JP4651773B2 - Method for manufacturing semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a semiconductor device having a circuit including thin film transistors (hereinafter referred to as TFTs) over a substrate having an insulating surface. In particular, the present invention relates to an electro-optical device typified by a liquid crystal display device in which a pixel TFT provided in a display region and a drive circuit provided in the periphery of the display region are provided on the same substrate, and such an electro-optical device. It can be suitably used for an electronic device equipped with the device. Note that in this specification, a semiconductor device refers to all devices that function by utilizing semiconductor characteristics, and includes the above-described electro-optical device and electronic equipment including the electro-optical device in its category.
[0002]
[Prior art]
A TFT in which an active layer is formed of a crystalline silicon film on a substrate having an insulating surface (hereinafter referred to as a crystalline silicon TFT) has high field effect mobility, so that various functional circuits can be formed. There has been developed the electro-optical device in which such a functional circuit is integrally formed on the same substrate. An active matrix liquid crystal display device is well known as a representative example.
[0003]
In an active matrix liquid crystal display device using crystalline silicon TFTs, a pixel TFT is formed in each pixel in the image display area, and a drive circuit is provided around the image display area. The drive circuit is composed of a shift register circuit, a level shifter circuit, a buffer circuit, a sampling circuit, etc., which are formed on the basis of a CMOS circuit. Such a circuit is formed on the same substrate, and the display device is completed as a unit.
[0004]
Since the operating conditions of the pixel TFT and the driving circuit are not necessarily the same, the characteristics required for the TFT are not a little different. For example, the pixel TFT is required to have a function as a switch element for applying a voltage to the liquid crystal. Since the liquid crystal is driven by alternating current, a method called frame inversion driving is often employed. In this method, in order to hold the charge of the holding capacitor, the characteristic required for the pixel TFT is to sufficiently reduce the off-current value (drain current that flows when the TFT is turned off). On the other hand, since a high drive voltage is applied to the buffer circuit of the drive circuit, it is necessary to increase the breakdown voltage of the TFT so that it does not break even when a high voltage is applied. Further, in order to increase the current driving capability, it is necessary to secure a sufficient on-current value (drain current that flows when the TFT is turned on).
[0005]
However, there is a problem that the off-current value of the crystalline silicon TFT tends to be high. In addition, as with MOS transistors used in ICs and the like, deterioration phenomena such as a decrease in on-current value are observed in crystalline silicon TFTs. The main cause is hot carrier injection, and it is considered that hot carriers generated by a high electric field near the drain cause a deterioration phenomenon.
[0006]
As a TFT structure for reducing the off-current value, a lightly doped drain (LDD) structure is known. In this structure, a region to which an impurity element is added at a low concentration is provided between a channel formation region and a source region or a drain region formed by adding an impurity element at a high concentration, and this region is referred to as an LDD region. I'm calling.
[0007]
Regarding a method for manufacturing a TFT having an LDD region, for example, in Japanese Patent No. 2564725, a gate insulating film is formed wider in the channel width direction than the gate electrode, and an insulating film thinner than the gate insulating film is formed beside the gate insulating film. A method of forming an LDD region in a semiconductor film between an end portion of a gate electrode and a source or drain region using the difference in thickness between the insulating film and the gate insulating film is disclosed.
[0008]
As a means for preventing deterioration due to hot carriers, a so-called GOLD (Gate-drain Overlapped LDD) structure in which an LDD region is disposed so as to overlap a gate electrode through a gate insulating film is known. With such a structure, a high electric field in the vicinity of the drain is relieved, hot carrier injection is prevented, and deterioration is effectively prevented. For example, “Mutuko Hatano, Hajime Akimoto and Takeshi Sakai, IEDM97 TECHNICAL DIGEST, p523-526, 1997” discloses a GOLD structure formed by side walls made of silicon, but compared with TFTs of other structures, It has been confirmed that extremely excellent reliability can be obtained.
[0009]
Introducing an impurity element into a semiconductor layer for forming an impurity region such as a source region, a drain region, and an LDD region of a TFT having such a structure is performed by using a gate electrode or a mask insulating film provided on the semiconductor layer. It was desirable to use this method in a self-aligned manner. Further, in order to reduce the number of masks, an impurity element of one conductivity type is once introduced into the entire surface using a gate electrode or an insulating film for a mask, and either a p-channel TFT or an n-channel TFT with a higher concentration than that is introduced. A method of introducing an impurity element having a conductivity type opposite to one conductivity type into the impurity region of one of the TFTs (referred to as a cross-doping method in this specification) has been adopted.
[0010]
[Problems to be solved by the invention]
However, the required characteristics are not necessarily the same between the pixel TFT and the TFT of a drive circuit such as a shift register circuit or a buffer circuit. For example, in a pixel TFT, a large reverse bias (a negative voltage in an n-channel TFT) is applied to the gate, but a TFT in a drive circuit basically does not operate in a reverse bias state. Also, regarding the operation speed, the pixel TFT was good at 1/100 or less of the TFT of the drive circuit.
[0011]
The GOLD structure has a high effect of preventing the deterioration of the on-current value, but there is a problem that the off-current value becomes larger than that of the normal LDD structure. Therefore, it is not a preferable structure for application to the pixel TFT. Conversely, the normal LDD structure has a high effect of suppressing the off-current value, but has a low effect of relaxing the electric field in the vicinity of the drain and preventing deterioration due to hot carrier injection. Thus, in a semiconductor device having a plurality of integrated circuits with different operating conditions, such as an active matrix liquid crystal display device, it is not always preferable to form all TFTs with the same structure. Such problems have become apparent as the characteristics of crystalline silicon TFTs increase and the performance required for active matrix liquid crystal display devices increases.
[0012]
Although there are several means for reducing the off-current value of the TFT, it is necessary to form a good junction between the channel formation region and the impurity region (LDD region, source region or drain region). For this purpose, it is necessary to precisely control the distribution of impurity elements at the interface between the channel formation region and the impurity region in contact therewith. However, when the above-described cross-doping method is performed, one impurity type impurity element and the opposite conductivity type impurity element are introduced into the impurity region of one TFT, and the distribution of the impurity element at the interface is reduced. It was difficult to control precisely.
[0013]
Such an LDD structure is formed in consideration of the characteristics of the n-channel TFT. A p-channel TFT formed on the same substrate for forming a CMOS circuit or the like is often formed with a single drain structure in order to reduce the number of masks as much as possible. However, in that case, the source or drain region of the p-channel TFT is doped with phosphorus (P) for forming the LDD of the n-channel TFT, and a defect is formed at the junction with the channel formation region, increasing the off-current value. There was a problem.
[0014]
The present invention is a technique for solving such a problem, and the operation characteristics of the semiconductor device can be obtained by making the structure of the TFT disposed in each circuit of the semiconductor device appropriate according to the function of the circuit. And to improve reliability.
[0015]
[Means for Solving the Problems]
In order to solve the above problems, the structure of the present invention is a semiconductor device in which a pixel TFT provided in a display region and an n-channel TFT and a p-channel TFT of a driver circuit provided in the periphery of the display region are provided on the same substrate In the device, the pixel TFT and the TFT of the drive circuit include an active layer, an LDD region provided in the active layer, a gate insulating film provided between the active layer and the substrate, A gate electrode provided between the gate insulating film and the substrate, and the LDD region of the pixel TFT and the n-channel TFT of the drive circuit is disposed so as to at least partially overlap the gate electrode; The LDD region of the p-channel TFT of the driving circuit is arranged so as to overlap with the gate electrode. In addition, the LDD region of the n-channel TFT of the pixel TFT and the driving circuit is disposed so as not to overlap with the channel protective insulating film provided in the TFT and at least partially overlaps the gate electrode. The LDD region of the p-channel TFT of the driver circuit is arranged to overlap with a protective insulating film of the TFT and with a gate electrode.
[0016]
According to another aspect of the invention, the p-channel TFT of the driving circuit provides an impurity region (A) including both an impurity element imparting p-type and an impurity element imparting n-type, and a p-type impart. An impurity region (B) containing only the impurity element to be formed, and the impurity region (B) is formed between the impurity region (A) and the LDD region of the p-channel TFT of the driver circuit. It is characterized by that.
[0017]
In this structure, phosphorus (P) doped in the source or drain region of the p-channel TFT without increasing the number of masks is not doped in the junction with the channel formation region, and the off-current value is reduced. It is an object.
[0018]
The storage capacitor connected to the pixel TFT is formed of a capacitor wiring formed on the substrate, an insulating film formed on the capacitor wiring, and a semiconductor layer formed on the insulating film. Alternatively, an organic resin film is formed on the pixel TFT, a light shielding film formed on the organic resin film, a dielectric film formed in close contact with the light shielding film, and a part of the light shielding film. A capacitor is formed from a pixel electrode that is provided so as to overlap and is connected to the pixel TFT.
[0019]
In order to solve the above problems, a method for manufacturing a semiconductor device of the present invention is the same as that of a pixel TFT provided in a display region, and an n-channel TFT and a p-channel TFT of a driver circuit provided around the display region. In the method for manufacturing a semiconductor device over the substrate, a step of forming an LDD region at least partially overlapping with the gate electrode in the pixel TFT and the n-channel TFT, and a p-channel TFT in the driver circuit are provided. And a step of forming an LDD region which overlaps with the gate electrode. A step of forming an LDD region in the pixel TFT and the n-channel TFT that does not overlap with a channel protection insulating film of the TFT and at least partially overlaps with a gate electrode; The TFT includes a step of forming an LDD region that overlaps with the channel protective insulating film of the TFT and overlaps with the gate electrode.
[0020]
In the above method for manufacturing a semiconductor device, an impurity region (A) including both an impurity element imparting p-type and an impurity element imparting n-type and p-type are imparted to the p-channel TFT of the driver circuit. Forming an impurity region (B) containing an impurity element, and the impurity region (B) is formed between the impurity region (A) and the LDD region of the p-channel TFT of the driver circuit. It is desirable.
[0021]
In another aspect of the invention, a semiconductor device having a pixel TFT provided in a display region and an n-channel TFT and a p-channel TFT of a driver circuit provided in the periphery of the display region on the same substrate is manufactured. In the method, a first step of forming a gate electrode on a substrate, a second step of forming a gate insulating film on the gate electrode, and forming first and second semiconductor layers on the gate insulating film A third step of performing, a fourth step of forming a channel protective film on the first and second semiconductor layers, and introducing an impurity element imparting n-type into the first semiconductor layer, A fifth step of forming an LDD region of the n-channel TFT that does not overlap with the channel protective film; and an impurity element imparting n-type conductivity is introduced into the first semiconductor layer, so that the source region or drain of the n-channel TFT Forming a region A seventh step of introducing an impurity element imparting p-type into the second semiconductor layer to form an LDD region and a source region or drain region of the p-channel TFT overlying the channel protective film; It is characterized by having these processes.
[0022]
In the method for manufacturing a semiconductor device of the present invention, a step of forming a capacitor wiring on the substrate, a step of forming an insulating layer on the capacitor wiring, and a step of forming a semiconductor layer on the insulating layer, A step of forming a storage capacitor connected to the pixel TFT, a step of forming an organic resin layer on the pixel TFT, a step of forming a light-shielding film on the organic resin, and a dielectric in close contact with the light-shielding film. A capacitor is formed from a step of forming a body film and a step of forming a pixel electrode that is provided so as to partially overlap the light shielding film and is connected to the pixel TFT. The light shielding film is preferably formed of a material containing one or more selected from aluminum, tantalum, and titanium, and the dielectric film is preferably formed of an oxide of a material forming the light shielding film. It is most preferable to use an anodic oxidation method as a method of forming the product.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described in detail with reference to the following examples.
[0024]
[Example 1]
An embodiment of the present invention will be described with reference to FIGS. Here, a method for simultaneously manufacturing a pixel TFT in the display region and a TFT in a driver circuit provided in the periphery of the display region will be described in detail according to the process.
[0025]
(Formation of gate electrode, gate insulating film, crystalline semiconductor film: FIG. 1A)
In FIG. 1A, a low alkali glass substrate or a quartz substrate can be used for the substrate 101. An insulating film such as a silicon oxide film, a silicon nitride film, or a silicon nitride oxide film may be formed on the surface of the substrate 101 on which the TFT is formed (not shown). The gate electrodes 102 to 104 and the capacitor wiring 105 are made of an element selected from tantalum (Ta), titanium (Ti), tungsten (W), molybdenum (Mo), and aluminum (Al), or a material mainly containing one of them. After forming a film by using a known film forming method such as sputtering or vacuum deposition, a pattern was formed by etching so that the end face was tapered. For example, a Ta film is formed to a thickness of 200 nm by sputtering, a resist mask is formed in a predetermined shape, and then CF _Four And O ₂ If the plasma etching process is performed with this mixed gas, it can be processed into a desired shape. The gate electrode may have a two-layer structure of tantalum nitride (TaN) and Ta or tungsten nitride (WN) and W (not shown). Although not shown here, a gate wiring connected to the gate electrode is also formed at the same time.
[0026]
The gate insulating film 106 is a material containing silicon oxide or silicon nitride as a component, and is formed to a thickness of 10 to 200 nm, preferably 50 to 150 nm. For example, plasma CVD method, SiH _Four , NH _Three , N ₂ A silicon nitride film 106a made from a material of 50 nm, SiH _Four And N ₂ A gate insulating film may be formed by stacking the silicon nitride oxide film 106b using O as a raw material to a thickness of 75 nm. Of course, a single layer made of a silicon nitride film or a silicon oxide film can be used. In order to obtain a clean surface, it is preferable to perform plasma hydrogen treatment before forming the gate insulating film.
[0027]
Next, a crystalline semiconductor film serving as an active layer of the TFT was formed. Silicon was used as the material of the crystalline semiconductor film. First, an amorphous silicon film having a thickness of 20 to 150 nm was formed in close contact with the gate insulating film 106 by a known film formation method such as a plasma CVD method or a sputtering method. There is no limitation on the conditions for forming the amorphous silicon film, but oxygen and nitrogen impurity elements contained in the film are 5 × 10 5. ¹⁸ cm ^-3 It is desirable to reduce it to the following. Further, since the gate insulating film and the amorphous silicon film can be formed by the same film formation method, they may be formed continuously. After the gate insulating film is formed, it is possible to prevent contamination of the surface by not exposing it to the air atmosphere, so that variation in characteristics of TFTs to be manufactured and variation in threshold voltage can be reduced. Then, a crystalline silicon film 107 is formed using a known crystallization technique. For example, the crystalline silicon film 107 is formed by a laser crystallization method, a thermal crystallization method (solid phase growth method), or a crystallization method using a catalytic element according to the technique disclosed in Japanese Patent Laid-Open No. 7-130552. May be.
[0028]
In the region of the crystalline silicon film 107 where the n-channel TFT is formed, 1 × 10 6 is used for the purpose of controlling the threshold voltage. ¹⁶ ~ 5x10 ¹⁷ cm ^-3 About boron (B) may be added. Boron (B) may be added by an ion doping method, or may be added simultaneously with the formation of an amorphous silicon film.
[0029]
(Mask insulation film formation, n ^- Region formation: FIG. 1 (B))
Next, in order to form an LDD region of the n-channel TFT, an impurity element imparting n-type was added. First, a mask insulating film 108 made of a silicon oxide film or a silicon nitride film was formed on the surface of the crystalline silicon film 107 to a thickness of 100 to 200 nm, typically 120 nm. After forming a photoresist film on the entire surface, the photoresist film was exposed using the gate electrodes 102 to 104 as a mask by an exposure method from the back surface of the substrate 101 to form resist masks 109 to 112 on the gate electrodes. By this method, a resist mask could be formed on the gate electrode and inside the gate electrode.
[0030]
Then, an impurity element imparting n-type conductivity was added to the crystalline silicon film below the mask insulating film 108 by an ion doping method (or an ion implantation method). In the technical field of semiconductors, phosphorus (P), arsenic (As), antimony (Sb), etc. are applied from the group 15 elements of the periodic table as impurity elements imparting n-type. Here, phosphorus (P) is used. Using. The formed impurity regions 113 to 118 have a phosphorus (P) concentration of 1 × 10 ¹⁷ ~ 5x10 ¹⁸ cm ^-3 In this case, 5 × 10 ¹⁷ cm ^-3 It was. In this specification, the concentration of an impurity element imparting n-type contained in the impurity regions 113 to 118 is defined as (n ^- ).
[0031]
(Channel protection film formation: FIG. 1C)
Next, the mask insulating film 108 was removed by etching using this resist mask to form channel protective films 119 to 122. In order to etch the mask insulating film 108 with high selectivity with respect to the crystalline silicon film 107 as a base, a wet etching method using a hydrofluoric acid-based solution is employed here. Of course, it may be performed by a dry etching method, for example, CHF. _Three The insulating film 108 can be etched with a gas. In any case, in this step, channel protection films 119 to 122 are formed inside the end faces of the resist masks 109 to 112 by over-etching.
[0032]
(N ⁺ Region formation: FIG. 2 (A))
Next, in the n-channel TFT, a step of forming an impurity region functioning as a source region or a drain region was performed. Here, resist masks 123 to 125 were formed by a normal exposure method. Then, the channel protective film 122 on the capacitor wiring 105 was removed by etching using this resist mask. Next, impurity regions 126 to 130 in which an impurity element imparting n-type conductivity was added to the crystalline silicon film 107 were formed by an ion doping method (or an ion implantation method). Impurity regions 126 to 130 have 1 × 10 ²⁰ ~ 1x10 ^{twenty one} cm ^-3 In this case, 5 × 10 ²⁰ cm ^-3 Impurity elements were included at a concentration of. This concentration is referred to herein as (n ⁺ ).
[0033]
(P ⁺ Region formation: FIG. 2 (B))
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 was performed. In the semiconductor technical field, boron (B), aluminum (Al), gallium (Ga), or the like is applied from the group 13 element of the periodic table to the impurity element imparting p-type. Here, boron (B) is used. Using. A mask 131 was formed so as to be positioned on the inner side of the channel protective film 119, and all regions where n-channel TFTs were formed were covered with resist masks 132 and 133. And diborane (B ₂ H ₆ The impurity regions 134 to 136 are formed by an ion doping method using ion) (an ion implantation method may be used). Impurity regions 135a, 135b, 136a, and 136b are doped with an impurity element from the surface of the crystalline silicon film, and the boron (B) concentration in these regions is 1.5 × 10 5. ²⁰ ~ 3x10 ^{twenty one} cm ^-3 Where 2 × 10 ^{twenty one} cm ^-3 It was. In this specification, the concentration of the impurity element imparting p-type contained in the impurity regions 135a, 135b, 136a, and 136b formed here (p ⁺ ). On the other hand, since the impurity region 134 has an impurity element added to the crystalline silicon film through the channel protective film 119, the boron (B) concentration in this region is 1 × 10. ¹⁶ ~ 1x10 ¹⁸ cm ^-3 It became. In this specification, the concentration of the impurity element imparting p-type contained in the impurity region 134 formed here is defined as (p ^- ).
[0034]
As shown in FIGS. 1B to 2A, since phosphorus (P) is added to the impurity regions 135b and 136b in the previous step, boron (B) and phosphorus (P) are added. A mixed region is formed, but by increasing the boron (B) concentration added in this step to 1.5 to 3 times that, p-type conductivity is ensured, and this has no influence on the TFT characteristics. There wasn't. In this specification, this region is referred to as an impurity region (B). The impurity regions 135a and 136a on the channel formation region side of the impurity regions (B) 135b and 136b are regions containing only boron (B), and this region is referred to as an impurity region (A) in this specification. The impurity region 134 that overlaps with the gate electrode 103 and also overlaps with the channel protective film 120 is formed as a region containing only boron (B), and this region functions as an LDD region.
[0035]
(Formation of first interlayer insulating film, thermal activation process, hydrogenation process: FIG. 2C)
After each impurity element is selectively added to the crystalline silicon film, the crystalline silicon film is etched to be divided into islands, and a protective insulating film 137 that later becomes a part of the first interlayer insulating film is formed. . The protective insulating film 137 may be formed using a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or a stacked film including a combination thereof. The film thickness may be 100 to 400 nm.
[0036]
Thereafter, a heat treatment process was 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, a rapid thermal annealing method (RTA method), or the like. Here, the activation process was performed by furnace annealing. The heat treatment was performed in a nitrogen atmosphere at 300 to 650 ° C., preferably 500 to 550 ° C., here at 525 ° C. for 4 hours. Further, a process of hydrogenating the active layer was performed by performing heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen. This step is a step of terminating dangling bonds in the active layer with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.
[0037]
When the crystalline silicon film 107 serving as an active layer is formed from an amorphous silicon film by a crystallization method using a catalytic element, the crystalline silicon film 107 has approximately 1 × 10 × 10. ¹⁷ ~ 5x10 ¹⁹ cm ^-3 Of catalytic element remained. Of course, there is no problem in completing and operating the TFT even in such a state, but it is more preferable to remove the remaining catalyst element from at least the channel formation region. As one of means for removing the catalyst element, there is a means for utilizing the gettering action by phosphorus (P). The concentration of phosphorus (P) necessary for gettering is the impurity region (n) formed in FIG. ⁺ ) And the catalytic element from the channel formation region of the n-channel TFT and the p-channel TFT to the peripheral impurity region to which phosphorus (P) is added by the heat treatment in the activation process performed here. Was able to gettering. As a result, the catalyst element concentration in the channel formation region is 5 × 10 5. ¹⁷ cm ^-3 And the impurity region has 1 × 10 10 ¹⁸ ~ 5x10 ²⁰ cm ^-3 The catalyst element segregated.
[0038]
(Formation of interlayer insulating film, formation of source / drain wiring, formation of passivation film, formation of pixel electrode: FIG. 3)
After the activation process, an interlayer insulating film 138 having a thickness of 500 to 1500 nm was formed on the protective insulating film 137. A laminated film composed of the protective insulating film 137 and the interlayer insulating film 138 was used as a first interlayer insulating film. Thereafter, contact holes reaching the source region or drain region of each TFT were formed, and source wirings 139 to 141 and drain wirings 142 and 143 were formed. 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.
[0039]
The protective insulating film 137 and the interlayer insulating film 138 may be formed of a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or the like, but in any case, it is preferable to set the internal stress of the film as a compressive stress.
[0040]
Next, a passivation film 144 was formed to a thickness of 50 to 500 nm (typically 100 to 300 nm) using a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film. Thereafter, when the hydrogenation treatment was performed in this state, a favorable result was 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 144 at a position where a contact hole for connecting the pixel electrode and the drain wiring is formed later.
[0041]
Thereafter, a second interlayer insulating film 145 made of an organic resin film was formed to a thickness of about 1 μm. As an applicable organic resin material, polyimide, acrylic, polyamide, polyimide amide, BCB (benzocyclobutene), or the like can be used. Here, it was formed by baking at 300 ° C. using a type of polyimide that is thermally polymerized after being applied to the substrate. A contact hole reaching the drain wiring 143 was formed in the second interlayer insulating film 145 and the passivation film 144, and a pixel electrode 146 was provided. As the pixel electrode 146, a transparent conductive film is used when a transmissive liquid crystal display device is used, and a metal film may be used when a reflective liquid crystal display device is used. Here, in order to obtain a transmissive liquid crystal display device, an indium tin oxide (ITO) film was formed to a thickness of 100 nm by sputtering. The pixel electrode 190 is an electrode of an adjacent pixel.
[0042]
Through the above steps, the pixel TFT in the display area and the TFT of the drive circuit provided around the display area can be formed on the same substrate. In the driving circuit, an n-channel TFT 168 and a p-channel TFT 167 are formed, and a logic circuit based on a CMOS circuit can be formed. The pixel TFT 169 is an n-channel TFT, and a storage capacitor 170 is connected to the pixel TFT 169 from the capacitor wiring 105, the semiconductor layer 166, and an insulating film formed therebetween.
[0043]
The p-channel TFT 167 of the driver circuit includes a channel formation region 147, source regions 150a and 150b, drain regions 151a and 151b, and LDD regions 148 and 149. The source region 150b and the drain region 151b are formed of an impurity region (B), and the boron (B) concentration in this region is 1.5 to 3 times the phosphorus (P) concentration. The source region 150a and the drain region 151a formed inside the impurity region (B), that is, on the channel formation region 147 side are the impurity regions (A), and boron (B) is the same concentration as the impurity regions (B). It is an area to include. In addition, LDD regions 148 and 149 which overlap with the gate electrode 103 and also overlap with the channel protective film 120 are formed as regions containing only boron (B). In this way, by separating the impurity region (B) from the channel formation region, the channel formation region and the LDD region in contact with the channel formation region, and the junction formation between the LDD region and the source region or drain region can be ensured. It was possible to maintain good characteristics.
[0044]
The n-channel TFT 168 of the driver circuit has a channel formation region 152, a source region 155 and a drain region 156, and LDD regions 153 and 154. The pixel TFT 169 includes channel formation regions 157 and 158, source or drain regions 163 to 165, and LDD regions 159 to 162. The LDD region of the n-channel TFT of the drive circuit is provided mainly for the purpose of relaxing the high electric field in the vicinity of the drain and preventing the deterioration of the on-current value due to hot carrier injection. Impurity element concentration to be applied is 5 × 10 ¹⁷ ~ 5x10 ¹⁸ cm ^-3 I should have done it. On the other hand, the LDD region of the pixel TFT is provided mainly for the purpose of reducing the off-current value, and the concentration of the impurity element may be the same as the concentration of the LDD region of the n-channel TFT of the driver circuit. The density may be ½ to 1/10. In FIG. 3, the pixel TFT 169 is completed as a double gate structure, but it may be a single gate structure or a multi-gate structure provided with a plurality of gate electrodes.
[0045]
As described above, the present invention can optimize the structure of TFTs constituting each circuit in accordance with specifications required by the pixel TFT and the drive circuit, and can improve the operation performance and reliability of the semiconductor device. did it.
[0046]
[Example 2]
This embodiment will be described with reference to FIG. 4 as an example in which a storage capacitor connected to the pixel TFT has a structure different from that of the first embodiment. The p-channel TFT 167, the n-channel TFT 168, and the pixel TFT 169 of the driver circuit were manufactured in the same manner as in Example 1. Hereinafter, differences from the first embodiment will be described.
[0047]
A light shielding film 171 is formed on the second interlayer insulating film 145 at least on the pixel TFT. The light-shielding film 171 is a film mainly containing one or more elements selected from Al, Ti, and Ta. The light-shielding film 171 is formed to a thickness of 100 to 300 nm and is patterned into a predetermined shape. Further, a third interlayer insulating film 172 was formed thereon using an organic resin film in the same manner as the second interlayer insulating film. The thickness of the third interlayer insulating film 172 was set to 0.5 to 1 μm. Then, a contact hole reaching the drain wiring 143 was formed in the third interlayer insulating film 172, the second interlayer insulating film 145, and the passivation film 144, and the pixel electrode 173 was provided. The pixel electrode 173 may be a transparent conductive film in the case of a transmissive liquid crystal display device, and a metal film in the case of a reflective liquid crystal display device. Here, in order to obtain a transmissive liquid crystal display device, an indium tin oxide (ITO) film was formed to a thickness of 100 nm by sputtering. In this manner, the storage capacitor 174 connected to the pixel TFT 169 can be formed from the light shielding film 171, the third interlayer insulating film 172, and the pixel electrode 173.
[0048]
[Example 3]
In this embodiment, a process of forming a crystalline semiconductor film which becomes an active layer of the TFT shown in Embodiments 1 and 2 will be described with reference to FIG. First, gate electrodes 1102 and 1103 having a thickness of 100 to 400 nm are formed on a substrate (a glass substrate in this embodiment) 1101. The gate electrode is formed from a material containing one or more elements selected from Al, Ti, Ta, Mo, and W, and is patterned to have a tapered end surface. Although not shown, a laminated structure of the materials may be used. For example, a two-layer structure of tantalum nitride (TaN) and Ta may be used from the substrate side. Further, an oxide may be coated on the surface of the gate electrode by an anodic oxidation method or the like. The gate insulating film 1104 is formed using a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film, and has a thickness of 20 to 200 nm, preferably 75 to 125 nm. Then, an amorphous semiconductor film (amorphous silicon film in this embodiment) 1105 having a thickness of 50 nm is continuously formed on the gate insulating film 1104 without being released to the atmosphere.
[0049]
Next, an aqueous solution (nickel acetate aqueous solution) containing 10 ppm of catalyst element (nickel in this embodiment) in terms of weight is applied by spin coating to form the catalyst element-containing layer 1106 over the entire surface of the amorphous semiconductor film 1105. To do. In addition to nickel (Ni), usable catalyst elements include germanium (Ge), iron (Fe), palladium (Pd), tin (Sn), lead (Pb), cobalt (Co), platinum (Pt). ), Copper (Cu), and gold (Au). In this embodiment, a method of adding nickel by a spin coating method was used. However, a thin film made of a catalytic element (a nickel film in this embodiment) is deposited on an amorphous semiconductor film by an evaporation method or a sputtering method. You may take the means to form. (Fig. 5 (A))
[0050]
Next, a heat treatment step is performed at 400 to 500 ° C. for about 1 hour before crystallization to desorb hydrogen from the film, and then at 500 to 650 ° C. (preferably 550 to 570 ° C.) for 4 to 12 hours. Heat treatment is performed (preferably 4 to 6 hours). In this embodiment, heat treatment is performed at 550 ° C. for 4 hours to form a crystalline semiconductor film (crystalline silicon film in this embodiment) 1107. (Fig. 5 (B))
[0051]
The active layer 1107 formed as described above can form a crystalline semiconductor film with excellent crystallinity by using a catalyst element (here, nickel) that promotes crystallization. In order to further improve the crystallinity, a laser crystallization method may be used in combination. For example, a linear beam is formed using XeF excimer laser light (wavelength 308 nm), and the oscillation frequency is 5 to 50 Hz and the energy density is 100 to 500 mJ / cm. ² As shown in FIG. 5B, the linear semiconductor overlap ratio of 80 to 98% was applied to the crystalline semiconductor film 1107 manufactured in FIG. As a result, a crystalline semiconductor film 1108 with further excellent crystallinity could be formed. (Fig. 5 (C))
[0052]
When a crystalline semiconductor film manufactured over the substrate 1101 in this way is used to manufacture a TFT according to the procedure shown in Embodiments 1 and 2, good characteristics can be obtained. The characteristics of a TFT can be typically represented by field effect mobility, but the characteristics of a TFT formed from a crystalline semiconductor film manufactured as in this embodiment are 150 to 220 cm for an n-channel TFT. ² / V · sec, 90-120cm for p-channel TFT ² / V · sec was obtained, and even when operated continuously, characteristic deterioration from the initial value was hardly observed, and excellent characteristics were obtained from the viewpoint of reliability.
[0053]
[Example 4]
In this embodiment, another structure of the storage capacitor connected to the pixel TFT will be described with reference to FIGS. Here, the manufacturing steps of FIGS. 6 and 7 are the same as the step of forming the second interlayer insulating film 145 made of an organic resin film in accordance with the manufacturing steps described in the first embodiment. It has already been described with reference to FIGS. Therefore, in the present embodiment, the description will be made by paying attention only to differences from the first embodiment.
[0054]
6A, first, after forming the second interlayer insulating film 145 according to the steps of Embodiment 1, a light shielding film 301 is formed with a material containing an element selected from Al, Ta, and Ti. Then, a dielectric film 302 (an oxide of a material for forming the light shielding film) having a thickness of 30 to 150 nm (preferably 50 to 75 nm) is formed on the surface of the light shielding film 301 by an anodic oxidation method.
[0055]
When forming the dielectric film 302 by the anodic oxidation method, an ethylene glycol tartrate solution having a sufficiently low alkali ion concentration was first prepared. This was a solution in which 15% ammonium tartrate aqueous solution and ethylene glycol were mixed at a ratio of 2: 8, and aqueous ammonia was added thereto to adjust the pH to 7 ± 0.5. Then, a platinum electrode serving as a cathode is provided in the solution, the substrate on which the light shielding film 301 is formed is immersed in the solution, and a constant (several mA to several tens mA) direct current is passed using the light shielding film 301 as an anode. . The voltage between the cathode and the anode in the solution changes with time as the oxide grows, but the voltage is adjusted so that the current becomes constant, and when the voltage reaches 150 V, the voltage is not maintained or The anodizing treatment was terminated by setting the holding time to several seconds to several tens of seconds. Thus, the light shielding film 301 can be formed without causing the dielectric film to reach the surface in contact with the second interlayer insulating film.
[0056]
Although the dielectric film is provided only on the surface of the light shielding film here, the dielectric film may be formed by a vapor phase method such as a plasma CVD method, a thermal CVD method, or a sputtering method. In that case also, the film thickness is preferably 30 to 150 nm (preferably 50 to 75 nm). Alternatively, a silicon oxide film, a silicon nitride film, a silicon nitride oxide film, a DLC (Diamond like carbon) film, or an organic resin film may be used. Further, a laminated film combining these may be used.
[0057]
Thereafter, the pixel electrode 303 is formed as in the first embodiment. Thus, the storage capacitor 304 is formed in the region where the light shielding film 301 and the pixel electrode 303 overlap with each other with the dielectric film 302 interposed therebetween.
[0058]
In the structure of FIG. 6B, a light shielding film 301 and a dielectric film 302 are formed as in FIG. 6A, and then a spacer 305 made of an organic resin is formed. As the organic resin film, a film selected from polyimide, polyamide, polyimide amide, acrylic, and BCB (benzocyclobutene) can be used. After that, the spacer 305, the second interlayer insulating film 145, and the passivation film 143 are etched to form contact holes, and the pixel electrode 306 is formed using the same material as that in the first embodiment. Thus, the storage capacitor 307 is formed in a region where the light shielding film 301 and the pixel electrode 306 overlap with each other with the dielectric film 302 interposed therebetween. By providing the spacer 305 in this manner, a short circuit that occurs between the light shielding film 301 and the pixel electrode 306 can be prevented.
[0059]
In the structure of FIG. 6C, a light shielding film 301 is formed as in FIG. 6A, and a spacer 308 made of an organic resin is formed so as to cover an end portion of the light shielding film 301. As the organic resin, a film selected from polyimide, polyamide, polyimide amide, acrylic, and BCB (benzocyclobutene) can be used. Next, a dielectric film 309 is formed on the exposed surface of the light shielding film 301 by anodic oxidation. Note that a dielectric film is not formed on a portion in contact with the spacer 308. Then, the spacer 308, the second interlayer insulating film 145, and the passivation film 143 are etched to form a contact hole, and the pixel electrode 310 is formed using the same material as that of the first embodiment. Thus, the storage capacitor 311 is formed in a region where the light shielding film 301 and the pixel electrode 310 overlap with each other with the dielectric film 309 interposed therebetween. By providing the spacer 308 in this manner, a short circuit that occurs between the light shielding film 301 and the pixel electrode 310 can be prevented.
[0060]
In FIG. 7A, first, the second interlayer insulating film 145 is formed in accordance with the steps of Embodiment 1, and then the insulating film 312 is formed thereon with a material such as a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film. . The insulating film 312 is formed by a known film formation method, and among these, it is preferable to use a sputtering method. Thereafter, similarly to FIG. 6A, a light-shielding film, a dielectric film, and a pixel electrode are formed, and the storage capacitor 313 is provided. By providing the insulating film 312, the adhesion of the light shielding film to the base is improved, and when the dielectric film is formed by the anodic oxidation method, the formation of the dielectric film around the interface with the base of the light shielding film is prevented. it can.
[0061]
In FIG. 7B, similarly, after forming the insulating film and the light shielding film, a region of the insulating film that is not in close contact with the light shielding film is removed by etching, and the insulating film 314 is formed so as to overlap the light shielding film. A pixel electrode 315 is provided. With this configuration, the adhesion of the light shielding film to the base is improved, and when the dielectric film is formed by the anodic oxidation method, the dielectric film wraps around the interface with the base of the light shielding film. In addition, the light transmittance of the pixel region where the light shielding film is formed can be improved.
[0062]
The structure shown in FIGS. 7A and 7B can be combined with the structure provided with the spacers shown in FIGS. 6B and 6C. Further, the configuration of this embodiment shown in FIGS. 6 and 7 can be combined with the configuration of Embodiment 1 or Embodiment 2.
[0063]
[Example 5]
In the method for manufacturing a semiconductor device in which the pixel TFT formed in the display region and the driver circuit TFT provided in the periphery of the display region described in Example 1 and Example 2 are provided over the same substrate, a crystal serving as an active layer A conductive semiconductor film, an insulating film such as a gate insulating film, an interlayer insulating film, and a base film, and a conductive film such as a gate electrode, a source wiring, a drain wiring, and a pixel electrode can all be formed by sputtering. The advantage of using the sputtering method is suitable for forming a uniform film over a large-area substrate because a DC (direct current) discharge method can be adopted in forming a conductive film or the like. In addition, it is not necessary to use silane (SiH4), which requires great care when forming a silicon-based material such as an amorphous silicon film or a silicon nitride film, and the safety of work is ensured. Such a point can be utilized as a very merit in the production site. Hereinafter, a manufacturing process using the sputtering method will be described according to the first embodiment.
[0064]
The gate electrodes 102 to 104 and the capacitor wiring 105 in FIG. 1A can be easily formed by a known sputtering method using a target material such as Ta, Ti, W, or Mo. When a compound material such as W-Mo or Ta-Mo is used, a compound target may be used similarly. Further, when forming TaN or WN, nitrogen (N) in addition to argon (Ar) in the sputtering atmosphere. ₂ ) And ammonia (NH _Three ) Can be prepared by appropriate addition. In addition, there is a method in which helium (He), krypton (Kr), or xenon (Xe) is added to the sputtering gas in addition to Ar to control the internal stress of the coating film to be produced.
[0065]
As the silicon nitride film 106a used for the gate insulating film 106, a silicon (Si) target is used, and Ar, N ₂ , Hydrogen (H ₂ ), NH _Three It can be formed by mixing properly. Alternatively, a similar material can be formed using a silicon nitride target material. The silicon nitride oxide film 106b uses an Si, Ar, N ₂ , H ₂ , N ₂ It is produced by mixing O with appropriate mixing and sputtering.
[0066]
Similarly, the amorphous silicon film uses a Si target and Ar, H ₂ Is used as a sputtering gas. Further, when it is desired to add a small amount of boron (B) to the amorphous silicon film, several tens to several thousand ppm of boron (B) may be added to the target in advance, or sputtering gas may be added. Diborane (B ₂ H ₆ ) Can also be added.
[0067]
Silicon oxide films applicable to the channel protective films 119 to 122 can be manufactured by sputtering with silicon oxide (or quartz) as a target material and using a mixed gas of Ar or Ar and oxygen (O2). The silicon nitride film, the silicon oxide film, and the silicon nitride oxide film used for the protective insulating film 137, the interlayer insulating film 138, and the passivation film 144 may be formed as described above.
[0068]
In the case where Al is used in the source wirings 139 to 141 and the drain wirings 142 and 143, the inclusion of about 0.01 to 5% by weight of Ti, Si, scandium (Sc), vanadium (V), Cu or the like causes hillocks. It is effective for prevention. Ti, Ta, Al, etc. used for the light shielding film 171, ITO, ZnO, SnO used for the pixel electrode 146 ₂ Any of these may be formed by a known sputtering method.
[0069]
As described above, films other than the second interlayer insulating film 145 and the third interlayer insulating film 172 made of an organic resin can be formed by sputtering. The detailed experimental conditions may be determined by the practitioner.
[0070]
[Example 6]
In this embodiment, a pixel TFT and a TFT of a driver circuit, particularly, another example of a p-channel TFT will be described. First, the steps from FIG. 1A to FIG. 2A described in the first embodiment are performed in the same manner. FIG. 12A corresponds to FIG. 2A and shows a state where resist masks 1123 to 1125 and impurity regions 1126 to 1130 to which an impurity element imparting n-type conductivity is added are formed.
[0071]
Then, as shown in FIG. ⁺ Region formation is performed. A mask 1131 was formed so as to be positioned on the inner side of the channel protective film 1119, and all regions where n-channel TFTs were formed were covered with resist masks 1132 and 1133. Further, a channel protection insulating film 1119b having a new shape is formed by wet etching using a hydrofluoric acid-based solution so that the end of the channel protection film 1119 substantially matches the end of the mask 1131. . And diborane (B ₂ H ₆ The high-concentration impurity regions 1134 to 1136 are formed by an ion doping method using () (an ion implantation method may be used). Impurity regions 1134 to 1136 are doped with an impurity element from the surface of the crystalline silicon film, and the boron (B) concentration in this region is 1.5 × 10 5. ²⁰ ~ 3x10 ^{twenty one} cm ^-3 Where 2 × 10 ^{twenty one} cm ^-3 It was. In this specification, the concentration of the impurity element imparting p-type contained in the impurity regions 1134 to 1136 formed here is defined as (p ⁺ ). In this manner, by providing the end portion in contact with the channel formation region of the high-concentration impurity region of the p-channel TFT on the channel formation region side from the end portions of the low-concentration impurity regions 1113 and 1114 formed in the previous step, The joining state in this part can be made favorable.
[0072]
As shown in FIGS. 1B to 2A, since phosphorus (P) is added to the impurity regions 1135 and 1136 in the previous step, boron (B) and phosphorus (P) are added. A mixed region is formed, but by increasing the boron (B) concentration added in this step to 1.5 to 3 times that, p-type conductivity is ensured, and this has no influence on the TFT characteristics. There wasn't. In this specification, this region is referred to as a region (B). The impurity region 134 on the channel formation region side includes only boron (B), and this region is referred to as a region (A) in this specification.
[0073]
After each impurity element is selectively added to the crystalline silicon film, the crystalline silicon film is etched to be divided into islands, and a protective insulating film 1137 that later becomes a part of the first interlayer insulating film is formed. . The protective insulating film 1137 may be formed using a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or a stacked film including a combination thereof. The film thickness may be 100 to 400 nm.
[0074]
Thereafter, a heat treatment process was performed to activate the impurity element imparting n-type or p-type added at each concentration. In the case of activation by the furnace annealing method, heat treatment was performed in a nitrogen atmosphere at 300 to 650 ° C., preferably 500 to 550 ° C., here 525 ° C. for 4 hours. When laser annealing is applied, an excimer laser is used as a light source, and the laser beam is converted into a linear beam with a line width of 100 to 500 μm by an optical system. ), Irradiation is performed at an energy density of 100 to 500 mJ / cm 2. Further, a process of hydrogenating the active layer was performed by performing heat treatment at 300 to 450 ° C. for 1 to 12 hours in an atmosphere containing 3 to 100% hydrogen. This step is a step of terminating dangling bonds in the active layer with thermally excited hydrogen. As another means of hydrogenation, plasma hydrogenation (using hydrogen excited by plasma) may be performed.
[0075]
After the activation process, an interlayer insulating film 1138 having a thickness of 500 to 1500 nm was formed on the protective insulating film 1137. A laminated film composed of the protective insulating film 1137 and the interlayer insulating film 1138 was used as a first interlayer insulating film. Thereafter, contact holes reaching the source region or the drain region of each TFT were formed, and source wirings 1139 to 1141 and drain wirings 1142 and 1143 were formed. 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.
[0076]
The protective insulating film 1137 and the interlayer insulating film 1138 may be formed of a silicon nitride film, a silicon oxide film, a silicon nitride oxide film, or the like. In any case, it is preferable to set the internal stress of the film as a compressive stress.
[0077]
Next, a passivation film 1144 was formed to a thickness of 50 to 500 nm (typically 100 to 300 nm) using a silicon nitride film, a silicon oxide film, or a silicon nitride oxide film. Thereafter, when the hydrogenation treatment was performed in this state, a favorable result was 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 1144 at a position where a contact hole for connecting the pixel electrode and the drain wiring is formed later.
[0078]
Thereafter, as in Example 1, a second interlayer insulating film 1145 made of an organic resin film was formed to a thickness of about 1 μm. A contact hole reaching the drain wiring 1143 was formed in the second interlayer insulating film 1145 and the passivation film 1144, and a pixel electrode 1146 was provided. The pixel electrode 1146 may be a transparent conductive film in the case of a transmissive liquid crystal display device, and a metal film in the case of a reflective liquid crystal display device. Here, in order to obtain a transmissive liquid crystal display device, an indium tin oxide (ITO) film was formed to a thickness of 100 nm by sputtering. The pixel electrode 1190 is an electrode of an adjacent pixel.
[0079]
Through the above steps, the pixel TFT in the display area and the TFT of the drive circuit provided around the display area can be formed on the same substrate. In the driving circuit, an n-channel TFT 1168 and a p-channel TFT 1167 are formed, and a logic circuit based on a CMOS circuit can be formed. The pixel TFT 1169 is an n-channel TFT, and a storage capacitor 1170 is connected to the pixel TFT 1169 from the capacitor wiring 105, the semiconductor layer 1166, and an insulating film formed therebetween.
[0080]
A p-channel TFT 1167 of the driver circuit includes a channel formation region 1147, source regions 1148 and 1150 formed of high-concentration impurity regions, and drain regions 1149 and 1151. The source region 1150 and the drain region 1151 are formed of a region (B), and the boron (B) concentration in this region is 1.5 to 3 times the phosphorus (P) concentration. A source region 1148 and a drain region 1149 formed on the inner side of the impurity region (B), that is, on the channel formation region 1147 side are regions (A), and regions containing only boron (B) at the same concentration as the region (B). It is. This region (A) has a structure that entirely overlaps with the gate electrode 1103, while the region (B) partially overlaps with the gate electrode 1103. As described above, the high concentration impurity region of the p-channel TFT is formed from the region (B) and the region (A), and the region (B) is separated from the channel formation region, whereby the channel formation region, the high concentration impurity region, The bonding can be made excellent.
[0081]
The n-channel TFT 1168 of the driver circuit includes a channel formation region 1152, a source region 1155 and a drain region 1156, and LDD regions 1153 and 1154. The pixel TFT 1169 includes channel formation regions 1157 and 1158, source or drain regions 1163 to 1165, and LDD regions 1159 to 1162. The LDD region of the n-channel TFT of the drive circuit is provided mainly for the purpose of relaxing the high electric field in the vicinity of the drain and preventing the deterioration of the on-current value due to hot carrier injection. Impurity element concentration to be applied is 5 × 10 ¹⁷ ~ 5x10 ¹⁸ cm ^-3 I should have done it. On the other hand, the LDD region of the pixel TFT is provided mainly for the purpose of reducing the off-current value, and the concentration of the impurity element may be the same as the concentration of the LDD region of the n-channel TFT of the driver circuit. The density may be ½ to 1/10. In FIG. 3, the pixel TFT 1169 is completed as a double gate structure, but it may be a single gate structure or a multi-gate structure provided with a plurality of gate electrodes.
[0082]
In the TFT manufactured through the above steps, the channel protection insulating films 1119b and 1120 to 1122 are formed without being damaged by an ion doping method or the like, and thus the TFT characteristics may be stabilized. it can. For example, as a bias / thermal stress (BTS) test, even when a voltage of −1.7 MV is applied to the gate electrode and left at 150 ° C. for 1 hour, the threshold voltage, field effect mobility, subthreshold Fluctuations such as constants and on-current values are hardly observed. Furthermore, according to the present invention, the structure of the TFT constituting each circuit can be optimized according to the specifications required by the pixel TFT and the drive circuit, and the operation performance and reliability of the semiconductor device can be improved.
[0083]
Further, the storage capacitor shown in FIG. 13 has a light shielding film, a dielectric layer formed on the surface thereof by an anodic oxidation method, a pixel electrode, as described in Embodiment 4 with reference to FIGS. You may form from.
[0084]
[Example 7]
In this example, a process of manufacturing an active matrix liquid crystal display device from a substrate on which a pixel TFT and a driving circuit are formed will be described. As shown in FIG. 8, an alignment film 601 is formed on the substrate in the state of FIG. Usually, a polyimide resin is often used for the alignment film of the liquid crystal display element. A light shielding film 603, a transparent conductive film 604, and an alignment film 605 are formed on the opposite substrate 602. After the alignment film was formed, rubbing treatment was performed so that the liquid crystal molecules were aligned with a certain pretilt angle. Then, the one substrate on which the pixel TFT and the drive circuit are formed and the counter substrate are bonded to each other through a sealing material, a spacer (both not shown), and the like by a known cell assembling process. Thereafter, a liquid crystal material 606 was injected between both substrates and completely sealed with a sealant (not shown). A known liquid crystal material may be used as the liquid crystal material. In this way, the active matrix liquid crystal display device shown in FIG. 8 is completed.
[0085]
Next, the configuration of the active matrix liquid crystal display device will be described with reference to the perspective view of FIG. 9 and the top view of FIG. 9 and 10 use the same reference numerals in order to correspond to the cross-sectional structure diagrams of FIGS. 1 to 3 and FIG. 10 corresponds to the sectional view of the pixel TFT 169 and the storage capacitor 170 shown in FIG.
[0086]
The perspective view shown in FIG. 9 includes a display region 701, a scanning (gate) line driving circuit 702, and a signal (source) line driving circuit 703 formed on the glass substrate 101. A pixel TFT 169 is provided in the display area, and a drive circuit provided in the periphery of the display area is configured based on a CMOS circuit. The scanning (gate) line driving circuit 702 and the signal (source) line driving circuit 703 are respectively connected to the gate wiring 104 (represented by the same reference numerals in the sense of being connected to the gate electrode and extending) and the source wiring 141. To the pixel TFT in the display area 701. Further, the FPC 731 is connected to the external input / output terminal 734.
[0087]
FIG. 10 is a top view showing almost one pixel in the display area 701. The gate wiring 104 intersects with the active layer thereunder via a gate insulating film (not shown). Although not shown, the active layer includes a source region, a drain region, n ^- An LDD region composed of regions is formed. Reference numeral 180 denotes a contact portion between the source wiring 141 and the source region 163, 181 denotes a contact portion between the drain wiring 143 and the drain region 165, and 182 denotes a contact portion between the drain wiring 143 and the pixel electrode 146. The storage capacitor 170 is formed in a region where the semiconductor layer 166 connected to the drain region 165 of the pixel TFT 169 overlaps with the capacitor wiring 105 and the insulating film formed therebetween.
[0088]
Although the active matrix liquid crystal display device of this embodiment has been described in light of the structure described in the first embodiment, the active matrix liquid crystal display device can be freely combined with any of the configurations of the first to sixth embodiments. Can be produced.
[0089]
[Example 8]
Substrates in which pixel TFTs and drive circuits manufactured by implementing the present invention are integrally formed on the same substrate are various electro-optical devices (active matrix liquid crystal display devices, active matrix EL display devices, active matrix EC devices). Display device). That is, the present invention can be implemented in all electronic devices in which these electro-optical devices are incorporated as display media.
[0090]
Examples of such electronic devices include a video camera, a digital camera, a projector (rear type or front type), a head mounted display (goggles type display), a car navigation system, a personal computer, a mobile phone, or an electronic book. An example of them is shown in FIG.
[0091]
FIG. 11A illustrates a mobile phone, which includes a main body 9001, an audio output portion 9002, an audio input portion 9003, a display device 9004, operation switches 9005, and an antenna 9006. The present invention can be applied to the audio output unit 9002, the audio input unit 9003, and an active matrix display device 9004 provided with a drive circuit in the display area and its periphery.
[0092]
FIG. 11B illustrates a video camera which includes a main body 9101, a display device 9102, an audio input portion 9103, operation switches 9104, a battery 9105, and an image receiving portion 9106. The present invention can be applied to the voice input portion 9103, the active matrix display device 9102 and the image receiving portion 9106 each having a display area and a drive circuit in the periphery thereof.
[0093]
FIG. 11C illustrates a mobile computer, which includes a main body 9201, a camera portion 9202, an image receiving portion 9203, operation switches 9204, and a display device 9205. The present invention can be applied to the image receiving portion 9203 and an active matrix display device 9205 provided with a drive circuit in the display area and its periphery.
[0094]
FIG. 11D illustrates a goggle type display which includes a main body 9301, a display device 9302, and an arm portion 9303. The present invention can be applied to an active matrix display device 9302 provided with a drive circuit in the display area and its periphery. Although not shown, it can also be used for other signal control circuits.
[0095]
FIG. 11E illustrates a rear projector, which includes a main body 9401, a light source 9402, a display device 9403, a polarizing beam splitter 9404, reflectors 9405 and 9406, and a screen 9407. The present invention can be applied to an active matrix display device 9403 provided with a driver circuit in and around the display region.
[0096]
FIG. 11F illustrates a portable book which includes a main body 9501, display devices 9502 and 9503, a storage medium 9504, operation switches 9505, and an antenna 9506, and is stored in a mini disc (MD) or a digital video disc (DVD). Displayed data and data received by an antenna are displayed. The display devices 9502 and 9503 are active matrix direct-view display devices each including a display region and a driver circuit around the display region. The present invention can be applied to the display devices.
[0097]
Although not shown here, the present invention can also be applied to a display unit of a car navigation system or an image sensor personal computer. Thus, the applicable range of the present invention is extremely wide and can be applied to electronic devices in all fields. Moreover, the electronic apparatus of a present Example is realizable even if it uses the structure which consists of what combination of Examples 1-7.
[0098]
【The invention's effect】
By using the present invention, in a semiconductor device (specifically, an electro-optical device here) in which a plurality of functional circuits are formed on the same substrate, a TFT having appropriate performance according to the specifications required by the functional circuits Can be arranged, and its operating characteristics and reliability can be greatly improved.
[0099]
In particular, in a bottom gate type or inverted stagger type TFT provided with an LDD region, the LDD region of the pixel TFT is set to n. ^- By forming Loff at a concentration of 1%, it is possible to greatly reduce the off-current value and contribute to lower power consumption of the pixel TFT. In addition, the LDD region of the n-channel TFT of the drive circuit is set to ^- By forming Lov + Loff at a concentration of N, it is possible to increase current drive capability, prevent deterioration due to hot carriers, and reduce deterioration of the on-current value.
[0100]
Further, in the p-channel TFT of the driver circuit, an impurity region (B) including both an impurity element imparting p-type and an impurity element imparting n-type, and an impurity region including an impurity element imparting p-type ( A), and the impurity region (A) is formed between the impurity region (A) and the LDD region of the p-channel TFT of the driver circuit, thereby being in contact with the channel formation region. The junction formation between the LDD region and the LDD region and the source region or the drain region is ensured, and the characteristics of the p-channel TFT can be kept good.
[0101]
In addition, operation performance and reliability of a semiconductor device (specifically, an electronic device here) having such an electro-optical device as a display medium can be improved.
[Brief description of the drawings]
FIGS. 1A and 1B are diagrams illustrating a manufacturing process of a pixel TFT and a driver circuit TFT. FIGS.
FIGS. 2A and 2B are diagrams illustrating a manufacturing process of a pixel TFT and a TFT of a driver circuit. FIGS.
FIGS. 3A and 3B are diagrams illustrating a manufacturing process of a pixel TFT and a driver circuit TFT. FIGS.
FIGS. 4A and 4B are diagrams illustrating a manufacturing process of a pixel TFT and a driver circuit TFT; FIGS.
FIGS. 5A and 5B illustrate a manufacturing process of a crystalline semiconductor film. FIGS.
FIG. 6 illustrates an example of a cross-sectional structure of a storage capacitor.
FIG. 7 illustrates an example of a cross-sectional structure of a storage capacitor.
FIG. 8 illustrates a cross-sectional structure of an active matrix liquid crystal display device.
FIG. 9 is a perspective view of an active matrix liquid crystal display device.
FIG. 10 is a top view of a pixel.
FIG 11 illustrates an example of a semiconductor device.
FIGS. 12A to 12C are diagrams illustrating manufacturing steps of a pixel TFT and a TFT of a driver circuit. FIGS.
FIGS. 13A and 13B are diagrams illustrating manufacturing steps of a pixel TFT and a TFT of a driver circuit. FIGS.
[Explanation of symbols]
101 substrate
102 to 104 Gate electrode
105 capacitance wiring
106 Gate insulation film
107 crystalline silicon film
108 Mask insulation film
119 to 121 channel protective film
139-141 Source electrode
142-143 drain electrode
137 Protective insulating film
138 Interlayer insulation film
144 Passivation film
145 Second interlayer insulating film
146 Pixel electrode

Claims (7)

A TFT provided in the display region, and an n-channel TFT and a p-channel TFT of a drive circuit provided around the display region on the same substrate;
The p-channel TFT has a first gate electrode and a first semiconductor film,
The first semiconductor film includes a first channel formation region, a first impurity region not adjacent to the first channel formation region, a second impurity region adjacent to the first channel formation region, Have
The n-channel TFT has a second gate electrode and a second semiconductor film,
The second semiconductor film has a second channel formation region and a third impurity region,
The second impurity region is a method for manufacturing a semiconductor device having no impurity element added to the third impurity region,
Forming the first gate electrode and the second gate electrode on the substrate;
Forming a gate insulating film on the first gate electrode and the second gate electrode;
Forming the first semiconductor film on the first gate electrode via the gate insulating film, forming the second semiconductor film on the second gate electrode via the gate insulating film;
Forming a first insulating film on the first semiconductor film and the second semiconductor film;
On the first insulating film, said first mask is formed which is positioned inside the first gate electrode, on the first insulating film, the second located on the inner side of the second gate electrode Forming a mask of
Using the first mask and the second mask, an impurity element imparting the n-type is added at a first concentration to form the second channel formation region;
Using the first mask and the second mask, the first insulating film is etched, and the first channel protective film located inside the first mask and the second mask. Forming a second channel protective film located inside;
A third mask wider than the first channel protective film is formed on the first channel protective film and the first semiconductor film , and is formed on the second channel protective film and the second semiconductor film . Forming a fourth mask wider than the second gate electrode;
Using the third mask and the fourth mask, an impurity element imparting the n-type is added at a second concentration higher than the first concentration to form the third impurity region;
Forming a fifth mask located on the inner side of the first channel protective film on the first channel protective film , and forming a sixth mask on the whole of the second semiconductor film;
Using the first channel protective film, the fifth mask, and the sixth mask, an impurity element imparting p-type to the first semiconductor film is formed at a third concentration higher than the second concentration. A method for manufacturing a semiconductor device, wherein the first channel formation region, the first impurity region, and the second impurity region are formed by addition. In claim 1,
The first channel formation region is formed by adding an impurity element imparting the p-type to the first semiconductor film using the first channel protective film, the fifth mask, and the sixth mask. And the second impurity region is formed, whereby the first channel formation region is shorter in the channel length direction than the second channel formation region. A TFT provided in the display region, and an n-channel TFT and a p-channel TFT of a drive circuit provided around the display region on the same substrate;
The p-channel TFT has a first gate electrode and a first semiconductor film,
The first semiconductor film has a first channel formation region and a first impurity region adjacent to the first channel formation region,
The n-channel TFT has a second gate electrode and a second semiconductor film,
The second semiconductor film has a second channel formation region and a second impurity region,
The first impurity region is a method for manufacturing a semiconductor device having no impurity element added to the second impurity region,
Forming the first gate electrode and the second gate electrode on the substrate;
Forming a gate insulating film on the first gate electrode and the second gate electrode;
Forming the first semiconductor film on the first gate electrode via the gate insulating film, forming the second semiconductor film on the second gate electrode via the gate insulating film;
Forming a first insulating film on the first semiconductor film and the second semiconductor film;
On the first insulating film, said first mask is formed which is positioned inside the first gate electrode, on the first insulating film, the second located on the inner side of the second gate electrode Forming a mask of
Using the first mask and the second mask, an impurity element imparting the n-type is added at a first concentration to form the second channel formation region;
Using the first mask and the second mask, the first insulating film is etched, and the first channel protective film located inside the first mask and the second mask. Forming a second channel protective film located inside;
A third mask wider than the first channel protective film is formed on the first channel protective film and the first semiconductor film , and is formed on the second channel protective film and the second semiconductor film . Forming a fourth mask wider than the second gate electrode;
Using the third mask and the fourth mask, an impurity element imparting the n-type is added at a second concentration higher than the first concentration to form the second impurity region;
Forming a fifth mask located on the inner side of the first channel protective film on the first channel protective film , and forming a sixth mask on the whole of the second semiconductor film;
Etching the first channel protective film using the fifth mask to form a third channel protective film,
Using the third channel protective film, the fifth mask, and the sixth mask, an impurity element imparting p-type to the first semiconductor film is formed at a third concentration higher than the second concentration. A method for manufacturing a semiconductor device, wherein the first channel formation region and the first impurity region are formed by addition. In claim 3,
Using the third channel protective film, the fifth mask, and the sixth mask, the impurity element imparting the p-type is added to the first semiconductor film, and the first channel formation region And the first impurity region is formed, whereby the first channel formation region is shorter in the channel length direction than the second channel formation region. In any one of Claims 1 thru | or 4,
Forming capacitive wiring on the substrate;
Forming an insulating film on the capacitor wiring;
Forming a third semiconductor film on the insulating film to form a capacitor having the capacitor wiring, the insulating film, and the third semiconductor film;
The method for manufacturing a semiconductor device, wherein the capacitor is electrically connected to the TFT in the display region. In any one of Claims 1 thru | or 4,
Forming a light shielding film on the TFT in the display area;
Forming a dielectric film in contact with the light shielding film;
The display area said to form a pixel electrode electrically connected to the T FT of as the light shielding film to partially overlap the light shielding film to form a capacitor having a dielectric layer, and the pixel electrode,
The method for manufacturing a semiconductor device, wherein the capacitor is electrically connected to the TFT in the display region. In claim 6,
The light shielding film is formed of a material including one or more selected from aluminum, tantalum, and titanium,
The method for manufacturing a semiconductor device, wherein the dielectric film is formed of an oxide of a material for forming the light shielding film.

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