JP2000208475A - Method and apparatus for chemical treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus for chemical treatment that can significantly reduce time and labor required to set the chemical agent treatment conditions and appropriately and precisely regulate the treating performance of a chemical. SOLUTION: Each chemical reaction between the chemical and a semiconductor substrate surface is analyzed from the relationship between the concentration of chemical species dissolved in the chemical agent and the semiconductor substrate surface. The proportion of each chemical reaction contributing to the entire chemical reactions is obtained from the reaction speed ratio. This proportion is used as a parameter to set or regulate the chemical treatment conditions so that preferable chemical reactions are caused for the semiconductor substrate or an object to be treated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical processing method and a chemical processing apparatus for etching or cleaning a semiconductor substrate surface or a material formed on a semiconductor substrate surface with a chemical in a manufacturing process of a semiconductor device or the like. .

[0002]

2. Description of the Related Art In etching and cleaning processes for semiconductor substrates, wet processing using chemicals is mainly used. In the cleaning process, several types of chemicals are properly used for a target processing object. A chemical solution containing ammonia and hydrogen peroxide (ammonia-hydrogen peroxide chemical solution: APM) is applied to particles attached to the surface of the semiconductor substrate, and a chemical solution containing hydrochloric acid and hydrogen peroxide is applied to the metal on the surface of the semiconductor substrate. (Hydrochloric acid-hydrogen peroxide solution: HPM) is used.

In recent years, in the processing of a semiconductor substrate using a chemical, strict control of the processing performance of the chemical has become an important issue with the high integration of semiconductor devices. For example, in the cleaning of a semiconductor substrate by APM, particles attached to the semiconductor substrate are removed by etching of the substrate surface and then removed by electrostatic repulsion with the substrate surface. For example, surface micro-roughness degrades the characteristics of the semiconductor device itself, causes problems related to the manufacturing process such as defective film formation, and reduces the yield of final products. As described above, in the treatment of a semiconductor substrate with a chemical, it is important to control the chemical reaction between the chemical and the surface of the semiconductor substrate.

Therefore, as a technique for controlling the cleaning performance of APM, Japanese Patent Application Laid-Open No. Hei 7-142435 discloses that the ammonia concentration is set to 3.
Cleaning methods for controlling APM in the range of 5 to 2.5% by weight are disclosed. Also, Japanese Patent Application Laid-Open No. 4-107922
In order to reduce the amount of etching of the substrate, Japanese Patent Application Laid-Open Publication No. 2002-214,055 discloses a method of controlling the APM such that the volume ratio of the hydrogen peroxide solution falls within a region calculated from the volume ratio of the ammonia water using a calculation formula. ing. Also, JP-A-10-18
In order to shorten the APM processing time, the APM is controlled so that the value of the equation obtained by substituting the ammonia concentration, the hydrogen peroxide concentration, the processing solution temperature, and the processing time becomes a predetermined value or more. A method for doing so is disclosed.

[0005]

However, according to the method disclosed in Japanese Patent Application Laid-Open No. Hei 7-142435, the APM
Temperature and hydrogen peroxide concentration are fixed, and the parameters that can be changed are limited to ammonia concentration.
There is a problem that versatility is not achieved as a method for managing the cleaning property of the varnish, and strict control cannot be performed. Also, Japanese Patent Application Laid-Open No. 4-1
In the method disclosed in Japanese Patent Application Laid-Open No. 07922, there is a problem that the temperature change of the volume ratio of the hydrogen peroxide solution is not taken into account, and the calculation formula can be established only at a specific temperature. Further, according to the method disclosed in Japanese Patent Application Laid-Open No. 10-183185, a plurality of parameters (ammonia concentration, hydrogen peroxide solution concentration, treatment liquid temperature, treatment time) are converted into one empirical formula based on limited experimental results. Since the empirical formula was incorporated, there was a problem that the empirical formula had no versatility, and the applicable range was limited to a concentration range that compensated for the experimental results.

In the APM cleaning, particles attached to a semiconductor substrate are removed by desorption of the substrate surface by etching and subsequent electrostatic repulsion with the substrate surface. For this reason, the cleaning properties of APM should be controlled by parameters based on the chemical reaction between the chemical solution and the semiconductor substrate surface. However, in the above-mentioned conventional technology, only indirect control based on the component concentration of the chemical solution is performed, and it is difficult to strictly control the cleaning property of the chemical solution by this method.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and in a chemical treatment of a semiconductor substrate, the time and labor required for setting treatment conditions of the chemical can be greatly reduced.
It is another object of the present invention to provide a chemical processing method capable of more accurately and strictly controlling the processing performance of a chemical, and a chemical processing apparatus for executing the method.

[0008]

The present invention provides the following chemical liquid processing methods (1) to (8) and chemical liquid processing apparatuses (9) to (13) in order to achieve the above object.

(1) In the chemical treatment of a semiconductor substrate, each chemical reaction between the chemical and the surface of the semiconductor substrate is analyzed from the relationship between the concentration of the chemical species dissolved in the chemical and the surface of the semiconductor substrate.
The ratio of each chemical reaction that contributes to the total chemical reaction is determined from the ratio of the reaction rates, and the ratio is used as a parameter to determine the chemical solution processing conditions during substrate processing so that the desired chemical reaction occurs on the semiconductor substrate or the object to be processed. A chemical processing method used for control or prediction of chemical processing conditions before substrate processing.

(2) The amount of a chemical substance generated or changed by the chemical reaction between the chemical species dissolved in the chemical solution and the surface of the semiconductor substrate is obtained using a relational expression of the chemical reaction containing the ratio as a parameter. Controlling the chemical processing conditions during the substrate processing or predicting the chemical processing conditions before the substrate processing so that the value falls within a predetermined area.

(3) Using a chemical reaction relational expression including the above ratio as a parameter, a concentration region of the chemical solution in which the chemical solution has a necessary and sufficient processing capability with respect to the semiconductor substrate is obtained, and the amount of the chemical solution used is minimized. And controlling the chemical processing conditions during the substrate processing or predicting the chemical processing conditions before the substrate processing.

(4) The chemical reaction desired for the semiconductor substrate or the object to be processed is a chemical reaction that does not damage the structure, composition or electrical properties of the material formed on the surface of the semiconductor substrate. ) Chemical treatment method.

(5) The purpose of the chemical treatment of the semiconductor substrate is to completely or partially etch the material formed on the substrate surface or to remove contaminants attached to the material formed on the substrate surface. The chemical solution treatment method according to any one of (1) to (4).

(6) The chemical solution contains an etching agent and an oxidizing agent, and the semiconductor substrate whose Si surface is entirely or partially exposed on the surface is the object to be treated, and the chemical solution treatment uses an etching reaction on the surface. The chemical liquid treatment method according to any one of (1) to (5), wherein

(7) The etching solution of the chemical solution is hydrofluoric acid, ammonia water or cathode water obtained by electrolysis, and the oxidizing agent is hydrogen peroxide solution, sulfuric acid, nitric acid, oxygen or ozone. (6) The chemical treatment method according to (6).

(8) The chemical is ammonia and hydrogen peroxide
And treating a silicon substrate with the chemical solution.
In, the chemical species having an etching action in the chemical solution is OH
^-, The oxidizing species is HO_Two ^-And silicon based
When the plate is etched, Si is OH ^-Directly dissolved by
Reaction path and Si is HO_Two ^-OH after being oxidized by^-By
It consists of two dissolution reaction paths,
On the other hand, Si is OH^-Of the reaction pathway directly dissolved by
The ratio given is less than 0.001, or for all reactions
Si is HO_Two ^-OH after being oxidized by^-Dissolution reaction by
During substrate processing so that the ratio of paths is 0.999 or more
Control of chemical processing conditions or chemical processing conditions before substrate processing
(7) Chemical solution treatment method, wherein
Law.

(9) A chemical processing apparatus for performing the chemical processing method according to any one of (1) to (8), wherein the measuring apparatus intermittently or continuously measures the component concentration and the temperature of the chemical, and the measuring apparatus A function of calculating the ratio of each chemical reaction to the total chemical reaction by using a relational expression previously obtained from the data obtained by the experiment, and a function of controlling the component concentration and the temperature of the chemical solution according to the determined ratio. And a control device having the following.

(10) It has a processing tank in which a semiconductor substrate is installed and in which chemical liquid processing is performed, an overflow tank installed so as to surround the processing tank, and a circulating pump connected to the overflow tank. The overflow tank is provided with a supply pipe for replenishing predetermined components contained in the chemical solution and a supply pipe for supplying ultrapure water, and for removing particle components on the downstream side of the circulation pump. (9) The semiconductor substrate chemical treatment apparatus according to (9), wherein a filtration device is provided, and the predetermined component is circulated and supplied to the treatment tank by the circulation pump.

(11) A support base having a function of sucking and holding the semiconductor substrate and rotating the semiconductor substrate at a predetermined number of rotations, and a chemical liquid nozzle for flowing a chemical liquid onto the surface of the substrate held by the support base, wherein the chemical liquid nozzle Has a mixing tank for a chemical solution, and the mixing tank is provided with a supply pipe for supplying a predetermined component contained in the chemical liquid and a supply pipe for supplying ultrapure water, A filtration device for removing particle components is provided on the downstream side of the liquid sending pump, which is connected to a pump, and the chemical solution prepared in the mixing tank is held by the liquid solution pump from the chemical solution nozzle on the support base. (9) being supplied to the surface of the rotating substrate.
Alternatively, the semiconductor substrate chemical treatment apparatus according to (10).

(12) The chemical solution supplied to the semiconductor substrate from the chemical solution nozzle is collected in the collection tank by the liquid sending pump from the drain of the processing tank after the substrate processing, and the concentration of the chemical component, the temperature of the chemical solution, and the dissolved component are monitored in the collection tank. Replenishment of a chemical component or temperature control by a heater is performed according to the chemical treatment methods (1) to (8), and a chemical that cannot be regenerated in the recovery tank is discharged from a drain of the recovery tank and re-prepared in the recovery tank. The chemical solution having a predetermined processing performance is supplied to the rotating substrate surface while being held on the support table from the chemical solution nozzle by a liquid feed pump communicating with the recovery tank (11). A) Chemical liquid processing apparatus for semiconductor substrates.

(13) The function of actually measuring the state of the structure or composition of the semiconductor device or the state of contamination of the semiconductor device is combined, and the actually measured data is used to control chemical processing conditions during substrate processing or to predict chemical processing conditions before substrate processing. (9) The semiconductor substrate chemical treatment apparatus according to any one of (9) to (12).

[0022]

Embodiments of the present invention will be described below. A description will be given of a method of controlling the processing performance of a chemical solution by a ratio (contribution ratio) of each chemical reaction between the chemical solution and the semiconductor substrate that contributes to all chemical reactions in the processing of the semiconductor substrate with the chemical solution.

The chemical reaction on the surface of the semiconductor substrate by the chemical proceeds along reaction paths 1, 2, 3,..., X composed of a plurality of chemical reactions. The contribution ratio (α ₁ , α ₂ , α ₃ ,..., Α _X ) of each reaction path to the total chemical reaction is determined by the relative ratio of the reaction rates (v ₁ , v ₂ ,..., V _X ) of each chemical reaction. You. For example, as shown in Chemical formula 2, the contribution rate of reaction path ₁ is represented by α ₁ , and the contribution rate of reaction path 2 is represented by α ₂ . Since the reaction rate of all the chemical reactions is the sum of the reaction rates of the respective reaction paths, the reaction rate v _Total of the semiconductor substrate by the chemical solution is expressed as shown in Formula 3 using the reaction rate of each chemical reaction. The reaction rate of each reaction path is obtained from the reaction rate constant specific to the reaction and the concentration (activity) of the dissolved chemical species involved in the reaction in the chemical solution (Chem. 4). The concentration (activity) of each dissolved chemical species in the drug solution can be calculated using an analysis method disclosed in Japanese Patent Application Laid-Open No. 9-203405. Using a computer based on the relationships of Chemical Formulas 1 to 4, the contribution rate of each reaction path can be obtained from the component concentration and temperature of the chemical solution. Conversely, it is also possible to set the contribution ratio of each reaction path in advance, and obtain the component concentration and the temperature of the chemical solution so as to obtain the contribution ratio.

[0024]

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In the treatment of a semiconductor substrate with a chemical solution, it is ideal that the substrate itself or the material formed on the substrate surface is efficiently treated in a short time without damaging the semiconductor substrate as much as possible. Among the reaction paths, there are reaction paths that meet the above conditions and reaction paths that do not. Optimal processing can be performed by selecting a processing condition that maximizes the contribution rate of a reaction path that meets the above conditions and minimizes the contribution rate of a reaction path that does not conform to the above conditions.

(First Embodiment) FIG. 1 is a flowchart showing an example of a method for setting chemical solution processing conditions before substrate processing according to a first embodiment of the present invention. In this example, the chemical solution component concentration, the chemical solution temperature, and the chemical solution processing time, which are the chemical solution processing conditions, are determined from the contribution ratio of each chemical reaction and the allowable range of the substrate processing amount.

In the chemical liquid control method of the present invention, the contribution of each reaction path to all chemical reactions is used as an index in order to control the cleaning properties of the chemical liquid. Since the chemical reaction between the chemical and the surface of the semiconductor substrate is directly controlled, the precise setting of the chemical processing conditions and the strict control of the cleaning properties of the chemical are compared to the conventional indirect control method for managing the chemical concentration. It becomes possible. Further, the time and labor required for initial setting of processing conditions required every time the apparatus is started or the process is changed are greatly reduced.

An allowable range of the contribution rate of the chemical reaction and the substrate processing amount is set (S100). The concentration of the chemical component and the temperature of the chemical solution are set as initial values (S101), and the concentration of the dissolved chemical species is calculated from the component concentration and the temperature (S102). The reaction rate of each chemical reaction is calculated from the chemical species concentration and the temperature (S103). The contribution rate of each chemical reaction is determined from the reaction rate (S104). In the evaluation of the contribution rate (S105), when the contribution rate is out of the allowable range, the component concentration of the chemical solution and the temperature of the chemical solution are corrected (S106), and the chemical species concentration is calculated again from the chemical species concentration calculation (S102). The evaluation up to the contribution ratio (S105) is performed. In the evaluation of the contribution rate (S105), if the contribution rate is within the allowable range, a chemical solution processing time is set (S107), and a substrate processing amount obtained from the processing time and the reaction speed is calculated (S10).
8). In the evaluation of the processing amount (S109), if the processing amount is out of the allowable range, the chemical processing time is evaluated (S110). If the processing time can be changed within the allowable range, the chemical processing time is set ( From S107) to the evaluation of the substrate throughput (S109) are performed. If the processing time cannot be changed within the allowable range, the component concentration of the chemical solution and the temperature of the chemical solution are corrected (S106), and the calculation is performed again from the calculation of the chemical species concentration (S102). Evaluation of the processing amount (S109)
In step (1), when the processing amount is within the allowable range, the component concentration of the obtained chemical, the temperature of the chemical, and the chemical processing time are determined as the chemical processing conditions (S111).

(Second Embodiment) FIG. 2 is a flowchart showing an example of a method for controlling chemical solution processing conditions during substrate processing according to a second embodiment of the present invention. In this example, the concentration of the chemical species dissolved in the chemical solution and the temperature of the chemical solution are monitored, and based on the calculated reaction rate of each chemical reaction, the chemical solution is adjusted so that the contribution rate of each chemical reaction and the substrate processing amount fall within an allowable range. Controls component concentration, chemical temperature, and chemical treatment time.

The substrate processing amount indicates the substrate surface itself or a material (such as a thin film) formed on the substrate surface. For example, when processing a thin film formed on a semiconductor substrate surface with a chemical solution, the amount of change in the film thickness of the thin film can be accurately grasped and processed. It is possible to prevent performance deterioration and product yield reduction. In addition, the data on the amount of change in the thin film can be positively used, and the variation in the film thickness during film formation can be corrected by the processing time of the chemical solution.

The allowable range of the contribution rate of the chemical reaction and the substrate throughput is set (S200). The component concentration of the chemical solution and the temperature of the chemical solution are monitored (S201), and the concentration of the dissolved chemical species is calculated from the component concentration and the temperature (S202). The reaction rate of each chemical reaction is calculated from the chemical species concentration and the temperature (S20).
3). The contribution rate of each chemical reaction to the total reaction is determined from the reaction rate (S204). Evaluation of the contribution rate (S20
In 5), when the contribution ratio is out of the allowable range, the component concentration of the chemical and the temperature of the chemical are corrected (S20).
7) From the monitoring of the chemical component concentration and the chemical temperature (S201) to the evaluation of the contribution rate of the chemical reaction (S205). In the evaluation of the contribution rate (S205), when the contribution rate is within the allowable range, a chemical solution processing time is set (S20).
6), a substrate processing amount obtained from the processing time and the reaction speed is calculated (S208). Evaluation of the processing amount (S20
In 9), when the processing amount is out of the allowable range,
The chemical processing time is evaluated (S210). If the processing time can be changed within an allowable range, the processing from setting of the chemical processing time (S206) to evaluation of the substrate processing amount (S209) is performed. If the processing time cannot be changed within an allowable range,
The concentration of the chemical solution and the temperature of the chemical solution are corrected (S207), and the monitoring is again performed from the concentration of the chemical solution component and the temperature of the chemical solution (S201). In the evaluation of the processing amount (S209), when the processing amount is within the allowable range, the processing of the semiconductor substrate with the chemical and the control of the processing conditions of the chemical (S201 to S209)
At the same time. The processing conditions of the chemical solution are controlled so that the processing performance of the chemical solution is always kept constant irrespective of whether the semiconductor substrate is being processed or on standby.

FIG. 3 is a configuration diagram of an embodiment of a semiconductor substrate chemical solution processing apparatus incorporating the chemical solution processing condition control method of the present invention described in FIG. The chemical processing apparatus has a reservoir 15 for the chemical component A, a reservoir 16 for the chemical component B, and a reservoir 17 for ultrapure water, and the chemical components A, B from the reservoirs 15, 16, and 17. , Ultrapure water, liquid pump 1
A necessary amount is supplied to the processing tank 1 via the overflow tank 2 by driving of 8, 19, and 20, and the semiconductor substrate 4 is processed in the processing tank 1. The chemical solution 3 is circulated so as to pass through the filter 14 by the driving of the circulation pump 13 to prevent particles from being accumulated in the chemical solution 3 in the processing tank 1.

The contribution ratio of the chemical reaction and the allowable range of the substrate processing amount are set (S200). The concentration of the chemical component A and the concentration of the chemical component B of the chemical 3 are controlled by the concentration controller 11, and the temperature of the chemical is controlled by the temperature controller 7. The water level (chemical liquid amount) of the chemical liquid 3 is monitored by the water level controller 10 (S201).
Based on the chemical component concentration and the chemical temperature obtained by each controller, the analyzer 12 calculates the concentration of the dissolved chemical species (S202), and calculates the reaction speed of each chemical reaction (S20).
3), the contribution rate of the chemical reaction is calculated (S204). The analysis unit 12 evaluates the contribution ratio (S205). If the contribution ratio is out of the allowable range, an instruction is sent from the analysis unit 12, and the liquid component A and the liquid component B by the liquid feed pumps 18, 19, and 20 are sent. Then, replenishment of ultrapure water or temperature adjustment by the heater 8 is performed (S207). The analysis device 12 evaluates the contribution ratio (S205). If the contribution ratio is within the allowable range, a chemical solution processing time is set (S206), and a substrate processing amount obtained from the processing time and the reaction speed is calculated. (S208). The analysis unit 12 evaluates the processing amount (S209), and when the processing amount is out of the allowable range,
The chemical processing time is evaluated (S210), and if the processing time can be changed within an allowable range, the chemical processing time is set (S210).
206) to the evaluation of the substrate processing amount (S209). The processing amount is evaluated by the analyzer 12 (S20).
9) If the processing time cannot be changed within an allowable range,
The concentration of the chemical solution and the temperature of the chemical solution are corrected (S207), and the monitoring is again performed from the concentration of the chemical solution component and the temperature of the chemical solution (S201). The processing amount is evaluated by the analyzer 12 (S20).
9) If the processing amount is within the allowable range, processing of the semiconductor substrate with the chemical and control of the processing conditions of the chemical (S201 to S201)
209) at the same time. Regardless of whether the semiconductor substrate is being processed or is on standby, the processing performance of the chemical solution is always kept constant.

(Third Embodiment) FIG. 4 is a flowchart showing an example of a method for setting chemical solution processing conditions before substrate processing according to a third embodiment of the present invention. In this example, the reaction speed of each chemical reaction is calculated from the concentration of the chemical species dissolved in the chemical solution and the temperature of the chemical solution, and the concentration region of the chemical component is determined so that the contribution rate of each chemical reaction falls within a predetermined range. Further, in the concentration region, the component concentration of the chemical solution, the chemical solution temperature, and the chemical solution processing time are determined so that the variation range of the chemical solution component concentration falls within a predetermined range and the amount of the chemical solution used is minimized.

In the chemical processing method of the present invention, a plurality of chemical processing conditions having the same processing capability can be selected.
In the treatment of the semiconductor substrate with the chemical solution, by selecting the minimum necessary chemical solution component concentration, the amount of the chemical solution used can be significantly reduced.

The variation range of the concentration of the chemical component and the allowable range of the amount of the chemical solution to be processed are set (S300). As the initial values, the component concentration of the chemical solution currently used or to be used and the temperature of the chemical solution are set (S301), and the dissolved chemical species concentration is calculated from the component concentration and the temperature (S302). The reaction rate of each chemical reaction is calculated from the chemical species concentration and the temperature (S303). The contribution rate of each chemical reaction to the total reaction is determined from the reaction rate (S304). In the evaluation of the contribution rate (S305), when the contribution rate is out of the allowable range, the component concentration of the chemical solution and the temperature of the chemical solution are corrected (S306), and the concentration of the dissolved chemical species is calculated (S302). The evaluation up to the contribution rate (S305) is performed. Evaluation of the contribution rate (S3
In step 05), when the contribution rate is within the allowable range, the concentration area of the chemical component in which the contribution rate is the same as the contribution rate and the substrate processing amount is within the allowable range is calculated (S30).
7). A reduction rate of the chemical component concentration is set (S308), and the chemical component concentration is calculated (S309). In the evaluation of the concentration of the chemical component (S310), if the chemical component falls outside the concentration range, the reduction rate of the component concentration is corrected (S311), and the calculation of the component concentration is again performed from the calculation of the component concentration (S309). Evaluation (S310) is performed. In the evaluation of the chemical component concentration (S310), when the chemical component is within the concentration range, the fluctuation range of the chemical component concentration is calculated (S312). In the evaluation of the fluctuation range (S313), when the fluctuation range is within the allowable range, the set low chemical solution component concentration is used, and from the setting of the reduction rate (S308) to the evaluation of the fluctuation range of the chemical solution component concentration (S313). Do. The above operation is repeated to evaluate the fluctuation range of the chemical component concentration (S31
In 3), if the fluctuation range is out of the allowable range,
The chemical component concentration, the chemical temperature, and the chemical processing time evaluated last time are determined as chemical processing conditions (S314).

FIG. 3 shows a method for controlling chemical treatment conditions according to the present invention.
In addition to the conventional batch-type chemical processing equipment described in (1), more effective chemicals will be used in the single-wafer-type chemical processing equipment that is expected to be used in response to the increase in diameter of semiconductor substrates in the future. Operation can be realized. Normally, a single-wafer type chemical processing apparatus is constituted by one processing tank, and a chemical obtained by processing a semiconductor substrate is discarded only once. The chemical is disposable. Disposable chemicals increase the amount of chemicals used and cause a significant increase in manufacturing costs, including the cost of treating waste liquids. When disposing of chemicals, the chemicals should be set to the lowest concentration that allows normal processing in order to reduce the amount of chemicals used. The conventional control method cannot control such a chemical concentration.

However, by using the method of the present invention, it is possible to select a plurality of combinations of the chemical component concentrations having the same contribution rate (the same cleaning performance of the chemical solution). When the semiconductor substrate is processed only once, since the fluctuation of the chemical solution condition during the substrate processing is slight, the concentration of each chemical solution component is the lowest among the combinations of the chemical solution component concentrations having the same contribution rate when processing the semiconductor substrate. All you have to do is select a combination. This makes it possible to reduce the amount of chemical used in a single-wafer type chemical processing apparatus.

FIG. 5 is a block diagram of an embodiment of a semiconductor substrate chemical solution processing apparatus incorporating the method for setting chemical solution processing conditions of the present invention shown in FIG. The chemical processing apparatus of the present invention includes a storage tank 15 for a chemical component A and a storage tank 1 for a chemical component B.
6 and a storage tank 17 of ultrapure water.
The chemical solution components A, B, and ultrapure water from 6, 17 are supplied to the preliminary tank 25 by driving the liquid feed pumps 18, 19, 20, mixed by the stirrer 27, temperature-controlled by the heater 26, and then sent. When the liquid pump 30 is driven, the liquid is supplied from the chemical liquid nozzle 24 to the support base 21 through the filter 31 by suction and is supplied to the semiconductor substrate 4 rotated by the rotator 22 for processing. The chemical that has processed the semiconductor substrate 4 is discharged from the drain. If the number of chemicals or ultrapure water to be treated in the chemical preparation section 32 is prepared, a plurality of chemical treatments or ultrapure water treatment can be performed in the treatment tank 23. At the time of preparing the chemical solution in the preliminary tank 25, FIG.
The setting of the chemical treatment conditions of the present invention described in the above is performed by the analyzer 1.
2 is performed.

Further, in the chemical liquid cleaning apparatus shown in FIG. 5, if the method for controlling the chemical liquid processing conditions shown in FIG. 2 is used, it is possible to recycle and reuse the disposed chemical liquid.

FIG. 6 is a block diagram of one embodiment of the semiconductor substrate chemical solution treatment apparatus of the present invention. The chemical processing apparatus of the present invention includes a storage tank 15 for a chemical component A and a storage tank 1 for a chemical component B.
6 and a storage tank 17 of ultrapure water.
The chemical solution components A, B, and ultrapure water from 6, 17 are supplied to the preliminary tank 25 by driving the liquid feed pumps 18, 19, 20, mixed by the stirrer 27, temperature-controlled by the heater 26, and then sent. When the liquid pump 30 is driven, the liquid is supplied from the chemical liquid nozzle 24 to the support base 21 through the filter 31 by suction and is supplied to the semiconductor substrate 4 rotated by the rotator 22 for processing. The chemical that has processed the semiconductor substrate 4 is sent to the collection tank 33 by driving the liquid sending pump 38. The chemical in the recovery tank 33 is monitored by the concentration controller 11 and the temperature controller 37, and is analyzed by the analyzer 1.
If the contribution rate calculated in step 2 is within the allowable range, the chemical solution is passed through the filter 40 and returned to the processing tank 23, and the next processing of the semiconductor substrate 4 is performed. When the contribution rate calculated by the analyzer 12 is out of the allowable range, the minimum necessary amount of chemical replenishment from the storage tanks 15, 16, and 17 and the temperature control by the heater 34 are performed so that the contribution rate is within the allowable range. After that, the chemical solution is passed through the filter and returned to the processing tank 23, and the next processing of the semiconductor substrate 4 is performed. The above operation is repeated to advance the processing of the semiconductor substrate with the minimum amount of chemical. For the preparation of the chemical in the preliminary tank 25, the method for setting the chemical processing conditions described in FIG. 4 is applied, and for the preparation of the chemical in the recovery tank 33, the control method for the chemical processing conditions described in FIG. .

Further, in the chemical cleaning device shown in FIG.
By combining the function of actually measuring the state of the structure and composition of the semiconductor device or the state of contamination of the semiconductor device, it is possible to perform a chemical treatment with higher precision. For example, data to be measured include the thickness of a thin film formed on a semiconductor substrate, the concentration of constituent elements, and the form and concentration of impurities remaining on the surface. In the measuring device, a commercially available measuring device can be used according to the purpose of the measurement.

FIG. 7 is a block diagram of an embodiment of a semiconductor substrate chemical solution treatment apparatus according to the present invention. The chemical processing apparatus of the present invention includes a storage tank 15 for a chemical component A and a storage tank 1 for a chemical component B.
6 and a storage tank 17 of ultrapure water.
The chemical solution components A, B, and ultrapure water from 6, 17 are supplied to the preliminary tank 25 by driving the liquid feed pumps 18, 19, 20, mixed by the stirrer 27, temperature-controlled by the heater 26, and then sent. When the liquid pump 30 is driven, the liquid is supplied from the chemical liquid nozzle 24 to the support base 21 through the filter 31 by suction and is supplied to the semiconductor substrate 4 rotated by the rotator 22 for processing. The chemical that has processed the semiconductor substrate is discharged from the drain. It is to be noted that the used chemical liquid can be reused if the apparatus is configured to have a collecting function as shown in FIG. The semiconductor substrate 4 is subjected to a predetermined measurement by the measuring device 41 and the measuring device 36
Based on the actual measurement data obtained in step (1), the method for setting the chemical processing conditions described in FIG. 4 is performed. A plurality of semiconductor substrates 4 are always stored in the clean case 42 and the processing tank 2
While the processing of the semiconductor substrate 4 is being performed in 3, the semiconductor substrate 4 is transported from the clean case 42 to the measuring device 41,
By performing the predetermined measurement, a decrease in throughput can be suppressed.

[0044]

(Embodiment 1) A method of controlling the cleaning property of APM will be described by taking as an example a cleaning process of a silicon substrate surface by APM. Dissolved species in APM, NH ₃ , NH ₄ ⁺ , H ₂ O
^{_{2, HO 2 -, H +}} , OH - each concentration (activity) of the Patent 9
It can be calculated using the analysis method disclosed in -203405.

It has been confirmed that the etching reaction of the silicon substrate surface by APM proceeds in two reaction paths from the relationship between the concentration of the dissolved species in APM and the measured value of the etching rate (Chem. 5). One Si is OH ₂ ^- is oxidized (reaction rate v _1a) by further OH ^- a reaction pathway is dissolved (reaction rate v _1b) at 1, and one, Si is O
H ^- is a reaction pathway 2, which is directly dissolved (reaction rate v ₂₎ by. The contribution rate of the reaction path 1 to the total etching reaction is represented by α ₁ , and the contribution rate of the reaction path 2 to the total etching reaction is represented by α ₂ (Formula 6). The etching rate _Er of the substrate by APM is expressed using the reaction rate of each elementary reaction (Chem. 7).

[0046]

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Reaction path 1 is a reaction for forming an oxide film having high hydrophilicity and etching the oxide film. Therefore, the permeability of the chemical solution to the interface between the particles and the substrate is increased, and the removability of the particles is improved. . On the other hand, reaction path 2 is an anisotropic etching reaction that does not form an oxide film, and increases micro-roughness (irregularities) on the substrate surface. In APM cleaning of a silicon substrate, particles on the substrate surface must be removed by etching. This requires a certain amount of etching, but the etching of reaction path 2 causes a sharp increase in etching rate, an increase in micro roughness, and a decrease in particle removal properties.
In order to perform normal APM cleaning, it is necessary to treat the silicon substrate under the condition that the contribution of the reaction path 1 is large and the contribution of the reaction path 2 is as small as possible.

In the case where APM cleaning of the silicon substrate was performed using the chemical processing apparatus shown in FIG. 3 and the contribution rate α ₁ of the reaction path 1 to the entire etching reaction as an index,
The control result of the PM cleanability will be described.

[0049] The relationship between the etching rate of the silicon substrate and the contribution ratio alpha ₁ by the APM in FIG 8 shows the relationship between the micro-roughness of the silicon substrate surface by APM (irregularities) and contribution ratio alpha ₁ in FIG. 9 (Temperature: 80 ° C., OH ^- concentration: 2 ×
10 ⁻³ mol / l). FIG. 10 shows the relationship between the removal rate of particles (approximately 5000 particles / substrate) adhered to the silicon substrate by APM and the contribution rate α ₁ (temperature: 80
° C, etching depth: 2 nm). In the reduction of the contribution rate α _1,
The etching rate and micro-roughness increased sharply, and the particle removal rate decreased. When cleaning a silicon substrate with APM, in order to suppress damage to the silicon substrate and obtain a high particle removal rate, the contribution rate α _{1 of the} reaction path 1 is required.
The washing condition may be controlled so that the α ₁ value becomes 0.999 or more using the index as an index. As alpha ₁ value is equal to or greater than 0.999, it was controlled chemical component concentrations and chemical temperature and chemical treatment time, the deterioration of the shape or the electrical characteristic of the semiconductor device treated with chemical was not seen, the yield is also greatly improved I was able to confirm.

(Example 2) Taking the cleaning treatment of the silicon substrate surface by APM as an example, under the same chemical treatment conditions as shown in Embodiment 1, the chemical solution temperature and the chemical solution treatment time (the amount of the semiconductor substrate surface treatment) ) Will be described below. As shown in Example 1, the contribution rate α ₁ of the reaction route 1 in which normal chemical treatment can be performed is 0.999.
It was above. When the temperature of the chemical solution was 80 ° C. and the time of the chemical solution treatment was 10 minutes (the processing amount of the semiconductor substrate surface: 4.5 to 5.0 nm), the contribution α ₁ of the reaction path 1 was calculated to be 0.999 or more. FIG. 11 shows the concentration ranges of ammonia and hydrogen peroxide in APM. The black area is the available density area. Note that the available concentration range changes depending on the temperature of the chemical or the processing time of the chemical. Actually, when the silicon substrate is subjected to APM cleaning in the chemical solution processing apparatus shown in FIG. 4, the combination of the ammonia concentration and the hydrogen peroxide concentration is
What is necessary is just to control so that it may enter into the black area | region of FIG. If the combination is black region of ammonia concentration and hydrogen peroxide concentration, the contribution rate alpha ₁ becomes more than 0.999, any combination even comparable cleaning performance is obtained. In the continuous use of APM, the concentration of ammonia, the concentration of hydrogen peroxide, and the temperature were constantly monitored, and it was confirmed that the contribution rate α ₁ calculated by the analyzer from the above parameters was 0.999 or more. _{When 1} is less than 0.999, if the replenishment of the chemical solution is performed so that the combination of the ammonia concentration and the hydrogen peroxide concentration enters the black region in FIG.
PM processing can be maintained.

(Example 3) Table of silicon substrate by APM
Taking the surface cleaning process as an example, the same
Chemical solution using the chemical solution treatment method of the present invention under chemical solution treatment conditions
The reduction in the amount used will be described. Normal as shown in Example 2
Α of reaction route 1 that can perform various chemical treatments ₁Is 0.99
9 or more. When performing APM processing on a silicon substrate,
Figure 11 shows the combination of the concentration of ammonia and the concentration of hydrogen peroxide.
Any combination within the black area shown
APM treatment, etc. can be performed.
The combination of ammonia concentration and hydrogen peroxide concentration.
If they are selected so that their concentrations are low, the low concentration of APM
Accuracy can be realized. For example, RCA cleaning (RCA Revie
w, W. Kern et al., 1970)
APM (NH_Three: H_TwoO_Two: H_TwoO = 1: 1: 5
80 ° C.) in FIG. 11, the ammonia concentration and
Both hydrogen peroxide concentrations can be reduced to 1/20
Yes (NH_ThreeConcentration: 29% by weight, H_TwoO_TwoConcentration: 30 layers
amount%).

[0052]

As described above, according to the method for treating a chemical solution of the present invention, each chemical reaction contributes to the entire chemical reaction from the relationship between the concentration of the chemical species dissolved in the chemical solution and the surface of the semiconductor substrate. Since the ratio is analyzed and the ratio is used as an index to control chemical solution processing or to set processing conditions, the time and effort required for initial setting of processing conditions are lower than conventional indirect control based on the component concentration of chemical solutions. Can be greatly reduced, and
The processing performance of the chemical solution can be more strictly controlled. Further, according to the method for treating a chemical solution, it is possible to set optimal cleaning conditions, particularly in a low-concentration region of the chemical solution.
Cost reduction can be realized by reducing the amount of chemical solution used.

[Brief description of the drawings]

FIG. 1 is a flowchart of an example of a method for treating a semiconductor substrate with a chemical solution according to the present invention.

FIG. 2 is a flowchart of an example of a method for treating a semiconductor substrate with a chemical solution according to the present invention.

FIG. 3 is a configuration diagram of one embodiment of a semiconductor substrate chemical solution treatment apparatus of the present invention.

FIG. 4 is a flowchart of an example of a method for treating a semiconductor substrate with a chemical solution according to the present invention.

FIG. 5 is a configuration diagram of one embodiment of a semiconductor substrate chemical solution treatment apparatus of the present invention.

FIG. 6 is a configuration diagram of one embodiment of a semiconductor substrate chemical solution treatment apparatus of the present invention.

FIG. 7 is a configuration diagram of one embodiment of a semiconductor substrate chemical solution treatment apparatus of the present invention.

FIG. 8 is a diagram showing an example of the relationship between the contribution rate α1 of the reaction path ₁ and the etching rate in APM processing of a silicon substrate using the chemical processing apparatus of the present invention.

FIG. 9 is a diagram showing an example of the relationship between the contribution ratio α ₁ of the reaction path ₁ and the surface micro-roughness of a substrate in APM processing of a silicon substrate using the chemical solution processing apparatus of the present invention.

FIG. 10 is a diagram showing an example of the relationship between the contribution rate α1 of the reaction path ₁ and the removal rate of particles attached to the substrate surface in APM processing of a silicon substrate using the chemical processing apparatus of the present invention.

FIG. 11 is a graph showing that the contribution rate α ₁ of the reaction path ₁ is 0.
It is a figure which shows the concentration area | region of ammonia and hydrogen peroxide which are 999 or more.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Processing tank 2 Overflow tank 3 Chemical solution 4 Semiconductor substrate 5 Carrier 6, 28, 36 Temperature sensor 7, 29, 37 Temperature controller 8, 26, 34 Heater 9 Water level sensor 10 Water level controller 11 Concentration controller 12 Analysis device 13 Circulation pump 14, 31, 40 Filter 15, 16, 17 Storage tank 18, 19, 20, 30, 38, 39 Liquid feed pump 25 Mixing tank 27, 35 Stirrer 32 Chemical liquid preparation unit 33 Recovery tank 41 Measuring device 42 Clean case

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 647 H01L 21/304 648F 648 21/30 569Z 21/306 R (72) Inventor Shio Hase Tokyo 5-7-1 Shiba, Tokyo Minato-ku F-term in NEC Corporation (reference) 2H096 AA25 GA30 HA19 HA20 5F043 AA02 BB02 BB30 DD13 DD30 EE07 EE08 EE12 EE22 EE23 EE24 EE25 EE31 EE33 EE40 GG10 5F046 LA01 LA14

Claims (13)

[Claims] In a chemical treatment of a semiconductor substrate, each chemical reaction between the chemical and the surface of the semiconductor substrate is analyzed from a relationship between the concentration of a chemical species dissolved in the chemical and the surface of the semiconductor substrate, and each chemical reaction is analyzed by a total chemical reaction. The ratio contributing to the reaction is determined from the ratio of the reaction rates, and the ratio is used as a parameter to control chemical solution processing conditions during substrate processing or to control chemical solution processing before substrate processing so that a desired chemical reaction occurs on the semiconductor substrate or the object to be processed. A chemical treatment method used for predicting chemical treatment conditions. 2. In the chemical treatment of a semiconductor substrate, each chemical reaction between the chemical and the surface of the semiconductor substrate is analyzed based on the relationship between the concentration of the chemical species dissolved in the chemical and the surface of the semiconductor substrate, and each of the chemical reactions is determined by the total chemical reaction. A chemical substance generated or changed by a chemical reaction between a chemical species dissolved in a chemical solution and a semiconductor substrate surface, using a relational expression of a chemical reaction containing the ratio as a parameter, while obtaining a ratio contributing to the reaction from a reaction speed ratio. A chemical solution processing method comprising: determining an amount and controlling a chemical solution processing condition during substrate processing or predicting a chemical solution processing condition before substrate processing so that the chemical substance amount falls within a predetermined region. 3. In the chemical treatment of a semiconductor substrate, each chemical reaction between the chemical and the surface of the semiconductor substrate is analyzed based on the relationship between the concentration of the chemical species dissolved in the chemical and the surface of the semiconductor substrate. The ratio contributing to the reaction is determined from the ratio of the reaction rates, and the concentration range of the chemical having the necessary and sufficient processing capability for the semiconductor substrate is determined by using the chemical reaction relational expression including the ratio as a parameter. A chemical solution processing method for controlling chemical solution processing conditions during substrate processing or predicting chemical solution processing conditions before substrate processing so as to minimize the amount of used. 4. The chemical reaction desired for the semiconductor substrate or the object to be processed is a chemical reaction that does not damage the structure, composition or electrical characteristics of the material formed on the surface of the semiconductor substrate. The method for treating a chemical solution according to item 1. 5. The object of the chemical treatment of a semiconductor substrate is to completely or partially etch a material formed on the substrate surface or to remove contaminants attached to the material formed on the substrate surface. The chemical solution treatment method according to any one of claims 1 to 4, wherein 6. A semiconductor substrate in which a chemical solution contains an etching agent and an oxidizing agent, and a semiconductor substrate having a Si surface entirely or partially exposed on a surface is an object to be processed, and the chemical solution process is a process utilizing an etching reaction on the surface. The chemical solution treatment method according to claim 1, wherein: 7. The etching solution of the chemical solution is hydrofluoric acid,
7. The chemical solution treatment method according to claim 6, wherein the aqueous solution is ammonia water or cathode water obtained by electrolysis, and the oxidizing agent is hydrogen peroxide solution, sulfuric acid, nitric acid, oxygen or ozone. 8. The chemical solution is an aqueous solution containing ammonia and hydrogen peroxide, and in the treatment of the silicon substrate with the chemical solution, chemical species having an etching action in the chemical solution are OH ⁻ ,
Species with oxidation action is HO ₂ ^- and is, etching of the silicon substrate, Si is OH ^- by a reaction pathway directly dissolved, Si is HO ₂ ^- reaction pathway that dissolves by ^- OH after being oxidized in consists of two reaction routes, Si relative to the total reaction OH ^- by contributing ratio less than 0.001 of the reaction pathway is dissolved directly, or Si relative to the total reaction
Control of chemical processing conditions during substrate processing or prediction of chemical processing conditions before substrate processing so that the ratio of the reaction path that is oxidized by HO ₂ ⁻ and then dissolved by OH ⁻ is 0.999 or more. The chemical solution treatment method according to claim 7, wherein: 9. A chemical solution processing apparatus for performing the chemical solution processing method according to claim 1, wherein the measuring apparatus measures the component concentration and the temperature of the chemical solution intermittently or continuously. The function of calculating the ratio of each chemical reaction to the total chemical reaction using a relational expression obtained experimentally in advance from the data obtained by the measurement device, and the component concentration and temperature of the chemical solution according to the determined ratio. And a control device having a control function. 10. A semiconductor device, comprising: a processing tank in which a semiconductor substrate is installed and a chemical solution processing is performed; an overflow tank installed to surround a periphery of the processing tank; and a circulation pump communicating with the overflow tank. In the overflow tank,
A supply pipe for replenishing a predetermined component contained in the chemical solution and a supply pipe for supplying ultrapure water are provided, and a filtration device for removing particle components is provided downstream of the circulation pump, 10. The semiconductor substrate chemical treatment apparatus according to claim 9, wherein the predetermined component is circulated and supplied to the processing tank by a circulation pump. 11. A supporting base having a function of sucking and holding a semiconductor substrate and rotating the semiconductor substrate at a predetermined number of revolutions, and a chemical liquid nozzle for flowing a chemical liquid onto a surface of the substrate held by the supporting base,
The chemical liquid nozzle includes a chemical liquid mixing tank, and the mixing tank is provided with a supply pipe for supplying a predetermined component contained in the chemical liquid and a supply pipe for supplying ultrapure water. Is connected to a liquid sending pump, a filtration device for removing particle components is provided downstream of the liquid sending pump,
The chemical solution prepared in the mixing tank is supplied from a chemical solution nozzle to a rotating substrate surface while being held on the support table by a solution sending pump. 11. Semiconductor substrate chemical treatment equipment. 12. A chemical solution supplied to a semiconductor substrate from a chemical solution nozzle is collected in a recovery tank by a liquid sending pump from a drain of the processing tank after substrate processing, and a concentration of a chemical component, a temperature of the chemical solution, and a dissolved component are monitored in the recovery tank. , Any one of claims 1 to 8
The replenishment of the chemical component or the temperature adjustment by the heater is performed by the chemical treatment method according to the item, and the chemical that cannot be regenerated in the recovery tank is discharged from the drain of the recovery tank, re-prepared in the recovery tank, and has a predetermined processing performance. 12. The semiconductor substrate according to claim 11, wherein the chemical having the chemical is supplied to a rotating substrate surface while being held on a support base from a chemical nozzle by a liquid sending pump communicating with the recovery tank. Chemical processing equipment. 13. A combination of a function of actually measuring the state of the structure or composition of a semiconductor device or the state of contamination of a semiconductor device, and using measured data to control chemical processing conditions during substrate processing or to predict chemical processing conditions before substrate processing. The chemical liquid processing apparatus for a semiconductor substrate according to claim 9, wherein: