JP2006005060A - Vacuum plasma apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the abnormal temperature rise of a member by suppressing an exothermic reaction to the contact of a metal member, such as a stainless steel used in the reaction treatment room, the exhaust gas system, and the treatment gas supply system of a vacuum plasma apparatus with gas species. <P>SOLUTION: A contact with a gas is covered by the passivity of an aluminum or a metal fluoride, and the contact of the exothermic reaction species is interrupted with a metal material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for preventing abnormal temperature rise in a reaction processing chamber, an exhaust system, and a processing gas supply system in a vacuum plasma processing apparatus.

  Currently, vacuum plasma processing apparatuses are used in various industrial fields such as metal material processing and semiconductor device manufacturing, and film formation is performed using plasma generated by introducing a processing gas into a vacuum chamber and performing discharge or the like. Surface treatments such as treatment and modification treatment are performed.

  In particular, in the manufacture of semiconductor devices, processes using a vacuum plasma apparatus such as etching, CVD, and ashing have been frequently used in recent years, and oxidizing power is present in the processing gas used and the reaction product gas after the plasma processing to be exhausted. Various molecular species such as possessed, reducing gas, self-decomposing gas are included.

  On the other hand, metal members such as stainless steel used for piping, valves, etc. may have reactivity and catalytic activity with respect to components in the processing gas and exhaust gas after plasma processing, and plasma processing chambers. Further, an exothermic reaction proceeds on the gas contact surface of the exhaust system and the processing gas supply system, which may lead to abnormal temperature rise of the member.

  In particular, when an exothermic reaction as described above occurs in a bellows portion having a large contact area with gas or a member having relatively low heat conduction to the surroundings, the abnormal temperature rise of the member becomes more prominent. There is a risk of accelerating the wear of parts and the deterioration of the O-ring used.

  For example, in Japanese Patent No. 3110465, a moisture generation method (Japanese Patent Laid-Open No. 6-115903) using a SUS-316L pipe subjected to electrolytic polishing treatment as a catalyst for generating moisture from hydrogen gas and oxygen gas is a conventional technique. It has been pointed out that there is a danger that heat is generated near the gas inlet of the stainless steel piping during the reaction.

  In addition, it is known that various reactions such as fluorination of chromium oxide and iron contained in stainless steel and decomposition reaction of monosilane used as a processing gas during film formation of silicon-based materials progress on the stainless steel surface. Therefore, there is a high risk of causing heat generation by the reaction heat accompanying the exothermic reaction in the contact portion with the processing gas or the exhaust gas.

The present invention has been made in view of the above problems, and suppresses an exothermic reaction in a contact portion between a metal member such as stainless steel and a gas in a vacuum plasma apparatus, thereby preventing an abnormal temperature rise, thereby improving the durability and safety of the apparatus. The purpose is to improve the sex.
Japanese Patent No. 3110465

  The present invention suppresses an exothermic reaction at a contact portion between a metal member such as stainless steel and a gas type in a reaction processing chamber, an exhaust system, and a processing gas supply system in a vacuum plasma processing apparatus, and prevents an abnormal temperature rise of the member. Therefore, it aims at improving the safety | security and durability of an apparatus.

  In order to solve the above-mentioned problems, the temperature rise prevention method of the present invention is such that a gas contact portion of a metal member such as stainless steel is made of aluminum or metal fluoride in a reaction processing chamber, an exhaust system, and a processing gas supply system in a vacuum plasma processing apparatus. It is comprised by covering with the passive state of.

  The contact between the metal material having reactivity or catalytic ability with respect to the active gas such as stainless steel and the exothermic reactive species contained in the processing gas or the exhaust gas is blocked, and the exothermic reaction on the surface of the metal material is suppressed. As a result, the temperature rise of the metal material can be minimized, and the safety and durability of the vacuum plasma apparatus can be improved.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration example of a vacuum plasma apparatus according to an embodiment of the present invention.

  The vacuum plasma apparatus shown in FIG. 1 is a microwave plasma processing apparatus. The processing chamber 6 introduces a processing gas used for plasma processing, an exhaust line 10 including an exhaust device 10 and an exhaust valve 9 for evacuating the processing chamber. A gas introducing device 8 and a gas introducing port 3 for performing the above operation, a microwave waveguide 1 for supplying a microwave for performing plasma discharge into the processing chamber, a microwave transmitting window 2 and a microwave power source 7 are provided. Yes. A stainless bellows 5 is connected in the middle of the exhaust line 4.

  The gas introduction device 8 is provided with a flow rate control device represented by a mass flow controller (not shown), and a plurality of processing gases can be mixed at a desired flow rate and introduced into the processing chamber 3.

  Further, a pressure controller (not shown) is provided between the vacuum valve 9 and the exhaust device 10, and the processing chamber 3 can be adjusted to a desired pressure.

  In the plasma chamber material, the potential state affected by the wall material and the grounding / floating of the wall greatly affects the potential distribution of the processing plasma and the disappearance time of the charged particles. For this reason, it is said that the reactivity with active species such as radicals / ions changes depending on the selection of the wall material, and the loss / adsorption establishment differs, thereby affecting the ratio of active species in the plasma.

  In the semiconductor device manufacturing process, contamination of the processing substrate with heavy metals such as Cr / Ni / Fe often adversely affects device performance. For the above reasons, the plasma processing chamber wall material should not be made of stainless steel with heavy metals such as Cr / Ni / Fe as the main component, but should be made of pure aluminum material or # 5000 series aluminum material containing a small amount of heavy metal. Mainstream.

  However, the bellows used in the exhaust line downstream of the process chamber after the substrate processing and the bellows in the exhaust valve having the bellows structure often use stainless steel for reasons of repeated strength.

  Plasma discharge was performed with the following gas composition using the vacuum plasma apparatus configured as described above.

Process gas: O2 3SLM + SF6 5sccm + H2 40sccm + Ar 1SLM
The above-mentioned plasma is altered and hardened by the irradiated ion component, especially in the process of removing resist used as a mask material for etching and ion implantation in the semiconductor device manufacturing process, and the processing substrate is placed on a high-temperature heater. Thus, it is used when it is difficult to remove by ordinary ashing in which processing is performed only with oxygen gas plasma.

  Hereinafter, the role of the plasma treatment will be specifically described.

  First, a process in a high dose ion implantation resist ashing apparatus having a plasma chamber for supplying a halogen-based gas such as CF4 / SF6 / NF3 will be described.

  A resist pattern is formed on the substrate, and ions are implanted into the substrate using the resist pattern as a mask for the purpose of diffusing impurities such as phosphorus, arsenic, and boron. At the time of this ion implantation, the kinetic energy of ions is converted into thermal energy, and the resist is heated to cause thermal alteration, and an altered portion called a hardened layer is generated. In the case of removing the resist pattern in which the altered hardened layer is formed in this way, conventionally, when the altered hardened layer is removed only by oxygen plasma, the normal resist remaining in the lower portion is also removed by ashing.

However, in particular, a high dose ion implantation process in which ion acceleration energy is 100 keV or more and an ion implantation amount is 1 × E16 ions / cm ² or more, for example, p_MOS / n_MOS formation in the DRAM manufacturing process and ion ashing process after the ion implantation. The implanted modified hardened layer resist has a larger activation energy than a normal resist, and the conventional oxygen radical-based ashing method has a problem of requiring an ashing time because of a low reaction rate.

  In addition, since the ashing speed is highly temperature dependent, it is conceivable to increase the ashing speed by increasing the processing temperature. However, in this case, the N2 and other degassing occurs in the lower layer resist that is different in thermal expansion between the altered hardened layer and the non-hardened resist layer and is not altered by high temperature ashing. There is also a report that the modified hardened layer causes a cross-linking reaction when the ion-implanted species is heated. Especially, the novolak resist and phosphorus are transformed into a very hard film. A phenomenon called “popping” occurs, and the scattered surface altered layer is reattached to the substrate surface, which makes it impossible to peel off in the subsequent cleaning process and causes a reduction in the yield of semiconductor devices.

  Therefore, in resist ashing that has undergone such high-dose ion implantation treatment, the activation energy of the above-mentioned altered hardened layer is lowered by adding a halogen-based gas such as CF4 / SF6 / NF3 and no burst occurs. A method of increasing the ashing speed at a low temperature is becoming common.

  The plasma discharge as described above was performed in the processing chamber 3, and the temperatures outside the casing of the exhaust valve 9 and outside the stainless bellows 5 were measured with a thermocouple. Actually, a 3.0 kW, 2.45 GHz microwave oscillator was used, and plasma discharge was performed under a cycle oscillation condition of a processing pressure of 146 Pa (1.1 Torr), a microwave oscillation time of 200 seconds, and 60 seconds OFF. 2 shows the casing temperature measurement location of the stainless steel bellows portion exhaust valve 9 and FIG. 2 shows the temperature measurement location of the outer surface of the bellows portion 5.

  FIG. 3 shows the results of measuring the casing temperature transition of the stainless steel bellows part exhaust valve 9. In this measurement, a temperature increase of about 10 ° C from 32 ° C to 42 ° C was confirmed by 6 cycles of microwave oscillation. In addition, as shown in FIG. 4, when plasma discharge was performed under the same conditions without adding SF6, the temperature rise was clearly reduced (about 1.0 ° C./6 cycles). It was shown that the increased temperature was not due to heat conduction from the exhaust gas.

  Further, the temperature rise of the stainless steel welded bellows 5 under the same plasma discharge conditions is much larger than the outside of the exhaust valve 9, and as shown in FIG. 5, about 40 ° C. (33 ° C. → 73 ° C.) in two 200 sec plasma discharge cycles. ) Was observed. It was also confirmed that this abnormal temperature increase reached about 170 ° C. by repeating the discharge cycle.

  Next, FIG. 6 shows a state in which a cylindrical aluminum (material: A5052) cover 15 having a thickness of 0.5 mm is attached to the stainless steel bellows portion 11 of the exhaust valve 9 for the purpose of suppressing the exothermic reaction according to the present invention. FIG. 7 shows a graph obtained by measuring and plotting the temperature of the exhaust valve casing surface under the above-described processing conditions (see FIG. 3) using this exhaust valve.

  The temperature rise by 6 cycles of microwave oscillation was suppressed to about 1.5 ° C, confirming the heat generation suppressing effect of the aluminum cover.

  Similarly, FIG. 8 shows a state in which a cylindrical aluminum (material: A5052) cover 16 is attached to a location 5 where a stainless steel material is used for the pipe bellows portion. The graph which measured and plotted the temperature of the pipe bellows outer surface on the above-mentioned process conditions (refer FIG. 7) using this pipe bellows is shown in FIG.

  Two cycles of microwave oscillation caused the temperature to rise from 40 ° C from 33 ° C to 73 ° C without the aluminum cover (Figure 7), compared with 3 ° C at 1/13 from 28 ° C to 31 ° C with the aluminum cover. However, only the temperature was raised, and the heat generation suppressing effect of the aluminum cover was confirmed.

  In this example, aluminum (A5052) was used as the material to be coated. However, the effect of the present invention is not limited to this, and fluorine-free surfaces are in contact with other aluminum alloys, pure aluminum materials, and gases. A metal material subjected to a kinetic treatment can be used in the same manner.

  Also, the coating method is not limited to the cylindrical cover, and the same applies to other forms such as coating treatment by film formation and surface passivation treatment as long as the contact between the exothermic reactive species and the metal material can be blocked. An effect can be obtained.

It is a figure which shows the structural example of the vacuum plasma apparatus concerning one Example of this invention. It is a figure which shows the temperature measurement location of the bellows part structure exhaust valve made from stainless steel, and the temperature measurement location of the piping bellows part outer surface. It is a figure which shows the graph which plotted the casing temperature transition of stainless steel bellows part structure exhaust valves. It is a figure which performed the plasma discharge without adding SF6 to process gas, and shows the graph which plotted the casing temperature transition of the stainless steel bellows part structure exhaust valve. It is a figure which shows the graph which plotted the bellows outer surface temperature transition of the stainless steel bellows part. It is a figure which shows the exhaust valve figure of stainless steel bellows part structure, and the attachment figure of the aluminum cover for heat_generation | fever suppression. It is the graph which plotted the bellows outer surface temperature transition at the time of mounting | wearing with the cover made from aluminum to the exhaust valve of stainless steel bellows part structure. It is a figure which shows the mounting state of the stainless steel piping bellows and the aluminum cover for heat_generation | fever suppression. It is the graph which plotted the bellows outer surface temperature transition at the time of attaching an aluminum cover to a stainless steel bellows part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave waveguide 2 Microwave transmission window 3 Process gas introduction port 4 Exhaust line 5 Stainless steel piping bellows part 6 Plasma processing chamber 7 Exhaust valve casing bottom surface temperature measurement part 8 Microwave power supply 9 Exhaust valve which has stainless bellows component 10 Exhaust device 11 Stainless steel bellows in exhaust valve 12 Exhaust valve casing temperature measurement location 13 Exhaust valve casing 14 Stainless steel piping bellows temperature measurement location 15 Aluminum cover for stainless steel bellows portion in exhaust valve 16 Aluminum cover for stainless steel piping bellows

Claims (5)

  In the vacuum plasma apparatus, the contact portion between the metal material portion and the exhaust gas exhausted from the processing gas or the plasma processing chamber is coated with a metal material other than iron, nickel, chromium or a metal fluoride. Vacuum plasma equipment.   The vacuum plasma apparatus according to claim 1, wherein the covering process is performed with an aluminum material.   The vacuum plasma apparatus according to claim 1, wherein the coating treatment is performed on a member made of stainless steel or a constituent material of stainless steel.   The vacuum plasma apparatus according to claim 1, wherein the covering process is performed on a bellows-shaped member.   The vacuum plasma apparatus according to claim 1, wherein the covering process is performed by fixing and covering an aluminum cover on the contact portion.

Images