JPH04357835A - Wet processor - Google Patents

Abstract

PURPOSE:To maintain a temperature distribution constant so as to eliminate deterioration of uniformity of a temperature of etchant due to an increase in a cleaning wet etching tank when a capacity of the tank is increased as a diameter of a wafer is increased. CONSTITUTION:Three heaters 2a, 2b, 2c are mounted in a quartz cleaning tank, and platinum-based thermocouples are provided as temperature sensors 3a, 3b at the intermediates therebetween. Chemicals are circulated through a pump 5 and a filter 6 to remove dusts, and to soak it. Further, in order to improve uniformity of a temperature, a temperature difference of the sensors 3a, 3b is obtained, and outputs of the heaters 2a and 2c are controlled based on its result. When ammonia water, hydrogen peroxide water, water are mixed at about 1:1:5 to clean a silicon series wafer, it is heated to about 80 deg.C by the heater 2b, and the outputs of the heaters 2a, 2b are controlled by a difference of a set temperature and the sensor 3a, 3b. Thus, an etching rate of the silicon becomes uniform, and characteristics of a semiconductor device are stabilized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wet processing apparatus for cleaning, wet etching, etc. for manufacturing semiconductor devices.

0002

2. Description of the Related Art In recent years, the diameter of wafers has increased from 6 inches to 8 inches, and is expected to become even larger in the future. Furthermore, in order to increase the processing capacity, the size of the processing tank is doubled so that two batches can be processed at the same time. As described above, since wet processing apparatuses still employ batch processing, the capacity of the cleaning tank is increasing as the diameter of wafers becomes larger. An example of a conventional wet processing apparatus, particularly a cleaning apparatus, will be described below with reference to the drawings.

FIG. 5 shows a sectional view of a processing tank of a conventional cleaning device. In FIG. 5, 1 is a cleaning tank. 2
is a heater, and the amount of heating is controlled by electric current. 3 is a temperature sensor, 7 and 8 are liquid level sensors, and 9 is an automatic valve.

[0004] The operation of the cleaning device constructed as described above when using a two-liquid mixture will be described.

First, the automatic valve 9 of the chemical solution 1 is opened and introduced into the cleaning tank 1. When the chemical liquid 1 is introduced to the position of the liquid level sensor 7, the valve 9 is automatically closed, and then the chemical liquid 2 is introduced into the cleaning tank 1 by opening the automatic valve 9. The automatic valve 8 closes at the position of the liquid level sensor 8, and the chemical liquid 1 and the chemical liquid 2 are mixed. Thereafter, a heater 2 heats the chemical solution, and a temperature sensor 3 monitors the temperature while controlling the heater output to maintain a constant temperature.

[0006]

[Problems to be Solved by the Invention] However, in the above configuration, the temperature inside the cleaning tank 1 is measured only at one point, and the heater 2 for heating is also located at the bottom of the cleaning tank 1. When the size of wafer 1 increases, the temperature distribution is not uniform and the etching rate varies within the wafer surface.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention provides a wet processing apparatus having a heating or cooling method and temperature control means for making the temperature distribution within the cleaning tank constant.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the wet processing apparatus of the present invention includes temperature measuring means at two or more places, heating or cooling means at two or more places, and temperature control means. It is prepared.

[0009]

[Operation] With the above-described configuration, the present invention first measures the temperature distribution inside the processing tank using temperature measuring means at two or more locations, and then controls the heating or cooling means installed inside and outside the processing tank based on the results. This keeps the temperature distribution inside the tank constant.

0010

【Example】

(Embodiment 1) A processing tank of a cleaning apparatus showing a first embodiment of the present invention will be described below with reference to the drawings. Figure 1
1 is a cross-sectional view of a processing tank of a cleaning device showing a first embodiment of the present invention. In FIG. 1, 1 is a quartz cleaning tank, 2 is a heater wire, 3 is a temperature sensor using a platinum thermocouple, 5 is a circulation pump, 6 is a filter, and 7 is a temperature control means.

Regarding the cleaning tank configured as above,
The operation will be explained below using FIG. First, as shown in FIG. 1, the chemical liquid in the cleaning tank 1 is circulated using a pump 5 and returned to the cleaning tank 1 through a filter 6 in order to remove dust. Although the temperature distribution is moderated to some extent by this circulation effect, when the cleaning tank 1 is large, a temperature gradient is created between the center and the periphery. FIG. 3 shows this situation. Approximately 20 when the heating source is placed at the origin
There is a drop of approximately 3°C at a distance of 0mm. The usable temperature variation is determined by the difference in the chemical solution used and the difference in the etching rate, but as the degree of integration of semiconductor devices increases, the films become thinner and finer, so the temperature variation can be reduced to 0.
．． I want to keep it below 5°C. Heaters 2a and 2b for heating
, 2c are installed at one location in the center and two locations on the periphery, and temperature sensors 3a and 3b are installed between them. The chemical solution used is a mixture of ammonia water, hydrogen peroxide solution, and water at a ratio of about 1:1:
It is mixed at a ratio of 5:5.

FIG. 4 shows a flowchart of temperature control of the processing tank. This will be explained below with reference to FIG. The set temperature Tc is approximately 8
Heat at 0°C to approximately 80°C using the main heater 2b. At this time, the main heater 2b is controlled by the temperature sensor on the high temperature side based on the temperature of the temperature sensor 3a or 3b. When the temperature of the temperature sensor on the high temperature side does not rise to the set temperature Tc, it is heated by the main heater 2b. Also, the chemical solution is at the set temperature T.
If the temperature does not rise to c, heating may be performed using heaters 2a and 2c.

Approximately 80°C at temperature sensor 3a or 3b
When this temperature is reached, if there is a temperature difference between the temperature of the temperature sensor 3a or 3b and the set temperature Tc, the heater 2a or 2c performs heating according to the difference. That is, when the temperature sensor 3a is lower than the set temperature Tc, the heater 2a heats it, and when the temperature sensor 3b is lower than the set temperature Tc, the heater 2c heats it.

Furthermore, if the temperature rises too much above the set temperature Tc, all heaters are turned off. The main heater 2b uses a general PID method to control these heaters, and the heaters 2a and 2c are controlled using a value obtained by multiplying the difference between the temperatures of the temperature sensors 3a and 3b and the set temperature by a certain coefficient. These controls and calculations are performed by a computer. Furthermore, the coefficient varies depending on the cleaning tank and chemicals used, and is determined empirically.

As described above, according to this embodiment, the temperature distribution within the plane of the cleaning tank can be uniformly controlled using three heaters and two temperature sensors, and silicon-based etching with ammonia/hydrogen peroxide solution can be prevented. It can be carried out with good uniformity, and deterioration in reliability of the gate oxide film due to roughness of the silicon substrate can be suppressed without variation. Furthermore, since the etching can be performed with good uniformity, the particulate removal performance is stable and dust can be removed without variation between wafers.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a sectional view of a processing tank of a cleaning device showing a second embodiment of the present invention. The cleaning tank is of the circulation type as in the first embodiment, and the difference from FIG.
The temperature sensor 3 is installed near the bottom of the cleaning tank (
They are installed in two locations: 3a) and near the top of the liquid level (3b). The temperature is controlled to a set temperature by the temperature sensor 3a. If there is a temperature difference between the temperature sensor 3b and the set temperature, the temperature of the temperature sensor 3b is generally lower, so the temperature can be made uniform by heating it with the heater 2b. The heater 2b is controlled by a value obtained by multiplying the temperature difference by a coefficient, and by having a computer perform the calculation and control, the temperature can always be kept constant.

As described above, according to the second embodiment, by controlling the heaters installed on the walls and bottom of the cleaning tank, the temperature of the bottom and top of the chemical solution can be kept constant, thereby preventing etching inside the wafer. Improved uniformity.

Although the first and second embodiments have been considered independently, they may be implemented in combination, and depending on the size of the cleaning tank, the heater and temperature sensor may be further divided. Further, in the present invention, the chemical solution is circulated through a filter in order to reduce dust, but the present invention can also be applied to a tank in which no circulation is performed. In addition, although only temperature differences were used for control to improve uniformity, PID
method may be used.

In the first embodiment, the heater 2 has a heater wire placed inside a quartz tube, but a heater film may be sandwiched between quartz plates and used instead of the heater 2.

Further, in the second embodiment, a film heater for heating is used as the heater 2, but an electronic cooling film may be attached to cool the chemical solution.

[0022]

Effects of the Invention As described above, the present invention provides temperature measuring means at two or more locations and heating or cooling means at two or more locations, and controls the heating and cooling means based on the temperature measurement results. It is possible to improve etching uniformity and stabilize the cleaning effect in the manufacturing process of semiconductor devices and the like.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a processing tank of a cleaning device in a first embodiment of the present invention.

FIG. 2 is a sectional view of a processing tank of a cleaning device in a second embodiment of the present invention.

FIG. 3 is a characteristic diagram showing the relationship between the distance from the heater and the liquid temperature.

FIG. 4 is a flow diagram of temperature control in the first embodiment of the present invention.

FIG. 5 is a sectional view of a processing tank of a conventional cleaning device.

[Explanation of symbols]

1　Cleaning tank 2 Heater 3 Temperature sensor

Claims (4)

[Claims] Claim 1: The temperature control means includes temperature measurement means at two or more locations, heating or cooling means at two or more locations, and temperature control means, and the temperature control means takes in temperature data obtained by each of the temperature measurement means and processes the temperature data. A wet processing apparatus characterized in that calculations are performed using temperature data to yield results for the number of heating or cooling means, and the output of each heating or cooling means is controlled based on the results. 2. The wet processing apparatus according to claim 1, wherein the temperature measuring means and the heating or cooling means are in one-to-one correspondence, and the corresponding heating or cooling means is controlled by the temperature obtained by the temperature measuring means. 3. The main heating source is controlled at the highest temperature among the temperature measuring means, the other heating means and the temperature measuring means are in one-to-one correspondence, and the heating means other than the main heating source is controlled at that temperature. The wet processing apparatus according to claim 1, wherein the wet processing apparatus controls: 4. The main cooling means is controlled at a temperature that indicates the lowest temperature among the temperature measurement points, the other cooling means and the temperature measuring means are in one-to-one correspondence, and the cooling means other than the main cooling means are controlled at that temperature. The wet processing apparatus according to claim 1, wherein the wet processing apparatus controls: