JP2001194362A - Method and apparatus for extracting impurities in semi conductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and an apparatus for extracting impurities present in the surface and in the depth direction of a semi conductor substrate with high accuracy in which the etching speed is high, the etching quantity can be controlled correctly, and the concentration of impurities of the back ground is low. SOLUTION: Etchants 3, 18 are vaporized, the semi conductor substrate 6 is heated, and the semi conductor substrate 6 is etched to a predetermined depth by the etching vapor while exhausting a generated reaction gas. The impurities (alkaline metal, heavy metal, etc.), is made to remain on the semi conductor substrate. An acid reagent 21 is vaporized and the semi conductor substrate is cooled to extract the impurities in liquid drops.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas phase separation of a trace substance.
Solution method and gas phase decomposition apparatus, especially, sample of semiconductor substrate
Etching impurities existing on the surface or in the depth direction
It relates to a method and an apparatus for extracting. 2. Description of the Related Art In semiconductor manufacturing technology, device
It is important to increase reliability and manufacturing yield, and silicon
Control of various defects in the substrate plays an important role
You. One of the causes of this defect is the presence of alkali metals or heavy metals.
There is metal contamination. Single crystal silicon is of very high purity
The impurities mixed in this form the nuclei of crystal defects.
Or the breakdown voltage characteristics of the gate oxide film
Causing problems such as junction leaks,
Deterioration in performance and yield is caused. [0003] The aforementioned trace amounts of impurities in a semiconductor substrate are extracted.
As a means of emitting, conventionally, high-purity hydrofluoric acid and nitric acid
Dissolution by the mixture was performed. However, commercial purification
Reagent extraction provides high sensitivity and high sensitivity
Has become more difficult. Furthermore, impurity extraction with high sensitivity
Use Reagent Reagent Vapor as an Effective Method
A method is disclosed. Disclosed in Analytical Chemistry vol. 46, No. 9, pp. 743-747
Use the natural evaporation of hydrofluoric acid and nitric acid
And react the reagent vapor with the Si substrate to etch the Si substrate.
To extract impurities. Also, analytical chemistry
_, vol. 42 (1993) discloses a method for
This is an example using the mind. Teflon with silicon sample
Add sulfuric acid to the cup and put it in the pressure decomposition vessel.
The reagent (hydrofluoric acid + nitric acid) into the Teflon container on the side
Seal tightly. Hold this in a stainless steel outer container and heat it.
To decompose the sample with a mixed vapor of hydrofluoric acid and nitric acid.
Heat until white smoke comes out, and add fluorosilicic acid and hydrogen fluoride
Remove the acid. Extract the remaining impurities and, for example,
Impurity concentration can be fixed by the secondary absorption method. this
The extraction method is to heat hydrofluoric acid and nitric acid in a closed container.
It is characterized by generating steam and using sulfuric acid and pure water.
And measuring the whole silicon in a fragmented state
It is. The following is a material technology, No. 5, (1991).
Adsorb the indicated heated reagent vapor to pure water.
This is an example used. Silicone sample and pure water
In a car, place a hydrofluoric acid, nitric acid, and sulfuric acid
Set in a sealed container of fluorine resin. Then add a closed container
Hydrofluoric acid and nitric acid vapor generated by heating beaker
Is a method of decomposing a sample by being absorbed by pure water in it.
You. After decomposition of the sample, add sulfuric acid and treat with sulfuric acid white smoke.
Silicon as the main component is removed as fluorosilicic acid,
For example, by performing atomic absorption spectrometry analysis, the impurity concentration is fixed.
You can do it. This method also heats in a closed container to fluorinate
Generates hydrogen and nitric acid vapors and uses sulfuric acid and pure water
It is characterized by the fact that the whole Si substrate is measured
is there. [0006] However, as described above,
However, the impurity extraction method has the following problems. Analytical chemistry
In the example disclosed in vol.46, No.9, pp.743-747, the reagent
Slow etching rate due to natural evaporation
In addition, it is performed in a closed reaction vessel.
The gas generated by the reaction accumulates in the reaction vessel,
Slows or reverse reaction progresses. Therefore, the sample
When etching to a predetermined depth,
Difficult to control. In addition, impurity extraction
Dissolve the powder produced in
Since the purity of water and acid affects the analysis results, high-precision
Cannot be analyzed. Analytical chemistry _, vol.42 (1993)
Since the method is performed in a closed container, the same problem as above
Occurs. This method also measures the whole semiconductor substrate.
This is a method for determining the impurity level up to a predetermined depth in the semiconductor substrate.
Can not analyze substances. Material technology, disclosed in No. 5, (1991)
These methods have similar problems. In addition, this method
Since the reagent is heated to normal pressure to form a vapor, the
Mist of about 100μm is easy to be generated,
Impurities are wrapped in this mist and mixed into the extract
Therefore, it is not possible to extract an extract for analysis with high accuracy. The present invention has been made in view of such a problem.
To the surface of the semiconductor substrate or to a predetermined depth.
Fast and accurate etching, background
Low impurity concentration, semiconductor substrate impurity extraction method or
An extraction device is provided. [0008] The above-mentioned problem is solved by the first aspect.
A process of vaporizing an etching solution, which is an invention;
Heating the body substrate; and
The semiconductor substrate is etched to remove impurities in the semiconductor substrate.
Leaving a reaction product containing on the semiconductor substrate,
Vaporizing an oxidizing reagent; and
Supplying the conductive substrate, and cooling the semiconductor substrate,
Liquefying the oxidizing vapor on the semiconductor;
Extracting impurities in the reaction product.
The problem is solved by a method for extracting impurities from a plate. Next, the operation of the first invention will be described.
You. In the present invention, the semiconductor substrate is vaporized by an etching solution,
While heating the semiconductor substrate, for example, etch by a predetermined thickness.
Ching. After etching, contained in the semiconductor substrate
The impurities are left on the etched surface. That
After that, the vaporized acidic reagent is liquefied by cooling,
Impurities are extracted. As described above, the etching process
Let's use the most suitable etching steam for this
Since the body substrate is etched while being heated, the semiconductor
Reaction with the substrate is promoted, and a predetermined depth of the semiconductor substrate
Etching can be performed at high speed and accurately
You. Furthermore, in the impurity extraction process, the optimal acid steam
Use semiconductor air and cool the semiconductor substrate.
Extracts impurities up to a predetermined depth on the body substrate as droplets
be able to. Further, the semiconductor substrate according to the first aspect of the present invention has a defect.
In the method of extracting pure substances, the semiconductor
Body substrate by etching to remove impurities in the semiconductor substrate
In the step of leaving on the substrate, including the step of discharging gas
It is characterized by: According to this, the etching steam
Generated in the process of etching a semiconductor substrate by using
Etching while discharging gas, so etch
Stable etching is possible without stopping
You. Therefore, it is possible to etch accurately to a predetermined depth of the semiconductor substrate.
I can do it. Further, the semiconductor substrate according to the first aspect of the present invention has a problem.
In the method for extracting a pure substance, the etching solution is vaporized.
After the step of vaporizing and the step of vaporizing the acidic reagent
Then, the generated steam is passed through a hydrophobic porous membrane to produce high-purity steam.
It is characterized by including a purifying process for obtaining a feeling. to this
According to the vapor of the etching solution and the vapor of the acidic chemical solution,
Pass through a hydrophobic porous membrane before feeding to a semiconductor substrate
Mist containing impurities in the vapor
Captured by the membrane. Because of this, background impurities
(Impurities contained in etching steam and acidic steam)
The degree can be kept low. The above-described object is the second invention.
1, heating the etching solution container as illustrated in FIG.
The first heating means 5, 22 and the container for the acidic chemical solution.
The second heating means 23 for heating and the semiconductor substrate
The reaction vessel 29 placed in front of the
First supply means 2, 27 for supplying to the reaction vessel;
8 and the vapor of the acidic reagent were supplied to the reaction vessel.
Supply means 28 and 8 for controlling the temperature of the semiconductor substrate.
Semiconductor substrate having temperature control means 7 for controlling
Is solved by an impurity extraction device. Next, the operation of the second invention will be described.
You. According to the present invention, an etching solution container and an acidic chemical solution
Reaction with containers and heating means to vaporize these chemicals
Means for controlling the temperature of the semiconductor substrate in the container.
Therefore, as in the description of the operation of the first invention,
Impurities on the surface of the semiconductor substrate and the predetermined depth
Object extraction can be performed at high speed and accurately. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the accompanying drawings. (Basic Configuration of Method and Apparatus for Extracting Impurities from Semiconductor Substrate)
FIG. 1 is a diagram illustrating impurity extraction from a semiconductor substrate according to an embodiment of the present invention.
1 shows a basic configuration of the device. This device is basically a gas generator
2, 27, 28, the reaction chamber 29, and the exhaust gas treatment device 10
It is composed. The surface in contact with reagents and reagent vapor
It is made of a corrosion-resistant material such as fluoroethylene. From each gas
The creatures 2, 27 and 28 have the same configuration. In FIG. 1, containers for reagents 2, 27, 28
With many small holes with a diameter of 50 μm or less above the opening of
Hydrophobic porous membrane such as porous tetrafluoroethylene
4, 17, 20 are arranged and cover the opening. container
Heating means 5, 22, 23 are provided below 2, 27, 28.
Arranged to heat the interior of the container. Heating temperature
The degree depends on the etching depth and the type of etchant.
It is selected from the range of temperature to 120 ° C. Impurities in reagents
Is converted into a mist with a particle size of several 100 μm by heating.
It is wrapped and evaporates, but with the hydrophobic porous membranes 4, 17, 20
Since it is shut off, it does not reach the inside of the reaction vessel 29.
It should be noted that instead of the hydrophobic porous membranes 4, 17, 20
By forming a filter member having a porous membrane, this member
May be covered. Each of the gas generators 2 and 27 supplies gas on the way.
It is connected to the system 8 and mixes both gases to flow gas into the reaction vessel
Connected to the unit. In these gas supply systems, steam is liquefied.
It is desirable to heat so that it does not occur. Inside the reaction vessel 29
In the above, a heating tank in which the semiconductor substrate 6 is a temperature control device
Alternatively, it is arranged in contact with the cooling tank 7. The reaction vessel is on the side
Heat evenly including the side surface to prevent liquefaction on the surface
Things are desirable. The temperature control device 7 supplies hot water
It is kept at a constant temperature above room temperature. In addition, place to cool
If the cooling water is supplied, a constant temperature below room temperature
Is kept. The means of temperature control is to supply hot water and cooling water.
Not only if the goal is achieved,
May be used. The reaction vessel 29 has a valve V2 and a pipe 12
An exhaust system provided with a semiconductor substrate 6 is provided.
After completion of the reaction, the reagent vapor passes through the pipe 12 and
It is bubbled into the exhaust gas treatment liquid 9 in the device 10. Anti
The reaction gas is discharged without accumulating in the reaction vessel 29
Therefore, the reaction can be promoted. Also, reagent vapor
By mixing and introducing an inert gas into the reaction vessel 29,
Gas emission can be made faster. Inert gas is nitrogen
Element or argon. In the reaction vessel 29, the piping 12
In addition, a pipe 15 is connected via a valve V4.
The pipe 15 supplies a gas such as an inert gas into the gas phase cracker.
Purge the reaction vessel to complete the etching process.
Used to make Exhaust gas treatment liquid 9 is alkaline
Exhaust gas is eliminated by bubbling using solution or water.
It is regarded as harmful and is discharged from the pipe 13 to the outside. It
On the container 2, 27, 28 side containing each reagent
Also, pipes 11, 24 and 25 connect valves V1, V7 and V8.
Each is connected to the exhaust gas treatment device 10 through the respective components. Piping 1
1, 24 and 25 are exhaust gas treatment liquids of the exhaust gas treatment device 10.
9 is introduced. In addition, if necessary, the gas generator 2, 2
Liquid dope is applied on the hydrophobic porous membranes 4, 17, 20 of 7, 28
Provide rain and drain from drain when liquid is generated
Is desirable. It is also connected to a gas generating vessel
Piping 14, 16, 19 and valves V3, V5, V6
Is a means for supplying an inert gas such as nitrogen. The acidic reagent used to extract impurities
The gas generator 28 is connected to the gas pipe 30 and
9 is connected to the gas inlet. Each gas supply line
Is preferably heated to prevent liquefaction. Then half
After cooling the conductive substrate 6, the acidic reagent gas is supplied to the reaction vessel 29.
By introducing the acid reagent, the acidic reagent is uniformly applied to the surface of the semiconductor substrate 6.
Droplets are formed, and impurities can be extracted. (When a Si substrate is used as a semiconductor substrate,
FIG. 2 shows a semiconductor device according to an embodiment of the present invention.
Impurity extraction device when Si substrate is used as body substrate
Show. FIG. 2 is a diagram for explaining FIG. 1 in more detail. Lottery
The discharge device is roughly divided into a hydrofluoric acid purified gas generator 4
0, nitric acid purified gas generator 80, acidic reagent purified gas generator
90, a gas phase cracker 50, and an exhaust gas treatment device 60.
It is. Each purified gas generator 40, 80, 90
Are commercially available reagent containers 42, 82, 92 on a support base.
After being placed and taking off this lid, containers 41, 81, 91
Are combined. Reagent containers 42, 82 and 92 are rubber
Heaters 45, 85 and 95 are wound around the temperature controller 4
6,86,96, which match the reagent type and conditions.
In addition, it can be heated to a predetermined temperature. Each of the reagent containers 41, 81, 91 has a gas
Piping 47, 49, 87, 89, 97, 99 and drain
48, 88, 98. Gas piping 47, 49,
87, 89, 97, 99 and drains 48, 88, 9
8 is a valve V49, V89, V99 and a valve V4
8, V88 and V98 are connected. Gas piping 47,
87 and 97 are connected to an inert gas source having a valve.
Have been. With this configuration, each reagent volume
The reagents in the vessels 42, 82 and 92 are heated to a predetermined temperature,
After purifying the generated reagent vapor, the gas piping 49, 89, 9
9 through a valve 49, 89, 99 to a gas pipe 70,
73 or 71 respectively. Gas phase decomposition device 50
Has a container on which a Si substrate 53 from which impurities are to be extracted is placed.
The container 51 has gas pipes 55, 56, 5.
7, 59 are connected, and further have a drain 58. Moth
Pipes 55, 57, 59 and drain 58
Valves V55, V57, V59 and V58 are connected
I have. An inert gas source having a valve is provided in the gas pipe 56.
Is connected. Each of the reagent containers 41, 81, 91 and
And the reaction chamber vessel 51 or at least the inner surface
Made of materials that are not attacked by reagents such as fluoroethylene
You. Further, the gas pipe 70 is made of
It is formed of a free tube of ethylene or the like. Exhaust gas
The processing device 60 includes gas inlets 63 and 64 and a gas outlet 6.
5 containing a container 61. Gas inlets 63 and 64
Is a free tube of tetrafluoroethylene, etc.
Valves V49, V89, V99,
And V55. Before or after starting the reaction with the Si substrate 53
After that, the steam of each gas generator 40, 80, 90 is
V49, V89, V99 are switched to the gas pipe 71 side to discharge
The gas is discharged to the gas processing device 60 and becomes harmless. Ma
In addition, in the gas phase decomposer 50, the decomposition of the Si substrate 53 is completed.
After that, the valves V57 and V59 are closed and the valve V55 is closed.
With the gas open, an inert gas is
The inside of the container of the phase decomposer 50 is purged. Of the gas phase cracker 50
There is hot water for heating or cooling the Si substrate 53
Alternatively, an inlet 67 and an outlet 68 for the cooling water are provided,
It is supplied to a heating tank or a cooling tank provided in the container 51.
It is. Drains 48, 88, 98, 58 are filled with liquid
It is for discharging in case of FIG. 3 shows the structure of the hydrofluoric acid gas purifier 40.
Here is an example. The reagent container 42 is a commercially available reagent container, etc.
Is threaded. A rubber heater is provided in the reagent container 42.
And the whole can be heated to a uniform temperature. container
The lower member 41b is connected to the screw portion, and the upper member 4
1a is connected to the lower member 41b to form a substantially closed structure.
ing. Tetrafluoroethylene or the like is used for the lower member 41b.
Is bonded to remove the mist.
Leave. Upper member arranged so as to surround the hydrophobic porous member 44
41a has gas pipes 47 and 49 and a drain 48.
Are formed. The drain 48 is connected to the reagent container 42
The reagent vapor that has passed through the hydrophobic porous membrane 44 to the outside is
When liquefied, open the V48 and remove the liquid reagent
It is for doing. Gas pipe 47 introduces inert gas
The gas pipe 49 is a pipe for performing the generated reagent.
With piping to supply steam to the outside together with inert gas
is there. The gas pipe 49 has a three-way cock type valve V4
9 is connected. FIG. 4 shows another embodiment of the hydrofluoric acid gas generator.
Is shown. The gas pipe 47 is inserted deeply into the reagent container 42.
It is supposed to be. The nitrogen supplied from the gas pipe 47
An inert gas such as a source gas bubbles the reagent in the reagent container 42.
A hydrophobic porous membrane 44 containing the reagent vapor
Is supplied to the outside from the gas pipe 49. Other points
Is similar to the hydrofluoric acid gas generator shown in FIG. FIG. 5 shows the structure of the gas phase cracker 50. container
51 is a hot water tank 52 formed inside the
It has a water tank 52. Of the hot water tank 52 or the cooling water tank 52
On the tetrafluoroethylene sheet serving as the upper plate, Si
Substrate 53 is placed, sample holder 54 is placed, and Si substrate
A predetermined area of 53 is exposed. On this exposed surface
Reacts with steam. Gas pipes 55 and 5 are provided in the container 51.
6, 57, 59 and the drain 58 are connected.
Two-way cocks were formed in the waste pipes 55, 57, 59
The valves V55, V57 and V59 are connected, and the drain 5
8 is connected to a valve V58. (Method of extracting impurities in Si substrate)
Example) Above, the basic configuration of the present invention and specific examples of the extraction device are shown.
Was. Next, the impurity in the Si substrate 53 is
An example of extracting is shown. Try Si substrate 53 in reaction vessel 51
Pressed by the material presser 54 and placed on the temperature control layer 52
You. Hot water of 80 ° C. is flowed into the temperature control tank 52 to
The plate 53 is heated to 80C. Remove nitrogen gas from pipe 56
It is supplied to the reaction vessel 51. Hydrofluoric acid gas generator 40 and nitric acid gas generation
The upper pipe 70 of the vessel 80 is heated to 80 ° C. At this time,
Valve V49 of hydrofluoric acid gas generator 40 and nitric acid gas
Valve V89 of the gas generator 80 to the exhaust gas treatment device side 60
Switch. Next, a hydrofluoric acid gas generator 40 and a nitric acid gas
A 2.0 l / min nitrogen gas was supplied from the gas pipes 47 and 87 to the generator 80.
Introduce hydrogen gas and bubbling hydrofluoric acid and nitric acid
You. At the same time, the hydrofluoric acid reagent container 42 and the nitric acid reagent container
Heat 82 to 80 ° C. using heaters 45 and 85.
This process is continued for a certain period of time to stabilize the steam. This steam
Open the hydrogen fluoride gas generator 40 and the nitric acid gas generator 80
Passing through the hydrophobic porous membrane 44 attached to the mouth.
Therefore, mist containing impurities in the chemical solution is captured.
You. Therefore, it is an ultra-high-purity etching vapor. Thereafter, a hydrofluoric acid gas generator 40 and nitric acid
The respective valves V49 and V89 of the gas generator 80 are
Switch to the phase decomposer 50 side, and from gas pipe 70 to vessel 51
Supply hydrofluoric acid and nitric acid vapor. At this time, gas phase decomposition
The nitrogen valve (not shown) of the vessel 50 is closed and hydrofluoric acid is
And open the valve V57 so that the vapor of nitric acid is supplied.
You. At the same time, the reaction product gas generated in the etching process
V55 can be opened to discharge the reaction product gas
So that In this way, the hydrofluoric acid and nitric acid are steamed.
Is supplied to the reaction vessel 51, and the Si substrate is
Switch. During etching, the Si substrate is heated
Etching because the reaction products are exhausted
The reaction is stably etched to a predetermined depth. Edge
After the etching, the impurities in the Si substrate 53
3 is left over. Thereafter, the valves V49 and
And V89 are switched to the exhaust gas side, and each steam is exhausted
Discharge to 60. At the same time, the container 51 of the gas phase cracker 50
Supply nitrogen gas, close valve V57 and release reagent vapor.
Shut off and open the valve V55 to supply nitrogen gas to the exhaust gas treatment unit 60.
And discharge the reagent vapor. At this time, nitrogen gas is also required
To 80 ° C. Fill the container 51 with nitrogen gas for 30 minutes
After purging and discharging residual gas, heating of nitrogen gas is
Stop and flow cooling water of -5 ° C into temperature control tank 52
Cools the Si substrate 53. Next, hydrochloric acid was used as an acidic reagent,
The upper part of the chemical gas generator 90 and the gas supply part 73 are heated to 60 ° C.
heat. Discharge valve V99 of acid reagent gas generator 90.
Switch to the other side. Next, add 2.0 l / mi to the acidic reagent gas generator.
Introduce n 2 nitrogen gas and bubble hydrochloric acid. at the same time
Heat hydrochloric acid to 60 ° C. using heater 95,
Is generated, and this process is performed for a certain period of time until the acid vapor stabilizes.
Continue the process. The vapor of the acidic reagent also passes through the hydrophobic porous membrane 20.
So that it becomes an ultra-high-purity acidic vapor.
The acidic reagent is hydrofluoric acid, nitric acid, vinegar instead of hydrochloric acid.
An acidic reagent such as an acid may be used. After the supply of steam is stabilized, an acidic reagent gas is generated.
Switch the greige valve V99 to the reaction vessel 51 side, and
The acidic vapor is supplied to the vessel 51 of the gas phase cracker 50 through the pipe 73.
Can be supplied. At this time, the nitrogen
Stop supply of element and open valve V59 to acidify reactor 51
Supply steam for 1 hour. At this time, the Si substrate 53 is cooled.
Therefore, a droplet is formed on the Si substrate 53. This
Of the analysis contained in the Si substrate 53 in the droplet of
Elephant impurities are incorporated. Then the acidic reagent
Switching the valve V99 of the gas generator 90 to the exhaust gas side,
The acidic vapor is discharged to a gas treatment device 60. At the same time, container 5
1 to supply nitrogen and close valve V59 for supplying acid gas
I will. Thereafter, the container 51 is opened, and the Si substrate 5 described above is opened.
Droplets formed on the surface of No. 3 with a micropipette
Recover and quantitatively analyze by graphite furnace polarized Zeeman atomic absorption spectrometry
I do. Si after the above etching and extraction steps are completed
As a result of measuring the etching amount of the substrate 53 with a step gauge, it was found that
It was etched by 5 μm. By the above method, the impurity content of the Si substrate 53 is
Of the Si substrate with normal device characteristics
Is that Fe is 1.5 × 10 ^Fifteen atom / cm ^Three Detected, and
S which is assumed to be contaminated with impurities due to abnormalities in chair characteristics
For i-substrate, Fe is 1.4 × 10 ¹⁶ atom / cm ^Three was detected. De
The Si substrate with abnormal vise characteristics is compared to the normal Si substrate.
Fe is detected one digit more, and the Si substrate is contaminated with Fe.
It is clear that this is one of the causes of abnormal device characteristics.
won. In the above embodiment, the hydrofluoric acid vapor and the nitric acid vapor were used.
Gas is mixed in the piping on the way and then supplied to the reactor
However, only one of them may be alternately flowed for a certain time.
For example, first nitric acid vapor for 3 minutes, then hydrofluoric acid
Alternating steam for 3 minutes, then nitric acid for 3 minutes
By supplying to the Si substrate, the
It is possible to suppress variation in the etching. Also
First, hydrofluoric acid and nitric acid are mixed in one gas generator.
To generate steam. This allows the gas generator
Two units for the mixed solution of hydrofluoric acid and nitric acid and for the acidic reagent
Therefore, the impurity extraction device can be simplified. Further, in the above embodiment, the acidic vapor is vapor phase separated.
The Si substrate 53 is cooled before being supplied to the dissolver 50
However, it may be cooled after supplying the acidic vapor. further,
As a method of generating a purified gas, in the above embodiment, as shown in FIG.
Put the pipe 47 into the reagent and bubble nitrogen gas.
But passed through the hydrophobic porous membrane 44 as shown in FIG.
The steam may be mixed with nitrogen gas from the pipe 47. Further, in the above embodiment, the acidic reagent
Although hydrochloric acid was used, hydrofluoric acid can also be used.
Wear. Also in this case, the number of gas generators becomes two and the extraction device
Is simplified. As described above, the present invention has been applied to the surface of Si substrate.
Or it can be etched quickly and accurately to a predetermined depth.
Low background impurity concentration,
Pure substance extraction can be performed. The present invention has been described in connection with the preferred embodiments.
However, the present invention is not limited to these. Various
It is obvious to those skilled in the art that changes, improvements, combinations, etc. are possible.
Will. As described above, according to the present invention, a half
Etching with etching steam while heating the conductive substrate
After that, while cooling the semiconductor substrate, the impurities are
Extracted as droplets, which has been difficult for semiconductor substrates
High-speed extraction of impurities to the surface of the plate or to a specified depth
And can be performed accurately. Further, etching vapor and acidic vapor are
As it is passed through a hydrophobic porous membrane, it is wrapped in mist
The impurities in the chemical solution are captured and the background impurities are concentrated.
Low-precision, high-precision impurity extraction becomes possible. In addition, half
In the process of etching the conductive substrate with etching steam,
Exhaust the reaction gas to etch the semiconductor substrate
More stable because the etching reaction with the etching steam is stable
Impurities can be extracted to a predetermined depth in complex semiconductor substrates.
You. Further, when ending the etching process,
Supply inert gas to exhaust etching vapor
The etching reaction can be stopped at any depth
You.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing a basic configuration of the present invention. FIG. 2 is a schematic side view showing an impurity extraction device according to an embodiment of the present invention. FIG. 3 is a partially cutaway side view showing a hydrofluoric acid gas generator of the impurity extraction apparatus shown in FIG. 2; FIG. 4 is a partially cutaway side view showing another example of the hydrofluoric acid gas generator of the impurity extraction device shown in FIG. 2; FIG. 5 is a partially broken side view of a gas phase decomposition section of the impurity extraction device shown in FIG. [Description of Signs] 1,26,27 Openings 2,27,28 Gas Generator Containers 3,18,21 Reagents 4,17,20 Hydrophobic Porous Membrane 5,22,23 Heating Means 6 Sample 7 Heating Tank or Cooling Tanks 8, 30 Gas supply system 9 Exhaust gas treatment liquid 10 Exhaust gas treatment containers 11, 12, 24, 25 Piping 14, 15, 16, 19 Gas introduction means V Valve 29 Reaction container 40 Hydrofluoric acid gas generator 41 Container 42 Reagent Container 44 Hydrophobic porous membrane 46, 86, 96 Temperature controller 47, 49, 55, 56, 57, 59, 70, 71, 7
2, 73, 87, 89, 97, 99 Gas piping 48, 58, 88, 98 Drain 50 Gas phase decomposer 51 Vessel 52 Heating or cooling tank 53 Sample 54 Sample holder 60 Exhaust gas treatment device 63, 64 Gas inlet 65 Gas Outlet 67 Warm water or cooling water inlet 68 Warm water or cooling water outlet

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/66 H01L 21/306 B (72) Inventor Shinsaburo Onda 1-chome, Matsuzakaira, Yamatocho, Kurokawa-gun, Miyagi No. 6 F-term in FUJIFILM Micro Devices Co., Ltd. (Reference) 2G042 AA10 CA03 CB06 EA03 FA01 FB02 GA01 4M106 AA01 BA12 CB01 DH01 DH44 DH45 DH46 DH55 5F004 AA16 BA20 BB18 BB25 BB26 BB30 BC03 DA29 DA20 DA20 DA02 DA00 DA20 DA00 5F043 AA02 BB02 DD10 DD13 EE03 EE07 EE16 EE22 EE27 EE37 EE40 GG10

Claims (1)

Claims: 1. A step of vaporizing an etchant, a step of heating a semiconductor substrate, etching the semiconductor substrate with a vapor of the etchant, and supplying an inert gas to the etching. Terminating the etching by discharging the vapor of the liquid to leave impurities in the semiconductor substrate on the semiconductor substrate; vaporizing an oxidizing reagent; and supplying the oxidizing vapor to the semiconductor substrate. And extracting the impurity from the semiconductor substrate by cooling the semiconductor substrate and liquefying the oxidizing vapor on the semiconductor substrate. 2. The method for extracting impurities from a semiconductor substrate according to claim 1, wherein an inert gas is mixed with the vapor of the etching solution and the oxidizing vapor. 3. The method according to claim 1, further comprising the step of discharging the gas in the step of etching the semiconductor substrate with the vapor of the etchant to leave impurities in the semiconductor substrate on the semiconductor substrate. Item 2. The method for extracting impurities from a semiconductor substrate according to Item 1. 4. The method according to claim 1, further comprising, after the step of vaporizing the etchant and the step of vaporizing the acidic reagent, a step of purifying the generated vapor through a hydrophobic porous membrane to obtain high-purity vapor. The method for extracting impurities from a semiconductor substrate according to claim 1. 5. The method according to claim 1, wherein the semiconductor substrate is a silicon substrate, and the etchant is hydrofluoric acid and nitric acid. 6. The acidic reagent is hydrochloric acid, hydrofluoric acid, nitric acid,
2. The method for extracting impurities from a semiconductor substrate according to claim 1, wherein the method is one of acetic acid. 7. The method for extracting impurities from a semiconductor substrate according to claim 1, further comprising the step of subjecting the vapor of the etching solution and the oxidizing vapor to an exhaust gas treatment. 8. A first heating means for heating a vessel for an etching solution, a second heating means for heating a vessel for an acidic chemical solution, a reaction vessel on which a semiconductor substrate is mounted, and said etching solution. First for supplying steam to the reaction vessel
A semiconductor substrate, comprising: a supply unit for supplying the vapor of the acidic reagent to the reaction vessel; and a temperature control unit for controlling the temperature of the semiconductor substrate. Impurity extraction equipment. 9. The semiconductor according to claim 8, further comprising gas introduction means for introducing an inert gas into the etching solution container, the acidic chemical solution container, and the reaction container. Substrate impurity extraction device. 10. The method according to claim 1, further comprising a step of purifying a vapor of said etching solution and a vapor of said acidic chemical solution, wherein said etching solution container and said acidic reagent container have a hydrophobic porous film at an opening thereof. An apparatus for extracting impurities from a semiconductor substrate according to claim 8. 11. The apparatus for extracting impurities from a semiconductor substrate according to claim 8, further comprising exhaust gas means for discharging a reaction product gas from said reaction vessel. 12. The apparatus according to claim 12, further comprising: said first supply means and said second supply means.
9. The apparatus for extracting impurities from a semiconductor substrate according to claim 8, further comprising heating means for heating the supply means. 13. An apparatus for extracting impurities from a semiconductor substrate according to claim 11, further comprising exhaust gas treatment means connected to said exhaust gas means. 14. An apparatus for extracting impurities from a semiconductor substrate according to claim 8, further comprising holding means for holding said semiconductor substrate on said temperature control means. 15. The apparatus for extracting impurities from a semiconductor substrate according to claim 14, wherein said holding means has a mechanism for exposing only a predetermined area of said semiconductor substrate.