JP3297650B2 - Semiconductor 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 a semiconductor processing apparatus having a processing section for performing processing by receiving a plurality of types of processing liquids.
The present invention relates to a semiconductor processing apparatus capable of measuring the concentration of a plurality of types of processing liquids.

[0002]

2. Description of the Related Art In this semiconductor processing apparatus, ammonia (NH ₃ ), hydrogen peroxide (H ₂ O ₂ ) and ammonia (H ₂ O ₂ ) as chemicals are supplied to a cleaning liquid supply pipe connected to a lower part of a processing tank for cleaning a semiconductor wafer. Hydrofluoric acid (HF), hydrochloric acid (HCl), etc., and pure water, which is water from which ions have been removed, are mixed and prepared at a predetermined ratio and supplied as a cleaning liquid. An optical part for transmitted light measurement for irradiating the cleaning liquid flowing in the pipe with light and measuring the intensity of transmitted light at a predetermined wavelength (transmitted light intensity) is provided in the middle of the cleaning liquid supply pipe. The optical unit includes a light source, a flow cell including a light transmitting unit (hereinafter, referred to as a cell unit) having a gap for irradiating and transmitting the light of the light source to the cleaning liquid in the tube, and a light transmitted through the cell unit. And a photodetector comprising a photodetector for detecting the intensity of the light.

The following method is used to measure the concentration of the cleaning liquid in the semiconductor cleaning apparatus having the above configuration.

The first method is to measure the light intensity of a predetermined wavelength incident on the flow cell (incident light intensity I _0), the transmitted light intensity I _m of the cleaning liquid flowing through the cleaning liquid supply pipe, Lambert -
The concentration of the cleaning solution is calculated based on Beer's law (Lambert-Beer's Law). Specifically, substituting the transmitted light intensity I _m of the measured incident light intensity I ₀ and the washing solution in the following equation (1). Here, the symbol k in the formula is the extinction coefficient (/ mm ·) specific to each cleaning solution, which represents the degree to which the cleaning solution absorbs light.
%), Symbol d is the length of the cell portion provided in the flow cell for measuring the intensity of light transmitted through the fluid, that is, the optical path length of transmitted light (mm), and symbol c is the concentration (%) of the cleaning liquid. . c = −1 / kd · ln (I _m / I ₀ ) (1)

[0005] The second method, when not cleaning a semiconductor wafer in semiconductor cleaning device, measured in advance transmitted light intensity I _C of the pure water flowing through the cleaning liquid supply pipe. Then, when you are washing the semiconductor wafer, measuring the transmitted light intensity I _m of the cleaning liquid flowing through the cleaning liquid supply pipe, Lambert - based on Beer's law, i.e., the transmitted light intensity I of pure water measured
By substituting the transmitted light intensity I _{m C} and the cleaning solution to the following equation (2) to calculate the concentration of the cleaning liquid. c = −1 / k′d · ln (I _m / I _c ) (2) where k ′ is a value when light passes through pure water in cell portions having the same optical path length. It is the extinction coefficient specific to each washing solution defined for the light intensity.

[0006]

However, the conventional apparatus for measuring the concentration by the above-described method has the following problems. Regardless of whether the concentration is measured by the first method or the second method, the extinction coefficient (the extinction coefficient k, which represents the degree to which the washing liquid absorbs light in the first method) In the second method, the extinction coefficient k ′) unique to each cleaning solution defined with respect to the light intensity when passing through pure water with the same optical path length is different. Since a dedicated concentration measuring device is provided for the cleaning liquid, the number of parts increases, which is a factor of increasing the price of the device.

The present invention has been made in view of such circumstances, and measures the concentrations of a plurality of types of processing solutions in a semiconductor processing apparatus that performs processing by supplying a plurality of types of processing solutions. In addition, an object of the present invention is to provide a semiconductor processing apparatus capable of reducing the number of parts and reducing the cost of the apparatus as compared with the related art.

[0008]

The present invention has the following configuration in order to achieve the above object. That is, a chemical liquid supply unit that has a plurality of types of chemical liquid tanks and supplies a plurality of types of processing liquids, a processing unit that performs processing using a plurality of types of processing liquids, and a processing liquid that is supplied from the chemical liquid supply unit. A processing liquid supply pipe that supplies the plurality of types of chemical liquid tanks and the processing liquid supply pipe, and a branch pipe that connects the plurality of types of chemical liquid tanks to the processing liquid supply pipe. A control valve for controlling the opening and closing of a flow path from each of the chemical tanks to the processing liquid supply pipe, a control unit for controlling the operation valve, and a control pipe provided between the branch pipe and the processing unit. , A transmitted light measurement optical unit for detecting the light intensity transmitted through the processing solution, and a calibration curve for the transmitted light intensity associated with the absorption coefficient specific to each processing solution or the concentration of the processing solution specific to each processing solution. The data is stored and provided by the control unit. From the extinction coefficient or the calibration curve data corresponding to the processing liquid flowing through the processing liquid supply pipe, based on the control information of the operation valve, the processing pipe is set based on the transmitted light intensity detected by the transmitted light measuring optical unit. A semiconductor processing apparatus comprising: a concentration calculating unit that obtains a concentration of a flowing processing liquid.

[0009]

The operation of the present invention is as follows. That is,
When the control unit that controls the operation valve opens an operation valve of a flow path from a required chemical liquid tank among a plurality of types of chemical liquid tanks in the chemical liquid supply unit, the control information of the operation valve given from the control unit Based on the concentration calculator, from the extinction coefficient or the calibration curve data corresponding to the processing liquid flowing through the processing liquid supply pipe, the transmitted light intensity detected by the transmitted light measuring optical unit is used to calculate the processing liquid flowing through the processing pipe. Calculate the concentration. When the control unit that controls the operation valve opens the operation valve of the flow path from the chemical liquid tank that is different from the previous one, the concentration calculation is performed based on the control information of the operation valve that is different from the one provided from the control unit. In the part, from the extinction coefficient or the calibration curve data corresponding to a processing liquid different from the one flowing through the processing liquid supply pipe, the transmitted light intensity detected by the transmitted light measurement optical unit, Calculate the concentration of another processing solution.

[0010]

An embodiment of the present invention will be described below with reference to the drawings.

First, the outline of the semiconductor processing apparatus of the present invention will be described. FIG. 1 is a diagram showing a cleaning step in a semiconductor cleaning apparatus for sequentially cleaning a semiconductor wafer with a plurality of cleaning liquids using a concentration measuring method according to one embodiment of the present invention. In this semiconductor cleaning apparatus, generally, R
Cleaning is performed using a method known as a CA cleaning method,
As an example, the processing is sequentially performed using the following cleaning liquid and time. (1) Rinse with pure water for 10 minutes (2) Ammonia (NH ₃ ) / hydrogen peroxide (H ₂ O ₂ )
10 minutes (3) Pure water rinse 20 minutes (4) Hydrofluoric acid (HF) 5 minutes (5) Pure water rinse 20 minutes (6) Hydrochloric acid (HCl) / hydrogen peroxide (H ₂ O ₂ ) 10
Minutes (7) Rinse with pure water 20 minutes

[0012] In such processing steps, the transmitted light of pure water during pure water rinsing (1), (3), and (5), which is a pre-process of each of the cleaning processes (2), (4), and (6). Intensity I _c (I
_{c1, I c 2, I c3} ) were measured, then measures the transmitted light intensity _{I m (I m1, I m2} , I m3) of each wash. Then, by substituting the transmitted light intensity I of the corresponding cleaning liquid and the transmitted light intensity I _c of each pure water respectively above (2),
The concentrations C ₁ , C ₂ , and C ₃ of each cleaning solution are calculated.

Next, an embodiment of the present invention will be described in detail. FIG. 2 is a diagram showing a schematic configuration of a semiconductor cleaning apparatus according to one embodiment of the present invention.

In the drawing, reference numeral 10 denotes a cleaning liquid supply pipe through which the cleaning liquid flows. Pure water, which is water from which ions have been removed, is supplied at a predetermined pressure to a start end of the cleaning liquid supply pipe 10, and a cleaning processing unit 20 including a processing tank for cleaning a semiconductor wafer with the supplied cleaning liquid is provided at an end. Is arranged.

In the middle of the cleaning liquid supply pipe 10, a chemical liquid supply section 40 for supplying a predetermined amount of a chemical liquid for preparing a cleaning liquid is connected via a branch pipe 30. The chemical solution supply unit 40 includes four chemical solution tanks 41a to 41d, a pump P for pumping the chemical solution in each of the chemical solution tanks, a supply valve for controlling the opening and closing of the branch flow path, and a flow rate control for adjusting the flow rate of the chemical solution. Operation valves 42a to 42d including valves are provided. In this embodiment, as an example, hydrofluoric acid (HF), ammonia (NH ₃ ), hydrogen peroxide (H ₂ O ₂ ), and hydrochloric acid (HCl) are stored in this order in each of the chemical liquid tanks 41a to 41d.

The chemical supply section 40 is controlled by a control section 50. Specifically, the control unit 50 controls each of the operation valves 42a to 42d of the chemical liquid supply unit 40, for example, in order to execute processing in the order shown in FIG. The control unit 50 includes a ROM 51 storing a processing program, a CPU 52 interpreting and executing the program, a RAM 53 used as a work area in the execution process of each processing, a CRT 54 displaying a control state and the like, and capable of bidirectional data transfer. Interface 55 and the like.

The cleaning liquid supply pipe 10 between the cleaning processing section 20 and the branch pipe is provided with a transmitted light measuring optical section 60 for measuring the transmitted light intensity of a fluid (pure water or cleaning liquid). This is because a light source 61 such as a halogen lamp that emits light including the ultraviolet to infrared region, and a cell length d for irradiating and transmitting the light of the light source 61 to the fluid in the cleaning liquid supply pipe 10.
And a light intensity detector 63 for detecting the light intensity of a predetermined wavelength transmitted through the flow cell 62, and the like. To measure the concentration of the cleaning solution,
If necessary, ultraviolet light and / or infrared light included in the light emitted from the light source 61 is used. As the light intensity detector 63, when ultraviolet light is used, a semiconductor element such as GaP or an ultraviolet photoelectric tube having high sensitivity to ultraviolet light is used, and when infrared light is used, infrared light is used. A semiconductor element such as PbS having high sensitivity is used.

The transmitted light intensity detected by the light intensity detector 63 is given to a density calculator 70. The concentration calculation unit 70 determines the type of fluid flowing through the cleaning liquid supply pipe 10 based on the control information of the operation valves 42a to 42d given from the control unit 50, and determines a concentration calculation process according to the corresponding cleaning liquid. At the same time, the concentration of the cleaning liquid to be measured is calculated based on the transmitted light intensity given from the light intensity detector 63. The density calculation unit 70 is a ROM 7 storing a density calculation processing program.
1, a CPU 72 for executing the program, a RAM 73 mainly used as a work area for operations, etc., a CRT 74 for displaying the calculated density and the like, and an interface 7
5 and so on.

Next, the concentration measurement in the above-described semiconductor cleaning apparatus will be described with reference to the flowchart shown in FIG.

In step S1, the control unit 50 acquires operation valve control information of the operation valves 42a to 42d of the chemical liquid supply unit 40.

In step S2, it is determined whether all the operating valves are closed from the operating valve control information obtained in step S1, and if NO, it is determined that one of the cleaning liquids is being used. The processing after step S4 is performed, and if YES, it is determined that only pure water in which no cleaning liquid is used is flowing. In this embodiment,
Since the pure water rinsing step (1) of the pretreatment of the NH ₃ + H ₂ O ₂ washing step (2) is performed for 10 minutes, the state where only the pure water flows continues for 10 minutes.

In step S3, the transmitted light intensity I _{C of} pure water
Is measured. Measurements during the 20 minute deionized water rinse is performed, is repeatedly performed at appropriate periods, the average value of each measured value is stored in the RAM73 of the concentration calculation section 70 as a transmitted light intensity I _C.

Then, the washing step is performed for the next NH._Three+ H_TwoO_Two
When the process proceeds to the cleaning step (2), the concentration calculation unit 70 determines in step S
1 (in this case, the operating valve 42
b, 42c are open and the operating valves 42a, 42d are closed).
Determine the type of cleaning solution currently used. Sand
In step S2, NO (all operating valves are not closed).
) And the process proceeds to step S4, where YES
(The operation valves 42b and 42c are open, and the operation valves 42a and 42d are
(Closed), the NH after step S5 is determined.
_Three+ H_TwoO_TwoMove on to the cleaning solution concentration calculation process.

[0024] In step S5, measuring the transmitted light intensity I _m of NH ₃ + H ₂ O ₂ cleaning solution. Here, similarly to the measurement of the transmitted light intensity of the pure water described above, a predetermined cleaning time (10
During minute) is measured repeatedly transmitted light intensity I _m, the average value is stored in the RAM73 of NH ₃ + H ₂ O ₂ cleaning solution concentration calculator 70 as transmitted light intensity I _m of.

In step S6, the transmitted light intensity I _C of the pure water obtained in step S3 and the N
H ₃ + H ₂ O ₂ using a transmitted light intensity I _m of the cleaning liquid, to calculate the concentration according to the concentration calculating process of NH ₃ + H ₂ O ₂ cleaning solution which is determined in advance. This density calculation processing will be described later.

In step S7, the concentration of the NH ₃ + H ₂ O ₂ cleaning solution obtained in step S6 is displayed on the CRT 74.

In the next pure water rinsing step (3), the transmitted light intensity I _C of the pure water is newly measured by the above-described steps S1 to S3. Then, the next HF cleaning step (4)
Then, the process proceeds from step S1 to S2, S4, and S8. If it is determined that HF cleaning solution is used in step S8, the measured transmitted light intensity I _m of HF cleaning solution in step S9, in the next step S10, the transmitted light intensity of the pure water obtained just before I _C When, using the transmitted light intensity I _m of HF cleaning solution, to calculate the concentration according to the concentration calculating process of HF cleaning solution.

Similarly, in the pure water rinsing step immediately before the predetermined cleaning treatment, the transmitted light intensity of pure water is measured, and the transmitted light intensity and the transmitted light intensity of the cleaning liquid are used to obtain a predetermined concentration. The concentration of the cleaning liquid is calculated according to the calculation processing.

As described above, since the transmitted light intensity of pure water, which is a reference in the concentration calculation process, is measured in the pure water rinsing step immediately before the cleaning step, the transmitted light intensity of pure water is measured. , The time from when the transmitted light intensity of the cleaning liquid to be measured is measured is extremely short. Therefore, the fluctuation of the light amount of the light source during this period is slight, and the concentration of the cleaning liquid can be accurately measured. Further, since the transmitted light intensity of the pure water is measured during the pure water rinsing step, it is not necessary to stop the cleaning device to measure the transmitted light intensity of the pure water.

Next, the processing for calculating the concentration of the cleaning liquid will be briefly described by taking the HF cleaning liquid as an example. Examples of the concentration calculation process include a method of calculating using the above-described concentration calculation formula (2) and a method of obtaining using a calibration curve.

In the above-described concentration measurement of the HF cleaning solution, the concentration calculation formula (2) is used. That is, substituting the transmitted light intensity I _C of the pure water obtained in step S3 when the pure water rinsing step (3), the transmitted light intensity I _m of HF cleaning solution obtained in step S9 to the concentration calculation formula (2) Then, the density c is obtained. At this time, a value specific to the HF solution is set as the absorption coefficient k '.

As to the method for obtaining the concentration using the calibration curve, first, the calibration curve data is prepared as follows. First, a plurality of HF cleaning solutions having different concentrations from pure water are prepared, and the transmitted light intensity of pure water with respect to infrared light and the transmitted light intensity of each HF cleaning solution are measured. Then, the transmitted light intensity ratio T of each HF cleaning liquid to the transmitted light intensity of pure water is calculated, and the transmitted light intensity ratio T is associated with the concentration c of the HF cleaning liquid, and the concentration calculating unit 70.
In the RAM 73. FIG. 4 is a diagram showing the relationship between the transmitted light intensity ratio T and the concentration c as calibration curve data.

[0033] When determining the concentration of HF cleaning solution (Fig. 3 step S10), first, the ratio of the transmitted light intensity Ic of pure water measured in step S3, the transmitted light intensity I _m of HF cleaning liquid measured in step S9 Calculate T1. Then, in the RAM 73 of the density calculator 70, a transmitted light intensity ratio T equal to the ratio T1 is searched to obtain a density c corresponding thereto.

In the above embodiment, the transmitted light intensity of the reference pure water was measured in the pure water rinsing step immediately before the cleaning step using the cleaning liquid to be measured. However, the present invention is not limited to this. The transmitted light intensity of pure water may be measured in a pure water rinsing step immediately after the corresponding cleaning step.

[0035]

As is apparent from the above description, according to the present invention, it is possible to measure the concentrations of a plurality of types of processing solutions in a semiconductor processing apparatus which performs processing by receiving a plurality of types of processing solutions. Based on the control information of the operation valve, the concentration calculator, from the absorption coefficient or the calibration curve data corresponding to the processing liquid flowing through the processing liquid supply pipe, from the transmitted light intensity detected by the transmitted light measurement optical unit, Since the concentration of the processing liquid flowing through the processing pipe is calculated, there is no need for a means for measuring the concentration of the number of processing liquids corresponding to the number of processing liquids, the number of parts is reduced, and the cost of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a process diagram of a semiconductor cleaning process as an example to which the present invention is applied.

FIG. 2 is a view showing a schematic configuration of a semiconductor cleaning apparatus according to one embodiment to which the present invention is applied.

FIG. 3 is a flowchart illustrating a procedure for measuring the concentration of the apparatus according to the embodiment.

FIG. 4 is a schematic diagram of a calibration curve used for concentration measurement.

[Description of Signs] 10 ... Cleaning solution supply pipe 40 ... Chemical solution supply unit 50 ... Control unit 60 ... Transmitted light measurement optical unit 70 ... Concentration calculation unit

Claims (1)

(57) [Claims] A liquid supply unit configured to supply a plurality of types of processing liquids; a processing unit configured to perform processing using the plurality of types of processing liquids; In a semiconductor processing apparatus having a processing liquid supply pipe for supplying to the processing unit, the plurality of types of chemical liquid tanks are connected to the processing liquid supply pipe via the plurality of types of chemical liquid tanks and the processing liquid supply pipe. A branch pipe, an operating valve for controlling opening and closing of a flow path from each chemical tank to the processing liquid supply pipe, for each chemical liquid tank, a control unit for controlling the operation valve, and a branch pipe and the processing unit. And a transmitted light measuring optical unit for detecting the intensity of light transmitted through the processing solution, and the transmitted light intensity corresponding to the absorption coefficient unique to each processing solution or the concentration of the processing solution unique to each processing solution. Calibration curve data for the control unit From the extinction coefficient or the calibration curve data corresponding to the processing liquid flowing through the processing liquid supply pipe, based on the transmitted light intensity detected by the transmitted light measuring optical unit, based on the control information of the operation valve given from A semiconductor processing apparatus, comprising: a concentration calculating unit that obtains a concentration of a processing liquid flowing through a pipe.