JPH09246225A - Silicon wafer processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a waste solution discharged from a cleaning process or etching process and also accurately control the etching rate by providing an etching or cleaning treatment tank and a total residue after evaporation equipment for measuring the amount of total burning residue in a chemical. SOLUTION: An etching or cleaning treatment tank 2 for a silicon wafer 6 containing a chemical 4 including at least hydrofluoric acid and a total residue after evaporation equipment 10 for measuring the amount of the total residue after evaporation in the chemical 4 are provided. For example, the total residue meter 10 causes evaporation by spraying sample water and contacting it to heated air, by which the evaporation residue in the sample water is turned into fine particles and these are measured with a gas phase fine particle counter. Then, the measured value of the total residue after evaporation equipment 10 is sent to a control section 12; when this measured value exceeds a predetermined concentration, a control signal is sent out to a chemical supplementing valve 14 and opening/closing of the chemical supplementing valve 14 is controlled; and a chemical such as a dilute hydrofluoric acid is supplied to the treatment tank 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer processing apparatus such as a silicon wafer cleaning apparatus and an etching apparatus used for manufacturing semiconductors, particularly silicon semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, a silicon wafer processing apparatus is an apparatus for cleaning the surface of a silicon wafer, dissolving a silicon oxide film, or etching a silicon wafer, and usually contains 0.5 to 1% of hydrofluoric acid. I'm using it.

Table 1 shows an example of a wafer cleaning process (Ultra Pure Water Science, Realize, p. 774).

[0004]

[Table 1]

As shown in Table 1, the contamination of the silicon wafer is treated with a chemical solution suitable for removing each contamination, and then the chemical solution containing the contaminants adhering to the surface of the silicon wafer is further treated with ultrapure water. This is performed by repeating the washing step. Finally, the ultrapure water attached to the silicon wafer is completely removed.

The dilute hydrofluoric acid etching steps indicated by 2, 4 and 6 in Table 1 are chemical solution treatments and removal of natural oxide films formed in the atmosphere or ultrapure water.

The use of hydrofluoric acid in the production of silicon semiconductor devices is not limited to the etching steps shown in Table 1. For example, when etching a silicon oxide film, buffered hydrofluoric acid (a mixed solution of ammonia and hydrofluoric acid) is used. Is used, and when etching the silicon oxide film and the silicon surface, hydrofluoric nitric acid (a mixed solution of hydrofluoric acid, nitric acid, and acetic acid) is used.

The above chemicals are used in the manufacturing process, and when the period of use is prolonged or the throughput of silicon wafers is increased, the silicon concentration in the chemicals rises and the etching efficiency changes and deteriorates. It is necessary to renew the chemical solution in the processing tank. However, since it is difficult to determine the update time, conventionally, the update time of the chemical solution is
Alternatively, it is actually performed every time when the number of processed silicon wafer carriers is measured and reaches a predetermined number, and more quickly than necessary in order to give priority to the stability of processing.

Therefore, conventionally, the renewal of the medicinal solution has been made independent of the concentration of silicon in the medicinal solution, and even the medicinal solution which can be sufficiently used is renewed and disposed of as a waste liquid.
Since the waste liquid of the above chemical liquid has a high concentration and cannot be normally processed by the waste water treatment facility in the factory, the waste liquid processing company will be entrusted with its disposal, and the cost burden for that is large,
It is also undesirable from the viewpoint of environmental protection.

Further, since it is not possible to keep the silicon concentration in the chemical solution constant, it is feared that the processing efficiency such as etching will be varied and the characteristics of the semiconductor device of the product will be affected. In particular, in the etching process using buffered hydrofluoric acid or hydrofluoric nitric acid, which is required to accurately etch a submicron level pattern, it is necessary to sufficiently control the etching rate, and therefore, it is possible to reduce the etching rate. It is extremely important to control the concentration of silicon in the causative solution.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to reduce waste liquid discharged from a cleaning process using a chemical solution containing at least hydrofluoric acid or an etching process. A silicon wafer processing apparatus that can reduce the cost burden required for the waste liquid processing and contribute to environmental protection, and can accurately control the etching rate by keeping the silicon concentration in the chemical liquid in the processing tank constant. To provide.

[0012]

In order to achieve the above object, the present invention provides a treatment tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, and a total evaporation residue amount in the chemical solution. The present invention proposes a silicon wafer processing apparatus comprising a total evaporation residue measuring device.

The present invention also provides a treatment tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a total evaporation residue meter for measuring the total evaporation residue amount in the chemical solution, and the total evaporation residue. A silicon wafer processing apparatus comprising: a chemical liquid replenishing device that updates at least a part of the chemical liquid in the processing tank when the measurement value of the physical meter exceeds a predetermined value. , A control unit for sending a control signal for controlling the replenishment amount of the chemical liquid according to the output of the total evaporation residue meter, and a chemical liquid replenishment valve for opening and closing according to the control signal.

Further, according to the present invention, a processing tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a pump and a filtering device are interposed, and the chemical solution is taken out of the chemical solution tank and filtered. A silicon wafer processing apparatus, comprising: a circulation line for returning to the processing tank; and a total evaporation residue meter for measuring the total amount of evaporation residue in the chemical liquid flowing in the circulation line.

Further, according to the present invention, a processing tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a pump and a filtering device are interposed, and the chemical solution is taken out of the chemical solution tank and filtered. A circulation line returning to the processing tank, a total evaporation residue meter for measuring the total amount of evaporation residue in the chemical liquid flowing in the circulation line, and a measured value of the total evaporation residue meter exceeding a predetermined value. A silicon wafer processing apparatus comprising a chemical liquid replenishing device for renewing at least a part of the chemical liquid in the processing tank, wherein the chemical liquid replenishing device replenishes the chemical liquid according to the output of a total evaporation residue meter. A control unit for transmitting a control signal for controlling the amount,
And a chemical liquid supply valve that opens and closes according to the control signal.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a flow of the first embodiment of the present invention.

In FIG. 1, reference numeral 2 is a processing tank in which a chemical solution 4 is contained. The chemical solution 4 is selected according to the content of the treatment performed in the treatment tank 2. For example, dilute hydrofluoric acid is used to remove the natural oxide film on the surface of the silicon wafer 6, and buffered hydrofluoric acid (a mixed solution of ammonia and hydrofluoric acid) is used to etch the silicon oxide film formed as the insulating film.
Hydrofluoric nitric acid (a mixed solution of hydrofluoric acid, nitric acid, and acetic acid) is selected for etching both the silicon oxide film and the silicon surface, and the concentrations and compositions thereof are known per se. Known conditions are appropriately selected as the processing conditions such as the processing temperature and the processing time.

Then, the silicon wafer 6 is etched or the oxide film is removed in the processing bath 2. Along with this, the concentration of the silicon compound in the chemical solution in the processing tank 2 starts to increase, and the concentration of hydrofluoric acid and the like starts to decrease.

Reference numeral 8 denotes a sampling tube, one end of which is immersed in the chemical liquid 4 in the processing tank 2 and the other end of which is connected to the inlet of the total evaporation residue meter. The chemical solution 4 is sent through the pipe 8 to a total evaporation residue meter 10, where the concentration of the total evaporation residue in the chemical solution is measured.

The total evaporation residue meter 10 is for spraying sample water and evaporating it by bringing it into contact with heated air to atomize the evaporation residue in the sample water, and measure this by a gas phase particle counter. As a total evaporation residue meter, TS-1000 (manufactured by Hitachi Engineering), high pure monitor (trade name, manufactured by Nomura Micro Science)
Known materials such as the above can be used as they are.

The measured value of the total evaporation residue meter is the control unit 12
When the measured value exceeds a predetermined concentration, a control signal is sent to the chemical liquid replenishing valve 14. Accordingly, the opening / closing of the chemical liquid supply valve 14 is controlled or the opening degree of the valve is adjusted, and the chemical liquid such as dilute hydrofluoric acid stored in the chemical liquid tank 16 passes through the supply pipe 18 to the distributor 20 in the processing layer. It is sent and supplied into the processing tank 2.

Here, the predetermined concentration is determined experimentally and empirically, but it is generally preferable to be determined in the range of 0.005 to 0.05% by weight.

When only opening and closing the valve, the alarm output of the total evaporation residue meter can be used, but when a signal for adjusting the opening is obtained, for example, a digital controller ES100X (manufactured by OMRON) is used. A well-known controller such as the above can be used. Here, the control unit 12 and the chemical liquid supply valve 14 form a chemical liquid supply device. Reference numeral 22 is a discharge line for discharging the chemical liquid 4 in the processing tank 2.

In the above embodiment, for example, the chemical solution 4 in the processing bath 2 is sampled every time one set of silicon wafer carriers is processed, and the silicon concentration in the chemical solution is measured as the concentration of all evaporation residues. The update frequency of the chemical solution can be determined so that the elementary concentration does not become an abnormally high concentration, or by providing a control unit that adjusts the opening degree of the chemical solution supply valve according to the measurement value of the total evaporation residue meter, It is possible to control the silicon concentration to a predetermined value.

The chemical solution can be updated by either continuous update due to overflow or a batch-type update method in which the entire amount of the used chemical solution is discharged and replaced with an unused chemical solution.

In particular, in an etching apparatus that requires accurate control of the etching rate, an intelligent type controller that responds well to disturbance is used as the total evaporation residue concentration control unit, and the opening degree of the chemical liquid supply valve is adjusted. By controlling, it is preferable to continuously update the chemical liquid so that the concentration of silicon in the processing tank maintains a predetermined value.

(Second Embodiment) FIG. 2 is a flow chart showing a second embodiment of the present invention. In this form, the pump 3
2. A circulation line 36 in which a filtration device 34 is interposed is attached to the treatment tank 2, and the chemical liquid extracted from the bottom portion 38 of the treatment tank 2 by the operation of the pump 32 is sent to the filtration device 34.
Here, the solid matter is filtered and then returned to the processing tank 2.
Reference numeral 40 denotes a sampling pipe connected to the circulation line 36. A part of the chemical liquid flowing in the circulation line 36 is sent to the total evaporation residue meter 10 through the pipe 40, and other configurations and functions are Since it is the same as the first embodiment, the same reference numerals are given to the same portions, and the description thereof will be omitted.

[0028]

Since the present invention is configured as described above, it is possible to accurately measure the silicon concentration in the processing tank and thereby to update the chemical solution in the processing tank at an appropriate time, or It is possible to control the silicon concentration in the liquid to a desired concentration or less. Therefore, it is possible to reduce the usage amount of the chemical solution that has been excessively supplied in the related art, accurately control the etching rate, and the like, and it is possible to manufacture the silicon semiconductor device stably and at low cost.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating an embodiment of a first present invention.

FIG. 2 is a flowchart illustrating an embodiment of the second present invention.

[Explanation of symbols]

 2 Processing Tank 4 Chemical Liquid 6 Silicon Wafer 8 Sampling Pipe 10 Total Evaporation Residue Total 12 Control Unit 14 Chemical Liquid Supply Valve 16 Chemical Liquid Tank 18 Supply Pipe 20 Distributor 22 Discharge Line 32 Pump 34 Filtration Device 36 Circulation Line 40 Sampling Pipe

Claims (6)

[Claims] 1. A processing tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, and a total evaporation residue meter for measuring the total evaporation residue amount in the chemical solution. Silicon wafer processing equipment. 2. A processing tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a total evaporation residue meter for measuring the total amount of evaporation residue in the chemical solution, and a total evaporation residue meter A silicon wafer processing apparatus comprising: a chemical liquid replenishing device that updates at least a part of the chemical liquid in the processing tank when a measured value exceeds a predetermined value. 3. A chemical solution replenishing device comprises a control section for sending a control signal for controlling the replenishment amount of the chemical solution according to the output of the total evaporation residue meter, and a chemical solution replenishing valve for opening and closing according to the control signal. The silicon wafer processing apparatus according to claim 2, wherein 4. A treatment tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a pump and a filtration device, and the chemical solution is taken out of the chemical solution tank and filtered to be treated. A silicon wafer processing apparatus, comprising: a circulation line for returning to the substrate; and a total evaporation residue meter for measuring the total amount of evaporation residue in the chemical liquid flowing in the circulation line. 5. A processing tank for etching or cleaning a silicon wafer containing a chemical solution containing at least hydrofluoric acid, a pump and a filtration device, and the chemical solution is taken out of the chemical solution tank and filtered to be treated. A circulation line for returning to, a total evaporation residue meter for measuring the total evaporation residue amount in the chemical liquid flowing in the circulation line, and the treatment tank when the measured value of the total evaporation residue meter exceeds a predetermined value. And a chemical solution replenishing device for renewing at least a part of the chemical solution in the silicon wafer processing apparatus. 6. A chemical solution replenishing device comprises a control section for sending a control signal for controlling the replenishment amount of the chemical solution according to the output of the total evaporation residue meter, and a chemical solution replenishing valve for opening and closing according to the control signal. The silicon wafer processing apparatus according to claim 5, comprising: