JP2009049284A - Method and equipment of surface treatment using hydrogen fluoride - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the tact time by eliminating a step for stabilizing the gas state and resuming surface treatment immediately after a temporary stop for replacing an article to be treated when the surface treatment is performed using a treatment gas containing hydrogen fluoride (HF). <P>SOLUTION: When surface treatment is performed, a treatment gas of required flow rate and concentration of hydrogen fluoride is produced using a plurality of production sections 10 and passed through the ejection channels 23, 24 and 25 at an ejection channel defining section 20 before being jetted to an article W to be treated. When a temporary stop mode is selected by a selecting means 51, the number of sections 10 for producing hydrogen fluoride is decreased and the treatment gas is passed through the ejection channels 23-25 at a flow rate lower than that when surface treatment is performed and with the substantially same concentration of hydrogen fluoride as that when surface treatment is performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an apparatus and a method for performing surface treatment by spraying a processing gas containing hydrogen fluoride (HF) onto a workpiece from a jet channel.

For example, in the surface treatment such as film formation and etching, generally, after supplying the processing gas, the process is waited for stabilization, and the processing is started after a predetermined time. After the processing is completed, the processing gas supply is turned off. Thereafter, the workpiece is replaced. In particular, when the processing is performed in a vacuum, the above sequence is inevitably performed because of the necessity of exhaust. The same sequence is generally adopted in the treatment under atmospheric pressure.
JP 2007-1116020 A

  However, when HF is used as a processing gas component, once the processing gas supply is temporarily stopped due to replacement of an object to be processed, and then the processing gas supply is resumed, it takes time until the HF concentration stabilizes, and the tact time is reduced. The problem of being pressured has become apparent.

The inventor has intensively studied to solve the above problems.
FIG. 5 shows a case where a mixed gas of CF ₄ and H ₂ O is introduced into a plasma space, and is passed through a nozzle tube (length 1.23 m) made of HF resistant Teflon (registered trademark) from the plasma space. The result of having analyzed the gas component in the exit of this with a Fourier-transform infrared spectrometer (FTIR) is shown. 0 on the horizontal axis (elapsed time) is the time when the plasma is turned on. HF and CO ₂ are generated by plasmatization. Of these, the CO ₂ concentration rose sharply as soon as the plasma was turned on, and reached saturation in a relatively short time. On the other hand, the HF concentration took a very long time to saturate and saturate. This is considered because HF is a substance that is easily adsorbed on the inner wall of the nozzle. While the adsorption proceeds, the amount of HF from the nozzle outlet decreases accordingly. As the adsorption approaches saturation and equilibrates with desorption, the amount of HF from the nozzle outlet increases. The amount of adsorption in the equilibrium state mainly depends on the HF concentration in the gas.
Therefore, if the supply of the same amount of processing gas as at the time of executing the process is continued without stopping the supply of the processing gas even when the object to be processed is replaced, the execution of the process can be resumed immediately after the replacement. However, this will increase the loss of the processing gas.

The present invention has been made based on such consideration, and in a method for performing surface treatment of an object to be processed using an ejection path defining portion having an ejection path through which a processing gas containing HF passes.
At the time of performing the surface treatment, a treatment gas having a required flow rate and HF concentration is sprayed on the workpiece through the ejection path,
When the surface treatment is temporarily stopped, a treatment gas having a flow rate smaller than that during execution of the surface treatment and substantially the same hydrogen fluoride concentration as that during execution of the surface treatment is ejected through the ejection path.
Further, the present invention provides an apparatus for performing a surface treatment by spraying a processing gas containing HF onto an object to be processed.
Means for supplying the processing gas;
An ejection path defining portion having a distal end surface to be opposed to the object to be processed, and an ejection path that is continuous with the supply unit and that is open to the distal end surface;
A selection means for selecting a surface treatment execution mode and a pause mode;
The supply means supplies a processing gas having a required flow rate and HF concentration to the ejection path in the execution mode, and has a flow rate smaller than the execution mode in the temporary stop mode and substantially the same as the execution mode. A treatment gas having a hydrogen fluoride concentration is supplied to the ejection passage.
Thereby, the process for stabilizing the gas state can be omitted when the process execution mode is reselected after the pause mode, and the process can be resumed immediately. As a result, the tact time can be shortened. Further, the loss of the processing gas that flows during the temporary stop mode can be offset with the loss of the processing gas during the gas state stabilization process that is no longer necessary. Furthermore, the loss of the processing gas can be reduced as compared with the case where the processing gas is always flowed at a constant amount regardless of the mode.

The supply means includes a plurality of generation units that generate hydrogen fluoride by converting the fluorine-containing raw material and the hydrogen-containing raw material into plasma (including decomposition, excitation, activation, radicalization, and ionization), and in the execution mode, The plurality of generation units may be operated, and in the temporary stop mode, only a smaller number of generation units may be operated than in the execution mode, and the other generation units may be stopped.
Examples of the fluorine-containing raw material include CF ₄ , CHF ₃ , COF ₂ , and F ₂ .
Examples of the hydrogen-containing raw material include H ₂ O and H ₂ .

  It is preferable that the inner surface of the ejection path of the ejection path defining portion is made of a fluorine-based resin such as polytetrafluoroethylene or Teflon (registered trademark), or a ceramic such as alumina. Thereby, the corrosion resistance with respect to HF in process gas can be improved. The main body of the ejection path defining section itself may be made of the fluorine resin or ceramics, and the main body of the ejection path defining section is made of a metal such as aluminum or stainless steel, and the inner surface thereof is coated with the fluororesin. May be made.

  According to the present invention, the gas state stabilization process can be omitted and the process can be resumed immediately when the process execution is resumed after being temporarily stopped by replacement of an object to be processed. As a result, the tact time can be shortened.

Embodiments of the present invention will be described below.
As shown in FIG. 1, the surface treatment apparatus includes a processing unit 1 and a stage 2. The workpiece W is arranged on the stage 2. The workpiece W is made of, for example, a glass substrate. An amorphous silicon layer (not shown) to be etched is formed on the surface of the glass substrate W.
The size of the glass substrate W is not limited, but is 2 m × 2 m, for example.
The thickness of the amorphous silicon layer is, for example, 200 nm.

A moving mechanism 3 is connected to the stage 2. The stage 2 is reciprocated (scanned) in the left-right direction in FIG. 1 by the moving mechanism 3.
The moving mechanism 3 may be connected to the processing unit 1, the position of the stage 2 may be fixed, and the processing unit 1 may be movable left and right.

The processing unit 1 is disposed above the stage 2.
As shown in FIGS. 1 and 2, the processing unit 1 includes a plurality of (for example, five) generation units 10, 10... And a single ejection path defining unit 20. The ejection path defining unit 20 extends in the front-rear direction (the direction orthogonal to the plane of FIG. 1, the left-right direction in FIG. 2). A plurality of generators 10, 10... Are arranged side by side in the front-rear direction on the upper surface of the ejection path defining unit 20.

The HF raw material supply path 31 from the HF raw material gas source 30 is branched into a plurality of lines and is connected to each generating unit 10. Each supply path 31a after the branch is provided with an HF raw material flow rate adjusting means 32 comprising an electromagnetic on-off valve.
The HF source gas source 30 supplies a mixed gas of, for example, Ar, CF ₄ (fluorine-containing source), and H ₂ O (hydrogen-containing source) as the HF source gas to each generator 10 via the HF source supply path 31. It is like that.

Each generation unit 10 is provided with a pair of electrodes 11. The electrodes 11 extend in the left-right direction (in the direction orthogonal to the plane of FIG. 2) and constitute parallel plate electrodes.
The length of the electrode 11 in the left-right direction is, for example, about 1 m.

By supplying power from a power source (not shown), an atmospheric pressure discharge is generated between the electrodes 11 and 11 so that the interelectrode space 12 becomes a plasma space. The supplied power is 4 kW, for example.
An HF raw material gas is introduced into the plasma space 12 to be turned into plasma, and HF is generated.

  At the bottom of each generation unit 10, a lead-out port 13 connected to the plasma space 12 is formed. The outlet 13 has a slit shape extending in the left-right direction.

  The ejection path defining unit 20 has a rectangular parallelepiped shape with a length in the left-right direction (left-right direction in FIG. 1) of, for example, about 1 m and a length in the front-rear direction (in the orthogonal direction in FIG. 1) of, for example, about 2 m. The inside of the ejection path defining part 20 is partitioned vertically by a partition wall 22 to form a plurality of stages of rectifying paths 23, 23. The outlet 13 of each generator 10 is connected to the uppermost rectifying path 23.

  In the partition wall 22 between the upper and lower rectifying paths 23, 23, a communication hole 24 that connects the rectifying paths 23, 23 is formed. The number of the communication holes 24 increases as the lower partition 22 is reached. Accordingly, the gas is made uniform in the front-rear direction and the left-right direction as the gas flows toward the lower rectification path 23.

A plurality of (for example, five) injection ports 25 are formed at the bottom of the ejection path defining unit 20. The injection port 25 has a slit shape extending in the front-rear direction, and is arranged side by side with each other. The lowermost rectification path 23 is connected to the injection port 25.
The length of each injection port 25 in the front-rear direction is, for example, about 2 m.
The rectifying path 23, the communication hole 24, and the ejection port 25 constitute ejection paths 23 to 25.

The outer casing 21 and the inner partition 22 of the ejection path defining unit 20 are made of metal such as aluminum or stainless steel. The inner surface of the rectifying passage 23, the inner surface of the communication hole 24, and the inner surface of the injection port 25 of the ejection passage defining unit 20 are coated with a fluorine resin such as Teflon (registered trademark). (Therefore, the inner surfaces of the ejection paths 23 to 25 are made of a fluorine resin.) The fluorine resin coating has high corrosion resistance against HF.
The main body of the ejection path defining unit 20 may be made of fluorine resin instead of metal, or may be made of ceramic such as alumina. Ceramics such as alumina are also highly resistant to corrosion by HF.
It is also possible to stack the ceramic plates on which the concave portions to be the rectifying passages 23, the communication holes 24, and the injection ports 25 are laminated to form the ejection passage defining portion 20.

The HF-containing gas from the generation unit 10 is introduced from the outlet 13 into the uppermost rectification path 23.
Separately, an ozone supply path 41 from the ozonizer 40 is connected to the first-stage rectification path 23. The ozone supply path 41 is provided with ozone flow rate adjusting means 42 including an electromagnetic flow rate control valve.

Further, the surface treatment apparatus is provided with a control means 50 and a mode selection switch 51 (selection means) attached to the control means 50. The mode selection switch 51 can select a surface treatment execution mode and a pause mode.
The control means 50 operates the on-off valve 32, the flow rate control valve 42, the power source (not shown), the moving mechanism 3 and the like according to the selected mode.

In the surface treatment apparatus having the above-described configuration, when the execution mode of the surface treatment is selected by the mode selection switch 51, the control unit 50 opens the on-off valve 32 of each branch supply path 31a, and a plurality of (5 HF source gas (Ar + CF ₄ + H ₂ O) is supplied to all of the generators 10.
The flow rate of each component of the HF source gas is set to be, for example, Ar 9 slm, CF _{4 1} slm, and H 2 O 0.1 slm per generation unit 10.
As a result, the HF raw material gas is turned into plasma by each generating unit 10 to generate an HF-containing gas, which is introduced into the ejection path defining unit 20.

Further, the control means 50 operates the flow rate control valve 42 to introduce the ozone-containing gas (O ₂ + O ₃ ) generated by the ozonizer 40 into the ejection path defining unit 20. The supply flow rate of the ozone-containing gas is set to 30 slm, for example, and the ozone concentration O ₃ / (O ₂ + O ₃ ) in the ozone-containing gas is set to be about 8%, for example.
As a result, the HF-containing gas and the ozone-containing gas are mixed inside the ejection path defining unit 20 to generate a processing gas containing HF and O ₃ as reactive components.
The flow rate of the processing gas after mixing is 80.5 slm. The HF concentration in this processing gas is about 0.4 vol%.

The processing gas having the required flow rate and the required HF concentration is made uniform in the front-rear direction and the left-right direction by passing through the plurality of stages of rectifying passages 23 and the communication holes 24 of the ejection passage defining unit 20. It is spouted out evenly.
At this time, HF adsorption occurs on the inner surfaces of the ejection paths 23 to 25. This adsorption amount is saturated at a magnitude corresponding to the HF concentration of the processing gas and reaches an equilibrium state.
The processing gas ejected from the ejection port 25 is sprayed onto the lower glass substrate W, O ₃ and HF come into contact with the amorphous silicon, a reaction occurs, and the amorphous silicon is etched.

  At the same time, the control means 50 operates the moving mechanism 3 to cause the stage 2 to scan left and right. The moving speed of the stage 2 is set to 10 m / min, for example. The amorphous silicon can be etched by, for example, about 20 nm by one scan of the stage 2 (one movement in the right direction or one movement in the left direction). The movement distance for one scan is the total of the dimension (2 m) in the left-right direction of the glass substrate W and the dimension (1 m) in the left-right direction of the ejection path defining unit 20, and is 3 m here. By scanning the stage 2 10 times (5 reciprocations), the 200 nm amorphous silicon layer can be etched, and the processing for one glass substrate W is completed. The required time is about 3 min.

  As shown in FIG. 3, after the process is completed, the mode selection switch 51 selects the pause mode. The control unit 50 may automatically enter a temporary stop mode when the number of scans reaches a predetermined number. In this case, the control unit 50 also functions as a “selection unit”.

  When the pause mode is selected, the stage 2 is stopped at a position where it is retracted from the processing unit 1. The processed glass substrate W on the stage 2 is taken out and replaced with a glass substrate W to be newly processed. The replacement may be performed manually or automatically using a manipulator (not shown). For example, replacement takes about 0.5 min.

  As shown in FIG. 3, when entering the temporary stop mode, the control unit 50 closes four of the five on-off valves 32 and stops the supply of the HF source gas to the corresponding four generation units 10, Power supply from the power source to these four generation units 10 is stopped, and plasma generation is stopped.

  On the other hand, one of the on-off valves 32 is maintained in an open state, and the supply of the HF raw material gas to the corresponding one generation unit 10 is continued, and the power supply to the one generation unit 10 is continued. As a result, plasma generation is continued in one generation unit 10, and HF-containing gas is generated. The supply gas condition and the plasma generation condition in the one generation unit 10 are the same as those at the time of processing execution. Therefore, HF having the same concentration as that at the time of executing the process is generated. The flow rate of the HF-containing gas introduced into the ejection path defining unit 20 is reduced to one fifth of that at the time of processing execution.

  In FIG. 3, the generation unit 10 that continues the HF generation is arranged at one end in the longitudinal direction of the processing unit 1, but is not limited to this, and five (plural) generation units Any one of 10 may be used, and the number is not limited to one. A plurality of generation units 10 may be used. For example, two generation units 10 at both ends may be provided, or different generation units 10 may be provided for each temporary stop.

  Further, the control means 50 throttles the flow rate control valve 42 in parallel with the operation of the on-off valve 32, so that the flow rate of the ozone-containing gas in the ozonizer 40 is reduced to one-fifth of the time when the process is executed. The ozone-containing gas having a flow rate of 1/5 is introduced into the uppermost rectifying path 23 of the ejection path defining unit 20 and mixed with the HF-containing gas from the one generating unit 10.

  Therefore, a processing gas having a flow rate of 1/5 smaller than that at the time of executing the process and an HF concentration substantially equal to that at the time of executing the process is generated. This processing gas flows through the ejection paths 23 to 25 and is ejected. Therefore, even when the temporary stop mode is entered, the amount of adsorption of HF on the inner surfaces of the ejection paths 23 to 25 does not decrease, and the equilibrium state between adsorption and desorption is continuously maintained from the time of execution of processing.

After the replacement of the glass substrate W is completed, the processing execution mode is reselected by the mode selection switch 51. In response to this, the control means 50 opens the four on-off valves 32 that have been closed, restarts the power supply to the four generation units 10, and restarts the HF generation in these four generation units 10. Further, the flow control valve 42 is operated to return the supply amount of the ozone-containing gas from the ozonizer 40 to the original size. As a result, a processing gas having a flow rate five times that at the time of the temporary stop and an HF concentration equal to that at the time of the temporary stop is generated. Since the HF concentration is unchanged, the adsorption amount of HF on the inner surfaces of the ejection paths 23 to 25 continues to maintain an equilibrium state. Therefore, the HF concentration in the processing gas does not decrease when passing through the ejection passages 23 to 25. Therefore, it is not necessary to wait until the HF concentration in the gas injected from the injection port 25 is stabilized, and the surface treatment can be immediately performed on the new glass substrate W.
As a result, the time required for gas stabilization (2 min or more) becomes unnecessary, and the tact time can be shortened.
Further, at the time of the temporary stop, the gas amount can be reduced by about 17% as compared with the case where the HF generation is performed by supplying the gas to all five generation units 10 as in the case of executing the process.

Next, another embodiment of the present invention will be described. In the following embodiments, the same reference numerals are given to the drawings for the same configurations as those already described, and the description thereof is omitted.
In this embodiment, the plasma generation unit 10 of the processing unit 1 is omitted, and the processing unit 1 includes only the ejection path defining unit 20. In place of the plasma generation unit 10, a storage tank 60 is provided as an HF supply source. Liquid HF is stored in the tank 60. A nitrogen supply source 62 is connected to the HF storage tank 60 via a carrier path 61. A carrier flow rate control valve 63 is provided in the carrier path 61. An HF-containing gas supply path 64 extends from the tank 60.

Nitrogen (N ₂ ) gas from the nitrogen supply source 62 is introduced into the HF storage tank 60 through the carrier path 61, and HF is vaporized and mixed therein, whereby HF containing a mixed gas of N ₂ and HF is contained. Gas is generated. This HF-containing gas is led out from the tank 60 to the supply path 64.
The carrier flow rate control valve 63 (HF-containing gas flow rate control means) can control the flow rate of N _{2 and} thus the HF-containing gas.

Further, an ozone supply path 41 extends from the ozonizer 40 and merges with the HF-containing gas supply path 64. An ozone flow rate control valve 42 is provided in the ozone supply path 41.
The ozone-containing gas (O ₂ + O ₃ ) generated by the ozonizer 40 is mixed with the HF-containing gas (N ₂ + HF) from the HF-containing gas supply path 64 via the ozone supply path 41 and processed gas (N ₂ + HF + O _2). + O ₃ ) is generated.

  A processing gas supply path 65 extends from the junction of the HF-containing gas supply path 64 and the ozone supply path 41. For example, the processing gas supply path 65 is bifurcated and connected to both longitudinal ends of the uppermost rectifying path 23 of the ejection path defining section 20.

The flow rate of the HF-containing gas in the processing execution mode is, for example, 50 slm, and the HF concentration is, for example, HF / N ₂ = 1 vol%. The flow rate of the ozone-containing gas is, for example, 30 slm, and the O ₃ concentration is, for example, O 3 / (O ₂ + O ₃ ) = 8 vol%. Therefore, the flow rate of the process gas in the process execution mode is 80 slm.

When the temporary stop mode is selected by the mode selection switch 51, the control means 50 operates the carrier flow rate control valve 63 and the ozone flow rate control valve 42 to make the flow rate of the processing gas smaller than the processing execution mode. Preferably, the processing execution mode is set to 1/5 to 1/100. When the flow rate in the processing execution mode is 80 slm, it is preferable to set the flow rate to about 0.8 to 16 slm in the temporary stop mode. The HF concentration in the processing gas is set equal to the processing execution mode.
As a result, as in the first embodiment, when the process execution mode is reselected, the gas stabilization process can be omitted, and the process can be resumed immediately.

The present invention is not limited to the above embodiment, and various modifications can be made.
For example, in the first embodiment, the supply flow rate to one generation unit 10 that continues operation in the pause mode may be smaller than the supply flow rate to the one generation unit 10 in the process execution mode. As long as it does not become more than the sum of the supply flow rate to all the production | generation parts 10 in a mode, you may enlarge.
The number of generation units 10 is not limited to five, but may be one to four, or six or more. When there is only one generation unit 10, the gas supply flow rate to the one generation unit 10 may be adjusted according to the mode.
The present invention is applicable not only to etching but also to various plasma surface treatments such as ashing, film formation, cleaning, and surface modification.

  The present invention can be used for manufacturing a semiconductor substrate and a flat panel display (FPD), for example.

It is front sectional drawing which shows schematic structure of the surface treatment apparatus which concerns on 1st Embodiment of this invention. It is side surface sectional drawing which shows the said surface treatment apparatus in process execution mode. It is side surface sectional drawing which shows the said surface treatment apparatus in temporary stop mode. It is side surface sectional drawing which shows schematic structure of the surface treatment apparatus which concerns on 2nd Embodiment of this invention. It is a graph which shows the experimental result of the density | concentration change of the plasma generation component in the process of making this invention in the nozzle exit.

Explanation of symbols

W Glass substrate (object to be processed)
DESCRIPTION OF SYMBOLS 1 Processing part 10 Generation | occurrence | production part 20 Spout path definition part 21 Outer casing 22 Partition 23 Rectification path (spout path)
24 communication hole (spout channel)
25 injection port
30 HF source gas source 32 Electromagnetic on-off valve (source flow rate control means)
40 Ozonizer 41 Ozone supply path 42 Flow control valve (ozone flow control means)
50 Control means 51 Mode selection switch (selection means)
60 HF storage tank 63 Carrier flow rate control valve (HF containing gas flow rate control means)

Claims (4)

In a method of performing surface treatment of an object to be processed using an ejection path defining portion having an ejection path through which a processing gas containing hydrogen fluoride (HF) passes.
At the time of performing the surface treatment, a treatment gas having a required flow rate and hydrogen fluoride concentration is sprayed on the object to be treated through the ejection path,
When the surface treatment is temporarily stopped, the surface treatment is characterized in that a treatment gas having a flow rate smaller than that during execution of the surface treatment and substantially the same hydrogen fluoride concentration as that during execution of the surface treatment is ejected through the ejection path. Method. In an apparatus for performing a surface treatment by spraying a treatment gas containing hydrogen fluoride (HF) on a workpiece,
Means for supplying the processing gas;
An ejection path defining portion having a distal end surface to be opposed to the object to be processed, and an ejection path that is continuous with the supply unit and that is open to the distal end surface;
A selection means for selecting a surface treatment execution mode and a pause mode;
The supply means supplies a processing gas having a required flow rate and hydrogen fluoride concentration to the ejection path in the execution mode, and has a flow rate smaller than the execution mode in the temporary stop mode and is substantially the same as the execution mode. A surface treatment apparatus for supplying a treatment gas having the same hydrogen fluoride concentration to the ejection passage.   The supply means includes a plurality of generation units that generate hydrogen fluoride by converting the fluorine-containing raw material and the hydrogen-containing raw material into plasma, and operates the plurality of generation units in the execution mode, and in the temporary stop mode, the 3. The surface treatment apparatus according to claim 2, wherein only a smaller number of generation units than in the execution mode are operated, and the other generation units are stopped.   The surface treatment apparatus according to claim 2, wherein an inner surface of the ejection path of the ejection path defining unit is made of a fluorine-based resin or ceramics.

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