TW202232251A - Photoresist stripping method - Google Patents

Abstract

Provided is a photoresist stripping method. Using a wafer with a photoresist, the method comprises: first placing the wafer in an etching chamber; arranging within the etching chamber an gas homogenizing disc provided with a plurality of through holes; placing the wafer between the gas homogenizing disc and a microwave source; then introducing successively oxygen and water into the etching chamber from above the wafer to perform a softening process on the surface part of the photoresist; discharging the oxygen and water introduced; introducing 0.2 to 0.5g of water into the etching chamber from above the wafer and starting the microwave source at the same time, wherein the microwave source ionizes the water-vapor into an ion state, and the water-vapor in the ion state descends to the wafer via the gas homogenizing disc to absorb the chloride ions attached to the wafer; and finally, performing a dry photoresist removal according to the preset dry photoresist removal parameters, to strip off the surface part of the photoresist as well as the photoresist.

Description

Photoresist stripping method

The invention belongs to the technical field of the semiconductor industry, and particularly relates to a method for stripping photoresist.

The traditional mainstream degumming method adopts wet degumming, which has low cost and high efficiency. However, with the continuous iteration and updating of technologies, more and more IC manufacturers have begun to use dry degumming. The dry degumming process is different from the traditional wet degumming process. The degumming process does not require soaking in chemical solvents or drying. The degumming process is easier to control, avoiding excessive counting of substrates and improving product yield. Dry French degumming is also known as plasma degumming. Its principle is similar to ion cleaning. The photoresist is mainly removed by the reaction between oxygen nuclei and photoresist in a plasma environment. Since the basic component of photoresist is hydrocarbons Organic matter, under the action of radio frequency or microwave, oxygen is ionized into oxygen atoms and chemically reacts with the photoresist to generate carbon monoxide, carbon dioxide and water, etc., and then is evacuated by a pump to complete the removal of the photoresist.

In the process of dry degumming, the uniformity of degumming is the main factor to judge the quality of degumming. However, in the traditional dry degumming process, the uniformity of the photoresist degumming is too poor, which affects the production efficiency, thereby affecting the yield of the entire product.

The purpose of the present invention is to provide a method for stripping photoresist, which improves the uniformity of degumming of photoresist by setting the parameters in the uniform air plate, the softening process and the dry degumming process. For achieving the above object, the present invention adopts the following technical solutions:

A method for stripping photoresist, using a wafer with photoresist, comprising the following steps:

Step 01: placing the wafer in an etching chamber; setting a gas-sparing plate with a plurality of through holes in the etching chamber; placing the wafer between the gas-distributing plate and the microwave source;

Step 02: From the top of the wafer, oxygen and water are successively introduced into the etching chamber to soften the surface portion of the photoresist;

Step 03: discharge both the oxygen and water introduced in step 02;

Step 04: Pour 0.2-0.5 g of water into the etching chamber from above the wafer and activate the microwave source at the same time, the water forms moisture during the descending process, and the microwave source ionizes the moisture into an ionic state, and the water vapor in the ionic state descends to the wafer through a uniform air plate to absorb the chloride ions attached to the wafer;

Step 05: According to the preset dry degumming parameters, dry degumming is performed to peel off the surface layer of the photoresist and the photoresist; wherein, the preset dry degumming parameters include the flow rate of oxygen and The flow rate of nitrogen; the oxygen and nitrogen are both introduced into the etching chamber from above the wafer;

At the same time, 0.2-0.5 g of water is continuously poured into the etching chamber from above the wafer to absorb the chloride ions attached to the wafer.

Preferably, in step 04, the radio frequency power of the microwave source is 1000-1400W; the reaction pressure of the etching cavity is 2000-8000mtorr.

Preferably, in step 05, the preset dry degumming parameters further include radio frequency power and reaction pressure of the etching cavity; the radio frequency power of the microwave source is 1000-1400W; the reaction pressure of the etching cavity is 2000-8000mtorr .

Preferably, in step 05, the oxygen flow is 2000-4000 sccm, and the nitrogen flow is 200-800 sccm.

Preferably, in step 02, the total flow of oxygen introduced is 3500sccm, and the introduction time is 30s; the total amount of water introduced is 0.6g, and the introduction time is 30s.

Preferably, in step 01, the air sparger is made of quartz material.

Preferably, in step 01, the air distribution plate includes N circles of through-hole units, where N≧1; the through-hole unit includes a plurality of through-holes distributed along the circumference; the through-hole units have different radii .

Preferably, after step 05, return to step 04.

Preferably, step 01 specifically includes:

Step S1: sending the wafer in the wafer loading cavity directly above the hot stage in the etching cavity through a robotic arm device;

Step S2: the ceramic ejector mechanism located under the hot stage is lifted up and passes through the hollow area of the hot stage and the robotic arm device in turn; to lift the wafer on the hollow area; the distance between the wafer and the hot stage is 9mm .

Compared with the prior art, the advantages of the present invention are:

(1) First, in the softening process, oxygen and water are introduced to physically soften the photoresist and the surface layer of the photoresist, so that the photoresist and the surface layer of the photoresist contain water; The softened oxygen and water are discharged from the etching chamber; then the chloride ions on the wafer are dissolved by the water in the ionic state to remove the chloride ions; finally, the surface layer of the photoresist and the photoresist are removed by setting the parameters of dry removal. stripped. Therefore, through the above-mentioned steps, the uniformity of degumming can be improved.

(2) During the softening process and the dry degumming process, oxygen, nitrogen and water are all introduced into the etching chamber from above the wafer, and the oxygen, nitrogen and water are ionized into an ion state by a microwave source. The function of the uniform air plate is to sprinkle the wafer evenly to react with the photoresist and the surface layer of the photoresist, so that the photoresist is finally removed, and the removal is uniform.

The present invention will be described in more detail below with reference to the schematic diagrams, wherein preferred embodiments of the present invention are shown, and it should be understood that those skilled in the art can modify the present invention described herein and still achieve the advantageous effects of the present invention. Therefore, the following description should be construed as widely known to those skilled in the art and not as a limitation of the present invention.

As shown in FIG. 1 , a photoresist stripping method, using a wafer with photoresist, includes the following steps 01 to 06 .

Step 01: placing the wafer in an etching chamber; setting a gas-sparing plate with a plurality of through holes in the etching chamber; placing the wafer between the gas-distributing plate and the microwave source.

The air distribution plate is made of quartz material; the air distribution plate includes N circles of through-hole units, where N is a positive integer and N≧1; the through-hole unit includes several through-holes distributed along the circumference; the through-hole units have different radii.

The function of the uniform air plate is to uniformize the oxygen and water introduced into the etching cavity. In step 02, the function of the uniform air plate is to make oxygen and water evenly contact with the photoresist and the surface layer of the photoresist, so as to improve the softening effect; in step 04, the function of the uniform air plate is to uniformize the The water vapor formed by the ionization of the microwave source makes the water vapor evenly contact with the photoresist and the surface layer of the photoresist, so as to evenly absorb the chlorine ions attached to the wafer; The oxygen ions, nitrogen ions and water vapor ions formed by the ionization of the microwave source make the oxygen ions, nitrogen ions, and water vapor ions evenly contact with the photoresist and the surface layer of the photoresist, and improve the uniformity of debonding.

The specific operation of placing the wafer in the etching cavity is as follows: first, the wafer in the wafer loading cavity is sent to the directly above the hot stage in the etching cavity through a robotic arm device; then, the wafer is placed under the hot stage The ceramic ejector pin mechanism of the device rises and passes through the hollow area of the hot stage and the robotic arm device in turn; to lift the wafer on the hollow area; the distance between the wafer and the hot stage is 9mm. Those skilled in the art can know that the operation method of how the wafer is placed in the etching chamber belongs to the prior art. In addition, since the temperature of the hot stage is relatively high, in order to prevent the photoresist on the wafer from sticking, the wafer and the hot stage are not in contact, which reduces the difficulty of removing the glue.

Step 02: Pour oxygen and water into the etching chamber successively from above the wafer to soften the surface layer of the photoresist.

Specifically, both oxygen and water are introduced through the wafer. With the increase of the amount of introduction, the oxygen gradually covers the photoresist on the wafer and the surface layer of the photoresist completely or the water vapor gradually covers the wafer. The photoresist and the surface layer of the photoresist are completely submerged. The function of oxygen is to soften the photoresist and the surface layer of the photoresist first, so as to avoid the subsequent degumming time process causing the photoresist and the surface layer of the photoresist to dry out; the function of water is to prevent the photoresist and photoresist from drying. The surface layer part is physically softened, so that the photoresist and the surface layer part of the photoresist both contain water, so as to avoid drying the photoresist and the surface layer part of the photoresist at a high temperature of 250 degrees on the hot stage.

Among them, the total flow of oxygen introduced is 3500sccm, and the introduction time is 30s; the total amount of water introduced is 0.6g, and the introduction time is 30s.

Step 03: Completely discharge the oxygen and water introduced in Step 02.

Specifically, an exhaust pipe communicating with the etching cavity and a drain pipe communicating with the etching cavity may be provided at the bottom of the etching cavity. When the softening time reaches the preset value, open the valves on the exhaust pipe and the drain pipe to discharge oxygen and water out of the etching chamber respectively. The function of step 3 is to avoid residual oxygen or water. If oxygen or water remains, the ratio of process gas and water in steps 4 and 5 will be unbalanced, affecting the uniformity of degumming.

Step 04: Pour 0.2~0.5g of water into the etching chamber from the top of the wafer and start the microwave source at the same time. The water forms water vapor during the descending process, and the microwave source ionizes the water vapor into an ionic state, and the water in the ionic state The gas is lowered to the wafer through the uniform gas plate to absorb the chlorine ions attached to the wafer, and this step can also play the role of degumming. Among them, in the previous process of the degumming process, the dry etching of aluminum requires chlorine gas. Therefore, the residual chloride ions appear in the degumming process, and the chloride ions have a corrosive effect, so they need to be removed in advance.

Among them, the radio frequency power of the microwave source is 1000~1400W; the reaction pressure of the etching cavity is 2000~8000mtorr.

Step 05: according to the preset dry method degumming parameters, dry method degumming is performed to peel off the surface layer of the photoresist and the photoresist; wherein, the preset dry method degumming parameters include the flow rate of oxygen and the flow rate of nitrogen; Both oxygen and nitrogen are passed from the top of the wafer into the etching chamber; oxygen and nitrogen are used as reactive gases, which react with the photoresist and the surface layer of the photoresist after ionization, so as to remove the photoresist and the photoresist. The surface layer is partially removed.

At the same time of dry degumming, 0.2~0.5g of water is continuously poured into the etching chamber from above the wafer to further absorb the chloride ions attached to the wafer.

Among them, the oxygen flow rate is 2000~4000sccm, and the nitrogen flow rate is 200~800sccm.

Among them, the preset dry method degumming parameters also include the radio frequency power and the reaction pressure of the etching cavity; the radio frequency power of the microwave source is 1000-1400W; the reaction pressure of the etching cavity is 2000-8000mtorr.

Step 06: After Step 05, return to Step 04. Steps 04 and 05 are repeated several times to completely remove the photoresist and the surface layer of the photoresist.

Example 1

Parameter settings in step 04: the size of the air distribution plate hole is 6-10mm, the number of layers is 5 layers from the inside to the outside, and the 2mm increments or the same from the inside to the outside; the radio frequency power is 1000-1400W, and the pressure of the etching chamber is 2000 -8000mtorr, water flow is 0.2-0.5g. The experimental results show that the degumming uniformity is 10.5%, and the degumming rate is 49190A/min.

The parameter settings in step 05: the size of the air distribution plate hole is 6-10mm, the number of layers is 5 layers from the inside to the outside, and the 2mm increments or the same from the inside to the outside; the upper RF power is 1000-1400W, and the etching chamber pressure is 2000-8000mtorr, water flow 0.2-0.5g, oxygen flow 2000-4000sccm, nitrogen flow 200-800sccm. The experimental results show that the degumming uniformity is 14.8%, and the degumming rate is 31470A/min.

Example 2

The parameter settings in step 04: the size of the air distribution plate hole is 6-10mm, the number of layers is 4 layers from the inside to the outside, and the 2mm increments or the same from the inside to the outside; the upper RF power is 1000-1400W, and the etching chamber pressure is 2000-8000mtorr, water flow is 0.2-0.5g. The experimental results show that the degumming uniformity is 14.2%, and the degumming rate is 55230A/min.

The parameter settings in step 05: the size of the air distribution plate hole is 6-10mm, the number of layers is 4 layers from the inside to the outside, and the 2mm increment or the same from the inside to the outside; the RF power is 1000-1400W, and the cavity pressure is 2000-8000mtorr , the water flow is 0.2-0.5g, the oxygen flow is 2000-4000sccm, and the nitrogen flow is 200-800sccm. The experimental results show that the degumming uniformity is 14.4%, and the degumming rate is 30600A/min.

Example 3

Case three:

The parameter settings in step 04: the size of the air distribution plate hole is 6-10mm, the number of layers is 4 layers from the inside to the outside, and the 2mm increments or the same from the inside to the outside; the RF power is 800-1000W, and the cavity pressure is 2000-8000mtorr , the water flow is 0.2-0.5g. The experimental results show that the degumming uniformity is 12.2%, and the degumming rate is 29190A/min.

The parameter settings in step 05: the size of the air distribution plate hole is 6-10mm, the number of layers is 4 layers from the inside to the outside, and the 2mm increments or the same from the inside to the outside; the RF power is 800-1000W, and the cavity pressure is 2000-8000mtorr , the water flow is 0.2-0.5g, the oxygen flow is 2000-4000sccm, and the nitrogen flow is 200-800sccm. The experimental results show that the degumming uniformity is 11%, and the degumming rate is 41190A/min.

It can be seen from the uniformity and degumming rate of dry method degumming in Example 1 and Example 2 that by adjusting the structure of the uniform air plate (number of turns and aperture size), the uniformity can be controlled within 15% and the etching rate can be controlled within 15%. Above 25000A/min.

It can be seen from the uniformity and degumming rate of dry-process degumming in Examples 2 and 3 that the uniformity can be stabilized by adjusting the process parameters on the basis of the optimized structure (number of turns and aperture size) of the air-distribution plate. It is controlled within 15% and the etching rate is above 25000A/min.

表2  對應表1的10組實驗的輸出參數（均勻性＜15）

In addition, as shown in Tables 1-2, the present invention also verifies the effect of the size of the through hole on the etching rate of the dry method and the uniformity of the debonding. In Table 2, the degumming uniformity calculation has been calculated by the industry range method. In this example, "uniformity" refers to "degumming uniformity". Table 1 Dimensional data of 10 groups of through holes

Table 2 corresponds to the output parameters of the 10 groups of experiments in Table 1 (uniformity < 15)

The above are only preferred embodiments of the present invention, and do not have any limiting effect on the present invention. Any person skilled in the art, within the scope of not departing from the technical solution of the present invention, makes any form of equivalent replacement or modification to the technical solution and technical content disclosed in the present invention, all belong to the technical solution of the present invention. content still falls within the protection scope of the present invention.

01~05: Steps

FIG. 1 is a schematic flowchart of a photoresist stripping method according to an embodiment of the present invention.

01~05: Steps

Claims (9)

A method for stripping photoresist, using a wafer with photoresist, comprising the following steps: Step 01: Place the wafer in an etching chamber; set a gas-sparing disk with a plurality of through holes in the etching chamber; place the wafer between the gas-sparing disk and the microwave source ; Step 02: From the top of the wafer, oxygen and water are successively introduced into the etching chamber to soften the surface portion of the photoresist; Step 03: discharge the oxygen and water introduced in the step 02; Step 04: Pour 0.2-0.5 g of water into the etching chamber from above the wafer and activate the microwave source at the same time, the water forms moisture during the descending process, and the microwave source ionizes the moisture into an ionic state, and the water vapor in the ionic state descends to the wafer through a gas-distributing plate to absorb the chloride ions attached to the wafer; and Step 05: According to the preset dry degumming parameters, dry degumming is performed to peel off the surface layer of the photoresist and the photoresist; wherein, the preset dry degumming parameters include the flow rate of oxygen and The flow rate of nitrogen; both the oxygen and nitrogen are passed into the etching chamber from above the wafer, At the same time, 0.2-0.5 g of water is continuously poured into the etching chamber from above the wafer to absorb the chloride ions attached to the wafer. According to the photoresist stripping method according to claim 1, in step 04, the radio frequency power of the microwave source is 1000-1400W; the reaction pressure of the etching cavity is 2000-8000mtorr. According to the photoresist stripping method according to claim 1, in step 05, the preset dry method stripping parameters further include radio frequency power and the reaction pressure of the etching cavity; the radio frequency power of the microwave source is 1000-1400W; the reaction pressure of the etching chamber is 2000-8000mtorr. According to the photoresist stripping method according to claim 1, in the step 05, the oxygen flow rate is 2000-4000 sccm, and the nitrogen flow rate is 200-800 sccm. According to the photoresist stripping method according to claim 1, in the step 02, the total flow of oxygen to be introduced is 3500sccm, and the introduction time is 30s; the total amount of water to be introduced is 0.6g, and the introduction time is 30s . According to the photoresist stripping method as claimed in claim 1, in the step 01, the uniform gas plate is made of quartz material. According to the photoresist stripping method according to claim 1, in the step 01, the air distribution plate includes N circles of through-hole units, wherein N≧1; the through-hole unit includes a plurality of through-hole units distributed along the circumference. the through hole; the radius of the through hole unit is different. The photoresist stripping method according to claim 1, after the step 05, returns to the step 04. The photoresist stripping method according to claim 1, in the step 01, the method specifically includes: Step S1: sending the wafer in the wafer loading chamber directly above the hot stage in the etching chamber through a robotic arm device; and Step S2: the ceramic ejector mechanism located under the hot stage is lifted up and passes through the hollow region of the hot stage and the robotic arm device in turn; to lift the wafer on the hollow region; the wafer and the The distance between the hot stages is 9mm.

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