JP2010010588A - Element manufacturing method and film forming apparatus - Google Patents

Abstract

Provided is a method for efficiently manufacturing an element in which a plurality of films having different compositions are laminated while suppressing a film thickness distribution.
A plurality of layers are stacked by repeating vapor phase growth while changing at least one of the type and flow rate of a material gas. When changing the type and flow rate of the material gas, the distance between the gas supply nozzle and the substrate holding part is changed to a predetermined distance, so that the peak of the film thickness distribution in the radial direction of the substrate holding part is obtained. It is generated in a position that does not overlap with the Thereby, the film thickness on a board | substrate can be equalize | homogenized by rotating and revolving a board | substrate.
[Selection] Figure 2

Description

  The present invention relates to a vapor phase growth method in which a plurality of gases are supplied to deposit reaction products.

  Conventionally, an apparatus and a growth method for obtaining a thin film such as a semiconductor crystal on a substrate by flowing a material gas while heating the substrate installed in a reaction tube are known.

For example, Patent Document 1 discloses metal hydrides such as Group V material gases AsH ₃ (arsine) and PH ₃ (phosphine), and Group III material gases TMGa (trimethylgallium) and TMIn (trimethylindium). A vapor phase growth method is disclosed in which organic metal compounds such as TMAl (trimethylaluminum) are supplied from separate supply nozzles without being mixed in the middle. The supplied material gas is supplied with heat energy from the heater in the reaction tube and starts the reaction. The reaction product is deposited on the substrate and a film is formed. For example, by supplying PH _{3 of} Group V material gas from one supply nozzle and TMGa of Group III gas and H ₂ gas of dilution gas from another supply nozzle, GaP (gallium phosphide) is formed on the substrate. Crystals can be grown.

  In Patent Document 1, when a plurality of substrates are fixed to a substrate holder at a time, a rectifying plate is provided in a material gas supply nozzle in order to reduce a film thickness distribution or a mixed crystal ratio generated between the plurality of substrates. An arrangement for controlling the joining position of two or more kinds of reaction gases is disclosed.

  Patent Documents 2 to 5 describe that by controlling the distance between the substrate and the gas supply nozzle (or the gas discharge head or the like), it is possible to reduce variations in film thickness and to reduce deposits on the surface of the gas discharge head. Has been.

JP 2006-344615 A Japanese Patent Laid-Open No. 5-29302 JP-A-9-153461 (Claim 5) JP-A-9-283445 (Claim 7) JP 2003-249491 A

  In the method of vapor phase growth by reacting the material gas, the gas supplied from the gas supply unit is mixed and a chemical reaction is generated by the thermal energy from the heater to generate a reaction product (for example, a crystal). It is a method of depositing. The amount of the reaction product generated varies depending on the distance from the gas supply unit (center of the susceptor) because it is affected by the manner in which heat energy is applied to the material gas supplied from the gas supply unit, the flow rate, and material depletion. For this reason, it is difficult to obtain a flat film thickness distribution for the entire susceptor, and a film thickness distribution having a peak at a position away from the susceptor center by a predetermined distance as shown in FIG.

  When the film thickness distribution has a peak as shown in FIG. 10, the substrate is arranged at a position deviated from the peak, that is, the substrate at a position where the film thickness distribution monotonously increases or monotonously decreases with respect to the distance from the susceptor center. By rotating and revolving the film, the film thickness distribution is made uniform on the substrate.

  However, when a plurality of films having different compositions are successively laminated on the substrate, it is necessary to change the type and ratio (supply amount) of the material gas supplied from the gas supply nozzle. If the environmental conditions are the same, the peak of the film thickness distribution moves. When the peak of the film thickness distribution moves on the substrate, the film thickness distribution on the substrate cannot be made uniform even if the substrate rotates and revolves. For this reason, in order to make the film thickness distribution of the laminated film uniform, every time the type or ratio of the material gas is changed, conditions such as the gas supply amount, temperature, pressure, etc. are adjusted, and the peak position of the film thickness distribution is adjusted. Must be offset from the substrate. Moreover, since the change in the peak position of the film thickness distribution is greatly affected by the thermal energy supplied to the material gas as described above, the peak position change in the film thickness distribution can be adjusted by adjusting the gas supply amount, temperature, pressure, etc. It is not easy to predict. In practice, it is necessary to conduct experiments under various conditions in advance to obtain appropriate values for conditions such as the gas supply amount, temperature, and pressure.

  In addition, when changing the settings of the gas supply amount, temperature, pressure, etc., as well as the type of gas during the growth of the laminated film, a waiting time is required until the set conditions are stabilized, and the growth time becomes longer. The gas utilization efficiency also deteriorates.

  An object of the present invention is to provide a method for efficiently manufacturing an element in which a plurality of films having different compositions are laminated while suppressing the film thickness distribution.

  In order to achieve the above object, in the first aspect of the present invention, while rotating the substrate relative to the substrate holding portion, the substrate holding portion is rotated, and a predetermined material gas is ejected from one or more gas supply nozzles. There is provided a method for manufacturing a multilayer element having a plurality of films by repeatedly depositing a reaction product of a material gas on the substrate while changing at least one of the kind and flow rate of the material gas. When changing at least one of the type and flow rate of the material gas, the distance between the gas supply nozzle and the substrate holder is changed so that the peak of the film thickness distribution in the radial direction of the substrate holder does not overlap the substrate. Cause it to occur. As a result, the peak of the film thickness distribution can be controlled so as not to overlap the substrate by adjusting one parameter called distance, and the film thickness can be made uniform by rotating the substrate holding part while rotating the substrate. It becomes possible.

  The distance can be set to a value obtained in advance. Further, when there are two or more gas supply nozzles, the distance between the two or more gas supply nozzles and the substrate holder can be changed.

  It is preferable to change the distance so that the peak positions of the respective film thickness distributions when the plurality of films are formed are matched.

  During the formation of one of the plurality of films, the gas supply nozzle can be swung to change the distance from the substrate holder. Thereby, a film thickness can be made more uniform.

  According to the second aspect of the present invention, the substrate holding unit that holds the substrate, the rotation mechanism unit that rotates the substrate holding unit and rotates the substrate with respect to the substrate holding unit, and the material gas are supplied. There is provided a film forming apparatus including two or more gas supply nozzles and a movable mechanism for independently changing the distance between the two or more gas supply nozzles and the substrate holding unit.

An embodiment of the present invention will be described.
First, the structure of the film forming apparatus of this embodiment will be described with reference to FIGS. As shown in FIGS. 1 and 2, the film forming apparatus includes a susceptor 3 that holds a plurality of substrates 4, a heater 7 that heats the susceptor 3, and a reaction tube 5 in which a gas supply unit 6 is arranged. Yes. The wall surface 16 of the reaction tube 5 facing the susceptor 3 is formed to be parallel to the susceptor 3 with a certain distance therebetween. The reaction tube 5 is disposed in the glove box 2. The susceptor 3 is provided with a rotation drive mechanism 15 that rotates (revolves) the entire susceptor 3 about a shaft 21. The susceptor 3 includes a mechanism for rotating (spinning) each substrate 4 with respect to the susceptor 3.

  Between the susceptor 3 and the opposing wall surface 16, a gas supply unit 6 for supplying a material gas is disposed. As shown in FIG. 2, the gas supply unit 6 includes a first supply nozzle 6a and a second supply nozzle 6b. The first and second supply nozzles 6a and 6b are disk-shaped, and are provided with jet nozzles around them. As a result, the material gas is uniformly ejected around. The gas supply unit 6 is disposed at a position facing the inside of the revolution trajectory of the substrate 4 at the center of the susceptor 3 so as to eject the material gas from the center of the disc-shaped susceptor 3 toward the outer periphery.

  A material gas is supplied to the first supply nozzle 6a from a supply pipe 6c. The material gas is supplied to the second supply nozzle 6b from the supply pipe 6d. The supply pipes 6 c and 6 d are drawn out to the outside of the reaction pipe 5 through through holes provided in the opposing wall surface 16. The supply pipe 6 c to the first supply nozzle 6 a and the supply pipe 6 d to the second supply nozzle 6 b are arranged coaxially with the central axis 21 of the susceptor 3. The supply pipes 6c and 6d can move independently in the direction of the shaft 21.

  A nozzle drive mechanism 15 is attached to the supply pipes 6c and 6d. The nozzle driving mechanism 15 has a support frame 22 fixed to the supply pipe 6c, and the support frame 22 is provided with a ball screw 23 and a motor 24 for driving the support frame 22 against the wall surface 16. Similarly, a support frame 25 is fixed to the supply pipe 6d, and the support frame 25 is provided with a ball screw 26 and a motor 27 for driving it in the direction of the axis 21 with respect to the wall surface 16. By rotating the motor 24, the supply pipe 6c and the nozzle 6a move in the direction of the axis 21, and by rotating the motor 27, the supply pipe 6c and the nozzle 6b move in the direction of the axis 21. By moving the gas supply nozzles 6a and 6b, the distance between the gas supply nozzles 6a and 6b and the susceptor 3 and the distance between the gas supply nozzles 6a and 6b and the substrate 4 can be changed.

  A bellows (expandable tube) 28 and a bellows 29 are disposed between the support frame 25 and the wall surface 16 and between the support frame 25 and the support frame 22 so as to surround the supply tubes 6c and 6d. ing. Thus, the airtightness of the reaction tube 5 is maintained while allowing the supply tubes 6c and 6d to move.

  As shown in FIG. 1, the gas control device 1 is connected to the supply pipes 6c and 6d, and the material gas is supplied at a set flow rate.

  An exhaust port 8 is connected to the reaction tube 5 as shown in FIG. The exhaust port 8 is connected to an exhaust pump 10 via a trap mechanism 9. On the exhaust side of the exhaust pump 10, an exhaust gas abatement equipment 11 is installed.

  The operation of each part when performing film formation using the film formation apparatus of the present embodiment will be described. One or more substrates 4 are mounted on the susceptor 3 at positions shifted from the center, and the susceptor 3 is rotated (revolved) and each substrate 4 is rotated. The exhaust pump 10 is operated to reduce the pressure in the reaction tube 5 to a predetermined pressure. By heating the heater 7, the susceptor 3 and the opposing wall surface 16 are heated. The supply nozzles 6a and 6b are supplied with a first material gas and a second material gas at a predetermined flow rate from the gas control device 1, respectively. The material gas ejected from the supply nozzles 6a and 6b flows outward from the center of the susceptor 3 and receives heat from the susceptor 3 while flowing. Thereby, when the temperature of the first and second material gases reaches a predetermined reaction temperature (position), the first and second material gases start to react, and the reaction product is deposited on the substrate 4. . Therefore, the film thickness distribution deposited on the substrate 4 changes depending on the distance from the center of the susceptor 3, and the distribution has a peak as shown in FIG. When the peak of the film thickness distribution deviates from the substrate 4 and indicates monotonic decrease and monotonic increase, the film thickness on the substrate 4 can be made uniform by rotating and revolving the substrate 4. When positioned on the substrate 4, the film thickness on the substrate 4 is not uniform even if the substrate 4 rotates and revolves.

  At this time, the position of the supply nozzles 6a and 6b can be changed even during film formation by independently moving the material gas supply nozzles 6a and 6b by driving the external motors 24 and 27, respectively. As a result, the distance between the susceptor 3 and the supply nozzles 6a and 6b changes, so that the amount of heat received by the jetted gas from the heater 7 changes, and the position and reaction rate at which the reaction starts change. Therefore, the peak of the film thickness distribution can be changed, and the peak position is shifted from the substrate 4 by changing the positions of the supply nozzles 6a and 6b even when the gas supply amount and the gas type are changed. The film can be formed with a uniform film thickness.

For example, under the conditions of a distance of 25 mm between the susceptor 3 and the opposing wall surface 16, a pressure in the reaction tube 5 of 10 kPa, a heater temperature of 870 ° C., and a temperature of the opposing wall surface 16 of 220 ° C., the V ₃ group gas PH ₃ , the supply nozzle When supplying the group III gas TMGa (trimethylgallium) from 6b, the distance (S1) between the susceptor 3 and the supply nozzle 6a shown in FIG. 3 is 2 mm, the distance (S2) between the susceptor 3 and the supply nozzle 6b is 23 mm, When the total flow rate of the supply amount from the supply nozzle 6a and the supply amount from the supply nozzle 6b is set to 20 SLM, a film thickness peak occurs in the vicinity of 10 cm from the center of the susceptor 3 as shown in FIG. When the total flow rate is changed to 40 SLM without changing the positions of the supply nozzles 6a and 6b, the peak position of the film thickness moves to around 12 cm. When the substrate 4 is present in the vicinity of 12 cm from the center of the susceptor 3, a film having a uniform film thickness cannot be obtained.

  In contrast, the supply amount from the supply nozzle 6a and the supply nozzle 6b is changed to 40 SLM, the distance (S1) between the susceptor 3 and the supply nozzle 6a is 2 mm, and the distance (S2) between the susceptor 3 and the supply nozzle 6b is 10. When changed to .5 mm, the peak position of the film thickness can be maintained at substantially the same position as the peak position of the supply amount 20 SLM as shown in FIG. Therefore, the peak position can be shifted from the substrate 4, and even when the flow rate is changed from 20 SLM to 40 SLM, a film having a uniform film thickness can be obtained.

Further, for example, supply of V ₃ group gas PH ₃ from the supply nozzle 6a under the conditions of a distance of 25 mm between the susceptor 3 and the opposing wall surface 16, a pressure in the reaction tube 5 of 10 kPa, a heater temperature of 870 ° C., and a temperature of the opposing wall surface 16 of 220 ° C. When the group III-based gas TMGa (trimethylgallium) is supplied from the nozzle 6b, the distance between the susceptor 3 and the supply nozzle 6a (S1) is 2 mm, the distance between the susceptor 3 and the supply nozzle 6b (S2) is 23 mm, and from the supply nozzle 6a. When the total flow rate of the supply amount and the supply amount from the supply nozzle 6b is 40SLM, and the ratio of the V group gas flow rate from the supply nozzle 6a to the III group gas flow rate from the supply nozzle 6b (V / III) = 40, FIG. Thus, a film thickness peak occurs in the vicinity of 11 cm from the center of the susceptor 3. When the ratio is changed to the ratio V / III = 640 with the total flow rate of 40 SLM, the peak position moves to around 12 cm. Therefore, when the substrate 4 is in the vicinity of 12 cm from the center of the susceptor 3, a film having a uniform film thickness cannot be obtained.

  On the other hand, when the ratio V / III is changed to 640, the distance (S1) between the susceptor 3 and the supply nozzle 6a is changed to 2 mm, and the distance (S2) between the susceptor 3 and the supply nozzle 6b is changed to 14.5 mm. Thus, as shown in FIG. 7, the peak position of the film thickness can be maintained at substantially the same position as the peak position of the ratio V / III = 40, so that the peak position can be shifted from the substrate 4. Therefore, even when the flow rate ratio (V / III) is changed, a film having a uniform film thickness can be obtained. In the graph of FIG. 7, the heights of the peaks are the same before and after changing the flow rate ratio (V / III) because the film formation times are different (70 minutes and 78 minutes). .

  When actually forming a film, the relationship between the positions (S1, S2, S3) of the supply nozzles 6a, 6b, the film forming conditions, and the peak position of the film thickness distribution, which have been obtained in advance, is used. The position of the supply nozzles 6a and 6b is adjusted so that the film thickness peak position does not overlap the substrate 4 when changing the type, flow rate, and ratio of the material gas in order to stack different films. Thereby, a laminated film with a uniform film thickness can be formed.

  That is, by adjusting the positions of the supply nozzles 6a and 6b, the film thickness distribution can be easily controlled without adjusting the position of the substrate 4 and the gas supply amount, and the film thickness distribution can be easily laminated. A film can be formed. By using this technique for forming a laminated film of a light emitting element or a semiconductor element, it is possible to improve the uniformity of the film thickness distribution and obtain an element having excellent light emission efficiency and electronic control characteristics.

  The peak of the film thickness distribution is preferably substantially the same position before and after the condition change as shown in the graphs of FIGS. 5 and 7, but does not necessarily have to be the same position and does not necessarily overlap with the substrate 4. Good.

  In the embodiment described above, the supply nozzles 6a and 6b can be swung with a constant width while one film is formed of the same material. However, it is necessary to determine the swing range so that the peak position does not overlap the substrate due to the swing. By rotating the nozzle during film formation, the uniformity of the film thickness distribution is improved.

  A method for manufacturing the light emitting device of FIG. 8A using the film forming method of the present embodiment will be described. 8A includes an n-type GaAs buffer layer 72, a Si-doped n-type AlGaInP n-type cladding layer 73, an undoped AlGaInP active layer 74, and a Zn-doped AlGaInP layer. A p-type cladding layer 75 and a Zn-doped p-type GaP current diffusion layer 76 are stacked. The film thickness of each layer is as shown in FIG.

  In the present embodiment, the layers from the buffer layer 72 to the current diffusion layer 76 are formed using the film forming apparatus shown in FIG. At this time, the distance between the susceptor 3 and the opposing wall surface 16 (F in FIG. 3) and the positions of the supply nozzles 6a and 6b (S1, S2, and S3 in FIG. 3) are set as shown in FIG. 8B.

Specifically, when the n-type GaAs buffer layer 72 is formed, the supply nozzle 6a is operated under the conditions of the internal pressure of the reaction tube 5 of 10 kPa, the heater temperature of 600 to 900 ° C., and the temperature of the opposing wall surface 16 of 200 to 300 ° C. From Group V, AsH ₃ , and Group III gas, trimethylgallium (TMGa), is supplied from the supply nozzle 6b. Film formation is performed by setting the distance F between the susceptor 3 and the opposing wall surface 16 to 20 mm and the positions S1, S2, and S3 of the supply nozzles 6a and 6b to 2 mm, 5 mm, and 13 mm, respectively.

When forming the n-type cladding layer 73 of Si-doped n-type AlGaInP, from the supply nozzle 6a under the conditions of the internal pressure of the reaction tube 5 of 10 kPa, the heater temperature of 600 to 900 ° C., and the temperature of the opposing wall surface 16 of 200 to 300 ° C. The group III gas TMGa, TMA (trimethylaluminum), and TMI (trimethylindium) are supplied from the group V gas PH ₃ and the supply nozzle 6b. Film formation is performed by setting the distance F between the susceptor 3 and the opposing wall surface 16 to 20 mm, and the positions S1, S2, and S3 of the supply nozzles 6a and 6b to 2 mm, 7 mm, and 11 mm, respectively.

When forming the active layer 74 of undoped AlGaInP and the p-type cladding layer of Zn-doped AlGaInP, under the conditions of the internal pressure of the reaction tube 5 of 10 kPa, the heater temperature of 600 to 900 ° C., and the temperature of the opposing wall surface 16 of 200 to 300 ° C. From the supply nozzle 6a, the group V gas PH _{3 is} supplied, and from the supply nozzle 6b, the group III gases TMGa, TMA (trimethylaluminum), and TMI (trimethylindium) are supplied. Film formation is performed by setting the distance F between the susceptor 3 and the opposing wall surface 16 to 20 mm, and the positions S1, S2, and S3 of the supply nozzles 6a and 6b to 2 mm, 5 mm, and 13 mm, respectively. When forming the p-type cladding layer 75, DMZn (dimethyl zinc) is supplied for Zn doping.

When the Zn-doped p-type GaP current diffusion layer 76 is formed, the supply nozzle 6a to V is used under the conditions of the internal pressure of the reaction tube 5 of 10 kPa, the heater temperature of 600 to 900 ° C., and the temperature of the opposing wall surface 16 of 200 to 300 ° C. The group III gas PH ₃ and the group III gas TMGa are supplied from the supply nozzle 6b. The distance F between the susceptor 3 and the opposing wall surface 16 is narrowed to 15 mm, and the positions S1, S2, and S3 of the supply nozzles 6a and 6b are set to 1 mm, 1 mm, and 13 mm, respectively.

  Since the nozzle position and the distance between the susceptor 3 and the opposing wall surface 16 can be adjusted and the peak of the film thickness distribution can be shifted from the substrate, each layer of the light emitting element in FIG. 8A is formed with a uniform film thickness. can do. Thereby, the light emitting element excellent in luminous efficiency can be manufactured.

  Next, an example of a supply nozzle according to another embodiment will be described with reference to FIG.

  As shown in FIG. 9, this supply nozzle has nozzles 81 to 84 in which the ends of pipes having different diameters are expanded in a circle and are coaxially arranged with respect to the shaft 21. And 83, and the space between the nozzles 83 and 84, respectively, serves as a flow path, and material gas can be supplied from each space. The other configuration is the same as the configuration of FIGS.

  Although this supply nozzle has a compact configuration, there is an advantage that three or more material gases can be supplied simultaneously. It is also possible to use only two flow paths between the nozzles 81 and 82 and between the nozzles 83 and 84. Furthermore, the material gas can also be supplied from the central space of the nozzle 81 through the space between the nozzle 81 and the susceptor 3.

  When changing the type or flow rate of the gas, the positions of the nozzles 81 to 84 are adjusted so that the peak position of the film thickness distribution is moved so as not to overlap the substrate 4 and film formation is performed. Thereby, a laminated film having a uniform film thickness distribution can be formed as in the nozzle of FIG.

1 is a block diagram showing an overall structure of a film forming apparatus according to an embodiment. FIG. 2 is a cross-sectional view showing a detailed configuration of a reaction tube 5 and a nozzle movable mechanism 15 of the film forming apparatus of FIG. 1. The enlarged view of the supply nozzle part of FIG. 2 is a graph showing the film thickness distribution when the gas flow rate is changed without moving the supply nozzle in the film forming apparatus of FIG. 1. 2 is a graph showing a film thickness distribution when a supply nozzle is moved before and after changing a gas flow rate in the film forming apparatus of FIG. 1. 3 is a graph showing a film thickness distribution when the flow rate ratio of a group V gas and a group III gas is changed without moving a supply nozzle in the film forming apparatus of FIG. The graph which shows the film thickness distribution at the time of moving a supply nozzle before and after changing the flow ratio of V group gas and III group gas in the film-forming apparatus of FIG. (A) Explanatory drawing which shows the structure of the light emitting element manufactured with the manufacturing method of this embodiment, (b) Explanatory drawing which shows the nozzle position at the time of the growth of each layer of Fig. (A). Sectional drawing which shows the supply nozzle shape of another embodiment. The graph which shows the substrate position for forming into a film thickness distribution curve produced with a film-forming apparatus, and a uniform film thickness.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Gas control apparatus, 2 ... Glove box, 3 ... Susceptor, 4 ... Substrate, 5 ... Reaction tube, 6 ... Gas supply part, 7 ... Heater, 8 ... Exhaust port, 9 ... Trap mechanism, 10 ... Exhaust pump, 11 Detoxification equipment, 15 ... Nozzle operation mechanism, 22 ... Support frame, 23 ... Ball screw, 24 ... Motor, 25 ... Support frame, 26 ... Ball screw, 27 ... Motor, 28, 29 ... Bellows.

Claims (6)

A step of rotating the substrate holding unit while rotating the substrate with respect to the substrate holding unit, ejecting a predetermined material gas from one or more gas supply nozzles, and depositing a reaction product of the material gas on the substrate; , A method for producing a multi-layer laminated element by repeatedly performing at least one of the type and flow rate of the material gas,
When changing at least one of the type and flow rate of the material gas, the distance between the gas supply nozzle and the substrate holding portion is changed, and the peak of the film thickness distribution in the radial direction of the substrate holding portion is changed to the substrate. A method for manufacturing an element, wherein the element is generated at a position that does not overlap with the element.   The element manufacturing method according to claim 1, wherein the distance is set to a predetermined distance obtained in advance for each type and flow rate of the material gas.   3. The element manufacturing method according to claim 1, wherein when the number of the gas supply nozzles is two or more, the distance from the substrate holding unit is changed for each of the two or more gas supply nozzles. Device manufacturing method.   4. The element manufacturing method according to claim 1, wherein the peak positions of the respective film thickness distributions at the time of forming the plurality of films are matched by changing the distance. The manufacturing method of the element which does.   5. The device manufacturing method according to claim 1, wherein the gas supply nozzle is swung during the formation of one of the plurality of films to hold the substrate. 6. A method for manufacturing an element, wherein the distance to the part is periodically changed.   A substrate holding unit for holding a substrate; a rotation mechanism unit for rotating the substrate holding unit and rotating the substrate with respect to the substrate holding unit; two or more gas supply nozzles for supplying a material gas; A film forming apparatus comprising: a movable mechanism for independently changing a distance between the gas supply nozzle and the substrate holding part.

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