JP3612018B2 - Method for manufacturing semiconductor device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for manufacturing a semiconductor device (such as various transistors and integrated circuits) and an apparatus therefor.
[0002]
[Prior art]
In recent years, semiconductor element manufacturing methods and apparatuses using lasers have been developed. For example, a laser etching (laser scribing) method that etches and patterns a film by irradiating laser light, a laser annealing method that changes the crystalline state of the film or surface by irradiating laser light, impurities A laser doping method or the like in which the impurities are diffused in the coating film or the surface by irradiating with a laser beam in an atmosphere containing.
[0003]
[Problems to be solved by the invention]
However, in such a semiconductor manufacturing method using a laser, conventionally, a substrate processed by another film forming apparatus or an etching apparatus is set in the laser processing apparatus, and after evacuation or substrate heating, the laser processing is performed. As a result, the productivity was remarkably low. The present invention aims to improve such low productivity.
[0004]
[How to solve the problem]
The configuration of the present invention is as follows. First, film forming equipment (plasma CVD equipment, sputtering equipment, thermal CVD equipment, vacuum deposition equipment, etc.), etching equipment, doping equipment (plasma doping equipment, ion implantation equipment, etc.), heat treatment equipment (thermal diffusion equipment, thermal crystallization) Equipment), vacuum chambers such as spare chambers, and laser processing equipment (laser etching equipment, laser annealing equipment, laser doping equipment, etc.) are combined into a multi-chamber system, and the substrate is once in the atmosphere. It performs the necessary processing without exposing to Such a system is characterized not only in that the time for evacuation is significantly shortened, but also that the substrate can be protected from undesired contamination associated with the transport of the substrate.
[0005]
Further, there is a method of performing various annealings by irradiating infrared light instead of irradiating laser light. For example, after crystallizing an amorphous silicon film formed over a glass substrate by heating, the crystallinity can be further increased by performing irradiation with infrared light. Infrared light is more easily absorbed by the silicon thin film than the glass substrate, and is useful because it can selectively heat only the silicon thin film without heating the glass substrate much. The effect is considered to be comparable to that obtained by thermal annealing at 1000 ° C. or higher.
[0006]
This annealing by irradiation with infrared light can be completed within a few minutes, so it is called rapid thermal annealing (RTA). It is also effective to perform this annealing after forming an insulating film on the semiconductor. In this case, the level at the interface between the semiconductor and the insulating film can be reduced, and the interface characteristics can be improved. For example, after forming an active layer (a channel forming region is formed) of an insulated gate field effect semiconductor device, a silicon oxide film to be a gate insulating film is formed, and then RTA is performed, whereby an insulated gate field effect is obtained. It is possible to improve the interface characteristics at and near the interface between the channel and the gate insulating film, which is an important element in the semiconductor device. The following examples illustrate the various examples of the present invention.
[0007]
【Example】
[Example 1]
FIG. 1 shows an example of the present invention. In this example, a plasma CVD film forming apparatus and a laser processing apparatus (for example, a laser annealing apparatus) are combined, and one spare chamber is provided between the two apparatuses.
[0008]
In the figure, 1 is a chamber of a plasma CVD apparatus, and 2 is a chamber of a laser annealing apparatus. These chambers are provided with gas introduction valves 7 and 18 and exhaust valves 8 and 19 so that necessary gases can be introduced and exhausted, and the internal pressure can be kept at an appropriate value.
[0009]
The chamber 1 is further provided with electrodes 4 and 5, a substrate (sample) 6 to be processed is placed on the electrode 5, and an RF power source (for example, frequency 13.56 MHz) 3 is connected to the electrode 4. ing. Then, an appropriate gas (for example, monosilane or disilane) is introduced into the chamber, and a discharge is generated between the electrodes to form a film on the substrate 6. The substrate may be heated as necessary. When monosilane is used as the gas and the substrate is set to 300 ° C. or lower, an amorphous silicon film is formed on the substrate.
[0010]
Since such amorphous silicon does not have excellent electrical characteristics, the characteristics can be improved by crystallization by laser annealing. A window 14 is provided in the chamber 2, and laser light from the laser device 11 via the mirror 12 and the lens 13 is irradiated to the substrate 17 on the sample holder 15 through the window. The substrate is heated by the heater 16 to 300 to 500 ° C., preferably 300 to 400 ° C. This heating is indispensable when performing crystallization with good reproducibility.
[0011]
The sample holder is movable and can be moved gradually to the right side of the figure with the substrate on it. As a result, laser treatment can be performed on the entire surface of the substrate. For example, if the substrate is 300 mm × 400 mm, the entire surface of the substrate can be laser-treated by making the shape of the laser beam 2 × 350 mm linear. If the moving speed of the holder at this time is 20 mm / second, the processing time for one substrate is 400 ÷ 20 = 20 seconds.
[0012]
The substrate on which the amorphous silicon film is formed by the plasma CVD apparatus 1 is transferred to the laser processing apparatus 2 in the following order. First, after the film formation is completed, the inside of the film formation apparatus 1 is evacuated to a sufficient vacuum state. On the other hand, the preliminary chamber 9 is also evacuated to a sufficient vacuum state. Then, the gate between the film forming apparatus 1 and the spare chamber is opened, and the substrate is transferred to the spare chamber. After the transfer, the gate is closed, the reaction gas is again introduced into the film forming apparatus, and film formation is started.
[0013]
On the other hand, the inside of the laser processing apparatus 2 is now in a sufficiently vacuum state. The preliminary chamber 9 is already in a sufficiently vacuum state. Then, the gate between the preliminary chamber and the laser processing apparatus is opened, and the substrate is transferred from the preliminary chamber to the laser processing apparatus. After the transfer, the gate is closed and the sample holder 15 is heated to an appropriate temperature by the heater 16. When the temperature is stable and precise alignment of the substrate set in the laser processing apparatus is completed, laser processing is performed.
[0014]
At this time, for example, if the processing time in the laser device for one substrate including from the substrate setting to alignment and removal is substantially equal to the film formation time in the plasma CVD device including the substrate setting and exhaust. From the plasma CVD apparatus to the laser processing apparatus, processing can be performed without waiting time. If the processing time of the laser of one substrate is half of the film formation time in plasma CVD, two films may be formed in plasma CVD at a time. In this case, after the film formation is completed, two substrates are taken out to the spare chamber, one of which is sent to the laser processing apparatus and processed, and the other one is stored in the spare chamber. Then, after the first sheet is processed, one sheet stored in the spare room is processed.
[0015]
[Example 2]
FIG. 2 shows an example of the present invention. In this example, a plasma doping apparatus and a laser processing apparatus (for example, a laser annealing apparatus) are combined, and one spare chamber is provided between the two apparatuses.
[0016]
In the figure, 21 is a chamber of a plasma doping apparatus, and 22 is a chamber of a laser annealing apparatus. In these chambers, necessary gas can be introduced and exhausted, and the internal pressure can be maintained at an appropriate value.
[0017]
The chamber 21 is further provided with an anode electrode 24 and a grid electrode 25, and a high voltage of 100 kV at maximum is applied to the anode by a high voltage power source 23. The positive ions 26 in the plasma generated by RF discharge or the like in the vicinity of the grid electrode are accelerated in the direction of the sample holder 28 by the high voltage described above. As a result, accelerated cations are implanted into the substrate (sample) 27 on the sample holder 28.
[0018]
In such ion implantation, the crystalline material (for example, single crystal silicon or crystalline silicon) that has been formed on the substrate until then becomes amorphous or close to the characteristics, and the electrical characteristics are deteriorated. The characteristics are improved by crystallization by annealing. A window 34 is provided in the chamber 22, and laser light passing through the mirror 32 and the lens 33 from the laser device 31 is irradiated to the substrate 35 on the sample holder 36 through the window. The substrate may be heated by the heater 37.
[0019]
The sample holder is movable and can be moved gradually to the right side of the figure with the substrate on it. As a result, laser treatment can be performed on the entire surface of the substrate. The substrate doped with the plasma doping apparatus 21 is transferred to the laser processing apparatus 22 via the preliminary chamber 29 as in the first embodiment.
[0020]
In this embodiment, a doping apparatus using ion implantation using a plasma source is used. However, it goes without saying that an ion implantation apparatus that implants ions by separating the mass of ions may be used.
[0021]
Example 3
FIG. 3 shows an example of the present invention. In this example, a plasma doping apparatus, a dry etching apparatus, and a laser processing apparatus (for example, a laser annealing apparatus) are combined, and one spare chamber is provided between the three apparatuses.
[0022]
In the figure, 41 is a chamber of a plasma doping apparatus, 42 is an etching apparatus, and 43 is a chamber of a laser annealing apparatus. In these chambers, necessary gas can be introduced and exhausted, and the internal pressure can be maintained at an appropriate value.
[0023]
The chamber 41 is further provided with an anode electrode 45 and a grid electrode 46, and a high voltage of 100 kV at maximum is applied to the anode by a high voltage power supply 44. The positive ions 47 in the plasma generated by RF discharge or the like in the vicinity of the grid electrode are accelerated in the direction of the sample holder 49 by the high voltage described above. As a result, accelerated cations (such as boron ions and phosphorus ions) are implanted into the substrate (sample) 48 on the sample holder 49.
[0024]
For example, in the substrate 48, crystalline silicon and a silicon oxide layer thereon are formed on an insulating substrate, and a gate electrode of a thin film transistor is further formed. Then, necessary impurities are implanted into the silicon oxide layer and the silicon layer by doping. In this way, doping through a material such as silicon oxide is referred to as through doping, which is a suitable method for forming a semiconductor element with a high yield.
[0025]
As described in Example 2, the crystallinity deteriorates as a result of such ion implantation, so that crystallinity is improved by a method such as laser annealing, but impurities are also implanted into silicon oxide. ing. For example, a problem arises when an ultraviolet excimer laser excellent in mass productivity, for example, a KrF laser (wavelength 248 nm), a XeCl laser (308 nm), or a XeF laser (350 nm) is used as a laser used for laser annealing. That is, pure silicon oxide is transparent to ultraviolet light of 200 nm or more, but silicon oxide containing impurities exhibits considerable absorption.
[0026]
As a result, a large part of the laser energy is absorbed by the silicon oxide film, which causes a problem that it cannot be used efficiently for improving crystallinity. In order to solve this problem, the silicon oxide film must be etched so that the laser light is efficiently absorbed by the coating whose crystallinity is to be improved. The etching apparatus 42 is provided for this purpose.
[0027]
The etching apparatus 42 is provided with electrodes 53 and 54, an RF power source 52 is connected to the electrode 53, and a substrate 55 is placed on the electrode 54. For example, the silicon oxide film on the substrate can be etched when a discharge is generated between the electrodes by power from an RF power source in a carbon tetrafluoride atmosphere.
[0028]
The laser processing apparatus 43 is substantially the same as that shown in the first and second embodiments, and a window 61 is provided in the chamber 43, and laser light passes through the mirror 59 and the lens 60 from the laser apparatus 58, and laser light passes through the window 61. Then, the substrate 62 on the movable sample holder 64 is irradiated. The substrate may be heated by the heater 63.
[0029]
The substrate doped by the plasma doping apparatus 41 is transferred to the etching apparatus 42 via the preliminary chamber 50 as in the first embodiment. After the etching process is completed, the substrate is transferred to the laser processing apparatus 43 via the preliminary chamber 56. Be transported.
[0030]
An example of manufacturing a thin film transistor (TFT) using such a multi-chamber system is shown in FIG. A base silicon oxide film 102 having a thickness of 20 to 200 nm is formed on a glass substrate (eg, Corning 7059) 101 by a sputtering method or a plasma CVD method. Further, an amorphous silicon film is deposited to a thickness of 100 to 200 nm by a method such as LPCVD, plasma CVD, or sputtering, and crystallized by heating in nitrogen at 550 to 650 ° C. for 4 to 48 hours or in vacuum. .
[0031]
Then, the crystallized silicon film is patterned to form active layer regions 103 and 104. Then, a silicon oxide film 105 having a thickness of 50 to 150 nm functioning as a gate oxide film is formed, and further, a gate electrode 106 is formed of a material such as aluminum, tantalum, chromium, tungsten, molybdenum, silicon, an alloy thereof or a multilayer wiring. 107 is formed. (Fig. 5 (A))
[0032]
Thereafter, a mask material 108 such as a resist is formed only in the active layer region 103, and boron doping is performed by the plasma doping apparatus 41 of FIG. The acceleration voltage of the spine was 20 to 65 keV, typically 65 keV, and the dose amount was 6 × 10 ¹⁵ cm ⁻² . A P-type region 109 is formed by this doping process. (Fig. 5 (B))
[0033]
After the doping is completed, the substrate is transferred to the etching apparatus 42, and the mask material 108 is removed by discharge in an oxygen atmosphere. Usually, it is more efficient to remove a mask material such as a resist with a remover. However, in consideration of taking in and out of a vacuum apparatus, it is more efficient to perform ashing with an etching apparatus in a multi-chamber system as shown in FIG. And processing capacity is high.
[0034]
Next, the substrate is returned to the doping apparatus 41 again, and this time, phosphorus is doped. The acceleration voltage of phosphorus was 20 to 85 keV, typically 80 keV, and the dose amount was 4 × 10 ¹⁵ cm ⁻² . By this doping process, an N-type region 110 was formed. (Fig. 5 (C))
[0035]
Next, the substrate was sent again to the etching apparatus 42, where the silicon oxide film 105 was etched. As described above, this silicon oxide film contains a large amount of phosphorus and boron, so that the laser light is absorbed so much that laser annealing cannot be performed efficiently. (Fig. 5 (D))
[0036]
After the silicon oxide film 105 is etched, the substrate is sent to the laser processing apparatus 43 where laser annealing is performed. As the laser, a KrF laser (pulse width 20 nsec, repetition frequency 200 Hz) was used. However, it will be apparent that other lasers may be used. The energy density per pulse of the laser is 200 to 400 mJ / cm ² , preferably 250 to 300 mJ / cm ² , but this is changed depending on other conditions (for example, the dose amount and the thickness of the silicon film). (Fig. 5 (E))
[0037]
After the laser annealing, the substrate was taken out to form an interlayer insulating film 111 and metal wiring / electrodes 112. Of course, a film forming chamber may be added to the multi-chamber system of FIG. 3 to form an interlayer insulating film continuously. Through the above steps, N-channel and P-channel TFTs were completed.
[0038]
Although FIG. 3 shows a state in which the vacuum devices are arranged in series, for example, as shown in FIG. 4, they may be arranged in parallel. In FIG. 4, a chamber 71 for entering and exiting the substrate, a laser processing device 73, a plasma doping device 75, and an etching device 77 are connected to a common spare chamber 79 through respective gates 72, 74, 76, and 78. The state of being done is shown.
[0039]
Then, the substrates 81 to 84 are transferred to a spare room or another chamber by the magic hand 80. In such a system, it is possible to expand the system as necessary, and flexibility during mass production (addition of film formation / etching process, flexibility to change tact as the film formation time is extended, etc.) Property).
[0040]
Example 4
In this embodiment, as shown in FIG. 6, a chamber 41 of a plasma doping apparatus, a chamber 42 of an etching apparatus, and a chamber 601 for performing annealing by rapid thermal annealing (RTA) using infrared light are constituted by a spare room 50 and 56. It has a connected configuration. 3 have the same configuration as that described in FIG.
[0041]
A chamber 601 that performs RTA is provided with a light source (lamp) 602 that irradiates infrared light, a chamber 603 that constitutes a light source room, and a quartz window 606 that transmits infrared light. Although not shown in the figure, a gas introduction system and a gas exhaust system for introducing an inert gas or a necessary gas are provided.
[0042]
The substrate 604 is placed on the substrate holder 605 and is transferred to each chamber by a magic hand (substrate transport robot). This transfer method may be a method of transferring only the substrate or a method of moving the entire substrate holder.
[0043]
The atmosphere in which RTA is performed is normally performed in an inert atmosphere such as nitrogen, but may be performed in an ammonia (NH ₃ ) atmosphere, nitrous oxide (N ₂ O), or an oxygen atmosphere.
[0044]
An example using the apparatus shown in FIG. 6 is shown below. First, consider the case of manufacturing only the right TFT in the TFT manufacturing process shown in FIG. In this case, first, after a silicon oxide film is formed on the active layer 104, the substrate is carried into a chamber 601 where RTA is performed. Then, the chamber 601 is filled with an inert gas, and infrared light is irradiated from the lamp 602. By this step, the interface characteristics between the active layer 103 and the silicon oxide film 105 are improved. Specifically, the interface state at the interface between the channel formation region and the gate insulating film can be reduced.
[0045]
Then, the chamber 601 is set in a reduced pressure state, and the substrate is transferred to the preliminary chamber 56 that is also held in the same reduced pressure state. In the same manner, the substrate is carried into the chamber 41 where plasma doping is performed via the chamber 42 and the preliminary chamber 50 held in a reduced pressure state. It is important that these substrate transport steps be performed without exposure to the outside air.
[0046]
Then, the necessary ion implantation process is performed in the chamber of the doping apparatus. Further, in a state where the degree of vacuum is maintained, the substrate is transferred to the chamber 42 of the etching apparatus and dry etching is performed to remove the exposed oxide film 105. Further, the implanted impurities can be activated by carrying the substrate into the chamber 601 where RTA is performed and performing RTA. At this time, the absence of the oxide film 105 is important for effective RTA. That is, the silicon oxide film 105 contains impurities implanted at the time of ion implantation, and this impurity component absorbs infrared rays.
[0047]
In addition to the configuration of the apparatus described above, a chamber for irradiating laser light and a chamber for performing RTA may be combined. It is also possible to combine a plurality of required chambers.
[0048]
【The invention's effect】
In the present invention, a laser processing apparatus or an apparatus that irradiates intense light and a vacuum apparatus (a film forming apparatus or an etching apparatus) related thereto are combined into a system, and mass productivity is improved by efficiently using the system. It was shown that. Thus, the present invention is an industrially useful invention.
[Brief description of the drawings]
FIG. 1 shows a conceptual diagram of a multi-chamber of the present invention.
FIG. 2 shows a conceptual diagram of the multi-chamber of the present invention.
FIG. 3 shows a conceptual diagram of the multi-chamber of the present invention.
FIG. 4 shows a conceptual diagram of the multi-chamber of the present invention.
FIG. 5 shows an embodiment of the present invention.
FIG. 6 shows a conceptual diagram of the multi-chamber of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Film-forming chamber 2 ... Laser processing chamber 3 ... RF power supply 4, 5 ... Electrode 6 ... (During film-forming) Substrate 7 ... Vacuum valve (gas introduction side)
8 ... Vacuum valve (exhaust side)
9: Preliminary chamber 10: Substrate 11 (after film formation) ... Laser apparatus 12 ... Mirror 13 ... Lens 14 ... Window 15 ... Substrate holder (movable)
16 ... Heater 17 ... Substrate 18 (during laser processing) ... Vacuum valve (gas introduction side)
19 ・ ・ ・ Vacuum valve (exhaust side)
21 ... Doping device chamber 22 ... Laser processing chamber 23 ... High voltage power supply 24 ... Anode electrode 25 ... Grid electrode 26 ... Ion flow 27 ... Doping substrate 28 .... Sample holder 29 ... Preliminary chamber 30 ... (Doping) substrate 31 ... Laser device 32 ... Mirror 33 ... Lens 34 ... Window 35 ... (During laser processing) ) Substrate 36 ... Substrate holder (movable)
37 ・ ・ ・ Heater

Claims (4)

Forming first and second active layers made of a crystalline silicon film on a glass substrate;
Forming a gate insulating film on the first and second active layers;
Forming a first gate electrode on the first active layer via the gate insulating film, and forming a second gate electrode on the second active layer via the gate insulating film;
Forming a mask material on the first gate electrode so as to cover the first active layer;
Using a semiconductor processing apparatus having a first chamber for doping, a second chamber for dry etching, and a third chamber for irradiating laser light,
Doping the second active layer with boron in the first chamber;
Moving the glass substrate from the first chamber to the second chamber without exposing the glass substrate to outside air;
Removing the mask material in the second chamber;
Moving the glass substrate from the second chamber to the first chamber without exposing the glass substrate to outside air;
Doping the first and second active layers with phosphorus in the first chamber;
Moving the glass substrate from the first chamber to the second chamber without exposing the glass substrate to outside air;
Etching the gate insulating film implanted with boron or phosphorus during the doping by causing a discharge in the second chamber;
Moving the glass substrate from the second chamber to the third chamber without exposing the glass substrate to outside air;
A method of manufacturing a semiconductor device, wherein the first chamber and the second active layer are irradiated with laser light in the third chamber.   A silicon oxide film is formed on a glass substrate,
  Forming first and second active layers made of a crystalline silicon film on the silicon oxide film;
  Forming a gate insulating film on the first and second active layers;
  Forming a first gate electrode on the first active layer via the gate insulating film, and forming a second gate electrode on the second active layer via the gate insulating film;
  Forming a mask material on the first gate electrode so as to cover the first active layer;
  Using a semiconductor processing apparatus having a first chamber for doping, a second chamber for dry etching, and a third chamber for irradiating laser light,
  Doping the second active layer with boron in the first chamber;
  Moving the glass substrate from the first chamber to the second chamber without exposing the glass substrate to outside air;
  Removing the mask material in the second chamber;
  Moving the glass substrate from the second chamber to the first chamber without exposing the glass substrate to outside air;
  Doping the first and second active layers with phosphorus in the first chamber;
  Moving the glass substrate from the first chamber to the second chamber without exposing the glass substrate to outside air;
  Etching the gate insulating film implanted with boron or phosphorus during the doping by causing a discharge in the second chamber;
  Moving the glass substrate from the second chamber to the third chamber without exposing the glass substrate to outside air;
  A method of manufacturing a semiconductor device, wherein the first chamber and the second active layer are irradiated with laser light in the third chamber. 3. The method for manufacturing a semiconductor device according to claim 1 , wherein the laser beam is an excimer laser beam. In any one of claims 1 to 3, in the laser light irradiation in said third chamber, the glass substrate is put on the sample holder of the movable, linear laser beam, characterized in that it is illuminated A method for manufacturing a semiconductor device.

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