JP2008306089A - Immersion type cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily control the amount of etching of a film to be etched by controlling the chemical concentration by accurately finding a mixing ratio of cleaning chemical to refill a required amount of chemical. <P>SOLUTION: In the replacement of chemicals, the amounts of supply of chemicals 21, 22, 23 to be supplied to a chemical tank 1 are measured by chemical flow meters 31, 32, 33, respectively. With the measured flow rate, a supply time is calculated in an operation part 7 and the total input of each chemical is calculated from the integral of the supply flow rate and the supply time. The mixing ratio is found from the total input of each chemical and the chemical concentration is calculated. At this point, if the calculated concentration is different from the set concentration, an amount of refill of each chemical is calculated in the operation part 7 so that a desired chemical concentration is obtained and the amount of refill is adjusted by varying the supply time. Only the chemical to be refilled is supplied to the chemical tank 1 by opening a mixing valve 4 for the supply time calculated in the operation part 7 and thus the chemical concentration is adjusted. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an immersion type cleaning apparatus that can control the etching amount of a semiconductor substrate by chemical processing to a desired etching amount by controlling the concentration of the chemical solution used in circulation in the immersion type cleaning apparatus.

  With the progress of miniaturization of semiconductor devices in recent years, the etching margin of a semiconductor substrate has decreased, and processing is performed so as to reduce the etching amount of the substrate as much as possible in the cleaning process. The etching amount can be controlled by the concentration of the chemical solution. Recently, the concentration of the cleaning chemical solution has been reduced, and the etching amount has been reduced. At this time, the concentration of the processing chemical solution must be accurately controlled, and variation in the etching amount causes a large variation in the etching amount, thereby reducing the product yield of the semiconductor device.

  In addition, metal films play an important role in the manufacture of semiconductor devices, and since they have low resistance, they are used not only for wiring materials but also for gate films. Normally, in wet etching of metal films, etching is performed using an acid-based chemical solution having a high metal-dissolving ability. However, depending on the metal, only an acid-based chemical solution does not have a sufficient etching ability, so that the oxidizing power is high. Etching is performed by mixing chemicals and repeating oxidation and etching of the metal film. Also in this case, the concentration of the chemical solution and the oxidizing agent used for the etching process must be accurately controlled. If the variation in concentration is large, the etching amount cannot be controlled to a desired value, and an unintended metal film is etched. In this case as well, the product yield of the semiconductor device is lowered.

Therefore, in Patent Document 1, as a method for controlling the concentration of the chemical solution, the concentration of the treatment chemical solution is measured with a concentration meter installed in the treatment tank in a one-bath type cleaning apparatus. A cleaning method for replenishment has been proposed.
JP 2002-289565 A

  However, in the current chemical concentration meter, since the chemical concentration of the low concentration chemical solution is lower than the variation in measured concentration, it is not only difficult to measure the concentration accurately, but it cannot be controlled to a desired set concentration. In addition, the chemical solution used for etching the metal film is cleaned using a cleaning chemical solution corresponding to each film type. In this case, a concentration meter corresponding to each chemical solution must be used. Conventionally used densitometers using conductivity have a problem in that the measurement variation is large and the concentration cannot be measured accurately.

  Therefore, in the present invention, the concentration control by the conventional densitometer is not performed, and the amount of change in the chemical component is calculated from the supply flow rate of each chemical solution, the chemical solution volatilization amount during non-processing, and the consumption amount by the processing wafer, thereby The purpose of the present invention is to provide an immersion type cleaning apparatus that can accurately control the amount of etching with respect to the film to be etched by accurately determining the mixing ratio and replenishing the required amount of chemical solution to control the chemical concentration. Yes.

  In order to solve the above-described problems, an immersion type cleaning apparatus according to the present invention includes a chemical solution treatment tank that performs wet etching treatment of a semiconductor substrate using a chemical solution, and a circulation pump that circulates the chemical solution in the chemical solution treatment tank. , Equipped with a flow meter for measuring the supply flow rate for supplying the chemical solution to the chemical treatment tank, and a supply amount calculation unit for calculating the supply amount from the supply flow rate and the supply time. The chemical ratio is calculated by calculating the mixing ratio.

  In addition, when the calculated chemical solution concentration is different from the set concentration, the replenishment amount of each chemical solution is calculated so as to become the set concentration, and the supply of the chemical solution is performed so that the desired replenishment amount is obtained by varying the supply time. It is characterized by doing.

  The chemical treatment tank also includes a thermometer for measuring the temperature of the chemical in the chemical treatment tank and a heater for controlling the temperature of the circulating chemical, and calculates the chemical volatilization amount from the circulation time and the chemical temperature. For this purpose, a volatilization amount calculation unit is provided.

  If the immersion type cleaning apparatus of the present invention is used, it is possible to control the concentration of the cleaning chemical in the processing tank to a set value, and the etching amount of the substrate or metal film by the chemical can be controlled.

  In addition, since it is possible to calculate the concentration from the mixing amount regardless of the cleaning chemical solution, a concentration meter corresponding to each cleaning chemical solution is not required, and the concentration control of various cleaning chemical solutions can be performed according to the present invention. The cleaning process can be performed regardless of the etching film.

  In addition, by stabilizing the concentration of the chemical solution, the frequency of chemical solution exchange can be reduced, which not only lowers the cost of the chemical solution, but also reduces the non-production time for chemical solution exchange, etc. Can also be improved.

  Hereinafter, an immersion type cleaning apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic view of an immersion type cleaning apparatus of the present invention. At the time of chemical solution exchange, the supply flow rates of the chemical solutions 21, 22, and 23 supplied to the chemical solution tank 1 are measured by the respective chemical flow meters 31, 32, and 33. The kind and number of chemicals supplied at this time are not limited. The measured flow rate is calculated by the calculation unit 7 in the supply time, and the total input amount of each chemical solution is calculated from the integrated value of the supply flow rate and the supply time. The mixing ratio is calculated from the total amount of each chemical solution added, and the chemical concentration is calculated.

  When the concentration calculated at this time is different from the set concentration, the replenishment amount of each chemical solution is calculated by the calculation unit 7 so as to obtain a desired chemical solution concentration, and the replenishment amount is adjusted by varying the supply time. Only the chemical solution to be replenished over the supply time calculated by the calculation unit 7 is opened, and the chemical solution is supplied to the chemical solution tank 1 to adjust the chemical solution concentration.

  A method for controlling the chemical concentration when the chemical is circulated by the circulation pump 8 will be described with reference to FIGS.

  As shown in FIG. 2, when the concentration of a chemical solution changes due to volatilization regardless of whether the semiconductor substrate is processed or not, the concentration of the chemical solution decreases over time, and the concentration of the chemical solution depends on the situation of cleaning the semiconductor substrate 6. Different. Since the volatilization amount of the chemical solution greatly depends on the chemical solution temperature, the chemical solution temperature constantly measured by the treatment tank thermometer 5 installed in the chemical solution tank 1 and the chemical solution volatilization amount per unit time when used at that temperature Further, the amount of volatilization of each chemical solution is calculated in the calculation unit 7 from the time circulated in the chemical solution tank 1 after the chemical solution exchange. Further, the difference between the amount of each chemical solution and the input amount at the time of replacing the chemical solution is calculated, and the concentration of the chemical solution is obtained from the mixing ratio.

  At this time, if the chemical solution concentration is significantly different from the set concentration, the chemical solution replenishment amount is calculated from the volatilization amount by the calculation unit 7, and the mixing valve 4 for only the chemical solution to be supplemented is opened and supplied to the chemical solution tank 1. The replenishment amount at this time is determined by the calculation unit 7 from the supply flow rate of the chemical solution. During the determined supply time, the mixing valve 4 is opened and the chemical solution is replenished with a desired replenishment amount.

  The chemical replenishment at this time is preferably performed immediately before the semiconductor substrate 6 is put into the chemical liquid tank 1 and cleaned as much as possible. The volatilization amount immediately before the processing is calculated by the arithmetic unit 7 and the chemical liquid is replenished. Since the chemical concentration at the time of processing the substrate 6 can be made the same as the set concentration, the etching amount by the chemical can be controlled.

  Thereafter, when chemical solution replenishment is performed for the concentration change due to volatilization with the same chemical solution, the volatilization amount is calculated from the elapsed time since the previous replenishment and the processing bath temperature, and the necessary replenishment amount is determined. As described above, since the concentration of the chemical solution can be made constant, the frequency of the chemical solution exchange can be reduced.

  Also, as shown in FIG. 3, when the chemical solution is consumed by the semiconductor substrate 6 and changes in concentration, the semiconductor substrate 1 immediately after the cleaning treatment of the semiconductor substrate 6 in the chemical bath 1 or immediately before the next cleaning treatment. The consumption amount is calculated by the calculation unit 7 from the amount of the chemical solution consumed on the sheet and the number of processed semiconductor substrates, and the same amount of chemical solution is replenished as the consumption amount. In any case, the mixing valve 4 is opened only for the chemical solution to be replenished, and the chemical solution is supplied during the supply time calculated by the calculation unit 7 from the amount to be replenished and the supply flow rate.

  Furthermore, as shown in FIG. 4, when the concentration changes due to volatilization and consumption of the semiconductor substrate, replenishment may be performed by calculating both the volatilization amount and the consumption amount. Also in this case, it is desirable that the chemical solution is replenished immediately before the semiconductor substrate 6 is put into the processing tank 1.

(Embodiment 2)
In addition, when the concentration changes due to the volatilization of the chemical solution as shown in FIG. 5, the temperature for volatilization varies depending on the type of the chemical solution. The volatilization amount of the chemical solution may be controlled by the above. Since the amount of volatilization of the chemical solution can be suppressed by lowering the chemical solution temperature by the heater 9 while the semiconductor substrate is not cleaned in the chemical solution tank 1, the replenishment amount can be reduced.

  Moreover, when it is desired to volatilize several kinds of chemical liquid components contained in the processing chemical liquid, the processing tank temperature may be increased, and a desired volatilization amount can be obtained, so that the mixing amount of the chemical liquid can be adjusted.

(Embodiment 3)
Further, when the etching target is a metal film, the metal substrate is effectively oxidized by supplying an oxidizing agent such as hydrogen peroxide water or ozone water immediately before the semiconductor substrate 6 is put into the chemical bath 1. The film may be etched.

  At this time, as shown in FIG. 6, the amount of oxidant input may be determined in the calculation unit 7 from the consumption per semiconductor substrate and the number of semiconductor substrates 6 that are put into the chemical bath 1 and cleaned. Etching of the metal film stops and etching of the metal film stops when all of the oxidizing agent in the chemical solution is consumed, so that unnecessary etching is not performed and the etching amount can be controlled to a desired amount. . After cleaning the semiconductor substrate, the oxidant is not replenished because the oxidant is not contained in the chemical solution.

  Since the immersion type cleaning apparatus according to the present invention can control the concentration of the circulating chemical solution, it is useful as one that can stably carry out etching of a semiconductor substrate.

Sectional view of the immersion type cleaning apparatus of the present invention The figure which shows the relationship between the elapsed time which concerns on Embodiment 1 of this invention, and a chemical | medical solution concentration. The figure which shows the relationship between the elapsed time which concerns on Embodiment 1 of this invention, and a chemical | medical solution concentration. The figure which shows the relationship between the elapsed time which concerns on Embodiment 1 of this invention, and a chemical | medical solution concentration. The figure which shows the relationship between the elapsed time which concerns on Embodiment 2 of this invention, a chemical | medical solution concentration, and heater temperature. The figure which shows the relationship between the elapsed time which concerns on Embodiment 3 of this invention, and a chemical | medical solution concentration.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Chemical tank 21-23 Cleaning chemical liquid 31-33 Chemical flow meter 4 Mixing valve 5 Processing tank thermometer 6 Semiconductor substrate 7 Calculation part 8 Circulation pump 9 Heater

Claims (3)

A chemical treatment tank for performing a wet etching process on a semiconductor substrate using a chemical,
A circulation pump for circulating the chemical solution in the chemical solution treatment tank;
A flow meter for measuring the supply flow rate for supplying the chemical solution to the chemical treatment tank;
A supply amount calculation unit for calculating the supply amount from the supply flow rate and the supply time,
An immersion type cleaning apparatus that calculates a chemical concentration by calculating a mixing ratio in the chemical treatment tank from the input amount of the chemical.   When the calculated concentration of the chemical solution is different from the set concentration, the replenishment amount of each chemical solution is calculated so as to be the set concentration, and the supply of the chemical solution is performed so that the desired replenishment amount is achieved by varying the supply time. The immersion type cleaning apparatus according to claim 1, wherein the immersion type cleaning apparatus is performed. The chemical treatment tank is a thermometer for measuring a chemical temperature in the chemical treatment tank,
A heater for controlling the temperature of the circulating chemical solution,
The immersion cleaning apparatus according to claim 1, further comprising a volatilization amount calculation unit for calculating the chemical volatilization amount from the circulation time and the chemical liquid temperature.

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