JP4357786B2 - Heat treatment apparatus and heat treatment method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heat treatment method and a heat treatment apparatus to which the heat treatment method is applied. In particular, the present invention relates to a heat treatment method and a heat treatment apparatus for heating a gas by radiation from a heating element using a lamp or the like, and heating a substrate to be processed or a formation on the substrate to be processed by the heated gas.
[0002]
[Prior art]
In the manufacturing process of a semiconductor device, heat treatment for the purpose of oxidation, diffusion, gettering, recrystallization after ion implantation, etc. is incorporated into a semiconductor or a semiconductor substrate. As a typical example of an apparatus for performing these heat treatments, a hot-wall type horizontal or vertical furnace annealing furnace is known.
[0003]
A horizontal or vertical furnace annealing furnace is a batch-type apparatus that processes a large number of substrates at once. For example, in a vertical furnace annealing furnace, a substrate is placed horizontally and in parallel on a susceptor made of quartz, and is moved into and out of a reaction tube by an elevator that is driven up and down. A heater is installed on the outer periphery of the bell jar type reaction tube, and the substrate is heated by the heater. In view of this configuration, a relatively long time is required for the temperature raising time until the predetermined heating temperature is reached and the temperature lowering time for cooling to a temperature at which it can be taken out.
[0004]
However, MOS transistors and the like used for integrated circuits are required to have extremely precise processing accuracy with miniaturization. In particular, it is necessary to minimize the diffusion of impurities to form a shallow junction. The process that takes time to raise and lower the temperature as in the furnace annealing furnace described above makes it difficult to form a shallow junction.
[0005]
The Rapid Thermal Anneal (hereinafter referred to as RTA) method has been developed as a heat treatment technique for rapid heating and rapid cooling. In the RTA method, an infrared lamp or the like is used to rapidly heat a substrate or a formed material on the substrate, and heat treatment can be performed in a short time.
[0006]
On the other hand, thin film transistors (hereinafter referred to as TFTs) are attracting attention as a technology that can directly form an integrated circuit on a glass substrate. The technology is being applied to new electronic devices such as liquid crystal display devices. In particular, TFTs that form impurity regions such as source and drain regions in a polycrystalline semiconductor film formed over a glass substrate require activation and heat treatment to alleviate strain. However, the glass substrate has a defect that the strain point is at most about 600 to 700 ° C., has poor heat resistance, and easily breaks due to thermal shock.
[0007]
[Problems to be solved by the invention]
In conventional vertical or horizontal furnace annealing furnaces, whether the substrate on which the integrated circuit is formed is a semiconductor or a material such as glass or ceramic, the uniformity of the heat treatment temperature is ensured as the substrate size increases. It becomes difficult to do. In order to ensure the uniformity of the temperature in the substrate and between the substrates, it is necessary to widen the interval (pitch) between the substrates to be placed horizontally and in parallel considering the characteristics of the gas flowing in the reaction tube as a fluid. is there. For example, if one side of the substrate exceeds 500 mm, the substrate interval needs to be 30 mm or more.
[0008]
Therefore, when the substrate to be processed is enlarged, the apparatus is necessarily enlarged. In addition, since a large number of substrates are processed in a lump, the weight increases by itself, and it is necessary to make a susceptor for placing a substrate to be processed strong. For this reason, the weight further increases, and the operation of the machine for carrying in / out the substrate to be processed becomes slow. In addition to increasing the floor area occupied by the heat treatment apparatus, it also affects the construction cost of the building in order to ensure the load resistance of the floor. Thus, the enlargement of the apparatus has a vicious circle.
[0009]
On the other hand, the RTA method is premised on single-wafer processing, and the load on the apparatus does not increase extremely. However, there is a difference in the absorptance of the lamp light used as the heating means depending on the characteristics of the substrate to be processed and the formed material thereon. For example, when a metal wiring pattern is formed on a glass substrate, the metal wiring is preferentially heated, causing a phenomenon that local distortion occurs and the glass substrate is broken. Therefore, in heat treatment, complicated control such as adjusting the temperature rising rate is required.
[0010]
An object of the present invention is to solve the above-mentioned problems, and an impurity element added to a semiconductor film by a short heat treatment without deforming the substrate in a manufacturing process of a semiconductor device using a substrate having low heat resistance such as glass. It is an object of the present invention to provide a method of performing activation and gettering treatment of the metal and a heat treatment apparatus capable of such heat treatment.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, a heat treatment apparatus having a first configuration according to the present invention includes means for supplying a gas from the upstream side of the reaction tube, means for heating the gas upstream of the reaction tube, Means is provided for holding the substrate to be processed on the downstream side, and means for circulating the gas from the downstream side to the upstream side of the reaction tube.
[0012]
In addition to the above configuration, a reaction tube having an intake portion for sucking gas and an exhaust portion for exhausting the sucked gas, a heating means for heating the gas sucked in the reaction tube, and the heated gas in the reaction tube There may be provided means for supplying the substrate to be processed disposed on the substrate and means for circulating the gas discharged from the exhaust part to the intake part.
[0013]
The reaction tube is made of quartz or ceramic to prevent contamination from the inner wall. As the heating means, one or a plurality of types selected from a halogen lamp, a metal halide lamp, a high-pressure mercury lamp, a high-pressure sodium lamp, and a xenon lamp are applied. However, when gas is directly heated by radiation from the lamp, the efficiency is deteriorated. Preferably, the heating means is formed by combining a heat generating means and a heat absorber that absorbs heat radiation from the heat generating means. With this combination, the heat absorber absorbs the radiation light and heats it, so that the gas can be heated by heat conduction therefrom. The heat transfer efficiency can be improved by increasing the area where the heat absorber is in contact with the gas.
[0014]
In addition, by circulating the gas used for heating the substrate to be processed, power for heating the gas can be saved. Although some of the circulating gas may be exhausted, it can be used as a heat source for preheating the newly introduced gas.
[0015]
As a configuration that positively utilizes the preheating effect of the heated and circulating gas, means for supplying gas from the upstream side of the reaction tube via a heat exchanger, and means for heating the gas upstream of the reaction tube; The heat treatment apparatus may also include a means for holding the substrate to be processed on the downstream side of the reaction tube and a means for supplying gas to the heat exchanger from the downstream side of the reaction tube.
[0016]
In addition to the above configuration, a reaction tube having an intake section for sucking gas and an exhaust section for exhausting the sucked gas, a heat exchanger provided in the front stage of the intake section, and the gas through the heat exchanger Supplying means; heating means for heating the sucked gas in the reaction tube; means for supplying the gas heated by the heating means to the substrate to be processed disposed in the reaction tube; and heating the gas discharged from the exhaust section And a means for supplying to the exchanger.
[0017]
As a form in which a plurality of processing chambers are provided and the heated gas is used efficiently, a processing chamber for holding a substrate and performing heat treatment is provided, and the substrate is supplied by supplying the gas heated by the heating means to the processing chamber. A heat treatment apparatus for heating, wherein a plurality of treatment chambers are provided, and a plurality of substrates can be simultaneously heat treated by flowing heated gases sequentially into the treatment chambers. An auxiliary heating means may be provided between the processing chambers so that the gas flowing sequentially between the plurality of processing chambers has a constant temperature. The heated gas that circulates can also be used as a heat source for heating the newly introduced gas through the heat exchanger.
[0018]
In the heat treatment apparatus having the second configuration having such a function, the gas supply means is connected to the inlet of the first gas heating means via the heat exchanger, and the inlet of the first processing chamber is the first inlet. Connected to the outlet of the gas heating means, the outlet of the first processing chamber connected to the second gas heating means and the inlet, and the inlet of the second processing chamber connected to the outlet of the second gas heating means And the discharge port of the second processing chamber is connected to the heat exchanger, and the substrate is heated using the gas heated by the heating means as a heat source.
[0019]
In addition to the above configuration, the gas supplied from the gas supply means is supplied to the first heating means via the heat exchanger, the gas heated by the first heating means is supplied to the first processing chamber, The gas supplied to the first processing chamber is supplied to the second heating means, the gas heated by the second heating means is supplied to the second processing chamber, and the gas supplied to the second processing chamber is supplied to the heat exchanger. Is used as a heat source for heating the gas supplied from the gas supply means, and the substrate is heated using the gas heated by the heating means as the heat source.
[0020]
The processing chamber is made of quartz or ceramic to prevent contamination from the inner wall. The first processing chamber and the second processing chamber are connected by a gas pipe, and the gas heated by the heating means is flowed from the first processing chamber to the second processing, whereby energy for heating the gas is obtained. Can be saved. Of course, since the temperature of the gas decreases during this time, a gas heating means is provided between the first processing chamber and the second processing chamber so that the temperature of the gas flowing between the processing chambers becomes constant.
[0021]
The number of processing chambers connected by gas pipes can be arbitrary. That is, another configuration of the heat treatment apparatus of the present invention includes n (n> 2) processing chambers and gas heating means, and introduces an m-th (1 ≦ m ≦ (n−1)) processing chamber. The inlet is connected to the outlet of the mth gas heating means, the inlet of the nth processing chamber is connected to the outlet of the nth gas heating means, and the outlet of the nth processing chamber is connected to the heat exchanger. It is a heat treatment apparatus for heating a substrate using a gas connected to and heated by a heating means as a heat source.
[0022]
In addition to the above configuration, there are n (n> 2) processing chambers and gas heating means, and the gas heated by the m-th (1 ≦ m ≦ (n−1)) heating means is the m-th treatment. The gas supplied to the mth processing chamber is heated by the (m + 1) th heating means and supplied to the (m + 1) th processing chamber, and the gas supplied to the nth processing chamber is supplied to the heat exchanger, This is a heat treatment apparatus that uses a gas supplied from a gas supply means as a heat source for heating, and heats the substrate using the gas heated by the heating means as a heat source.
[0023]
The gas supply means includes a first gas supply means connected to the gas heating means as a heating gas and a second gas supply means connected to each processing chamber as a cooling gas. can do. By supplying the heating gas and the cooling gas as separate systems, the time required for heating the object to be processed and the time required for cooling can be shortened, and the throughput can be improved.
[0024]
Such a configuration of the heat treatment apparatus of the present invention includes a first gas supply unit, a gas heating unit, and a plurality of processing chambers, and the first gas supply unit includes a plurality of processing chambers via the gas heating unit. The second gas supply means is connected to the pipe connected in parallel to each of the plurality of processing chambers, and heats the substrate using the gas heated by the heating means as a heat source. is there.
[0025]
By heating the substrate to be processed with the heated gas, the substrate can be heated with good uniformity without being affected by the material of the formed material. Accordingly, heat treatment can be performed without causing local distortion, and it becomes easy to complete the heat treatment by rapid heating even for a glass or a fragile substrate.
[0026]
In the heat treatment method using the heat treatment apparatus of the first configuration in the present invention, gas is supplied from the upstream side of the reaction tube, heated by the heating means provided on the upstream side, and flowed downstream, the gas Is heated from the downstream side of the reaction tube to the upstream side, and the substrate to be processed provided on the downstream side of the reaction tube is heated.
[0027]
In addition to the above method, after supplying gas from the intake portion of the reaction tube, heating the gas by the heating means provided in the reaction tube and flowing it downstream, and exhausting the gas from the exhaust portion of the reaction tube This is a method of heating the substrate to be processed disposed in the reaction tube while supplying the gas again from the intake section and circulating the gas.
[0028]
By heating the substrate to be processed with the heated gas, the substrate can be heated with good uniformity without being affected by the material of the formed material. Accordingly, heat treatment can be performed without causing local distortion, and it becomes easy to complete the heat treatment by rapid heating even for a glass or a fragile substrate.
[0029]
In the heat treatment method using the heat treatment apparatus having the second configuration of the present invention, the gas is supplied from the gas supply means to the first gas heating means via the heat exchanger, and the gas is heated by the first gas heating means. The heated gas is supplied to the first processing chamber, the gas discharged from the first processing chamber is heated by the second gas heating means, and the heated gas is supplied to the second processing chamber. Then, the exhaust gas discharged from the second processing chamber is supplied to the heat exchanger, and the substrate disposed in the processing chamber is heated using the gas heated by the heating means as a heat source.
[0030]
In addition to the above-described method, the m-th processing chamber is configured such that the gas heated by the m-th (1 ≦ m ≦ (n−1)) heating means by the n (n> 2) processing chambers and the gas heating means. The gas supplied to the m-th processing chamber is heated by the (m + 1) -th heating means and supplied to the (m + 1) -th processing chamber, and the gas supplied to the n-th processing chamber is supplied to the heat exchanger. This is a heat treatment method in which a gas supplied from a supply means is used as a heat source for heating, and a substrate disposed in n process chambers is heated.
[0031]
In addition to the above method, gas is supplied from the first gas supply means to the first gas heating means via the heat exchanger, the gas is heated by the first gas heating means, and the heated gas A heating period in which the gas discharged from the first processing chamber is heated by the second gas heating means, and the heated gas is supplied to the second processing chamber; And a cooling period in which gas is supplied from the two gas supply means to the first processing chamber and the second processing chamber without passing through the heating means, and the substrate disposed in the processing chamber is cooled. .
[0032]
In addition to the above method, the heating gas supplied from the first gas supply means by the n (n> 2) processing chambers and the gas heating means is the mth (1 ≦ m ≦ (n−1). )), The gas heated by the heating means is supplied to the m-th processing chamber, the gas supplied to the m-th processing chamber is heated by the (m + 1) -th heating means and supplied to the (m + 1) -th processing chamber, A heating period in which the gas supplied to the processing chamber is supplied to the heat exchanger and used as a heat source for heating the gas supplied from the gas supply means, and the substrate disposed in the n processing chambers is heated; This is a heat treatment method having a cooling period in which a cooling gas supplied from the gas supply means is supplied to n processing chambers to cool a substrate disposed in the processing chambers.
[0033]
By using a heated gas as in the structure of the above invention, even a glass substrate on which a predetermined pattern is formed of a metal, a semiconductor, an insulator, etc., is uniform without causing local thermal distortion. It becomes possible to heat to. Furthermore, by circulating the heated gas, the thermal efficiency can be improved and the energy consumption required for the heat treatment can be reduced.
[0034]
As the gas applied in the present invention, an inert gas such as nitrogen or a rare gas, a reducing gas such as hydrogen, or an oxidizing gas such as oxygen, nitrous oxide, or nitrogen dioxide can be used.
[0035]
If an inert gas such as nitrogen or a rare gas is used, heat treatment for crystallization of the amorphous semiconductor film, heat treatment for gettering, ion implantation or ion doping (method of implanting ions without mass separation) It can be applied to heat treatment for the purpose of subsequent recrystallization and activation.
[0036]
When hydrogen diluted with hydrogen or an inert gas is used as a reducing gas such as hydrogen, hydrogenation treatment for compensating for defects (dangling bonds) in the semiconductor can be performed.
[0037]
When an oxidizing gas such as oxygen, nitrous oxide, or nitrogen dioxide is used, an oxide film can be formed over the semiconductor substrate or the semiconductor film.
[0038]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a cross-sectional view showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied, and FIG. 2 is a top view corresponding thereto. In order to clarify the correspondence, the same reference numerals are used in FIGS. 1 and 2.
[0039]
The heat treatment apparatus shown in FIGS. 1 and 2 includes a reaction tube 1101 provided with a heating means 1105 comprising a heating element 1102 and an endothermic body 1104, a heating element control device 1103, gas supply means 1109, 1110, and a pressure control valve 1111. Yes.
[0040]
The reaction tube is made of quartz or ceramic to prevent contamination from the inner wall. Quartz is a member commonly used as a reaction tube material. Further, when the size of the substrate is increased, it is difficult to form a reaction tube with quartz according to the size, and in this case, ceramic may be applied.
[0041]
In the heating unit 1105, a halogen lamp, a metal halide lamp, a high-pressure mercury lamp, a high-pressure sodium lamp, a xenon lamp, or the like is used as the heating element 1102. The heating element control device 1103 is for controlling the heating element 1102 so as to obtain a predetermined temperature or predetermined heat radiation. The gas is heated by absorbing the radiation of the heating element 1102 or when the heating element 1102 is in contact with the gas. Further, as shown in the figure, a heat absorber 1104 formed of quartz, SiC, Si, or the like is provided around the heat generator 1102, and radiation from the heat generator 1102 is once absorbed by the heat absorber 1104. The gas may be heated by heat conduction. At this time, it is desirable to provide a structure in which fins are provided on the surface of the endothermic body 1104 to increase the contact area with the gas. Thus, the heating means 1105 is provided on the upstream side of the reaction tube 1101.
[0042]
The orifice plates 1106 and 1107 are provided between a region where the heating element 1102 is provided and a region where the substrate 1120 is installed. These orifice plates 1106 and 1107 are provided with pores for the purpose of controlling the flow rate and flow direction of the gas. The orifice plate 1106 is installed for the purpose of retaining gas in the region where the heating element 1102 is installed, and the orifice plate 1107 is provided to allow the gas to flow in from the direction perpendicular to the substrate 1102.
[0043]
The gas is guided from the gas supply means 1109 by the nozzle 1108 through the heat exchanger 1119 to the intake portion 1112 and introduced into the reaction tube 1101. The gas introduced into the reaction tube 1101 passes through the region where the heating element 1102 is provided, the orifice plates 1106 and 1107, and is discharged from the exhaust unit 1113 located on the downstream side of the reaction tube 1101. The exhausted gas is returned to the upstream side by the connecting pipe 1114, passes through the heat exchanger 1119, and flows into the reaction pipe 1101 again from the intake portion 1112. This is how it circulates. A part is discharged from the pressure control valve 1111 to the outside. The pressure control valve 1111 is provided to keep the inside of the reaction tube 1101 at a predetermined pressure.
[0044]
In the heat exchanger 1119, the heated gas circulates, and the gas supplied from the gas supply means 1109 can be preheated in advance by heating the nozzle 1108. By injecting gas from the tip of the nozzle 1108 at the intake portion 1112, convection is generated in the direction of the arrow shown in the figure, and a part of the heated gas that circulates and returns to the heat exchanger 1119 is again generated. It flows into the reaction tube 1101 from the intake portion 1112.
[0045]
Of course, the circulating gas is lower than the initial temperature, but by using such a closed system, the thermal efficiency can be improved and the consumed power can be saved. A heater 1116 may be provided on the outer periphery of the connecting pipe 1114 (1115 is a heater power source).
[0046]
The substrate 1120 to be processed is placed on the holding means 1117 in the reaction tube. The structure of the holding unit 1117 is configured to minimize the contact area with the substrate 1120 to be processed. A gate valve 1118 is provided at one end of the reaction tube 1101, and the substrate to be processed is taken in and out by opening and closing. The substrate 1120 to be processed is placed on the cassette 1122, and the transfer unit 1121 carries in and out the reaction tube 1101. The transport unit 1121 and the cassette 1122 are desirably installed under a clean unit 1123 that blows clean air in order to prevent the substrate 1120 from being contaminated from the surrounding environment.
[0047]
An example of the heat treatment procedure is shown below. After the substrate to be processed is set on the holding means 1117 and the gate valve is closed, a gas for heating is supplied from the gas supply means. After the gas supplied into the reaction tube is filled and held until replacement, the gas is heated by the heating means 1105. The heated gas passes through the orifice plates 1106 and 1107 and is irradiated to the substrate to be processed 1120 to be heated. Thereafter, the gas passes through the heat exchanger 1119 from the exhaust part 1113 and is supplied again from the intake part 1112 into the reaction tube 1101. The substrate 1120 is heat-treated by circulation of the heated gas.
[0048]
After a predetermined time has elapsed, the heating of the gas by the heating means 1105 is terminated. Then, a gas for cooling is supplied from the gas supply means 1110 to cool the substrate 1120 to be processed. By flowing this cooling gas, the temperature of the gas in the reaction tube is lowered, and the temperature of the substrate to be processed 1120 can be lowered. Thereafter, the gate valve 1118 is opened, and the substrate 1120 to be processed is taken out by the transfer means. As described above, the heat treatment of the substrate to be processed 1120 can be performed in a short time.
[0049]
The heat treatment method of the present invention and the heat treatment apparatus to which the heat treatment method is applied are premised on batch processing, but the substrate to be processed is heated directly by heating the gas. The substrate can be quickly cooled by cooling with a gas at about room temperature. Of course, care must be taken when using a substrate that is vulnerable to thermal shock, such as glass, but unlike in the case of conventional RTA, the substrate is destroyed by rapid heating, unlike instantaneous heating of several microseconds to seconds. There is no end to it.
[0050]
The gas used for heating or cooling can be selected depending on the application of heat treatment. If an inert gas such as nitrogen or a rare gas is used, heat treatment for crystallization of the amorphous semiconductor film, heat treatment for gettering, ion implantation or ion doping (method of implanting ions without mass separation) It can be applied to heat treatment for the purpose of subsequent recrystallization and activation. When hydrogen diluted with hydrogen or an inert gas is used as a reducing gas such as hydrogen, hydrogenation treatment for compensating for defects (dangling bonds) in the semiconductor can be performed. When an oxidizing gas such as oxygen, nitrous oxide, or nitrogen dioxide is used, an oxide film can be formed over the semiconductor substrate or the semiconductor film.
[0051]
In order to improve the processing capability, the configuration shown in FIG. 3 can be applied. In FIG. 3, reaction tubes 1201 to 1204 are the same as those in FIG. A heating means 1208 and its control device 1207, a pressure control valve 1212, and gas supply means 1209 and 1211 are provided.
[0052]
The heat exchangers do not have to correspond to the reaction tubes on a one-to-one basis. As shown in the figure, the reaction tubes 1201 and 1202 correspond to the heat exchanger 1205 and the reaction tubes 1203 and 1204 correspond to the heat exchanger 1206. Also good. Such a configuration is also possible if it is assumed that heat treatment is performed at the same temperature in a plurality of reaction tubes. Gas is supplied to each reaction tube from a gas supply means 1209 via a nozzle 1210. In addition, the conveyance means 1213 and the cassette 1214 are the same as those shown in FIG.
[0053]
The heat treatment apparatus having the configuration shown in FIG. 3 makes it possible to perform heat treatment at different temperatures and at different times in the reaction tubes 1201 and 1202 and the reaction tubes 1203 and 1204.
[0054]
Moreover, the heat processing apparatus shown in FIG. 4 has shown the form which abbreviate | omitted the heat exchanger. Here, in the reaction tubes 1301 and 1302, the heating means 1305 and the control device 1307 are common. Further, in the reaction tubes 1303 and 1304, the heating means 1306 and the control device 1307 are shared. In addition, a pressure control valve 1312 and gas supply means 1310 and 1311 are provided.
[0055]
Although the heat exchanger is omitted in FIG. 4, the gas supply unit 1310 supplies gas for heating, and the gas heated by the heating elements 1308 and 1309 in the heating units 1305 and 1306 is circulated. Is the same as FIG. In addition, the conveyance means 1313 and the cassette 1314 are the same as those shown in FIG.
[0056]
FIG. 5 shows the configuration of a heat treatment apparatus provided with a plurality of reaction tubes. The reaction tube 1401, the heating means 1411, the control device 1410, the gas supply means 1412 and 1414, and the heat exchanger 1413 can employ any one of the configurations described in FIG. Similarly, a reaction tube 1402, a heating unit 1416, a control device 1415, gas supply units 1417 and 1419, and a heat exchanger 1418 are provided. The transport means 1403 is for transporting the object to be processed from the cassette 1404 to and from each reaction tube. Reference numerals 1406 a to 1406 c are also cassettes each including a target object, and the target object is supplied to the cassette 1404 by the transport unit 1405.
[0057]
FIG. 5 shows an example of the configuration of the heat treatment apparatus based on the mass batch processing method, but it is not necessary to be limited to this configuration and arrangement, and any other arrangement can be adopted. Since the heat treatment apparatus described in this embodiment mode is a batch processing method and heats a substrate to be processed with a heated gas, heat treatment can be performed with high uniformity even when the size of the substrate is increased. For example, the present invention can be applied to a heat treatment of a substrate having a side length exceeding 1000 mm.
[0058]
Such a heat treatment method and a heat treatment apparatus using the heat treatment method of the present invention are not limited by the form and size of the substrate to be processed. The single wafer processing does not require a robust susceptor even if the substrate to be processed is enlarged, and the size can be reduced accordingly. Further, the heating means does not need a large scale, and power consumption can be saved.
[0059]
[Embodiment 2]
FIG. 10 is a sectional view showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied. The heat treatment apparatus of the present invention includes a plurality of gas supply means, a plurality of gas heating means, a plurality of processing chambers, and a heat exchanger.
[0060]
The first gas supply means 106, the heat exchanger 113, and the first gas heating means 108 are connected by gas pipes 10 and 11. The gas supplied from the first gas supply means 106 is preheated in advance by the heat exchanger 113 and supplied to the first heating means 108. First, the heating means 108 heats the gas to a predetermined temperature.
[0061]
The outlet of the first heating means 108 is connected to the inlet provided in the first processing chamber 101 by the gas pipe 12 and supplies heated gas. In the first processing chamber 101, a substrate holding means 115 and a shower plate 116 for spraying heated gas to the substrate are provided. Further, the supplied gas is discharged from an exhaust port provided in the first processing chamber 101.
[0062]
The treatment chamber is formed using quartz or ceramic in order to prevent contamination from the wall material when the heated gas is introduced. Further, when the size of the substrate is increased, it is difficult to form a processing chamber with quartz according to the size, and in this case, ceramic may be applied. The structure of the holding means 115 is configured to minimize the contact area with the substrate. The gas supplied to the processing chamber 101 passes through the shower plate 116 and is blown onto the substrate. Fine openings are formed in the shower plate 116 at predetermined intervals so that the heated gas can be sprayed uniformly on the substrate. By providing the shower plate 116, the substrate can be heated with good uniformity even if the area of the substrate is increased.
[0063]
The structure of such a processing chamber is the same in the second processing chamber 102, the third processing chamber 103, the fourth processing chamber 104, and the fifth processing chamber 105.
[0064]
The heated gas supplied to the first processing chamber 101 is used for heating the substrate 117 placed on the substrate holding means 115, and then supplied to the second processing chamber 102 to be used again for heating the substrate. . In this process, the temperature of the gas is lowered, so that the second heating means 109 controls the gas so as to reach a predetermined temperature. The gas pipe 13 is connected to the discharge port provided in the first processing chamber 101 and the introduction port of the second heating means 109, and the gas pipe 14 is connected to the discharge port of the second heating means 109 and the second processing chamber 102. Is connected to the inlet provided in the. Although not shown, these gas pipes may be provided with heat retaining means.
[0065]
Similarly, the heated gas supplied to the second processing chamber 102 is used for heating the substrate, and then supplied to the third gas heating means 110 through the gas pipe 15, and the third through the gas pipe 16. To the processing chamber 103. The heated gas supplied to the third processing chamber 103 is supplied to the fourth gas heating means 111 through the gas pipe 17 and supplied to the fourth processing chamber 104 through the gas pipe 18. The heated gas supplied to the fourth processing chamber 104 is supplied to the fifth gas heating means 112 through the gas pipe 19 and supplied to the fifth processing chamber 105 through the gas pipe 20.
[0066]
Here, a third gas heating means 110 is interposed between the second processing chamber 102 and the third processing chamber 103 by gas pipes 15 and 16. A fourth gas heating means 111 is interposed between the third processing chamber 103 and the fourth processing chamber 104 and connected by gas pipes 17 and 18. Between the fourth processing chamber 104 and the fifth processing chamber 105, a fifth gas heating means 112 is inserted and connected by gas pipes 19 and 20.
[0067]
As described above, the gas supplied from the first gas supply means 106 is heated by the gas heating means and continuously supplied from the first processing chamber to the fifth processing chamber. Gas heating means is provided between the processing chambers so that the temperatures of the gases supplied to the processing chambers are the same. Needless to say, the number of processing chambers may be set as required, and is not limited to the number shown in this embodiment mode.
[0068]
The substrates are installed one by one in one processing chamber. By connecting each processing chamber in series with a gas pipe and flowing a continuously heated gas, the amount of gas used can be saved, and the energy required for heating can be saved. .
[0069]
The second gas supply means 107 is connected to a pipe 22 that supplies gas in parallel to each of the plurality of processing chambers. The second gas supply means 107 supplies the heated process chamber or process substrate for cooling. The temperature suitable for supply is arbitrarily set, but may be about room temperature. The supplied gas is discharged to the outside of the processing chamber through the drain pipe 23.
[0070]
The heat exchanger 113 is provided to preheat the gas supplied by the first gas supply means 106 in advance. The gas supplied from the first gas supply means is heated by the heat of the gas discharged from the fifth treatment chamber 105. A gas pipe 21 is connected to a heat exchanger 113 from an outlet provided in the fifth processing chamber 105. The gas discharged from the fifth processing chamber 105 is discharged, but is cooled by passing through this heat exchanger. The supplied gas is heated by the heat. In this way, the energy required to heat the gas can be saved.
[0071]
An example of this heat exchanger is shown in FIG. A high-temperature gas flows into the heat exchanger, and a pipe 402 provided with fins as shown in the figure and a cold (usually room temperature) gas flow in and a pipe 401 similarly provided with fins are installed. is there. The casing 400 is filled with oil 403 as a medium for transferring heat. The fins are provided in order to improve the heat exchange efficiency. With such a configuration, the high-temperature gas transmits heat to the oil 403 and is discharged at a low temperature. The heat causes the cold gas to be heated by passing through the heat exchanger. Here, a simple example of the heat exchanger is shown, but the configuration of the heat exchanger applicable to the heat treatment apparatus according to the present invention is not limited to FIG. 13 and other configurations may be adopted.
[0072]
FIG. 12 shows an example of the configuration of the gas heating means. In FIG. 12, a heat absorbing body 303 is provided inside a cylinder 301 through which gas passes. The heat absorber 303 is made of high-purity titanium or tungsten, or silicon carbide, quartz, or silicon. The cylinder 301 is formed of translucent quartz or the like, and heats the heat absorbing body 303 by radiation of a light source 302 provided on the outside thereof. The gas is heated in contact with the endothermic body 303. However, by providing a light source outside the cylinder 301, contamination is prevented and the purity of the gas to be passed can be maintained. The inside of the housing 300 may be evacuated to increase the heat insulating effect.
[0073]
Next, an example of a heat treatment procedure using the heat treatment apparatus having the configuration shown in FIG. 10 will be described. After the substrate is disposed on the holding unit in each of the first processing chamber 101 to the fifth processing chamber 105, gas is supplied from the first gas supply unit 106. The gas is allowed to flow for a while without heating until the inside of each processing chamber or pipe is replaced. Thereafter, the gas is heated by the first gas heating means 108, the second gas heating means 109, the third gas heating means 110, the fourth gas heating means 111, and the fifth gas heating means 112. The heated gas in the processing chamber is blown onto the substrate through the shower plate to heat the substrate. The heated gas goes through each processing chamber and is supplied to the heat exchanger. And the gas supplied from the 1st gas supply means 106 is utilized as a heat source which warms.
[0074]
After a predetermined time has elapsed, the gas heating by the gas heating means 108 to 112 is terminated. Then, a gas for cooling is supplied from the second gas supply means 107 to cool the substrate. By flowing this cooling gas, the temperature of the gas in the processing chamber is lowered, and the temperature of the substrate can be lowered. Thereafter, the substrate is taken out to complete the heat treatment using the heat treatment apparatus of the present invention.
[0075]
The number of substrates that can be inserted into the processing chamber varies depending on the size of the processing chamber and the substrate. However, if one substrate is inserted into one processing chamber, processing can be performed by one heat treatment. The number of substrates is determined by the number of processing chambers.
[0076]
In order to save the gas used and improve the thermal efficiency, it is desirable to reduce the internal volume of the processing chamber as much as possible. The dimensions in the processing chamber are determined by the size of the substrate and the operating range of the transfer means for taking in and out the substrate. Since the transfer means requires an operation range of about 10 mm in order to take in and out the substrate, one dimension of the processing chamber is determined by the thickness of the substrate and the minimum operation range of the transfer means.
[0077]
The heat treatment method of the present invention and the heat treatment apparatus to which the heat treatment method is applied are premised on batch-type treatment, but the substrate to be treated is heated directly by heating the gas. The substrate to be processed can be quickly cooled by cooling it with a gas at room temperature. Of course, care must be taken when using a substrate that is vulnerable to thermal shock, such as glass, but unlike in the case of conventional RTA, the substrate is destroyed by rapid heating, unlike instantaneous heating of several microseconds to seconds. There is no end to it.
[0078]
The gas used for heating or cooling can be selected depending on the application of heat treatment. If an inert gas such as nitrogen or a rare gas is used, heat treatment for crystallization of the amorphous semiconductor film, heat treatment for gettering, ion implantation or ion doping (method of implanting ions without mass separation) It can be applied to heat treatment for the purpose of subsequent recrystallization and activation. When hydrogen diluted with hydrogen or an inert gas is used as a reducing gas such as hydrogen, hydrogenation treatment for compensating for defects (dangling bonds) in the semiconductor can be performed. When an oxidizing gas such as oxygen, nitrous oxide, or nitrogen dioxide is used, an oxide film can be formed over the semiconductor substrate or the semiconductor film.
[0079]
The heat treatment apparatus to which the heat treatment method of the present invention described above is applied can be applied to heat treatment of various objects to be processed. For example, the present invention can be applied to a heat treatment of a semiconductor substrate forming an integrated circuit, a heat treatment of an insulating substrate on which a TFT is formed, a heat treatment of a metal substrate, and the like. For example, it can be applied to heat treatment of a glass substrate on which a TFT is formed. Even if the substrate size is not only 600 × 720 mm but also 1200 × 1600 mm, the substrate can be heated with good uniformity. Further, it is not necessary to increase the size of the jig for holding the substrate.
[0080]
[Embodiment 3]
An embodiment of the heat treatment method of the present invention will be described with reference to FIG. FIG. 8 shows a time course (procedure) in the heat treatment using the heat treatment apparatus shown in FIG. Nitrogen (N ₂ ) Is used. A halogen lamp is used as the heating element.
[0081]
The substrate to be processed is set from the cassette into the reaction tube by the transfer means, and then the gate valve is closed. In the meantime, it is considered that nitrogen is continuously supplied from the gas supply means into the reaction tube to minimize the mixing of outside air. After closing the gate valve, the nitrogen flow rate is increased and the reaction tube is filled with nitrogen to replace it.
[0082]
Then, the nitrogen flow rate is increased, the halogen lamp as a heating element is turned on, and the nitrogen is heated. The heating temperature can be adjusted by the power supplied to the heating element or the supply amount of the power and nitrogen. The heating temperature can be approximately 100 to 1000 ° C.
[0083]
The substrate to be processed placed on the downstream side of the reaction tube is heated with heated nitrogen to perform heat treatment. The time is arbitrary. Although the temperature of nitrogen that has reached the exhaust section decreases, it is circulated and heated again by the heating element, and used for heating the object to be processed. Thereafter, a period until the halogen lamp is turned off is a substantial heat treatment period.
[0084]
After the halogen lamp is turned off, cooling nitrogen is supplied from the gas supply means to lower the temperature of the substrate to be processed. At this time, the flow rate of the heating nitrogen may be kept constant or may be lowered. In any case, since the halogen lamp is turned off, the temperature of nitrogen in the reaction tube decreases, and the temperature of the substrate to be processed also decreases. The rate of temperature drop is abrupt at first and then gradually decreases. When the temperature is about 200 ° C. or lower, the gate valve is opened and the substrate to be processed is taken out. At that stage, the supply of cooling nitrogen may be stopped.
[0085]
By repeating such a series of processes as one cycle, a large number of substrates can be processed continuously.
[0086]
[Embodiment 4]
FIG. 11 shows one embodiment of the heat treatment apparatus of the present invention. In FIG. 11, a first gas heating means 207 is provided corresponding to the first processing chamber 201, and a second gas heating means 208 is provided corresponding to the second processing chamber 202. The processing chamber 203 is provided with a third gas heating means 209 correspondingly, and the fourth processing chamber 204 is provided with a fourth gas heating means 210 correspondingly. Further, a first gas supply means 205, a second gas supply means 206, a heat exchanger 211, and an abatement means 212 are provided, and these pipes have the same configuration as the heat treatment apparatus described in the embodiment. Yes.
[0087]
The first gas supply means 205 supplies a heating gas. The second gas supply means 206 supplies a cooling gas.
[0088]
In each processing chamber, the substrate 215 held in the cassette 214 is transferred by the transfer means 213 and placed on the holding means 216. Each processing chamber takes in and out the substrate by opening and closing the gate valve.
[0089]
FIG. 14 shows a configuration of a heat treatment apparatus having a plurality of treatment chambers. Processing chambers 501 and 502, first gas supply means 506 and 509, second gas supply means 507 and 510, and gas heating means 508 and 511 are provided. The processing chambers 501 and 502 may be stacked in a plurality of stages, and a gas heating unit is provided correspondingly. Such a configuration may be referred to FIG. The buffer cassette 503 holds one end of the heat-treated substrate carried out of the processing chamber, and further cools the substrate. The cassettes 505a to 505c are applied when holding and transporting the substrate. The substrate is used to move between the cassettes 505a to 505c, the processing chambers 501 and 502, and the buffer cassette 503 by the transfer means 504.
[0090]
The number of processing chambers can be determined by the time required for the heat treatment and the operation speed of the transfer means (that is, the speed at which the substrate can be moved). If the tact time is about 10 minutes, 3 to 10 stages can be installed in the processing chambers 501 and 502.
[0091]
FIG. 14 shows an example of the configuration of the heat treatment apparatus based on the mass batch processing method, but it is not necessary to be limited to this configuration and arrangement, and any other arrangement can be adopted. Since the heat treatment apparatus shown here is a batch processing method and heats the substrate to be processed with a heated gas, heat treatment can be performed with good uniformity even if the size of the substrate is increased. For example, the present invention can be applied to a heat treatment of a substrate having a side length exceeding 1000 mm.
[0092]
Such a heat treatment method and a heat treatment apparatus using the heat treatment method of the present invention are not limited by the form and size of the substrate to be processed. The single wafer processing does not require a robust susceptor even if the substrate to be processed is enlarged, and the size can be reduced accordingly. Further, the heating means does not need a large scale, and power consumption can be saved.
[0093]
[Embodiment 5]
An example in which heat treatment accompanying crystallization and gettering of a semiconductor film is performed using the heat treatment method of the present invention and a heat treatment apparatus to which the heat treatment method is applied will be described with reference to FIG.
[0094]
In FIG. 6A, the material of the substrate 600 is not particularly limited; however, barium borosilicate glass, aluminoborosilicate glass, quartz, or the like can be preferably used. An inorganic insulating film having a thickness of 10 to 200 nm is formed on the surface of the substrate 600 as the blocking layer 601. An example of a suitable blocking layer is a silicon oxynitride film manufactured by a plasma CVD method, and SiH _Four , NH _Three , N ₂ A first silicon oxynitride film made of O is formed to a thickness of 50 nm, and SiH _Four And N ₂ A film in which a second silicon oxynitride film made of O is formed to a thickness of 100 nm is applied. The blocking layer 601 is provided so that the alkali metal contained in the glass substrate does not diffuse into the semiconductor film formed thereon, and can be omitted when quartz is used as the substrate.
[0095]
For the semiconductor film (first semiconductor film) 602 having an amorphous structure formed over the blocking layer 601, a semiconductor material containing silicon as a main component is used. Typically, an amorphous silicon film, an amorphous silicon germanium film, or the like is applied, and the film is formed to a thickness of 10 to 100 nm by a plasma CVD method, a low pressure CVD method, or a sputtering method. In order to obtain high-quality crystals, the concentration of impurities such as oxygen and nitrogen contained in the semiconductor film 502 having an amorphous structure is set to 5 × 10. ¹⁸ /cm ^Three It should be reduced to the following. These impurities interfere with the crystallization of the amorphous semiconductor, and also increase the density of trapping centers and recombination centers even after crystallization. Therefore, it is desirable not only to use a high-purity material gas but also to use an ultrahigh vacuum-compatible CVD apparatus equipped with a mirror surface treatment (electropolishing treatment) in the reaction chamber and an oil-free vacuum exhaust system.
[0096]
After that, a catalytic metal element that promotes crystallization is added to the surface of the semiconductor film 602 having an amorphous structure. Metal elements having a catalytic action for promoting crystallization of semiconductor films include iron (Fe), nickel (Ni), cobalt (Co), ruthenium (Ru), rhodium (Rh), palladium (Pd), and osmium (Os). , Iridium (Ir), platinum (Pt), copper (Cu), gold (Au), etc., and one or more selected from these can be used. Typically, nickel is used, and a catalyst-containing layer 603 is formed by applying a nickel acetate salt solution containing 1 to 100 ppm of nickel in terms of weight with a spinner. Crystallization can be performed in a shorter time as the nickel content increases.
[0097]
In this case, in order to improve the familiarity of the solution, as the surface treatment of the semiconductor film 602 having an amorphous structure, an extremely thin oxide film is formed with an ozone-containing aqueous solution, and the oxide film is formed using hydrofluoric acid and hydrogen peroxide solution. After etching with the mixed solution, a clean surface is formed, and then an ultrathin oxide film is formed again by treatment with an aqueous solution containing ozone. Since the surface of the semiconductor film such as silicon is inherently hydrophobic, the nickel acetate salt solution can be uniformly applied by forming the oxide film in this way.
[0098]
Needless to say, the catalyst-containing layer 603 is not limited to such a method, and may be formed by sputtering, vapor deposition, plasma treatment, or the like. Further, the catalyst-containing layer 603 may be formed before forming the semiconductor film 602 having an amorphous structure, that is, on the blocking layer 601.
[0099]
A heat treatment for crystallization is performed while the semiconductor film 602 having an amorphous structure and the catalyst-containing layer 603 are kept in contact with each other. For the heat treatment, a heat treatment apparatus having the structure shown in FIG. 10 is used. FIG. 15 is a graph for explaining the heat treatment process, which will be described below with reference to the graph.
[0100]
Nitrogen, argon, or the like can be used as the heating gas. The substrate 600 on which the amorphous semiconductor film is formed is set from the cassette into the reaction tube by the transfer means, and then the gate valve is closed. In the meantime, it is considered that nitrogen is continuously supplied from the gas supply means into the reaction tube to minimize the mixing of outside air. After closing the gate valve, the nitrogen flow rate is increased and the reaction tube is filled with nitrogen to replace it.
[0101]
Then, the nitrogen flow rate is increased, and the nitrogen gas supplied by the gas heating means is heated to the first temperature. The heating temperature can be adjusted by the power supplied to the heating element or the supply amount of the power and nitrogen. Here, the substrate is heated to 550 ± 50 ° C. as the first temperature (step of temperature increase 1 shown in FIG. 15). The time required to raise the temperature is only 2 minutes.
[0102]
When the substrate reaches the first temperature, the state is maintained for 3 minutes. At this stage, crystal nuclei are formed in the amorphous semiconductor film (nucleation stage shown in FIG. 15). Thereafter, it is heated to a second temperature for crystallization. The substrate is heated by setting the heating nitrogen gas to 675 ± 25 ° C. (step of temperature increase 2 shown in FIG. 15). When the second temperature is reached, the temperature is maintained for 5 minutes to perform crystallization (crystallization stage shown in FIG. 15). Of course, the nitrogen gas for heating is continuously supplied for the period up to now.
[0103]
When the predetermined time has passed, the supply of the heating nitrogen gas is stopped and the cooling nitrogen gas is supplied. It may be nitrogen gas at room temperature. Then, the substrate is rapidly cooled (temperature lowering stage shown in FIG. 15). This time is about 3 minutes. When the substrate cools to about 300 ° C., the substrate is taken out of the processing chamber by the transfer means, and the substrate is transferred to the buffer cassette. Here, the substrate is further cooled to 150 ° C. or less (transfer stage shown in FIG. 16). Then, the heat treatment for crystallization is completed by transferring the substrate to the cassette.
[0104]
The time from carrying the substrate into the heat treatment apparatus and taking it out after heat treatment is 13 minutes. Thus, by using the heat treatment apparatus and heat treatment method of the present invention, the heat treatment for crystallization can be performed in a very short time.
[0105]
In this manner, a semiconductor film (first semiconductor film) 604 having a crystal structure illustrated in FIG. 6B can be obtained.
[0106]
In order to further increase the crystallization rate (the ratio of the crystal component in the total volume of the film) and repair defects remaining in the crystal grains, a semiconductor film 604 having a crystal structure as shown in FIG. It is also effective to irradiate with laser light. As the laser, excimer laser light having a wavelength of 400 nm or less, and second and third harmonics of a YAG laser are used. In any case, pulse laser light having a repetition frequency of about 10 to 1000 Hz is used, and the laser light is 100 to 400 mJ / cm in the optical system. ² The semiconductor film 604 having a crystal structure with a 90 to 95% overlap rate may be subjected to laser treatment.
[0107]
A catalytic element (nickel here) remains in the semiconductor film (first semiconductor film) 605 having a crystal structure thus obtained. Although it is not uniformly distributed in the film, if it is an average concentration, it is 1 × 10 ¹⁹ /cm ^Three Remaining at a concentration exceeding Of course, various semiconductor elements including TFTs can be formed even in such a state, but the element is removed by gettering by the method described below.
[0108]
First, as shown in FIG. 6D, a thin barrier layer 606 is formed on the surface of a semiconductor film 605 having a crystal structure. Although the thickness of a barrier layer is not specifically limited, You may substitute for the chemical oxide formed simply by processing with ozone water. Similarly, chemical oxide can be formed by treatment with an aqueous solution in which sulfuric acid, hydrochloric acid, nitric acid or the like and hydrogen peroxide are mixed. As another method, the oxidation treatment may be performed by generating ozone by plasma treatment in an oxidizing atmosphere or ultraviolet irradiation in an oxygen-containing atmosphere. Alternatively, a thin oxide film may be formed by heating to about 200 to 350 ° C. using a clean oven to form a barrier layer. Alternatively, a barrier layer may be formed by depositing an oxide film of about 1 to 5 nm by plasma CVD, sputtering, vapor deposition, or the like.
[0109]
A semiconductor film (second semiconductor film) 607 is formed thereon with a thickness of 25 to 250 nm by plasma CVD or sputtering. Typically, an amorphous silicon film is selected. Since this semiconductor film 607 is removed later, it is desirable that the semiconductor film 607 be a film having a low density in order to increase the selection ratio between the semiconductor film 605 having a crystal structure and etching. For example, when an amorphous silicon film is formed by a plasma CVD method, the substrate temperature is set to about 100 to 200 ° C., and 25 to 40 atomic% of hydrogen is contained in the film. The same applies to the case where the sputtering method is employed, and a large amount of hydrogen can be contained in the film by sputtering with a mixed gas of argon and hydrogen at a substrate temperature of 200 ° C. or lower. In addition, when a rare gas element is added during film formation by sputtering or plasma CVD, the rare gas element can be simultaneously incorporated into the film. A gettering site can be formed even with the rare gas element thus taken in.
[0110]
Thereafter, a rare gas element is added to the semiconductor film 607 by 1 × 10 6 by ion doping or ion implantation. ²⁰ ~ 2.5 × 10 ^{twenty two} /cm ^Three To be included at a concentration of Although the acceleration voltage is arbitrary, since it is a rare gas element, ions of the rare gas implanted may pass through the semiconductor film 607 and the barrier layer 606 and partly reach the semiconductor film 605 having a crystal structure. Absent. Since the rare gas element itself is inactive in the semiconductor film, the rare gas element is 1 × 10 10 near the surface of the semiconductor film 605. ¹³ ~ 1x10 ²⁰ /cm ^Three Even if there is a region that is included at a moderate concentration, the device characteristics are not significantly affected. Further, a rare gas element may be added at the stage of forming the semiconductor film 607.
[0111]
As the rare gas element, one or more selected from helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe) are used. In the present invention, in order to form a gettering site, these rare gas elements are used as an ion source and implanted into a semiconductor film by an ion doping method or an ion implantation method. There are two meanings of implanting ions of these rare gas elements. One is to form a dangling bond by implantation to give distortion to the semiconductor film, and the other is to give distortion by implanting the ions between the lattices of the semiconductor film. Implanting inert gas ions can satisfy both of these simultaneously, but the latter is particularly noticeable when using an element with a larger atomic radius than silicon, such as argon (Ar), krypton (Kr), and xenon (Xe). It is done.
[0112]
In order to reliably achieve gettering, it is necessary to perform heat treatment thereafter. FIG. 16 is a graph for explaining the heat treatment process. Hereinafter, the heat treatment process will be described with reference to the graph. Similarly, the heat treatment apparatus of the present invention is used for the heat treatment. In order to efficiently process a large number of substrates, it is desirable to use an apparatus configured as shown in FIG. Nitrogen, argon, or the like can be used as the heating gas.
[0113]
Nitrogen, argon, or the like can be used as the heating gas. The substrate 600 on which the structure of FIG. 6D is formed is set from the cassette into the reaction tube by the transfer means, and then the gate valve is closed. In the meantime, it is considered that nitrogen is continuously supplied from the gas supply means into the reaction tube to minimize the mixing of outside air. After closing the gate valve, the nitrogen flow rate is increased and the reaction tube is filled with nitrogen to replace it.
[0114]
Then, the nitrogen flow rate is increased, and the nitrogen gas supplied by the gas heating means is heated to the third temperature. The heating temperature can be adjusted by the power supplied to the heating element or the supply amount of the power and nitrogen. Here, the third temperature is set to 675 ± 25 ° C., and the substrate is heated (the temperature rising stage shown in FIG. 16). The time required to raise the temperature is 2 minutes.
[0115]
When the substrate reaches the third temperature, the state is maintained for 3 minutes. As a result, gettering is performed (step of gettering shown in FIG. 16). In the gettering, the catalytic element in the gettering region (capture site) is released by thermal energy and moves to the gettering site by diffusion. Accordingly, the gettering depends on the processing temperature, and the gettering proceeds in a shorter time as the temperature is higher. As shown by an arrow in FIG. 6E, the direction in which the catalyst element moves is a distance of about the thickness of the semiconductor film, and gettering is completed in a relatively short time.
[0116]
When the predetermined time has passed, the supply of the heating nitrogen gas is stopped and the cooling nitrogen gas is supplied. It can be nitrogen gas at room temperature. Then, the substrate is rapidly cooled (step of temperature decrease shown in FIG. 16). This time is about 3 minutes. When the substrate cools to about 300 ° C., the substrate is taken out of the processing chamber by the transfer means, and the substrate is transferred to the buffer cassette. Here, the substrate is further cooled to 150 ° C. or lower, and the transfer stage shown in FIG. 16). Then, the heat treatment for gettering is completed by transferring the substrate to the cassette.
[0117]
It takes 9 minutes to carry the substrate into the heat treatment apparatus, heat treat it, and take it out. Thus, by using the heat treatment apparatus and heat treatment method of the present invention, heat treatment for gettering can be performed in a very short time.
[0118]
Even with this heat treatment, 1 × 10 ²⁰ /cm ^Three The semiconductor film 607 containing a rare gas element at the above concentration is not crystallized. This is presumably because the rare gas element remains in the film without being re-emitted even in the above processing temperature range, thereby inhibiting the crystallization of the semiconductor film.
[0119]
Thereafter, the amorphous semiconductor 607 is selectively etched and removed. As an etching method, ClF _Three Dry etching without plasma by hydrazine, tetraethylammonium hydroxide (chemical formula (CH _Three ) _Four NOH) can be easily removed by heating to 50 ° C. using an aqueous solution containing 20-30%, preferably 25%. At this time, the barrier layer 606 becomes an etching stopper and remains almost unetched. The barrier layer 606 may then be removed with hydrofluoric acid.
[0120]
Thus, as shown in FIG. 6F, the concentration of the catalytic element is 1 × 10. ¹⁷ /cm ^Three A semiconductor film 608 having a crystal structure reduced to the following can be obtained. The thus formed semiconductor film 608 having a crystal structure is formed as a thin rod-like or thin flat rod-like crystal by the action of the catalytic element, and each crystal grows in a specific direction when viewed macroscopically. The semiconductor film 608 having such a crystal structure can be applied not only to the active layer of a TFT but also to a photoelectric conversion layer of a photosensor or a solar cell.
[0121]
[Embodiment 6]
A method for manufacturing a TFT using a semiconductor film manufactured according to Embodiment Mode 5 will be described with reference to FIGS. The heat treatment method and heat treatment apparatus of the present invention can also be used in the TFT manufacturing process described in this embodiment mode.
[0122]
First, in FIG. 7A, a semiconductor film 702 that is separated in an island shape from the semiconductor film manufactured in Embodiment 4 over a light-transmitting substrate 700 such as aluminoborosilicate glass or barium borosilicate glass; 703 is formed. Further, between the substrate 700 and the semiconductor film, a first insulating film 701 in which one or a plurality selected from silicon nitride, silicon oxide, and silicon nitride oxide is combined is formed with a thickness of 50 to 200 nm.
[0123]
Thereafter, as shown in FIG. 7B, a second insulating film 704 is formed with a thickness of 80 nm. The second insulating film 704 is used as a gate insulating film and is formed using a plasma CVD method or a sputtering method. As the second insulating film 704, SiH _Four And N ₂ O to O ₂ A silicon oxynitride film formed by adding Si can reduce a fixed charge density in the film and is a preferable material for a gate insulating film. Needless to say, the gate insulating film is not limited to such a silicon oxynitride film, and an insulating film such as a silicon oxide film or a tantalum oxide film may be used as a single layer or a stacked structure.
[0124]
A first conductive film for forming a gate electrode is formed over the second insulating film 704. There is no limitation on the type of the first conductive film, but a conductive material such as aluminum, tantalum, titanium, tungsten, molybdenum, or an alloy thereof can be used. As a structure of the gate electrode using such a material, a stacked structure of tantalum nitride or titanium nitride and tungsten or molybdenum tungsten alloy, a stacked structure of tungsten and aluminum, or copper can be employed. In the case of using aluminum, a material to which 0.1 to 7% by weight of titanium, scandium, neodymium, silicon, copper, or the like is added in order to improve heat resistance is used. The first conductive film is formed with a thickness of 300 nm.
[0125]
Thereafter, a resist pattern is formed, and gate electrodes 705 and 706 are formed. Although not shown, a wiring connected to the gate electrode can be formed at the same time.
[0126]
As shown in FIG. 7C, n-type semiconductor regions 707 and 708 are formed in a self-aligning manner using this gate electrode as a mask. For doping, phosphorus is implanted by an ion implantation method or an ion doping method (herein, a method of implanting ions that are not mass-separated). The phosphorus concentration in this region is 1 × 10 ²⁰ ~ 1x10 ^{twenty one} /cm ^Three To be in the range.
[0127]
Subsequently, as shown in FIG. 7D, a mask 709 covering one semiconductor film 703 is formed, and a p-type semiconductor region 710 is formed in the semiconductor film 702. Boron is used as an impurity to be added, and is added at a concentration 1.5 to 3 times that of phosphorus in order to invert the n-type. The phosphorus concentration in this region is 1.5 × 10 ²⁰ ~ 3x10 ^{twenty one} /cm ^Three To be in the range.
[0128]
Thereafter, as shown in FIG. 7E, a third insulating film 711 made of a silicon oxynitride film or a silicon nitride film is formed to a thickness of 50 nm by plasma CVD.
[0129]
Then, heat treatment is performed to recover and activate the crystallinity of the n-type and p-type semiconductor regions. The heat treatment can be performed by the procedure shown in Embodiment Mode 3 using the heat treatment apparatus having the configuration shown in FIG. In order to efficiently process a large number of substrates, the apparatus shown in FIG. 3 or 4 may be used, or the apparatus having the configuration shown in FIG. 10 or 11 may be used.
[0130]
Nitrogen, argon, or the like can be used as the heating gas. The activation is performed by heating the gas to a temperature of 450 to 700 ° C. and performing a heat treatment for 10 to 3600 seconds. Alternatively, a reducing atmosphere in which hydrogen is added to the gas may be used. Hydrogenation can also be performed simultaneously with the added hydrogen.
[0131]
When heat treatment by the RTA method is performed in a state where the gate electrode is formed on the glass substrate, the gate electrode selectively absorbs the radiation of the lamp light and is locally heated to damage the glass substrate. There is a case. Since the heat treatment according to the present invention is heating by gas, there is no such influence.
[0132]
The fourth insulating film 712 illustrated in FIG. 7F is formed using a silicon oxide film or silicon oxynitride. Alternatively, the surface may be planarized by forming with an organic insulating material such as polyimide or acrylic.
[0133]
Next, a contact hole reaching the impurity region of each semiconductor film from the surface of the fourth insulating film 712 is formed, and wiring is formed using Al, Ti, Ta, or the like. In FIG. 7F, reference numerals 713 and 714 denote source lines or drain electrodes. Thus, an n-channel TFT and a p-channel TFT can be formed. Although each TFT is shown here as a single unit, a CMOS circuit, NMOS circuit, or PMOS circuit can be formed using these TFTs.
[0134]
[Embodiment 7]
In the heat treatment method of the present invention and the heat treatment apparatus to which the heat treatment method is applied, an inert gas and a kind selected from oxygen, nitrous oxide, and nitrogen dioxide are mixed into the gas to be heated to obtain an oxidizing gas. An oxide film can be formed on the surface.
[0135]
FIG. 9 shows an example. A field oxide film for element isolation or gate insulation is formed on a single crystal silicon substrate by mixing 1 to 30% of oxygen with nitrogen as a heating gas and performing a heat treatment at 850 to 1000 ° C. A film can be formed.
[0136]
In FIG. 9A, an n well 802 and a p well 803 are formed on a substrate 801 made of single crystal silicon having a relatively high resistance (for example, n-type, about 10 Ωcm). Thereafter, the field oxide film 805 is formed by using the heat treatment method of the present invention using a mixed gas of oxygen and nitrogen as a heating gas. At this time, boron (B) may be selectively introduced into the semiconductor substrate by an ion implantation method to form a channel stopper. The heating temperature is 800 to 1000 ° C.
[0137]
Similarly, a silicon oxide film 806 to be a gate insulating film is formed. As the apparatus used for forming the field oxide film 805 and the silicon oxide film 806, any of the apparatuses having the structure shown in FIG. 1, FIG. 3, or FIG. 4 may be used.
[0138]
Subsequently, as shown in FIG. 9B, a polycrystalline silicon film for gate is formed with a thickness of 100 to 300 nm by a CVD method. The polycrystalline silicon film for the gate is preliminarily formed in order to reduce the resistance. ^{twenty one} /cm ^Three Phosphorus (P) may be doped at a moderate concentration, or a dense n-type impurity may be diffused after the polycrystalline silicon film is formed. Here, in order to further reduce the resistance, a silicide film is formed with a thickness of 50 to 300 nm on the polycrystalline silicon film. As the silicide material, molybdenum silicide (MoSix), tungsten silicide (WSix), tantalum silicide (TaSix), titanium silicide (TiSix), or the like can be used. The silicide material may be formed according to a known method. Then, the polycrystalline silicon film and the silicide film are etched to form gates 807 and 808. The gates 807 and 808 have a two-layer structure of polycrystalline silicon films 807a and 808a and silicide films 807b and 808b.
[0139]
Thereafter, as shown in FIG. 9C, sidewalls 816 and 817 are formed, and source and drain regions 820 of the n-channel MOS transistor and source and drain regions 824 of the p-channel MOS transistor are formed by ion implantation. To do. Of course, the heat treatment method and heat treatment apparatus of the present invention can also be applied to heat treatment for recrystallization and activation of these source and drain regions. The heating nitrogen gas is heated by a heating means so that the heating temperature is 700 to 1000 ° C., preferably 950 ° C. By this heat treatment, the impurities are activated and the resistance of the source and drain regions is reduced.
[0140]
In this way, the n-channel MOS transistor 331 and the p-channel MOS transistor 330 are completed. The transistor structure described in this embodiment mode is just an embodiment mode, and the present invention is not necessarily limited to the manufacturing process and structure shown in FIGS. A CMOS circuit, an NMOS circuit, or a PMOS circuit can be formed using these transistors. Various circuits such as a shift register, a buffer, sampling, a D / A converter, and a latch can be formed, and a semiconductor device such as a memory, a CPU, a gate array, and a RISC can be manufactured. Such a circuit can be operated at high speed by being composed of MOS, and can reduce power consumption by setting the drive voltage to 3 to 5V.
[0141]
【The invention's effect】
As described above, according to the present invention, the heat treatment of the substrate to be processed is not restricted by the shape or size of the substrate to be processed, and a robust susceptor is not required even if the substrate to be processed is enlarged. Therefore, the size can be reduced accordingly. The heat treatment method of the present invention and the heat treatment apparatus to which the heat treatment method is applied are a batch processing method, and a method of heating a substrate to be processed by a heated gas. Therefore, even if the substrate size is increased, heat treatment can be performed with good uniformity. It can also be applied to heat treatment of a substrate having a side length exceeding 1000 mm. For this purpose, a large-scale heating means is not required, and a heat treatment apparatus with reduced power can be realized.
[0142]
As the heat treatment for the substrate to be processed, crystallization of an amorphous semiconductor film, gettering, activation of impurities, hydrogenation, oxidation of a semiconductor surface, and the like can be performed. By incorporating such a process into the manufacturing process of the semiconductor element, an integrated circuit can be formed over a large area substrate.
[Brief description of the drawings]
FIG. 1 is a cross-sectional structure diagram showing an embodiment of a heat treatment apparatus to which a heat treatment method of the present invention is applied.
FIG. 2 is a top structural view showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 3 is a cross-sectional structure diagram showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 4 is a cross-sectional structure diagram showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 5 is a cross-sectional structure diagram showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
6 is a cross-sectional view illustrating a process for manufacturing a semiconductor film, to which a heat treatment method and a heat treatment apparatus of the present invention are applied. FIG.
7 is a cross-sectional view illustrating a manufacturing process of a TFT to which a heat treatment method and a heat treatment apparatus of the present invention are applied. FIG.
FIG. 8 is a conceptual diagram illustrating a heat treatment method of the present invention.
FIG. 9 is a cross-sectional view illustrating a semiconductor substrate heat treatment step to which the heat treatment method and the heat treatment apparatus of the present invention are applied.
FIG. 10 is a sectional structural view showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 11 is a cross-sectional structure diagram showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 12 is a diagram for explaining an example of a gas heating unit applicable to the heat treatment apparatus of the present invention.
FIG. 13 is a diagram for explaining an example of a heat exchanger applicable to the heat treatment apparatus of the present invention.
FIG. 14 is a layout diagram showing an embodiment of a heat treatment apparatus to which the heat treatment method of the present invention is applied.
FIG. 15 is a graph for explaining a change in substrate temperature in a crystallization process using the heat treatment method of the present invention.
FIG. 16 is a graph illustrating a change in substrate temperature in a gettering process using the heat treatment method of the present invention.
[Explanation of symbols]
101 first processing chamber, 102 second processing chamber, 103 third processing chamber, 104 fourth processing chamber, 105 fifth processing chamber,
106 first gas supply means, 107 second gas supply means, 108 first gas heating means, 109 second gas heating means, 110 third gas heating means, 111 fourth gas heating means, 112 5 gas heating means,
113 heat exchanger, 114 abatement means, 115 substrate holding means, 116 shower plate
1101 Reaction tube, 1105 Heating means, 1106, 1107 Orifice plate, 1109 Gas supply means, 1110 Cooling gas supply means, 1112 Intake part, 1113 Exhaust part, 1114 Connecting pipe, 1116 Heater, 1121 Conveying means

Claims (7)

A heat treatment apparatus comprising a heating means for heating a gas and heating a substrate to be processed using the gas heated by the heating means as a heat source,
A first gas supply means Ru Connecting to an inlet side of the first heating means via a heat exchanger,
A first processing chamber connected to the discharge port side of the first heating means;
A second heating means connected to the discharge port side of the first processing chamber;
A heat treatment apparatus comprising a second treatment chamber connected to the discharge port side of the second heating means. A heat treatment apparatus comprising a heating means for heating a gas and heating a substrate to be processed using the gas heated by the heating means as a heat source,
A first gas supply means Ru Connecting to an inlet side of the first heating means via a heat exchanger,
A first processing chamber connected to the discharge port side of the first heating means;
A second heating means connected to the discharge port side of the first processing chamber;
A second processing chamber connected to the outlet side of the second heating means;
Heat treatment apparatus is characterized in that a second gas supply means for supplying a cooling gas their Re to, respectively of the first processing chamber and said second processing chamber. In claim 1 or claim 2,
The heat exchanger includes first and second pipes provided with fins, respectively.
A heat treatment apparatus, wherein a first gas is introduced into the first pipe, and a second gas having a temperature lower than that of the first gas is introduced into the second pipe. In any one of Claim 1 thru | or 3,
The first heating means includes a cylinder, a light source provided outside the cylinder, and a heat absorber provided inside the cylinder. A heat treatment method for heating a substrate disposed in a processing chamber using a gas heated by a heating means as a heat source,
Supplying gas from the gas supply means to the first heating means via the heat exchanger;
The gas is heated by the first heating means,
Supplying the heated gas to the first processing chamber;
Heating the gas discharged from the first processing chamber by a second heating means;
Supplying the heated gas to a second processing chamber;
A heat treatment method comprising supplying the exhausted gas discharged from the second processing chamber to the heat exchanger. In claim 5,
The heat exchanger includes first and second pipes provided with fins, respectively.
The first gas is introduced into the first pipe, and the second gas is introduced into the second pipe, thereby cooling the first gas and heating the second gas. A heat treatment method. In claim 5 or claim 6,
The first heating means includes a cylinder, a light source provided on the outside of the cylinder, and an endothermic body provided on the inside of the cylinder,
A heat treatment method, wherein the heat absorber absorbs radiant heat from the light source and heats a gas introduced into the cylinder.

Images