CN1379288A - Etching method and quantitative analysis method of etching liquid - Google Patents
Etching method and quantitative analysis method of etching liquid Download PDFInfo
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- CN1379288A CN1379288A CN02108573A CN02108573A CN1379288A CN 1379288 A CN1379288 A CN 1379288A CN 02108573 A CN02108573 A CN 02108573A CN 02108573 A CN02108573 A CN 02108573A CN 1379288 A CN1379288 A CN 1379288A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3205—Deposition of non-insulating-, e.g. conductive- or resistive-, layers on insulating layers; After-treatment of these layers
- H01L21/321—After treatment
- H01L21/3213—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer
- H01L21/32133—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only
- H01L21/32134—Physical or chemical etching of the layers, e.g. to produce a patterned layer from a pre-deposited extensive layer by chemical means only by liquid etching only
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
- C23F1/00—Etching metallic material by chemical means
- C23F1/10—Etching compositions
- C23F1/14—Aqueous compositions
- C23F1/16—Acidic compositions
Abstract
The invention provides an etching method for metal which uses an etching solution containing nitric acid and phosphoric acid, and is improved so as to maintain long the etching capacity of the etching solution. In the etching method for metal, an etching solution containing nitric acid and phosphoric acid is repeatedly used. In this method, the control of the concentration to be required is performed before the repeated use based on the measured result of the concentration equivalent to the acid components prescribed in the following formula (1): the concentration (wt.%) equivalent to the acid components = the concentration (wt.%) of nitric acid * 98/63 + the concentration (wt.%) of phosphoric acid (1) (wherein, 98 is the molecular weight of phosphoric acid, and 63 is the molecular weight of nitric acid).
Description
Technical Field
The present invention relates to a metal etching method, and more particularly, to an etching method suitable for use in a microetching step using a photosensitive resin or the like for forming a fine electrode or metal wiring on a metal (layer) in a substrate manufacturing step of a semiconductor device substrate, a liquid crystal element substrate, or the like. The present invention also relates to a method for quantitatively analyzing the etching solution and a method for recovering phosphoric acid from the etching solution.
Background
In recent years, demands for miniaturization and high performance of wiring, electrodes, and the like attached to a semiconductor device substrate or a liquid crystal element substrate have become more severe.
In response to such a demand, a low-resistance material suitable for fine etching processing and capable of withstanding an increase in the electrical demand of the device has been discussed in place of a conventionally used chromium (Cr) alloy wiring material such as CrMo. For example, new materials made of aluminum (Al), silver, copper, and the like are proposed for use as wiring materials, and microfabrication using such new materials is also under discussion. In etching of these new materials, an etching solution containing nitric acid, phosphoric acid, and acetic acid is generally used.
When aluminum is used as a metal to be etched, it is necessary to remove aluminum by ionizing it from 0 to 3 valent, and there is a problem that the etching rate is difficult to control because the amount of acid consumed in an etching solution is large compared with silver (1 valent) or copper (2 valent), and the etching rate is rapidly decreased. Therefore, in a batch process such as a dipping method, if the etching rate of the etching solution is lower than a specific value, the etching solution is usually discarded in its entire amount even if a large portion of the etching ability of the etching solution remains, and a new etching solution is replaced, which causes a problem that the amount of the etching solution used and the amount of the etching solution discarded are large.
Disclosure of Invention
The present invention has been made in view of the above circumstances, and an object thereof is to provide a metal etching method in which an etching solution containing nitric acid and phosphoric acid is repeatedly used, that is, an improved etching method in which the etching ability of the etching solution can be maintained for a long period of time. Further, another object of the present invention is to provide a method for quantitatively analyzing the etching solution and a method for recovering phosphoric acid from the etching solution.
The present inventors have conducted intensive studies in view of the above-mentioned problems, and as a result, have found that, in an etching solution containing nitric acid and phosphoric acid, phosphoric acid is dissociated only in the 1 st order, and it is considered that nitric acid, which functions as an oxidizing agent, also functions as an etching acid, and that if the concentration of the etching acid in the etching solution is controlled to be constant, the etching rate can be controlled.
The present invention was further studied based on the above findings, and the present invention consists of related 5 inventions, and the gist of each invention is as follows.
That is, the 1 st gist of the present invention resides in an etching method for a metal in which an etching solution containing nitric acid and phosphoric acid is repeatedly used, characterized in that necessary concentration adjustment is performed before the repeated use based on the measurement result of the concentration corresponding to the acid component defined in the following formula (1):
acid component corresponding concentration (wt%) ═ nitric acid concentration (wt%) × 98/63+ phosphoric acid concentration (wt%) … (1)
(in the above formula, 98 is the molecular weight of phosphoric acid, 63 is the molecular weight of nitric acid).
The 2 nd gist of the present invention resides in an etching method or an etching apparatus, characterized by comprising the following steps (I) to (IV):
(I) a step of calculating the concentration of an etching solution containing nitric acid and phosphoric acid and not containing a metal to be etched ionized by etching, in accordance with an acid component specified by the following formula (1):
acid component-corresponding concentration (wt%) + phosphoric acid concentration (wt%) + nitric acid concentration (wt%) × 98/63 … (1);
(II) a step of etching a metal using the etching solution;
(III) adjusting the concentration of the acid component in the etching solution used for etching the metal to be equal to the concentration of the acid component calculated in the step (I);
(IV) a step of etching the metal using the etching solution whose concentration has been adjusted in the step (III).
The 3 rd gist of the present invention resides in a method for quantitatively analyzing an etching liquid containing an ionized etched metal, which is used in a metal etching process and contains phosphoric acid and an ionized etched metal, characterized in that the concentration of phosphoric acid is measured by the following steps (a) and (b):
(a) firstly, drying the etched etching solution to remove nitric acid and acetic acid;
(b) then, the concentration of phosphoric acid was analyzed by neutralization titration, and during this time, the amount 2 times the amount of titration up to the 1 st inflection point of phosphoric acid was regarded as the amount of titration up to the 2 nd inflection point of phosphoric acid, and the concentration of phosphoric acid was calculated.
The 4 th gist of the present invention resides in a method for quantitatively analyzing an etching solution containing no metal to be etched ionized by etching, which comprises a step of quantitatively analyzing an etching solution used in a metal etching process, which contains nitric acid and phosphoric acid, and which does not contain a metal to be etched ionized by etching, wherein the concentration of nitric acid is determined by an ultraviolet absorption photometry, the concentration of phosphoric acid is determined by a neutralization titration method after drying a mixed acid solution, and the concentration of acetic acid is calculated by subtracting the nitric acid equivalent and the phosphoric acid equivalent from the total acid equivalent.
The 5 th gist of the present invention resides in a method for recovering phosphoric acid from an etching solution used for metal etching, characterized by drying an etching solution used for metal etching containing nitric acid and phosphoric acid, and then removing an ionized metal to be etched in the etching solution.
Drawings
FIG. 1 is a schematic view of an example of an etching apparatus 1 used in the present invention.
Description of the symbols: 1, etching a groove; 2 circulating pump of analytical equipment; 3 nitric acid/phosphoric acid/acetic acid concentration analysis device; 4, etching the object; 5, a fresh acetic acid liquid tank; 6 a fresh acetic acid liquid supply pump; 7 a heating device; 8 acetic acid concentration output signal; 9 etch stop waste purge line; 10 new etching solution (concentration-adjusted phosphoric acid/nitric acid/acetic acid) introduction line; 11 a stirring device; 12, removing and regulating an output signal by using the etching waste liquid; 13 a liquid level gauge; 14 new etching liquid introduction signal; 15 a fresh etching solution tank; 16 fresh etching solution supply pump.
Detailed Description
The present invention will be described in detail below.
First, the etching method of the present invention is explained. The present invention is a metal etching method in which an etching solution containing nitric acid and phosphoric acid is repeatedly used.
The metal to be etched is not particularly limited, but aluminum (Al), silver, copper or an alloy containing any one or more of these metals as a main component is preferable, and Al or an alloy containing Al is particularly preferable. The ratio of the main component in the above alloy is usually more than 50% by weight, preferably more than 80% by weight. On the other hand, the lower limit of the minor component (additive component) is usually 0.1% by weight.
The phosphoric acid concentration of the etching solution is generally greater than 50% by weight, preferably greater than 60% by weight, particularly preferably greater than 70% by weight, generally less than 85% by weight, preferably less than 84% by weight, particularly preferably less than 80% by weight. When the phosphoric acid concentration is too low, the etching rate is low and the etching efficiency is low. Therefore, the concentration of phosphoric acid is preferably selected from the above range.
The phosphoric acid concentration of the etching solution is generally greater than 0.1% by weight, preferably greater than 0.5% by weight, particularly preferably greater than 3% by weight, generally less than 20% by weight, preferably less than 15% by weight, particularly preferably less than 12% by weight, and more preferably less than 8% by weight. The higher the nitric acid concentration, the higher the etching rate, however, when the nitric acid concentration is too high, an oxide film is formed on the surface of the metal to be etched, the etching rate tends to decrease, and the edge etching amount tends to increase due to oxidative deterioration of the photosensitive resin (resist) present on the metal to be etched. Therefore, the concentration of the acid is preferably selected from the above range.
The etching solution may also contain a diluent, a surfactant, a chelating agent, and the like. Usually the etching liquid contains water in addition to these components.
The thinner is helpful for improving the wettability of the etching solution and the resist and adjusting the etching speed. The diluent includes acetic acid, citric acid, malic acid, etc., of which acetic acid is preferable. The concentration of the diluent is generally greater than 0.1% by weight, preferably greater than 0.5% by weight, particularly preferably greater than 1% by weight, and more preferably greater than 2% by weight, relative to the total weight of the etching solution. The upper limit thereof is determined by the area ratio of the photosensitive resin surface from the viewpoint of improving the wettability of the photosensitive resin surface (hydrophobicity), and is usually less than 50% by weight, preferably less than 35% by weight, particularly preferably less than 20% by weight, and more preferably less than 10% by weight.
The surfactant reduces the surface tension of the etching solution and improves the wettability to the pattern on the object to be etched. In particular, when an object to be etched has a fine pattern such as a substrate for manufacturing a semiconductor device or a liquid crystal element substrate, uniform etching can be achieved by improving wettability of an etching solution to the pattern. Since the etching solution of the present invention is acidic, it is preferable that the etching solution is not decomposed under acidic conditions as a surfactant. The amount of surfactant added is generally greater than 0.001 wt%, preferably greater than 0.01 wt%, particularly preferably greater than 0.1 wt%, more preferably greater than 0.2 wt%, generally less than 1 wt%, preferably less than 0.5 wt%, relative to the total weight of the etching solution.
The concentration of water in the etching solution is generally greater than 1% by weight, and generally less than 20% by weight.
In general, in an etching solution containing nitric acid and phosphoric acid, it can be said that nitric acid functions as an oxidizing agent for oxidizing a metal surface, and phosphoric acid functions as an acid for dissolving the oxidized metal surface. The reaction at this time is shown in the formula (A).
However, the present inventors have found that, in the case of an etching solution formed of nitric acid, phosphoric acid and acetic acid, aluminum is used as a metal to be etched, and the etching solution is an etching solution, the aluminum and the phosphoric acid react with each other to generate hydrogen, regardless of the presence or absence of nitric acid as an oxidizing agent, and the reaction of the formula (C) and the reaction of the formula (B) occur together. Further, the reaction of formula (B) and formula (C) is combined to give formula (D).
：(B)
：(D)
As is clear from the formula (D), the consumption amount of nitric acid (oxidizing agent) is about 60% of the theoretical amount with respect to 1 mol of Al, and phosphoric acid (acid component) is consumed only by the 1-stage dissociation portion under a strong acid such as that of the etching solution, and as a result, phosphoric acid as an acid component is consumed 3 times by mol with respect to Al as a metal to be etched.
In the etching method of the present invention, based on the measurement result of the concentration of the acid component specified by the following formula (1), the concentration is adjusted as necessary before the repeated use. In a preferred embodiment of the present invention, nitric acid and/or phosphoric acid is added to the etching solution after etching to adjust the concentration to the same value as the concentration corresponding to the acid component of the etching solution before etching. The nitric acid concentration and the phosphoric acid concentration of the etching solution are preferably measured by the quantitative analysis method described later.
Acid component corresponding concentration (wt%) ═ nitric acid concentration (wt%) × 98/63+ phosphoric acid concentration (wt%) … (1)
(in the above formula, 98 is the molecular weight of phosphoric acid, 63 is the molecular weight of nitric acid).
The acid component corresponding concentration in the above formula is a parameter obtained by converting nitric acid into phosphoric acid and determining the acid component in the etching solution as the phosphoric acid concentration, but by controlling such a parameter at a constant value, the etching rate can be kept at a constant value.
The acid equivalent component concentration is controlled to be generally more than 50 wt%, preferably more than 70 wt%, generally less than 85 wt%, preferably less than 84 wt%. The higher the acid component concentration, the faster the etching rate. However, since the concentration of commercially available phosphoric acid is usually 85 wt%, when the concentration of phosphoric acid is 85 wt%, the concentration of nitric acid becomes 0 wt% (oxidizing agent is not present), and the generated hydrogen covers the metal surface, thereby slowing down the etching rate. Thus, the phosphoric acid concentration is preferably less than 84 wt%.
In a preferred embodiment of the present invention, when the concentration of the metal to be etched existing in the etching solution and ionized by etching is a (mol%) and the valence of the ionized metal to be etched is Y, the concentration is adjusted so that the concentration of nitric acid (mol%) in the etching solution becomes greater than the product of a and Y.
The etching rate is controlled by controlling the concentration of the acidic moiety in the etching solution, and for example, when only phosphoric acid is added to control the concentration of the acidic moiety, the concentration of nitric acid in the etching solution, that is, the concentration of the oxidizing agent in the etching solution can be reduced. Further, if the concentration of the oxidizing agent becomes too low, the reaction of the formula (B) may not proceed, and the etching rate may be lowered. Therefore, in a preferred embodiment of the present invention, the ratio of phosphoric acid and nitric acid is generally determined so as to satisfy the above-described formulas (C) and (D). However, even when these formulae are not satisfied, the concentration (mol%) of nitric acid in the etching solution may be in a range larger than the product (AY) of the concentration (a) of the ionized metal to be etched and the valence (Y) of the metal.
By adjusting the nitric acid concentration in the etching solution as described above, the etching rate can be adjusted without adding a diluent component or the like, and the etching can be continued for a long period of time during which the etching rate is stable.
In order to adjust the concentration of the acidic moiety and/or the concentration of nitric acid in the etching solution, phosphoric acid and/or nitric acid may be added to the etching solution after the etching, however, in a preferred embodiment of the present invention, a part of the etching solution after the etching is extracted from the etching step, and then nitric acid and/or phosphoric acid is added to the etching solution remaining in the etching step, so that the concentration is adjusted to the same value as the concentration of the acidic moiety in the etching solution before the etching.
By drawing out a part of the etching solution as described above, the total amount of the etching solution can be constantly kept constant. Since the etching solution after the etching treatment is reused as the etching solution by removing the extracted portion and adding the oxidizing agent and the acid component, the amount of the waste etching solution can be reduced as compared with the case where the entire amount of the etching solution after the etching treatment is discarded.
The amount of the etching solution to be extracted (F) is appropriately selected depending on the etching rate or the composition thereof, and in a preferred embodiment of the present invention, the amount is set so as to satisfy the following formula (2) as a value of 1000g of the etching solution.
A: 100 (constant), B: 500 (constant), F: the amount of the etching solution taken out [ g ],
c0: the acid component of the etching solution before etching had a concentration [ wt.% ],
c1: the acid component of the etching solution after etching corresponds to the concentration [ wt. ].
When the etched metal is Al, the constants in the preceding formula are preferably a-200 and B-300, more preferably a-210 and B-280.
When the extracted amount (F) of the etching solution is smaller than the above range, the concentrations of the acid and the oxidizing agent cannot be maintained, and the etching rate becomes slow, and when it is larger than the above range, the reuse efficiency of the etching solution becomes poor, and the amount of the etching solution to be discarded becomes large, similar to the whole solution exchange method.
With respect to the nitric acid and phosphoric acid added to the etching solution after the end of etching, the concentration C (wt%) corresponding to the acid component determined from the added nitric acid and phosphoric acid satisfies the following formula (3), and preferably the ratio of phosphoric acid and nitric acid satisfies the following formula (4). The G (constant) in the formula (4) is preferably 5 to 10.
C1+D×(C0-C1)≥C≥C1+E×(C0-C1)…(3)
C0: the acid component of the etching solution before etching has a corresponding concentration (wt%),
c1: the acid component of the etching solution after etching has a corresponding concentration (wt%),
d: 6 (constant), E: 1 (constant)
Phosphoric acid (wt%): nitric acid (wt%) × 98/63 ═ G: 1 … (4)
G: 1 to 10 (constant)
In this period, phosphoric acid may be used in a high concentration of 1 to 5 wt%, preferably 1 to 3 wt%, higher than the phosphoric acid concentration in the etching solution before etching. The nitric acid may be used in a high concentration which is usually 0.1 to 2.0 wt%, preferably 0.1 to 0.5 wt% higher than the nitric acid concentration in the etching solution before etching.
In addition, the composition of the etching solution can be controlled by analyzing the composition of the etching solution as appropriate among other components, such as volatile acetic acid, and the like, in a diluent or the like, and compensating for the shortage. Further, it is preferable that the sum of the additives such as phosphoric acid, nitric acid and acetic acid is the same as the amount extracted from the etching solution, because the liquid level of the etching solution in the etching bath is kept constant.
Specifically, the etching method of the present invention includes the following steps (I) to (IV).
(I) A step of calculating the concentration of an etching solution containing nitric acid and phosphoric acid, and not containing a metal to be etched ionized by etching, in accordance with an acid component specified by the following formula (1):
acid component corresponding concentration (wt%) + phosphoric acid concentration (wt%) + nitric acid concentration (wt%) × 98/63 … (1);
(II) a step of etching a metal using the etching solution;
(III) adjusting the concentration of the etching solution so that the concentration of the etching solution corresponding to the acid component used for etching the metal is equal to the value of the concentration of the etching solution corresponding to the acid component calculated in the step (I);
(IV) etching the metal with the etching solution having the concentration adjusted in the step (III).
In this etching method, after the steps (I) to (IV) are completed, the step (III) and the step (IV) are usually repeated. In the step (III), the concentration is adjusted by withdrawing a part of the etching solution from the system as needed and then adding nitric acid and/or phosphoric acid thereto, as described above.
As the etching apparatus, a conventionally known apparatus used in a spray system or a dip system can be used. Further, either a batch method or a continuous method may be used.
Specifically, the etching apparatus includes the following steps (I) to (IV).
(I) Calculating the concentration of an etching solution containing nitric acid and phosphoric acid and not containing a metal to be etched ionized by etching, the concentration corresponding to an acid component specified by the following formula (1),
acid component corresponding concentration (wt%) + phosphoric acid concentration (wt%) + nitric acid concentration (wt%) × 98/63 … (1);
(II) a step of etching a metal using the etching solution;
(III) adjusting the concentration of the acid component in the etching solution used for etching the metal to be equal to the concentration of the acid component calculated in the step (I);
(IV) a step of etching the metal with the use of the etching solution having the concentration adjusted in the step (III).
Fig. 1 is a schematic diagram of an example of an etching apparatus of a program feedback setting method used in the present invention.
The etching apparatus shown in FIG. 1 is mainly composed of an etching bath (1), an analyzer circulation pump (2), a nitric acid/phosphoric acid/acetic acid concentration analyzer (3), a fresh acetic acid bath (5), a fresh acetic acid supply pump (6), a heating device (7), an etching-terminated waste liquid removal line (9), a fresh etching liquid (concentration-adjusted phosphoric acid/nitric acid/acetic acid) introduction line (10), a stirring device (11), a fresh etching liquid bath (15), and a fresh etching liquid supply pump (16). And receives an acetic acid concentration output signal (8) from the analyzer means (3) to control the amount of the fresh acetic acid solution to be supplied. Further, the amount of the etching liquid removed is controlled by receiving an etching liquid removal regulation output signal (12) from the analyzer means (3). That is, first, a necessary amount of the etching terminating solution proportional to the difference in the equivalent acid concentration is partially withdrawn from the etching chamber (1) through the etching terminating waste solution removing line (9). Then, a new etching solution introduction signal (14) is received from a liquid level meter (13) provided in the etching chamber (1), and a new etching solution is supplied from a new etching solution introduction line (10) and returned to the predetermined liquid level of the etching chamber (1). The object (4) to be etched is immersed in an etching solution in the etching tank (1) in an appropriate manner.
According to the etching apparatus described above, acetic acid may be added so that the number of moles is constant. In addition, by a programmed feedback setting method similar to that of acetic acid, a new solution of nitric acid, phosphoric acid and acetic acid is added to the etching solution to make the concentration value of the acid component in the etching solution constant, and the etching rate can be returned to the value at the start of etching.
In short, it is possible to provide nitric acid and phosphoric acid which can form concentrations corresponding to acid components equivalent to the acid components used in the consumed portion of the dissolved aluminum equivalent to the etching liquid reduced portion. It is also conceivable to supply a new etching solution by supplementing an acid such as acetic acid or other components, which are taken out and reduced separately. Further, since the increase in the number of moles of nitric acid in the etching solution can be adjusted by periodically withdrawing a part of the etching solution, continuous etching can be performed without exchanging the total amount of the etching solution. The concentration of aluminum dissolved in the etching solution may be analyzed outside the etching chamber (1), or a value estimated from the mass balance such as the number of processes of the object to be etched (4) may be used.
The temperature of the etching solution is in the range of typically more than 20 deg.c, preferably more than 25 deg.c, typically less than 50 deg.c, preferably less than 40 deg.c.
If the etching solution after etching is dried under the condition that phosphoric acid is not evaporated to remove nitric acid and acetic acid, a liquid containing ionized etched metal and phosphoric acid can be obtained. Phosphoric acid, nitric acid and acetic acid used as raw materials of the etching solution are high-purity products having impurity contents of less than ppm. Thus, by removing the etching target metal from the solution containing the etching target metal and phosphoric acid with an ion exchange resin or the like, high-purity phosphoric acid can be obtained. Further, if the removed etched metal is also recovered, it can be used as various raw materials.
The etching method of the present invention is used in a fine etching process using a photosensitive resin or the like for forming a fine electrode or metal wiring on a metal or a metal layer in the production process of various substrates such as a semiconductor device substrate and a liquid crystal element substrate.
Next, the method for quantitatively analyzing the etching solution of the present invention will be described.
The 1 st analysis method of the present invention is a method for quantitatively analyzing an etching liquid containing phosphoric acid and ionized metal to be etched, which is used in a metal etching process, as described above, and is characterized in that the concentration of phosphoric acid is measured by the following steps (a) and (b). In a preferred embodiment of the present invention, the concentration of nitric acid is quantified by ultraviolet absorptiometry.
(a) First, the etching solution after etching is dried to remove nitric acid and acetic acid.
(b) Then, the concentration of phosphoric acid was analyzed by neutralization titration. During this period, the amount of the solution 2 times the amount of the solution dropping to the 1 st inflection point of phosphoric acid was regarded as the amount of the solution dropping to the 2 nd inflection point of phosphoric acid, and the concentration of phosphoric acid was calculated.
The drying may be performed under conditions where phosphoric acid does not evaporate, but is generally performed by heating the sample in a boiling water bath for 30 to 60 minutes. Thus, the nonvolatile phosphoric acid remains intact in the sample, and acids (nitric acid and acetic acid) other than phosphoric acid are removed from the sample.
The neutralization titration is usually carried out using an aqueous sodium hydroxide solution of 0.1 to 1 mol/liter as a standard solution. In general, phosphoric acid is dissociated in 3 stages in water and is known as a 3-valent acid, but in neutralization titration, a 2-stage reaction as shown below occurs and is treated as a 2-valent acid.
< stage 1: pH2.9 to 4.5>
< stage 2: pH4.5 to >
Therefore, the neutralization curve of phosphoric acid usually has a 1 st inflection point and a 2 nd inflection point, and the 2 nd inflection point is the endpoint of the neutralization titration. After the 1 st inflection point, metal ions derived from the metal to be etched precipitate as a metal hydroxide due to the increase in PH of the solution. Under the influence of the precipitate, the accuracy of neutralization titration is very low, and the concentration of phosphoric acid cannot be accurately measured. Therefore, if the concentration of phosphoric acid is calculated by considering 2 times the amount of the drop up to the 1 st inflection point as the amount of the drop up to the 2 nd inflection point, the concentration of phosphoric acid can be accurately determined because the concentration of nitric acid is not affected.
In a preferred embodiment of the 1 st analysis method, the nitric acid concentration of the etching solution is generally performed by ultraviolet absorptiometry using a calibration curve prepared from a reference solution having a known nitric acid concentration. For the preparation of the standard solution, for example, nitrate such as potassium nitrate is dissolved in water.
In a preferred embodiment of the 1 st analysis method, the acetic acid concentration is calculated by subtracting the nitric acid and phosphoric acid concentrations obtained by the above-described method from the total acid concentration value measured in advance. The measurement of the total acid concentration is not particularly limited, and is generally performed by neutralization titration without drying the etching solution. The acetic acid concentration may be determined by conversion from a measured value of TOC (total organic carbon), for example, in the absence of a surfactant.
In the etching method of the present invention described above, in order to measure the nitric acid concentration and the phosphoric acid concentration of the etching solution used for metal etching, the 1 st analysis method is preferably used. The method of analysis 1 can be used to measure the nitric acid concentration and phosphoric acid concentration of the original etching solution not used for metal etching.
The 2 nd analysis method of the present invention is a method for quantifying an original metal etching solution before etching, which is an etching solution used in a metal etching process and contains nitric acid and acetic acid and does not contain a metal to be etched ionized by etching.
(1) The concentration of nitric acid was quantified by ultraviolet absorbance,
(2) the concentration of phosphoric acid is quantified by a neutralization titration method after the drying of the mixed acid solution,
(3) the concentration of acetic acid was calculated by subtracting the nitric acid and phosphoric acid equivalents from the total acid equivalents.
In the 2 nd analysis method, quantitative analysis of nitric acid was performed by ultraviolet absorptiometry using a calibration curve prepared from a reference solution having a known nitric acid concentration. In the preparation of the reference liquid, an aqueous solution of a nitrate such as potassium nitrate is used.
In the 2 nd analysis method, quantitative analysis of phosphoric acid was performed by neutralization titration after drying of the mixed acid solution. Drying is usually carried out by heating the sample in a boiling water bath for 30 to 60 minutes. Thus, as nonvolatile phosphoric acid, it remained intact in the sample, and acids (nitric acid and acetic acid) other than phosphoric acid were removed from the sample. The neutralization titration after drying is usually carried out as a standard solution with a 1 mol/l aqueous solution of sodium hydroxide.
Generally, phosphoric acid is dissociated in 3 stages in water and known as a 3-valent acid, but in the neutralization titration, a 2-stage reaction shown below is caused, and the acid equivalent is calculated as a 2-valent acid treatment.
< stage 1: pH2.9 to 4.5>
< stage 2: pH4.5 to >
In the 2 nd analysis method, the concentration of acetic acid is calculated by subtracting the total of nitric acid equivalent and phosphoric acid equivalent from the total acid equivalent (subtraction method). Specifically, the calculation is performed by the following equation.
Acetic acid equivalent (total acid equivalent) - (nitric acid equivalent + phosphoric acid equivalent)
On the other hand, the total acid equivalent of the mixed acid solution is generally determined by neutralization titration using a 1 mol/l aqueous solution of sodium hydroxide in a standard solution, as shown in the following reaction in stage 2.
<Stage 1>
<Stage 2>
In the etching method of the present invention described above, in order to measure the concentrations of nitric acid, phosphoric acid and acetic acid in the etching solution used in the metal etching process which is an etching solution before repeated use and does not contain ionized metal to be etched by etching, it is preferable to use the 2 nd analysis method.
In the analysis method 2, the quantitative analysis of phosphoric acid is inhibited by metal ions such as aluminum, silver, and copper, and there is a problem that the results are discrete. Therefore, the object to be measured is preferably an etching solution not containing the metal ions as described above. The removal of metal ions from the mixed acid solution can be easily performed by a cationic ion exchange resin or a chelate resin.
[ examples ]
The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. In the following description, [% ] means "% by weight" unless otherwise specified.
The etching apparatus shown in FIG. 1 was used as the apparatus. The etching object was formed by providing aluminum with a thickness of 1.2 μm on a glass substrate and patterning the aluminum with a photosensitive resin.
Example 1
1000g of an etching solution composed of 5.2% nitric acid, 73% phosphoric acid and 3.4% acetic acid, the balance being water (acid content corresponding to a concentration of 81.1%) was charged into an etching bath (1) shown in FIG. 1, and the uniformity of the etching solution was attempted by using a heating apparatus (7) and a stirring apparatus (11) and taking an etching temperature of 33 ℃.
An object (4) to be etched is immersed in an etching solution in an etching tank (1), and the start time is measured, and the end of etching is visually confirmed to calculate the etching rate, and the etching rate of the etching solution at the start of etching is 2300 Å/min.
The amount of aluminum dissolved in the etching solution by etching was calculated from the area and thickness of the etched portion removed from the substrate, and integrated, the etching rate at the time of termination of etching (the time point when the amount of aluminum dissolved by etching reached 1 g) was 2150 Å/min (about 93% of the time of initiation of etching).
After the etching was terminated, the concentrations of nitric acid, phosphoric acid and acetic acid in the etching solution were analyzed by the following methods, i.e., 5.1% nitric acid, 71.9% phosphoric acid and 3.4% acetic acid (the concentration of the acid component corresponds to 79.8%).
(1) Quantitative analysis of nitric acid:
first, 6g of the mixed acid solution was diluted with water to 250 g. An aqueous solution of potassium nitrate prepared to contain 25mg of nitric acid component per 1g was used as a reference solution, and the absorbance near 300nm was measured. The measuring apparatus used was a process titrator [ ECOSAVER-100] (manufactured by Mitsubishi chemical corporation). Water was used as a control. A calibration curve is prepared from the relationship between the reference solution and the absorbance, and the concentration of nitric acid in the mixed acid solution is calculated.
(2) Quantitative analysis of phosphoric acid:
first, 1g of the mixed acid solution was heated in a boiling water bath for 30 minutes or more, and after drying, the entire residue was washed in a 200ml container, and the concentration of phosphoric acid was calculated by neutralization titration with a 1 mol/l aqueous solution of sodium hydroxide.
(3) Acetic acid analysis was performed by subtraction of nitric acid equivalents and phosphoric acid equivalents from the total acid equivalents:
first, 1g of the mixed acid solution was diluted with 50ml of water, and the neutralized titration was carried out with a 1 mol/l aqueous sodium hydroxide solution, and the total acid equivalent in the mixed acid solution was measured. Then, the acid equivalent of nitric acid and phosphoric acid obtained in (1) and (2) above was subtracted from the total acid equivalent to obtain the equivalent of acetic acid, and the acetic acid concentration was calculated from the acetic acid equivalent.
Then, 310g of the etching solution was removed from the etching bath (1), and 310g of a mixed acid solution composed of 5.5% nitric acid, 75.4% phosphoric acid, 3.4% acetic acid, and the balance water was added to the etching bath (1), and the concentrations of the respective components in the etching solution of the etching bath (1) were 5.2% nitric acid, 73% phosphoric acid, and 3.4% acetic acid (the acid component corresponds to a concentration of 81.1% by weight), and the etching rate was 2300 Å/min.
From the above results, the etching solution amount necessary for etching 1g of aluminum was continuously etched only by replacing 310g of the etching solution, and 690g of the etching solution remaining in the etching bath was reused effectively. Even when compared with the total amount of the etching liquid, the amount of the etching liquid used can be reduced to about 31%, and the addition to the ambient environment can be reduced.
Example 2
Etching was performed in the same manner as in example 1 except that the amount of aluminum treated in example 1 was 0.5g, and the etching rate of the etching solution at the time of etching termination was reduced to 2200 Å/min (about 96.5% of the etching initiation time) at the time of etching termination when the amount of aluminum dissolved by etching reached 0.5 g.
After the etching was terminated, the composition of the etching solution was analyzed in the same manner as in example 1, and as a result, nitric acid was 5.1%, phosphoric acid was 71.5%, and acetic acid was 3.4% (the concentration of the acid component was 80.4% by weight).
Then, 183g of the etching solution was removed from the etching bath (1), and 183g of a solution containing 5.5 wt% of nitric acid, 75.4 wt% of phosphoric acid, and 3.4 wt% of acetic acid were added thereto, wherein the etching solution in the etching bath 1 had an acid concentration of 5.2 wt% of nitric acid, 73 wt% of phosphoric acid, and 3.4 wt% of acetic acid (acid component concentration: 81.1 wt%), and an etching rate of 2300 Å/min.
Again, the etching was repeated in the same manner using this etching solution. After the etching was terminated, 183g of the etching solution was removed in the same manner as described above, and then if a mixed acid solution of 5.5% nitric acid, 73% phosphoric acid, 3.4% acetic acid, and the balance water was added, the etching rate was again restored to the value at the start of etching.
Comparative example 1
The etching solution was adjusted in the same manner as in example 1 except that the etching solution was not removed and a new solution such as nitric acid or phosphoric acid was not added at all, and etching was performed by etching a total of 2g of aluminum, and the etching rate of the etching solution at the time of termination of etching was lowered to 1960 Å/min, which is about 85% of the start of etching, and the acid corresponding concentration was 78.6 wt%.
Example 3
An etching solution was prepared which was composed of a mixed acid solution (the balance being water) having a nitric acid concentration of 14.8 wt%, a phosphoric acid concentration of 59.9 wt%, and an acetic acid concentration of 5.0 wt%. Then, the necessary analysis was performed in the following order.
(1) Quantitative analysis of nitric acid
First, 6g of the mixed acid solution was diluted with water to 250 g. An aqueous potassium nitrate solution containing 25mg of nitric acid per 1g was prepared as a reference solution, and the absorbance near 302nm was measured. Water was used as a control. A calibration curve is prepared from the relationship between the reference solution and the absorbance, and the concentration of nitric acid in the mixed acid solution is calculated. The concentration of nitric acid was 14.9 wt%. The nitric acid equivalent was (14.9 (wt%)/100)/0.0631 ═ 2.365 (meq.). Here, 0.0631 represents the amount (g) of nitric acid corresponding to 1ml of 1 mol/l sodium hydroxide. Then, the CV value (coefficient of variation) at this time was 0.3%, and the dispersion of the analysis values was small.
(2) Quantitative analysis of phosphoric acid:
first, 1g of the mixed acid solution was heated in a boiling water bath for 30 minutes or more, and after drying, the entire residue was washed in a 200ml container, and the concentration of phosphoric acid was calculated by neutralization titration with a 1 mol/l aqueous solution of sodium hydroxide. The phosphoric acid concentration was 59.9 wt%. The phosphoric acid equivalent was (59.9 (wt%)/100)/0.04900 ═ 12.224 (meq.). Here, 0.04900 represents the amount (g) of phosphoric acid corresponding to 1ml of 1 mol/liter of sodium hydroxide. The CV value (coefficient of variation) at this time was 0.08%.
(3) Analysis of acetic acid by deduction of nitric acid equivalents and phosphoric acid equivalents from total acid equivalents
First, 1g of the mixed acid solution was diluted with 50ml of water, and the neutralized and titrated with a 1 mol/l aqueous solution of sodium hydroxide, whereby the total acid equivalent in the mixed acid solution was measured. The total acid equivalent is 15.422meq. Then, the acid equivalent of nitric acid and phosphoric acid obtained in the above (1) and (2) was subtracted from the total acid equivalent to obtain the equivalent of acetic acid. The equivalent weight of acetic acid is 15.422- (2.365+12.224) ═ 0.833 (meq.). Then, the acetic acid concentration was calculated from the equivalent of acetic acid. The concentration of acetic acid was 0.833(meq.) × 0.06005 × 100 ═ 5.0 wt%. Here, 0.06005 represents the amount (g) of acetic acid corresponding to 1ml of 1 mol/l sodium hydroxide. The CV value in the measurement of the total acid equivalent was 0.04%.
According to the etching method of the present invention, the life of the conventional etching solution can be prolonged by about 2 times. Meanwhile, in the composition of the etching solution before use, diluent components such as acetic acid are volatile due to the boiling point, and if they are volatile, the concentration of acids other than acetic acid is concentrated. In this sense, the control of the acetic acid concentration requires a separate system, and if the acid and the oxidizing agent are adjusted, the etching rate at the subsequent stage can be maintained at intervals of the initial etching rate, so that stable etching for a long period of time becomes possible. By extending the liquid life by a factor of 2, it is effective because the amount of waste is reduced by half. The phosphoric acid component recovered by the treatment for removing acetic acid and nitric acid may be reused as a fertilizer by neutralization and chlorination.
As described in the above examples, according to the present invention, quantitative analysis of nitric acid, phosphoric acid, and acetic acid in a mixed acid solution can be performed efficiently and with high accuracy by a simple operation.
Claims (22)
1. A method for etching a metal by repeatedly using an etching solution containing nitric acid and phosphoric acid, characterized in that the concentration of the etching solution is adjusted before repeated use on the basis of the measurement result of the concentration corresponding to an acid component specified by the following formula (1):
acid component corresponding concentration (wt%) ═ nitric acid concentration (wt%) × 98/63+ phosphoric acid concentration (wt%) … (1)
(in the above formula, 98 is the molecular weight of phosphoric acid, 63 is the molecular weight of nitric acid).
2. The etching method according to claim 1, wherein nitric acid and/or phosphoric acid is added to the etching solution after etching to adjust the concentration to the same value as the concentration corresponding to the acid component of the etching solution before etching.
3. The etching method according to claim 1 or 2, wherein when the concentration of the metal to be etched existing in the etching solution and ionized by the etching is a (mol%), and the valence number of the ionized metal to be etched is Y, the concentration is adjusted so that the concentration of nitric acid in the etching solution (mol%) is greater than the product of a and Y.
4. The etching method according to claim 1, wherein a part of the etching solution after etching is extracted from the etching step, and then nitric acid and/or phosphoric acid is added to the etching solution remaining in the etching step to adjust the concentration to the same value as the concentration corresponding to the acid component of the etching solution before etching.
5. The etching method according to claim 4, wherein the extraction amount F of the etching solution with respect to 1000g of the etching solution satisfies the following formula (2):
a: 100 (constant)
B: 500 (constant)
F: amount of etching solution drawn out [ g ]
C0: concentration of acid component in etching solution before etching [ wt% ]
C1: the acid component of the etching solution after etching corresponds to the concentration [ wt. ].
6. The etching method according to claim 4, wherein the concentration C (wt%) of the acid component determined from the added nitric acid and phosphoric acid satisfies the following formula (3), and the ratio of phosphoric acid and nitric acid satisfies the following formula (4):
C1+D×(C0-C1)≥C≥C1+E×(C0-C1) …(3)
c0: concentration of acid component in etching solution before etching (wt%)
C1: acid component concentration (wt%) of etching solution after etching
D: 6 (constant)
E: 1 (constant)
Phosphoric acid (wt%): nitric acid (wt%) × 98/63 ═ G: 1 … (4)
G: 1 to 10 (constant).
7. The etching method according to claim 1, wherein the etching solution contains acetic acid.
8. The etching method according to claim 7, wherein the concentration of acetic acid in the etching solution after etching is measured, and acetic acid is added so that the concentration of acetic acid in the etching solution before etching is the same.
9. The etching method according to claim 1, wherein the metal to be etched is aluminum, silver, copper, or an alloy containing any one or more of these metals.
10. The etching method according to claim 1, wherein the phosphoric acid concentration is measured by the following steps (a) and (b):
(a) firstly, drying the etched etching solution to remove nitric acid and acetic acid;
(b) then, the concentration of phosphoric acid was analyzed by neutralization titration, and during this time, the amount 2 times the amount of titration up to the 1 st inflection point of phosphoric acid was regarded as the amount of titration up to the 2 nd inflection point of phosphoric acid, and the concentration of phosphoric acid was calculated.
11. The etching method according to claim 1, wherein the concentration of the nitric acid is measured by ultraviolet absorptiometry.
12. The etching method according to claim 8, wherein the concentration of acetic acid in the etching solution is calculated by subtracting the nitric acid equivalent and the phosphoric acid equivalent from the total acid equivalent.
13. The etching method according to claim 1, wherein the concentration of nitric acid in the etching solution not containing the metal to be etched ionized by etching is determined by an ultraviolet absorptiometry, and the concentration of phosphoric acid is determined by a neutralization titration method after drying the etching solution.
14. An etching method comprising the following steps (I) to (IV):
(I) a step of calculating the concentration of an etching solution containing nitric acid and phosphoric acid, but not containing a metal to be etched ionized by etching, in the acid component corresponding to the following formula (1):
acid component-corresponding concentration (wt%) + phosphoric acid concentration (wt%) + nitric acid concentration (wt%) × 98/63 … (1);
(II) a step of etching a metal using the etching solution;
(III) adjusting the concentration of the acid component in the etching solution used for etching the metal so that the concentration of the acid component is equal to the concentration of the acid component calculated in the step (I);
(IV) a step of etching the metal using the etching solution whose concentration is adjusted in the step (III).
15. The etching method according to claim 14, wherein the steps (III) and (IV) are repeated after the steps (I) to (IV) are completed.
16. An etching apparatus comprising the following steps (I) to (IV):
(I) a step of calculating the concentration of an etching solution containing nitric acid and phosphoric acid, but not containing a metal to be etched ionized by etching, in the acid component corresponding to the following formula (1):
acid component-corresponding concentration (wt%) + phosphoric acid concentration (wt%) + nitric acid concentration (wt%) × 98/63 … (1);
(II) a step of etching a metal using the etching solution;
(III) adjusting the concentration so that the concentration of the etching solution corresponding to the acid component used for etching the metal is equal to the concentration of the etching solution corresponding to the acid component calculated in the step (I);
(IV) a step of etching the metal using the etching solution whose concentration is adjusted in the step (III).
17. A method for quantitatively analyzing an etching solution containing phosphoric acid and an ionized metal to be etched, which is used in a metal etching process, characterized in that the concentration of phosphoric acid is measured by the following steps (a) and (b):
(a) firstly, drying the etched etching solution to remove nitric acid and acetic acid;
(b) then, the concentration of phosphoric acid was analyzed by neutralization titration, and during this time, the amount 2 times the amount of titration up to the 1 st inflection point of phosphoric acid was regarded as the amount of titration up to the 2 nd inflection point of phosphoric acid, and the concentration of phosphoric acid was calculated.
18. The quantitative analysis method according to claim 17, wherein the etching solution contains nitric acid, and the concentration of the nitric acid is determined by ultraviolet absorptiometry.
19. The quantitative analysis method according to claim 17, wherein the etched metal is aluminum, silver, copper, or an alloy containing any one or more of these metals.
20. The quantitative analysis method according to claim 16, wherein the etching solution contains phosphoric acid, nitric acid and acetic acid.
21. A method for quantitatively analyzing an etching solution used in a metal etching process, the etching solution containing nitric acid, phosphoric acid and acetic acid and not containing a metal to be etched ionized by etching, wherein the concentration of nitric acid is determined by an ultraviolet absorptiometry, the concentration of phosphoric acid is determined by a neutralization titration method after drying a mixed acid solution, and the concentration of acetic acid is calculated by subtracting a nitric acid equivalent and a phosphoric acid equivalent from a total acid equivalent.
22. A method for recovering phosphoric acid from an etching solution used for metal etching, characterized in that the etching solution used for metal etching, which contains nitric acid and phosphoric acid, is dried, and then the metal to be etched ionized in the etching solution is removed.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001104783 | 2001-04-03 | ||
| JP2001104783A JP4686885B2 (en) | 2001-04-03 | 2001-04-03 | Quantitative analysis method of mixed acid solution used in metal etching process |
| JP2001241312A JP2003049285A (en) | 2001-08-08 | 2001-08-08 | Etching method, quantitative analysis method for etching solution and method for recovering phosphoric acid from etching solution |
| JP2001241312 | 2001-08-08 |
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| Publication Number | Publication Date |
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| CN1379288A true CN1379288A (en) | 2002-11-13 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN02108573A Pending CN1379288A (en) | 2001-04-03 | 2002-04-02 | Etching method and quantitative analysis method of etching liquid |
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| KR (1) | KR20020079414A (en) |
| CN (1) | CN1379288A (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101192507B (en) * | 2006-11-29 | 2011-07-20 | 上海华虹Nec电子有限公司 | Phosphoric acid solution exchanging method in semiconductor integrated circuit production |
| CN102534621A (en) * | 2012-02-21 | 2012-07-04 | 上海正帆科技有限公司 | Method for treating acidic etching solution |
| CN102621273A (en) * | 2012-04-17 | 2012-08-01 | 昊诚光电（太仓）有限公司 | Method for detecting mixed acid solution in manufacturing process of polycrystalline silicon solar cell |
| CN102967686A (en) * | 2012-11-14 | 2013-03-13 | 杭州格林达化学有限公司 | Method for testing and controlling acid concentrations in ITO (indium tin oxide) etching liquid on line |
| WO2014023045A1 (en) * | 2012-08-10 | 2014-02-13 | 深圳市华星光电技术有限公司 | Potentiometric titration method of mixed acid concentration in aluminum etching liquid |
| CN103604856A (en) * | 2013-11-15 | 2014-02-26 | 深圳市华星光电技术有限公司 | Potentiometric titration method of acid mixture solution |
| US8945934B2 (en) | 2012-08-10 | 2015-02-03 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Potentiometric titration method for measuring concentration of acid mixture of aluminum etchant |
| CN105181888A (en) * | 2015-09-01 | 2015-12-23 | 信利（惠州）智能显示有限公司 | Titration apparatus for etching solution concentration monitoring system |
| CN108427442A (en) * | 2017-02-12 | 2018-08-21 | 苏州耀群净化科技有限公司 | A kind of etchant concentration method of adjustment |
| CN105866049B (en) * | 2016-05-20 | 2019-04-26 | 深圳市华星光电技术有限公司 | Etching solution acid concentration measuring equipment |
-
2002
- 2002-04-02 CN CN02108573A patent/CN1379288A/en active Pending
- 2002-04-02 KR KR1020020017977A patent/KR20020079414A/en not_active Application Discontinuation
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101192507B (en) * | 2006-11-29 | 2011-07-20 | 上海华虹Nec电子有限公司 | Phosphoric acid solution exchanging method in semiconductor integrated circuit production |
| CN102534621A (en) * | 2012-02-21 | 2012-07-04 | 上海正帆科技有限公司 | Method for treating acidic etching solution |
| CN102621273A (en) * | 2012-04-17 | 2012-08-01 | 昊诚光电（太仓）有限公司 | Method for detecting mixed acid solution in manufacturing process of polycrystalline silicon solar cell |
| CN102621273B (en) * | 2012-04-17 | 2014-04-02 | 昊诚光电（太仓）有限公司 | Method for detecting mixed acid solution in manufacturing process of polycrystalline silicon solar cell |
| WO2014023045A1 (en) * | 2012-08-10 | 2014-02-13 | 深圳市华星光电技术有限公司 | Potentiometric titration method of mixed acid concentration in aluminum etching liquid |
| US8945934B2 (en) | 2012-08-10 | 2015-02-03 | Shenzhen China Star Optoelectronics Technology Co., Ltd. | Potentiometric titration method for measuring concentration of acid mixture of aluminum etchant |
| CN102967686A (en) * | 2012-11-14 | 2013-03-13 | 杭州格林达化学有限公司 | Method for testing and controlling acid concentrations in ITO (indium tin oxide) etching liquid on line |
| CN103604856A (en) * | 2013-11-15 | 2014-02-26 | 深圳市华星光电技术有限公司 | Potentiometric titration method of acid mixture solution |
| CN103604856B (en) * | 2013-11-15 | 2015-11-25 | 深圳市华星光电技术有限公司 | A kind of potentiometric titration method of mixed acid solution |
| CN105181888A (en) * | 2015-09-01 | 2015-12-23 | 信利（惠州）智能显示有限公司 | Titration apparatus for etching solution concentration monitoring system |
| CN105866049B (en) * | 2016-05-20 | 2019-04-26 | 深圳市华星光电技术有限公司 | Etching solution acid concentration measuring equipment |
| CN108427442A (en) * | 2017-02-12 | 2018-08-21 | 苏州耀群净化科技有限公司 | A kind of etchant concentration method of adjustment |
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| KR20020079414A (en) | 2002-10-19 |
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