1. Technical Field
The present invention relates to inlet systems, and more particularly, to an inlet system for a metal-organic chemical vapor deposition (MOCVD) apparatus.
2. Description of Related Art
Metal-organic chemical vapor deposition (MOCVD), or known as metal-organic chemical vapor phase epitaxy (MOVPD), is a semiconductor thin-film preparation technique for use in preparing semiconductor thin-films from III-V compounds, II-VI compounds, and alloys thereof, such as gallium nitride, gallium arsenide, indium phosphide, and zinc oxide. As semiconductor thin-films have increasingly wide application, the manufacturing of light-emitting diodes (LED), laser diodes (LD), and radio frequency integrated circuit (RF IC) usually requires MOCVD apparatuses; hence, MOCVD apparatuses are attributed to one of the important types of semiconductor process apparatuses.
The underlying principle of MOCVD involves converting a precursor into a gas and then delivering a reactant gas together with a carrier gas to a reactor through an inlet system, such that a solid-state substance produced as a result of a chemical reaction deposits on a solid-state substrate positioned on a rotatable heating platform, thereby allowing a semiconductor thin-film to be formed on the solid-state substrate. During the deposition process, it is important to control the thickness, and the uniformity thereof, of the semiconductor thin-film. However, turbulent flow, which occurs to the reactor because of thermal buoyancy and inertial force, is an important factor in causing uneven thickness of the semiconductor thin-film. Furthermore, the turbulent flow causes the contamination of the inner wall of the reactor chamber and a waste of the precursor.
The aforesaid phenomena can be prevented by means of process parameter control, the shape of a nozzle of the inlet system, and the type of the reactor. At present, MOCVD apparatus inlet systems used by the industrial sector come in three types. The first type of MOCVD apparatus inlet systems operates in a vertical inlet mode and relies upon the high-speed and yet axial-rotation-free rotation of a platform to ensure uniform flow, increases the yield effectively, and reduces the duration and frequency of rinsing and maintenance. However, not only is the reactor bulky, but the required amount of the reactant gas is also excessive, not to mention that turbulent flow is likely to occur to the reactor and thus cause instability.
The second type of MOCVD apparatus inlet systems operates in a central nozzle mode and relies upon the low-speed rotation of a platform as well as the axial rotation of a wafer to ensure stable flow. It has advantages, namely a compact reactor, and efficient use of the reactant gas in terms of the required amount thereof But the reactor chamber of the reactor is so low to render automation difficult. Moreover, the reactor must be opened after each instance of the manufacturing process, thereby bringing about a change in the subsequent manufacturing process environment. Furthermore, due to deposition and contamination, the axial-rotation of the platform often speeds up, slows down, or even stops during the epitaxy process, thereby changing growth conditions and causing uneven thickness of the thin-film grown.
The third type of MOCVD apparatus inlet systems operates in an inlet mode characterized by a shower nozzle and relies upon the low and medium-speed rotation of a platform to ensure uniform intake. However, the aforesaid inlet mode is characterized disadvantageously be a small distance (of 20 mm approximately) between an intake port and the platform, a high likelihood of clogging the apertures of the shower nozzle, and thus the necessity to clean or change the shower nozzle regularly.
The above analysis indicates that conventional inlet systems for use with MOCVD apparatuses each have advantages and disadvantages. However, the past enhancement of the uniformity of flow inside the reactor chamber is mainly achieved by altering the means of intake and designing the geometrical shapes of intake ports as well as an array in which the intake ports are arrange. Nonetheless, some disadvantages remain unsolved, including: in the reactor chamber, the reactant gas forms unstable turbulent flow; the reactant gas undergoes a pre-reaction in the vicinity of the intake ports to form products at the intake ports, thus clogging the intake ports; and the turbulent flow causes the contamination of the inner wall of the reactor chamber and a waste of precursors.
The present invention relates to an inlet system for use with a metal-organic chemical vapor deposition (MOCVD) apparatus. The inlet system includes a subsidiary inlet module disposed outside an inlet module to reduce turbulent flow and concentrate a reactant gas, so as to not only enhance the reaction rate of the reactant gas and the growth rate of films but also enhance the uniformity of film growth.
The present invention provides an inlet system for a metal-organic chemical vapor deposition (MOCVD) apparatus, comprising: an inlet module for admitting at least a reactant gas; and a subsidiary inlet module disposed outside the inlet module, including at least a subsidiary inlet channel, and admitting a carrier gas.
The present invention also provides an inlet system for a metal-organic chemical vapor deposition (MOCVD) apparatus, comprising: an inlet module including at least a first reacting gas channel for admitting a first reactant gas and at least a second reacting gas channel for admitting a second reactant gas; and a subsidiary inlet module including at least a subsidiary inlet channel adapted to admit a carrier gas and disposed between the at least a first reacting gas channel and the at least a second reacting gas channel to separate the at least a first reacting gas channel and the at least a second reacting gas channel.
Implementation of the present invention involves the following inventive steps:
1. enhance the reaction rate of a reactant gas and the growth rate of a thin-film;
2. reduce formation of turbulent flow and thus enhance the uniformity and stability of the growth of the thin-film; and
3. reduce pollution, decrease the required frequency of the rinsing and maintenance of a reactor chamber, enhance the utilization rate of the apparatus, and cut the production costs thereof
The invention as well as a preferred mode of use and advantages thereof will be best understood by referring to the following detailed description of an illustrative embodiment in conjunction with the accompanying drawings, wherein:
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The inlet module 11 admits the reactant gas. The carrier gas is delivered together with the reactant gas to the reactor chamber 20 through the inlet module 11. The carrier gas is any gas that does not undergo any chemical reaction with the reactant gas and is exemplified by hydrogen or nitrogen. The reactant gas is exemplified by a single gas composed of a III compound, a V compound, a II compound, or a VI compound, by a mixture of gases composed of a mixture of a III compound and a V compound, or by a mixture of gases composed of a mixture of a II compound and a VI compound.
The subsidiary inlet module 12 admits the carrier gas only and is disposed outside the inlet module 11. The carrier gas admitted into the subsidiary inlet module 12 can be either identical to or different from the carrier gas for use in delivering the reactant gas in the inlet module 11 so long as the carrier gas admitted into the subsidiary inlet module 12 does not undergo any chemical reaction with the reactant gas.
The subsidiary inlet module 12 comprises at least a subsidiary inlet channel 121. Intake ports of the subsidiary inlet channel 121 surround intake ports of the inlet system 10 and are positioned proximate to the inner wall of the reactor chamber 20. The carrier gas is delivered to the reactor chamber through the subsidiary inlet module 12; hence, the carrier gas reduces turbulent flow near the inner wall of the reactor chamber, prevents the reactant gas from contaminating the inner wall of the reactor chamber, and concentrates the reactant gas, thereby achieving the effective use of the reactant gas.
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The subsidiary inlet channel 121, 121a, 121b of the subsidiary inlet module 12 illustrated with both
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The first reacting gas channel 111 and the second reacting gas channel 112 of the inlet module 11 each admit a single reactant gas only. Furthermore, each of the intake ports of the first and second reacting gas channels 111, 112 is linear, round, or has any appropriate geometrical shape, which is not restrictive of the present invention.
The subsidiary inlet module 12 comprises at least a subsidiary inlet channel 121 adapted to admit the carrier gas and disposed between the first reacting gas channel 111 and the second reacting gas channel 112 to separate the first reacting gas channel 111 from the second reacting gas channel 112 and thus prevent the first reactant gas and the second reactant gas from undergoing a pre-reaction in the vicinity of the intake ports and clogging the intake ports, reduce formation of particles which cannot form a film at the low and medium temperature areas and thus save the reactant gas, and lessen gas flow instability otherwise caused by an inertial force driven by difference on momentum between fluid flow of the first reactant gas and the second reactant gas.
For instance, the subsidiary inlet channel 121 has at least an annular intake port disposed outside the first reacting gas channel 111 or the second reacting gas channel 112 so as to surround intake ports of the first reacting gas channel 111 or intake ports of the second reacting gas channel 112. Referring to
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Hence, the peripheral intake port 122 is disposed outside the intake ports of the inlet system 10 and positioned proximate to the inner wall of the reactor chamber. Referring to
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The subsidiary inlet module 12 comprises at least a subsidiary inlet channel 121 and a plurality of linear intake ports. The linear intake ports are arranged radiately. Referring to
The linear intake ports of the subsidiary inlet channel 121 separate the first reacting gas channel 111 and the second reacting gas channel 112, such that each linear intake port of each said subsidiary inlet channel 121 are flanked by the first reacting gas channel 111 and the second reacting gas channel 112.
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The peripheral intake port 122 is disposed outside intake ports of the inlet system 10 and positioned proximate to the inner wall of the reactor chamber. Referring to
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The subsidiary inlet module 12 comprises at least a subsidiary inlet channel 121 and a plurality of linear intake ports. The linear intake ports are parallel and are each disposed between at least a first reacting gas channel 111 and at least a second reacting gas channel 112 to separate the first reacting gas channel 111 from the second reacting gas channel 112.
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The peripheral intake port 122 is disposed outside intake ports of the inlet system 10 and positioned proximate to the inner wall of the reactor chamber. Referring to
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The subsidiary inlet module 12 comprises at least a subsidiary inlet channel 121 and a plurality of transverse linear intake ports 121c and a plurality of longitudinal linear intake ports 121d. The transverse linear intake ports 121c are in contact with the longitudinal linear intake ports 121d, respectively, and surround the intake ports of at least a first reacting gas channel 111 or the intake ports of at least a second reacting gas channel 112 so as to separate the first reacting gas channel 111 and the second reacting gas channel 112.
The transverse and longitudinal linear intake ports 121c, 121d are each flanked by the first reacting gas channel 111 and the second reacting gas channel 112 and adapted to admit the carrier gas into the reactor chamber. Due to the transverse and longitudinal linear intake ports 121c, 121d of the subsidiary inlet channel 121, the reactant gas being discharged from the first and second reacting gas channels 111, 112 can be insulated from the intake ports by the carrier gas, thereby inhibiting the pre-reaction and lessening the likelihood of intake port clogging.
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With the implementation of the embodiment of the present invention, it is easy to process and produce a subsidiary inlet module in a conventional inlet system, block, separate and guide a reactant gas, enhance the growth rate and uniformity of thickness of a semiconductor thin-film effectively, reduce contamination and a waste of the reactant gas, prevent turbulent flow from happening to a reactor chamber, and enhance the stability of the manufacturing process.
The reactant gas at the periphery of a conventional inlet system has a low utilization rate, as it is discharged mostly from the reactor chamber, thereby causing a waste of the reactant gas. In view of this, the inlet system of the present invention is characterized in that: a subsidiary inlet module is disposed outside an inlet module; and the subsidiary inlet module narrows the scope and guides the flow motion of intake of the reactant gas and thus enhances the utilization rate of the reactant gas.
From the perspective of the inlet module, the subsidiary inlet module insulates at least two reactant gases at the intake ports so as to reduce the likelihood that the reactant gases undergo a pre-reaction in the vicinity of the intake ports, thus clogging the intake ports. Also, due to the reduction in the likelihood of a pre-reaction and inner wall contamination, the required frequency of rinsing and maintenance decreases greatly, thereby enhancing the efficiency of operation of the MOCVD apparatus.
The features of the present invention are disclosed above by the preferred embodiment to allow persons skilled in the art to gain insight into the contents of the present invention and implement the present invention accordingly. The preferred embodiment of the present invention should not be interpreted as restrictive of the scope of the present invention. Hence, all equivalent modifications or amendments made to the aforesaid embodiment should fall within the scope of the appended claims.
Number | Date | Country | Kind |
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TW 103106593 | Feb 2014 | TW | national |