JP4361415B2 - Al taper dry etching method - Google Patents

Description

  The present invention relates to a method of processing aluminum (Al) or an Al alloy (hereinafter collectively referred to as “Al”) used as a wiring material for thin film elements such as LSIs and liquid crystal displays. The present invention particularly relates to an Al gate wiring of an active matrix type liquid crystal display represented by a thin film transistor (TFT) and a taper dry etching method for other Al wiring.

  Conventionally, in a liquid crystal display, unlike an LSI having a minimum pattern line width of 1 μm or less, it is usually as wide as 2 to 10 μm or more. For the gate wiring, Cr, Ta, Mo, W or an alloy thereof is generally used because of ease of processing and chemical resistance. However, with an increase in screen size and resolution, signal delay due to an increase in electrical resistance of the gate wiring has become a problem. Moreover, in order to reduce the gate line width as much as possible and increase the aperture ratio of the panel, an Al gate electrode having a low electric resistance has been desired.

  Further, Al can be processed by wet etching using nitric acid, phosphoric acid or acetic acid, or dry etching using Cl-based gas. Currently, wet etching is mainly used when using Al in liquid crystal displays. However, when considering miniaturization of wiring, ensuring reproducibility, reducing waste, and reducing costs, it is the same as LSI. It is considered that Al processing is directed from wet etching to dry etching.

FIG. 8 is a cross-sectional view of a TFT of a liquid crystal display described on pages 88 to 99 of Flat Panel Display '91 (published by Nikkei BP). In the figure, 1 is a substrate made of glass or quartz, 2 is a gate wiring made of Al, Cr, Ta, Mo, W or the like, 3 is a gate insulating film made of Si ₃ N ₄ , SiO ₂ or Al ₂ O ₃ or the like. 4 is a channel made of a-Si or poly-Si, 5 is a source / drain made of a-Si or poly-Si implanted with an impurity such as P or B, 6 is Al, Cr, Ta, Mo or A source / drain electrode made of W or the like, and 7 is a protective film made of Si ₃ N ₄ or SiO ₂ . This structure is called a channel etch type bottom gate structure.

  The TFT generally has a bottom gate structure as shown in FIG. 8, and it is necessary to form a gate insulating film, a channel and the like on the gate wiring. It is clear from many experiments that a small taper angle θ of at least 60 ° or less, preferably 40 ° or less is desirable, considering the coverage of the film formed on the gate wiring, the withstand voltage of the gate insulating film, and TFT characteristics. Became. However, since the Al dry etching technique used in LSI technology is mainly aimed at miniaturization of 1 μm or less, it is aimed at vertical reversal to taper, and the taper angle θ is usually 70. ~ 90 °.

As an Al taper dry etching technique, for example, Japanese Patent Application Laid-Open No. 64-15933 describes a method using two etching steps of vertical etching and over-etching for taper. However, there is a problem in that even the underlying substrate (substrate) made of SiO ₂ or Si ₃ N ₄ is etched by over-etching.

Further, as a taper dry etching method, for example, there is a sidewall formation method in which deposits (depots) are positively formed on the sidewall surface of a processed film to be etched to control lateral etching, and oxygen or the like is used as an etching gas. There is a resist receding method in which etching of the resist mask is promoted by adding.

However, the side wall forming method is not preferable because the surface of the tapered portion is likely to be rough due to deposits and the generation of dust is increased. Further, the conventional resist receding method has a defect that oxygen in the etching gas causes dust generation during Al etching, and there is room for improvement.

  Further, the isotropic etching method has a problem that etching residues are easily generated.

  In view of the above problems, an object of the present invention is to provide an Al taper dry etching technique based on a resist receding method capable of reducing the Al taper angle of an Al gate wiring of a liquid crystal display. It is another object of the present invention to provide conditions under which Al taper can be realized by a dry etching process that is as simple as possible with almost no underlying etching problem.

  It has been found that the Al taper dry etching method for obtaining a small Al taper angle is effective based on the resist receding method.

The resist receding method of the present invention is characterized by forming a small resist taper angle without adding oxygen to the etching gas and obtaining a small Al taper angle by anisotropic dry etching.

  The Al taper dry etching method according to the present invention is as follows.

  Al taper dry based on a resist receding method for obtaining a small Al taper angle comprising a step of forming a resist pattern having a small resist taper angle corresponding to a desired small Al taper angle and an ionic anisotropic dry etching step. Etching method.

  In the resist pattern forming step, post-baking is preferably performed at or above the resist pre-baking temperature after resist development.

  In the resist pattern forming step, it is preferable that the focal position at the time of exposure deviates from the focal range with respect to the line width of the exposure machine.

  In the resist pattern forming step, the γ value in the resist sensitivity curve is preferably 1.5 or less.

  As the dry etching, parallel plate RIE type ionic etching in which high frequency power is applied to the substrate side or other plasma etching in which high frequency power is applied to the substrate side can be considered.

  The gas pressure in the dry etching process is preferably 30 mTorr or less.

The main reactive gas of the gas in the dry etching process is preferably BCl ₃ and the BCl ₃ concentration is preferably 80 to 100%.

  It is better that the ratio of the etching rate of Al to the resist in the dry etching process is 1.0 or less and the etching rate of the resist is fast.

  A fluorine-based gas is preferably added to the gas in the dry etching process.

  According to the present invention, a resist pattern having a small taper angle is transferred to Al by giving conditions for reducing the resist taper angle, ionic anisotropic etching conditions, and taper promoting conditions, and the Al tape of 60 ° or less is transferred. A taper angle can be obtained. Therefore, it is possible to contribute to improving the coverage of the film formed on the Al gate wiring, the breakdown voltage of the gate insulating film, and the TFT characteristics.

  The present invention relates to an Al taper dry etching method based on a resist receding method for obtaining a small Al taper angle, which comprises a step of forming a resist pattern having a small resist taper angle and a step of performing anisotropic dry etching.

In the present invention, as shown in FIG. 1, the Al taper angle is an angle θ ₁ formed by the taper portion (inclined portion) of the Al gate wiring and the substrate surface, and the resist taper angle is the resist taper portion and the Al processed film. Is an angle θ ₂ formed by the upper surface (where 1 is a substrate, 8 is Al, and 9 is a resist).

There are various methods for reducing the resist taper angle as follows.
(1) During resist formation: A method of reducing the aspect ratio (resist film thickness / resist line width). This is because the resist taper angle can be reduced because the resist is easily pulled in the lateral direction when the resist shrinks in volume during post-baking.

(2) During exposure (a) A method in which the focal position deviates from the focal range with respect to the line width of the resist. Here, the focus range refers to a range in which a substantially vertical resist pattern can be formed. If the focus range is deviated from this range, the resist is necessarily tapered.
(B) A method of overexposure in which the exposure amount is larger than the optimum exposure amount. This is because the resist taper angle can be reduced because the resist which is not originally exposed is partially exposed by light diffraction and is dissolved in the developer. The optimum exposure amount is an exposure amount when the reticle (mask) dimension and the resist dimension match.
(C) A method in which the resolution of the exposure machine is made lower than the line width of the resist pattern. When the resolution is lower than the resolution at which a vertical resist pattern can be formed (the line width of the resist pattern is made smaller than the resolvable line width), the formed resist is tapered.

(3) During development: A method of increasing the solubility of the resist. In this case, this can be achieved by adjusting the temperature, density, etc. of the developer.

(4) Post-baking A method of causing resist volume shrinkage by performing post-baking at a temperature equal to or higher than the pre-baking temperature in the resist drying (solvent volatilization) step before exposure. This removes the volatile components in the resist that could not be sufficiently volatilized during pre-baking, thereby shrinking the volume of the resist and consequently reducing the resist taper angle. In particular, post-baking at a temperature higher than the softening point of the resist is advantageous because the resist taper angle can be reduced by softening and flowing the resist itself.

  The above methods may be used alone or in appropriate combination.

  The conditions for performing the above method will be described in the following examples. In particular, in order to obtain a desired small Al taper angle in the present invention, a resist taper of 80 ° or less with respect to an Al taper angle of 60 ° or less. The resist taper angle is 70 ° or less with respect to the Al taper angle of 40 ° or less for the reason of improving the corner, TFT characteristics of the bottom gate structure, the coverage of the film formed on the gate wiring, and the breakdown voltage of the gate insulating film. Is preferred.

  In order to perform the resist receding method in the present invention, it is necessary to form a smaller resist taper angle corresponding to the smaller Al taper angle before etching.

  When anisotropic etching is performed on a resist pattern having a small taper angle, the resist itself is also etched. Therefore, the Al layer existing under the resist also has a taper angle corresponding to the taper angle of the resist. Become. That is, an angle corresponding to the resist taper angle can be transferred to Al as the processed film.

  When isotropic etching is performed, Al is etched regardless of the resist shape and taper angle, and it is difficult to achieve a small Al taper angle.

  As the anisotropic dry etching, anisotropic dry etching using plasmaized ions is preferable, and parallel plate RIE type ionicity performed by applying high-frequency power to the substrate from the viewpoint that ions are incident on the substrate side. Anisotropic etching is preferred. For example, high density plasma type anisotropic dry etching known to those skilled in the art such as ECR, helical, helicon, ICP or SWP type may be performed.

Examples of the ionic anisotropic dry etching method for obtaining a small Al taper angle according to the present invention include the following.
(1) A method of reducing the gas pressure during etching. This is because the lower the gas pressure, the lower the probability of collision between ions, and the longer the mean free path of ions and the higher the etching anisotropy, the smaller the Al taper angle.

(2) A method in which the gas composition during etching contains BCl ₃ and Cl ₂ . This is because there is a track record in LSI technology as a Cl ₂ gas capable of etching Al. In this case, the concentration of BCl ₃ is preferably 80 to 100% because anisotropic dry etching is strengthened.

(3) A method of reducing the ratio of Al etching rate / resist etching rate (Al / resist selection ratio). In FIG. 1, when θ ₁ is the Al taper angle, θ ₂ is the resist taper angle before etching, M is the Al etching rate, and R is the resist etching rate, M / R is the Al / resist selectivity. , Tan θ ₁ = M / R × tan θ ₂ Therefore, the Al taper angle can be reduced because the Al taper angle is proportional to the ratio.

  The above methods may be used alone or in appropriate combination.

  The conditions for performing the method will be described in the following examples.

Example 1
The present invention is illustrated by the following examples, but the present invention is not limited to these examples.

  The present invention needs to provide two conditions: a process condition for forming a resist pattern (mask) having a small resist taper angle corresponding to a desired Al taper angle, and a process condition for performing ionic anisotropic dry etching. It is. First, resist pattern formation conditions will be described.

  FIG. 2 is a diagram showing the post-baking temperature dependence of the resist taper angle according to the present invention. From the figure, it can be seen that by performing post-baking after development, the resist taper angle becomes smaller as the post-baking temperature becomes higher. This is because post-baking at a temperature equal to or higher than the pre-baking temperature causes the organic solvent remaining in the resist that cannot be volatilized by pre-baking to volatilize, causing the resist to shrink in volume, and the resist itself at a temperature higher than the resist softening point. Resist taper (also called spheroidization) is achieved by softening and flowing (flowing). The post-bake temperature may be any temperature that can reduce the taper angle of the resist to such an extent that the resist pattern accuracy is not inferior, and depends on the softening point of the resist (for example, 140 to 150 ° C.). This is advantageous for tapering the resist.

  Next, a small Al taper angle can be obtained by performing an ionic anisotropic dry etching process of Al using this resist pattern having a small taper angle.

  Experiments were conducted with resist and Al film thicknesses of 1.5 μm and 0.25 μm, respectively, and resist line widths of 5, 10 and 50 μm (experiment numbers 1-1, 1-2 and 1-3, respectively).

The dry etching conditions at this time are a parallel plate RIE apparatus, a gas pressure of 30 mTorr, a gas composition BCl ₃ / Cl ₂ = 40/10 sccm, and a power density of 1.4 W / cm ² . As shown in FIG. 2, when using a resist pattern with a post-bake temperature of 180 ° C. in each of Experiment Nos. 1-1 to 3, the Al taper angle of an Al film having a line width of 5, 10 or 50 μm is 30 to 60 °. (Experiment Nos. 1-4 to 6).

  As can be seen from FIG. 2, the resist taper angle after post-baking is greatly different depending on the line width, and a smaller resist taper angle is obtained when the line width is wider. This is because the smaller the resist film thickness and the line width aspect ratio, the easier it is for the pattern end to be pulled in the lateral direction when the resist volume shrinks, and to be tapered.

  If the resist film thickness and the line width aspect ratio are related to the resist taper angle due to volume shrinkage during post-baking, the resist taper angle is considered to be related to the resist film thickness in addition to the post-bake temperature. If the aspect ratio is smaller, the taper is more easily tapered. If the line width is the same, the smaller the resist film thickness, the smaller the taper angle.

  FIG. 3 is a graph showing the resist coating film thickness dependence of the Al taper angle after post-baking according to the present invention. In order to obtain a resist taper angle as small as possible, the post bake temperature is 180 ° C. The Al film thickness was 0.25 μm, and the resist line width was 5, 10 or 50 μm (Experiment Nos. 1-7 to 9). A taper angle of 60 ° or less is obtained for any resist coating film thickness and line width. As described above, a smaller resist taper angle was obtained when the resist film thickness was smaller. In particular, it is more effective for Al taper to make the resist coating film thickness 1.5 μm or less, preferably 0.5 to 1.0 μm.

  Note that the method of promoting resist taper using volume shrinkage by post-baking resist after development is highly dependent on line width for the above reasons. Further, it is difficult to taper with a small line width. Therefore, a method of performing resist taper immediately after development without using post bake is preferable.

Other methods for obtaining a small resist taper angle are as follows. If the focus position at the time of exposure deviates from the focus range for the line width of the exposure machine, the vertical pattern cannot be formed because the focus is blurred, and as a result, the resist is tapered even immediately after development. The The depth of focus is proportional to wavelength / (lens aperture ratio) ² .

  Even if the exposure amount during exposure is tens to hundreds of percent higher than the optimum exposure amount, the portions that are not originally exposed by light diffraction are slightly exposed and dissolved in the developer. Is tapered. In addition, since the line width of the resist pattern becomes narrow in overexposure, it is necessary to design a mask (reticle) that allows for this thinning.

  In addition, when the line width of the resist pattern is narrower than the resolution of the exposure machine, a vertical pattern cannot be formed, so that the resist is tapered even immediately after development. In general, the resolution is defined as the minimum line width that can form a substantially vertical pattern, so an isolated pattern such as a gate wiring does not mean that a line width less than the resolution cannot be formed. If the line width is determined, in order to reduce the resolution of the exposure device, the resolution is proportional to the wavelength / lens aperture ratio NA, so the lens aperture ratio NA is, for example, about 0.1 (NA is originally larger) Is good, so keep it to the minimum necessary). Alternatively, the exposure wavelength may be longer than the g and h lines of the Hg lamp of the light source used in liquid crystal display manufacturing.

FIG. 4 is a graph conceptually showing the relationship (resist sensitivity curve) between the exposure amount and the resist residual film ratio. The resist residual film ratio on the vertical axis means resist thickness after development / resist thickness before development. The tan θ value of the tangent angle θ formed by the resist sensitivity curve and the exposure amount (logarithmic axis) on the horizontal axis is called a γ value. Currently, the γ value of a resist (for example, TFR-B (manufactured by Tokyo Ohka Kogyo Co., Ltd.)) generally used in a liquid crystal display is about 1.8. The larger this value, the easier the vertical resist pattern can be formed. Conventionally, in the case of miniaturization as in LSI, resist materials and processes have been developed so that the γ value becomes 2 or more for pattern verticalization. The ideal (vertical) resist sensitivity curve is shown as A in FIG. The present invention is a method of reducing the Al taper angle θ ₁ to curve B and curve C. If the purpose is taper, the photosensitive group of the resist material, the base resin, the pre-baking temperature (for example, 70 to 130 ° C.), and the pre-baking so that the γ value is 1.5 or less, preferably 0.5 to 1.5. If conditions such as time (for example, 30 seconds to 1 hour), developer, development temperature, and development time are selected, taper can be facilitated. For example, use a resist with a poor resist sensitivity, lower or increase the resist pre-bake temperature from the optimum temperature, or lengthen the pre-bake time to degrade the resist photosensitive group and lower the resist sensitivity. A combination of appropriate measures such as increasing the solubility of the unexposed portion of the resist by increasing or decreasing the temperature of the developer from a normal temperature (for example, 23 ° C.) and / or promoting taper by over-developing. It is also possible to do this.

  Note that the above method is not the optimum use condition in the conventional etching process, so that it is easy to deteriorate the pattern accuracy and reproducibility. However, in the case of the gate wiring of a liquid crystal display, since the line width is usually as wide as 5 μm or more, there is no need for accuracy like LSI, etc., and the gate wiring is often in the pixel design that can be handled as an isolated pattern. Therefore, the method can be performed.

Example 2
Next, conditions for promoting Al taper by ionic anisotropic dry etching will be described. In order to achieve anisotropic etching, the gas pressure during etching is the most important. Since the lower the gas pressure, the lower the probability of collision between ions and the longer the mean free path, anisotropic etching is likely to be realized.

FIG. 5 is a diagram showing the gas pressure dependence during etching of the Al taper angle. For resists with line widths of 5, 10 and 50 μm (Experiment Nos. 2-1 to 3), experiments were conducted with gas pressures of 15, 30 and 60 mTorr. The resist post-baking temperature is 180 ° C., the resist film thickness is 1.5 μm, the gas composition is BCl ₃ / Cl ₂ = 40/10 sccm, and the power density is 1.4 W / cm ² .

  From the figure, it can be seen that the smaller the gas pressure, the easier it is to taper, and in particular for any line width, 30 mTorr or less (preferably 15 mTorr or less) is good for making the taper angle 60 ° or less. If the gas pressure is as high as 60 mTorr, the etching changes from ionic anisotropic etching to radical isotropic etching, so in Al alloy films such as AlSiCu, the shape of the tapered portion is rough at the grain boundary. Or etching residues of additives such as Cu having a low vapor pressure tend to remain on the substrate.

Example 3
The gas composition is also very important for promoting anisotropic dry etching.

FIG. 6 is a diagram showing the gas composition dependency during etching of the Al taper angle. The gas pressure during etching was 30 mTorr, and conditions other than the gas composition were the same as in Example 2 (experiments for resist line widths of 5, 10 and 50 μm were performed as Experiment Nos. 3-1, 2 and 3, respectively. To do). The gas composition is generally BCl ₃ and Cl ₂ because it is a chlorine-based gas capable of etching Al. In this case, the higher the BCl ₃ concentration, the more the deposition property (depositing property) is added to the dry etching, the effect of protecting the etched Al side wall surface and preventing the lateral etching, and the strong anisotropic etching. Become. On the other hand, if the BCl ₃ concentration is low, the etched Al side wall surface is not depositable, and even if it touches Cl ₂ , the lateral etching proceeds and isotropic etching is likely to occur. In addition, the problem that the shape of the tapered portion is rough at the grain boundary is likely to occur. In this embodiment, the Al taper angle when the BCl3 concentration is 60% looks small in the figure, but in reality, the shape of the taper portion is rough and uneven (taper angle is not uniform), and is used because there is no linearity of the pattern. It was impossible. Therefore, the BCl ₃ concentration is preferably 80 to 100%.

Similar effects can be expected with SiCl ₄ as well as BCl ₃ as a gas having a deposition property (deposition property) that promotes anisotropic etching of Al.

Example 4
The basic idea of the present invention is based on the resist receding method. Therefore, the resist which is a mask is etched at the same time during Al etching.

  FIG. 7 is a diagram showing the resist taper angle dependency before etching of the Al taper angle calculated from the ratio of the resist etching rate and the Al etching rate during the anisotropic etching (Al / resist selection ratio). Those having an Al / resist selection ratio of 0.2, 0.5, 0.8, 1.0, 1.5 and 2.0 are defined as 4-1 to 6, respectively. When the Al / resist selection ratio at the time of etching is 1, the Al taper angle and the resist taper angle before the etching are the same, but when the Al / resist selection ratio is 1 or less, Al taper is promoted. Conversely, when the Al / resist selection ratio is 1 or more, Al verticalization is promoted. Therefore, an etching condition that promotes the etching rate of the resist is preferable for Al taper so that the Al / resist selection ratio is 1 or less.

As a method for promoting resist etching, it is conceivable to add a gas such as O ₂ , CF ₄ , or SF ₆ that etches the resist in the etching gas but does not etch Al.

The effect of adding CF ₄ to the etching gas having an Al taper angle was confirmed. Experiments were performed with a post-baking temperature of 180 ° C. and a resist film thickness of 1.5 μm, line widths of 5, 10 and 50 μm (experiment numbers 4-7 to 9). Here, CF ₄ was added in an amount of about 30% with respect to the total flow rate of the reaction gas of BCl ₃ and Cl ₂ . The results are shown in Table 1.

It can be seen that Al taper is promoted at any line width by promoting the resist etching rate. In a general resist receding method, O ₂ is added to accelerate the etching rate of the resist. However, in Al etching, BCl ₃ and O ₂ of the reaction gas react to form an oxide of B to form the inside of the apparatus. It cannot be used because it causes dust generation and increases the number of device defects. Therefore, it is effective that the same effect of promoting resist etching rate is added a fluorine-containing gas such as CF4 or SF ₆ can be expected.

  Note that an AlSiCu alloy gate having an extremely small taper angle of about 20 ° as an Al taper angle was obtained by the Al taper dry etching method of this embodiment.

It is explanatory drawing of an Al taper angle and a resist taper angle. It is a figure which shows the post-baking temperature dependence of the resist taper angle by Example 1 of this invention. It is a figure which shows the resist coating film thickness dependence of the Al taper angle by Example 1 of this invention. It is a figure which shows the resist sensitivity curve of Example 1 of this invention. It is a figure which shows the gas pressure dependence at the time of the etching of Al taper angle by Example 2 of this invention. It is a figure which shows the gas composition dependence at the time of the etching of Al taper angle by Example 3 of this invention. It is a figure which shows the resist taper angle dependence of Al taper angle of Example 4 of this invention. It is sectional drawing which shows the TFT structure of a liquid crystal display.

Explanation of symbols

  1 substrate, 2 gate wiring, 3 gate insulating film, 4 channel, 5 source drain, 6 source drain electrode, 7 protective film, 8 Al, 9 resist.

Claims (8)

Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
In the resist pattern forming step, post-baking at a temperature equal to or higher than the softening point of the resist after resist development,
Before the anisotropic dry etching, forming the resist taper angle at 80 ° or less by the post-baking;
The anisotropic dry etching with respect to substantially the entire film thickness of the Al or Al alloy film is performed only under one condition in which the etching gas has a BCl ₃ concentration of 80 to 100%, does not contain oxygen, and has a gas pressure of 30 mTorr or less. Consists of
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
The focus position at the time of exposure is out of the focus range for the resist pattern line width of the exposure machine,
Forming the resist taper angle at 80 ° or less by the exposure before performing the anisotropic dry etching;
The anisotropic dry etching with respect to substantially the entire film thickness of the Al or Al alloy film is performed only under one condition in which the etching gas has a BCl ₃ concentration of 80 to 100%, does not contain oxygen, and has a gas pressure of 30 mTorr or less. Consists of
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
Including a heat treatment or a development treatment in which the γ value of the resist sensitivity curve in the resist pattern forming step is 1.5 or less,
Forming the resist taper angle at 80 ° or less by the heat treatment or the development process before performing the anisotropic dry etching;
The anisotropic dry etching with respect to substantially the entire film thickness of the Al or Al alloy film is performed only under one condition in which the etching gas has a BCl ₃ concentration of 80 to 100%, does not contain oxygen, and has a gas pressure of 30 mTorr or less. Consists of
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
The film thickness after drying of the applied resist is 1.5 μm or less, and the aspect ratio is 3/10 or less,
The anisotropic dry etching with respect to substantially the entire film thickness of the Al or Al alloy film has a predetermined etching gas concentration of 80 to 100%, and the predetermined etching gas is BCl ₃ or SiCl ₄ .
It consists of only one process that does not contain oxygen and has a gas pressure of 30 mTorr or less,
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
Overexposure when the exposure amount at the time of exposure is greater than the optimal exposure amount,
Forming the resist taper angle at 80 ° or less by the overexposure before performing the anisotropic dry etching;
The anisotropic dry etching with respect to substantially the entire film thickness of the Al or Al alloy film has a predetermined etching gas concentration of 80 to 100%, and the predetermined etching gas is BCl ₃ or SiCl ₄ .
It consists of only one process that does not contain oxygen and has a gas pressure of 30 mTorr or less,
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. Forming a resist pattern having a small resist taper angle corresponding to a desired small taper angle on the Al or Al alloy film;
A step of performing anisotropic dry etching on the Al or Al alloy film having the resist pattern,
An Al taper dry etching method based on a resist recession method for obtaining a taper angle of a small Al or Al alloy,
The resolution of the exposure machine is lower than the resist pattern line width to be formed,
In the anisotropic dry etching step with respect to substantially the entire film thickness of the Al or Al alloy film, a predetermined etching gas concentration is 80 to 100%, and the predetermined etching gas is BCl ₃ or SiCl ₄ ,
It consists of only one process that does not contain oxygen and has a gas pressure of 30 mTorr or less,
An Al taper dry etching method for obtaining a pattern in which the taper angle of Al or Al alloy is 60 ° or less and the shape of the taper portion is not rough. The Al taper dry etching method according to claim 1, wherein in the dry etching step, a ratio of an Al etching rate to a resist etching rate during etching is 1.0 or less. The Al taper dry etching method according to claim 1, wherein a fluorine-containing compound gas is added to the etching gas in the dry etching step.

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