JPH11111685A - Dry etching method, manufacture of semiconductor device and liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the residues of a film to be etched and particles by dry etching the film to be etched with a first etching gas and then switching the first etching gas to a second etching gas. SOLUTION: After a film to be etched is dry etched with a first etching gas, the first etching gas is switched to a second etching gas and dry etching of the film to be etched is continued. Consequently, residue and etching products which could not be removed by etching with the first etching gas are removed by the second etching gas, and the entire surface of a substrate can be cleaned. Preferably, by setting the vacuum level of the system higher than 20 mTorr at the time of etching with second etching gas in order to evacuate etching products adequately without leaving residues.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for etching a film to be etched.

[0002]

2. Description of the Related Art In recent years, in a display semiconductor device such as an active matrix type liquid crystal display device and a photoelectric conversion element such as a solar cell, it is necessary to transmit light through the device. The substance is used. In order to pattern a transparent electrode made of such a transparent conductive material into a predetermined shape, a dry etching method such as a wet etching method in which the electrode is immersed in a hydrochloric acid aqueous solution or a reactive ion etching method (Reactive Ion Etching: RIE) is used. Used.

However, in the wet etching method, since the etching is isotropically etched, lateral etching called side etching or undercut occurs, which is not very suitable for fine processing. Therefore, an RIE method, which is a dry etching method, is used. In the RIE method, the chamber is evacuated to a vacuum state, a reaction gas such as CF ₄ is put into the chamber, and high-frequency power is applied from a high-frequency power source, thereby causing discharge to generate plasma. In this plasma, the gas is dissociated by collisions with electrons whose electric field is accelerated, generating ions and extremely chemically active atoms and molecules. RI
The method E utilizes ions generated by dissociation of a reaction gas. When CF ₄ is used as a reaction gas, cations such as CF ₃ ⁺ and CF ₂ ⁺ are generated. The cations generated in this manner are accelerated by an electric field, and are made to collide with an object to be etched. Since such ion bombardment occurs only in the depth direction, the etching proceeds only in the vertical direction, resulting in anisotropic etching.

Japanese Patent Application Laid-Open No. 2-158129 (International Patent Classification; H01L 21/302) describes a technique for etching a transparent electrode film using the RIE method.
According to the technique described in the publication, an ITO film formed on an amorphous silicon film is etched by a RIE method using a mixed gas of chlorine (Cl ₂ ) and methane (CH ₄ ). I have.

[0005] However, in such an etching method, C and H contained in methane are dissociated by plasma injection, and a deposit composed of a compound containing C and H is generated. Since such a deposit adheres to the base of the ITO film and the wall surface in the chamber or floats in the chamber, there has been a problem that the film to be etched is contaminated.

[0006] Therefore, it is necessary to frequently clean the inside of the chamber, and this has hindered the manufacturing process.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional drawbacks, and has as its object to provide a dry etching method capable of performing uniform etching with little residue and particles of a film to be etched. And

[0008]

According to a first aspect of the present invention, there is provided a dry etching method, wherein after a film to be etched is dry-etched with a first etching gas, the first etching gas is switched to a second etching gas. Since the film to be etched is continuously dry-etched, residues and etching products that cannot be removed by etching with the first etching gas are removed by etching with the second etching gas, and the entire surface of the substrate is cleaned. be able to.

In the dry etching method according to the present invention, after the film to be etched is dry-etched with a first etching gas, the first etching gas is switched to a second etching gas, and the film to be etched is etched. A dry etching method for continuously performing dry etching, wherein at least the degree of vacuum of the system at the time of dry etching using the second etching gas is a degree of vacuum at which a film to be etched out of a predetermined shape remains in the film to be etched. Since it is a certain one, by making it sufficiently lower than in the case where the degree of vacuum is high, it is possible to exhaust a product by etching and leave no residue.

According to a third aspect of the present invention, in the dry etching method, after the film to be etched is dry-etched with a first etching gas, the first etching gas is switched to a second etching gas to dry the film to be etched. A dry etching method for successively performing dry etching, wherein at least the degree of vacuum of the system at the time of dry etching using the second etching gas is less than 20 mTorr. You can leave it.

According to a fourth aspect of the present invention, in the dry etching method according to the first aspect, the film to be etched is a film containing In ₂ O _3. Since it is an etching method, it is possible to easily etch even In ₂ O ₃ which is conventionally difficult to dry-etch. The dry etching method according to claim 5, wherein the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is a chlorine-based gas. or because it is a dry etching method according to any one of claims 4, one of HBr, HI reacts with in ₂ O _3, in ₂ B
r ₃ and Inl ₃ are generated and etched. The other Cl is I
nCl ₃ is generated and etched, and HBr, HI
The product containing C and H generated by the reaction with CCl ₂ ↑ and H ₂
{, HCl} can be decomposed and removed.

According to a sixth aspect of the present invention, in the dry etching method according to the fifth aspect, the chlorine-based gas is Cl ₂ or BCl ₃ , or a mixed gas thereof. , Accurate and clean etching can be performed. 7. The dry etching method according to claim 7, wherein the dry etching is reactive ion etching.
Since the dry etching method according to any one of the above, the reaction can be promoted by ion bombardment energy and energy can be given to the product to facilitate evaporation.

In the method of manufacturing a semiconductor device according to the present invention, after the film to be etched is dry-etched with a first etching gas, the first etching gas is switched to a second etching gas, and the etching is continued. Since it includes the step of dry etching the etching film,
Generation of defective semiconductor devices due to particles and residues can be prevented.

10. A method of manufacturing a semiconductor device according to claim 9, wherein a step of forming a semiconductor switching element having an electrode portion on a substrate, a step of forming an insulating film on the semiconductor switching element, Providing a contact hole at a position corresponding to the above, forming a transparent conductive film in the contact hole and on the insulating film, forming a resist of a desired pattern on the transparent conductive film, Dry-etching the transparent conductive film in the non-covered region with a first etching gas,
Switching the etching gas to the second etching gas to continuously dry-etch the transparent conductive film in the non-covered region. Therefore, it is possible to prevent the generation of a residue on the step portion.

According to a tenth aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: depositing a semiconductor film on a substrate, forming a gate insulating film on the semiconductor film, and forming a gate electrode on the gate insulating film. Forming, forming a drain and a source in the semiconductor film, forming an interlayer insulating film on the entire surface of the substrate, and providing a contact hole at a position of the interlayer insulating film corresponding to the drain and the source. Forming an electrode metal film in the contact hole and on the interlayer insulating film; forming an insulating protective film on the electrode metal film; and forming the electrode metal film in contact with the drain or source. Forming a contact hole at a corresponding position, forming a transparent conductive film over the entire surface of the substrate, and forming a resist of a desired pattern on the transparent conductive film And dry etching the transparent conductive film in the non-covered region of the resist with a first etching gas, and then switching the first etching gas to a second etching gas to change the transparent conductive film in the non-covered region. And a step of continuously dry-etching the film, so that a semiconductor device with improved characteristics can be obtained.

12. The method of manufacturing a semiconductor device according to claim 11, wherein: a step of depositing an amorphous semiconductor film on the substrate; a step of forming a gate insulating film on the semiconductor film; Polycrystallizing, forming a gate electrode on the gate insulating film, forming a drain and a source on the amorphous semiconductor film, and forming an interlayer insulating film on the entire surface of the substrate. Providing a contact hole in the interlayer insulating film at a position corresponding to the drain and the source; forming an electrode metal film in the contact hole and on the interlayer insulating film; Forming a protective film, forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source, and forming a transparent conductive film over the entire surface of the substrate. Forming a resist of a desired pattern on the transparent conductive film, and after dry-etching the transparent conductive film in an uncovered region of the resist with a first etching gas, Switching to the second etching gas and subsequently dry-etching the transparent conductive film in the non-covered region. Therefore, the amorphous semiconductor film is polycrystallized using the starting film. As a result, the generation of defective semiconductor devices due to particles and residues can be prevented, so that elements can be miniaturized.

In a twelfth aspect of the present invention, in the method of manufacturing a semiconductor device, the degree of vacuum at least when dry-etching with the second etching gas is less than 20 mTorr. Since the method for manufacturing a semiconductor device according to any one of the above, the product produced by the etching can be sufficiently exhausted to leave no residue, and the occurrence of a defective semiconductor device due to particles or residue can be prevented. Therefore, the element can be miniaturized.

The method of manufacturing a semiconductor device according to claim 13, wherein the film to be etched is a film containing In ₂ O _3.
Since the method of manufacturing a semiconductor device described in the above section, even when In ₂ O ₃ is used as an electrode, it can be applied to a display device that does not oxidize and requires light transmission.

According to a fourteenth aspect of the present invention, in the method of manufacturing a semiconductor device, the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is a chlorine-based gas. Since the method of manufacturing a semiconductor device according to any one of claims 8 to 11, one of HBr and HI reacts with In ₂ O ₃ to form In ₂ B
r ₃ and Inl ₃ are generated and etched. The other Cl is I
nCl ₃ is generated and etched, and HBr, HI
The product containing C and H generated by the reaction with CCl ₂ ↑ and H ₂
{, HCl} can be decomposed and removed.

[0020] The method of manufacturing a semiconductor device according to claim 15, wherein the chlorine-based gas, Cl2 or BCl ₃ or claim 14, characterized in that mixtures of these gases,
In the method of manufacturing a semiconductor device described in (1), accurate and clean etching can be performed. The method of manufacturing a semiconductor device according to claim 16, wherein the dry etching is reactive ion etching. 18. Therefore, it is suitable for manufacturing a semiconductor device which requires high processing accuracy and requires fine processing.

In the method of manufacturing a liquid crystal display device according to the present invention, after the film to be etched is dry-etched with a first etching gas, the first etching gas is subjected to a second etching.
A method of manufacturing a liquid crystal display device, comprising a step of dry-etching the film to be etched successively by switching to the etching gas of (1), so that a surface on which an alignment film for aligning liquid crystal is formed is flattened. And good orientation can be obtained.

A method of manufacturing a liquid crystal display device according to claim 18, wherein a step of forming a semiconductor switching element having an electrode portion on the first substrate and a step of forming an insulating film on the semiconductor switching element Providing a contact hole at a position corresponding to the electrode portion; forming a transparent conductive film in the contact hole and on the insulating film; and forming a resist having a desired pattern on the transparent conductive film. And after dry-etching the transparent conductive film in the uncoated region of the resist with a first etching gas,
A step of switching the first etching gas to a second etching gas to continuously dry-etch the transparent conductive film in the non-covered region, and a second substrate provided opposite to the first substrate. And a step of filling a liquid crystal substance, so that a surface on which an alignment film for aligning liquid crystal is formed can be flattened, good alignment can be achieved, and particles adhere to the surface of the transparent conductive film. In this case, when the alignment film formed on the surface of the transparent conductive film is rubbed, the particles are spread and the dirt is diffused. According to the present invention, this can be prevented.

20. The method of manufacturing a liquid crystal display device according to claim 19, wherein: a step of depositing a semiconductor film on the first substrate; a step of forming a gate insulating film on the semiconductor film; Forming a gate electrode on the semiconductor film, forming a drain and a source on the semiconductor film, forming an interlayer insulating film on the entire surface of the first substrate, and corresponding to the drain and the source of the interlayer insulating film. Providing a contact hole at a position; forming an electrode metal film in the contact hole and on the interlayer insulating film; forming an insulating protective film on the electrode metal film; Forming a contact hole at a position corresponding to the contacted electrode metal film; forming a transparent conductive film over the entire surface of the substrate; and forming a desired pattern on the transparent conductive film. Forming a resist, and after dry-etching the transparent conductive film in an uncovered region of the resist with a first etching gas, switching the first etching gas to a second etching gas to form the uncovered region. And a step of filling a liquid crystal material between a second substrate provided opposite to the first substrate.
Since an etching residue and particles are suppressed, a liquid crystal display device including a semiconductor having good characteristics can be obtained.

The method of manufacturing a liquid crystal display device according to claim 20, wherein a step of depositing an amorphous semiconductor film on the first substrate, a step of forming a gate insulating film on the semiconductor film, A step of polycrystallizing the amorphous semiconductor film, a step of forming a gate electrode on the gate insulating film, a step of forming a drain and a source on the amorphous semiconductor film,
Forming an interlayer insulating film over the entire surface of the substrate, providing a contact hole at a position corresponding to the drain and source of the interlayer insulating film, and forming an electrode metal film in the contact hole and on the interlayer insulating film. Forming an insulating protective film on the electrode metal film, forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source, and forming a transparent layer on the entire surface of the substrate. Forming a conductive film, forming a resist of a desired pattern on the transparent conductive film, and dry-etching the transparent conductive film in an uncoated region of the resist with a first etching gas; Switching the first etching gas to the second etching gas to continuously dry-etch the transparent conductive film in the non-covered region; Since the method includes a step of forming an electrode on a second substrate facing the plate and a step of filling a liquid crystal material between the first substrate and the second substrate, etching residues and particles are suppressed. Therefore, a liquid crystal display device including a semiconductor having good characteristics can be obtained.

According to a twenty-first aspect of the present invention, in the method of manufacturing a liquid crystal display device, the degree of vacuum of the system when dry etching is performed on the film to be etched after switching to at least the second etching gas is less than 20 mTorr. Since the method for manufacturing a liquid crystal display device according to any one of claims 17 to 20, the etching residue and particles are suppressed, and a surface on which an alignment film for aligning the liquid crystal is formed. Can be flattened and good alignment can be performed, so that a liquid crystal display device provided with a semiconductor having good characteristics can be obtained.

In the method for manufacturing a liquid crystal display device according to the present invention, the transparent conductive film is a film containing In ₂ O _3.
According to the method of manufacturing a liquid crystal display device described in the section, an etching residue and particles are suppressed, so that a liquid crystal display device including a semiconductor with good characteristics can be obtained. The method for manufacturing a liquid crystal display device according to claim 23, wherein the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is a chlorine-based gas. Since the method for manufacturing a liquid crystal display device according to any one of claims 17 to 21, the etching residue and particles are suppressed, so that a liquid crystal display device including a semiconductor with good characteristics can be obtained. .

The liquid crystal display device according to claim 23, wherein the chlorine-based gas is Cl ₂ or BCl ₃ , or a mixed gas thereof. Since the manufacturing method described above is used, an etching residue and particles are suppressed, so that a liquid crystal display device including a semiconductor having good characteristics can be obtained. Claim 2
22. The method of manufacturing a liquid crystal display device according to claim 5, wherein the dry etching is reactive ion etching. Therefore, it is possible to obtain a liquid crystal display device including a semiconductor device which has high processing accuracy and requires fine processing.

[0028]

FIG. 1 shows a case where the dry etching method of the present invention is applied to a polycrystalline silicon thin film transistor and a liquid crystal display device using the thin film transistor. Step 1 (FIG. 1A): A polycrystalline silicon film 2 is formed on an insulating substrate 1 made of a quartz glass substrate or the like by using a low pressure CVD method. In order to use the polycrystalline silicon film 2 as an active layer of a thin film transistor, it is processed into a predetermined shape, for example, an island shape by a photolithography process or the like.

In the step 1, the polycrystalline silicon film 2 is formed on the insulating substrate 1, but the present invention is not limited to this. An amorphous silicon film is formed on the insulating substrate 1 and solid-phase growth is performed. Thus, the polycrystalline silicon film 2 may be formed. Step 2 (FIG. 1B): Then, H as a gate insulating film 3 is formed on the polycrystalline silicon film 2 by a low pressure CVD method.
A TO film (High Temperature Oxide: silicon oxide film) is formed.

Step 3 (FIG. 1C): After a polycrystalline silicon film 4 is deposited on the gate insulating film 3 by a low pressure CVD method, impurities are implanted into the polycrystalline silicon film 4 to further perform a heat treatment. To activate the impurities. Next, normal pressure CVD
A silicon oxide film 5 is deposited on polycrystalline silicon film 4 by a method. Next, the polycrystalline silicon 4 and the silicon oxide film 5 are patterned into a predetermined shape by using a photolithography technique and a dry etching technique by an RIE method. This polycrystalline silicon film 4 becomes the gate electrode 4.

An HTO film as an insulating film is formed on the gate insulating film 3 and the silicon oxide film 5 by a low pressure CVD method. This is anisotropically etched back to form sidewalls 6 on the side surfaces of the gate electrode 4 and the silicon oxide film 5. Next, impurities are implanted into the source region 8 and the drain region 9 in the polycrystalline silicon film 2 by a self-alignment technique, and a heat treatment is performed to activate the impurities.

Step 4 (FIG. 1D): The side walls 6 and the silicon oxide film 5 are covered with a resist film 10, and impurities are implanted into the polycrystalline silicon film 2 using the resist film 10 as a mask. As a result, a region having a lower concentration than the source region 8 and the drain region 9, that is, an LDD (Lightly Do
A ped drain region 7 is formed, and a TFT having an LDD structure can be formed.

Step 5 (FIG. 2E): After the resist film 10 is removed, a silicon oxide film 11 and a fluid BPSG film (a part of the interlayer insulating film) are formed on the entire surface of the device by normal pressure CVD. 12) are deposited successively. Next, it is placed in an electric furnace and heated to 900 ° C. to reflow the BPSG film. The heat treatment at this time activates the source region 8 and the drain region 9 at the same time.

Through the above steps, a thin film transistor is formed. Since the BPSG film 12 has poor peelability of the resist film and easily absorbs moisture, a silicon oxide film is further deposited on the BPSG film as a protective film by a normal pressure CVD method. As described above, the silicon oxide film / BPSG
An interlayer insulating film 13 made of a film / silicon oxide film is formed.

Next, it is placed in an electric furnace and heated at a temperature of 450 ° C. for 12 hours in a hydrogen atmosphere to perform a hydrogen plasma treatment.
By performing such hydrogen treatment, hydrogen atoms are bonded to crystal defect portions of the polycrystalline silicon film, so that the crystal structure is stabilized and the field effect mobility is increased. Step 6 (FIG. 2F): A contact for making contact between a transparent electrode described later and the source region 8 and the drain region 9 at a position of the interlayer insulating film 13 corresponding to the source region 8 and the drain region 9. A contact hole 14 is formed.

Thereafter, a wiring layer 15 in which an Al—Si alloy and Ti are laminated is formed on the contact hole 14 and the interlayer insulating film 13. Step 7 (FIG. 2G): The wiring layer 15 is dry-etched by photolithography and RIE to form a source electrode 16.
And the drain electrode 17. Step 8 (FIG. 2H): Then, a protective film 18 made of a silicon oxide film is formed on the entire surface of the device by a normal pressure CVD method. In the silicon oxide film 18, a contact hole 19 that contacts the source electrode 16 is formed by photolithography and dry etching.

Step 9 (FIG. 3I): Next, a transparent conductive film 20 made of an ITO film is formed on the entire surface of the device including the silicon oxide film 18 and the inside of the contact hole 19 by sputtering. This ITO film is to be the pixel electrode 20 '. Step 10 (FIG. 3 (j)): Then, the transparent conductive film 20
A resist film 21 is applied thereon to form a predetermined electrode pattern.

In this state, the exposed transparent conductive film 20 is etched by a dry etching method, for example, the RIE method using HBr gas as a first etching gas. Subsequently, HBr is changed to Cl ₂ gas as a _second etching gas, and etching is performed to the end. Step 11 (FIG. 3 (k)): After etching, resist film 2
1 is removed to form the pixel electrode 20 ', and a TFT (Thin Film Transistor) substrate on one side of the liquid crystal display device is completed.

The case where the above-mentioned TFT substrate is used for a liquid crystal display device will be described below. FIG. 4 is a partial cross-sectional view of the liquid crystal display device. A counter electrode substrate 22 is provided at a position facing the above-described TFT substrate. On the counter electrode substrate 22, a counter electrode 23 made of an ITO film or the like is formed in order.
In the case of the active matrix type, the counter electrode 23 is formed as a common electrode on the entire surface of the substrate. An alignment film 24 made of polyimide or the like for aligning the liquid crystal is formed thereon.
An alignment film 24 made of polyimide or the like is also formed on the TFT substrate 1 manufactured by the above-described manufacturing method.

The two substrates are bonded to each other between and around the completed counter electrode substrate 22 and the TFT substrate 1 using a sealing agent 25 made of an adhesive resin. Then, as shown in the schematic sectional view of the liquid crystal display device shown in FIG. 5, a liquid crystal material 26 is filled between the two substrates to complete a liquid crystal display (LCD). Since FIG. 5 is a schematic diagram, all TFTs manufactured by the above-described manufacturing method are not described. Therefore, it is different from the actual number.

FIG. 6 is a block diagram of an active matrix type LCD according to this embodiment. In the pixel section 30, each scanning line (gate wiring) G1... Gn, Gn + 1.
..Gm and each data wiring (drain line) D1... D
n, Dn + 1... Dm. Each gate line and data line are orthogonal to each other, and a pixel 31 is provided at the orthogonal portion. Each gate wiring is connected to a gate driver 32 so that a gate signal (scanning signal) is applied. Each drain wiring is connected to a drain driver (data driver) 33 so that a data signal (video signal) is applied. A peripheral drive circuit 34 is configured by these drivers 32 and 33.

An LCD in which at least one of the drivers 32 and 33 is formed on the same substrate as the pixel unit 30 is generally a driver integrated type (built-in driver type).
It is called CD. Note that the gate driver is used for the pixel portion 3.
0 may be provided at both ends. Further, the drain driver 33 may be provided at both ends of the pixel unit 30 in some cases.

The switching element of the peripheral drive circuit 34 also uses a polycrystalline silicon TFT manufactured by the same manufacturing method as that of the polycrystalline silicon TFT. Formed. The polycrystalline silicon TFT for the peripheral drive circuit
Adopts an ordinary single drain structure instead of an LDD structure (of course, it may have an LDD structure).

The polycrystalline silicon TFT of the peripheral driving circuit is formed in a CMOS structure, thereby realizing a reduction in the size of each driver. FIG. 7 shows an equivalent circuit of a pixel 31 provided at a portion orthogonal to the gate line Gn and the drain line Dn. The pixel 31 includes a TFT as a pixel driving element, a liquid crystal cell LC, and an auxiliary capacitance Cs. The gate of the TFT is connected to the gate wiring Gn, and the drain of the TFT is connected to the drain wiring Dn. The liquid crystal cell LC is used as the source of the TFT.
Are connected to an auxiliary capacitance (additional capacitance) Cs.

The liquid crystal cell LC and the storage capacitor Cs form a signal storage element. The voltage Vcom is applied to the common electrode (the electrode on the opposite side of the display electrode) of the liquid crystal cell LC. On the other hand, in the auxiliary capacitance Cs, a constant voltage VR is applied to an electrode on the side opposite to the side connected to the source of the TFT. The common electrode of the liquid crystal cell LC is an electrode which is literally common to all the pixels 31.
In the auxiliary capacitance Cs, the electrode on the side opposite to the side connected to the source of the TFT may be connected to the adjacent gate line Gn + 1 in some cases.

In the pixel 31 thus configured,
When a positive voltage is applied to the gate of the TFT by setting the gate line Gn to a positive voltage, the TFT turns on. Then, the capacitance of the liquid crystal cell LC and the auxiliary capacitance Cs are charged by the data signal applied to the drain wiring Dn. Conversely, when the gate line Gn is set to a negative voltage and a negative voltage is applied to the gate of the TFT, the TFT is turned off, and the voltage applied to the drain line Dn at that time becomes the capacitance and the auxiliary capacitance of the liquid crystal cell LC. Cs. As described above, by supplying the data signal to be written to the pixel to the drain wiring Dn and controlling the voltage of the gate wiring, an arbitrary data signal can be held in the pixel. The transmittance of the liquid crystal cell LC changes according to the data signal held by the pixel, and the pixel is displayed.

Here, the important characteristics of the pixel are:
There are writing characteristics and holding characteristics. What is required for the writing characteristics is that the signal storage elements (the liquid crystal cell LC and the storage capacitor C
The point is whether a desired video signal voltage can be sufficiently written to s). What is required for the holding characteristics is whether the video signal voltage once written in the signal storage element can be held for a required time. The auxiliary capacitance Cs is provided to improve the writing characteristics and the holding characteristics by increasing the capacitance of the signal storage element. That is, in the liquid crystal cell LC, there is a limit to the increase in capacitance due to its structure.
Therefore, the insufficient capacitance of the liquid crystal cell LC is compensated for by the auxiliary capacitance Cs. Here, a dry etching apparatus used in the present invention will be described.

FIG. 8 is a schematic sectional view of a dry etching apparatus used in the present invention. As shown in the figure, the chamber is provided with a cathode electrode substrate provided with a film to be etched, for example, a glass substrate, and an anode electrode substrate facing the cathode electrode substrate. Cooling water for adjusting the substrate temperature is circulated inside the cathode electrode substrate. Further, an etching gas for etching the film to be etched can be introduced into the anode electrode substrate.

The chamber is evacuated to a vacuum after the film to be etched is disposed, and then a high-frequency power is applied to the cathode electrode from a high-frequency power supply to generate a discharge and generate plasma. The introduced gas is dissociated to generate ions and the like, which are accelerated by the electric field and collide with the film to be etched on the cathode electrode substrate to etch the film to be etched.

Here, the relationship between the temperature of the cathode electrode of the dry etching apparatus and the etching rate of the film to be etched will be described. FIG. 9 shows the relationship between the etching rate and the substrate temperature. As shown in the figure, the horizontal axis shows the temperature of the cathode electrode, and the vertical axis shows the etching rates of the film to be etched and the ITO film.

According to the figure, it is understood that the etching rate is constant irrespective of the temperature of the cathode electrode. That is, it is found that the etching rate of the film to be etched does not depend on the cathode electrode temperature. Next, the relationship between the degree of vacuum in the chamber and the etching rates of the film to be etched and the ITO film will be described.

FIG. 10 shows the relationship between the degree of vacuum in the chamber and the etching rates of the film to be etched and ITO.
As shown in the figure, the horizontal axis indicates the degree of vacuum in the chamber,
The vertical axis indicates the etching rate of the ITO film. According to the figure, it can be seen that the etching rate of the film to be etched is substantially constant regardless of the degree of vacuum in the chamber. That is, it is understood that the etching rate of the film to be etched does not depend on the degree of vacuum in the chamber.

Further, the relationship between the degree of vacuum and the residue during the etching of the film to be etched will be described. FIG. 11 is a table showing the relationship between the conditions etched by the dry etching method of the present invention and the residues of the film to be etched.
2 shows a graph in which the values are plotted.

The values in the table shown in FIG. 11 are the results of measuring the residue, which is the remaining thickness of the ITO film after etching the ITO film with the first etching gas and then etching with the second etching gas. is there. As shown in FIGS. 11 and 12, the horizontal axis represents the degree of vacuum in the chamber when the dry etching is performed using the first etching gas and then the ITO film is etched using the second etching gas. Represents the thickness of the residue at each degree of vacuum.

It can be clearly seen that the thickness of the residue is very large when the degree of vacuum in the chamber during etching with the second etching gas is 20 mTorr or more, but becomes very small when the degree of vacuum is less than 20 mTorr. Here, the residue of the ITO film, which is a transparent conductive film, is obtained by etching with a second etching gas, observing a cross-sectional SEM, and measuring the thickness of the remaining ITO film.

Further, HBr is used as the first etching gas.
And Cl2 gas was used as the second etching gas. In the present invention, as the transparent conductive film of the film to be etched, in addition to the ITO film, In2O3 (indium oxide)
There are transparent conductive films such as films, SnO2 (tin oxide) films, and ZnO (zinc oxide) films.

Here, the SEM of the surface of the ITO film before and after etching by the dry etching method of the present invention was used.
The photograph is shown in FIG. 13A shows the surface of the etched ITO film when the degree of vacuum in the chamber at the time of etching is 20 mTorr, and FIG. 13B shows the state where the degree of vacuum at the time of etching is 30 mTorr.
The surface of the state where the ITO film is etched at the time of rr is shown.

As shown in the figure, one area (a) has an IT
The region where the O film is etched, and the other region (b) is IT
The ITO film remains in the region where the O film was covered with the resist film at the time of etching, and a step is generated from the region (a). In the area (a) of FIG.
The surface is flat with no residue of the film (it looks uniform black without any white spots in the figure). Therefore, it is understood that the ITO film has been completely etched. On the other hand, the ITO film remains in the region shown in FIG. 3B and has irregularities (white spots, which are residues of the ITO film, are seen in the drawing).

Next, the degree of vacuum in the chamber at the time of etching and the variation in the remaining ITO film after etching will be described. FIG. 14 shows the relationship between the degree of vacuum in the chamber and the in-plane variation of the residue (surface thickness) of the film to be etched. As shown in the figure, the horizontal axis indicates the degree of vacuum in the chamber, and the vertical axis indicates the variation in the etching rate in the plane. The variation is shown as a ratio (%) of the variation to the average value of the thickness of each point in the plane.

According to the figure, the degree of vacuum in the chamber is 3
It can be seen that when the pressure reaches 0 mTorr, the variation becomes about two to three times more than when the variation is less than 30 mTorr. That is, it is understood that when the pressure is 30 mTorr or more, a portion where the product produced by the etching is hardly exhausted is formed in the surface, and a portion where an extremely large amount of residue is generated is generated.

Here, FIG. 15 shows a film I to be etched.
The number of etching treatments on the substrate provided with the TO film and the number of particles (size 0. 0) due to the re-adhesion of the etching substance on the 6-inch wafer after etching (excluding the surrounding area of 5 mm).
3 to 10 μm). As shown in the figure, the horizontal axis indicates the number of processed sheets, and the vertical axis indicates the number of particles.

An ITO film having a thickness of 2000 Å was formed on the substrate on which the TFT was formed with an insulating film interposed therebetween, followed by dry etching with HBr and then etching with Cl ₂ gas. From the figure, it can be seen that no increase in particles is observed even after processing 100 sheets. This is because the generation of particles was suppressed by performing dry cleaning using Cl ₂ gas after etching the ITO film using HBr.

The above is summarized as follows. (1) The thickness of the residue is very large when the degree of vacuum in the chamber at the time of etching with the second etching gas is 20 mTorr or more, but becomes very thin when the degree of vacuum is less than 20 mTorr. (2) When the degree of vacuum in the chamber becomes 30 mTorr, the variation in the substrate becomes larger than when it is less than 30 mTorr.

(3) No increase in particles is observed even when a large number of sheets are processed. (4) The etching rate of the film to be etched is substantially constant regardless of the degree of vacuum in the chamber. (5) The etching rate is almost constant irrespective of the temperature of the cathode electrode. From these facts, it can be seen that by switching from the first etching gas to the second etching gas and setting the degree of vacuum at the time of etching to less than 20 mTorr, no residue is left and no particles are generated. In the above-described embodiment, the active matrix type liquid crystal display device has been described. However, the present invention can be applied to a known simple matrix type liquid crystal display device.

[0065]

According to the present invention, the characteristics of the semiconductor device and the liquid crystal display device can be improved because no residue remains after the etching of the film to be etched.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing an embodiment of the present invention.

FIG. 2 is a process sectional view showing one embodiment of the present invention.

FIG. 3 is a process sectional view showing an embodiment of the present invention.

FIG. 4 is a sectional view showing one embodiment of the present invention.

FIG. 5 is a sectional view showing an embodiment of the present invention.

FIG. 6 is a block diagram showing an embodiment of the present invention.

FIG. 7 is an equivalent circuit diagram showing an embodiment of the present invention.

FIG. 8 is a schematic sectional view of an etching apparatus showing one embodiment of the present invention.

FIG. 9 is a characteristic diagram showing one embodiment of the present invention.

FIG. 10 is a characteristic diagram showing one embodiment of the present invention.

FIG. 11 is a characteristic diagram showing one embodiment of the present invention.

FIG. 12 is a characteristic diagram showing one embodiment of the present invention.

FIG. 13 is a perspective photograph showing an embodiment of the present invention.

FIG. 14 is a characteristic diagram showing one embodiment of the present invention.

FIG. 15 is a characteristic diagram showing one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 TFT substrate 20 ITO film 20 'Pixel electrode 22 Counter electrode substrate

Claims (25)

[Claims] 2. The method according to claim 1, wherein after the film to be etched is dry-etched with a first etching gas, the first etching gas is switched to a second etching gas and the film to be etched is continuously dry-etched. Dry etching method. 2. A dry etching method in which a film to be etched is dry-etched with a first etching gas, and then the first etching gas is switched to a second etching gas to continuously dry-etch the film to be etched. Wherein at least the degree of vacuum of the system at the time of dry etching using the second etching gas is a degree of vacuum that does not leave a film to be etched out of a predetermined shape among the films to be etched. . 3. A dry etching method in which a film to be etched is dry-etched with a first etching gas, and then the first etching gas is switched to a second etching gas to dry-etch the film to be etched. The vacuum degree of the system at least during dry etching using the second etching gas is 20 mTorr.
r is less than r. 4. The dry etching method according to claim 1, wherein the film to be etched is a film containing In ₂ O ₃ . 5. The method according to claim 1, wherein the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is
The dry etching method according to claim 1, wherein the dry etching method is a chlorine-based gas. 6. The chlorine-based gas is Cl ₂ or BC
The dry etching method according to claim 5, wherein the dry etching method is l ₃ or a mixed gas thereof. 7. The method according to claim 1, wherein the dry etching is reactive ion etching.
The dry etching method according to claim 1. 8. A method of dry-etching a film to be etched with a first etching gas, switching the first etching gas to a second etching gas, and continuously dry-etching the film to be etched. A method for manufacturing a semiconductor device. 9. A step of forming a semiconductor switching element having an electrode on a substrate, a step of forming an insulating film on the semiconductor switching element, and a step of providing a contact hole at a position corresponding to the electrode. Forming a transparent conductive film in the contact hole and on the insulating film; forming a resist of a desired pattern on the transparent conductive film; After dry etching with 1 etching gas,
Switching the first etching gas to a second etching gas and subsequently dry-etching the transparent conductive film in the non-covered region. 10. A step of depositing a semiconductor film on a substrate;
Forming a gate insulating film on the semiconductor film, forming a gate electrode on the gate insulating film, forming a drain and a source on the semiconductor film, and forming an interlayer insulating film on the entire surface of the substrate Forming a contact hole at a position corresponding to the drain and source in the interlayer insulating film; forming an electrode metal film in the contact hole and on the interlayer insulating film; Forming an insulating protective film, forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source, and forming a transparent conductive film over the entire surface of the substrate; Forming a resist of a desired pattern on the transparent conductive film, and dry-etching the transparent conductive film in an uncoated region of the resist with a first etching gas; After grayed, a step of continuing dry etching a transparent conductive film of the uncoated region by switching the first etching gas in the second etching gas,
A method for manufacturing a semiconductor device including: 11. A step of depositing an amorphous semiconductor film on a substrate, a step of forming a gate insulating film on the semiconductor film,
Polycrystallizing the amorphous semiconductor film; forming a gate electrode on the gate insulating film; forming a drain and a source on the amorphous semiconductor film; Forming a film, providing a contact hole in the interlayer insulating film at a position corresponding to the drain and source, forming an electrode metal film in the contact hole and on the interlayer insulating film, Forming an insulating protective film on a metal film, forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source, and forming a transparent conductive film on the entire surface of the substrate Forming a resist of a desired pattern on the transparent conductive film, and dry-etching the transparent conductive film in an uncoated region of the resist with a first etching gas. After packaging, a method of manufacturing a semiconductor device comprising the steps of subsequently dry-etching a transparent conductive film of the uncoated region by switching the first etching gas in the second etching gas. 12. The degree of vacuum at least when dry-etching with the second etching gas is 20 mTorr.
The method of manufacturing a semiconductor device according to claim 8, wherein: 13. The method according to claim 8, wherein the film to be etched is a film containing In ₂ O ₃ . 14. The method according to claim 8, wherein the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is a chlorine-based gas. A method for manufacturing a semiconductor device according to claim 1. 15. The method according to claim 15, wherein the chlorine-based gas is Cl ₂ or B
15. The method according to claim 14, wherein the gas is Cl ₃ or a mixed gas thereof. 16. The method according to claim 8, wherein the dry etching is reactive ion etching. 17. A method of dry-etching a film to be etched with a first etching gas, switching the first etching gas to a second etching gas, and continuously dry-etching the film to be etched. A method for manufacturing a liquid crystal display device characterized by the above-mentioned. 18. A step of forming a semiconductor switching element having an electrode portion on a first substrate, a step of forming an insulating film on the semiconductor switching element, and forming a contact hole at a position corresponding to the electrode portion. Providing, forming a transparent conductive film in the contact hole and on the insulating film, forming a resist of a desired pattern on the transparent conductive film, and forming a transparent conductive film in an uncoated region of the resist. A step of dry-etching the film with a first etching gas, switching the first etching gas to a second etching gas, and continuously dry-etching the transparent conductive film in the uncovered region; Filling a liquid crystal material between the substrate and a second substrate provided so as to face the liquid crystal display device. 19. A step of depositing a semiconductor film on a first substrate, a step of forming a gate insulating film on the semiconductor film,
Forming a gate electrode on the gate insulating film, forming a drain and a source on the semiconductor film, forming an interlayer insulating film on the entire surface of the first substrate; And providing a contact hole at a position corresponding to the source, and forming an electrode metal film in the contact hole and on the interlayer insulating film,
Forming an insulating protective film on the electrode metal film, and forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source,
A step of forming a transparent conductive film on the entire surface of the substrate, a step of forming a resist having a desired pattern on the transparent conductive film, and a step of etching the transparent conductive film in an uncoated region of the resist with a first etching gas After dry etching, the first
Switching the etching gas to the second etching gas to continuously dry-etch the transparent conductive film in the non-covered region; and interposing a liquid crystal substance between the second substrate provided opposite to the first substrate. And a filling step. 20. A step of depositing an amorphous semiconductor film on a first substrate, a step of forming a gate insulating film on the semiconductor film, and a step of polycrystallizing the amorphous semiconductor film; Forming a gate electrode on the gate insulating film, forming a drain and a source on the amorphous semiconductor film,
Forming an interlayer insulating film on the entire surface of the first substrate, providing a contact hole at a position corresponding to the drain and source of the interlayer insulating film, and forming an electrode metal in the contact hole and on the interlayer insulating film. Forming a film; forming an insulating protective film on the electrode metal film; forming a contact hole at a position corresponding to the electrode metal film in contact with the drain or source; Forming a transparent conductive film on the entire surface;
Forming a resist of a desired pattern on the transparent conductive film, and dry-etching the transparent conductive film in an uncovered region of the resist with a first etching gas; Switching to an etching gas, and subsequently dry-etching the transparent conductive film in the non-covered region; forming an electrode on a second substrate facing the first substrate; Filling a liquid crystal material between the second substrate and the second substrate. 21. The system according to claim 17, wherein the degree of vacuum in the system when the film to be etched is continuously dry-etched at least after switching to the second etching gas is less than 20 mTorr. 2. The method for manufacturing a liquid crystal display device according to claim 1. 22. The method for manufacturing a liquid crystal display device according to claim 17, wherein said transparent conductive film is a film containing In ₂ O ₃ . 23. The method according to claim 17, wherein the first etching gas is hydrogen bromide or hydrogen iodide, and the second etching gas is a chlorine-based gas. A method for manufacturing the liquid crystal display device according to claim 1. 24. The chlorine-based gas is Cl ₂ or BC
l ₃ or The method according to claim 23, characterized in that mixtures of these gases. 25. The method according to claim 17, wherein the dry etching is reactive ion etching.