JP2599250C - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION       [0001]     [Industrial applications]   The present invention is directed to nitride semiconductors used in devices such as light emitting diodes and laser diodes.
The present invention relates to a dry etching method for a gallium arsenide compound semiconductor, and particularly to a reactive plasma.
And an etching method using the same.       [0002]     [Prior art]   Currently, gallium nitride-based compound semiconductors are used as blue light emitting diode (LED) materials
Is being put to practical use. For example, a light emitting chip of a blue LED has a GaN substrate on a substrate.
Buffer layer, n-type GaN layer, n-type GaAlN layer, InGaN layer, p-type GaAlN layer
, P-type GaN layers are sequentially stacked.       [0003]   As a substrate on which such a gallium nitride-based compound semiconductor structure is formed,
In general, a sapphire substrate is used. Sapphire substrate is electrically insulating
Therefore, an electrode is provided on top of this, and this is
It cannot be electrically connected to the compound semiconductor layer. Therefore, gallium nitride-based
Compound semiconductor etching is required. Taking the above double heterostructure as an example
To explain, the p-type GaAlN layer and the InGa
The N layer and a part of the n-type GaAlN layer are removed by etching to form a part of the n-type GaN layer.
It needs to be exposed. An n-electrode is provided on the exposed surface of the n-type GaN layer.
The p-electrode is provided on the surface of the uppermost p-type GaN layer.       [0004]   In addition, the realization of a double hetero structure of gallium nitride based compound semiconductor
Gallium nitride-based compound semiconductors are not only LEDs, but also short-wavelength laser diodes.
It can be used practically as a material for a laser diode (LD). Gallium nitride
In order to create light emitting devices such as LDs using compound semiconductors, etching techniques
The art is very important. Gallium nitride-based compound semiconductors include other GaAs, GaP, etc.
Since it does not have cleavage like the semiconductor material of
When realizing an end-face reflection type LD, the end face etched as vertically as possible
It is necessary to realize.       [0005]   Now, regarding the etching technology of the gallium nitride based compound semiconductor, a reactive gas pump is used.
A dry etching method using plasma is known, and many reports have been published on this method.
There is a notice. For example, Japanese Unexamined Patent Publication No._FourA method using gas,
JP-A-3-108779 discloses CCl_TwoF_TwoGas, CCl_FourGas, CF_FourGas
The method used, JP-A-4-34929 discloses BCl_ThreeGas method is shown
ing. Also, Cl_Two/ H_TwoMixed gas of BCl_ThreeUsing mixed gas of / Ar
(Semicond. Sci. Tecnol. 8, (1993) 310-312.
), BCl_Three/ SiCl_FourUsing a mixed gas (Appl. Phys. Let)
t. 64 (7), 14 Feb. 1994), SiCl_FourGas, or SiCl_Four/ SiF_Four(App. Phys. Lett. 6)
3 (20), 15 Nov. 1993).       [0006]   These methods use reactive power generated by a high-frequency power supply in an etching chamber.
Gallium nitride-based compound semiconductor placed on the electrodes by dry etching
And wet etching methods (for example, phosphoric acid and sulfuric acid).
Gallium nitride-based compound with a higher etching rate than the method using mixed acid)
There is an advantage that a semiconductor can be etched into a desired shape.       [0007]     [Problems to be solved by the invention]   However, in the above-mentioned conventional method, the etching residue (etching) depends on the type of gas.
The semiconductor that has not been etched on the etching surface remains in an uneven shape), d.
Ditch pits (in the form of a hole in the etched surface, which is uneven)
Are likely to occur, and it is difficult to obtain a smooth etched surface.
there were. Furthermore, the gas flow rate in the etching chamber during etching, plasma power,
Despite controlling the conditions such as the degree of vacuum in the same way,
Etching differs in etching speed, etching direction, etc. from the previous etching
There was a problem that the result was difficult to stabilize, that is, the reproducibility was poor. Same again
When a plurality of gallium nitride-based compound semiconductor samples are installed in one etching chamber,
There is also a problem that the etching result differs for each sample.       [0008]   Therefore, the object of the present invention is to firstly etch the etching residue on the etched surface.
Secondly, a smooth etched surface without residue, etch pit, etc. can be obtained.
Thirdly, for a plurality of gallium nitride based compound semiconductors
Also provide a way to etch with the same result when they are etched simultaneously
It is to be.       [0009]     Means and action for solving the problem   The present inventors have etched a gallium nitride-based compound semiconductor with a reactive plasma gas. Gallium nitride-based compound semiconductor is converted to silicon radicals and silicon chloride.
Etching with plasma gas generated from chlorine gas while subjecting to the action of elemental radicals
It has been found that the intended purpose can be achieved by
Was.       [0010]   In the first aspect of the present invention, the gallium nitride-based compound semiconductor is made of chlorine gas and silicon dioxide.
Plasma gas generated from a plasma generation gas containing two types of gases including an oxygen-containing gas
Using silicon dioxide as a mask.       [0011]   In the second aspect of the present invention, the silicon piece and the gallium nitride are contained in the etching chamber.
And a silicon-based compound semiconductor, and a plasma gas for generating the silicon pieces from chlorine gas.
Gallium nitride-based compound semiconductor and the plasma gas.
Etch with       [0012]   Hereinafter, the present invention will be described in more detail.       [0013]   The gallium nitride-based compound semiconductor to be dry-etched according to the present invention is GaN
III-V compound semiconductor containing gallium and nitrogen, such as GaN, GaAlN, and InGaN
And the formula In_aAl_bGa_1-abN (where 0 ≦ a, 0 ≦ b, a + b ≦ 1)
Can be represented. These gallium nitride-based compound semiconductors are doped with impurities.
Or undoped, and the impurities are p-type
, N-type. Gallium nitride-based compound semiconductors have a single-layer structure.
Or a multilayer structure. In the case of a multilayer structure, all of them are gallium nitride
May be formed of a compound semiconductor, or at least one of the layers may be
It may be formed of a gallium nitride-based compound semiconductor. In the present invention,
Even if the gallium compound semiconductor is present in any of the above forms,
Can be switched. Gallium nitride based compound semiconductors are based on sapphire
It may be formed on a plate. The present invention relates to a multilayer structure including a double heterostructure.
It is suitable for dry etching of a gallium arsenide compound semiconductor.       [0014]   In the first embodiment of the present invention, the gallium nitride-based compound semiconductor is replaced with chlorine gas.
(Cl_Two) And silicon-containing gas generated from a plasma generating gas containing two types of gases
Etching is selectively performed using the silicon dioxide as a mask with the plasma gas. Yo
More specifically, usually 10^-6Installed in an etching chamber decompressed to the order of torr
Gallium nitride-based compound semiconductor on a placed electrode (for example, one of parallel plate electrodes)
And two gases, chlorine gas and silicon-containing gas, are contained in the etching chamber.
Introduce the plasma generating gas, apply high frequency power to the electrodes, and
Generates plasma and etches gallium nitride-based compound semiconductor with the plasma
To run.       [0015]   As the silicon-containing gas used here, for example, silicon tetrachloride (SiCl_Four),
Silicon tetrafluoride (SiF_Four), Silane gas (SiH_Four)
And an organic metal compound gas containing Si. These
Preferably, the iodine-containing gas is not in the form of an oxide. Most preferred silicon-containing
The gas is silicon tetrachloride. Since silicon tetrachloride contains chlorine, it can be used together with chlorine gas.
When etching gallium nitride-based compound semiconductors, other elements besides chlorine and silicon
Element does not adversely affect the gallium nitride-based compound semiconductor. Therefore, the present invention
In the first aspect, a combination of a silicon tetrachloride gas and a chlorine gas as a plasma generating gas is used.
Most preferably, combination is used.       [0016]   In the first aspect of the present invention, the chlorine gas plasma is mainly composed of gallium nitride.
To contribute to the etching of system-based compound semiconductors and to control the etching rate.
The silicon-containing gas plasma is mainly used for etching residues and etch pits.
Contribute to the solution. Generated by plasma decomposition of chlorine gas or silicon-containing gas
Or a silicon chloride radical (SiC
l_x), Gallium nitride-based compound semiconductor where silicon radicals etc. are being etched
It acts on the etched surface of the body and eliminates etching residues and etch pits. Especially salt
The silicon nitride radical acts as a reducing agent and acts on the surface of the gallium nitride-based compound semiconductor. It is assumed that the natural oxide film formed on the surface is removed, which contributes to the flattening of the etched surface.
Is done. In addition, silicon tetrachloride alone may be used to separate
Etching with silicon tetrachloride plasma alone is slow
It is not preferable.       [0017]   In the first embodiment of the present invention, the salt introduced into the depressurized etching chamber is used.
The flow rate of the raw gas is preferably 0.1 cc / min to 500 cc / min.
If the flow rate of chlorine gas is less than 0.1 cc / min, gallium nitride based compound semiconductor
Tends to be impractical due to the low etching rate, while 500 cc / min.
If the pressure exceeds the limit, the degree of vacuum in the etching chamber will not be stable, and the etching result will tend to vary.
In the direction.       [0018]   Silicon-containing gas is used to etch the etched surface of gallium nitride based compound semiconductor
Chlorine gas is introduced into the etching chamber at a quantitative rate sufficient to eliminate residues and etch pits.
Both will be introduced. Silicon-containing gas (especially silicon tetrachloride gas)
S), the flow rate of the silicon-containing gas is described as follows.
From the viewpoint of etching rate, preferably 0.4 to 2.5 times the flow rate of chlorine gas
It is particularly preferably 0.5 to 2 times the chlorine gas flow rate. In addition, plasma emission
The total flow of raw gas may be in the range of 0.1 cc / min to 500 cc / min.
Particularly preferred.       [0019]   Next, a second embodiment of the present invention will be described. In a second aspect, the etchin
A silicon piece and a gallium nitride-based compound semiconductor are installed in a chamber, and the silicon piece is salted.
The gallium nitride-based gas is used for the action of the plasma gas generated from the raw gas.
The compound semiconductor is etched with the plasma gas. More specifically, the first state
Like normal 10^-6installed in an etching chamber that is decompressed to the order of torr
On the electrode (for example, one of the parallel plate electrodes) and a silicon gallium nitride-based compound
Place the conductor, introduce chlorine gas into the etching chamber, apply high frequency power to the electrodes
To generate plasma from chlorine gas and etch the silicon pieces with the plasma gas The gallium nitride-based compound semiconductor is etched while etching.       [0020]   The silicon piece used in the second aspect may be in the form of a wafer,
May be in the form of chips cut from
May be. Usually, a gallium nitride-based compound semiconductor is mounted on a silicon piece. Silicon
Exposed area of the piece, i.e. silicon piece directly etched by chlorine gas plasma
The area is preferably as large as possible. Specifically, the exposed area of the silicon piece is
It is desirable that the exposed area of the gallium nitride-based compound semiconductor is 1/100 or more.
No. The exposed area of the silicon piece is 1/100 of the exposed area of the gallium nitride compound semiconductor.
If it is less than the etching surface of the gallium nitride-based compound semiconductor to be etched,
Etching residues and etch pits are not easily eliminated, and a flat etched surface is obtained.
It tends to be difficult.       [0021]   In the second aspect, the chlorine plasma is composed of gallium nitride-based compound semiconductor and silicon.
Etch pieces. The Si that pops out after etching is
By bonding with the chlorine radical, the silicon chloride radical (
SiCl_x) Is formed, and the silicon chloride radicals and silicon radicals are in the first state.
Similarly, the etched surface of the gallium nitride-based compound semiconductor layer is flattened.       [0022]   In the second aspect, the flow rate of the chlorine gas introduced into the etching chamber is zero.
. It is preferably 1 cc / min to 200 cc / min.       [0023]   In the present invention (including the first aspect and the second aspect), the gallium nitride-based compound
The target semiconductor mainly consists of Cl, whose etching rate can be controlled, and flattened etching surface.
Since it is etched simultaneously with Si that can be supported, etch quickly and uniformly on a plane
Can be Gallium nitride is etched by etching with plasma of Si and Cl.
-Based compound semiconductors are anisotropically etched and the etched end faces must be vertical
Can be.       [0024]   In the present invention, the pressure in the etching chamber during plasma etching is
The same as in the case of Zuma dry etching, for example, 1 × 10^-3torr
To 500 torr. Also, the high frequency power density is
The same as in the case of light etching, for example, 0.01 to 50 W / cm
^TwoPower density can be used. Note that the second aspect of the present invention also
Used as a mask when performing selective etching by forming on the surface of gallium arsenide compound semiconductor layer
In particular, silicon dioxide can be preferably used. Silicon dioxide is chlorine gas
It has the property of being hardly etched by plasma.       [0025]   FIG. 1 shows an example of a dry etching apparatus used to carry out the method of the present invention.
It is a figure which shows schematically. This apparatus basically includes an etching chamber 1 and a high-frequency power supply.
It comprises a source 2, an exhaust device, and a plasma generating gas introducing device.       [0026]   More specifically, for example, inside the etching chamber 1 made of aluminum, a pair of
Parallel plate type electrodes 11 and 12 are installed facing each other. Generally, the anode 11 is
High-frequency power is applied to the cathode 12. Cathode 12 is a plasma gas
To a temperature at which the metal material forming the cathode 12 melts.
So that the cooling water flows on the back side to cool it.
It has structure. A 13.56 MHz high frequency power supply 2 matches this cathode 12.
It is connected via a switching box 22 to control the plasma.       [0027]   The etching chamber 1 has an exhaust pipe 3, and a dry pump, a turbo
An exhaust device (not shown) in which a pump and the like are combined is connected. This exhaust system
Drives the inside of the etching chamber 1 by, for example, 10^-6Can be set to a vacuum below torr
You. The pressure in the etching chamber 1 is controlled, for example, by a pressure control provided in the middle of the exhaust pipe 3.
The pressure is adjusted by the regulating valve 33 and is always maintained at a constant degree of vacuum.       [0028]   The etching chamber 1 further introduces each plasma generating gas into the etching chamber 1.
Gas introduction pipe for the external plasma generating gas source (illustration Without). More specifically, the etching chamber 1 introduces chlorine gas.
First gas introducing pipe 4a for introducing a silicon-containing gas and a second gas introducing pipe 4a for introducing a silicon-containing gas.
Is provided. The flow rate of each gas is distributed to the gas introduction pipes 4a and 4b, respectively.
It is precisely controlled by the provided mass flow controllers 44a and 44b. What
As in the second embodiment of the present invention, only chlorine is used as the plasma generating gas.
When the gas is introduced into the switching chamber 1, the gas introduction pipe 44b is omitted or closed.       [0029]   Next, the gallium nitride-based compound semiconductor is etched using the above dry etching apparatus.
The following describes the second operation for convenience of explanation.
You. First, a silicon piece 102 in the form of, for example, a wafer is placed on the cathode 12 respectively.
Gallium nitride-based compound in the form of, for example, a wafer.
The conductor 101 is placed. Next, the exhaust system is driven to evacuate the inside of the etching chamber 1 for 10 minutes.^-6
Evacuate until the pressure is on the order of torr. Low vacuum in etching chamber 1
After that, the chlorine gas is supplied from the gas introduction pipe 4a so that the flow rate becomes the above-mentioned flow rate.
Controlled by the low controller 44a, the gas is introduced into the etching chamber 1 and exhausted at the same time.
The inside of the etching chamber 1 is evacuated by the apparatus, and the pressure adjusting valve 33 is adjusted to etch the etching chamber.
The pressure in the chamber 1 is controlled to a predetermined pressure. After the pressure in the etching chamber 1 is stabilized,
A chlorine gas is supplied between the two electrodes 11 and 12 from the high-frequency power supply 2 via the matching box 22.
Plasma is generated, thereby etching the silicon piece 102 while forming a nitride film.
The compound semiconductor 101 is etched.       [0030]   In the first embodiment of the present invention, since the silicon piece 102 is not used, the gallium nitride-based
The compound semiconductor 101 is directly mounted on the cathode 12. And, in the case of the above second aspect
In the same manner as described above, the inside of the etching chamber 1 is^-6torr order
Exhaust until pressure is reached. After the degree of vacuum in the etching chamber 1 is stabilized, the gas introduction pipe
4a, chlorine gas is controlled by the mass flow controller 44a to control the flow rate thereof.
The gas is introduced into the chamber 1 and the mass flow controller is connected through the gas introduction pipe 4b.
The silicon-containing gas (preferably silicon tetrachloride) is controlled while controlling the flow rate by the heater 44b.
It is introduced into the etching chamber 1. At the same time, the inside of the etching chamber 1 is exhausted by the exhaust device. The gas is exhausted, and the pressure in the etching chamber 1 is controlled to a predetermined pressure by adjusting the pressure adjusting valve 33.
I will. After the pressure in the etching chamber 1 is stabilized, the matching
A chlorine gas and a silicon-containing gas are pumped between the electrodes 11 and 12 through a box 22.
Generates plasma, thereby etching the gallium nitride-based compound semiconductor 101
I do.       [0031]     【Example】   Next, the present invention will be described with reference to examples. In each of the following examples, FIG.
Such an etching apparatus was used.       [0032]   Example 1   200 angstroms on a sapphire substrate with a thickness of 400 μm and a diameter of 2 inches
GaN buffer layer and a wafer with a 4 μm thick GaN layer laminated on it
Prepared. Silicon dioxide (SiO 2) is formed on the upper GaN layer by a conventional method._Two) To 0.5
μm thick and a silicon dioxide film
Patterning was used as a mask to produce an etching sample 101.       [0033]   Four of the etching samples 101 were placed at the position of the cathode 12 in the etching chamber 1.
It was set on a fixed table. After installation, the etching chamber 1 was 5 × 10^-6
It was evacuated to torr. After the degree of vacuum in the etching chamber 1 is stabilized, the gas introduction pipe 4
80cc / min of chlorine gas from a, and silicon tetrachloride gas from gas introduction pipe 4b
Each of the mass flow controllers 44 is set so that it flows in at a flow rate of 40 cc / min.
These gases were introduced into the etching chamber 1 under the control of a and 44b. At the same time
The inside of the etching chamber 1 is evacuated by a vacuum pump, and the pressure adjusting valve 33 is adjusted.
Thus, the inside of the etching chamber 1 was controlled to a reduced pressure of 0.04 torr.       [0034]   After confirming that the degree of vacuum in the etching chamber 1 is stable, the high-frequency power source 2
A plasma is generated between the electrodes 11 and 12 via the matching box 22 and
Frequency power area density 1.27W / cm^TwoEtching was started.       [0035]   After the etching, the sample 101 is taken out of the etching chamber 1, and the sample is etched.
Was observed with a scanning electron microscope (SEM). Fig. 3 shows the etched surface by SEM
5 is a photograph showing a crystal structure of a. As shown in this figure, the method according to the present invention
The isotropic etching is performed, and the etched end face is almost vertical. Further
In addition, no residue or the like is generated on the etched GaN surface, and the GaN surface is etched flat.
You can see that it is done. The etching rate of GaN is 5600 Å
Etching was very fast at a loam / minute. In addition, FIG. 3 is a sample in four sheets.
Is a view in which a part of the sample is observed, and the other three samples are similar to FIG.
A smooth etched surface was obtained, and the etching depths were all the same.       [0036]   Further, the selectivity of GaN and silicon dioxide mask by the reaction gas (GaN
/ SiO_Two) Is as high as 33.0, which means that GaN is easily etched,
SiO_TwoIndicates that etching is difficult, and SiO_TwoIs related to the method of the present invention.
It is shown that it is most suitable as a mask material.       [0037]   Figure 2 shows the flow ratio of chlorine gas to silicon tetrachloride gas and gallium nitride based compound semiconductor.
FIG. 4 is a diagram showing a relationship between the etching rate and the etching speed. This is the high-frequency power of the first embodiment.
Under the conditions of areal density and degree of vacuum, the total gas flow rate of chlorine gas and silicon tetrachloride gas
Set to 120 cc / min and change the mixing ratio of chlorine gas and silicon tetrachloride gas.
It is the result of measuring the etching rate in each case. As shown in FIG.
However, etching with silicon tetrachloride gas alone has a low etching rate.
As the raw gas is mixed, the etching rate tends to increase. But chlorine
Conversely, the etching rate decreases with the gas alone. That is, as described above,
Silicon can be used at a ratio of 0.4 to 2.5 times the volume of chlorine gas.
Preferably, it is further introduced into the etching chamber 1 at a rate of 0.2 to 2 times.
It turns out that it is preferable.       [0038]   Example 2   Four 3 inch diameter Si wafers 102 are placed on the stage of etching chamber 1
did. Then, a 2-inch diameter etching sample prepared in the same manner as in Example 1.
101 was placed so as to be located substantially at the center of each Si wafer 102.       [0039]   Thereafter, only chlorine gas was introduced at 120 cc / min without introducing silicon tetrachloride gas.
Sample 10 in the same manner as in Example 1 except that the sample 10 was introduced into the etching chamber 1 at a flow rate of
1 was etched. As a result, a smooth surface almost equivalent to the etched surface shown in FIG.
As a result, the etching surface became almost vertical and the anisotropic etching of the GaN layer was performed.
And confirmed. The etching rate was 5000 Å / min,
All samples are etched with the same etching shape and the same etching rate
It had been. GaN / SiO_TwoWas also as high as 35.7.       [0040]   Comparative Example 1   Etch only chlorine gas at a flow rate of 120 cc / min without using silicon tetrachloride gas
Etching was carried out in the same manner as in Example 1 except that the etching was carried out in the chamber 1. Etch
FIG. 4 shows a photograph showing the crystal structure of the etched surface by SEM after the etching. In FIG.
Has a large number of etch pits on the etched GaN surface and has fine irregularities
You can see that. The etching rate was 2500 Å / min.
Etch pits were similarly generated on the other three sheets, and the etching rate was ± 5%.
There was variation.       [0041]   Comparative Example 2   For the same sample as in Example 1, 30 c of chlorine gas was used as a plasma generating gas.
c / min and boron trichloride gas into the etching chamber 1 at a flow rate of 10 cc / min.
When etching was performed in the same manner as in Example 1 except that
As in Comparative Example 1, a large number of etch pits were generated on the
Fine irregularities were observed. The etching rate is 1520 angstroms /
Min, GaN / SiO_TwoAlso showed a low value of 2.62.       [0042]   Example 3   This embodiment will be described with reference to FIGS. FIG. 5 shows this implementation.
It is a top view which shows the shape of the silicon dioxide mask used for the example. As shown in FIG.
Each of the mask portions 50 has a radius from a corner of the square to about 約 of the length of one side of the square.
It has a thickness of 0.5 μm and has a shape obtained by cutting out a quarter circle. Figure 6
FIG. 3 is a cross-sectional view illustrating a structure of a light emitting device obtained by the example of FIG.       [0043]   200 Å thick on a sapphire substrate 60 with a thickness of 400 μm and a diameter of 2 inches
A GaN buffer layer 61 having a thickness of 4 tons, an n-type GaN layer 62 having a thickness of 4 μm,
2 μm n-type GaAlN 63, 400 Å thick InGaN layer 64
0.2 μm thick p-type GaAlN layer 65 and 0.3 μm thick p-type GaN
A wafer in which the layers 66 were sequentially stacked was prepared.       [0044]   Next, after forming a mask having a shape as shown in FIG. 5 on the surface of the p-type GaN layer 66,
The gallium nitride-based compound semiconductor layer was etched in the same manner as in Example 1.       [0045]   After confirming that the etching depth has reached the n-type GaN layer 62, the etching is terminated.
Was. After etching is completed, the wafer is immersed in hydrofluoric acid to remove the mask,
Accordingly, the p-type GaN layer 66 is provided with the p-electrode 68 and the n-type G
On the aN layer 62, an n-electrode 67 was formed by vapor deposition.       [0046]   After the electrodes are formed, the wafer is cut along the broken line shown in FIG.
15,000 light-emitting chips were obtained from one wafer. The structure of the light emitting device is shown in FIG.
Shown in plan view.       [0047]   The surface of the electrode 67 formed on the surface of the n-type GaN layer 62 of this light emitting chip is
Surface is smooth, and the same surface is obtained by inheriting its properties.
Was. Further, since the etching end face is substantially perpendicular, the electrode 67
Short-circuit between the electrodes caused by the contact between won.       [0048]     【The invention's effect】   As described above, when etching a gallium nitride-based compound semiconductor,
According to the method of the present invention, a flat surface having very little residue on the etched surface, etch pits, etc.
A smooth surface can be obtained. Therefore, as shown in Example 3, this etched surface
When the electrodes are formed on the electrodes, the electrode surfaces can also be smooth surfaces. Wire bond to smooth electrode surface
When the electrodes are connected by soldering, etc., these materials are less likely to be peeled from the electrodes.
Therefore, the reliability of the device is remarkably improved.       [0049]   In addition, since the etching rate is stable, the etching depth can be strictly controlled.
. Therefore, even for a gallium nitride-based compound semiconductor device having a complicated structure,
Etching can be controlled.       [0050]   Furthermore, the same result is simultaneously etched for a plurality of gallium nitride-based compound semiconductors.
Can be etched and the etching rate is faster than other methods, thus improving productivity.
Can be made.       [0051]   According to the method of the present invention, when a silicon dioxide mask is used, the mask is
Very high etching selectivity with gallium arsenide compound semiconductors
Gallium nitride-based compound semiconductors can be etched deeply.
.       [0052]   As described above, the etching method of the present invention provides a method of etching gallium nitride-based compound semiconductors.
This semiconductor material is very useful for laser diodes and solar cells in the future.
In realizing a device such as a pond, its industrial utility value is high.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view showing the structure of a main part of an etching apparatus used in one embodiment of the present invention. FIG. 2 is a graph showing a relationship between a flow rate ratio of a chlorine gas and a silicon tetrachloride gas and an etching rate of a gallium nitride-based compound semiconductor. FIG. 3 is an electron microscope photograph showing a crystal structure of an etched surface of a gallium nitride-based compound semiconductor according to one embodiment of the present invention. FIG. 4 is an electron micrograph showing a crystal structure of an etched surface of a gallium nitride-based compound semiconductor according to a comparative example. FIG. 5 is a plan view showing the shape of a mask used in one embodiment of the present invention. FIG. 6 is a cross-sectional view illustrating a structure of a light-emitting element including a gallium nitride-based compound semiconductor obtained in one example of the present invention. [Description of Signs] 1 ... Etching chamber, 2 ... High frequency power supply, 3 ... Exhaust pipe, 4a, 4b ... Gas introduction pipe,
11, 12 ... electrodes, 62 ... n-type GaN layer, 66 ... p-type GaN layer, 67 ... n-electrode,
68: p electrode; 101: gallium nitride compound semiconductor; 102: silicon piece.

Claims (1)

Claims: 1. A gallium nitride-based compound semiconductor is selectively etched with a plasma gas generated from a plasma generation gas containing two kinds of gases, a chlorine gas and a silicon-containing gas, using silicon dioxide as a mask. A method of dry-etching a gallium nitride-based compound semiconductor. 2. The dry etching method for a gallium nitride-based compound semiconductor according to claim 1, wherein the silicon-containing gas is a silicon tetrachloride gas. 3. A silicon piece and a gallium nitride-based compound semiconductor are installed in an etching chamber, and the silicon piece is subjected to the action of a plasma gas generated from chlorine gas, and the gallium nitride-based compound semiconductor is etched with the plasma gas. A method of dry-etching a gallium nitride-based compound semiconductor. 4. A gallium nitride-based compound semiconductor which is selectively etched with a plasma gas generated from a chlorine gas using silicon dioxide as a mask while being subjected to the action of silicon radicals and silicon chloride radicals. Dry etching method for compound semiconductor.