JP7032095B2 - Surface treatment method and equipment - Google Patents

Description

The present invention relates to a method and an apparatus for surface-treating a substrate to be treated containing a silicon-containing substance, and particularly to a surface treatment method and an apparatus suitable for dry etching of a high-strain point glass substrate or the like.

For the surface roughness formation of glass substrates, processing methods such as mechanical polishing and wet etching using an aqueous solution of ammonium fluoride are the mainstream.
Further, in a manufacturing process of a flat panel display or the like using glass as a substrate, the glass substrate is easily peeled off and charged, and the electronic circuit or the like may be destroyed by the discharge after charging. In Patent Document 1, in order to prevent the peeling charge, it is proposed that the back surface of the glass substrate is dry-etched with a plasma containing a hydrogen fluoride gas to have a certain surface roughness. The temperature of the glass substrate during dry etching (vapor phase chemical reaction) is set to 25 ° C.

Japanese Patent No. 5679513

In recent years, for example, in order to eliminate the deviation of the print pattern due to the heat cycle, a high strain point glass substrate having a strain point of about 600 ° C. to 1000 ° C. has been developed. Incidentally, the strain point of a general blue plate glass is about 500 ° C.
High strain point glass has a low linear expansion rate. On the other hand, high strain point glass has a small proportion of the composition that develops roughness, and it is said that it is difficult to obtain a constant surface roughness even if it is etched with hydrogen fluoride or the like.
In view of such circumstances, it is an object of the present invention to roughen the surface of a substrate to be treated such as glass having a high strain point with a small amount of etching.

In order to solve the above-mentioned problems, the inventor has made diligent research and consideration.
As a solution, for example, it is conceivable to heat a process gas containing a fluorine-based reaction component such as hydrogen fluoride to bring it into contact with the substrate to be treated. Generally, under the condition that the substrate to be treated at room temperature and the heated process gas are combined, a high reaction can be expected because the gas component is easily adsorbed on the surface of the substrate to be treated.
However, in the dry etching reaction of a silicon-containing substrate using hydrogen fluoride, under the above-mentioned combination conditions, the aggregated layer of the liquid phase generated on the substrate surface during the reaction process becomes too thick, and the etching reaction proceeds but the etching reaction proceeds but is high Ra (coarse). The expression of (s) is slowed down.
Further, from the viewpoint of processing efficiency, it is efficient to process the entire area in the width direction of the substrate to be processed at once by using an outlet nozzle having the same size as the width of the substrate to be processed. It is necessary to provide a rectifying section including a chamber, a perforated plate, a slit, etc. for homogenizing the gas in the width direction of the nozzle (see JP-A-2004-006586, etc.), and gas heating and heat insulating means are incorporated therein. Is not easy.
On the other hand, if the substrate to be treated is heated, the reaction proceeds while evaporating the aggregated layer, so that high surface roughness can be expected.

The present invention has been made based on the above-mentioned study, and is a surface treatment method for dry etching the surface to be treated of a substrate to be treated containing a silicon-containing substance.
The strain point of the substrate to be processed is 600 ° C. to 1000 ° C.
The step of transporting the substrate to be processed in the transport direction so as to pass through the processing region, and
A step of supplying a process gas containing a fluorine-based reaction component to the processing region, and
A step of adjusting the temperature of the substrate to be processed before being carried into the processing area to 35 ° C. or higher and 100 ° C. or lower,
It is characterized by being equipped with.
As a result, the surface of the substrate to be treated with a high strain point can be reliably surface-roughened with a small amount of etching.
If the temperature is lower than 35 ° C., the etching amount increases but the desired surface roughness cannot be obtained.
If the temperature exceeds 100 ° C., it is necessary to make the device configuration heat resistant, which increases the cost. In addition, a cloudy portion or cloudiness appears on the surface to be treated, and the charge suppressing effect is reduced.
The linear expansion rate of the substrate to be processed is preferably about 1 to 50 ( ^10-7 / ° C.).
Examples of the heating method of the substrate to be processed in the substrate temperature control step include infrared rays (IR), ultraviolet rays (UV), laser, plasma, and warm air.
It is preferable to pass the processing area by transporting the substrate to be processed. It is preferable to heat the substrate to be processed while transporting it.
It is preferable that the substrate temperature control step is performed immediately before the substrate to be processed is carried into the processing space. As a result, the substrate to be treated after heating can be introduced into the processing area before the heat is dissipated, the range in which the heat insulating means for preventing heat dissipation should be provided can be reduced, or the heat insulating means can be omitted.

The dew point of the process gas is preferably 15 ° C to 40 ° C. As a result, the surface of the substrate to be processed having a high strain point can be more reliably surface-roughened.

The apparatus of the present invention is a surface treatment apparatus for dry etching the surface to be treated of a substrate to be treated containing a silicon-containing substance.
A processing unit having a processing area and
A transport means for transporting the substrate to be processed in the transport direction so as to pass through the processing region.
A process gas supply means for supplying a process gas containing a fluorine-based reaction component to the processing region, and a process gas supply means.
A substrate temperature adjusting means arranged on the upstream side of the processing region in the transport direction and adjusting the temperature of the substrate to be processed to 35 ° C. or higher and 100 ° C. or lower.
The strain point of the substrate to be processed is 600 ° C. to 1000 ° C.
The process gas is preferably generated by plasmating a raw material gas containing fluorine-containing gas and water in the vicinity of atmospheric pressure.
The pressure in the processing region is preferably near atmospheric pressure.
In the present specification, the vicinity of atmospheric pressure means a range of 1.013 × 10 ⁴ to 50.663 × 10 ⁴ Pa, and 1.333 × 10 ⁴ in consideration of facilitation of pressure adjustment and simplification of device configuration. ~ 10.664 × 10 ⁴ Pa is preferable, and 9.331 × 10 ⁴ to 10.397 × 10 ⁴ Pa is more preferable.
Examples of the silicon-containing substance include SiO ₂ , SiN, Si, SiC, SiOC and the like.
The fluorine-based reaction component is a compound capable of reacting with the silicon-containing substance, and examples thereof include HF and COF ₂ .

According to the present invention, a substrate to be treated having a high strain point can be reliably surface-roughened with a small amount of etching.

FIG. 1 is a front view showing a schematic configuration of a surface treatment apparatus according to an embodiment of the present invention. FIG. 2 is a plan view of the nozzle portion of the surface treatment apparatus along the line II-II of FIG. FIG. 3 is a graph showing the results of Example 1. FIG. 4 is a photograph of the surface to be treated after the roughening treatment when the substrate temperature exceeds 100 ° C. FIG. 5 is an AFM (atomic force microscope) image of the surface to be treated after the roughening treatment when the substrate temperature is over 100 ° C.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a surface treatment apparatus 1 according to an embodiment of the present invention. The substrate 9 to be processed is a glass substrate that should be a semiconductor device such as a flat panel display. The glass substrate 9 contains a silicon-containing substance such as SiO ₂ as a main component.
The glass substrate 9 is a high strain point glass having a strain point of about 600 ° C. to 1000 ° C.
The linear expansion rate of the glass substrate 9 is relatively low, about 1 to 50 ( ^10-7 / ° C.).
The initial roughness of the back surface (processed surface 9a) of the glass substrate 9 is, for example, Ra = 0.1 nm to 0.2 nm.

The surface treatment apparatus 1 roughens the surface to be processed 9a (back surface or lower surface) of the glass substrate 9 by dry etching while transporting the glass substrate 9 in the transport direction MD. As a result, fine irregularities having a surface roughness Ra = angstrom order to nano order, preferably Ra = 0.3 nm to 1 nm are formed on the surface to be treated.

The surface treatment apparatus 1 includes an HF generation unit 10, a dry etching processing unit 20, and a transport means 30.
The HF generation unit 10 is composed of an atmospheric pressure plasma generation unit including a pair of electrodes 11 and 11 facing each other. Although not shown, a solid dielectric such as alumina (Al ₂ O ₃ ) is provided on the facing surface of at least one electrode. One of these electrodes 11 is connected to the high frequency power supply 15, and the other is electrically grounded. When a pulsed high-frequency voltage is preferably applied between the electrodes 11 and 11, a glow discharge near the atmospheric pressure is generated, and the space between the electrodes 11c becomes a discharge space.

The raw material gas supply unit 12 is connected to the upstream end of the space between the electrodes 11c (discharge space). The fluorine-containing raw material gas includes a fluorine-containing gas, water ( _H2O ), and a carrier gas.
Fluorine-containing gases include PFCs (perfluorocarbons) such as CF ₄ , C ₂ F ₄ , C ₂ F ₆ , C ₃ F ₈ , and HFCs (hydrofluorocarbons) such as CHF ₃ , CH ₂ F ₂ , and CH ₃ F. Examples include SF ₆ , NF ₃ , XeF ₂ , and other fluorine-containing compounds. Here, CF ₄ is used as the fluorine-containing gas.

Examples of the carrier gas include rare gases such as helium, argon, neon and xenon, nitrogen and other inert gases. In addition to the function of transporting the fluorine-containing gas, the carrier gas has a function as a diluting gas for diluting the fluorine-containing gas, a function as a discharge generating gas in the discharge space 11c, and the like.

When the fluorine-containing raw material gas is plasmatized (including excitation, activation, radicalization, ionization, etc.) in the discharge space 11c, the fluorine-containing gas (CF ₄ ) is decomposed, and the fluorine-based reaction component, which is a fluorine-based reaction component, is used. Hydrogen fluoride (HF) is produced. As a result, a process gas is generated from the fluorine-containing raw material gas. The reaction formula for producing hydrogen fluoride is, for example, the following formula.
CF ₄ + 2H ₂ O → 4HF + CO ₂ (Equation 1)
The process gas contains hydrogen fluoride (HF) and water ( _H2O ). The dew point of the process gas (condensation point of hydrofluoric acid water) is preferably about 15 ° C to 40 ° C.
The fluorine-based reaction component in the process gas is not limited to hydrogen fluoride (HF), and may be COF ₂ or the like.

The process gas supply path 13 is connected to the downstream end of the space between the electrodes 11c (discharge space). The process gas supply path 13 extends to the processing section 20.

The processing unit 20 includes a nozzle unit 21 and an opposing member 23, and is housed in a processing chamber (not shown). The internal pressure of the processing chamber is almost atmospheric pressure.

As shown in FIGS. 1 and 2, the nozzle portion 21 has a container shape extending in the width direction TD (direction orthogonal to the paper surface in FIG. 1) orthogonal to the transport direction MD. An outlet 21a and a suction port 21b are formed on the upper surface 21f (processed area image plane) of the nozzle portion 21. The outlet 21a has a slit shape extending in the width direction TD (direction orthogonal to the paper surface in FIG. 1). The dimension of the TD in the width direction of the outlet 21a is about the same as or slightly larger than the width dimension of the glass substrate 9 (the dimension in the direction orthogonal to the paper surface in FIG. 1). Although not shown, a rectifying unit is provided inside the nozzle unit 21. The rectifying unit includes a chamber, a slit, a perforated plate, etc. (see JP-A-2004-006586, etc.). By passing through the rectifying section, the process gas from the process gas supply path 13 is made uniform in the width direction TD of the nozzle section 21 (in the direction orthogonal to the paper surface in FIG. 1), and then blown upward from the outlet 21a. Orthogonal.

The suction port 21b extends in a slit shape in the width direction TD (direction orthogonal to the paper surface in FIG. 1). The suction port 21b is connected to a suction means (not shown) such as a vacuum pump via a suction path 14.

The air outlet 21a and the suction port 21b are arranged apart from each other on both sides (left and right in FIG. 1) of the transport direction MD on the nozzle upper surface 21f. Preferably, the outlet 21a is arranged near the end of the nozzle upper surface 21f on the transport downstream side (left side in FIG. 1), and the suction port 21b is the end of the nozzle upper surface 21f on the transport upstream side (right side in FIG. 1). It is located nearby.
Contrary to the above arrangement, the outlet 21a may be arranged on the upstream side of the transport, and the suction port 21b may be arranged on the downstream side of the transport. The air outlet 21a may be arranged at the center of the nozzle upper surface 21f in the transport direction, and the pair of suction ports 21b may be arranged on the transport upstream side and the transport downstream side with the air outlet 21a interposed therebetween.

The facing member 23 is arranged above the nozzle portion 21 at a distance. The facing member 23 is formed in a horizontal plate shape and extends in the width direction TD (direction orthogonal to the paper surface in FIG. 1) in parallel with the nozzle portion 21. The lower surface 23a (opposing surface) of the facing member 23 faces the upper surface 21f of the nozzle portion 21 in the vertical direction (opposing direction). A flat space 22 is formed between the facing surfaces 23a and 21f. The flat space 22 extends in the width direction TD (direction orthogonal to the paper surface in FIG. 1). As shown in FIG. 2, both ends of the flat space 22 in the width direction TD are closed by a pair of end walls 27.

The portion of the flat space 22 from the outlet 21a to the suction port 21b is the processing region 22a. Both ends of the flat space 22 and thus the transport direction MD of the processing region 22a are open. The two directions orthogonal to the transport direction MD in the processing region 22a are closed by the upper and lower surfaces 23a and 21f and the pair of end walls 27. That is, the processing region 22a is closed except for both sides of the transport direction MD.
The internal pressure of the flat space 22 and thus the processing region 22a is near the atmospheric pressure.

The process gas supply means 26 for supplying the process gas to the processing region 22a is configured by the HF generation unit 10, the process gas supply path 13, and the nozzle unit 21 including the outlet 21a.

The transport means 30 is composed of, for example, a roller conveyor, horizontally supports the glass substrate 9, and passes the glass substrate 9 through the flat space 22 and thus the processing region 22a along the transport direction MD. The surface to be processed 9a of the glass substrate 9 during transportation is directed downward. The distance d from the nozzle upper surface 21f to the surface to be processed 9a (lower surface) of the glass substrate 9 being conveyed is, for example, d = 1 mm to 5 mm, preferably d = 4 mm.

As shown in FIGS. 1 and 2, the drive rollers 34 on both sides of the nozzle portion 21 in the transport means 30 have a cylindrical shape (log shape) having an axial length substantially the same as the width dimension of the nozzle portion 21. There is. An annular body 34c made of a soft material such as an O-ring is provided on the outer peripheral portion of the drive roller 34 at intervals. The annular body 34c is in contact with the glass substrate 9. The drive roller 34 is housed in a roller storage box 37 having an upper opening. Dry gas is supplied to the roller housing box 37.
Further, the transport means 30 includes a free roller 35 on the upper surface 21f of the nozzle. An annular body 35c made of a soft material such as an O-ring is provided on the outer circumference of the free roller 35. The annular body 35c is in contact with the glass substrate 9.
A shielding wall 36 is provided between the free rollers 35 adjacent to the TD in the width direction and further outside of the outermost free roller 35 in the TD in the width direction.

As shown in FIG. 1, the surface treatment device 1 further includes a substrate temperature adjusting means 40. The substrate temperature adjusting means 40 is arranged on the upstream side (right side in FIG. 1) in the transport direction from the processing unit 20 and thus the processing area 22a. The substrate temperature controlling means 40 includes a pair of infrared heaters 41 and 41. The pair of infrared heaters 41, 41 are arranged so as to sandwich the transport path through which the glass substrate 9 passes from above and below. As shown in FIG. 2, each infrared heater 41 extends in the width direction TD in parallel with the nozzle portion 21. The lower infrared heater 41 is arranged so as not to interfere with the roller 31 of the transport means 30.
One of the upper and lower infrared heaters 41 and 41 may be omitted. For example, the upper infrared heater 41 may be omitted.
Preferably, the infrared heater 41 is arranged as close as possible to the nozzle portion 21 and thus the processing region 22a. For example, the distance D from the infrared heater 41 to the processing region 22a is preferably about D = 10 mm to 100 mm. It is preferable that the moving speed of the glass substrate 9 is about 2 to 20 m / min and the temperature of the glass substrate 9 can be heated to 35 ° C. or higher and 100 ° C. or lower.
The substrate temperature controlling means 40 may include a laser heater, a plasma heater, a warm air heater, or the like instead of the infrared heater 41.

The substrate temperature adjusting means 40 adjusts the temperature of the glass substrate 9 to 35 ° C. or higher and 100 ° C. or lower.
If the temperature is lower than 35 ° C, the desired surface roughness cannot be obtained.
If the temperature exceeds 100 ° C., the etching processing unit 20 and the transporting means 30 need to have heat resistant specifications, which increases the cost. In addition, a cloudy portion or cloudiness appears on the surface to be treated of the glass substrate 9, and the charge suppressing effect is also reduced.

The glass substrate 9 is dry-etched (surface roughened) by the surface treatment apparatus 1 as follows.
A process gas containing hydrogen fluoride (HF) is generated by plasma conversion of the fluorine-containing raw material gas in the HF generation unit 10. The process gas is sent to the etching processing unit 20 via the process gas supply path 13 and is supplied to the processing region 22a from the outlet 21a (process gas supply step).

In parallel, the glass substrate 9 is transported along the transport direction MD by the transport means 30 (transport step).
Immediately before the glass substrate 9 reaches the etching processing unit 20, the glass substrate 9 is heated by the substrate temperature adjusting means 40. The heating set temperature of the glass substrate 9 is adjusted to 35 ° C. or higher and 100 ° C. or lower (board temperature adjusting step).
The heated glass substrate 9 is carried into the processing region 22a. By heating the glass substrate 9 immediately before carrying in, the glass substrate 9 can be arranged in the processing region 22a before the heat is dissipated. Therefore, the range in which the heat insulating means such as the heat insulating material should be provided can be reduced, or the heat insulating means can be omitted.

In the processing region 22a, the process gas comes into contact with the surface to be processed 9a of the heated glass substrate 9. As a result, hydrogen fluoride and water vapor are condensed on the surface to be treated 9a to form an aggregate layer of hydrofluoric acid water. An etching reaction occurs between the aggregated layer of the hydrofluoric acid water and the silicon-containing substance of the glass substrate 9. The reaction formula is, for example, the following formula.
SiO ₂ + 4HF + H ₂ O → SiF ₄ + 3H ₂ O (Equation 2)
By setting the dew point of the process gas to 15 ° C to 40 ° C and heating the glass substrate 9, the thickness of the aggregated layer can be reliably suppressed.

As a result, it is possible to form fine irregularities having a surface roughness Ra = angstrom order to nano order, preferably Ra = 0.3 nm to 1 nm on the surface to be treated.
Even if the glass substrate 9 is a high strain point glass having a strain point of about 600 ° C. to 1000 ° C., the desired surface roughness Ra can be obtained with a small amount of etching by heating the glass substrate 9.
Since it is not necessary to heat the process gas, it is not necessary to incorporate the gas heating and heat insulating means into the nozzle portion 21, and the device configuration can be simplified.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.
For example, hydrogen fluoride in the process gas is not limited to that produced by plasma discharge. The HF generating means is not limited to the atmospheric pressure plasma, and may be a corona discharge. The gas obtained by vaporizing the aqueous hydrogen fluoride solution may be used as the process gas. A method of bubbling an aqueous solution of hydrogen fluoride and performing a dry etching process may also be used.

Examples will be described. The present invention is not limited to the following examples.
A surface treatment apparatus having substantially the same configuration as the apparatus 1 shown in FIG. 1 was used.
As the substrate 9 to be processed, high strain point glass having a strain point of 600 to 800 ° C. was used.
The initial surface roughness Ra of the surface to be treated 9a of the glass substrate 9 (before the etching treatment) was Ra = 0.18 nm.
The width of the glass substrate 9 (dimensions in the direction orthogonal to the paper surface in FIG. 1) was 370 mm.
The length of the glass substrate 9 in the transport direction (left-right direction in FIG. 1) was 470 mm.
The thickness of the glass substrate 9 was 0.7 mm.
The transport speed of the glass substrate 9 was 6.0 m / min.
The set heating temperature of the glass substrate 9 by the infrared heater 41, that is, the substrate temperature was set to the following four types.
25 ° C (without substrate heating), 35 ° C, 55 ° C, 125 ° C
The heated substrate 9 was passed through the processing region 22a.

At the same time, the fluorine-containing raw material gas containing CF ₄ , Ar and H ₂ O was plasmatized in the HF generation unit 10 to generate a process gas.
The flow rate of CF ₄ of the fluorine-containing raw material gas was 0.8 slm, and the flow rate of Ar was 11.2 slm.
The supply flow rate of the process gas was 12 slm.
The dew point of the process gas was 30 ° C.
This process gas was sent to the etching processing unit 20 and supplied to the processing region 22a from the outlet 21a so as to be in contact with the surface to be processed 9a of the glass substrate 9.

The surface roughness Ra and the etching amount of the surface to be treated 9a of the glass substrate 9 after the treatment were measured.
As a measuring instrument, a scanning probe microscope (manufactured by Hitachi High-Technologies Corporation, model: AFM5100N) was used.
The etching amount was calculated from the weight of the glass substrate 9 before and after the treatment.

The measurement results are as shown in the graphs of Table 1 and FIG.
Due to the effect of heating the substrate, the aggregated layer of the liquid phase did not become too thick, and high Ra was developed with a small amount of etching. It was confirmed that the surface of a high strain point glass substrate can be reliably and satisfactorily roughened by setting the substrate temperature to 35 ° C. or higher and 100 ° C. or lower.

FIG. 4 is a photograph of the surface to be treated 9a after the roughening treatment at a substrate temperature of 125 ° C., and FIG. 5 is an AFM image thereof.
When the substrate temperature was higher than 100 ° C., cloudiness or cloudiness appeared on the surface to be treated 9a, and it was confirmed in the AFM image that the surface was depressed and raised.

The present invention can be applied to, for example, the manufacture of flat panel displays.

1 Surface treatment device 9 Processed circuit board 9a Processed surface 20 Processing unit 26 Process gas supply means 30 Transport means 40 Substrate temperature control means 41 Infrared heater

Claims (2)

A surface treatment method for dry etching the surface to be treated of a substrate to be treated, which contains a silicon-containing substance and has a strain point of 600 ° C. to 1000 ° C.
The step of transporting the substrate to be processed in the transport direction so as to pass through the processing region, and
A step of supplying a process gas containing a fluorine-based reaction component to the processing region, and
A step of adjusting the temperature of the substrate to be processed before being carried into the processing area to more than 55 ° C and 100 ° C or less, and
A surface treatment method comprising the above, wherein the dew point of the process gas is 15 ° C to 30 ° C. A surface treatment device that dry-etches the surface to be treated of a substrate to be treated, which contains silicon-containing substances and has a strain point of 600 ° C to 1000 ° C.
A processing unit having a processing area and
A transport means for transporting the substrate to be processed in the transport direction so as to pass through the processing region.
A process gas supply means for supplying a process gas containing a fluorine-based reaction component to the processing region, and a process gas supply means.
A substrate temperature adjusting means arranged on the upstream side of the processing region in the transport direction and adjusting the temperature of the substrate to be processed to more than 55 ° C. and 100 ° C. or lower.
A surface treatment apparatus comprising the above, wherein the dew point of the process gas is 15 ° C to 30 ° C.

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