SF6: O2: Kr is 1: 1: 2. Is changed to control the trench etching shape.

The invention of claim 4 is a dry etching method in a triode type etching apparatus in which a grounded grid electrode is arranged between the first electrode and the second electrode to which RF power is supplied. The present invention provides SF6, O2, Kr so that the partial pressure ratio of SF6: O2: Kr is about 1: 1: 2, and
It is characterized in that the ratio of the RF power supplied to the electrode or the magnitude of the RF power is changed to control the trench etching shape.

(Operation) In the present invention, when performing trench etching with an aspect ratio of 1 or more, H of the elements belonging to Group 0 is used.
Element gases other than e and Ne are used as additive gases for etching.

Explaining the improvement of the etching rate by using such a gas, the additive gas acts in three directions to improve the etching rate.

First, each of the additive gases has a relatively small ionization energy, for example, 16 eV for Ar gas and 14 eV for Kr gas. Therefore, ionization is easy between the parallel plate electrodes.

Here, the material to be etched disposed on one of the parallel plate electrodes has a negative potential due to a self-bias effect at the time of application of a high-frequency voltage, and the ionized additive gas, for example, Kr ^+, is applied to the material to be etched at a negative potential. It moves and sputters the material to be etched to promote etching and contribute to improving the etching rate.

For example, when SF6 is used as an etching gas, it is decomposed into F ^* (fluorine radical) which is a free atom in a plasma electric field, causing a chemical reaction with Si constituting a silicon substrate which is an example of a material to be etched, and Si + F ^* → Although Si etching is performed by SiF4 ↑, F ^* may be attached to the Si layer without any energy on the Si layer. At this time, the above chemical reaction does not occur, and etching may not be performed.

Here, when Kr ⁺ collides with the above attached F ^* , F ^*
Is given energy, and the above-mentioned chemical reaction is carried out to contribute to the etching. Such an action is referred to as ion assist. Such an ion assist is promoted by the additional gas which is easily ionized, and the etching rate can be increased. It should be noted that such ion assist is effective for imparting energy because the kinetic energy is larger for an element having a larger mass, and such an action cannot be expected for He and Ne. Runs well.

Since the above-mentioned additive gas is easily ionized, it is also effective in stabilizing and homogenizing the discharge. Therefore, a high pressure (for example, 0.3 Torr or more, preferably 0.5
Even under (about Torr), uniform and stable discharge can be obtained. Then, under such a high pressure, the number of reactive species increases, so that the etching rate can be improved.

Next, a description will be given of the anisotropic etching effect of reduced side etch due to the additional gas.In a plasma in which uniform and stable discharge can be obtained even under a relatively high pressure, many additional gas ions such as Kr ⁺ are generated, And this Kr ⁺
Moves along the electric field in the parallel plate electrode and collides straight with the material to be etched, thereby promoting the etching by the above-mentioned action. Therefore, since the direction of the ionized gas is perpendicular to the material to be etched,
Even when etching is performed deeply like a trench, side etching is reduced, and suitable anisotropic etching can be performed.

If O2 is also used as an additive gas, the effect of oxidizing the trench side wall and preventing side etching can be obtained.

According to the first aspect of the invention, by setting the partial pressure ratio of SF6: O2: Kr to about 1: 1: 2, the trench etching shape can be optimized so that the side wall of the trench etching becomes almost vertical, Moreover, the etching rate can be kept high while reducing the consumption of Kr, and as a result, practical trench etching with high anisotropy becomes possible.

According to the invention of claim 2, the pressure in the reaction chamber is set to 0.3 Torr.
By doing so, the etching rate and the selectivity are further improved as compared with the other pressure ranges, and there is an effect that the trench etching shape can be formed into a positive taper that can easily fill the hole later.

According to the third and fourth aspects of the present invention, the flow rate of SF6 or O2 is changed with respect to a reference partial pressure ratio in which the partial pressure ratio of SF6: O2: Kr is 1: 1: 2, or a triode type etching apparatus. By changing the RF power ratio or the magnitude of the RF power supplied to the first and second electrodes, it is possible to easily set the process conditions for optimizing the trench etching shape.

(Example) Hereinafter, an example in which the present invention is applied to trench etching for obtaining a 4MDRAμ capacitor will be specifically described with reference to the drawings.

First, a dry etching apparatus will be described with reference to FIG.

As a feature of this dry etching apparatus, three electrodes, an upper electrode 1, a grid 2, and a lower electrode 3, which are respectively arranged in parallel, are provided in a chamber 6, and the grid 2 is grounded. Adopts a triode etching method in which RF power supplies 4 and 5 are connected respectively.

With such a configuration, the degree of freedom of the process parameters can be increased, and the plasma etcher and RIE (React
ive Ion Etching), making it possible to perform etching with both advantages.

Further, in this apparatus, an etchant is mainly generated by the discharge between the upper electrode 1 and the grid 2, and the discharge here does not directly contact the wafer 7 placed on the lower electrode 3. High power can be applied without causing damage, and high-density plasma can be generated.

In the discharge between the grid 2 and the lower electrode 3, generation of an etchant and control of ion energy are performed.

As described above, there is a great advantage of the triode system in that generation of an etchant and control of ion energy can be performed independently.

 Hereinafter, each component of the present apparatus will be described.

<Regarding Upper Electrode 1 and Grid 2> The upper electrode 1 is shaped like a shower head, and has, for example, about 3500 holes with a diameter of 1 mm in a predetermined range so that gas can be uniformly extracted. . Further, a cooling system in which a cooling liquid circulates inside the upper electrode 1 is employed.

The RF power from the RF power supply 4 is supplied from a matching box (not shown) to the electrodes via a copper plate. The grid 2 is attached to the upper electrode 1 with the insulating ring 1a interposed therebetween as a spacer.

The grid 2 is directly connected to the inner wall of the chamber 6,
The earth is taken integrally with the chamber 6. The grid 2 has about 100 holes having a diameter of 5 mm in a predetermined range.

The gap between the upper electrode 1 and the grid 2 can be adjusted by replacing the insulating spacer.

<Regarding Lower Electrode 3> The lower electrode 3 is sized so that, for example, an 8-inch wafer can be placed thereon. When using a wafer 7 having a size of 8 inches or less, a focus ring (not shown) is used. Can be attached.

A load lock chamber 8 is provided on the lower electrode 3.
A wafer lift (not shown) is provided for setting the wafer 7 from the above. The lower electrode 3 is also capable of circulating cooling water inside the electrode, similarly to the upper electrode 1. Further, the supply of the RF power to the lower electrode 3 is performed by extending the lower electrode terminal to the lower part of the chamber 6 and connecting an RF cable thereto.

The gap between the lower electrode 3 and the grid 2 can be adjusted by manually raising and lowering the lower electrode 3.

<Regarding the Exhaust System> An exhaust port 10 is provided at the lower part of the chamber 6, and the exhaust port 10 has an APC (Auto Pressure
Control) valve 11, conductance valve 12, turbo molecular pump (TMP) 13 and rotary pump (RP) 14 are connected to each other. In addition, a rotary pump (R.
P) 16 is connected.

<Gas supply system> As a gas supply system, in the present embodiment, O2, Kr, N2 and two kinds of etching gases can be introduced into the chamber 6, and the supply flow rate of each gas system is a mass flow controller (MFC). It can be controlled by 18.

Next, an embodiment of the method of the present invention using the above-described embodiment apparatus will be described.

In this example, dry etching was performed under the following various conditions.

First, SF6 was used as an etching gas, and O2 and Kr belonging to Group 0 were used as an additive gas.

 The flow rate was SF6: 110 cc / min O2: 90 cc / min Kr: 200 cc / min. That is, the partial pressure ratio is about 1: 1: 2.

The various parameter conditions of the apparatus are as follows.

Pressure: 0.5Torr RF power ・ Upper electrode 1 → 13.56MHz, 400W ・ Lower electrode 3 → 13.56MHz, 200W Gap between electrodes ・ Upper electrode 1-Grid 2: 1cm ・ Lower electrode 3-Grid 2: 4cm Grid 2 Opening area: φ125mm Under the above conditions, a Si wafer 20 as shown in FIG.
A mask material 22 of SiO2 was formed with the opening width shown in the figure, and dry etching was performed. The etching characteristics at this time were as follows.

・ Etching rate = 2 μm / min ・ Selection ratio (vs. SiO 2) = 40.6 Here, for practical use of trench etching, an etching rate of 1 to 1.5 μm / min and a selection ratio of 15 or more are required. The results all clear this.

Further, the etching shape after the lapse of the etching time of 2.5 minutes is as shown in FIG. 3, and the shape is close to a U-shape, which is ideal with a large R at the bottom. About 5μm etching, about 0.
Although a side etch of about 25 μm occurs, the angle of the entrance of the trench becomes obtuse due to the entry of the side etch, and is slightly tapered. Therefore,
With such a side etch, this can be used for controlling the taper of the trench side wall and removing the angle of the entrance.

By controlling the gas ratio of SF6 / O2 / Kr and the power ratio between the upper electrode 1 and the lower electrode 2, the taper angle of the trench side wall can be controlled as will be described in detail later.

The self-bias voltage of the wafer 7 is about −2 V to −3 V. Since the self-bias voltage is so low, there is no damage due to ion bombardment.

As described above, when SF6 is used, a large number of F ^{* s} are generated due to dissociation during discharge and a large etching rate can be obtained. However, since F ^* itself progresses isotropically, the etching side wall is formed by O2. Oxidation prevents side etching and anisotropic etching with a high etching rate and little side etching can be performed by the above-described sputtering and ion assisting effects of Kr ⁺ .

Hereinafter, the dry etching characteristics of the wafer obtained by the above method will be described.

<Uniformity> As shown in FIG. 4, the distribution of the etching rate on the wafer 7 was found to be ± 4.6% uniformity at 13 points of measurement. According to FIG. 4, the etching rate is low at the center of the wafer 7 and high at the edge. In order to improve such uniformity, it is possible to optimize the focus ring and optimize it by optimizing the electrode structure using a gas flow simulation in the chamber 6.

<Wafer Surface Temperature> FIG. 5 is a characteristic graph showing the dependence of the wafer surface temperature on the etching time, and the measurement was performed using a thermo label. It can be seen that the surface temperature reaches 220 ° C. after about 2 minutes and 30 seconds and is saturated. In addition, Si as a mask
When shifting from O2 to resist, the wafer must be cooled efficiently.

<Time Dependence of Etching Rate> FIG. 6 is a graph showing the etching time dependency of the etching depth. Generally, in the case of trench etching, the etching rate tends to decrease as the depth increases. The etching rate is constant for a sample having an opening width of 1.6 μm.

<Dependence of Etching Rate on Mask Opening Width> As shown in FIG. 7, the etching rate tends to decrease as the opening width of the mask becomes smaller. Since a trench having the same diameter is usually formed on the same wafer, a difference in the etching rate due to the opening width (diameter) does not matter.

Next, experiments were conducted by changing the opening area of the grid 2 to φ200 mm and φ125 mm, which have relatively good uniformity, and the etching characteristics in each case will be described below.

<In the case of grid opening area φ200mm> First, at a pressure of 300mTorr and 400mTorr, the partial pressure ratio of SF3: O2: Kr
Experiments with 1: 1: 0,1: 1: 2,1: 1: 4 changed the results.In addition to reducing the side etch by adding Kr, the larger the amount of Kr, the lower the bottom of the trench. It turned out to be flat. Expected to be due to bottom impact effect by Kr ⁺ .

In addition, as a result of experiments at pressures of 50 mTorr, 100 mTorr, and 200 mTorr, the side etch was not reduced by the addition of Kr as observed at a pressure of 300 mTorr or more.

FIG. 8 shows characteristics of the etching rate, the selectivity, and the self-bias voltage when the pressure and the mixture ratio of the gas are changed. At a pressure of 200 mTorr or less, the selectivity decreased due to the addition of Kr, and at a pressure of 300 mTorr or more, a phenomenon of increasing the selectivity was observed. This is considered to be because at 200 mTorr or less, Kr addition greatly increases the self-bias voltage of -100 to -400 and increases the ion impact energy.

Meanwhile, in the above 300 mTorr, the self-bias voltage is small, no large energy of extent cutting the Kr ⁺ itself SiO _2. Further, the ion assist effect in the depth direction increases, and neutral molecules (atoms) other than radicals contribute to the etching, so that the ratio of the etching rate of SiO2 to the etching rate of Si becomes relatively large. It is considered something.

Thus, it was found that the effects of Kr addition such as reduction of side etch, uniform discharge, and improvement of selectivity were remarkable at 300 mTorr or more.

<Case of Grid Opening Area φ125 mm> The following experiment was performed under SF6: O2: Kr = 1: 1: 2.

<Pressure Dependence> As a result of examining the etching shape in the range of 300 mTorr to 600 mTorr, it was found that the side wall tends to have a positive taper (the opening side is wide and the bottom is narrow) on such a high pressure side.

In addition, it was found that the shape of the bottom also had a large R on the high pressure side.

FIG. 9 shows the etching rate, the selectivity, and the side etch rate at the center and side of the wafer when the pressure is changed. At a pressure of 500 mTorr or more, a uniform shape is obtained at the center and side of the wafer. In addition, both the etching rate and the selectivity increase on the high pressure side.

<Dependency on gas mixture ratio> 500 mTorr, RF power 400 W at upper electrode 1, RF power at lower electrode 3
The dependence on the SF6 / O2 ratio when Kr was constant at 200 W and Kr = 200 cc / min was examined.

When SF6 / O2 = 105/95, the side wall becomes vertical, and when SF6 is increased from there, it becomes a reverse taper (the opening side is narrow and the bottom is wide),
Increasing the O2 content results in a positive taper. That is, it has been found that the trench shape can be controlled by controlling the gas mixture ratio.

FIG. 10 shows the SF6 / O2 ratio dependence of the etching rate, selectivity, and side etch rate.

The etching rate and the selectivity are increased by increasing the amount of SF6. The side etch rate has a minimum point for the SF6 / O2 ratio. By properly choosing the SF6 / O2 ratio, side etch can be minimized.

Next, the SF6 / O2 flow rate was fixed at 100/100, and Kr was 200-600c.
When the shape change was examined under the conditions of a pressure of 500 mTorr, an upper power of 400 W, and a lower power of 200 W, the Kr amount was changed to 200 cc / min.
Even if it increased from min to 400,600 cc / min, no further side etch suppression effect was seen. Under these conditions, Kr of etching rate, selectivity and side etch rate
The flow rate dependence was as shown in FIG. 11, and it was found that the etching rate decreased as the Kr amount increased. This is SF
This is because the partial pressure of No. 6 decreases, and it is considered that the Kr content is appropriately about the same as the content of SF6 and O2.

<RF power dependence> The dependence of the lower RF power when the upper RF power was fixed at 400 W was examined.

It was found that as the lower RF power was increased, the sidewalls shifted from a positive taper to vertical.

It has also been found that the side etch at the entrance of the trench tends to be reduced by increasing the lower power.

FIG. 12 is a characteristic diagram showing the dependence of the etching rate, selectivity, and side etch rate on the lower power under the above conditions. It can be seen that by increasing the lower power, the selectivity decreases, the side etch decreases, and the side walls tend to become perpendicular from the positive taper. It is considered that these are because the energy of the etchant itself and the impact in the depth direction increase due to the increase in the lower power.

Fig. 13 shows the etching rate when the ratio of the upper and lower RF powers is fixed at 2: 1 and the power is increased.
It shows the power dependence of the side etch rate. Incidentally, the trench shape in the above experiment, when the power is low, the side etch at the trench entrance tends to be remarkable,
Also, when the power was increased, the side walls also tended to shift from the forward taper to the reverse taper.

As described above, it was found that by controlling the gas mixture ratio, it was possible to reduce the side etch and control the side wall taper, and further, by controlling the RF power ratio and RF power between the upper and lower parts. Also, it can be seen that the trench shape can be controlled.

Next, when comparing the trench structure obtained by the method of the present invention and the trench structure of the conventional method by microscopic photographs, FIG. 14 shows that SF6 = 100 cc / min, O2 = 100 cc / m
in, pressure 0.3 Torr, upper RF power 400 W, lower RF power 2
It is a microscope picture which shows the trench structure at the time of 00W, and a large side etch appears.

On the other hand, FIG. 15 is a micrograph showing the trench structure when Kr = 200 cc / min is added to the conditions in FIG. 14 and etching is performed, and it can be seen that the side etch is significantly reduced.

FIG. 16 shows that SF6 = 41 cc / min, O2 = 34 cc / min, Kr = 7
4 is a micrograph showing a trench structure when dry etching is performed under the conditions of 5 cc / min, a pressure of 0.5 Torr, an upper RF power of 400 W, and a lower RF power of 200 W. In the figure, the thickness of the upper SiO2 layer is 0.4 μm, the upper opening width of the trench is 1.3 μm, and the trench depth of the Si layer below the SiO2 layer is 4.2 μm. As shown in the figure, there was almost no side etching, and the etching rate was 1.7 μm / min.

Next, a case where SiCl4 is mixed with SF6 as an etching gas will be described. SF6 / SiCl4 / Kr as gas flow rate
An experiment was performed with / O2 = 100/10/200/100, upper RF power of 400 W, lower RF power of 200 w, and pressure of 200 mTorr to 400 mTorr. The pressure dependency of the etching rate and the selectivity in this case is as shown in FIG. 17, and it was found that the selectivity was considerably increased by adding a small amount of SiCl4 as compared with SF6 / O2 / Kr. This is because the rate of Si hardly changes, but the rate of SiO2 decreases to about half. It is also considered that the protection effect of the SiO2 film was increased.

Next, the case where CBrF3 / SF6 is used as an etching gas and Ar is added thereto will be described.
It was found that the side etch was reduced and the selectivity was also reduced by the addition of Ar compared to the case of only 3 / SF6.

Seems for Ar ⁺ effect.

Next, the case where Ar is added to CBrF3 as an etching gas will be described. CBrF3 is a gas in which a C-based side wall protective film is easily formed and anisotropy is easily obtained. It turned out that.
It is considered that the high impact of Ar ⁺ weakens the side wall protection effect.

FIG. 18 shows the pressure dependence of the etching rate and the selectivity. Although both the etching rate and the selectivity are low, the addition of Ar increases the etching rate.

As described above, among the elements belonging to group 0, the gases of Ar and Kr have a considerable effect on the shape and selectivity of the trench,
In addition, Si which requires an etching rate of 1 μm / min or more
In the trench etching process, it was possible to secure anisotropy by adding O2 and Kr while utilizing the high etching rate of SF6.

The present invention is not limited to the above embodiment,
Various modifications can be made within the scope of the present invention.
Among the elements belonging to group 0, the gases excluding He and Ne are A
In addition to r and Kr, there are also Xe and Rn, which can also be expected to have similar effects by sputtering and ion assist, but they are expensive because of the rare gas. It can be said that it is suitable for. Further, SF6 as an etching gas is excellent in that a high etching rate can be used, but is not limited thereto.

[Effects of the Invention] As described above, according to the present invention, in performing trench etching with an aspect ratio of 1 or more, any one of the group 0 group elements except He and Ne is added. Thus, anisotropic etching with an improved etching rate and reduced side etching can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view for explaining an example of an etching apparatus for carrying out the method of the present invention, and FIG. 2 is a drawing in which SiO2 is used as a mask as a material to be etched.
FIG. 3 is a schematic explanatory diagram for explaining a Si wafer, FIG. 3 is a schematic explanatory diagram showing an etching shape of a Si wafer when Kr is used as an additive gas, and FIG. 4 is a diagram for explaining uniformity of an etching rate. 5A shows the coordinates of the wafer, and FIGS.
(C) is a characteristic diagram showing the etching rate at each position in the X and Y directions, FIG. 5 is a characteristic diagram showing the dependence of the wafer surface temperature on the etching time, and FIG. 6 is a characteristic diagram showing the etching depth. FIG. 7 is a characteristic diagram showing the dependence of the etching rate on the mask opening width, and FIG. 8 is a characteristic diagram showing the dependence on the partial pressure ratio and the pressure of SF6 / O2 / Kr. FIG. 9 is a characteristic diagram showing an etching rate, a selection ratio, and a self-bias voltage. FIG.
FIG. 10 is a characteristic diagram showing the selectivity and the side etch rate at the center and the edge of the wafer. FIG. 10 shows the dependence of the etch rate, the selectivity and the side etch rate on the SF6 / O2 mixture ratio when the Kr amount is constant. FIG. 11 is a characteristic diagram showing the dependence of the etching rate, the selectivity, and the side etch rate on the Kr flow rate when the SF6 / O2 flow rate is constant. FIG. 12 is a graph showing the etch rate, the selectivity, and the side etch rate. FIG. 13 is a characteristic diagram showing the dependence of the rate on the lower RF power, and FIG. 13 shows the RF of the etching rate, the selectivity, and the side etch rate when the ratio of the upper and lower powers is fixed at 2: 1.
FIG. 14 is a characteristic diagram showing power dependence, FIG. 14 is a schematic diagram of a micrograph showing a trench structure obtained by etching when Kr is not added, and FIG. 15 is a diagram in which Kr is added to the etching conditions of FIG. FIG. 16 is a schematic diagram of a micrograph showing a trench structure when etching is performed, FIG. 16 is a schematic diagram of a micrograph showing a trench structure after performing etching for 2.5 minutes by adding Kr, FIG. 17 is SF6 FIG. 18 is a characteristic diagram showing the pressure dependence of the etching rate and the selectivity when / SiCl4 / Kr / O2 is used as the etching gas.FIG. 18 shows the pressure dependence of the etch rate and the selectivity when Ar is added to CBrF3. FIG. 1 ... upper electrode, 2 ... grid, 3 ... lower electrode, 4,5 ... RF power supply, 6 ... chamber, 7 ... material to be etched, 8 ... load lock chamber, 20 ... Si wafer, 22 ... SiO2 (mask material).

Claims (4)

(57) [Claims] An anisotropic dry etching for forming a trench having a depth / opening aspect ratio of 1 or more in the material to be etched by arranging the material to be etched on one of the parallel plate electrodes. And dry-etching by supplying SF6, O2, Kr such that the partial pressure ratio of SF6: O2: Kr is about 1: 1: 2. 2. The dry etching method according to claim 1, wherein the pressure in the reaction chamber is 0.3 Torr or more. 3. An anisotropic dry etching for forming a trench having an aspect ratio of depth / opening width of 1 or more in the material to be etched by arranging the material to be etched on one of the parallel plate electrodes. SF6, O2, Kr, SF6: O2: Kr relative to the reference partial pressure ratio of 1: 1: 2, the SF6 or O2 flow rate is changed by changing the partial pressure ratio, trench A dry etching method characterized by controlling an etching shape. 4. A grounded grid electrode is arranged between a first electrode and a second electrode to which RF power is supplied, and
An anisotropic material is placed on one of the second electrodes, and anisotropic dry etching for forming a trench having an aspect ratio of depth / opening width of 1 or more in the material to be etched is performed using SF6, O2, Kr is supplied such that the partial pressure ratio of SF6: O2: Kr is about 1: 1: 2, and the RF power ratio supplied to the first and second electrodes or the magnitude of the RF power is changed. And controlling the trench etching shape.