TW202123782A - Semiconductor processing equipment - Google Patents

Abstract

The invention relates to a semiconductor processing equipment. In an embodiment of the invention, the semiconductor processing equipment comprises a reaction chamber, in which a base is arranged for carrying a workpiece to be processed; a first plasma generation chamber connected to the reaction chamber for providing an ion beam to the workpiece to be processed along a first direction; and a second plasma generating chamber which is connected to the reaction chamber. A distance between an outlet of the second plasma generation chamber and the base is larger than a predetermined distance, so as to provide free radicals to the workpiece to be processed along a second direction, wherein the first direction and the second direction are at a certain angle.

Description

Semiconductor processing equipment

The present invention generally relates to the field of semiconductors, and more particularly to a semiconductor processing equipment.

The third-generation semiconductor materials represented by silicon carbide (SiC) are rapidly emerging. With its excellent characteristics, SiC materials can be used in occasions where traditional materials such as Si, GaAs, and InP are difficult to handle, bringing breakthroughs in device performance. In the widely used SiC etching process, it is necessary to increase the plasma density to obtain a high etching rate.

However, high-density plasma has a heating effect on SiC materials, and its heat source comes from three aspects: one is ion bombardment heating, the other is chemical reaction heat, and the third is radiant heat. The above-mentioned heating effect of the high-density plasma will disadvantageously lead to a rapid increase in the surface temperature of the wafer, destruction of the bonding structure, and ultimately the termination of the production process. Therefore, in the prior art, there is a contradiction between plasma density and temperature, which makes it difficult for the prior art to achieve a balance between high etching rate and low wafer temperature.

The invention discloses a semiconductor processing equipment to solve the problems in the prior art, so as to realize high etching rate and low wafer temperature at the same time, and realize flexible control of the etching process.

According to an embodiment of the present invention, a semiconductor processing equipment is disclosed. The semiconductor processing equipment includes a reaction chamber in which a susceptor for supporting a workpiece to be processed is provided; and a first plasma generation chamber reacts with the reaction chamber. The chamber is communicated and arranged to provide an ion beam to the workpiece to be processed along a first direction; a second plasma generation chamber, the second medium cylinder is communicated with the reaction chamber, and the second plasma is generated The distance between an outlet of the cavity and the base is greater than a preset distance, so as to provide free radicals to the workpiece to be processed along a second direction; wherein the first direction and the second direction are at a certain angle.

According to an embodiment of the present invention, the semiconductor processing equipment further includes a vacuum system connected to the reaction chamber and disposed opposite to the second plasma generation chamber, wherein the vacuum system is configured to cause the The free radicals accelerate to the workpiece to be processed.

According to an embodiment of the present invention, the base is coupled to a bias power source to attract the ion beam to accelerate movement toward the workpiece to be processed in the first direction.

According to an embodiment of the present invention, the frequency of the bias power supply is 0.4 MHz-13.56 MHz.

According to an embodiment of the present invention, the first plasma generation chamber includes a filter grid coupled to a DC bias power source, so that the ion beam accelerates toward the workpiece to be processed in the first direction.

According to an embodiment of the present invention, the minimum distance between the filter grid and the base is 10 mm-100 mm.

According to an embodiment of the present invention, the preset distance range is 60 mm-300 mm.

According to an embodiment of the present invention, the predetermined distance is 200 mm.

According to an embodiment of the present invention, the first direction and the second direction form an angle of 90°.

According to an embodiment of the present invention, the second direction is parallel to the surface of the workpiece to be processed.

According to an embodiment of the present invention, the first plasma generation chamber includes: a first dielectric cylinder and a first induction coil arranged around the first dielectric cylinder, the first dielectric cylinder axially parallel to the first direction.

According to an embodiment of the present invention, the first medium cylinder is coupled to a first gas transport module, the first gas transport module is configured to provide a first reaction gas to the first medium cylinder, the first The induction coil is coupled to a first radio frequency power supply via a first matching circuit.

According to an embodiment of the present invention, the second plasma generation chamber includes: a second dielectric cylinder and a second induction coil arranged around the second dielectric cylinder, and the second dielectric cylinder axially corresponds to the second direction parallel.

According to an embodiment of the present invention, the second medium cylinder is coupled to a second gas transport module, the second gas transport module is configured to provide a second reaction gas to the second medium cylinder, and the second induction The coil is coupled to a second radio frequency power supply via a second matching circuit.

According to an embodiment of the present invention, the shape of the cross-section of the second medium cylinder along the second direction is configured to control the free radical to cover the area of the workpiece to be processed.

According to an embodiment of the present invention, the shape of the cross-section is a rectangle, and the length of the long side of the rectangle is configured to control the free radical to cover the area of the workpiece to be processed.

According to an embodiment of the present invention, the workpiece to be processed includes a SiC semiconductor wafer.

The present invention uses two independent plasma sources to generate ions and free radicals required for the etching of the workpiece to be processed, which can make the ion density and free radical density independently controllable, breaking through the ion density and free radicals in a single plasma generation source The ratio of density cures the limitation caused by the etching rate of the workpiece to be processed, especially such as SiC semiconductor wafer. Moreover, since the plasma source that generates ions in the present invention does not directly contact the wafer, and the plasma source that generates free radicals is a remote plasma source, the plasma radiation heating effect of two independent plasma sources will be obvious Reduce, thereby effectively reducing the surface temperature of the wafer.

The following disclosure provides many different embodiments or examples of different components for implementing the disclosure. Specific examples of components and configurations are described below to simplify the disclosure. Of course, these are only examples and are not intended to be limiting. For example, in the following description, a first member formed on or on a second member may include an embodiment in which the first member and the second member are formed in direct contact, and may also include additional members therein An embodiment that can be formed between the first member and the second member so that the first member and the second member may not directly contact. In addition, the present disclosure may repeat reference numbers and/or letters in each example. This repetition is for the purpose of simplification and clarity and does not in itself indicate the relationship between the various embodiments and/or configurations discussed.

In addition, for ease of description, spatially relative terms such as "below", "below", "below", "above", "upper" and the like can be used herein to describe one element or component and another(s) The relationship between components or components is illustrated in the figure. Spatial relative terms are intended to cover different orientations of devices in use or operation other than those depicted in the figures. The device can be oriented in other ways (rotated by 90 degrees or in other orientations) and therefore the spatial relative descriptors used in this article can also be interpreted.

Although the numerical ranges and parameters stated in the broad scope of this disclosure are approximate values, the numerical values stated in the specific examples should be reported as accurately as possible. However, any value inherently contains certain errors inevitably due to the standard deviation seen in the respective test measurement. Furthermore, as used herein, the term "about" generally means within 10%, 5%, 1%, or 0.5% of a given value or range. Alternatively, the term "approximately" means within one acceptable standard error of the mean when considered by a general technician of the technology. Except in the operation/working example, or unless explicitly specified in other ways, such as the total numerical range of the quantity of materials disclosed in this article, the duration of time, temperature, operating conditions, the ratio of quantities and the like, Quantities, values and percentages should be understood as modified by the term "about" in all examples. Correspondingly, unless otherwise indicated, the numerical parameters stated in the scope of this disclosure and the accompanying invention application are approximate values that can be changed as needed. At the very least, each numerical parameter should be explained at least in view of the number of significant digits reported and by applying ordinary rounding techniques. Ranges can be expressed herein as from one endpoint to the other or between two endpoints. All ranges disclosed herein include endpoints, unless otherwise specified.

Figure 1 shows a device (10) according to an embodiment of the invention. The device (10) may include a reaction chamber (100), a first plasma generation chamber (601), and a second plasma generation chamber (602). The first plasma generation chamber (601) is connected to the reaction chamber (100), and is used to provide ion beams to the workpiece to be processed along the first direction. The second plasma generation chamber (602) is connected to the reaction chamber (100). In an embodiment, the reaction chamber (100) may be further configured as a vacuum reaction chamber. The lower part of the reaction chamber (100) may include a susceptor (503) to carry and/or hold the workpiece to be processed, and the workpiece to be processed may be (but not limited to) a semiconductor wafer. An outlet is provided on one side of the second plasma generating chamber (602) adjacent to the reaction chamber (100). The second plasma generation chamber (602) communicates with the reaction chamber (100) through the outlet, so as to provide free radicals to the workpiece to be processed in the second direction. The distance between the outlet and the susceptor can be set to be greater than a preset distance, so that the concentration of ions and electrons with a limited lifespan after attenuation through the long path of the preset distance is much lower than the concentration of free radicals, so that those reaching the surface of the workpiece to be processed Mainly neutral gases and active free radicals. Preferably, the preset distance may be greater than 200 mm.

The present invention uses two independent plasma sources of the first plasma generation chamber (601) and the second plasma generation chamber (602) to respectively generate ions and free radicals required for etching the workpiece to be processed, which can make the ion density and The free radical density is independently controllable, which breaks through the limitation caused by the curing rate of the workpiece to be processed, especially the etching rate of the SiC semiconductor wafer, caused by the ratio between the ion density and the free radical density in a single plasma generation source. Moreover, because the plasma source for generating ions in the first plasma generating chamber (601) in the present invention does not directly contact the wafer, and the plasma source for generating radicals in the second plasma generating chamber (602) is remote plasma. Therefore, the plasma radiation heating effect of the two independent plasma sources will be significantly reduced, thereby effectively reducing the surface temperature of the workpiece to be processed.

In an embodiment, the base (503) may be a mechanical chuck, and mechanically supports and/or holds the workpiece to be processed. In another embodiment, the base (503) may be an electrostatic adsorption chuck (ESC, ElectroStatic Chuck) to carry and/or hold the workpiece to be processed by electrostatic adsorption. The base (503) can be coupled to a bias power supply (505) via a matcher (504) to attract the ion beam to accelerate movement toward the workpiece to be processed in the first direction. Preferably, the bias power supply (505) is a radio frequency bias power supply (505), and the radio frequency power frequency generated by the radio frequency bias power supply may be 0.4 MHz-13.56 MHz.

Above the reaction chamber (100), the first plasma generation chamber (601) may include a first dielectric cylinder (104) and a first induction coil (103) arranged around the first dielectric cylinder (104). The first medium cylinder (104) contains the first reaction gas. The first induction coil (103) is coupled to the first radio frequency power supply (101). Preferably, the first induction coil (103) can be coupled to the first radio frequency power supply (101) via the first matching circuit (102). The power source frequency of the first radio frequency power supply (101) can be configured to be 0.4 MHz-60 MHz. In an embodiment, the first medium cylinder (104) may be composed of materials such as quartz or ceramics. The first reaction gas may be an inert gas, such as (but not limited to) argon (Ar). Preferably, a first gas transport module (401) may be further provided to provide the first reaction gas into the first medium cylinder (104).

When the first radio frequency power supply (101) is turned on, the first induction coil (103) is excited to generate an electromagnetic field, which can be coupled to the first reaction gas through the first dielectric cylinder (104) to generate a first plasma containing ions and electrons . The ionized first reaction gas can enter the reaction chamber (100) through the outlet of the first medium cylinder (104) and the opening in the upper part of the reaction chamber (100) under the action of external force such as gravity. A medium cylinder (104) moves in the first axial direction toward the workpiece to be processed. However, the axial direction of the first medium cylinder (104) may not be parallel to the first direction. The first direction may be perpendicular to the surface of the workpiece to be processed or not perpendicular to the surface of the workpiece to be processed. Preferably, when the first direction is perpendicular to the surface of the workpiece to be processed, the collimation and uniformity of the distribution of the first reaction gas on the surface of the workpiece to be processed can be improved.

The first plasma generation chamber (601) may include a filter grid (302). In one embodiment, the filter grid (302) is arranged at the lower part of the first medium cylinder (104). The DC bias power supply (301) provides a positive bias to the filter grid (302), so that the ion beam in the first ionized reaction gas is stripped from the plasma sheath and passes through the filter grid (302) along the first direction It accelerates toward the workpiece to be processed, and makes the electrons in the ionized first reaction gas be suppressed by the filter grid (302) and cannot pass through the filter grid (302).

Preferably, the filter grid (302) can include a grid with grid holes, and can be made of materials such as molybdenum metal. The aperture of the grid holes can be configured to be 0.5-2 mm, and the DC positive bias voltage can be configured to be 25-100 V. When the thickness of the plasma sheath is generally 1 mm, it is beneficial to configure the aperture of the grid hole of the filter grid (302) to be less than 2 mm, because when the aperture of the grid hole is smaller than this value, it can further ensure that only ions can Go through the filter grid (302).

Figure 2 shows a top view of the structure of the first medium cylinder (104) and the filter grid (302), wherein the first medium cylinder (104) has a cylindrical cross-section, and its inner diameter can be configured to be no smaller than the diameter of the base (503). In an embodiment, the distance between the base (503) and the filter grid (302) may be 10-100 mm.

Figure 3 shows the structural side view of the filter grid (302), where the thickness H1 of the filter grid (302) can be 0.5-5 mm, the radius R of the grid hole can be 0.25-1 mm, and the material can be molybdenum, which has a high melting point and is resistant to Corroded metal materials.

Referring to Fig. 1, on one side of the reaction chamber (100), a second plasma generation chamber (602) is provided. The second plasma generation chamber (602) may include a second dielectric cylinder (204) and a second induction coil (203) arranged around the second dielectric cylinder (204). The second medium cylinder (204) contains the second reaction gas. The second induction coil (203) is coupled to the second radio frequency power supply (201). Preferably, the second induction coil (203) can be coupled to the second radio frequency power supply (201) via the second matching circuit (202). The frequency of the power source of the second radio frequency power supply (201) can be configured to be 0.4 MHz-60 MHz. When the second radio frequency power supply (201) is turned on, the second induction coil (203) is excited to generate an electromagnetic field, which can be coupled to the second reaction gas through the second dielectric cylinder (204) to generate ions, electrons, neutral gas and In the second plasma of radicals, the radicals may include active fluorine (F) radicals, for example. In an embodiment, the second medium cylinder (204) may be composed of materials such as quartz or ceramics. The second reaction gas may be an inert gas containing free radicals, such as (but not limited to) sulfur hexafluoride (SF6). Preferably, a second gas transport module (402) may be further provided to provide the second reaction gas into the second medium cylinder (204). Outside the second medium cylinder (204), a second induction coil (203) is provided.

Still referring to Figure 1, on the other side of the reaction chamber (100), a vacuum system (701) is provided. The vacuum system (701) draws vacuum or exhausts gas from the reaction chamber (100) from the other side to Make the ionized second reaction gas enter the reaction chamber (100) through the outlet of the second medium cylinder (204) and the opening on the side of the reaction chamber (100) and along the axis parallel to the second medium cylinder (204) The second direction moves toward the workpiece to be processed. However, the axial direction of the second medium cylinder (204) may not be parallel to the second direction. The second direction may be parallel to the surface of the workpiece to be processed or not parallel to the surface of the workpiece to be processed. Preferably, when the second direction is parallel to the surface of the workpiece to be processed, the radial velocity of free radicals moving on the surface of the workpiece to be processed can be increased.

In a preferred embodiment, the first plasma generating cavity (601) is arranged above the reaction chamber (100), and the second plasma generating cavity (602) is arranged on the side of the reaction chamber (100). At this time, the first direction is perpendicular to the surface of the workpiece to be processed, and the second direction is parallel to the surface of the workpiece to be processed, and the first direction and the second direction form an angle of 90°.

In another embodiment, the first plasma generation chamber (601) may not be located above the reaction chamber (100), and the first direction is not perpendicular to the surface of the workpiece to be processed; similarly, the second plasma generation chamber (602) ) May not be located on the side of the reaction chamber (100), at this time the second direction is not parallel to the surface of the workpiece to be processed. Therefore, the angle between the first direction and the second direction may not be 90°, but a certain angle.

In one embodiment, the vacuum system (701) communicates with the reaction chamber (100) and is arranged opposite to the second medium cylinder (204) to accelerate the free radicals toward the workpiece to be processed. In another embodiment, the vacuum system (701) is not arranged opposite to the second medium cylinder (204), but is arranged at a certain angle.

In an embodiment, the distance between the outlet of the second medium cylinder (204) and the workpiece to be processed may be configured such that the main component of the ionized second reaction gas reaching the surface of the workpiece is only neutral gas. And free radicals, and the ions and electrons therein have a relatively short life. After experiencing the long distance path between the outlet of the second medium cylinder (204) and the workpiece to be processed, the density has decayed to be much lower than that of neutral gas and The concentration of free radicals is therefore negligible. Preferably, the preset distance range between the outlet of the second medium cylinder (204) and the workpiece to be processed may be 60 mm-300 mm. In particular, the preset distance can be configured to be 200 mm. The shape of the cross section (508) at the outlet of the second media cylinder (204) can be configured to control the free radicals covering the area of the workpiece to be processed.

Fig. 4 shows a cross-sectional view viewed from the outlet of the second medium cylinder (204) in the second direction. In this embodiment, the cross-sectional shape of the cross-section (508) is rectangular. However, the cross-sectional shape of the cross-section (508) can also be configured in any shape. The rectangular section has a length (509) inside, and the length (509) can be expressed as L. In addition, the rectangular cross-section has a width (510) inside, and the width (510) can be expressed as W. The internal length L of the rectangular cross-section can determine the coverage area of the plasma in the reaction chamber (100), which provides an effective adjustment means for obtaining the uniformity of the large-area surface plasma density in the reaction chamber (100). Preferably, the internal length L of the rectangular cross-section may be configured to be greater than the diameter of the base (503).

As an embodiment, the workpiece to be processed may be a SiC semiconductor wafer. The ion beam from the ionized first reaction gas enters the reaction chamber (100) simultaneously with the ionized second reaction gas. The ion beam bombards the SiC wafer under the action of gravity or the voltage-biased susceptor (503), breaking the Si-C bond in the SiC wafer, and at the same time fluorine (F) radicals react with Si to produce SiF4 volatile gas. The SiF4 volatile gas is discharged from the reaction chamber (100) under the action of the vacuum system (701).

Preferably, the residence time of the gas on the surface of the workpiece to be processed can be further shortened, so as to reduce the adverse effect on the etching uniformity caused by the excessive residence time of the by-products. As an example, for a workpiece to be processed with a diameter of 200 mm, the residence time should be less than 20 ms, that is, the radial velocity difference of the reaction gas on the surface of the workpiece should be greater than 10 m/s.

By separately composing the ions and free radicals required for the etching of the workpiece to be processed through an ion source and a free radical generating source, the present invention can realize independent control of ion concentration and free radical concentration, making the control of the etching process more flexible.

At the same time, since ions and free radicals are generated by separate ion sources and free radical generating sources, and then contact the workpiece to be processed through the reaction chamber (100), it can effectively prevent the workpiece to be processed from being directly exposed to the plasma generation area. High-density ion beam and high-density free radicals can be obtained to significantly increase the etching rate, and at the same time, the plasma radiation heating is greatly reduced to avoid the debonding of bonds and wafers caused by high temperature during the etching process, thereby increasing the etching rate at the same time Obtain a lower surface temperature of the workpiece to be processed.

The foregoing content summarizes the features of several embodiments, so that those familiar with the art can better understand the aspect of the disclosure. Those familiar with the technology should understand that they can easily use the present disclosure as a basis for designing or modifying other processes and structures for implementing the same purpose and/or achieving the same advantages of the embodiments described herein. Those familiar with this technology should also understand that these equivalent structures do not depart from the spirit and scope of this disclosure, and they can make various changes, substitutions and alterations in this article without departing from the spirit and scope of this disclosure.

10: Equipment 100: reaction chamber 101: The first RF power supply 102: The first matching circuit 103: The first induction coil 104: The first medium cylinder 201: Second RF power supply 202: second matching circuit 203: second induction coil 204: second medium cylinder 301: DC bias power supply 302: filter grid 401: The first gas transport module 402: The second gas transport module 503: Pedestal 504: Matcher 505: Bias power supply 601: The first plasma generation chamber 602: Second Plasma Generation Chamber 701: vacuum system L, 509: Internal length of rectangular section R: grid hole radius W, 510: Internal width of rectangular section

When read in conjunction with the accompanying drawings, the aspect of the present disclosure is best understood from the following detailed description. It should be noted that according to standard practice in the industry, the various components are not drawn to scale. In fact, the size of various components can be increased or decreased arbitrarily for the sake of clarity of the discussion. FIG. 1 is a schematic diagram of a semiconductor processing equipment according to an embodiment of the present invention. FIG. 2 is a top view of the structure of the first media cylinder and the filter grid according to an embodiment of the present invention. Fig. 3 is a structural side view of a filter grid according to an embodiment of the present invention. Fig. 4 is a cross-sectional view of the outlet of the second medium cylinder according to an embodiment of the present invention.

10: Equipment

100: reaction chamber

101: The first RF power supply

102: The first matching circuit

103: The first induction coil

104: The first medium cylinder

201: Second RF power supply

202: second matching circuit

203: second induction coil

204: second medium cylinder

301: DC bias power supply

302: filter grid

401: The first gas transport module

402: The second gas transport module

503: Pedestal

504: Matcher

505: Bias power supply

601: The first plasma generation chamber

602: Second Plasma Generation Chamber

701: vacuum system

Claims (17)

A semiconductor processing equipment, including: A reaction chamber, in which a pedestal for supporting a workpiece to be processed is provided; A first plasma generation chamber, connected to the reaction chamber, for providing an ion beam to the workpiece to be processed along a first direction; A second plasma generation chamber, the second plasma generation chamber is connected with the reaction chamber, and the distance between an outlet of the second plasma generation chamber and the susceptor is greater than a predetermined distance, so as to realize the The second direction provides free radicals to the workpiece to be processed; Wherein, the first direction and the second direction are at a certain angle. The semiconductor processing equipment according to claim 1, wherein the semiconductor processing equipment further comprises a vacuum system which is connected to the reaction chamber and is arranged opposite to the second plasma generation chamber, wherein the vacuum system is It is configured to accelerate the free radicals to the workpiece to be processed. The semiconductor processing equipment according to claim 1, wherein the base is coupled to a bias power source to attract the ion beam to accelerate toward the workpiece to be processed in the first direction. The semiconductor processing equipment according to claim 3, wherein the frequency of the bias power supply is 0.4 MHz-13.56 MHz. The semiconductor processing equipment according to claim 1, wherein the first plasma generation chamber includes a filter grid coupled to a DC bias power supply, so that the ion beam is directed toward the workpiece to be processed along the first direction Speed up movement. The semiconductor processing equipment according to claim 5, wherein the minimum distance between the filter grid and the base is 10 mm-100 mm. The semiconductor processing equipment according to claim 1, wherein the preset distance range is 60 mm-300 mm. The semiconductor processing equipment according to claim 7, wherein the preset distance is 200 mm. The semiconductor processing equipment according to claim 1, wherein the first direction and the second direction form an angle of 90°. The semiconductor processing equipment according to claim 1, wherein the second direction is parallel to the surface of the workpiece to be processed. The semiconductor processing equipment according to claim 1, wherein the first plasma generation chamber includes: A first medium cylinder and a first induction coil arranged around the first medium cylinder, and the axial direction of the first medium cylinder is parallel to the first direction. The semiconductor processing apparatus according to claim 11, wherein the first medium cylinder is coupled to a first gas transport module, and the first gas transport module is configured to provide a first reaction gas to the first medium cylinder , The first induction coil is coupled to a first radio frequency power supply via a first matching circuit. The semiconductor processing equipment according to claim 1, wherein the second plasma generation chamber includes: A second medium cylinder and a second induction coil arranged around the second medium cylinder, and the axial direction of the second medium cylinder is parallel to the second direction. The semiconductor processing apparatus according to claim 1, wherein the second medium cylinder is coupled to a second gas transport module, and the second gas transport module is configured to provide a second reaction gas to the second medium cylinder, The second induction coil is coupled to a second radio frequency power supply via a second matching circuit. The semiconductor processing equipment according to claim 14, wherein the shape of the cross section of the second dielectric cylinder along the second direction is configured to control the area of the workpiece to be processed by the free radicals. The semiconductor processing equipment according to claim 15, wherein the shape of the cross section is a rectangle, and the length of the long side of the rectangle is configured to control the free radical to cover the area of the workpiece to be processed. The semiconductor processing equipment according to claim 1, wherein the workpiece to be processed includes a SiC semiconductor wafer.

Images