JPH07335120A - Manufacture of field emission micro-cathode - Google Patents

Abstract

PURPOSE:To provide a manufacturing method for a micro-cathode in a uniform shape and uniform height. CONSTITUTION:In order to reduce the dispersion of shapes of micro-chip cathodes, in the final stage of etching of an insulating layer 32, a process is switched to an anti-resist high selection etching step, and the rownding of a conductive layer 35 positioned in the lower layer of a resist film 38 is suppressed. As the technique for switching the condition, a technique varying the flow rate of etching gas, a technique varying the distance between a board 106 and plasma for etching, and a technique varying the exposed surface area of a silicon constituting material 110 set in an etching device are included. In addition, a technique varying the kind of etching gas (so as to contain sulfur for example), or a technique varying the exposed surface area of the constituting material 110 containing sulfur set in the etching device is included.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method for manufacturing a field emission type microcathode which can be used as, for example, a flat panel display or an image pickup device.

[0002]

2. Description of the Related Art Flat-panel displays have been attracting attention in recent years as a substitute for cathode ray tubes as display devices for small computers or word processors, wall-mounted televisions, and the like. Among them, the field emission display (FED) can realize high brightness and high-speed response, and therefore has characteristics superior to those of the currently mainstream liquid crystal displays.

In manufacturing this FED, it is necessary to fabricate a large number of field emission type microcathodes in an array on the surface of the substrate. The key technology of the manufacturing process in FED is the formation process of field emission type micro cathode. The field emission type microcathode is a cone-shaped acute-angled cathode, but as shown in FIG. 5, it is manufactured by applying the manufacturing process technology of the semiconductor device according to the conventional example.

An outline of a method of manufacturing a field emission type microcathode according to a conventional example will be described with reference to FIG. Figure 5 (A)
As shown in, the tungsten silicide film 3, the silicon oxide film 4, the polysilicon film 6 and the tungsten silicide film 8 are sequentially formed on the silicon substrate 2. A resist film 10 is formed thereon, and the resist film 10 is patterned with a pattern corresponding to the cathode hole by a photolithography method to form an opening 12.

Next, as shown in FIG.
First, the tungsten silicide film 8 and the polysilicon film 6 are R
Etching is performed by IE or the like. Next, using the same resist film 10 as a mask, the silicon oxide film 4 is etched to form a cathode hole 16 as shown in FIG.

Next, as shown in FIG. 2D, the resist film 10 is removed, and as shown in FIG. 2E, an aluminum layer 18 which is a peeling layer is formed on the tungsten silicide film 8. To film. After that, as shown in FIG. 6F, a molybdenum (Mo) layer 22 is formed on the entire surface of the silicon substrate 2 by a sputtering method or a vapor deposition method. At that time, a microcathode 20 having a sharp tip conical tip made of Mo is formed on the tungsten silicide film 3 in the cathode hole 16 formed in the silicon oxide film 4.

After that, as shown in FIG. 1G, when the aluminum layer 18 which is a peeling layer is removed by wet etching, the Mo layer 22 deposited on the aluminum layer 18 is also removed and the inside of the cathode hole 16 is removed. The microcathode 20 remains. After that, a transparent substrate having a phosphor film or a transparent substrate having a transparent conductive film formed thereon is bonded to the silicon substrate 2 in a vacuum state to form an FED or an image sensor.

Electrons are emitted from the microcathode 20 toward the transparent substrate to be bonded by scanning the grid electrode composed of the tungsten silicide film 8 or the like, and functions as an FED or an image pickup device. Therefore, the shape, especially the height, of the microcathode 20 needs to be uniform, and if they are formed nonuniformly, the emission current becomes unstable, which may cause a pixel defect.

[0009]

However, it has been difficult to form these microcathodes with a uniform shape and height by the conventional method for producing microcathodes. The reason will be described below.

What greatly influences the shape of the microcathode is the coverage when the Mo layer 22 is formed by the sputtering method or the like. This coverage is very sensitive to changes in the shape of the tungsten silicide film 8 that is the base of the Mo layer 22. The change in shape of the tungsten silicide film 8 is caused by the opening 12 of the resist film 10 based on the etching process of the silicon oxide film 4 shown in FIGS.
The cause is the tapering of the tape.

That is, by this etching process, the resist film 10 is also etched, the shape of the opening 12 is changed, and a shoulder drop portion or a taper portion is formed in the opening portion of the tungsten silicide film, which causes the microcathode. The problem is that the height or shape of the For example, when the opening of the tungsten silicide film 8 has a tapered shape, as shown in FIG.
2 changes, the time until the opening of the Mo layer 22 closes increases, and the microcathode 20 formed in the cathode hole 16 corresponding to the portion where the opening does not close.
Is higher than other parts.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for producing a microcathode capable of forming a microcathode having a uniform shape and height.

[0013]

The present inventor has diligently studied a method for producing a microcathode capable of forming a microcathode having a uniform shape and height, and as a result, reduced variations in microtip cathode shape. In order to achieve this, it was found that it is preferable to switch to a resist high-selective etching step at the end of the etching of the insulating layer to suppress shoulder drop of the conductive layer located under the resist film.

The present invention has been made based on the above findings, and when forming a cathode hole in an insulating layer, the conditions in the etching apparatus are set so that a high resist-to-resist ratio condition is obtained at the end of etching of the insulating layer. It is characterized by switching. As a method of switching the conditions in the etching apparatus so that the above high resist-to-resist ratio condition is achieved, a method of changing the flow rate ratio of the etching gas, a method of changing the distance between the substrate and the etching plasma, and A method of changing the exposed surface area of the installed silicon-based component, a method of changing the type of etching gas (for example, so that the etching gas contains sulfur), or A method of changing the exposed surface area can be exemplified.

In the present invention, the term "end of etching the insulating layer" means that when the cathode hole is formed in the insulating layer, the cathode hole is formed in the insulating layer at a depth of at least about 1/3 of the layer thickness. This means the subsequent etching. The etching apparatus used in the present invention is not particularly limited,
Plasma etching equipment is preferred. Examples of the plasma etching device include a microwave electron cyclotron resonance plasma (ECR) etching device, an induction coil type plasma (ICP) etching device, a helicon wave utilizing plasma etching device, and a transformer coupled plasma (TC).
P) An etching device or the like can be exemplified. In the plasma etching apparatus of the present invention, the higher the plasma density that can be generated, the more effective the generation of halogen elements such as fluorine (F) and sulfur (S).

[0016]

According to the present invention, when the cathode holes are formed in the insulating layer, the conditions in the etching apparatus are switched so that the conditions for the high resist selectivity ratio are satisfied at the end of the etching of the insulating layer.

One method for switching the conditions in the etching apparatus so that the high resist-to-resist ratio condition is obtained is a method of changing the flow rate ratio of the etching gas as described above. That is, for example, when about half of the cathode holes are formed in the insulating layer, the etching process is performed under the condition that the ratio of the deposition gas is increased so that the selection ratio with respect to the resist becomes several times. As a result, at the end of etching,
The deposit acts as a sidewall protective film, and the resist film is scraped (retreated)
Can be prevented, the shoulder of the cathode hole portion of the conductive layer on the lower side thereof can be prevented from being dropped, and a uniform and favorable shape of the cathode hole can be formed. Therefore, in the subsequent steps, the microcathode can be formed inside the cathode hole with a uniform height and shape.

In another aspect of the present invention, the distance between the substrate and the etching plasma is increased at the end of the etching of the insulating layer so that the high selectivity ratio to the resist is satisfied. By doing so, the degree of re-dissociation of the etching gas is affected, the amount of halogen radicals for etching that acts on the substrate is controlled, and the deposition of the sidewall protective film is promoted. As a result, it is possible to prevent the resist film from being scraped (retracted), eliminate the shoulder drop of the cathode hole portion of the conductive layer below the resist film, and form a uniform and good-shaped cathode hole. Therefore, in the subsequent steps, the microcathode can be formed inside the cathode hole with a uniform height and shape.

In still another aspect of the present invention, the exposed surface area of the silicon-based component placed in the etching apparatus is changed at the end of the etching of the insulating layer so that the high resist-to-resist ratio ratio condition is satisfied. As a silicon-based component,
Although not particularly limited, Si or the like coated on the inner wall of the chamber of the plasma etching apparatus can be exemplified. In order to change the exposed surface area of the silicon-based component, for example, a shutter may be provided on the surface of the silicon-based component and the opening of the shutter may be adjusted.

That is, in the invention according to this aspect, the opening of the shutter is relatively large at the initial stage of etching the insulating layer, and the opening of the shutter is narrowed during the etching (end of etching). By changing the exposed surface area of the silicon-based component exposed to plasma, re-dissociation of the etching gas is significantly suppressed at the end of etching, and the selectivity ratio to resist is increased. As a result, it is possible to prevent the resist film from being scraped (retracted), eliminate the shoulder drop of the cathode hole portion of the conductive layer below the resist film, and form a uniform and good-shaped cathode hole. for that reason,
In the subsequent steps, the micro cathode can be formed inside the cathode hole with a uniform height and shape.

[0021] In still another aspect of the present invention, the type of etching gas is changed so that the high resist to selectivity ratio condition is satisfied (for example, the etching gas contains sulfur). At the final stage of plasma etching, sulfur (S) is re-dissociated in the plasma and a side wall protective film containing S is formed in the cathode hole. As a result, it is possible to prevent the resist film from being scraped (retracted), eliminate the shoulder drop of the cathode hole portion of the conductive layer below the resist film, and form a uniform and good-shaped cathode hole. Therefore, in the subsequent steps, the microcathode can be formed inside the cathode hole with a uniform height and shape. Since the side wall protective film containing S can be removed at the same time as the ashing removal of the resist film, a special process for removing the side wall protective film is not required, which contributes to the reduction of the process.

In still another aspect of the present invention, the exposed surface area of the sulfur-containing component installed in the etching apparatus is changed so as to satisfy the high resist to selectivity ratio condition. The constituent material containing sulfur (S) is not particularly limited, and examples thereof include SiS coated on the inner wall of the chamber of the plasma etching apparatus. In order to change the exposed surface area of the silicon-based component, for example, a shutter may be provided on the surface of the silicon-based component and the opening of the shutter may be adjusted.

That is, in the invention according to this aspect, the opening of the shutter is relatively small at the initial stage of etching the insulating layer, and the opening of the shutter is increased during the etching (end of etching). By changing the exposed surface area of the S-based component exposed to plasma, S is dissociated from the surface of the S-based component at the end of etching, and the side wall protective film containing S as a main component is located on the cathode hole side. Deposit on the area. As a result, it is possible to prevent the resist film from being scraped (retracted), eliminate the shoulder drop of the cathode hole portion of the conductive layer below the resist film, and form a uniform and good-shaped cathode hole. Therefore, in the subsequent steps, the microcathode can be formed inside the cathode hole with a uniform height and shape.

Since the side wall protective film containing S can be removed at the same time when the resist film is removed by ashing, a special process for removing the side wall protective film is not required, which contributes to the reduction of the process.

[0025]

The method for producing a microcathode according to the present invention will be described in detail below with reference to the embodiments shown in the drawings.
1 (A) to 1 (D) are cross-sectional views of a main part showing a manufacturing process of a microcathode according to an embodiment of the present invention, and FIGS.
(G) is a cross-sectional view of an essential part showing a subsequent step of the manufacturing process shown in FIG. 1, and FIGS. 3 and 4 are schematic cross-sectional views of an essential part of a plasma etching apparatus used in an embodiment of the present invention.

First, a plasma etching apparatus that can be used in the embodiments of the present invention will be described. For example, the RF bias application type ECR plasma etching apparatus shown in FIG. 3 can be used. In the apparatus, the microwave generated in the magnetron 101 passes through the waveguide 102, and the reaction chamber 104 surrounded by the quartz bell jar 103.
Transferred to at the solenoid coil 105 which is installed in a manner to surround the reaction chamber 104, a microwave frequency (2.45 GHz), the magnetic field causes a so-called ECR discharge (8.75 × 10 ^- 2T) and the Caused by,
Generate a gas plasma. The gas plasma reaches the wafer 106 as a substrate to be etched.

The wafer 106 is transferred and set by a transfer means (not shown) so as to be placed on the stage 107. The stage 107 is controlled to move up and down for the purpose of placing the wafer 106 and moving the wafer 106 toward and away from the gas plasma. The stage 107 is provided with a heat exchange tube or a heater for controlling the wafer temperature. RF is applied to the stage 107 from a radio frequency (RF) power supply 112 of 13.56 MHz.

The etching gas is introduced into the bell jar 103 through a gas introduction pipe (not shown), and is exhausted from an exhaust pipe 108 by an exhaust system (not shown).
In the embodiment, the wafer 106 on the stage 107 is held by the clamp 109. The clamp 109 includes a silicon (Si) -based material or a sulfur compound (for example, Si).
S).

On the inner wall of the bell jar 103, a silicon (Si) type material or a sulfur compound (eg SiS) is used.
A coating layer 110 composed of is formed. A shutter 111 is formed on the surface of the coating layer 110.
Is attached. The opening of the shutter 111 can be controlled so as to change the exposed surface area of the coating layer 110. The moving mechanism of the shutter 111 is not particularly limited as long as it can be freely opened and closed.
A slide movement mechanism, a rotation movement mechanism, or a shutter movement mechanism used for a camera or the like can be exemplified. The structure of the shutter 111 is not particularly limited as long as it can appropriately shield the plasma ions, and the shutter 111 may be formed of a metal mesh or the like.

The plasma etching apparatus shown in FIG.
It is of a CP type, and the induction coupling coil 115 wound around the side wall of the chamber 114 is 2M
It has a mechanism of applying RF of Hz to form high density plasma. The wafer 106 as a substrate to be etched is placed on the stage 107 and clamped.
Held by 9. Stage 107 and clamp 1
The configuration of 09 is basically the same as that of the device shown in FIG. Around the chamber 114, heat exchange means 115 for controlling the temperature of the chamber 114 itself.
Has been placed.

In the apparatus of the embodiment shown in FIG. 4, a coating layer 110 made of a silicon (Si) type material or a sulfur compound (eg SiS) is formed on the inner wall of the chamber 114. A shutter 111 is attached to the surface of the coating layer 110. The opening of the shutter 111 can be controlled so as to change the exposed surface area of the coating layer 110. The moving mechanism of the shutter 111 is not particularly limited as long as it can be opened and closed, and a slide moving mechanism, a rotation moving mechanism, or a shutter moving mechanism used for a camera or the like can be illustrated. The structure of the shutter 111 is not particularly limited as long as it can appropriately shield the plasma ions, and the shutter 111 may be formed of a metal mesh or the like.

First Embodiment Next, a method of manufacturing a microcathode according to the first embodiment of the present invention will be described. In this embodiment, a method of changing the flow rate ratio of the etching gas is adopted as a method of switching the conditions in the etching apparatus so that the high selectivity ratio with respect to the resist is obtained.

In this embodiment, first, as shown in FIG. 1A, the insulating layer 32 and the conductive layer 3 are formed on the semiconductor substrate 30.
5 is sequentially formed. As the semiconductor substrate 30, for example, a single crystal silicon substrate is used. As the insulating layer 32, silicon oxide formed by CVD or thermal oxidation is used. The insulating layer 32 formed of a silicon oxide film is formed by CVD under the following conditions, for example. TEOS (Tetraethyloxys) is used as a CVD source gas.
ilane or Tetraethylorthosilicate, Si (OC ₂ H ₅
) ₄ ) and O ₂ , the flow ratio of TEOS / O ₂ is
The conditions are 500/1000 SCCM, atmospheric pressure of 5 Pa, and substrate temperature of 400 ° C. The layer thickness of the insulating layer 32 is, for example, 1.0 μm.

The conductive layer 35 is not particularly limited, in the present embodiment, a polycide film which is a laminated film of a polysilicon n ⁺ -type conductivity layer 34 and a tungsten silicide (WSi _x) layer 36 is used. This conductive layer 35 functions, for example, as a grid of microcathodes.

The thickness of the polysilicon film 34 is, for example, 5
It is 0 nm. The film thickness of the tungsten silicide film 36 is, for example, 150 to 300 nm. The polysilicon film 34 and the tungsten silicide film 36 are formed by, for example, CVD. The polysilicon film 34 is formed under the following conditions, for example. SiH ₄ and PH ₃ are used as the CVD source gas, the flow rate ratio of SiH ₄ / PH ₃ is 500 / 0.3 SCCM, and the atmospheric pressure is 100P.
a, the substrate temperature is 500 ° C. The tungsten silicide film 36 is formed under the following conditions, for example. WF ₆ , SiH _4, and He are used as the CVD source gas, and the flow rate ratio of WF ₆ / SiH ₄ / He is 3/30.
0 / 500SCCM, atmospheric pressure 70Pa, substrate temperature 3
The condition is 60 ° C.

Next, this tungsten silicide film 36 is formed.
A resist film 38 is formed on the
Then, the openings 40 are formed in a predetermined pattern corresponding to the cathode holes by photolithography. The inner diameter of the opening 40 corresponds to the inner diameter of the cathode hole and is, for example, about 0.8 μm. The resist film 38 is not particularly limited, but, for example, a novolac-based g-line resist can be used.

Next, the semiconductor substrate 30 on which the resist film 38 is formed is placed in, for example, a general plasma etching apparatus, and etching processing is performed using the resist film 38 as a mask. The plasma etching apparatus is not particularly limited, but for example, a microwave electron cyclotron resonance plasma (ECR) etching apparatus, an induction coil type plasma (ICP) etching apparatus, a helicon wave utilizing plasma etching apparatus, a transformer coupled plasma (T
CP) etching device and the like can be exemplified.

First, using, for example, an ECR etching apparatus, the tungsten silicide film 36 and the polysilicon film 34 are continuously etched under the following conditions as shown in FIG. As the etching gas, Cl ₂ and O are used.
Using a mixed gas of ₂ and a flow rate ratio of Cl ₂ / O ₂ of 70 /
It will be 10 SCCM. The atmospheric pressure is 0.4 Pa. The microwave power is 850 W, which is high frequency (R
F) Power is 40 W and substrate temperature is 10 ° C.

Subsequently, the insulating layer 32 is processed by etching, and the etching conditions at the initial stage of the etching are set to the conditions of step I shown below.

[0040]

[Table 1] [Step I: Main etching step] Gas: CHF ₃ / CH ₂ F ₂ = 45 / 5SCCM Pressure: 0.27Pa μ wave output: 1200W RF bias: 225W (800kHz) Substrate temperature: 20 ° C In the example, the etching condition is switched to the condition of Step II shown below in a state where the insulating layer 32 is etched by about half.

[0041]

[Table 2] [Step II: Over-etching step] Gas: CHF ₃ / CH ₂ F ₂ = 35/15 SCCM RF bias: 175 W (800 kHz) (other conditions are the same as in Step I) Conventionally, such a multilayer film In the continuous etching, the resist film 38 recedes due to excessive overetching under high energy conditions, the side wall of the opening 40 is also shaved, and the tungsten silicide film 36 located thereunder is also partially etched to form a tapered shape. Is formed. This is because the conductive film 35 and the insulating layer 32 are etched with the same resist film 38, so that the resist film 3
It is considered that the time for which 8 was exposed to plasma etching was longer than that in the conventional etching technique for forming contact holes. However, in the present embodiment, at the end of the etching of the insulating layer 32, the etching condition is changed from step I to step II under the condition of the high resist selectivity ratio, so that even the sidewall of the opening of the conductive layer 35 is over-etched. It will not be done. That is,
In this embodiment, at the end of etching the insulating layer 32,
Since the etching gas flow rate ratio is changed to the condition of high selectivity ratio to resist, as shown in FIG. 1C, SiCl, S
The reaction product such as iO ₂ becomes the side wall protection film 41 and adheres to the side wall of the opening of the resist film 38 and the conductive layer 35. As a result, the resist film 38 can be prevented from receding, the shoulder of the tungsten silicide film 36 can be prevented, and the cathode hole 44 having a good anisotropic shape can be formed.

Next, as shown in FIG. 1D, the resist film 38 is removed by resist ashing. The resist ashing is performed by using 500 SCCM of O ₂ under the conditions of an atmospheric pressure of 3.0 Pa, a substrate temperature of 200 ° C., and a radio frequency (RF) power of 300 W. The sidewall protective film 41 is also removed at the same time as or after the removal of the resist film 38.

Next, as shown in FIG. 2E, a tungsten silicide film 36 is formed by using an electron beam evaporation method or the like.
A peeling layer 46 is formed on the above. The peeling layer 46 is composed of, for example, an aluminum metal layer. The peeling layer 4
The layer thickness of 6 is not particularly limited, but is, for example, about 50 nm. The substrate angle during electron beam evaporation is preferably about 20 degrees. The atmospheric pressure is 1.0 Pa, for example.

Next, as shown in FIG. 2F, a cathode forming layer 48 is deposited on the peeling layer 46 by using, for example, an electron beam evaporation method. Molybdenum (Mo) is preferably used for the cathode formation layer 48, but other refractory metals, other metals, compounds, or the like can also be used. The angle of the substrate during electron beam evaporation is
About 90 degrees is preferred. Cathode forming layer 48 is about 1.0 μ
By forming it with a layer thickness of m 2, the surface of the substrate 30 located at the bottom of the cathode hole 44 has a cathode 50 with an acute cone shape.
Are formed with a uniform shape and height. Each cathode 50
The shape, in particular the height, of each of the openings 4 of the cathode formation layer 48 is
It depends on the time until 8a is closed. In this embodiment, on the sidewall of the opening of the tungsten silicide film 36,
Since there is no taper or shoulder drop, the step coverage of the cathode formation layer 48 is also constant, and each opening 48a thereof is
The time until closing is constant, and the shape, especially height, of each cathode 50 can be made uniform.

Next, as shown in FIG. 2G, wet etching (about 30 seconds) is performed with hydrofluoric acid at a ratio of water: hydrofluoric acid of about 5: 1, and the peeling layer 46 made of aluminum or the like is used. Are removed by etching, and the cathode forming layer 48 located thereon is lifted off. In the cathode hole 44, the microcathode 20 having a uniform shape and height remains.

After that, on the substrate 30, a transparent substrate having a phosphor film formed thereon or a transparent substrate having a transparent conductive film formed thereon is laminated in a vacuum state to form an FED or an image pickup device. Second Embodiment In the second embodiment of the present invention, a method of changing the distance between the plasma and the substrate is adopted as a method for increasing the resist selective ratio.

The details will be described below. However, the description of the part of the process common to the process shown in the first embodiment will be omitted. Similar to the first embodiment, FIG.
As shown in FIGS. 1A and 1B, after the conductive layer 35 is etched using the resist film 38 as a mask, FIG.
As shown in (C), the insulating layer 32 is etched. At that time, as shown in FIG. 3, an ECR plasma etching apparatus capable of controlling vertical movement of the stage 107 is used, and as shown below, the main etching process of the insulating layer 32 and the over-etching process of the stage 107 are performed. Change the height of.

First, main etching of the insulating layer 32 is performed under the following conditions.

[0049]

[Table 3] [Step I: Main etching step] Gas: CHF ₃ / CH ₂ F ₂ = 45 / 5SCCM Pressure: 0.27Pa μ wave output: 1200W RF bias: 225W (800kHz) Substrate temperature: 20 ° C ECR high S: 40 mm Stage height: 150 mm Next, at the stage where about half the cathode holes 44 are formed in the insulating layer 32 shown in FIG. 1C, the etching conditions are switched to the following.

[0050]

[Table 4] [Step II: Over-etching step] ECR height: 70 mm Stage height: 0 mm (other conditions are the same as step I) Here, the ECR point height is the height from the lower end of the solenoid coil 105 in FIG. It shows that. The stage height refers to the height when the wafer stage 107 is moved up and down, and indicates that the stage height 0 mm is a position about 200 mm away from the lower end of the solenoid coil 105. Therefore, the plasma-substrate distance under the above conditions is about 90 mm in Step I and about 2 mm in Step II.
It becomes 70 mm.

The stage height affects the degree of re-dissociation and is an important parameter for controlling the effective F radical production amount on the wafer. Under the above conditions, Step II
In promoting deposition, pairs for performing resist high selective etching, as in the results in FIG. 1 (C), the cathode hole 44 obtained tungsten silicide (WSi _x) good shape without the bowing of membrane 36 It was

The subsequent steps are the same as in the case of the first embodiment. As described above, in this embodiment, as in the first embodiment, as shown in FIG. 2G, the microchip cathode 50 having a good and uniform shape could be realized. Third Embodiment In the third embodiment of the present invention, a method of changing the exposed area of the constituent material in the Si-based chamber is adopted as a method for increasing the resist selective ratio.

The details will be described below. However, the description of the part of the process common to the process shown in the first embodiment will be omitted. Similar to the first embodiment, FIG.
As shown in FIGS. 1A and 1B, after the conductive layer 35 is etched using the resist film 38 as a mask, FIG.
As shown in (C), the insulating layer 32 is etched. At that time, as shown in FIG. 4, an ICP plasma etching apparatus having a coating layer 110, which is a silicon-based constituent material, and a shutter 111 mounted on the inner wall of the chamber 114 is used. The main etching process and the over etching process of
The opening degree of the shutter 111 is changed.

First, main etching of the insulating layer 32 is performed under the following conditions.

[0055]

[Table 5] [Step I: Main etching step] Gas: C ₂ F ₆ = 50 SCCM Pressure: 0.27 Pa Source output: 2000 W RF bias: 800 W Substrate temperature: 20 ° C Chamber temperature: 270 ° C Shutter temperature: 100% Next, when about half the cathode holes 44 are formed in the insulating layer 32 shown in FIG. 1C, the etching conditions are switched to the following.

[0056]

[Table 6] [Step II: Over-etching step] Shutter temperature: 20% (other conditions are the same as step I) Here, the shutter opening is shutter 1 in FIG.
Coating layer 11 on the inner wall of the chamber by opening and closing 11
The exposure area is 0, and in FIG. 4, the opening degree is about 50%. The shutter opening is an important parameter that controls the total production of F radicals.

Under the above conditions, SiO₂ Figure 1 consisting of
Is the etching about half of the insulating layer 32 shown in FIG.
If so, switch to the reselection condition of Step II.
By doing so, re-dissociation is greatly suppressed and the selectivity ratio to resist
Is approximately doubled, and there is no shoulder drop as shown in Fig. 1 (C).
Tungsten silicide with good anisotropic shape (WSi
_x) Became cathode hole 44 of membrane 36. At that time,
The same conditions as in Example 1 were used to promote high selectivity.
So normal SiO₂ The stack that can be seen when etching
The product serves as a sidewall protection film 41 of the photoresist film 38.
Prevented retreat.

The subsequent steps are the same as in the case of the first embodiment. As described above, in this embodiment, as in the first embodiment, as shown in FIG. 2G, the microchip cathode 50 having a good and uniform shape could be realized. Fourth Embodiment In the fourth embodiment of the present invention, a method of supplying S into plasma is adopted as a method of increasing the selective ratio to resist.

The details will be described below. However, the description of the part of the process common to the process shown in the first embodiment will be omitted. Similar to the first embodiment, FIG.
As shown in FIGS. 1A and 1B, after the conductive layer 35 is etched using the resist film 38 as a mask, FIG.
As shown in (C), the insulating layer 32 is etched. At that time, using the ICP plasma etching apparatus shown in FIG. 4, the type of etching gas is changed between the main etching step of the insulating layer 32 and the over-etching step, as shown below.

First, main etching of the insulating layer 32 is performed under the following conditions.

[0061]

[Table 7] [Step I: Main etching step] Gas: C ₂ F ₆ = 50SCCM Pressure: 0.27Pa Source output: 2000W RF bias: 800W Substrate temperature: -20 ° C Chamber temperature: 270 ° C Next figure When about half of the cathode holes 44 are formed in the insulating layer 32 shown in FIG. 1 (C), the etching conditions are switched to the following.

[0062]

TABLE 8 [Step II: overetching step Gas: The _{C 2 F 2 / S 2 F} 2 = 40 / 10SCCM ( other conditions similar to step I) above condition, FIG. 1 made of SiO ₂ (C 1), when the etching of the insulating layer 32 is about half done, the condition is changed to the addition condition of S ₂ F _{2 in} step II, so that S is dissociated and generated in the plasma, and S is the main component. By depositing the side wall protective film 41 shown in (C), receding of the photoresist 5 is prevented. Therefore, Fig. 1 (C)
As shown in, the cathode hole 44 of tungsten silicide having good anisotropic shape without bowing (WSi _x) layer 36
Became. At this time, the deposited side wall protection 41 is completely removed when the photoresist film 38 is ashed, and no special process for removing the side wall protection film 41 is required.

The subsequent steps are the same as in the case of the first embodiment. As described above, in this embodiment, as in the first embodiment, as shown in FIG. 2G, the microchip cathode 50 having a good and uniform shape could be realized. Fifth Embodiment In the fifth embodiment of the present invention, a method of changing the exposed area of the constituent material in the S-based chamber is adopted as a method for increasing the resist selective ratio.

The details will be described below. However, the description of the part of the process common to the process shown in the first embodiment will be omitted. Similar to the first embodiment, FIG.
As shown in FIGS. 1A and 1B, after the conductive layer 35 is etched using the resist film 38 as a mask, FIG.
As shown in (C), the insulating layer 32 is etched. At that time, as shown in FIG. 3, an ECR plasma etching apparatus having a coating layer 110, which is a sulfur-based (eg, SiS) constituent material, and a shutter 111 mounted on the inner wall of the chamber 114 is used. The opening degree of the shutter 111 is changed in the main etching process of the insulating layer 32 and the over etching process.

First, the main etching of the insulating layer 32 is performed under the following conditions.

[0066]

[Table 9] [Step I: Main etching step] Gas: CHF ₃ / CH ₂ F ₂ = 45 / 5SCCM Pressure: 0.27Pa μ wave output: 1200W RF bias: 225W (800kHz) Substrate temperature: 20 ° C Shutter open Degree: 0% Next, when about half of the cathode holes 44 are formed in the insulating layer 32 shown in FIG. 1C, the etching conditions are switched to the following.

[0067]

[Table 10] [Step II: Over-etching step] Shutter opening: 100% (other conditions are the same as step I) Here, the shutter opening is the shutter 1 in FIG.
Coating layer 11 on the inner wall of the chamber by opening and closing 11
The exposure area is 0, and in FIG. 3, the opening degree is about 50%. The shutter opening is an important parameter that controls the dissociation generation of S.

In this embodiment, by switching to the condition of step II, S is dissociated and generated from the surface of the S-based constituent material exposed to plasma, and S is the main component as shown in FIG. 1 (C). By depositing the sidewall protection film 41, the photoresist film 38 is prevented from receding. Therefore, also in this embodiment, as shown in FIG. 1 (C), it was the cathode hole 44 of tungsten silicide (WSi _x) layer 36 of the highly anisotropic shape without bowing.

Although the present invention has been described above based on the five embodiments, it should be understood that the present invention is not limited to the above-mentioned embodiments, and includes a plasma source, an apparatus configuration, a substrate structure, It goes without saying that the processing conditions and the like can be appropriately selected without departing from the spirit of the present invention.

[0070]

As described above, according to the present invention, a microcathode having a uniform shape and height can be formed without causing a defect due to an abnormal shape of a conductive layer formed of a tungsten silicide film or the like. Can be stably formed. A device using this microcathode is suitably used as an FED used for a flat display or the like, or an image pickup device.

[Brief description of drawings]

FIG. 1A to FIG. 1D are cross-sectional views of a main part showing a manufacturing process of a microcathode according to an embodiment of the present invention.

2 (E) to 2 (G) are cross-sectional views of essential parts showing a step that follows the manufacturing step shown in FIG. 1.

FIG. 3 is a schematic cross-sectional view of a main part of a plasma etching apparatus used in an embodiment of the present invention.

FIG. 4 is a schematic cross-sectional view of a main part of a plasma etching apparatus used in another embodiment of the present invention.

FIG. 5 is a cross-sectional view of essential parts showing a method for manufacturing a microcathode according to a conventional example.

[Explanation of symbols]

 30 ... Semiconductor substrate 32 ... Insulating layer 34 ... Polysilicon film 35 ... Conductive layer 36 ... Tungsten silicide film 38 ... Resist film 40 ... Opening 41 ... Side wall protective film 44 ... Cathode hole 46 ... Peeling layer 48 ... Cathode forming layer 50 ... Micro cathode 107 ... Stage 110 ... Coating layer 111 ... Shutter

Claims (7)

[Claims] 1. A step of forming at least an insulating layer and then a conductive layer on a surface of a substrate, a step of forming a resist film on the conductive layer, and a predetermined pattern in which a cathode hole is to be formed. A step of patterning the resist film, and an etching process using the resist film as a mask,
The method has a step of forming a cathode hole in the conductive layer and the insulating layer, and a step of forming a microcathode in the cathode hole formed in the insulating layer, and when forming a cathode hole in the insulating layer, A method of manufacturing a field emission type microcathode, characterized in that the conditions in the etching apparatus are switched so that a high selection ratio condition for the resist is achieved at the end of the etching of the insulating layer. 2. The field emission type microcathode according to claim 1, wherein the method for switching the conditions in the etching apparatus so as to satisfy the high resist-to-resist ratio condition is a method for changing the flow rate ratio of the etching gas. Production method. 3. The field emission according to claim 1, wherein the method of switching the conditions in the etching apparatus so as to obtain the high resist-to-resist ratio condition is a method of changing the distance between the substrate and the etching plasma. Of manufacturing a micro-cathode. 4. The method of switching the conditions in the etching apparatus so that the high resist-to-resist selection ratio condition is achieved is a method of changing the exposed surface area of the silicon-based component installed in the etching apparatus. 1. The method for producing a field emission microcathode according to 1. 5. The method for producing a field emission type microcathode according to claim 1, wherein the method of switching the conditions in the etching apparatus so as to obtain the high resist-to-resist ratio condition is a method of changing the type of etching gas. Method. 6. The method for producing a field emission microcathode according to claim 5, wherein etching is performed under the condition that an etching gas containing sulfur is used at the end of the etching of the insulating layer. 7. The method of switching the conditions in the etching apparatus so that the high resist-to-resist ratio condition is achieved is a method of changing the exposed surface area of the constituent material containing sulfur installed in the etching apparatus. Item 2. A method for producing a field emission microcathode according to Item 1.