JP3445765B2 - Substrate surface treatment method for semiconductor element formation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a surface of a substrate for forming a semiconductor element, and more specifically, it is applied on a substrate for forming a semiconductor element used for forming a semiconductor element in a step of forming an element or a step of forming a structure and then subjected to predetermined treatment. The present invention relates to a substrate surface treatment method for removing an organic compound or the like afterwards. Particularly, the surface treatment of the substrate for forming a semiconductor element for easily cleaning and removing the residual fine foreign matter after the oxidative decomposition removal treatment and the adhered fine foreign matter after the treatment without damaging the substrate and discharging the adverse substances to the surrounding environment Regarding the method.

[0002]

2. Description of the Related Art Generally, when a fine electric element or circuit is formed on a substrate, a photoresist is applied to form a pattern such as an arbitrary circuit on the applied surface, and the element pattern is processed by etching or the like. Form. After forming the element pattern, foreign substances such as photoresist and organic substances on the substrate are removed. It is well known that, in the formation of semiconductor elements, if the removal of the organic substances and the photoresist adhered to the substrate is not complete, inconvenience will occur in the subsequent fine electrical element formation process, Must be completely removed. To remove the photoresist, conventionally, a substance having a strong oxidizing power such as sulfuric acid or ozone (O ₃ ) is used, and either dry treatment or wet treatment may be performed depending on the type of photoresist, its coating characteristics, element forming conditions and the like. Has been adopted. The former is a method in which oxygen is used as a main process gas and is oxidized and decomposed in an active state such as oxygen plasma under vacuum to remove the oxygen. In the dry process, the ion implantation amount is usually about 1 × 10 ¹⁵ atoms / cm ^{2 in the} diffusion process.
This is often done in the above cases. On the other hand, the latter wet processing often a way of removing by oxidizing using O ₃ solution of a mixed solution or O ₃ were mixed and dissolved sulfuric acid and hydrogen peroxide in ultrapure water to ultrapure water is there.

After the dry treatment, a wet treatment is often performed. It is known that after dry-process oxidative decomposition of a photoresist, foreign matter containing residual carbon as a main component, silicon-based foreign matter, or floating foreign matter adhered after the photoresist removal treatment remains. The organic foreign matter remaining on the substrate remains in the form of fine particles or a thin film containing an organic material as a main component, which causes inconvenience in various device forming steps thereafter. Such organic foreign matter is conventionally removed by the above-described wet oxidative cleaning treatment, particularly, a cleaning treatment with a solution of sulfuric acid and hydrogen peroxide dissolved in ultrapure water.
Further, some resist which is difficult to remove even by dry oxidative decomposition treatment due to a large amount of ion implantation and strong baking of the photoresist is removed by wet oxidation cleaning treatment. Further, simple organic substances are removed by washing with ozone water in which ozone gas is dissolved in ultrapure water. For example , JP-A-9
In -255998 discloses, Ru Tei is proposed a method of UV irradiation in the presence of ozone gas for the removal of organic type fine foreign matter remaining on the substrate. Furthermore, after passing through an etching step for forming a device structure, particularly a dry etching step and a subsequent oxidative decomposition treatment step by plasma such as oxygen, metal contamination that is considered to be derived from a metal material of the device may remain. However, these metal impurities can be simultaneously removed by the oxidation treatment with sulfuric acid.

In manufacturing the device as described above,
The photoresist removal process is repeated at various stages. For example, in the etching process of silicon and metal and the diffusion process of source / drain, the photoresist is always present on the substrate and the photoresist removal process is performed. The general sequence of the conventional photoresist removing process has the following configuration, although it varies depending on the state of the photoresist. That is, (1) the above-mentioned dry oxidative decomposition treatment → (2) the above-mentioned wet treatment with a mixed solution prepared by mixing and dissolving sulfuric acid and hydrogen peroxide in ultrapure water → (3) mixing and dissolving ammonia and hydrogen peroxide in ultrapure water Oxidation / reduction wet cleaning treatment with the above solution → (4) A sequence of the following steps is adopted.

Prior to the transition to the next process, for example, (CVD
Prior to the step of re-applying a photoresist to form a structure on the substrate (before the film forming step such as), a cleaning process for removing minute foreign matters (hereinafter, simply referred to as particles) remaining on the substrate, So-called rinse processing is performed. This rinsing treatment generally uses an alkaline mixed solution in which ammonia, hydrogen peroxide solution, and ultrapure water are mixed. This is because the particles can be removed electrostatically or by light etching (lift-off) on the substrate surface with a mixed solution in which reducing ammonia and oxidizing hydrogen peroxide are mixed with ultrapure water. Further, Japanese Patent Laid-Open No. 10-41262 proposes that metal particles can be removed by using hydrogen water obtained by dissolving hydrogen gas in carbonated water or ultrapure water to reduce corrosion of metal wiring and the like. In addition, JP-A-10-12825
Japanese Patent Laid-Open No. 3 proposes cleaning and rinsing treatment by ultrasonically irradiating the substrate with hydrogen water obtained by dissolving hydrogen gas in ultrapure water of 0.05 ppm or more.

[0006]

However, in the general sequence of the photoresist removing process described above, (1) dry oxidative decomposition treatment, (2) wet treatment, (3) oxidation / reduction wet cleaning treatment, and (4) next The various cleaning processes conventionally used in the rinse process before shifting to the process have the following problems, respectively. That is, in the conventional dry processing, it is general to oxidize and decompose the photoresist using oxygen plasma, and the plasma state such as oxygen plasma is active in a high energy state, so that fine wiring and circuit of a semiconductor element are often used. , Others may damage the material forming the structure. Especially recently, copper (C
There is a tendency to use chemically reactive activators such as u), and oxidation of these activators is a problem. Furthermore, since the plasma state cannot be obtained under normal pressure,
The process chamber must be vacuumed and the substrate must be physically harsh. Further, there is a problem that the processing apparatus itself is damaged by the plasma and a constituent material of the apparatus, for example, a stainless material is attached to the substrate.

Further, the conventional wet treatment uses a solution in which sulfuric acid and hydrogen peroxide are mixed and dissolved in ultrapure water as described above, and the solution has an oxidation-reduction potential (hereinafter, simply referred to as ORP) in an acidic region. However, there is a problem in that particles contained in a liquid such as photoresist that has been oxidatively decomposed and minute fragments that are decomposed from the photoresist are reattached to the substrate due to the zeta potential. In addition, as described above, AlSi
The above solution cannot be used for removing the photoresist remaining after forming a metal pattern of a chemically reactive wiring material such as Cu, Al or Cu. Further, the above solution is usually 10
Since it is used after being heated to 0 ° C. or higher, SOx, which is a chemical contaminant in a clean room, which has become a problem these days, may be discharged. Furthermore, sulfuric acid has a higher cost than other cleaning treatment chemicals, and there is a problem in terms of safety such as corrosion of chemical liquid lines and the like, and handling is difficult. Sulfuric acid-based substances are generally difficult to remove, a large amount of ultrapure water is used for rinsing chemicals, and there is a problem in waste liquid treatment.

[0008] In the method of UV irradiation in the presence of a pre Kitoku No. 9-255998 JP proposal ozone, which corresponds to the organic type fine foreign matter can not be applied to the photoresist stripping process. In addition, in the reduction / oxidation solution cleaning process in which ammonia and hydrogen peroxide are mixed and dissolved in ultrapure water, ammonia generally has a relatively high iron (Fe) concentration, and Fe is specifically adsorbed on the substrate used for semiconductor element formation. It is also known that Fe is an impurity that should be removed because it is feared that Fe will adversely affect the device characteristics, so Fe is not a preferable cleaning treatment. Further, the reducing / oxidizing solution is, for example, 70
Since the substrate is heated to a temperature of not less than 0 ° C. and used, the surface of the substrate or a thin film forming a structure may be etched to give undesired irregularities on the substrate to deteriorate the surface roughness. Further, the wiring material such as Al may also be corroded, and ammonia contamination in the clean room, which has been a problem these days, may occur. Further, in the washing with ammonia-hydrogen, the hydrogen peroxide solution may oxidize the substrate to give an undesired oxide film, which may impair the electrical characteristics of the device. To a further <br/>, before Kitoku method of 0.05ppm or more hydrogen gas proposed in Unexamined 10-128253 JP immersed ultrasonic irradiation the substrate to hydrogen water, dissolved in ultrapure water to a rinse treatment However, it does not disclose or suggest the removal of the organic compound-based foreign matter or the residue after the dry oxidative decomposition, which is the object of the present invention.

The present invention removes an organic compound (photoresist) existing on a semiconductor element forming substrate used for forming a semiconductor element, and removes a minute foreign substance containing an organic compound as a main component after the removal processing. In view of the fact that the conventional cleaning process is still not sufficient as described above, the removal of the photoresist and the remaining small amount of foreign matter such as organic compounds and particles without damaging the substrate surface or structure by solving various problems of the conventional method are solved. It is an object of the present invention to develop a method for treating the surface of a substrate for forming a semiconductor element, which effectively removes the impurities and does not adversely affect the characteristics of the semiconductor element in the subsequent element forming step and film forming step. For the above-mentioned purpose, the inventors reviewed various conventional cleaning methods and, at the same time, earnestly examined the cleaning method again. As a result, as a dry process, instead of the plasma oxidation method which causes damage to the substrate etc. and has a problem in operability, the ozone gas is processed in a predetermined heating state,
Furthermore, by wet treatment with ozone water and / or ultrasonic active hydrogen water, an element formation substrate having excellent element characteristics is finally obtained, and the surface treatment of the semiconductor element formation substrate has little influence on the device and has good operability. A method was found and the present invention was completed.

[0010]

According to the present invention, a resist existing on a semiconductor element forming substrate used for forming a semiconductor element is removed, and a minute foreign matter containing an organic compound as a main component remaining after the removal processing. Is a method of removing the ozone, and (1) an ozone gas treatment step of directly or indirectly heating the substrate to room temperature or higher and treating it with an ozone-containing gas in a dry atmosphere; Each of an ozone water treatment step of treating with ozone water dissolved in pure water, and (3) a hydrogen water treatment step of treating hydrogen-containing gas activated by ultrasonic waves with hydrogen water dissolved in ultrapure water
Substrates for forming a semiconductor element, wherein the steps (1), (2), and (3) are performed in the order , and ozone water having an ozone concentration of 20 to 60 ppm is used in the ozone water treatment step (2). A surface treatment method is provided.

In the method for treating the surface of a substrate for forming a semiconductor element of the present invention, it is preferable that the ozone concentration of the ozone-containing gas in the ozone gas treatment step is 4 to 8% by volume and the heating temperature is 300 to 350 ° C. . It is preferable to treat the ozone gas treated substrate treated in the ozone gas treating step in the ozone water treating step one or more times, and then treat it in the hydrogen water treating step. It is preferable that the ozone water treatment substrate treated in the ozone water treatment step is treated in the ozone gas treatment step and then in the hydrogen water treatment step. Furthermore, it is preferable that after the ozone gas treatment substrate treated in the ozone gas treatment step is treated in the hydrogen water treatment step, it is further treated in the ozone water treatment step, and further in the hydrogen water treatment step. Step and a series of surface treatments including an ozone water treatment step and / or a hydrogen water treatment step are preferably continuously repeated two or more times, and the ozone gas treatment step and the ozone water treatment step and / or hydrogen water are also preferable. In a series of surface treatments including treatment steps, each step is preferably repeated twice or more.

[0012] Substrate surface treatment for semiconductor element formation of the present invention
According to the method of processing, the substrate for forming a semiconductor element is spread on the dopant.
It can be applied to the substrate in the diffusion process or etching process.
In addition, it contains materials that are chemically reactive such as Al, W, and Cu.
It can also be applied to substrates. Further, the semiconductor element formation of the present invention
The substrate surface treatment method for the
100ppm or less of acid components such as hydrochloric acid in ozone water used
Lower, preferably about 10 ppm, and / or the hydrogen water
Alkaline components such as ammonia in hydrogen water used in the treatment process
Content of 100 ppm or less, preferably about 10 ppm
Can be processed.

Since the present invention is configured as described above and the substrate for semiconductor element formation is subjected to the dry oxidative decomposition treatment with the ozone-containing gas such as ozone gas as the ozone gas treatment step, unlike the conventional oxygen plasma treatment, the substrate or the fine substrate on the substrate is finely divided. The organic compound on the substrate can be decomposed by oxidation without damaging the electric circuit, wiring, element structure, and constituent materials. For example,
Even in a device substrate made of a chemically active material such as Al, W, and Cu, ozone gas does not pass through a protective film such as silicon nitride and oxidizes an organic compound on the substrate without damaging the wiring material. Can be decomposed. Particularly, unlike the conventional dry ozone treatment, the temperature on the substrate surface is heated to about 300 ° C. and the ozone-containing gas having a higher ozone concentration than that of the conventional one is used, so that the resist can be effectively removed. Further, since the plasma is not used, it is not necessary to make the inside of the processing chamber vacuum, the substrate can be processed under a moderate condition of normal pressure, stress on the substrate can be reduced, and damage to the material constituting the device can be reduced. Further, if necessary, surface treatment having ozone gas resistance can be performed to prevent damage to the device.

In the wet treatment with ozone water, which is the ozone water treatment step, the same ozone-containing gas used in the dry ozone gas treatment step is dissolved in ultrapure water to obtain ozone water having oxidizing power, and dry oxidation in the ozone gas treatment step is carried out. Oxidative decomposition of the residue after the decomposition treatment or a small amount of the organic compound which is the resist remaining after the dry treatment is performed. Ozone water causes less damage to a metal material such as Al than an acidic solution such as sulfuric acid, and can effectively remove a residue or an organic compound while minimizing corrosion of a wiring material. Further, whereas the conventional treatment with the ultrapure water mixed solution of sulfuric acid and hydrogen peroxide is conducted at a high temperature of 100 ° C. or higher, the ozone water treatment of the present invention can be basically conducted at room temperature. It does not emit SOx, which is a chemical pollutant in the clean room, which has become a problem these days. In addition, the waste liquid after treatment is immediately separated into ozone gas and water,
Ozone gas can be decomposed into water and oxygen by using the flare method and the UV lamp method, and the waste liquid treatment cost can be reduced as compared with the conventional treatment using sulfuric acid. The ozone water used for the treatment is basically water, and the amount of rinse used with ultrapure water can be reduced as compared with the conventional wet oxidation method using sulfuric acid. In the ozone water treatment step of the present invention, if necessary, an acid component such as hydrochloric acid may be added in an amount of about 100 ppm, preferably 10 ppm. This is for removing metal contaminants.

Since the hydrogen water treatment step of the present invention uses hydrogen water in which a hydrogen gas-containing gas is dissolved in ultrapure water, it does not use a large amount of ammonia as in the conventional wet oxidation treatment and Fe contamination. The level can be reduced, and ammonia contamination in the clean room, which is a problem, does not occur. Further, since ultrasonic waves are activated and activated, foreign substances can be effectively removed. Whereas the conventional treatment with a mixed solution of ammonia and hydrogen peroxide in ultrapure water is performed at 70 ° C. or higher as described above, the hydrogen water treatment of the present invention can be performed basically at room temperature by etching or the like. Surface roughening is reduced. Further, as in the ozone water treatment step, hydrogen water is basically water, and the amount of rinse used by ultrapure water is reduced. In the hydrogen water treatment step of the present invention, if necessary, an alkaline component such as ammonia may be added in an amount of about 100 ppm, preferably 10 ppm. This is to improve the efficiency of removing fine particles.

Further, the semiconductor element forming substrate surface treatment method of the present invention can be carried out as a series of continuous treatments by setting a sequence so as to include the ozone gas treatment step, the ozone water treatment step and the hydrogen water treatment step. . In this case, the ozone gas treatment step is basically an essential step and is usually adopted as the first step. However, for example, the ozone gas treatment step can be performed after the ozone water treatment step. In this case, the ozone water oxidative decomposition is initiated by catalytically utilizing the surface water content after the ozone water treatment, and finally the dry type is used. It performs ozone oxidation decomposition. Further, it is also possible to perform the treatment only in two steps of the ozone gas treatment step and the hydrogen water treatment step. For example, if the substrate material can be treated without fear of oxidation, ozone gas treatment can be intensively performed to almost completely oxidize and decompose the resist and organic compounds, and the ozone water treatment can be omitted. Furthermore, in the semiconductor element forming substrate surface treatment method of the present invention, particularly, the cleaning treatment by the ozone water treatment step and the hydrogen water treatment step can be continuously performed by using the same cleaning apparatus, and the treatment time and the treatment cost can be reduced. It can be significantly reduced compared to the past. That is, in the conventional method of cleaning and removing the photoresist and fine foreign matter on the substrate, each cleaning step after the dry oxidative decomposition treatment is separated, and the processing tanks thereof are also completely separated,
On the other hand, intermediate rinsing with ultrapure water was required before moving to the next step, which increased processing time and processing cost.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail. In the present invention, the substrate to be surface-treated is a semiconductor element, that is, a substrate having a fine electric element or circuit, and various semiconductor element formation such as a semiconductor substrate such as silicon (Si) or an insulating substrate such as glass. In particular, it is a substrate for use after formation of minute electric elements and circuits or local dopant diffusion or etching treatment in a semiconductor element manufacturing process. The present invention is a surface treatment method mainly consisting of oxidative decomposition of the photoresist remaining on the surface of the substrate and subsequent cleaning treatment of residual foreign matters. That is, the first is a dry oxidative decomposition process using ozone gas, and the second is
After that, mainly the remaining organic foreign matter is treated with ozone water, and the third is a treatment in which residual particles are then treated with hydrogen water in combination.

In the ozone gas dry oxidative decomposition treatment which is the ozone gas processing step of the present invention, the substrate to be processed is heated to room temperature or higher, preferably 300 to 350 ° C., without using oxygen plasma used in the conventional dry oxidative decomposition. Then, an ozone-containing gas of about 4 to 8% by volume obtained by the silent oxygen discharge is introduced into the processing chamber of the apparatus. In the ozone gas treatment step of the present invention, for example,
A single-wafer oxidative decomposition treatment apparatus as shown in the schematic explanatory view of FIG. 1 can be used. In FIG. 1, the chamber 11 of the oxidative decomposition apparatus 10 is designed to be automatically opened and closed, and the semiconductor element forming substrate 1 is provided inside the chamber 11.
It has a susceptor 13 made of quartz that holds 2 points at 3 points. The semiconductor element forming substrate can be fed in and out and allowed to stand still on the quartz susceptor 13 in conjunction with opening and closing of the chamber. The chamber 11 is hermetically sealed before the oxidative decomposition treatment with ozone gas, and the substrate 12 is heated from the back side by the heater 14 via the susceptor 13. On the other hand, the ozone-containing gas can be obtained by using a silent discharge type or electrolytic type ozone generator of an oxygen-containing gas such as air or oxygen. In FIG. 1, for example, an ozone generator 15 by silent discharge is installed in an oxidative decomposition apparatus 10, and an oxygen-containing gas is sent to a silent discharge ozone generator 15 through a filter 16 to contain ozone having a concentration of about 4 to 8% by volume. A gas is generated and introduced into the diffuser 17 arranged in the chamber 11. The ozone-containing gas is efficiently diffused in the chamber 11 by the diffuser 17. After the ozone oxidative decomposition treatment, nitrogen gas is introduced into the chamber 11 through the filter in the same manner as the oxygen-containing gas, and ozone in the treatment atmosphere is promptly replaced and purged. At this time, the purge exhaust gas is
The ozone gas is sent from the exhaust line 18 to an ozone decomposition treatment device (not shown) and the ozone gas is exhausted outside the device as oxygen gas. The flow rate of the ozone-containing gas from the ozone generator 15 and the purging nitrogen gas are controlled by a flow rate (mass) controller arranged in the feed line, respectively, and the chamber 11 is controlled.
Sent to. A spin motor 19 is arranged below the chamber 11 to rotate the susceptor 13 and rotate the substrate placed thereon.

In the present invention, the ozone water treatment step usually performed after the ozone gas treatment step is a wet cleaning treatment with ozone water, and the ozone concentration in the ozone water is about 20.
-60 ppm is preferable. The oxidizing power of ozone water depends on the dissolved ozone concentration, and can be appropriately selected within the above ozone concentration range depending on the properties of the substrate to be treated. For example, if it is a pollutant due to a gaseous organic substance or a residue after oxidative decomposition treatment, it may have a medium concentration of about 20 to 30 ppm, or if a large amount of ion implantation is performed or a heat-treated resist is subjected to oxidative decomposition treatment. Removal of residual organic compounds is about 50-6
A high concentration of 0 ppm is suitable. The ozone water of the present invention is
By increasing the concentration of dissolved ozone by pressure dissolution and using it, oxidative decomposition of the above-mentioned residual organic compound is possible. In the present invention, as the ozone-containing gas, an ozone-containing gas obtained by a silent discharge of oxygen or the like can be used as in the ozone-containing gas treatment, and an ozone-containing gas obtained by an electrolytic ozone generator can be used. it can. The generated ozone-containing gas is pressurized to be used as high-concentration ozone water, whereby a strong organic residue remaining after photoresist ashing and a resist remaining after ashing can be removed by ozone water treatment. On the other hand, the ozone-dissolved water liquid used in the conventional wet ozone cleaning of the substrate is generally 2
The dissolution level was about 0 ppm, and it was not possible to remove the organic residue and the resist after the above ashing with such an ozone solution. Further, the wet treatment system of the ozone water treatment step of the present invention is different from the conventional wet treatment performed in an open system, and since it is performed in a closed system because it is a pressure treatment, danger can be avoided in terms of safety. Further, since the ozone water is prepared by using the ozone-containing gas generated from the ozone generator and is not stored in the chemical liquid tank, the liquid property is stable, and the substrate property after the treatment has little variation.

The hydrogen water treatment step in the present invention is a wet cleaning treatment similar to the above ozone water treatment step, and is a cleaning treatment with hydrogen water. In the present invention, cleaning is performed by ultrasonic irradiation using hydrogen water in which at least 1 ppm or more of hydrogen gas is dissolved in ultrapure water. As described above, the method of immersing a substrate in hydrogen water having a hydrogen gas content of 0.05 ppm or more and irradiating ultrasonic waves proposed in JP-A-10-128253 discloses a cleaning / rinsing treatment, and in particular, In the present invention, the removal of fine foreign matters originating from the organic residue and organic compounds remaining after the dry oxidative decomposition of the photoresist on the substrate by the ozone-containing gas targeted in the present invention, that is, the fine foreign matters remaining after ashing the resist, It does not disclose any removal. Moreover, a suitable hydrogen dissolution concentration for practically washing and removing these is at least 1 ppm or more, preferably 1.2 to 2.0 ppm, which were first confirmed by the inventors. As the hydrogen-containing gas used in the hydrogen water treatment step, the hydrogen gas obtained by the electrolysis method can be used similarly to the ozone-containing gas in the ozone water treatment step. Also, the ORP value of hydrogen water is
It is about −550 mV, and the surface potentials on the particles and the substrate are negatively charged, so that they are efficiently removed by electrostatic repulsion. Further, particles are physically removed by the effect of cavitation by ultrasonic waves, and radicals such as hydrogen and hydroxyl groups are generated, so that an extremely thin organic film or the like is decomposed. In addition, since hydrogen water basically uses electrostatic repulsion, the composition of particles is less affected by the chemical removal method, and the type of ion-implanted material is less affected.

In the present invention, the wet cleaning treatment of the ozone water treatment step and the hydrogen water treatment step can be carried out by using the same apparatus as needed, and the wet cleaning treatment of the ozone water treatment step and the hydrogen water treatment step can be performed. It can be done continuously and collectively. For these wet cleaning treatments, for example, a wet cleaning treatment apparatus as shown in the schematic explanatory view of FIG. 2 can be used. The same components as those of the apparatus shown in FIG. 1 among the components of the wet cleaning apparatus 20 of FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. In FIG. 2, the substrate 12 to be processed is held in the cup 21 of the chamber 11 by the vacuum chuck 22. The chuck method includes a vacuum method and a side holding method, and any method may be used. On the other hand, the wet cleaning treatment device 20 includes an ozone water preparation device 2
3 and a hydrogen water preparation device 24 are installed, the concentration of ozone water and hydrogen water are adjusted, and the flow rate is controlled by a flow rate (mass) controller.
1 is flowed into. Substrate 12 held by chuck 22
On the other hand, ozone water is discharged through a nozzle (not shown), and hydrogen water is a movable ultrasonic wave generator-equipped dispenser 2
Emitted from 5. Further, the wet cleaning processing apparatus 20 is provided with an acid component supplier 26 and an alkaline component supplier 27,
If necessary, trace amount in ozone water to remove metal contamination,
For example, acid components such as hydrochloric acid and sulfuric acid added at 10 ppm, and a trace amount in hydrogen water to improve the efficiency of removing fine particles,
An alkaline component such as ammonia added at 10 ppm can be injected into the chamber cup 21 simultaneously with ozone water or hydrogen water and / or by being mixed with ozone water or hydrogen water. Further, an ultrapure water (DIW) supply mechanism 28 is provided so that the ultrapure water can flow out from above and below the inside of the chamber cup 21 through the nozzle to wash the substrate after each solution washing process. After the wet cleaning treatment with each chemical, the substrate rinsed with ultrapure water is rotated at 3000 rpm and dried by a so-called spin dry method. Further, a casing exhaust facility (not shown) is appropriately arranged so that the dissolved ozone gas is not released into the atmosphere from the inside of the cleaning device due to the inflow of highly concentrated ozone water or the like. Further, in order to prevent the high-concentration ozone gas from being directly exhausted, the ozone gas is sent to the thermal decomposition treatment device or the UV lamp decomposition treatment device (not shown) from the exhaust line 18 similarly to the oxidation decomposition device 10 of FIG. Exhaust out of the device as gas. In the examples described below, a thermal decomposition treatment apparatus was used to decompose and discharge.

In the present invention, for example, when the ozone gas treatment step is followed by the ozone gas treatment step, the three steps may be carried out by the same apparatus. Therefore, the surface treatment operation is simplified, and the equipment cost and treatment time for a series of treatments are reduced as compared with the conventional method, which is preferable. However, each wet cleaning process may be performed using different devices depending on design conditions, operating conditions, and the like. The apparatus for performing the wet cleaning treatment of the present invention is an apparatus for generating ozone water, or ozone by connecting to a portion having a mechanism for making ozone water by gas-liquid contact of ozone-containing gas and ultrapure water. Can supply water. The same applies to hydrogen water. Treatment with ozone water or hydrogen water
All can be performed at room temperature, for example, 25 ° C., and may be appropriately heated if necessary. Further, as described above, since both the ozone-containing gas and the hydrogen gas can be obtained in the electrolytic ozone generator, the method for treating the substrate surface of the semiconductor element of the present invention and the electrolytic ozone generator are combined to produce an anode. By using the ozone-containing gas generated from the ozone gas treatment step and the ozone water treatment step and using the hydrogen gas generated from the cathode in the hydrogen water treatment step, the ozone-containing gas, ozone water and hydrogen water required for each treatment step can be efficiently used. Manufacture, the device can be simplified, and the operation is simple.

[0023]

EXAMPLES The present invention will be described in more detail based on the following examples. However, the present invention is not limited to the following examples. (Sample preparation) A silicon (Si) wafer prepared by the 8-inch (8 ") CZ method (Czochralski method) as a sample is dissolved by dissolving NH3 and hydrogen peroxide in ultrapure water with a wet immersion type cleaning device. Was immersed in a solution (NH3: ultrapure hydrogen peroxide: ultrapure water = 1: 1: 8) and subjected to ultrasonic irradiation at 70 ° C. The treated wafer was dried and then subjected to i-line (36
(5 nm) A photosensitive organic compound was applied by a single-wafer spin coater to a film thickness of about 12,000 Å, and the whole surface was exposed to i-line for 25 seconds to expose the photoresist. After exposure, the wafer was baked in a nitrogen (N ₂ ) gas stream. Also,
The inside of the chamber is suctioned and depressurized to about 10 ⁻³ Torr and CF _{4 is} added.
Dry etching was performed for 40 seconds to obtain sample A. Also,
Similarly to the above, after applying an organic compound and exposing, BF ₂ or A
A sample in which s was ion-implanted was prepared. The dose amount of BF ₂ is 5.0 × 10 ¹³ atoms / cm ² (accelerating voltage: 1
5 keV) is the sample B and the dose amount of As is 8.0 × 10.
¹³ atoms / cm ² (accelerating voltage: 30 keV) was used as the sample C and the dose amount of BF ₂ was 3.0 × 10 ¹⁵ atoms.
/ Cm ² (accelerating voltage: 20 keV) was used as sample D, and the dose amount of As was 2.0 × 10 ¹⁵ atoms / cm ² (accelerating voltage: 40 keV) as sample E. Table 1 shows sample preparation conditions
Are summarized in. For each sample, the film thickness of the organic compound was measured by a light interference type film thickness measuring device and is also shown in Table 1.

[0024]

[Table 1]

Example 1 Samples A, B and C were sequentially treated in the sequence of ozone gas treatment step (dry ozone oxidative decomposition treatment) → ozone water treatment step (ozone concentration: 20 ppm) → hydrogen water treatment step. Oxidation / decomposition device 10 having the same structure as that of FIG.
Was used to heat each sample on the susceptor 13 for about 60 seconds before the ozone gas treatment step. Sample A is
Ozone-containing oxygen gas having an ozone concentration of 4% by volume was circulated at a temperature of 300 ° C. for 72 seconds at a flow rate of 10 l / min for treatment. Sample B was treated at a temperature of 300 ° C. for 180 seconds by flowing an ozone-containing oxygen gas having an ozone concentration capacity of 5% at a flow rate of 12 liters / minute. Sample C was treated by flowing ozone-containing oxygen gas having an ozone concentration of 5% by volume at a temperature of 350 ° C. for 200 seconds at a flow rate of 14 l / min. The thickness of each of the samples was measured with an optical interference type film thickness measuring device, and the results are shown in Table 2. As a result, it was found that the photoresist on the substrate was almost completely removed by the ozone-containing gas oxidative decomposition treatment, and no residue was confirmed. Therefore, the particles on the substrate after the ozone gas treatment step were measured with a laser light scattering type particle counter to have a particle size of 0.2 μm or more. According to the result, it was found that the photoresist itself did not remain on the substrate, but the residue after the ozone gas treatment remained. Also, some photoresist pieces and the like were confirmed on the substrate surface. These were foreign substances containing carbon and silicon oxide compounds as main components. Further, it was confirmed that relatively large particles remained.

[0026]

[Table 2]

Next, each sample subjected to the oxidative decomposition treatment in the ozone gas treatment step as described above was washed with ozone water using the apparatus having the same structure as that shown in FIG. Ozone water is discharged from the nozzle of the device 20, and each sample is 1000 r
The sample A was rotated for 30 seconds, the sample B was processed for 45 seconds, and the sample C was processed for 60 seconds. 0 before and after processing.
Particles of 2 μm or more were measured with a laser light scattering type particle counter, and the results are shown in Table 2. After the ozone water treatment process, the number of particles counted is reduced, and the particle size peak is about 5 μm to about 1 μm.
It can be seen that the relatively large foreign matter such as the photoresist pieces, which has been shifted to, is oxidized and decomposed by the ozone water treatment.

Next, in order to remove fine particles remaining in each sample treated in the above ozone water treatment step, the sample was treated with hydrogen water. 1000r for each sample A, B and C
It was rotated at pm and hydrogen water was discharged from the dispenser 25 with an ultrasonic generator of the apparatus 20 and treated for 20 seconds. The frequency of ultrasonic waves at this time was 1.5 MHz. Particles before and after the treatment were similarly measured with a laser light scattering type particle counter, and the results are shown in Table 2. From these results, it is clear that the number of particles remaining after the treatment of this example is reduced to a level comparable to or higher than that of the conventional method.

Example 2 Ozone gas treatment step → ozone water treatment step (ozone concentration:
Samples A, D and E were sequentially treated in the sequence of 60 ppm) → hydrogen water treatment step. Each sample was heated for about 60 seconds before the treatment in the first ozone gas treatment step. Sample A was treated at a temperature of 300 ° C. for 72 seconds by flowing an ozone-containing oxygen gas having an ozone concentration of 4% by volume at a flow rate of 10 l / min. Sample D has a flow rate of ozone-containing oxygen gas of 5% at an ozone concentration capacity of 5% for 180 seconds at a temperature of 350 ° C.
It was circulated and processed at a rate of 1 liter / minute. Sample E has a temperature of 350
Ozone-containing oxygen gas having an ozone concentration of 6% by volume was flowed at a flow rate of 16 l / min for 200 seconds at 0 ° C. for processing. For each sample, the photoresist thickness was measured with an optical interference type film thickness measuring device, and the results were treated as shown in Table 3. In addition, since the photoresist remained in the center of the substrate of each sample after the oxidative decomposition treatment, particles were not measured.

[0030]

[Table 3]

Then, each sample subjected to the oxidative decomposition treatment in the ozone gas treatment step was washed with ozone water in the same manner as in Example 1. Rotate each sample together at 1000 rpm,
Sample A was processed for 30 seconds, sample D for 90 seconds, and sample E for 120 seconds by ejecting ozone water from the nozzle. Particles of 0.2 μm or more before and after the treatment were measured with a laser light scattering type particle counter, and the results are shown in Table 3. In each of the samples after the ozone water treatment, almost no foreign matter, which is considered to be a photoresist piece, was confirmed, and the residual photoresist was completely removed. Most of the particles could be determined to be carbon or silicon.

Next, in order to remove particles remaining in each sample treated in the above-mentioned ozone water treatment step, the sample was treated with hydrogen water. Each sample A, D and E was rotated at 1000 rpm and hydrogen water was discharged from the dispenser 25 with an ultrasonic generator and treated for 20 seconds in the same manner as in Example 1. The frequency of ultrasonic waves at this time was 1.5 MHz. Particles before and after the treatment were similarly measured with a laser light scattering type particle counter, and the results are shown in Table 3.

From these results, the substrate treatment in the above sequence is performed with the ozone water treatment step at an ozone concentration of about 60 p.
It is apparent that the use of pm high-concentration ozone water enables not only removal of organic substances but also photoresist stripping. Thus, in particular, is effective when it is desired to avoid as much as possible oxidative degradation treatment, for example, depending on the conditions of the ion implantation stop dry processing a certain processing, after conventional oxidation decomposition treatment of sulfuric acid and hydrogen peroxide It can be applied in the same manner as the treatment with the ultrapure water mixed solution. As a result, it became clear that in the ozone gas treatment step, the oxidative decomposition can be limited to the photoresist removal to some extent, and the next ozone water treatment can simultaneously remove the photoresist and the organic matter. Example 2
It is clear that the number of particles remaining after the treatment (1) is reduced to a level comparable to or more than that of the conventional method as in the first embodiment.

[0034]

The present invention is a substrate surface treatment method for removing unnecessary photoresist after forming various element structures of a substrate for forming a semiconductor element, using an ozone-containing gas, high-concentration ozone water and hydrogen water. Therefore, compared with the conventional method using an acid component such as sulfuric acid or ammonia or an alkaline component and an organic solvent for removing organic substances on the substrate, the environmental load is small and the cost is low without damaging the element structure, It has excellent industrial utility. Further, since the acid component, the alkali component and the organic solvent used in the above conventional method are not used,
Damage is reduced without significantly corroding the structure of semiconductor elements and wiring materials. In addition, it is possible to minimize the deterioration of the electrical characteristics of the device, improve the reliability of the element performance, reduce the electric resistance, reduce the power consumption, speed up the element performance, and at the same time improve the manufacturing yield. In addition, it is possible to reduce the running cost and improve the safety of the semiconductor manufacturing apparatus.

Many reports have hitherto been made on the treatment of semiconductor element forming substrates, such as dry oxidative decomposition reaction using ozone gas and treatment with so-called functional water such as ozone water and hydrogen water. However, the present invention can reduce damage to the semiconductor element structure and the forming material because it does not use high-energy substances such as plasma or high-purity conventional chemicals, and combines dry and wet treatments. This makes it possible to process the substrate more efficiently. Since ozone gas has a strong oxidizing power and is not in a high energy state like plasma, mainly organic compounds on the substrate can be removed without causing problems such as permeation through the structure. Although there are many reports on the treatment of ozone water and the like, the present invention enables high-concentration ozone water and ozone gas at high temperature to directly peel off a large amount of organic compounds such as photoresist, which is difficult to remove, and a dry method. It is the first proposal in the present invention to use high-concentration ozone water for cleaning treatment after oxidative decomposition treatment, or to combine high-temperature ozone-containing gas treatment and high-concentration ozone water treatment.

Further, it is said that the treatment using hydrogen water after ultrasonic activation can remove minute foreign matters. In the present invention, high purity sulfuric acid can be obtained by combining the ozone water treatment. For example, a series of processes from the peeling of the organic compound such as photoresist to the subsequent cleaning can be continuously and collectively performed without using a chemical solution such as. The combination of dry and wet processes that do not use high-energy substances such as plasma and chemicals such as sulfuric acid used in the conventional method makes it easy to operate because of the merit of avoiding contact with dangerous chemicals. To improve the usefulness. Further, it is industrially useful because it contributes to the reduction or reduction of the total cost by not using the chemical liquid.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of an oxidative decomposition treatment apparatus for an ozone gas treatment process of the present invention.

FIG. 2 is a schematic explanatory view showing an example of a wet cleaning treatment apparatus for the ozone water treatment process and the hydrogen water treatment process of the present invention.

[Explanation of symbols]

10 Oxidative decomposition treatment equipment 11 chambers 12 Semiconductor element forming substrate 13 Susceptor 14 heater 15 Ozone generator 16 filters 17 Gas diffuser 18 Exhaust line 19 Spin motor 20 Wet cleaning equipment 21 chamber cup 22 chuck 23 Ozone water preparation device 24 Hydrogen water preparation device 25 Ultrasonic Generator Dispenser 26 Acid component feeder 27 Alkaline component feeder 28 Ultrapure water supply mechanism

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H01L 21/304 B08B 3/08

Claims (5)

(57) [Claims] 1. A method for removing a resist existing on a substrate for forming a semiconductor element used for forming a semiconductor element, and a method for removing minute foreign matters containing an organic compound as a main component after the removal processing. (1) an ozone gas treatment step of directly or indirectly heating to room temperature or higher and treating with ozone-containing gas in a dry atmosphere, (2) treating ozone-containing gas with ozone water dissolved in ultrapure water Steps (1), (2) and (3) of the ozone water treatment step and the hydrogen water treatment step of (3) treating with hydrogen water activated by ultrasonic waves and dissolving hydrogen-containing gas in ultrapure water In the ozone water treatment step of (2) above, 20 to 60
A substrate surface treatment method for semiconductor element formation, which comprises using ozone water having an ozone concentration of ppm. 2. The ozone concentration of the ozone-containing gas in the ozone gas treatment step (1) is 4 to 8% by volume,
The substrate surface treatment method for forming a semiconductor element according to claim 1, wherein the heating temperature is 300 to 350 ° C. 3. The substrate surface treatment method for forming a semiconductor element according to claim 1, wherein hydrogen water having a hydrogen dissolution concentration of 1.2 to 2.0 ppm is used in the hydrogen water treatment step (3). 4. The ozone gas treatment substrate treated in the ozone gas treatment step of (1) is treated twice or more in the ozone water treatment step of (2), and then the (3).
The hydrogen water treatment process according to any one of claims 1 to 3.
A method for treating a surface of a substrate for forming a semiconductor element according to the item. Wherein said semiconductor element forming substrate, the semiconductor element formation substrate surface treatment method according to any one of claims 1 to 4, which is a diffusion process or the substrate after the etching step is completed the dopant.