JP4583533B2 - Method for forming metal wiring - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of dry-etching a metal film into a predetermined shape in the presence of a gas containing Cl (chlorine) in the same processing chamber, and further preventing corrosion of the formed metal wiring. Further, the present invention relates to a semiconductor device manufactured by including a method for preventing dry etching of a metal film and corrosion of metal wiring in the same processing chamber, and a manufacturing method thereof. Note that the semiconductor device here includes an electro-optical device such as a liquid crystal display device and an EL display device, and an electronic device including the electro-optical device as a component.
[0002]
[Prior art]
In a conventional process for forming a metal wiring of a semiconductor device, first, a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, and a resin film are formed as a base film for the metal wiring, and a wiring material film is formed thereon by sputtering. Al (aluminum) film, Al-Si (silicon), Al-Cu (copper), Al-Si-Cu, Al-Nd (neodymium), Al-Ti (titanium), Al-Mo (molybdenum) and Al-Sc An Al alloy film such as (scandium) or a laminated film of an Al alloy film and a Ti film, a TiN (titanium nitride) film, a W (tungsten) film, and a WN (tungsten nitride) film is formed. Next, a photoresist is formed into a predetermined shape using a photomask. Then, using the photoresist as a mask, Cl ₂ , SiCl _Four , BCl _Three And CCl _Four The metal wiring is formed by dry etching using various chlorine-containing gases.
[0003]
If left in the atmosphere after etching, the resist and wiring surfaces have Cl ₂ (Chlorine) and chlorine-based compounds remain, and these substances and H in the atmosphere ₂ O reacts to produce hydrochloric acid, which causes wiring corrosion. The corrosion of the wiring not only lowers the yield of the semiconductor device but also reduces the reliability of the wiring and shortens the life. Note that the chlorine-based compound is a compound containing Al and Cl generated by etching, and is typically AlCl. _Three And Al ₂ Cl ₆ Is mentioned. Further, the compound to be generated varies depending on the etching conditions.
[0004]
As a solution of this method, after etching, before being released to the atmosphere, it is transported to a rinsing chamber in a nitrogen gas atmosphere and washed with pure water or a chemical solution to remove chlorine and chlorine-based compounds. ₆ And CF _Four A method of substituting chlorine adhering to the surface of the resist and wiring with fluorine by exposing to a plasma of a gas containing fluorine such as H; ₂ There is a method of removing chlorine adhering to the surface together with a photoresist by plasma of O gas.
[0005]
[Problems to be solved by the invention]
However, the method of removing chlorine by cleaning with pure water, chemical solution, or the like is not desirable because the cleaning apparatus needs to be incorporated in the etching apparatus, and the configuration of the apparatus becomes complicated and the cost increases. In addition, as the patterns become finer, it may be difficult to sufficiently penetrate pure water, a chemical solution, or the like between the patterns, and the effect may not be obtained.
[0006]
On the other hand, in the method of replacing Cl (chlorine) with F (fluorine) by plasma of a gas containing fluorine, a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, and a resin film, which are base films for metal wiring, are etched. End up. And H ₂ In the method of removing chlorine by plasma of O gas, when the base film is a resin film, the base film is largely etched. Although these methods can be performed in the same processing chamber, since plasma is used, damage due to charge-up is also a problem.
[0007]
[Means for Solving the Problems]
The method of the present invention for solving the above-described problems is a process of forming a metal film as a wiring material, a process of forming a photoresist on the metal film, and a gas containing chlorine in the metal film. Etching in the reaction chamber and H in the reaction chamber. ₂ And a step of introducing O gas.
[0008]
In addition, H in the reaction chamber ₂ A step of performing plasma treatment with an inert gas in the reaction chamber is provided after the step of introducing the O gas.
[0009]
The metal film is typified by a film mainly containing Al (referred to as an Al alloy film), for example, Al-Si, Al-Cu, Al-Si-Cu, Al-Nd, Al-Ti, Al-Mo, and Al-Sc. A single layer film made of an Al alloy film, or a film mainly containing an Al alloy film and a metal other than Al, such as Ta (tantalum), Ti (titanium), Mo (molybdenum), and W (tungsten) It is a film mainly containing an element selected from the above, an alloy film in which the elements are combined, or a laminated film with a nitride film of the elements.
[0010]
The temperature in the reaction chamber in each of the above steps is maintained in the range of 70 ° C to 200 ° C, preferably 70 ° C to 100 ° C.
[0011]
In particular, H ₂ The pressure in the reaction chamber when introducing the O gas is a chlorine-based compound remaining on the surface of the photoresist and the metal wiring after the metal film is dry-etched using a gas containing chlorine in the reaction chamber. This is a method for manufacturing a semiconductor device, characterized by being lower than the saturated vapor pressure.
[0012]
The inert gas is one or a plurality selected from Ar (argon), Kr (krypton), or Xe (xenon).
[0013]
In the method of the present invention, H in the reaction chamber ₂ Chlorine is removed by introducing O gas with low pressure and heating. This H ₂ The effect of removing Cl (chlorine) by O gas is ₂ Gas and O ₂ For gases, the temperature and pressure are set to H ₂ It is clear from the fact that it was introduced under the same conditions as O gas and it was confirmed that the effect of preventing corrosion of metal wiring could not be obtained.
[0014]
A mechanism for preventing corrosion of the metal wiring according to the present invention will be described with reference to FIG. As shown in FIG. 1A, a film to be a base film 102 is formed on a substrate 101, a metal film 103 to be a wiring material is formed thereon, and a photoresist 104 is further formed thereon. . After that, when the metal film is dry-etched using a gas containing chlorine, the surface of the photoresist and the formed metal wiring 105 is formed with Cl. ₂ (Chlorine) 106 and AlCl _Three A chlorine-based compound 107 such as the residue remains (FIG. 1B).
[0015]
After etching, H ₂ When O gas 108 is introduced into the reaction chamber, Cl ₂ And AlCl _Three It reacts with a chlorine-based compound such as HCl (hydrogen chloride) gas 109. At this time, the lower the pressure in the reaction chamber, the higher the temperature, the more H present in the reaction chamber. ₂ O, Cl ₂ And AlCl _Three The degree of freedom of chlorine compounds such as ₂ The reaction between O and the chlorine-based compound is promoted.
[0016]
The generated HCl gas is Cl ₂ And AlCl _Three The temperature which shows the same saturated vapor pressure is lower than chlorinated compounds such as. For example, the HCl temperature at a saturated vapor pressure of 1333 Pa (≈10 Torr) is −136 ° C., whereas Cl ₂ Is −102 ° C. Furthermore, AlCl which is one of chlorinated compounds _Three Is 124 ° C., a very high temperature compared to HCl. That is, Cl ₂ And AlCl _Three Chlorinated compounds such as H ₂ By reacting with O to make HCl, Cl (chlorine), which causes corrosion of the metal wiring, tends to exist in a gaseous state and can be easily removed.
[0017]
On the other hand, in the method of the present invention, after dry etching is performed in a reaction chamber to form a metal wiring having a predetermined shape, H ₂ It is characterized by introducing O gas. Therefore, in order to continuously process a plurality of substrates in the same reaction chamber, it is desired to keep the temperature in the reaction chamber constant. When the temperature in the reaction chamber is as low as 70 ° C. or lower, H ₂ O and Cl ₂ And AlCl _Three The reaction with chlorine-based compounds such as the above becomes worse, and the removal of Cl becomes difficult. Further, although the removal of Cl becomes efficient when the temperature of the reaction chamber becomes high, the heat resistance of the photoresist becomes a problem when the temperature becomes higher than 200 ° C. For this reason, the temperature in the reaction chamber is set in the range of 70 ° C to 200 ° C. However, in consideration of the durability of an organic resin part of the etching apparatus, for example, an O-ring or the like, a temperature of 100 ° C. or lower is preferable.
[0018]
In order to remove chlorine remaining on the surface of the resist and wiring with high reliability even for fine patterns, H ₂ O gas and Cl ₂ (Chlorine) and AlCl _Three As shown in FIG. 1 (C), chlorine-based compounds such as ₂ When introducing O gas, Cl ₂ (Chlorine) and AlCl _Three It is desirable that a chlorine-based compound such as is present in a gaseous state. For this reason, H ₂ The pressure of the reaction chamber when introducing O gas is Cl ₂ And AlCl _Three Chlorinated compounds such as H and ₂ It is necessary that the pressure be such that O can exist in a gaseous state. For example, molecules remaining in the reaction chamber are Cl ₂ AlCl which is one of the above-mentioned chlorinated compounds _Three And H ₂ Assuming that there are three types of O, the saturated vapor pressure at 100 ° C. is AlCl _Three Is 133 Pa (≈1 Torr), which is the lowest compared to other molecules. Therefore, in order for the molecules to exist in a gaseous state, the pressure may be set to 133 Pa or less. Therefore, H ₂ In the case where the reaction chamber is kept at 100 ° C. when introducing the O gas, by maintaining a low pressure state of 133 Pa or less, Cl ₂ And AlCl _Three Chlorinated compounds such as H and ₂ O becomes HCl gas more effectively and efficiently (FIG. 1D).
[0019]
In this way, Cl remaining on the surface of the resist and wiring ₂ (Chlorine) and AlCl _Three Since the chlorine-based compounds such as HCl are removed from the surface as HCl, the metal wiring is not corroded even when opened to the atmosphere (FIG. 1E).
[0020]
Further, in the method of the present invention, H in the same reaction chamber. ₂ After introducing the O gas, the reaction chamber must be returned to a clean state in order to dry-etch the metal film again. For this reason, H remaining in the reaction chamber ₂ A step of removing O is required. Such H ₂ O can be removed by plasma treatment using one or more selected from Ar, Kr or Xe. In order to improve the throughput, it is desirable to perform the plasma treatment with the substrate after being etched or before being etched in the reaction chamber. However, since plasma is used, damage due to charge-up becomes a problem. However, by performing plasma processing under conditions that do not require much self-bias, the substrate is not damaged by the plasma. ₂ O can be removed.
[0021]
By repeating the above steps, metal wiring is formed in the same processing chamber, chlorine is reliably removed even for fine patterns, and corrosion of the metal wiring is prevented without damaging the underlying film. Can be achieved.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described. FIG. 2 schematically shows the structure of an etching apparatus for carrying out the present invention.
[0023]
The etching apparatus of FIG. 2 is a single wafer type dry etching apparatus having a vacuum preliminary chamber 201 and a reaction chamber 202. In FIG. 2, 203 is a substrate cassette, 204 and 205 are gate valves, 206 is a substrate transfer arm, 207 and 208 are vacuum exhaust pipes, 209 and 210 are vacuum exhaust pumps, 211 and 212 Is a gas supply pipe.
[0024]
A series of operations of the embodiment of the present invention using the etching apparatus configured as described above will be described. First, an Al film serving as a wiring material, or a single-layer Al alloy film such as Al-Si, Al-Cu, Al-Si-Cu, Al-Nd, Al-Ti, Al-Mo, Al-Sc ( Alternatively, a laminated film of an Al alloy film and a film mainly containing a metal other than Al, such as a Ta film, a Ti film, a W-Mo film, a Ti-Ta film, a titanium nitride film, or a tungsten nitride film, is formed by sputtering or vapor deposition. A substrate on which a photoresist is formed on the substrate cassette 203 is set on the substrate cassette 203.
[0025]
Then, the substrate is transferred from the substrate cassette to the vacuum preliminary chamber 201 by the substrate transfer arm 206, and the vacuum preliminary chamber is evacuated.
[0026]
After the evacuation is completed, the first substrate is transferred to the reaction chamber 202 which is always in a low pressure (vacuum) state and the temperature is maintained at 70 ° C. to 200 ° C. In the reaction chamber, Cl ₂ , SiCl _Four , BCl _Three , CCl _Four A gas containing chlorine such as is supplied from the gas supply pipe 212, and the wiring material is dry-etched to form a metal wiring. After etching, H in the reaction chamber ₂ A gas containing O is introduced to leave Cl remaining on the resist and wiring surfaces. ₂ (Chlorine) and AlCl _Three Remove chlorinated compounds such as During this time, the vacuum preliminary chamber is set to atmospheric pressure, and the second substrate is transferred to the vacuum preliminary chamber by the substrate transfer arm.
[0027]
Thereafter, H remaining in the reaction chamber ₂ O is removed by plasma treatment with one or more kinds of inert gases such as Ar, Kr or Xe. H by this plasma treatment ₂ Since the O treatment is performed under the condition that the self-bias is not so much, the substrate is hardly damaged. Therefore, the substrate is not in the reaction chamber and H ₂ O may be removed, but the throughput is further improved when the substrate after etching or the substrate before etching is in the reaction chamber.
[0028]
In particular, when the plasma treatment is performed with an inert gas in a state where the substrate is in the reaction chamber, the substrate that has been etched in the reaction chamber is transported to the vacuum preliminary chamber and the second sheet that has already been transferred to the vacuum preliminary chamber. It is preferable to carry out after carrying the substrate to the reaction chamber.
This is because the surface of the substrate after etching is etched with the metal film on the surface and the underlying film appears, so that the surface of the substrate before etching is covered with a metal film compared to the case where the plasma charge tends to accumulate. This is because the charge is hard to accumulate.
[0029]
After this, H ₂ Etching of the second substrate is performed in the reaction chamber where O is removed and cleaned. Meanwhile, the vacuum preliminary chamber is set to atmospheric pressure, the first substrate is returned to the substrate cassette, and the third substrate is moved to the vacuum preliminary chamber.
[0030]
The above is a series of operations, and by repeating this, metal wiring is continuously formed in the same processing chamber.
[0031]
【Example】
[Example 1]
An embodiment of the present invention will be described with reference to FIGS. Here, a method for manufacturing a pixel TFT which is a switching element of a pixel portion and a TFT of a driver circuit (a source signal line driver circuit, a gate signal line driver circuit, or the like) provided in the periphery of the pixel portion on the same substrate according to the process. This will be described in detail. However, in order to simplify the description, a CMOS circuit, which is a basic configuration circuit, is illustrated as the drive circuit unit, and an n-channel TFT is illustrated as the pixel TFT unit.
[0032]
In FIG. 3A, a substrate 6001 includes polyethylene terephthalate (PET) in addition to a glass substrate such as barium borosilicate glass, aluminoborosilicate glass or quartz represented by # 7059 glass or # 1737 glass manufactured by Corning. ), Polyethylene naphthalate (PEN), polyethersulfone (PES), or the like, a plastic substrate having no optical anisotropy can be used. In the case of using a glass substrate, heat treatment may be performed in advance at a temperature lower by about 10 to 20 ° C. than the glass strain point. In this example, Corning # 1737 glass is used. A base film 6002 such as a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is formed on the surface of the substrate 6001 where a TFT is formed in order to prevent impurity diffusion from the substrate 6001. For example, SiH by plasma CVD method _Four , NH _Three , N ₂ A silicon oxynitride film made from O is 100 nm, similarly SiH _Four , N ₂ A silicon oxynitride film formed from O is stacked to a thickness of 200 nm.
[0033]
Next, a semiconductor film 6003a having an amorphous structure with a thickness of 20 to 150 nm (preferably 30 to 80 nm) is formed by a known method such as a plasma CVD method or a sputtering method. In this embodiment, an amorphous silicon film is formed to a thickness of 54 nm by plasma CVD. As the semiconductor film having an amorphous structure, there are an amorphous semiconductor film and a microcrystalline semiconductor film, and a compound semiconductor film having an amorphous structure such as an amorphous silicon germanium film may be applied. Further, since the base film 6002 and the amorphous silicon film 6003a can be formed by the same film formation method, they may be formed continuously. In that case, after the base film is formed, it is possible to prevent contamination of the surface by not exposing it to the air atmosphere, and variations in characteristics of the TFT to be manufactured and variations in threshold voltage can be reduced.
[0034]
Then, a crystallization step is performed to form a crystalline silicon film 6003b from the amorphous silicon film 6003a. As the method, a laser annealing method, a thermal annealing method, a solid phase growth method), or a rapid thermal annealing method (RTA method) can be applied. in front Predicate As Resistance Poor heat The When using a plastic substrate, it is particularly desirable to apply a laser annealing method. In the RTA method, an infrared lamp, a halogen lamp, a metal halide lamp, a xenon lamp, or the like is used as a light source. In this embodiment, a crystalline silicon film 6003b is formed by a crystallization method using a catalytic element in accordance with the technique disclosed in Japanese Patent Laid-Open No. 7-130552. Prior to the crystallization step, depending on the amount of hydrogen contained in the amorphous silicon film, heat treatment is performed at 400 to 500 ° C. for about 1 hour to reduce the amount of hydrogen to 5 atoms% or less, and then crystallization is performed. desirable. When the amorphous silicon film is crystallized, the rearrangement of atoms occurs and the amorphous silicon film is densified. Therefore, the thickness of the crystalline silicon film to be produced is larger than the initial thickness of the amorphous silicon film (54 nm in this embodiment). Is also reduced by about 1 to 15% (FIG. 3B).
[0035]
Then, the crystalline silicon film 6003b is patterned into an island shape to form island-like semiconductor layers 6004 to 6007. Thereafter, a mask layer 6008 made of a silicon oxide film having a thickness of 50 to 150 nm is formed by plasma CVD or sputtering. (FIG. 3C).
[0036]
Then, a resist mask 6009 is provided, and 1 × 10 6 is formed on the entire surface of the island-like semiconductor layers 6004 to 6007 where n-channel TFTs are to be formed. ¹⁶ ~ 5x10 ¹⁷ atoms / cm ^Three B (boron) is added as an impurity element imparting p-type at a concentration of about. The addition of B (boron) is performed for the purpose of controlling the threshold voltage. B (boron) may be added by an ion doping method, or may be added simultaneously with the formation of the amorphous silicon film. The addition of B (boron) here is not always necessary (FIG. 3D). Thereafter, the resist mask 6009 is removed.
[0037]
In order to form the LDD region of the n-channel TFT of the driver circuit, an impurity element imparting n-type conductivity is selectively added to the island-shaped semiconductor layers 6010 to 6012. Therefore, resist masks 6013 to 6016 are formed in advance. As the impurity element imparting n-type conductivity, P (phosphorus) or arsenic (As) may be used. Here, phosphine (PH) is added to add P (phosphorus). _Three ) Was applied. The P (phosphorus) concentration of the impurity regions 6017 and 6018 formed is 2 × 10 ¹⁶ ~ 5x10 ¹⁹ atoms / cm ^Three It may be in the range. In this specification, the concentration of the impurity element imparting n-type contained in the impurity regions 6017 to 6019 formed here is expressed as (n−). The impurity region 6019 is a semiconductor layer for forming a storage capacitor of the pixel portion, and P (phosphorus) is added to this region at the same concentration (FIG. 4A). Thereafter, the resist masks 6013 to 6016 are removed.
[0038]
Next, after removing the mask layer 6008 with hydrofluoric acid or the like, a step of activating the impurity element added in FIGS. 3D and 4A is performed. The activation can be performed by a heat treatment at 500 to 600 ° C. for 1 to 4 hours or a laser activation method in a nitrogen atmosphere. Moreover, you may carry out using both together. In order to produce a crystalline semiconductor film by the laser crystallization method, a pulse oscillation type or continuous emission type excimer laser, a solid-state laser such as a YAG laser, or YVO is used. _Four Laser, YLF laser, YAlO _Three Use a laser. These solid-state lasers can achieve a high output and a high repetition frequency by using a laser diode excitation method. YAG laser, YVO4 laser, YLF laser, YAlO _Three The laser can use the second harmonic (532 nm), the third harmonic (355 nm), and the fourth harmonic (266 nm). Broadly speaking, when laser light having a wavelength of 400 nm or more is irradiated, it can be crystallized by heating from the inside of the semiconductor film in consideration of the penetration depth of light. On the other hand, when the wavelength is 400 nm or less, it can be crystallized by heating from the surface of the semiconductor film. In any case, the number of irradiation pulses and the irradiation energy density are set appropriately.
[0039]
When these lasers are used, it is preferable to use a method in which laser light emitted from a laser oscillator is linearly collected by an optical system and irradiated onto a semiconductor film. Crystallization conditions are appropriately selected by the practitioner. When an excimer laser is used, the pulse oscillation frequency is 30 Hz, and the laser energy density is 100 to 400 mJ / cm. ² (Typically 200-300mJ / cm ² ). When a YAG laser is used, the second harmonic is used and the pulse oscillation frequency is 1 to 10 kHz, and the laser energy density is 300 to 600 mJ / cm. ² (Typically 350-500mJ / cm ² ) Then, a laser beam condensed linearly with a width of 100 to 1000 μm, for example 400 μm, is irradiated over the entire surface of the substrate, and the superposition rate (overlap rate) of the linear laser beam at this time is 80 to 98%. Note that the laser light irradiation conditions are not limited and can be appropriately determined.
[0040]
In this embodiment, a laser activation method is used. The laser light is KrF excimer laser light (wavelength 248 nm), the shape of the laser light is processed into a linear beam, the oscillation frequency is 5 to 50 Hz, and the energy density is 100 to 500 mJ / cm. ² Then, the entire surface of the substrate on which the island-shaped semiconductor layer is formed is processed by scanning the linear beam with an overlap ratio of 85%.
[0041]
Then, the gate insulating film 6020 is formed with an insulating film containing silicon with a thickness of 10 to 150 nm by a plasma CVD method or a sputtering method. For example, a silicon oxynitride film is formed with a thickness of 120 nm. As the gate insulating film, another insulating film containing silicon may be used as a single layer or a stacked structure (FIG. 4B).
[0042]
Next, a first conductive layer is formed to form a gate electrode. The first conductive layer may be formed as a single layer, but may have a laminated structure such as two layers or three layers as necessary. In this embodiment, a conductive layer (A) 6021 made of a conductive nitride metal film and a conductive layer (B) 6022 made of a metal film are laminated. The conductive layer (B) 6022 is an element selected from Ta (tantalum), Ti (titanium), Mo (molybdenum), and W (tungsten), an alloy containing the element as a main component, or an alloy film in which the elements are combined. (Typically Mo—W alloy film, Mo—Ta alloy film), and the conductive layer (A) 6021 is TaN (tantalum nitride), WN (tungsten nitride), TiN (titanium nitride) film, MoN. (Molybdenum nitride) is formed.
Alternatively, tungsten silicide, titanium silicide, or molybdenum silicide may be applied to the conductive layer (A) 6021 as an alternative material. In the conductive layer (B), it is preferable to reduce the concentration of impurities contained in order to reduce resistance, and in particular, the oxygen concentration is preferably 30 ppm or less. For example, W (tungsten) can realize a specific resistance value of 20 μΩcm or less by setting the oxygen concentration to 30 ppm or less.
[0043]
The conductive layer (A) 6021 may be 10 to 50 nm (preferably 20 to 30 nm), and the conductive layer (B) 6022 may be 200 to 400 nm (preferably 250 to 350 nm). In this embodiment, a 30 nm thick tantalum nitride film is used for the conductive layer (A) 6021 and a 350 nm Ta film is used for the conductive layer (B) 6022, both of which are formed by sputtering. In film formation by this sputtering method, if an appropriate amount of Xe or Kr is added to the sputtering gas Ar, the internal stress of the film to be formed can be relaxed and the film can be prevented from peeling. Although not shown, it is effective to form a silicon film doped with P (phosphorus) with a thickness of about 2 to 20 nm under the conductive layer (A) 6021. This improves adhesion and prevents oxidation of the conductive film formed thereon, and at the same time, an alkali metal element contained in a trace amount in the conductive layer (A) or the conductive layer (B) diffuses into the gate insulating film 6020. Can be prevented (FIG. 4C).
[0044]
Next, resist masks 6023 to 6027 are formed, and the conductive layers (A) 6021 and (B) 6022 are etched together to form gate electrodes 6028 to 6031 and capacitor wirings 6032. The gate electrodes 6028 to 6031 and the capacitor wiring 6032 are integrally formed of 6028a to 6032a made of a conductive layer (A) and 6028b to 6032b made of a conductive layer (B). At this time, the gate electrode of the TFT constituting the drive circuit 6029 ˜6030 are formed so as to overlap with part of the impurity regions 6017 and 6018 with the gate insulating film 6020 interposed therebetween (FIG. 4D).
[0045]
Next, in order to form a source region and a drain region of the p-channel TFT of the driver circuit, a step of adding an impurity element imparting p-type is performed. Here, impurity regions are formed in a self-aligning manner using the gate electrode 6028 as a mask. At this time, a region where the n-channel TFT is formed is covered with a resist mask 6033. And B ₂ H ₆ An impurity region 6034 is formed by an ion doping method using (diborane). The B (boron) concentration in this region is 3 × 10 ²⁰ ~ 3x10 ^{twenty one} atoms / cm ^Three To be. Thereafter, the resist mask 6033 is removed. In this specification, the concentration of the impurity element imparting p-type contained in the impurity region 6034 formed here is expressed as (p ++) (FIG. 5A).
[0046]
Next, in the n-channel TFT, an impurity region functioning as a source region or a drain region is formed. Resist masks 6035 to 6037 are formed, and an impurity element imparting n-type conductivity is added to form impurity regions 6038 to 6042. This is PH _Three (Phosphine) is used for ion doping, and the P (phosphorus) concentration in this region is 1 × 10 ²⁰ ~ 1x10 ^{twenty one} atoms / cm ^Three And In this specification, the concentration of the impurity element imparting n-type contained in the impurity regions 6038 to 6042 formed here is defined as (n ⁺ ) (FIG. 5B).
[0047]
The impurity regions 6038 to 6042 contain P (phosphorus) or B (boron) that has already been added in the previous step, but P (phosphorus) is added at a sufficiently higher concentration than that. The influence of P (phosphorus) or B (boron) added in the previous process may not be considered. Further, since the P concentration added to the impurity region 6038 is 1/2 to 1/3 of the B concentration added in FIG. 5A, p-type conductivity is ensured, and the TFT characteristics are affected. There is nothing.
[0048]
After removing the resist masks 6035 to 6037, an impurity addition step for imparting n-type for forming an LDD region of the n-channel TFT in the pixel portion was performed. Here, an impurity element imparting n-type is added by ion doping in a self-aligning manner using the gate electrode 6031 as a mask. The concentration of P (phosphorus) to be added is 1 × 10 ¹⁶ ~ 5x10 ¹⁸ atoms / cm ^Three By adding the impurity element at a concentration lower than that of the impurity element added in FIGS. 4A, 5A, and 5B, substantially only impurity regions 6043 and 6044 are formed. The In this specification, the concentration of an impurity element imparting n-type contained in the impurity regions 6043 and 6044 is defined as (n ^- ) (FIG. 5C).
[0049]
Thereafter, a heat treatment process is performed to activate the impurity element imparting n-type or p-type added at each concentration. This step can be performed by a furnace annealing method, a laser annealing method, or a rapid thermal annealing method (RTA method). Here, the activation process is performed by furnace annealing. The heat treatment is performed at 400 to 800 ° C., typically 500 to 600 ° C. in a nitrogen atmosphere having an oxygen concentration of 1 ppm or less, preferably 0.1 ppm or less. In this embodiment, the heat treatment is performed at 500 ° C. for 4 hours. Do. Further, in the case where a substrate 6001 having heat resistance such as a quartz substrate is used, heat treatment may be performed at 800 ° C. for 1 hour, and activation of the impurity element, impurity region to which the impurity element is added, and A junction with the channel formation region can be formed satisfactorily. Note that this effect may not be obtained when an interlayer film for preventing Ta peeling of the gate electrode is formed.
[0050]
When laser annealing is used, a pulse oscillation type or continuous emission type excimer laser, a solid-state laser such as a YAG laser, or YVO _Four Laser, YLF laser, YAlO _Three Laser can be applied. These solid-state lasers can achieve a high output and a high repetition frequency by using a laser diode excitation method. YAG laser, YVO _Four Laser, YLF laser, YAlO _Three The laser can use the second harmonic (532 nm), the third harmonic (355 nm), and the fourth harmonic (266 nm). Broadly speaking, when laser light having a wavelength of 400 nm or more is irradiated, annealing can be performed by heating from the inside of the semiconductor film in consideration of the penetration depth of light. On the other hand, when the wavelength is 400 nm or less, annealing can be performed by heating from the surface of the semiconductor film. In any case, the number of irradiation pulses and the irradiation energy density are made suitable.
[0051]
In this heat treatment, conductive films (C) 6028c to 6032c are formed with a thickness of 5 to 80 nm from the surface of the metal films 6028b to 6032b forming the gate electrodes 6028 to 6031 and the capacitor wiring 6032. For example, WN (tungsten nitride) can be formed when the conductive layers (B) 6028b to 6032b are tungsten (W), and TaN (tantalum nitride) can be formed when the conductive layers (B) 6028b to 6032b are Ta (tantalum). The conductive layers (C) 6028c to 6032c can be formed in the same manner even when the gate electrodes 6028 to 6031 and the capacitor wiring 6032 are exposed to a plasma atmosphere containing nitrogen using nitrogen or ammonia. Further, a heat treatment is performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen to perform a step of hydrogenating the island-shaped semiconductor layer. This step is a step of terminating dangling bonds in the semiconductor layer with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma or hydrogenated plasma) may be performed.
[0052]
An island-shaped semiconductor layer is formed from an amorphous silicon film by a crystallization method using a catalytic element Is In this case, a trace amount of catalytic element remains in the island-like semiconductor layer. Of course, the TFT can be completed even in such a state, but it is more preferable to remove at least the remaining catalyst element from the channel formation region. One means for removing this catalytic element is a means that utilizes the gettering action by P (phosphorus). The concentration of P (phosphorus) necessary for gettering is the impurity region (n) formed in FIG. ⁺ The catalytic element can be gettered from the channel formation region of the n-channel TFT and the p-channel TFT by the heat treatment in the activation process performed here (FIG. 5D).
[0053]
When the activation and hydrogenation steps are completed, a second conductive film is formed as a gate wiring. The second conductive film includes a conductive layer (D) mainly composed of low resistance materials such as Al (aluminum) and Cu (copper), Ti (titanium), Ta (tantalum), W (tungsten), Mo ( And a conductive layer (E) made of molybdenum).
In this embodiment, an Al alloy film containing 0.1 to 2% by weight of titanium (Ti) is formed as the conductive layer (D) 6045, and a titanium (Ti) film is formed as the conductive layer (E) 6046. The conductive layer (D) 6045 may be 200 to 400 nm (preferably 250 to 350 nm), and the conductive layer (E) 6046 may be 50 to 200 (preferably 100 to 150 nm). (Fig. 6 (A))
[0054]
Then, a photoresist is formed into a predetermined shape using a photomask in order to form a gate wiring connected to the gate electrode. By etching the conductive layer (E) 6046 and the conductive layer (D) 6045, gate wirings 6047 and 6048 and a capacitor wiring 6049 are formed. The etching process first removes the surface of the conductive layer (E) to the middle of the conductive layer (D) by the method shown in the first embodiment. First, in a processing chamber at a temperature of 100 ° C., Cl ₂ And BCl _Three Etching is performed using a mixed gas with the gas, and then the pressure in the processing chamber is kept at 66.5 Pa. ₂ The flow rate of O gas is 300 sccm, and the treatment is performed for 120 seconds to remove Cl (chlorine) adhering to the surface. In addition, H in the reaction chamber ₂ O is removed by plasma treatment with Ar. Thereafter, the conductive layer (D) is removed by wet etching with a phosphoric acid-based etching solution, whereby the gate wiring can be formed while maintaining selective processability with the base.
[0055]
The first interlayer insulating film 6050 is formed of a silicon oxide film or a silicon oxynitride film with a thickness of 500 to 1500 nm, and forms a contact hole reaching the source region or the drain region formed in each island-shaped semiconductor layer. Thereafter, a metal film to be the source wirings 6051 to 6054 and the drain wirings 6055 to 6058 is formed, and a photoresist is formed in a predetermined shape using a photomask thereon.
Although not shown, in this embodiment, this electrode is a laminated film having a three-layer structure in which a Ti film is 100 nm, an aluminum film containing Ti is 300 nm, and a Ti film is 150 nm continuously formed by sputtering. Source wirings 6051 to 6054 and drain wirings 6055 to 6058 are formed by the method. First, in a processing chamber at a temperature of 75 ° C., Cl ₂ And BCl _Three Etching is performed using a mixed gas with the gas, and then the pressure in the processing chamber is kept at 66.5 Pa. ₂ The flow rate of O gas is 300 sccm, and the treatment is performed for 120 seconds to remove Cl (chlorine) adhering to the surface. In addition, H in the reaction chamber ₂ O is removed by plasma treatment with Ar.
[0056]
Next, a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film is formed as the passivation film 6059 with a thickness of 50 to 500 nm (typically 100 to 300 nm). When the hydrogenation treatment is performed in this state, a favorable result can be obtained for improving the characteristics of the TFT. For example, heat treatment may be performed at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen, or the same effect can be obtained by using a plasma hydrogenation method. Note that an opening may be formed in the passivation film 6059 at a position where a contact hole for connecting the pixel electrode and the drain wiring is formed later (FIG. 6C).
[0057]
Thereafter, a second interlayer insulating film 6060 made of an organic resin is formed to a thickness of 1.0 to 1.5 μm. As the organic resin, polyimide, acrylic, polyamide, polyimide amide, BCB (benzocyclobutene), or the like can be used. Here, after applying to the substrate, a thermal polymerization type polyimide is used and baked at 300 ° C. Then, a contact hole reaching the drain wiring 6058 is formed in the second interlayer insulating film 6060, and pixel electrodes 6061 and 6062 are formed. The pixel electrode may be a transparent conductive film in the case of a transmissive liquid crystal display device, and may be a metal film in the case of a reflective liquid crystal display device. When a reflective liquid crystal display device is used to form a single-layer Al alloy film or a laminated film of an Al alloy film and a metal film other than Al, the reflective electrode can be formed by the method of Embodiment 1. . In this embodiment, an ITO (Indium Tin Oxide) film is formed to a thickness of 100 nm by sputtering to obtain a transmissive liquid crystal display device (FIG. 7).
[0058]
In this manner, a substrate having the TFT of the driving circuit and the pixel TFT of the pixel portion can be completed on the same substrate. A p-channel TFT 6101, a first n-channel TFT 6102, and a second n-channel TFT 6103 are formed in the driver circuit, and a pixel TFT 6104 and a storage capacitor 6105 are formed in the pixel portion. In this specification, such a substrate is referred to as an active matrix substrate for convenience.
[0059]
The p-channel TFT 6101 of the driver circuit includes a channel formation region 6106, source regions 6107a and 6107b, and drain regions 6108a and 6108b in an island-shaped semiconductor layer 6004. The first n-channel TFT 6102 includes an LDD region 6110 that overlaps the island-shaped semiconductor layer 6005 with the channel formation region 6109 and the gate electrode 6029 (hereinafter, such an LDD region is referred to as an LD region). _ov A source region 6111 and a drain region 6112. This L _ov The length of the region in the channel length direction was 0.5 to 3.0 μm, preferably 1.0 to 1.5 μm. The second n-channel TFT 6103 has a channel formation region 6113, LDD regions 6114 and 6115, a source region 6116, and a drain region 6117 in the island-shaped semiconductor layer 6006. This LDD region is L _ov LDD region that does not overlap with the gate electrode 6030 (hereinafter, such an LDD region is referred to as L _off And this L is formed. _off The length of the region in the channel length direction is 0.3 to 2.0 μm, preferably 0.5 to 1.5 μm. In the pixel TFT 6104, channel formation regions 6118, 6119, L _off It has regions 6120 to 6123 and source or drain regions 6124 to 6126. L _off The length of the region in the channel length direction is 0.5 to 3.0 μm, preferably 1.5 to 2.5 μm. Further, the storage capacitor 6105 includes capacitor wirings 6032 and 6049, an insulating film made of the same material as the gate insulating film, and a semiconductor layer 6127 which is connected to the drain region 6126 of the pixel TFT 6104 and to which an impurity element imparting n-type conductivity is added. Is formed. Although the pixel TFT 6104 has a double gate structure in FIG. 7, it may have a single gate structure or a multi-gate structure provided with a plurality of gate electrodes.
[0060]
As described above, in this embodiment, it is possible to optimize the structure of the TFT constituting each circuit according to the specifications required by the pixel TFT and the drive circuit, and to improve the operation performance and reliability of the semiconductor device. Can do. Furthermore, the LDD region, the source region, and the drain region can be easily activated by forming the gate electrode from a heat-resistant conductive material, and the wiring resistance can be sufficiently reduced by forming the gate electrode from a low-resistance material. Therefore, the present invention can be applied to a display device having a pixel portion (screen size) of 4 inches class or more.
[0061]
[Example 2]
In this embodiment, a process of manufacturing a transmissive liquid crystal panel based on the active matrix substrate manufactured by the process of Embodiment 1 will be described.
[0062]
Please refer to FIG. An alignment film 6201 is formed on the active matrix substrate in the state of FIG. In this embodiment, polyimide is used for the alignment film 6201. Next, a counter substrate is prepared. The counter substrate is a counter electrode made of a glass substrate 6202, a light shielding film 6203, and a transparent conductive film. 6204 , And an alignment film 6205.
[0063]
In this embodiment, a polyimide film in which liquid crystal molecules are aligned in parallel to the substrate is used for the alignment film. Note that after the alignment film is formed, a rubbing process is performed so that the liquid crystal molecules are aligned in parallel with a certain pretilt angle.
[0064]
Next, the active matrix substrate and the counter substrate that have undergone the above-described steps are bonded to each other through a sealing material, a spacer (both not shown), and the like by a known cell assembling step. Thereafter, liquid crystal 6206 is injected between both the substrates and completely sealed with a sealant (not shown). Therefore, a transmissive liquid crystal panel as shown in FIG. 8 is completed.
[0065]
[Example 3]
In this embodiment, an example of a liquid crystal display device manufactured according to the present invention is shown in FIG.
Since a known method may be used for a manufacturing method of a pixel TFT (pixel switching element) and a cell assembly process, detailed description thereof is omitted.
[0066]
FIG. 9 is a schematic diagram of the active matrix type liquid crystal panel of this embodiment. As shown in FIG. 9, the active matrix substrate and the counter substrate face each other, and liquid crystal is sandwiched between these substrates. The active matrix substrate includes a pixel portion 1001 formed on a glass substrate 1000, a scanning line driver circuit 1002, and a signal line driver circuit 1003.
[0067]
The scan line driver circuit 1002 and the signal line driver circuit 1003 are connected to the pixel portion 1001 by a scan line 1030 and a signal line 1040, respectively. These drive circuits 1002 and 1003 are mainly composed of CMOS circuits.
[0068]
A scanning line 1030 is formed for each row of the pixel portion 1001, and a signal line 1040 is formed for each column. In the vicinity of the intersection of the scanning line 1030 and the signal line 1040, a pixel TFT 1010 Is formed. The gate electrode of the pixel TFT 1010 is connected to the scanning line 1030, and the source is connected to the signal line 1040. Further, a pixel electrode 1060 and a storage capacitor 1070 are connected to the drain.
[0069]
The counter substrate 1080 has a transparent conductive film such as an ITO film formed on the entire surface of the glass substrate. The transparent conductive film is a counter electrode with respect to the pixel electrode 1060 of the pixel portion 1001, and the liquid crystal material is driven by an electric field formed between the pixel electrode and the counter electrode. An alignment film, a black matrix, and a color filter are formed on the counter substrate 1080 if necessary.
[0070]
IC chips 1032 and 1033 are attached to the glass substrate on the active matrix substrate side using the surface to which the FPC 1031 is attached. These IC chips 1032 and 1033 are formed by forming circuits such as a video signal processing circuit, a timing pulse generation circuit, a γ correction circuit, a memory circuit, and an arithmetic circuit on a silicon substrate.
[0071]
Further, the liquid crystal display portion that can be manufactured using the present invention does not matter whether it is a transmissive type or a reflective type.
It is up to the practitioner to choose either. Thus, the present invention can be applied to any active matrix type electro-optical device (semiconductor device).
[0072]
Example 4
The present invention can also be applied to an active matrix EL display device. An example is shown in FIG.
[0073]
FIG. 10 is a circuit diagram of an active matrix EL display device. Reference numeral 81 denotes a display area, and an X-direction peripheral drive circuit 82 and a Y-direction peripheral drive circuit 83 are provided around the display area. Each pixel in the display area 81 includes a switching TFT 84, a capacitor 85, a current control TFT 86, and an organic EL element 87. The switching TFT 84 has an X direction signal line 88a (or 88b) and a Y direction signal line 80a ( Or 80b, 80c). Further, power supply lines 89 a and 89 b are connected to the current control TFT 86.
[0074]
Example 5
The present invention can be applied to all conventional IC technologies. That is, it can be applied to all semiconductor circuits currently on the market. For example, the present invention may be applied to a microprocessor such as a RISC processor or an ASIC processor integrated on one chip, and is represented by a liquid crystal driver circuit (D / A converter, γ correction circuit, signal dividing circuit, etc.). The present invention may be applied to a signal processing circuit and a high-frequency circuit for a portable device (mobile phone, PHS, mobile computer).
[0075]
A semiconductor circuit such as a microprocessor is mounted on various electronic devices and functions as a central circuit. Typical electronic devices include personal computers, portable information terminal devices, and all other home appliances. In addition, a computer for controlling a vehicle (such as an automobile or a train) may be used. The present invention can also be applied to such a semiconductor device.
[0076]
Example 6
The CMOS circuit and the pixel portion formed by implementing the present invention can be used for various electro-optical devices (active matrix liquid crystal display, active matrix EL display, active matrix EC display). That is, the present invention can be implemented in all electronic devices in which these electro-optical devices are incorporated as display units.
[0077]
Such electronic devices include video cameras, digital cameras, projectors (rear type or front type), head mounted displays (goggles type displays), car navigation systems, personal computers, personal digital assistants (mobile computers, mobile phones or electronic books). Etc.). Examples of these are shown in FIGS.
[0078]
FIG. 11A illustrates a personal computer, which includes a main body 2001, an image input portion 2002, a display portion 2003, and a keyboard 2004. The present invention can be applied to the image input unit 2002, the display unit 2003, and other signal control circuits.
[0079]
FIG. 10B illustrates a video camera, which includes a main body 2101, a display portion 2102, an audio input portion 2103, operation switches 2104, a battery 2105, and an image receiving portion 2106. The present invention can be applied to the display portion 2102, the voice input portion 2103, and other signal control circuits.
[0080]
FIG. 11C illustrates a mobile computer, which includes a main body 2201, a camera unit 2202, an image receiving unit 2203, operation switches 2204, and a display unit 2205. The present invention can be applied to the display portion 2205 and other signal control circuits.
[0081]
FIG. 11D illustrates a goggle type display which includes a main body 2301, a display portion 2302, and an arm portion 2303. The present invention can be applied to the display portion 2302 and other signal control circuits.
[0082]
FIG. 11E shows a player using a recording medium (hereinafter referred to as a recording medium) on which a program is recorded. The player includes a main body 2401, a display portion 2402, a speaker portion 2403, a recording medium 2404, and operation switches 2405. This apparatus uses a DVD (Digital Versatile Disc), CD, or the like as a recording medium, and can perform music appreciation, movie appreciation, games, and the Internet. The present invention can be applied to the display portion 2402 and other signal control circuits.
[0083]
FIG. 11F illustrates a digital camera which includes a main body 2501, a display portion 2502, an eyepiece portion 2503, an operation switch 2504, and an image receiving portion (not shown). The present invention can be applied to the display portion 2502 and other signal control circuits.
[0084]
Figure 12 (A) is a front type projector, which is composed of a light source optical system, a display unit 2601, and a screen 2602. The present invention can be applied to a display unit and other signal control circuits.
[0085]
FIG. 12B shows a rear projector, which includes a main body 2701, a light source optical system and display unit 2702, a mirror 2703, and a screen 2704. The present invention can be applied to a display unit and other signal control circuits.
[0086]
As described above, the applicable range of the present invention is so wide that the present invention can be applied to electronic devices in various fields. Further, the electronic apparatus of the present embodiment can be realized by using a configuration including any combination of the first to fifth embodiments.
[0087]
【The invention's effect】
By using the present invention, metal wiring is formed by dry etching in the same processing chamber, chlorine is removed without damaging the underlying film, and metal wiring is reliably corroded even for fine patterns. You can achieve preventing.
[0088]
[Brief description of the drawings]
FIG. 1 is a view showing a mechanism for preventing corrosion of a metal wiring according to the present invention.
FIG. 2 is a schematic view of an etching apparatus for carrying out the present invention.
3 is a diagram showing a TFT manufacturing process of Example 1. FIG.
4 is a diagram showing a TFT manufacturing process of Example 1. FIG.
5 is a diagram showing a TFT manufacturing process of Example 1. FIG.
6 shows a TFT manufacturing process of Example 1. FIG.
7 is a diagram showing a TFT manufacturing process of Example 1. FIG.
8 is a diagram showing a transmissive liquid crystal panel of Example 2. FIG.
FIG. 9 is a diagram showing an example of an active matrix substrate of Example 3.
10 shows an EL panel circuit diagram of Example 4. FIG.
FIG. 11 is a diagram illustrating an example of an electronic apparatus according to a sixth embodiment.
FIG. 12 is a diagram illustrating an example of an electronic apparatus according to a sixth embodiment.

Claims (5)

A metal film and a substrate having a photoresist on the metal film are transferred to a reaction chamber;
In the reaction chamber, the photoresist as a mask, the metal film, using a gas containing chlorine, by etching, to form a metal wiring, and chlorine compounds is generated on the surface of the metal wiring And
By introducing H ₂ O gas into the reaction chamber, the chlorine compound is removed,
Transporting the substrate from the reaction chamber;
Wherein the reaction chamber in line Ukoto plasma processing with an inert gas, a method of forming the metal wiring, and removing of H _{2 O} remaining in the reaction chamber. Oite to claim 1, wherein the metal film is an aluminum film, a single layer film mainly containing aluminum, or the film and the metal other than aluminum mainly containing aluminum is a laminated film of mainly comprising film A method for forming a metal wiring. Transporting a first substrate having a first metal film and a first photoresist on the first metal film to a reaction chamber;
A first metal wiring is formed in the reaction chamber by etching the first metal film using a gas containing chlorine using the first photoresist as a mask, and the first photoresist Chlorine compound is generated on the surface of the metal wiring of 1,
H in the reaction chamber ₂ By introducing O gas, the chlorine compound is removed,
Transporting the first substrate from the reaction chamber;
Transporting a second substrate having a second metal film and a second photoresist on the second metal film to the reaction chamber;
By performing plasma treatment with an inert gas in the reaction chamber, H remaining in the reaction chamber ₂ A method for forming a metal wiring, wherein O is removed. 4. The film according to claim 3, wherein the first metal film and the second metal film are an aluminum film, a single-layer film mainly containing aluminum, or a film mainly containing aluminum and a metal mainly containing aluminum. A method of forming a metal wiring, wherein   5. The inert gas according to claim 1, wherein the inert gas is selected from Ar (argon), Kr (krypton), or Xe (xenon). Method for forming metal wiring.

Images