JP4544898B2 - Method for forming ZnO film - Google Patents

Description

  The present invention relates to a ZnO film forming method for forming a ZnO film on the surface of an object to be processed by at least a Zn source gas and an O source gas.

As a ZnO epitaxial film used for a light emitting element such as a white light emitting diode (LED), an MBE (Molecular Beam Epitaxy) apparatus or an MO-CVD (Metal Organic-Chemical Vapor Deposition) apparatus is generally employed as a film forming apparatus. ing. In these apparatuses, plasma or laser is used to assist the decomposition of the source gas, thereby increasing the formation efficiency of the ZnO film.
Japanese Patent No. 2715299

  As in the MBE apparatus and the MO-CVD apparatus, assembling the plasma source and the laser source into the film forming apparatus has a problem that the structure becomes complicated and the equipment cost increases. Further, adding a plasma source or a laser source to an existing film forming apparatus has the same problem as the above case. Furthermore, the use of plasma or the like further activates the decomposition of the source gas, but on the other hand, particles are more likely to be generated due to by-product deposition, which may cause adverse effects on film quality degradation and the like.

  The present invention has been made in view of the above circumstances, and provides a method for forming a ZnO film by introducing decomposition gas into a processing space and promoting the growth of ZnO film formation without any special equipment modification. With the goal.

In order to achieve the above object, a ZnO film forming method according to the present invention supplies at least a Zn source gas and an O source gas into a processing space and is exposed to the processing space by the both source gases. A ZnO film forming method for forming a ZnO film on the surface of a ZnO film while introducing at least hydrogen gas as a decomposition gas that promotes decomposition of either of the two source gases into the processing space. The gist of the present invention is that when the films are formed, both the raw material gases and the decomposition gas are not radicalized, and the decomposition gas is supplied into the processing space separately from the two raw material gases.

In the ZnO film forming method of the present invention, a ZnO film is formed while introducing at least hydrogen gas as a decomposition gas that promotes decomposition of either of the two source gases into the processing space. For this reason, since the decomposition of either of the two source gases is promoted by the decomposition gas, the growth rate of the film formed on the surface of the object to be processed is improved, and the formation time of the ZnO film is shortened. , Improve productivity. Further, in the case of a film forming apparatus for heating an object to be processed to form a film, it is effective to reduce the heat energy cost for heating by shortening the film forming time. Since cracked gas is used as a means for decomposing the source gas, it is possible to avoid using plasma and laser as in the prior art, and it is effective for simplifying the structure of the film forming equipment and reducing equipment costs. At the same time, particles due to by-product accumulation are less likely to occur, and film quality degradation and the like can be avoided. Further, as a decomposition gas, Ri by the fact that select an effective hydrogen gas decomposition accelerator for the organic metal material is a Zn material, even in a low temperature range where the organic metal material is less likely to decompose, the surface of the hydrogen treatment object Therefore, the decomposition effect of the organometallic material is exhibited, and favorable film growth is achieved. Thus, because of the selection of hydrogen gas, a minute amount of moisture H _{2 O} is generated by the reaction between O material gases especially oxygen, which makes the base point of the reaction reacts with a portion of the organometallic material is a Zn material , Zn + O → ZnO is promoted.
In the ZnO film forming method of the present invention, since the radicals of both the raw material gas and the decomposition gas are not used, it is possible to avoid the use of plasma, laser, high frequency discharge, microwave discharge, etc. It is effective for simplification and reduction of equipment costs, and particles due to by-product accumulation are less likely to be generated, so that deterioration of film quality and the like can be avoided.
Further, in the ZnO film forming method of the present invention, since the decomposition gas is supplied into the processing space separately from the two source gases, only the decomposition gas is processed through an independent flow path, that is, a third supply flow path. Since it is supplied into the space, it becomes easy to adapt to various conditions such as the type of decomposition gas, the flow rate, and the ejection state of the object to be processed.

  Next, the best mode for carrying out the present invention will be described.

  In the ZnO film forming method of the present invention, at least a Zn source gas and an O source gas are supplied into the processing space, and the ZnO film is formed on the surface of the object exposed to the processing space by the two source gases. The present invention relates to a method for forming a ZnO film. In the present invention, a ZnO film is formed while introducing a decomposition gas that promotes decomposition of at least one of the two source gases into the processing space.

  The present invention relates to a film forming method using MBE (Molecular Beam Epitaxy) or MO-CVD (Metal Organic-Chemical Vapor Deposition). Therefore, the processing space is decompressed by a vacuum pump or the like, and then a predetermined source gas is introduced, and the source gas is supplied under a decompression condition or a normal pressure condition.

The object to be processed is arranged in the processing space, and generates a ZnO film on the surface of the object to be processed by being injected with a raw material gas to the surface. Specifically, as the object to be processed, various substrates such as a sapphire substrate, a ZnO substrate, a SiC substrate, and a ScAlMgO ₄ substrate can be used, and are not particularly limited.

The Zn source gas is a source gas serving as a Zn source for generating a ZnO film, and various gases such as diethyl zinc (DEZn), DMZn, Zn (C ₅ H ₇ O ₂ ) can be used. There is no particular limitation.

The O source gas is a source gas serving as an O source for generating a ZnO coating, and various gases such as oxygen, nitrous oxide, N ₂ O, NO, and H ₂ O can be used. It is not limited.

The cracked gas is introduced into the processing space at the same time as the source gas and promotes the decomposition of either of the source gases. As the cracked gas, various gases can be used as long as they promote the decomposition of the raw material gas, and are not particularly limited. Specifically, a gas containing H or H group is preferably used. be able to. For example, acetylene (C ₂ H ₂ ), ethylene (C ₂ H ₄ ), benzene (C ₂ H ₆ ), or the like can be used as hydrogen gas or a gas containing H or H groups other than hydrogen gas.

As the decomposition gas, hydrogen gas is particularly preferably used. By using hydrogen gas as the cracking gas, the hydrogen gas effectively acts as a cracking gas in promoting the decomposition of the organometallic material that is the Zn source, and the Zn element is decomposed from the Zn source gas. Reacts with the O source gas and the formation of a good ZnO film proceeds. Furthermore, since hydrogen tends to stay on the surface of the object to be processed even in a low temperature range where the organic metal material is difficult to decompose, the decomposition effect of the organic metal material is exhibited and favorable film growth is achieved. Since hydrogen gas is used as a means for decomposing the source gas, it is possible to avoid using plasma or laser as in the prior art, and it is effective for simplifying the structure of the film forming equipment and reducing equipment costs. Furthermore, by using hydrogen gas as the cracked gas, a trace amount of water H ₂ O is generated by reaction with O source gas, particularly oxygen, and this reacts with a part of the organometallic material that is Zn source to set the base point of the reaction. The reaction of Zn + O → ZnO is promoted.

  In the ZnO film forming method of the present invention, the ZnO film is formed while introducing a decomposition gas that promotes decomposition of at least one of the two source gases into the processing space.

By doing so, the decomposition of either of the two source gases is promoted by the decomposition gas, so that the growth rate of the film formed on the surface of the object to be processed is improved and the formation of the ZnO film is formed. Time is shortened and productivity is improved. Further, in the case of a film forming apparatus for heating an object to be processed to form a film, it is effective to reduce the heat energy cost for heating by shortening the film forming time. Since cracked gas is used as a means for decomposing the source gas, it is possible to avoid using plasma and laser as in the prior art, and it is effective for simplifying the structure of the film forming equipment and reducing equipment costs. At the same time, particles due to by-product accumulation are less likely to occur, and film quality degradation and the like can be avoided. Furthermore, it is possible to select a hydrogen gas that is effective for promoting the decomposition of the organometallic material, which is a Zn raw material, as a decomposition gas. Therefore, the decomposition effect of the organometallic material is exhibited, and favorable film growth is achieved. As described above, when hydrogen gas is selected, a trace amount of water H ₂ O is generated by reaction with O source gas, particularly oxygen, and this reacts with a part of the organometallic material that is Zn source, and the reaction base point. And the reaction of Zn + O → ZnO is promoted.

  In the ZnO film forming method of the present invention, it is preferable that the volume ratio of the decomposition gas to the source gas to be decomposed in the processing space is less than 10 times the capacity. In this way, an appropriate source gas is decomposed by the cracked gas, and a reduction action or the like by the cracked gas is hardly caused. On the contrary, an efficient film formation is performed. It is.

  In the ZnO film forming method of the present invention, it is preferable that the decomposition gas is introduced into the processing space at a flow rate less than 10 times the flow rate of the raw material gas to be decomposed. In this way, an appropriate source gas is decomposed by the cracked gas, and a reduction action or the like by the cracked gas is hardly caused. On the contrary, an efficient film formation is performed. It is. Further, the volume ratio of the decomposition gas to the raw material gas can be controlled very easily and accurately, the film formation speed and film quality can be easily controlled, and it is advantageous for the simplification of the apparatus for realizing the film formation method. At this time, in order to more accurately control the volume ratio of the cracked gas to the source gas, it is preferable to start introduction of both the source gas and the cracked gas into the processing space at the same time.

  If the volume ratio of the cracked gas to the raw material gas to be decomposed in the processing space or the flow rate of the cracked gas with respect to the flow rate of the raw material gas to be decomposed is 10 times or more, a reduction reaction by the cracked gas occurs, and the reaction is completed. The surface of the deposited ZnO film is etched by the reducing action, and the deposition rate is reduced. In addition, the surface of the ZnO film is not mirror-finished, and the surface state is roughened, which may lead to performance degradation when the ZnO film is used as a semiconductor.

  The volume ratio of the cracked gas to the raw material gas to be decomposed in the processing space and the flow rate of the cracked gas with respect to the flow rate of the raw material gas to be decomposed can obtain a desired effect if it is less than 10 times Since it is more preferable, it is 0.5 times or more and less than 10 times, and more preferably 1 time or more and less than 10 times.

The pressure level in the processing space during the generation of the ZnO film is not particularly limited, and film formation can be performed at various pressure levels from a normal pressure level to a high vacuum level. Specifically, 10 ⁻² Torr (about 1.33 Pa) level, 10 ⁻³ Torr (about 0.133 Pa) level, 10 ⁻⁴ Torr (about 0.0133 Pa) level, 10 ⁻⁵ Torr (about 0.00133 Pa) ) Level film formation is possible.

  In the ZnO film forming method of the present invention, it is preferable not to radicalize both the raw material gas and the decomposition gas. By doing so, it is possible to avoid the use of plasma, laser, high frequency discharge, microwave discharge, etc., which is effective in simplifying the structure of the film forming equipment and reducing equipment costs, and also by particles generated by by-product deposition. Is less likely to occur, and film quality degradation and the like can be avoided.

  In the ZnO film forming method of the present invention, it is preferable to supply the decomposition gas and the source gas to be decomposed into the processing space from a common supply channel. By doing so, the source gas to be decomposed is decomposed by the decomposition gas in the common supply flow path, and the decomposed source gas is in a state in which film growth is easily promoted on the surface of the object to be processed. To reach. For this reason, the growth rate of film formation is increased, and the productivity is improved.

  In the ZnO film forming method of the present invention, a source gas different from the source gas to be decomposed may be supplied into the processing space separately from the decomposition gas and the source gas to be decomposed. Is preferred. By doing so, the flow path through which the raw material gas to be decomposed and the cracked gas circulates, that is, the first supply flow path that is the common supply flow path, and the flow path through which other different raw material gases circulate, that is, the first flow path. The two supply flow paths are established separately and independently. For this reason, the source gas and the cracked gas that circulate through the first supply channel can be supplied to the surface of the object to be processed in a state separated from other different source gases that circulate through the second supply channel, The supply state of the source gas decomposed by the decomposition gas on the surface of the object to be processed and other different source gases are optimized for the film formation or the improvement of the film growth rate.

  In the ZnO film forming method of the present invention, it is preferable that the decomposition gas is supplied into the processing space separately from the two source gases. By doing so, only the cracked gas is supplied into the processing space via the independent flow path, that is, the third supply flow path, so that the various conditions such as the type of cracked gas, the flow rate, and the ejection state of the object to be processed are met. It is easier to adapt.

  In the ZnO film forming method of the present invention, the source gas to be decomposed by the decomposition gas is preferably a Zn source gas. By doing so, the Zn element is decomposed from the Zn source gas, and the Zn element reacts with the O source gas, so that a good ZnO film is formed. Furthermore, since hydrogen gas that is effective in promoting the decomposition of the organometallic material that is the Zn raw material can be selected as the decomposition gas, hydrogen can be removed from the surface of the workpiece even in a low temperature range where the organometallic material is difficult to decompose. Therefore, the decomposition effect of the organometallic material is exhibited, and favorable film growth is achieved.

  In the ZnO film forming method of the present invention, it is preferable that the Zn source gas, the O source gas, and the decomposition gas are jetted from the jetting opening close to the surface of the object to be processed. By doing so, since Zn source gas, O source gas and decomposition gas from each ejection opening flow out from the approached location, the decomposition of the source gas and the subsequent reaction with other source gases are excellent in film formation. Progress in a state that is appropriate for proper growth.

  In the ZnO film forming method of the present invention, it is preferable that one of the ejection openings is the common supply channel. By doing so, since the source gas to be decomposed is ejected from one of the ejection openings in a state of being decomposed by the decomposition gas, the source gas to be decomposed is in a good decomposition state. Then, it reaches the surface of the object to be processed in a state where film growth is easily promoted. For this reason, the growth rate of film formation is increased, and the productivity is improved.

  In the method for forming a ZnO film of the present invention, the Zn source gas, the O source gas, and the decomposition gas are independently introduced into a plurality of diffusion chambers, and each Zn source gas, It is preferable that the O source gas and the cracked gas are injected independently. By doing so, even if there is a pulsation or turbulent flow state in each gas flow, it is buffered in each diffusion chamber, so that each gas flow flowing out from each ejection opening becomes a rectified state, and The atmosphere of the processing gas acting on the surface is optimized for film formation and improvement of the formation speed. In addition, since the first supply channel, the second supply channel, and the third supply channel branch from each diffusion chamber and communicate with each ejection opening, the amount of outflow gas at each ejection opening becomes substantially uniform. The film growth on the surface of the object to be processed proceeds uniformly without unevenness, and better film quality can be ensured.

  1 to 3 show a first example of a film forming apparatus for realizing the film forming method of the present invention.

  In the following description, hydrogen gas is used as a decomposition gas for the Zn source gas, and a ZnO film on the surface of the object to be processed is formed at a high film growth rate together with the O source gas.

  FIG. 1 is a cross-sectional view showing the overall structure of the film forming apparatus. In this apparatus, a separation plate 3 is provided in a processing vessel 2 whose inside is a processing space 1, and a plate-like sapphire substrate 5 which is an object to be processed is aligned with an opening 4 opened in the separation plate 3. It is placed. A heater H is disposed above the back surface of the sapphire substrate 5 to form a heating area 1A. The processing space 1 below the separation plate 3 and the sapphire substrate 5 is a growth area 1B to which various processing gases are supplied. A vacuum pump (not shown) for evacuating the processing space 1 is arranged so that the processing space 1 is evacuated from the exhaust port 6. Reference numeral 8 denotes a heating reflector.

  The processing gas, that is, the raw material gas or the decomposition gas is supplied to the sapphire substrate 5 from the supply flow path to the processing space 1 or the growth area 1B. In this example, the processing gas supplied into the growth area 1B passes through the gas ejection head 7. The gas ejection head 7 is disposed in the growth area 1B on the lower side of the separation plate 3 and the sapphire substrate 5 placed thereon. A CVD (Chemical Vapor Deposition) process is performed on the surface of the sapphire substrate 5 by the processing gas ejected from the gas ejection head 7 to form a ZnO epitaxial film or an insulating oxide film used for a light emitting element such as a white LED or the like. A metal film or the like for wiring is formed.

In the first example, a Zn source gas and an O source gas are used as source gases, and a hydrogen gas that is a gas containing H or H groups is used as a decomposition gas for the Zn source gas. As the source gas, DEZn (diethyl zinc) is adopted as the Zn source gas, and oxygen (O ₂ ) and nitrous oxide (N ₂ O) are adopted as the O source gas. A ZnO film is formed on the surface of the sapphire substrate 5 using the above-described source gas or decomposition gas.

  The gas ejection head (also referred to as a shower head) 7 is partitioned into a first diffusion chamber 10 and a second diffusion chamber 11 via a partition plate 9, and the first diffusion chamber 10 has a later-described structure. A first supply channel 15 is opened, and a second supply channel 16 described later is opened in the second diffusion chamber 11. An opening plate 12 is disposed on the sapphire substrate 5 side of the second diffusion chamber 11 so as to face the sapphire substrate 5. As shown in an enlarged view in FIG. 2, a plurality of ejection openings 13, 14 are arranged on the opening plate 12 in a close state. One ejection opening 13 is a circular hole 13A provided directly in the aperture plate 12, and the other ejection opening 14 is a pipe 14A having a circular cross section smaller in diameter than the ejection opening 13. The hole 13A communicates with the second diffusion chamber 11, and the pipe 14A penetrates the partition plate 9 and communicates with the first diffusion chamber 10. Therefore, the ejection opening 13, that is, the hole 13 </ b> A, and the ejection opening 14, that is, the pipe 14 </ b> A are arranged concentrically and have a close positional relationship.

  Through the first supply flow path 15, DEZn gas to be decomposed and hydrogen gas, which is a decomposition gas with respect to the DEZn gas, flow at the predetermined flow rate ratio described above. That is, the first supply channel 15 functions as a common supply channel of the present invention. Mass flow controllers (flow rate controllers) 19 and 20 are disposed in the DEZn gas and hydrogen gas flow paths 17 and 18, respectively, and both flow paths 17 and 18 are connected to the switching valve 21. A supply passage 15 is connected and a vent passage 21A is connected. The DEZn gas and the hydrogen gas are set to the above-described predetermined flow rates by the mass flow controllers (flow rate controllers) 19 and 20, respectively, and are discharged out of the system from the vent passage 21A through the processing equipment (not shown) in the initial stage. Is done. Thereafter, the switching valve 21 is switched after the flow ratio between the two gases is stabilized at a predetermined value, whereby DEZn gas and hydrogen gas are simultaneously supplied to the first diffusion chamber 10.

  Through the second supply channel 16, oxygen, which is an O source gas, and nitrous oxide flow at a predetermined flow rate ratio. Mass flow controllers (flow rate controllers) 24 and 25 are disposed in the oxygen and nitrous oxide channels 22 and 23, respectively. Both channels 22 and 23 are connected to the switching valve 26, and the switching valve 26 is connected to the second channel. A supply passage 16 is connected, and a vent passage 26A is connected. Oxygen and nitrous oxide are set to predetermined flow rates by mass flow controllers (flow rate controllers) 24 and 25, respectively, and are released out of the system from the vent passage 26A through a treatment facility (not shown) in the initial stage. . Thereafter, the switching valve 26 is switched after the flow ratio between the two gases is stabilized at a predetermined value, whereby oxygen and nitrous oxide are supplied to the second diffusion chamber 11. In addition, since oxygen and nitrous oxide do not particularly interact with each other, they can be supplied in a mixed state from the second supply channel 16 which is a common passage as described above, but oxygen and nitrous oxide are supplied separately. It can also be supplied in a flow path. By separately supplying in this way, the valve device for setting the supply ratio of both gases is simplified.

  As described above, the first supply flow path 15 and the second supply flow path 16 are provided separately, and the DEZn gas to be decomposed flows through the first supply flow path 15 and is supplied to the first diffusion chamber 10. Is done. On the other hand, oxygen and nitrous oxide that are not subject to decomposition flow through the second supply channel 16 and are supplied to the second diffusion chamber 11.

  The Zn source gas, hydrogen gas, and the like flowing through the first supply channel 15 are decomposed by the hydrogen gas while they are flowing, and the Zn source gas is in a good decomposition state from the pipe 14A to the sapphire substrate. 5 is supplied to the surface. Accordingly, the first supply flow path 15 includes a pipe member 15A extending from the switching valve 21, the first diffusion chamber 10 in which the pipe member 15A is open, and a pipe extending from the first diffusion chamber 10 to the opening plate 12. 14A. In addition, since the O source gas flowing through the second supply channel 16 starts to react with the Zn element decomposed from the position where it exits the opening plate 12, switching is performed in the same manner as the first supply channel 15. It exists from the valve 26 to the hole 13A.

  The operation of the film forming apparatus will be described in relation to the ZnO film forming sequence shown in FIG. The film forming sequence of the film forming apparatus is in three stages: substrate cleaning, buffer layer growth, and high temperature layer growth.

The first substrate cleaning is performed in order to control the state of the film growth surface of the sapphire substrate 5 and promote the growth of film formation, and as a method thereof, heat treatment is performed in a vacuum or in a gas atmosphere. In this example, the temperature of the sapphire substrate heated by the heater H is kept at about 1000 ° C. in a hydrogen gas atmosphere. At this stage of substrate cleaning, DEZn, O ₂ and N ₂ O are not supplied. In order to carry out the substrate cleaning, the processing space 1 is brought into a vacuum state, and the mass flow controller (flow rate controller) 20, the switching valve 21 and the control device (not shown) for the heater H are operated to generate hydrogen gas. In the atmosphere, the temperature of the sapphire substrate 5 is kept at about 1000 ° C. Hydrogen gas in substrate cleaning is supplied from the first supply flow path 15 to the first diffusion chamber 10 and is sprayed from the pipe 14 </ b> A to the surface of the sapphire substrate 5.

The next step, buffer layer growth, is performed to grow a ZnO single crystal film at a low temperature and to facilitate the subsequent high-temperature layer growth. After completion of the substrate cleaning, the processing space 1 is maintained in a vacuum state, and the controller of the heater H is operated to stabilize the temperature of the sapphire substrate 5 at about 400 ° C. in about 5 minutes. After this stable state, the switching valves 21 and 26 are switched so that DEZn and H ₂ are supplied from the first supply flow path 15 to the first diffusion chamber 10 at a predetermined flow rate ratio, and the pipe 14A is After that, it is sprayed on the surface of the sapphire substrate 5. Simultaneously with this spraying, O ₂ and N ₂ O are supplied from the second supply channel 16 to the second diffusion chamber 11 at a predetermined flow rate ratio, and sprayed onto the surface of the sapphire substrate 5 through the holes 13A. As described above, the DEZn gas is sprayed onto the surface of the sapphire substrate 5 together with O ₂ and N ₂ O while being decomposed by H ₂ , and the buffer layer is grown. The target film thickness of the ZnO single crystal film formed at this stage is 30 to 40 nm.

In the final high-temperature layer growth, the sapphire substrate temperature is set to 600 to 800 ° C., and ZnO film formation is performed. At this stage, in order to advance the reliable film formation, the degree of vacuum is increased before supplying the processing gas such as each source gas and decomposition gas, and the control device of the heater H is operated to operate the sapphire substrate 5. The temperature is maintained at a high temperature of 600 to 800 ° C., and thereafter, each mass flow controller (flow controller) 19, 20, 24, and 25 and the switching valves 21 and 26 are operated in the same manner as the buffer layer growth stage. The growth pressure at this stage is 10 ^{−3 to 1} Pa (10 ⁻⁵ to 10 ⁻² Torr). Thus, DEZn and H ₂ are supplied from the first supply flow channel 15 to the first diffusion chamber 10 at a predetermined flow rate ratio, and are sprayed onto the surface of the sapphire substrate 5 through the pipe 14A. Simultaneously with this spraying, O ₂ and N ₂ O are supplied from the second supply channel 16 to the second diffusion chamber 11 at a predetermined flow rate ratio, and sprayed onto the surface of the sapphire substrate 5 through the holes 13A. As described above, while the DEZn gas is decomposed into Zn element by H ₂ , it is jetted onto the surface of the sapphire substrate 5 together with O ₂ and N ₂ O, and the Zn element reacts with the O source gas, and the growth of the ZnO film formation occurs. Figured. Thereafter, when a predetermined film thickness is reached, the supply of each gas is stopped, the heating of the heater H is also stopped, and the sapphire substrate 5 is taken out from the film forming apparatus. The reaction formulas in the buffer layer growth and the high temperature layer growth are Zn + O → ZnO and Zn + N ₂ O → ZnO + N ₂ . The target film thickness of the ZnO film formed at this stage is 2 μm.

At the stage of the high temperature layer growth, since the temperature is high, it is necessary to prevent the reduction from proceeding from the surface layer of the ZnO film. For this purpose, O ₂ and N ₂ O are kept flowing even after the supply of DEZn and H ₂ is stopped while maintaining the vacuum state, and the heating temperature is lowered. By taking such measures to prevent reduction, the thickness of the ZnO film formation can be ensured normally, and the film formation time can be shortened. The O ₂ and N ₂ O supply extension time is indicated by the symbol T in FIG.

In the first example, the sapphire substrate 5 is an object to be processed, but it is also possible to use this as a ZnO substrate and form a ZnO film on the surface thereof by homo-growth. In the first example, O ₂ and N ₂ O are supplied at a predetermined flow rate ratio, but O ₂ and N ₂ O can be supplied separately and separately.

  With the configuration of the first example, the decomposition of DEZn, which is the Zn source gas, is promoted by hydrogen gas, which is the decomposition gas, so that it is formed on the surface of the sapphire substrate 5 by the reaction between the decomposed Zn element and oxygen. The growth rate of the ZnO film is improved, the formation time of the ZnO film is shortened, and the productivity is improved. Further, in the case of a film forming apparatus that heats the sapphire substrate 5 to form a film, it is effective to reduce the heat energy cost for heating by shortening the film forming time. Since hydrogen gas is used as a gas for decomposing Zn source gas, it is possible to avoid the use of plasma and laser as in the prior art, and it is effective for simplifying the structure of film deposition equipment and reducing equipment costs. . Furthermore, since hydrogen gas that is effective for promoting decomposition of the organometallic material that is the Zn raw material can be selected as the decomposition gas, hydrogen can be removed from the surface of the sapphire substrate 5 even in a low temperature range where the organometallic material is difficult to decompose. Therefore, the decomposition effect of the organometallic material is exhibited, and favorable film growth is achieved.

On the other hand, since hydrogen gas can be selected as the decomposition gas as described above, a trace amount of water H ₂ O is generated by reaction with O source gas, particularly oxygen, and this is part of the organometallic material that is Zn source. The base point of reaction is made by reaction, and the reaction of Zn + O → ZnO is promoted. Furthermore, the reaction of Zn + O → ZnO is promoted by adding water (H ₂ O) as an O raw material.

  In the first supply flow path 15, the DEZn gas to be decomposed is decomposed into Zn element by hydrogen gas, which is the decomposition gas, and the decomposed DEZn gas promotes film growth on the surface of the sapphire substrate 5. Reach easily. For this reason, the growth rate of film formation is increased, and the productivity is improved.

The flow path through which DEZn gas and hydrogen gas to be decomposed flow, that is, the first supply flow path 15, and the flow path through which O raw material gas, which is another different raw material gas, flows, that is, the second supply flow path 16, are separately provided. It is established in an independent state. For this reason, DEZn gas and hydrogen gas flowing through the first supply flow channel 15 are supplied to the surface of the sapphire substrate 5 in a state of being separated from other O source gases flowing through the second supply flow channel 16. Thus, the supply state of Zn element decomposed with hydrogen gas or O source gas on the surface of the sapphire substrate 5 is optimized for film formation or for improving the film growth rate. In addition, the film quality can be improved and the number of particles can be reduced. Since DEZn gas and hydrogen gas are supplied from the first supply flow path 15, the generation of H ₂ O by the reaction with the O source gas is caused by the sapphire substrate 5. This is considered to be because the surface is limited.

  In the processing space 1 (growth area 1B), the Zn source gas, the O source gas, and the decomposition gas are jetted to the surface of the sapphire substrate 5 with a plurality of jet openings, that is, a hole 13A and a pipe 14A in a close positional relationship. Since the Zn source gas, the O source gas, and the decomposition gas from the holes 13A and the pipes 14A flow out from close locations, the decomposition of the source gas and the subsequent reaction are in an appropriate state for good growth of the film formation. Proceed with Furthermore, by arranging a plurality of combinations of the plurality of ejection openings, for example, the holes 13A and the pipes 14A in accordance with the size of the sapphire substrate 5, the processing gas atmosphere for forming the ZnO film can be formed satisfactorily. Can do.

  Since the pipe 14A out of the hole 13A and the pipe 14A serves as the first supply passage 15, the Zn raw material gas is ejected from one of the pipes 14A in a state of being decomposed by hydrogen gas. The Zn source gas to be decomposed is in a good decomposition state and reaches the surface of the sapphire substrate 5 in a state in which film growth is easily promoted. For this reason, the growth rate of film formation is increased, and the productivity is improved.

  Since the source gas to be decomposed of the cracked gas is a Zn source gas, the Zn element is decomposed from the Zn source gas, and the Zn element reacts with the O source gas, so that a good ZnO film is formed. To do. Furthermore, since hydrogen gas that is effective for promoting the decomposition of the organometallic material that is the Zn raw material is selected as the decomposition gas, hydrogen can be present on the surface of the sapphire substrate 5 even in a low temperature range where the organometallic material is difficult to decompose. Since it is easy to stay, the decomposition effect of the organometallic material is exhibited, and favorable film growth is achieved.

  The hydrogen gas acts as a decomposition gas, effectively acts to promote the decomposition of the organometallic material that is the Zn raw material, and hydrogen tends to stay on the surface of the sapphire substrate 5 even in a low temperature range where the organometallic material is difficult to decompose. The decomposition effect of the organometallic material is exhibited and good ZnO film growth is achieved. Since hydrogen gas is used as a means for decomposing the source gas, it is possible to avoid using plasma or laser as in the prior art, and it is effective for simplifying the structure of the film forming equipment and reducing equipment costs.

  A flow path for supplying hydrogen gas into the processing space 1 can be provided separately from the first supply flow path 15 for supplying Zn source gas and the second supply flow path 16 for supplying O source gas. That is, as shown by a two-dot chain line in FIG. 1, the third supply channel 27 opens into the first diffusion chamber 10, and a mass flow controller (flow rate controller) 28 is provided in the middle of the third supply channel 27. It is arranged.

  By providing the third supply flow path 27, only hydrogen gas is supplied into the processing space 1 via an independent flow path, that is, the third supply flow path. It becomes easy to adapt to various conditions such as the state.

  4 and 5 show a second example of a film forming apparatus for realizing the film forming method of the present invention.

  In this second example, a plurality of ejection openings communicate with a plurality of diffusion chambers into which the Zn source gas, O source gas and decomposition gas are independently introduced, and Zn source gas and O source gas are introduced from each ejection opening. And the cracked gas are injected independently. 4 is a cross-sectional view of the entire processing container 2, and FIG. 5 is an enlarged cross-sectional view of a part of the gas ejection head 7. As shown in FIG. Although not shown, the planar shape of the gas ejection head 7 is circular, and a large number of ejection openings 13 are provided on the surface thereof so that a uniform ZnO film can be formed on the surface of the sapphire substrate 5.

  In this example, substantially dome-shaped diffusion chambers 29A, 29B, and 29C having a circular planar shape are configured as independent chambers at the center of thick laminated members 30A, 30B, and 30C. The first supply channel 15 for supplying DEZn communicates with the ejection opening 13 from the outside of the gas ejection head 7, and a diffusion chamber 29 </ b> A is disposed in the middle of the first supply channel 15. The third supply channel 27 for supplying hydrogen gas communicates with the ejection opening 13 from the outside of the gas ejection head 7, and a diffusion chamber 29 </ b> B is disposed in the middle of the third supply channel 27. Further, the second supply channel 16 for supplying the O source gas communicates with the ejection opening 13 from the outside of the gas ejection head 7, and the diffusion chamber 29 </ b> C is disposed in the middle of the second supply channel 16. . As described above, since each diffusion chamber 29A, 29B, 29C is independent, only DEZn is supplied to the diffusion chamber 29A, only hydrogen gas is supplied to the diffusion chamber 29B, and the diffusion chamber 29C is also supplied to the diffusion chamber 29C. Is supplied with only O source gas.

  As shown in FIG. 5, the ejection opening 13 is formed by inserting a large-diameter pipe 32 into a circular opening 31 provided in the laminated member 30 </ b> C to form an annular flow gap 33, and the large-diameter pipe 32. A small-diameter pipe 34 is inserted into the inside to form an annular flow gap 35, and the inside of the small-diameter pipe 34 itself is a flow passage 36. The flow passage 36 communicates with the first supply flow path 15, the flow gap 35 communicates with the third supply flow path 27, and the flow gap 33 communicates with the second supply flow path 16. Other than that, it is the same as that of the said 1st example, and attaches | subjects the same code | symbol to the same part.

  With the above configuration, even if there is a pulsation or a turbulent flow state in each gas, it is buffered in each diffusion chamber 29A, 29B, 29C, so that the flow of each gas flowing out from each of the ejection openings 33, 35, 36 is rectified. Thus, the processing gas atmosphere acting on the surface of the sapphire substrate 5 is optimized for film formation and improvement of the formation speed. Further, since the first supply flow path 15, the third supply flow path 27, and the second supply flow path 16 are branched from the diffusion chambers 29A, 29B, and 29C, and communicate with the ejection openings 36, 35, and 33, respectively. The amount of outflow gas in each of the ejection openings 36, 35, 33 becomes substantially uniform, the film growth on the surface of the sapphire substrate 5 proceeds uniformly, and better film quality can be ensured. Other than that, there exists an effect similar to the said 1st example.

  In the first example, DEZn and hydrogen gas are simultaneously supplied to the first supply flow path 15 and nothing is supplied to the third supply flow path 27, or some other gas is supplied. It is also possible.

  6 and 7 show a third example of a film forming apparatus for realizing the film forming method of the present invention.

  In the third example, the shape of the diffusion chamber is changed. FIG. 6 is a cross-sectional view of the gas ejection head 7, and FIG. 7 is an enlarged cross-sectional view of a portion of the ejection opening 13. A wide and flat circular space is provided between the laminated members 30C and 30B, the space is configured as a diffusion chamber 29C, and a wide and flat circular space is provided between the laminated members 30B and 30A. The space is configured as a diffusion chamber 29B, and a concave portion having a large space volume is provided in the central portion of the laminated member 30A to make the diffusion chamber 29A. The second supply channel 16 has a supply pipe 16A inserted into the diffusion chamber 29C from the outside, and a nozzle hole 16B that opens at a substantially central portion of the diffusion chamber 29C is provided at the tip thereof. Further, the third supply channel 27 has a supply pipe 27A inserted from the outside into the diffusion chamber 29B, and a nozzle hole 27B that opens at a substantially central portion of the diffusion chamber 29B is provided at the tip thereof. The rest is the same as in the first and second examples, and the same reference numerals are given to the same parts.

  With the above configuration, O source gas and hydrogen gas are supplied from the nozzles 16B and 27B to the central portions of the diffusion chambers 29B and 29C, which are wide and flat circular spaces, respectively, and the flow rate is uniform with respect to the respective jet openings 13. Gas can flow out, and a uniform quality ZnO film can be formed over the entire surface of the sapphire substrate 5. Other than that, there exists an effect similar to the said 1st and 2nd example.

  FIG. 8 shows a fourth example of a film forming apparatus for realizing the film forming method of the present invention.

  In the fourth example, the heating area 1A shown in FIG. 1 is formed in a state of an independent heating box 37 in the processing space 1, and the sapphire substrate 5 is attached to the lower side thereof. A first supply flow path 15 for supplying DEZn and hydrogen gas is inserted into the processing space 1 from the outside of the processing container 2, and a second supply flow path 16 for supplying O source gas is processed from the outside of the processing container 2. The first supply flow path 15 and the second supply flow path 16 are inserted into the space 1, and each processing gas is blown onto the surface of the sapphire substrate 5. It is also possible to supply the hydrogen gas by arranging the third supply channel 27 as shown by the two-dot chain line. Other than that is the same as that of the said 1st-3rd example, and attaches | subjects the same code | symbol to the same part.

  With the above configuration, Zn element decomposed with hydrogen gas and O source gas are sprayed onto the surface of the sapphire substrate 5 to form a ZnO film. Other than that, there exists an effect similar to the said 1st-3rd example.

Using the film forming apparatus shown in FIG. 1, a ZnO film was formed under the following conditions.
Deposition temperature (substrate temperature): 700 ° C
DEZn flow rate: 2 sccm
Oxygen flow rate: 500 sccm
Nitrous oxide flow rate: 40sccm
Hydrogen flow rate: 0 sccm (Comparative Example 1)
Hydrogen flow rate: 10 sccm (Example 1)
DEZn to hydrogen volume ratio: 5 times Pressure level: 10 ^-2 Torr order
(About 1.33Pa)

The growth rates of ZnO in Comparative Example 1 and Example 1 are as follows, and the growth rate of ZnO was improved 2.8 times by adding hydrogen.
Comparative Example 1: 0.05 μm / Hr
Example 1: 0.1395 μm / Hr

Using the film forming apparatus shown in FIG. 1, a ZnO film was formed under the following conditions.
Deposition temperature (substrate temperature): 600 ° C
DEZn flow rate: 2 sccm
Oxygen flow rate: 360 sccm
Nitrous oxide flow rate: 40sccm
Hydrogen flow rate: 0 sccm (Comparative Example 2)
Hydrogen flow rate: 10 sccm (Example 2)
DEZn to hydrogen volume ratio: 5 times Pressure level: 10 ^-3 Torr order
(About 0.133Pa)

The growth rates of ZnO in Comparative Example 2 and Example 2 were as follows, and the growth rate of ZnO was improved 4.5 times by adding hydrogen.
Comparative Example 2: 0.0645 μm / Hr
Example 2: 0.287 μm / Hr

Using the film forming apparatus shown in FIG. 1, a ZnO film was formed under the following conditions.
Deposition temperature (substrate temperature): 400 ° C
DEZn flow rate: 5 sccm
Oxygen flow rate: 160 sccm
Nitrous oxide flow rate: 40sccm
Hydrogen flow rate: 10 sccm (Example 3)
Hydrogen flow rate: 50 sccm (Comparative Example 3)
DEZn to hydrogen volume ratio: 2 times (Example 3)
10 times (Comparative Example 3)
Pressure level: 10 ^-4 Torr order
(About 10133Pa)

The growth rate of ZnO in Example 3 and Comparative Example 3 is as follows. The growth rate of ZnO is as follows when hydrogen is added twice as much as DEZn and when hydrogen is added as 10 times as much as DEZn. Slightly decreased with almost no change. In Comparative Example 3, the surface of the ZnO film of Example 3 was a mirror surface, whereas the surface of Comparative Example 3 was cloudy, and a reduction reaction of the surface of the ZnO film by hydrogen occurred and the surface state deteriorated. I understand.
Example 3: 0.469 μm / Hr
Comparative Example 3: 0.444 μm / Hr

  The present invention avoids the economic burden of incorporating a plasma source or a laser source into a film forming apparatus, or modifying an existing film forming apparatus to equip a plasma source or a laser source. ZnO film can be formed stably in quality with a simple film forming facility, and can be applied to manufacture of a light emitting element such as a white light emitting diode.

It is a whole lineblock diagram showing the 1st example of the film deposition system which realizes the film deposition method of the present invention. It is an expanded sectional view of a jet opening part. It is a sequence diagram of ZnO film formation. It is sectional drawing of the film-forming apparatus of the 2nd example. It is an expanded sectional view of the gas ejection head shown in FIG. It is sectional drawing of the gas ejection head of the 3rd example. It is a partial expanded sectional view of the gas ejection head shown in FIG. It is sectional drawing of the film-forming apparatus of the 4th example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing space 1A Heating area 1B Growth area 2 Processing container 3 Separation plate 4 Opening 5 To-be-processed object, sapphire substrate, ZnO substrate 6 Exhaust port 7 Gas ejection head H Heating heater 8 Reflector 9 Partition plate 10 1st diffusion chamber 11 2nd Diffusion chamber 12 Opening plate 13 Ejection opening 13A Hole 14 Ejection opening 14A Pipe 15 First supply flow path 15A Pipe member 16 Second supply flow path 16A Supply pipe 16B Injection hole 17 Flow path 18 Flow path 19 Mass flow controller (flow rate controller)
20 Mass flow controller (flow controller)
21 Switching valve 21A Vent passage 22 Channel 23 Channel 24 Mass flow controller (flow controller)
25 Mass Flow Controller (Flow Controller)
26 Switching valve 26A Vent passage T Extended time 27 Third supply flow path 27A Supply pipe 27B Injection port 28 Mass flow controller (flow rate controller)
29A Diffusion chamber 29B Diffusion chamber 29C Diffusion chamber 30A Laminating member 30B Laminating member 30C Laminating member 31 Opening 32 Large diameter pipe 33 Flow gap 34 Small diameter pipe 35 Flow gap 36 Flow passage 37 Heating box

Claims (6)

This is a ZnO film forming method in which at least a Zn source gas and an O source gas are supplied into a processing space, and a ZnO film is formed on the surface of the object to be processed exposed to the processing space by the two source gases. And
When forming a ZnO film while introducing hydrogen gas as a decomposition gas that promotes at least decomposition of either of the two source gases into the processing space,
Do not radicalize both raw material gases and cracked gas, and
A method of forming a ZnO film, wherein the decomposition gas is supplied into the processing space separately from the two source gases.   2. The method for forming a ZnO film according to claim 1, wherein the volume ratio of the decomposition gas to the source gas to be decomposed in the processing space is less than 10 times the volume.   The method for forming a ZnO film according to claim 1 or 2, wherein the decomposition gas is introduced into the processing space at a flow rate less than 10 times the flow rate of the raw material gas to be decomposed.   The method for forming a ZnO film according to any one of claims 1 to 3, wherein the source gas to be decomposed by the decomposition gas is a Zn source gas. The method for forming a ZnO film according to any one of claims 1 to 4 , wherein the Zn source gas, the O source gas, and the decomposition gas are jetted from a jetting opening adjacent to a surface of an object to be processed. The Zn source gas, the O source gas, and the decomposition gas are independently introduced into a plurality of diffusion chambers, and the Zn source gas, the O source gas, and the decomposition gas are independently supplied from the respective jet openings through the diffusion chambers. The ZnO film forming method according to claim 5 , wherein the ZnO film is sprayed.

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