JP3163058B2 - Immersion type substrate processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an immersion type substrate processing apparatus for performing surface treatment by immersing a substrate in a processing solution obtained by mixing a chemical solution and pure water at a required ratio, and in particular, to the transmitted light intensity of a fluid (sample The present invention relates to a technique of measuring a transmitted light intensity (a transmitted light intensity) and a reference transmitted light intensity (a reference transmitted light intensity), and adjusting the density based on a ratio of these.

[0002]

2. Description of the Related Art In a conventional apparatus of this type, a processing solution obtained by mixing a chemical solution and pure water at a required ratio is stored in a processing tank in advance, and a substrate is immersed in the processing tank to perform surface treatment. Has become. The concentration of the processing solution is adjusted by appropriately adding a chemical solution or pure water.

[0003]

However, the prior art having such a structure has the following problems. That is, when performing a plurality of treatments, if the number of substrates to be immersed is different each time, or if the surface state of the substrate is various and the degree of reaction with the treatment liquid is different, the concentration of the treatment liquid is required. It cannot be easily maintained at the value. Therefore, there is a problem that the quality of processing in the immersion type substrate processing apparatus is not stable.

[0004] The present invention has been made in view of such circumstances, and by adjusting the supply amount of a chemical solution or pure water based on the result of concentration measurement to maintain the concentration of the processing solution at a required value. An object of the present invention is to provide an immersion-type substrate processing apparatus capable of immersing a substrate with a stable finish.

[0005]

The present invention has the following configuration in order to achieve the above object. That is, the immersion type substrate processing apparatus according to claim 1, wherein the immersion type substrate processing apparatus performs surface treatment by immersing a substrate in a processing liquid obtained by mixing a chemical solution and pure water at a required ratio, wherein the processing liquid A processing tank for immersing the substrate, an overflow section for storing the processing liquid overflowing from the processing tank, a processing liquid supply pipe for circulating the processing liquid remaining in the overflow section to the processing tank, A pure water supply pipe for supplying pure water to the processing liquid circulating from the processing tank through the overflow section to the processing tank via the processing liquid supply pipe, and a flow rate of pure water supplied from the pure water supply pipe. pure and water flow rate adjusting means, and the chemical supply pipe for supplying a chemical liquid to the overflow portion, and the chemical flow rate adjusting means for adjusting the flow rate of the chemical liquid supplied from the chemical liquid supply pipe, is disposed in the processing liquid supply pipe for A processing solution concentration measuring unit that measures the concentration of the processing solution based on the transmitted light intensity of the processing solution; and the pure water flow rate adjusting unit and the chemical solution based on the processing solution concentration measured by the processing solution concentration measuring unit. Control means for controlling the flow rate adjusting means.

Further, the immersion type substrate processing apparatus according to the second aspect is the immersion type substrate processing apparatus according to the first aspect.
The processing liquid supply pipe includes a processing liquid heating unit that heats the circulating processing liquid, and a temperature measurement unit that measures the temperature of the circulating processing liquid.The processing liquid concentration measurement unit includes:
After confirming that the temperature of the treatment liquid has reached a predetermined temperature by the temperature measuring means, the concentration of the treatment liquid is measured.

[0007]

The operation of the first aspect of the invention is as follows. Pure water is supplied to the processing liquid supply pipe via a pure water supply pipe, and a chemical liquid is supplied via a chemical liquid supply pipe to generate a processing liquid. The concentration of the treatment liquid is adjusted by adjusting the supply amounts of the pure water and the chemical liquid by the pure water flow rate adjusting means and the chemical liquid flow rate adjusting means. The generated processing liquid is supplied to a processing tank, and a substrate in the processing tank is subjected to a surface treatment.
The processing liquid overflowing the processing tank circulates through the overflow section through the processing liquid supply pipe, and returns to the processing tank again. Although the processing liquid circulates in this manner, the concentration of the processing liquid may fluctuate as many substrates are processed. The concentration of the processing liquid flowing through the processing liquid supply pipe is measured by the processing liquid concentration measuring means based on the transmitted light intensity, and based on the concentration of the processing liquid measured by the processing liquid concentration measuring means, the control means The flow rate adjusting means and the chemical liquid flow rate adjusting means are controlled to adjust the concentration of the processing liquid to a required value.

According to the second aspect of the present invention, the processing liquid supply pipe is provided with the processing liquid heating means and the temperature measuring means, and is controlled so that the temperature of the processing liquid becomes a predetermined temperature. Generally, since the extinction coefficient that affects the transmitted light intensity has a temperature dependency, the measurement can be performed accurately when the processing solution concentration measuring means measures the temperature of the processing solution at a predetermined temperature.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of an immersion type substrate processing apparatus according to one embodiment of the present invention. In this apparatus, for example, in order to clean a substrate such as a semiconductor wafer, a chemical solution and pure water according to the purpose are mixed and adjusted at a predetermined ratio, and the substrate is added to a processing liquid (sample fluid) having a predetermined concentration. The substrate is treated by immersion.

In the drawing, reference numeral 1 denotes an overflow type processing tank. The processing tank 1 is a processing tank body 1 in which a wafer carrier (not shown) containing a plurality of semiconductor wafers is immersed.
_1, and a overflow part 1 ₂ which for retention of processing solution overflowing from the processing tank body 1 ₁ is disposed around it. The treatment tank body 1 _1, pure water by the pure water supply pipe 3 is supplied at a predetermined pressure, the supply amount is designed to be regulated by the flow control valve V _1. Further, the overflow portion 1 ₂ is chemical through the flow control valve V ₂ and the chemical supply pipe 7 for regulating the flow rate of the chemical liquid from the chemical liquid tank 5 are supplied. In addition,
Flow control valve V ₁ was equivalent to the pure water flow rate adjusting means in the present invention, the flow control valve V ₂ corresponds to the chemical flow rate adjusting means.

Furthermore the overflow part 1 ₂ is one end disposed in the processing liquid supply pipe 9 for circulating the processing liquid held up, the pump 11 for this is for circulating the processing solution, A heater 13 for heating the circulating processing liquid to a predetermined temperature, a temperature sensor 15 for measuring the temperature of the processing liquid, and a filter 17 for removing particles and the like in the circulating processing liquid. a sample cell 19 having a predetermined optical path length d is disposed, the other end is connected to the bottom of the processing tank body 1 _1. Note that the heater 13 corresponds to a processing liquid heating unit in the present invention, and the temperature sensor 15 corresponds to a temperature measuring unit.

Light from a light source 21 such as a halogen lamp is branched into two directions by a light branching unit 22 in the sample cell 19, and one of them is irradiated. The other is irradiated to a reference cell 23 having an optical path length d filled with pure water. One of the light transmitted through the sample cell 19 and the reference cell 23 is selectively irradiated on the photodetector 25 by the optical path switching unit 24. This reference cell 23
May be any as long as it has a constant extinction coefficient. For example, an optical filter having a predetermined extinction coefficient may be used instead. Further, the light source 21, the optical branching unit 22, the sample cell 19, the reference cell 23, the optical path switching unit 24, and the photodetector 25 are described.
Constitutes the transmitted light intensity measuring optical unit 20.

A signal corresponding to the transmitted light intensity detected by the light detector 25 is given to a density controller 30. The density control unit 30 is roughly classified into a transmitted light intensity measurement unit 31, a temperature control unit 32, an optical path switching control unit 33, a density calculation unit 34, a feedback control unit 35, and a supply amount control unit 36 in terms of function. The transmitted light intensity measuring optical unit 20, the transmitted light intensity measuring unit 31, and the concentration calculating unit 34 correspond to a processing liquid concentration measuring unit in the present invention, and include a feedback control unit 35, a supply amount controlling unit 36, Corresponds to control means.

The transmitted light intensity measuring section 31 includes an optical path switching section 24
Synchronously irradiates the photodetector 25 with the transmitted light of the sample cell 19 and the reference cell 23 alternately.
The signal corresponding to the transmitted light intensity from the sample is measured as the sample transmitted light intensity and the reference transmitted light intensity, respectively.

The density calculating section 34 includes a transmitted light intensity measuring section 31.
Calculates the concentration of the treatment liquid based on the measured sample transmitted light intensity and the reference transmitted light intensity. The calculation of the density is performed by the following equation. This equation is derived from Lambert-Beer's law as is well known. The sample transmitted light intensity is I _S , the reference transmitted light intensity is I _R , the ratio (transmittance) of these is T, the extinction coefficient of the treatment liquid is α, and the optical path length of the sample cell (= optical path length of the reference cell) is d. Concentration c [%] =-1 / α · d · ln (I _S / I _R ) = − 1 / α · d · ln (T) (1)

The feedback control section 35 stores a target density c _o preset by an input means (not shown), compares the target density c _o with the density c calculated by the density calculation section 34, and performs control according to the deviation. The signal is output to the supply control unit 36. The supply amount control unit 36 controls the flow control valve V of the pure water supply pipe 3 in accordance with a signal from the feedback control unit 35.
₁ or by adjusting the flow control valve V ₂ of the chemical liquid tank to adjust the concentration of the treating solution in the treating layer 1. By repeating this, the concentration of the processing liquid is adjusted so that the concentration c of the processing liquid coincides with the target concentration c ₀ .

Referring now to FIG. FIG. 2 is a diagram showing a schematic configuration of the transmitted light intensity measuring optical unit 20.

The irradiation light from the light source 21 is converted into parallel light by a collimating lens
a. One of the irradiated light condensed by the condenser lens 22a is incident to the optical fiber 22b _1, and the other is incident on the optical fiber 22b _2. Light emitted from the end of the optical fiber 22b ₁ is collimated by the collimator lens 19a, and is incident on the sample cell 19. The light transmitted through the sample cell 19 is condensed by the condenser lens 19b and is incident on the optical fiber 19c. The transmitted light emitted from the optical fiber 19c is collimated by the collimator lens 19d.

The other irradiated light condensed by the condenser lens 22a is incident to the optical fiber 22b _2, reference is collimated by the collimator lens 23a cells 23
Is irradiated. The light transmitted through the reference cell 23 is condensed by the condenser lens 23b and is incident on the optical fiber 23c. The light emitted from the optical fiber 23c is collimated by the collimator lens 23d.

The light transmitted through the sample cell 19 is reflected by a reflecting mirror 19e disposed at a position facing the collimating lens 19d.
The direction of the light is changed by 90 ° by the reflection of light, and the light is incident on the prism P. The light transmitted through the reference cell 23 is incident on the prism P with its direction changed by 90 ° by a reflection mirror 23e disposed at a position facing the collimator lens 23d. The light reflected by the prism P passes through the condenser lens 2
The light is condensed by 5a and is incident on the photodetector 25.

A light selection shutter 24 is provided between the collimating lenses 19d and 23d and the reflection mirrors 19e and 23e.
a is provided. The light selective shutter 24a comprises a plate-like shape, and a light-shielding portion 24a ₁ and the opening portion 24a ₂ Metropolitan is a light transmissive portion. The light selection shutter 24a alternately reflects light transmitted through the sample cell 19 and the reference cell 23 with the reflection mirror 19e and the reflection mirror 23.
e is operated by the air cylinder 24b so as to irradiate e. The operation axis of the air cylinder 24b is contracted / extended by the optical path switching control unit 33 of the density control unit 30.

In the configuration of the optical path switching unit 24, the light transmitted through the sample cell 19 is incident on the photodetector 25 by the contraction of the air cylinder 24b, and the air cylinder 24b
The light transmitted through the reference cell 23 is made incident on the photodetector 25 by the extension operation of.

Next, the density adjustment processing in the substrate processing apparatus having the above-described configuration will be described with reference to FIG. FIG. 3 is a timing chart showing the operation timing of the optical path switching control unit 33 and the measurement timing of the transmitted light intensity measurement unit 31.

[0024] First, the target concentration c ₀ of the treatment liquid is previously input through an input means (not shown), the target concentration c ₀ is
It is stored in the feedback control unit 35. Then, the supply amount control unit 36 controls the pure water flow control valve V ₁ and the chemical flow control valve V _2, and supplies the chemical liquid and the pure water to the treatment tank 1 at a ratio of approximately a predetermined concentration c. . And after the treatment liquid has accumulated up to the overflow part 1 _2, while circulating the processing solution to the processing liquid supply pipe 9 by a pump 11, temperature control unit 3
2 adjusts the temperature of the processing liquid so as to reach a predetermined temperature based on the detection signal from the temperature sensor 15.

After the transmitted light intensity measuring section 31 confirms that the temperature of the processing liquid has reached a predetermined temperature, the optical path switching control section 3
3 is instructed to drive the light selection shutter 24. Optical path switching control unit 33 performs a contraction operation of the air cylinder 24b for a predetermined time t _1, perform decompression operation for a predetermined time t _2. Thus, the transmitted light of t ₁ hour only sample cell 19 is irradiated on the optical detector 25, transmitted light t ₂ hours by reference cell 23 is irradiated on the optical detector 25. The predetermined times t ₁ and t
₂ is, for example, one second.

The reason why the transmitted light intensity is measured after confirming that the temperature of the processing liquid has reached the predetermined temperature is to accurately measure the transmitted light intensity. In other words, the transmitted light intensity is displaced by the extinction coefficient, which is a constant indicating the rate at which the medium absorbs light, but since this extinction coefficient has a temperature dependence, even if the transmitted light intensity is measured at various temperatures, It is not possible to accurately control the density based on this. Therefore,
The transmitted light intensity is measured after the temperature of the treatment liquid reaches a certain temperature, so that the transmitted light intensity according to the concentration can be accurately measured.

The transmitted light intensity measurement unit 31 takes in the output signal of the photodetector 25 at an appropriate timing in the above t ₁ hour, to measure this as a sample transmitted light intensity I _s1. Further, at an appropriate timing within the time t ₂ , the photodetector 31
_{Is taken} in and measured as the reference transmitted light intensity I _R1 . As described above, the irradiation light from one light source 21 is branched and one light detector 25 is irradiated with the transmitted light of the sample cell 19 and the reference cell 23. Even if there is a change in sensitivity, the influence affects both the reference transmitted light intensity and the sample transmitted light intensity. Therefore, these ratios are hardly affected by fluctuations, and the concentration of the processing solution can be accurately adjusted based on these ratios.

The transmitted light intensity measuring section 31 is provided for measuring the transmitted light intensity of the sample.
I_SAnd reference transmitted light intensity I_RMeasurement is repeated
These sequentially measured transmitted light intensities are processed as follows.
First, the first sample transmitted light intensity I_S1And reference transmitted light
Strength I_R1Ratio T with₁₁(= I_S1/ I_R1), The second
Sample transmitted light intensity I_S2And the first reference transmitted light intensity I _R1
Ratio T with_{twenty one}(= I_S2/ I_R1) Is calculated and their average value T
_AV1Ask for. Next, the second sample transmitted light intensity I_S2And the second
First reference transmitted light intensity I_R1Ratio T with_{twenty one}And each second
Eye sample transmitted light intensity I_S2And reference transmitted light intensity I_R2Ratio T with
_{twenty two}(= I_S2/ I _R2) And the average value T_AV2Ask for. this
Go sequentially to find the moving average. This moving average T_AVnBut
Each time it is calculated, this value is sent to the density calculator 34, where
Moving average T_AVnIs substituted for T in the above equation (1) and processing is performed.
The concentration c of the liquid is calculated.

As described above, when compared with the ideal state where the sample transmitted light intensity and the reference transmitted light intensity are measured simultaneously, "small",
By calculating a moving average of the ratio between the sample transmitted light intensity and the reference transmitted light intensity in a relationship of repeating “large”, the influence of the sensitivity fluctuation of the photodetector 25 is suppressed, and the accuracy and the ideal state are improved. It is possible to determine the ratio between the near sample transmitted light intensity I _S and the reference transmitted light intensity I _R.

The feedback controller 35 outputs a control signal to the supply controller 36 in accordance with the difference between the preset target concentration c ₀ and the concentration c of the processing liquid calculated by the concentration calculator 34. Supply amount control unit 36, the pure water supply pipe 3 of the flow control valve V ₁ or the flow control valve V ₂ of the liquid tank and to supply the pure water or chemical liquid adjusted according to the control signal, the concentration of the processing solution adjust.

As described above, the supply amount control unit 36 adjusts the flow control valve V ₁ or the flow control valve V ₂ to supply pure water or a chemical solution in accordance with the concentration deviation of the processing liquid, thereby adjusting the concentration of the processing liquid. Therefore, the concentration of the processing solution can be adjusted to a required value. Accordingly, the processing solution concentration can be maintained at a required value, and the substrate can be stably processed with good quality.

It is necessary to measure the transmitted light intensity in a plurality of different wavelength bands depending on the processing liquid. For example, in a processing solution composed of ammonia and hydrogen peroxide, the rate of change in transmitted light intensity due to the concentration of ammonia in the infrared wavelength band is large,
In the ultraviolet wavelength band, the rate of change in transmitted light intensity due to the concentration of hydrogen peroxide is large. Therefore, in order to measure the transmitted light intensity of such a processing solution and control the concentration based on the measured intensity, it is preferable to configure the photodetector 25 as shown in FIG.

That is, the sample cell 19 and the reference cell 2
The light transmitted through 3 is applied to the prism P. Then, the light is separated by the dichroic mirror H into ultraviolet light UV and light in the visible / infrared wavelength range IR. Furthermore these light, the ultraviolet band-pass filters F ₁ and the infrared band-pass filter F ₂ is selected measurement wavelength of ultraviolet light and infrared light, respectively, through respective condenser lenses 25a ₁ and the condenser lens 25a ₂ , An ultraviolet light detector 25 ₁ having a spectral sensitivity to a wavelength selected by a bandpass filter.
(E.g., composed of a semiconductor element made of GaP or the like or an ultraviolet phototube) and an infrared light detector 25 ₂ having a similar spectral sensitivity (e.g., composed of a semiconductor element made of PbS, GaAsP, or the like) Is done.

In the case of such a configuration, the sample transmitted light intensities I _{S (UV)} , I _{S (UV)} and I
_{S (IR)} and reference transmitted light intensities _{IR (UV)} and _{IR (IR)} are measured. Then, as described above, the ratio T _{11 (UV)} between the first sample transmitted light intensity I _{S1 (UV)} and the reference transmitted light intensity I _{R1 (UV)} is obtained.
(= I _{S1 (UV)} / I _{R1 (UV) )} and the ratio T between the first sample transmitted light intensity I _{S1 (IR)} and the reference transmitted light intensity I _{R1 (IR).
The} ratio between ultraviolet light and infrared light is calculated as in _{11 (IR)} (= I _{S1 (IR)} / I _{R1 (IR)} ). Hereinafter, similarly, the ratio between the ultraviolet light and the infrared light may be sequentially obtained.

The optical path switching section 24 described above may be configured as shown in FIG. That is, the place of the light selective shutter 24a, the light blocking portion 24a ₁ and obtained by forming into a disk shape and a cut-out portion 24a ₂ is a light transmitting part at a predetermined ratio of light selected disc 24a ', instead of the air cylinder 24b Motor 24 for rotating the light selection disk 24a 'at a predetermined speed
b ′. For example, the optical path switching control unit 3
3 controls the rotation of the motor 24b 'as shown in FIG. According to this, the transmitted light of the sample cell 19 and the reference cell 23
Are alternately applied to the photodetector 23 for the time t ₁ , and the irradiation interval is controlled to be the time t ₂ . Then, the transmitted light intensity I _S and the reference transmitted light intensity I _R are measured by the transmitted light intensity measurement unit 31 in synchronization with each irradiation timing.
With such a configuration, a time period (t ₂ −t ₁ ) during which light is not irradiated on the photodetector 25 occurs. Therefore,
The same effect as the provision of a chopping sector or the like for intermittently irradiating light to suppress the heat rise of the photodetector 25 can be obtained, and the transmitted light intensity can be measured more stably. .

The optical path switching section 24 includes an optical path branching section 22.
May be arranged at any position as long as it is between the photodetector 25 and. For example, on the light source 21 side, the collimating lens 2
It may be arranged between 1a and the condenser lens 22a (see FIG. 2). In this case, the optical fibers 19c, 2
3c is a so-called multi-core bundle type and two-branch type optical fiber in which the core and the clad of both optical fibers are welded at one end so that both lights are emitted from one end. Is preferred. According to this configuration, the light transmitted through the sample cell 19 and the reference cell 23 is converged by this optical fiber, so that one light detector 2
5 does not require a configuration for converging both transmitted lights.

[0037]

As apparent from the above description, according to the first aspect of the present invention, the control means controls the pure water flow rate adjusting means and the chemical solution flow rate adjusting means based on the concentration measured by the processing solution concentration measuring means. Since the concentration of the processing liquid is adjusted to a required value by controlling the means, the processing liquid concentration can be maintained at the required value. Therefore, the substrate can be stably processed with good quality.

According to the second aspect of the present invention, since the measurement is performed after the temperature of the processing solution reaches a predetermined temperature, the measurement can be performed accurately, and the concentration can be adjusted accurately.
Therefore, the processing can be performed on the substrate more accurately.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of an immersion type substrate processing apparatus according to an embodiment.

FIG. 2 is a schematic configuration diagram of a transmitted light intensity measuring optical unit.

FIG. 3 is a timing chart showing the operation of an optical path switching control unit and the measurement timing of a transmitted light intensity measurement unit.

FIG. 4 is a diagram showing a modification of the photodetector.

FIG. 5 is a schematic configuration diagram showing a modified example of the optical path switching unit.

FIG. 6 is a timing chart showing the operation of the optical path switching control unit and the measurement timing of the transmitted light intensity measurement unit.

[Explanation of symbols]

1 ... treatment tank 1 ₁ ... treatment tank main body 1 ₂ ... overflow portion 3 ... pure water supply pipe 7 ... chemical supply pipe 9 ... treatment liquid supply pipe V ₁ ... flow control valve V ₂ ... flow control valve 13 ... Heater 15 ... Temperature Sensor 19: Sample cell 20: Optical unit for transmitted light intensity measurement 21: Light source 22: Optical branching unit 23: Reference cell 24: Optical path switching unit 25: Photodetector 30: Concentration control unit 31: Transmitted light intensity measurement unit 32: Temperature controller 33… Optical path switching controller 34… Concentration calculator 35… Feedback controller 36… Supply amount controller

Continuation of the front page (56) References JP-A-61-281532 (JP, A) JP-A-6-132270 (JP, A) JP-A-5-129274 (JP, A) JP-A-7-326600 (JP, A) , A) Japanese Utility Model Application Hei 5-53241 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304 B08B 3/00-3/04

Claims (2)

(57) [Claims] 1. An immersion type substrate processing apparatus for performing surface treatment by immersing a substrate in a processing solution obtained by mixing a chemical solution and pure water at a required ratio, wherein the substrate is immersed in the processing solution. A processing tank, an overflow section for storing the processing liquid overflowing from the processing tank, a processing liquid supply pipe for circulating the processing liquid remaining in the overflow section to the processing tank, and the processing from the processing tank via the overflow section. A pure water supply pipe for supplying pure water to the processing liquid circulating to the processing tank by a liquid supply pipe, and a pure water flow rate adjusting unit for adjusting a flow rate of the pure water supplied from the pure water supply pipe; a chemical supply pipe for supplying a chemical liquid to the overflow portion, and the chemical flow rate adjusting means for adjusting the flow rate of the chemical liquid supplied from the chemical liquid supply pipe is disposed in the processing liquid supply pipe, the treatment liquid transmitted light A processing solution concentration measuring unit that measures the concentration of the processing solution based on the degree, and controls the pure water flow rate adjusting unit and the chemical solution flow rate adjusting unit based on the processing solution concentration measured by the processing solution concentration measuring unit. An immersion type substrate processing apparatus, comprising: a control unit. 2. The immersion type substrate processing apparatus according to claim 1, wherein the processing liquid supply pipe measures a processing liquid heating means for heating the circulating processing liquid, and measures a temperature of the circulating processing liquid. A temperature measuring means for measuring the concentration of the processing liquid after confirming that the processing liquid has reached a predetermined temperature by the temperature measuring means. Immersion type substrate processing equipment.