JP3276900B2 - Semiconductor device and display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film transistor (TFT) used for an active matrix type display device such as a semiconductor device, in particular, a liquid crystal display (LCD) and an electroluminescence (EL) display.
The present invention relates to a method of manufacturing a peripheral drive circuit integrated display in which an in-film tansistor is formed as a switching element in a display portion and a drive circuit is formed in a peripheral portion.

[0002]

2. Description of the Related Art A flat display device comprising a display element using liquid crystal or organic electroluminescence (EL) as an optical member has advantages of small size, thin shape, low power consumption, and the like, and is used in the field of OA equipment, AV equipment and the like. Is being put to practical use. In these LCD and organic EL display devices, an active matrix type in which a TFT is formed on a substrate supporting a liquid crystal or EL is used as a switching element for controlling the timing of holding and rewriting image information of each display element. It has become mainstream because of its goodness. Among them,
A built-in driver has been developed that forms the TFT not only as a switching element for the display element but also around the display element group to constitute a peripheral driver for driving the display element, realizing further miniaturization and lower cost. are doing.

[0003] TF used in a display device with a built-in driver
As T, a polycrystalline semiconductor, particularly polysilicon (p-Si) was used for the channel layer because of the operation speed applicable to a driver and the low film formation temperature that can be formed on an inexpensive glass substrate having low heat resistance. Things are suitable. In forming polysilicon, by performing laser annealing on amorphous silicon formed on the substrate, crystallization can be performed while suppressing the temperature of the supporting substrate to 400 to 600 ° C., and p-Si thus obtained is used. By a method of forming a TFT, a driver circuit can be formed on a non-alkali glass substrate.

FIG. 4 is a configuration diagram of a laser annealing apparatus for performing such laser annealing. (5
1) is an oscillation source for generating a pulse laser, and (52) is
An optical system including a lens (55) and a mirror (56);
3) is a final irradiation part, and (54) is a substrate to be processed (5) inside.
9) A processing chamber equipped with a stage (58) for supporting the same. Laser light such as an excimer laser generated in the laser oscillation source (51) is sent to the optical system (52). In the optical system (52), various lenses (5
Reference numeral 5) denotes a cylindrical lens, a condenser lens or the like, and while passing therethrough, the laser beam is converted into a laser beam having a predetermined cross-sectional shape. The laser beam has a rectangular shape, in particular, a long-axis direction having a very large line shape with respect to the short-axis direction. The line beam is applied to a substrate (59) to be processed in the chamber (54) through a transparent window (60) provided in the chamber (54). The stage (58) on which the substrate to be processed (59) is placed is movable horizontally and vertically on a plane, and
9) The line beam is scanned above.

FIG. 5 is an enlarged sectional view of a substrate (59) to be processed. TFT on substrate (10) such as non-alkali glass
Gate electrode (11) and a gate insulating film (1
2) An a-Si (13a) to be processed is formed thereon. FIG. 6 is a graph showing T using the obtained p-Si (13).
It is sectional drawing of FT. FIG. 7 is a plan view of the TFT, and FIGS. 5 and 6 are cross-sectional views along the line AA in FIG. The p-Si (13) obtained by subjecting the a-Si (13a) to laser annealing is left in an island shape in a region passing above the gate electrode (11), and a region immediately above the gate electrode (11). Is a non-doped channel region (CH), a lightly doped (LD) region (LD) on both sides of which is lightly doped with impurities, and a source region (S) and a drain on the outside thereof which are heavily doped with impurities. A region (D) is formed. p-
Covering the implantation stopper film (14) used as a mask when forming the Si (13) and the LD region (LD),
An interlayer insulating film (15) of iNx, SiO2 or the like is formed. A source electrode (16) is formed on the interlayer insulating film (15).
And a drain electrode (17) are formed, and the interlayer insulating film (1) is formed.
5) They are connected to the source region (S) and the drain region (D) through the contact holes (CT) formed therein.

[0006]

FIG. 8 shows a-Si (1
3A) Irradiation laser energy (horizontal axis) and p-Si (13) grain size formed at that time (vertical axis)
FIG. As the energy increases, the grain size also increases. However, when the energy exceeds a certain energy value Eo at which the maximum grain is not obtained, the grain size rapidly decreases. Therefore, in order to obtain a predetermined grain size, the energy must be within a narrow range of Ed and Eu.

For this reason, if the irradiation energy of the line beam is slightly varied and deviates from the optimum range between Ed and Eu, crystallization is not sufficiently performed, and the poorly crystallized region (R) having a small grain size becomes p-p. It occurs in a certain area in Si. FIG. 7 shows a positional relationship between a channel region (CH) of a certain TFT and a poorly crystallized region (R). In FIG. 7, p
In Si- (13), the poorly crystallized region (R) is formed in a line extending in the vertical direction (V) and passes through the channel region (CH), but has a width X of the poorly crystallized region (R). Is larger than the channel width W of the channel region (CH) and covers the channel region (CH). The poorly crystallized region (R) has extremely low mobility, and the charge transfer path (MN) in the channel region (CH) connecting the source region (S) and the drain region (D) becomes poor. Getting worse.

The element characteristics are determined by the substantial width of the movement path. As the ratio of the poorly crystallized region (R) to the channel width W increases, the deterioration of the characteristics becomes more remarkable. Therefore, as shown in FIG. 7, even if the poorly crystallized region (R) does not occur over the entire channel region (CH), if the poorly crystallized region (R) covers a part of the channel region (CH), the characteristics can be improved. Gets worse.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve this problem, and is directed to a semiconductor device having a plurality of semiconductor elements in which a semiconductor film annealed by a pulse laser is formed on a substrate. One, some, or all of the semiconductor elements have a plurality of channel regions that are electrically in a parallel relationship, each channel width of the plurality of channel regions, and a separation distance of a gap between the channel regions. Is larger than the pitch of the pulse laser.

Thus, even if a defective region having the same width as the pitch of the pulse laser is generated on the channel region, the ratio of the defective region to the channel width is reduced, and deterioration of device characteristics is suppressed. Further, a display electrode group for modulating the optical modulation member on the substrate, a first thin film transistor group connected to each of the display electrode groups for supplying a display signal, and a second thin film transistor for driving the first thin film transistor group a group of the thin film transistor forming, the first and second thin film transistors is a display device using a semiconductor film annealed by pulsed laser is applied to the channel region, forming the first or second thin film transistor group One, some, or all of the thin film transistors have a plurality of channel regions that are electrically in parallel with each other, and the width of each of the plurality of channel regions and the separation distance of the gap between the respective channel regions are adjusted. The total distance is larger than the pitch of the pulse laser.

As a result, even if a defective region having the same width as the pitch of the pulse laser is generated on the channel region, the ratio of the defective region to the channel width is reduced, and the display device has excellent element characteristics. Is obtained.

[0012]

FIG. 1 is a plan view of a TFT according to an embodiment of the present invention. The cross-sectional structure along the line AA in FIG. 1 is the same as that shown in FIG. In the present embodiment, one element in which the gate electrode (11), the source electrode (16), and the drain electrode (17) are each integrated has two channel regions (CH) in an electrically parallel relationship. And these channel regions (C
H) are spaced apart from each other. The channel width (W) of each of the two channel regions (CH)
2, W3) and the width (WA) of the gap between the channel regions (CH) is a total distance W1 which is equal to the pitch P of the pulse laser, as will be described later in detail. Has been larger than.

FIG. 2 is a plan view of the substrate to be processed during laser annealing. The large substrate (1) includes a plurality of, for example, six, active matrix substrates (2) used for display devices. Each active matrix substrate (2)
In (3), a display section in which display elements are to be formed in a matrix is formed, and (4) is to be formed to generate a scanning signal for controlling switching to write a display signal to each display element. A gate driver (5) is a drain driver to be formed to supply a display signal to each display element in synchronization with the scanning signal.

These active matrix substrates (2)
Is bonded to a counter substrate provided with a counter electrode to form each display element, and a display device housing is formed and separated for each active matrix substrate (2), and an optical member is provided in each housing. A certain liquid crystal is loaded to complete the LCD. In the display section (3), each display element includes a capacitor having a liquid crystal as a dielectric layer and a TFT as a switching element for controlling rewriting and holding of a display signal voltage for driving the liquid crystal in the capacitor. ,
In the driver sections (4, 5), CMOS transistors are formed by N-ch and P-ch TFTs as shown in FIG.

In FIG. 2, an enlarged cross section is shown in FIG.
A state in which laser annealing is performed in a state where the a-Si (13a) is formed on the substrate (10) is shown. Scanning is performed by sequentially shifting each shot of the line beam (LB), which is a pulse laser, on the substrate (1) with a predetermined overlap amount. And
A poorly crystallized region (R) caused by a variation in irradiation energy remains in a linear shape extending in the same direction as the direction of the line beam (LB). The major axis direction and the minor axis direction of the line beam (LB) are set in the horizontal direction (H) and the vertical direction (V) with respect to the substrate (1) plane, respectively.

First, the applicant of the present application has found out that the reason for the occurrence of the poor crystallization region (R) is as follows. First, a line beam (LB) as shown in FIG.
Scan of each shot of pulsed laser (STn)
Is sequentially shifted in the short axis direction, here, the vertical direction (V). Here, the line width T and the line length of the line beam (LB) are set by the laser oscillation source (51) and the optical system (52) of the laser annealing apparatus shown in FIG. In addition, the oscillation frequency of the oscillation source (51) is set to 200 for stability between shots of the pulse laser.
The frequency is set to about 300 Hz, for example, 290 Hz, and the line width T of the line beam (LB) is set to 10 for uniformity of the energy density in the irradiation area of the line beam (LB).
It is set to 0 to 1000 μm, for example, 600 μm. When the scanning speed, that is, the moving speed of the stage (58) is set, the throughput is determined, and at the same time, the overlap amount between the shots (STn) is determined from the pulse frequency and the line width T set by the oscillation source (51). That is, the pitch P is determined. For example, if P = 30 μm,
The shot is set to 0 shots.

Irradiation energy of the pulse laser is inevitable to be slightly varied between shots. If the irradiation energy deviates from a very narrow optimum range between Ed and Eu for a certain shot, crystallization becomes poor. And the shot fails. In FIG. 3, for example, when the shot STn-3 fails, the next shot STn-
The region where 2, STn-1,... Overlap is recrystallized to recover the failure of shot STn-3. Since it is final, the crystallization failure is not recovered, and remains as a poor crystallization region (R). That is, it can be seen that the poorly crystallized region (R) is a slender elongated in the direction perpendicular to the scanning direction of the line beam (LB), and its line width X is equal to the pitch P of the pulse laser.

P is determined by the equipment and process conditions as described above. Further, the channel width W of one element is determined by the required operation characteristics. In the present invention, under a constant pitch P and a channel width W,
Channel width W of each of a plurality of channel regions (CH)
2 and W3, and the relationship between pitch P

[0019]

(Equation 1)

[0020]

(Equation 2)

It is set to be as follows. In FIG. 1, the poorly crystallized region (R) occurs at the same position as in the conventional example shown in FIG. 7, but in FIG. 7, the entire region of the channel region (CH) is covered by the poorly crystallized region (R). In contrast, in FIG. 1, the right channel region (CH) is covered by the poorly crystallized region (R), but the left channel region (CH) is covered by the poorly crystallized region (R). Is out of range. Therefore, in the device of FIG. 1, the movement path (MG) having a width of W2 in the entire width W of the channel width is substantially improved.

Thus, the poorly crystallized region (R) having a width P is obtained.
Occurs over the region of the TFT, but the poorly crystallized region (R) extends over the entire width of the channel region (CH).
Is not occupied, and the movement path (MG) formed in the channel region (CH) outside the poor crystallization region (R)
Thereby, good element characteristics can be obtained.

[0023]

As is apparent from the above description, the present invention relates to a semiconductor device or a display device having a plurality of semiconductor elements formed by using a semiconductor film subjected to pulsed laser annealing. By arranging the channel regions apart and making the sum of the channel width and the separation distance larger than the pulse pitch, even if a defective region having the same width as the pulse pitch occurs in the semiconductor film,
The entire area of the channel region is prevented from being covered by the defective area, and furthermore, the ratio of the defective area to the entire width of the channel area is reduced, and the width of the substantial moving path is increased. Semiconductor device or display device having

[Brief description of the drawings]

FIG. 1 is a plan view of a TFT according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating a positional relationship between a substrate to be processed and a region to be irradiated with a line beam according to the embodiment of the present invention.

FIG. 3 is a plan view showing how a line beam is scanned.

FIG. 4 is a configuration diagram of a laser annealing apparatus.

FIG. 5 is a cross-sectional view of a substrate to be processed during laser annealing.

FIG. 6 is a sectional view of a TFT.

FIG. 7 is a plan view of a conventional TFT.

FIG. 8 is a diagram illustrating a relationship between laser energy and grain size.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate to be processed 2 Active matrix substrate 3 Pixel part 4 Gate driver 5 Drain driver 10 Substrate 11 Gate electrode 12 Gate insulating film 13 p-Si 16 Source electrode 17 Drain electrode CH Channel region D Drain region S Source region LB Edge of line beam Line R Crystallized area

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FIG02F 1/136 500 (72) Inventor Kiyoshi Yoneda 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (56 References JP-A-9-74205 (JP, A) JP-A-58-178565 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 29/786 H01L 21/336 H01L 21/20 G02F 1/1368 G09F 9/33

Claims (3)

(57) [Claims] 1. A semiconductor device having a plurality of semiconductor elements formed by forming a semiconductor film annealed by a pulse laser on a substrate, wherein one, some, or all of the semiconductor elements are electrically connected. Has a plurality of channel regions in a parallel relationship, the total distance including the channel width of the plurality of channel regions and the separation distance of the gap of each channel region is larger than the pitch of the pulse laser. Characteristic semiconductor device. 2. A display electrode group for modulating an optical modulation member on a substrate; a first thin film transistor group connected to each of the display electrode groups for supplying a display signal;
Second thin film transistors are formed for driving the first thin film transistor group, said first and second thin film transistors is a display device using a semiconductor film annealed by pulsed laser is applied to the channel region, the first Thin film forming the first or second thin film transistor group
One, some, or all of the membrane transistors each have a plurality of channel regions that are in electrical parallel relation, and are adjusted to each channel width of the plurality of channel regions and the separation distance of the gap between each channel region. The display device, wherein a total distance is larger than a pitch of the pulse laser. 3. A display electrode group for modulating an optical modulation member on a substrate; a first thin film transistor group connected to each of the display electrode groups for supplying a display signal;
A second thin film transistor group for driving one thin film transistor group is formed, and the first or second thin film transistor group is a display device using a semiconductor film annealed by a pulsed laser for a channel region, Pulse of the first or second thin film transistor group
Channel the semiconductor film annealed by laser
Thin film transistor that constitutes a group of thin film transistors provided in the
One, some, or all of the transistors have a plurality of channel regions that are electrically in parallel with each other, and the sum of each channel width of the plurality of channel regions and the separation distance of the gap between the channel regions is provided. The display device, wherein the distance is larger than the pitch of the pulse laser.