JPH1082995A - Liquid crystal display device and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the luminance of a liquid crystal display device by improving the reflectivity of a reflection liquid crystal element. SOLUTION: A wiring 25a connected to the source region 22a an MOSFETQ11 formed on the main surface of a semiconductor substrate 13 is covered with an insulating film 26 having a flattened front surface and an electrode 14 for impressing a liquid crystal driving voltage consisting of a titanium layer 14a as a lower layer and an aluminum alloy layer 14b as an upper layer is formed on this insulating film 26. At the time of producing the reflection liquid crystal element, the films are continuously formed without breaking vacuum after the deposition of the titanium layer 14a before the deposition of the aluminum alloy layer 14b. The oxide of the titanium formed on the surface of the titanium layer 14a is otherwise removed by sputter etching before the deposition of the aluminum alloy layer 14b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a manufacturing technique thereof, and more particularly to a technique effective when applied to a liquid crystal display device having a reflection type liquid crystal element.

[0002]

2. Description of the Related Art Recently, an LCD (Liquid Crystal Display) has been used because it is more compact or lighter than a projector using a CRT (Cathode-Ray Tube).
Display) has attracted attention.

As a light valve of such an LCD projector, a TFT (Thin Film Transister) LCD element, which is an active matrix type LCD element, is widely used. However, a reduction in luminance in high-definition projection is a problem. I have.

As a countermeasure, for example, the Institute of Electronics, Information and Communication Engineers, “TECHNICAL REPORT OF IEICE” EI
D94-77, October 1994, pp. 97-101, NCAP (Nema (Nema) which does not require a polarizing plate.
A reflective liquid crystal device that drives tic Curvilinear Aligned Phase) with a MOSFET has been proposed.

The following is a brief description of the reflective liquid crystal element described in the above document.

That is, the reflective liquid crystal element has a MOSFET array formed in a two-dimensional array on a semiconductor substrate made of silicon single crystal, and a data driver and a scan driver are arranged around the MOSFET array. Is what it is. Each MOSFET functions as a switching element for driving a liquid crystal, and corresponds to one pixel.

[0007] The output of the data driver is connected to the drains of a group of MOSFETs in the vertical direction of the MOSFET array, and outputs a video signal sequentially selected by a shift register provided in the data driver.

The output of the scan driver is connected to the gate electrodes of a group of MOSFETs in the horizontal direction of the MOSFET array, and is selected by a shift register.
It outputs an ET ON / OFF control signal.

The source of the MOSFET is connected to a storage capacitor and an electrode formed above the MOSFET via an insulating film, and a transparent electrode (I
An NCAP liquid crystal is formed between the glass substrate on which the (TO) is formed.

Therefore, at one moment, one M selected by the data driver and the scan driver is used.
The OSFET is turned on, and at that moment the MOSF
A video signal applied to the drain of the ET is transmitted to the electrode via the source, and is applied as a drive voltage to the liquid crystal in the electrode region. The transmission / non-transmission of the liquid crystal is controlled by the application / non-application of the driving voltage, and the reflection / non-reflection of light in the pixel portion is controlled.

The light emitted from the light source is applied to the reflection type liquid crystal element. When the NCAP liquid crystal is in a transmitting state, the light passes through the glass substrate, the transparent electrode and the liquid crystal, is reflected by the electrode, and is returned to the liquid crystal and the transparent. The light passes through the electrodes and the glass substrate, and is projected onto a screen via an appropriate optical system to form an image.

Such a reflection type liquid crystal element does not use a polarizing plate, and also serves as an electrode for applying a liquid crystal driving voltage and also serves as a projection light reflection plate. There is an advantage that a liquid crystal display device with high luminance can be obtained.

[0013]

However, even in the reflection type liquid crystal element, there is a strong demand for further improvement in luminance.
The present inventor has recognized that the following problems exist as a result of repeated experimental studies aimed at further improving the luminance.

That is, as described above, the projection light is reflected by the drive voltage application electrode of the reflection type liquid crystal element, and this electrode is made of a thin film mainly composed of aluminum which has been conventionally used in the manufacture of LSIs and the like. Is formed.

The main function of such an aluminum thin film for LSI lies in the electrical connection between semiconductor integrated circuit elements, and the function as a reflector for reflecting projection light has not been expected. Therefore, the material design or electrode film configuration in consideration of the reflectance is not considered, but rather, the material is designed from the viewpoint of preventing the reflection of exposure light in the photolithography process, and the antireflection film is used together. It was used in various usage forms.

Further, even when the anti-reflection film is not used, there is a phenomenon that the reflectance is lowered by a heat treatment step after the drive voltage application electrode of the reflection type liquid crystal element is formed. , And moreover,
The inventor has recognized that hillocks are generated on the surface of the aluminum thin film through the heat treatment process, and the surface is roughened.

An object of the present invention is to improve the projection light reflectance of a reflection type liquid crystal element and improve the luminance of a liquid crystal display device.

Another object of the present invention is to suppress the occurrence of hillocks on the aluminum thin film surface of the liquid crystal drive voltage applying electrode of the reflection type liquid crystal element and to improve the projection light reflectance of the liquid crystal drive voltage applying electrode. is there.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0020]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

(1) The liquid crystal display device of the present invention is provided on a liquid crystal driving MOSFET arranged in a two-dimensional array on the main surface of a semiconductor substrate and an insulating film covering the MOSFET. MOSFE through the opened connection hole
An electrode layer electrically connected to the source region of T and acting as a reflector for reflecting light passing through a liquid crystal layer provided thereover, and an electrode layer to which a voltage applied to the liquid crystal layer is applied. A liquid crystal display device having a liquid crystal element, wherein an electrode layer is formed on a first metal layer made of a material having a high solid solubility in silicon and an upper layer of the first metal layer containing aluminum as a main component. And a second metal layer.

According to such a liquid crystal display device, the first electrode layer made of a material having a high solid solubility in silicon is used.
In order to form a laminated film including a metal layer of aluminum and a second metal layer mainly composed of aluminum and formed on the first metal layer, the hillocks of the surface of the second metal layer mainly composed of aluminum are formed. Can be suppressed, and the reflectance of the metal layer as the reflection plate can be improved. As a result, the brightness of the liquid crystal display device can be improved.

That is, as the aluminum alloy as the second metal layer, an alloy in which silicon atoms or copper atoms or both are added to aluminum is usually used for the purpose of suppressing the electromigration effect or reducing the aluminum spikes. Can be However, the present inventors have determined that one of the causes of the generation of hillocks is due to the presence of silicon atoms contained in the aluminum alloy, and the present invention has been completed based on the above findings. In other words, silicon atoms that cause hillocks are absorbed by the first metal layer by diffusion, and the silicon content in the second metal layer is reduced to suppress hillocks. Therefore, the first metal layer is made of a material having a high solid solubility in silicon.

As a material having a high solid solubility, IVB
Group V or Group VB metals, especially titanium.

(2) The method for manufacturing a liquid crystal display device according to the present invention is the method for manufacturing a liquid crystal display device according to (1) above, wherein a vacuum process for forming the first metal layer and a second metal layer are performed. The first and second metal layers are continuously formed while maintaining a vacuum state between the vacuum process and the vacuum process to be formed.

According to such a method of manufacturing a liquid crystal display device, the vacuum process for forming the first metal layer and the vacuum process for forming the second metal layer are continuously performed while maintaining a vacuum state. In order to form the first and second metal layers, the generation of hillocks on the surface of the aluminum alloy as the second metal layer is suppressed, the reflectance of the reflective liquid crystal element is improved, and the brightness of the liquid crystal display device is increased. Can be improved.

The first metal layer and the second metal layer are generally formed as thin films using a vacuum process such as a vacuum deposition method or a sputtering method. In such a vacuum process, after forming the first metal film, the vacuum state is broken,
When exposed to the air atmosphere, a natural oxide layer formed by combining with oxygen in the air atmosphere is formed on the surface of the first metal film. When such an oxide layer is present at the interface between the first metal film and the second metal film, the silicon atoms in the second metal film described in the above (1) may be transferred to the first metal film. Diffusion is prevented, and the silicon atom concentration in the second metal film does not decrease. Such a state induces the generation of hillocks on the surface of the aluminum alloy, which is the second metal film, even though the first metal film is formed, and lowers the reflectance of the surface. Thus, in the manufacturing method of the present invention, after forming the first metal film, the second metal film is formed without breaking in vacuum.

(3) A method for manufacturing a liquid crystal display device according to the present invention is the method for manufacturing a liquid crystal display device according to the above (1), wherein a first metal layer is formed, and then a second metal layer is formed. Before this, the oxide layer formed on the surface of the first metal layer is removed by sputtering.

According to such a method of manufacturing a liquid crystal display device, the oxide layer formed on the surface of the first metal layer after the first metal layer is formed and before the second metal layer is formed. Is removed by sputtering, the generation of hillocks on the surface of the aluminum alloy as the second metal layer can be suppressed, the reflectance of the reflective liquid crystal element can be improved, and the luminance of the liquid crystal display device can be improved.

As described in the above (2), when the vacuum state is broken after the formation of the first metal layer and the first metal layer is exposed to the atmosphere, an oxide layer is formed on the surface. However, according to the manufacturing method of the present invention, even if the first metal layer is exposed to the atmosphere by breaking the vacuum after the formation of the first metal layer, the formation of the second metal layer is prevented before forming the second metal layer. Since the removed oxide layer is removed by sputtering, no oxide layer is formed at the interface between the first metal layer and the second metal layer, and therefore, the second metal of the silicon atoms in the first metal layer is removed. Diffusion into the layer is not prevented, and generation of hillocks can be suppressed.

[0031]

Embodiments of the present invention will be described below in detail with reference to the drawings.

(Embodiment) FIG. 1 is a sectional view showing an example of a main part of a reflection type liquid crystal element used in a liquid crystal display device according to an embodiment of the present invention, and FIG.
FIG. 1 is a conceptual diagram illustrating a configuration example of a liquid crystal display device according to an embodiment of the present invention. FIG. 3 is a circuit diagram showing an example of a liquid crystal driving MOSFET array of a reflective liquid crystal element and its peripheral circuits.

As shown in FIG. 2, the liquid crystal display of this embodiment has a light source 1, an optical system 2, a reflector 3 for reflecting light passing through the optical system 2, a reflective liquid crystal element 4, and a projection light lens. 5 and a screen 6.

The light emitted from the light source 1 is shaped by the optical system 2, reflected by the reflector 3, passes through the projection light lens 5, and irradiates the reflection type liquid crystal element 4. Needless to say, the irradiated light is a light having a spatially substantially uniform light flux, but is reflected by the reflective liquid crystal element 4 to have a different reflectance for each pixel of the reflective liquid crystal element 4. The light is reflected and becomes projection light including image information. The projection light is focused by the projection light lens 5 and forms an image on the screen 6.

As shown in FIG. 3, the reflection type liquid crystal element 4
The pixel unit 7 includes a data driver 8a and a scan driver 8b.

The data driver 8a includes a horizontal shift register 9a and an output GV of the horizontal shift register 9a.
_{1 ~GV n} connected to the gate terminal is image signal output MOS
Composed of a FETQV ₁ ~QV _n. Each output DO ₁ to DO _n data driver 8a is an image signal output MOSF
ETQV ₁ is the output of ~QV _n, only the time selected by the horizontal shift register 9a, the image signal input to the image signal input 10 is outputted.

The scan driver 8b includes a vertical shift register 9b and an output G of the vertical shift register 9b.
A that outputs the logical product of H _{1 to} GH _m and pulse input 11
Composed of the ND gate AND ₁ ~AND _m. Output SO ₁ to SO _m scan driver 8b is the output of the AND gate AND ₁ ~AND _m.

The pixel section 7 has MOSFETs Q _{11 to} Q _nm arranged in a two-dimensional array.

MOSFETs Q arranged in a line in the vertical direction
₁₁ a drain terminal of the to Q _m1 is connected to the output DO ₁ data driver 8a by a common wiring, likewise, MOS
Drain terminal of FETQ ₁₂ ~Q _m2 to the output DO _2, MO
The drain terminal of SFETQ _1n ~Q _mn are successively connected to the output DO _n.

MOSFETs Q arranged in a row in the horizontal direction
The gate terminals of _{11 to} Q _1n are connected to the output SO ₁ of the scan driver 8b by a common wiring.
The gate terminals of the FETs Q ₂₁ to Q _2n to output SO _2, MOS
The gate terminals of the FETs Q _m1 to Q _mn is sequentially connected to the output SO _m.

Further, liquid crystal capacitors C _{11 to} C _mn are connected to the source terminals of the MOSFETs of the respective pixel portions as an equivalent circuit of the liquid crystal. Although not shown, the liquid crystal capacitance C ₁₁ ~ in order to increase the time constant of the decay of charge accumulated in each pixel
A storage capacitor may be formed in parallel with C _mn .

In such a reflective liquid crystal element 4, the horizontal shift register 9a and the vertical shift register 9
The charge corresponding to the image signal voltage applied to the image signal input 10 is accumulated only in the liquid crystal capacitance corresponding to one pixel selected as b, and the light reflectance at that pixel is controlled.
One screen is formed at the stage where the accumulation of the electric charge for each pixel is performed in the horizontal direction and the vertical direction, and the accumulated electric charge is held until the next signal input. The operations of the horizontal shift register 9a and the vertical shift register 9b are synchronized by a synchronization signal input to the synchronization signal input 12.

Next, the element configuration of the pixel section 7 will be described with reference to FIG. Hereinafter, as a representative example of the pixel unit 7, a MOS
FETs Q ₁₁ only the pixel area corresponding to the will be described, it is needless to say that the same configuration applies to other pixel regions.

The pixel portion 7 includes a MOS transistor formed on a semiconductor substrate 13 made of silicon single crystal having a p-type conductivity.
And FETs Q _11, the liquid crystal driving voltage applying electrode 14 for applying a liquid crystal driving voltage that is formed above the MOSFET Q ₁₁
, NACP liquid crystal layer 15, and liquid crystal drive voltage applying electrode 1
And a common electrode 16 held at a ground potential and a glass substrate 17 supporting the common electrode 16. The common electrode 16 is a transparent electrode.
A TO film can be used. The light emitted from the light source 1 enters the glass substrate 17 and is reflected by the liquid crystal drive voltage application electrode 14 to become projection light.

The semiconductor substrate 13 has a field insulating film 18 as an element isolation region on its main surface, and the active region 1 on the main surface of the semiconductor substrate 13 surrounded by the field insulating film 18.
9 The, MOSFET Q ₁₁ is formed. Field insulating film 18 can be, for example, a silicon oxide film.

The MOSFET Q ₁₁ has a gate electrode 21 formed on the active region 19 via the gate insulating film 20,
It comprises a source region 22a and a drain region 22b formed in the active region 19 on both sides of the gate electrode 21. Gate electrode 21 is made of, for example, a polycrystalline silicon film, and source region 22a and drain region 22b are
This is an n-type impurity semiconductor region having a high concentration of the n-type impurity implanted in the active region 19. The gate electrode 21, a gate electrode of the array of MOSFET Q ₁₂ to Q _1n in a row in the other horizontal direction, the output SO of the scan driver 8b
Connected to ₁ .

The gate electrode 21 and the semiconductor substrate 13 are
Connection hole 2 covered with insulating film 23 and opened in insulating film 23 above source region 22a and drain region 22b.
4, wirings 25a and 25b are formed on the insulating film 23 in contact with the source region 22a and the drain region 22b, respectively. Insulating film 23 can be, for example, a silicon oxide film, and has a wiring 25a.
The wiring 25b can be formed, for example, of a metal containing aluminum as a main component. The wiring 25b is
The other MOSFETs Q _{21 to} Q arranged in a line in the vertical direction
together with wires connected to the drain electrode of _m1, is connected to the output DO ₁ data driver 8a.

An insulating film 26 having a flattened surface is formed on the wiring 25a and the wiring 25b, and a liquid crystal driving voltage is applied so as to be connected to the wiring 25a through a connection hole 27 opened in the insulating film 26. An electrode 14 is formed. The insulating film 26 is, for example, a silicon oxide film or PIQ
It can be a membrane. The reason why the surface of the insulating film 26 is flattened is to flatten the surface of the liquid crystal drive voltage applying electrode 14 formed on the upper surface thereof, to ensure a mirror surface, and to make the light reflection uniform. As described later, a CMP (Chemical Mechanical Polishing) method or the like can be used as the planarization method.

The electrode 14 for applying the liquid crystal driving voltage is connected to the wiring 25.
a and a titanium layer 14a, which is a first metal layer, in contact with the insulating film 26, and an aluminum alloy layer 14b, which is a second metal layer formed on and in contact with the titanium layer 14a. The thicknesses of the titanium layer 14a and the aluminum alloy layer 14b are, for example, 10 nm and 2 nm, respectively.
00 nm. Aluminum alloy layer 14
b is mainly composed of aluminum, and for example, silicon, copper, or the like is added for the purpose of suppressing the electromigration effect or reducing aluminum spikes. The liquid crystal drive voltage application electrode 14 has a function as an electrode for applying a drive voltage to the NACP liquid crystal layer 15 and also has a function as a reflector for the light emitted from the light source 1.

Although not shown, a silicon nitride film having a thickness of about 120 nm may be formed as a protective layer on the surface of the liquid crystal drive voltage applying electrode 14 and the insulating film 26.

According to such a liquid crystal display device of the present embodiment, the electrode 14 for applying the liquid crystal driving voltage is formed of the titanium layer 14a.
And an aluminum alloy layer 14b.
Since silicon contained in the aluminum alloy layer 14b can be diffused into the titanium layer 14a in a subsequent thermal process, generation of hillocks on the surface of the aluminum alloy layer 14b can be suppressed. As a result, the reflectance of the light emitted from the light source 1 on the surface of the liquid crystal drive voltage applying electrode 14 can be improved, and the luminance of the liquid crystal display device can be improved.

FIG. 9 is a graph showing the reflectance of the liquid crystal drive voltage applying electrode 14 with and without the titanium layer 14a in the liquid crystal drive voltage applying electrode 14, and illustrates the above effect. It is. FIG. 9A shows the titanium layer 1
4 shows a reflectivity 91 when having the titanium layer 14a and a reflectivity 92 when not having the titanium layer 14a, and is about 5% higher than the reflectivity 92 when the reflectance 91 does not have the titanium layer 14a. You can see that it is doing. FIG. 9B shows the reflectivity 93 and the aluminum disappearance rate 9 when the thickness ratio of the titanium layer 14a and the aluminum alloy layer 14b is changed.
4 is shown. When the ratio of the thickness of the titanium layer 14a to the thickness of the aluminum alloy layer 14b is changed in the range of 1:40 to 1:10, a large change in the reflectivity 93 is not recognized, but the titanium layer 14a with respect to the aluminum alloy layer 14b is not changed. When the film thickness ratio exceeds 3/40, the aluminum disappearance rate 94 sharply increases, and it can be seen that there is an optimum value for the film thickness ratio. In this case, it can be seen that the optimal range is a range of 1:40 to 3:40.

Next, a method for manufacturing the reflective liquid crystal element 4 will be described with reference to FIGS.

First, a semiconductor substrate 13 is prepared which is doped with an impurity exhibiting a p-type conductivity, for example, boron and has a surface of a [100] plane having a resistivity of several Ω · cm.
The main surface of the semiconductor substrate 13 is provided with a LOCOS (Local Oxid
field insulating film 18 by using the
Is formed, and the gate insulating film 20 is formed using a thermal oxidation method.
Is formed (FIG. 4).

Next, a gate electrode 21 is formed in the active region 19 on the main surface of the semiconductor substrate 13 surrounded by the field insulating film 18.
To form The gate electrode 21 is formed by a known CVD method.
(Chemical Vapor Deposition) technology, photolithography technology and etching technology can be used. Further, in the active region 19 on both sides of the gate electrode 21, an impurity semiconductor region having an n-type conductivity, which is to be the source region 22a and the drain region 22b, is formed (FIG. 5). Using the gate electrode 21 as a mask, the impurity semiconductor region can be formed, for example, by ion-implanting phosphorus and activating phosphorus by heat treatment. By using the gate electrode 21 as a mask as described above, the impurity semiconductor region can be formed in a self-aligned manner.

Next, an insulating film 23 made of a silicon oxide film is formed on the entire surface of the semiconductor substrate 13 on which the gate electrode 21 is formed, and a connection hole 24 is formed above the source region 22a and the drain region 22b. A known CVD method can be used to form the silicon oxide film, and a known photolithography technique and etching technique can be used to form the connection holes 24. Further, an aluminum alloy film (not shown) is formed on the entire surface of the insulating film 23 in which the connection holes 24 are formed, and the aluminum alloy film is patterned using a known photolithography technique and an etching technique to form wirings 25a and 25b. (FIG. 6). For forming the aluminum alloy film, a known sputtering method can be used.

Next, an insulating film (not shown) covering the wirings 25a and 25b is formed by using a known CVD method or the like.
The insulating film 26 is formed by flattening using an MP method or the like. Further, a connection hole 27 is formed in the insulating film 26 by using a known photolithography technique and an etching technique (FIG. 7). As the insulating film, a silicon oxide film can be used. Further, a PIQ film can be used as the insulating film. In this case, due to the step coverage of the PIQ film,
Since the surface is spontaneously flattened, there is an advantage that a flattening step is not required.

Next, a thin film to become the titanium layer 14a is deposited to a thickness of about 10 nm on the insulating film 26 by sputtering, and a thin film to become the aluminum alloy layer 14b is deposited by sputtering to a thickness of about 10 nm. Deposit with a thickness of 200 nm. At this time, after deposition of the thin film to become the titanium layer 14a, the pressure is kept at a reduced pressure without vacuum breaking until deposition of the thin film to become the aluminum alloy layer 14b. As a method of depositing a metal film of a different material while maintaining such a reduced pressure state, a method using a multi-chamber type sputtering apparatus,
Alternatively, a method using a multi-target sputtering apparatus can be exemplified. As the sputtering conditions,
For the titanium film, the substrate temperature was 200 ° C., the gas type was argon, the pressure was 30 mTorr, the input power was 1 kW for a 6-inch target, the processing time was 7 seconds,
For the aluminum alloy film, the substrate temperature was 200 ° C,
The conditions can be exemplified in which the gas type is argon, the pressure is 30 mTorr, the input power is 4 kW for a 6-inch target, and the processing time is 17 seconds.

Further, patterning is performed using a known photolithography technique and an etching technique to form a liquid crystal driving voltage application electrode 14 (FIG. 8). Thereafter, a silicon nitride film having a thickness of about 120 nm may be formed on the entire surface of the semiconductor substrate 13 on which the liquid crystal drive voltage application electrode 14 is formed to serve as a protective film.

Finally, the polymer liquid crystal NAC
A P liquid crystal layer 15 is formed by coating, and a glass substrate 17 on which a common electrode 16 made of ITO is formed is placed so that the common electrode 16 side is in contact with the NACP liquid crystal layer 15, and the reflective liquid crystal element 4 shown in FIG. Complete.

According to the liquid crystal display device using the reflection type liquid crystal element 4 manufactured by such a manufacturing method, the aluminum alloy layer 14b is formed after the thin film to be the titanium layer 14a is deposited.
In order to continuously form the liquid crystal drive voltage applying electrode 14 while maintaining the reduced pressure state without breaking the vacuum until the deposition of the thin film, the titanium layer 14a and the aluminum alloy layer 1
No oxide of titanium is formed at the interface with the aluminum alloy layer 4b, so that silicon contained in the aluminum alloy layer 14b can be effectively diffused into the titanium layer 14a. As a result, no hillocks are generated on the surface of the aluminum alloy layer 14b by the heat treatment process after the formation of the liquid crystal drive voltage applying electrode 14, and the reflectance of the light emitted from the light source 1 at the liquid crystal drive voltage applying electrode 14 is improved. In addition, the brightness of the liquid crystal display device can be improved.

In the above manufacturing method, the titanium layer 1
Even if the surface of the thin film 4a is oxidized by vacuum breaking after forming the thin film, the oxide film may be removed by sputter etching before depositing the thin film to be the aluminum alloy layer 14b. it can. The conditions of the sputter etch include the conditions of a substrate temperature of 200 ° C., a gas type of argon, a pressure of 30 mTorr, an input power of 0.38 kW for a 6-inch size electrode, and a processing time of 74 seconds. it can.

In such a case, as in the case of the above-described effect, the generation of hillocks on the surface of the aluminum alloy layer 14b is suppressed, the reflectance of the reflective liquid crystal element 4 is improved, and the luminance of the liquid crystal display device is improved. Can be. Further, even when the titanium layer 14a and the aluminum alloy layer 14b are continuously formed without breaking in a vacuum, sputter etching may be performed during that time.

Although the invention made by the inventor has been specifically described based on the embodiments of the present invention, the present invention is not limited to the above embodiments, and various modifications may be made without departing from the gist of the invention. Needless to say, it can be changed.

For example, in the present embodiment, an example was described in which titanium layer 14a was used as the first metal layer. However, the first metal layer is not limited to a titanium film, but has a solid solubility in silicon. A substance belonging to a high group IVB or VB may be used. For example, niobium, tantalum and the like can be exemplified.

[0066]

The effects obtained by typical ones of the inventions disclosed in the present application will be briefly described as follows.

(1) The projection light reflectance of the reflection type liquid crystal element can be improved, and the luminance of the liquid crystal display device can be improved.

(2) The occurrence of hillocks on the surface of the aluminum thin film of the electrode for applying the liquid crystal driving voltage of the reflective liquid crystal element can be suppressed, and the reflectance of the projection light of the electrode for applying the liquid crystal driving voltage can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing an example of a main part of a reflective liquid crystal element used in a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram illustrating a configuration example of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 illustrates a liquid crystal driving M of the reflective liquid crystal element according to the present embodiment.
FIG. 3 is a circuit diagram illustrating an example of an OSFET array and peripheral circuits thereof.

FIG. 4 is a cross-sectional view showing an example of a manufacturing process of a main part of a reflective liquid crystal element used in the liquid crystal display device according to one embodiment of the present invention.

FIG. 5 is a cross-sectional view showing an example of a manufacturing process of a main part of a reflective liquid crystal element used in the liquid crystal display device according to one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing an example of a manufacturing process of a main part of a reflective liquid crystal element used in the liquid crystal display device according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view illustrating an example of a manufacturing process for a main part of a reflective liquid crystal element used in the liquid crystal display device according to an embodiment of the present invention.

FIG. 8 is a cross-sectional view showing an example of a manufacturing process for a main part of a reflective liquid crystal element used in the liquid crystal display device according to one embodiment of the present invention.

9A and 9B are graphs showing the reflectance of a liquid crystal driving voltage application electrode, wherein FIG. 9A shows the reflectance with and without a titanium layer, and FIG. 9B shows the reflectance between a titanium layer and aluminum. It shows the reflectivity and the aluminum disappearance rate when the ratio of the film thickness to the alloy layer is changed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Light source 2 Optical system 3 Reflector 4 Reflective liquid crystal element 5 Projection light lens 6 Screen 7 Pixel part 8a Data driver 8b Scan driver 9a Horizontal shift register 9b Vertical shift register 10 Image signal input 11 Pulse input 12 Synchronization signal input 13 Semiconductor substrate 14 Liquid crystal drive voltage applying electrode 14a Titanium layer 14b Aluminum alloy layer 15 NACP liquid crystal layer 16 Common electrode 17 Glass substrate 18 Field insulating film 19 Active region 20 Gate insulating film 21 Gate electrode 22a Source region 22b Drain region 23 Insulating film 24 connection hole 25a wiring 25b wiring 26 insulating film 27 contact hole 91 reflectance 92 reflectance 93 reflectance 94 aluminum erasure rate DO ₁ to DO _n data driver output GV ₁ ~GV _n horizontal shift register output QV ₁ QV _n image signal output MOSFET SO ₁ to SO _m scanning driver output GH ₁ ~GH _m vertical shift register output AND ₁ ~AND _m AND gates C ₁₁ -C _mn liquid crystal capacitor Q ₁₁ to Q _mn MOSFET

Claims (5)

[Claims] A liquid crystal driving MOSFET disposed in a two-dimensional array on a main surface of a semiconductor substrate;
It is provided in an upper layer of an insulating film covering the ET, is electrically connected to a source region of the MOSFET through a connection hole opened in the insulating film, and reflects light passing through a liquid crystal layer provided in the upper layer. A liquid crystal display device having a reflective liquid crystal element including an electrode layer to which a voltage applied to the liquid crystal layer is applied at the same time as acting as a reflector, wherein the electrode layer has a high solid solubility in silicon. A liquid crystal display device, which is a stacked film including a first metal layer made of a material and a second metal layer containing aluminum as a main component and formed on the first metal layer. 2. The liquid crystal display device according to claim 1, wherein the first metal layer is made of a group IVB or group VB metal. 3. The liquid crystal display device according to claim 1, wherein the first metal layer is made of titanium. 4. The method for manufacturing a liquid crystal display device according to claim 1, wherein a vacuum process for forming the first metal layer and a vacuum process for forming the second metal layer are performed. Wherein the first and second metal layers are continuously formed while maintaining a vacuum state. 5. The method of manufacturing a liquid crystal display device according to claim 1, wherein the first metal layer is formed, and the first metal layer is formed before the second metal layer is formed. A method for manufacturing a liquid crystal display device, comprising: removing an oxide layer formed on the surface of the metal layer by sputtering.