KR101049939B1 - Substrate manufacturing method - Google Patents

Abstract

In the substrate manufacturing method, first, the substrate on which the photoresist is formed is heated and then subjected to primary plasma ashing. Subsequently, after the temperature of the substrate is lowered at atmospheric pressure, the substrate is subjected to secondary plasma ashing. As such, during the plasma ashing process, the temperature of the substrate is temporarily lowered at atmospheric pressure, thereby reducing chemical bond change of the photoresist, reducing popping and residue generation, and improving product yield.

Description

Substrate manufacturing method {METHOD FOR PRODUCTING SUBSTRATE}

The present invention relates to an apparatus for manufacturing a semiconductor substrate, and more particularly to a substrate manufacturing method for processing a semiconductor substrate.

In general, plasma refers to an ionized gas state composed of ions, electrons, radicals, and the like, and is generated by a very high temperature, a strong electric field, or high frequency electromagnetic fields (RF Electromagnetic Fields).

Particularly, plasma generation by glow discharge is performed by free electrons excited by direct current or high frequency electromagnetic field, and the excited free electrons collide with gas molecules to generate active species such as ions, radicals and electrons. ). These active species physically or chemically act on the surface of the material to change the surface properties. As such, treating the surface of a substance with active species is referred to as plasma treatment.

Such plasma processing is used in processes for manufacturing semiconductor devices, such as thin film deposition, cleaning, ashing or etching processes.

In general, the plasma ashing process removes the photoresist by reacting the plasma with the photoresist while placing the wafer on a chuck heated to about 200 ° C to 300 ° C.

This plasma ashing process is mainly through plasma generation using oxygen gas. However, when the photoresist is removed after the high dose implant treatment, the surface of the photoresist hardens during the high dose implant treatment. As a result, popping is caused, and residue is left by popping. These residues are not easily removed by chemical treatment, resulting in wafer failure.

To prevent this, a gas containing fluorine, such as carbon tetrafluoride (CF4) gas, is added during the plasma ashing process to remove residues formed by popping. In other words, the photoresist changes in material due to temperature increase, thereby increasing the amorphous carbon constituting the photoresist. Accordingly, the residue due to popping increases the degree of hardening by increasing the bond between carbon and carbon, thus increasing the energy required to remove it. Since these residues are difficult to remove using oxygen gas, fluorine-based gas is added during the plasma ashing process. Since the fluorine-based gas bonds with the carbon constituting the residue and breaks the bond between carbon and carbon, the residue can be easily removed. However, such fluorine-based gas causes loss of the oxide film formed on the wafer.

In addition, since the plasma ashing process using only oxygen gas requires a process temperature of 300 ° C. or higher, as described above, it causes popping and residual residues, and causes changes in wafer characteristics due to high temperatures, and to remove residues. A separate chemical treatment is involved.

An object of the present invention is to provide a method for manufacturing a substrate that can improve the process efficiency.

A substrate manufacturing method according to one feature for realizing the object of the present invention described above is as follows. First, the substrate on which the photoresist is formed is heated. The substrate is then subjected to primary plasma ashing and the temperature of the substrate is lowered at atmospheric pressure. Again, the substrate is subjected to secondary plasma ashing.

Here, the primary plasma ashing treatment and the secondary plasma ashing treatment are performed under vacuum pressure, and the primary plasma ashing treatment and the secondary plasma ashing treatment are performed using oxygen gas.

On the other hand, after the secondary plasma ashing treatment, the substrate is cleaned using pure water without chemical treatment.

In addition, the substrate manufacturing method according to one feature for realizing the above object of the present invention is as follows. First, the substrate is heated in a state in which the substrate is seated on a support member installed inside the chamber. The substrate is subjected to primary plasma ashing while maintaining the inside of the chamber at a first pressure. The temperature of the substrate is lowered while maintaining the inside of the chamber at a second pressure. The substrate is subjected to secondary plasma ashing while maintaining the inside of the chamber at a third pressure.

Here, the second pressure is higher than the first and third pressures.

Specifically, the second pressure is atmospheric pressure, and the first and third pressures are vacuum pressures.

According to the present invention described above, by lowering the temperature of the substrate for a while at atmospheric pressure during the plasma ashing process, it prevents the chemical bond change of the photoresist, reduces the popping and residue generation, improve the ashing efficiency, the product yield Can improve.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a substrate manufacturing apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the substrate manufacturing apparatus 400 of the present invention includes a processing unit 100, a plasma generating unit 200, and the first and second exhaust pipes 310 and 320.

The processing unit 100 is subjected to an ashing process of the wafer, and the plasma raw net 200 generates plasma required for the ashing process and provides the processing unit 100 to the processing unit 100. The first and second exhaust pipes 310 and 320 discharge the gas and the reaction by-products inside the processing unit 100 to the outside and adjust the internal pressure of the processing unit 100.

In detail, the processing unit 100 includes a chamber 110, a chuck 120, a baffle 130, and a cover 140.

The chamber 110 provides a process space PS in which a process of processing the substrate is performed, and first and second exhausts communicating with the first and second exhaust pipes 310 and 320 on the bottom surface 111, respectively. Holes 111a and 111b are formed. During the processing of the substrate, the chamber 110 is grounded.

The chuck 120 is installed in the process space PS and supports the wafer during the ashing process. Specifically, the chuck 120 includes a support plate 121 on which the wafer is seated and a support shaft 123 coupled to a lower portion of the support plate 121. During the ashing process, the support plate 121 heats the wafer seated on the upper surface to a predetermined temperature, and the support shaft 123 rotates about the central axis to rotate the support plate 121.

The baffle 130 and the cover 140 are provided on the chuck 120. The baffle 130 is coupled to an upper end of the chamber 110 and faces the support plate 121. The baffle 130 is grounded to filter the plasma generated from the plasma generation unit 200, and mainly passes through the radicals of the plasma to provide the process space PS.

The cover 140 is provided on the chamber 110 and the baffle 130, and is coupled to the chamber 110 to seal the process space PS. In addition, the cover 140 is coupled to the plasma generating unit 200, the inlet 141 is introduced to the plasma from the plasma generating unit 200 is formed. An induction space GS through which the plasma from the plasma generation unit 200 flows through the inlet 141 is formed in the cover 140. Plasma in the induction space GS is provided to the process space PS via the baffle 130. In one example of the invention, the induction space GS is formed in an inverted funnel shape.

The plasma generating unit 200 is installed above the cover 140. The plasma generating unit 200 includes a magnetron 210, a waveguide 220, first and second gas supply pipes 231 and 233, a plasma source unit 240, and an inlet pipe 250.

In detail, the magnetron 210 generates microwaves for plasma generation, and the waveguide 220 guides the microwaves generated by the magnetron 210 to the plasma source unit 240. The first gas supply pipe 231 is connected to the plasma source unit 240, and supplies a processing gas for plasma ashing to the plasma source unit 240.

In the plasma source unit 240, the plasma is generated by the processing gas from the first gas supply pipe 231 and the microwaves from the magnetron 210.

The plasma source unit 240 is connected to the input end of the inlet pipe 250, the output end of the inlet pipe 250 is coupled to the upper surface of the cover 140 is in communication with the inlet 141. The plasma generated by the plasma source unit 240 is provided to the induction space GS through the inlet pipe 250, and is provided to the process space PS through the baffle 130.

In addition, the inlet pipe 250 is connected to the second gas supply pipe 233. The output end of the second gas supply pipe 233 is coupled to the side of the inlet pipe 250, and provides a control gas to the inlet pipe 250, the radical generation rate of the plasma generated in the plasma source unit 240 Adjust

The plasma generating unit 200 may further include a third gas supply pipe 235 which provides a cleaning gas for cleaning the inside of the chamber 110. The third gas supply pipe 235 is connected to the plasma source unit 240, and the cleaning gas removes particles attached to the inner wall of the chamber 110 and the baffle 130 during processing of the substrate.

Meanwhile, the first and second exhaust pipes 310 and 320 are installed below the chamber 110. The first and second exhaust pipes 310 and 320 are coupled to the bottom surface 111 of the chamber 110 to form first and second exhaust holes 111a and 111b formed in the bottom surface 111 of the chamber 110. ) And the gas introduced into the process space PS and the process by-products generated in the process are discharged to the outside. The first and second exhaust pipes 310 and 320 are connected to an external pressure regulator (not shown), and the pressure of the process space is adjusted through the first and second exhaust pipes 310 and 320.

In this embodiment, the substrate manufacturing apparatus 501 includes two exhaust pipes 310 and 320, but the number of the exhaust pipes 310 and 320 may increase or decrease according to the size of the chamber 110. have.

Hereinafter, a plasma ashing process using the substrate manufacturing apparatus 400 will be described in detail with reference to the accompanying drawings.

2 is a flowchart illustrating a method of manufacturing a wafer using the substrate manufacturing apparatus shown in FIG. 1, and FIG. 3 is a view illustrating a process in which plasma ashing is performed in the substrate manufacturing apparatus illustrated in FIG. 1.

2 and 3, first, the support plate 121 of the chuck 120 is heated, and then the wafer 10 on which the photoresist is formed is seated on the support plate 121 (step S110). In this case, the support plate 121 is heated to about 200 to 300 degrees Celsius, and the wafer 10 is an implant using a high dose implant (HDI) or plasma after the photoresist is formed. After the process, it is introduced into the chamber 10.

The wafer 10 is heated by the heated support plate 121 (step S120). At this time, the heating time of the wafer 10 is about 2 to 20 seconds.

Here, the step of mounting the wafer 10 to the support plate 121 (S110) and the step of heating the wafer 10 (S120) is performed in a state in which the internal pressure of the chamber 110 is maintained at atmospheric pressure. .

Subsequently, after making the inside of the chamber 110 in a vacuum state, the plasma 10 is subjected to primary plasma ashing using oxygen gas (step S130).

Specifically, oxygen gas is supplied to the plasma source unit 240 from the first gas supply pipe 231. Meanwhile, microwaves are generated from the magnetron 210, and the microwaves are guided to the plasma source unit 240 through the waveguide 220. Accordingly, a plasma containing oxygen is generated in the plasma source unit 240, and the generated plasma is provided to the wafer 10 via the induction pipe 250 and the baffle 130. As a result, the primary plasma ashing treatment of the wafer 10 is performed.

In the first plasma ashing process, the internal pressure of the chamber 110 is about 0.1 to about 1 Torr, and the power of about 1000 to about 3000 Watts is consumed, and the flow rate of the supplied oxygen gas is supplied. Is about 1000 to about 5000 sccm (Standard Cubic Centimeter per Minute), the time required is about 10 to about 30 seconds.

Subsequently, the internal pressure of the chamber 110 is set to atmospheric pressure, and then the temperature of the wafer 10 is lowered by waiting the wafer 10 in a state where the wafer 10 is separated from the support plate 121. (S140). Here, the waiting time of the wafer 10 is at least about 30 seconds.

When the wafer is separated from the support plate 121, the wafer 10 is spaced about 1 cm or more from the support plate 121 by a lift pin (not shown) installed on the support plate 121. Here, the lift pin separates the wafer 10 from the support plate 121 through a lifting operation in the state in which the lift pin is supported.

In addition, the wafer 10 may be withdrawn from the chamber 110 to separate the wafer 10 from the support plate 121. In this case, the wafer 10 may be cooled by using a separate cooling member, or the wafer 10 may be waited at room temperature.

The above-described methods of lowering the temperature of the wafer 10 are performed at atmospheric pressure.

Subsequently, the wafer 10 is seated on the support plate 121, and then the wafer 10 is subjected to secondary plasma ashing using oxygen gas (step S160). At this time, the internal pressure of the chamber 110 is about 0.1 to about 1 Torr, the power consumption is about 1000 to about 3000 watts, the flow rate of oxygen gas is about 1000 to about 5000 sccm, the time required is about 10 to about 30 Seconds.

Subsequently, the pressure and the power consumption of the chamber 110 are increased in step S160 to perform the third plasma ashing process on the wafer 10 (step S170). At this time, the internal pressure of the chamber 110 is about 0.5 to about 2.5 Torr, the power consumption is about 3000 to about 7000 watts, the flow rate of oxygen gas is about 1000 to about 5000 sccm.

In one example of the present invention, the primary plasma ashing treatment and the second plasma ashing treatment are performed under lower pressure and lower power consumption than the tertiary plasma ashing treatment in consideration of popping occurrence. On the other hand, the third plasma ashing treatment is performed under higher pressure and higher power consumption than the first plasma ashing treatment and the second plasma ashing treatment to improve ashing rate.

After removal of the photoresist through tertiary plasma ashing of the wafer 10, the wafer 10 is withdrawn from the chamber 110 (S180), and the wafer 10 is cleaned with pure water. It dries (step S190).

As mentioned above, although plasma ashing is performed using oxygen gas, this invention is not limited to this.

As described above, the plasma ashing process according to the present invention heats the wafer 10 at atmospheric pressure, decreases the temperature of the wafer 10 at atmospheric pressure after the first plasma ashing treatment, and applies the wafer 10 to the wafer 10. It prevents material change of the formed photoresist, that is, chemical bond change.

Specifically, the photoresist generates a change in chemical bonding at a high temperature in a vacuum state, and the chemical bond change of the photoresist according to temperature and pressure is shown in Table 1 below.

Chemical bond Before HDI Treatment After HDI treatment Heat in vacuum after HDI treatment Heat at atmospheric pressure after HDI treatment Carbon-oxygen 26 14 0 16 Carbon-hydrogen 74 50 13 52 Amorphous carbon 0 36 87 32

Referring to Table 1, before HDI treatment, the carbon-oxygen bond of the photoresist is about 26%, the carbon-hydrogen bond is about 74%, and the amorphous carbon is about 0%. The chemical bonds of the photoresist after HDI treatment show that carbon-oxygen bonds are reduced by 14% compared to HDI treatment, carbon-hydrogen bonds are reduced by 50% than HDI treatment, and amorphous carbon is about 36% HDI treated. Increase than before.

When the HDI treated photoresist is heated in a vacuum at about 259 degrees Celsius, carbon-oxygen bonds are reduced to about 0% than before heating, carbon-hydrogen bonds are reduced to about 13% than before heating, and amorphous carbon is about 87% Furnace is increased than before heating. That is, when the HDI-treated photoresist is heated in a vacuum state, a change in chemical bond occurs, and the amorphous carbon is rapidly increased.

Due to this, the photoresist has an increase in the bond group between carbon and carbon, thereby increasing the double bond and triple bond between carbon and carbon, and increasing popping. Generally, it takes about 81 Kcal / mole of energy to break down carbon-carbon bonds, while about 145 Kcal / mole and about 198 Kcal / mole of energy to break down carbon = carbon bonds and carbon-to-carbon bonds, respectively. This makes it difficult to remove residues.

On the other hand, when the HDI treated photoresist is heated to about 250 degrees Celsius at atmospheric pressure, the carbon-oxygen bond is about 16%, the carbon-hydrogen bond is about 52%, and the amorphous carbon is about 32%. As such, when the HDI treated photoresist is heated at atmospheric pressure, since the chemical bond is almost unchanged from before heating, it is possible to prevent an increase in amorphous carbon, to reduce popping, and to easily remove residues and photoresists.

Hereinafter, referring to FIG. 2, FIG. 3, and Table 1, the chemical bond change of the photoresist formed on the wafer 10 for each of steps S120 to S150 is as follows.

First, in step S120, since the wafer 10 is heated at atmospheric pressure, the photoresist of the wafer 10 hardly changes chemical bonds. That is, the chemical bonding of the photoresist appears almost similar to before heating, ie after HDI treatment.

In step S130, since the wafer 10 is subjected to primary plasma ashing under a high temperature vacuum, the photoresist of the wafer 10 is changed in chemical bonding. That is, the amorphous carbon of the photoresist of the wafer 10 is rapidly increased.

However, in steps S140 and S150, the wafer 10 is separated from the chuck 120 to reduce the temperature at atmospheric pressure. As a result, the amorphous carbon of the photoresist is reduced to a state before heating. That is, the chemical bond of the photoresist is changed to the state after the HDI treatment again.

As such, the plasma ashing process according to the present invention reduces the temperature of the wafer 10 after the primary plasma ashing treatment at atmospheric pressure to reduce the chemical bond change of the photoresist due to the temperature rise.

Accordingly, the substrate manufacturing apparatus 400 may prevent popping, easily remove residues and the photoresist, and improve plasma ashing efficiency. In addition, since the substrate manufacturing apparatus 400 does not need to use a fluorine-based gas to prevent popping and remove residues, it is possible to prevent oxide film loss of the wafer 10 and to improve product yield.

In addition, since the plasma ashing process according to the present invention minimizes the chemical bond change of the photoresist, the wafer 10 is cleaned using pure water without a separate chemical treatment during the cleaning process of the wafer 10 after the plasma ashing process. Can reduce the manufacturing cost.

Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

1 is a view showing a substrate manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method of manufacturing a wafer using the substrate manufacturing apparatus shown in FIG. 1.

3 is a diagram illustrating a process in which plasma ashing is performed in the substrate manufacturing apparatus shown in FIG. 1.

Description of the Related Art [0002]

100: processing unit 200: plasma generating unit

310, 320: exhaust pipe 400: substrate manufacturing apparatus

Claims (18)

delete Heating the substrate on which the photoresist is formed at atmospheric pressure; Primary plasma ashing of the substrate under vacuum; Lowering the temperature of the substrate at atmospheric pressure; And A second plasma ashing treatment of the substrate under vacuum; Heating the substrate, Heating a support member installed in the chamber; And Mounting and heating the substrate on the support member while maintaining the internal pressure of the chamber at atmospheric pressure; The heating time of the substrate is 2 to 20 seconds, The internal pressure of the chamber during the first plasma ashing process is 0.1 to 1 Torr, the power consumption is 1000 to 3000 watts (W), and the flow rate of the gas used for the primary plasma ashing process is 1000 to 5000 sccm (Standard Cubic Centimeter per Minute) and the duration is 10-30 seconds, In the secondary plasma ashing process, the internal pressure of the chamber is 0.1 to 1 Torr, the power consumption is 1000 to 3000 watts, the flow rate of the gas used for the secondary plasma ashing process is 1000 to 5000 sccm and the time required is 10 to 30 seconds. A substrate manufacturing method characterized by the above-mentioned. 3. The method of claim 2, wherein the lowering the temperature of the substrate separates the substrate from the support member for a predetermined time while maintaining the internal pressure of the chamber at atmospheric pressure. The method of claim 3, wherein the lowering of the temperature of the substrate comprises separating the substrate from the support member by at least one centimeter. The method of claim 4, wherein the substrate is spaced apart from the support member by a lift pin provided in the support member when the temperature of the substrate decreases. The method of claim 2, The cooling of the substrate may include disposing the substrate from the chamber and arranging the substrate outside the chamber for a predetermined time at atmospheric pressure. And a temperature outside the chamber is lower than an inside temperature of the chamber. The method of claim 2, wherein the cooling of the substrate comprises drawing the substrate out of the chamber and then cooling the substrate at atmospheric pressure using a cooling device. delete The method of manufacturing a substrate according to any one of claims 2 to 7, wherein the first plasma ashing treatment and the second plasma ashing treatment are performed using oxygen gas. delete The method of claim 2, wherein after the secondary plasma ashing step, Further comprising tertiary plasma ashing of the substrate; Wherein said tertiary plasma ashing process is performed under process conditions in which the internal pressure and power consumption of said chamber are higher than said primary and secondary plasma ashing process steps. 8. The method of claim 2, wherein prior to heating the substrate, the substrate is implanted using a high dose implant treatment or plasma. 9. 8. The process of claim 2, wherein after the secondary plasma treatment step, Cleaning the substrate using pure water without chemical treatment. Mounting the substrate on a support member installed inside the chamber and heating the substrate at atmospheric pressure; Subjecting the substrate to a first plasma ashing process after the chamber internal pressure is vacuumed; Lowering the temperature of the substrate after the internal pressure of the chamber is brought to atmospheric pressure; And And subjecting the substrate to secondary plasma ashing after vacuuming the chamber internal pressure. delete delete The method of claim 14, The heating of the substrate is performed for 2 to 20 seconds while the inside of the chamber is maintained at atmospheric pressure. In the primary plasma ashing process, the internal pressure of the chamber is 0.1 to 1 Torr, the power consumption is 1000 to 3000 watts (W), and the flow rate of the gas used for the primary plasma ashing process is 1000 to 5000 sccm ( Standard Cubic Centimeter per Minute) and the duration is 10-30 seconds, In the secondary plasma ashing process, the internal pressure of the chamber is 0.1 to 1 Torr, the power consumption is 1000 to 3000 watts, the flow rate of the gas used for the secondary plasma ashing process is 1000 to 5000 sccm and the time required is 10 to 30 seconds A substrate manufacturing method, characterized in that. The method of claim 14, After the second plasma ashing treatment step, And cleaning the substrate with pure water without chemical treatment.

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