JP2000292808A - Semiconductor device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent destruction of a film layer other than an object to be cut by a laser beam, and to prevent a decrease in reliability such as a new image defect or a disorder in alignment of liquid crystal. SOLUTION: A thin film transistor 3 formed on an insulating substrate 2, a wiring layer 11 extending from a source region 7s formed in a semiconductor layer 7 of the thin film transistor 3, and a storage capacitor electrode connected to the wiring layer 11 A storage capacitor line 30 disposed opposite to the storage capacitor electrode via the interlayer insulating film 10; and a metal reflection layer 22 disposed opposite to the wiring layer via the interlayer insulating film. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device,
Particularly, a thin film transistor (TFT-Thin Film Tr) used as a pixel switching element in a liquid crystal display device or the like.
ansistor-) for arrays.

[0002]

2. Description of the Related Art For example, a semiconductor device using a polycrystalline semiconductor such as polysilicon includes, for example, a thin film transistor (TFT) formed corresponding to a liquid crystal cell of a liquid crystal display device. This will be described with reference to FIGS.

As shown in FIG. 6, a conventional semiconductor device 1 is realized as a liquid crystal display device in which a TFT 3 as a semiconductor circuit is formed on a glass insulating substrate 2.
In the equivalent circuit of one pixel shown in FIG. 5, the liquid crystal Cl has a voltage difference (Vco) between the common voltage Vcom and the pixel voltage Vn.
m−Vn), the transmittance is modulated, and the display operation is performed. The signal voltage Vsig supplied via the signal line 4 is
When an ON voltage is applied to the gate electrode of TFT3, TF
The pixel voltage Vn is transmitted to the pixel electrode forming the liquid crystal capacitance Cl via T3.

The pixel voltage Vn needs to be held only until the next ON voltage is applied to the gate electrode G of the TFT 3. In order to reduce the leak current through the TFT 3, the pixel voltage Vn is connected in parallel with the liquid crystal capacitance Cl. The storage capacitor Cs is connected. When an electrical defect such as a short-circuit defect occurs in the storage capacitor Cs, the storage capacitor Cs is separated from the liquid crystal capacitor Cl to eliminate the leakage of the storage capacitor Cs and completely take the role of the original storage capacitor Cs. If not, the degree of image defects can be reduced.

FIG. 6 is a cross-sectional structure of one pixel of a liquid crystal display device using a poly-Si transistor circuit on a glass substrate 2. The TFT 3 has a polycrystalline silicon layer 7a, a gate insulating layer 8a (gate electrode), and a gate conductor layer 9a, and the storage capacitor Cs has a polycrystalline silicon layer 7b, a gate insulating film 8a.
b, a capacitor Cs electrode 9b. The source of the TFT 3 and the storage capacitor Cs are connected by an aluminum (Al) wiring 11 a formed on the first interlayer insulating film 10. The drain of the TFT 3 is connected to the signal line Al wiring 11A. A second interlayer insulating film 12 is provided on the Al wiring 11, and a pixel electrode 13 is formed on the second interlayer insulating film 12 by an ITO (indium tin oxide) transparent conductor layer. It is connected to the TFT 3 and the storage capacitor Cs. The pixel electrode 13A is a pixel electrode of an adjacent pixel.

On these pixel electrodes 13 and 13A, for example, a first alignment film 14 made of polyimide is formed.
5, including a liquid crystal layer 15 sandwiched between a second alignment film 16 and a counter glass substrate 18 having a transparent conductor film 17
One pixel is configured. Here, the storage capacitor Cs and the liquid crystal capacitor Cl in FIG. 5 are separated from each other by the Al wiring 11 connecting the polycrystalline silicons 7a and 7b in FIG.
For example, it can be realized by irradiating a laser 19 from the back surface of the glass substrate 2 for cutting.

The Al wiring layer 1 by the irradiation of the laser 19
In the cutting of 1, the second interlayer insulating film 12, the pixel electrode 13, and the first alignment film 14 on the cut portion 20 are also irradiated with the laser. Irradiation of these with the laser disturbs the orientation of the liquid crystal 15 on the cut portion, and not only the Al wiring 11 but also the second interlayer insulating film 12 and the pixel electrode 13.
Destruction will also occur. Due to the disorder of the alignment of the liquid crystal 15 and the destruction of the insulating film 12 and the pixel electrode 13, further image defects or poor reliability occur.

FIG. 7 shows another conventional example. That is, TF
T3 and the storage capacitor Cs are polycrystalline silicon (poly Si) 7
Connected by When the laser 19 is applied to the connection between the TFT 3 and the storage capacitor Cs in the polycrystalline silicon 7, the polycrystalline silicon layer 7 is cut.

In this other conventional semiconductor device, a polycrystalline silicon (poly Si) layer 7 is
By irradiation with 0, the poly-Si islands 7a and 7b are melted and separated. This polycrystalline silicon (poly Si) separation reduces the required laser irradiation energy by 1/4 as compared with the cutting of the Al wiring.
However, the disorder of the alignment of the liquid crystal 15 and the destruction of the first interlayer insulating film 10, the second interlayer insulating film 12, and the pixel electrode 13 cannot be avoided even if the degree is different. There was a problem. Further, since the liquid crystal layer 15 has a thickness of about 4 μm, the transparent conductor film 17 and the pixel electrode 13 or the
This causes an electrical short circuit in the wiring and causes new image defects.

[0010]

As described above, according to the conventional semiconductor device, the interlayer insulating film 12 and the pixel electrode 13 are destroyed when the laser beam 19 is irradiated, or the alignment of the liquid crystal 15 is disturbed. And image defects occur.

The present invention has been made in order to solve the above-mentioned problem in the conventional semiconductor device, and is intended for cutting the wiring layer 11 or the polycrystalline semiconductor layer 7 connecting the TFT 3 and the storage capacitor Cs by laser irradiation. By forming a reflective layer on the back side of the cutting target in the laser incident direction, laser damage to film layers other than the cutting target is prevented, and new image defects and poor reliability such as liquid crystal alignment disorder are prevented. It is intended to be.

[0012]

In order to achieve the above object, a semiconductor device according to the basic structure of the present invention has a thin film transistor formed on an insulating substrate and a source region formed in a semiconductor layer of the thin film transistor. An existing wiring layer, a storage capacitor electrode connected to the wiring layer, a storage capacitor wiring opposed to the storage capacitor electrode via an interlayer insulating film, and a storage capacitor wiring connected to the wiring layer via the interlayer insulating film. And a metal reflective layer disposed opposite to the metal reflective layer.

In the above-mentioned basic structure, the wiring layer may be electrically insulated from a wiring for driving the thin film transistor.

Further, in the above basic configuration, the insulating substrate may be formed of a glass substrate.

In the above-mentioned basic structure, the storage capacitor electrode and the wiring layer may be formed below the interlayer insulating film.

In the above-mentioned basic structure, the semiconductor layer may be made of a polycrystalline silicon film.

In the above-mentioned basic structure, the metal reflective layer may be formed of the same layer as a source electrode connected to the source region of the thin film transistor.

Further, in the case where the metal wiring layer is formed in the same layer as the source electrode, the metal reflection layer is
It may be formed integrally with the source electrode.

In the above-mentioned basic structure, the metal reflection layer may be made of an aluminum film or an aluminum alloy film.

Further, in the above basic configuration, the interlayer insulating film may be a gate insulating film of the thin film transistor.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a semiconductor device according to the present invention will be described below in detail with reference to the drawings. First, a semiconductor device according to a first embodiment of the present invention will be described with reference to FIGS. In the following drawings showing each embodiment, the same reference numerals as those used in FIGS. 6 and 7 showing the conventional semiconductor device indicate the same or corresponding components as those of the conventional semiconductor device. And FIG. 1 is a plan view of FIG.
It is sectional drawing of the -A 'line.

The semiconductor device 21 shown in FIG. 1 has a gate electrode 9a formed on a gate insulating film 8a on a channel region 7a of a polycrystalline semiconductor (poly Si) layer 7 formed on a glass substrate 2. A storage capacitor Cs including a TFT 3 and a storage capacitor line 30 opposed to a region 7b other than a channel region of the poly-Si layer 7 via a gate insulating film 8b.
Is formed, and a first interlayer insulating film 10 is formed thereon. The source and drain of the TFT 3 are connected to a drain electrode 11A and a source electrode 11a formed on, for example, Al provided on the first interlayer insulating film 10. The TFT 3 and the storage capacitor Cs are connected by an n ⁺ -type poly-Si layer extending from the source region 7 s of the TFT 3. The Al electrode is not limited to being formed only of aluminum, but may be formed of an alloy with another metal.

An Al metal electrode is provided as a metal reflection layer 22 on the first interlayer insulating film 10 corresponding to the cut portion 20 of the impurity-doped polycrystalline semiconductor (poly Si) layer 7. A second interlayer insulating film 12 is formed so as to cover it, and an IT layer formed thereover is formed.
The O transparent conductor pixel electrode 13 is connected to the source electrode 11a.

FIG. 2 is a plan view of the semiconductor device shown in FIG. A scanning line 9 for driving the TFT 3 and a signal line 11 are arranged orthogonal to each other, and a gate electrode 9 a of the TFT 3 is branched from the scanning line 9. Under the gate electrode 9a, a poly-Si layer is arranged with a gate insulating film interposed therebetween, and an impurity is introduced into the poly-Si layer to form a drain region 7d and a source region 7s. Drain region 7d is connected to source electrode 11a via a contact hole provided in the gate insulating film and the interlayer insulating film. This source electrode 11a is the second interlayer insulating film 1
2 is connected to the pixel electrode 13 via a contact hole.

The storage capacitor wiring 30 is connected in parallel with the scanning line 9.
Is arranged. The storage capacitor line 30 is connected to the scanning line 9
And the same layer. This storage capacitor wiring 3
A poly-Si layer serving as a storage capacitor electrode 7b is opposed to a lower layer of 0 through a gate insulating film. As in the source region 7s and the drain region 7d, an n-type impurity is introduced into the poly-Si layer in the region forming the storage capacitor electrode 7b and the wiring layer 20.

On the upper side of the wiring layer 20, a metal reflection layer 22 is opposed to the metal reflection layer 22 with the gate insulating film and the first interlayer insulating film 10 interposed therebetween. The metal reflection layer 22 is formed of the same Al film as the signal line 11 and the source electrode 11a, and is formed electrically separated from the signal line 11 and the scanning line 9.

In the above configuration, the poly S
The i-layer 7 is irradiated with laser light 19 from the glass substrate 2 side to melt-cut the doped poly-Si layer 7. Here, a part of the laser light irradiates the polycrystalline semiconductor layer 7 and contributes to the melting and cutting of the doped polycrystalline semiconductor (poly Si). In a semiconductor device having such a configuration, A
Since it is not necessary to melt and cut the l-wiring layer with the irradiation laser light 19, only the polycrystalline semiconductor layer 7 can be cut with a laser irradiation energy of 1/4 to 1/10 of the energy for cutting the Al layer 11. Further, since the cutting irradiation energy can be further reduced by the reflection effect from the metal reflection layer 22, the influence on the periphery of the cutting portion 20 is reduced.

In the embodiment, the laser light 19
Is blocked by the metal reflective layer 22, the pixel electrode 13, the first
Since the laser beam 19 is not irradiated to the alignment film 14 and the liquid crystal layer 15, it is possible to suppress the occurrence of a new image defect and the problem of reliability, which are problems in the conventional semiconductor device.

In the first embodiment, the Al reflection layer 2
Although 2 is used as a reflection layer for the laser beam 19, when the gate electrode 9a and the Cs electrode 30 are, for example, molybdenum-tungsten (MoW), this metal layer may be used as a reflection layer. Further, in the first embodiment, it is assumed that the liquid crystal layer 15 is injected, an image is displayed, a specific cell is detected as having an image defect, and then the cell is repaired (repaired). The present invention is not limited to this, and repair may be performed after detecting a circuit defect by an electrical method. In this case, the present invention is applicable not only to the display device. In a state where the liquid crystal layer 15 is not present, the metal reflection layer 22 is formed below the polycrystalline semiconductor (poly Si) layer 7 so that the laser beam 19 is irradiated not from the glass substrate 2 side but from the opposite direction. May be.

Next, a semiconductor device according to a second embodiment of the present invention is shown in FIG. 3 as a sectional structure and FIG. 4 as a plan structure.
The cross-sectional view of FIG. 3 is obtained by cutting the plan view of FIG. 4 along the line BB ′. The semiconductor device according to the second embodiment includes:
The metal reflection layer 22 is formed integrally with the source electrode 11a of the TFT 3.

In the semiconductor device according to the second embodiment, since the metal reflection layer 22 is connected to the source electrode 11a, the laser irradiation energy is easily attenuated by heat conduction, and the energy intensity is lower than that of the first embodiment. Can also be secured large. As described above, by securing a large laser irradiation energy, the doped poly-Si layer 7 can be easily melted and cut, and the processing margin can be increased. Also in the second embodiment, since the laser beam 19 is blocked by the metal reflection layer 22, the pixel electrode 13 and the first
Since the irradiation of the alignment film 14 and the liquid crystal layer 15 is eliminated, the occurrence of a new image defect which has conventionally been a problem can be suppressed, and the reliability can be improved.

When the island-like metal reflection layer 22 is formed as the reflection layer as in the first embodiment, the source electrode 1
A space between the metal reflective layer 22 and the source electrode 11a is required, and the repair pattern can be reduced in size by connecting the metal reflective layer 22 to the source electrode 11a as in the second embodiment. In the second embodiment, the metal reflection layer 22 is connected to the source electrode 11a. However, the present invention is not limited to this, and may be connected to another metal electrode in the circuit.

The laser beam 19 may be emitted from the opposite side of the glass substrate 2 instead of the glass substrate 2.

[0034]

As described above, according to the semiconductor device of the present invention, it is possible to suppress image defects while suppressing adverse effects on circuit elements arranged around a cut portion of a wiring of a semiconductor circuit formed on an insulating substrate. In addition, it is possible to perform melting and cutting of the wiring layer for a specific cell having the above-mentioned problem, and it is possible to suppress the occurrence of new image defects and the problem of impairing reliability.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a plan view showing an arrangement of the semiconductor device shown in FIG. 1;

FIG. 3 is a sectional view showing a configuration of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a plan view showing an arrangement of the semiconductor device shown in FIG. 3;

FIG. 5 is a circuit diagram showing an equivalent circuit of a conventional semiconductor device.

FIG. 6 is a sectional view showing the structure of the conventional semiconductor device shown in FIG.

FIG. 7 is a cross-sectional view showing a different structure of a conventional semiconductor device.

[Explanation of symbols]

 Reference Signs List 2 glass substrate 3 TFT 7 polycrystalline semiconductor layer 11 wiring layer 19 laser beam 20 fusing location 21 semiconductor device 22 metal reflection layer 30 storage capacitor wiring Cs storage capacitor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H092 JA25 JA29 JA38 JA42 JA44 JB13 JB23 JB32 JB33 JB38 JB51 JB57 JB63 JB69 JB72 KA04 KA07 KA16 KA18 KB14 KB23 MA35 MA47 NA25 NA27 NA29 PA06 5C094 AA42 DB04A19 EA05 EA06 EB02 ED11 FA01 FA02 FB12 FB14 FB15 GB10 5F110 AA26 AA27 CC02 DD02 EE06 GG02 GG13 HL03 HM17 HM18 NN44 NN46 NN47 NN73 QQ30

Claims (9)

[Claims] 1. A thin film transistor formed on an insulating substrate, a wiring layer extending from a source region formed in a semiconductor layer of the thin film transistor, a storage capacitor electrode connected to the wiring layer, and the storage capacitor electrode A storage capacitor wiring opposed to the wiring layer via an interlayer insulating film, and a metal reflective layer opposed to the wiring layer via the interlayer insulating film. 2. The semiconductor device according to claim 1, wherein said wiring layer is electrically insulated from a wiring for driving said thin film transistor. 3. The semiconductor device according to claim 1, wherein said insulating substrate is a glass substrate. 4. The semiconductor device according to claim 1, wherein said storage capacitor electrode and said wiring layer are formed below said interlayer insulating film. 5. The semiconductor device according to claim 1, wherein said semiconductor layer is made of a polycrystalline silicon film. 6. The semiconductor device according to claim 1, wherein said metal reflection layer is formed of the same layer as a source electrode connected to said source region of said thin film transistor. 7. The semiconductor device according to claim 6, wherein said metal reflection layer is formed integrally with said source electrode. 8. The method according to claim 1, wherein said metal reflection layer is made of an aluminum film or an aluminum alloy film.
3. The semiconductor device according to claim 1. 9. The semiconductor device according to claim 1, wherein said interlayer insulating film is a gate insulating film of said thin film transistor.