JP4406172B2 - Substrate processing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a substrate processing method for generating excited active species using plasma and promoting oxidation of an oxide film formed on the substrate surface using the excited active species.
[0002]
[Prior art]
As a semiconductor device, a silicon oxide (SiO _x ) thin film such as a SiO ₂ thin film is used as an insulating film. As a method for forming a silicon oxide (SiO _x ) thin film, there are means such as annealing a silicon substrate in an oxygen atmosphere, depositing it by a CVD method, or performing reactive sputtering while introducing oxygen. However, in any case, due to insufficient oxygen flow rate or insufficient heating of the substrate, it is difficult to perform sufficient oxidation due to insufficient oxygen incorporation into the film.
[0003]
When an under-oxidized silicon oxide (SiO _x ) thin film is allowed to function as a semiconductor device, current flows even at a low voltage at which current should not flow, causing malfunction.
[0004]
In order to repair such oxidation deficiency, methods of reannealing in an oxygen atmosphere or using oxygen plasma have been considered so far, but none of these methods has been sufficient.
[0005]
In the case of an indium tin oxide (hereinafter referred to as “ITO”) thin film used as a transparent electrode in a liquid crystal display device or the like, oxygen is released during film formation by sputtering. Sputtering is usually performed with oxygen flowing to make up for this. However, the amount of oxygen that escapes is still larger than the amount taken in, and oxygen in the ITO thin film may be insufficient. In such a case, conventionally, oxygen deficiency has been compensated by annealing in the air or in an oxygen atmosphere.
[0006]
In the case of annealing, the annealing time is determined by the relationship with temperature. In order to shorten the annealing time, the substrate temperature may be increased. However, in the case of a glass substrate for TFT, if the temperature is too high, the substrate itself is thermally damaged. If the temperature is lowered to avoid thermal damage, the annealing time becomes longer. If annealing takes a long time, productivity will decrease.
[0007]
In the case of an ITO thin film, complete oxidation is not preferable. Defects from which oxygen is released moderately are necessary. Conductivity is obtained by the free electrons in the defective portion, and the complete electron is lost. On the other hand, if the oxidation is insufficient, the crystallinity is impaired, light scattering increases in the film, and the transparency is lacking.
[0008]
[Problems to be solved by the invention]
Until now, in order to make up for the lack of oxidation in oxide films such as silicon oxide (SiO _x ) thin films and ITO thin films as described above, annealing in an oxygen atmosphere (in the case of ITO thin films, air is also possible) or oxygen plasma There has been a method of placing a substrate therein. However, in the case of annealing, an annealing apparatus becomes large. When oxygen plasma is used, the plasma directly contacts the thin film surface and is damaged by ion bombardment.
[0009]
In order to prevent this, measures such as lowering the plasma density and shortening the processing time have been considered, but this is not sufficient.
[0010]
The present invention does not require a large annealing apparatus when performing substrate processing for promoting the oxidation of an oxide film such as a silicon oxide (SiO _x ) thin film or ITO thin film formed on the substrate, and the oxidation promotion described above. An object of the present invention is to propose a substrate processing method in which plasma does not directly contact the surface of a thin film to be processed.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the substrate processing method proposed by the present invention is to generate plasma in a vacuum vessel to generate excited active species, and to treat the substrate surface with this excited active species.
[0012]
In this substrate processing method, the interior is separated into two chambers by a conductive partition wall, and one of the two separated chambers is a plasma generation space in which a high-frequency electrode is disposed, and the other chamber is Is formed as a substrate processing space in which a substrate holding mechanism for placing a substrate is disposed, and the conductive partition wall portion has a plurality of through holes that let the plasma generation space and the substrate processing space pass through. This is done using a vacuum vessel.
[0013]
That is, using the vacuum container having the above-described configuration, a plasma generation gas is supplied to the plasma generation space, and a high frequency power is applied to the high frequency electrode to generate a plasma discharge, thereby generating the plasma generation space. The excited active species of the generated plasma generating gas is introduced into the substrate processing space through a plurality of through holes of the conductive partition wall, and the substrate is treated with the excited active species introduced in the substrate processing space. Is what you do.
[0014]
Here, in the substrate processing method of the present invention, the plasma generating gas is any one of O ₂ , O ₃ , H ₂ O, CO, CO ₂ , NO, NO ₂ , and N ₂ O. A gas formed by mixing a rare gas or a nitrogen gas , supplying the plasma generating gas to a space on the opposite side of the substrate from the high-frequency electrode of the plasma generating space ; The excited active species introduced into the substrate processing space through the through-holes and the activated species transitioned from the excited active species act on the oxide film formed on the substrate to promote the oxidation. It is what.
[0016]
Further, the oxide film that promotes oxidation can be a silicon oxide (SiO _x ) thin film or an ITO (indium tin oxide) thin film formed on the surface of the substrate to be processed.
[0017]
According to the substrate processing method of the present invention, neutral plasma generating gas or electrically neutral excited species (radicals) of these plasma generating gas generated by oxygen plasma in the plasma generation space. A glass substrate or the like on which an oxide film is formed on the surface by selectively introducing only the excited active species into the substrate processing space and performing a process for further oxidation such as a silicon oxide (SiO _x ) thin film and an ITO thin film Without exposing the substrate to plasma containing high-energy ions, the substrate can be processed by the excited active species and the activated species that have transitioned from the excited active species. Therefore, it is possible to prevent the oxide film, which is subjected to the treatment for further proceeding the oxidation, directly contacting the surface of the oxide film and being damaged by the ion bombardment.
[0018]
As described above, as the plasma generation gas, any one of O ₂ , O ₃ , H ₂ O, CO, CO ₂ , NO, NO ₂ , N ₂ O, or these gases may be used. Since a gas composed of a rare gas or nitrogen gas is used, in addition to the excited active species, these plasma generation gases are also introduced into the substrate processing space, but in order to avoid thermal damage to the substrate itself. In the present invention in which substrate processing is performed at a temperature of about 300 ° C., the plasma generating gas introduced into these substrate processing spaces hardly affects the substrate.
[0019]
In the above description, only the neutral plasma generating gas and the excited active species that are electrically neutral excited species (radicals) of these plasma generating gases generated by the oxygen plasma in the plasma generation space are electrically conductive. The introduction of the charged particles of the plasma introduced into the substrate processing space through the plurality of through holes of the partition wall, that is, the plasma generation space, into the substrate processing space is, for example, a conductive partition. By keeping the portion at the same ground potential as the vacuum vessel, it is possible to realize without high frequency leakage into the substrate processing space.
[0020]
The plurality of through holes provided in the conductive partition wall that separates the inside of the vacuum vessel of the substrate processing apparatus used in the present invention into two chambers, the gas flow rate in the through hole is u, When the substantial length of the through hole is L (FIG. 4) and the mutual gas diffusion coefficient (the mutual gas diffusion coefficient of the gas on both sides of the through hole, ie, the plasma generation space and the substrate processing space) is D, uL It is desirable to form so as to satisfy the condition of / D> 1.
[0021]
By satisfying this condition, it is possible to prevent the plasma generating gas or its active species once released into the substrate processing space from back-diffusing back into the plasma generating space.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
[0023]
A preferred embodiment of the present invention will be described with reference to FIGS.
[0024]
In FIG. 1, 1 is a load lock chamber, 2 is a transfer chamber, and 3 is a substrate processing chamber in which the substrate processing method of the present invention is performed.
[0025]
The load lock chamber 1 and the substrate processing chamber 3 are connected to the transport chamber 2 through gate valves 4b and 4c, respectively. The load lock chamber 1 has a gate valve 4a for placing a substrate from the atmosphere in the apparatus. An exhaust valve 5 is attached to each of these chambers, and an exhaust mechanism (not shown) is connected to the chamber. When substrate processing is performed in each chamber, the inside of each of the chambers 1, 2, and 3 is evacuated by an evacuation mechanism through the evacuation valve 5 and maintained in a required vacuum state (or reduced pressure state). Note that a robot arm 2a for transporting a substrate is incorporated in the transport chamber 2 as indicated by a broken line.
[0026]
FIG. 2 is a top view of FIG. As can be seen, the illustrated embodiment is configured as a cluster type device.
[0027]
The substrate is carried into the load lock chamber 1 and depressurized to a required vacuum state. Thereafter, the substrate is transferred by the substrate transfer robot arm 2a provided in the transfer chamber 2, and is transferred into the substrate processing chamber 3 through the gate valves 4b and 4c. The substrate carried into the substrate processing chamber 3 is placed on the substrate holder 17 (FIG. 3) disposed at the lower portion.
[0028]
In each of the chambers 1 to 3 shown in FIG. 1, the structure of the substrate processing chamber 3 is indicated by a solid line as a characteristic configuration. The substrate processing chamber 3 is used to process a substrate processed by the method of the present invention (of these oxide films formed on the substrate) on an oxide film such as a silicon oxide (SiO _x ) thin film and an ITO thin film formed on the substrate. This is a substrate processing apparatus in which oxidation is further advanced.
[0029]
As illustrated in FIG. 3, the substrate processing chamber 3 includes a plasma generation space 15 spatially separated from the substrate processing space 16 above the interior thereof, and a plasma separation type substrate processing apparatus. It is configured as.
[0030]
The vacuum container 12 of the substrate processing apparatus is a vacuum container whose interior is maintained in a desired vacuum state by the exhaust mechanism 13 when performing substrate processing such as film formation processing. The exhaust mechanism 13 is connected to an exhaust port 12b-1 formed in the vacuum vessel 12.
[0031]
Inside the vacuum vessel 12, a conductive partition 14 made of a conductive member is provided in a horizontal state, and the periphery of the conductive partition 14 having a rectangular shape, for example, is fixed to a conductive material. It arrange | positions so that it may be pressed on the lower surface of the part 22 and a sealing state may be formed.
[0032]
Thus, the interior of the vacuum vessel 12 is separated into two upper and lower chambers by the conductive partition wall 14, the upper chamber forms the plasma generation space 15, and the lower chamber forms the substrate processing space 16.
[0033]
The conductive partition wall portion 14 has a desired specific thickness, has a flat plate shape as a whole, and has a planar shape similar to the horizontal sectional shape of the vacuum vessel 12.
[0034]
The substrate 11 is disposed on a substrate holder 17 provided in the substrate processing space 16. The substrate 11 is substantially parallel to the conductive partition wall 14 and is disposed such that the film formation surface (upper surface) to be processed faces the lower surface of the partition wall 14.
[0035]
The potential of the substrate holder 17 is held at the ground potential 41 that is the same potential as the vacuum vessel 12. Further, a heater 18 is provided inside the substrate holder 17. The temperature of the substrate 11 is maintained at a predetermined temperature by the heater 18.
[0036]
The structure of the vacuum vessel 12 will be further described. The vacuum vessel 12 includes an upper vessel 12a that forms the plasma generation space 15 and a lower vessel 12b that forms the substrate processing space 16 from the viewpoint of improving the assemblability. When the vacuum container 12 is formed by combining the upper container 12a and the lower container 12b, the conductive partition wall 14 is provided at a position between them. The electrode 20 has an insulating member 21a on the upper side of the insulating member 21a, 21b between which the side surface of the peripheral part is interposed between the upper container 12a, and a lower insulating member 21b on the lower end surface of the peripheral part. They are attached in contact with each other. As a result, an isolated plasma generation space 15 and a substrate processing space 16 are formed above and below the conductive partition wall 14.
[0037]
The conductive partition wall 14 includes a plurality of through holes 25, and the plasma generation space 15 and the substrate processing space 16 are connected only by the plurality of through holes 25.
[0038]
In the illustrated embodiment, the plurality of through holes 25 have a gas flow velocity u in the through hole 25, a substantial through hole length L (FIG. 4), and a mutual gas diffusion coefficient (both sides of the through hole 25). In other words, when the mutual gas diffusion coefficient of the gas in the plasma generation space 15 and the substrate processing space 16 is D, it is formed to satisfy the condition of uL / D> 1.
[0039]
In the embodiment of the substrate processing apparatus to which the substrate processing method of the present invention shown in FIG. 3 is applied, the region where the plasma 19 is generated in the plasma generation space 15 is the partition wall 14, the upper container 12 a, and the approximate center thereof. And a plate-like electrode (high-frequency electrode) 20 disposed at the position. The electrode 20 has a plurality of holes 20a.
[0040]
A power introducing rod 29 connected to the electrode 20 is provided on the ceiling of the upper container 12a. The electrode 20 is fed with high-frequency power for discharge by the power introduction rod 29. The electrode 20 functions as a high frequency electrode. The power introduction rod 29 is covered with an insulator 31 so as to be insulated from other metal parts.
[0041]
The conductive partition wall 14 has a ground potential 41 through the conductive material fixing portion 22.
[0042]
The insulating member 21 a is provided with a plasma generation gas introduction pipe 23 for introducing a gas for generating excited active species from the outside into the plasma generation space 15. As the plasma generation gas, for example, any of O ₂ , O ₃ , H ₂ O, CO, CO ₂ , NO, NO ₂ , N ₂ O, or a mixture of these gases with a rare gas or a nitrogen gas Gas can be used.
[0043]
A preferred embodiment of the present invention using the substrate processing chamber 3 described above will be described.
[0044]
By supplying a plasma generating gas (for example, O ₂ ) from the plasma generating gas introduction pipe 23 to the plasma generating space 15 and applying high frequency power to the electrode 20 of the plasma generating space 15 to generate a plasma discharge. In the plasma generation space 15, excited active species (O ^* and O ₂ ^* ) of the plasma generating gas (O ₂ ) are generated.
[0045]
The excited active species and the plasma generating gas generated in this way are introduced into the substrate processing space 16 through the plurality of through holes 25 of the conductive partition wall 14. At this time, some of the excited active species (O ^* and O ₂ ^* ) transition to a low energy level while moving to the substrate processing space 16 through the through-holes 25, and the basis of the O atoms In this way, the excited active species (O ^* and O ₂ ^* ) introduced into the substrate processing space 16 and the active species that have transitioned from the excited active species as described above are the substrate. The substrate 11 is processed to act on an oxide film such as a silicon oxide (SiO _x ) thin film or an ITO thin film formed on the substrate 11 and to promote the oxidation of those oxide films.
[0046]
Here, in the present invention, as described above, since the conductive partition wall portion 14 is reliably in contact with the conductive material fixing portion 22 having the ground potential, there is no leakage of the high-frequency substrate processing space 16. Only the excited active species (O ^* and O ₂ ^* ) and the plasma generating gas (O ₂ ) generated as described above are introduced into the substrate processing space 16 through the plurality of through holes 25 of the conductive partition wall 14. Will be. Therefore, the excited active species introduced into the substrate processing space 16 and the activated species that have transitioned from the excited active species as described above act on the oxide film formed on the surface of the substrate 11 on the substrate holder 17, and the substrate 11. That is, the process of promoting the oxidation of the oxide film formed on the substrate 11 is performed.
[0047]
【Example】
A preferred embodiment of the present invention using the substrate processing apparatus illustrated in FIG. 3 will be described.
[0048]
A glass substrate 11 (370 mm × 470 mm) on which a 1000 Å silicon oxide film is formed is placed on the substrate holder 17. The inside of the vacuum vessel 12 is depressurized to a predetermined depressurized state (about 32 Pa), the glass substrate 11 is kept at a predetermined temperature (about 310 ° C.) by the heater 18, and O 2 is generated from the plasma generating gas introduction pipe 23. In the space 15, a flow rate of 1.7 g / min. (1.2 SLM). Here, a substrate process was performed in which high-frequency power of 60 MHz and 1.2 KW was applied to the electrode 20 through the power introduction rod 29 to promote oxidation of the silicon oxide film formed on the glass substrate 11.
[0049]
The preferred embodiments and examples of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the embodiments and examples, and is understood from the description of the scope of claims. It can be changed into various forms within the scope.
[0050]
For example, the glass substrate 11 on which the substrate processing of further progressing the oxidation of the oxide film formed on the surface is performed is replaced with the glass substrate on which the ITO thin film is formed on the surface, under the same conditions as in the above embodiment. It is possible to perform substrate processing (processing for further oxidizing the ITO thin film).
[0051]
Further, the configuration of the entire apparatus including the substrate processing chamber 3 in which the substrate processing method of the present invention is performed, the load lock chamber 1, the transfer chamber 2, and the like is not limited to the form shown in FIGS. For example, instead of the configuration in which four substrate processing chambers 3 are provided as shown in FIG. 2, the number of substrate processing chambers 3 is reduced, and instead a film forming chamber (for example, a silicon-based thin film on the surface of the substrate). It is also possible to attach a CVD chamber in which a film is formed, a sputtering chamber in which an ITO film which is a transparent conductive thin film is formed on the substrate surface, or a heating chamber.
[0052]
【The invention's effect】
According to the method of the present invention, an oxide film such as a silicon oxide (SiO _x ) thin film or an ITO thin film formed on a substrate that does not require a large-scale annealing apparatus and realizes further progress of oxidation. A substrate treatment that promotes oxidation of the oxide film can be performed without directly contacting the surface of the substrate with plasma to compensate for the lack of oxidation in the oxide film.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an entire apparatus including a substrate processing apparatus in which the present invention is implemented.
2 is a plan view of FIG. 1. FIG.
FIG. 3 is a schematic cross-sectional view of a substrate processing apparatus in which the present invention is implemented.
FIG. 4 is a partially enlarged cross-sectional view of a conductive partition wall.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Load lock chamber 2 Transfer chamber 2a Robot arm 3 Substrate processing chamber 4a, 4b, 4c Gate valve 5 Exhaust valve 12 Vacuum container 12a Upper container 12b Lower container 12b-1 Exhaust port 13 Exhaust mechanism 14 Conductive partition part 15 Plasma production space 16 Substrate processing space 17 Substrate holder 18 Heater 19 Plasma 20 Electrode 20a Electrode holes 21a and 21b Insulating member 22 Conductive material fixing part 23 Plasma generating gas introduction pipe 25 Through hole 29 Power introduction rod 31 Insulator 41 Ground potential

Claims (3)

A substrate processing method for generating excited active species by generating plasma in a vacuum container and processing the substrate surface with the excited active species,
The inside of the vacuum vessel is separated into two chambers by a conductive partition wall, and one of the two separated chambers is a plasma generation space in which a high frequency electrode is arranged, and the other chamber is a substrate. Each is formed as a substrate processing space in which a substrate holding mechanism is placed,
Using a vacuum vessel in which the conductive partition wall has a plurality of through holes that let the plasma generation space and the substrate processing space pass through,
The plasma generation gas is supplied to the plasma generation space, and a high frequency power is applied to the high frequency electrode to generate a plasma discharge, thereby generating an excited active species of the plasma generation gas generated in the plasma generation space, Introduced into the substrate processing space through a plurality of through holes in the conductive partition wall;
In the substrate processing method, in the substrate processing space, processing the substrate with the excited active species introduced,
The plasma generation gas is a gas obtained by mixing a rare gas or a nitrogen gas with any one of O ₂ , O ₃ , H ₂ O, CO, CO ₂ , NO, NO ₂ , and N ₂ O. The plasma generating gas is supplied to a space opposite to the substrate with respect to the high-frequency electrode of the plasma generating space, and is introduced into the substrate processing space through a plurality of through holes of the conductive partition wall. The substrate processing method characterized in that the excited active species and the active species transitioned from the excited active species act on the oxide film formed on the substrate to promote the oxidation. 2. The substrate processing method according to claim 1, wherein the oxide film whose oxidation is promoted is a silicon oxide (SiO _x ) thin film or an ITO (indium tin oxide) thin film formed on the surface of the substrate to be processed.   The plurality of through holes provided in the conductive partition wall separating the inside of the vacuum chamber into two chambers have a gas flow velocity in the through hole u, a substantial through hole length L, 3. The substrate processing method according to claim 1, wherein the substrate diffusion method is formed so as to satisfy a condition of uL / D> 1, where D is a gas diffusion coefficient.

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