JP2009238998A - Method of forming contact hole, pattern forming method, and method of manufacturing electrooptical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of forming a contact hole capable of controlling a taper angle appropriately even if a hole diameter in etching is small and an aspect ratio is high, and to provide a pattern forming method, and a method of manufacturing an electrooptical device. <P>SOLUTION: A metal film 3 is formed on a film 2 formed on a base material 1. Then, a resist mask 4 is formed on the metal film 3. The resist mask 4 is used, the metal film 3 is subjected to dry etching, the amount of retreat of the resist mask 4 by dry etching is controlled, and a metal mask 5 is formed, where an open side face 5a has a first tilt angle to the film. By performing dry etching to the film by the metal mask 5 having a first tilt angle, a conductive section 6 formed on the surface of the base material 1 is exposed, and a hole having a second tilt angle according to the first tilt angle to the conductive section 6 of the open side face 5a is formed. Then, in the method of forming a contact hole, the metal mask 5 is removed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a contact hole forming method, a pattern forming method, and an electro-optical device manufacturing method.

  Conventionally, as a conduction method between multilayer wirings in a semiconductor element, for example, there is a technique of forming a metal wiring by forming a contact hole and forming a metal film inside the contact hole by a sputtering method. However, the contact hole has a very poor step coverage, particularly on the side wall, and if the contact hole diameter becomes small and the aspect ratio becomes high, disconnection may occur. As a method for improving the step coverage of such a contact hole, it is conceivable to reduce the taper angle of the contact hole.

In Patent Document 1, a gentle taper (small taper angle) is formed on the top of the contact hole by combining wet etching and dry etching. Further, in Patent Document 2, dry etching is performed while retracting the photoresist to form a contact hole having a small taper angle.
JP-A-6-97104 JP-A-5-102106

However, since the wet etching which is isotropic etching is used in the method in the above-mentioned patent document 1, the controllability of the etching amount in the horizontal direction and the vertical direction is poor, and a contact hole having a small hole diameter and a high aspect ratio is formed. Difficult to do.
In the method in Patent Document 2, the taper angle of the contact hole depends on the resist receding speed during the dry etching process. That is, the taper angle becomes smaller as the resist receding speed increases. Further, the resist receding speed depends on the contact between the resist and the film to be etched, and the resist receding speed increases (increases) as the resist grounding angle decreases. That is, the taper angle of the contact hole becomes smaller as the contact angle of the resist becomes smaller. On the other hand, the contact hole tends to increase the contact angle of the resist when the hole diameter is small and the aspect ratio is high. Therefore, it is difficult for the method in Patent Document 2 to form a contact hole having a small hole diameter and a high aspect ratio.

  The present invention has been made in view of such circumstances, and a contact hole forming method and pattern forming method capable of satisfactorily controlling the taper angle even when the hole diameter during etching is small and the aspect ratio is high. And a method of manufacturing an electro-optical device.

  In order to solve the above problems, a contact hole forming method of the present invention includes a step of forming a metal film on a film formed on a substrate, a step of forming a resist mask on the metal film, Dry etching the metal film using a resist mask, and controlling a receding amount of the resist mask by the dry etching to form a metal mask having an opening side surface having a first inclination angle with respect to the film; The film is dry-etched using the metal mask having the first inclination angle to expose the conductive part formed on the surface of the base material, and the opening side surface is the first with respect to the conductive part. A step of forming a hole having a second inclination angle corresponding to the inclination angle of the first metal layer and a step of removing the metal mask.

  According to the contact hole forming method of the present invention, a metal mask having an opening side surface having a first inclination angle with respect to the film is formed by controlling a receding amount of the resist mask by dry etching, and the first mask is formed. Since the hole is formed in the film using the metal mask having the inclination angle, the inclination of the opening side surface of the hole can be controlled to the second inclination angle corresponding to the first inclination angle. Therefore, even if the contact hole diameter (hole diameter) to be formed is small and the aspect ratio is high, a hole having a desired taper angle (second inclination angle) can be formed. In addition, since the contact hole can be formed only by the dry etching process, it is possible to obtain a highly accurate one with a small processing conversion difference and to easily control the etching.

In the contact hole forming method, it is preferable that in the step of forming the hole, dry etching is performed using the resist mask as a mask together with the metal mask.
According to this structure, the process of peeling a resist mask by peeling a resist mask with a metal mask after contact hole formation becomes unnecessary, and a process can be simplified.
In the contact hole forming method, the step of forming the metal mask may control the amount of retraction of the resist mask by the dry etching by controlling the addition amount of a gas for etching the resist mask. preferable.
According to this configuration, in the dry etching of the metal mask, the amount of etching of the resist mask is controlled from zero to a predetermined addition amount by controlling the amount of the etching gas added to the dry etching gas. Therefore, the metal mask having the first inclination angle can be easily formed.
Further, in the contact hole forming method, in the step of forming the metal mask, the first inclination angle is changed from about 20 degrees to about 90 degrees by controlling a receding amount of the resist mask by the dry etching. Preferably, in the step of forming the hole, the hole is formed at a second inclination angle of about 80 degrees to about 60 degrees according to the first inclination angle.
According to this configuration, by selecting the first inclination angle, the inclination angle of the hole to be formed can be formed at a desired angle, and a contact hole with excellent step coverage can be formed.
In the contact hole forming method, the aspect ratio of the hole (hole depth / hole diameter) is preferably greater than 0.3, and the first inclination angle is approximately 90 degrees. .
According to this configuration, when the aspect ratio of the contact hole (hole) is large (high), that is, when the contact hole has a small diameter and a fine contact hole is formed, the mask and the contact hole formed are Since the conversion difference can be reduced and a contact hole with excellent controllability can be formed, and the inclination angle of the hole to be formed can be reduced, a contact hole with excellent step coverage can be formed.

  The pattern forming method of the present invention includes a step of forming a metal film on a film formed on a substrate, a step of forming a resist mask on the metal film, and dry etching the metal film using the resist mask. And forming a metal mask having an opening side surface having a first tilt angle with respect to the film by controlling a receding amount of the resist mask by the dry etching, and a metal mask having the first tilt angle. Forming a pattern in which the side surface of the etched film has a second inclination angle corresponding to the first inclination angle with respect to the metal film; and And a step of removing the mask.

  According to the pattern forming method of the present invention, since the film is patterned using the metal mask whose opening side surface has the first inclination angle with respect to the film, the etching region is a pattern having a fine and tapered shape. Also, the taper angle can be formed with high accuracy by using the desired second inclination angle. Further, since the patterning is performed only by the dry etching process, a highly accurate product with a small processing conversion difference can be obtained, and the etching can be easily controlled.

In the pattern forming method, it is preferable that dry etching is performed using the resist mask as a mask together with the metal mask in the step of forming the pattern of the film.
According to this structure, the process of peeling a resist mask by peeling a resist mask with a metal mask after pattern formation becomes unnecessary, and a process can be simplified.

  According to the electro-optical device manufacturing method of the present invention, in the electro-optical layer manufacturing method in which an electro-optical layer is sandwiched between a pair of substrates, in the semiconductor layer constituting the switching element formed on one of the substrates Forming a metal film on an insulating film covering the active region; forming a resist mask on the metal film; dry-etching the metal film using the resist mask; and forming a resist mask by the dry etching. Forming a metal mask having an opening side surface having a first inclination angle with respect to the film by controlling a receding amount; and dry etching using the metal mask having the first inclination angle, The insulating film includes a hole that exposes an active region and has an opening side surface having a second inclination angle corresponding to the first inclination angle with respect to the conductive portion. Forming, removing the metal mask, characterized in that it comprises a step of forming a conductive portion connected to said active region through said hole.

  According to the method of manufacturing the electro-optical device of the present invention, the metal mask having the opening side surface having the first inclination angle with respect to the film is formed by controlling the receding amount of the resist mask by dry etching. Since the hole is formed in the film using the metal mask having the inclination angle of 1, the inclination of the opening side surface of the hole can be controlled to the second inclination angle corresponding to the first inclination angle. Therefore, even when the contact hole (hole) for forming the conductive portion connected to the active region of the semiconductor layer has a small hole diameter and a large (high) aspect ratio (hole diameter), a desired taper is obtained. It can be formed to have an angle (second inclination angle). Therefore, since the inner wall surface of the contact hole has a desired taper angle (not likely to cause disconnection), for example, when forming the conductive portion by sputtering, good step coverage can be obtained, and disconnection occurs. Is prevented.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a method for forming a contact hole will be described. In this description, a step of forming a contact hole in the interlayer insulating film with a particularly small hole diameter and a high aspect ratio (contact hole depth / contact hole diameter) is taken as an example. This step is applied to a step of manufacturing a liquid crystal display device as an electro-optical device to be described later.

As shown in FIG. 1A, a metal film 3 is formed on an interlayer insulating film (film) 2 formed on a substrate 1. Here, the base material 1 includes various materials such as a substrate, a substrate whose surface is covered with an insulating layer, or a substrate on which metal wiring is formed. In the present embodiment, the interlayer insulating film 2 is formed so as to cover the conductive portion 6 formed on the substrate 1. The interlayer insulating film 2 is made of silicon oxide such as a SiO ₂ film.

  The metal film 3 is formed of a Mo film by sputtering, for example. The Mo film is preferably set to a thickness of about 500 to 5000 mm, for example, and in this embodiment is set to 2000 mm. As the metal film 3, a Ti film can be used in addition to the Mo film. The interlayer insulating film 2 is formed to a thickness of, for example, 7000 mm.

Subsequently, as shown in FIG. 1B, a resist is formed on the metal film 3, and the resist is patterned by photolithography to form a resist mask 4. Then, the metal mask 3 is formed on the interlayer insulating film 2 by dry etching the metal film 3 using the resist mask 4. As an etching gas, a gas having a high selectivity with respect to the interlayer insulating film 2 (SiO ₂ film), for example, Cl ₂ is used.

Here, in the dry etching process of the metal film 3, the inclination angle of the opening side surface (tapered portion 5a) of the metal mask 5 is formed to a desired inclination angle (first inclination angle) in the range of 90 degrees to 20 degrees. . The first tilt angle can be controlled by adding a gas having an effect of etching the resist mask 4 to the etching gas for the metal film during dry etching. That is, the amount of retreat of the resist mask is controlled by controlling the amount of gas that has an effect of etching the resist mask 4. For example, when the material of the resist mask 4 is C or H, the addition amount of O ₂ may be controlled.
When the gas is not added, the resist mask 4 is not etched, so that no receding occurs. Therefore, the taper part 5 a of the metal mask 5 has a taper angle of approximately 90 degrees with respect to the interlayer insulating film 2.
As the amount of gas to be added is increased, the amount of etching of the resist mask 4 is increased, so that the amount of recession of the resist mask 4 is also increased. As the receding amount of the resist mask 4 increases, the taper angle of the taper portion 5a of the metal mask 5 also decreases.
As shown in FIG. 1C, the resist mask 4 is used as a mask while controlling the receding amount by dry etching. When a gas having an effect of etching the resist mask 4 is added, as the dry etching progresses, the resist mask recedes and the diameter of the resist mask increases. By performing dry etching in this way, a tapered portion 5a whose opening side surface is inclined from about 90 degrees to about 20 degrees with respect to the interlayer insulating film 2 as the metal mask 5 in accordance with the receding amount of the resist mask 4. Can be formed. The metal mask 5 has an opening formed at a position corresponding to the conductive portion 6 formed on the substrate 1, and the opening diameter (hole diameter on the side in contact with the interlayer insulating film 2) is, for example, 1. It is about 8 μm. The metal mask 5 is used as a mask when forming contact holes (holes) in the interlayer insulating film 2 as will be described later.

Subsequently, the resist mask 4 on the metal mask 5 is removed as shown in FIG.
Here, during the dry etching process of the metal film 3 (Mo film), the film thickness of the film to be etched is small, and further, Cl ₂ used as an etching gas is difficult to form a deposition film (polymerized film). When the resist mask 4 is peeled off, the resist residue hardly occurs. Even if a resist residue is generated on the metal mask 5, there is no problem because it is removed together with the metal mask 5 when the metal mask 5 described later is peeled off.

  By the way, when the taper angle of the contact hole is increased, there is a possibility that the step coverage of the wiring layer (metal film) formed on the inner wall surface of the hole by sputtering is deteriorated. In particular, when the diameter of the contact hole is small and the aspect ratio is high, the wiring layer may be disconnected.

Therefore, the present inventor conducted intensive research and found that the taper angle of the inner wall surface in the contact hole depends on the inclination angle (taper angle) of the opening side surface of the metal mask. Then, the taper angle of the metal mask was set variously, and an experiment for measuring the taper angle of the contact hole formed by using this metal mask was conducted. The experimental results shown in Table 1 were obtained from this experiment.
Hereinafter, the operation of the metal mask 5 also used in the present embodiment will be described.

  As shown in Table 1, it can be seen that as the taper angle of the metal mask increases, the taper angle of the contact hole formed by etching decreases. It can also be seen that when a metal mask having a taper angle of 20 degrees or more with respect to the film to be etched is used, the taper angle of the contact hole is 80 degrees or less.

Here, the reason why the taper angle of the contact hole formed by etching decreases as the taper angle of the metal mask with respect to the etching target film increases.
When the etching target film is dry-etched, a reactive organism is formed between the etching gas and the etching target film.

  When the taper angle θ1 of the metal mask 50 with respect to the etching target film 51 is small (for example, 20 degrees), as shown in FIG. 2A, the distance between the inner wall surfaces of the metal mask 50 is long and the reactive organism X is masked. It is difficult to adhere to the bottom side of the side wall, and etching is not hindered by the deposition of the reactive organism X. As a result, the etching proceeds well in the thickness direction of the film to be etched 51, and the contact hole 52 having a large taper angle θ2 (for example, 80 degrees) is formed.

On the other hand, when the taper angle θ3 of the metal mask 50 (corresponding to the metal mask 5 in FIG. 1) with respect to the etching target film 51 (corresponding to the interlayer insulating film 2 in FIG. 1) is large (for example, 90 degrees), FIG. As shown in FIG. 2, the distance between the inner wall surface (tapered portion 50a) of the metal mask 50 and the film to be etched 50 is shorter than that in FIG. 2A, and the reaction product X easily adheres to the bottom side of the mask side wall. Therefore, the etching is inhibited by the deposition of the reaction product X. As a result, the etching rate is reduced as compared with the case of FIG. 2A, and the contact hole 52 having a small taper angle θ4 (for example, 65 degrees) is formed.
For example, when contact hole etching is performed using the Mo film as a mask as the metal mask 50, the following reaction is performed. Note that the etching gas here is C ₂ HF ₅ .
C ₂ HF ₅ introduced into the chamber generates CFx, CHFy and F by a dissociation reaction (hereinafter, only CFx and F will be described for the sake of simplicity). The generated CFx and F arrive at the substrate surface and react with the Mo film as the metal mask 50 and the SiO ₂ film as the etching target film 51. Reactive organisms produced by the reaction are MoF and SiFx, respectively, and their boiling points are 35 ° C. and −86 ° C., respectively. Dry etching proceeds when a reaction gas reacts with a film to be etched and a reaction product generated by the reaction is vaporized. The ease of etching is determined by the ease of vaporization of the reaction product and is represented by the boiling point. Since the boiling point of SiFx is lower than that of MoF, the SiO ₂ film is more easily etched than the Mo film. Furthermore, MoF having a high boiling point immediately returns to a solid even when vaporized, and adheres to the substrate surface and the chamber side wall. That is, it is considered that the following three reactions occur simultaneously on the substrate surface.
1. Reaction between reaction gas (CFx and F) and substrate surface (Mo film and SiO ₂ film).
2. Detachment of reaction products (MoF and SiFx) from the substrate surface (Mo film and SiO ₂ film).
3. Reattachment of reaction product (MoF) to substrate surface (Mo film and SiO2 film).
On the surface of the SiO ₂ film that is the etching target film 51, a reaction between the reaction gas (CFx and F), the SiO ₂ film, and the reattached MoF occurs. The etching rate of the SiO ₂ film decreases as the amount of MoF reattached increases. The amount of MoF reattached to the SiO ₂ film increases as the taper angle of the Mo film increases as the Mo film is closer. That is, the etching rate of the SiO ₂ film becomes smaller as the distance from the Mo film becomes shorter and the taper angle of the Mo film becomes larger, and as a result, the taper angle of the contact hole becomes smaller.
On the Mo surface which is the metal mask 50, the reaction between the reactive gas, the Mo film, and the reattached MoF occurs. Etching of the Mo film hardly proceeds because MoF is reattached to the surface in addition to the poor volatility of MoF. For this reason, the etching in the lateral direction does not proceed and the conversion difference can be kept small.
In this way, by utilizing the adhesion of the reaction product MoF generated by the reaction between the reaction gas and the Mo film to the substrate surface, the difference (conversion difference) between the opening diameter of the metal mask and the opening diameter of the contact hole is obtained. The taper angle of the contact hole can be reduced while keeping it small.

By the way, when the contact hole diameter is 2.0 μm or less, disconnection of the wiring in the contact hole is likely to occur. For example, when the hole diameter (hole diameter) is 2.0 μm and the hole height (hole depth) is 0.6 μm (the aspect ratio is 0.30 (0.6 μm / 2.0 μm)), the contact hole By setting the taper angle of the inner wall surface (tapered portion 50a) to 80 degrees or less, more preferably 76 degrees or less, good step coverage can be obtained and the occurrence of disconnection can be prevented.
When the hole diameter is 2.0 μm and the hole height is 0.7 μm (the aspect ratio is 0.35 (0.7 μm / 2.0 μm)), the taper angle of the inner wall surface of the contact hole is 76 degrees or less. More preferably, by setting the angle to 71 degrees or less, good step coverage can be obtained and the occurrence of disconnection can be prevented.
When the hole diameter is 1.5 μm and the hole height is 0.7 μm (the aspect ratio is 0.46 (0.7 μm / 1.5 μm)), in order to prevent disconnection, the inner wall surface of the contact hole Is preferably set to 73 degrees or less, more preferably 65 degrees or less. That is, the smaller the hole diameter, the smaller the taper angle of the contact hole.

Returning to the description of the contact hole manufacturing process, the interlayer insulating film 2 is dry-etched using the metal mask 5 as shown in FIG. Since the metal mask 5 includes the taper portion 5a inclined at 20 degrees or more with respect to the interlayer insulating film 2, a desired taper angle is obtained even when the contact hole diameter is as small as 2.0 μm or less and the aspect ratio is high. Can be formed. Further, since the contact hole can be formed only by the dry etching process, the controllability of the etching is easy, and furthermore, a highly accurate one with little processing conversion difference can be obtained. As an etching gas, one having a high selectivity with respect to the metal mask 5 (Mo film), for example, C ₂ HF ₅ is used. As an etching gas, CF ₄ , C ₄ F ₈ , CHF ₃ , and CH ₂ F ₂ can be used in addition to C ₂ HF ₅ .

Subsequently, as shown in FIG. 3B, the metal mask 5 is removed with a solution. As a solution for removing the metal mask 5 (Mo film), phosphoric acid, nitric acid, acetic acid, or a mixed solution thereof can be used. When a Ti film is used as the metal mask 5, hydrofluoric acid, nitric acid, or a mixed solution thereof can be used.
By removing the metal mask 5 in this manner, a contact hole 7 exposing the conductive portion 6 is formed in the interlayer insulating film 2 as shown in FIG.

In this embodiment, the resist mask 4 is peeled off as shown in FIG. 1D prior to the dry etching process of the interlayer insulating film 2. However, in the present invention, the resist mask 4 is not peeled off. (The step of FIG. 1D is omitted), and the interlayer insulating film 2 can be dry etched using the resist mask 4 and the metal mask 5 as a mask. Thereby, it is not necessary to separately perform a step of removing the resist mask 4, and the manufacturing process can be simplified.
The taper angle of the contact hole 7 formed in the interlayer insulating film 2 can also be adjusted by changing the film thickness of the metal mask 5.

  The contact hole forming method described above can be applied to a pattern forming method for forming a pattern such as a wiring having a desired taper angle by using the metal mask 5 having the taper angle as described above. That is, in the pattern forming method of the present invention, a metal film is formed on a film formed on a substrate, a resist mask is formed on the metal film, and the resist mask is used as a mask while retracting the resist mask. Forming a metal mask having a taper portion whose opening side surface forms an inclined surface of 20 ° or more with respect to the film by dry etching, patterning the film by dry etching using the metal mask, and metal mask The process of removing. According to the pattern forming method of the present invention, since the metal mask 5 includes the tapered portion 5a having an inclined surface of 20 degrees or more with respect to the film to be etched, the etching region has a pattern that is fine and has a tapered shape. Even if it exists, it can form with sufficient precision.

(Method for manufacturing electro-optical device)
Next, a case where the present invention is applied to a manufacturing process of a liquid crystal display device will be described as an embodiment of a method for manufacturing an electro-optical device of the present invention. First, since the manufacturing method of the present invention is characterized in that a TFT array substrate on which TFT elements as switching elements are formed is formed, the manufacturing process of the TFT array substrate will be mainly described. The contact hole forming process described above is used as part of the manufacturing process of the TFT array substrate.

First, the liquid crystal display device manufactured by this method will be described.
FIG. 4 is a plan view of the liquid crystal display device according to the present invention as seen from the counter substrate side shown together with each component, and FIG. 5 is a cross-sectional view taken along the line HH ′ of FIG. FIG. 6 is an equivalent circuit diagram of various elements and wirings in a plurality of pixels formed in a matrix in the image display area of the liquid crystal display device, and FIG. It is an expanded sectional view which shows a part. In each drawing used in the following description, the scale is different for each layer and each member so that each layer and each member can be recognized on the drawing.

  4 and 5, the liquid crystal display device (electro-optical device) 100 according to the present embodiment is bonded to the TFT array substrate 10 and the counter substrate 25 which form a pair by a sealing material 54 which is a photo-curable sealing material. The liquid crystal 55 is sealed and held in a region partitioned by the sealing material 54.

  A peripheral parting 53 made of a light shielding material is formed in a region inside the region where the sealing material 54 is formed. A data line driving circuit 201 and a mounting terminal 202 are formed along one side of the TFT array substrate 10 in a region outside the sealing material 54, and the scanning line driving circuit 204 is formed along two sides adjacent to the one side. Is formed. On the remaining side of the TFT array substrate 10, a plurality of wirings 205 are provided for connecting between the scanning line driving circuits 204 provided on both sides of the image display area. In addition, an inter-substrate conductive material 206 for providing electrical continuity between the TFT array substrate 10 and the counter substrate 25 is disposed in at least one corner of the counter substrate 25.

In the liquid crystal display device 100, depending on the type of the liquid crystal 55 to be used, that is, depending on the operation mode such as TN (Twisted Nematic) mode, STN (Super Twisted Nematic) mode, or normally white mode / normally black mode. A retardation plate, a polarizing plate, and the like are arranged in a predetermined direction, but the illustration is omitted here.
In addition, the liquid crystal display device 100 has, for example, red (R), green (G), and blue (B) color filters (non-uniform) in a region of the counter substrate 25 facing each pixel electrode (to be described later) of the TFT array substrate 10. As shown, a full color display is possible.

  In the image display area of the liquid crystal display device 100 having such a structure, as shown in FIG. 5, a plurality of pixels 100a are arranged in a matrix, and each of these pixels 100a has a pixel switching area. TFT (switching element) 30 is formed, and a data line 6 a for supplying pixel signals S 1, S 2,..., Sn is electrically connected to the source of the TFT 30. Pixel signals S1, S2,..., Sn to be written to the data lines 6a may be supplied line-sequentially in this order, or may be supplied for each group to a plurality of adjacent data lines 6a. . Further, the scanning line 3a is electrically connected to the gate of the TFT 30, and the scanning signals G1, G2,..., Gm are applied to the scanning line 3a in a pulse-sequential manner in this order at a predetermined timing. It is configured.

  The pixel electrode 9 is electrically connected to the drain of the TFT 30, and the pixel signal S1, S2,..., Sn supplied from the data line 6a is obtained by turning on the TFT 30 as a switching element for a certain period. Write to each pixel at a predetermined timing. The pixel signals S1, S2,..., Sn written in the liquid crystal via the pixel electrode 9 in this way are held for a certain period with the counter electrode 21 of the counter substrate 25 shown in FIG. In order to prevent the retained pixel signals S1, S2,..., Sn from leaking, a storage capacitor 60 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9 and the counter electrode 21. For example, the voltage of the pixel electrode 9 is held by the storage capacitor 60 for a time longer than the time when the source voltage is applied. Thereby, the charge retention characteristics are improved, and the liquid crystal display device 100 with a high contrast ratio can be realized. Reference numeral 3 b denotes an auxiliary capacitance line connected to the counter electrode 21.

  FIG. 7 shows a partially enlarged view around the TFT 30 of the TFT array substrate 10 in the liquid crystal display device 100. As shown in FIG. 7, the TFT array substrate 10 includes a TFT 30 having a semiconductor layer 12, a gate electrode 14, a drain electrode 19, and a source electrode 22.

  The TFT array substrate 10 includes a semiconductor layer 12 made of polysilicon formed on a substrate body 10A via a base insulating film 11 made of a silicon oxide film. A gate electrode 14 is provided on the semiconductor layer 12 via a gate insulating film 13 made of a silicon oxide film. A first interlayer insulating film 15 made of silicon oxide or the like is formed so as to cover the gate electrode 14.

  The first interlayer insulating film 15 and the gate insulating film 13 expose the contact hole 17 that exposes the drain region (active region) 12A of the semiconductor layer 12 and the source region (active region) 12B of the semiconductor layer 12. A contact hole 20 is formed. Further, on the first interlayer insulating film 15, a drain electrode (conductive portion) 19 connected to the drain region 12 </ b> A through the contact hole 17 and a source electrode (connected to the source region 12 </ b> B through the contact hole 20). Conductive portion) 22 is provided. A second interlayer insulating film 16 made of silicon oxide is formed so as to cover the drain electrode 19 and the source electrode 22. In addition, a contact hole 23 for exposing the drain electrode 19 is formed in the second interlayer insulating film 16. A pixel electrode 9 is formed on the second interlayer insulating film 16, and the pixel electrode 9 is connected to the drain electrode 19 through the contact hole 23.

The manufacturing method of the liquid crystal display device according to the present embodiment applies the above-described contact hole forming method to the interlayer insulating film (the first interlayer insulating film 15 and the gate insulating film 13) that covers the TFT 30 on the substrate body 10A. Forming the contact holes 17 and 20 and forming the source electrode 22 and the drain electrode 19 in the contact holes 17 and 20.
The substrate body 10A in the manufacturing method of the liquid crystal display device corresponds to the base material 1 in the contact hole forming method shown in FIGS. 1 and 2, and the first interlayer insulating film 15 and the gate insulation in the manufacturing method of the liquid crystal display device. The film 13 corresponds to the interlayer insulating film 2 shown in FIGS. 1 and 2, and the drain region 12A and the source region 12B in the manufacturing method of the liquid crystal display device correspond to the conductive portion 6 shown in FIGS.

Therefore, even in the method of manufacturing the liquid crystal display device according to the present embodiment, since the metal mask 5 is used, even when the hole diameter is small and the aspect ratio is high, the taper angle is controlled well, so that the source The contact holes 17 and 20 for forming the source electrode 22 and the drain electrode 19 connected to the region 12B or the drain region 12A can be formed in a state having a desired taper angle. Therefore, as described above, the inner wall surfaces of the contact holes 17 and 20 have a desired taper angle (which is less likely to cause disconnection). Therefore, when the source electrode 22 and the drain electrode 19 are formed by, for example, sputtering, it is preferable. Step coverage can be obtained, and the occurrence of disconnection is prevented.
Further, the liquid crystal display device 100 according to the present embodiment can be used for electronic devices such as a mobile phone and a PC (personal computer). In the mobile phone, the liquid crystal display device 100 according to the present embodiment is used for the display screen. Further, in a PC, it can be used for an input unit such as a keyboard and a display screen. In addition, by incorporating the peripheral circuit in the substrate in the liquid crystal panel, the number of parts can be greatly reduced, and the apparatus body can be reduced in weight and size.

  In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning of this invention, it can change suitably. For example, in the above-described embodiment, the liquid crystal display device has been described as the electro-optical device. However, the source / drain electrodes that are conductive through the contact holes manufactured by the above-described method are provided in the source / drain regions of the semiconductor layer constituting the TFT. The present invention is also applicable to an organic EL device including an electro-optical device substrate, an electrophoretic display device, and the like.

It is a figure explaining the formation process of a contact hole. It is a figure explaining the relationship between a metal mask and the taper angle of a contact hole. It is a figure explaining the formation process of the contact hole following FIG. It is a plane block diagram of a liquid crystal display device. It is sectional drawing which follows the H-H 'line | wire of FIG. 3 of a liquid crystal display device. It is an equivalent circuit diagram of a liquid crystal display device. It is an enlarged view which shows the principal part of the TFT array substrate of a liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Base material, 2 ... Interlayer insulating film (film | membrane), 3 ... Metal film, 4 ... Resist mask, 5 ... Metal mask, 6 ... Conductive part, 7 ... Contact hole, 12 ... Semiconductor layer, 13 ... Gate insulating film ( Interlayer insulating film), 15 ... first interlayer insulating film (interlayer insulating film), 17, 20 ... contact hole, 19 ... drain electrode (conductive portion), 22 ... source electrode (conductive portion), 100 ... liquid crystal display device (electrical) Optical device)

Claims (8)

Forming a metal film on the film formed on the substrate;
Forming a resist mask on the metal film;
Dry etching the metal film using the resist mask and controlling a receding amount of the resist mask by the dry etching to form a metal mask having an opening side surface having a first inclination angle with respect to the film; ,
The film is dry-etched using the metal mask having the first inclination angle to expose the conductive part formed on the surface of the base material, and the opening side surface is the first with respect to the conductive part. Forming a hole having a second inclination angle according to the inclination angle;
Removing the metal mask;
A method for forming a contact hole, comprising:   2. The contact hole forming method according to claim 1, wherein in the step of forming the hole, dry etching is performed using the resist mask as a mask together with the metal mask.   3. The method according to claim 1, wherein the step of forming the metal mask controls an amount of recession of the resist mask by the dry etching by controlling an addition amount of a gas for etching the resist mask. Contact hole formation method. In the step of forming the metal mask, the first inclination angle is controlled from about 20 degrees to about 90 degrees by controlling a receding amount of the resist mask by the dry etching,
The step of forming a hole includes forming the hole at a second inclination angle of about 80 degrees to about 60 degrees according to the first inclination angle. A method for forming a contact hole as described. The hole aspect ratio (hole depth / hole diameter) is greater than 0.3;
The contact hole forming method according to claim 1, wherein the first inclination angle is approximately 90 degrees. Forming a metal film on the film formed on the substrate;
Forming a resist mask on the metal film;
Dry etching the metal film using the resist mask and controlling a receding amount of the resist mask by the dry etching to form a metal mask having an opening side surface having a first inclination angle with respect to the film; ,
The film is dry-etched using a metal mask having the first tilt angle, and the side surface of the etched film has a second tilt angle corresponding to the first tilt angle with respect to the metal film. Forming a pattern having:
Removing the metal mask;
A pattern forming method comprising:   The pattern forming method according to claim 6, wherein in the step of forming the pattern of the film, dry etching is performed using the resist mask as a mask together with the metal mask. In the manufacturing method of the electro-optic layer formed by sandwiching the electro-optic layer between a pair of substrates,
Forming a metal film on an insulating film covering an active region in a semiconductor layer constituting a switching element formed on one side of the substrate;
Forming a resist mask on the metal film;
Dry etching the metal film using the resist mask and controlling a receding amount of the resist mask by the dry etching to form a metal mask having an opening side surface having a first inclination angle with respect to the film; ,
The active region is exposed by dry etching using the metal mask having the first inclination angle, and the opening side surface is a second inclination angle corresponding to the first inclination angle with respect to the conductive portion. Forming a hole having a hole in the insulating film;
Removing the metal mask;
Forming a conductive portion connected to the active region through the hole;
A method for manufacturing an electro-optical device.

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