JP5213741B2 - Substrate manufacturing method - Google Patents

Description

  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.

Generally, 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 a high frequency electromagnetic field (RF Electromagnetic Fields).
In particular, glow discharge plasma is generated by free electrons excited by a direct current or a high-frequency electromagnetic field. The excited free electrons collide with gas molecules and are the same active species as ions, radicals, electrons, and the like (Active Specials). Is generated. Such active species physically or chemically act on the surface of the substance to change the surface properties. Treating the surface of a substance with such active species is called plasma treatment.

  Such plasma treatment is used in a process for manufacturing a semiconductor element, for example, a thin film deposition, cleaning, ashing or etching process.

  In general, in the plasma ashing process, plasma is reacted with a photoresist in a state where a wafer is placed on a chuck heated to about 200 ° C. to 300 ° C. to remove the photoresist.

  Such a plasma ashing process is mainly performed through plasma generation using oxygen gas. However, when the photoresist is removed after being subjected to a high dose implant process, the surface of the photoresist is hardened in the process of the high dose implant process. Accordingly, popping is induced, and the residue remains from the popping. Such a residue cannot be easily removed even by chemical treatment, and causes a wafer defect.

  In order to prevent this, a gas containing fluorine such as carbon tetrafluoride (CF4) gas is added during the plasma ashing process, and the formed residue is removed by popping. That is, as the temperature of the photoresist increases, the material changes, and the amorphous carbon constituting the photoresist increases. Accordingly, the residue due to popping increases the bonding groups between carbon and carbon, and the degree of curing increases, so the energy required to remove it increases. Since such a residue is difficult to remove using oxygen gas, a fluorine-based gas is added during the plasma ashing process. Since the fluorine-based gas is bonded to carbon constituting the residue and cuts a bonding group between the carbons, the residue can be easily removed. However, such a fluorine-based gas induces a loss of an 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, popping and residue residue are induced, wafer property change due to high temperature is induced, and additional chemical treatment is involved for residue removal.

  The present invention has been made in view of the above problems, and an object thereof is to provide a substrate manufacturing method capable of improving process efficiency.

  In order to achieve the above object, a substrate manufacturing method according to one feature for realizing the object of the present invention is as follows.

  First, a substrate on which a photoresist is formed is heated. Subsequently, the substrate is subjected to primary plasma ashing, and the temperature of the substrate is lowered in an atmospheric pressure state. Again, the substrate is subjected to secondary plasma ashing.

  Here, the primary plasma ashing process and the secondary plasma ashing process are performed in a vacuum state and using oxygen gas.

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

  In order to achieve the above object, a substrate manufacturing method according to one feature for realizing the object of the present invention is as follows. First, a substrate is heated in a state where the substrate is seated on a support member installed inside the chamber. A primary plasma ashing process is performed on the substrate while the chamber is maintained at the first pressure. The temperature of the substrate is lowered while the chamber is maintained at the second pressure. A secondary plasma ashing process is performed on the substrate while the chamber is maintained at the 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, during the plasma ashing process, the temperature of the substrate is lowered for a while in the atmospheric pressure state, thereby preventing the chemical bond change of the photoresist, reducing popping and residue generation, the efficiency of ashing, and Product yield can be improved.

1 is a view showing a substrate manufacturing apparatus according to an embodiment of the present invention. 2 is a flowchart for explaining a method of manufacturing a wafer using the substrate manufacturing apparatus shown in FIG. 1. 2 is a diagram illustrating a process in which plasma ashing is performed in the substrate manufacturing apparatus illustrated in FIG. 1.

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

  FIG. 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 generation unit 200, and first and second exhaust pipes 310 and 320.

  The processing unit 100 performs a wafer ashing process, and the plasma generation unit 200 generates plasma necessary for the ashing process and provides the plasma to the processing unit 100. The first and second exhaust pipes 310 and 320 discharge the gas and reaction byproducts inside the processing unit 100 to the outside, and adjust the internal pressure of the processing unit 100.

  Specifically, 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 substrate processing process is performed, and the first and second exhaust holes 111a and 111b communicated with the first and second exhaust pipes 310 and 320 on the bottom surface 111, respectively. Is formed. The chamber 110 is grounded during the substrate processing process.

  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 a 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 at a preset temperature, and the support shaft 123 rotates around the central axis to rotate the support plate 121.

  A baffle 130 and a cover 140 are disposed on the chuck 120. The baffle 130 is coupled to the upper part of the chamber 110 and faces the support plate 121. The baffle 130 is grounded, filters the plasma generated from the plasma generation unit 200, and mainly passes the plasma radicals, and provides them to the process space (PS).

  The cover 140 is disposed on the chamber 110 and the baffle 130 and is coupled to the chamber 110 to seal the process space (PS). The cover 140 is coupled to the plasma generation unit 200 to form an inlet 141 into which plasma from the plasma generation unit 200 flows. Inside the cover 140, an induction space (GS) is formed in which plasma from the plasma generation unit 200 flows through the inlet 141. The plasma in the induction space (GS) is provided to the process space (PS) via the baffle 130. In one example of the present invention, the guide space (GS) is formed in an inverted conical shape.

  A plasma generation unit 200 is installed on the cover 140. The plasma generation 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 inflow pipe 250.

  Specifically, the magnetron 210 generates a microwave for plasma generation, and the waveguide 220 guides the microwave 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, plasma is generated by the processing gas from the first gas supply pipe 231 and the microwave from the magnetron 210.

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

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

  The plasma generation unit 200 may further include a third gas supply pipe 235 that provides a cleaning gas for cleaning the interior 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 the substrate processing process.

On the other hand, first and second exhaust pipes 310 and 320 are installed under the chamber 110. The first and second exhaust pipes 310 and 320 are coupled to the bottom surface 111 of the chamber 110, and the first and second exhaust holes 111a formed in the bottom surface 111 of the chamber 110,
111b is communicated with each other, and gas flowing into the process space (PS) and 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 adjusting device (not shown), and the pressure in the process space is adjusted through the first and second exhaust pipes 310 and 320.

  In this embodiment, the substrate manufacturing apparatus 400 includes two exhaust pipes 310 and 320, and the number of the exhaust pipes 310 and 320 increases or decreases depending on the size of the chamber 110.

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

  2 is a flowchart for explaining a method of manufacturing a wafer using the substrate manufacturing apparatus shown in FIG. 1, and FIG. 3 is a process in which plasma ashing is performed in the substrate manufacturing apparatus shown in FIG. It is drawing which shows.

  Referring to FIGS. 2 and 3, first, the support plate 121 of the chuck 120 is heated, and then the wafer 10 on which the photoresist is to be formed is seated on the support plate 121 (step S110). At this time, the support plate 121 is heated to about 200 ° C. to about 300 ° C., and the wafer 10 is subjected to a high dose implant (hereinafter referred to as HDI) or an implant process using plasma after the photoresist is formed. It is drawn into the chamber 110.

  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 placing the wafer 10 on the support plate 121 (S110) and the step of heating the wafer 10 (S120) are performed in a state where the internal pressure of the chamber 110 is maintained at atmospheric pressure.

  Subsequently, after the chamber 110 is evacuated, the wafer 10 is subjected to primary plasma ashing using oxygen gas (step S130).

  Specifically, oxygen gas is supplied from the first gas supply pipe 231 to the plasma source unit 240. On the other hand, microwaves are generated from the magnetron 210, and the microwaves are guided to the plasma source unit 240 through the waveguide 220. Accordingly, plasma containing oxygen is generated in the plasma source unit 240, and the generated plasma is provided to the wafer 10 via the inflow pipe 250 and the baffle 130. Thus, the primary plasma ashing process for the wafer 10 is performed.

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

  Subsequently, after the internal pressure of the chamber 110 is set to atmospheric pressure, the wafer 10 is put on standby with the wafer 10 separated from the support plate 121, and the temperature of the wafer 10 is lowered (S140). Here, the waiting time of the wafer 10 is about 30 seconds at the shortest.

  When separating the wafer 10 from the support plate 121, the wafer 10 is separated from the support plate 121 by about 1 cm or more by lift pins (not shown) installed on the support plate 121. Here, the lift pins allow the wafer 10 to be separated from the support plate 121 through a lifting operation while supporting the wafer 10.

  The wafer 10 can be pulled out from the chamber 110 and the wafer 10 can be separated from the support plate 121. In such a case, the wafer 10 can be cooled using a separate cooling member, and the wafer 10 can be put on standby at room temperature.

  The above-described method for lowering the temperature of the wafer 10 is performed at atmospheric pressure.

  Subsequently, after the wafer 10 is seated on the support plate 121, the wafer 10 is subjected to a secondary plasma ashing process 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 oxygen gas flow rate is about 1000 to about 5000 sccm, and the required time is about 10 to about 30 seconds. It is.

  Subsequently, in step S160, the pressure and power consumption of the chamber 110 are further increased, and the wafer 10 is subjected to the third plasma ashing process (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, and the oxygen gas flow rate is about 1000 to about 5000 sccm.

  In an example of the present invention, the primary plasma ashing process and the second plasma ashing process are performed under a lower pressure and lower power consumption than the tertiary plasma ashing process in consideration of the occurrence of popping. On the other hand, the tertiary plasma ashing process is performed under higher pressure and higher power consumption than the primary plasma ashing process and the secondary plasma ashing process in order to improve the ashing rate.

  When the removal of the photoresist is completed through the third plasma ashing process of the wafer 10, the wafer 10 is pulled out from the chamber 110 (S180), and the wafer 10 is washed with pure water and dried (step S190).

  In the above, plasma ashing is performed using oxygen gas, but the present invention is not limited to this.

  As described above, in the plasma ashing process according to the present invention, after the primary plasma ashing process is performed by heating the wafer 10 at atmospheric pressure, the temperature of the wafer 10 is decreased at atmospheric pressure to reduce the photoresist formed on the wafer 10. Prevents material changes, ie, chemical bond changes.

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

  Referring to Table 1, before the HDI process, the photoresist has about 26% carbon-oxygen bonds, about 74% carbon-hydrogen bonds, and about 0% amorphous carbon. Looking at the chemical bonds of the photoresist after the HDI treatment, the carbon-oxygen bond is reduced by about 14% from before the HDI treatment, the carbon-hydrogen bond is reduced by about 50% from before the HDI treatment, and the amorphous carbon is about 36% increase from before HDI treatment.

  When an HDI-processed photoresist is heated in a vacuum state at about 259 ° C., carbon-oxygen bonds are reduced by about 0% from before heating, carbon-hydrogen bonds are reduced by about 13% from before heating, and amorphous. Carbonaceous carbon is about 87%, increasing from before heating. That is, when a photoresist subjected to HDI treatment is heated in a vacuum state, a chemical bond is changed and amorphous carbon is rapidly increased.

  Accordingly, in the photoresist, the bonding group between carbon and carbon is increased, and double and triple bonds between carbon and carbon are increased and popping is increased. Generally, about 81 Kcal / mole of energy is required to decompose the carbon-carbon bond, while about 145 Kcal / mole and about 198 Kcal are required to decompose the carbon = carbon bond and carbon≡carbon bond, respectively. Since the energy of / mole is required, it becomes difficult to remove the residue by popping.

On the other hand, when the photoresist treated with HDI is heated to about 250 ° C. at atmospheric pressure, the carbon-oxygen bond is about 16%, the carbon-hydrogen bond is about 52%, and the amorphous carbon is about 32%. It is. In this way, when the HDI-treated photoresist is heated at atmospheric pressure, the chemical bond is almost unchanged from that before heating, thus preventing an increase in amorphous carbon, reducing popping,
Residue and photoresist can be easily removed.

  Hereinafter, with reference to FIGS. 2 and 3 and Table 1, the chemical bond change of the photoresist formed on the wafer 10 according to steps S120 to S150 is as follows.

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

  In step S130, the wafer 10 is subjected to a primary plasma ashing process in a high-temperature vacuum state, so that a chemical bond change occurs in the photoresist of the wafer 10. That is, amorphous carbon is rapidly increased in the photoresist of the wafer 10.

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

  As described above, the plasma ashing process according to the present invention lowers the temperature of the wafer 10 in the atmospheric pressure state after the primary plasma ashing process, and reduces the chemical bond change of the photoresist due to the temperature rise.

  Accordingly, the substrate manufacturing apparatus 400 can prevent popping, easily remove residues and photoresist, and improve plasma ashing efficiency. Since the substrate manufacturing apparatus 400 does not need to use a fluorine-based gas for preventing popping and removing residues, the oxide film loss of the wafer 10 can be prevented and the product yield can be improved. .

  The plasma ashing process according to the present invention minimizes the chemical bond change of the photoresist. Therefore, after the plasma ashing process, the wafer 10 is cleaned by using pure water without a separate chemical treatment during the cleaning process of the wafer 10. Manufacturing costs can be reduced.

  Although the present invention has been described with reference to the embodiments, those skilled in the art can make various modifications to the present invention without departing from the spirit and scope of the present invention described in the claims. Can be modified and changed.

10 Wafer 100 Processing Unit 110 Chamber 111 Bottom 111a, 111b Exhaust Hole 120 Chuck 121 Support Plate 123 Support Shaft 130 Baffle 140 Cover 141 Inlet 200 Plasma Generation Unit 210 Magnetron 220 Waveguides 231, 233, 235 Gas Supply Pipe 240 Plasma Source Pipe 250 Inflow pipe 310, 320 Exhaust pipe 400 Substrate manufacturing apparatus

Claims (18)

Heating a substrate on which a photoresist subjected to a hydose implant process is formed to 250 ° C. under atmospheric pressure;
Subjecting the substrate to a primary plasma ashing process in a vacuum state;
Lowering the temperature of the substrate at atmospheric pressure;
Sequentially performing a secondary plasma ashing process on the substrate in a vacuum state,
The gas during the ashing process is oxygen,
A substrate manufacturing method characterized by the above. Heating the substrate comprises:
Heating a support member installed in the chamber;
The substrate manufacturing method according to claim 1, further comprising: placing the substrate on the support member and heating the substrate while maintaining the internal pressure of the chamber at atmospheric pressure. Lowering the temperature of the substrate comprises:
The substrate manufacturing method according to claim 2, wherein the substrate is separated from the support member within a preset time while the internal pressure of the chamber is maintained at atmospheric pressure.   The method for manufacturing a substrate according to claim 3, wherein the step of lowering the temperature of the substrate includes separating the substrate from the support member by 1 cm or more.   The substrate manufacturing method according to claim 1, wherein the substrate is separated from the support member by a lift pin disposed on the support member when the temperature of the substrate decreases. The step of cooling the substrate is, after the substrate is pulled out from the chamber, placed outside the chamber within a preset time in an atmospheric pressure state,
The substrate manufacturing method according to claim 2, wherein the temperature outside the chamber is lower than the temperature inside the chamber.   The method for manufacturing a substrate according to claim 2, wherein in the step of cooling the substrate, after the substrate is pulled out of the chamber, the substrate is cooled in an atmospheric pressure state using a cooling device. .   The substrate manufacturing method according to claim 1, wherein the primary plasma ashing process and the secondary plasma ashing process are performed in a vacuum pressure state. The primary plasma ashing process and the secondary plasma ashing process, the substrate manufacturing method according to any one of claims 1 to 7 that is carried out using oxygen gas, characterized by. The heating time of the substrate is 2 to 20 seconds,
During 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, the gas flow rate used for the primary plasma ashing process is 1000 to 5000 sccm, and the required time is 10 Thirty seconds,
During 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 gas flow rate used for the secondary plasma ashing process is 1000 to 5000 sccm, and the required time is 10 to 10 times. The substrate manufacturing method according to claim 2, wherein the time is 30 seconds. After the secondary plasma ashing process step,
Further comprising performing a third plasma ashing process on the substrate;
The method of claim 10, wherein the tertiary plasma ashing process is performed under process conditions in which the internal pressure and power consumption of the chamber are higher than those in the primary and secondary plasma ashing processes.   The method of claim 1, wherein the substrate is subjected to an implant process using a high dose implant process or plasma before the step of heating the substrate. After the secondary plasma treatment step,
The method for manufacturing a substrate according to claim 1, further comprising cleaning the substrate using pure water without chemical treatment. Heating the substrate to 250 ° C. at atmospheric pressure in a state where a substrate on which a photoresist on which a high-dose implant process is performed is seated on a support member installed inside the chamber;
Performing a primary plasma ashing process on the substrate in a state where the interior of the chamber is maintained at a first pressure;
Lowering the temperature of the substrate while maintaining the interior of the chamber at a second pressure;
Sequentially performing a secondary plasma ashing process on the substrate while maintaining the interior of the chamber at a third pressure. The second pressure is higher than the first and third pressures,
The second pressure is the same as the atmospheric pressure;
The gas during the ashing process is oxygen,
A substrate manufacturing method characterized by the above.   The substrate manufacturing method according to claim 14, wherein the second pressure is atmospheric pressure.   The substrate manufacturing method according to claim 15, wherein the first and third pressures are vacuum pressures. The step of heating the substrate is performed for 2 to 20 seconds with the interior of the chamber maintained at atmospheric pressure.
During 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, the gas flow rate used for the primary plasma ashing process is 1000 to 5000 sccm, and the required time is 10 Thirty seconds,
During 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 gas flow rate used for the secondary plasma ashing process is 1000 to 5000 sccm, and the required time is 10 to 10 times. substrate manufacturing method according to any one of claims 14 to 16, wherein a is 30 seconds. After the secondary plasma ashing process,
Using pure water chemical treatment without, substrate manufacturing method according to any one of claims 14 to 16, wherein the, further comprising the step of cleaning the substrate.

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