JP4598416B2 - Plasma processing method - Google Patents

Description

The present invention, in the semiconductor and thin-film display industry, which can be used in thin-film circuit forming method, in particular glass or quartz having a high substrate insulating property, the transistor element can be formed plasma treatment how on such compound semiconductor In this regard, the substrate to be processed before plasma processing is already in a state where the electric charge has accumulated, and if the substrate to be processed in this state is plasma-processed, device damage and device destruction can be effectively reduced. about the plasma processing how that can be.

  In recent years, in the field of thin-film device manufacturing, there has been an increasing demand for a simplified manufacturing process and a manufacturing method with a low environmental impact from the viewpoint of manufacturing cost reduction and environmental protection. A thin film processing method and apparatus are desired.

  However, the thin film element device is manufactured through a variety of manufacturing processes, such as heat treatment, water washing treatment, and plasma treatment, so that the substrate to be treated is always caused by various factors. Accumulation of charge occurs on the front and back of the film.

  Thin film processing and equipment using plasma generates plasma in a vacuum, dissociates process gases, and performs processing that combines physical and chemical reactions with ions and radicals, so it is on the substrate to be processed. A large amount of charge is generated.

  Due to the structure of the thin film circuit, a large amount of generated charge has a thin insulating film that insulates between the metal film, but the withstand voltage has a threshold value that exceeds the threshold value. When the substrate to be processed has such a charge and is charged, the insulating film is broken and a thin film circuit cannot be formed. For this reason, efforts have been made to reduce the charged charge by means of a plasma process, or to make the plasma as low as possible on the substrate to be processed.

  Hereinafter, a typical dry etching apparatus will be described with reference to FIG.

  101 is a plasma processing vessel for performing a dry etching process, 101a is a process gas and inert gas introducing device, 102 is an electrode having a function of generating plasma for placing a substrate to be processed 112, and 103 is evacuated. 104, a vacuum transfer container for transferring the substrate 112 to and from the plasma processing container in a vacuum pressure state, 104a a vacuum exhaust device, 104b an inert gas introducing device, 105 a plasma processing container 101 and a vacuum transfer container 104 is a gate door having an opening / closing mechanism as a partition 104, 106 is a vacuum transfer mechanism, 106a is interlocked with the vacuum transfer mechanism 106, and lift pins that operate to place the substrate 112 to be processed on the electrode 102, 107 from the atmospheric state A function that can reduce the pressure inside the container to a vacuum state and vice versa. A load lock container, 107a is an evacuation device, 107b is an inert gas introduction device, 108 is a gate door which serves as a partition wall between the vacuum transfer container 104 and the load lock container 107 and has an opening / closing mechanism, and 109 is a vacuum for the load lock container 107 A gate door for holding, 110 a substrate storage device for storing the substrate 112 to be processed, 111 an atmospheric transfer mechanism for taking out the substrate 112 from the substrate storage device 110 and transferring it to the load lock container 107 It is.

  The operation of the dry etching apparatus configured as described above will be described below.

  First, the substrate 112 to be processed is taken out from the substrate storage device 110 by the atmospheric transfer mechanism 111, and the load lock container 107 is purged with an inert gas from the inert gas introduction device 107b to the atmospheric state, and the gate door 109 is opened. The substrate 112 to be processed is transferred to the load lock container 107 by the atmospheric transfer mechanism 111.

  Subsequently, the gate door 109 is closed, the operation of the inert gas introduction device 107b is stopped in the load lock container 107, the exhaust device 107a is exhausted, and after the vacuum exhaust is completed to a certain pressure, the gate door 108 is opened. open. The vacuum transfer container 104 is in a state where the exhaust device 104a is always evacuated and always kept in a vacuum state. The substrate to be processed 112 placed on the load lock container 107 is taken out by the vacuum transfer mechanism 106, transferred to the vacuum transfer container 104, and the gate door 108 is closed.

  The evacuation apparatus 103 in the plasma processing vessel 101 is always evacuated and the inside of the vessel is always kept in a vacuum state. The gate door 105 is opened, the substrate to be processed 112 in the vacuum transfer mechanism 106 in the vacuum transfer container 104 is transferred to the electrode 102 of the plasma processing container 101, the substrate 112 to be processed is placed on the lift pins 106a, and the gate The door 105 is closed, the lift pins 106a are lowered, the substrate to be processed is placed on the electrode 102, and then plasma processing is performed.

After the plasma treatment is completed, a process of removing a charge on the substrate to be treated 112 by changing a plasma generation region by pressure or power, which is called a static elimination process with a gas such as N ₂ or O ₂ , or a process During the processing, the lift pins 106a are raised to raise the substrate 112 to be processed.

  Thereafter, the gate door 105 is opened, and the substrate to be processed 112 on the lift pins 106 a in the plasma processing chamber 101 is taken out from the plasma processing chamber 101 by the vacuum transfer mechanism 106 and transferred to the vacuum transfer chamber 104. The

  At this time, the vacuum exhaust apparatus 103 of the plasma processing vessel 101 performs an exhausting operation so that the reaction product after the plasma processing does not flow into the vacuum transfer vessel 104. The gate door 105 is closed, then the gate door 108 is opened, the substrate 112 to be processed is transferred to the load lock container 107 by the vacuum transfer mechanism 106, and the gate door 108 is closed. The vacuum exhaust device 107a in the load lock container 107 is stopped, the inert gas is purged from the inert gas introduction device 107b, the inside of the load lock container 107 is changed from the vacuum pressure state to the atmospheric pressure state, the gate door 109 is opened, The substrate to be processed 112 in the load lock container 107 is taken out by the atmospheric transfer mechanism 111 and stored in the substrate storage device 110. See Patent Documents 1 to 3.

JP-A-7-106314 Japanese Patent No. 3227812 Japanese Patent No. 3170849

  However, after the plasma processing of the substrate 112 to be processed in the plasma processing chamber 101 is completed and the charge removal process is completed, the gate door 105 is opened, and the substrate to be processed on the electrode 102 in the plasma processing chamber 101 is opened by the vacuum transfer mechanism 106. When the 112 is taken out from the plasma processing container 101 and transferred into the vacuum transfer container 104, the potential value of the electric charge remaining on the surface of the substrate to be processed 112 behaves as shown in FIG. Indicates.

  The electric charge charged on the surface of the substrate to be processed 112 after the plasma treatment shows a maximum potential value when passing through the gate door 105, and the substrate to be processed 112 is then transferred to the vacuum transfer container 104 while maintaining a high potential. Placed. There is a problem that dielectric breakdown occurs when the charged potential that changes when the substrate to be processed 112 is transferred in a vacuum exceeds the withstand voltage threshold value 102a of the insulating film formed on the substrate to be processed 112.

  As shown in FIG. 5, when the substrate to be processed 112 is transferred, the charge −Q charged on the surface of the substrate to be processed 112 is polarized oppositely to the charge + Q on the surface of the electrode 102. (At this point, since the distance d between the back surface of the substrate to be processed 112 and the surface of the electrode 102 is extremely large, this does not apply to the formula of (Equation 1)). Only when there is a distance d that fits the following formula (formula 1) when changing to the bottom surface of the gate door 105 and the bottom surface of the vacuum transfer container 104.

ただし、Ｃ_ｇは距離ｄのギャップでのコンデンサー容量、Ｖ_ｇは距離ｄのギャップでの電位差、Ｓは面積、ｄは距離、εは誘電率である。なお、図５中、Ｖ_ｇｍａｘは距離ｄでの最大ギャップでの電位である。
前記（式１）から分かるように、ｄ（距離）に影響される領域（ｄｍｉｎ）に達した時に、Ｖ_ｇが上昇する可能性があるためと考えられる。

Where C _g is the capacitor capacity at the gap of distance d, V _g is the potential difference at the gap of distance d, S is the area, d is the distance, and ε is the dielectric constant. In FIG. 5, V _gmax is a potential at the maximum gap at the distance d.
As can be seen from the above (Equation 1), it is considered that V _g may increase when the region (dmin) affected by d (distance) is reached.

  Of course, it can be easily imagined that the surface potential of the substrate to be processed 112 rises the most at the moment when the substrate to be processed 112 is separated from the electrode 102. Since a part of the substrate 112 passes through the gate door 105, the surface potential of only a part of the substrate 112 to be processed may be abnormally increased, and it is assumed that dielectric breakdown occurs in that part.

  In addition, even if dielectric breakdown does not occur, a thin film that remains active and is formed on the substrate to be processed 112, which is generally referred to as damage, changes the composition inside the thin film due to local increase in charge. It also becomes a factor that degrades the characteristics and performance of the thin film.

In general vacuum mass production equipment, the gate door is made as small as possible to reduce the pressure loss when the gate door is opened and closed. The distance between the substrate to be processed 112 and the gate door 105 at the point where the substrate to be processed 112 passes through the gate door 105 is influenced by the basic formula of capacitance because the substrate to be processed 112 and the gate door 105 are as close as possible. It will be a range. A part of the substrate 112 to be processed has a higher potential Vg than when the potential _Vg is on the electrode 102.

  As long as the substrate to be processed 112 is transferred in a vacuum, there is no place where the accumulated charge is discharged, so that the charge remains at a very high level until the atmospheric condition. Therefore, depending on the form of mass production equipment, not only the gate door 105 but also other parts may be easily affected by (Equation 1).

The present invention is, that such light of the conventional problems, to provide a plasma processing how that can reduce the amount of charge to be treated on a substrate which changes in transferring a substrate to be processed after the plasma treatment With the goal.

  In order to achieve the above object, the present invention is configured as follows.

According to the first aspect of the present invention, in the plasma processing method of forming a thin film circuit on the substrate to be processed by applying power to the electrode on which the substrate to be processed is placed under reduced pressure,
Wherein the plasma treatment is applied to a previously treated substrate, wherein in a state where the target substrate is released from the electrode, the front and back surfaces of the substrate to be processed charge removal plasma in a gas mainly containing inert gas and 曝, to provide a plasma processing method characterized by removing the charges on the surface and the back surface of the substrate to be treated.
According to a second aspect of the present invention, there is provided the plasma processing method according to the first aspect, wherein the charged charge removing plasma is 1/3 or less of the high frequency power during the plasma processing.
According to a third aspect of the present invention, there is provided the plasma processing method according to the first or second aspect, wherein the charged charge removing plasma is 0.1 to 1.0 W / cm ² .
According to a fourth aspect of the present invention, the above charge removing plasma exposure of the substrate to be processed, by removing the charged charges on the surface and the back surface of the substrate to be processed, and the front and back surfaces of the substrate to be processed The plasma processing method according to any one of the first to third aspects, wherein the surface of the electrode has the same potential.

According to the present invention, before performing the plasma treatment on the substrate to be processed, the initial charge of the substrate to be processed is obtained by applying the substrate to be charged to the plasma for removing charged charges in a gas mainly composed of an inert gas. was removed in the plasma treatment immediately before the surface of the front and back surfaces and the electrodes of the substrate as the same potential, it is possible to provide a plasma treatment how that can prevent plasma damage that occurs after the plasma treatment.

  Conventionally, in general, before plasma processing, there is a possibility that reactive organisms attached to the wall of the plasma processing chamber may fly and adhere to the substrate to be processed, resulting in particle failure. It was not thought. However, in recent years, the ratio of defects that occur when a substrate to be processed is charged during transportation and the charged substrate to be processed is placed on an electrode that is charged at a different potential than the ratio of particle defects. There is a tendency to increase. Therefore, the present invention generates a minimum amount of plasma while minimizing the influence of reactive organisms attached to the wall of the plasma processing chamber so as not to cause particle defects, while generating both surfaces of the substrate to be processed and the electrodes. The surface is set to the same potential. In other words, plasma damage that occurs after plasma processing is more effective by generating a minimum plasma that can make the front and back surfaces of the processing substrate and the surface of the electrode have the same potential, that is, plasma for removing charged charges. Can be prevented.

  Embodiments according to the present invention will be described below in detail with reference to the drawings.

  A plasma processing method and apparatus according to a first embodiment of the present invention will be described with reference to the drawings.

A typical dry etching apparatus and method for the plasma processing method and apparatus according to the first embodiment will be described below with reference to FIGS. 1A, 1B, and 2. FIG. 1 is a plasma processing container for dry etching (an example of a plasma processing chamber), 1a is an inert gas introduction device that introduces an inert gas into the plasma processing container 1 when charged charges are removed before plasma processing, and 1b is plasma. It is a process gas introduction device that introduces a process gas into the plasma processing container 1 during processing. 2 is an electrode having a function of generating plasma for placing the substrate 12 to be processed, 2a is a high-frequency power source, 2b is a grounded counter electrode, and 2c is interposed between the high-frequency power source 2a and the electrode 2. The matching box is an impedance matching circuit. Reference numeral 3 denotes an evacuation apparatus such as a pump for reducing the pressure in the plasma processing chamber 1, and 4 is adjacent to the plasma processing chamber 1 in order to put the substrate 12 to be processed in and out of the plasma processing chamber 1 in a vacuum pressure state. The vacuum transfer container (an example of a vacuum transfer chamber), 4a is a vacuum exhaust device such as a pump for reducing the pressure in the vacuum transfer container 4 in the same manner as the plasma processing container 1, and 4b is N ₂ in the vacuum transfer container 4. N ₂ gas introduction device 5 for introducing gas serves as a partition between plasma processing container 1 and vacuum transfer container 4 and has a gate door having an opening / closing mechanism, and 6 is a combination of vacuum plasma processing container 1 and vacuum transfer container 4. This is a vacuum transfer mechanism for transferring the substrate 12 to be processed. Reference numeral 6a denotes a lift pin used for separating the substrate 12 to be processed and the electrode 2 in the plasma processing chamber 1. Reference numeral 6b denotes a lift pin lifting device such as a motor or an air cylinder for raising and lowering the lift pin 6a. Reference numeral 7 denotes a vacuum state from an atmospheric state. A load lock container (an example of a load lock chamber) having a function capable of depressurizing the inside of the container and conversely, an operation of pressurizing from a vacuum state to an atmospheric state, and 7a represents the depressurization operation in the load lock container 7. An evacuation device such as a pump, 7b is an N ₂ gas introduction device. Reference numeral 8 denotes a gate door which serves as a partition wall between the vacuum transfer container 4 and the load lock container 7 and has an opening / closing mechanism, 9 is a gate door for holding the load lock container 7 in a vacuum, and 10 is a substrate for storing the substrate 12 to be processed. It is a storage device. Reference numeral 11 denotes an atmospheric transfer mechanism such as a robot arm for taking out the substrate 12 to be processed from the substrate storage apparatus 10 and transferring it to the load lock container 7. Reference numeral 1000 denotes an inert gas introduction device 1a, a process gas introduction device 1b, a high frequency power source 2a, a matching box 2c, a vacuum exhaust device 3, a vacuum exhaust device 4a, an N ₂ gas introduction device 4b, a gate door 5, and a vacuum transfer mechanism 6. And a lift pin elevating device 6b, an evacuating device 7a, an N ₂ gas introducing device 7b, a gate door 8, a gate door 9, a substrate storage device 10, and an atmospheric transfer mechanism 11.

  The operation of the dry etching apparatus configured as described above will be described below. The following operations are controlled by the control apparatus 1000.

First, the substrate 12 to be processed is taken out from the substrate storage device 10 by the atmospheric transfer mechanism 11, and the load lock container 7 is purged with N ₂ gas from the inert gas introduction device 7b to be in the atmospheric state, and the gate door 9 is opened. The substrate to be processed 12 is transferred to the load lock container 7 by the atmospheric transfer mechanism 11. Subsequently, the gate door 9 is closed, the operation of the inert gas introduction device 7b is stopped in the load lock container 7, the exhaust device 7a is exhausted, and after the vacuum exhaust is completed to a certain pressure, the gate door 8 is opened. open.

  In the vacuum transfer container 4, the exhaust device 4 a is always evacuated and always kept in a vacuum state. The to-be-processed substrate 12 mounted on the load lock container 7 is taken out by the vacuum transfer mechanism 6, transferred to the vacuum transfer container 4, and the gate door 8 is closed. The vacuum evacuation device 3 in the plasma processing container 1 is always evacuated, and the plasma processing container 1 is always kept in a vacuum permanent position. The gate door 5 is opened, the substrate 12 in the vacuum transfer mechanism 6 in the vacuum transfer container 4 is transferred onto the lift pins 6a of the plasma processing container 1, and the gate door 5 is closed.

In a state where the substrate 12 to be processed is held on the lift pins 6a, an inert gas is introduced into the plasma processing container 1 from the inert gas introduction device 1a, and a high frequency power is applied to the electrode 2 from the high frequency power source 2a. A weakly charged charge removing plasma is generated so that the substrate 12 to be processed is not etched or a thin film is not formed in a gas mainly composed of an inert gas. That is, here, an inert gas such as N ₂ gas is introduced from the inert gas introduction device 1a, the inside of the plasma processing vessel 1 is regulated to about 40 Pa by the vacuum exhaust device 3, and 0.1 W from the high frequency power source 2a. A weakly charged charge removing plasma is applied for 5 seconds to which high frequency power of / cm ² is applied to the electrode 2, and pretreatment charge removal is performed on both the front and back surfaces of the substrate 12 and the surface of the electrode 2, so that the front and back surfaces of the substrate 12 are processed. Both surfaces and the surface of the electrode 2 are set to the same potential. Thereafter, the lift pin 6a is lowered by driving the lift pin lifting / lowering device 6b, the substrate 12 is placed on the electrode 2, the introduction of the inert gas from the inert gas introduction device 1a is stopped, and the process gas is processed. A desired plasma process is performed on an 8-inch wafer as an example of the substrate 12 to be processed by applying the high frequency power of 100 to 150 W / cm ^{2 to} the electrode 2 from the high frequency power source 2a. Done. When desired plasma processing is performed, a chlorine-based gas is introduced as a process gas to the metal-based thin film of the substrate 12 to be processed, and a fluorine-based gas is introduced as a process gas to the substrate 12 to be processed of silicon. For plasma processing of the resist on the substrate 12 to be processed, an oxygen-based gas is introduced as a process gas to perform desired plasma processing, for example, processing such as etching, thin film formation, and resist removal.

Here, the high-frequency power used when generating the weak plasma that does not etch the substrate 12 or form a thin film in the gas mainly composed of the inert gas is the high-frequency power at the time of plasma processing. 1/3 or less, or 0.1-1.0 W / cm < ² > is preferable. The time is preferably 10 seconds or less.

The inert gas is at least one of Ar, He, N ₂ , H ₂ , and vaporized H ₂ O gas.

  Further, the lift pin 6a is not limited to the one in which the lift pin 6a is lowered after performing the pre-treatment charge removal on the substrate 12 and the electrode 2, but the lift pin 6a is lowered while performing the pre-treatment charge removal on the substrate 12 and the electrode 2. Also good.

  As described above, the charged potential on the substrate 12 to be processed was measured with a non-contact surface potential meter in a vacuum in the plasma processing chamber 1 when the pretreatment with weak plasma was performed and when it was not performed. As a result, the charges accumulated on the surface of the substrate to be processed 12 are as shown in Table 1.

従来は所望のプラズマ処理中にプラズマから発生し与えられる電荷によって、プラズマダメージや絶縁破壊が発生すると考えられていた。

Conventionally, it has been considered that plasma damage and dielectric breakdown occur due to electric charges generated from plasma during desired plasma processing.

  However, from the above evaluation results that form the basis of the present invention, the electric charge charged only on the front side of the substrate to be processed 12 in the desired plasma treatment is added to the charges on the front and back of the substrate to be processed 12 accumulated before the processing. Thus, it is considered that the charge balance between the front and back surfaces of the substrate 12 to be processed is disturbed, adversely affects the devices on the thin film circuit, and causes plasma damage and dielectric breakdown.

  The charge of the substrate to be processed 12 from the beginning is the heat treatment or washing treatment in the previous process, or frictional charging in the process of transporting the substrate to be processed 12 in the atmosphere, or from the substrate storage device 10 to the load lock container 7. It is presumed that the charge is triboelectrically charged when transferred and exhausted from atmospheric pressure to a vacuum state.

  Therefore, immediately before performing the desired plasma treatment, the front and back surfaces of the substrate to be processed 12 and the surface of the electrode 2 are simultaneously subjected to a neutralization process with a weak plasma as a pretreatment. The surface of the substrate 12 and the surface of the electrode 2 are neutralized by making the same potential through a medium called plasma, and plasma damage that occurs after the plasma treatment, for example, plasma damage or dielectric breakdown on the device on the thin film circuit Can be effectively prevented.

  Thereafter, the lift pin 6a is raised by driving the lift pin lifting device 6b, and the substrate 12 to be processed is separated from the electrode 2. Next, the gate door 5 is opened, and the substrate to be processed 12 on the lift pins 6 a in the plasma processing container 1 is taken out from the plasma processing container 1 by the vacuum transfer mechanism 6 and transferred to the vacuum transfer container 4. The

Further, after the plasma treatment is completed, by performing a process treatment for removing charges charged on both the front and back surfaces of the substrate 12 and the surface of the electrode 2 in a charge removal process using a gas such as N ₂ or O ₂ , Damage suppression effect is demonstrated.

Thereafter, the N ₂ gas introduction device 4b is stopped, the gate door 5 is closed, the vacuum exhaust device 4a is operated, the inside of the vacuum transfer container 4 is exhausted to a predetermined pressure or less, and the vacuum exhaust device 3 performs plasma processing. The container 1 is also evacuated to a predetermined pressure or lower. Next, the gate door 8 is opened, the substrate 12 to be processed is transferred to the load lock container 7 by the vacuum transfer mechanism 6, and the gate door 8 is closed. The vacuum exhaust device 7a in the load lock container 7 is stopped, the inert gas is purged from the inert gas introduction device 7b, the inside of the load lock container 7 is changed from the vacuum pressure state to the atmospheric pressure state, the gate door 9 is opened, The substrate to be processed 12 in the load lock container 7 is taken out by the atmospheric transfer mechanism 11 and stored in the substrate storage device 10.

  Although the parallel plate RIE plasma processing method has been described as an embodiment of the present invention, the same effect can be obtained even if this is a plasma processing method such as an ICP method, an ECR method, or a PE method.

  In addition to the plasma processing container 1, the same processing can be performed by separately arranging a processing container dedicated to pretreatment for generating a plasma for removing charged charges, or by preprocessing with a container such as the vacuum transfer container 4. An effect is obtained.

  It is to be noted that, by appropriately combining any of the various embodiments, the effects possessed by them can be produced.

1 is a plan view of a schematic configuration of a plasma processing apparatus according to a first embodiment of the present invention. It is a side view of schematic structure of the plasma processing container of the plasma processing apparatus concerning said 1st embodiment of the present invention. It is a side view of schematic structure of the plasma processing apparatus concerning said 1st embodiment. It is a schematic block diagram of the conventional plasma processing apparatus. (A), (b) is a graph which shows the schematic block diagram of the conventional plasma processing apparatus, and the relationship between the position of a to-be-processed substrate and the surface charge value in the schematic structure of the conventional plasma processing apparatus, respectively. FIG. 5 is a schematic diagram illustrating a mechanism for increasing a surface potential of a substrate to be processed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma processing container 1a Inert gas introduction apparatus 1b Process gas introduction apparatus 2 Electrode 2a High frequency power supply 2b Counter electrode 2c Matching box 3 Vacuum exhaust apparatus 4 Vacuum transfer container 4a Vacuum exhaust apparatus 4b Inert gas introduction apparatus 5 Gate door 6 Vacuum Transport mechanism 6a Lift pin 6b Lift pin lifting device 7 Load lock container 7a Vacuum exhaust device 7b Inert gas introduction device 8 Gate door 9 Gate door 10 Substrate storage device 11 Atmospheric transport mechanism 12 Substrate to be processed 1000 Control device

Claims (4)

In the plasma processing method of forming a thin film circuit on the substrate to be processed by applying electric power to an electrode on which the substrate to be processed is placed under reduced pressure,
Wherein the plasma treatment is applied to a previously treated substrate, wherein in a state where the target substrate is released from the electrode, the front and back surfaces of the substrate to be processed charge removal plasma in a gas mainly containing inert gas 曝 and, a plasma processing method characterized by removing the charged charges on the surface and the back surface of the substrate to be treated.   2. The plasma processing method according to claim 1, wherein the plasma for removing charge charges is 1/3 or less of high-frequency power during plasma processing. The plasma processing method according to claim 1 or 2, wherein said charge removing plasma is 0.1~1.0W / cm ^2. Exposing said target substrate to said charge removing plasma, by removing the charges on the surface and the back surface of the substrate, and a surface of the front and back surfaces and the electrodes of the substrate to be processed at the same potential The plasma processing method according to any one of claims 1 to 3.

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