JP4430417B2 - Film forming apparatus and cleaning method thereof - Google Patents

Description

  The present invention relates to a film forming apparatus having a configuration in which a cleaning gas is excited outside a film forming chamber to generate radicals, and the cleaning gas containing the radicals is directly introduced into the film forming chamber without using a shower plate. And a cleaning method thereof.

  For example, in a film forming apparatus such as a plasma CVD apparatus, when a film forming process is repeated, a film is also formed on a portion other than the substrate that is a film forming target (such as a support portion on which the substrate is placed and supported or an inner wall of the film forming chamber) Will be deposited. Therefore, cleaning for removing the film is performed separately from the film forming process.

For example, in Patent Document 1, a cleaning gas containing radicals is introduced directly into a film formation chamber without using a shower plate used during film formation, thereby preventing radicals from disappearing when radicals pass through small holes in the shower plate. In this way, the cleaning efficiency is improved.
JP 2002-60949 A

  For example, in Patent Document 1, as one embodiment, as shown in FIG. 5, one cleaning gas introduction pipe 51 connected to the radical generation source 21 is connected to the central portion of the side wall 2 c of the vacuum chamber 2. 1 shows a configuration in which a cleaning gas containing radicals is introduced from the side 13c side of the substrate support portion 3a disposed in the film forming chamber 10 to support the substrate 9.

  As another embodiment, as shown in FIG. 6, the cleaning gas introduction pipe 52a connected to the radical generation source 21a is connected to a position near the side wall 2b in the side wall 2a and connected to the radical generation source 21b. The cleaning gas introduction pipe 52b is connected to a position near the side wall 2d in the side wall 2c, and a cleaning gas containing radicals is introduced from the opposite two sides 13a and 13c of the substrate support 3a, respectively. It is shown.

  As shown in FIG. 5, the cleaning gas containing radicals introduced into the film forming chamber 10 from the cleaning gas introduction pipe 51 advances the cleaning from a portion close to the gas introduction port, and a → b → c → As indicated by d, the cleaning area is expanded. In this case, the portions A, B, C, and D corresponding to the four corners of the substrate support portion 3a are difficult to reach the cleaning gas containing radicals, and are the last portions to be cleaned in the substrate support portion 3a. This tendency becomes larger as the film forming chamber 10 becomes larger, which increases the cleaning time.

  In addition, although the planar dimension of the film-forming chamber 10 is enlarged with the increase in the size of the substrate 9, the dimension in the height direction does not increase at the same rate as the planar dimension. Therefore, the gas introduction port formed in the side wall portion of the vacuum chamber 2 cannot be made so large in diameter due to the restriction of the height of the film forming chamber 10, and the amount of gas introduction cannot be made so large. Further, even if the amount of gas introduced from one place is increased, it takes time to reach the entire film forming chamber 10 which is enlarged. For this reason, radicals may disappear.

  Further, in the configuration of FIG. 6, it is possible to prevent a decrease in the cleaning speed in the portions A and C near the gas introduction ports of the cleaning gas introduction pipes 52a and 52b among the four corners A to D, but the portions B and B separated from the gas introduction ports. In D, the cleaning speed also decreases.

In other words, the conventional arrangement of the cleaning gas inlet is not sufficient for efficiently cleaning a film forming chamber corresponding to a substrate having a large size exceeding 1 m ² in particular. In particular, the four corners A to D of the substrate support portion 3a are more heavily soiled than the central portion covered with the substrate 9 during film formation, and improving the cleaning speed of the four corners A to D can improve the cleaning time of the entire film formation chamber. Leads to shortening.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to form a film that can be efficiently cleaned even if the substrate support portion and the film formation chamber that support the substrate become larger as the substrate becomes larger. An apparatus and a cleaning method thereof are provided.

  In solving the above problems, a film forming apparatus of the present invention is provided with a film forming chamber, a substantially rectangular substrate support disposed in the film forming chamber, and the substrate support. A shower plate having a large number of small holes for introducing a film forming gas into the film forming chamber, and a gas introducing port directly connected to the film forming chamber without passing through the shower plate, and the gas introducing port is a substrate. It is characterized by comprising at least four cleaning gas introduction pipes respectively directed to the four corners of the support portion, and a radical generation source provided outside the film forming chamber and connected to the cleaning gas introduction pipe.

  In order to solve the above problems, the method for cleaning a film forming apparatus according to the present invention includes a step of exciting a cleaning gas outside the film forming chamber to generate radicals, and a cleaning gas containing radicals in the film forming chamber. And a step of introducing directly into the film formation chamber without going through the shower plate for introducing the film formation gas toward the four corners of the substantially rectangular substrate support portion disposed in the substrate.

  In the present invention, cleaning is performed from the four corners, which are more easily contaminated than the central portion covered by the substrate during film formation, and where the cleaning gas is difficult to reach when the substrate support portion becomes larger as the substrate becomes larger. Thus, the cleaning speed at the four corners can be prevented from decreasing.

  Note that as the film forming chamber is increased in size, the cleaning gas tends to be less likely to reach the side portion (particularly the central portion of the side portion) that is the portion between the four corners of the substrate support portion. Therefore, in addition to the four corners, the cleaning gas may be introduced toward the side portion.

  Also, from the viewpoint of suppressing the disappearance of radicals before they are introduced into the film formation chamber, we want to generate radicals as close as possible to the gas inlet, so a radical generation source is prepared for each cleaning gas inlet tube. In addition, it is preferable to provide each radical generation source near the gas inlet of each cleaning gas inlet tube.

  According to the film forming apparatus or the cleaning method for the film forming apparatus of the present invention, the cleaning gas containing radicals is introduced toward the four corners of the substrate support portion, thereby improving the cleaning speed at the four corners, which has been apt to decrease in the past. As a result, the cleaning time for the entire film formation chamber can be shortened. In particular, the film formation chamber for large substrates can be effectively cleaned.

[First Embodiment]
(Structure of deposition system)
1 and 2 show a plasma CVD apparatus as an example of a film forming apparatus according to the first embodiment of the present invention. FIG. 1 is a longitudinal sectional view of the vacuum chamber 2, and FIG. 2 is a view of the film forming chamber 10 as viewed from above.

  The film forming apparatus 30 according to this embodiment includes a vacuum chamber 2 whose internal space functions as the film forming chamber 10. A cathode electrode 4 is provided on the upper wall portion of the vacuum chamber 2, and the anode electrode 3 is disposed in the film forming chamber 10 so as to face the cathode electrode 4. The cathode electrode 4 is connected to a high frequency power source 8 and the anode electrode 3 is grounded.

  As shown in FIG. 2, the upper surface of the anode electrode 3 has a substantially quadrangular shape (which may be square or rectangular) and functions as the substrate support portion 3 a. In addition, the substantially quadrangular shape is not limited to a right angle as illustrated. Also included are those with slightly rounded corners (curved).

  A film forming gas introduction pipe 15 is connected so as to penetrate the upper part of the cathode electrode 4. A shower plate 5 having a large number of small holes is attached to the lower portion of the cathode electrode 4. The shower plate 5 is opposed to the substrate support 3a and the substrate 9 placed thereon. The planar shape of the shower plate 5 has a rectangular shape, for example, in accordance with the rectangular substrate 9. The planar dimension of the shower plate 5 is larger than the planar dimension of the substrate 9.

  As shown in FIG. 1, an exhaust port 7 is formed at the bottom of the vacuum chamber 2. The exhaust port 7 is connected to a vacuum exhaust system including a vacuum pump and piping (not shown).

  Four radical generation sources 21a to 21d are provided outside the vacuum chamber 2 (see FIG. 2). The radical generation source 21 a is disposed in the vicinity of a corner formed by the side wall 2 a and the side wall 2 b of the vacuum chamber 2. The radical generation source 21b is disposed in the vicinity of a corner formed by the side wall 2b and the side wall 2c. The radical generation source 21c is disposed in the vicinity of a corner formed by the side wall 2c and the side wall 2d. The radical generation source 21d is disposed in the vicinity of a corner formed by the side wall 2d and the side wall 2a.

  The radical generation sources 21a to 21d are connected to cleaning gas introduction pipes 23a to 23d, respectively. A cleaning gas is supplied from a cleaning gas supply source (not shown) to each of the radical generation sources 21a to 21d.

  Specifically, each of the radical generation sources 21a to 21d is a chamber that temporarily stores the cleaning gas flowing from the cleaning gas supply source. In this chamber, the cleaning gas is activated by a high frequency of, for example, 400 kHz. The

  The cleaning gas introduction pipe 23a passes through a corner formed by the side wall 2a and the side wall 2b of the vacuum chamber 2, and the gas introduction port 20a is formed in the four corners A to D of the substrate support 3a (FIG. 2). In the upper left corner A). A valve 24 is provided between the gas inlet 20a and the outlet of the radical generation source 21a. The gas inlet 20a communicates directly with the film forming chamber 10 without using the above-described film forming shower plate 5.

  The cleaning gas introduction pipe 23b passes through a corner portion formed by the side wall 2b and the side wall 2c of the vacuum chamber 2, and the gas introduction port 20b has four corners A to D of the substrate support 3a (FIG. 2). In the upper right corner B). A valve 24 is provided between the gas inlet 20b and the outlet of the radical generation source 21b. The gas inlet 20b communicates directly with the film forming chamber 10 without using the film forming shower plate 5 described above.

  The cleaning gas introduction pipe 23c passes through a corner portion formed by the side wall 2c and the side wall 2d of the vacuum chamber 2, and the gas introduction port 20c has four corners A to D of the substrate support 3a (FIG. 2). In the lower right corner C). A valve 24 is provided between the gas inlet 20c and the outlet of the radical generation source 21c. The gas inlet 20c communicates directly with the film forming chamber 10 without using the film forming shower plate 5 described above.

  The cleaning gas introduction pipe 23d passes through a corner formed by the side wall 2d and the side wall 2a of the vacuum chamber 2, and the gas introduction port 20d has four corners A to D of the substrate support 3a (FIG. 2). In the lower left corner D). A valve 24 is provided between the gas inlet 20d and the outlet of the radical generation source 21d. The gas introduction port 20d communicates directly with the film forming chamber 10 without using the film forming shower plate 5 described above.

  In FIG. 1, the extending direction of the cleaning gas introduction pipes 23a and 23b is shown in parallel to the surface direction of the substrate support portion 3a. However, the cleaning gas blowing direction is as shown by the one-dot chain line. You may incline so that it may face the shower plate 5. FIG. At the time of film formation, a film is attached to the entire surface of the shower plate 5, but since the substrate 9 is placed on the substrate support portion 3a, no film is attached to the center portion. It is preferable to incline toward 5.

  Further, when the space for installing the radical generation source cannot be secured around the side walls 2a to 2d of the vacuum chamber 2, the radical generation source 21b is disposed below the vacuum chamber 2 as shown in FIG. The gas inlet port may be guided to the side wall portion side by bending the gas inlet tube 23b.

(Film formation process)
During film formation using the film formation apparatus 30 configured as described above, the film formation chamber 10 is evacuated through the exhaust port 7 and depressurized, and then a film formation gas (SiH ₄ gas, NH ₃ gas, etc.) is used. Is supplied to the shower plate 5 through the film forming gas introduction pipe 15, and the gas is uniformly ejected to the substrate 9 through a large number of small holes in the shower plate 5. Then, high frequency power is applied to the cathode electrode 4 by the high frequency power source 8 to decompose and react the introduced film forming gas, thereby depositing a thin film (for example, SiN _x film) on the substrate 9. At this time, the valves 24 of the cleaning gas introduction pipes 23a to 23d are closed. Note that the film formed on the substrate 9 is not limited to the SiN _x film, but may be a film of another material such as a SiO ₂ film.

(Cleaning process)
At the time of cleaning the film forming chamber 10, after the pressure inside the film forming chamber 10 is reduced through the exhaust port 7, for example, NF ₃ gas as a cleaning gas and Ar gas as a carrier gas are supplied to the radical generation sources 21a to 21d, For example, a high frequency of 400 kHz is used to apply a high frequency to the NF ₃ gas to generate fluorine radicals. Gas containing fluorine radicals is open and is a valve 24, and is introduced directly into the film forming chamber 10 through the respective cleaning gas introduction pipe 23 a to 23 d, fluorine radicals to be cleaned material (e.g. SiN _X film) The inside of the film forming chamber 10 is cleaned by a chemical reaction. The removed substance to be cleaned is exhausted from the exhaust port 7 together with the cleaning gas.

  Since radicals are directly introduced into the film forming chamber 10 which is a space to be cleaned without passing through the shower plate 5 having a small conductance, the generated radicals are prevented from disappearing before reaching the film forming chamber 10. Can be cleaned efficiently.

  Furthermore, in this embodiment, the cleaning gas containing radicals is introduced from the four corner directions of the vacuum chamber 2 as indicated by arrows in FIG.

  That is, a cleaning gas containing radicals is introduced from the gas introduction port 20a of the cleaning gas introduction pipe 23a toward the upper left corner A of the substrate support portion 3a (in FIG. 2). The cleaning gas from the gas introduction port 20a The cleaning area gradually expands from the upper left corner A as time passes, as indicated by a → b → c in FIG.

  Similarly, a cleaning gas containing radicals is introduced from the gas introduction port 20b of the cleaning gas introduction pipe 23b toward the upper right corner B of the substrate support portion 3a (in FIG. 2), and the cleaning gas from the gas introduction port 20b is introduced. The cleaning area due to is gradually expanded from the upper right corner B as time passes, as indicated by a → b → c in FIG.

  Similarly, a cleaning gas containing radicals is introduced from the gas introduction port 20c of the cleaning gas introduction pipe 23c toward the lower right corner C (in FIG. 2) of the substrate support 3a, and the cleaning gas from the gas introduction port 20c is introduced. The cleaning region due to, gradually expands from the lower right corner C as time passes, as indicated by a → b → c in FIG.

  Similarly, a cleaning gas containing radicals is introduced from the gas introduction port 20d of the cleaning gas introduction pipe 23d toward the lower left corner D (in FIG. 2) of the substrate support 3a, and the cleaning gas from the gas introduction port 20d is introduced. The cleaning area due to is gradually expanded from the lower left corner D as time passes, as indicated by a → b → c in FIG.

  As described above, in the present embodiment, the film is formed to be thicker than the central part covered by the substrate 9 at the time of film formation, and when the substrate supporting part 3a is enlarged as the substrate 9 is enlarged. Since the cleaning is started from the four corners A to D which are difficult to reach the cleaning gas, it is possible to prevent the cleaning speed at the four corners A to D from being lowered, and as a result, the cleaning time of the entire film forming chamber 10 can be shortened. .

  Further, in the present embodiment, the radical generation source 21a to 21d is connected to each of the cleaning gas introduction pipes 23a to 23d without sharing the radical generation source among the four cleaning gas introduction pipes 23a to 23d, And the connection position is made close to each gas inlet 20a-20d. Thereby, it is possible to avoid unnecessarily increasing the transport distance of radicals before being introduced into the film forming chamber 10, and to suppress the disappearance of radicals before being introduced into the film forming chamber 10. This also contributes to an improvement in cleaning efficiency.

  Further, since the radical generation sources 21 a to 21 d and the cleaning gas introduction pipes 23 a to 23 d are arranged at the four corners outside the vacuum chamber 2, the substrate 9 can be carried in and out through any side wall portion of the vacuum chamber 2. It won't interfere.

  Next, a description will be given of the results of comparison of cleaning speeds in the example corresponding to the first embodiment and Comparative Examples 1 to 3 under the same cleaning conditions.

  In Comparative Example 1, as shown in FIG. 7, two cleaning gas introduction pipes 53a and 53b are connected to the side wall 2c of the vacuum chamber 2, and radicals are included toward the one side 13c of the substrate support 3a. In this configuration, a cleaning gas is introduced.

  Comparative Example 2 has the configuration described in the above conventional example. As shown in FIG. 6, cleaning gas introduction pipes 52 a and 52 b are connected to two opposing side wall portions 2 a and 2 c of the vacuum chamber 2 to support the substrate. In this configuration, a cleaning gas containing radicals is introduced toward each of the two opposite side portions 13a and 13c of the portion 3a. The gas introduction port of the cleaning gas introduction pipe 52a is formed at a position close to the side wall 2b, and the gas introduction port of the cleaning gas introduction pipe 52b is formed at a position close to the side wall 2d.

  In Comparative Example 3, as shown in FIG. 8, cleaning gas introduction pipes 54a to 54d are connected to all of the side wall portions 2a to 2d of the vacuum chamber 2, and each of the four side portions 13a to 13d of the substrate support portion 3a is connected. For this, a cleaning gas containing radicals is introduced. The gas introduction ports of the cleaning gas introduction pipes 54a to 54d are respectively formed in the central portions of the side wall portions 2a to 2d.

In any of the examples and the comparative examples 1 to 3, the film forming chamber 10 has the same size, specifically, a size that can support the film formation of the substrate 9 having a size of (1100 mm × 1300 mm). A 1 μm film was formed and cleaned. The cleaning gas used was NF ₃ and Ar was used as the carrier gas. The total gas flow rate introduced into the film forming chamber 10 was 4 slm for both NF ₃ and Ar, and was introduced uniformly from each gas inlet.

  The comparison results of the cleaning speed are shown in Table 1 below. The cleaning speed shown in Table 1 is the value of the portion with the slowest cleaning speed.

As is apparent from this result, the cleaning speed with the highest example is obtained. Note that the cleaning speed of 780 nm / min obtained in the example is that the cleaning of the film forming apparatus corresponding to a small substrate having a substrate size of 400 mm × 500 mm (cleaning gas from one place toward the side of the substrate support portion). (Introduction) is almost the same as the value currently obtained. In other words, even in a film forming chamber corresponding to a large substrate exceeding 1 m ² , the present embodiment is different from a cleaning speed that is practically satisfactory and obtained with a film forming apparatus corresponding to a small substrate. You can get no value.

Although NF ₃ is used as the cleaning gas, the same effect can be obtained by using, for example, F ₂ gas that can generate fluorine radicals that become active species in the radical generation source.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. In addition, the same code | symbol is attached | subjected to the same component as the said 1st Embodiment, and the detailed description is abbreviate | omitted.

  In this embodiment, as shown in FIG. 3, the cleaning gas is introduced from the four corners on the assumption that a larger substrate or a plurality of substrates are placed on the substrate support portion 103a for film formation. In addition, a cleaning gas containing radicals is also introduced toward the center of each of the two opposite sides 113b and 113d on the long side of the rectangular substrate support 103a.

  That is, the cleaning gas introduction pipe 23e is connected to the central part of the side wall part 102b of the vacuum chamber 102, and the cleaning gas introduction pipe 23f is connected to the central part of the side wall part 102d facing the side wall part 102b. The cleaning gas introduction pipes 23e and 23f are connected to radical generation sources 21e and 21f, respectively.

  In the case where the long side portions 113b and 113d become longer, a cleaning gas introduction pipe for introducing a cleaning gas toward the side portions 113b and 113d may be additionally provided.

  In the present embodiment, the substrate is carried in and out from either side of the short side wall portions 102a and 102c to which the cleaning gas introduction pipe is not connected.

  As mentioned above, although each embodiment of this invention was described, of course, this invention is not limited to these, A various deformation | transformation is possible based on the technical idea of this invention.

The cleaning gas is not limited to NF ₃ , and other gases such as F ₂ , CF ₄ , C ₂ F ₆ , C ₃ F ₃ , CHF ₃ , and SF ₆ may be used. Further, the carrier gas is not limited to Ar gas, and other inert gas may be used.

  Examples of the substrate to be deposited include a liquid crystal substrate, a semiconductor substrate, and other electronic device substrates.

It is a longitudinal cross-sectional view of the film-forming apparatus which concerns on the 1st Embodiment of this invention. It is a cross-sectional view of the film forming apparatus according to the first embodiment. It is a cross-sectional view of the film-forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the modification of the arrangement position of a radical production | generation source. It is a cross-sectional view of a conventional film forming apparatus. It is a cross-sectional view of the film-forming apparatus of another prior art example. 6 is a cross-sectional view of a film forming apparatus of Comparative Example 1. FIG. 10 is a cross-sectional view of a film forming apparatus of Comparative Example 2. FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 2 ... Vacuum chamber, 3 ... Anode electrode, 3a ... Substrate support part, 4 ... Cathode electrode, 5 ... Shower plate, 9 ... Substrate, 10 ... Film-forming chamber, 15 ... Film-forming gas introduction pipe, 20a-20d ... Gas introduction Mouth, 21a to 21f ... radical generation source, 23a to 23f ... cleaning gas introduction tube, 30 ... film forming apparatus, 102 ... vacuum chamber, 103 ... anode electrode, 103a ... substrate support, AD ... four corners of substrate support .

Claims (8)

A deposition chamber;
A substantially square substrate support disposed in the film forming chamber;
A shower plate disposed opposite to the substrate support and having a large number of small holes for introducing a film forming gas into the film forming chamber;
At least four cleaning gas introduction pipes each having a gas introduction port communicated directly into the film forming chamber without passing through the shower plate, the gas introduction ports being respectively directed to the four corners of the substrate support;
And a radical generation source provided outside the film formation chamber and connected to the cleaning gas introduction pipe.   2. The film forming apparatus according to claim 1, further comprising a cleaning gas introduction pipe having a gas introduction port directed to each of two opposing sides of the substrate support in addition to the four corners. .   The film forming apparatus according to claim 2, wherein the substrate support portion has a rectangular shape, and the two side portions are two long side portions.   The film forming apparatus according to claim 2, wherein the gas inlet is directed to a substantially central portion of each of the two side portions.   5. The film forming apparatus according to claim 1, wherein a plurality of the radical generation sources are provided corresponding to each of the plurality of cleaning gas introduction pipes. A step of generating radicals by exciting a cleaning gas outside the deposition chamber;
A method of cleaning a film forming apparatus, including a step of introducing the cleaning gas containing radicals directly into the film forming chamber without using a shower plate for introducing a film forming gas,
A cleaning method for a film forming apparatus, wherein the cleaning gas containing radicals is introduced toward the four corners of a substantially rectangular substrate support provided in the film forming chamber.   The film forming apparatus cleaning method according to claim 6, wherein the cleaning gas containing the radicals is introduced not only to the four corners but also toward two opposing sides of the substrate support.   The cleaning method for a film forming apparatus according to claim 7, wherein a cleaning gas containing the radicals is introduced toward a substantially central portion of each of the two side portions.

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