JPH07101715A - Production of silicon dioxide coating film and device therefor - Google Patents

Abstract

PURPOSE:To provide a method and a device to form a silicon dioxide film of uniform thickness on the surface of a base body by which the use amt. of the treating liquid is decreased and properties for maintenance, control and operation can be improved. CONSTITUTION:A base body 8 is dipped in a treating liquid 7 containing an aq. soln. of silicofluoride with a supersaturation state of silicon dioxide in such a manner that the surface of the base body 8 to be treated is along with the vertical direction. In this state, at least one of the base body 8 and the treating liquid 7 is vibrated in the vertical direction to produce a silicon dioxide film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for producing a silicon dioxide film, and more particularly, to a substrate to be processed such as a semiconductor wafer or a glass substrate in a semiconductor manufacturing process or a manufacturing process of electronic parts such as a liquid crystal display device. The present invention relates to a method and an apparatus for producing a silicon dioxide film, which produces a silicon dioxide film from a liquid phase.

[0002]

2. Description of the Related Art The liquid phase film forming method for a silicon dioxide film as described above is capable of forming a film at a temperature in the vicinity of room temperature, has good followability even with submicron level surface irregularities, and has a uniform thickness defect. In order to obtain a coating film having a small amount, its practical use has recently begun, and improvement of the method is being studied. Such a liquid phase film forming method of a silicon dioxide film has been proposed, for example, in JP-A-60-33233 and JP-A-62-20876. Among them, in the technique related to the former proposal, a treatment tank and a tank for dissolving an activator for maintaining a supersaturated state of silicon dioxide are separately provided,
A circulation device that circulates the treatment liquid and a filtration device that performs filtration are provided and are configured to form a silicon dioxide film while circulating the treatment liquid.

[0003]

By the way, the deposition of silicon dioxide is caused by colloidal silicate ions [Si (O
H) ₄ ] is caused by polycondensation between them, and such polycondensation occurs not only on the substrate surface but also in the treatment liquid. For this reason,
In the above conventional technique, a situation occurs in which the circulation device and the filtration device are blocked by the silicon dioxide particles. In order to avoid such a situation, conventionally, the circulation system is frequently cleaned, but this is not an effective method. In addition, there is a problem in that the amount of treatment liquid used is large because of having the circulation device and the filtration device, which is not economical.

As a means for solving such a problem, a method without circulating the processing liquid has been proposed. However, if the treatment liquid is not circulated, a large amount of silicon dioxide particles staying in the treatment liquid will adhere to the surface of the substrate, or the thickness of the silicon dioxide film formed on the surface of the substrate will be uneven. The problem arises. That is, the deposition rate of the silicon dioxide film depends on the degree of supersaturation of silicon dioxide in the treatment liquid and the temperature difference between the film formation temperature and the treatment liquid production temperature, and colloid formation [Si (OH) ₄ ] depends on these conditions. Ultimately determined by the amount of sol. Since this sol has a higher density than the treatment liquid, it settles due to gravity, and the number of silicon dioxide particles adhering to the substrate surface increases. As a measure to prevent the adhesion of such silicon dioxide particles, a film forming method is generally used in which the base material is arranged in a processing tank so that the surface of the base material is along the vertical direction. However, in such a film forming method, since the concentration of [Si (OH) ₄ ] sol in the treatment liquid is higher in the downward direction, a new problem that the thickness of the silicon dioxide film becomes thicker in the lower side. Was occurring.

The present invention has been made in order to solve such problems, and it is of course possible to reduce the amount of the processing liquid used and improve the maintainability and operability. An object of the present invention is to provide a method and an apparatus capable of forming a silicon dioxide film having a uniform thickness on a material surface.

[0006]

According to the present invention, a substrate is immersed in a treatment liquid containing an aqueous solution of hydrofluoric silicic acid in which silicon dioxide is in a supersaturated state so that the surface of the substrate to be treated lies vertically. The feature is that the silicon dioxide film is manufactured while vertically oscillating at least one of the base material and the treatment liquid in the arranged state, and the base material and the treatment liquid are integrally formed in the same direction. It includes the case of vibrating and the case of vibrating either the substrate or the treatment liquid.

[0007]

When the processing liquid is vibrated in the vertical direction, minute waviness in the vertical direction is generated in the processing liquid, and relative movement in the vertical direction occurs between the processing liquid and the substrate. That is,
The treatment liquid is agitated by the base material, as a result, the sedimentation of the [Si (OH) ₄ ] sol in the treatment liquid is hindered, and the difference in concentration of the [Si (OH) ₄ ] sol is eliminated. The probability that the sol reaches the surface of the base material becomes uniform. this is,
The same applies to the case where only the base material is vibrated, or the case where only the treatment liquid is vibrated while the base material is stationary. Furthermore, in the present invention, since the treatment liquid and the base material are vertically vibrated relatively, it is possible to very effectively prevent the silicon dioxide particles staying in the treatment liquid from adhering to the substrate surface. .

Here, the frequency of the relative vibration is 15 Hz to 1
00 Hz is desirable. If the frequency is lower than 15 Hz, the effect of relative vibration is small, and it becomes difficult to satisfy the constraint condition of the deviation rate of the thickness of the silicon dioxide film that can be industrially applied. On the other hand, even if it exceeds 100 Hz, the thickness is evenly distributed. This is because the improvement effect at one time is not different from the case of 100 Hz or less, and the device for generating vibration becomes large-scale and expensive. The amplitude of relative vibration is 0.025.
It is desirable that it is mm to 0.15 mm. Amplitude is 0.
When it is less than 025 mm, the substantial effect of the relative vibration cannot be obtained, and when it exceeds 0.15 mm, the local concentration fluctuation becomes severe and the silicon dioxide particles in the treatment liquid (attach to the surface of the base material and become a contaminant). This is because the number of will increase. Furthermore, in order to ensure the substantial effect of the relative vibration, if the frequency of the vibration is reduced, the amplitude should be increased accordingly. Specifically, when the frequency is taken on the horizontal axis and the amplitude is taken on the vertical axis in Cartesian coordinates, the frequency is 50H.
When decreasing from z to 15 Hz, the lower limit of the amplitude corresponding to the frequency is 0.025 mm to 0.1.
It is desirable to set so as to increase linearly up to 5 mm.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described below with reference to FIG. FIG. 1 is a side sectional view showing a silicon dioxide film manufacturing apparatus of an example. The apparatus for producing a silicon dioxide film shown in this figure is roughly configured by a vibrating device (vibration generating means) 1 and a processing device 2 arranged on the vibrating device 1.

First, the processing apparatus 2 will be described. In the figure, reference numeral 2a is an outer tank constituting the outermost liquid-tight wall portion of the processing apparatus 2. The processing tank 3 is detachably fixed inside the outer tank 2a by a fastener 11 attached to the bottom of the outer tank 2a. The processing tank 3 has a cylindrical shape with a bottom, and the opening at the upper end is hermetically closed by a lid 4 and a packing 9 interposed between the lid 4 and the processing tank 3. In addition,
Reference numeral 10 in the drawing is a fastening tool for fixing the lid 4 to the processing tank 3. In addition, a treatment liquid 7 containing a hydrosilicofluoric acid aqueous solution in which silicon dioxide is in a supersaturated state is injected into the treatment tank 3, and a plurality of base materials 8 are included in the treatment liquid 7 in a vertical direction on the treatment surface. It is dipped and held by an appropriate means so as to follow the above.

Further, a liquid 12 as a heat medium for keeping the treatment liquid 7 in the treatment bath 3 at an appropriate temperature is injected into the outer bath 2a. The liquid 12 is uniformly maintained at a predetermined film forming temperature by the temperature controller 5 and the stirring device 6 arranged in the outer tank 2a. The processing device 2 configured as described above is adapted to be vertically vibrated by the vibrating device 1.

Reference numeral 13 in the drawing is a frame which is a main body of the vibration exciter 1. A permanent magnet 14 is arranged inside the frame 13. A vibrating table 16 whose upper end surface is attached to the lower end surface of the processing device 2 is elastically supported by a spring 17 on the pedestal 13. The lower end of the vibrating table 16 is made to project downward, and the coil 15 is attached to the walls of the projecting portions facing each other so as to surround the permanent magnet 14. An oscillator 19 and an amplifier 18, which are connected to an AC power source, are connected to the coil 15, and the frequency and amplitude of the vibrating table 16 are controlled.

Next, the step of forming a film on the base material 8 by the silicon dioxide film manufacturing apparatus having the above structure will be described. First, the treatment liquid 7 and the base material 8 are put into the treatment tank 3, and the lid 4 is closed with the fastener 10. Next, the processing tank 3 is attached to the bottom of the outer tank 2a, and this is fixed with the fastener 11. Next, the liquid 12 having a film forming temperature in advance is injected into the outer tank 2a, and then the liquid 12 is stirred by the stirrer 6 while the film forming temperature is maintained by the temperature controller 5 while the vibrating device 1 is used. A silicon dioxide film is formed on the surface of the substrate 8 while applying vertical vibration to the processing device 2.

According to the silicon dioxide film manufacturing apparatus having the above-mentioned structure, by vibrating the entire processing apparatus 2 in the vertical direction, a fine waviness in the vertical direction is generated in the processing liquid 7, and the processing liquid 7 and the base material 8 are formed. Relative vibration is generated in the vertical direction between and. As a result, the treatment liquid 7 is agitated by the base material 8, and as a result, the sedimentation of the [Si (OH) ₄ ] sol in the treatment liquid is hindered, and the concentration difference of the [Si (OH) ₄ ] sol due to gravity is eliminated. As a result, the probability that the sol reaches the surface of the base material becomes uniform. Further, in the above-described embodiment, the treatment liquid 7 and the base material 8 are relatively vibrated in the vertical direction, so that the adhesion of the silicon dioxide particles retained in the treatment liquid 7 to the surface of the substrate 8 is extremely effective. It can also be prevented.

Here, FIG. 3 shows that a silicon dioxide film is formed on the surface of a single crystal silicon substrate having a diameter of 5 inches by the silicon dioxide film producing apparatus having the above-mentioned structure under the condition that the deposition rate of the silicon dioxide film is 0.5 μm / h. 3 shows the relationship between the frequency (frequency) and the amplitude of the processing device 2 for forming and obtaining a uniform thickness that is industrially practical. The deviation rate of the thickness that is industrially practical [(maximum-minimum of film thickness) ÷
The constraint condition of the average of film thickness × 100] was set to 3% or less, and the frequency and the amplitude were set to the minimum necessary values to satisfy the conditions.

As a result, regarding the relationship between the frequency and the amplitude that satisfy the condition of the thickness uniformity, the amplitude is required to be 0.15 mm or more when the frequency is 15 Hz, and the minimum is required as the frequency increases. It was confirmed that the maximum amplitude gradually decreased. It was also confirmed that the minimum required amplitude was 0.025 mm when the frequency was 50 Hz, and the value of the required amplitude remained constant at 0.025 mm even when the frequency increased from 50 Hz. From the above results, the range of the frequency and the amplitude for obtaining the industrially practical thickness deviation rate is the area on the upper right side of the polygonal line E-A-B-C in FIG. The above relationship is the same when the deposition rate is 0.5 μm / h or less.

Further, if the amplitude exceeds 0.15 mm, the local concentration fluctuation becomes severe, which causes a problem that the number of silicon dioxide particles in the treatment liquid increases. Further, even if the frequency is made higher than 100 Hz, the improvement effect on the uniformity is not improved, but the vibration and swing mechanism of the vibration device becomes large and expensive, which is not preferable.

For the above reasons, the preferable range of the frequency and the amplitude that can obtain the industrially practical thickness deviation rate and do not cause various adverse effects is the polygonal line A in FIG.
It becomes the area inside -B-C-D-A.

Next, FIG. 2 shows another embodiment of the present invention, which is an example in which only the processing tank 3 is vibrated while the substrate 8 is stationary. In this example, the substrate 8
Is a chuck (grasping means) arranged separately from the processing tank 3.
The processing tank 3 is held stationary by 20 and the processing tank 3 can be vertically vibrated by the vibrating device 1 similar to the above-described embodiment. Also in this embodiment, the same effect as the above embodiment can be obtained.

In the above embodiment, the processing bath 3 is configured to vibrate, but the processing bath is left stationary and the chuck 2 is operated.
0 may be configured to vibrate in the vertical direction. Further, the vibrating device is not limited to the above-mentioned embodiment, and its configuration is arbitrary as long as the frequency and the amplitude can be controlled.

[Experimental Results] Next, the results when a silicon dioxide film is formed on the substrate surface according to the present invention will be described in comparison with a comparative example. Table 1 shows the production conditions of the silicon dioxide coatings of Examples 1 to 5 according to the method of the present invention and Comparative Examples 1 to 3.
And the manufacturing conditions are shown together with the deviation rate of the coating thickness. In Table 1, No. of the example. No. 1 is No. 1 when the frequency is the minimum within the scope of the present invention. 4 and No. 5 is the case where the amplitude is the minimum.

In the production experiment of the silicon dioxide film, the treatment liquid was produced at 25 ° C. and the concentration of the activator (Al) added was 0.2 m.
ol / l, diameter 5 inches as base material, thickness 0.6 m
Using a silicon single crystal plate of m, the treatment liquid temperature at the time of producing the silicon dioxide film was 35 ° C., and the operation was performed while vibrating for 1 hour in the apparatus shown in FIG. The base material after manufacturing is washed with ultrapure water and then dried, and the film thickness is measured at 20 points with an optical interference film thickness meter, and the thickness deviation rate [(maximum-minimum of film thickness) / average of film thickness] X100] was calculated.

In the evaluation shown in Table 1, the constraint condition of the industrially practical thickness deviation rate (%) is set to 3% or less, and those satisfying the condition are marked with ◯, and those not satisfying with are marked with ×. It is shown as a mark. From the results shown in Table 1, it was confirmed that Examples 1 to 5 included in the range described in the claims are within the industrially practical range.

[0024]

[Table 1]

Table 2 shows the results of comparison between the method according to the present invention and the conventional method (liquid circulation, stationary method). Table 2
As is clear from the above, when the silicon dioxide film is produced according to the present invention, since the liquid circulation device is unnecessary, the amount of the treatment liquid used is, for example, the size of the substrate is 5 inches in diameter as compared with the conventional method. If you do, about 1/20 to 1/3 per sheet
We were able to reduce it to about 0. It was also confirmed that the silicon dioxide film formed on the surface of the substrate had a uniform thickness and was industrially applicable.

[0026]

[Table 2]

[0027]

As described above, according to the present invention, in the treatment liquid containing the hydrofluoric acid silicofluoride solution in which silicon dioxide is supersaturated, the surface of the substrate to be treated is vertically aligned. With the material immersed and placed, the silicon dioxide film is manufactured by vertically vibrating at least one of the substrate and the treatment liquid, so the amount of treatment liquid used is reduced and maintenance and controllability are improved. Of course, it is possible to improve the properties of [Si (OH)
₄ ] Sol precipitation is hindered, the difference in concentration of [Si (OH) ₄ ] sol is eliminated, the probability that the sol reaches the surface of the base material becomes uniform, and the film thickness of the silicon dioxide film can be made uniform. The effect is obtained.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment of a silicon dioxide film manufacturing apparatus of the present invention.

FIG. 2 is a side sectional view showing another embodiment of the silicon dioxide film manufacturing apparatus of the present invention.

FIG. 3 is a diagram showing a relationship between frequency and amplitude in the method for producing a silicon dioxide film of the present invention.

[Explanation of symbols]

 1 Vibrating Device (Vibration Generating Means) 2 Processing Device 3 Processing Tank 4 Lid 5 Temperature Controller 6 Stirrer 7 Processing Liquid 8 Base Material 9 Packing 10, 11 Fastening Tool 12 Heat Medium 13 Stand 14 Permanent Magnet 15 Coil 16 Vibration Stand 17 Spring 18 Amplifier 19 Oscillator 20 Chuck

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kunio Tachiishi 4-2-1 Motofujisawa, Fujisawa City, Kanagawa Prefecture EBARA Research Institute

Claims (3)

[Claims] 1. A method for producing a silicon dioxide film, which comprises depositing a silicon dioxide film on the surface of a substrate by bringing a substrate into contact with a treatment liquid containing an aqueous solution of hydrofluoric silicic acid in which silicon dioxide is supersaturated. In the liquid, the substrate is immersed and arranged so that the surface to be treated of the substrate is aligned in the vertical direction, and at least one of the substrate and the treatment liquid is vertically vibrated while vibrating vertically. A method for producing a silicon dioxide coating, which comprises producing the coating. 2. The relative vibration between the substrate and the treatment liquid has a frequency of 15 Hz to 100 Hz and an amplitude of 0.025 mm to 0.
Within the range of 15 mm, and when the frequency is on the abscissa and the amplitude is on the ordinate in Cartesian coordinates, the frequency is 15 Hz-
In the range of 50Hz, the frequency is from 15Hz to 50Hz.
The amplitude increases from 0.15 mm to 0.
The method for producing a silicon dioxide film according to claim 1, wherein each value on a straight line that linearly decreases to 025 mm is set as a lower limit value. 3. A silicon dioxide film production apparatus for depositing a silicon dioxide film on the surface of a substrate by contacting a substrate with a treatment liquid containing a hydrofluoric acid silicofluoride solution in which silicon dioxide is supersaturated. Holding means for immersing and arranging the base material in the processing liquid so that the surface to be processed of the base material fits vertically, and a vibration generating means for vertically vibrating at least one of the base material and the processing liquid. An apparatus for producing a silicon dioxide film, comprising: