TWI817230B - Radio frequency adjustment device, plasma processing equipment and radio frequency electric field adjustment method - Google Patents

Abstract

The invention provides a radio frequency adjustment device, plasma processing equipment and a radio frequency electric field adjustment method, which include a baffle located between a reaction chamber and a lining of the plasma processing equipment, and a driving element that controls the movement of the baffle. By changing the baffle position to adjust the capacitance of the radio frequency circuit inside the plasma processing equipment, thereby adjusting the uniformity of the radio frequency electric field, effectively compensating for the uneven radio frequency electric field caused by the opening of the film transfer port on the side wall of the reaction chamber or the asymmetry of the internal components of the reaction chamber, so that the formed The plasma is more uniform and stable, ensuring the processing yield of the substrate surface.

Description

Radio frequency adjustment device, plasma processing equipment and radio frequency electric field adjustment method

The present invention relates to the technical field of plasma etching, and in particular to a radio frequency adjustment device, plasma processing equipment using the device, and a radio frequency electric field adjustment method.

Micromachining of semiconductor substrates or substrates is a well-known technology that can be used to manufacture, for example, semiconductors, flat panel displays, light emitting diodes (LEDs), solar cells, etc. An important step in micromachining manufacturing is the plasma treatment process step, which is performed inside a reaction chamber into which process gases are input. The radio frequency source is inductively and/or capacitively coupled to the inside of the reaction chamber to form a radio frequency electric field to excite the process gas to generate and maintain plasma, and the substrate is etched through the plasma.

The density of the plasma will affect the etching efficiency, and the distribution of the radio frequency electric field will affect the density of the plasma. Generally speaking, one factor that affects the RF electric field inside the reaction cavity is the morphology inside the reaction cavity. In order to achieve a uniform RF electric field as much as possible, the reaction cavity and internal components are usually designed into a symmetrical structure, that is, a common cylindrical or annular shape. status.

However, in the conventional technology, not all reaction chambers and internal components can be designed into a symmetrical structure around the center. Depending on the situation, some asymmetric components will affect the uniform distribution of the radio frequency electric field, which will lead to different etching rates. Reduced yield of semiconductor processing.

In order to solve the above technical problems, the present invention provides a radio frequency adjustment device, located between the inner wall and the lining of the reaction chamber of the plasma processing equipment, for adjusting the distribution of the radio frequency electric field, including: located on the inner wall of the reaction chamber and baffles between linings and not in contact with either; and A driving element located in the reaction chamber, the driving element is fixedly connected to the baffle, and is used for the baffle to move along the inner wall of the reaction chamber.

Preferably, the baffle is annular and is divided into at least two arc-shaped plates in the circumferential direction of the ring, and the driving element can control the arc-shaped plates to move respectively.

Preferably, at least two of the arc-shaped plates have different heights.

Preferably, the baffle is made of semiconductor.

Preferably, the baffle is made of metal.

Preferably, the baffle is made of aluminum and its surface is plated with nickel.

Preferably, the driving element can also control the baffle to move in the circumferential direction and/or to move up and down along the inner wall of the reaction chamber.

Preferably, the driving element can record the position data of the baffle.

Furthermore, the present invention also provides a plasma processing equipment, which includes a reaction chamber and a lining located in the reaction chamber, and also includes a radio frequency adjustment device in any of the above embodiments.

Preferably, the reaction chamber has a film transfer port, and the baffle can at least partially block the film transfer port by moving.

Furthermore, the present invention also provides a radio frequency electric field adjustment method, which includes the following steps: initializing the position of the baffle in any of the above radio frequency adjustment devices; introducing reactive gases into the plasma processing equipment; applying a radio frequency electric field to stimulate the plasma reaction The substrate in the cavity is etched; and the baffle is adjusted according to the surface uniformity of the etched substrate.

Preferably, when adjusting the position of the baffle, the driving element can record the position data of the baffle for forming a visual image in an external operating system.

Preferably, it also includes the following steps: For a position where the surface etching depth of the etched substrate is shallower, the baffle closest to the position is raised; and for a position where the surface etching depth of the etched substrate is deep, the baffle closest to the position is lowered.

The advantage of the present invention is that the present invention provides a radio frequency adjustment device, a plasma processing equipment and a radio frequency electric field adjustment method, which can adjust the capacitance of the radio frequency circuit inside the plasma processing equipment to adjust the uniformity of the radio frequency electric field, effectively making up for the problems caused by the reaction cavity. The uneven radio frequency electric field generated by the opening of the chip transfer port on the side wall or the asymmetry of the components inside the reaction chamber makes the formed plasma more uniform and stable, ensuring the processing yield of the substrate surface.

110:Reaction chamber

111: Film transfer port

120: Lining

130:Baffle

131: Drive components

140:Electrostatic chuck

160:Gas nozzle

170:Plasma confinement ring

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the conventional technology, the drawings needed to be used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those with ordinary knowledge in the technical field to which the present invention belongs, other drawings can be obtained based on these drawings without making any progressive changes.

FIG. 1 shows a schematic structural diagram of a plasma processing equipment; FIG. 2 shows a partial top view of a plasma processing equipment; and FIG. 3 shows a schematic structural diagram of a baffle of a radio frequency adjustment device according to an embodiment.

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those with ordinary skill in the technical field to which the present invention belongs without making any progressive changes shall fall within the scope of protection of the present invention.

FIG. 1 shows a schematic structural diagram of a plasma processing equipment, including a evacuable reaction chamber 110 surrounded by metal materials. The reaction chamber 110 is used for processing substrates. The inside of the reaction chamber 110 includes an electrostatic chuck 140, which is used to support the substrate and control processing factors that affect the substrate, such as temperature and electric field of the substrate. The electrostatic chuck 140 is equipped with a temperature control device for controlling the temperature of the upper substrate. A DC electrode is also provided inside the electrostatic chuck 140. The DC electrode is used between the back side of the substrate and the bearing surface of the electrostatic chuck 140. Generate DC adsorption to achieve fixation to the substrate. A plasma confinement ring 170 is provided around the electrostatic chuck 140 and is located between the electrostatic chuck 140 and the side wall of the reaction chamber 110 to confine the plasma in the reaction area while allowing gas to pass; it is provided below the plasma confinement ring 170 There is a grounding ring, which is used to provide an electric field shield to avoid plasma leakage. A gas nozzle 160 is provided at the top of the reaction chamber 110 for introducing the reaction gas. A radio frequency power supply usually applies a radio frequency signal to the electrostatic chuck 140 or the gas nozzle 160. The radio frequency signal forms a radio frequency electric field in the reaction chamber 110 for excitation. The plasma, in some embodiments, is also provided with a bias radio frequency power source coupled to the electrostatic chuck 140 to control the bombardment direction of the plasma. The radio frequency adjustment device disclosed in the present invention can be used in the plasma processing equipment as shown in Figure 1.

As shown in Figure 1, when the plasma is etching, a certain amount of corrosion will occur on the side wall of the reaction chamber 110. A small amount of corrosion will cause the side wall to produce particle contaminants that can fall off, destroying the etching uniformity of the surface of the substrate. It will affect the performance of integrated circuits, and severe corrosion will shorten the service life of the reaction chamber. In order to avoid this situation, an inner lining 120 is provided between the generated plasma and the side wall of the reaction chamber 110. It is also made of metal. In some embodiments, the same material as aluminum as the side wall of the reaction chamber 110 can be selected. , a corrosion-resistant coating can be evaporated on it. The lining 120 overlaps the upper edge of the side wall of the reaction chamber 110. Except for the upper edge contact, the two usually maintain a certain gap in other areas. Therefore, according to the skin principle, when the radio frequency signal flows through the side wall of the reaction chamber 110, there will be Pass along the surface of the liner 120 and incorporate the liner 120 into the radio frequency circuit. If the liner 120 is damaged due to long-term plasma bombardment, the liner 120 is easier to replace than the side wall of the reaction chamber 110 . However, although in order to maintain the reaction chamber 110 internal radio frequency electric field is uniformly distributed in space, but if different components are designed and manufactured into symmetrical structures as much as possible, such as the annular lining 120, there will still be situations where the internal components destroy the symmetry. If a chip transfer port 111 is provided on the reaction chamber 110 and/or the liner 120 in order to transfer substrates in and out, the chip transfer port 111 will create gaps in the radio frequency signals propagating along the surface compared with other locations. , which in turn affects the morphology of the plasma near it, causing a deviation in the etching rate of the substrate.

In one embodiment of the present invention, a baffle 130 that is not in contact with the reaction chamber 110 and the lining 120 is provided. The material of the baffle 130 can be a metal material or a semiconductor material. In some embodiments, , the material of the baffle is aluminum, and the surface is plated with nickel. The capacitance of the radio frequency circuit is calculated according to the formula: C=εS/d; the lining 120 and the side wall of the reaction chamber 110 are regarded as a flat capacitor, where the relative area of the two is S, the distance between them is d, and the dielectric coefficient of the baffle 130 is regarded as ε.

The baffle 130 can move along the side wall through the driving element 131. In some embodiments, the baffle 130 can move up and down to at least partially cover the film transfer port 111 on the side wall of the reaction chamber 110. Because the existence of the film transfer port 111 makes the S value here smaller, and by covering this place with the baffle 130, the overall reduced capacitance value can be compensated by increasing ε, thereby achieving the effect of adjusting the radio frequency electric field.

As shown in Figure 3, in some embodiments, the baffle 130 can be a concave plate with a gap in the middle, and the gap corresponds to the film transfer port 111. This is suitable for situations where the baffle 130 is relatively high and still blocks the film transfer port 111 even if it drops to the lowest point. , when it is necessary to transfer the film, the baffle 130 is lowered so as not to block the passage of the film. When it is necessary to adjust, the baffle 130 is raised, and the concave plate can further improve the effectiveness of inserting between the side wall of the reaction chamber 110 and the lining 120 area to achieve a greater adjustment effect. Correspondingly, corresponding shape compensation can be set on the opposite side of the concave shape of the baffle 130 to achieve overall symmetry of the radio frequency electric field. In other embodiments, the driving element 131 can control the baffle 130 to rotate in the circumferential direction. The baffle 130 is a curved plate with the same curvature as the side wall of the reaction chamber 110. When the film needs to be transferred, the baffle 130 It is rotated away from the position of the film transfer port 111 and does not block the film transfer channel. When adjustment is required, the baffle 130 rotates back to the position of the film transfer port 111 and adjusts the overlapping area to adjust the balance between the radio frequency electric field here and other positions in the reaction chamber 110 .

As shown in FIG. 2 , which is another embodiment of the present invention, the baffle 130 is an annular plate, which is divided into four parts along the circumferential direction. The up and down movement can be controlled respectively by the driving element 131 , and the baffle 130 can be controlled by the driving element 131 . The integral baffle 130 is controlled to rotate along the circumference. In other embodiments, the baffle 130 can be divided into other numbers of sub-arc plates according to actual conditions, such as two or five. The size of each arc plate does not need to be the same, and can be different in size in the circumferential direction. Can be different sizes in upper and lower heights. In this way, a more flexible control method can be used when adjusting the radio frequency electric field. For example, in addition to changing the position of the baffle 130 according to the film transfer port 111 on the side wall of the reaction chamber 110, the position of the baffle 130 can also be changed according to other asymmetric components inside the reaction chamber 110. Changing the position of the baffle 130 serves the purpose of comprehensive adjustment.

In other embodiments, the driving element 131 can record the position data of the baffle 130. For example, starting from the beginning, the position change of each movement thereafter, including the rotation or elevation or lowering of the baffle 130, will be transmitted through the communication module. The external human-computer interaction device inserted into the reaction chamber 110 forms a visual graphical interface on the display screen of the device to instantly display the changes of the current internal baffle 130 of the reaction chamber 110, which is more conducive to integrating the internal information of the reaction chamber 110. The physical appearance is used to initially analyze the next movement plan of the baffle 130 .

Preferably, the present invention also provides a plasma processing equipment, which may be an inductively coupled plasma processing equipment or a capacitively coupled plasma processing equipment, and may not be limited to the above two types of plasma processing equipment. The processing equipment includes a reaction of metal. Chamber 110, metal lining 120, and any one of the above radio frequency adjustment devices located between the side wall of the reaction chamber 110 and the lining 120. The driving element 131 controls the movement of the baffle 130 to adjust the capacitance in the radio frequency circuit to achieve the purpose of adjusting the radio frequency electric field. A uniform and symmetrical radio frequency electric field can make plasma etching more uniform.

Preferably, the present invention also provides a radio frequency electric field adjustment method, which includes the following steps: initializing the position of the baffle 130 in any of the above radio frequency adjustment devices, and moving the baffle 130 to a certain position based on the analysis of the actual situation. For example, first move to the vicinity of the film transfer port 111 and partially block the film transfer port 111, introduce the reaction gas, apply a radio frequency electric field to excite the plasma, and etch the surface of the sample substrate, and analyze the surface of the substrate after the etching is completed. The morphology of the reaction chamber 110 is used to indirectly analyze the distribution of the radio frequency electric field in the reaction chamber 110. According to the analysis results, the baffle 130 is adjusted again and the reaction process is repeated until the etching results meet the requirements. The position of the baffle 130 at this time is recorded as a reference for subsequent reactions. Commonly used configurations. In some embodiments, the specific analysis process includes, for a position where the surface etching depth of the etched substrate is shallow, raising the baffle 130 closest to the position in the reaction chamber 110 to increase the capacitance there and improve the For the position where the etching depth of the surface of the etched substrate is deeper, lower the baffle 130 closest to the position to reduce the capacitance there and reduce the reaction rate there. In some embodiments, the movement of the baffle 130 is operated through a visual image operation interface. During each analysis, in addition to referring to the etching situation of the sample substrate, the baffle can also be analyzed based on the baffle position data returned by the driving element 131. The positional relationship between the plate 130 and other components in the reaction chamber 110 is combined to determine the next adjustment of the position of the baffle 130. In this way, the number of times to find the most suitable position can be reduced and the adjustment efficiency can be improved.

Although the content of the present invention has been described in detail through the above preferred embodiments, it should be recognized that the above description should not be considered as limiting the present invention. Various modifications and substitutions of the present invention will be apparent to those with ordinary skill in the technical field to which the present invention pertains after reading the above content. Therefore, the protection scope of the present invention should be limited by the appended patent application scope.

110:Reaction chamber

111: Film transfer port

120: Lining

130:Baffle

131: Drive components

140:Electrostatic chuck

160:Gas nozzle

170:Plasma confinement ring

Claims (13)

A radio frequency adjustment device is located between the inner wall and the inner lining of a reaction chamber of a plasma processing equipment that can flow through radio frequency, and is used to adjust the distribution of the radio frequency electric field. It includes: located on the inner wall and inner lining of the reaction chamber. A baffle between the linings and not in contact with the two; and a driving element located in the reaction chamber, the driving element is fixedly connected to the baffle, and is used for the baffle to move along the inner wall of the reaction chamber to change the The capacitance distribution between the inner wall and lining of the reaction chamber. The radio frequency adjustment device according to claim 1, wherein the baffle is annular and is divided into at least two arc-shaped plates in the circumferential direction of the ring, and the driving element controls the at least two arc-shaped plates respectively. sports. The radio frequency adjustment device according to claim 2, wherein at least two of the arc-shaped plates have different heights. The radio frequency adjustment device according to claim 2, wherein the baffle is made of semiconductor. The radio frequency adjustment device according to claim 2, wherein the baffle is made of metal. The radio frequency adjustment device according to claim 5, wherein the baffle is made of aluminum and its surface is plated with nickel. The radio frequency adjustment device as claimed in claim 1, wherein the driving element controls the baffle to move in a circumferential direction and/or to move up and down along the inner wall of the reaction chamber. The radio frequency adjustment device as claimed in claim 7, wherein the driving element records a position data of the baffle. A plasma processing equipment includes a reaction chamber and a lining located in the reaction chamber, which also includes any radio frequency adjustment device as described in claims 1-8. The plasma processing equipment of claim 9, wherein the reaction chamber is provided with a film transfer port, and the baffle can at least partially block the film transfer port by moving. A radio frequency electric field adjustment method, which includes the following steps: initializing the position of the baffle in any radio frequency adjustment device as described in claim 1-8; A reactive gas is introduced into the plasma processing equipment; a radio frequency electric field is applied to excite the plasma to etch a substrate in the reaction chamber; and the baffle is adjusted according to the surface uniformity of the etched substrate. The radio frequency electric field adjustment method as claimed in claim 11, wherein when adjusting the position of the baffle, the driving element records the position data of the baffle for forming a visual image in an external operating system. The radio frequency electric field adjustment method as described in claim 11, further comprising the following steps: for the position where the surface etching depth of the substrate is shallower after etching, raising the baffle closest to the position; and for the position after etching, Where the surface of the substrate is etched to a deeper depth, the baffle closest to that location is lowered.