CN106933054B - Graphical process method - Google Patents

Abstract

The invention provides a patterning process method, directly coating photoresist on the light-transmitting substrate, directly coating the photoresist on the light-transmitting substrate, after exposing the front side of the light-transmitting substrate, the visible The minimum luminous flux received by the region is defined as E _T , and then the backside of the light-transmitting substrate is exposed, and the minimum luminous flux required to make the photoresist react is defined as E ₀ , then the exposure dose E _B used for the backside exposure satisfies E ₀ >E _B >E ₀ ‑E _T , so that the luminous flux received by the bottom of the visible area is E _B +E _T , then E _B +E _T >E ₀ , so the photoresist at the bottom of the visible area can generate light acid reaction, and the luminous flux received by the light-shielding area is only E _B , because E ₀ >E _B , the photoresist in the light-shielding area still cannot undergo photoacid reaction, which solves the problem of the photoresist receiving light at the bottom of the light-shielding area in the traditional process. The photoacid reaction cannot occur due to insufficient luminous flux, which leads to the problem of photoresist residue, which improves the photolithography resolution.

Description

A graphical process method

technical field

The invention relates to the field of semiconductor photolithography, in particular to a patterning process method.

Background technique

In recent years, with the rapid development of the flat panel industry and the continuous emergence of high-resolution display technology, it is required that the liquid crystal pixels be miniaturized, thus posing new challenges to the flat panel manufacturing process, and the key to the miniaturization of liquid crystal pixels is high resolution photolithography.

In the TFT (Thin Film Transistor, thin film transistor) manufacturing process, in order to ensure the maximum yield, a low dose of positive photoresist is generally used in production, and the positive photoresist is also called positive photoresist. Positive photoresist resins are a type of novolac formaldehyde called novolac, which dissolves in the developer when no dissolution inhibitor is present. Before exposure, DNQ (diazonaphthoquinone) is a strong dissolution inhibitor and a photosensitizer, which can reduce the dissolution rate of the resin. After ultraviolet exposure, DNQ chemically decomposes in the photoresist and becomes solubility Enhancer, which greatly increases the solubility factor in the developer to 100 or higher. This exposure reaction will generate carboxylic acid in DNQ, which has a high solubility in the developer, which means that the positive photoresist will undergo a photoacid reaction to decompose when it encounters ultraviolet light. In the subsequent developer, The substances formed by the photoacid reaction dissolve in the developer solution and are removed. Correspondingly, when the negative photoresist encounters ultraviolet light, it will produce a monomer polymerization reaction, and the produced substance cannot be dissolved in the corresponding developer solution, while the part that has not encountered ultraviolet light does not undergo a chemical reaction, and will occur in the corresponding developer solution. dissolve and be removed.

The traditional patterning process method is as follows: please refer to Figure 1, a metal layer and a photoresist layer are sequentially formed on the light-transmitting substrate 01, and then the photoresist 02 is exposed and developed. After exposure and development, the photoresist 02 pattern left is the pattern of the metal circuit to be formed later, and then the metal not covered by the photoresist 02 is etched and removed. At this time, the metal circuit covered by the photoresist 02 Since it is protected by the photoresist 02 , it remains. When the photoresist 02 is peeled off, a metal circuit is formed on the light-transmitting substrate 01 . Therefore, if the photoresist 02 used is positive, then the mask plate 04 used in the exposure is positive, that is, the part of the circuit pattern that needs to leave the metal 03 is black, and the part of the photoresist that blocks ultraviolet light The irradiation of 02, here called the shading area, needs to remove the part of the metal 03 corresponding to the color of the mask plate 04, which is transparent, so that the ultraviolet light passes through the mask plate 04 to carry out the photoresist 02 on this part. Irradiation, here is called the visible area, so after development, the metal layer in the visible area is not covered by photoresist 02, and the metal 03 at this position can be easily removed by etching.

Due to the miniaturization of semiconductor devices, the metal lines that need to be formed also tend to be miniaturized. In particular, the width of the metal lines and the distance between the lines are required to be smaller and smaller. The minimum distance between the pattern lines formed by exposure Called the lithography resolution. If the photolithographic resolution is low, the metal between the metal lines that should be removed by etching is retained due to the residual photoresist 02 on the upper layer, which seriously affects the lines in the entire semiconductor device. The remaining photoresist 02 in the upper layer is mainly because the received light flux cannot cause photoacid reaction when receiving exposure.

For the photoresist itself, the exposure dose and the photolithography resolution are a pair of contradictions, through the minimum line width formula (Lmin is the minimum line width, s is the exposure dose, and q is the dose required for a single photon or electron reaction). It can be seen that the smaller the exposure dose, the larger the minimum line width, that is, the lower the lithography resolution, but if blindly increasing the exposure Dose, then the light is too strong, so that the light-transmitting substrate 01 and even the photoresist 02 itself will have a strong refraction, causing the photoresist 02 in the light-shielding area to be affected by the refracted light, resulting in a photoacid reaction.

In the photolithography process, after the photoresist 02 in the visible area is irradiated from the front, the photoresist 02 on the top can generally be clearly distinguished, but the photoresist 02 on the bottom is often due to the photoresist 02. The thickness of 02 is relatively large, so that after the light passes through the photoresist 02, the luminous flux attenuates, then the luminous flux received by the bottom is not enough to chemically decompose the bottom photoresist 02, resulting in the residue of the bottom photoresist 02 . In addition, after the photoresist 02 is exposed to light from the front, when etching the metal layer, if the metal 03 is etched by wet method, the sidewall of the bottom metal layer is not protected by the photoresist, and it will be etched by flow The lateral corrosion of the liquid may easily cause problems such as side etching; if dry etching is used, please refer to Figure 2, the cross section of the entire photoresist line formed is similar to a trapezoid, if the photoresist 02 remains between the two lines, Cover the metal 03 that needs to be etched and removed below, so that the ion etching gas cannot be released to the metal 03 that needs to be etched and removed. Then after etching and deglue, the two lines will be partially adhered, which will affect The entire metal circuit.

Therefore, in view of the above problems, it is necessary to invent a patterning process method, which can improve the resolution of photolithography, and at the same time avoid the problems of lateral corrosion of the metal circuit layer or adhesion of the metal circuit.

Contents of the invention

In order to solve the above problems, the present invention proposes a patterning process method, directly coating photoresist on the light-transmitting substrate, directly coating photoresist on the light-transmitting substrate, and After exposure, the minimum luminous flux received by the visible light area is defined as E _T , and then the backside of the light-transmitting substrate is exposed, and the minimum luminous flux required to make the photoresist react is defined as E ₀ , then the backside exposure used The exposure dose E _B satisfies E ₀ >E _B >E ₀ -E _T , so that the luminous flux received by the bottom of the light area is E _B +E _T , then E _B +E _T >E ₀ , so the light flux at the bottom of the light area is The photoresist can undergo photoacid reaction, and the luminous flux received by the shading area is only E _B , since E ₀ >E _B , the photoresist in the shading area still cannot undergo photoacid reaction. The light flux received by the photoresist at the bottom of the optical area is insufficient to cause photoacid reaction, which leads to the problem of photoresist residue, which improves the photolithography resolution.

In order to achieve the above object, the present invention provides a patterning process method, which sequentially includes the following steps:

Next steps:

Step 1: Coating photoresist on the light-transmitting substrate;

Step 2: exposing the front side of the light-transmitting substrate through a mask;

Step 3: Expose the backside of the light-transmitting substrate. In step 2, the minimum luminous flux received by the light-seeing area is defined as E _T , and the minimum luminous flux required to make the photoresist react is defined as E ₀ , then the transparent The light flux E _B used for the backside exposure of the optical substrate satisfies E ₀ >E _B >E ₀ −E _T .

Preferably, after step three, patterning photoresist, forming a metal layer, and removing glue are sequentially performed on the front side of the light-transmitting substrate.

Preferably, the method of patterning the photoresist is to develop the front side of the transparent substrate.

Preferably, after developing the front side of the transparent substrate, the width of the formed photoresist lines gradually decreases from top to bottom.

Preferably, the method of forming the metal layer is sputtering or electroplating metal on the transparent substrate after patterning the photoresist, and the metal used is at least one of copper, gold, silver, titanium, molybdenum or cobalt .

Preferably, the deglue method is to immerse the light-transmitting substrate after the metal layer is formed in a stripping solution.

Preferably, the polarity of the mask plate in step 2 is opposite to that of the photoresist.

Preferably, the projection exposure mode is selected for the front exposure of the transparent substrate in step 2, and the full exposure mode is selected for the back exposure of the transparent substrate in step 3.

Preferably, the transparent substrate is a glass substrate.

Compared with the prior art, the beneficial effects of the present invention are: the present invention provides a patterning process method, which includes the following steps in sequence:

Step 1: Coating photoresist on the light-transmitting substrate;

Step 2: exposing the front side of the light-transmitting substrate through a mask;

Step 3: exposing the backside of the light-transmitting substrate, using a luminous flux less than the minimum luminous flux required to cause the photoresist to react;

Step 4: Patterning photoresist, forming a metal layer, and removing glue on the front side of the light-transmitting substrate in sequence.

In the present invention, the photoresist is directly coated on the light-transmitting substrate, and the photoresist is directly coated on the light-transmitting substrate. After exposing the front side of the light-transmitting substrate, the minimum luminous flux received by the light-seeing area is defined as E _T , and then expose the backside of the light-transmitting substrate, define the minimum luminous flux required to cause the photoresist to react as E ₀ , then the exposure dose E _B used for backside exposure satisfies E ₀ >E _B >E ₀ -E _T , so that the luminous flux received by the bottom of the light-seeing area is E _B +E _T , then E _B +E _T >E ₀ , so the photoresist at the bottom of the light-seeing area can undergo photoacid reaction, while the light-shielding area receives The luminous flux is only E _B , since E ₀ >E _B , the photoresist in the light-shielding area still cannot undergo photoacid reaction, which solves the problem that the photoresist at the bottom of the light-shielding area cannot receive enough luminous flux in the traditional process. The photoacid reaction leads to the problem of photoresist residue, which improves the photolithography resolution.

The present invention forms a metal layer on the substrate after exposing and developing the photoresist, then the place that is not covered by the photoresist is covered with the metal layer to form a metal circuit, and the place covered by the photoresist is covered by the metal layer. Above the photoresist, below the photoresist is the light-transmitting substrate, then as the photoresist is removed, the metal originally covered on the photoresist is also removed, exposing the light-transmitting substrate, forming the required circuit , so that the metal circuit layer can be formed without etching the metal layer, thus avoiding the influence of etching on the metal circuit in the traditional process.

Description of drawings

Fig. 1 is the schematic diagram of exposure photoresist in the prior art;

Figure 2 is a schematic diagram of the photoresist in the prior art after development

Fig. 3 is the graphical process flow chart provided by the present invention;

Figure 4 is a schematic diagram of exposure of photoresist from the front side of the light-transmitting substrate provided by the present invention;

FIG. 5 is a schematic diagram of exposing photoresist from the backside of a light-transmitting substrate provided by the present invention;

FIG. 6 is a schematic diagram after forming a metal layer provided by the present invention.

Illustration of prior art: 01-light-transmitting substrate, 02-photoresist, 03-metal, 04-mask;

The diagram of the present invention: 1-light-transmitting substrate, 2-photoresist, 3-metal, 4-mask.

Detailed ways

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

Embodiment one

In order to achieve the above purpose, please refer to Figure 3, the present invention provides a graphic process method, which includes the following steps in turn:

Step 1: Coating photoresist 2 on the light-transmitting substrate 1. The photoresist 2 coated in this embodiment is a positive resist, that is, photoacid reaction will occur when it encounters ultraviolet light to decompose into soluble Substances in the developer solution;

Step 2: Please refer to FIG. 4, expose the front side of the light-transmitting substrate 1 through the mask plate 4, the direction of the arrow in the figure is the light direction, and the polarity of the mask plate 4 used is opposite to that of the photoresist 2, that is The positive photoresist 2 uses the negative mask 4, that is, the photoresist 2 is removed where the metal circuit needs to be made, and the positive photoresist here needs to be irradiated by ultraviolet light, which is the visible area. This place on the stencil 4 should be a transparent color; keep the photoresist 2 where no metal circuit needs to be made, then the positive photoresist here should not be irradiated by ultraviolet light, and it should be black here on the mask 4.

Step 3: After step 2, the front side of the light-transmitting substrate 1 is exposed, and the exposure dose used is the same as that of the traditional process. Therefore, due to the blocking of the top photoresist 2, the luminous flux received by the bottom photoresist 2 must be difficult to use. It undergoes photoacid reaction, and the minimum luminous flux received by the entire visible area is defined as E _T . Generally, the luminous flux received by the visible area decreases with the increase of the depth of the photoresist 2, so the photoresist at the bottom The luminous flux received by glue 2 is E _T .

Please refer to Figure 5, and then expose the backside of the transparent substrate 1, define the minimum luminous flux required to cause the photoacid reaction of the photoresist 2 to be E ₀ , then the luminous flux E _B used for the backside exposure of the transparent substrate 1 satisfies E ₀ >E _B >E ₀ -E _T , due to the exposure on the back of the light-transmitting substrate 1, the luminous fluxes received by the photoresist 2 at the bottom of the light-seeing area and the light-shielding area are both E _B , but because the light-seeing area At least luminous flux E _T has been received when exposing the front side of the light-transmitting substrate 1 , then after exposing the back side of the light-transmitting substrate 1 , the luminous flux received by the visible region is at least E _B + _ET , and by E _B >E ₀ -E _T shows that E _B +E _T >E ₀ , so the minimum luminous flux received by the visible area is greater than the minimum luminous flux E ₀ required for the photoacid reaction of photoresist 2, then even the bottom The photoresist 2 can also undergo a photoacid reaction and decompose into substances that can be dissolved by subsequent developing solutions.

Step 4: After step 3 is completed, the front side of the light-transmitting substrate 1 is sequentially developed, and the photoresist 2 at the bottom of the visible area can be fully dissolved and removed, and the remaining photoresist between the lines in the formed pattern is greatly reduced. This solves the problem of photoresist residue due to insufficient luminous flux received by the photoresist at the bottom of the visible area in the traditional process, and improves the photolithography resolution.

Preferably, the projection exposure mode is selected for the front exposure of the transparent substrate 1 in step 2, and the full exposure mode is selected for the rear exposure of the transparent substrate 1 in step 3. In the projection exposure mode, since the objective lens is used, the attenuation of the ultraviolet light when passing through the photoresist 2 is relatively small; in the full exposure mode, the objective lens is not used, and the attenuation of the ultraviolet light is relatively small when passing through the photoresist 2. Large, resulting in the attenuated minimum luminous flux E _T received by the bottom photoresist 2 during the front exposure is greater than the attenuated minimum luminous flux E _H received by the top photoresist 2 during the back exposure, defining the front exposure The luminous flux received by the top is E _S , and the luminous flux received by the bottom is E _W during the back exposure, then the exposure dose during the front exposure and back exposure should be adjusted so that the sum of the luminous flux received twice by the top is less than that received by the bottom twice The sum of the luminous flux, that is, E _S +E _H < _ET +E _W , when the received luminous flux increases, the area irradiated by the ultraviolet light increases, so that after developing the front side of the light-transmitting substrate 1, the formed The width of the photoresist 2 lines gradually decreases from top to bottom, and the cross-section of the photoresist 2 lines forms an inverted trapezoid, so that when the metal 3 is subsequently sputtered, the hypotenuse (ie, the side wall) of the inverted trapezoid is opposite to the positive trapezoid. More difficult to deposit metal 3.

Step 5: After step 4 is completed, a layer of patterned photoresist 2 remains on the light-transmitting substrate 1. At this time, the part not covered with photoresist 2 should be the place where metal lines need to be formed in the process, so A metal layer is formed on the light-transmitting substrate 1. Preferably, the metal layer is formed by sputtering. Please refer to FIG. Where metal lines need to be formed on the photoresist 2 , since the photoresist 2 is not covered, the sputtered metal 3 is directly formed on the light-transmitting substrate 1 . However, since the cross-section of the photoresist 2 lines is an inverted trapezoid, it is difficult for the sputtered metal 3 to accumulate on the sidewalls of the photoresist 2 lines.

After the metal layer is formed, the light-transmitting substrate 1 is immersed in the stripping solution of the photoresist 2. Since there is no sputtered metal 3 on the side of the photoresist 2 lines, the side walls of the photoresist 2 lines will also Complete contact with the stripping solution, so that the two fully react, so that the photoresist 2 covered with metal is completely separated from the light-transmitting substrate 1 under the action of the stripping solution, and the remaining light-transmitting substrate 1, directly The metal 3 formed on the light-transmitting substrate 1 is not removed, and the required metal circuit is formed.

Preferably, the metal used for metal sputtering is at least one of copper, gold, silver, titanium, molybdenum or cobalt.

Preferably, the transparent substrate 1 is a glass substrate.

Embodiment two

The difference between this embodiment and the first embodiment is that the photoresist 2 used is negative, and the mask 4 used is a positive mask.

It is obvious that those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and equivalent technologies thereof, the present invention also intends to include these modifications and variations.

Claims (6)

1. A graphical process method is characterized by sequentially comprising the following steps:

the method comprises the following steps: coating photoresist on a light-transmitting substrate;

step two: exposing the front side of the light-transmitting substrate through a mask plate;

step three: exposing the back surface of the light-transmitting substrate, wherein the minimum luminous flux received by the visible light area in the step two is defined as E_TDefining the minimum light flux required to react said photoresist as E₀Then the luminous flux E used for back exposure of the light-transmitting substrate_BSatisfies E₀> E_B>E₀-E_T；

Step four: patterning photoresist, forming a metal layer and removing the photoresist on the front surface of the light-transmitting substrate in sequence;

wherein, in the second step, the maximum luminous flux received by the photoresist during the front-side exposure is defined as E_S(ii) a In the third step, when the back surface of the light-transmitting substrate is exposed, the minimum luminous flux received by the photoresist is defined as E_HThe maximum luminous flux received by the photoresist is E_W，E_S+E_H<E_T+E_W；

The method for patterning the photoresist comprises the steps of developing the front side of the light-transmitting substrate;

and after the front surface of the light-transmitting substrate is developed, the width of the formed photoresist lines is gradually reduced from top to bottom.

2. The patterning process of claim 1, wherein the metal layer is formed by sputtering or plating a metal on the transparent substrate after the photoresist is patterned, and the metal is at least one of copper, gold, silver, titanium, molybdenum, or cobalt.

3. The patterning process of claim 1, wherein the photoresist is removed by immersing the transparent substrate after the metal layer is formed in a stripping solution.

4. The patterning process of claim 1, wherein the polarity of the reticle in step two is opposite to the polarity of the photoresist.

5. The patterning process of claim 1, wherein in step two, a projection exposure mode is used for front exposure of said transparent substrate, and in step three, a full-mask exposure mode is used for back exposure of said transparent substrate.

6. The patterning process of claim 1, wherein said light transmissive substrate is a glass substrate.