TW399238B - The method and device of removing the cooling by-product remained in the exhaust pipeline for the low pressure chemical vapor deposition (LPCVD) - Google Patents

Abstract

This is a device to sublime and vaporize ammonium chloride (NH4Cl) (the by-product in the silicon nitride deposition process). Reflux condition is prevented from entering into the reactor, and the vapor and particles is prevented to block the vacuum pump. The exhaustion pipeline includes the new valve assembly, sublimation and the cold trap, the cooling and heating device, to decrease the particle number of the cooled NH4Cl in the first path cold trap. Thus, it decreases maintenance work, increases equipment uptime, and increases product yield.

Description

Employees 'Cooperatives of the Central Bureau of Standards, Ministry of Economic Affairs, A7 B7---------- —' ——-------- ~~ ---. V. Description of the Invention (1) The present invention relates to An apparatus and method for manufacturing a semiconductor thin film. In particular, the present invention relates to a method and a device which can effectively reduce the buildup of solids in a low pressure chemical vapor deposition film manufacturing process. The following four documents are related to the use of hot traps and cold traps. (Condenser) (cold trap) A method for separating a source substance from a reaction chamber. U.S. Patent No. 4,168,741 issued to K. Degenhardt et al. On September 25, 1979 shows an apparatus for supplying ammonia gas in a photocopying machine. US Patent No. 5,015,503 issued to R. D. Varrin, Jr. et al. On May 14, 1991 discloses a device for manufacturing a compound semiconductor thin film. The device includes a heat trap and a condenser for separating source materials from the reaction chamber, and provides a supply for controlling reaction species. The heat trap and condenser are connected to the reaction chamber via hot and cold feet to establish a closed loop circulating flow. US Patent No. 5,250,323 issued to S. Miyazaki on October 5, 1993, discloses a chemical vapor growth device having an exhaust device including a trap. This patent includes a trap, which is arranged in the first exhaust device to absorb the source gas remaining in the source gas inlet and the gas flow rate controller. W. Basta et al., Issued on November 16, 1993. US Patent No. 5,261,963 discloses a CVD apparatus including an exhaust gas phase condensation apparatus. This device includes a reactor, the reactor has a reaction chamber, the reaction chamber has a deposition area for depositing substrates, and an exhaust area "total cost of condensation paper size free use Chinese National Standard (CNS) 8 4 specifications (2 丨 0 > < 297 mm) (Please read the notes on the back before filling out this page) Order " Λ7 B7_____ V. Description of the invention (2) It is set in the exhaust area to be used before the used gas has entered the outlet Excessive, unreacted gaseous reactants in the used gas are condensed. This condensation assembly includes a high surface area, porous structure located in the exhaust zone, in which the temperature of the used gas stream is sufficiently reduced to condense excessive, unreacted gaseous reactants from it. Phase deposition (LPCVD) is a known method for depositing and forming a protective film on a substrate. Generally speaking, the substrate is placed in a reaction chamber, heated to an appropriate reaction temperature, and exposed to one or more elevated-temperature gaseous reactants in the reactor to react with the substrate surface to form a coating thereon. . The LPCVD deposited coating can be reacted with the substrate by appropriate heating in a reactor to form a protective diffusion coating thereon. The ammonium gaseous by-product is produced during the silicon nitride process when a thin silicon nitride layer is formed on a semiconductor substrate in an LPCVD reactor. This vaporized ammonium is produced in the gas phase and quickly crystallizes into a vapor / crystal mix and is discharged from the exhaust port. This vapor / crystallized mixture is taken into a condenser. Printed by the Consumers' Cooperative of the Central Ramp Bureau of the Ministry of Economic Affairs (please read the precautions on the back before filling this page)

A By definition, the condenser acts as a cryopump. The system pressure is reduced in the vacuum system due to the low temperature condensation of the vapor. When a surface is introduced into a system whose temperature is sufficiently low to condense the vapor present, the pressure in the system becomes the pressure of the vapor pressure of the condensate. When the condensate solidifies, a slight drop in the temperature of this solid will usually result in a dramatic drop in vapor pressure. The cryopump is based on the above principle. In some cases, the trap is used to condense or freeze these vapors, to steam the flow of 4 papers. Applicable to China National Standard (CNS) Conglin (2 丨 〇χ297 公 楚) '~~ *-Economy Printed by the Central Standards Bureau of the Ministry of Work and Consumer Cooperatives A 7 _________B7 V. Description of the Invention (3) " — ~ 'The gas (oil or mercury) is pumped out of the vacuum line, or pumped out. In other cases, the main function of a trap is to reduce the extraction time by extracting various condensable vapors. The condenser used in traditional LPCVDs collects and retains the NΗ4α solids so that they do not enter the vacuum pump. This can prevent the solids from damaging the pump when the steam is extracted. When the Nha solids increase during condensation, the system pressure gradually becomes difficult to control. In order to avoid that the vapor cannot be extracted from the reaction chamber due to the increase in solid volume in the condensing line, the LPCVD process must be stopped. Maintenance personnel must remove and clean the vacuum lines, thus reducing the utilization of the equipment process. Circles 1a to 1c show many specific embodiments of conventional exhaust lines. Each embodiment includes an LPCVD reactor 10 ′ having an exhaust outlet 14, a pressure sensor 15, a first valve 23 ′, a condenser 11, and a vacuum fruit 21 ′ in the order described above. Sequence settings. A second valve 24 is provided to provide another passage to bypass the first valve 23. During the LPCVD preparation, all valves are closed, a semiconductor substrate and a source substance (not shown) are placed and sealed in the reaction tube 20. At the beginning of the sedimentation cycle, the second valve 24 is opened to limit the surge of air from the reaction tube ', thereby avoiding the interference of NH4C solids being introduced into the vacuum pump 21 in the exhaust line. When the chamber pressure drops to a predetermined maximum value, the first valve 23 is opened to accelerate the pressure down to a predetermined process force. The source material is heated to a predetermined evaporation temperature. This vapor surrounds the semiconductor substrate and reacts with it to form a nitride protective film thereon to obtain an NH4C < by-product vapor. This by-product vapor is discharged, and when it is discharged, the paper size is applicable to the Chinese National Standard (CNS) A4 specification (210X297). (Please read the precautions on the back before filling this page}

.V, π Printed by the Shellfish Consumer Cooperative of the Central Ladder Bureau of the Ministry of Economic Affairs A7 B7 V. Description of the Invention (4) Crystallization starts at 14:00 of the exhaust outlet. When this vapor / crystal mixture is pushed into the exhaust line, passes through the opened first valve 23 and enters the condenser η, the crystals are condensed, and only the vapor can be pushed out and discharged by the pump 21. The temperature of the condenser 11 is obtained by circulating the cold water in the attached cold plate with an extended conductive surface to solidify the NH4C / and retain the NH4C / so as not to be taken in by the pump 21. Generally speaking, ’NH4C / by-products crystallize at a location that is sufficiently cold in the reactor exhaust line, resulting in clogging of the exhaust line. Exhaust clogging issues can affect process pressure control and cause the LPCVD plant to stop. Preventive maintenance requires time-consuming disassembly and cleaning steps, reflecting the increase in manufacturing costs due to lower equipment utilization. "Current semiconductor chemical processes require effective reduction of solids through the process to achieve less maintenance and products. Yield improvement. A solution that can effectively reduce these contaminants in the pump circuit is to use a combination of a heating circuit and a vapor sublimation trap. This vapor sublimation trap attracts the exhausted vapor ' and solidifies it before it has a chance to return to the reaction chamber to contaminate the semiconductor substrate. It also prevents vapors and particles from entering and damaging the vacuum pump. Gaseous by-products produced during semiconductor CVD and etching processes can be easily extracted from the reaction chamber. However, because the line temperature is lower than the temperature of the reaction chamber, they are usually cured in a vacuum line. Line congestion means longer downtime and lower product yields', especially for larger wafers and smaller feature size trends. This paper size is applicable to China National Standard (CNS) A4 (21〇X 297 mm) (Please read the precautions on the back before filling this page) J. Order ^ f ^ mr ^ r ^ f ^ rs' ^ ii ttiAr ^ nzw ^ > ASV? 297

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®ν * ^ F Lengzhai 0 s MLΛσ (NHUC,) coffee-J _It & U- Sr 4, § ΛΓ NWI * s ^ \\\ ^. V & p 」$ 隹 Λ * 涂 紫 4 Xu + 华Although d ο report to Saki do article. Bismuth X Feng IsriAQ Ge 50 3HOWH-JM $ Μ Tea batch t rush selection 卅 3 Ο Λ Printed by the Consumers' Cooperative of the Central Standards Bureau of the Ministry of Economy time. An object of the present invention is to provide an improved LPCVD apparatus and method in which reflux and damage to a vacuum pump can be avoided by collecting vapors and particles generated in a reactor during a gasification crushing process. Another object of the present invention is to provide an improved device and method in which the volume of NH4C 彳 solids condensed and collected is maintained to a minimum, thereby avoiding process control problems for semiconductor substrates processed in the reactor and damage. Another object of the present invention is to reduce the frequency of disassembling and cleaning the equipment, thereby increasing the utilization of the equipment. Brief Description of the Drawings Figures la, lb, and lc are diagrams of many vapor exhaust lines of conventional technology. Fig. 2 is a partial structure 囷 of a specific embodiment of the exhaust pipe of the present invention. The third circle is a partial structural diagram of a specific embodiment of an exhaust pipe according to another embodiment of the present invention. Figure 4 shows the vapor pressure circle of NH4Cf. First referring to Fig. 4, the vapor pressure profile of NH4C / is shown. Based on this, the transfer of NH4C / vapor to solid is plotted as a function of temperature versus pressure. The present invention is predicted based on the fact that NH4C / evaporates from the solid phase at a temperature of 75 ° C or above and a pressure of 3 X 10 · 3 Torr. This fact applies to the paper size of China National Standard (CNS) A4 (210X297 mm) (please read the precautions on the back before filling this page) Order. 1 · Μ B7 V. Description of the invention (7) Heating and pressure cause the NH4C € solid to evaporate in the exhaust line and reduce its volume. Referring to FIG. 2, there is shown an LPCVD deposition system including a process reactor 10 having a reaction chamber 11 having a deposition region 13 for depositing a substrate (not shown) and an exhaust region 12 It is connected to Shenji District 13. This deposition zone includes a device (not shown) that introduces a source material. The source material is heated to react with the substrate to form a protective layer thereon, while producing an NH4C / vapor by-product. The exhaust area 12 includes a device for introducing NH4C vapor generated in the reaction chamber into an exhaust line 15 through a reactor outlet 14. In a specific embodiment of the present invention, as shown in FIG. 2, an insulated and heated vacuum pipe π started from the process reactor outlet 14 is guided through a vacuum pipe 15 to a vacuum environment. This vacuum line branches off near the exit of the sublimation trap 31. The first path is generated after the valve 33, and the second path is generated after the valve 36, and the two ends at the pumps 37 and 38, respectively. Yin Ben, the Central Bureau of Standards and Quarantine of the Ministry of Economic Affairs (please read the notes on the back before filling this page) In a typical LPCVD deposition cycle, a semiconductor substrate and a source substance (not shown) are placed in the deposition area 13 The thermal controller 34 is closed, the valve 33 is opened, and the vacuum pumps 37 and 38 are opened. The process reactor is hermetically sealed and must be evacuated to reduce its pressure. Open one or two-stage valve 23. Valve 23 is a separation valve that allows the vacuum system to slowly evacuate. The two stages of this valve consist of a small return valve and a main disconnect valve. This shuttle valve establishes a small opening for initial pump down 'to slow down the system's pumping. This reduces the application of the Chinese National Standard (CNS) A4 specification (210X297 mm) due to particles disturbing the paper size. The printing bag A7 of the Consumer Cooperatives of the Central Bureau of Economic Affairs of the Ministry of Economic Affairs ______B7 V. Description of Invention (8) Pollution and damage due to sudden pressure changes. When the process pressure and temperature are reached, the vapor deposition cycle begins. The deposition of the reaction between the source material and the semiconductor substrate will produce vaporized ammonium (NH / O by-products. This vapor is exhausted through outlet 14. When NH4 < ^ vapor is cooled, at a temperature of less than 75 ° C and Crystallization begins at pressures greater than 3 x 10-3 Torr. Cooling occurs immediately and the vapor and crystal mixture enters outlet 14. When the vapor / crystal mixture is removed via outlet 14, the vapor / crystal mixture is condensed Introduced and held in the sublimation trap 31. When the deposition cycle is complete 'close the main valve 23 and valve 33 to isolate the first path of the vacuum line. Open the valve 36 so that the second path is pumped down by the vacuum pump 38. Second The path has a condenser 32, which is placed between the sublimation trap 31 and the vacuum pump 38, and will be connected only when the valve 36 is opened. When the product is loaded and unloaded, 'the thermal controller 34 is opened, and the mixing valves 43 and 44 are opened so that Hot and cold water is circulated to the hot surface of the sublimation trap 31 to evaporate solid NH / f therein. A sensor 34a provides temperature feedback to the thermal controller 34 to control the mixing valves 43 and 44. This thermal controller maintains Rise The trap is in the ideal gas phase state to remove and / or reduce solids generated in the trap 31. Vapors and particles are transferred to the condenser 32 and re-condensed. Before closing the valve connected to the second path, By introducing nitrogen into the vacuum duct between the main valve 23 and the trap 31, the vacuum environment established by the pump% is discharged to the atmosphere. After the nitrogen is purged, all paper standards are closed. Applicable to Chinese national standards (CNS) ) A4 specification (2 丨 0X29 * 7 public Chu) (Please read the precautions on the back before filling this page)

1T -1. Printed by the Central Laboratories of the Ministry of Economic Affairs, Shellfish Consumer Cooperative, A7 B7 V. The valve of invention description (9), the valve 33 is opened to prepare to start the next process cycle. Referring to Section 3, a second embodiment of the present invention will be described. The insulated vacuum conduit 17 starting at the outlet 14 of the process reactor, guides a vacuum environment through the vacuum conduit. This vacuum line branches off near the exit of the sublimation trap 31. The first path is generated after the valve 33, and the second path is generated after the valve 36. By adding a valve 51 provided at the outlet end of the condenser 32, the condenser 32 can be separated from the first and second paths. By adding the valve 51, only one vacuum pump 37 is required. The operation sequence of the second embodiment is the same as that of the first embodiment, except that the opening and closing of the valve 51 are different. The switching sequence is the same as that of the valve 36. Both are turned on and off at the same time. "With the combination of sensors and feedback, the tool controller can perform the operation sequence of the sublimation cycle, and perform processing of by-products in the first exhaust path, leaving only Manually clean the condensate in the condenser in the second path. The present invention reduces the frequency of this manual cleaning, and can perform this manual cleaning during the silicon nitride deposition process. According to the difference in the design of the sublimation trap 31, the inlet end of the condenser 32 may also be connected to the entrance of the sublimation trap 31 in parallel to perform the functions of the aforementioned design. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make changes and retouching without departing from the spirit and scope of the present invention. The scope of protection shall be determined by the scope of the attached patent application. 11

This paper size applies to China National Standard (CNS) A4 (210X 297 mm) (Please read the precautions on the back before filling this page)

Claims (1)

Printed by the Central Standards Bureau of the Ministry of Economic Affairs, Shellfish Consumer Cooperatives 6. Scope of patent application 1. A method for removing condensed by-products retained in the exhaust pipeline of a low-pressure chemical vapor deposition device. The condensed by-products are The processing and removal of the condensed by-products of the vapor phase produced by the chemical reaction between the source substance in the reactor of the low-pressure chemical vapor deposition device and the semiconductor substrate includes the following steps: placing a semiconductor substrate A protective layer is formed on a support of the process reactor; at least one source substance is introduced into the process reactor by a source substance introduction device; and the at least one source substance is used to form the semiconductor substrate on the semiconductor substrate. A protective layer is formed thereon; the vapor by-products generated by the chemical reaction of the process reactor are discharged; a first path device is provided to discharge the vapor by-products, and the first path device includes a sublimation trap to condense and store A condensed by-product 'and prevent the by-product vapor from flowing back and damaging the first path vacuum pump; providing a first The path device is 'parallel to the first path device'. The second path includes a separation valve, a condenser, and an auxiliary vacuum pump. A two-stage valve is provided to complete the first step after the low-pressure chemical vapor deposition process is completed. The first and second paths are separated from the process reactor; a second separation valve device is provided, which is provided at the inlet of the first pump device to heat the condensed by-products retained in the sublimation capture device 12 paper sizes applicable China National Standard (CNS > A4 specification (210X297 mm) 1 ^ 7 ------ (Please read the note on the back before filling in this page) Order the A8 printed by the Bayer Consumer Cooperative of the Central Standards Bureau of the Ministry of Economic Affairs B8 C8 D8, the patent application scope Gu Shi Zhao 'to separate the first fruit device from the sublimation capture device; and to provide a condenser separation valve device, which is set at the inlet of the condenser, in the process of growth Separate the outlet of the sublimation capture device from the first path from the condenser device. 2. The method as described in item 丨 of the patent application range, wherein the temperature of the sublimation capture device can be adjusted to Condensate vapor by-products during nitride growth. 3. The method as described in item 1 of the patent application scope, wherein the temperature of the sublimation trap can be adjusted to evaporate the condensed by-products after the nitride growth process is completed to remove them. Removed from the sublimation trap. 4. The method as described in item 1 of the scope of patent application, wherein the temperature of the sublimation trap is detected by a thermoelectric chirp, and controlled by a temperature controller to communicate with a The programmed tool controller is consistent. 5. As described in item 1 of the scope of the patent application, by heating the condensed by-product to an evaporation temperature, and by heating the condensed by-product during product loading and unloading. Drain into the second path condenser to remove condensed by-products from the sublimation trap, thereby requiring less maintenance, increasing equipment availability, and improving product yield. 6. The method according to item 1 of the scope of patent application, wherein the source gases are digas silane and ammonia. 7. The method according to item 6 of the patent application, wherein the cleaning gas is nitrogen. 8. The method described in item 7 of the scope of the patent application, in which the second paper size is applied to the application of the national standard of China (CNS) A4 (210X297 mm) (please read the note on the back before filling in this page) ) Order -f A8 B8 C8 D8 Printed and patented by the Central Industrial Standards Bureau of the Ministry of Economic Affairs, Zhengong Consumer Cooperative. The condenser includes an adsorbent, which is a component selected from the source gas. 9. A device for removing condensed by-products retained in an exhaust line of a low-pressure chemical vapor deposition device, the condensed by-products being a source substance and The gas phase produced by the chemical reaction between the semiconductor substrates. The device for processing and removing the condensed by-products includes: a process reactor to perform a low pressure chemical vapor phase growth process to a semiconductor substrate; Forming a protective layer; an exhaust device to exhaust vapor by-products produced by the chemical reaction of the process reactor; a first path device to exhaust the vapor by-products, the first path device including a sublimation trap A condensed by-product is condensed and stored, and the by-product vapor is prevented from flowing back and damaging the vacuum pump of the first path; a second path device is arranged in parallel with the first path device, and the second path includes a separation valve , A condenser, and an auxiliary vacuum pump; a two-stage valve to connect the first and second paths with the Process reactor separation; a second separation valve device 'is provided at the inlet of the first pump device to heat the condensed by-product solids retained in the sublimation capture device, the first pump device and the sublimation The capture device is separated; and a condenser separation valve device is provided at the inlet of the condenser to separate the outlet of the first path sublimation capture device from the condenser device during nitride growth. (Please read the precautions on the reverse side before filling out this page) n ^ n H · Order _! 14 A8 B8 C8 D8 Six «The Ministry of Economic Affairs of the Chinese Ministry of Economy and Trade Coordination Bureau Shellfish Consumer Cooperatives printed the scope of patent application 10. If you apply for a patent The device of range 9 wherein the shirt of the sublimation trap can be adjusted to condense vapor by-products during nitride growth. ... w 11. The device according to item 9 of the scope of the patent application, wherein the temperature of the sublimation trap can be adjusted to evaporate the condensed by-products after the nitride growth process is completed to remove it from the sublimation trap. 12. The device according to item 9 of the scope of patent application, wherein the temperature of the sublimation trap is detected by a thermoelectric device and controlled by a temperature controller to be consistent with a stylized tool controller. 13. The device according to item 9 of the scope of the patent application, wherein the generation of solids is reduced by heating all pump lines and vacuum elements, including valves' in the first path. 14. The device described in item 9 of the scope of patent application, which can optionally remove the second-path vacuum pump by adding a separation valve provided at the outlet of the condenser of the second-path, and An outlet of the separation valve is connected to the first path adjacent to an inlet of the first path vacuum pump. 15. The device as described in item 9 of the scope of patent application, by heating the condensed by-product to an evaporation temperature, and by condensing the evaporated by-product to the second path during product loading and unloading To remove condensed by-products from the sublimation trap, thereby requiring less maintenance, increasing equipment availability, and improving product yield. 15 This paper uses the Chinese National Standard (CNS) A4 size (210X297 mm) τ. Pay ------ π ------ line ... t (Please read the precautions on the back before reading (Fill in this page)